Bump version to 2.1.3-mempow.0

# Conflicts:
#	pom.xml

.github/workflows/pr-testing.yml

@@ -0,0 +1,33 @@
+name: PR testing
+
+on:
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  mavenTesting:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Cache local Maven repository
+      uses: actions/cache@v2
+      with:
+        path: ~/.m2/repository
+        key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
+        restore-keys: |
+          ${{ runner.os }}-maven-
+    - name: Set up the Java JDK
+      uses: actions/setup-java@v2
+      with:
+        java-version: '11'
+        distribution: 'adopt'
+
+    - name: Run all tests
+      run: |
+        mvn -B clean test -DskipTests=false --file pom.xml
+        if [ -f "target/site/jacoco/index.html" ]; then echo "Total coverage: $(cat target/site/jacoco/index.html | grep -o 'Total[^%]*%' | grep -o '[0-9]*%')"; fi
+
+    - name: Log coverage percentage
+      run: |
+        if [ ! -f "target/site/jacoco/index.html" ]; then echo "No coverage information available"; fi
+        if [ -f "target/site/jacoco/index.html" ]; then echo "Total coverage: $(cat target/site/jacoco/index.html | grep -o 'Total[^%]*%' | grep -o '[0-9]*%')"; fi

.gitignore

@@ -1,6 +1,8 @@
 /db*
+/lists/
 /bin/
 /target/
+/qortal-backup/
 /log.txt.*
 /arbitrary*
 /Qortal-BTC*
@@ -14,5 +16,15 @@
 /settings.json
 /testnet*
 /settings*.json
-/testchain.json
-/run-testnet.sh
+/testchain*.json
+/run-testnet*.sh
+/.idea
+/qortal.iml
+.DS_Store
+/src/main/resources/resources
+/*.jar
+/run.pid
+/run.log
+/WindowsInstaller/Install Files/qortal.jar
+/*.7z
+/tmp

AutoUpdates.md

@@ -1,5 +1,20 @@
 # Auto Updates
 
+## TL;DR: how-to
+
+* Prepare new release version (see way below for details)
+* Assuming you are in git 'master' branch, at HEAD
+* Shutdown local node if running
+* Build auto-update download: `tools/build-auto-update.sh` - uploads auto-update file into new git branch
+* Restart local node
+* Publish auto-update transaction using *private key* for **non-admin** member of "dev" group:
+	`tools/publish-auto-update.sh non-admin-dev-member-private-key-in-base58`
+* Wait for auto-update `ARBITRARY` transaction to be confirmed into a block
+* Have "dev" group admins 'approve' auto-update using `tools/approve-auto-update.sh`
+	This tool will prompt for *private key* of **admin** of "dev" group
+* A minimum number of admins are required for approval, and a minimum number of blocks must pass also.
+* Nodes will start to download, and apply, the update over the next 20 minutes or so (see CHECK_INTERVAL in AutoUpdate.java)
+
 ## Theory
 * Using a specific git commit (e.g. abcdef123) we produce a determinstic JAR with consistent hash.
 * To avoid issues with over-eager anti-virus / firewalls we obfuscate JAR using very simplistic XOR-based method.
@@ -25,8 +40,8 @@ The same method is used to obfuscate and de-obfuscate:
 
 ## Typical download locations
 The git SHA1 commit hash is used to replace `%s` in various download locations, e.g.:
-* https://github.com/QORT/qortal/raw/%s/qortal.update
-* https://raw.githubusercontent.com@151.101.16.133/QORT/qortal/%s/qortal.update
+* https://github.com/Qortal/qortal/raw/%s/qortal.update
+* https://raw.githubusercontent.com@151.101.16.133/Qortal/qortal/%s/qortal.update
 
 These locations are part of the org.qortal.settings.Settings class and can be overriden in settings.json like:
 ```
@@ -45,4 +60,12 @@ $ java -cp qortal.jar org.qortal.XorUpdate
 usage: XorUpdate <input-file> <output-file>
 $ java -cp qortal.jar org.qortal.XorUpdate qortal.jar qortal.update
 $
-```
+```
+
+## Preparing new release version
+
+* Shutdown local node
+* Modify `pom.xml` and increase version inside `<version>` tag
+* Commit new `pom.xml` and push to github, e.g. `git commit -m 'Bumped to v1.4.2' -- pom.xml; git push`
+* Tag this new commit with same version: `git tag v1.4.2`
+* Push tag up to github: `git push origin v1.4.2`

DATABASE.md

@@ -4,10 +4,10 @@ You can examine your node's database using [HSQLDB's "sqltool"](http://www.hsqld
 It's a good idea to install "rlwrap" (ReadLine wrapper) too as sqltool doesn't support command history/editing.
 
 Typical command line for sqltool would be:
-`rlwrap java -cp ${HSQLDB_JAR}:${SQLTOOL_JAR} org.hsqldb.cmdline.SqlTool --rcFile=${SQLTOOL_RC} qora`
+`rlwrap java -cp ${HSQLDB_JAR}:${SQLTOOL_JAR} org.hsqldb.cmdline.SqlTool --rcFile=${SQLTOOL_RC} qortal`
 
 `${HSQLDB_JAR}` should be set with pathname where Maven downloaded hsqldb, 
-typically `${HOME}/.m2/repository/org/hsqldb/hsqldb/2.5.0/hsqldb-2.5.0.jar`
+typically `${HOME}/.m2/repository/org/hsqldb/hsqldb/2.5.1/hsqldb-2.5.1.jar`
 
 `${SQLTOOL_JAR}` should be set with pathname where Maven downloaded sqltool,
 typically  `${HOME}/.m2/repository/org/hsqldb/sqltool/2.5.0/sqltool-2.5.0.jar`
@@ -25,10 +25,16 @@ Above `url` component `file:db/blockchain` assumes you will call `sqltool` from
 
 Another idea is to assign a shell alias in your `.bashrc` like:
 ```
-export HSQLDB_JAR=${HOME}/.m2/repository/org/hsqldb/hsqldb/2.5.0/hsqldb-2.5.0.jar
+export HSQLDB_JAR=${HOME}/.m2/repository/org/hsqldb/hsqldb/2.5.1/hsqldb-2.5.1.jar
 export SQLTOOL_JAR=${HOME}/.m2/repository/org/hsqldb/sqltool/2.5.0/sqltool-2.5.0.jar
 alias sqltool='rlwrap java -cp ${HSQLDB_JAR}:${SQLTOOL_JAR} org.hsqldb.cmdline.SqlTool --rcFile=${SQLTOOL_RC}'
 ```
 So you can simply type: `sqltool qortal`
 
 Don't forget to use `SHUTDOWN;` before exiting sqltool so that database files are closed cleanly.
+
+## Quick and dirty version
+
+With `sqltool-2.5.0.jar` and `qortal.jar` in current directory, and database in `db/`
+
+`java -cp qortal.jar:sqltool-2.5.0.jar org.hsqldb.cmdline.SqlTool --inlineRc=url=jdbc:hsqldb:file:db/blockchain`

README.md

@@ -9,4 +9,4 @@
 - Create basic *settings.json* file: `echo '{}' > settings.json`
 - Run JAR in same working directory as *settings.json*: `java -jar target/qortal-1.0.jar`
 - Wrap in shell script, add JVM flags, redirection, backgrounding, etc. as necessary.
-- Or use supplied example shell script: *run.sh*
+- Or use supplied example shell script: *start.sh*

TestNets.md

@@ -0,0 +1,69 @@
+# How to build a testnet
+
+## Create testnet blockchain config
+
+- You can begin by copying the mainnet blockchain config `src/main/resources/blockchain.json`
+- Insert `"isTestChain": true,` after the opening `{`
+- Modify testnet genesis block
+
+### Testnet genesis block
+
+- Set `timestamp` to a nearby future value, e.g. 15 mins from 'now'
+	This is to give yourself enough time to set up other testnet nodes
+- Retain the initial `ISSUE_ASSET` transactions!
+- Add `ACCOUNT_FLAGS` transactions with `"andMask": -1, "orMask": 1, "xorMask": 0` to create founders
+- Add at least one `REWARD_SHARE` transaction otherwise no-one can mint initial blocks!
+	You will need to calculate `rewardSharePublicKey` (and private key),
+	or make a new account on mainnet and use self-share key values
+- Add `ACCOUNT_LEVEL` transactions to set initial level of accounts as needed
+- Add `GENESIS` transactions to add QORT/LEGACY_QORA funds to accounts as needed
+
+## Testnet `settings.json`
+
+- Create a new `settings-test.json`
+- Make sure to add `"isTestNet": true,`
+- Make sure to reference testnet blockchain config file: `"blockchainConfig": "testchain.json",`
+- It is a good idea to use a separate database: `"repositoryPath": "db-testnet",`
+- You might also need to add `"bitcoinNet": "TEST3",` and `"litecoinNet": "TEST3",`
+
+## Other nodes
+
+- Copy `testchain.json` and `settings-test.json` to other nodes
+- Alternatively, you can run multiple nodes on the same machine by:
+	* Copying `settings-test.json` to `settings-test-1.json`
+	* Configure different `repositoryPath`
+	* Configure use of different ports:
+		+ `"apiPort": 22391,`
+		+ `"listenPort": 22392,`
+
+## Starting-up
+
+- Start up at least as many nodes as `minBlockchainPeers` (or adjust this value instead)
+- Probably best to perform API call `DELETE /peers/known`
+- Add other nodes via API call `POST /peers <peer-hostname-or-IP>`
+- Add minting private key to node(s) via API call `POST /admin/mintingaccounts <minting-private-key>`
+	This key must have corresponding `REWARD_SHARE` transaction in testnet genesis block
+- Wait for genesis block timestamp to pass
+- A node should mint block 2 approximately 60 seconds after genesis block timestamp
+- Other testnet nodes will sync *as long as there is at least `minBlockchainPeers` peers with an "up-to-date" chain`
+- You can also use API call `POST /admin/forcesync <connected-peer-IP-and-port>` on stuck nodes
+
+## Dealing with stuck chain
+
+Maybe your nodes have been offline and no-one has minted a recent testnet block.
+Your options are:
+
+- Start a new testnet from scratch
+- Fire up your testnet node(s)
+- Force one of your nodes to mint by:
+	+ Set a debugger breakpoint on Settings.getMinBlockchainPeers()
+	+ When breakpoint is hit, change `this.minBlockchainPeers` to zero, then continue
+- Once one of your nodes has minted blocks up to 'now', you can use "forcesync" on the other nodes
+
+## Tools
+
+- `qort` tool, but use `-t` option for default testnet API port (62391)
+- `qort` tool, but first set shell variable: `export BASE_URL=some-node-hostname-or-ip:port`
+- `qort` tool, but prepend with one-time shell variable: `BASE_URL=some-node-hostname-or-ip:port qort ......`
+- `peer-heights`, but use `-t` option, or `BASE_URL` shell variable as above
+

WindowsInstaller/README.md

@@ -12,7 +12,7 @@ configured paths, or create a dummy `D:` drive with the expected layout.
 
 Typical build procedure:
 
-* Overwrite the `qortal.jar` file in `Install-Files\`
+* Place the `qortal.jar` file in `Install-Files\`
 * Open AdvancedInstaller with qortal.aip file
 * If releasing a new version, change version number in:
 	+ "Product Information" side menu

pom.xml

@@ -3,16 +3,20 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>org.qortal</groupId>
 	<artifactId>qortal</artifactId>
-	<version>1.3.9</version>
+	<version>2.1.3-mempow.0</version>
 	<packaging>jar</packaging>
 	<properties>
 		<skipTests>true</skipTests>
-		<bitcoinj.version>0.15.5</bitcoinj.version>
+		<altcoinj.version>bf9fb80</altcoinj.version>
+		<bitcoinj.version>0.15.10</bitcoinj.version>
 		<bouncycastle.version>1.64</bouncycastle.version>
 		<build.timestamp>${maven.build.timestamp}</build.timestamp>
 		<ciyam-at.version>1.3.8</ciyam-at.version>
 		<commons-net.version>3.6</commons-net.version>
 		<commons-text.version>1.8</commons-text.version>
+		<commons-io.version>2.6</commons-io.version>
+		<commons-compress.version>1.21</commons-compress.version>
+		<xz.version>1.9</xz.version>
 		<dagger.version>1.2.2</dagger.version>
 		<guava.version>28.1-jre</guava.version>
 		<hsqldb.version>2.5.1</hsqldb.version>
@@ -199,6 +203,10 @@
 							<pattern>org.qortal.api.model**</pattern>
 							<template>${project.build.sourceDirectory}/org/qortal/data/package-info.java</template>
 						</package>
+						<package>
+							<pattern>org.qortal.api.model.**</pattern>
+							<template>${project.build.sourceDirectory}/org/qortal/data/package-info.java</template>
+						</package>
 					</packages>
 					<outputDirectory>${project.build.directory}/generated-sources/package-info</outputDirectory>
 				</configuration>
@@ -383,6 +391,11 @@
 			<name>project</name>
 			<url>file:${project.basedir}/lib</url>
 		</repository>
+		<!-- jitpack for build-on-demand of altcoinj -->
+		<repository>
+			<id>jitpack.io</id>
+			<url>https://jitpack.io</url>
+		</repository>
 	</repositories>
 	<dependencies>
 		<!-- https://mvnrepository.com/artifact/org.codehaus.mojo/build-helper-maven-plugin -->
@@ -417,17 +430,43 @@
 			<artifactId>bitcoinj-core</artifactId>
 			<version>${bitcoinj.version}</version>
 		</dependency>
+		<!-- For Litecoin, etc. support, requires bitcoinj -->
+		<dependency>
+			<groupId>com.github.jjos2372</groupId>
+			<artifactId>altcoinj</artifactId>
+			<version>${altcoinj.version}</version>
+		</dependency>
 		<!-- Utilities -->
 		<dependency>
 			<groupId>com.googlecode.json-simple</groupId>
 			<artifactId>json-simple</artifactId>
 			<version>1.1.1</version>
 		</dependency>
+		<dependency>
+			<groupId>org.json</groupId>
+			<artifactId>json</artifactId>
+			<version>20210307</version>
+		</dependency>
 		<dependency>
 			<groupId>org.apache.commons</groupId>
 			<artifactId>commons-text</artifactId>
 			<version>${commons-text.version}</version>
 		</dependency>
+		<dependency>
+			<groupId>commons-io</groupId>
+			<artifactId>commons-io</artifactId>
+			<version>${commons-io.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>org.apache.commons</groupId>
+			<artifactId>commons-compress</artifactId>
+			<version>${commons-compress.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>org.tukaani</groupId>
+			<artifactId>xz</artifactId>
+			<version>${xz.version}</version>
+		</dependency>
 		<!--  For bitset/bitmap compression -->
 		<dependency>
 			<groupId>io.druid</groupId>

src/main/java/org/hsqldb/jdbc/HSQLDBPool.java

@@ -21,18 +21,28 @@ public class HSQLDBPool extends JDBCPool {
 	public Connection tryConnection() throws SQLException {
 		for (int i = 0; i < states.length(); i++) {
 			if (states.compareAndSet(i, RefState.available, RefState.allocated)) {
-				return connections[i].getConnection();
+				JDBCPooledConnection pooledConnection = connections[i];
+
+				if (pooledConnection == null)
+					// Probably shutdown situation
+					return null;
+
+				return pooledConnection.getConnection();
 			}
 
 			if (states.compareAndSet(i, RefState.empty, RefState.allocated)) {
 				try {
-					JDBCPooledConnection connection = (JDBCPooledConnection) source.getPooledConnection();
+					JDBCPooledConnection pooledConnection = (JDBCPooledConnection) source.getPooledConnection();
 
-					connection.addConnectionEventListener(this);
-					connection.addStatementEventListener(this);
-					connections[i] = connection;
+					if (pooledConnection == null)
+						// Probably shutdown situation
+						return null;
 
-					return connections[i].getConnection();
+					pooledConnection.addConnectionEventListener(this);
+					pooledConnection.addStatementEventListener(this);
+					connections[i] = pooledConnection;
+
+					return pooledConnection.getConnection();
 				} catch (SQLException e) {
 					states.set(i, RefState.empty);
 				}

src/main/java/org/qortal/RepositoryMaintenance.java

@@ -1,6 +1,7 @@
 package org.qortal;
 
 import java.security.Security;
+import java.util.concurrent.TimeoutException;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -57,10 +58,10 @@ public class RepositoryMaintenance {
 
 		LOGGER.info("Starting repository periodic maintenance. This can take a while...");
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			repository.performPeriodicMaintenance();
+			repository.performPeriodicMaintenance(null);
 
 			LOGGER.info("Repository periodic maintenance completed");
-		} catch (DataException e) {
+		} catch (DataException | TimeoutException e) {
 			LOGGER.error("Repository periodic maintenance failed", e);
 		}
 

src/main/java/org/qortal/api/ApiError.java

@@ -15,7 +15,7 @@ public enum ApiError {
 	// COMMON
 	// UNKNOWN(0, 500),
 	JSON(1, 400),
-	// NO_BALANCE(2, 422),
+	INSUFFICIENT_BALANCE(2, 402),
 	// NOT_YET_RELEASED(3, 422),
 	UNAUTHORIZED(4, 403),
 	REPOSITORY_ISSUE(5, 500),
@@ -126,10 +126,13 @@ public enum ApiError {
 	// Groups
 	GROUP_UNKNOWN(1101, 404),
 
-	// Bitcoin
-	BTC_NETWORK_ISSUE(1201, 500),
-	BTC_BALANCE_ISSUE(1202, 402),
-	BTC_TOO_SOON(1203, 408);
+	// Foreign blockchain
+	FOREIGN_BLOCKCHAIN_NETWORK_ISSUE(1201, 500),
+	FOREIGN_BLOCKCHAIN_BALANCE_ISSUE(1202, 402),
+	FOREIGN_BLOCKCHAIN_TOO_SOON(1203, 408),
+
+	// Trade portal
+	ORDER_SIZE_TOO_SMALL(1300, 402);
 
 	private static final Map<Integer, ApiError> map = stream(ApiError.values()).collect(toMap(apiError -> apiError.code, apiError -> apiError));
 
@@ -157,4 +160,4 @@ public enum ApiError {
 		return this.status;
 	}
 
-}
+}

src/main/java/org/qortal/api/ApiExceptionFactory.java

@@ -16,4 +16,8 @@ public enum ApiExceptionFactory {
 		return createException(request, apiError, null);
 	}
 
+	public ApiException createCustomException(HttpServletRequest request, ApiError apiError, String message) {
+		return new ApiException(apiError.getStatus(), apiError.getCode(), message, null);
+	}
+
 }

src/main/java/org/qortal/api/ApiService.java

@@ -14,6 +14,8 @@ import java.security.SecureRandom;
 import javax.net.ssl.KeyManagerFactory;
 import javax.net.ssl.SSLContext;
 
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 import org.eclipse.jetty.http.HttpVersion;
 import org.eclipse.jetty.rewrite.handler.RedirectPatternRule;
 import org.eclipse.jetty.rewrite.handler.RewriteHandler;
@@ -43,12 +45,15 @@ import org.qortal.api.websocket.ActiveChatsWebSocket;
 import org.qortal.api.websocket.AdminStatusWebSocket;
 import org.qortal.api.websocket.BlocksWebSocket;
 import org.qortal.api.websocket.ChatMessagesWebSocket;
+import org.qortal.api.websocket.PresenceWebSocket;
 import org.qortal.api.websocket.TradeBotWebSocket;
 import org.qortal.api.websocket.TradeOffersWebSocket;
 import org.qortal.settings.Settings;
 
 public class ApiService {
 
+	private static final Logger LOGGER = LogManager.getLogger(ApiService.class);
+
 	private static ApiService instance;
 
 	private final ResourceConfig config;
@@ -200,6 +205,10 @@ public class ApiService {
 			context.addServlet(ChatMessagesWebSocket.class, "/websockets/chat/messages");
 			context.addServlet(TradeOffersWebSocket.class, "/websockets/crosschain/tradeoffers");
 			context.addServlet(TradeBotWebSocket.class, "/websockets/crosschain/tradebot");
+			context.addServlet(PresenceWebSocket.class, "/websockets/presence");
+
+			// Warn about API security if needed
+			this.checkApiSecurity();
 
 			// Start server
 			this.server.start();
@@ -220,4 +229,23 @@ public class ApiService {
 		this.server = null;
 	}
 
+	private void checkApiSecurity() {
+		// Warn about API security if needed
+		boolean allConnectionsAllowed = false;
+		if (Settings.getInstance().isApiKeyDisabled()) {
+			for (String pattern : Settings.getInstance().getApiWhitelist()) {
+				if (pattern.startsWith("0.0.0.0/") || pattern.startsWith("::/") || pattern.endsWith("/0")) {
+					allConnectionsAllowed = true;
+				}
+			}
+
+			if (allConnectionsAllowed) {
+				LOGGER.warn("Warning: API key validation is currently disabled, and the API whitelist " +
+						"is allowing all connections. This can be a security risk.");
+				LOGGER.warn("To fix, set the apiKeyDisabled setting to false, or allow only specific local " +
+						"IP addresses using the apiWhitelist setting.");
+			}
+		}
+	}
+
 }

src/main/java/org/qortal/api/Base58TypeAdapter.java

@@ -2,7 +2,7 @@ package org.qortal.api;
 
 import javax.xml.bind.annotation.adapters.XmlAdapter;
 
-import org.bitcoinj.core.Base58;
+import org.qortal.utils.Base58;
 
 public class Base58TypeAdapter extends XmlAdapter<String, byte[]> {
 

src/main/java/org/qortal/api/Security.java

@@ -12,6 +12,11 @@ public abstract class Security {
 	public static final String API_KEY_HEADER = "X-API-KEY";
 
 	public static void checkApiCallAllowed(HttpServletRequest request) {
+		// If API key checking has been disabled, we will allow the request in all cases
+		boolean isApiKeyDisabled = Settings.getInstance().isApiKeyDisabled();
+		if (isApiKeyDisabled)
+			return;
+
 		String expectedApiKey = Settings.getInstance().getApiKey();
 		String passedApiKey = request.getHeader(API_KEY_HEADER);
 

src/main/java/org/qortal/api/model/BlockMintingInfo.java

@@ -0,0 +1,23 @@
+package org.qortal.api.model;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import java.math.BigDecimal;
+import java.math.BigInteger;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class BlockMintingInfo {
+
+	public byte[] minterPublicKey;
+	public int minterLevel;
+	public int onlineAccountsCount;
+	public BigDecimal maxDistance;
+	public BigInteger keyDistance;
+	public double keyDistanceRatio;
+	public long timestamp;
+	public long timeDelta;
+
+	public BlockMintingInfo() {
+	}
+
+}

src/main/java/org/qortal/api/model/ConnectedPeer.java

@@ -1,61 +1,74 @@
 package org.qortal.api.model;
 
-import javax.xml.bind.annotation.XmlAccessType;
-import javax.xml.bind.annotation.XmlAccessorType;
-
+import io.swagger.v3.oas.annotations.media.Schema;
 import org.qortal.data.network.PeerChainTipData;
 import org.qortal.data.network.PeerData;
 import org.qortal.network.Handshake;
 import org.qortal.network.Peer;
 
-import io.swagger.v3.oas.annotations.media.Schema;
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import java.util.UUID;
+import java.util.concurrent.TimeUnit;
 
 @XmlAccessorType(XmlAccessType.FIELD)
 public class ConnectedPeer {
 
-	public enum Direction {
-		INBOUND,
-		OUTBOUND;
-	}
-	public Direction direction;
-	public Handshake handshakeStatus;
-	public Long lastPing;
-	public Long connectedWhen;
-	public Long peersConnectedWhen;
+    public enum Direction {
+        INBOUND,
+        OUTBOUND;
+    }
 
-	public String address;
-	public String version;
+    public Direction direction;
+    public Handshake handshakeStatus;
+    public Long lastPing;
+    public Long connectedWhen;
+    public Long peersConnectedWhen;
 
-	public String nodeId;
+    public String address;
+    public String version;
 
-	public Integer lastHeight;
-	@Schema(example = "base58")
-	public byte[] lastBlockSignature;
-	public Long lastBlockTimestamp;
+    public String nodeId;
 
-	protected ConnectedPeer() {
-	}
+    public Integer lastHeight;
+    @Schema(example = "base58")
+    public byte[] lastBlockSignature;
+    public Long lastBlockTimestamp;
+    public UUID connectionId;
+    public String age;
 
-	public ConnectedPeer(Peer peer) {
-		this.direction = peer.isOutbound() ? Direction.OUTBOUND : Direction.INBOUND;
-		this.handshakeStatus = peer.getHandshakeStatus();
-		this.lastPing = peer.getLastPing();
+    protected ConnectedPeer() {
+    }
 
-		PeerData peerData = peer.getPeerData();
-		this.connectedWhen = peer.getConnectionTimestamp();
-		this.peersConnectedWhen = peer.getPeersConnectionTimestamp();
+    public ConnectedPeer(Peer peer) {
+        this.direction = peer.isOutbound() ? Direction.OUTBOUND : Direction.INBOUND;
+        this.handshakeStatus = peer.getHandshakeStatus();
+        this.lastPing = peer.getLastPing();
 
-		this.address = peerData.getAddress().toString();
+        PeerData peerData = peer.getPeerData();
+        this.connectedWhen = peer.getConnectionTimestamp();
+        this.peersConnectedWhen = peer.getPeersConnectionTimestamp();
 
-		this.version = peer.getPeersVersionString();
-		this.nodeId = peer.getPeersNodeId();
+        this.address = peerData.getAddress().toString();
 
-		PeerChainTipData peerChainTipData = peer.getChainTipData();
-		if (peerChainTipData != null) {
-			this.lastHeight = peerChainTipData.getLastHeight();
-			this.lastBlockSignature = peerChainTipData.getLastBlockSignature();
-			this.lastBlockTimestamp = peerChainTipData.getLastBlockTimestamp();
-		}
-	}
+        this.version = peer.getPeersVersionString();
+        this.nodeId = peer.getPeersNodeId();
+        this.connectionId = peer.getPeerConnectionId();
+        if (peer.getConnectionEstablishedTime() > 0) {
+            long age = (System.currentTimeMillis() - peer.getConnectionEstablishedTime());
+            long minutes = TimeUnit.MILLISECONDS.toMinutes(age);
+            long seconds = TimeUnit.MILLISECONDS.toSeconds(age) - TimeUnit.MINUTES.toSeconds(minutes);
+            this.age = String.format("%dm %ds", minutes, seconds);
+        } else {
+            this.age = "connecting...";
+        }
+
+        PeerChainTipData peerChainTipData = peer.getChainTipData();
+        if (peerChainTipData != null) {
+            this.lastHeight = peerChainTipData.getLastHeight();
+            this.lastBlockSignature = peerChainTipData.getLastBlockSignature();
+            this.lastBlockTimestamp = peerChainTipData.getLastBlockTimestamp();
+        }
+    }
 
 }

src/main/java/org/qortal/api/model/CrossChainBitcoinP2SHStatus.java

@@ -1,31 +0,0 @@
-package org.qortal.api.model;
-
-import java.math.BigDecimal;
-
-import javax.xml.bind.annotation.XmlAccessType;
-import javax.xml.bind.annotation.XmlAccessorType;
-
-import io.swagger.v3.oas.annotations.media.Schema;
-
-@XmlAccessorType(XmlAccessType.FIELD)
-public class CrossChainBitcoinP2SHStatus {
-
-	@Schema(description = "Bitcoin P2SH address", example = "3CdH27kTpV8dcFHVRYjQ8EEV5FJg9X8pSJ (mainnet), 2fMiRRXVsxhZeyfum9ifybZvaMHbQTmwdZw (testnet)")
-	public String bitcoinP2shAddress;
-
-	@Schema(description = "Bitcoin P2SH balance")
-	public BigDecimal bitcoinP2shBalance;
-
-	@Schema(description = "Can P2SH redeem yet?")
-	public boolean canRedeem;
-
-	@Schema(description = "Can P2SH refund yet?")
-	public boolean canRefund;
-
-	@Schema(description = "Secret extracted by P2SH redeemer")
-	public byte[] secret;
-
-	public CrossChainBitcoinP2SHStatus() {
-	}
-
-}

src/main/java/org/qortal/api/model/CrossChainBitcoinyHTLCStatus.java

@@ -0,0 +1,31 @@
+package org.qortal.api.model;
+
+import java.math.BigDecimal;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class CrossChainBitcoinyHTLCStatus {
+
+	@Schema(description = "P2SH address", example = "3CdH27kTpV8dcFHVRYjQ8EEV5FJg9X8pSJ (mainnet), 2fMiRRXVsxhZeyfum9ifybZvaMHbQTmwdZw (testnet)")
+	public String bitcoinP2shAddress;
+
+	@Schema(description = "P2SH balance")
+	public BigDecimal bitcoinP2shBalance;
+
+	@Schema(description = "Can HTLC redeem yet?")
+	public boolean canRedeem;
+
+	@Schema(description = "Can HTLC refund yet?")
+	public boolean canRefund;
+
+	@Schema(description = "Secret used by HTLC redeemer")
+	public byte[] secret;
+
+	public CrossChainBitcoinyHTLCStatus() {
+	}
+
+}

src/main/java/org/qortal/api/model/CrossChainDualSecretRequest.java

@@ -0,0 +1,29 @@
+package org.qortal.api.model;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class CrossChainDualSecretRequest {
+
+	@Schema(description = "Public key to match AT's trade 'partner'", example = "C6wuddsBV3HzRrXUtezE7P5MoRXp5m3mEDokRDGZB6ry")
+	public byte[] partnerPublicKey;
+
+	@Schema(description = "Qortal AT address")
+	public String atAddress;
+
+	@Schema(description = "secret-A (32 bytes)", example = "FHMzten4he9jZ4HGb4297Utj6F5g2w7serjq2EnAg2s1")
+	public byte[] secretA;
+
+	@Schema(description = "secret-B (32 bytes)", example = "EN2Bgx3BcEMtxFCewmCVSMkfZjVKYhx3KEXC5A21KBGx")
+	public byte[] secretB;
+
+	@Schema(description = "Qortal address for receiving QORT from AT")
+	public String receivingAddress;
+
+	public CrossChainDualSecretRequest() {
+	}
+
+}

src/main/java/org/qortal/api/model/CrossChainOfferSummary.java

@@ -4,7 +4,7 @@ import javax.xml.bind.annotation.XmlAccessType;
 import javax.xml.bind.annotation.XmlAccessorType;
 import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
 
-import org.qortal.crosschain.BTCACCT;
+import org.qortal.crosschain.AcctMode;
 import org.qortal.data.crosschain.CrossChainTradeData;
 
 import io.swagger.v3.oas.annotations.media.Schema;
@@ -16,26 +16,41 @@ public class CrossChainOfferSummary {
 	// Properties
 
 	@Schema(description = "AT's Qortal address")
-	public String qortalAtAddress;
+	private String qortalAtAddress;
 
 	@Schema(description = "AT creator's Qortal address")
-	public String qortalCreator;
+	private String qortalCreator;
+
+	@Schema(description = "AT creator's ephemeral trading key-pair represented as Qortal address")
+	private String qortalCreatorTradeAddress;
 
 	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
 	private long qortAmount;
 
+	@Schema(description = "Bitcoin amount - DEPRECATED: use foreignAmount")
 	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	@Deprecated
 	private long btcAmount;
 
+	@Schema(description = "Foreign blockchain amount")
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	private long foreignAmount;
+
 	@Schema(description = "Suggested trade timeout (minutes)", example = "10080")
 	private int tradeTimeout;
 
-	private BTCACCT.Mode mode;
+	@Schema(description = "Current AT execution mode")
+	private AcctMode mode;
 
 	private long timestamp;
 
+	@Schema(description = "Trade partner's Qortal receiving address")
 	private String partnerQortalReceivingAddress;
 
+	private String foreignBlockchain;
+
+	private String acctName;
+
 	protected CrossChainOfferSummary() {
 		/* For JAXB */
 	}
@@ -43,12 +58,16 @@ public class CrossChainOfferSummary {
 	public CrossChainOfferSummary(CrossChainTradeData crossChainTradeData, long timestamp) {
 		this.qortalAtAddress = crossChainTradeData.qortalAtAddress;
 		this.qortalCreator = crossChainTradeData.qortalCreator;
+		this.qortalCreatorTradeAddress = crossChainTradeData.qortalCreatorTradeAddress;
 		this.qortAmount = crossChainTradeData.qortAmount;
-		this.btcAmount = crossChainTradeData.expectedBitcoin;
+		this.foreignAmount = crossChainTradeData.expectedForeignAmount;
+		this.btcAmount = this.foreignAmount; // Duplicate for deprecated field
 		this.tradeTimeout = crossChainTradeData.tradeTimeout;
 		this.mode = crossChainTradeData.mode;
 		this.timestamp = timestamp;
 		this.partnerQortalReceivingAddress = crossChainTradeData.qortalPartnerReceivingAddress;
+		this.foreignBlockchain = crossChainTradeData.foreignBlockchain;
+		this.acctName = crossChainTradeData.acctName;
 	}
 
 	public String getQortalAtAddress() {
@@ -59,6 +78,10 @@ public class CrossChainOfferSummary {
 		return this.qortalCreator;
 	}
 
+	public String getQortalCreatorTradeAddress() {
+		return this.qortalCreatorTradeAddress;
+	}
+
 	public long getQortAmount() {
 		return this.qortAmount;
 	}
@@ -67,11 +90,15 @@ public class CrossChainOfferSummary {
 		return this.btcAmount;
 	}
 
+	public long getForeignAmount() {
+		return this.foreignAmount;
+	}
+
 	public int getTradeTimeout() {
 		return this.tradeTimeout;
 	}
 
-	public BTCACCT.Mode getMode() {
+	public AcctMode getMode() {
 		return this.mode;
 	}
 
@@ -83,10 +110,18 @@ public class CrossChainOfferSummary {
 		return this.partnerQortalReceivingAddress;
 	}
 
+	public String getForeignBlockchain() {
+		return this.foreignBlockchain;
+	}
+
+	public String getAcctName() {
+		return this.acctName;
+	}
+
 	// For debugging mostly
 
 	public String toString() {
-		return String.format("%s: %s", this.qortalAtAddress, this.mode.name());
+		return String.format("%s: %s", this.qortalAtAddress, this.mode);
 	}
 
 }

src/main/java/org/qortal/api/model/CrossChainSecretRequest.java

@@ -8,17 +8,14 @@ import io.swagger.v3.oas.annotations.media.Schema;
 @XmlAccessorType(XmlAccessType.FIELD)
 public class CrossChainSecretRequest {
 
-	@Schema(description = "Public key to match AT's trade 'partner'", example = "C6wuddsBV3HzRrXUtezE7P5MoRXp5m3mEDokRDGZB6ry")
-	public byte[] partnerPublicKey;
+	@Schema(description = "Private key to match AT's trade 'partner'", example = "C6wuddsBV3HzRrXUtezE7P5MoRXp5m3mEDokRDGZB6ry")
+	public byte[] partnerPrivateKey;
 
 	@Schema(description = "Qortal AT address")
 	public String atAddress;
 
-	@Schema(description = "secret-A (32 bytes)", example = "FHMzten4he9jZ4HGb4297Utj6F5g2w7serjq2EnAg2s1")
-	public byte[] secretA;
-
-	@Schema(description = "secret-B (32 bytes)", example = "EN2Bgx3BcEMtxFCewmCVSMkfZjVKYhx3KEXC5A21KBGx")
-	public byte[] secretB;
+	@Schema(description = "Secret (32 bytes)", example = "FHMzten4he9jZ4HGb4297Utj6F5g2w7serjq2EnAg2s1")
+	public byte[] secret;
 
 	@Schema(description = "Qortal address for receiving QORT from AT")
 	public String receivingAddress;

src/main/java/org/qortal/api/model/CrossChainTradeSummary.java

@@ -6,6 +6,8 @@ import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
 
 import org.qortal.data.crosschain.CrossChainTradeData;
 
+import io.swagger.v3.oas.annotations.media.Schema;
+
 // All properties to be converted to JSON via JAXB
 @XmlAccessorType(XmlAccessType.FIELD)
 public class CrossChainTradeSummary {
@@ -15,9 +17,20 @@ public class CrossChainTradeSummary {
 	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
 	private long qortAmount;
 
+	@Deprecated
+	@Schema(description = "DEPRECATED: use foreignAmount instead")
 	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
 	private long btcAmount;
 
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	private long foreignAmount;
+
+	private String atAddress;
+
+	private String sellerAddress;
+
+	private String buyerReceivingAddress;
+
 	protected CrossChainTradeSummary() {
 		/* For JAXB */
 	}
@@ -25,7 +38,11 @@ public class CrossChainTradeSummary {
 	public CrossChainTradeSummary(CrossChainTradeData crossChainTradeData, long timestamp) {
 		this.tradeTimestamp = timestamp;
 		this.qortAmount = crossChainTradeData.qortAmount;
-		this.btcAmount = crossChainTradeData.expectedBitcoin;
+		this.foreignAmount = crossChainTradeData.expectedForeignAmount;
+		this.btcAmount = this.foreignAmount;
+		this.sellerAddress = crossChainTradeData.qortalCreator;
+		this.buyerReceivingAddress = crossChainTradeData.qortalPartnerReceivingAddress;
+		this.atAddress = crossChainTradeData.qortalAtAddress;
 	}
 
 	public long getTradeTimestamp() {
@@ -40,4 +57,11 @@ public class CrossChainTradeSummary {
 		return this.btcAmount;
 	}
 
+	public long getForeignAmount() { return this.foreignAmount; }
+
+	public String getAtAddress() { return this.atAddress; }
+
+	public String getSellerAddress() { return this.sellerAddress; }
+
+	public String getBuyerReceivingAddressAddress() { return this.buyerReceivingAddress; }
 }

src/main/java/org/qortal/api/model/ListRequest.java

@@ -0,0 +1,18 @@
+package org.qortal.api.model;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import java.util.List;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class ListRequest {
+
+	@Schema(description = "A list of items")
+	public List<String> items;
+
+	public ListRequest() {
+	}
+
+}

src/main/java/org/qortal/api/model/SimpleForeignTransaction.java

@@ -0,0 +1,157 @@
+package org.qortal.api.model;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class SimpleForeignTransaction {
+
+	public static class AddressAmount {
+		public final String address;
+		public final long amount;
+
+		protected AddressAmount() {
+			/* For JAXB */
+			this.address = null;
+			this.amount = 0;
+		}
+
+		public AddressAmount(String address, long amount) {
+			this.address = address;
+			this.amount = amount;
+		}
+	}
+
+	private String txHash;
+	private long timestamp;
+
+	private List<AddressAmount> inputs;
+
+	public static class Output {
+		public final List<String> addresses;
+		public final long amount;
+
+		protected Output() {
+			/* For JAXB */
+			this.addresses = null;
+			this.amount = 0;
+		}
+
+		public Output(List<String> addresses, long amount) {
+			this.addresses = addresses;
+			this.amount = amount;
+		}
+	}
+	private List<Output> outputs;
+
+	private long totalAmount;
+	private long fees;
+
+	private Boolean isSentNotReceived;
+
+	protected SimpleForeignTransaction() {
+		/* For JAXB */
+	}
+
+	private SimpleForeignTransaction(Builder builder) {
+		this.txHash = builder.txHash;
+		this.timestamp = builder.timestamp;
+		this.inputs = Collections.unmodifiableList(builder.inputs);
+		this.outputs = Collections.unmodifiableList(builder.outputs);
+
+		Objects.requireNonNull(this.txHash);
+		if (timestamp <= 0)
+			throw new IllegalArgumentException("timestamp must be positive");
+
+		long totalGrossAmount = this.inputs.stream().map(addressAmount -> addressAmount.amount).reduce(0L, Long::sum);
+		this.totalAmount = this.outputs.stream().map(addressAmount -> addressAmount.amount).reduce(0L, Long::sum);
+
+		this.fees = totalGrossAmount - this.totalAmount;
+
+		this.isSentNotReceived = builder.isSentNotReceived;
+	}
+
+	public String getTxHash() {
+		return this.txHash;
+	}
+
+	public long getTimestamp() {
+		return this.timestamp;
+	}
+
+	public List<AddressAmount> getInputs() {
+		return this.inputs;
+	}
+
+	public List<Output> getOutputs() {
+		return this.outputs;
+	}
+
+	public long getTotalAmount() {
+		return this.totalAmount;
+	}
+
+	public long getFees() {
+		return this.fees;
+	}
+
+	public Boolean isSentNotReceived() {
+		return this.isSentNotReceived;
+	}
+
+	public static class Builder {
+		private String txHash;
+		private long timestamp;
+		private List<AddressAmount> inputs = new ArrayList<>();
+		private List<Output> outputs = new ArrayList<>();
+		private Boolean isSentNotReceived;
+
+		public Builder txHash(String txHash) {
+			this.txHash = Objects.requireNonNull(txHash);
+			return this;
+		}
+
+		public Builder timestamp(long timestamp) {
+			if (timestamp <= 0)
+				throw new IllegalArgumentException("timestamp must be positive");
+
+			this.timestamp = timestamp;
+			return this;
+		}
+
+		public Builder input(String address, long amount) {
+			Objects.requireNonNull(address);
+			if (amount < 0)
+				throw new IllegalArgumentException("amount must be zero or positive");
+
+			AddressAmount input = new AddressAmount(address, amount);
+			inputs.add(input);
+			return this;
+		}
+
+		public Builder output(List<String> addresses, long amount) {
+			Objects.requireNonNull(addresses);
+			if (amount < 0)
+				throw new IllegalArgumentException("amount must be zero or positive");
+
+			Output output = new Output(addresses, amount);
+			outputs.add(output);
+			return this;
+		}
+
+		public Builder isSentNotReceived(Boolean isSentNotReceived) {
+			this.isSentNotReceived = isSentNotReceived;
+			return this;
+		}
+
+		public SimpleForeignTransaction build() {
+			return new SimpleForeignTransaction(this);
+		}
+	}
+
+}

src/main/java/org/qortal/api/model/TradeBotRespondRequest.java

@@ -1,23 +0,0 @@
-package org.qortal.api.model;
-
-import javax.xml.bind.annotation.XmlAccessType;
-import javax.xml.bind.annotation.XmlAccessorType;
-
-import io.swagger.v3.oas.annotations.media.Schema;
-
-@XmlAccessorType(XmlAccessType.FIELD)
-public class TradeBotRespondRequest {
-
-	@Schema(description = "Qortal AT address", example = "Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
-	public String atAddress;
-
-	@Schema(description = "Bitcoin BIP32 extended private key", example = "xprv___________________________________________________________________________________________________________")
-	public String xprv58;
-
-	@Schema(description = "Qortal address for receiving QORT from AT", example = "Qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq")
-	public String receivingAddress;
-
-	public TradeBotRespondRequest() {
-	}
-
-}

src/main/java/org/qortal/api/model/crosschain/BitcoinSendRequest.java

@@ -1,4 +1,4 @@
-package org.qortal.api.model;
+package org.qortal.api.model.crosschain;
 
 import javax.xml.bind.annotation.XmlAccessType;
 import javax.xml.bind.annotation.XmlAccessorType;
@@ -9,16 +9,20 @@ import io.swagger.v3.oas.annotations.media.Schema;
 @XmlAccessorType(XmlAccessType.FIELD)
 public class BitcoinSendRequest {
 
-	@Schema(description = "Bitcoin BIP32 extended private key", example = "tprv8ZgxMBicQKsPdahhFSrCdvC1bsWyzHHZfTneTVqUXN6s1wEtZLwAkZXzFP6TbTVGajEB55L1HYLg2aQMecZLXLre5YJcawpdFG66STVAWPJ")
+	@Schema(description = "Bitcoin BIP32 extended private key", example = "tprv___________________________________________________________________________________________________________")
 	public String xprv58;
 
 	@Schema(description = "Recipient's Bitcoin address ('legacy' P2PKH only)", example = "1BitcoinEaterAddressDontSendf59kuE")
 	public String receivingAddress;
 
-	@Schema(description = "Amount of BTC to send")
+	@Schema(description = "Amount of BTC to send", type = "number")
 	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
 	public long bitcoinAmount;
 
+	@Schema(description = "Transaction fee per byte (optional). Default is 0.00000100 BTC (100 sats) per byte", example = "0.00000100", type = "number")
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	public Long feePerByte;
+
 	public BitcoinSendRequest() {
 	}
 

src/main/java/org/qortal/api/model/crosschain/DogecoinSendRequest.java

@@ -0,0 +1,29 @@
+package org.qortal.api.model.crosschain;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class DogecoinSendRequest {
+
+	@Schema(description = "Dogecoin BIP32 extended private key", example = "tprv___________________________________________________________________________________________________________")
+	public String xprv58;
+
+	@Schema(description = "Recipient's Dogecoin address ('legacy' P2PKH only)", example = "DoGecoinEaterAddressDontSendhLfzKD")
+	public String receivingAddress;
+
+	@Schema(description = "Amount of DOGE to send", type = "number")
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	public long dogecoinAmount;
+
+	@Schema(description = "Transaction fee per byte (optional). Default is 0.00000100 DOGE (100 sats) per byte", example = "0.00000100", type = "number")
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	public Long feePerByte;
+
+	public DogecoinSendRequest() {
+	}
+
+}

src/main/java/org/qortal/api/model/crosschain/LitecoinSendRequest.java

@@ -0,0 +1,29 @@
+package org.qortal.api.model.crosschain;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class LitecoinSendRequest {
+
+	@Schema(description = "Litecoin BIP32 extended private key", example = "tprv___________________________________________________________________________________________________________")
+	public String xprv58;
+
+	@Schema(description = "Recipient's Litecoin address ('legacy' P2PKH only)", example = "LiTecoinEaterAddressDontSendhLfzKD")
+	public String receivingAddress;
+
+	@Schema(description = "Amount of LTC to send", type = "number")
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	public long litecoinAmount;
+
+	@Schema(description = "Transaction fee per byte (optional). Default is 0.00000100 LTC (100 sats) per byte", example = "0.00000100", type = "number")
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	public Long feePerByte;
+
+	public LitecoinSendRequest() {
+	}
+
+}

src/main/java/org/qortal/api/model/crosschain/TradeBotCreateRequest.java

@@ -1,9 +1,11 @@
-package org.qortal.api.model;
+package org.qortal.api.model.crosschain;
 
 import javax.xml.bind.annotation.XmlAccessType;
 import javax.xml.bind.annotation.XmlAccessorType;
 import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
 
+import org.qortal.crosschain.SupportedBlockchain;
+
 import io.swagger.v3.oas.annotations.media.Schema;
 
 @XmlAccessorType(XmlAccessType.FIELD)
@@ -12,22 +14,30 @@ public class TradeBotCreateRequest {
 	@Schema(description = "Trade creator's public key", example = "2zR1WFsbM7akHghqSCYKBPk6LDP8aKiQSRS1FrwoLvoB")
 	public byte[] creatorPublicKey;
 
-	@Schema(description = "QORT amount paid out on successful trade", example = "80.40200000")
+	@Schema(description = "QORT amount paid out on successful trade", example = "80.40000000", type = "number")
 	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
 	public long qortAmount;
 
-	@Schema(description = "QORT amount funding AT, including covering AT execution fees", example = "81")
+	@Schema(description = "QORT amount funding AT, including covering AT execution fees", example = "80.50000000", type = "number")
 	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
 	public long fundingQortAmount;
 
-	@Schema(description = "Bitcoin amount wanted in return", example = "0.00864200")
+	@Deprecated
+	@Schema(description = "Bitcoin amount wanted in return. DEPRECATED: use foreignAmount instead", example = "0.00864200", type = "number", hidden = true)
 	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
-	public long bitcoinAmount;
+	public Long bitcoinAmount;
+
+	@Schema(description = "Foreign blockchain. Note: default (BITCOIN) to be removed in the future", example = "BITCOIN", implementation = SupportedBlockchain.class)
+	public SupportedBlockchain foreignBlockchain;
+
+	@Schema(description = "Foreign blockchain amount wanted in return", example = "0.00864200", type = "number")
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	public Long foreignAmount;
 
 	@Schema(description = "Suggested trade timeout (minutes)", example = "10080")
 	public int tradeTimeout;
 
-	@Schema(description = "Bitcoin address for receiving", example = "1BitcoinEaterAddressDontSendf59kuE")
+	@Schema(description = "Foreign blockchain address for receiving", example = "1BitcoinEaterAddressDontSendf59kuE")
 	public String receivingAddress;
 
 	public TradeBotCreateRequest() {

src/main/java/org/qortal/api/model/crosschain/TradeBotRespondRequest.java

@@ -0,0 +1,29 @@
+package org.qortal.api.model.crosschain;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class TradeBotRespondRequest {
+
+	@Schema(description = "Qortal AT address", example = "Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
+	public String atAddress;
+
+	@Deprecated
+	@Schema(description = "Bitcoin BIP32 extended private key. DEPRECATED: use foreignKey instead", hidden = true,
+			example = "xprv___________________________________________________________________________________________________________")
+	public String xprv58;
+
+	@Schema(description = "Foreign blockchain private key, e.g. BIP32 'm' key for Bitcoin/Litecoin starting with 'xprv'",
+			example = "xprv___________________________________________________________________________________________________________")
+	public String foreignKey;
+
+	@Schema(description = "Qortal address for receiving QORT from AT", example = "Qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq")
+	public String receivingAddress;
+
+	public TradeBotRespondRequest() {
+	}
+
+}

src/main/java/org/qortal/api/resource/AddressesResource.java

@@ -12,6 +12,7 @@ import io.swagger.v3.oas.annotations.tags.Tag;
 
 import java.math.BigDecimal;
 import java.util.ArrayList;
+import java.util.Comparator;
 import java.util.List;
 
 import javax.servlet.http.HttpServletRequest;
@@ -33,11 +34,12 @@ import org.qortal.api.Security;
 import org.qortal.api.model.ApiOnlineAccount;
 import org.qortal.api.model.RewardShareKeyRequest;
 import org.qortal.asset.Asset;
-import org.qortal.controller.Controller;
+import org.qortal.controller.OnlineAccountsManager;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.account.AccountData;
 import org.qortal.data.account.RewardShareData;
 import org.qortal.data.network.OnlineAccountData;
+import org.qortal.data.network.OnlineAccountLevel;
 import org.qortal.data.transaction.PublicizeTransactionData;
 import org.qortal.data.transaction.RewardShareTransactionData;
 import org.qortal.data.transaction.TransactionData;
@@ -158,7 +160,7 @@ public class AddressesResource {
 	)
 	@ApiErrors({ApiError.PUBLIC_KEY_NOT_FOUND, ApiError.REPOSITORY_ISSUE})
 	public List<ApiOnlineAccount> getOnlineAccounts() {
-		List<OnlineAccountData> onlineAccounts = Controller.getInstance().getOnlineAccounts();
+		List<OnlineAccountData> onlineAccounts = OnlineAccountsManager.getInstance().getOnlineAccounts();
 
 		// Map OnlineAccountData entries to OnlineAccount via reward-share data
 		try (final Repository repository = RepositoryManager.getRepository()) {
@@ -180,6 +182,66 @@ public class AddressesResource {
 		}
 	}
 
+	@GET
+	@Path("/online/levels")
+	@Operation(
+			summary = "Return currently 'online' accounts counts, grouped by level",
+			responses = {
+					@ApiResponse(
+							description = "online accounts",
+							content = @Content(mediaType = MediaType.APPLICATION_JSON, array = @ArraySchema(schema = @Schema(implementation = ApiOnlineAccount.class)))
+					)
+			}
+	)
+	@ApiErrors({ApiError.PUBLIC_KEY_NOT_FOUND, ApiError.REPOSITORY_ISSUE})
+	public List<OnlineAccountLevel> getOnlineAccountsByLevel() {
+		List<OnlineAccountData> onlineAccounts = OnlineAccountsManager.getInstance().getOnlineAccounts();
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			List<OnlineAccountLevel> onlineAccountLevels = new ArrayList<>();
+
+			for (OnlineAccountData onlineAccountData : onlineAccounts) {
+				try {
+					final int minterLevel = Account.getRewardShareEffectiveMintingLevel(repository, onlineAccountData.getPublicKey());
+
+					OnlineAccountLevel onlineAccountLevel = onlineAccountLevels.stream()
+							.filter(a -> a.getLevel() == minterLevel)
+							.findFirst().orElse(null);
+
+					// Note: I don't think we can use the level as the List index here because there will be gaps.
+					// So we are forced to manually look up the existing item each time.
+					// There's probably a nice shorthand java way of doing this, but this approach gets the same result.
+
+					if (onlineAccountLevel == null) {
+						// No entry exists for this level yet, so create one
+						onlineAccountLevel = new OnlineAccountLevel(minterLevel, 1);
+						onlineAccountLevels.add(onlineAccountLevel);
+					}
+					else {
+						// Already exists - so increment the count
+						int existingCount = onlineAccountLevel.getCount();
+						onlineAccountLevel.setCount(++existingCount);
+
+						// Then replace the existing item
+						int index = onlineAccountLevels.indexOf(onlineAccountLevel);
+						onlineAccountLevels.set(index, onlineAccountLevel);
+					}
+
+				} catch (DataException e) {
+					continue;
+				}
+			}
+
+			// Sort by level
+			onlineAccountLevels.sort(Comparator.comparingInt(OnlineAccountLevel::getLevel));
+
+			return onlineAccountLevels;
+
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
 	@GET
 	@Path("/balance/{address}")
 	@Operation(

src/main/java/org/qortal/api/resource/AdminResource.java

@@ -22,6 +22,7 @@ import java.time.OffsetDateTime;
 import java.time.ZoneOffset;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.stream.Collectors;
 
@@ -35,6 +36,7 @@ import javax.ws.rs.core.Context;
 import javax.ws.rs.core.MediaType;
 
 import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 import org.apache.logging.log4j.core.LoggerContext;
 import org.apache.logging.log4j.core.appender.RollingFileAppender;
 import org.qortal.account.Account;
@@ -67,6 +69,8 @@ import com.google.common.collect.Lists;
 @Tag(name = "Admin")
 public class AdminResource {
 
+	private static final Logger LOGGER = LogManager.getLogger(AdminResource.class);
+
 	private static final int MAX_LOG_LINES = 500;
 
 	@Context
@@ -459,6 +463,23 @@ public class AdminResource {
 			if (targetHeight <= 0 || targetHeight > Controller.getInstance().getChainHeight())
 				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_HEIGHT);
 
+			// Make sure we're not orphaning as far back as the archived blocks
+			// FUTURE: we could support this by first importing earlier blocks from the archive
+			if (Settings.getInstance().isTopOnly() ||
+				Settings.getInstance().isArchiveEnabled()) {
+
+				try (final Repository repository = RepositoryManager.getRepository()) {
+					// Find the first unarchived block
+					int oldestBlock = repository.getBlockArchiveRepository().getBlockArchiveHeight();
+					// Add some extra blocks just in case we're currently archiving/pruning
+					oldestBlock += 100;
+					if (targetHeight <= oldestBlock) {
+						LOGGER.info("Unable to orphan beyond block {} because it is archived", oldestBlock);
+						throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_HEIGHT);
+					}
+				}
+			}
+
 			if (BlockChain.orphan(targetHeight))
 				return "true";
 			else
@@ -542,19 +563,8 @@ public class AdminResource {
 		Security.checkApiCallAllowed(request);
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
-
-			blockchainLock.lockInterruptibly();
-
-			try {
-				repository.exportNodeLocalData();
-				return "true";
-			} finally {
-				blockchainLock.unlock();
-			}
-		} catch (InterruptedException e) {
-			// We couldn't lock blockchain to perform export
-			return "false";
+			repository.exportNodeLocalData();
+			return "true";
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		}
@@ -564,13 +574,13 @@ public class AdminResource {
 	@Path("/repository/data")
 	@Operation(
 		summary = "Import data into repository.",
-		description = "Imports data from file on local machine. Filename is forced to 'import.script' if apiKey is not set.",
+		description = "Imports data from file on local machine. Filename is forced to 'qortal-backup/TradeBotStates.json' if apiKey is not set.",
 		requestBody = @RequestBody(
 			required = true,
 			content = @Content(
 				mediaType = MediaType.TEXT_PLAIN,
 				schema = @Schema(
-					type = "string", example = "MintingAccounts.script"
+					type = "string", example = "qortal-backup/TradeBotStates.json"
 				)
 			)
 		),
@@ -588,7 +598,7 @@ public class AdminResource {
 
 		// Hard-coded because it's too dangerous to allow user-supplied filenames in weaker security contexts
 		if (Settings.getInstance().getApiKey() == null)
-			filename = "import.script";
+			filename = "qortal-backup/TradeBotStates.json";
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
@@ -600,6 +610,10 @@ public class AdminResource {
 				repository.saveChanges();
 
 				return "true";
+
+			} catch (IOException e) {
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA, e);
+
 			} finally {
 				blockchainLock.unlock();
 			}
@@ -628,25 +642,9 @@ public class AdminResource {
 	public String checkpointRepository() {
 		Security.checkApiCallAllowed(request);
 
-		try (final Repository repository = RepositoryManager.getRepository()) {
-			ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
+		RepositoryManager.setRequestedCheckpoint(Boolean.TRUE);
 
-			blockchainLock.lockInterruptibly();
-
-			try {
-				repository.checkpoint(true);
-				repository.saveChanges();
-
-				return "true";
-			} finally {
-				blockchainLock.unlock();
-			}
-		} catch (InterruptedException e) {
-			// We couldn't lock blockchain to perform checkpoint
-			return "false";
-		} catch (DataException e) {
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
-		}
+		return "true";
 	}
 
 	@POST
@@ -671,14 +669,16 @@ public class AdminResource {
 			blockchainLock.lockInterruptibly();
 
 			try {
-				repository.backup(true);
+				// Timeout if the database isn't ready for backing up after 60 seconds
+				long timeout = 60 * 1000L;
+				repository.backup(true, "backup", timeout);
 				repository.saveChanges();
 
 				return "true";
 			} finally {
 				blockchainLock.unlock();
 			}
-		} catch (InterruptedException e) {
+		} catch (InterruptedException | TimeoutException e) {
 			// We couldn't lock blockchain to perform backup
 			return "false";
 		} catch (DataException e) {
@@ -703,13 +703,15 @@ public class AdminResource {
 			blockchainLock.lockInterruptibly();
 
 			try {
-				repository.performPeriodicMaintenance();
+				// Timeout if the database isn't ready to start after 60 seconds
+				long timeout = 60 * 1000L;
+				repository.performPeriodicMaintenance(timeout);
 			} finally {
 				blockchainLock.unlock();
 			}
 		} catch (InterruptedException e) {
 			// No big deal
-		} catch (DataException e) {
+		} catch (DataException | TimeoutException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		}
 	}

src/main/java/org/qortal/api/resource/BlocksResource.java

@@ -1,5 +1,6 @@
 package org.qortal.api.resource;
 
+import com.google.common.primitives.Ints;
 import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.Parameter;
 import io.swagger.v3.oas.annotations.media.ArraySchema;
@@ -8,7 +9,14 @@ import io.swagger.v3.oas.annotations.media.Schema;
 import io.swagger.v3.oas.annotations.responses.ApiResponse;
 import io.swagger.v3.oas.annotations.tags.Tag;
 
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.math.RoundingMode;
 import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
 
 import javax.servlet.http.HttpServletRequest;
@@ -20,18 +28,25 @@ import javax.ws.rs.QueryParam;
 import javax.ws.rs.core.Context;
 import javax.ws.rs.core.MediaType;
 
+import org.qortal.account.Account;
 import org.qortal.api.ApiError;
 import org.qortal.api.ApiErrors;
 import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.model.BlockMintingInfo;
 import org.qortal.api.model.BlockSignerSummary;
+import org.qortal.block.Block;
+import org.qortal.controller.Controller;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.account.AccountData;
 import org.qortal.data.block.BlockData;
 import org.qortal.data.block.BlockSummaryData;
 import org.qortal.data.transaction.TransactionData;
+import org.qortal.repository.BlockArchiveReader;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryManager;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.block.BlockTransformer;
 import org.qortal.utils.Base58;
 
 @Path("/blocks")
@@ -60,7 +75,8 @@ public class BlocksResource {
 	@ApiErrors({
 		ApiError.INVALID_SIGNATURE, ApiError.BLOCK_UNKNOWN, ApiError.REPOSITORY_ISSUE
 	})
-	public BlockData getBlock(@PathParam("signature") String signature58) {
+	public BlockData getBlock(@PathParam("signature") String signature58,
+							  @QueryParam("includeOnlineSignatures") Boolean includeOnlineSignatures) {
 		// Decode signature
 		byte[] signature;
 		try {
@@ -70,16 +86,80 @@ public class BlocksResource {
 		}
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
+		    // Check the database first
 			BlockData blockData = repository.getBlockRepository().fromSignature(signature);
-			if (blockData == null)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
+			if (blockData != null) {
+				if (includeOnlineSignatures == null || includeOnlineSignatures == false) {
+					blockData.setOnlineAccountsSignatures(null);
+				}
+				return blockData;
+			}
 
-			return blockData;
+            // Not found, so try the block archive
+			blockData = repository.getBlockArchiveRepository().fromSignature(signature);
+			if (blockData != null) {
+				if (includeOnlineSignatures == null || includeOnlineSignatures == false) {
+					blockData.setOnlineAccountsSignatures(null);
+				}
+				return blockData;
+			}
+
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		}
 	}
 
+	@GET
+	@Path("/signature/{signature}/data")
+	@Operation(
+			summary = "Fetch serialized, base58 encoded block data using base58 signature",
+			description = "Returns serialized data for the block that matches the given signature",
+			responses = {
+					@ApiResponse(
+							description = "the block data",
+							content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
+					)
+			}
+	)
+	@ApiErrors({
+			ApiError.INVALID_SIGNATURE, ApiError.BLOCK_UNKNOWN, ApiError.INVALID_DATA, ApiError.REPOSITORY_ISSUE
+	})
+	public String getSerializedBlockData(@PathParam("signature") String signature58) {
+		// Decode signature
+		byte[] signature;
+		try {
+			signature = Base58.decode(signature58);
+		} catch (NumberFormatException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_SIGNATURE, e);
+		}
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+
+            // Check the database first
+			BlockData blockData = repository.getBlockRepository().fromSignature(signature);
+			if (blockData != null) {
+                Block block = new Block(repository, blockData);
+                ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+                bytes.write(Ints.toByteArray(block.getBlockData().getHeight()));
+                bytes.write(BlockTransformer.toBytes(block));
+                return Base58.encode(bytes.toByteArray());
+            }
+
+            // Not found, so try the block archive
+            byte[] bytes = BlockArchiveReader.getInstance().fetchSerializedBlockBytesForSignature(signature, false, repository);
+            if (bytes != null) {
+                return Base58.encode(bytes);
+            }
+
+            throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
+		} catch (TransformationException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA, e);
+		} catch (DataException | IOException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
 	@GET
 	@Path("/signature/{signature}/transactions")
 	@Operation(
@@ -117,8 +197,12 @@ public class BlocksResource {
 		}
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			if (repository.getBlockRepository().getHeightFromSignature(signature) == 0)
+		    // Check if the block exists in either the database or archive
+			if (repository.getBlockRepository().getHeightFromSignature(signature) == 0 &&
+					repository.getBlockArchiveRepository().getHeightFromSignature(signature) == 0) {
+				// Not found in either the database or archive
 				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
+            }
 
 			return repository.getBlockRepository().getTransactionsFromSignature(signature, limit, offset, reverse);
 		} catch (DataException e) {
@@ -147,7 +231,19 @@ public class BlocksResource {
 	})
 	public BlockData getFirstBlock() {
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			return repository.getBlockRepository().fromHeight(1);
+			// Check the database first
+			BlockData blockData = repository.getBlockRepository().fromHeight(1);
+			if (blockData != null) {
+				return blockData;
+			}
+
+			// Try the archive
+			blockData = repository.getBlockArchiveRepository().fromHeight(1);
+			if (blockData != null) {
+				return blockData;
+			}
+
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		}
@@ -209,17 +305,28 @@ public class BlocksResource {
 		}
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
+			BlockData childBlockData = null;
+
+			// Check if block exists in database
 			BlockData blockData = repository.getBlockRepository().fromSignature(signature);
+			if (blockData != null) {
+				return repository.getBlockRepository().fromReference(signature);
+			}
 
-			// Check block exists
-			if (blockData == null)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
-
-			BlockData childBlockData = repository.getBlockRepository().fromReference(signature);
+			// Not found, so try the archive
+			// This also checks that the parent block exists
+			// It will return null if either the parent or child don't exit
+			childBlockData = repository.getBlockArchiveRepository().fromReference(signature);
 
 			// Check child block exists
-			if (childBlockData == null)
+			if (childBlockData == null) {
 				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
+			}
+
+			// Check child block's reference matches the supplied signature
+			if (!Arrays.equals(childBlockData.getReference(), signature)) {
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
+			}
 
 			return childBlockData;
 		} catch (DataException e) {
@@ -285,13 +392,20 @@ public class BlocksResource {
 		}
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
+			// Firstly check the database
 			BlockData blockData = repository.getBlockRepository().fromSignature(signature);
+			if (blockData != null) {
+				return blockData.getHeight();
+			}
 
-			// Check block exists
-			if (blockData == null)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
+			// Not found, so try the archive
+			blockData = repository.getBlockArchiveRepository().fromSignature(signature);
+			if (blockData != null) {
+				return blockData.getHeight();
+			}
+
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
 
-			return blockData.getHeight();
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		}
@@ -316,13 +430,101 @@ public class BlocksResource {
 	@ApiErrors({
 		ApiError.BLOCK_UNKNOWN, ApiError.REPOSITORY_ISSUE
 	})
-	public BlockData getByHeight(@PathParam("height") int height) {
+	public BlockData getByHeight(@PathParam("height") int height,
+								 @QueryParam("includeOnlineSignatures") Boolean includeOnlineSignatures) {
 		try (final Repository repository = RepositoryManager.getRepository()) {
+			// Firstly check the database
 			BlockData blockData = repository.getBlockRepository().fromHeight(height);
-			if (blockData == null)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
+			if (blockData != null) {
+				if (includeOnlineSignatures == null || includeOnlineSignatures == false) {
+					blockData.setOnlineAccountsSignatures(null);
+				}
+				return blockData;
+			}
 
-			return blockData;
+			// Not found, so try the archive
+			blockData = repository.getBlockArchiveRepository().fromHeight(height);
+			if (blockData != null) {
+				if (includeOnlineSignatures == null || includeOnlineSignatures == false) {
+					blockData.setOnlineAccountsSignatures(null);
+				}
+				return blockData;
+			}
+
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
+
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@GET
+	@Path("/byheight/{height}/mintinginfo")
+	@Operation(
+			summary = "Fetch block minter info using block height",
+			description = "Returns the minter info for the block with given height",
+			responses = {
+					@ApiResponse(
+							description = "the block",
+							content = @Content(
+									schema = @Schema(
+											implementation = BlockData.class
+									)
+							)
+					)
+			}
+	)
+	@ApiErrors({
+			ApiError.BLOCK_UNKNOWN, ApiError.REPOSITORY_ISSUE
+	})
+	public BlockMintingInfo getBlockMintingInfoByHeight(@PathParam("height") int height) {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			// Try the database
+			BlockData blockData = repository.getBlockRepository().fromHeight(height);
+			if (blockData == null) {
+
+				// Not found, so try the archive
+				blockData = repository.getBlockArchiveRepository().fromHeight(height);
+				if (blockData == null) {
+
+					// Still not found
+					throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
+				}
+			}
+
+			Block block = new Block(repository, blockData);
+			BlockData parentBlockData = repository.getBlockRepository().fromSignature(blockData.getReference());
+			if (parentBlockData == null) {
+				// Parent block not found - try the archive
+				parentBlockData = repository.getBlockArchiveRepository().fromSignature(blockData.getReference());
+				if (parentBlockData == null) {
+
+					// Still not found
+					throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
+				}
+			}
+
+			int minterLevel = Account.getRewardShareEffectiveMintingLevel(repository, blockData.getMinterPublicKey());
+			if (minterLevel == 0)
+				// This may be unavailable when requesting a trimmed block
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+			BigInteger distance = block.calcKeyDistance(parentBlockData.getHeight(), parentBlockData.getSignature(), blockData.getMinterPublicKey(), minterLevel);
+			double ratio = new BigDecimal(distance).divide(new BigDecimal(block.MAX_DISTANCE), 40, RoundingMode.DOWN).doubleValue();
+			long timestamp = block.calcTimestamp(parentBlockData, blockData.getMinterPublicKey(), minterLevel);
+			long timeDelta = timestamp - parentBlockData.getTimestamp();
+
+			BlockMintingInfo blockMintingInfo = new BlockMintingInfo();
+			blockMintingInfo.minterPublicKey = blockData.getMinterPublicKey();
+			blockMintingInfo.minterLevel = minterLevel;
+			blockMintingInfo.onlineAccountsCount = blockData.getOnlineAccountsCount();
+			blockMintingInfo.maxDistance = new BigDecimal(block.MAX_DISTANCE);
+			blockMintingInfo.keyDistance = distance;
+			blockMintingInfo.keyDistanceRatio = ratio;
+			blockMintingInfo.timestamp = timestamp;
+			blockMintingInfo.timeDelta = timeDelta;
+
+			return blockMintingInfo;
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		}
@@ -348,13 +550,26 @@ public class BlocksResource {
 	})
 	public BlockData getByTimestamp(@PathParam("timestamp") long timestamp) {
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			int height = repository.getBlockRepository().getHeightFromTimestamp(timestamp);
-			if (height == 0)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
+			BlockData blockData = null;
 
-			BlockData blockData = repository.getBlockRepository().fromHeight(height);
-			if (blockData == null)
+			// Try the Blocks table
+			int height = repository.getBlockRepository().getHeightFromTimestamp(timestamp);
+			if (height > 0) {
+				// Found match in Blocks table
+				return repository.getBlockRepository().fromHeight(height);
+			}
+
+			// Not found in Blocks table, so try the archive
+			height = repository.getBlockArchiveRepository().getHeightFromTimestamp(timestamp);
+			if (height > 0) {
+				// Found match in archive
+				blockData = repository.getBlockArchiveRepository().fromHeight(height);
+			}
+
+			// Ensure block exists
+			if (blockData == null) {
 				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
+			}
 
 			return blockData;
 		} catch (DataException e) {
@@ -391,9 +606,14 @@ public class BlocksResource {
 
 			for (/* count already set */; count > 0; --count, ++height) {
 				BlockData blockData = repository.getBlockRepository().fromHeight(height);
-				if (blockData == null)
-					// Run out of blocks!
-					break;
+				if (blockData == null) {
+					// Not found - try the archive
+					blockData = repository.getBlockArchiveRepository().fromHeight(height);
+					if (blockData == null) {
+						// Run out of blocks!
+						break;
+					}
+				}
 
 				blocks.add(blockData);
 			}
@@ -438,7 +658,29 @@ public class BlocksResource {
 			if (accountData == null || accountData.getPublicKey() == null)
 				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.PUBLIC_KEY_NOT_FOUND);
 
-			return repository.getBlockRepository().getBlockSummariesBySigner(accountData.getPublicKey(), limit, offset, reverse);
+
+			List<BlockSummaryData> summaries = repository.getBlockRepository()
+					.getBlockSummariesBySigner(accountData.getPublicKey(), limit, offset, reverse);
+
+			// Add any from the archive
+			List<BlockSummaryData> archivedSummaries = repository.getBlockArchiveRepository()
+					.getBlockSummariesBySigner(accountData.getPublicKey(), limit, offset, reverse);
+			if (archivedSummaries != null && !archivedSummaries.isEmpty()) {
+				summaries.addAll(archivedSummaries);
+			}
+			else {
+				summaries = archivedSummaries;
+			}
+
+			// Sort the results (because they may have been obtained from two places)
+			if (reverse != null && reverse) {
+				summaries.sort((s1, s2) -> Integer.valueOf(s2.getHeight()).compareTo(Integer.valueOf(s1.getHeight())));
+			}
+			else {
+				summaries.sort(Comparator.comparing(s -> Integer.valueOf(s.getHeight())));
+			}
+
+			return summaries;
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		}
@@ -474,7 +716,8 @@ public class BlocksResource {
 				if (!Crypto.isValidAddress(address))
 					throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
 
-			return repository.getBlockRepository().getBlockSigners(addresses, limit, offset, reverse);
+			// This method pulls data from both Blocks and BlockArchive, so no need to query serparately
+			return repository.getBlockArchiveRepository().getBlockSigners(addresses, limit, offset, reverse);
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		}
@@ -514,7 +757,76 @@ public class BlocksResource {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			return repository.getBlockRepository().getBlockSummaries(startHeight, endHeight, count);
+
+			/*
+			 * start	end		count		result
+			 * 10		40		null		blocks 10 to 39 (excludes end block, ignore count)
+			 *
+			 * null		null	null		blocks 1 to 50 (assume count=50, maybe start=1)
+			 * 30		null	null		blocks 30 to 79 (assume count=50)
+			 * 30		null	10			blocks 30 to 39
+			 *
+			 * null		null	50			last 50 blocks? so if max(blocks.height) is 200, then blocks 151 to 200
+			 * null		200		null		blocks 150 to 199 (excludes end block, assume count=50)
+			 * null		200		10			blocks 190 to 199 (excludes end block)
+			 */
+
+			List<BlockSummaryData> blockSummaries = new ArrayList<>();
+
+			// Use the latest X blocks if only a count is specified
+			if (startHeight == null && endHeight == null && count != null) {
+				BlockData chainTip = repository.getBlockRepository().getLastBlock();
+				startHeight = chainTip.getHeight() - count;
+				endHeight = chainTip.getHeight();
+			}
+
+			// ... otherwise default the start height to 1
+			if (startHeight == null && endHeight == null) {
+				startHeight = 1;
+			}
+
+			// Default the count to 50
+			if (count == null) {
+				count = 50;
+			}
+
+			// If both a start and end height exist, ignore the count
+			if (startHeight != null && endHeight != null) {
+				if (startHeight > 0 && endHeight > 0) {
+					count = Integer.MAX_VALUE;
+				}
+			}
+
+			// Derive start height from end height if missing
+			if (startHeight == null || startHeight == 0) {
+				if (endHeight != null && endHeight > 0) {
+					if (count != null) {
+						startHeight = endHeight - count;
+					}
+				}
+			}
+
+			for (/* count already set */; count > 0; --count, ++startHeight) {
+				if (endHeight != null && startHeight >= endHeight) {
+					break;
+				}
+				BlockData blockData = repository.getBlockRepository().fromHeight(startHeight);
+				if (blockData == null) {
+					// Not found - try the archive
+					blockData = repository.getBlockArchiveRepository().fromHeight(startHeight);
+					if (blockData == null) {
+						// Run out of blocks!
+						break;
+					}
+				}
+
+				if (blockData != null) {
+					BlockSummaryData blockSummaryData = new BlockSummaryData(blockData);
+					blockSummaries.add(blockSummaryData);
+				}
+			}
+
+			return blockSummaries;
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		}

src/main/java/org/qortal/api/resource/BootstrapResource.java

@@ -0,0 +1,92 @@
+package org.qortal.api.resource;
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.tags.Tag;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.api.ApiError;
+import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.Security;
+import org.qortal.repository.Bootstrap;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.*;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+import java.io.IOException;
+
+
+@Path("/bootstrap")
+@Tag(name = "Bootstrap")
+public class BootstrapResource {
+
+	private static final Logger LOGGER = LogManager.getLogger(BootstrapResource.class);
+
+	@Context
+	HttpServletRequest request;
+
+	@POST
+	@Path("/create")
+	@Operation(
+		summary = "Create bootstrap",
+		description = "Builds a bootstrap file for distribution",
+		responses = {
+			@ApiResponse(
+				description = "path to file on success, an exception on failure",
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
+			)
+		}
+	)
+	public String createBootstrap() {
+		Security.checkApiCallAllowed(request);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+
+			Bootstrap bootstrap = new Bootstrap(repository);
+			try {
+				bootstrap.checkRepositoryState();
+			} catch (DataException e) {
+				LOGGER.info("Not ready to create bootstrap: {}", e.getMessage());
+				throw ApiExceptionFactory.INSTANCE.createCustomException(request, ApiError.REPOSITORY_ISSUE, e.getMessage());
+			}
+			bootstrap.validateBlockchain();
+			return bootstrap.create();
+
+		} catch (DataException | InterruptedException | IOException e) {
+			LOGGER.info("Unable to create bootstrap", e);
+			throw ApiExceptionFactory.INSTANCE.createCustomException(request, ApiError.REPOSITORY_ISSUE, e.getMessage());
+		}
+	}
+
+	@GET
+	@Path("/validate")
+	@Operation(
+			summary = "Validate blockchain",
+			description = "Useful to check database integrity prior to creating or after installing a bootstrap. " +
+					"This process is intensive and can take over an hour to run.",
+			responses = {
+					@ApiResponse(
+							description = "true if valid, false if invalid",
+							content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "boolean"))
+					)
+			}
+	)
+	public boolean validateBootstrap() {
+		Security.checkApiCallAllowed(request);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+
+			Bootstrap bootstrap = new Bootstrap(repository);
+			return bootstrap.validateCompleteBlockchain();
+
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE);
+		}
+	}
+}

src/main/java/org/qortal/api/resource/CrossChainBitcoinACCTv1Resource.java

@@ -0,0 +1,363 @@
+package org.qortal.api.resource;
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.parameters.RequestBody;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.tags.Tag;
+
+import java.util.Arrays;
+import java.util.Random;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+
+import org.qortal.account.PublicKeyAccount;
+import org.qortal.api.ApiError;
+import org.qortal.api.ApiErrors;
+import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.Security;
+import org.qortal.api.model.CrossChainBuildRequest;
+import org.qortal.api.model.CrossChainDualSecretRequest;
+import org.qortal.api.model.CrossChainTradeRequest;
+import org.qortal.asset.Asset;
+import org.qortal.crosschain.BitcoinACCTv1;
+import org.qortal.crosschain.Bitcoiny;
+import org.qortal.crosschain.AcctMode;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.transaction.BaseTransactionData;
+import org.qortal.data.transaction.DeployAtTransactionData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.transaction.DeployAtTransaction;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.transaction.Transaction;
+import org.qortal.transaction.Transaction.TransactionType;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.Transformer;
+import org.qortal.transform.transaction.DeployAtTransactionTransformer;
+import org.qortal.transform.transaction.MessageTransactionTransformer;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+@Path("/crosschain/BitcoinACCTv1")
+@Tag(name = "Cross-Chain (BitcoinACCTv1)")
+public class CrossChainBitcoinACCTv1Resource {
+
+	@Context
+	HttpServletRequest request;
+
+	@POST
+	@Path("/build")
+	@Operation(
+		summary = "Build Bitcoin cross-chain trading AT",
+		description = "Returns raw, unsigned DEPLOY_AT transaction",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = CrossChainBuildRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_DATA, ApiError.INVALID_REFERENCE, ApiError.TRANSFORMATION_ERROR, ApiError.REPOSITORY_ISSUE})
+	public String buildTrade(CrossChainBuildRequest tradeRequest) {
+		Security.checkApiCallAllowed(request);
+
+		byte[] creatorPublicKey = tradeRequest.creatorPublicKey;
+
+		if (creatorPublicKey == null || creatorPublicKey.length != Transformer.PUBLIC_KEY_LENGTH)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+
+		if (tradeRequest.hashOfSecretB == null || tradeRequest.hashOfSecretB.length != Bitcoiny.HASH160_LENGTH)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		if (tradeRequest.tradeTimeout == null)
+			tradeRequest.tradeTimeout = 7 * 24 * 60; // 7 days
+		else
+			if (tradeRequest.tradeTimeout < 10 || tradeRequest.tradeTimeout > 50000)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		if (tradeRequest.qortAmount <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		if (tradeRequest.fundingQortAmount <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		// funding amount must exceed initial + final
+		if (tradeRequest.fundingQortAmount <= tradeRequest.qortAmount)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		if (tradeRequest.bitcoinAmount <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PublicKeyAccount creatorAccount = new PublicKeyAccount(repository, creatorPublicKey);
+
+			byte[] creationBytes = BitcoinACCTv1.buildQortalAT(creatorAccount.getAddress(), tradeRequest.bitcoinPublicKeyHash, tradeRequest.hashOfSecretB,
+					tradeRequest.qortAmount, tradeRequest.bitcoinAmount, tradeRequest.tradeTimeout);
+
+			long txTimestamp = NTP.getTime();
+			byte[] lastReference = creatorAccount.getLastReference();
+			if (lastReference == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_REFERENCE);
+
+			long fee = 0;
+			String name = "QORT-BTC cross-chain trade";
+			String description = "Qortal-Bitcoin cross-chain trade";
+			String atType = "ACCT";
+			String tags = "QORT-BTC ACCT";
+
+			BaseTransactionData baseTransactionData = new BaseTransactionData(txTimestamp, Group.NO_GROUP, lastReference, creatorAccount.getPublicKey(), fee, null);
+			TransactionData deployAtTransactionData = new DeployAtTransactionData(baseTransactionData, name, description, atType, tags, creationBytes, tradeRequest.fundingQortAmount, Asset.QORT);
+
+			Transaction deployAtTransaction = new DeployAtTransaction(repository, deployAtTransactionData);
+
+			fee = deployAtTransaction.calcRecommendedFee();
+			deployAtTransactionData.setFee(fee);
+
+			ValidationResult result = deployAtTransaction.isValidUnconfirmed();
+			if (result != ValidationResult.OK)
+				throw TransactionsResource.createTransactionInvalidException(request, result);
+
+			byte[] bytes = DeployAtTransactionTransformer.toBytes(deployAtTransactionData);
+			return Base58.encode(bytes);
+		} catch (TransformationException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.TRANSFORMATION_ERROR, e);
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@POST
+	@Path("/trademessage")
+	@Operation(
+		summary = "Builds raw, unsigned 'trade' MESSAGE transaction that sends cross-chain trade recipient address, triggering 'trade' mode",
+		description = "Specify address of cross-chain AT that needs to be messaged, and signature of 'offer' MESSAGE from trade partner.<br>"
+			+ "AT needs to be in 'offer' mode. Messages sent to an AT in any other mode will be ignored, but still cost fees to send!<br>"
+			+ "You need to sign output with trade private key otherwise the MESSAGE transaction will be invalid.",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = CrossChainTradeRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(
+					schema = @Schema(
+						type = "string"
+					)
+				)
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.INVALID_CRITERIA, ApiError.REPOSITORY_ISSUE})
+	public String buildTradeMessage(CrossChainTradeRequest tradeRequest) {
+		Security.checkApiCallAllowed(request);
+
+		byte[] tradePublicKey = tradeRequest.tradePublicKey;
+
+		if (tradePublicKey == null || tradePublicKey.length != Transformer.PUBLIC_KEY_LENGTH)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+
+		if (tradeRequest.atAddress == null || !Crypto.isValidAtAddress(tradeRequest.atAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (tradeRequest.messageTransactionSignature == null || !Crypto.isValidAddress(tradeRequest.messageTransactionSignature))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			ATData atData = fetchAtDataWithChecking(repository, tradeRequest.atAddress);
+			CrossChainTradeData crossChainTradeData = BitcoinACCTv1.getInstance().populateTradeData(repository, atData);
+
+			if (crossChainTradeData.mode != AcctMode.OFFERING)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			// Does supplied public key match trade public key?
+			if (!Crypto.toAddress(tradePublicKey).equals(crossChainTradeData.qortalCreatorTradeAddress))
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+
+			TransactionData transactionData = repository.getTransactionRepository().fromSignature(tradeRequest.messageTransactionSignature);
+			if (transactionData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.TRANSACTION_UNKNOWN);
+
+			if (transactionData.getType() != TransactionType.MESSAGE)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.TRANSACTION_INVALID);
+
+			MessageTransactionData messageTransactionData = (MessageTransactionData) transactionData;
+			byte[] messageData = messageTransactionData.getData();
+			BitcoinACCTv1.OfferMessageData offerMessageData = BitcoinACCTv1.extractOfferMessageData(messageData);
+			if (offerMessageData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.TRANSACTION_INVALID);
+
+			// Good to make MESSAGE
+
+			byte[] aliceForeignPublicKeyHash = offerMessageData.partnerBitcoinPKH;
+			byte[] hashOfSecretA = offerMessageData.hashOfSecretA;
+			int lockTimeA = (int) offerMessageData.lockTimeA;
+
+			String aliceNativeAddress = Crypto.toAddress(messageTransactionData.getCreatorPublicKey());
+			int lockTimeB = BitcoinACCTv1.calcLockTimeB(messageTransactionData.getTimestamp(), lockTimeA);
+
+			byte[] outgoingMessageData = BitcoinACCTv1.buildTradeMessage(aliceNativeAddress, aliceForeignPublicKeyHash, hashOfSecretA, lockTimeA, lockTimeB);
+			byte[] messageTransactionBytes = buildAtMessage(repository, tradePublicKey, tradeRequest.atAddress, outgoingMessageData);
+
+			return Base58.encode(messageTransactionBytes);
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@POST
+	@Path("/redeemmessage")
+	@Operation(
+		summary = "Builds raw, unsigned 'redeem' MESSAGE transaction that sends secrets to AT, releasing funds to partner",
+		description = "Specify address of cross-chain AT that needs to be messaged, both 32-byte secrets and an address for receiving QORT from AT.<br>"
+			+ "AT needs to be in 'trade' mode. Messages sent to an AT in any other mode will be ignored, but still cost fees to send!<br>"
+			+ "You need to sign output with account the AT considers the trade 'partner' otherwise the MESSAGE transaction will be invalid.",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = CrossChainDualSecretRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(
+					schema = @Schema(
+						type = "string"
+					)
+				)
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.INVALID_DATA, ApiError.INVALID_CRITERIA, ApiError.REPOSITORY_ISSUE})
+	public String buildRedeemMessage(CrossChainDualSecretRequest secretRequest) {
+		Security.checkApiCallAllowed(request);
+
+		byte[] partnerPublicKey = secretRequest.partnerPublicKey;
+
+		if (partnerPublicKey == null || partnerPublicKey.length != Transformer.PUBLIC_KEY_LENGTH)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+
+		if (secretRequest.atAddress == null || !Crypto.isValidAtAddress(secretRequest.atAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (secretRequest.secretA == null || secretRequest.secretA.length != BitcoinACCTv1.SECRET_LENGTH)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		if (secretRequest.secretB == null || secretRequest.secretB.length != BitcoinACCTv1.SECRET_LENGTH)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		if (secretRequest.receivingAddress == null || !Crypto.isValidAddress(secretRequest.receivingAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			ATData atData = fetchAtDataWithChecking(repository, secretRequest.atAddress);
+			CrossChainTradeData crossChainTradeData = BitcoinACCTv1.getInstance().populateTradeData(repository, atData);
+
+			if (crossChainTradeData.mode != AcctMode.TRADING)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			String partnerAddress = Crypto.toAddress(partnerPublicKey);
+
+			// MESSAGE must come from address that AT considers trade partner
+			if (!crossChainTradeData.qortalPartnerAddress.equals(partnerAddress))
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+			// Good to make MESSAGE
+
+			byte[] messageData = BitcoinACCTv1.buildRedeemMessage(secretRequest.secretA, secretRequest.secretB, secretRequest.receivingAddress);
+			byte[] messageTransactionBytes = buildAtMessage(repository, partnerPublicKey, secretRequest.atAddress, messageData);
+
+			return Base58.encode(messageTransactionBytes);
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	private ATData fetchAtDataWithChecking(Repository repository, String atAddress) throws DataException {
+		ATData atData = repository.getATRepository().fromATAddress(atAddress);
+		if (atData == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
+
+		// Must be correct AT - check functionality using code hash
+		if (!Arrays.equals(atData.getCodeHash(), BitcoinACCTv1.CODE_BYTES_HASH))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		// No point sending message to AT that's finished
+		if (atData.getIsFinished())
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		return atData;
+	}
+
+	private byte[] buildAtMessage(Repository repository, byte[] senderPublicKey, String atAddress, byte[] messageData) throws DataException {
+		long txTimestamp = NTP.getTime();
+
+		// senderPublicKey could be ephemeral trade public key where there is no corresponding account and hence no reference
+		String senderAddress = Crypto.toAddress(senderPublicKey);
+		byte[] lastReference = repository.getAccountRepository().getLastReference(senderAddress);
+		final boolean requiresPoW = lastReference == null;
+
+		if (requiresPoW) {
+			Random random = new Random();
+			lastReference = new byte[Transformer.SIGNATURE_LENGTH];
+			random.nextBytes(lastReference);
+		}
+
+		int version = 4;
+		int nonce = 0;
+		long amount = 0L;
+		Long assetId = null; // no assetId as amount is zero
+		Long fee = 0L;
+
+		BaseTransactionData baseTransactionData = new BaseTransactionData(txTimestamp, Group.NO_GROUP, lastReference, senderPublicKey, fee, null);
+		TransactionData messageTransactionData = new MessageTransactionData(baseTransactionData, version, nonce, atAddress, amount, assetId, messageData, false, false);
+
+		MessageTransaction messageTransaction = new MessageTransaction(repository, messageTransactionData);
+
+		if (requiresPoW) {
+			messageTransaction.computeNonce();
+		} else {
+			fee = messageTransaction.calcRecommendedFee();
+			messageTransactionData.setFee(fee);
+		}
+
+		ValidationResult result = messageTransaction.isValidUnconfirmed();
+		if (result != ValidationResult.OK)
+			throw TransactionsResource.createTransactionInvalidException(request, result);
+
+		try {
+			return MessageTransactionTransformer.toBytes(messageTransactionData);
+		} catch (TransformationException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.TRANSFORMATION_ERROR, e);
+		}
+	}
+
+}

src/main/java/org/qortal/api/resource/CrossChainBitcoinResource.java

@@ -0,0 +1,167 @@
+package org.qortal.api.resource;
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.ArraySchema;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.parameters.RequestBody;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.tags.Tag;
+
+import java.util.List;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+
+import org.bitcoinj.core.Transaction;
+import org.qortal.api.ApiError;
+import org.qortal.api.ApiErrors;
+import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.Security;
+import org.qortal.api.model.crosschain.BitcoinSendRequest;
+import org.qortal.crosschain.Bitcoin;
+import org.qortal.crosschain.ForeignBlockchainException;
+import org.qortal.crosschain.SimpleTransaction;
+
+@Path("/crosschain/btc")
+@Tag(name = "Cross-Chain (Bitcoin)")
+public class CrossChainBitcoinResource {
+
+	@Context
+	HttpServletRequest request;
+
+	@POST
+	@Path("/walletbalance")
+	@Operation(
+		summary = "Returns BTC balance for hierarchical, deterministic BIP32 wallet",
+		description = "Supply BIP32 'm' private/public key in base58, starting with 'xprv'/'xpub' for mainnet, 'tprv'/'tpub' for testnet",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.TEXT_PLAIN,
+				schema = @Schema(
+					type = "string",
+					description = "BIP32 'm' private/public key in base58",
+					example = "tpubD6NzVbkrYhZ4XTPc4btCZ6SMgn8CxmWkj6VBVZ1tfcJfMq4UwAjZbG8U74gGSypL9XBYk2R2BLbDBe8pcEyBKM1edsGQEPKXNbEskZozeZc"
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string", description = "balance (satoshis)"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
+	public String getBitcoinWalletBalance(String key58) {
+		Security.checkApiCallAllowed(request);
+
+		Bitcoin bitcoin = Bitcoin.getInstance();
+
+		if (!bitcoin.isValidDeterministicKey(key58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		Long balance = bitcoin.getWalletBalance(key58);
+		if (balance == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+
+		return balance.toString();
+	}
+
+	@POST
+	@Path("/wallettransactions")
+	@Operation(
+		summary = "Returns transactions for hierarchical, deterministic BIP32 wallet",
+		description = "Supply BIP32 'm' private/public key in base58, starting with 'xprv'/'xpub' for mainnet, 'tprv'/'tpub' for testnet",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.TEXT_PLAIN,
+				schema = @Schema(
+					type = "string",
+					description = "BIP32 'm' private/public key in base58",
+					example = "tpubD6NzVbkrYhZ4XTPc4btCZ6SMgn8CxmWkj6VBVZ1tfcJfMq4UwAjZbG8U74gGSypL9XBYk2R2BLbDBe8pcEyBKM1edsGQEPKXNbEskZozeZc"
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(array = @ArraySchema( schema = @Schema( implementation = SimpleTransaction.class ) ) )
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
+	public List<SimpleTransaction> getBitcoinWalletTransactions(String key58) {
+		Security.checkApiCallAllowed(request);
+
+		Bitcoin bitcoin = Bitcoin.getInstance();
+
+		if (!bitcoin.isValidDeterministicKey(key58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		try {
+			return bitcoin.getWalletTransactions(key58);
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+		}
+	}
+
+	@POST
+	@Path("/send")
+	@Operation(
+		summary = "Sends BTC from hierarchical, deterministic BIP32 wallet to specific address",
+		description = "Currently only supports 'legacy' P2PKH Bitcoin addresses. Supply BIP32 'm' private key in base58, starting with 'xprv' for mainnet, 'tprv' for testnet",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = BitcoinSendRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string", description = "transaction hash"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.INVALID_CRITERIA, ApiError.INVALID_ADDRESS, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
+	public String sendBitcoin(BitcoinSendRequest bitcoinSendRequest) {
+		Security.checkApiCallAllowed(request);
+
+		if (bitcoinSendRequest.bitcoinAmount <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		if (bitcoinSendRequest.feePerByte != null && bitcoinSendRequest.feePerByte <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		Bitcoin bitcoin = Bitcoin.getInstance();
+
+		if (!bitcoin.isValidAddress(bitcoinSendRequest.receivingAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (!bitcoin.isValidDeterministicKey(bitcoinSendRequest.xprv58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		Transaction spendTransaction = bitcoin.buildSpend(bitcoinSendRequest.xprv58,
+				bitcoinSendRequest.receivingAddress,
+				bitcoinSendRequest.bitcoinAmount,
+				bitcoinSendRequest.feePerByte);
+
+		if (spendTransaction == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE);
+
+		try {
+			bitcoin.broadcastTransaction(spendTransaction);
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+		}
+
+		return spendTransaction.getTxId().toString();
+	}
+
+}

src/main/java/org/qortal/api/resource/CrossChainDogecoinACCTv1Resource.java

@@ -0,0 +1,140 @@
+package org.qortal.api.resource;
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.parameters.RequestBody;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.tags.Tag;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.api.ApiError;
+import org.qortal.api.ApiErrors;
+import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.Security;
+import org.qortal.api.model.CrossChainSecretRequest;
+import org.qortal.crosschain.AcctMode;
+import org.qortal.crosschain.DogecoinACCTv1;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.Transformer;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+import java.util.Arrays;
+
+@Path("/crosschain/DogecoinACCTv1")
+@Tag(name = "Cross-Chain (DogecoinACCTv1)")
+public class CrossChainDogecoinACCTv1Resource {
+
+	@Context
+	HttpServletRequest request;
+
+	@POST
+	@Path("/redeemmessage")
+	@Operation(
+		summary = "Signs and broadcasts a 'redeem' MESSAGE transaction that sends secrets to AT, releasing funds to partner",
+		description = "Specify address of cross-chain AT that needs to be messaged, Alice's trade private key, the 32-byte secret,<br>"
+			+ "and an address for receiving QORT from AT. All of these can be found in Alice's trade bot data.<br>"
+			+ "AT needs to be in 'trade' mode. Messages sent to an AT in any other mode will be ignored, but still cost fees to send!<br>"
+			+ "You need to use the private key that the AT considers the trade 'partner' otherwise the MESSAGE transaction will be invalid.",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = CrossChainSecretRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(
+					schema = @Schema(
+						type = "string"
+					)
+				)
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.INVALID_DATA, ApiError.INVALID_CRITERIA, ApiError.REPOSITORY_ISSUE})
+	public boolean buildRedeemMessage(CrossChainSecretRequest secretRequest) {
+		Security.checkApiCallAllowed(request);
+
+		byte[] partnerPrivateKey = secretRequest.partnerPrivateKey;
+
+		if (partnerPrivateKey == null || partnerPrivateKey.length != Transformer.PRIVATE_KEY_LENGTH)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		if (secretRequest.atAddress == null || !Crypto.isValidAtAddress(secretRequest.atAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (secretRequest.secret == null || secretRequest.secret.length != DogecoinACCTv1.SECRET_LENGTH)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		if (secretRequest.receivingAddress == null || !Crypto.isValidAddress(secretRequest.receivingAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			ATData atData = fetchAtDataWithChecking(repository, secretRequest.atAddress);
+			CrossChainTradeData crossChainTradeData = DogecoinACCTv1.getInstance().populateTradeData(repository, atData);
+
+			if (crossChainTradeData.mode != AcctMode.TRADING)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			byte[] partnerPublicKey = new PrivateKeyAccount(null, partnerPrivateKey).getPublicKey();
+			String partnerAddress = Crypto.toAddress(partnerPublicKey);
+
+			// MESSAGE must come from address that AT considers trade partner
+			if (!crossChainTradeData.qortalPartnerAddress.equals(partnerAddress))
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+			// Good to make MESSAGE
+
+			byte[] messageData = DogecoinACCTv1.buildRedeemMessage(secretRequest.secret, secretRequest.receivingAddress);
+
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, partnerPrivateKey);
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, secretRequest.atAddress, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.TRANSACTION_INVALID);
+
+			return true;
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	private ATData fetchAtDataWithChecking(Repository repository, String atAddress) throws DataException {
+		ATData atData = repository.getATRepository().fromATAddress(atAddress);
+		if (atData == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
+
+		// Must be correct AT - check functionality using code hash
+		if (!Arrays.equals(atData.getCodeHash(), DogecoinACCTv1.CODE_BYTES_HASH))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		// No point sending message to AT that's finished
+		if (atData.getIsFinished())
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		return atData;
+	}
+
+}

src/main/java/org/qortal/api/resource/CrossChainDogecoinResource.java

@@ -0,0 +1,165 @@
+package org.qortal.api.resource;
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.ArraySchema;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.parameters.RequestBody;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.tags.Tag;
+import org.bitcoinj.core.Transaction;
+import org.qortal.api.ApiError;
+import org.qortal.api.ApiErrors;
+import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.Security;
+import org.qortal.api.model.crosschain.DogecoinSendRequest;
+import org.qortal.crosschain.ForeignBlockchainException;
+import org.qortal.crosschain.Dogecoin;
+import org.qortal.crosschain.SimpleTransaction;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+import java.util.List;
+
+@Path("/crosschain/doge")
+@Tag(name = "Cross-Chain (Dogecoin)")
+public class CrossChainDogecoinResource {
+
+	@Context
+	HttpServletRequest request;
+
+	@POST
+	@Path("/walletbalance")
+	@Operation(
+		summary = "Returns DOGE balance for hierarchical, deterministic BIP32 wallet",
+		description = "Supply BIP32 'm' private/public key in base58, starting with 'xprv'/'xpub' for mainnet, 'tprv'/'tpub' for testnet",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.TEXT_PLAIN,
+				schema = @Schema(
+					type = "string",
+					description = "BIP32 'm' private/public key in base58",
+					example = "tpubD6NzVbkrYhZ4XTPc4btCZ6SMgn8CxmWkj6VBVZ1tfcJfMq4UwAjZbG8U74gGSypL9XBYk2R2BLbDBe8pcEyBKM1edsGQEPKXNbEskZozeZc"
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string", description = "balance (satoshis)"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
+	public String getDogecoinWalletBalance(String key58) {
+		Security.checkApiCallAllowed(request);
+
+		Dogecoin dogecoin = Dogecoin.getInstance();
+
+		if (!dogecoin.isValidDeterministicKey(key58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		Long balance = dogecoin.getWalletBalance(key58);
+		if (balance == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+
+		return balance.toString();
+	}
+
+	@POST
+	@Path("/wallettransactions")
+	@Operation(
+		summary = "Returns transactions for hierarchical, deterministic BIP32 wallet",
+		description = "Supply BIP32 'm' private/public key in base58, starting with 'xprv'/'xpub' for mainnet, 'tprv'/'tpub' for testnet",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.TEXT_PLAIN,
+				schema = @Schema(
+					type = "string",
+					description = "BIP32 'm' private/public key in base58",
+					example = "tpubD6NzVbkrYhZ4XTPc4btCZ6SMgn8CxmWkj6VBVZ1tfcJfMq4UwAjZbG8U74gGSypL9XBYk2R2BLbDBe8pcEyBKM1edsGQEPKXNbEskZozeZc"
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(array = @ArraySchema( schema = @Schema( implementation = SimpleTransaction.class ) ) )
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
+	public List<SimpleTransaction> getDogecoinWalletTransactions(String key58) {
+		Security.checkApiCallAllowed(request);
+
+		Dogecoin dogecoin = Dogecoin.getInstance();
+
+		if (!dogecoin.isValidDeterministicKey(key58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		try {
+			return dogecoin.getWalletTransactions(key58);
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+		}
+	}
+
+	@POST
+	@Path("/send")
+	@Operation(
+		summary = "Sends DOGE from hierarchical, deterministic BIP32 wallet to specific address",
+		description = "Currently only supports 'legacy' P2PKH Dogecoin addresses. Supply BIP32 'm' private key in base58, starting with 'xprv' for mainnet, 'tprv' for testnet",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = DogecoinSendRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string", description = "transaction hash"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.INVALID_CRITERIA, ApiError.INVALID_ADDRESS, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
+	public String sendBitcoin(DogecoinSendRequest dogecoinSendRequest) {
+		Security.checkApiCallAllowed(request);
+
+		if (dogecoinSendRequest.dogecoinAmount <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		if (dogecoinSendRequest.feePerByte != null && dogecoinSendRequest.feePerByte <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		Dogecoin dogecoin = Dogecoin.getInstance();
+
+		if (!dogecoin.isValidAddress(dogecoinSendRequest.receivingAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (!dogecoin.isValidDeterministicKey(dogecoinSendRequest.xprv58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		Transaction spendTransaction = dogecoin.buildSpend(dogecoinSendRequest.xprv58,
+				dogecoinSendRequest.receivingAddress,
+				dogecoinSendRequest.dogecoinAmount,
+				dogecoinSendRequest.feePerByte);
+
+		if (spendTransaction == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE);
+
+		try {
+			dogecoin.broadcastTransaction(spendTransaction);
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+		}
+
+		return spendTransaction.getTxId().toString();
+	}
+
+}

src/main/java/org/qortal/api/resource/CrossChainHtlcResource.java

@@ -0,0 +1,653 @@
+package org.qortal.api.resource;
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.tags.Tag;
+
+import java.math.BigDecimal;
+import java.util.List;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.GET;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.PathParam;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.bitcoinj.core.*;
+import org.bitcoinj.script.Script;
+import org.qortal.api.*;
+import org.qortal.api.model.CrossChainBitcoinyHTLCStatus;
+import org.qortal.crosschain.*;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+@Path("/crosschain/htlc")
+@Tag(name = "Cross-Chain (Hash time-locked contracts)")
+public class CrossChainHtlcResource {
+
+	private static final Logger LOGGER = LogManager.getLogger(CrossChainHtlcResource.class);
+
+	@Context
+	HttpServletRequest request;
+
+	@GET
+	@Path("/address/{blockchain}/{refundPKH}/{locktime}/{redeemPKH}/{hashOfSecret}")
+	@Operation(
+		summary = "Returns HTLC address based on trade info",
+		description = "Public key hashes (PKH) and hash of secret should be 20 bytes (base58 encoded). Locktime is seconds since epoch.",
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_CRITERIA})
+	public String deriveHtlcAddress(@PathParam("blockchain") String blockchainName,
+			@PathParam("refundPKH") String refundPKH,
+			@PathParam("locktime") int lockTime,
+			@PathParam("redeemPKH") String redeemPKH,
+			@PathParam("hashOfSecret") String hashOfSecret) {
+		SupportedBlockchain blockchain = SupportedBlockchain.valueOf(blockchainName);
+		if (blockchain == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		byte[] refunderPubKeyHash;
+		byte[] redeemerPubKeyHash;
+		byte[] decodedHashOfSecret;
+
+		try {
+			refunderPubKeyHash = Base58.decode(refundPKH);
+			redeemerPubKeyHash = Base58.decode(redeemPKH);
+
+			if (refunderPubKeyHash.length != 20 || redeemerPubKeyHash.length != 20)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+		} catch (IllegalArgumentException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+		}
+
+		try {
+			decodedHashOfSecret = Base58.decode(hashOfSecret);
+			if (decodedHashOfSecret.length != 20)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+		} catch (IllegalArgumentException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+		}
+
+		byte[] redeemScript = BitcoinyHTLC.buildScript(refunderPubKeyHash, lockTime, redeemerPubKeyHash, decodedHashOfSecret);
+
+		Bitcoiny bitcoiny = (Bitcoiny) blockchain.getInstance();
+
+		return bitcoiny.deriveP2shAddress(redeemScript);
+	}
+
+	@GET
+	@Path("/status/{blockchain}/{refundPKH}/{locktime}/{redeemPKH}/{hashOfSecret}")
+	@Operation(
+		summary = "Checks HTLC status",
+		description = "Public key hashes (PKH) and hash of secret should be 20 bytes (base58 encoded). Locktime is seconds since epoch.",
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.APPLICATION_JSON, schema = @Schema(implementation = CrossChainBitcoinyHTLCStatus.class))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_CRITERIA, ApiError.INVALID_ADDRESS, ApiError.ADDRESS_UNKNOWN})
+	public CrossChainBitcoinyHTLCStatus checkHtlcStatus(@PathParam("blockchain") String blockchainName,
+			@PathParam("refundPKH") String refundPKH,
+			@PathParam("locktime") int lockTime,
+			@PathParam("redeemPKH") String redeemPKH,
+			@PathParam("hashOfSecret") String hashOfSecret) {
+		Security.checkApiCallAllowed(request);
+
+		SupportedBlockchain blockchain = SupportedBlockchain.valueOf(blockchainName);
+		if (blockchain == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		byte[] refunderPubKeyHash;
+		byte[] redeemerPubKeyHash;
+		byte[] decodedHashOfSecret;
+
+		try {
+			refunderPubKeyHash = Base58.decode(refundPKH);
+			redeemerPubKeyHash = Base58.decode(redeemPKH);
+
+			if (refunderPubKeyHash.length != 20 || redeemerPubKeyHash.length != 20)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+		} catch (IllegalArgumentException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+		}
+
+		try {
+			decodedHashOfSecret = Base58.decode(hashOfSecret);
+			if (decodedHashOfSecret.length != 20)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+		} catch (IllegalArgumentException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+		}
+
+		byte[] redeemScript = BitcoinyHTLC.buildScript(refunderPubKeyHash, lockTime, redeemerPubKeyHash, decodedHashOfSecret);
+
+		Bitcoiny bitcoiny = (Bitcoiny) blockchain.getInstance();
+
+		String p2shAddress = bitcoiny.deriveP2shAddress(redeemScript);
+
+		long now = NTP.getTime();
+
+		try {
+			int medianBlockTime = bitcoiny.getMedianBlockTime();
+
+			// Check P2SH is funded
+			long p2shBalance = bitcoiny.getConfirmedBalance(p2shAddress.toString());
+
+			CrossChainBitcoinyHTLCStatus htlcStatus = new CrossChainBitcoinyHTLCStatus();
+			htlcStatus.bitcoinP2shAddress = p2shAddress;
+			htlcStatus.bitcoinP2shBalance = BigDecimal.valueOf(p2shBalance, 8);
+
+			List<TransactionOutput> fundingOutputs = bitcoiny.getUnspentOutputs(p2shAddress.toString());
+
+			if (p2shBalance > 0L && !fundingOutputs.isEmpty()) {
+				htlcStatus.canRedeem = now >= medianBlockTime * 1000L;
+				htlcStatus.canRefund = now >= lockTime * 1000L;
+			}
+
+			if (now >= medianBlockTime * 1000L) {
+				// See if we can extract secret
+				htlcStatus.secret = BitcoinyHTLC.findHtlcSecret(bitcoiny, htlcStatus.bitcoinP2shAddress);
+			}
+
+			return htlcStatus;
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+		}
+	}
+
+	@POST
+	@Path("/redeem/{ataddress}")
+	@Operation(
+			summary = "Redeems HTLC associated with supplied AT",
+			description = "To be used by a QORT seller (Bob) who needs to redeem LTC/DOGE/etc proceeds that are stuck in a P2SH.<br>" +
+					"This requires Bob's trade bot data to be present in the database for this AT.<br>" +
+					"It will fail if the buyer has yet to redeem the QORT held in the AT.",
+			responses = {
+					@ApiResponse(
+							content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "boolean"))
+					)
+			}
+	)
+	@ApiErrors({ApiError.INVALID_CRITERIA, ApiError.INVALID_ADDRESS, ApiError.ADDRESS_UNKNOWN})
+	public boolean redeemHtlc(@PathParam("ataddress") String atAddress) {
+		Security.checkApiCallAllowed(request);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			ATData atData = repository.getATRepository().fromATAddress(atAddress);
+			if (atData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
+
+			ACCT acct = SupportedBlockchain.getAcctByCodeHash(atData.getCodeHash());
+			if (acct == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			CrossChainTradeData crossChainTradeData = acct.populateTradeData(repository, atData);
+			if (crossChainTradeData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			// Attempt to find secret from the buyer's message to AT
+			byte[] decodedSecret = acct.findSecretA(repository, crossChainTradeData);
+			if (decodedSecret == null) {
+				LOGGER.info(() -> String.format("Unable to find secret-A from redeem message to AT %s", atAddress));
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+			}
+
+			List<TradeBotData> allTradeBotData = repository.getCrossChainRepository().getAllTradeBotData();
+			TradeBotData tradeBotData = allTradeBotData.stream().filter(tradeBotDataItem -> tradeBotDataItem.getAtAddress().equals(atAddress)).findFirst().orElse(null);
+
+			// Search for the tradePrivateKey in the tradebot data
+			byte[] decodedPrivateKey = null;
+			if (tradeBotData != null)
+				decodedPrivateKey = tradeBotData.getTradePrivateKey();
+
+			// Search for the foreign blockchain receiving address in the tradebot data
+			byte[] foreignBlockchainReceivingAccountInfo = null;
+			if (tradeBotData != null)
+				// Use receiving address PKH from tradebot data
+				foreignBlockchainReceivingAccountInfo = tradeBotData.getReceivingAccountInfo();
+
+			return this.doRedeemHtlc(atAddress, decodedPrivateKey, decodedSecret, foreignBlockchainReceivingAccountInfo);
+
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@POST
+	@Path("/redeemAll")
+	@Operation(
+			summary = "Redeems HTLC for all applicable ATs in tradebot data",
+			description = "To be used by a QORT seller (Bob) who needs to redeem LTC/DOGE/etc proceeds that are stuck in P2SH transactions.<br>" +
+					"This requires Bob's trade bot data to be present in the database for any ATs that need redeeming.<br>" +
+					"Returns true if at least one trade is redeemed. More detail is available in the log.txt.* file.",
+			responses = {
+					@ApiResponse(
+							content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "boolean"))
+					)
+			}
+	)
+	@ApiErrors({ApiError.INVALID_CRITERIA, ApiError.INVALID_ADDRESS, ApiError.ADDRESS_UNKNOWN})
+	public boolean redeemAllHtlc() {
+		Security.checkApiCallAllowed(request);
+		boolean success = false;
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			List<TradeBotData> allTradeBotData = repository.getCrossChainRepository().getAllTradeBotData();
+
+			for (TradeBotData tradeBotData : allTradeBotData) {
+				String atAddress = tradeBotData.getAtAddress();
+				if (atAddress == null) {
+					LOGGER.info("Missing AT address in tradebot data", atAddress);
+					continue;
+				}
+
+				String tradeState = tradeBotData.getState();
+				if (tradeState == null) {
+					LOGGER.info("Missing trade state for AT {}", atAddress);
+					continue;
+				}
+
+				if (tradeState.startsWith("ALICE")) {
+					LOGGER.info("AT {} isn't redeemable because it is a buy order", atAddress);
+					continue;
+				}
+
+				ATData atData = repository.getATRepository().fromATAddress(atAddress);
+				if (atData == null) {
+					LOGGER.info("Couldn't find AT with address {}", atAddress);
+					continue;
+				}
+
+				ACCT acct = SupportedBlockchain.getAcctByCodeHash(atData.getCodeHash());
+				if (acct == null) {
+					continue;
+				}
+
+				CrossChainTradeData crossChainTradeData = acct.populateTradeData(repository, atData);
+				if (crossChainTradeData == null) {
+					LOGGER.info("Couldn't find crosschain trade data for AT {}", atAddress);
+					continue;
+				}
+
+				// Attempt to find secret from the buyer's message to AT
+				byte[] decodedSecret = acct.findSecretA(repository, crossChainTradeData);
+				if (decodedSecret == null) {
+					LOGGER.info("Unable to find secret-A from redeem message to AT {}", atAddress);
+					continue;
+				}
+
+				// Search for the tradePrivateKey in the tradebot data
+				byte[] decodedPrivateKey = tradeBotData.getTradePrivateKey();
+
+				// Search for the foreign blockchain receiving address PKH in the tradebot data
+				byte[] foreignBlockchainReceivingAccountInfo = tradeBotData.getReceivingAccountInfo();
+
+				try {
+					LOGGER.info("Attempting to redeem P2SH balance associated with AT {}...", atAddress);
+					boolean redeemed = this.doRedeemHtlc(atAddress, decodedPrivateKey, decodedSecret, foreignBlockchainReceivingAccountInfo);
+					if (redeemed) {
+						LOGGER.info("Redeemed P2SH balance associated with AT {}", atAddress);
+						success = true;
+					}
+					else {
+						LOGGER.info("Couldn't redeem P2SH balance associated with AT {}. Already redeemed?", atAddress);
+					}
+				} catch (ApiException e) {
+					LOGGER.info("Couldn't redeem P2SH balance associated with AT {}. Missing data?", atAddress);
+				}
+			}
+
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+
+		return success;
+	}
+
+	private boolean doRedeemHtlc(String atAddress, byte[] decodedTradePrivateKey, byte[] decodedSecret,
+								 byte[] foreignBlockchainReceivingAccountInfo) {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+
+			ATData atData = repository.getATRepository().fromATAddress(atAddress);
+			if (atData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
+
+			ACCT acct = SupportedBlockchain.getAcctByCodeHash(atData.getCodeHash());
+			if (acct == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			CrossChainTradeData crossChainTradeData = acct.populateTradeData(repository, atData);
+			if (crossChainTradeData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			// Validate trade private key
+			if (decodedTradePrivateKey == null || decodedTradePrivateKey.length != 32)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			// Validate secret
+			if (decodedSecret == null || decodedSecret.length != 32)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			// Validate receiving address
+			if (foreignBlockchainReceivingAccountInfo == null || foreignBlockchainReceivingAccountInfo.length != 20)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			// Make sure the receiving address isn't a QORT address, given that we can share the same field for both QORT and foreign blockchains
+			if (Crypto.isValidAddress(foreignBlockchainReceivingAccountInfo))
+				if (Base58.encode(foreignBlockchainReceivingAccountInfo).startsWith("Q"))
+					// This is likely a QORT address, not a foreign blockchain
+					throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+
+			// Use secret-A to redeem P2SH-A
+
+			Bitcoiny bitcoiny = (Bitcoiny) acct.getBlockchain();
+			if (bitcoiny.getClass() == Bitcoin.class) {
+				LOGGER.info("Redeeming a Bitcoin HTLC is not yet supported");
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+			}
+
+			int lockTime = crossChainTradeData.lockTimeA;
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(crossChainTradeData.partnerForeignPKH, lockTime, crossChainTradeData.creatorForeignPKH, crossChainTradeData.hashOfSecretA);
+			String p2shAddressA = bitcoiny.deriveP2shAddress(redeemScriptA);
+			LOGGER.info(String.format("Redeeming P2SH address: %s", p2shAddressA));
+
+			// Fee for redeem/refund is subtracted from P2SH-A balance.
+			long feeTimestamp = calcFeeTimestamp(lockTime, crossChainTradeData.tradeTimeout);
+			long p2shFee = bitcoiny.getP2shFee(feeTimestamp);
+			long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(bitcoiny.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+			switch (htlcStatusA) {
+				case UNFUNDED:
+				case FUNDING_IN_PROGRESS:
+					// P2SH-A suddenly not funded? Our best bet at this point is to hope for AT auto-refund
+					return false;
+
+				case REDEEM_IN_PROGRESS:
+				case REDEEMED:
+					// Double-check that we have redeemed P2SH-A...
+					return false;
+
+				case REFUND_IN_PROGRESS:
+				case REFUNDED:
+					// Wait for AT to auto-refund
+					return false;
+
+				case FUNDED: {
+					Coin redeemAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
+					ECKey redeemKey = ECKey.fromPrivate(decodedTradePrivateKey);
+					List<TransactionOutput> fundingOutputs = bitcoiny.getUnspentOutputs(p2shAddressA);
+
+					Transaction p2shRedeemTransaction = BitcoinyHTLC.buildRedeemTransaction(bitcoiny.getNetworkParameters(), redeemAmount, redeemKey,
+							fundingOutputs, redeemScriptA, decodedSecret, foreignBlockchainReceivingAccountInfo);
+
+					bitcoiny.broadcastTransaction(p2shRedeemTransaction);
+					LOGGER.info(String.format("P2SH address %s redeemed!", p2shAddressA));
+					return true;
+				}
+			}
+
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE, e);
+		}
+
+		return false;
+	}
+
+	@POST
+	@Path("/refund/{ataddress}")
+	@Operation(
+			summary = "Refunds HTLC associated with supplied AT",
+			description = "To be used by a QORT buyer (Alice) who needs to refund their LTC/DOGE/etc that is stuck in a P2SH.<br>" +
+					"This requires Alice's trade bot data to be present in the database for this AT.<br>" +
+					"It will fail if it's already redeemed by the seller, or if the lockTime (60 minutes) hasn't passed yet.",
+			responses = {
+					@ApiResponse(
+							content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "boolean"))
+					)
+			}
+	)
+	@ApiErrors({ApiError.INVALID_CRITERIA, ApiError.INVALID_ADDRESS, ApiError.ADDRESS_UNKNOWN})
+	public boolean refundHtlc(@PathParam("ataddress") String atAddress) {
+		Security.checkApiCallAllowed(request);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			List<TradeBotData> allTradeBotData = repository.getCrossChainRepository().getAllTradeBotData();
+			TradeBotData tradeBotData = allTradeBotData.stream().filter(tradeBotDataItem -> tradeBotDataItem.getAtAddress().equals(atAddress)).findFirst().orElse(null);
+			if (tradeBotData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			if (tradeBotData.getForeignKey() == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			ATData atData = repository.getATRepository().fromATAddress(atAddress);
+			if (atData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
+
+			ACCT acct = SupportedBlockchain.getAcctByCodeHash(atData.getCodeHash());
+			if (acct == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			// Determine foreign blockchain receive address for refund
+			Bitcoiny bitcoiny = (Bitcoiny) acct.getBlockchain();
+			String receiveAddress = bitcoiny.getUnusedReceiveAddress(tradeBotData.getForeignKey());
+
+			return this.doRefundHtlc(atAddress, receiveAddress);
+
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE, e);
+		}
+	}
+
+
+	@POST
+	@Path("/refundAll")
+	@Operation(
+			summary = "Refunds HTLC for all applicable ATs in tradebot data",
+			description = "To be used by a QORT buyer (Alice) who needs to refund their LTC/DOGE/etc proceeds that are stuck in P2SH transactions.<br>" +
+					"This requires Alice's trade bot data to be present in the database for this AT.<br>" +
+					"It will fail if it's already redeemed by the seller, or if the lockTime (60 minutes) hasn't passed yet.",
+			responses = {
+					@ApiResponse(
+							content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "boolean"))
+					)
+			}
+	)
+	@ApiErrors({ApiError.INVALID_CRITERIA, ApiError.INVALID_ADDRESS, ApiError.ADDRESS_UNKNOWN})
+	public boolean refundAllHtlc() {
+		Security.checkApiCallAllowed(request);
+		boolean success = false;
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			List<TradeBotData> allTradeBotData = repository.getCrossChainRepository().getAllTradeBotData();
+
+			for (TradeBotData tradeBotData : allTradeBotData) {
+				String atAddress = tradeBotData.getAtAddress();
+				if (atAddress == null) {
+					LOGGER.info("Missing AT address in tradebot data", atAddress);
+					continue;
+				}
+
+				String tradeState = tradeBotData.getState();
+				if (tradeState == null) {
+					LOGGER.info("Missing trade state for AT {}", atAddress);
+					continue;
+				}
+
+				if (tradeState.startsWith("BOB")) {
+					LOGGER.info("AT {} isn't refundable because it is a sell order", atAddress);
+					continue;
+				}
+
+				ATData atData = repository.getATRepository().fromATAddress(atAddress);
+				if (atData == null) {
+					LOGGER.info("Couldn't find AT with address {}", atAddress);
+					continue;
+				}
+
+				ACCT acct = SupportedBlockchain.getAcctByCodeHash(atData.getCodeHash());
+				if (acct == null) {
+					continue;
+				}
+
+				CrossChainTradeData crossChainTradeData = acct.populateTradeData(repository, atData);
+				if (crossChainTradeData == null) {
+					LOGGER.info("Couldn't find crosschain trade data for AT {}", atAddress);
+					continue;
+				}
+
+				if (tradeBotData.getForeignKey() == null) {
+					LOGGER.info("Couldn't find foreign key for AT {}", atAddress);
+					continue;
+				}
+
+				try {
+					// Determine foreign blockchain receive address for refund
+					Bitcoiny bitcoiny = (Bitcoiny) acct.getBlockchain();
+					String receivingAddress = bitcoiny.getUnusedReceiveAddress(tradeBotData.getForeignKey());
+
+					LOGGER.info("Attempting to refund P2SH balance associated with AT {}...", atAddress);
+					boolean refunded = this.doRefundHtlc(atAddress, receivingAddress);
+					if (refunded) {
+						LOGGER.info("Refunded P2SH balance associated with AT {}", atAddress);
+						success = true;
+					}
+					else {
+						LOGGER.info("Couldn't refund P2SH balance associated with AT {}. Already redeemed?", atAddress);
+					}
+				} catch (ApiException | ForeignBlockchainException e) {
+					LOGGER.info("Couldn't refund P2SH balance associated with AT {}. Missing data?", atAddress);
+				}
+			}
+
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+
+		return success;
+	}
+
+
+	private boolean doRefundHtlc(String atAddress, String receiveAddress) {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+
+			ATData atData = repository.getATRepository().fromATAddress(atAddress);
+			if (atData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
+
+			ACCT acct = SupportedBlockchain.getAcctByCodeHash(atData.getCodeHash());
+			if (acct == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			CrossChainTradeData crossChainTradeData = acct.populateTradeData(repository, atData);
+			if (crossChainTradeData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			// If the AT is "finished" then it will have a zero balance
+			// In these cases we should avoid HTLC refunds if tbe QORT haven't been returned to the seller
+			if (atData.getIsFinished() && crossChainTradeData.mode != AcctMode.REFUNDED && crossChainTradeData.mode != AcctMode.CANCELLED) {
+				LOGGER.info(String.format("Skipping AT %s because the QORT has already been redemed", atAddress));
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+			}
+
+			List<TradeBotData> allTradeBotData = repository.getCrossChainRepository().getAllTradeBotData();
+			TradeBotData tradeBotData = allTradeBotData.stream().filter(tradeBotDataItem -> tradeBotDataItem.getAtAddress().equals(atAddress)).findFirst().orElse(null);
+			if (tradeBotData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			Bitcoiny bitcoiny = (Bitcoiny) acct.getBlockchain();
+			if (bitcoiny.getClass() == Bitcoin.class) {
+				LOGGER.info("Refunding a Bitcoin HTLC is not yet supported");
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+			}
+
+			int lockTime = tradeBotData.getLockTimeA();
+
+			// We can't refund P2SH-A until lockTime-A has passed
+			if (NTP.getTime() <= lockTime * 1000L)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_TOO_SOON);
+
+			// We can't refund P2SH-A until median block time has passed lockTime-A (see BIP113)
+			int medianBlockTime = bitcoiny.getMedianBlockTime();
+			if (medianBlockTime <= lockTime)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_TOO_SOON);
+
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTime, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+			String p2shAddressA = bitcoiny.deriveP2shAddress(redeemScriptA);
+			LOGGER.info(String.format("Refunding P2SH address: %s", p2shAddressA));
+
+			// Fee for redeem/refund is subtracted from P2SH-A balance.
+			long feeTimestamp = calcFeeTimestamp(lockTime, crossChainTradeData.tradeTimeout);
+			long p2shFee = bitcoiny.getP2shFee(feeTimestamp);
+			long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(bitcoiny.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+			switch (htlcStatusA) {
+				case UNFUNDED:
+				case FUNDING_IN_PROGRESS:
+					// Still waiting for P2SH-A to be funded...
+					throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_TOO_SOON);
+
+				case REDEEM_IN_PROGRESS:
+				case REDEEMED:
+				case REFUND_IN_PROGRESS:
+				case REFUNDED:
+					// Too late!
+					return false;
+
+				case FUNDED:{
+					Coin refundAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
+					ECKey refundKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
+					List<TransactionOutput> fundingOutputs = bitcoiny.getUnspentOutputs(p2shAddressA);
+
+					// Validate the destination foreign blockchain address
+					Address receiving = Address.fromString(bitcoiny.getNetworkParameters(), receiveAddress);
+					if (receiving.getOutputScriptType() != Script.ScriptType.P2PKH)
+						throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+					Transaction p2shRefundTransaction = BitcoinyHTLC.buildRefundTransaction(bitcoiny.getNetworkParameters(), refundAmount, refundKey,
+							fundingOutputs, redeemScriptA, lockTime, receiving.getHash());
+
+					bitcoiny.broadcastTransaction(p2shRefundTransaction);
+					return true;
+				}
+			}
+
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE, e);
+		}
+
+		return false;
+	}
+
+	private long calcFeeTimestamp(int lockTimeA, int tradeTimeout) {
+		return (lockTimeA - tradeTimeout * 60) * 1000L;
+	}
+
+}

src/main/java/org/qortal/api/resource/CrossChainLitecoinACCTv1Resource.java

@@ -0,0 +1,145 @@
+package org.qortal.api.resource;
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.parameters.RequestBody;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.tags.Tag;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.api.ApiError;
+import org.qortal.api.ApiErrors;
+import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.Security;
+import org.qortal.api.model.CrossChainSecretRequest;
+import org.qortal.crosschain.AcctMode;
+import org.qortal.crosschain.LitecoinACCTv1;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.Transformer;
+import org.qortal.transform.transaction.MessageTransactionTransformer;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+import java.util.Arrays;
+import java.util.Random;
+
+@Path("/crosschain/LitecoinACCTv1")
+@Tag(name = "Cross-Chain (LitecoinACCTv1)")
+public class CrossChainLitecoinACCTv1Resource {
+
+	@Context
+	HttpServletRequest request;
+
+	@POST
+	@Path("/redeemmessage")
+	@Operation(
+		summary = "Signs and broadcasts a 'redeem' MESSAGE transaction that sends secrets to AT, releasing funds to partner",
+		description = "Specify address of cross-chain AT that needs to be messaged, Alice's trade private key, the 32-byte secret,<br>"
+			+ "and an address for receiving QORT from AT. All of these can be found in Alice's trade bot data.<br>"
+			+ "AT needs to be in 'trade' mode. Messages sent to an AT in any other mode will be ignored, but still cost fees to send!<br>"
+			+ "You need to use the private key that the AT considers the trade 'partner' otherwise the MESSAGE transaction will be invalid.",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = CrossChainSecretRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(
+					schema = @Schema(
+						type = "string"
+					)
+				)
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.INVALID_DATA, ApiError.INVALID_CRITERIA, ApiError.REPOSITORY_ISSUE})
+	public boolean buildRedeemMessage(CrossChainSecretRequest secretRequest) {
+		Security.checkApiCallAllowed(request);
+
+		byte[] partnerPrivateKey = secretRequest.partnerPrivateKey;
+
+		if (partnerPrivateKey == null || partnerPrivateKey.length != Transformer.PRIVATE_KEY_LENGTH)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		if (secretRequest.atAddress == null || !Crypto.isValidAtAddress(secretRequest.atAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (secretRequest.secret == null || secretRequest.secret.length != LitecoinACCTv1.SECRET_LENGTH)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		if (secretRequest.receivingAddress == null || !Crypto.isValidAddress(secretRequest.receivingAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			ATData atData = fetchAtDataWithChecking(repository, secretRequest.atAddress);
+			CrossChainTradeData crossChainTradeData = LitecoinACCTv1.getInstance().populateTradeData(repository, atData);
+
+			if (crossChainTradeData.mode != AcctMode.TRADING)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			byte[] partnerPublicKey = new PrivateKeyAccount(null, partnerPrivateKey).getPublicKey();
+			String partnerAddress = Crypto.toAddress(partnerPublicKey);
+
+			// MESSAGE must come from address that AT considers trade partner
+			if (!crossChainTradeData.qortalPartnerAddress.equals(partnerAddress))
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+			// Good to make MESSAGE
+
+			byte[] messageData = LitecoinACCTv1.buildRedeemMessage(secretRequest.secret, secretRequest.receivingAddress);
+
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, partnerPrivateKey);
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, secretRequest.atAddress, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.TRANSACTION_INVALID);
+
+			return true;
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	private ATData fetchAtDataWithChecking(Repository repository, String atAddress) throws DataException {
+		ATData atData = repository.getATRepository().fromATAddress(atAddress);
+		if (atData == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
+
+		// Must be correct AT - check functionality using code hash
+		if (!Arrays.equals(atData.getCodeHash(), LitecoinACCTv1.CODE_BYTES_HASH))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		// No point sending message to AT that's finished
+		if (atData.getIsFinished())
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		return atData;
+	}
+
+}

src/main/java/org/qortal/api/resource/CrossChainLitecoinResource.java

@@ -0,0 +1,167 @@
+package org.qortal.api.resource;
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.ArraySchema;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.parameters.RequestBody;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.tags.Tag;
+
+import java.util.List;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+
+import org.bitcoinj.core.Transaction;
+import org.qortal.api.ApiError;
+import org.qortal.api.ApiErrors;
+import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.Security;
+import org.qortal.api.model.crosschain.LitecoinSendRequest;
+import org.qortal.crosschain.ForeignBlockchainException;
+import org.qortal.crosschain.Litecoin;
+import org.qortal.crosschain.SimpleTransaction;
+
+@Path("/crosschain/ltc")
+@Tag(name = "Cross-Chain (Litecoin)")
+public class CrossChainLitecoinResource {
+
+	@Context
+	HttpServletRequest request;
+
+	@POST
+	@Path("/walletbalance")
+	@Operation(
+		summary = "Returns LTC balance for hierarchical, deterministic BIP32 wallet",
+		description = "Supply BIP32 'm' private/public key in base58, starting with 'xprv'/'xpub' for mainnet, 'tprv'/'tpub' for testnet",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.TEXT_PLAIN,
+				schema = @Schema(
+					type = "string",
+					description = "BIP32 'm' private/public key in base58",
+					example = "tpubD6NzVbkrYhZ4XTPc4btCZ6SMgn8CxmWkj6VBVZ1tfcJfMq4UwAjZbG8U74gGSypL9XBYk2R2BLbDBe8pcEyBKM1edsGQEPKXNbEskZozeZc"
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string", description = "balance (satoshis)"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
+	public String getLitecoinWalletBalance(String key58) {
+		Security.checkApiCallAllowed(request);
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		if (!litecoin.isValidDeterministicKey(key58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		Long balance = litecoin.getWalletBalance(key58);
+		if (balance == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+
+		return balance.toString();
+	}
+
+	@POST
+	@Path("/wallettransactions")
+	@Operation(
+		summary = "Returns transactions for hierarchical, deterministic BIP32 wallet",
+		description = "Supply BIP32 'm' private/public key in base58, starting with 'xprv'/'xpub' for mainnet, 'tprv'/'tpub' for testnet",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.TEXT_PLAIN,
+				schema = @Schema(
+					type = "string",
+					description = "BIP32 'm' private/public key in base58",
+					example = "tpubD6NzVbkrYhZ4XTPc4btCZ6SMgn8CxmWkj6VBVZ1tfcJfMq4UwAjZbG8U74gGSypL9XBYk2R2BLbDBe8pcEyBKM1edsGQEPKXNbEskZozeZc"
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(array = @ArraySchema( schema = @Schema( implementation = SimpleTransaction.class ) ) )
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
+	public List<SimpleTransaction> getLitecoinWalletTransactions(String key58) {
+		Security.checkApiCallAllowed(request);
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		if (!litecoin.isValidDeterministicKey(key58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		try {
+			return litecoin.getWalletTransactions(key58);
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+		}
+	}
+
+	@POST
+	@Path("/send")
+	@Operation(
+		summary = "Sends LTC from hierarchical, deterministic BIP32 wallet to specific address",
+		description = "Currently only supports 'legacy' P2PKH Litecoin addresses. Supply BIP32 'm' private key in base58, starting with 'xprv' for mainnet, 'tprv' for testnet",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = LitecoinSendRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string", description = "transaction hash"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.INVALID_CRITERIA, ApiError.INVALID_ADDRESS, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
+	public String sendBitcoin(LitecoinSendRequest litecoinSendRequest) {
+		Security.checkApiCallAllowed(request);
+
+		if (litecoinSendRequest.litecoinAmount <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		if (litecoinSendRequest.feePerByte != null && litecoinSendRequest.feePerByte <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		if (!litecoin.isValidAddress(litecoinSendRequest.receivingAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (!litecoin.isValidDeterministicKey(litecoinSendRequest.xprv58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		Transaction spendTransaction = litecoin.buildSpend(litecoinSendRequest.xprv58,
+				litecoinSendRequest.receivingAddress,
+				litecoinSendRequest.litecoinAmount,
+				litecoinSendRequest.feePerByte);
+
+		if (spendTransaction == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE);
+
+		try {
+			litecoin.broadcastTransaction(spendTransaction);
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+		}
+
+		return spendTransaction.getTxId().toString();
+	}
+
+}

src/main/java/org/qortal/api/resource/CrossChainTradeBotResource.java

@@ -0,0 +1,296 @@
+package org.qortal.api.resource;
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.Parameter;
+import io.swagger.v3.oas.annotations.media.ArraySchema;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.parameters.RequestBody;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.tags.Tag;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.DELETE;
+import javax.ws.rs.GET;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.QueryParam;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+
+import org.qortal.account.Account;
+import org.qortal.account.PublicKeyAccount;
+import org.qortal.api.ApiError;
+import org.qortal.api.ApiErrors;
+import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.Security;
+import org.qortal.api.model.crosschain.TradeBotCreateRequest;
+import org.qortal.api.model.crosschain.TradeBotRespondRequest;
+import org.qortal.asset.Asset;
+import org.qortal.controller.Controller;
+import org.qortal.controller.tradebot.AcctTradeBot;
+import org.qortal.controller.tradebot.TradeBot;
+import org.qortal.crosschain.ForeignBlockchain;
+import org.qortal.crosschain.SupportedBlockchain;
+import org.qortal.crosschain.ACCT;
+import org.qortal.crosschain.AcctMode;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.utils.Base58;
+
+@Path("/crosschain/tradebot")
+@Tag(name = "Cross-Chain (Trade-Bot)")
+public class CrossChainTradeBotResource {
+
+	@Context
+	HttpServletRequest request;
+
+	@GET
+	@Operation(
+		summary = "List current trade-bot states",
+		responses = {
+			@ApiResponse(
+				content = @Content(
+					array = @ArraySchema(
+						schema = @Schema(
+							implementation = TradeBotData.class
+						)
+					)
+				)
+			)
+		}
+	)
+	@ApiErrors({ApiError.REPOSITORY_ISSUE})
+	public List<TradeBotData> getTradeBotStates(
+			@Parameter(
+					description = "Limit to specific blockchain",
+					example = "LITECOIN",
+					schema = @Schema(implementation = SupportedBlockchain.class)
+				) @QueryParam("foreignBlockchain") SupportedBlockchain foreignBlockchain) {
+		Security.checkApiCallAllowed(request);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			List<TradeBotData> allTradeBotData = repository.getCrossChainRepository().getAllTradeBotData();
+
+			if (foreignBlockchain == null)
+				return allTradeBotData;
+
+			return allTradeBotData.stream().filter(tradeBotData -> tradeBotData.getForeignBlockchain().equals(foreignBlockchain.name())).collect(Collectors.toList());
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@POST
+	@Path("/create")
+	@Operation(
+		summary = "Create a trade offer (trade-bot entry)",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = TradeBotCreateRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.INVALID_CRITERIA, ApiError.INSUFFICIENT_BALANCE, ApiError.REPOSITORY_ISSUE, ApiError.ORDER_SIZE_TOO_SMALL})
+	@SuppressWarnings("deprecation")
+	public String tradeBotCreator(TradeBotCreateRequest tradeBotCreateRequest) {
+		Security.checkApiCallAllowed(request);
+
+		if (tradeBotCreateRequest.foreignBlockchain == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		ForeignBlockchain foreignBlockchain = tradeBotCreateRequest.foreignBlockchain.getInstance();
+
+		// We prefer foreignAmount to deprecated bitcoinAmount
+		if (tradeBotCreateRequest.foreignAmount == null)
+			tradeBotCreateRequest.foreignAmount = tradeBotCreateRequest.bitcoinAmount;
+
+		if (!foreignBlockchain.isValidAddress(tradeBotCreateRequest.receivingAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (tradeBotCreateRequest.tradeTimeout < 60)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		if (tradeBotCreateRequest.foreignAmount == null || tradeBotCreateRequest.foreignAmount <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ORDER_SIZE_TOO_SMALL);
+
+		if (tradeBotCreateRequest.foreignAmount < foreignBlockchain.getMinimumOrderAmount())
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ORDER_SIZE_TOO_SMALL);
+
+		if (tradeBotCreateRequest.qortAmount <= 0 || tradeBotCreateRequest.fundingQortAmount <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ORDER_SIZE_TOO_SMALL);
+
+		if (!Controller.getInstance().isUpToDate())
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCKCHAIN_NEEDS_SYNC);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			// Do some simple checking first
+			Account creator = new PublicKeyAccount(repository, tradeBotCreateRequest.creatorPublicKey);
+
+			if (creator.getConfirmedBalance(Asset.QORT) < tradeBotCreateRequest.fundingQortAmount)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INSUFFICIENT_BALANCE);
+
+			byte[] unsignedBytes = TradeBot.getInstance().createTrade(repository, tradeBotCreateRequest);
+			if (unsignedBytes == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			return Base58.encode(unsignedBytes);
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@POST
+	@Path("/respond")
+	@Operation(
+		summary = "Respond to a trade offer. NOTE: WILL SPEND FUNDS!)",
+		description = "Start a new trade-bot entry to respond to chosen trade offer.",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = TradeBotRespondRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.INVALID_ADDRESS, ApiError.INVALID_CRITERIA, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE, ApiError.REPOSITORY_ISSUE})
+	@SuppressWarnings("deprecation")
+	public String tradeBotResponder(TradeBotRespondRequest tradeBotRespondRequest) {
+		Security.checkApiCallAllowed(request);
+
+		final String atAddress = tradeBotRespondRequest.atAddress;
+
+		// We prefer foreignKey to deprecated xprv58
+		if (tradeBotRespondRequest.foreignKey == null)
+			tradeBotRespondRequest.foreignKey = tradeBotRespondRequest.xprv58;
+
+		if (tradeBotRespondRequest.foreignKey == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		if (atAddress == null || !Crypto.isValidAtAddress(atAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (tradeBotRespondRequest.receivingAddress == null || !Crypto.isValidAddress(tradeBotRespondRequest.receivingAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (!Controller.getInstance().isUpToDate())
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCKCHAIN_NEEDS_SYNC);
+
+		// Extract data from cross-chain trading AT
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			ATData atData = fetchAtDataWithChecking(repository, atAddress);
+
+			// TradeBot uses AT's code hash to map to ACCT
+			ACCT acct = TradeBot.getInstance().getAcctUsingAtData(atData);
+			if (acct == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+			if (!acct.getBlockchain().isValidWalletKey(tradeBotRespondRequest.foreignKey))
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+			CrossChainTradeData crossChainTradeData = acct.populateTradeData(repository, atData);
+			if (crossChainTradeData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+			if (crossChainTradeData.mode != AcctMode.OFFERING)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			AcctTradeBot.ResponseResult result = TradeBot.getInstance().startResponse(repository, atData, acct, crossChainTradeData,
+					tradeBotRespondRequest.foreignKey, tradeBotRespondRequest.receivingAddress);
+
+			switch (result) {
+				case OK:
+					return "true";
+
+				case BALANCE_ISSUE:
+					throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE);
+
+				case NETWORK_ISSUE:
+					throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+
+				default:
+					return "false";
+			}
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@DELETE
+	@Operation(
+		summary = "Delete completed trade",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.TEXT_PLAIN,
+				schema = @Schema(
+					type = "string",
+					example = "93MB2qRDNVLxbmmPuYpLdAqn3u2x9ZhaVZK5wELHueP8"
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_ADDRESS, ApiError.REPOSITORY_ISSUE})
+	public String tradeBotDelete(String tradePrivateKey58) {
+		Security.checkApiCallAllowed(request);
+
+		final byte[] tradePrivateKey;
+		try {
+			tradePrivateKey = Base58.decode(tradePrivateKey58);
+
+			if (tradePrivateKey.length != 32)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+		} catch (NumberFormatException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+		}
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			// Handed off to TradeBot
+			return TradeBot.getInstance().deleteEntry(repository, tradePrivateKey) ? "true" : "false";
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	private ATData fetchAtDataWithChecking(Repository repository, String atAddress) throws DataException {
+		ATData atData = repository.getATRepository().fromATAddress(atAddress);
+		if (atData == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
+
+		// No point sending message to AT that's finished
+		if (atData.getIsFinished())
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		return atData;
+	}
+
+}

src/main/java/org/qortal/api/resource/ListsResource.java

@@ -0,0 +1,201 @@
+package org.qortal.api.resource;
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.ArraySchema;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.parameters.RequestBody;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.tags.Tag;
+
+import org.qortal.api.*;
+import org.qortal.api.model.ListRequest;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.account.AccountData;
+import org.qortal.list.ResourceListManager;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.*;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+
+
+@Path("/lists")
+@Tag(name = "Lists")
+public class ListsResource {
+
+	@Context
+	HttpServletRequest request;
+
+
+	/* Address blacklist */
+
+	@POST
+	@Path("/blacklist/addresses")
+	@Operation(
+			summary = "Add one or more QORT addresses to the local blacklist",
+			requestBody = @RequestBody(
+					required = true,
+					content = @Content(
+							mediaType = MediaType.APPLICATION_JSON,
+							schema = @Schema(
+									implementation = ListRequest.class
+							)
+					)
+			),
+			responses = {
+					@ApiResponse(
+							description = "Returns true if all addresses were processed, false if any couldn't be " +
+									"processed, or an exception on failure. If false or an exception is returned, " +
+									"the list will not be updated, and the request will need to be re-issued.",
+							content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "boolean"))
+					)
+			}
+	)
+	@ApiErrors({ApiError.INVALID_ADDRESS, ApiError.ADDRESS_UNKNOWN, ApiError.REPOSITORY_ISSUE})
+	public String addAddressesToBlacklist(ListRequest listRequest) {
+		Security.checkApiCallAllowed(request);
+
+		if (listRequest == null || listRequest.items == null) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+		}
+
+		int successCount = 0;
+		int errorCount = 0;
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+
+			for (String address : listRequest.items) {
+
+				if (!Crypto.isValidAddress(address)) {
+					errorCount++;
+					continue;
+				}
+
+				AccountData accountData = repository.getAccountRepository().getAccount(address);
+				// Not found?
+				if (accountData == null) {
+					errorCount++;
+					continue;
+				}
+
+				// Valid address, so go ahead and blacklist it
+				boolean success = ResourceListManager.getInstance().addToList("blacklist", "addresses", address, false);
+				if (success) {
+					successCount++;
+				}
+				else {
+					errorCount++;
+				}
+			}
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+
+		if (successCount > 0 && errorCount == 0) {
+			// All were successful, so save the blacklist
+			ResourceListManager.getInstance().saveList("blacklist", "addresses");
+			return "true";
+		}
+		else {
+			// Something went wrong, so revert
+			ResourceListManager.getInstance().revertList("blacklist", "addresses");
+			return "false";
+		}
+	}
+
+	@DELETE
+	@Path("/blacklist/addresses")
+	@Operation(
+			summary = "Remove one or more QORT addresses from the local blacklist",
+			requestBody = @RequestBody(
+					required = true,
+					content = @Content(
+							mediaType = MediaType.APPLICATION_JSON,
+							schema = @Schema(
+									implementation = ListRequest.class
+							)
+					)
+			),
+			responses = {
+					@ApiResponse(
+							description = "Returns true if all addresses were processed, false if any couldn't be " +
+									"processed, or an exception on failure. If false or an exception is returned, " +
+									"the list will not be updated, and the request will need to be re-issued.",
+							content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "boolean"))
+					)
+			}
+	)
+	@ApiErrors({ApiError.INVALID_ADDRESS, ApiError.ADDRESS_UNKNOWN, ApiError.REPOSITORY_ISSUE})
+	public String removeAddressesFromBlacklist(ListRequest listRequest) {
+		Security.checkApiCallAllowed(request);
+
+		if (listRequest == null || listRequest.items == null) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+		}
+
+		int successCount = 0;
+		int errorCount = 0;
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+
+			for (String address : listRequest.items) {
+
+				if (!Crypto.isValidAddress(address)) {
+					errorCount++;
+					continue;
+				}
+
+				AccountData accountData = repository.getAccountRepository().getAccount(address);
+				// Not found?
+				if (accountData == null) {
+					errorCount++;
+					continue;
+				}
+
+				// Valid address, so go ahead and blacklist it
+				// Don't save as we will do this at the end of the process
+				boolean success = ResourceListManager.getInstance().removeFromList("blacklist", "addresses", address, false);
+				if (success) {
+					successCount++;
+				}
+				else {
+					errorCount++;
+				}
+			}
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+
+		if (successCount > 0 && errorCount == 0) {
+			// All were successful, so save the blacklist
+			ResourceListManager.getInstance().saveList("blacklist", "addresses");
+			return "true";
+		}
+		else {
+			// Something went wrong, so revert
+			ResourceListManager.getInstance().revertList("blacklist", "addresses");
+			return "false";
+		}
+	}
+
+	@GET
+	@Path("/blacklist/addresses")
+	@Operation(
+			summary = "Fetch the list of blacklisted addresses",
+			responses = {
+					@ApiResponse(
+							description = "A JSON array of addresses",
+							content = @Content(mediaType = MediaType.APPLICATION_JSON, array = @ArraySchema(schema = @Schema(implementation = String.class)))
+					)
+			}
+	)
+	public String getAddressBlacklist() {
+		Security.checkApiCallAllowed(request);
+		return ResourceListManager.getInstance().getJSONStringForList("blacklist", "addresses");
+	}
+
+}

src/main/java/org/qortal/api/resource/PeersResource.java

@@ -321,7 +321,7 @@ public class PeersResource {
 				boolean force = true;
 				List<BlockSummaryData> peerBlockSummaries = new ArrayList<>();
 
-				SynchronizationResult findCommonBlockResult = Synchronizer.getInstance().fetchSummariesFromCommonBlock(repository, targetPeer, ourInitialHeight, force, peerBlockSummaries);
+				SynchronizationResult findCommonBlockResult = Synchronizer.getInstance().fetchSummariesFromCommonBlock(repository, targetPeer, ourInitialHeight, force, peerBlockSummaries, true);
 				if (findCommonBlockResult != SynchronizationResult.OK)
 					return null;
 

src/main/java/org/qortal/api/resource/TransactionsResource.java

@@ -510,14 +510,19 @@ public class TransactionsResource {
 		if (!Controller.getInstance().isUpToDate())
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCKCHAIN_NEEDS_SYNC);
 
+		byte[] rawBytes = Base58.decode(rawBytes58);
+
+		TransactionData transactionData;
+		try {
+			transactionData = TransactionTransformer.fromBytes(rawBytes);
+		} catch (TransformationException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.TRANSFORMATION_ERROR, e);
+		}
+
+		if (transactionData == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			byte[] rawBytes = Base58.decode(rawBytes58);
-
-			TransactionData transactionData = TransactionTransformer.fromBytes(rawBytes);
-
-			if (transactionData == null)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
-
 			Transaction transaction = Transaction.fromData(repository, transactionData);
 
 			if (!transaction.isSignatureValid())
@@ -535,16 +540,9 @@ public class TransactionsResource {
 				blockchainLock.unlock();
 			}
 
-			// Notify controller of new transaction
-			Controller.getInstance().onNewTransaction(transactionData, null);
-
 			return "true";
 		} catch (NumberFormatException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA, e);
-		} catch (TransformationException e) {
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.TRANSFORMATION_ERROR, e);
-		} catch (ApiException e) {
-			throw e;
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		} catch (InterruptedException e) {

src/main/java/org/qortal/api/resource/UtilsResource.java

@@ -33,7 +33,6 @@ import org.qortal.transaction.Transaction.TransactionType;
 import org.qortal.transform.Transformer;
 import org.qortal.transform.transaction.TransactionTransformer;
 import org.qortal.transform.transaction.TransactionTransformer.Transformation;
-import org.qortal.utils.BIP39;
 import org.qortal.utils.Base58;
 
 import com.google.common.hash.HashCode;
@@ -195,123 +194,6 @@ public class UtilsResource {
 		return Base58.encode(random);
 	}
 
-	@GET
-	@Path("/mnemonic")
-	@Operation(
-		summary = "Generate 12-word BIP39 mnemonic",
-		description = "Optionally pass 16-byte, base58-encoded entropy or entropy will be internally generated.<br>"
-				+ "Example entropy input: YcVfxkQb6JRzqk5kF2tNLv",
-		responses = {
-			@ApiResponse(
-				description = "mnemonic",
-				content = @Content(
-					mediaType = MediaType.TEXT_PLAIN,
-					schema = @Schema(
-						type = "string"
-					)
-				)
-			)
-		}
-	)
-	@ApiErrors({ApiError.NON_PRODUCTION, ApiError.INVALID_DATA})
-	public String getMnemonic(@QueryParam("entropy") String suppliedEntropy) {
-		if (Settings.getInstance().isApiRestricted())
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.NON_PRODUCTION);
-
-		/*
-		 * BIP39 word lists have 2048 entries so can be represented by 11 bits.
-		 * UUID (128bits) and another 4 bits gives 132 bits.
-		 * 132 bits, divided by 11, gives 12 words.
-		 */
-		byte[] entropy;
-		if (suppliedEntropy != null) {
-			// Use caller-supplied entropy input
-			try {
-				entropy = Base58.decode(suppliedEntropy);
-			} catch (NumberFormatException e) {
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
-			}
-
-			// Must be 16-bytes
-			if (entropy.length != 16)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
-		} else {
-			// Generate entropy internally
-			UUID uuid = UUID.randomUUID();
-
-			byte[] uuidMSB = Longs.toByteArray(uuid.getMostSignificantBits());
-			byte[] uuidLSB = Longs.toByteArray(uuid.getLeastSignificantBits());
-			entropy = Bytes.concat(uuidMSB, uuidLSB);
-		}
-
-		// Use SHA256 to generate more bits
-		byte[] hash = Crypto.digest(entropy);
-
-		// Append first 4 bits from hash to end. (Actually 8 bits but we only use 4).
-		byte checksum = (byte) (hash[0] & 0xf0);
-		entropy = Bytes.concat(entropy, new byte[] {
-			checksum
-		});
-
-		return BIP39.encode(entropy, "en");
-	}
-
-	@POST
-	@Path("/mnemonic")
-	@Operation(
-		summary = "Calculate binary entropy from 12-word BIP39 mnemonic",
-		description = "Returns the base58-encoded binary form, or \"false\" if mnemonic is invalid.",
-		requestBody = @RequestBody(
-			required = true,
-			content = @Content(
-				mediaType = MediaType.TEXT_PLAIN,
-				schema = @Schema(
-					type = "string"
-				)
-			)
-		),
-		responses = {
-			@ApiResponse(
-				description = "entropy in base58",
-				content = @Content(
-					mediaType = MediaType.TEXT_PLAIN,
-					schema = @Schema(
-						type = "string"
-					)
-				)
-			)
-		}
-	)
-	@ApiErrors({ApiError.NON_PRODUCTION})
-	public String fromMnemonic(String mnemonic) {
-		if (Settings.getInstance().isApiRestricted())
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.NON_PRODUCTION);
-
-		if (mnemonic.isEmpty())
-			return "false";
-
-		// Strip leading/trailing whitespace if any
-		mnemonic = mnemonic.trim();
-
-		String[] phraseWords = mnemonic.split(" ");
-		if (phraseWords.length != 12)
-			return "false";
-
-		// Convert BIP39 mnemonic to binary
-		byte[] binary = BIP39.decode(phraseWords, "en");
-		if (binary == null)
-			return "false";
-
-		byte[] entropy = Arrays.copyOf(binary, 16); // 132 bits is 16.5 bytes, but we're discarding checksum nybble
-
-		byte checksumNybble = (byte) (binary[16] & 0xf0);
-		byte[] checksum = Crypto.digest(entropy);
-		if (checksumNybble != (byte) (checksum[0] & 0xf0))
-			return "false";
-
-		return Base58.encode(entropy);
-	}
-
 	@POST
 	@Path("/privatekey")
 	@Operation(

src/main/java/org/qortal/api/websocket/ApiWebSocket.java

@@ -107,7 +107,9 @@ abstract class ApiWebSocket extends WebSocketServlet {
 
 	public void onWebSocketClose(Session session, int statusCode, String reason) {
 		synchronized (SESSIONS_BY_CLASS) {
-			SESSIONS_BY_CLASS.get(this.getClass()).remove(session);
+			List<Session> sessions = SESSIONS_BY_CLASS.get(this.getClass());
+			if (sessions != null)
+				sessions.remove(session);
 		}
 	}
 

src/main/java/org/qortal/api/websocket/ChatMessagesWebSocket.java

@@ -115,6 +115,9 @@ public class ChatMessagesWebSocket extends ApiWebSocket {
 	}
 
 	private void onNotify(Session session, ChatTransactionData chatTransactionData, List<String> involvingAddresses) {
+		if (chatTransactionData == null)
+			return;
+
 		// We only want direct/non-group messages where sender/recipient match our addresses
 		String recipient = chatTransactionData.getRecipient();
 		if (recipient == null)

src/main/java/org/qortal/api/websocket/PresenceWebSocket.java

@@ -0,0 +1,244 @@
+package org.qortal.api.websocket;
+
+import java.io.IOException;
+import java.io.StringWriter;
+import java.util.Collections;
+import java.util.EnumMap;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+
+import org.eclipse.jetty.websocket.api.Session;
+import org.eclipse.jetty.websocket.api.annotations.OnWebSocketClose;
+import org.eclipse.jetty.websocket.api.annotations.OnWebSocketConnect;
+import org.eclipse.jetty.websocket.api.annotations.OnWebSocketError;
+import org.eclipse.jetty.websocket.api.annotations.OnWebSocketMessage;
+import org.eclipse.jetty.websocket.api.annotations.WebSocket;
+import org.eclipse.jetty.websocket.servlet.WebSocketServletFactory;
+import org.qortal.controller.Controller;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.transaction.PresenceTransactionData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.event.Event;
+import org.qortal.event.EventBus;
+import org.qortal.event.Listener;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.transaction.PresenceTransaction.PresenceType;
+import org.qortal.transaction.Transaction.TransactionType;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+@WebSocket
+@SuppressWarnings("serial")
+public class PresenceWebSocket extends ApiWebSocket implements Listener {
+
+	@XmlAccessorType(XmlAccessType.FIELD)
+	@SuppressWarnings("unused")
+	private static class PresenceInfo {
+		private final PresenceType presenceType;
+		private final String publicKey;
+		private final long timestamp;
+		private final String address;
+
+		protected PresenceInfo() {
+			this.presenceType = null;
+			this.publicKey = null;
+			this.timestamp = 0L;
+			this.address = null;
+		}
+
+		public PresenceInfo(PresenceType presenceType, String pubKey58, long timestamp) {
+			this.presenceType = presenceType;
+			this.publicKey = pubKey58;
+			this.timestamp = timestamp;
+			this.address = Crypto.toAddress(Base58.decode(this.publicKey));
+		}
+
+		public PresenceType getPresenceType() {
+			return this.presenceType;
+		}
+
+		public String getPublicKey() {
+			return this.publicKey;
+		}
+
+		public long getTimestamp() {
+			return this.timestamp;
+		}
+
+		public String getAddress() {
+			return this.address;
+		}
+	}
+
+	/** Outer map key is PresenceType (enum), inner map key is public key in base58, inner map value is timestamp */
+	private static final Map<PresenceType, Map<String, Long>> currentEntries = Collections.synchronizedMap(new EnumMap<>(PresenceType.class));
+
+	/** (Optional) PresenceType used for filtering by that Session. */
+	private static final Map<Session, PresenceType> sessionPresenceTypes = Collections.synchronizedMap(new HashMap<>());
+
+	@Override
+	public void configure(WebSocketServletFactory factory) {
+		factory.register(PresenceWebSocket.class);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			populateCurrentInfo(repository);
+		} catch (DataException e) {
+			// How to fail properly?
+			return;
+		}
+
+		EventBus.INSTANCE.addListener(this::listen);
+	}
+
+	@Override
+	public void listen(Event event) {
+		// We use NewBlockEvent as a proxy for 1-minute timer
+		if (!(event instanceof Controller.NewTransactionEvent) && !(event instanceof Controller.NewBlockEvent))
+			return;
+
+		removeOldEntries();
+
+		if (event instanceof Controller.NewBlockEvent)
+			// We only wanted a chance to cull old entries
+			return;
+
+		TransactionData transactionData = ((Controller.NewTransactionEvent) event).getTransactionData();
+
+		if (transactionData.getType() != TransactionType.PRESENCE)
+			return;
+
+		PresenceTransactionData presenceData = (PresenceTransactionData) transactionData;
+		PresenceType presenceType = presenceData.getPresenceType();
+
+		// Put/replace for this publickey making sure we keep newest timestamp
+		String pubKey58 = Base58.encode(presenceData.getCreatorPublicKey());
+		long ourTimestamp = presenceData.getTimestamp();
+		long computedTimestamp = mergePresence(presenceType, pubKey58, ourTimestamp);
+
+		if (computedTimestamp != ourTimestamp)
+			// nothing changed
+			return;
+
+		List<PresenceInfo> presenceInfo = Collections.singletonList(new PresenceInfo(presenceType, pubKey58, computedTimestamp));
+
+		// Notify sessions
+		for (Session session : getSessions()) {
+			PresenceType sessionPresenceType = sessionPresenceTypes.get(session);
+
+			if (sessionPresenceType == null || sessionPresenceType == presenceType)
+				sendPresenceInfo(session, presenceInfo);
+		}
+	}
+
+	@OnWebSocketConnect
+	@Override
+	public void onWebSocketConnect(Session session) {
+		Map<String, List<String>> queryParams = session.getUpgradeRequest().getParameterMap();
+		List<String> presenceTypes = queryParams.get("presenceType");
+
+		// We only support ONE presenceType
+		String presenceTypeName = presenceTypes == null || presenceTypes.isEmpty() ? null : presenceTypes.get(0);
+
+		PresenceType presenceType = presenceTypeName == null ? null : PresenceType.fromString(presenceTypeName);
+
+		// Make sure that if caller does give a presenceType, that it is a valid/known one.
+		if (presenceTypeName != null && presenceType == null) {
+			session.close(4003, "unknown presenceType: " + presenceTypeName);
+			return;
+		}
+
+		// Save session's requested PresenceType, if given
+		if (presenceType != null)
+			sessionPresenceTypes.put(session, presenceType);
+
+		List<PresenceInfo> presenceInfo;
+
+		synchronized (currentEntries) {
+			presenceInfo = currentEntries.entrySet().stream()
+					.filter(entry -> presenceType == null ? true : entry.getKey() == presenceType)
+					.flatMap(entry -> entry.getValue().entrySet().stream().map(innerEntry -> new PresenceInfo(entry.getKey(), innerEntry.getKey(), innerEntry.getValue())))
+					.collect(Collectors.toList());
+		}
+
+		if (!sendPresenceInfo(session, presenceInfo)) {
+			session.close(4002, "websocket issue");
+			return;
+		}
+
+		super.onWebSocketConnect(session);
+	}
+
+	@OnWebSocketClose
+	@Override
+	public void onWebSocketClose(Session session, int statusCode, String reason) {
+		// clean up
+		sessionPresenceTypes.remove(session);
+
+		super.onWebSocketClose(session, statusCode, reason);
+	}
+
+	@OnWebSocketError
+	public void onWebSocketError(Session session, Throwable throwable) {
+		/* ignored */
+	}
+
+	@OnWebSocketMessage
+	public void onWebSocketMessage(Session session, String message) {
+		/* ignored */
+	}
+
+	private boolean sendPresenceInfo(Session session, List<PresenceInfo> presenceInfo) {
+		try {
+			StringWriter stringWriter = new StringWriter();
+			marshall(stringWriter, presenceInfo);
+
+			String output = stringWriter.toString();
+			session.getRemote().sendStringByFuture(output);
+		} catch (IOException e) {
+			// No output this time?
+			return false;
+		}
+
+		return true;
+	}
+
+	private static void populateCurrentInfo(Repository repository) throws DataException {
+		// We want ALL PRESENCE transactions
+
+		List<TransactionData> presenceTransactionsData = repository.getTransactionRepository().getUnconfirmedTransactions(TransactionType.PRESENCE, null);
+
+		for (TransactionData transactionData : presenceTransactionsData) {
+			PresenceTransactionData presenceData = (PresenceTransactionData) transactionData;
+
+			PresenceType presenceType = presenceData.getPresenceType();
+
+			// Put/replace for this publickey making sure we keep newest timestamp
+			String pubKey58 = Base58.encode(presenceData.getCreatorPublicKey());
+			long ourTimestamp = presenceData.getTimestamp();
+
+			mergePresence(presenceType, pubKey58, ourTimestamp);
+		}
+	}
+
+	private static long mergePresence(PresenceType presenceType, String pubKey58, long ourTimestamp) {
+		Map<String, Long> typedPubkeyTimestamps = currentEntries.computeIfAbsent(presenceType, someType -> Collections.synchronizedMap(new HashMap<>()));
+		return typedPubkeyTimestamps.compute(pubKey58, (somePubKey58, currentTimestamp) -> (currentTimestamp == null || currentTimestamp < ourTimestamp) ? ourTimestamp : currentTimestamp);
+	}
+
+	private static void removeOldEntries() {
+		long now = NTP.getTime();
+
+		currentEntries.entrySet().forEach(entry -> {
+			long expiryThreshold = now - entry.getKey().getLifetime();
+			entry.getValue().entrySet().removeIf(pubkeyTimestamp -> pubkeyTimestamp.getValue() < expiryThreshold);
+		});
+	}
+
+}

src/main/java/org/qortal/api/websocket/TradeBotWebSocket.java

@@ -15,7 +15,8 @@ import org.eclipse.jetty.websocket.api.annotations.OnWebSocketError;
 import org.eclipse.jetty.websocket.api.annotations.OnWebSocketMessage;
 import org.eclipse.jetty.websocket.api.annotations.WebSocket;
 import org.eclipse.jetty.websocket.servlet.WebSocketServletFactory;
-import org.qortal.controller.TradeBot;
+import org.qortal.controller.tradebot.TradeBot;
+import org.qortal.crosschain.SupportedBlockchain;
 import org.qortal.data.crosschain.TradeBotData;
 import org.qortal.event.Event;
 import org.qortal.event.EventBus;
@@ -30,7 +31,9 @@ import org.qortal.utils.Base58;
 public class TradeBotWebSocket extends ApiWebSocket implements Listener {
 
 	/** Cache of trade-bot entry states, keyed by trade-bot entry's "trade private key" (base58) */
-	private static final Map<String, TradeBotData.State> PREVIOUS_STATES = new HashMap<>();
+	private static final Map<String, Integer> PREVIOUS_STATES = new HashMap<>();
+
+	private static final Map<Session, String> sessionBlockchain = Collections.synchronizedMap(new HashMap<>());
 
 	@Override
 	public void configure(WebSocketServletFactory factory) {
@@ -42,7 +45,7 @@ public class TradeBotWebSocket extends ApiWebSocket implements Listener {
 				// How do we properly fail here?
 				return;
 
-			PREVIOUS_STATES.putAll(tradeBotEntries.stream().collect(Collectors.toMap(entry -> Base58.encode(entry.getTradePrivateKey()), TradeBotData::getState)));
+			PREVIOUS_STATES.putAll(tradeBotEntries.stream().collect(Collectors.toMap(entry -> Base58.encode(entry.getTradePrivateKey()), TradeBotData::getStateValue)));
 		} catch (DataException e) {
 			// No output this time
 		}
@@ -59,35 +62,59 @@ public class TradeBotWebSocket extends ApiWebSocket implements Listener {
 		String tradePrivateKey58 = Base58.encode(tradeBotData.getTradePrivateKey());
 
 		synchronized (PREVIOUS_STATES) {
-			if (PREVIOUS_STATES.get(tradePrivateKey58) == tradeBotData.getState())
+			Integer previousStateValue = PREVIOUS_STATES.get(tradePrivateKey58);
+			if (previousStateValue != null && previousStateValue == tradeBotData.getStateValue())
 				// Not changed
 				return;
 
-			PREVIOUS_STATES.put(tradePrivateKey58, tradeBotData.getState());
+			PREVIOUS_STATES.put(tradePrivateKey58, tradeBotData.getStateValue());
 		}
 
 		List<TradeBotData> tradeBotEntries = Collections.singletonList(tradeBotData);
-		for (Session session : getSessions())
-			sendEntries(session, tradeBotEntries);
+
+		for (Session session : getSessions()) {
+			// Only send if this session has this/no preferred blockchain
+			String preferredBlockchain = sessionBlockchain.get(session);
+
+			if (preferredBlockchain == null || preferredBlockchain.equals(tradeBotData.getForeignBlockchain()))
+				sendEntries(session, tradeBotEntries);
+		}
 	}
 
 	@OnWebSocketConnect
 	@Override
 	public void onWebSocketConnect(Session session) {
+		Map<String, List<String>> queryParams = session.getUpgradeRequest().getParameterMap();
+
+		List<String> foreignBlockchains = queryParams.get("foreignBlockchain");
+		final String foreignBlockchain = foreignBlockchains == null ? null : foreignBlockchains.get(0);
+
+		// Make sure blockchain (if any) is valid
+		if (foreignBlockchain != null && SupportedBlockchain.fromString(foreignBlockchain) == null) {
+			session.close(4003, "unknown blockchain: " + foreignBlockchain);
+			return;
+		}
+
+		// save session's preferred blockchain (if any)
+		sessionBlockchain.put(session, foreignBlockchain);
+
 		// Send all known trade-bot entries
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			List<TradeBotData> tradeBotEntries = repository.getCrossChainRepository().getAllTradeBotData();
-			if (tradeBotEntries == null) {
-				session.close(4001, "repository issue fetching trade-bot entries");
-				return;
-			}
+
+			// Optional filtering
+			if (foreignBlockchain != null)
+				tradeBotEntries = tradeBotEntries.stream()
+						.filter(tradeBotData -> tradeBotData.getForeignBlockchain().equals(foreignBlockchain))
+						.collect(Collectors.toList());
 
 			if (!sendEntries(session, tradeBotEntries)) {
 				session.close(4002, "websocket issue");
 				return;
 			}
 		} catch (DataException e) {
-			// No output this time
+			session.close(4001, "repository issue fetching trade-bot entries");
+			return;
 		}
 
 		super.onWebSocketConnect(session);
@@ -96,6 +123,9 @@ public class TradeBotWebSocket extends ApiWebSocket implements Listener {
 	@OnWebSocketClose
 	@Override
 	public void onWebSocketClose(Session session, int statusCode, String reason) {
+		// clean up
+		sessionBlockchain.remove(session);
+
 		super.onWebSocketClose(session, statusCode, reason);
 	}
 

src/main/java/org/qortal/api/websocket/TradeOffersWebSocket.java

@@ -3,10 +3,13 @@ package org.qortal.api.websocket;
 import java.io.IOException;
 import java.io.StringWriter;
 import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.function.Predicate;
+import java.util.function.Supplier;
 import java.util.stream.Collectors;
 
 import org.apache.logging.log4j.LogManager;
@@ -20,7 +23,9 @@ import org.eclipse.jetty.websocket.api.annotations.WebSocket;
 import org.eclipse.jetty.websocket.servlet.WebSocketServletFactory;
 import org.qortal.api.model.CrossChainOfferSummary;
 import org.qortal.controller.Controller;
-import org.qortal.crosschain.BTCACCT;
+import org.qortal.crosschain.SupportedBlockchain;
+import org.qortal.crosschain.ACCT;
+import org.qortal.crosschain.AcctMode;
 import org.qortal.data.at.ATStateData;
 import org.qortal.data.block.BlockData;
 import org.qortal.data.crosschain.CrossChainTradeData;
@@ -30,6 +35,7 @@ import org.qortal.event.Listener;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryManager;
+import org.qortal.utils.ByteArray;
 import org.qortal.utils.NTP;
 
 @WebSocket
@@ -38,18 +44,23 @@ public class TradeOffersWebSocket extends ApiWebSocket implements Listener {
 
 	private static final Logger LOGGER = LogManager.getLogger(TradeOffersWebSocket.class);
 
-	private static final Map<String, BTCACCT.Mode> previousAtModes = new HashMap<>();
+	private static class CachedOfferInfo {
+		public final Map<String, AcctMode> previousAtModes = new HashMap<>();
 
-	// OFFERING
-	private static final Map<String, CrossChainOfferSummary> currentSummaries = new HashMap<>();
-	// REDEEMED/REFUNDED/CANCELLED
-	private static final Map<String, CrossChainOfferSummary> historicSummaries = new HashMap<>();
+		// OFFERING
+		public final Map<String, CrossChainOfferSummary> currentSummaries = new HashMap<>();
+		// REDEEMED/REFUNDED/CANCELLED
+		public final Map<String, CrossChainOfferSummary> historicSummaries = new HashMap<>();
+	}
+	// Manual synchronization
+	private static final Map<String, CachedOfferInfo> cachedInfoByBlockchain = new HashMap<>();
 
 	private static final Predicate<CrossChainOfferSummary> isHistoric = offerSummary
-			-> offerSummary.getMode() == BTCACCT.Mode.REDEEMED
-			|| offerSummary.getMode() == BTCACCT.Mode.REFUNDED
-			|| offerSummary.getMode() == BTCACCT.Mode.CANCELLED;
+			-> offerSummary.getMode() == AcctMode.REDEEMED
+			|| offerSummary.getMode() == AcctMode.REFUNDED
+			|| offerSummary.getMode() == AcctMode.CANCELLED;
 
+	private static final Map<Session, String> sessionBlockchain = Collections.synchronizedMap(new HashMap<>());
 
 	@Override
 	public void configure(WebSocketServletFactory factory) {
@@ -75,7 +86,6 @@ public class TradeOffersWebSocket extends ApiWebSocket implements Listener {
 		BlockData blockData = ((Controller.NewBlockEvent) event).getBlockData();
 
 		// Process any new info
-		List<CrossChainOfferSummary> crossChainOfferSummaries;
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			// Find any new/changed trade ATs since this block
@@ -84,60 +94,77 @@ public class TradeOffersWebSocket extends ApiWebSocket implements Listener {
 			final Long expectedValue = null;
 			final Integer minimumFinalHeight = blockData.getHeight();
 
-			List<ATStateData> atStates = repository.getATRepository().getMatchingFinalATStates(BTCACCT.CODE_BYTES_HASH,
-					isFinished, dataByteOffset, expectedValue, minimumFinalHeight,
-					null, null, null);
+			for (SupportedBlockchain blockchain : SupportedBlockchain.values()) {
+				Map<ByteArray, Supplier<ACCT>> acctsByCodeHash = SupportedBlockchain.getFilteredAcctMap(blockchain);
 
-			if (atStates == null)
-				return;
+				List<CrossChainOfferSummary> crossChainOfferSummaries = new ArrayList<>();
 
-			crossChainOfferSummaries = produceSummaries(repository, atStates, blockData.getTimestamp());
+				synchronized (cachedInfoByBlockchain) {
+					CachedOfferInfo cachedInfo = cachedInfoByBlockchain.computeIfAbsent(blockchain.name(), k -> new CachedOfferInfo());
+
+					for (Map.Entry<ByteArray, Supplier<ACCT>> acctInfo : acctsByCodeHash.entrySet()) {
+						byte[] codeHash = acctInfo.getKey().value;
+						ACCT acct = acctInfo.getValue().get();
+
+						List<ATStateData> atStates = repository.getATRepository().getMatchingFinalATStates(codeHash,
+								isFinished, dataByteOffset, expectedValue, minimumFinalHeight,
+								null, null, null);
+
+						crossChainOfferSummaries.addAll(produceSummaries(repository, acct, atStates, blockData.getTimestamp()));
+					}
+
+					// Remove any entries unchanged from last time
+					crossChainOfferSummaries.removeIf(offerSummary -> cachedInfo.previousAtModes.get(offerSummary.getQortalAtAddress()) == offerSummary.getMode());
+
+					// Skip to next blockchain if nothing has changed (for this blockchain)
+					if (crossChainOfferSummaries.isEmpty())
+						continue;
+
+					// Update
+					for (CrossChainOfferSummary offerSummary : crossChainOfferSummaries) {
+						String offerAtAddress = offerSummary.getQortalAtAddress();
+
+						cachedInfo.previousAtModes.put(offerAtAddress, offerSummary.getMode());
+						LOGGER.trace(() -> String.format("Block height: %d, AT: %s, mode: %s", blockData.getHeight(), offerAtAddress, offerSummary.getMode().name()));
+
+						switch (offerSummary.getMode()) {
+							case OFFERING:
+								cachedInfo.currentSummaries.put(offerAtAddress, offerSummary);
+								cachedInfo.historicSummaries.remove(offerAtAddress);
+								break;
+
+							case REDEEMED:
+							case REFUNDED:
+							case CANCELLED:
+								cachedInfo.currentSummaries.remove(offerAtAddress);
+								cachedInfo.historicSummaries.put(offerAtAddress, offerSummary);
+								break;
+
+							case TRADING:
+								cachedInfo.currentSummaries.remove(offerAtAddress);
+								cachedInfo.historicSummaries.remove(offerAtAddress);
+								break;
+						}
+					}
+
+					// Remove any historic offers that are over 24 hours old
+					final long tooOldTimestamp = NTP.getTime() - 24 * 60 * 60 * 1000L;
+					cachedInfo.historicSummaries.values().removeIf(historicSummary -> historicSummary.getTimestamp() < tooOldTimestamp);
+				}
+
+				// Notify sessions
+				for (Session session : getSessions()) {
+					// Only send if this session has this/no preferred blockchain
+					String preferredBlockchain = sessionBlockchain.get(session);
+
+					if (preferredBlockchain == null || preferredBlockchain.equals(blockchain.name()))
+						sendOfferSummaries(session, crossChainOfferSummaries);
+				}
+
+			}
 		} catch (DataException e) {
 			// No output this time
-			return;
 		}
-
-		synchronized (previousAtModes) {
-			// Remove any entries unchanged from last time
-			crossChainOfferSummaries.removeIf(offerSummary -> previousAtModes.get(offerSummary.getQortalAtAddress()) == offerSummary.getMode());
-
-			// Don't send anything if no results
-			if (crossChainOfferSummaries.isEmpty())
-				return;
-
-			// Update
-			for (CrossChainOfferSummary offerSummary : crossChainOfferSummaries) {
-				previousAtModes.put(offerSummary.qortalAtAddress, offerSummary.getMode());
-				LOGGER.trace(() -> String.format("Block height: %d, AT: %s, mode: %s", blockData.getHeight(), offerSummary.qortalAtAddress, offerSummary.getMode().name()));
-
-				switch (offerSummary.getMode()) {
-					case OFFERING:
-						currentSummaries.put(offerSummary.qortalAtAddress, offerSummary);
-						historicSummaries.remove(offerSummary.qortalAtAddress);
-						break;
-
-					case REDEEMED:
-					case REFUNDED:
-					case CANCELLED:
-						currentSummaries.remove(offerSummary.qortalAtAddress);
-						historicSummaries.put(offerSummary.qortalAtAddress, offerSummary);
-						break;
-
-					case TRADING:
-						currentSummaries.remove(offerSummary.qortalAtAddress);
-						historicSummaries.remove(offerSummary.qortalAtAddress);
-						break;
-				}
-			}
-
-			// Remove any historic offers that are over 24 hours old
-			final long tooOldTimestamp = NTP.getTime() - 24 * 60 * 60 * 1000L;
-			historicSummaries.values().removeIf(historicSummary -> historicSummary.getTimestamp() < tooOldTimestamp);
-		}
-
-		// Notify sessions
-		for (Session session : getSessions())
-			sendOfferSummaries(session, crossChainOfferSummaries);
 	}
 
 	@OnWebSocketConnect
@@ -146,13 +173,36 @@ public class TradeOffersWebSocket extends ApiWebSocket implements Listener {
 		Map<String, List<String>> queryParams = session.getUpgradeRequest().getParameterMap();
 		final boolean includeHistoric = queryParams.get("includeHistoric") != null;
 
+		List<String> foreignBlockchains = queryParams.get("foreignBlockchain");
+		final String foreignBlockchain = foreignBlockchains == null ? null : foreignBlockchains.get(0);
+
+		// Make sure blockchain (if any) is valid
+		if (foreignBlockchain != null && SupportedBlockchain.fromString(foreignBlockchain) == null) {
+			session.close(4003, "unknown blockchain: " + foreignBlockchain);
+			return;
+		}
+
+		// Save session's preferred blockchain, if given
+		if (foreignBlockchain != null)
+			sessionBlockchain.put(session, foreignBlockchain);
+
 		List<CrossChainOfferSummary> crossChainOfferSummaries = new ArrayList<>();
 
-		synchronized (previousAtModes) {
-			crossChainOfferSummaries.addAll(currentSummaries.values());
+		synchronized (cachedInfoByBlockchain) {
+			Collection<CachedOfferInfo> cachedInfos;
 
-			if (includeHistoric)
-				crossChainOfferSummaries.addAll(historicSummaries.values());
+			if (foreignBlockchain == null)
+				// No preferred blockchain, so iterate through all of them
+				cachedInfos = cachedInfoByBlockchain.values();
+			else
+				cachedInfos = Collections.singleton(cachedInfoByBlockchain.computeIfAbsent(foreignBlockchain, k -> new CachedOfferInfo()));
+
+			for (CachedOfferInfo cachedInfo : cachedInfos) {
+				crossChainOfferSummaries.addAll(cachedInfo.currentSummaries.values());
+
+				if (includeHistoric)
+					crossChainOfferSummaries.addAll(cachedInfo.historicSummaries.values());
+			}
 		}
 
 		if (!sendOfferSummaries(session, crossChainOfferSummaries)) {
@@ -166,6 +216,9 @@ public class TradeOffersWebSocket extends ApiWebSocket implements Listener {
 	@OnWebSocketClose
 	@Override
 	public void onWebSocketClose(Session session, int statusCode, String reason) {
+		// clean up
+		sessionBlockchain.remove(session);
+
 		super.onWebSocketClose(session, statusCode, reason);
 	}
 
@@ -197,22 +250,34 @@ public class TradeOffersWebSocket extends ApiWebSocket implements Listener {
 	private static void populateCurrentSummaries(Repository repository) throws DataException {
 		// We want ALL OFFERING trades
 		Boolean isFinished = Boolean.FALSE;
-		Integer dataByteOffset = BTCACCT.MODE_BYTE_OFFSET;
-		Long expectedValue = (long) BTCACCT.Mode.OFFERING.value;
+		Long expectedValue = (long) AcctMode.OFFERING.value;
 		Integer minimumFinalHeight = null;
 
-		List<ATStateData> initialAtStates = repository.getATRepository().getMatchingFinalATStates(BTCACCT.CODE_BYTES_HASH,
-				isFinished, dataByteOffset, expectedValue, minimumFinalHeight,
-				null, null, null);
+		for (SupportedBlockchain blockchain : SupportedBlockchain.values()) {
+			Map<ByteArray, Supplier<ACCT>> acctsByCodeHash = SupportedBlockchain.getFilteredAcctMap(blockchain);
 
-		if (initialAtStates == null)
-			throw new DataException("Couldn't fetch current trades from repository");
+			CachedOfferInfo cachedInfo = cachedInfoByBlockchain.computeIfAbsent(blockchain.name(), k -> new CachedOfferInfo());
 
-		// Save initial AT modes
-		previousAtModes.putAll(initialAtStates.stream().collect(Collectors.toMap(ATStateData::getATAddress, atState -> BTCACCT.Mode.OFFERING)));
+			for (Map.Entry<ByteArray, Supplier<ACCT>> acctInfo : acctsByCodeHash.entrySet()) {
+				byte[] codeHash = acctInfo.getKey().value;
+				ACCT acct = acctInfo.getValue().get();
 
-		// Convert to offer summaries
-		currentSummaries.putAll(produceSummaries(repository, initialAtStates, null).stream().collect(Collectors.toMap(CrossChainOfferSummary::getQortalAtAddress, offerSummary -> offerSummary)));
+				Integer dataByteOffset = acct.getModeByteOffset();
+				List<ATStateData> initialAtStates = repository.getATRepository().getMatchingFinalATStates(codeHash,
+					isFinished, dataByteOffset, expectedValue, minimumFinalHeight,
+					null, null, null);
+
+				if (initialAtStates == null)
+					throw new DataException("Couldn't fetch current trades from repository");
+
+				// Save initial AT modes
+				cachedInfo.previousAtModes.putAll(initialAtStates.stream().collect(Collectors.toMap(ATStateData::getATAddress, atState -> AcctMode.OFFERING)));
+
+				// Convert to offer summaries
+				cachedInfo.currentSummaries.putAll(produceSummaries(repository, acct, initialAtStates, null).stream()
+										.collect(Collectors.toMap(CrossChainOfferSummary::getQortalAtAddress, offerSummary -> offerSummary)));
+			}
+		}
 	}
 
 	private static void populateHistoricSummaries(Repository repository) throws DataException {
@@ -228,33 +293,44 @@ public class TradeOffersWebSocket extends ApiWebSocket implements Listener {
 		Long expectedValue = null;
 		++minimumFinalHeight; // because height is just *before* timestamp
 
-		List<ATStateData> historicAtStates = repository.getATRepository().getMatchingFinalATStates(BTCACCT.CODE_BYTES_HASH,
-				isFinished, dataByteOffset, expectedValue, minimumFinalHeight,
-				null, null, null);
+		for (SupportedBlockchain blockchain : SupportedBlockchain.values()) {
+			Map<ByteArray, Supplier<ACCT>> acctsByCodeHash = SupportedBlockchain.getFilteredAcctMap(blockchain);
 
-		if (historicAtStates == null)
-			throw new DataException("Couldn't fetch historic trades from repository");
+			CachedOfferInfo cachedInfo = cachedInfoByBlockchain.computeIfAbsent(blockchain.name(), k -> new CachedOfferInfo());
 
-		for (ATStateData historicAtState : historicAtStates) {
-			CrossChainOfferSummary historicOfferSummary = produceSummary(repository, historicAtState, null);
+			for (Map.Entry<ByteArray, Supplier<ACCT>> acctInfo : acctsByCodeHash.entrySet()) {
+				byte[] codeHash = acctInfo.getKey().value;
+				ACCT acct = acctInfo.getValue().get();
 
-			if (!isHistoric.test(historicOfferSummary))
-				continue;
+				List<ATStateData> historicAtStates = repository.getATRepository().getMatchingFinalATStates(codeHash,
+					isFinished, dataByteOffset, expectedValue, minimumFinalHeight,
+					null, null, null);
 
-			// Add summary to initial burst
-			historicSummaries.put(historicOfferSummary.getQortalAtAddress(), historicOfferSummary);
+				if (historicAtStates == null)
+					throw new DataException("Couldn't fetch historic trades from repository");
 
-			// Save initial AT mode
-			previousAtModes.put(historicOfferSummary.getQortalAtAddress(), historicOfferSummary.getMode());
+				for (ATStateData historicAtState : historicAtStates) {
+					CrossChainOfferSummary historicOfferSummary = produceSummary(repository, acct, historicAtState, null);
+
+					if (!isHistoric.test(historicOfferSummary))
+						continue;
+
+					// Add summary to initial burst
+					cachedInfo.historicSummaries.put(historicOfferSummary.getQortalAtAddress(), historicOfferSummary);
+
+					// Save initial AT mode
+					cachedInfo.previousAtModes.put(historicOfferSummary.getQortalAtAddress(), historicOfferSummary.getMode());
+				}
+			}
 		}
 	}
 
-	private static CrossChainOfferSummary produceSummary(Repository repository, ATStateData atState, Long timestamp) throws DataException {
-		CrossChainTradeData crossChainTradeData = BTCACCT.populateTradeData(repository, atState);
+	private static CrossChainOfferSummary produceSummary(Repository repository, ACCT acct, ATStateData atState, Long timestamp) throws DataException {
+		CrossChainTradeData crossChainTradeData = acct.populateTradeData(repository, atState);
 
 		long atStateTimestamp;
 
-		if (crossChainTradeData.mode == BTCACCT.Mode.OFFERING)
+		if (crossChainTradeData.mode == AcctMode.OFFERING)
 			// We want when trade was created, not when it was last updated
 			atStateTimestamp = crossChainTradeData.creationTimestamp;
 		else
@@ -263,11 +339,11 @@ public class TradeOffersWebSocket extends ApiWebSocket implements Listener {
 		return new CrossChainOfferSummary(crossChainTradeData, atStateTimestamp);
 	}
 
-	private static List<CrossChainOfferSummary> produceSummaries(Repository repository, List<ATStateData> atStates, Long timestamp) throws DataException {
+	private static List<CrossChainOfferSummary> produceSummaries(Repository repository, ACCT acct, List<ATStateData> atStates, Long timestamp) throws DataException {
 		List<CrossChainOfferSummary> offerSummaries = new ArrayList<>();
 
 		for (ATStateData atState : atStates)
-			offerSummaries.add(produceSummary(repository, atState, timestamp));
+			offerSummaries.add(produceSummary(repository, acct, atState, timestamp));
 
 		return offerSummaries;
 	}

src/main/java/org/qortal/at/AT.java

@@ -1,5 +1,7 @@
 package org.qortal.at;
 
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 import org.ciyam.at.MachineState;
@@ -56,12 +58,12 @@ public class AT {
 
 		this.atData = new ATData(atAddress, creatorPublicKey, creation, machineState.version, assetId, codeBytes, codeHash,
 				machineState.isSleeping(), machineState.getSleepUntilHeight(), machineState.isFinished(), machineState.hadFatalError(),
-				machineState.isFrozen(), machineState.getFrozenBalance());
+				machineState.isFrozen(), machineState.getFrozenBalance(), null);
 
 		byte[] stateData = machineState.toBytes();
 		byte[] stateHash = Crypto.digest(stateData);
 
-		this.atStateData = new ATStateData(atAddress, height, stateData, stateHash, 0L, true);
+		this.atStateData = new ATStateData(atAddress, height, stateData, stateHash, 0L, true, null);
 	}
 
 	// Getters / setters
@@ -84,13 +86,28 @@ public class AT {
 		this.repository.getATRepository().delete(this.atData.getATAddress());
 	}
 
+	/**
+	 * Potentially execute AT.
+	 * <p>
+	 * Note that sleep-until-message support might set/reset
+	 * sleep-related flags/values.
+	 * <p>
+	 * {@link #getATStateData()} will return null if nothing happened.
+	 * <p>
+	 * @param blockHeight
+	 * @param blockTimestamp
+	 * @return AT-generated transactions, possibly empty
+	 * @throws DataException
+	 */
 	public List<AtTransaction> run(int blockHeight, long blockTimestamp) throws DataException {
 		String atAddress = this.atData.getATAddress();
 
 		QortalATAPI api = new QortalATAPI(repository, this.atData, blockTimestamp);
 		QortalAtLoggerFactory loggerFactory = QortalAtLoggerFactory.getInstance();
 
-		byte[] codeBytes = this.atData.getCodeBytes();
+		if (!api.willExecute(blockHeight))
+			// this.atStateData will be null
+			return Collections.emptyList();
 
 		// Fetch latest ATStateData for this AT
 		ATStateData latestAtStateData = this.repository.getATRepository().getLatestATState(atAddress);
@@ -100,8 +117,10 @@ public class AT {
 			throw new IllegalStateException("No previous AT state data found");
 
 		// [Re]create AT machine state using AT state data or from scratch as applicable
+		byte[] codeBytes = this.atData.getCodeBytes();
 		MachineState state = MachineState.fromBytes(api, loggerFactory, latestAtStateData.getStateData(), codeBytes);
 		try {
+			api.preExecute(state);
 			state.execute();
 		} catch (Exception e) {
 			throw new DataException(String.format("Uncaught exception while running AT '%s'", atAddress), e);
@@ -109,9 +128,18 @@ public class AT {
 
 		byte[] stateData = state.toBytes();
 		byte[] stateHash = Crypto.digest(stateData);
-		long atFees = api.calcFinalFees(state);
 
-		this.atStateData = new ATStateData(atAddress, blockHeight, stateData, stateHash, atFees, false);
+		// Nothing happened?
+		if (state.getSteps() == 0 && Arrays.equals(stateHash, latestAtStateData.getStateHash()))
+			// We currently want to execute frozen ATs, to maintain backwards support.
+			if (state.isFrozen() == false)
+				// this.atStateData will be null
+				return Collections.emptyList();
+
+		long atFees = api.calcFinalFees(state);
+		Long sleepUntilMessageTimestamp = this.atData.getSleepUntilMessageTimestamp();
+
+		this.atStateData = new ATStateData(atAddress, blockHeight, stateData, stateHash, atFees, false, sleepUntilMessageTimestamp);
 
 		return api.getTransactions();
 	}
@@ -130,6 +158,10 @@ public class AT {
 		this.atData.setHadFatalError(state.hadFatalError());
 		this.atData.setIsFrozen(state.isFrozen());
 		this.atData.setFrozenBalance(state.getFrozenBalance());
+
+		// Special sleep-until-message support
+		this.atData.setSleepUntilMessageTimestamp(this.atStateData.getSleepUntilMessageTimestamp());
+
 		this.repository.getATRepository().save(this.atData);
 	}
 
@@ -157,6 +189,10 @@ public class AT {
 		this.atData.setHadFatalError(state.hadFatalError());
 		this.atData.setIsFrozen(state.isFrozen());
 		this.atData.setFrozenBalance(state.getFrozenBalance());
+
+		// Special sleep-until-message support
+		this.atData.setSleepUntilMessageTimestamp(previousStateData.getSleepUntilMessageTimestamp());
+
 		this.repository.getATRepository().save(this.atData);
 	}
 

src/main/java/org/qortal/at/QortalATAPI.java

@@ -32,6 +32,7 @@ import org.qortal.group.Group;
 import org.qortal.repository.ATRepository;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
+import org.qortal.repository.ATRepository.NextTransactionInfo;
 import org.qortal.transaction.AtTransaction;
 import org.qortal.transaction.Transaction.TransactionType;
 import org.qortal.utils.Base58;
@@ -74,8 +75,45 @@ public class QortalATAPI extends API {
 		return this.transactions;
 	}
 
-	public long calcFinalFees(MachineState state) {
-		return state.getSteps() * this.ciyamAtSettings.feePerStep;
+	public boolean willExecute(int blockHeight) throws DataException {
+		// Sleep-until-message/height checking
+		Long sleepUntilMessageTimestamp = this.atData.getSleepUntilMessageTimestamp();
+
+		if (sleepUntilMessageTimestamp != null) {
+			// Quicker to check height, if sleep-until-height also active
+			Integer sleepUntilHeight = this.atData.getSleepUntilHeight();
+
+			boolean wakeDueToHeight = sleepUntilHeight != null && sleepUntilHeight != 0 && blockHeight >= sleepUntilHeight;
+
+			boolean wakeDueToMessage = false;
+			if (!wakeDueToHeight) {
+				// No avoiding asking repository
+				Timestamp previousTxTimestamp = new Timestamp(sleepUntilMessageTimestamp);
+				NextTransactionInfo nextTransactionInfo = this.repository.getATRepository().findNextTransaction(this.atData.getATAddress(),
+						previousTxTimestamp.blockHeight,
+						previousTxTimestamp.transactionSequence);
+
+				wakeDueToMessage = nextTransactionInfo != null;
+			}
+
+			// Can we skip?
+			if (!wakeDueToHeight && !wakeDueToMessage)
+				return false;
+		}
+
+		return true;
+	}
+
+	public void preExecute(MachineState state) {
+		// Sleep-until-message/height checking
+		Long sleepUntilMessageTimestamp = this.atData.getSleepUntilMessageTimestamp();
+
+		if (sleepUntilMessageTimestamp != null) {
+			// We've passed checks, so clear sleep-related flags/values
+			this.setIsSleeping(state, false);
+			this.setSleepUntilHeight(state, 0);
+			this.atData.setSleepUntilMessageTimestamp(null);
+		}
 	}
 
 	// Inherited methods from CIYAM AT API
@@ -146,7 +184,11 @@ public class QortalATAPI extends API {
 		String atAddress = this.atData.getATAddress();
 
 		int height = timestamp.blockHeight;
-		int sequence = timestamp.transactionSequence + 1;
+		int sequence = timestamp.transactionSequence;
+
+		if (state.getCurrentBlockHeight() < BlockChain.getInstance().getAtFindNextTransactionFixHeight())
+			// Off-by-one bug still in effect
+			sequence += 1;
 
 		ATRepository.NextTransactionInfo nextTransactionInfo;
 		try {
@@ -408,6 +450,10 @@ public class QortalATAPI extends API {
 
 	// Utility methods
 
+	public long calcFinalFees(MachineState state) {
+		return state.getSteps() * this.ciyamAtSettings.feePerStep;
+	}
+
 	/** Returns partial transaction signature, used to verify we're operating on the same transaction and not naively using block height & sequence. */
 	public static byte[] partialSignature(byte[] fullSignature) {
 		return Arrays.copyOfRange(fullSignature, 8, 32);
@@ -456,6 +502,15 @@ public class QortalATAPI extends API {
 		}
 	}
 
+	/*package*/ void sleepUntilMessageOrHeight(MachineState state, long txTimestamp, Long sleepUntilHeight) {
+		this.setIsSleeping(state, true);
+
+		this.atData.setSleepUntilMessageTimestamp(txTimestamp);
+
+		if (sleepUntilHeight != null)
+			this.setSleepUntilHeight(state, sleepUntilHeight.intValue());
+	}
+
 	/** Returns AT's account */
 	/* package */ Account getATAccount() {
 		return new Account(this.repository, this.atData.getATAddress());

src/main/java/org/qortal/at/QortalFunctionCode.java

@@ -10,7 +10,7 @@ import org.ciyam.at.ExecutionException;
 import org.ciyam.at.FunctionData;
 import org.ciyam.at.IllegalFunctionCodeException;
 import org.ciyam.at.MachineState;
-import org.qortal.crosschain.BTC;
+import org.qortal.crosschain.Bitcoin;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.transaction.TransactionData;
 import org.qortal.settings.Settings;
@@ -84,6 +84,43 @@ public enum QortalFunctionCode {
 			api.setB(state, bBytes);
 		}
 	},
+	/**
+	 * Sleep AT until a new message arrives after 'tx-timestamp'.<br>
+	 * <tt>0x0503 tx-timestamp</tt>
+	 */
+	SLEEP_UNTIL_MESSAGE(0x0503, 1, false) {
+		@Override
+		protected void postCheckExecute(FunctionData functionData, MachineState state, short rawFunctionCode) throws ExecutionException {
+			if (functionData.value1 <= 0)
+				return;
+
+			long txTimestamp = functionData.value1;
+
+			QortalATAPI api = (QortalATAPI) state.getAPI();
+			api.sleepUntilMessageOrHeight(state, txTimestamp, null);
+		}
+	},
+	/**
+	 * Sleep AT until a new message arrives, after 'tx-timestamp', or height reached.<br>
+	 * <tt>0x0504 tx-timestamp height</tt>
+	 */
+	SLEEP_UNTIL_MESSAGE_OR_HEIGHT(0x0504, 2, false) {
+		@Override
+		protected void postCheckExecute(FunctionData functionData, MachineState state, short rawFunctionCode) throws ExecutionException {
+			if (functionData.value1 <= 0)
+				return;
+
+			long txTimestamp = functionData.value1;
+
+			if (functionData.value2 <= 0)
+				return;
+
+			long sleepUntilHeight = functionData.value2;
+
+			QortalATAPI api = (QortalATAPI) state.getAPI();
+			api.sleepUntilMessageOrHeight(state, txTimestamp, sleepUntilHeight);
+		}
+	},
 	/**
 	 * Convert address in B to 20-byte value in LSB of B1, and all of B2 & B3.<br>
 	 * <tt>0x0510</tt>
@@ -108,7 +145,7 @@ public enum QortalFunctionCode {
 	CONVERT_B_TO_P2SH(0x0511, 0, false) {
 		@Override
 		protected void postCheckExecute(FunctionData functionData, MachineState state, short rawFunctionCode) throws ExecutionException {
-			byte addressPrefix = Settings.getInstance().getBitcoinNet() == BTC.BitcoinNet.MAIN ? 0x05 : (byte) 0xc4;
+			byte addressPrefix = Settings.getInstance().getBitcoinNet() == Bitcoin.BitcoinNet.MAIN ? 0x05 : (byte) 0xc4;
 
 			convertAddressInB(addressPrefix, state);
 		}

src/main/java/org/qortal/block/Block.java

@@ -28,7 +28,7 @@ import org.qortal.asset.Asset;
 import org.qortal.at.AT;
 import org.qortal.block.BlockChain.BlockTimingByHeight;
 import org.qortal.block.BlockChain.AccountLevelShareBin;
-import org.qortal.controller.Controller;
+import org.qortal.controller.OnlineAccountsManager;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.account.AccountBalanceData;
 import org.qortal.data.account.AccountData;
@@ -176,19 +176,26 @@ public class Block {
 		 * 
 		 *  @return account-level share "bin" from blockchain config, or null if founder / none found
 		 */
-		public AccountLevelShareBin getShareBin() {
+		public AccountLevelShareBin getShareBin(int blockHeight) {
 			if (this.isMinterFounder)
 				return null;
 
 			final int accountLevel = this.mintingAccountData.getLevel();
 			if (accountLevel <= 0)
-					return null;
+				return null; // level 0 isn't included in any share bins
 
-			final AccountLevelShareBin[] shareBinsByLevel = BlockChain.getInstance().getShareBinsByAccountLevel();
+			final BlockChain blockChain = BlockChain.getInstance();
+			final AccountLevelShareBin[] shareBinsByLevel = blockChain.getShareBinsByAccountLevel();
 			if (accountLevel > shareBinsByLevel.length)
 				return null;
 
-			return shareBinsByLevel[accountLevel];
+			if (blockHeight < blockChain.getShareBinFixHeight())
+				// Off-by-one bug still in effect
+				return shareBinsByLevel[accountLevel];
+
+			// level 1 stored at index 0, level 2 stored at index 1, etc.
+			return shareBinsByLevel[accountLevel-1];
+
 		}
 
 		public long distribute(long accountAmount, Map<String, Long> balanceChanges) {
@@ -225,7 +232,7 @@ public class Block {
 
 	// Other useful constants
 
-	private static final BigInteger MAX_DISTANCE;
+	public static final BigInteger MAX_DISTANCE;
 	static {
 		byte[] maxValue = new byte[Transformer.PUBLIC_KEY_LENGTH];
 		Arrays.fill(maxValue, (byte) 0xFF);
@@ -313,7 +320,7 @@ public class Block {
 		byte[] reference = parentBlockData.getSignature();
 
 		// Fetch our list of online accounts
-		List<OnlineAccountData> onlineAccounts = Controller.getInstance().getOnlineAccounts();
+		List<OnlineAccountData> onlineAccounts = OnlineAccountsManager.getInstance().getOnlineAccounts();
 		if (onlineAccounts.isEmpty()) {
 			LOGGER.error("No online accounts - not even our own?");
 			return null;
@@ -357,7 +364,7 @@ public class Block {
 			System.arraycopy(onlineAccountData.getSignature(), 0, onlineAccountsSignatures, i * Transformer.SIGNATURE_LENGTH, Transformer.SIGNATURE_LENGTH);
 		}
 
-		byte[] minterSignature = minter.sign(BlockTransformer.getBytesForMinterSignature(parentBlockData.getMinterSignature(),
+		byte[] minterSignature = minter.sign(BlockTransformer.getBytesForMinterSignature(parentBlockData,
 				minter.getPublicKey(), encodedOnlineAccounts));
 
 		// Qortal: minter is always a reward-share, so find actual minter and get their effective minting level
@@ -424,7 +431,7 @@ public class Block {
 		int version = this.blockData.getVersion();
 		byte[] reference = this.blockData.getReference();
 
-		byte[] minterSignature = minter.sign(BlockTransformer.getBytesForMinterSignature(parentBlockData.getMinterSignature(),
+		byte[] minterSignature = minter.sign(BlockTransformer.getBytesForMinterSignature(parentBlockData,
 				minter.getPublicKey(), this.blockData.getEncodedOnlineAccounts()));
 
 		// Qortal: minter is always a reward-share, so find actual minter and get their effective minting level
@@ -738,11 +745,7 @@ public class Block {
 		if (!(this.minter instanceof PrivateKeyAccount))
 			throw new IllegalStateException("Block's minter is not a PrivateKeyAccount - can't sign!");
 
-		try {
-			this.blockData.setMinterSignature(((PrivateKeyAccount) this.minter).sign(BlockTransformer.getBytesForMinterSignature(this.blockData)));
-		} catch (TransformationException e) {
-			throw new RuntimeException("Unable to calculate block's minter signature", e);
-		}
+		this.blockData.setMinterSignature(((PrivateKeyAccount) this.minter).sign(BlockTransformer.getBytesForMinterSignature(this.blockData)));
 	}
 
 	/**
@@ -793,7 +796,9 @@ public class Block {
 		NumberFormat formatter = new DecimalFormat("0.###E0");
 		boolean isLogging = LOGGER.getLevel().isLessSpecificThan(Level.TRACE);
 
+		int blockCount = 0;
 		for (BlockSummaryData blockSummaryData : blockSummaries) {
+			blockCount++;
 			StringBuilder stringBuilder = isLogging ? new StringBuilder(512) : null;
 
 			if (isLogging)
@@ -822,11 +827,11 @@ public class Block {
 			parentHeight = blockSummaryData.getHeight();
 			parentBlockSignature = blockSummaryData.getSignature();
 
-			/* Potential future consensus change: only comparing the same number of blocks.
-			if (parentHeight >= maxHeight)
+			// After this timestamp, we only compare the same number of blocks
+			if (NTP.getTime() >= BlockChain.getInstance().getCalcChainWeightTimestamp() && parentHeight >= maxHeight)
 				break;
-			*/
 		}
+		LOGGER.trace(String.format("Chain weight calculation was based on %d blocks", blockCount));
 
 		return cumulativeWeight;
 	}
@@ -971,10 +976,10 @@ public class Block {
 		byte[] onlineTimestampBytes = Longs.toByteArray(onlineTimestamp);
 
 		// If this block is much older than current online timestamp, then there's no point checking current online accounts
-		List<OnlineAccountData> currentOnlineAccounts = onlineTimestamp < NTP.getTime() - Controller.ONLINE_TIMESTAMP_MODULUS
+		List<OnlineAccountData> currentOnlineAccounts = onlineTimestamp < NTP.getTime() - OnlineAccountsManager.ONLINE_TIMESTAMP_MODULUS
 				? null
-				: Controller.getInstance().getOnlineAccounts();
-		List<OnlineAccountData> latestBlocksOnlineAccounts = Controller.getInstance().getLatestBlocksOnlineAccounts();
+				: OnlineAccountsManager.getInstance().getOnlineAccounts();
+		List<OnlineAccountData> latestBlocksOnlineAccounts = OnlineAccountsManager.getInstance().getLatestBlocksOnlineAccounts();
 
 		// Extract online accounts' timestamp signatures from block data
 		List<byte[]> onlineAccountsSignatures = BlockTransformer.decodeTimestampSignatures(this.blockData.getOnlineAccountsSignatures());
@@ -1087,9 +1092,14 @@ public class Block {
 			// Create repository savepoint here so we can rollback to it after testing transactions
 			repository.setSavepoint();
 
-			if (this.blockData.getHeight() == 212937)
+			if (this.blockData.getHeight() == 212937) {
 				// Apply fix for block 212937 but fix will be rolled back before we exit method
 				Block212937.processFix(this);
+			}
+			else if (InvalidNameRegistrationBlocks.isAffectedBlock(this.blockData.getHeight())) {
+				// Apply fix for affected name registration blocks, but fix will be rolled back before we exit method
+				InvalidNameRegistrationBlocks.processFix(this);
+			}
 
 			for (Transaction transaction : this.getTransactions()) {
 				TransactionData transactionData = transaction.getTransactionData();
@@ -1128,7 +1138,7 @@ public class Block {
 				// Check transaction can even be processed
 				validationResult = transaction.isProcessable();
 				if (validationResult != Transaction.ValidationResult.OK) {
-					LOGGER.debug(String.format("Error during transaction validation, tx %s: %s", Base58.encode(transactionData.getSignature()), validationResult.name()));
+					LOGGER.info(String.format("Error during transaction validation, tx %s: %s", Base58.encode(transactionData.getSignature()), validationResult.name()));
 					return ValidationResult.TRANSACTION_INVALID;
 				}
 
@@ -1242,12 +1252,13 @@ public class Block {
 		for (ATData atData : executableATs) {
 			AT at = new AT(this.repository, atData);
 			List<AtTransaction> atTransactions = at.run(this.blockData.getHeight(), this.blockData.getTimestamp());
+			ATStateData atStateData = at.getATStateData();
+			// Didn't execute? (e.g. sleeping)
+			if (atStateData == null)
+				continue;
 
 			allAtTransactions.addAll(atTransactions);
-
-			ATStateData atStateData = at.getATStateData();
 			this.ourAtStates.add(atStateData);
-
 			this.ourAtFees += atStateData.getFees();
 		}
 
@@ -1276,6 +1287,21 @@ public class Block {
 		return mintingAccount.canMint();
 	}
 
+	/**
+	 * Pre-process block, and its transactions.
+	 * This allows for any database integrity checks prior to validation.
+	 * This is called before isValid() and process()
+	 *
+	 * @throws DataException
+	 */
+	public void preProcess() throws DataException {
+		List<Transaction> blocksTransactions = this.getTransactions();
+
+		for (Transaction transaction : blocksTransactions) {
+			transaction.preProcess();
+		}
+	}
+
 	/**
 	 * Process block, and its transactions, adding them to the blockchain.
 	 * 
@@ -1331,7 +1357,10 @@ public class Block {
 		postBlockTidy();
 
 		// Give Controller our cached, valid online accounts data (if any) to help reduce CPU load for next block
-		Controller.getInstance().pushLatestBlocksOnlineAccounts(this.cachedValidOnlineAccounts);
+		OnlineAccountsManager.getInstance().pushLatestBlocksOnlineAccounts(this.cachedValidOnlineAccounts);
+
+		// Log some debugging info relating to the block weight calculation
+		this.logDebugInfo();
 	}
 
 	protected void increaseAccountLevels() throws DataException {
@@ -1513,6 +1542,9 @@ public class Block {
 	public void orphan() throws DataException {
 		LOGGER.trace(() -> String.format("Orphaning block %d", this.blockData.getHeight()));
 
+		// Log some debugging info relating to the block weight calculation
+		this.logDebugInfo();
+
 		// Return AT fees and delete AT states from repository
 		orphanAtFeesAndStates();
 
@@ -1543,8 +1575,8 @@ public class Block {
 
 		postBlockTidy();
 
-		// Remove any cached, valid online accounts data from Controller
-		Controller.getInstance().popLatestBlocksOnlineAccounts();
+		// Remove any cached, valid online accounts data from OnlineAccountsManager
+		OnlineAccountsManager.getInstance().popLatestBlocksOnlineAccounts();
 	}
 
 	protected void orphanTransactionsFromBlock() throws DataException {
@@ -1787,7 +1819,7 @@ public class Block {
 			// Find all accounts in share bin. getShareBin() returns null for minter accounts that are also founders, so they are effectively filtered out.
 			AccountLevelShareBin accountLevelShareBin = accountLevelShareBins.get(binIndex);
 			// Object reference compare is OK as all references are read-only from blockchain config.
-			List<ExpandedAccount> binnedAccounts = expandedAccounts.stream().filter(accountInfo -> accountInfo.getShareBin() == accountLevelShareBin).collect(Collectors.toList());
+			List<ExpandedAccount> binnedAccounts = expandedAccounts.stream().filter(accountInfo -> accountInfo.getShareBin(this.blockData.getHeight()) == accountLevelShareBin).collect(Collectors.toList());
 
 			// No online accounts in this bin? Skip to next one
 			if (binnedAccounts.isEmpty())
@@ -1985,4 +2017,38 @@ public class Block {
 		this.repository.getAccountRepository().tidy();
 	}
 
+	private void logDebugInfo() {
+		try {
+			// Avoid calculations if possible. We have to check against INFO here, since Level.isMoreSpecificThan() confusingly uses <= rather than just <
+			if (LOGGER.getLevel().isMoreSpecificThan(Level.INFO))
+				return;
+
+			if (this.repository == null || this.getMinter() == null || this.getBlockData() == null)
+				return;
+
+			int minterLevel = Account.getRewardShareEffectiveMintingLevel(this.repository, this.getMinter().getPublicKey());
+
+			LOGGER.debug(String.format("======= BLOCK %d (%.8s) =======", this.getBlockData().getHeight(), Base58.encode(this.getSignature())));
+			LOGGER.debug(String.format("Timestamp: %d", this.getBlockData().getTimestamp()));
+			LOGGER.debug(String.format("Minter level: %d", minterLevel));
+			LOGGER.debug(String.format("Online accounts: %d", this.getBlockData().getOnlineAccountsCount()));
+			LOGGER.debug(String.format("AT count: %d", this.getBlockData().getATCount()));
+
+			BlockSummaryData blockSummaryData = new BlockSummaryData(this.getBlockData());
+			if (this.getParent() == null || this.getParent().getSignature() == null || blockSummaryData == null || minterLevel == 0)
+				return;
+
+			blockSummaryData.setMinterLevel(minterLevel);
+			BigInteger blockWeight = calcBlockWeight(this.getParent().getHeight(), this.getParent().getSignature(), blockSummaryData);
+			BigInteger keyDistance = calcKeyDistance(this.getParent().getHeight(), this.getParent().getSignature(), blockSummaryData.getMinterPublicKey(), blockSummaryData.getMinterLevel());
+			NumberFormat formatter = new DecimalFormat("0.###E0");
+
+			LOGGER.debug(String.format("Key distance: %s", formatter.format(keyDistance)));
+			LOGGER.debug(String.format("Weight: %s", formatter.format(blockWeight)));
+
+		} catch (DataException e) {
+			LOGGER.info(() -> String.format("Unable to log block debugging info: %s", e.getMessage()));
+		}
+	}
+
 }

src/main/java/org/qortal/block/BlockChain.java

@@ -4,10 +4,7 @@ import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.InputStream;
 import java.sql.SQLException;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 import java.util.concurrent.locks.ReentrantLock;
 
 import javax.xml.bind.JAXBContext;
@@ -27,11 +24,9 @@ import org.eclipse.persistence.jaxb.UnmarshallerProperties;
 import org.qortal.controller.Controller;
 import org.qortal.data.block.BlockData;
 import org.qortal.network.Network;
-import org.qortal.repository.BlockRepository;
-import org.qortal.repository.DataException;
-import org.qortal.repository.Repository;
-import org.qortal.repository.RepositoryManager;
+import org.qortal.repository.*;
 import org.qortal.settings.Settings;
+import org.qortal.utils.Base58;
 import org.qortal.utils.StringLongMapXmlAdapter;
 
 /**
@@ -70,6 +65,10 @@ public class BlockChain {
 	private GenesisBlock.GenesisInfo genesisInfo;
 
 	public enum FeatureTrigger {
+		atFindNextTransactionFix,
+		newBlockSigHeight,
+		shareBinFix,
+		calcChainWeightTimestamp;
 	}
 
 	/** Map of which blockchain features are enabled when (height/timestamp) */
@@ -371,6 +370,22 @@ public class BlockChain {
 
 	// Convenience methods for specific blockchain feature triggers
 
+	public int getAtFindNextTransactionFixHeight() {
+		return this.featureTriggers.get(FeatureTrigger.atFindNextTransactionFix.name()).intValue();
+	}
+
+	public int getNewBlockSigHeight() {
+		return this.featureTriggers.get(FeatureTrigger.newBlockSigHeight.name()).intValue();
+	}
+
+	public int getShareBinFixHeight() {
+		return this.featureTriggers.get(FeatureTrigger.shareBinFix.name()).intValue();
+	}
+
+	public long getCalcChainWeightTimestamp() {
+		return this.featureTriggers.get(FeatureTrigger.calcChainWeightTimestamp.name()).longValue();
+	}
+
 	// More complex getters for aspects that change by height or timestamp
 
 	public long getRewardAtHeight(int ourHeight) {
@@ -486,29 +501,105 @@ public class BlockChain {
 	 * @throws SQLException
 	 */
 	public static void validate() throws DataException {
-		// Check first block is Genesis Block
-		if (!isGenesisBlockValid())
-			rebuildBlockchain();
 
+		boolean isTopOnly = Settings.getInstance().isTopOnly();
+		boolean archiveEnabled = Settings.getInstance().isArchiveEnabled();
+		boolean canBootstrap = Settings.getInstance().getBootstrap();
+		boolean needsArchiveRebuild = false;
+		BlockData chainTip;
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			chainTip = repository.getBlockRepository().getLastBlock();
+
+			// Ensure archive is (at least partially) intact, and force a bootstrap if it isn't
+			if (!isTopOnly && archiveEnabled && canBootstrap) {
+				needsArchiveRebuild = (repository.getBlockArchiveRepository().fromHeight(2) == null);
+				if (needsArchiveRebuild) {
+					LOGGER.info("Couldn't retrieve block 2 from archive. Bootstrapping...");
+
+					// If there are minting accounts, make sure to back them up
+					// Don't backup if there are no minting accounts, as this can cause problems
+					if (!repository.getAccountRepository().getMintingAccounts().isEmpty()) {
+						Controller.getInstance().exportRepositoryData();
+					}
+				}
+			}
+		}
+
+		boolean hasBlocks = (chainTip != null && chainTip.getHeight() > 1);
+
+		if (isTopOnly && hasBlocks) {
+			// Top-only mode is enabled and we have blocks, so it's possible that the genesis block has been pruned
+			// It's best not to validate it, and there's no real need to
+		} else {
+			// Check first block is Genesis Block
+			if (!isGenesisBlockValid() || needsArchiveRebuild) {
+				try {
+					rebuildBlockchain();
+
+				} catch (InterruptedException e) {
+					throw new DataException(String.format("Interrupted when trying to rebuild blockchain: %s", e.getMessage()));
+				}
+			}
+		}
+
+		// We need to create a new connection, as the previous repository and its connections may be been
+		// closed by rebuildBlockchain() if a bootstrap was applied
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			repository.checkConsistency();
 
-			int startHeight = Math.max(repository.getBlockRepository().getBlockchainHeight() - 1440, 1);
+			// Set the number of blocks to validate based on the pruned state of the chain
+			// If pruned, subtract an extra 10 to allow room for error
+			int blocksToValidate = (isTopOnly || archiveEnabled) ? Settings.getInstance().getPruneBlockLimit() - 10 : 1440;
 
+			int startHeight = Math.max(repository.getBlockRepository().getBlockchainHeight() - blocksToValidate, 1);
 			BlockData detachedBlockData = repository.getBlockRepository().getDetachedBlockSignature(startHeight);
 
 			if (detachedBlockData != null) {
-				LOGGER.error(String.format("Block %d's reference does not match any block's signature", detachedBlockData.getHeight()));
+				LOGGER.error(String.format("Block %d's reference does not match any block's signature",
+						detachedBlockData.getHeight()));
+				LOGGER.error(String.format("Your chain may be invalid and you should consider bootstrapping" +
+						" or re-syncing from genesis."));
+			}
+		}
+	}
 
-				// Wait for blockchain lock (whereas orphan() only tries to get lock)
-				ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
-				blockchainLock.lock();
-				try {
-					LOGGER.info(String.format("Orphaning back to block %d", detachedBlockData.getHeight() - 1));
-					orphan(detachedBlockData.getHeight() - 1);
-				} finally {
-					blockchainLock.unlock();
+	/**
+	 * More thorough blockchain validation method. Useful for validating bootstraps.
+	 * A DataException is thrown if anything is invalid.
+	 *
+	 * @throws DataException
+	 */
+	public static void validateAllBlocks() throws DataException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			BlockData chainTip = repository.getBlockRepository().getLastBlock();
+			final int chainTipHeight = chainTip.getHeight();
+			final int oldestBlock = 1; // TODO: increase if in pruning mode
+			byte[] lastReference = null;
+
+			for (int height = chainTipHeight; height > oldestBlock; height--) {
+				BlockData blockData = repository.getBlockRepository().fromHeight(height);
+				if (blockData == null) {
+					blockData = repository.getBlockArchiveRepository().fromHeight(height);
 				}
+
+				if (blockData == null) {
+					String error = String.format("Missing block at height %d", height);
+					LOGGER.error(error);
+					throw new DataException(error);
+				}
+
+				if (height != chainTipHeight) {
+					// Check reference
+					if (!Arrays.equals(blockData.getSignature(), lastReference)) {
+						String error = String.format("Invalid reference for block at height %d: %s (should be %s)",
+								height, Base58.encode(blockData.getReference()), Base58.encode(lastReference));
+						LOGGER.error(error);
+						throw new DataException(error);
+					}
+				}
+
+				lastReference = blockData.getReference();
 			}
 		}
 	}
@@ -531,7 +622,15 @@ public class BlockChain {
 		}
 	}
 
-	private static void rebuildBlockchain() throws DataException {
+	private static void rebuildBlockchain() throws DataException, InterruptedException {
+		boolean shouldBootstrap = Settings.getInstance().getBootstrap();
+		if (shouldBootstrap) {
+			// Settings indicate that we should apply a bootstrap rather than rebuilding and syncing from genesis
+			Bootstrap bootstrap = new Bootstrap();
+			bootstrap.startImport();
+			return;
+		}
+
 		// (Re)build repository
 		if (!RepositoryManager.wasPristineAtOpen())
 			RepositoryManager.rebuild();

src/main/java/org/qortal/block/InvalidNameRegistrationBlocks.java

@@ -0,0 +1,114 @@
+package org.qortal.block;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.naming.Name;
+import org.qortal.repository.DataException;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Invalid Name Registration Blocks
+ * <p>
+ * A node minted a version of block 535658 that contained one transaction:
+ * a REGISTER_NAME transaction that attempted to register a name that was already registered.
+ * <p>
+ * This invalid transaction made block 535658 (rightly) invalid to several nodes,
+ * which refused to use that block.
+ * However, it seems there were no other nodes minting an alternative, valid block at that time
+ * and so the chain stalled for several nodes in the network.
+ * <p>
+ * Additionally, the invalid block 535658 affected all new installations, regardless of whether
+ * they synchronized from scratch (block 1) or used an 'official release' bootstrap.
+ * <p>
+ * The diagnosis found the following:
+ * - The original problem occurred in block 535205 where for some unknown reason many nodes didn't
+ *   add the name from a REGISTER_NAME transaction to their Names table.
+ * - As a result, those nodes had a corrupt db, because they weren't holding a record of the name.
+ * - This invalid db then caused them to treat a candidate for block 535658 as valid when it
+ *   should have been invalid.
+ * - As such, the chain continued on with a technically invalid block in it, for a subset of the network
+ * <p>
+ * As with block 212937, there were three options, but the only feasible one was to apply edits to block
+ * 535658 to make it valid. There were several cross-chain trades completed after this block, so doing
+ * any kind of rollback was out of the question.
+ * <p>
+ * To complicate things further, a custom data field was used for the first REGISTER_NAME transaction,
+ * and the default data field was used for the second. So it was important that all nodes ended up with
+ * the exact same data regardless of how they arrived there.
+ * <p>
+ * The invalid block 535658 signature is: <tt>3oiuDhok...NdXvCLEV</tt>.
+ * <p>
+ * The invalid transaction in block 212937 is:
+ * <p>
+ * <code><pre>
+	 {
+		 "type": "REGISTER_NAME",
+		 "timestamp": 1630739437517,
+		 "reference": "4peRechwSPxP6UkRj9Y8ox9YxkWb34sWk5zyMc1WyMxEsACxD4Gmm7LZVsQ6Skpze8QCSBMZasvEZg6RgdqkyADW",
+		 "fee": "0.00100000",
+		 "signature": "2t1CryCog8KPDBarzY5fDCKu499nfnUcGrz4Lz4w5wNb5nWqm7y126P48dChYY7huhufcBV3RJPkgKP4Ywxc1gXx",
+		 "txGroupId": 0,
+		 "blockHeight": 535658,
+		 "approvalStatus": "NOT_REQUIRED",
+		 "creatorAddress": "Qbx9ojxv7XNi1xDMWzzw7xDvd1zYW6SKFB",
+		 "registrantPublicKey": "HJqGEf6cW695Xun4ydhkB2excGFwsDxznhNCRHZStyyx",
+		 "name": "Qplay",
+		 "data": "Registered Name on the Qortal Chain"
+	 }
+   </pre></code>
+ * <p>
+ * Account <tt>Qbx9ojxv7XNi1xDMWzzw7xDvd1zYW6SKFB</tt> attempted to register the name <tt>Qplay</tt>
+ * when they had already registered it 12 hours before in block <tt>535205</tt>.
+ * <p>
+ * However, on the broken DB nodes, their Names table was missing a record for the `Qplay` name
+ * which was sufficient to make the transaction valid.
+ *
+ * This problem then occurred two more times, in blocks 536140 and 541334
+ * To reduce duplication, I have combined all three block fixes into a single class
+ *
+ */
+public final class InvalidNameRegistrationBlocks {
+
+	private static final Logger LOGGER = LogManager.getLogger(InvalidNameRegistrationBlocks.class);
+
+	public static Map<Integer, String> invalidBlocksNamesMap = new HashMap<Integer, String>()
+	{
+		{
+			put(535658, "Qplay");
+			put(536140, "Qweb");
+			put(541334, "Qithub");
+		}
+	};
+
+	private InvalidNameRegistrationBlocks() {
+		/* Do not instantiate */
+	}
+
+	public static boolean isAffectedBlock(int height) {
+		return (invalidBlocksNamesMap.containsKey(height));
+	}
+
+	public static void processFix(Block block) throws DataException {
+		Integer blockHeight = block.getBlockData().getHeight();
+		String invalidName = invalidBlocksNamesMap.get(blockHeight);
+		if (invalidName == null) {
+			throw new DataException(String.format("Unable to lookup invalid name for block height %d", blockHeight));
+		}
+
+		// Unregister the existing name record if it exists
+		// This ensures that the duplicate name is considered valid, and therefore
+		// the second (i.e. duplicate) REGISTER_NAME transaction data is applied.
+		// Both were issued by the same user account, so there is no conflict.
+		Name name = new Name(block.repository, invalidName);
+		name.unregister();
+
+		LOGGER.debug("Applied name registration patch for block {}", blockHeight);
+	}
+
+	// Note:
+	// There is no need to write an orphanFix() method, as we do not have
+	// the necessary ATStatesData to orphan back this far anyway
+
+}

src/main/java/org/qortal/controller/AutoUpdate.java

@@ -14,6 +14,7 @@ import java.security.NoSuchAlgorithmException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.concurrent.TimeoutException;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -215,8 +216,17 @@ public class AutoUpdate extends Thread {
 		}
 
 		// Give repository a chance to backup in case things go badly wrong (if enabled)
-		if (Settings.getInstance().getRepositoryBackupInterval() > 0)
-			RepositoryManager.backup(true);
+		if (Settings.getInstance().getRepositoryBackupInterval() > 0) {
+			try {
+				// Timeout if the database isn't ready for backing up after 60 seconds
+				long timeout = 60 * 1000L;
+				RepositoryManager.backup(true, "backup", timeout);
+
+			} catch (TimeoutException e) {
+				LOGGER.info("Attempt to backup repository failed due to timeout: {}", e.getMessage());
+				// Continue with the auto update anyway...
+			}
+		}
 
 		// Call ApplyUpdate to end this process (unlocking current JAR so it can be replaced)
 		String javaHome = System.getProperty("java.home");

src/main/java/org/qortal/controller/BlockMinter.java

@@ -16,6 +16,7 @@ import org.qortal.account.PrivateKeyAccount;
 import org.qortal.block.Block;
 import org.qortal.block.Block.ValidationResult;
 import org.qortal.block.BlockChain;
+import org.qortal.data.account.AccountData;
 import org.qortal.data.account.MintingAccountData;
 import org.qortal.data.account.RewardShareData;
 import org.qortal.data.block.BlockData;
@@ -44,6 +45,14 @@ public class BlockMinter extends Thread {
 	private static Long lastLogTimestamp;
 	private static Long logTimeout;
 
+	// Recovery
+	public static final long INVALID_BLOCK_RECOVERY_TIMEOUT = 10 * 60 * 1000L; // ms
+
+	// Min account level to submit blocks
+	// This is an unvalidated version of Blockchain.minAccountLevelToMint
+	// and exists only to reduce block candidates by default.
+	private static int MIN_LEVEL_FOR_BLOCK_SUBMISSION = 3;
+
 	// Constructors
 
 	public BlockMinter() {
@@ -100,7 +109,7 @@ public class BlockMinter extends Thread {
 					continue;
 
 				// No online accounts? (e.g. during startup)
-				if (Controller.getInstance().getOnlineAccounts().isEmpty())
+				if (OnlineAccountsManager.getInstance().getOnlineAccounts().isEmpty())
 					continue;
 
 				List<MintingAccountData> mintingAccountsData = repository.getAccountRepository().getMintingAccounts();
@@ -127,6 +136,16 @@ public class BlockMinter extends Thread {
 						madi.remove();
 						continue;
 					}
+
+					// Optional (non-validated) prevention of block submissions below a defined level
+					AccountData accountData = repository.getAccountRepository().getAccount(mintingAccount.getAddress());
+					if (accountData != null) {
+						Integer level = accountData.getLevel();
+						if (level != null && level < MIN_LEVEL_FOR_BLOCK_SUBMISSION) {
+							madi.remove();
+							continue;
+						}
+					}
 				}
 
 				List<Peer> peers = Network.getInstance().getHandshakedPeers();
@@ -135,16 +154,35 @@ public class BlockMinter extends Thread {
 				// Disregard peers that have "misbehaved" recently
 				peers.removeIf(Controller.hasMisbehaved);
 
-				// Disregard peers that don't have a recent block
-				peers.removeIf(Controller.hasNoRecentBlock);
+				// Disregard peers that don't have a recent block, but only if we're not in recovery mode.
+				// In that mode, we want to allow minting on top of older blocks, to recover stalled networks.
+				if (Controller.getInstance().getRecoveryMode() == false)
+					peers.removeIf(Controller.hasNoRecentBlock);
 
 				// Don't mint if we don't have enough up-to-date peers as where would the transactions/consensus come from?
 				if (peers.size() < Settings.getInstance().getMinBlockchainPeers())
 					continue;
 
-				// If our latest block isn't recent then we need to synchronize instead of minting.
+				// If we are stuck on an invalid block, we should allow an alternative to be minted
+				boolean recoverInvalidBlock = false;
+				if (Synchronizer.getInstance().timeInvalidBlockLastReceived != null) {
+					// We've had at least one invalid block
+					long timeSinceLastValidBlock = NTP.getTime() - Synchronizer.getInstance().timeValidBlockLastReceived;
+					long timeSinceLastInvalidBlock = NTP.getTime() - Synchronizer.getInstance().timeInvalidBlockLastReceived;
+					if (timeSinceLastValidBlock > INVALID_BLOCK_RECOVERY_TIMEOUT) {
+						if (timeSinceLastInvalidBlock < INVALID_BLOCK_RECOVERY_TIMEOUT) {
+							// Last valid block was more than 10 mins ago, but we've had an invalid block since then
+							// Assume that the chain has stalled because there is no alternative valid candidate
+							// Enter recovery mode to allow alternative, valid candidates to be minted
+							recoverInvalidBlock = true;
+						}
+					}
+				}
+
+				// If our latest block isn't recent then we need to synchronize instead of minting, unless we're in recovery mode.
 				if (!peers.isEmpty() && lastBlockData.getTimestamp() < minLatestBlockTimestamp)
-					continue;
+					if (Controller.getInstance().getRecoveryMode() == false && recoverInvalidBlock == false)
+						continue;
 
 				// There are enough peers with a recent block and our latest block is recent
 				// so go ahead and mint a block if possible.
@@ -165,6 +203,14 @@ public class BlockMinter extends Thread {
 				// Do we need to build any potential new blocks?
 				List<PrivateKeyAccount> newBlocksMintingAccounts = mintingAccountsData.stream().map(accountData -> new PrivateKeyAccount(repository, accountData.getPrivateKey())).collect(Collectors.toList());
 
+				// We might need to sit the next block out, if one of our minting accounts signed the previous one
+				final byte[] previousBlockMinter = previousBlockData.getMinterPublicKey();
+				final boolean mintedLastBlock = mintingAccountsData.stream().anyMatch(mintingAccount -> Arrays.equals(mintingAccount.getPublicKey(), previousBlockMinter));
+				if (mintedLastBlock) {
+					LOGGER.trace(String.format("One of our keys signed the last block, so we won't sign the next one"));
+					continue;
+				}
+
 				for (PrivateKeyAccount mintingAccount : newBlocksMintingAccounts) {
 					// First block does the AT heavy-lifting
 					if (newBlocks.isEmpty()) {
@@ -219,6 +265,8 @@ public class BlockMinter extends Thread {
 						if (testBlock.isTimestampValid() != ValidationResult.OK)
 							continue;
 
+						testBlock.preProcess();
+
 						// Is new block valid yet? (Before adding unconfirmed transactions)
 						ValidationResult result = testBlock.isValid();
 						if (result != ValidationResult.OK) {
@@ -282,20 +330,26 @@ public class BlockMinter extends Thread {
 						RewardShareData rewardShareData = repository.getAccountRepository().getRewardShare(newBlock.getBlockData().getMinterPublicKey());
 
 						if (rewardShareData != null) {
-							LOGGER.info(String.format("Minted block %d, sig %.8s by %s on behalf of %s",
+							LOGGER.info(String.format("Minted block %d, sig %.8s, parent sig: %.8s by %s on behalf of %s",
 									newBlock.getBlockData().getHeight(),
 									Base58.encode(newBlock.getBlockData().getSignature()),
+									Base58.encode(newBlock.getParent().getSignature()),
 									rewardShareData.getMinter(),
 									rewardShareData.getRecipient()));
 						} else {
-							LOGGER.info(String.format("Minted block %d, sig %.8s by %s",
+							LOGGER.info(String.format("Minted block %d, sig %.8s, parent sig: %.8s by %s",
 									newBlock.getBlockData().getHeight(),
 									Base58.encode(newBlock.getBlockData().getSignature()),
+									Base58.encode(newBlock.getParent().getSignature()),
 									newBlock.getMinter().getAddress()));
 						}
 
-						// Notify controller after we're released blockchain lock
+						// Notify network after we're released blockchain lock
 						newBlockMinted = true;
+
+						// Notify Controller
+						repository.discardChanges(); // clear transaction status to prevent deadlocks
+						Controller.getInstance().onNewBlock(newBlock.getBlockData());
 					} catch (DataException e) {
 						// Unable to process block - report and discard
 						LOGGER.error("Unable to process newly minted block?", e);
@@ -306,12 +360,9 @@ public class BlockMinter extends Thread {
 				}
 
 				if (newBlockMinted) {
-					// Notify Controller and broadcast our new chain to network
+					// Broadcast our new chain to network
 					BlockData newBlockData = newBlock.getBlockData();
 
-					repository.discardChanges(); // clear transaction status to prevent deadlocks
-					Controller.getInstance().onNewBlock(newBlockData);
-
 					Network network = Network.getInstance();
 					network.broadcast(broadcastPeer -> network.buildHeightMessage(broadcastPeer, newBlockData));
 				}
@@ -378,7 +429,7 @@ public class BlockMinter extends Thread {
 			throw new DataException("Ignoring attempt to mint testing block for non-test chain!");
 
 		// Ensure mintingAccount is 'online' so blocks can be minted
-		Controller.getInstance().ensureTestingAccountsOnline(mintingAndOnlineAccounts);
+		OnlineAccountsManager.getInstance().ensureTestingAccountsOnline(mintingAndOnlineAccounts);
 
 		PrivateKeyAccount mintingAccount = mintingAndOnlineAccounts[0];
 
@@ -407,7 +458,8 @@ public class BlockMinter extends Thread {
 
 			// Add to blockchain
 			newBlock.process();
-			LOGGER.info(String.format("Minted new test block: %d", newBlock.getBlockData().getHeight()));
+			LOGGER.info(String.format("Minted new test block: %d sig: %.8s",
+					newBlock.getBlockData().getHeight(), Base58.encode(newBlock.getBlockData().getSignature())));
 
 			repository.saveChanges();
 

src/main/java/org/qortal/controller/OnlineAccountsManager.java

@@ -0,0 +1,404 @@
+package org.qortal.controller;
+
+import com.google.common.primitives.Longs;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.account.Account;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.account.PublicKeyAccount;
+import org.qortal.block.BlockChain;
+import org.qortal.crypto.MemoryPoW;
+import org.qortal.data.account.MintingAccountData;
+import org.qortal.data.account.RewardShareData;
+import org.qortal.data.network.OnlineAccountData;
+import org.qortal.network.Network;
+import org.qortal.network.Peer;
+import org.qortal.network.message.GetOnlineAccountsMessage;
+import org.qortal.network.message.Message;
+import org.qortal.network.message.OnlineAccountsMessage;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+import java.util.*;
+import java.util.stream.Collectors;
+
+public class OnlineAccountsManager extends Thread {
+
+    private static final Logger LOGGER = LogManager.getLogger(OnlineAccountsManager.class);
+
+    private static OnlineAccountsManager instance;
+
+    private volatile boolean isStopping = false;
+
+    // To do with online accounts list
+    private static final long ONLINE_ACCOUNTS_TASKS_INTERVAL = 10 * 1000L; // ms
+    private static final long ONLINE_ACCOUNTS_BROADCAST_INTERVAL = 1 * 60 * 1000L; // ms
+    public static final long ONLINE_TIMESTAMP_MODULUS = 5 * 60 * 1000L;
+    private static final long LAST_SEEN_EXPIRY_PERIOD = (ONLINE_TIMESTAMP_MODULUS * 2) + (1 * 60 * 1000L);
+    /** How many (latest) blocks' worth of online accounts we cache */
+    private static final int MAX_BLOCKS_CACHED_ONLINE_ACCOUNTS = 2;
+
+    public static final int POW_BUFFER_SIZE = 8 * 1024 * 1024; // bytes
+
+    private long onlineAccountsTasksTimestamp = Controller.startTime + ONLINE_ACCOUNTS_TASKS_INTERVAL; // ms
+
+    /** Cache of current 'online accounts' */
+    List<OnlineAccountData> onlineAccounts = new ArrayList<>();
+    /** Cache of latest blocks' online accounts */
+    Deque<List<OnlineAccountData>> latestBlocksOnlineAccounts = new ArrayDeque<>(MAX_BLOCKS_CACHED_ONLINE_ACCOUNTS);
+
+    public OnlineAccountsManager() {
+
+    }
+
+    public static synchronized OnlineAccountsManager getInstance() {
+        if (instance == null) {
+            instance = new OnlineAccountsManager();
+        }
+
+        return instance;
+    }
+
+    @Override
+    public void run() {
+        Thread.currentThread().setName("Online Accounts Manager");
+
+        try {
+            while (!isStopping) {
+                Thread.sleep(2000);
+
+                int difficulty = 15;
+                long timestamp = System.currentTimeMillis();
+
+                LOGGER.info("Computing nonce at difficulty {} for timestamp {}...", difficulty, timestamp);
+
+                byte[] bytes = Longs.toByteArray(timestamp);
+                Integer nonce = MemoryPoW.compute2(bytes, POW_BUFFER_SIZE, difficulty);
+                long totalTime = System.currentTimeMillis() - timestamp;
+                double hashRate = nonce / (double)totalTime * 1000.0f;
+
+                LOGGER.info("Computed nonce: {}. Time taken: {} ms. Hashrate: {}", nonce, totalTime, hashRate);
+            }
+
+        } catch (InterruptedException e) {
+            // Fall-through to exit thread...
+        }
+    }
+
+    public void shutdown() {
+        isStopping = true;
+        this.interrupt();
+    }
+
+
+
+    public void checkOnlineAccountsTasks(long now) {
+        // Perform tasks to do with managing online accounts list
+        if (now >= onlineAccountsTasksTimestamp) {
+            onlineAccountsTasksTimestamp = now + ONLINE_ACCOUNTS_TASKS_INTERVAL;
+            performOnlineAccountsTasks();
+        }
+    }
+
+    private void sendOurOnlineAccountsInfo() {
+        final Long now = NTP.getTime();
+        if (now == null)
+            return;
+
+        List<MintingAccountData> mintingAccounts;
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            mintingAccounts = repository.getAccountRepository().getMintingAccounts();
+
+            // We have no accounts, but don't reset timestamp
+            if (mintingAccounts.isEmpty())
+                return;
+
+            // Only reward-share accounts allowed
+            Iterator<MintingAccountData> iterator = mintingAccounts.iterator();
+            while (iterator.hasNext()) {
+                MintingAccountData mintingAccountData = iterator.next();
+
+                RewardShareData rewardShareData = repository.getAccountRepository().getRewardShare(mintingAccountData.getPublicKey());
+                if (rewardShareData == null) {
+                    // Reward-share doesn't even exist - probably not a good sign
+                    iterator.remove();
+                    continue;
+                }
+
+                Account mintingAccount = new Account(repository, rewardShareData.getMinter());
+                if (!mintingAccount.canMint()) {
+                    // Minting-account component of reward-share can no longer mint - disregard
+                    iterator.remove();
+                    continue;
+                }
+            }
+        } catch (DataException e) {
+            LOGGER.warn(String.format("Repository issue trying to fetch minting accounts: %s", e.getMessage()));
+            return;
+        }
+
+        // 'current' timestamp
+        final long onlineAccountsTimestamp = OnlineAccountsManager.toOnlineAccountTimestamp(now);
+        boolean hasInfoChanged = false;
+
+        byte[] timestampBytes = Longs.toByteArray(onlineAccountsTimestamp);
+        List<OnlineAccountData> ourOnlineAccounts = new ArrayList<>();
+
+        MINTING_ACCOUNTS:
+        for (MintingAccountData mintingAccountData : mintingAccounts) {
+            PrivateKeyAccount mintingAccount = new PrivateKeyAccount(null, mintingAccountData.getPrivateKey());
+
+            byte[] signature = mintingAccount.sign(timestampBytes);
+            byte[] publicKey = mintingAccount.getPublicKey();
+
+            // Our account is online
+            OnlineAccountData ourOnlineAccountData = new OnlineAccountData(onlineAccountsTimestamp, signature, publicKey);
+            synchronized (this.onlineAccounts) {
+                Iterator<OnlineAccountData> iterator = this.onlineAccounts.iterator();
+                while (iterator.hasNext()) {
+                    OnlineAccountData existingOnlineAccountData = iterator.next();
+
+                    if (Arrays.equals(existingOnlineAccountData.getPublicKey(), ourOnlineAccountData.getPublicKey())) {
+                        // If our online account is already present, with same timestamp, then move on to next mintingAccount
+                        if (existingOnlineAccountData.getTimestamp() == onlineAccountsTimestamp)
+                            continue MINTING_ACCOUNTS;
+
+                        // If our online account is already present, but with older timestamp, then remove it
+                        iterator.remove();
+                        break;
+                    }
+                }
+
+                this.onlineAccounts.add(ourOnlineAccountData);
+            }
+
+            LOGGER.debug(() -> String.format("Added our online account %s with timestamp %d", mintingAccount.getAddress(), onlineAccountsTimestamp));
+            ourOnlineAccounts.add(ourOnlineAccountData);
+            hasInfoChanged = true;
+        }
+
+        if (!hasInfoChanged)
+            return;
+
+        Message message = new OnlineAccountsMessage(ourOnlineAccounts);
+        Network.getInstance().broadcast(peer -> message);
+
+        LOGGER.debug(()-> String.format("Broadcasted %d online account%s with timestamp %d", ourOnlineAccounts.size(), (ourOnlineAccounts.size() != 1 ? "s" : ""), onlineAccountsTimestamp));
+    }
+
+    private void performOnlineAccountsTasks() {
+        final Long now = NTP.getTime();
+        if (now == null)
+            return;
+
+        // Expire old entries
+        final long cutoffThreshold = now - LAST_SEEN_EXPIRY_PERIOD;
+        synchronized (this.onlineAccounts) {
+            Iterator<OnlineAccountData> iterator = this.onlineAccounts.iterator();
+            while (iterator.hasNext()) {
+                OnlineAccountData onlineAccountData = iterator.next();
+
+                if (onlineAccountData.getTimestamp() < cutoffThreshold) {
+                    iterator.remove();
+
+                    LOGGER.trace(() -> {
+                        PublicKeyAccount otherAccount = new PublicKeyAccount(null, onlineAccountData.getPublicKey());
+                        return String.format("Removed expired online account %s with timestamp %d", otherAccount.getAddress(), onlineAccountData.getTimestamp());
+                    });
+                }
+            }
+        }
+
+        // Request data from other peers?
+        if ((this.onlineAccountsTasksTimestamp % ONLINE_ACCOUNTS_BROADCAST_INTERVAL) < ONLINE_ACCOUNTS_TASKS_INTERVAL) {
+            Message message;
+            synchronized (this.onlineAccounts) {
+                message = new GetOnlineAccountsMessage(this.onlineAccounts);
+            }
+            Network.getInstance().broadcast(peer -> message);
+        }
+
+        // Refresh our online accounts signatures?
+        sendOurOnlineAccountsInfo();
+    }
+
+    public static long toOnlineAccountTimestamp(long timestamp) {
+        return (timestamp / ONLINE_TIMESTAMP_MODULUS) * ONLINE_TIMESTAMP_MODULUS;
+    }
+
+    /** Returns list of online accounts with timestamp recent enough to be considered currently online. */
+    public List<OnlineAccountData> getOnlineAccounts() {
+        final long onlineTimestamp = OnlineAccountsManager.toOnlineAccountTimestamp(NTP.getTime());
+
+        synchronized (this.onlineAccounts) {
+            return this.onlineAccounts.stream().filter(account -> account.getTimestamp() == onlineTimestamp).collect(Collectors.toList());
+        }
+    }
+
+    /** Returns cached, unmodifiable list of latest block's online accounts. */
+    public List<OnlineAccountData> getLatestBlocksOnlineAccounts() {
+        synchronized (this.latestBlocksOnlineAccounts) {
+            return this.latestBlocksOnlineAccounts.peekFirst();
+        }
+    }
+
+    /** Caches list of latest block's online accounts. Typically called by Block.process() */
+    public void pushLatestBlocksOnlineAccounts(List<OnlineAccountData> latestBlocksOnlineAccounts) {
+        synchronized (this.latestBlocksOnlineAccounts) {
+            if (this.latestBlocksOnlineAccounts.size() == MAX_BLOCKS_CACHED_ONLINE_ACCOUNTS)
+                this.latestBlocksOnlineAccounts.pollLast();
+
+            this.latestBlocksOnlineAccounts.addFirst(latestBlocksOnlineAccounts == null
+                    ? Collections.emptyList()
+                    : Collections.unmodifiableList(latestBlocksOnlineAccounts));
+        }
+    }
+
+    /** Reverts list of latest block's online accounts. Typically called by Block.orphan() */
+    public void popLatestBlocksOnlineAccounts() {
+        synchronized (this.latestBlocksOnlineAccounts) {
+            this.latestBlocksOnlineAccounts.pollFirst();
+        }
+    }
+
+
+    // Utilities
+
+    private void verifyAndAddAccount(Repository repository, OnlineAccountData onlineAccountData) throws DataException {
+        final Long now = NTP.getTime();
+        if (now == null)
+            return;
+
+        PublicKeyAccount otherAccount = new PublicKeyAccount(repository, onlineAccountData.getPublicKey());
+
+        // Check timestamp is 'recent' here
+        if (Math.abs(onlineAccountData.getTimestamp() - now) > ONLINE_TIMESTAMP_MODULUS * 2) {
+            LOGGER.trace(() -> String.format("Rejecting online account %s with out of range timestamp %d", otherAccount.getAddress(), onlineAccountData.getTimestamp()));
+            return;
+        }
+
+        // Verify
+        byte[] data = Longs.toByteArray(onlineAccountData.getTimestamp());
+        if (!otherAccount.verify(onlineAccountData.getSignature(), data)) {
+            LOGGER.trace(() -> String.format("Rejecting invalid online account %s", otherAccount.getAddress()));
+            return;
+        }
+
+        // Qortal: check online account is actually reward-share
+        RewardShareData rewardShareData = repository.getAccountRepository().getRewardShare(onlineAccountData.getPublicKey());
+        if (rewardShareData == null) {
+            // Reward-share doesn't even exist - probably not a good sign
+            LOGGER.trace(() -> String.format("Rejecting unknown online reward-share public key %s", Base58.encode(onlineAccountData.getPublicKey())));
+            return;
+        }
+
+        Account mintingAccount = new Account(repository, rewardShareData.getMinter());
+        if (!mintingAccount.canMint()) {
+            // Minting-account component of reward-share can no longer mint - disregard
+            LOGGER.trace(() -> String.format("Rejecting online reward-share with non-minting account %s", mintingAccount.getAddress()));
+            return;
+        }
+
+        synchronized (this.onlineAccounts) {
+            OnlineAccountData existingAccountData = this.onlineAccounts.stream().filter(account -> Arrays.equals(account.getPublicKey(), onlineAccountData.getPublicKey())).findFirst().orElse(null);
+
+            if (existingAccountData != null) {
+                if (existingAccountData.getTimestamp() < onlineAccountData.getTimestamp()) {
+                    this.onlineAccounts.remove(existingAccountData);
+
+                    LOGGER.trace(() -> String.format("Updated online account %s with timestamp %d (was %d)", otherAccount.getAddress(), onlineAccountData.getTimestamp(), existingAccountData.getTimestamp()));
+                } else {
+                    LOGGER.trace(() -> String.format("Not updating existing online account %s", otherAccount.getAddress()));
+
+                    return;
+                }
+            } else {
+                LOGGER.debug(() -> String.format("Added online account %s with timestamp %d", otherAccount.getAddress(), onlineAccountData.getTimestamp()));
+            }
+
+            this.onlineAccounts.add(onlineAccountData);
+        }
+    }
+
+    public void ensureTestingAccountsOnline(PrivateKeyAccount... onlineAccounts) {
+        if (!BlockChain.getInstance().isTestChain()) {
+            LOGGER.warn("Ignoring attempt to ensure test account is online for non-test chain!");
+            return;
+        }
+
+        final Long now = NTP.getTime();
+        if (now == null)
+            return;
+
+        final long onlineAccountsTimestamp = this.toOnlineAccountTimestamp(now);
+        byte[] timestampBytes = Longs.toByteArray(onlineAccountsTimestamp);
+
+        synchronized (this.onlineAccounts) {
+            this.onlineAccounts.clear();
+
+            for (PrivateKeyAccount onlineAccount : onlineAccounts) {
+                // Check mintingAccount is actually reward-share?
+
+                byte[] signature = onlineAccount.sign(timestampBytes);
+                byte[] publicKey = onlineAccount.getPublicKey();
+
+                OnlineAccountData ourOnlineAccountData = new OnlineAccountData(onlineAccountsTimestamp, signature, publicKey);
+                this.onlineAccounts.add(ourOnlineAccountData);
+            }
+        }
+    }
+
+
+    // Network handlers
+
+    public void onNetworkGetOnlineAccountsMessage(Peer peer, Message message) {
+        GetOnlineAccountsMessage getOnlineAccountsMessage = (GetOnlineAccountsMessage) message;
+
+        List<OnlineAccountData> excludeAccounts = getOnlineAccountsMessage.getOnlineAccounts();
+
+        // Send online accounts info, excluding entries with matching timestamp & public key from excludeAccounts
+        List<OnlineAccountData> accountsToSend;
+        synchronized (this.onlineAccounts) {
+            accountsToSend = new ArrayList<>(this.onlineAccounts);
+        }
+
+        Iterator<OnlineAccountData> iterator = accountsToSend.iterator();
+
+        SEND_ITERATOR:
+        while (iterator.hasNext()) {
+            OnlineAccountData onlineAccountData = iterator.next();
+
+            for (int i = 0; i < excludeAccounts.size(); ++i) {
+                OnlineAccountData excludeAccountData = excludeAccounts.get(i);
+
+                if (onlineAccountData.getTimestamp() == excludeAccountData.getTimestamp() && Arrays.equals(onlineAccountData.getPublicKey(), excludeAccountData.getPublicKey())) {
+                    iterator.remove();
+                    continue SEND_ITERATOR;
+                }
+            }
+        }
+
+        Message onlineAccountsMessage = new OnlineAccountsMessage(accountsToSend);
+        peer.sendMessage(onlineAccountsMessage);
+
+        LOGGER.debug(() -> String.format("Sent %d of our %d online accounts to %s", accountsToSend.size(), this.onlineAccounts.size(), peer));
+    }
+
+    public void onNetworkOnlineAccountsMessage(Peer peer, Message message) {
+        OnlineAccountsMessage onlineAccountsMessage = (OnlineAccountsMessage) message;
+
+        List<OnlineAccountData> peersOnlineAccounts = onlineAccountsMessage.getOnlineAccounts();
+        LOGGER.debug(() -> String.format("Received %d online accounts from %s", peersOnlineAccounts.size(), peer));
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            for (OnlineAccountData onlineAccountData : peersOnlineAccounts)
+                this.verifyAndAddAccount(repository, onlineAccountData);
+        } catch (DataException e) {
+            LOGGER.error(String.format("Repository issue while verifying online accounts from peer %s", peer), e);
+        }
+    }
+
+}

src/main/java/org/qortal/controller/Synchronizer.java

@@ -3,9 +3,7 @@ package org.qortal.controller;
 import java.math.BigInteger;
 import java.text.DecimalFormat;
 import java.text.NumberFormat;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.List;
+import java.util.*;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.stream.Collectors;
 
@@ -15,8 +13,10 @@ import org.qortal.account.Account;
 import org.qortal.account.PublicKeyAccount;
 import org.qortal.block.Block;
 import org.qortal.block.Block.ValidationResult;
+import org.qortal.block.BlockChain;
 import org.qortal.data.block.BlockData;
 import org.qortal.data.block.BlockSummaryData;
+import org.qortal.data.block.CommonBlockData;
 import org.qortal.data.network.PeerChainTipData;
 import org.qortal.data.transaction.RewardShareTransactionData;
 import org.qortal.data.transaction.TransactionData;
@@ -32,17 +32,37 @@ import org.qortal.network.message.Message.MessageType;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryManager;
+import org.qortal.settings.Settings;
 import org.qortal.transaction.Transaction;
 import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
 
 public class Synchronizer {
 
 	private static final Logger LOGGER = LogManager.getLogger(Synchronizer.class);
 
+	/** Max number of new blocks we aim to add to chain tip in each sync round */
+	private static final int SYNC_BATCH_SIZE = 200; // XXX move to Settings?
+
+	/** Initial jump back of block height when searching for common block with peer */
 	private static final int INITIAL_BLOCK_STEP = 8;
-	private static final int MAXIMUM_BLOCK_STEP = 500;
+	/** Maximum jump back of block height when searching for common block with peer */
+	private static final int MAXIMUM_BLOCK_STEP = 128;
+
+	/** Maximum difference in block height between tip and peer's common block before peer is considered TOO DIVERGENT */
 	private static final int MAXIMUM_COMMON_DELTA = 240; // XXX move to Settings?
-	private static final int SYNC_BATCH_SIZE = 200;
+
+	/** Maximum number of block signatures we ask from peer in one go */
+	private static final int MAXIMUM_REQUEST_SIZE = 200; // XXX move to Settings?
+
+
+	// Keep track of the size of the last re-org, so it can be logged
+	private int lastReorgSize;
+
+	// Keep track of invalid blocks so that we don't keep trying to sync them
+	private Map<String, Long> invalidBlockSignatures = Collections.synchronizedMap(new HashMap<>());
+	public Long timeValidBlockLastReceived = null;
+	public Long timeInvalidBlockLastReceived = null;
 
 	private static Synchronizer instance;
 
@@ -62,6 +82,477 @@ public class Synchronizer {
 		return instance;
 	}
 
+
+	/**
+	 * Iterate through a list of supplied peers, and attempt to find our common block with each.
+	 * If a common block is found, its summary will be retained in the peer's commonBlockSummary property, for processing later.
+	 * <p>
+	 * Will return <tt>SynchronizationResult.OK</tt> on success.
+	 * <p>
+	 * @param peers
+	 * @return SynchronizationResult.OK if the process completed successfully, or a different SynchronizationResult if something went wrong.
+	 * @throws InterruptedException
+	 */
+	public SynchronizationResult findCommonBlocksWithPeers(List<Peer> peers) throws InterruptedException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			try {
+
+				if (peers.size() == 0)
+					return SynchronizationResult.NOTHING_TO_DO;
+
+				// If our latest block is very old, it's best that we don't try and determine the best peers to sync to.
+				// This is because it can involve very large chain comparisons, which is too intensive.
+				// In reality, most forking problems occur near the chain tips, so we will reserve this functionality for those situations.
+				final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
+				if (minLatestBlockTimestamp == null)
+					return SynchronizationResult.REPOSITORY_ISSUE;
+
+				final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
+				if (ourLatestBlockData.getTimestamp() < minLatestBlockTimestamp) {
+					LOGGER.debug(String.format("Our latest block is very old, so we won't collect common block info from peers"));
+					return SynchronizationResult.NOTHING_TO_DO;
+				}
+
+				LOGGER.debug(String.format("Searching for common blocks with %d peers...", peers.size()));
+				final long startTime = System.currentTimeMillis();
+				int commonBlocksFound = 0;
+				boolean wereNewRequestsMade = false;
+
+				for (Peer peer : peers) {
+					// Are we shutting down?
+					if (Controller.isStopping())
+						return SynchronizationResult.SHUTTING_DOWN;
+
+					// Check if we can use the cached common block data, by comparing the peer's current chain tip against the peer's chain tip when we last found our common block
+					if (peer.canUseCachedCommonBlockData()) {
+						LOGGER.debug(String.format("Skipping peer %s because we already have the latest common block data in our cache. Cached common block sig is %.08s", peer, Base58.encode(peer.getCommonBlockData().getCommonBlockSummary().getSignature())));
+						commonBlocksFound++;
+						continue;
+					}
+
+					// Cached data is stale, so clear it and repopulate
+					peer.setCommonBlockData(null);
+
+					// Search for the common block
+					Synchronizer.getInstance().findCommonBlockWithPeer(peer, repository);
+					if (peer.getCommonBlockData() != null)
+						commonBlocksFound++;
+
+					// This round wasn't served entirely from the cache, so we may want to log the results
+					wereNewRequestsMade = true;
+				}
+
+				if (wereNewRequestsMade) {
+					final long totalTimeTaken = System.currentTimeMillis() - startTime;
+					LOGGER.debug(String.format("Finished searching for common blocks with %d peer%s. Found: %d. Total time taken: %d ms", peers.size(), (peers.size() != 1 ? "s" : ""), commonBlocksFound, totalTimeTaken));
+				}
+
+				return SynchronizationResult.OK;
+			} finally {
+				repository.discardChanges(); // Free repository locks, if any, also in case anything went wrong
+			}
+		} catch (DataException e) {
+			LOGGER.error("Repository issue during synchronization with peer", e);
+			return SynchronizationResult.REPOSITORY_ISSUE;
+		}
+	}
+
+	/**
+	 * Attempt to find the find our common block with supplied peer.
+	 * If a common block is found, its summary will be retained in the peer's commonBlockSummary property, for processing later.
+	 * <p>
+	 * Will return <tt>SynchronizationResult.OK</tt> on success.
+	 * <p>
+	 * @param peer
+	 * @param repository
+	 * @return SynchronizationResult.OK if the process completed successfully, or a different SynchronizationResult if something went wrong.
+	 * @throws InterruptedException
+	 */
+	public SynchronizationResult findCommonBlockWithPeer(Peer peer, Repository repository) throws InterruptedException {
+		try {
+			final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
+			final int ourInitialHeight = ourLatestBlockData.getHeight();
+
+			PeerChainTipData peerChainTipData = peer.getChainTipData();
+			int peerHeight = peerChainTipData.getLastHeight();
+			byte[] peersLastBlockSignature = peerChainTipData.getLastBlockSignature();
+
+			byte[] ourLastBlockSignature = ourLatestBlockData.getSignature();
+			LOGGER.debug(String.format("Fetching summaries from peer %s at height %d, sig %.8s, ts %d; our height %d, sig %.8s, ts %d", peer,
+					peerHeight, Base58.encode(peersLastBlockSignature), peer.getChainTipData().getLastBlockTimestamp(),
+					ourInitialHeight, Base58.encode(ourLastBlockSignature), ourLatestBlockData.getTimestamp()));
+
+			List<BlockSummaryData> peerBlockSummaries = new ArrayList<>();
+			SynchronizationResult findCommonBlockResult = fetchSummariesFromCommonBlock(repository, peer, ourInitialHeight, false, peerBlockSummaries, false);
+			if (findCommonBlockResult != SynchronizationResult.OK) {
+				// Logging performed by fetchSummariesFromCommonBlock() above
+				peer.setCommonBlockData(null);
+				return findCommonBlockResult;
+			}
+
+			// First summary is common block
+			final BlockData commonBlockData = repository.getBlockRepository().fromSignature(peerBlockSummaries.get(0).getSignature());
+			final BlockSummaryData commonBlockSummary = new BlockSummaryData(commonBlockData);
+			final int commonBlockHeight = commonBlockData.getHeight();
+			final byte[] commonBlockSig = commonBlockData.getSignature();
+			final String commonBlockSig58 = Base58.encode(commonBlockSig);
+			LOGGER.debug(String.format("Common block with peer %s is at height %d, sig %.8s, ts %d", peer,
+					commonBlockHeight, commonBlockSig58, commonBlockData.getTimestamp()));
+			peerBlockSummaries.remove(0);
+
+			// Store the common block summary against the peer, and the current chain tip (for caching)
+			peer.setCommonBlockData(new CommonBlockData(commonBlockSummary, peerChainTipData));
+
+			return SynchronizationResult.OK;
+		} catch (DataException e) {
+			LOGGER.error("Repository issue during synchronization with peer", e);
+			return SynchronizationResult.REPOSITORY_ISSUE;
+		}
+	}
+
+
+	/**
+	 * Compare a list of peers to determine the best peer(s) to sync to next.
+	 * <p>
+	 * Will return a filtered list of peers on success, or an identical list of peers on failure.
+	 * This allows us to fall back to legacy behaviour (random selection from the entire list of peers), if we are unable to make the comparison.
+	 * <p>
+	 * @param peers
+	 * @return a list of peers, possibly filtered.
+	 * @throws InterruptedException
+	 */
+	public List<Peer> comparePeers(List<Peer> peers) throws InterruptedException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			try {
+
+				// If our latest block is very old, it's best that we don't try and determine the best peers to sync to.
+				// This is because it can involve very large chain comparisons, which is too intensive.
+				// In reality, most forking problems occur near the chain tips, so we will reserve this functionality for those situations.
+				final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
+				if (minLatestBlockTimestamp == null)
+					return peers;
+
+				final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
+				if (ourLatestBlockData.getTimestamp() < minLatestBlockTimestamp) {
+					LOGGER.debug(String.format("Our latest block is very old, so we won't filter the peers list"));
+					return peers;
+				}
+
+				// We will switch to a new chain weight consensus algorithm at a hard fork, so determine if this has happened yet
+				boolean usingSameLengthChainWeight = (NTP.getTime() >= BlockChain.getInstance().getCalcChainWeightTimestamp());
+				LOGGER.debug(String.format("Using %s chain weight consensus algorithm", (usingSameLengthChainWeight ? "same-length" : "variable-length")));
+
+				// Retrieve a list of unique common blocks from this list of peers
+				List<BlockSummaryData> commonBlocks = this.uniqueCommonBlocks(peers);
+
+				// Order common blocks by height, in ascending order
+				// This is essential for the logic below to make the correct decisions when discarding chains - do not remove
+				commonBlocks.sort((b1, b2) -> Integer.valueOf(b1.getHeight()).compareTo(Integer.valueOf(b2.getHeight())));
+
+				// Get our latest height
+				final int ourHeight = ourLatestBlockData.getHeight();
+
+				// Create a placeholder to track of common blocks that we can discard due to being inferior chains
+				int dropPeersAfterCommonBlockHeight = 0;
+
+				// Remove peers with no common block data
+				Iterator iterator = peers.iterator();
+				while (iterator.hasNext()) {
+					Peer peer = (Peer) iterator.next();
+					if (peer.getCommonBlockData() == null) {
+						LOGGER.debug(String.format("Removed peer %s because it has no common block data", peer));
+						iterator.remove();
+					}
+				}
+
+				// Loop through each group of common blocks
+				for (BlockSummaryData commonBlockSummary : commonBlocks) {
+					List<Peer> peersSharingCommonBlock = peers.stream().filter(peer -> peer.getCommonBlockData().getCommonBlockSummary().equals(commonBlockSummary)).collect(Collectors.toList());
+
+					// Check if we need to discard this group of peers
+					if (dropPeersAfterCommonBlockHeight > 0) {
+						if (commonBlockSummary.getHeight() > dropPeersAfterCommonBlockHeight) {
+							// We have already determined that the correct chain diverged from a lower height. We are safe to skip these peers.
+							for (Peer peer : peersSharingCommonBlock) {
+								LOGGER.debug(String.format("Peer %s has common block at height %d but the superior chain is at height %d. Removing it from this round.", peer, commonBlockSummary.getHeight(), dropPeersAfterCommonBlockHeight));
+								Controller.getInstance().addInferiorChainSignature(peer.getChainTipData().getLastBlockSignature());
+							}
+							continue;
+						}
+					}
+
+					// Calculate the length of the shortest peer chain sharing this common block, including our chain
+					final int ourAdditionalBlocksAfterCommonBlock = ourHeight - commonBlockSummary.getHeight();
+					int minChainLength = this.calculateMinChainLengthOfPeers(peersSharingCommonBlock, commonBlockSummary);
+
+					// Fetch block summaries from each peer
+					for (Peer peer : peersSharingCommonBlock) {
+
+						// If we're shutting down, just return the latest peer list
+						if (Controller.isStopping())
+							return peers;
+
+						// Count the number of blocks this peer has beyond our common block
+						final PeerChainTipData peerChainTipData = peer.getChainTipData();
+						final int peerHeight = peerChainTipData.getLastHeight();
+						final byte[] peerLastBlockSignature = peerChainTipData.getLastBlockSignature();
+						final int peerAdditionalBlocksAfterCommonBlock = peerHeight - commonBlockSummary.getHeight();
+						// Limit the number of blocks we are comparing. FUTURE: we could request more in batches, but there may not be a case when this is needed
+						int summariesRequired = Math.min(peerAdditionalBlocksAfterCommonBlock, MAXIMUM_REQUEST_SIZE);
+
+						// Check if we can use the cached common block summaries, by comparing the peer's current chain tip against the peer's chain tip when we last found our common block
+						boolean useCachedSummaries = false;
+						if (peer.canUseCachedCommonBlockData()) {
+							if (peer.getCommonBlockData().getBlockSummariesAfterCommonBlock() != null) {
+								if (peer.getCommonBlockData().getBlockSummariesAfterCommonBlock().size() == summariesRequired) {
+									LOGGER.trace(String.format("Using cached block summaries for peer %s", peer));
+									useCachedSummaries = true;
+								}
+							}
+						}
+
+						if (useCachedSummaries == false) {
+							if (summariesRequired > 0) {
+								LOGGER.trace(String.format("Requesting %d block summar%s from peer %s after common block %.8s. Peer height: %d", summariesRequired, (summariesRequired != 1 ? "ies" : "y"), peer, Base58.encode(commonBlockSummary.getSignature()), peerHeight));
+
+								// Forget any cached summaries
+								peer.getCommonBlockData().setBlockSummariesAfterCommonBlock(null);
+
+								// Request new block summaries
+								List<BlockSummaryData> blockSummaries = this.getBlockSummaries(peer, commonBlockSummary.getSignature(), summariesRequired);
+								if (blockSummaries != null) {
+									LOGGER.trace(String.format("Peer %s returned %d block summar%s", peer, blockSummaries.size(), (blockSummaries.size() != 1 ? "ies" : "y")));
+
+									if (blockSummaries.size() < summariesRequired)
+										// This could mean that the peer has re-orged. Exclude this peer until they return the summaries we expect.
+										LOGGER.debug(String.format("Peer %s returned %d block summar%s instead of expected %d - excluding them from this round", peer, blockSummaries.size(), (blockSummaries.size() != 1 ? "ies" : "y"), summariesRequired));
+									else if (blockSummaryWithSignature(peerLastBlockSignature, blockSummaries) == null)
+										// We don't have a block summary for the peer's reported chain tip, so should exclude it
+										LOGGER.debug(String.format("Peer %s didn't return a block summary with signature %.8s - excluding them from this round", peer, Base58.encode(peerLastBlockSignature)));
+									else
+										// All looks good, so store the retrieved block summaries in the peer's cache
+										peer.getCommonBlockData().setBlockSummariesAfterCommonBlock(blockSummaries);
+								}
+							} else {
+								// There are no block summaries after this common block
+								peer.getCommonBlockData().setBlockSummariesAfterCommonBlock(null);
+							}
+						}
+
+						// Ignore this peer if it holds an invalid block
+						if (this.containsInvalidBlockSummary(peer.getCommonBlockData().getBlockSummariesAfterCommonBlock())) {
+							LOGGER.debug("Ignoring peer %s because it holds an invalid block", peer);
+							peers.remove(peer);
+						}
+
+						// Reduce minChainLength if needed. If we don't have any blocks, this peer will be excluded from chain weight comparisons later in the process, so we shouldn't update minChainLength
+						List <BlockSummaryData> peerBlockSummaries = peer.getCommonBlockData().getBlockSummariesAfterCommonBlock();
+						if (peerBlockSummaries != null && peerBlockSummaries.size() > 0)
+							if (peerBlockSummaries.size() < minChainLength)
+								minChainLength = peerBlockSummaries.size();
+					}
+
+					// Fetch our corresponding block summaries. Limit to MAXIMUM_REQUEST_SIZE, in order to make the comparison fairer, as peers have been limited too
+					final int ourSummariesRequired = Math.min(ourAdditionalBlocksAfterCommonBlock, MAXIMUM_REQUEST_SIZE);
+					LOGGER.trace(String.format("About to fetch our block summaries from %d to %d. Our height: %d", commonBlockSummary.getHeight() + 1, commonBlockSummary.getHeight() + ourSummariesRequired, ourHeight));
+					List<BlockSummaryData> ourBlockSummaries = repository.getBlockRepository().getBlockSummaries(commonBlockSummary.getHeight() + 1, commonBlockSummary.getHeight() + ourSummariesRequired);
+					if (ourBlockSummaries.isEmpty()) {
+						LOGGER.debug(String.format("We don't have any block summaries so can't compare our chain against peers with this common block. We can still compare them against each other."));
+					}
+					else {
+						populateBlockSummariesMinterLevels(repository, ourBlockSummaries);
+						// Reduce minChainLength if we have less summaries
+						if (ourBlockSummaries.size() < minChainLength)
+							minChainLength = ourBlockSummaries.size();
+					}
+
+					// Create array to hold peers for comparison
+					List<Peer> superiorPeersForComparison = new ArrayList<>();
+
+					// Calculate max height for chain weight comparisons
+					int maxHeightForChainWeightComparisons = commonBlockSummary.getHeight() + minChainLength;
+
+					// Calculate our chain weight
+					BigInteger ourChainWeight = BigInteger.valueOf(0);
+					if (ourBlockSummaries.size() > 0)
+						ourChainWeight = Block.calcChainWeight(commonBlockSummary.getHeight(), commonBlockSummary.getSignature(), ourBlockSummaries, maxHeightForChainWeightComparisons);
+
+					NumberFormat formatter = new DecimalFormat("0.###E0");
+					NumberFormat accurateFormatter = new DecimalFormat("0.################E0");
+					LOGGER.debug(String.format("Our chain weight based on %d blocks is %s", (usingSameLengthChainWeight ? minChainLength : ourBlockSummaries.size()), formatter.format(ourChainWeight)));
+
+					LOGGER.debug(String.format("Listing peers with common block %.8s...", Base58.encode(commonBlockSummary.getSignature())));
+					for (Peer peer : peersSharingCommonBlock) {
+						final int peerHeight = peer.getChainTipData().getLastHeight();
+						final int peerAdditionalBlocksAfterCommonBlock = peerHeight - commonBlockSummary.getHeight();
+						final CommonBlockData peerCommonBlockData = peer.getCommonBlockData();
+
+						if (peerCommonBlockData == null || peerCommonBlockData.getBlockSummariesAfterCommonBlock() == null || peerCommonBlockData.getBlockSummariesAfterCommonBlock().isEmpty()) {
+							// No response - remove this peer for now
+							LOGGER.debug(String.format("Peer %s doesn't have any block summaries - removing it from this round", peer));
+							peers.remove(peer);
+							continue;
+						}
+
+						final List<BlockSummaryData> peerBlockSummariesAfterCommonBlock = peerCommonBlockData.getBlockSummariesAfterCommonBlock();
+						populateBlockSummariesMinterLevels(repository, peerBlockSummariesAfterCommonBlock);
+
+						// Calculate cumulative chain weight of this blockchain subset, from common block to highest mutual block held by all peers in this group.
+						LOGGER.debug(String.format("About to calculate chain weight based on %d blocks for peer %s with common block %.8s (peer has %d blocks after common block)", (usingSameLengthChainWeight ? minChainLength : peerBlockSummariesAfterCommonBlock.size()), peer, Base58.encode(commonBlockSummary.getSignature()), peerAdditionalBlocksAfterCommonBlock));
+						BigInteger peerChainWeight = Block.calcChainWeight(commonBlockSummary.getHeight(), commonBlockSummary.getSignature(), peerBlockSummariesAfterCommonBlock, maxHeightForChainWeightComparisons);
+						peer.getCommonBlockData().setChainWeight(peerChainWeight);
+						LOGGER.debug(String.format("Chain weight of peer %s based on %d blocks (%d - %d) is %s", peer, (usingSameLengthChainWeight ? minChainLength : peerBlockSummariesAfterCommonBlock.size()), peerBlockSummariesAfterCommonBlock.get(0).getHeight(), peerBlockSummariesAfterCommonBlock.get(peerBlockSummariesAfterCommonBlock.size()-1).getHeight(), formatter.format(peerChainWeight)));
+
+						// Compare against our chain - if our blockchain has greater weight then don't synchronize with peer (or any others in this group)
+						if (ourChainWeight.compareTo(peerChainWeight) > 0) {
+							// This peer is on an inferior chain - remove it
+							LOGGER.debug(String.format("Peer %s is on an inferior chain to us - removing it from this round", peer));
+							peers.remove(peer);
+						}
+						else {
+							// Our chain is inferior or equal
+							LOGGER.debug(String.format("Peer %s is on an equal or better chain to us. We will compare the other peers sharing this common block against each other, and drop all peers sharing higher common blocks.", peer));
+							dropPeersAfterCommonBlockHeight = commonBlockSummary.getHeight();
+							superiorPeersForComparison.add(peer);
+						}
+					}
+
+					// Now that we have selected the best peers, compare them against each other and remove any with lower weights
+					if (superiorPeersForComparison.size() > 0) {
+						BigInteger bestChainWeight = null;
+						for (Peer peer : superiorPeersForComparison) {
+							// Increase bestChainWeight if needed
+							if (bestChainWeight == null || peer.getCommonBlockData().getChainWeight().compareTo(bestChainWeight) >= 0)
+								bestChainWeight = peer.getCommonBlockData().getChainWeight();
+						}
+						for (Peer peer : superiorPeersForComparison) {
+							// Check if we should discard an inferior peer
+							if (peer.getCommonBlockData().getChainWeight().compareTo(bestChainWeight) < 0) {
+								BigInteger difference = bestChainWeight.subtract(peer.getCommonBlockData().getChainWeight());
+								LOGGER.debug(String.format("Peer %s has a lower chain weight (difference: %s) than other peer(s) in this group - removing it from this round.", peer, accurateFormatter.format(difference)));
+								peers.remove(peer);
+							}
+						}
+						// FUTURE: we may want to prefer peers with additional blocks, and compare the additional blocks against each other.
+						// This would fast track us to the best candidate for the latest block.
+						// Right now, peers with the exact same chain as us are treated equally to those with an additional block.
+					}
+				}
+
+				return peers;
+			} finally {
+				repository.discardChanges(); // Free repository locks, if any, also in case anything went wrong
+			}
+		} catch (DataException e) {
+			LOGGER.error("Repository issue during peer comparison", e);
+			return peers;
+		}
+	}
+
+	private List<BlockSummaryData> uniqueCommonBlocks(List<Peer> peers) {
+		List<BlockSummaryData> commonBlocks = new ArrayList<>();
+
+		for (Peer peer : peers) {
+			if (peer.getCommonBlockData() != null && peer.getCommonBlockData().getCommonBlockSummary() != null) {
+				LOGGER.trace(String.format("Peer %s has common block %.8s", peer, Base58.encode(peer.getCommonBlockData().getCommonBlockSummary().getSignature())));
+
+				BlockSummaryData commonBlockSummary = peer.getCommonBlockData().getCommonBlockSummary();
+				if (!commonBlocks.contains(commonBlockSummary))
+					commonBlocks.add(commonBlockSummary);
+			}
+			else {
+				LOGGER.trace(String.format("Peer %s has no common block data. Skipping...", peer));
+			}
+		}
+
+		return commonBlocks;
+	}
+
+	private int calculateMinChainLengthOfPeers(List<Peer> peersSharingCommonBlock, BlockSummaryData commonBlockSummary) {
+		// Calculate the length of the shortest peer chain sharing this common block
+		int minChainLength = 0;
+		for (Peer peer : peersSharingCommonBlock) {
+			final int peerHeight = peer.getChainTipData().getLastHeight();
+			final int peerAdditionalBlocksAfterCommonBlock = peerHeight - commonBlockSummary.getHeight();
+
+			if (peerAdditionalBlocksAfterCommonBlock < minChainLength || minChainLength == 0)
+				minChainLength = peerAdditionalBlocksAfterCommonBlock;
+		}
+		return minChainLength;
+	}
+
+	private BlockSummaryData blockSummaryWithSignature(byte[] signature, List<BlockSummaryData> blockSummaries) {
+		if (blockSummaries != null)
+			return blockSummaries.stream().filter(blockSummary -> Arrays.equals(blockSummary.getSignature(), signature)).findAny().orElse(null);
+		return null;
+	}
+
+
+
+	/* Invalid block signature tracking */
+
+	private void addInvalidBlockSignature(byte[] signature) {
+		Long now = NTP.getTime();
+		if (now == null) {
+			return;
+		}
+
+		// Add or update existing entry
+		String sig58 = Base58.encode(signature);
+		invalidBlockSignatures.put(sig58, now);
+	}
+	private void deleteOlderInvalidSignatures(Long now) {
+		if (now == null) {
+			return;
+		}
+
+		// Delete signatures with older timestamps
+		Iterator it = invalidBlockSignatures.entrySet().iterator();
+		while (it.hasNext()) {
+			Map.Entry pair = (Map.Entry)it.next();
+			Long lastSeen = (Long) pair.getValue();
+
+			// Remove signature if we haven't seen it for more than 1 hour
+			if (now - lastSeen > 60 * 60 * 1000L) {
+				it.remove();
+			}
+		}
+	}
+	private boolean containsInvalidBlockSummary(List<BlockSummaryData> blockSummaries) {
+		if (blockSummaries == null || invalidBlockSignatures == null) {
+			return false;
+		}
+
+		// Loop through our known invalid blocks and check each one against supplied block summaries
+		for (String invalidSignature58 : invalidBlockSignatures.keySet()) {
+			byte[] invalidSignature = Base58.decode(invalidSignature58);
+			for (BlockSummaryData blockSummary : blockSummaries) {
+				byte[] signature = blockSummary.getSignature();
+				if (Arrays.equals(signature, invalidSignature)) {
+					return true;
+				}
+			}
+		}
+		return false;
+	}
+	private boolean containsInvalidBlockSignature(List<byte[]> blockSignatures) {
+		if (blockSignatures == null || invalidBlockSignatures == null) {
+			return false;
+		}
+
+		// Loop through our known invalid blocks and check each one against supplied block signatures
+		for (String invalidSignature58 : invalidBlockSignatures.keySet()) {
+			byte[] invalidSignature = Base58.decode(invalidSignature58);
+			for (byte[] signature : blockSignatures) {
+				if (Arrays.equals(signature, invalidSignature)) {
+					return true;
+				}
+			}
+		}
+		return false;
+	}
+
+
 	/**
 	 * Attempt to synchronize blockchain with peer.
 	 * <p>
@@ -91,15 +582,40 @@ public class Synchronizer {
 					byte[] peersLastBlockSignature = peerChainTipData.getLastBlockSignature();
 
 					byte[] ourLastBlockSignature = ourLatestBlockData.getSignature();
-					LOGGER.debug(String.format("Synchronizing with peer %s at height %d, sig %.8s, ts %d; our height %d, sig %.8s, ts %d", peer,
+					String syncString = String.format("Synchronizing with peer %s at height %d, sig %.8s, ts %d; our height %d, sig %.8s, ts %d", peer,
 							peerHeight, Base58.encode(peersLastBlockSignature), peer.getChainTipData().getLastBlockTimestamp(),
-							ourInitialHeight, Base58.encode(ourLastBlockSignature), ourLatestBlockData.getTimestamp()));
+							ourInitialHeight, Base58.encode(ourLastBlockSignature), ourLatestBlockData.getTimestamp());
+
+					// If our latest block is very old, we should log that we're attempting to sync with a peer
+					// Otherwise, it can appear as though nothing is happening for a while after launch
+					final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
+					if (minLatestBlockTimestamp != null && ourLatestBlockData.getTimestamp() < minLatestBlockTimestamp) {
+						LOGGER.info(syncString);
+					}
+					else {
+						LOGGER.debug(syncString);
+					}
+
+					// Reset last re-org size as we are starting a new sync round
+					this.lastReorgSize = 0;
+
+					// Set the initial value of timeValidBlockLastReceived if it's null
+					Long now = NTP.getTime();
+					if (this.timeValidBlockLastReceived == null) {
+						this.timeValidBlockLastReceived = now;
+					}
+
+					// Delete invalid signatures with older timestamps
+					this.deleteOlderInvalidSignatures(now);
 
 					List<BlockSummaryData> peerBlockSummaries = new ArrayList<>();
-					SynchronizationResult findCommonBlockResult = fetchSummariesFromCommonBlock(repository, peer, ourInitialHeight, force, peerBlockSummaries);
-					if (findCommonBlockResult != SynchronizationResult.OK)
+					SynchronizationResult findCommonBlockResult = fetchSummariesFromCommonBlock(repository, peer, ourInitialHeight, force, peerBlockSummaries, true);
+					if (findCommonBlockResult != SynchronizationResult.OK) {
 						// Logging performed by fetchSummariesFromCommonBlock() above
+						// Clear our common block cache for this peer
+						peer.setCommonBlockData(null);
 						return findCommonBlockResult;
+					}
 
 					// First summary is common block
 					final BlockData commonBlockData = repository.getBlockRepository().fromSignature(peerBlockSummaries.get(0).getSignature());
@@ -149,10 +665,19 @@ public class Synchronizer {
 					// Commit
 					repository.saveChanges();
 
+					// Create string for logging
 					final BlockData newLatestBlockData = repository.getBlockRepository().getLastBlock();
-					LOGGER.info(String.format("Synchronized with peer %s to height %d, sig %.8s, ts: %d", peer,
+					String syncLog = String.format("Synchronized with peer %s to height %d, sig %.8s, ts: %d", peer,
 							newLatestBlockData.getHeight(), Base58.encode(newLatestBlockData.getSignature()),
-							newLatestBlockData.getTimestamp()));
+							newLatestBlockData.getTimestamp());
+
+					// Append re-org info
+					if (this.lastReorgSize > 0) {
+						syncLog = syncLog.concat(String.format(", size: %d", this.lastReorgSize));
+					}
+
+					// Log sync info
+					LOGGER.info(syncLog);
 
 					return SynchronizationResult.OK;
 				} finally {
@@ -175,7 +700,7 @@ public class Synchronizer {
 	 * @throws DataException
 	 * @throws InterruptedException
 	 */
-	public SynchronizationResult fetchSummariesFromCommonBlock(Repository repository, Peer peer, int ourHeight, boolean force, List<BlockSummaryData> blockSummariesFromCommon) throws DataException, InterruptedException {
+	public SynchronizationResult fetchSummariesFromCommonBlock(Repository repository, Peer peer, int ourHeight, boolean force, List<BlockSummaryData> blockSummariesFromCommon, boolean infoLogWhenNotFound) throws DataException, InterruptedException {
 		// Start by asking for a few recent block hashes as this will cover a majority of reorgs
 		// Failing that, back off exponentially
 		int step = INITIAL_BLOCK_STEP;
@@ -204,8 +729,12 @@ public class Synchronizer {
 			blockSummariesBatch = this.getBlockSummaries(peer, testSignature, step);
 
 			if (blockSummariesBatch == null) {
+				if (infoLogWhenNotFound)
+					LOGGER.info(String.format("Error while trying to find common block with peer %s", peer));
+				else
+					LOGGER.debug(String.format("Error while trying to find common block with peer %s", peer));
+				
 				// No response - give up this time
-				LOGGER.info(String.format("Error while trying to find common block with peer %s", peer));
 				return SynchronizationResult.NO_REPLY;
 			}
 
@@ -244,9 +773,13 @@ public class Synchronizer {
 		// Currently we work forward from common block until we hit a block we don't have
 		// TODO: rewrite as modified binary search!
 		int i;
-		for (i = 1; i < blockSummariesFromCommon.size(); ++i)
+		for (i = 1; i < blockSummariesFromCommon.size(); ++i) {
+			if (Controller.isStopping())
+				return SynchronizationResult.SHUTTING_DOWN;
+
 			if (!repository.getBlockRepository().exists(blockSummariesFromCommon.get(i).getSignature()))
 				break;
+		}
 
 		// Note: index i - 1 isn't cleared: List.subList is fromIndex inclusive to toIndex exclusive
 		blockSummariesFromCommon.subList(0, i - 1).clear();
@@ -295,6 +828,9 @@ public class Synchronizer {
 
 				// Check peer sent valid heights
 				for (int i = 0; i < moreBlockSummaries.size(); ++i) {
+					if (Controller.isStopping())
+						return SynchronizationResult.SHUTTING_DOWN;
+
 					++lastSummaryHeight;
 
 					BlockSummaryData blockSummary = moreBlockSummaries.get(i);
@@ -316,7 +852,7 @@ public class Synchronizer {
 			populateBlockSummariesMinterLevels(repository, ourBlockSummaries);
 			populateBlockSummariesMinterLevels(repository, peerBlockSummaries);
 
-			final int mutualHeight = commonBlockHeight - 1 + Math.min(ourBlockSummaries.size(), peerBlockSummaries.size());
+			final int mutualHeight = commonBlockHeight + Math.min(ourBlockSummaries.size(), peerBlockSummaries.size());
 
 			// Calculate cumulative chain weights of both blockchain subsets, from common block to highest mutual block.
 			BigInteger ourChainWeight = Block.calcChainWeight(commonBlockHeight, commonBlockSig, ourBlockSummaries, mutualHeight);
@@ -341,52 +877,148 @@ public class Synchronizer {
 		final byte[] commonBlockSig = commonBlockData.getSignature();
 		String commonBlockSig58 = Base58.encode(commonBlockSig);
 
+		byte[] latestPeerSignature = commonBlockSig;
+		int height = commonBlockHeight;
+
 		LOGGER.debug(() -> String.format("Fetching peer %s chain from height %d, sig %.8s", peer, commonBlockHeight, commonBlockSig58));
 
-		int ourHeight = ourInitialHeight;
+		final int maxRetries = Settings.getInstance().getMaxRetries();
 
 		// Overall plan: fetch peer's blocks first, then orphan, then apply
 
 		// Convert any leftover (post-common) block summaries into signatures to request from peer
 		List<byte[]> peerBlockSignatures = peerBlockSummaries.stream().map(BlockSummaryData::getSignature).collect(Collectors.toList());
 
-		// Fetch remaining block signatures, if needed
-		int numberSignaturesRequired = peerBlockSignatures.size() - (peerHeight - commonBlockHeight);
-		if (numberSignaturesRequired > 0) {
-			byte[] latestPeerSignature = peerBlockSignatures.isEmpty() ? commonBlockSig : peerBlockSignatures.get(peerBlockSignatures.size() - 1);
-
-			LOGGER.trace(String.format("Requesting %d signature%s after height %d, sig %.8s",
-					numberSignaturesRequired, (numberSignaturesRequired != 1 ? "s": ""), ourHeight, Base58.encode(latestPeerSignature)));
-
-			List<byte[]> moreBlockSignatures = this.getBlockSignatures(peer, latestPeerSignature, numberSignaturesRequired);
-
-			if (moreBlockSignatures == null || moreBlockSignatures.isEmpty()) {
-				LOGGER.info(String.format("Peer %s failed to respond with more block signatures after height %d, sig %.8s", peer,
-						ourHeight, Base58.encode(latestPeerSignature)));
-				return SynchronizationResult.NO_REPLY;
-			}
-
-			LOGGER.trace(String.format("Received %s signature%s", peerBlockSignatures.size(), (peerBlockSignatures.size() != 1 ? "s" : "")));
-
-			peerBlockSignatures.addAll(moreBlockSignatures);
-		}
-
-		// Fetch blocks using signatures
-		LOGGER.debug(String.format("Fetching new blocks from peer %s", peer));
+		// Keep a list of blocks received so far
 		List<Block> peerBlocks = new ArrayList<>();
 
-		for (byte[] blockSignature : peerBlockSignatures) {
-			Block newBlock = this.fetchBlock(repository, peer, blockSignature);
+		// Calculate the total number of additional blocks this peer has beyond the common block
+		int additionalPeerBlocksAfterCommonBlock = peerHeight - commonBlockHeight;
+		// Subtract the number of signatures that we already have, as we don't need to request them again
+		int numberSignaturesRequired = additionalPeerBlocksAfterCommonBlock - peerBlockSignatures.size();
+
+		int retryCount = 0;
+		while (height < peerHeight) {
+			if (Controller.isStopping())
+				return SynchronizationResult.SHUTTING_DOWN;
+
+            // Ensure we don't request more than MAXIMUM_REQUEST_SIZE
+            int numberRequested = Math.min(numberSignaturesRequired, MAXIMUM_REQUEST_SIZE);
+
+            // Do we need more signatures?
+			if (peerBlockSignatures.isEmpty() && numberRequested > 0) {
+                LOGGER.trace(String.format("Requesting %d signature%s after height %d, sig %.8s",
+                        numberRequested, (numberRequested != 1 ? "s" : ""), height, Base58.encode(latestPeerSignature)));
+
+                peerBlockSignatures = this.getBlockSignatures(peer, latestPeerSignature, numberRequested);
+
+                if (peerBlockSignatures == null || peerBlockSignatures.isEmpty()) {
+                    LOGGER.info(String.format("Peer %s failed to respond with more block signatures after height %d, sig %.8s", peer,
+                            height, Base58.encode(latestPeerSignature)));
+
+					// Clear our cache of common block summaries for this peer, as they are likely to be invalid
+					CommonBlockData cachedCommonBlockData = peer.getCommonBlockData();
+					if (cachedCommonBlockData != null)
+						cachedCommonBlockData.setBlockSummariesAfterCommonBlock(null);
+
+                    // If we have already received newer blocks from this peer that what we have already, go ahead and apply them
+                    if (peerBlocks.size() > 0) {
+						final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
+                    	final Block peerLatestBlock = peerBlocks.get(peerBlocks.size() - 1);
+						final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
+						if (ourLatestBlockData != null && peerLatestBlock != null && minLatestBlockTimestamp != null) {
+
+							// If our latest block is very old....
+							if (ourLatestBlockData.getTimestamp() < minLatestBlockTimestamp) {
+								// ... and we have received a block that is more recent than our latest block ...
+								if (peerLatestBlock.getBlockData().getTimestamp() > ourLatestBlockData.getTimestamp()) {
+									// ... then apply the blocks, as it takes us a step forward.
+									// This is particularly useful when starting up a node that was on a small fork when it was last shut down.
+									// In these cases, we now allow the node to sync forward, and get onto the main chain again.
+									// Without this, we would require that the node syncs ENTIRELY with this peer,
+									// and any problems downloading a block would cause all progress to be lost.
+									LOGGER.debug(String.format("Newly received blocks are %d ms newer than our latest block - so we will apply them", peerLatestBlock.getBlockData().getTimestamp() - ourLatestBlockData.getTimestamp()));
+									break;
+								}
+							}
+						}
+                    }
+					// Otherwise, give up and move on to the next peer, to avoid putting our chain into an outdated or incomplete state
+                    return SynchronizationResult.NO_REPLY;
+                }
+
+                numberSignaturesRequired = peerHeight - height - peerBlockSignatures.size();
+                LOGGER.trace(String.format("Received %s signature%s", peerBlockSignatures.size(), (peerBlockSignatures.size() != 1 ? "s" : "")));
+			}
+
+			if (peerBlockSignatures.isEmpty()) {
+				LOGGER.trace(String.format("No more signatures or blocks to request from peer %s", peer));
+				break;
+			}
+
+			// Catch a block with an invalid signature before orphaning, so that we retain our existing valid candidate
+			if (this.containsInvalidBlockSignature(peerBlockSignatures)) {
+				LOGGER.info(String.format("Peer %s sent invalid block signature: %.8s", peer, Base58.encode(latestPeerSignature)));
+				return SynchronizationResult.INVALID_DATA;
+			}
+
+			byte[] nextPeerSignature = peerBlockSignatures.get(0);
+			int nextHeight = height + 1;
+
+			LOGGER.trace(String.format("Fetching block %d, sig %.8s from %s", nextHeight, Base58.encode(nextPeerSignature), peer));
+			Block newBlock = this.fetchBlock(repository, peer, nextPeerSignature);
 
 			if (newBlock == null) {
 				LOGGER.info(String.format("Peer %s failed to respond with block for height %d, sig %.8s", peer,
-						ourHeight, Base58.encode(blockSignature)));
-				return SynchronizationResult.NO_REPLY;
+						nextHeight, Base58.encode(nextPeerSignature)));
+
+				if (retryCount >= maxRetries) {
+					// If we have already received newer blocks from this peer that what we have already, go ahead and apply them
+					if (peerBlocks.size() > 0) {
+						final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
+						final Block peerLatestBlock = peerBlocks.get(peerBlocks.size() - 1);
+						final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
+						if (ourLatestBlockData != null && peerLatestBlock != null && minLatestBlockTimestamp != null) {
+
+							// If our latest block is very old....
+							if (ourLatestBlockData.getTimestamp() < minLatestBlockTimestamp) {
+								// ... and we have received a block that is more recent than our latest block ...
+								if (peerLatestBlock.getBlockData().getTimestamp() > ourLatestBlockData.getTimestamp()) {
+									// ... then apply the blocks, as it takes us a step forward.
+									// This is particularly useful when starting up a node that was on a small fork when it was last shut down.
+									// In these cases, we now allow the node to sync forward, and get onto the main chain again.
+									// Without this, we would require that the node syncs ENTIRELY with this peer,
+									// and any problems downloading a block would cause all progress to be lost.
+									LOGGER.debug(String.format("Newly received blocks are %d ms newer than our latest block - so we will apply them", peerLatestBlock.getBlockData().getTimestamp() - ourLatestBlockData.getTimestamp()));
+									break;
+								}
+							}
+						}
+					}
+					// Otherwise, give up and move on to the next peer, to avoid putting our chain into an outdated or incomplete state
+					return SynchronizationResult.NO_REPLY;
+
+				} else {
+					// Re-fetch signatures, in case the peer is now on a different fork
+					peerBlockSignatures.clear();
+					numberSignaturesRequired = peerHeight - height;
+
+					// Retry until retryCount reaches maxRetries
+					retryCount++;
+					int triesRemaining = maxRetries - retryCount;
+					LOGGER.info(String.format("Re-issuing request to peer %s (%d attempt%s remaining)", peer, triesRemaining, (triesRemaining != 1 ? "s" : "")));
+					continue;
+				}
 			}
 
+			// Reset retryCount because the last request succeeded
+			retryCount = 0;
+
+			LOGGER.trace(String.format("Fetched block %d, sig %.8s from %s", nextHeight, Base58.encode(latestPeerSignature), peer));
+
 			if (!newBlock.isSignatureValid()) {
 				LOGGER.info(String.format("Peer %s sent block with invalid signature for height %d, sig %.8s", peer,
-						ourHeight, Base58.encode(blockSignature)));
+						nextHeight, Base58.encode(latestPeerSignature)));
 				return SynchronizationResult.INVALID_DATA;
 			}
 
@@ -395,12 +1027,19 @@ public class Synchronizer {
 				transaction.setInitialApprovalStatus();
 
 			peerBlocks.add(newBlock);
+
+			// Now that we've received this block, we can increase our height and move on to the next one
+			latestPeerSignature = nextPeerSignature;
+			peerBlockSignatures.remove(0);
+			++height;
 		}
 
 		// Unwind to common block (unless common block is our latest block)
-		LOGGER.debug(String.format("Orphaning blocks back to common block height %d, sig %.8s", commonBlockHeight, commonBlockSig58));
+		int ourHeight = ourInitialHeight;
+		LOGGER.debug(String.format("Orphaning blocks back to common block height %d, sig %.8s. Our height: %d", commonBlockHeight, commonBlockSig58, ourHeight));
+		int reorgSize = ourHeight - commonBlockHeight;
 
-		BlockData orphanBlockData = repository.getBlockRepository().fromHeight(ourHeight);
+		BlockData orphanBlockData = repository.getBlockRepository().fromHeight(ourInitialHeight);
 		while (ourHeight > commonBlockHeight) {
 			if (Controller.isStopping())
 				return SynchronizationResult.SHUTTING_DOWN;
@@ -422,13 +1061,23 @@ public class Synchronizer {
 		LOGGER.debug(String.format("Orphaned blocks back to height %d, sig %.8s - applying new blocks from peer %s", commonBlockHeight, commonBlockSig58, peer));
 
 		for (Block newBlock : peerBlocks) {
+			if (Controller.isStopping())
+				return SynchronizationResult.SHUTTING_DOWN;
+
+			newBlock.preProcess();
+
 			ValidationResult blockResult = newBlock.isValid();
 			if (blockResult != ValidationResult.OK) {
 				LOGGER.info(String.format("Peer %s sent invalid block for height %d, sig %.8s: %s", peer,
-						ourHeight, Base58.encode(newBlock.getSignature()), blockResult.name()));
+						newBlock.getBlockData().getHeight(), Base58.encode(newBlock.getSignature()), blockResult.name()));
+				this.addInvalidBlockSignature(newBlock.getSignature());
+				this.timeInvalidBlockLastReceived = NTP.getTime();
 				return SynchronizationResult.INVALID_DATA;
 			}
 
+			// Block is valid
+			this.timeValidBlockLastReceived = NTP.getTime();
+
 			// Save transactions attached to this block
 			for (Transaction transaction : newBlock.getTransactions()) {
 				TransactionData transactionData = transaction.getTransactionData();
@@ -444,6 +1093,7 @@ public class Synchronizer {
 			Controller.getInstance().onNewBlock(newBlock.getBlockData());
 		}
 
+		this.lastReorgSize = reorgSize;
 		return SynchronizationResult.OK;
 	}
 
@@ -469,7 +1119,8 @@ public class Synchronizer {
 
 			// Do we need more signatures?
 			if (peerBlockSignatures.isEmpty()) {
-				int numberRequested = maxBatchHeight - ourHeight;
+				int numberRequested = Math.min(maxBatchHeight - ourHeight, MAXIMUM_REQUEST_SIZE);
+
 				LOGGER.trace(String.format("Requesting %d signature%s after height %d, sig %.8s",
 						numberRequested, (numberRequested != 1 ? "s": ""), ourHeight, Base58.encode(latestPeerSignature)));
 
@@ -488,7 +1139,9 @@ public class Synchronizer {
 			peerBlockSignatures.remove(0);
 			++ourHeight;
 
+			LOGGER.trace(String.format("Fetching block %d, sig %.8s from %s", ourHeight, Base58.encode(latestPeerSignature), peer));
 			Block newBlock = this.fetchBlock(repository, peer, latestPeerSignature);
+			LOGGER.trace(String.format("Fetched block %d, sig %.8s from %s", ourHeight, Base58.encode(latestPeerSignature), peer));
 
 			if (newBlock == null) {
 				LOGGER.info(String.format("Peer %s failed to respond with block for height %d, sig %.8s", peer,
@@ -506,13 +1159,20 @@ public class Synchronizer {
 			for (Transaction transaction : newBlock.getTransactions())
 				transaction.setInitialApprovalStatus();
 
+			newBlock.preProcess();
+
 			ValidationResult blockResult = newBlock.isValid();
 			if (blockResult != ValidationResult.OK) {
 				LOGGER.info(String.format("Peer %s sent invalid block for height %d, sig %.8s: %s", peer,
 						ourHeight, Base58.encode(latestPeerSignature), blockResult.name()));
+				this.addInvalidBlockSignature(newBlock.getSignature());
+				this.timeInvalidBlockLastReceived = NTP.getTime();
 				return SynchronizationResult.INVALID_DATA;
 			}
 
+			// Block is valid
+			this.timeValidBlockLastReceived = NTP.getTime();
+
 			// Save transactions attached to this block
 			for (Transaction transaction : newBlock.getTransactions()) {
 				TransactionData transactionData = transaction.getTransactionData();
@@ -571,6 +1231,9 @@ public class Synchronizer {
 		final int firstBlockHeight = blockSummaries.get(0).getHeight();
 
 		for (int i = 0; i < blockSummaries.size(); ++i) {
+			if (Controller.isStopping())
+				return;
+
 			BlockSummaryData blockSummary = blockSummaries.get(i);
 
 			// Qortal: minter is always a reward-share, so find actual minter and get their effective minting level

src/main/java/org/qortal/controller/repository/AtStatesPruner.java

@@ -0,0 +1,109 @@
+package org.qortal.controller.repository;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.controller.Controller;
+import org.qortal.data.block.BlockData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.settings.Settings;
+import org.qortal.utils.NTP;
+
+public class AtStatesPruner implements Runnable {
+
+	private static final Logger LOGGER = LogManager.getLogger(AtStatesPruner.class);
+
+	@Override
+	public void run() {
+		Thread.currentThread().setName("AT States pruner");
+
+		boolean archiveMode = false;
+		if (!Settings.getInstance().isTopOnly()) {
+			// Top-only mode isn't enabled, but we might want to prune for the purposes of archiving
+			if (!Settings.getInstance().isArchiveEnabled()) {
+				// No pruning or archiving, so we must not prune anything
+				return;
+			}
+			else {
+				// We're allowed to prune blocks that have already been archived
+				archiveMode = true;
+			}
+		}
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			int pruneStartHeight = repository.getATRepository().getAtPruneHeight();
+
+			repository.discardChanges();
+			repository.getATRepository().rebuildLatestAtStates();
+
+			while (!Controller.isStopping()) {
+				repository.discardChanges();
+
+				Thread.sleep(Settings.getInstance().getAtStatesPruneInterval());
+
+				BlockData chainTip = Controller.getInstance().getChainTip();
+				if (chainTip == null || NTP.getTime() == null)
+					continue;
+
+				// Don't even attempt if we're mid-sync as our repository requests will be delayed for ages
+				if (Controller.getInstance().isSynchronizing())
+					continue;
+
+				// Prune AT states for all blocks up until our latest minus pruneBlockLimit
+				final int ourLatestHeight = chainTip.getHeight();
+				int upperPrunableHeight = ourLatestHeight - Settings.getInstance().getPruneBlockLimit();
+
+				// In archive mode we are only allowed to trim blocks that have already been archived
+				if (archiveMode) {
+					upperPrunableHeight = repository.getBlockArchiveRepository().getBlockArchiveHeight() - 1;
+
+					// TODO: validate that the actual archived data exists before pruning it?
+				}
+
+				int upperBatchHeight = pruneStartHeight + Settings.getInstance().getAtStatesPruneBatchSize();
+				int upperPruneHeight = Math.min(upperBatchHeight, upperPrunableHeight);
+
+				if (pruneStartHeight >= upperPruneHeight)
+					continue;
+
+				LOGGER.debug(String.format("Pruning AT states between blocks %d and %d...", pruneStartHeight, upperPruneHeight));
+
+				int numAtStatesPruned = repository.getATRepository().pruneAtStates(pruneStartHeight, upperPruneHeight);
+				repository.saveChanges();
+				int numAtStateDataRowsTrimmed = repository.getATRepository().trimAtStates(
+						pruneStartHeight, upperPruneHeight, Settings.getInstance().getAtStatesTrimLimit());
+				repository.saveChanges();
+
+				if (numAtStatesPruned > 0 || numAtStateDataRowsTrimmed > 0) {
+					final int finalPruneStartHeight = pruneStartHeight;
+					LOGGER.debug(() -> String.format("Pruned %d AT state%s between blocks %d and %d",
+							numAtStatesPruned, (numAtStatesPruned != 1 ? "s" : ""),
+							finalPruneStartHeight, upperPruneHeight));
+				} else {
+					// Can we move onto next batch?
+					if (upperPrunableHeight > upperBatchHeight) {
+						pruneStartHeight = upperBatchHeight;
+						repository.getATRepository().setAtPruneHeight(pruneStartHeight);
+						repository.getATRepository().rebuildLatestAtStates();
+						repository.saveChanges();
+
+						final int finalPruneStartHeight = pruneStartHeight;
+						LOGGER.debug(() -> String.format("Bumping AT state base prune height to %d", finalPruneStartHeight));
+					}
+					else {
+						// We've pruned up to the upper prunable height
+						// Back off for a while to save CPU for syncing
+						repository.discardChanges();
+						Thread.sleep(5*60*1000L);
+					}
+				}
+			}
+		} catch (DataException e) {
+			LOGGER.warn(String.format("Repository issue trying to prune AT states: %s", e.getMessage()));
+		} catch (InterruptedException e) {
+			// Time to exit
+		}
+	}
+
+}

src/main/java/org/qortal/controller/repository/AtStatesTrimmer.java

@@ -1,7 +1,8 @@
-package org.qortal.controller;
+package org.qortal.controller.repository;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.qortal.controller.Controller;
 import org.qortal.data.block.BlockData;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
@@ -20,8 +21,8 @@ public class AtStatesTrimmer implements Runnable {
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			int trimStartHeight = repository.getATRepository().getAtTrimHeight();
 
-			repository.getATRepository().prepareForAtStateTrimming();
-			repository.saveChanges();
+			repository.discardChanges();
+			repository.getATRepository().rebuildLatestAtStates();
 
 			while (!Controller.isStopping()) {
 				repository.discardChanges();
@@ -62,7 +63,7 @@ public class AtStatesTrimmer implements Runnable {
 					if (upperTrimmableHeight > upperBatchHeight) {
 						trimStartHeight = upperBatchHeight;
 						repository.getATRepository().setAtTrimHeight(trimStartHeight);
-						repository.getATRepository().prepareForAtStateTrimming();
+						repository.getATRepository().rebuildLatestAtStates();
 						repository.saveChanges();
 
 						final int finalTrimStartHeight = trimStartHeight;

src/main/java/org/qortal/controller/repository/BlockArchiver.java

@@ -0,0 +1,113 @@
+package org.qortal.controller.repository;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.controller.Controller;
+import org.qortal.data.block.BlockData;
+import org.qortal.repository.*;
+import org.qortal.settings.Settings;
+import org.qortal.transform.TransformationException;
+import org.qortal.utils.NTP;
+
+import java.io.IOException;
+
+public class BlockArchiver implements Runnable {
+
+	private static final Logger LOGGER = LogManager.getLogger(BlockArchiver.class);
+
+	private static final long INITIAL_SLEEP_PERIOD = 0L; // TODO: 5 * 60 * 1000L + 1234L; // ms
+
+	public void run() {
+		Thread.currentThread().setName("Block archiver");
+
+		if (!Settings.getInstance().isArchiveEnabled()) {
+			return;
+		}
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			// Don't even start building until initial rush has ended
+			Thread.sleep(INITIAL_SLEEP_PERIOD);
+
+			int startHeight = repository.getBlockArchiveRepository().getBlockArchiveHeight();
+
+			// Don't attempt to archive if we have no ATStatesHeightIndex, as it will be too slow
+			boolean hasAtStatesHeightIndex = repository.getATRepository().hasAtStatesHeightIndex();
+			if (!hasAtStatesHeightIndex) {
+				LOGGER.info("Unable to start block archiver due to missing ATStatesHeightIndex. Bootstrapping is recommended.");
+				repository.discardChanges();
+				return;
+			}
+
+			LOGGER.info("Starting block archiver from height {}...", startHeight);
+
+			while (!Controller.isStopping()) {
+				repository.discardChanges();
+
+				Thread.sleep(Settings.getInstance().getArchiveInterval());
+
+				BlockData chainTip = Controller.getInstance().getChainTip();
+				if (chainTip == null || NTP.getTime() == null) {
+					continue;
+				}
+
+				// Don't even attempt if we're mid-sync as our repository requests will be delayed for ages
+				if (Controller.getInstance().isSynchronizing()) {
+					continue;
+				}
+
+				// Don't attempt to archive if we're not synced yet
+				final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
+				if (minLatestBlockTimestamp == null || chainTip.getTimestamp() < minLatestBlockTimestamp) {
+					continue;
+				}
+
+
+				// Build cache of blocks
+				try {
+					final int maximumArchiveHeight = BlockArchiveWriter.getMaxArchiveHeight(repository);
+					BlockArchiveWriter writer = new BlockArchiveWriter(startHeight, maximumArchiveHeight, repository);
+					BlockArchiveWriter.BlockArchiveWriteResult result = writer.write();
+					switch (result) {
+						case OK:
+							// Increment block archive height
+							startHeight += writer.getWrittenCount();
+							repository.getBlockArchiveRepository().setBlockArchiveHeight(startHeight);
+							repository.saveChanges();
+							break;
+
+						case STOPPING:
+							return;
+
+							// We've reached the limit of the blocks we can archive
+							// Sleep for a while to allow more to become available
+						case NOT_ENOUGH_BLOCKS:
+							// We didn't reach our file size target, so that must mean that we don't have enough blocks
+							// yet or something went wrong. Sleep for a while and then try again.
+							repository.discardChanges();
+							Thread.sleep(60 * 60 * 1000L); // 1 hour
+							break;
+
+						case BLOCK_NOT_FOUND:
+							// We tried to archive a block that didn't exist. This is a major failure and likely means
+							// that a bootstrap or re-sync is needed. Try again every minute until then.
+							LOGGER.info("Error: block not found when building archive. If this error persists, " +
+									"a bootstrap or re-sync may be needed.");
+							repository.discardChanges();
+							Thread.sleep( 60 * 1000L); // 1 minute
+							break;
+					}
+
+				} catch (IOException | TransformationException e) {
+					LOGGER.info("Caught exception when creating block cache", e);
+				}
+
+			}
+		} catch (DataException e) {
+			LOGGER.info("Caught exception when creating block cache", e);
+		} catch (InterruptedException e) {
+			// Do nothing
+		}
+
+	}
+
+}

src/main/java/org/qortal/controller/repository/BlockPruner.java

@@ -0,0 +1,114 @@
+package org.qortal.controller.repository;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.controller.Controller;
+import org.qortal.data.block.BlockData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.settings.Settings;
+import org.qortal.utils.NTP;
+
+public class BlockPruner implements Runnable {
+
+	private static final Logger LOGGER = LogManager.getLogger(BlockPruner.class);
+
+	@Override
+	public void run() {
+		Thread.currentThread().setName("Block pruner");
+
+		boolean archiveMode = false;
+		if (!Settings.getInstance().isTopOnly()) {
+			// Top-only mode isn't enabled, but we might want to prune for the purposes of archiving
+			if (!Settings.getInstance().isArchiveEnabled()) {
+				// No pruning or archiving, so we must not prune anything
+				return;
+			}
+			else {
+				// We're allowed to prune blocks that have already been archived
+				archiveMode = true;
+			}
+		}
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			int pruneStartHeight = repository.getBlockRepository().getBlockPruneHeight();
+
+			// Don't attempt to prune if we have no ATStatesHeightIndex, as it will be too slow
+			boolean hasAtStatesHeightIndex = repository.getATRepository().hasAtStatesHeightIndex();
+			if (!hasAtStatesHeightIndex) {
+				LOGGER.info("Unable to start block pruner due to missing ATStatesHeightIndex. Bootstrapping is recommended.");
+				return;
+			}
+
+			while (!Controller.isStopping()) {
+				repository.discardChanges();
+
+				Thread.sleep(Settings.getInstance().getBlockPruneInterval());
+
+				BlockData chainTip = Controller.getInstance().getChainTip();
+				if (chainTip == null || NTP.getTime() == null)
+					continue;
+
+				// Don't even attempt if we're mid-sync as our repository requests will be delayed for ages
+				if (Controller.getInstance().isSynchronizing()) {
+					continue;
+				}
+
+				// Don't attempt to prune if we're not synced yet
+				final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
+				if (minLatestBlockTimestamp == null || chainTip.getTimestamp() < minLatestBlockTimestamp) {
+					continue;
+				}
+
+				// Prune all blocks up until our latest minus pruneBlockLimit
+				final int ourLatestHeight = chainTip.getHeight();
+				int upperPrunableHeight = ourLatestHeight - Settings.getInstance().getPruneBlockLimit();
+
+				// In archive mode we are only allowed to trim blocks that have already been archived
+				if (archiveMode) {
+					upperPrunableHeight = repository.getBlockArchiveRepository().getBlockArchiveHeight() - 1;
+				}
+
+				int upperBatchHeight = pruneStartHeight + Settings.getInstance().getBlockPruneBatchSize();
+				int upperPruneHeight = Math.min(upperBatchHeight, upperPrunableHeight);
+
+				if (pruneStartHeight >= upperPruneHeight) {
+					continue;
+				}
+
+				LOGGER.debug(String.format("Pruning blocks between %d and %d...", pruneStartHeight, upperPruneHeight));
+
+				int numBlocksPruned = repository.getBlockRepository().pruneBlocks(pruneStartHeight, upperPruneHeight);
+				repository.saveChanges();
+
+				if (numBlocksPruned > 0) {
+					LOGGER.debug(String.format("Pruned %d block%s between %d and %d",
+							numBlocksPruned, (numBlocksPruned != 1 ? "s" : ""),
+							pruneStartHeight, upperPruneHeight));
+				} else {
+					final int nextPruneHeight = upperPruneHeight + 1;
+					repository.getBlockRepository().setBlockPruneHeight(nextPruneHeight);
+					repository.saveChanges();
+					LOGGER.debug(String.format("Bumping block base prune height to %d", pruneStartHeight));
+
+					// Can we move onto next batch?
+					if (upperPrunableHeight > nextPruneHeight) {
+						pruneStartHeight = nextPruneHeight;
+					}
+					else {
+						// We've pruned up to the upper prunable height
+						// Back off for a while to save CPU for syncing
+						repository.discardChanges();
+						Thread.sleep(10*60*1000L);
+					}
+				}
+			}
+		} catch (DataException e) {
+			LOGGER.warn(String.format("Repository issue trying to prune blocks: %s", e.getMessage()));
+		} catch (InterruptedException e) {
+			// Time to exit
+		}
+	}
+
+}

src/main/java/org/qortal/controller/repository/NamesDatabaseIntegrityCheck.java

@@ -0,0 +1,415 @@
+package org.qortal.controller.repository;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.account.PublicKeyAccount;
+import org.qortal.api.resource.TransactionsResource.ConfirmationStatus;
+import org.qortal.data.naming.NameData;
+import org.qortal.data.transaction.*;
+import org.qortal.naming.Name;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.transaction.Transaction.TransactionType;
+import org.qortal.utils.Unicode;
+
+import java.util.*;
+
+public class NamesDatabaseIntegrityCheck {
+
+    private static final Logger LOGGER = LogManager.getLogger(NamesDatabaseIntegrityCheck.class);
+
+    private static final List<TransactionType> ALL_NAME_TX_TYPE = Arrays.asList(
+            TransactionType.REGISTER_NAME,
+            TransactionType.UPDATE_NAME,
+            TransactionType.BUY_NAME,
+            TransactionType.SELL_NAME
+    );
+
+    private List<TransactionData> nameTransactions = new ArrayList<>();
+
+    public int rebuildName(String name, Repository repository) {
+        int modificationCount = 0;
+        try {
+            List<TransactionData> transactions = this.fetchAllTransactionsInvolvingName(name, repository);
+            if (transactions.isEmpty()) {
+                // This name was never registered, so there's nothing to do
+                return modificationCount;
+            }
+
+            // Loop through each past transaction and re-apply it to the Names table
+            for (TransactionData currentTransaction : transactions) {
+
+                // Process REGISTER_NAME transactions
+                if (currentTransaction.getType() == TransactionType.REGISTER_NAME) {
+                    RegisterNameTransactionData registerNameTransactionData = (RegisterNameTransactionData) currentTransaction;
+                    Name nameObj = new Name(repository, registerNameTransactionData);
+                    nameObj.register();
+                    modificationCount++;
+                    LOGGER.trace("Processed REGISTER_NAME transaction for name {}", name);
+                }
+
+                // Process UPDATE_NAME transactions
+                if (currentTransaction.getType() == TransactionType.UPDATE_NAME) {
+                    UpdateNameTransactionData updateNameTransactionData = (UpdateNameTransactionData) currentTransaction;
+
+                    if (Objects.equals(updateNameTransactionData.getNewName(), name) &&
+                            !Objects.equals(updateNameTransactionData.getName(), updateNameTransactionData.getNewName())) {
+                        // This renames an existing name, so we need to process that instead
+                        this.rebuildName(updateNameTransactionData.getName(), repository);
+                    }
+                    else {
+                        Name nameObj = new Name(repository, name);
+                        if (nameObj != null && nameObj.getNameData() != null) {
+                            nameObj.update(updateNameTransactionData);
+                            modificationCount++;
+                            LOGGER.trace("Processed UPDATE_NAME transaction for name {}", name);
+                        } else {
+                            // Something went wrong
+                            throw new DataException(String.format("Name data not found for name %s", updateNameTransactionData.getName()));
+                        }
+                    }
+                }
+
+                // Process SELL_NAME transactions
+                if (currentTransaction.getType() == TransactionType.SELL_NAME) {
+                    SellNameTransactionData sellNameTransactionData = (SellNameTransactionData) currentTransaction;
+                    Name nameObj = new Name(repository, sellNameTransactionData.getName());
+                    if (nameObj != null && nameObj.getNameData() != null) {
+                        nameObj.sell(sellNameTransactionData);
+                        modificationCount++;
+                        LOGGER.trace("Processed SELL_NAME transaction for name {}", name);
+                    }
+                    else {
+                        // Something went wrong
+                        throw new DataException(String.format("Name data not found for name %s", sellNameTransactionData.getName()));
+                    }
+                }
+
+                // Process BUY_NAME transactions
+                if (currentTransaction.getType() == TransactionType.BUY_NAME) {
+                    BuyNameTransactionData buyNameTransactionData = (BuyNameTransactionData) currentTransaction;
+                    Name nameObj = new Name(repository, buyNameTransactionData.getName());
+                    if (nameObj != null && nameObj.getNameData() != null) {
+                        nameObj.buy(buyNameTransactionData);
+                        modificationCount++;
+                        LOGGER.trace("Processed BUY_NAME transaction for name {}", name);
+                    }
+                    else {
+                        // Something went wrong
+                        throw new DataException(String.format("Name data not found for name %s", buyNameTransactionData.getName()));
+                    }
+                }
+            }
+
+        } catch (DataException e) {
+            LOGGER.info("Unable to run integrity check for name {}: {}", name, e.getMessage());
+        }
+
+        return modificationCount;
+    }
+
+    public int rebuildAllNames() {
+        int modificationCount = 0;
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            List<String> names = this.fetchAllNames(repository);
+            for (String name : names) {
+                modificationCount += this.rebuildName(name, repository);
+            }
+            repository.saveChanges();
+        }
+        catch (DataException e) {
+            LOGGER.info("Error when running integrity check for all names: {}", e.getMessage());
+        }
+
+        //LOGGER.info("modificationCount: {}", modificationCount);
+        return modificationCount;
+    }
+
+    public void runIntegrityCheck() {
+        boolean integrityCheckFailed = false;
+        try (final Repository repository = RepositoryManager.getRepository()) {
+
+            // Fetch all the (confirmed) REGISTER_NAME transactions
+            List<RegisterNameTransactionData> registerNameTransactions = this.fetchRegisterNameTransactions();
+
+            // Loop through each REGISTER_NAME txn signature and request the full transaction data
+            for (RegisterNameTransactionData registerNameTransactionData : registerNameTransactions) {
+                String registeredName = registerNameTransactionData.getName();
+                NameData nameData = repository.getNameRepository().fromName(registeredName);
+
+                // Check to see if this name has been updated or bought at any point
+                TransactionData latestUpdate = this.fetchLatestModificationTransactionInvolvingName(registeredName, repository);
+                if (latestUpdate == null) {
+                    // Name was never updated once registered
+                    // We expect this name to still be registered to this transaction's creator
+
+                    if (nameData == null) {
+                        LOGGER.info("Error: registered name {} doesn't exist in Names table. Adding...", registeredName);
+                        integrityCheckFailed = true;
+                    }
+                    else {
+                        LOGGER.trace("Registered name {} is correctly registered", registeredName);
+                    }
+
+                    // Check the owner is correct
+                    PublicKeyAccount creator = new PublicKeyAccount(repository, registerNameTransactionData.getCreatorPublicKey());
+                    if (!Objects.equals(creator.getAddress(), nameData.getOwner())) {
+                        LOGGER.info("Error: registered name {} is owned by {}, but it should be {}",
+                                registeredName, nameData.getOwner(), creator.getAddress());
+                        integrityCheckFailed = true;
+                    }
+                    else {
+                        LOGGER.trace("Registered name {} has the correct owner", registeredName);
+                    }
+                }
+                else {
+                    // Check if owner is correct after update
+
+                    // Check for name updates
+                    if (latestUpdate.getType() == TransactionType.UPDATE_NAME) {
+                        UpdateNameTransactionData updateNameTransactionData = (UpdateNameTransactionData) latestUpdate;
+                        PublicKeyAccount creator = new PublicKeyAccount(repository, updateNameTransactionData.getCreatorPublicKey());
+
+                        // When this name is the "new name", we expect the current owner to match the txn creator
+                        if (Objects.equals(updateNameTransactionData.getNewName(), registeredName)) {
+                            if (!Objects.equals(creator.getAddress(), nameData.getOwner())) {
+                                LOGGER.info("Error: registered name {} is owned by {}, but it should be {}",
+                                        registeredName, nameData.getOwner(), creator.getAddress());
+                                integrityCheckFailed = true;
+                            }
+                            else {
+                                LOGGER.trace("Registered name {} has the correct owner after being updated", registeredName);
+                            }
+                        }
+
+                        // When this name is the old name, we expect the "new name"'s owner to match the txn creator
+                        // The old name will then be unregistered, or re-registered.
+                        // FUTURE: check database integrity for names that have been updated and then the original name re-registered
+                        else if (Objects.equals(updateNameTransactionData.getName(), registeredName)) {
+                            String newName = updateNameTransactionData.getNewName();
+                            if (newName == null || newName.length() == 0) {
+                                // If new name is blank (or maybe null, just to be safe), it means that it stayed the same
+                                newName = registeredName;
+                            }
+                            NameData newNameData = repository.getNameRepository().fromName(newName);
+                            if (!Objects.equals(creator.getAddress(), newNameData.getOwner())) {
+                                LOGGER.info("Error: registered name {} is owned by {}, but it should be {}",
+                                        updateNameTransactionData.getNewName(), newNameData.getOwner(), creator.getAddress());
+                                integrityCheckFailed = true;
+                            }
+                            else {
+                                LOGGER.trace("Registered name {} has the correct owner after being updated", updateNameTransactionData.getNewName());
+                            }
+                        }
+
+                        else {
+                            LOGGER.info("Unhandled update case for name {}", registeredName);
+                        }
+                    }
+
+                    // Check for name buys
+                    else if (latestUpdate.getType() == TransactionType.BUY_NAME) {
+                        BuyNameTransactionData buyNameTransactionData = (BuyNameTransactionData) latestUpdate;
+                        PublicKeyAccount creator = new PublicKeyAccount(repository, buyNameTransactionData.getCreatorPublicKey());
+                        if (!Objects.equals(creator.getAddress(), nameData.getOwner())) {
+                            LOGGER.info("Error: registered name {} is owned by {}, but it should be {}",
+                                    registeredName, nameData.getOwner(), creator.getAddress());
+                            integrityCheckFailed = true;
+                        }
+                        else {
+                            LOGGER.trace("Registered name {} has the correct owner after being bought", registeredName);
+                        }
+                    }
+
+                    // Check for name sells
+                    else if (latestUpdate.getType() == TransactionType.SELL_NAME) {
+                        SellNameTransactionData sellNameTransactionData = (SellNameTransactionData) latestUpdate;
+                        PublicKeyAccount creator = new PublicKeyAccount(repository, sellNameTransactionData.getCreatorPublicKey());
+                        if (!Objects.equals(creator.getAddress(), nameData.getOwner())) {
+                            LOGGER.info("Error: registered name {} is owned by {}, but it should be {}",
+                                    registeredName, nameData.getOwner(), creator.getAddress());
+                            integrityCheckFailed = true;
+                        }
+                        else {
+                            LOGGER.trace("Registered name {} has the correct owner after being listed for sale", registeredName);
+                        }
+                    }
+
+                    else {
+                        LOGGER.info("Unhandled case for name {}", registeredName);
+                    }
+
+                }
+
+            }
+
+        } catch (DataException e) {
+            LOGGER.warn(String.format("Repository issue trying to trim online accounts signatures: %s", e.getMessage()));
+            integrityCheckFailed = true;
+        }
+
+        if (integrityCheckFailed) {
+            LOGGER.info("Registered names database integrity check failed. Bootstrapping is recommended.");
+        } else {
+            LOGGER.info("Registered names database integrity check passed.");
+        }
+    }
+
+    private List<RegisterNameTransactionData> fetchRegisterNameTransactions() {
+        List<RegisterNameTransactionData> registerNameTransactions = new ArrayList<>();
+
+        for (TransactionData transactionData : this.nameTransactions) {
+            if (transactionData.getType() == TransactionType.REGISTER_NAME) {
+                RegisterNameTransactionData registerNameTransactionData = (RegisterNameTransactionData) transactionData;
+                registerNameTransactions.add(registerNameTransactionData);
+            }
+        }
+        return registerNameTransactions;
+    }
+
+    private List<UpdateNameTransactionData> fetchUpdateNameTransactions() {
+        List<UpdateNameTransactionData> updateNameTransactions = new ArrayList<>();
+
+        for (TransactionData transactionData : this.nameTransactions) {
+            if (transactionData.getType() == TransactionType.UPDATE_NAME) {
+                UpdateNameTransactionData updateNameTransactionData = (UpdateNameTransactionData) transactionData;
+                updateNameTransactions.add(updateNameTransactionData);
+            }
+        }
+        return updateNameTransactions;
+    }
+
+    private List<SellNameTransactionData> fetchSellNameTransactions() {
+        List<SellNameTransactionData> sellNameTransactions = new ArrayList<>();
+
+        for (TransactionData transactionData : this.nameTransactions) {
+            if (transactionData.getType() == TransactionType.SELL_NAME) {
+                SellNameTransactionData sellNameTransactionData = (SellNameTransactionData) transactionData;
+                sellNameTransactions.add(sellNameTransactionData);
+            }
+        }
+        return sellNameTransactions;
+    }
+
+    private List<BuyNameTransactionData> fetchBuyNameTransactions() {
+        List<BuyNameTransactionData> buyNameTransactions = new ArrayList<>();
+
+        for (TransactionData transactionData : this.nameTransactions) {
+            if (transactionData.getType() == TransactionType.BUY_NAME) {
+                BuyNameTransactionData buyNameTransactionData = (BuyNameTransactionData) transactionData;
+                buyNameTransactions.add(buyNameTransactionData);
+            }
+        }
+        return buyNameTransactions;
+    }
+
+    private void fetchAllNameTransactions(Repository repository) throws DataException {
+        List<TransactionData> nameTransactions = new ArrayList<>();
+
+        // Fetch all the confirmed REGISTER_NAME transaction signatures
+        List<byte[]> signatures = repository.getTransactionRepository().getSignaturesMatchingCriteria(
+                null, null, null, ALL_NAME_TX_TYPE, null, null,
+                ConfirmationStatus.CONFIRMED, null, null, false);
+
+        for (byte[] signature : signatures) {
+            TransactionData transactionData = repository.getTransactionRepository().fromSignature(signature);
+            nameTransactions.add(transactionData);
+        }
+        this.nameTransactions = nameTransactions;
+    }
+
+    private List<TransactionData> fetchAllTransactionsInvolvingName(String name, Repository repository) throws DataException {
+        List<TransactionData> transactions = new ArrayList<>();
+        String reducedName = Unicode.sanitize(name);
+
+        // Fetch all the confirmed name-modification transactions
+        if (this.nameTransactions.isEmpty()) {
+            this.fetchAllNameTransactions(repository);
+        }
+
+        for (TransactionData transactionData : this.nameTransactions) {
+
+            if ((transactionData instanceof RegisterNameTransactionData)) {
+                RegisterNameTransactionData registerNameTransactionData = (RegisterNameTransactionData) transactionData;
+                if (Objects.equals(registerNameTransactionData.getReducedName(), reducedName)) {
+                    transactions.add(transactionData);
+                }
+            }
+            if ((transactionData instanceof UpdateNameTransactionData)) {
+                UpdateNameTransactionData updateNameTransactionData = (UpdateNameTransactionData) transactionData;
+                if (Objects.equals(updateNameTransactionData.getName(), name) ||
+                        Objects.equals(updateNameTransactionData.getReducedNewName(), reducedName)) {
+                    transactions.add(transactionData);
+                }
+            }
+            if ((transactionData instanceof BuyNameTransactionData)) {
+                BuyNameTransactionData buyNameTransactionData = (BuyNameTransactionData) transactionData;
+                if (Objects.equals(buyNameTransactionData.getName(), name)) {
+                    transactions.add(transactionData);
+                }
+            }
+            if ((transactionData instanceof SellNameTransactionData)) {
+                SellNameTransactionData sellNameTransactionData = (SellNameTransactionData) transactionData;
+                if (Objects.equals(sellNameTransactionData.getName(), name)) {
+                    transactions.add(transactionData);
+                }
+            }
+        }
+        return transactions;
+    }
+
+    private TransactionData fetchLatestModificationTransactionInvolvingName(String registeredName, Repository repository) throws DataException {
+        List<TransactionData> transactionsInvolvingName = this.fetchAllTransactionsInvolvingName(registeredName, repository);
+
+        // Get the latest update for this name (excluding REGISTER_NAME transactions)
+        TransactionData latestUpdateToName = transactionsInvolvingName.stream()
+                .filter(txn -> txn.getType() != TransactionType.REGISTER_NAME)
+                .max(Comparator.comparing(TransactionData::getTimestamp))
+                .orElse(null);
+
+        return latestUpdateToName;
+    }
+
+    private List<String> fetchAllNames(Repository repository) throws DataException {
+        List<String> names = new ArrayList<>();
+
+        // Fetch all the confirmed name transactions
+        if (this.nameTransactions.isEmpty()) {
+            this.fetchAllNameTransactions(repository);
+        }
+
+        for (TransactionData transactionData : this.nameTransactions) {
+
+            if ((transactionData instanceof RegisterNameTransactionData)) {
+                RegisterNameTransactionData registerNameTransactionData = (RegisterNameTransactionData) transactionData;
+                if (!names.contains(registerNameTransactionData.getName())) {
+                    names.add(registerNameTransactionData.getName());
+                }
+            }
+            if ((transactionData instanceof UpdateNameTransactionData)) {
+                UpdateNameTransactionData updateNameTransactionData = (UpdateNameTransactionData) transactionData;
+                if (!names.contains(updateNameTransactionData.getName())) {
+                    names.add(updateNameTransactionData.getName());
+                }
+                if (!names.contains(updateNameTransactionData.getNewName())) {
+                    names.add(updateNameTransactionData.getNewName());
+                }
+            }
+            if ((transactionData instanceof BuyNameTransactionData)) {
+                BuyNameTransactionData buyNameTransactionData = (BuyNameTransactionData) transactionData;
+                if (!names.contains(buyNameTransactionData.getName())) {
+                    names.add(buyNameTransactionData.getName());
+                }
+            }
+            if ((transactionData instanceof SellNameTransactionData)) {
+                SellNameTransactionData sellNameTransactionData = (SellNameTransactionData) transactionData;
+                if (!names.contains(sellNameTransactionData.getName())) {
+                    names.add(sellNameTransactionData.getName());
+                }
+            }
+        }
+        return names;
+    }
+
+}

src/main/java/org/qortal/controller/repository/OnlineAccountsSignaturesTrimmer.java

@@ -1,8 +1,9 @@
-package org.qortal.controller;
+package org.qortal.controller.repository;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.block.BlockChain;
+import org.qortal.controller.Controller;
 import org.qortal.data.block.BlockData;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;

src/main/java/org/qortal/controller/repository/PruneManager.java

@@ -0,0 +1,160 @@
+package org.qortal.controller.repository;
+
+import org.apache.commons.io.FileUtils;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.controller.Controller;
+
+import org.qortal.data.block.BlockData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.settings.Settings;
+import org.qortal.utils.DaemonThreadFactory;
+
+import java.io.IOException;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
+public class PruneManager {
+
+    private static final Logger LOGGER = LogManager.getLogger(PruneManager.class);
+
+    private static PruneManager instance;
+
+    private boolean isTopOnly = Settings.getInstance().isTopOnly();
+    private int pruneBlockLimit = Settings.getInstance().getPruneBlockLimit();
+
+    private ExecutorService executorService;
+
+    private PruneManager() {
+
+    }
+
+    public static synchronized PruneManager getInstance() {
+        if (instance == null)
+            instance = new PruneManager();
+
+        return instance;
+    }
+
+    public void start() {
+        this.executorService = Executors.newCachedThreadPool(new DaemonThreadFactory());
+
+        if (Settings.getInstance().isTopOnly()) {
+            // Top-only-sync
+            this.startTopOnlySyncMode();
+        }
+        else if (Settings.getInstance().isArchiveEnabled()) {
+            // Full node with block archive
+            this.startFullNodeWithBlockArchive();
+        }
+        else {
+            // Full node with full SQL support
+            this.startFullSQLNode();
+        }
+    }
+
+    /**
+     * Top-only-sync
+     * In this mode, we delete (prune) all blocks except
+     * a small number of recent ones. There is no need for
+     * trimming or archiving, because all relevant blocks
+     * are deleted.
+     */
+    private void startTopOnlySyncMode() {
+        this.startPruning();
+
+        // We don't need the block archive in top-only mode
+        this.deleteArchive();
+    }
+
+    /**
+     * Full node with block archive
+     * In this mode we archive trimmed blocks, and then
+     * prune archived blocks to keep the database small
+     */
+    private void startFullNodeWithBlockArchive() {
+        this.startTrimming();
+        this.startArchiving();
+        this.startPruning();
+    }
+
+    /**
+     * Full node with full SQL support
+     * In this mode we trim the database but don't prune
+     * or archive any data, because we want to maintain
+     * full SQL support of old blocks. This mode will not
+     * be actively maintained but can be used by those who
+     * need to perform SQL analysis on older blocks.
+     */
+    private void startFullSQLNode() {
+        this.startTrimming();
+    }
+
+
+    private void startPruning() {
+        this.executorService.execute(new AtStatesPruner());
+        this.executorService.execute(new BlockPruner());
+    }
+
+    private void startTrimming() {
+        this.executorService.execute(new AtStatesTrimmer());
+        this.executorService.execute(new OnlineAccountsSignaturesTrimmer());
+    }
+
+    private void startArchiving() {
+        this.executorService.execute(new BlockArchiver());
+    }
+
+    private void deleteArchive() {
+        if (!Settings.getInstance().isTopOnly()) {
+            LOGGER.error("Refusing to delete archive when not in top-only mode");
+        }
+
+        try {
+            Path archivePath = Paths.get(Settings.getInstance().getRepositoryPath(), "archive");
+            if (archivePath.toFile().exists()) {
+                LOGGER.info("Deleting block archive because we are in top-only mode...");
+                FileUtils.deleteDirectory(archivePath.toFile());
+            }
+
+        } catch (IOException e) {
+            LOGGER.info("Couldn't delete archive: {}", e.getMessage());
+        }
+    }
+
+    public void stop() {
+        this.executorService.shutdownNow();
+
+        try {
+            this.executorService.awaitTermination(2L, TimeUnit.SECONDS);
+        } catch (InterruptedException e) {
+            // We tried...
+        }
+    }
+
+    public boolean isBlockPruned(int height) throws DataException {
+        if (!this.isTopOnly) {
+            return false;
+        }
+
+        BlockData chainTip = Controller.getInstance().getChainTip();
+        if (chainTip == null) {
+            throw new DataException("Unable to determine chain tip when checking if a block is pruned");
+        }
+
+        if (height == 1) {
+            // We don't prune the genesis block
+            return false;
+        }
+
+        final int ourLatestHeight = chainTip.getHeight();
+        final int latestUnprunedHeight = ourLatestHeight - this.pruneBlockLimit;
+
+        return (height < latestUnprunedHeight);
+    }
+
+}

src/main/java/org/qortal/controller/tradebot/AcctTradeBot.java

@@ -0,0 +1,30 @@
+package org.qortal.controller.tradebot;
+
+import java.util.List;
+
+import org.qortal.api.model.crosschain.TradeBotCreateRequest;
+import org.qortal.crosschain.ACCT;
+import org.qortal.crosschain.ForeignBlockchainException;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+
+public interface AcctTradeBot {
+
+	public enum ResponseResult { OK, BALANCE_ISSUE, NETWORK_ISSUE, TRADE_ALREADY_EXISTS }
+
+	/** Returns list of state names for trade-bot entries that have ended, e.g. redeemed, refunded or cancelled. */
+	public List<String> getEndStates();
+
+	public byte[] createTrade(Repository repository, TradeBotCreateRequest tradeBotCreateRequest) throws DataException;
+
+	public ResponseResult startResponse(Repository repository, ATData atData, ACCT acct,
+			CrossChainTradeData crossChainTradeData, String foreignKey, String receivingAddress) throws DataException;
+
+	public boolean canDelete(Repository repository, TradeBotData tradeBotData) throws DataException;
+
+	public void progress(Repository repository, TradeBotData tradeBotData) throws DataException, ForeignBlockchainException;
+
+}

src/main/java/org/qortal/controller/tradebot/DogecoinACCTv1TradeBot.java

@@ -0,0 +1,885 @@
+package org.qortal.controller.tradebot;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.bitcoinj.core.*;
+import org.bitcoinj.script.Script.ScriptType;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.account.PublicKeyAccount;
+import org.qortal.api.model.crosschain.TradeBotCreateRequest;
+import org.qortal.asset.Asset;
+import org.qortal.crosschain.*;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.data.transaction.BaseTransactionData;
+import org.qortal.data.transaction.DeployAtTransactionData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.transaction.DeployAtTransaction;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.transaction.DeployAtTransactionTransformer;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import static java.util.Arrays.stream;
+import static java.util.stream.Collectors.toMap;
+
+/**
+ * Performing cross-chain trading steps on behalf of user.
+ * <p>
+ * We deal with three different independent state-spaces here:
+ * <ul>
+ * 	<li>Qortal blockchain</li>
+ * 	<li>Foreign blockchain</li>
+ * 	<li>Trade-bot entries</li>
+ * </ul>
+ */
+public class DogecoinACCTv1TradeBot implements AcctTradeBot {
+
+	private static final Logger LOGGER = LogManager.getLogger(DogecoinACCTv1TradeBot.class);
+
+	public enum State implements TradeBot.StateNameAndValueSupplier {
+		BOB_WAITING_FOR_AT_CONFIRM(10, false, false),
+		BOB_WAITING_FOR_MESSAGE(15, true, true),
+		BOB_WAITING_FOR_AT_REDEEM(25, true, true),
+		BOB_DONE(30, false, false),
+		BOB_REFUNDED(35, false, false),
+
+		ALICE_WAITING_FOR_AT_LOCK(85, true, true),
+		ALICE_DONE(95, false, false),
+		ALICE_REFUNDING_A(105, true, true),
+		ALICE_REFUNDED(110, false, false);
+
+		private static final Map<Integer, State> map = stream(State.values()).collect(toMap(state -> state.value, state -> state));
+
+		public final int value;
+		public final boolean requiresAtData;
+		public final boolean requiresTradeData;
+
+		State(int value, boolean requiresAtData, boolean requiresTradeData) {
+			this.value = value;
+			this.requiresAtData = requiresAtData;
+			this.requiresTradeData = requiresTradeData;
+		}
+
+		public static State valueOf(int value) {
+			return map.get(value);
+		}
+
+		@Override
+		public String getState() {
+			return this.name();
+		}
+
+		@Override
+		public int getStateValue() {
+			return this.value;
+		}
+	}
+
+	/** Maximum time Bob waits for his AT creation transaction to be confirmed into a block. (milliseconds) */
+	private static final long MAX_AT_CONFIRMATION_PERIOD = 24 * 60 * 60 * 1000L; // ms
+
+	private static DogecoinACCTv1TradeBot instance;
+
+	private final List<String> endStates = Arrays.asList(State.BOB_DONE, State.BOB_REFUNDED, State.ALICE_DONE, State.ALICE_REFUNDING_A, State.ALICE_REFUNDED).stream()
+			.map(State::name)
+			.collect(Collectors.toUnmodifiableList());
+
+	private DogecoinACCTv1TradeBot() {
+	}
+
+	public static synchronized DogecoinACCTv1TradeBot getInstance() {
+		if (instance == null)
+			instance = new DogecoinACCTv1TradeBot();
+
+		return instance;
+	}
+
+	@Override
+	public List<String> getEndStates() {
+		return this.endStates;
+	}
+
+	/**
+	 * Creates a new trade-bot entry from the "Bob" viewpoint, i.e. OFFERing QORT in exchange for DOGE.
+	 * <p>
+	 * Generates:
+	 * <ul>
+	 * 	<li>new 'trade' private key</li>
+	 * </ul>
+	 * Derives:
+	 * <ul>
+	 * 	<li>'native' (as in Qortal) public key, public key hash, address (starting with Q)</li>
+	 * 	<li>'foreign' (as in Dogecoin) public key, public key hash</li>
+	 * </ul>
+	 * A Qortal AT is then constructed including the following as constants in the 'data segment':
+	 * <ul>
+	 * 	<li>'native'/Qortal 'trade' address - used as a MESSAGE contact</li>
+	 * 	<li>'foreign'/Dogecoin public key hash - used by Alice's P2SH scripts to allow redeem</li>
+	 * 	<li>QORT amount on offer by Bob</li>
+	 * 	<li>DOGE amount expected in return by Bob (from Alice)</li>
+	 * 	<li>trading timeout, in case things go wrong and everyone needs to refund</li>
+	 * </ul>
+	 * Returns a DEPLOY_AT transaction that needs to be signed and broadcast to the Qortal network.
+	 * <p>
+	 * Trade-bot will wait for Bob's AT to be deployed before taking next step.
+	 * <p>
+	 * @param repository
+	 * @param tradeBotCreateRequest
+	 * @return raw, unsigned DEPLOY_AT transaction
+	 * @throws DataException
+	 */
+	public byte[] createTrade(Repository repository, TradeBotCreateRequest tradeBotCreateRequest) throws DataException {
+		byte[] tradePrivateKey = TradeBot.generateTradePrivateKey();
+
+		byte[] tradeNativePublicKey = TradeBot.deriveTradeNativePublicKey(tradePrivateKey);
+		byte[] tradeNativePublicKeyHash = Crypto.hash160(tradeNativePublicKey);
+		String tradeNativeAddress = Crypto.toAddress(tradeNativePublicKey);
+
+		byte[] tradeForeignPublicKey = TradeBot.deriveTradeForeignPublicKey(tradePrivateKey);
+		byte[] tradeForeignPublicKeyHash = Crypto.hash160(tradeForeignPublicKey);
+
+		// Convert Dogecoin receiving address into public key hash (we only support P2PKH at this time)
+		Address dogecoinReceivingAddress;
+		try {
+			dogecoinReceivingAddress = Address.fromString(Dogecoin.getInstance().getNetworkParameters(), tradeBotCreateRequest.receivingAddress);
+		} catch (AddressFormatException e) {
+			throw new DataException("Unsupported Dogecoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+		}
+		if (dogecoinReceivingAddress.getOutputScriptType() != ScriptType.P2PKH)
+			throw new DataException("Unsupported Dogecoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+
+		byte[] dogecoinReceivingAccountInfo = dogecoinReceivingAddress.getHash();
+
+		PublicKeyAccount creator = new PublicKeyAccount(repository, tradeBotCreateRequest.creatorPublicKey);
+
+		// Deploy AT
+		long timestamp = NTP.getTime();
+		byte[] reference = creator.getLastReference();
+		long fee = 0L;
+		byte[] signature = null;
+		BaseTransactionData baseTransactionData = new BaseTransactionData(timestamp, Group.NO_GROUP, reference, creator.getPublicKey(), fee, signature);
+
+		String name = "QORT/DOGE ACCT";
+		String description = "QORT/DOGE cross-chain trade";
+		String aTType = "ACCT";
+		String tags = "ACCT QORT DOGE";
+		byte[] creationBytes = DogecoinACCTv1.buildQortalAT(tradeNativeAddress, tradeForeignPublicKeyHash, tradeBotCreateRequest.qortAmount,
+				tradeBotCreateRequest.foreignAmount, tradeBotCreateRequest.tradeTimeout);
+		long amount = tradeBotCreateRequest.fundingQortAmount;
+
+		DeployAtTransactionData deployAtTransactionData = new DeployAtTransactionData(baseTransactionData, name, description, aTType, tags, creationBytes, amount, Asset.QORT);
+
+		DeployAtTransaction deployAtTransaction = new DeployAtTransaction(repository, deployAtTransactionData);
+		fee = deployAtTransaction.calcRecommendedFee();
+		deployAtTransactionData.setFee(fee);
+
+		DeployAtTransaction.ensureATAddress(deployAtTransactionData);
+		String atAddress = deployAtTransactionData.getAtAddress();
+
+		TradeBotData tradeBotData =  new TradeBotData(tradePrivateKey, DogecoinACCTv1.NAME,
+				State.BOB_WAITING_FOR_AT_CONFIRM.name(), State.BOB_WAITING_FOR_AT_CONFIRM.value,
+				creator.getAddress(), atAddress, timestamp, tradeBotCreateRequest.qortAmount,
+				tradeNativePublicKey, tradeNativePublicKeyHash, tradeNativeAddress,
+				null, null,
+				SupportedBlockchain.DOGECOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				tradeBotCreateRequest.foreignAmount, null, null, null, dogecoinReceivingAccountInfo);
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Built AT %s. Waiting for deployment", atAddress));
+
+		// Attempt to backup the trade bot data
+		TradeBot.backupTradeBotData(repository, null);
+
+		// Return to user for signing and broadcast as we don't have their Qortal private key
+		try {
+			return DeployAtTransactionTransformer.toBytes(deployAtTransactionData);
+		} catch (TransformationException e) {
+			throw new DataException("Failed to transform DEPLOY_AT transaction?", e);
+		}
+	}
+
+	/**
+	 * Creates a trade-bot entry from the 'Alice' viewpoint, i.e. matching DOGE to an existing offer.
+	 * <p>
+	 * Requires a chosen trade offer from Bob, passed by <tt>crossChainTradeData</tt>
+	 * and access to a Dogecoin wallet via <tt>xprv58</tt>.
+	 * <p>
+	 * The <tt>crossChainTradeData</tt> contains the current trade offer state
+	 * as extracted from the AT's data segment.
+	 * <p>
+	 * Access to a funded wallet is via a Dogecoin BIP32 hierarchical deterministic key,
+	 * passed via <tt>xprv58</tt>.
+	 * <b>This key will be stored in your node's database</b>
+	 * to allow trade-bot to create/fund the necessary P2SH transactions!
+	 * However, due to the nature of BIP32 keys, it is possible to give the trade-bot
+	 * only a subset of wallet access (see BIP32 for more details).
+	 * <p>
+	 * As an example, the xprv58 can be extract from a <i>legacy, password-less</i>
+	 * Electrum wallet by going to the console tab and entering:<br>
+	 * <tt>wallet.keystore.xprv</tt><br>
+	 * which should result in a base58 string starting with either 'xprv' (for Dogecoin main-net)
+	 * or 'tprv' for (Dogecoin test-net).
+	 * <p>
+	 * It is envisaged that the value in <tt>xprv58</tt> will actually come from a Qortal-UI-managed wallet.
+	 * <p>
+	 * If sufficient funds are available, <b>this method will actually fund the P2SH-A</b>
+	 * with the Dogecoin amount expected by 'Bob'.
+	 * <p>
+	 * If the Dogecoin transaction is successfully broadcast to the network then
+	 * we also send a MESSAGE to Bob's trade-bot to let them know.
+	 * <p>
+	 * The trade-bot entry is saved to the repository and the cross-chain trading process commences.
+	 * <p>
+	 * @param repository
+	 * @param crossChainTradeData chosen trade OFFER that Alice wants to match
+	 * @param xprv58 funded wallet xprv in base58
+	 * @return true if P2SH-A funding transaction successfully broadcast to Dogecoin network, false otherwise
+	 * @throws DataException
+	 */
+	public ResponseResult startResponse(Repository repository, ATData atData, ACCT acct, CrossChainTradeData crossChainTradeData, String xprv58, String receivingAddress) throws DataException {
+		byte[] tradePrivateKey = TradeBot.generateTradePrivateKey();
+		byte[] secretA = TradeBot.generateSecret();
+		byte[] hashOfSecretA = Crypto.hash160(secretA);
+
+		byte[] tradeNativePublicKey = TradeBot.deriveTradeNativePublicKey(tradePrivateKey);
+		byte[] tradeNativePublicKeyHash = Crypto.hash160(tradeNativePublicKey);
+		String tradeNativeAddress = Crypto.toAddress(tradeNativePublicKey);
+
+		byte[] tradeForeignPublicKey = TradeBot.deriveTradeForeignPublicKey(tradePrivateKey);
+		byte[] tradeForeignPublicKeyHash = Crypto.hash160(tradeForeignPublicKey);
+		byte[] receivingPublicKeyHash = Base58.decode(receivingAddress); // Actually the whole address, not just PKH
+
+		// We need to generate lockTime-A: add tradeTimeout to now
+		long now = NTP.getTime();
+		int lockTimeA = crossChainTradeData.tradeTimeout * 60 + (int) (now / 1000L);
+
+		TradeBotData tradeBotData =  new TradeBotData(tradePrivateKey, DogecoinACCTv1.NAME,
+				State.ALICE_WAITING_FOR_AT_LOCK.name(), State.ALICE_WAITING_FOR_AT_LOCK.value,
+				receivingAddress, crossChainTradeData.qortalAtAddress, now, crossChainTradeData.qortAmount,
+				tradeNativePublicKey, tradeNativePublicKeyHash, tradeNativeAddress,
+				secretA, hashOfSecretA,
+				SupportedBlockchain.DOGECOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				crossChainTradeData.expectedForeignAmount, xprv58, null, lockTimeA, receivingPublicKeyHash);
+
+		// Attempt to backup the trade bot data
+		// Include tradeBotData as an additional parameter, since it's not in the repository yet
+		TradeBot.backupTradeBotData(repository, Arrays.asList(tradeBotData));
+
+		// Check we have enough funds via xprv58 to fund P2SH to cover expectedForeignAmount
+		long p2shFee;
+		try {
+			p2shFee = Dogecoin.getInstance().getP2shFee(now);
+		} catch (ForeignBlockchainException e) {
+			LOGGER.debug("Couldn't estimate Dogecoin fees?");
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		// Do not include fee for funding transaction as this is covered by buildSpend()
+		long amountA = crossChainTradeData.expectedForeignAmount + p2shFee /*redeeming/refunding P2SH-A*/;
+
+		// P2SH-A to be funded
+		byte[] redeemScriptBytes = BitcoinyHTLC.buildScript(tradeForeignPublicKeyHash, lockTimeA, crossChainTradeData.creatorForeignPKH, hashOfSecretA);
+		String p2shAddress = Dogecoin.getInstance().deriveP2shAddress(redeemScriptBytes);
+
+		// Build transaction for funding P2SH-A
+		Transaction p2shFundingTransaction = Dogecoin.getInstance().buildSpend(tradeBotData.getForeignKey(), p2shAddress, amountA);
+		if (p2shFundingTransaction == null) {
+			LOGGER.debug("Unable to build P2SH-A funding transaction - lack of funds?");
+			return ResponseResult.BALANCE_ISSUE;
+		}
+
+		try {
+			Dogecoin.getInstance().broadcastTransaction(p2shFundingTransaction);
+		} catch (ForeignBlockchainException e) {
+			// We couldn't fund P2SH-A at this time
+			LOGGER.debug("Couldn't broadcast P2SH-A funding transaction?");
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		// Attempt to send MESSAGE to Bob's Qortal trade address
+		byte[] messageData = DogecoinACCTv1.buildOfferMessage(tradeBotData.getTradeForeignPublicKeyHash(), tradeBotData.getHashOfSecret(), tradeBotData.getLockTimeA());
+		String messageRecipient = crossChainTradeData.qortalCreatorTradeAddress;
+
+		boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, messageData);
+		if (!isMessageAlreadySent) {
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK) {
+				LOGGER.warn(() -> String.format("Unable to send MESSAGE to Bob's trade-bot %s: %s", messageRecipient, result.name()));
+				return ResponseResult.NETWORK_ISSUE;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Funding P2SH-A %s. Messaged Bob. Waiting for AT-lock", p2shAddress));
+
+		return ResponseResult.OK;
+	}
+
+	@Override
+	public boolean canDelete(Repository repository, TradeBotData tradeBotData) throws DataException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null)
+			return true;
+
+		// If the AT doesn't exist then we might as well let the user tidy up
+		if (!repository.getATRepository().exists(tradeBotData.getAtAddress()))
+			return true;
+
+		switch (tradeBotState) {
+			case BOB_WAITING_FOR_AT_CONFIRM:
+			case ALICE_DONE:
+			case BOB_DONE:
+			case ALICE_REFUNDED:
+			case BOB_REFUNDED:
+			case ALICE_REFUNDING_A:
+				return true;
+
+			default:
+				return false;
+		}
+	}
+
+	@Override
+	public void progress(Repository repository, TradeBotData tradeBotData) throws DataException, ForeignBlockchainException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null) {
+			LOGGER.info(() -> String.format("Trade-bot entry for AT %s has invalid state?", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		ATData atData = null;
+		CrossChainTradeData tradeData = null;
+
+		if (tradeBotState.requiresAtData) {
+			// Attempt to fetch AT data
+			atData = repository.getATRepository().fromATAddress(tradeBotData.getAtAddress());
+			if (atData == null) {
+				LOGGER.debug(() -> String.format("Unable to fetch trade AT %s from repository", tradeBotData.getAtAddress()));
+				return;
+			}
+
+			if (tradeBotState.requiresTradeData) {
+				tradeData = DogecoinACCTv1.getInstance().populateTradeData(repository, atData);
+				if (tradeData == null) {
+					LOGGER.warn(() -> String.format("Unable to fetch ACCT trade data for AT %s from repository", tradeBotData.getAtAddress()));
+					return;
+				}
+			}
+		}
+
+		switch (tradeBotState) {
+			case BOB_WAITING_FOR_AT_CONFIRM:
+				handleBobWaitingForAtConfirm(repository, tradeBotData);
+				break;
+
+			case BOB_WAITING_FOR_MESSAGE:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleBobWaitingForMessage(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_WAITING_FOR_AT_LOCK:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleAliceWaitingForAtLock(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case BOB_WAITING_FOR_AT_REDEEM:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleBobWaitingForAtRedeem(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_DONE:
+			case BOB_DONE:
+				break;
+
+			case ALICE_REFUNDING_A:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleAliceRefundingP2shA(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_REFUNDED:
+			case BOB_REFUNDED:
+				break;
+		}
+	}
+
+	/**
+	 * Trade-bot is waiting for Bob's AT to deploy.
+	 * <p>
+	 * If AT is deployed, then trade-bot's next step is to wait for MESSAGE from Alice.
+	 */
+	private void handleBobWaitingForAtConfirm(Repository repository, TradeBotData tradeBotData) throws DataException {
+		if (!repository.getATRepository().exists(tradeBotData.getAtAddress())) {
+			if (NTP.getTime() - tradeBotData.getTimestamp() <= MAX_AT_CONFIRMATION_PERIOD)
+				return;
+
+			// We've waited ages for AT to be confirmed into a block but something has gone awry.
+			// After this long we assume transaction loss so give up with trade-bot entry too.
+			tradeBotData.setState(State.BOB_REFUNDED.name());
+			tradeBotData.setStateValue(State.BOB_REFUNDED.value);
+			tradeBotData.setTimestamp(NTP.getTime());
+			// We delete trade-bot entry here instead of saving, hence not using updateTradeBotState()
+			repository.getCrossChainRepository().delete(tradeBotData.getTradePrivateKey());
+			repository.saveChanges();
+
+			LOGGER.info(() -> String.format("AT %s never confirmed. Giving up on trade", tradeBotData.getAtAddress()));
+			TradeBot.notifyStateChange(tradeBotData);
+			return;
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_WAITING_FOR_MESSAGE,
+				() -> String.format("AT %s confirmed ready. Waiting for trade message", tradeBotData.getAtAddress()));
+	}
+
+	/**
+	 * Trade-bot is waiting for MESSAGE from Alice's trade-bot, containing Alice's trade info.
+	 * <p>
+	 * It's possible Bob has cancelling his trade offer, receiving an automatic QORT refund,
+	 * in which case trade-bot is done with this specific trade and finalizes on refunded state.
+	 * <p>
+	 * Assuming trade is still on offer, trade-bot checks the contents of MESSAGE from Alice's trade-bot.
+	 * <p>
+	 * Details from Alice are used to derive P2SH-A address and this is checked for funding balance.
+	 * <p>
+	 * Assuming P2SH-A has at least expected Dogecoin balance,
+	 * Bob's trade-bot constructs a zero-fee, PoW MESSAGE to send to Bob's AT with more trade details.
+	 * <p>
+	 * On processing this MESSAGE, Bob's AT should switch into 'TRADE' mode and only trade with Alice.
+	 * <p>
+	 * Trade-bot's next step is to wait for Alice to redeem the AT, which will allow Bob to
+	 * extract secret-A needed to redeem Alice's P2SH.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleBobWaitingForMessage(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// If AT has finished then Bob likely cancelled his trade offer
+		if (atData.getIsFinished()) {
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_REFUNDED,
+					() -> String.format("AT %s cancelled - trading aborted", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		Dogecoin dogecoin = Dogecoin.getInstance();
+
+		String address = tradeBotData.getTradeNativeAddress();
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(null, address, null, null, null);
+
+		for (MessageTransactionData messageTransactionData : messageTransactionsData) {
+			if (messageTransactionData.isText())
+				continue;
+
+			// We're expecting: HASH160(secret-A), Alice's Dogecoin pubkeyhash and lockTime-A
+			byte[] messageData = messageTransactionData.getData();
+			DogecoinACCTv1.OfferMessageData offerMessageData = DogecoinACCTv1.extractOfferMessageData(messageData);
+			if (offerMessageData == null)
+				continue;
+
+			byte[] aliceForeignPublicKeyHash = offerMessageData.partnerDogecoinPKH;
+			byte[] hashOfSecretA = offerMessageData.hashOfSecretA;
+			int lockTimeA = (int) offerMessageData.lockTimeA;
+			long messageTimestamp = messageTransactionData.getTimestamp();
+			int refundTimeout = DogecoinACCTv1.calcRefundTimeout(messageTimestamp, lockTimeA);
+
+			// Determine P2SH-A address and confirm funded
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(aliceForeignPublicKeyHash, lockTimeA, tradeBotData.getTradeForeignPublicKeyHash(), hashOfSecretA);
+			String p2shAddressA = dogecoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Dogecoin.getInstance().getP2shFee(feeTimestamp);
+			final long minimumAmountA = tradeBotData.getForeignAmount() + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(dogecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+			switch (htlcStatusA) {
+				case UNFUNDED:
+				case FUNDING_IN_PROGRESS:
+					// There might be another MESSAGE from someone else with an actually funded P2SH-A...
+					continue;
+
+				case REDEEM_IN_PROGRESS:
+				case REDEEMED:
+					// We've already redeemed this?
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_DONE,
+							() -> String.format("P2SH-A %s already spent? Assuming trade complete", p2shAddressA));
+					return;
+
+				case REFUND_IN_PROGRESS:
+				case REFUNDED:
+					// This P2SH-A is burnt, but there might be another MESSAGE from someone else with an actually funded P2SH-A...
+					continue;
+
+				case FUNDED:
+					// Fall-through out of switch...
+					break;
+			}
+
+			// Good to go - send MESSAGE to AT
+
+			String aliceNativeAddress = Crypto.toAddress(messageTransactionData.getCreatorPublicKey());
+
+			// Build outgoing message, padding each part to 32 bytes to make it easier for AT to consume
+			byte[] outgoingMessageData = DogecoinACCTv1.buildTradeMessage(aliceNativeAddress, aliceForeignPublicKeyHash, hashOfSecretA, lockTimeA, refundTimeout);
+			String messageRecipient = tradeBotData.getAtAddress();
+
+			boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, outgoingMessageData);
+			if (!isMessageAlreadySent) {
+				PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+				MessageTransaction outgoingMessageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, outgoingMessageData, false, false);
+
+				outgoingMessageTransaction.computeNonce();
+				outgoingMessageTransaction.sign(sender);
+
+				// reset repository state to prevent deadlock
+				repository.discardChanges();
+				ValidationResult result = outgoingMessageTransaction.importAsUnconfirmed();
+
+				if (result != ValidationResult.OK) {
+					LOGGER.warn(() -> String.format("Unable to send MESSAGE to AT %s: %s", messageRecipient, result.name()));
+					return;
+				}
+			}
+
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_WAITING_FOR_AT_REDEEM,
+					() -> String.format("Locked AT %s to %s. Waiting for AT redeem", tradeBotData.getAtAddress(), aliceNativeAddress));
+
+			return;
+		}
+	}
+
+	/**
+	 * Trade-bot is waiting for Bob's AT to switch to TRADE mode and lock trade to Alice only.
+	 * <p>
+	 * It's possible that Bob has cancelled his trade offer in the mean time, or that somehow
+	 * this process has taken so long that we've reached P2SH-A's locktime, or that someone else
+	 * has managed to trade with Bob. In any of these cases, trade-bot switches to begin the refunding process.
+	 * <p>
+	 * Assuming Bob's AT is locked to Alice, trade-bot checks AT's state data to make sure it is correct.
+	 * <p>
+	 * If all is well, trade-bot then redeems AT using Alice's secret-A, releasing Bob's QORT to Alice.
+	 * <p>
+	 * In revealing a valid secret-A, Bob can then redeem the DOGE funds from P2SH-A.
+	 * <p>
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleAliceWaitingForAtLock(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		if (aliceUnexpectedState(repository, tradeBotData, atData, crossChainTradeData))
+			return;
+
+		Dogecoin dogecoin = Dogecoin.getInstance();
+		int lockTimeA = tradeBotData.getLockTimeA();
+
+		// Refund P2SH-A if we've passed lockTime-A
+		if (NTP.getTime() >= lockTimeA * 1000L) {
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeA, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+			String p2shAddressA = dogecoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Dogecoin.getInstance().getP2shFee(feeTimestamp);
+			long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(dogecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+			switch (htlcStatusA) {
+				case UNFUNDED:
+				case FUNDING_IN_PROGRESS:
+				case FUNDED:
+					break;
+
+				case REDEEM_IN_PROGRESS:
+				case REDEEMED:
+					// Already redeemed?
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+							() -> String.format("P2SH-A %s already spent? Assuming trade completed", p2shAddressA));
+					return;
+
+				case REFUND_IN_PROGRESS:
+				case REFUNDED:
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDED,
+							() -> String.format("P2SH-A %s already refunded. Trade aborted", p2shAddressA));
+					return;
+
+			}
+
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+					() -> atData.getIsFinished()
+					? String.format("AT %s cancelled. Refunding P2SH-A %s - aborting trade", tradeBotData.getAtAddress(), p2shAddressA)
+					: String.format("LockTime-A reached, refunding P2SH-A %s - aborting trade", p2shAddressA));
+
+			return;
+		}
+
+		// We're waiting for AT to be in TRADE mode
+		if (crossChainTradeData.mode != AcctMode.TRADING)
+			return;
+
+		// AT is in TRADE mode and locked to us as checked by aliceUnexpectedState() above
+
+		// Find our MESSAGE to AT from previous state
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(tradeBotData.getTradeNativePublicKey(),
+				crossChainTradeData.qortalCreatorTradeAddress, null, null, null);
+		if (messageTransactionsData == null || messageTransactionsData.isEmpty()) {
+			LOGGER.warn(() -> String.format("Unable to find our message to trade creator %s?", crossChainTradeData.qortalCreatorTradeAddress));
+			return;
+		}
+
+		long recipientMessageTimestamp = messageTransactionsData.get(0).getTimestamp();
+		int refundTimeout = DogecoinACCTv1.calcRefundTimeout(recipientMessageTimestamp, lockTimeA);
+
+		// Our calculated refundTimeout should match AT's refundTimeout
+		if (refundTimeout != crossChainTradeData.refundTimeout) {
+			LOGGER.debug(() -> String.format("Trade AT refundTimeout '%d' doesn't match our refundTimeout '%d'", crossChainTradeData.refundTimeout, refundTimeout));
+			// We'll eventually refund
+			return;
+		}
+
+		// We're good to redeem AT
+
+		// Send 'redeem' MESSAGE to AT using both secret
+		byte[] secretA = tradeBotData.getSecret();
+		String qortalReceivingAddress = Base58.encode(tradeBotData.getReceivingAccountInfo()); // Actually contains whole address, not just PKH
+		byte[] messageData = DogecoinACCTv1.buildRedeemMessage(secretA, qortalReceivingAddress);
+		String messageRecipient = tradeBotData.getAtAddress();
+
+		boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, messageData);
+		if (!isMessageAlreadySent) {
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// Reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK) {
+				LOGGER.warn(() -> String.format("Unable to send MESSAGE to AT %s: %s", messageRecipient, result.name()));
+				return;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+				() -> String.format("Redeeming AT %s. Funds should arrive at %s",
+						tradeBotData.getAtAddress(), qortalReceivingAddress));
+	}
+
+	/**
+	 * Trade-bot is waiting for Alice to redeem Bob's AT, thus revealing secret-A which is required to spend the DOGE funds from P2SH-A.
+	 * <p>
+	 * It's possible that Bob's AT has reached its trading timeout and automatically refunded QORT back to Bob. In which case,
+	 * trade-bot is done with this specific trade and finalizes in refunded state.
+	 * <p>
+	 * Assuming trade-bot can extract a valid secret-A from Alice's MESSAGE then trade-bot uses that to redeem the DOGE funds from P2SH-A
+	 * to Bob's 'foreign'/Dogecoin trade legacy-format address, as derived from trade private key.
+	 * <p>
+	 * (This could potentially be 'improved' to send DOGE to any address of Bob's choosing by changing the transaction output).
+	 * <p>
+	 * If trade-bot successfully broadcasts the transaction, then this specific trade is done.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleBobWaitingForAtRedeem(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// AT should be 'finished' once Alice has redeemed QORT funds
+		if (!atData.getIsFinished())
+			// Not finished yet
+			return;
+
+		// If AT is REFUNDED or CANCELLED then something has gone wrong
+		if (crossChainTradeData.mode == AcctMode.REFUNDED || crossChainTradeData.mode == AcctMode.CANCELLED) {
+			// Alice hasn't redeemed the QORT, so there is no point in trying to redeem the DOGE
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_REFUNDED,
+					() -> String.format("AT %s has auto-refunded - trade aborted", tradeBotData.getAtAddress()));
+
+			return;
+		}
+
+		byte[] secretA = DogecoinACCTv1.getInstance().findSecretA(repository, crossChainTradeData);
+		if (secretA == null) {
+			LOGGER.debug(() -> String.format("Unable to find secret-A from redeem message to AT %s?", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		// Use secret-A to redeem P2SH-A
+
+		Dogecoin dogecoin = Dogecoin.getInstance();
+
+		byte[] receivingAccountInfo = tradeBotData.getReceivingAccountInfo();
+		int lockTimeA = crossChainTradeData.lockTimeA;
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(crossChainTradeData.partnerForeignPKH, lockTimeA, crossChainTradeData.creatorForeignPKH, crossChainTradeData.hashOfSecretA);
+		String p2shAddressA = dogecoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Dogecoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(dogecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+		switch (htlcStatusA) {
+			case UNFUNDED:
+			case FUNDING_IN_PROGRESS:
+				// P2SH-A suddenly not funded? Our best bet at this point is to hope for AT auto-refund
+				return;
+
+			case REDEEM_IN_PROGRESS:
+			case REDEEMED:
+				// Double-check that we have redeemed P2SH-A...
+				break;
+
+			case REFUND_IN_PROGRESS:
+			case REFUNDED:
+				// Wait for AT to auto-refund
+				return;
+
+			case FUNDED: {
+				Coin redeemAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
+				ECKey redeemKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
+				List<TransactionOutput> fundingOutputs = dogecoin.getUnspentOutputs(p2shAddressA);
+
+				Transaction p2shRedeemTransaction = BitcoinyHTLC.buildRedeemTransaction(dogecoin.getNetworkParameters(), redeemAmount, redeemKey,
+						fundingOutputs, redeemScriptA, secretA, receivingAccountInfo);
+
+				dogecoin.broadcastTransaction(p2shRedeemTransaction);
+				break;
+			}
+		}
+
+		String receivingAddress = dogecoin.pkhToAddress(receivingAccountInfo);
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_DONE,
+				() -> String.format("P2SH-A %s redeemed. Funds should arrive at %s", tradeBotData.getAtAddress(), receivingAddress));
+	}
+
+	/**
+	 * Trade-bot is attempting to refund P2SH-A.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleAliceRefundingP2shA(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		int lockTimeA = tradeBotData.getLockTimeA();
+
+		// We can't refund P2SH-A until lockTime-A has passed
+		if (NTP.getTime() <= lockTimeA * 1000L)
+			return;
+
+		Dogecoin dogecoin = Dogecoin.getInstance();
+
+		// We can't refund P2SH-A until median block time has passed lockTime-A (see BIP113)
+		int medianBlockTime = dogecoin.getMedianBlockTime();
+		if (medianBlockTime <= lockTimeA)
+			return;
+
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeA, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+		String p2shAddressA = dogecoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Dogecoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(dogecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+		switch (htlcStatusA) {
+			case UNFUNDED:
+			case FUNDING_IN_PROGRESS:
+				// Still waiting for P2SH-A to be funded...
+				return;
+
+			case REDEEM_IN_PROGRESS:
+			case REDEEMED:
+				// Too late!
+				TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+						() -> String.format("P2SH-A %s already spent!", p2shAddressA));
+				return;
+
+			case REFUND_IN_PROGRESS:
+			case REFUNDED:
+				break;
+
+			case FUNDED:{
+				Coin refundAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
+				ECKey refundKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
+				List<TransactionOutput> fundingOutputs = dogecoin.getUnspentOutputs(p2shAddressA);
+
+				// Determine receive address for refund
+				String receiveAddress = dogecoin.getUnusedReceiveAddress(tradeBotData.getForeignKey());
+				Address receiving = Address.fromString(dogecoin.getNetworkParameters(), receiveAddress);
+
+				Transaction p2shRefundTransaction = BitcoinyHTLC.buildRefundTransaction(dogecoin.getNetworkParameters(), refundAmount, refundKey,
+						fundingOutputs, redeemScriptA, lockTimeA, receiving.getHash());
+
+				dogecoin.broadcastTransaction(p2shRefundTransaction);
+				break;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDED,
+				() -> String.format("LockTime-A reached. Refunded P2SH-A %s. Trade aborted", p2shAddressA));
+	}
+
+	/**
+	 * Returns true if Alice finds AT unexpectedly cancelled, refunded, redeemed or locked to someone else.
+	 * <p>
+	 * Will automatically update trade-bot state to <tt>ALICE_REFUNDING_A</tt> or <tt>ALICE_DONE</tt> as necessary.
+	 * 
+	 * @throws DataException
+	 * @throws ForeignBlockchainException
+	 */
+	private boolean aliceUnexpectedState(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// This is OK
+		if (!atData.getIsFinished() && crossChainTradeData.mode == AcctMode.OFFERING)
+			return false;
+
+		boolean isAtLockedToUs = tradeBotData.getTradeNativeAddress().equals(crossChainTradeData.qortalPartnerAddress);
+
+		if (!atData.getIsFinished() && crossChainTradeData.mode == AcctMode.TRADING)
+			if (isAtLockedToUs) {
+				// AT is trading with us - OK
+				return false;
+			} else {
+				TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+						() -> String.format("AT %s trading with someone else: %s. Refunding & aborting trade", tradeBotData.getAtAddress(), crossChainTradeData.qortalPartnerAddress));
+
+				return true;
+			}
+
+		if (atData.getIsFinished() && crossChainTradeData.mode == AcctMode.REDEEMED && isAtLockedToUs) {
+			// We've redeemed already?
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+					() -> String.format("AT %s already redeemed by us. Trade completed", tradeBotData.getAtAddress()));
+		} else {
+			// Any other state is not good, so start defensive refund
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+					() -> String.format("AT %s cancelled/refunded/redeemed by someone else/invalid state. Refunding & aborting trade", tradeBotData.getAtAddress()));
+		}
+
+		return true;
+	}
+
+	private long calcFeeTimestamp(int lockTimeA, int tradeTimeout) {
+		return (lockTimeA - tradeTimeout * 60) * 1000L;
+	}
+
+}

src/main/java/org/qortal/controller/tradebot/DogecoinACCTv2TradeBot.java

@@ -0,0 +1,884 @@
+package org.qortal.controller.tradebot;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.bitcoinj.core.*;
+import org.bitcoinj.script.Script.ScriptType;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.account.PublicKeyAccount;
+import org.qortal.api.model.crosschain.TradeBotCreateRequest;
+import org.qortal.asset.Asset;
+import org.qortal.crosschain.*;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.data.transaction.BaseTransactionData;
+import org.qortal.data.transaction.DeployAtTransactionData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.transaction.DeployAtTransaction;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.transaction.DeployAtTransactionTransformer;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import static java.util.Arrays.stream;
+import static java.util.stream.Collectors.toMap;
+
+/**
+ * Performing cross-chain trading steps on behalf of user.
+ * <p>
+ * We deal with three different independent state-spaces here:
+ * <ul>
+ * 	<li>Qortal blockchain</li>
+ * 	<li>Foreign blockchain</li>
+ * 	<li>Trade-bot entries</li>
+ * </ul>
+ */
+public class DogecoinACCTv2TradeBot implements AcctTradeBot {
+
+	private static final Logger LOGGER = LogManager.getLogger(DogecoinACCTv2TradeBot.class);
+
+	public enum State implements TradeBot.StateNameAndValueSupplier {
+		BOB_WAITING_FOR_AT_CONFIRM(10, false, false),
+		BOB_WAITING_FOR_MESSAGE(15, true, true),
+		BOB_WAITING_FOR_AT_REDEEM(25, true, true),
+		BOB_DONE(30, false, false),
+		BOB_REFUNDED(35, false, false),
+
+		ALICE_WAITING_FOR_AT_LOCK(85, true, true),
+		ALICE_DONE(95, false, false),
+		ALICE_REFUNDING_A(105, true, true),
+		ALICE_REFUNDED(110, false, false);
+
+		private static final Map<Integer, State> map = stream(State.values()).collect(toMap(state -> state.value, state -> state));
+
+		public final int value;
+		public final boolean requiresAtData;
+		public final boolean requiresTradeData;
+
+		State(int value, boolean requiresAtData, boolean requiresTradeData) {
+			this.value = value;
+			this.requiresAtData = requiresAtData;
+			this.requiresTradeData = requiresTradeData;
+		}
+
+		public static State valueOf(int value) {
+			return map.get(value);
+		}
+
+		@Override
+		public String getState() {
+			return this.name();
+		}
+
+		@Override
+		public int getStateValue() {
+			return this.value;
+		}
+	}
+
+	/** Maximum time Bob waits for his AT creation transaction to be confirmed into a block. (milliseconds) */
+	private static final long MAX_AT_CONFIRMATION_PERIOD = 24 * 60 * 60 * 1000L; // ms
+
+	private static DogecoinACCTv2TradeBot instance;
+
+	private final List<String> endStates = Arrays.asList(State.BOB_DONE, State.BOB_REFUNDED, State.ALICE_DONE, State.ALICE_REFUNDING_A, State.ALICE_REFUNDED).stream()
+			.map(State::name)
+			.collect(Collectors.toUnmodifiableList());
+
+	private DogecoinACCTv2TradeBot() {
+	}
+
+	public static synchronized DogecoinACCTv2TradeBot getInstance() {
+		if (instance == null)
+			instance = new DogecoinACCTv2TradeBot();
+
+		return instance;
+	}
+
+	@Override
+	public List<String> getEndStates() {
+		return this.endStates;
+	}
+
+	/**
+	 * Creates a new trade-bot entry from the "Bob" viewpoint, i.e. OFFERing QORT in exchange for DOGE.
+	 * <p>
+	 * Generates:
+	 * <ul>
+	 * 	<li>new 'trade' private key</li>
+	 * </ul>
+	 * Derives:
+	 * <ul>
+	 * 	<li>'native' (as in Qortal) public key, public key hash, address (starting with Q)</li>
+	 * 	<li>'foreign' (as in Dogecoin) public key, public key hash</li>
+	 * </ul>
+	 * A Qortal AT is then constructed including the following as constants in the 'data segment':
+	 * <ul>
+	 * 	<li>'native'/Qortal 'trade' address - used as a MESSAGE contact</li>
+	 * 	<li>'foreign'/Dogecoin public key hash - used by Alice's P2SH scripts to allow redeem</li>
+	 * 	<li>QORT amount on offer by Bob</li>
+	 * 	<li>DOGE amount expected in return by Bob (from Alice)</li>
+	 * 	<li>trading timeout, in case things go wrong and everyone needs to refund</li>
+	 * </ul>
+	 * Returns a DEPLOY_AT transaction that needs to be signed and broadcast to the Qortal network.
+	 * <p>
+	 * Trade-bot will wait for Bob's AT to be deployed before taking next step.
+	 * <p>
+	 * @param repository
+	 * @param tradeBotCreateRequest
+	 * @return raw, unsigned DEPLOY_AT transaction
+	 * @throws DataException
+	 */
+	public byte[] createTrade(Repository repository, TradeBotCreateRequest tradeBotCreateRequest) throws DataException {
+		byte[] tradePrivateKey = TradeBot.generateTradePrivateKey();
+
+		byte[] tradeNativePublicKey = TradeBot.deriveTradeNativePublicKey(tradePrivateKey);
+		byte[] tradeNativePublicKeyHash = Crypto.hash160(tradeNativePublicKey);
+		String tradeNativeAddress = Crypto.toAddress(tradeNativePublicKey);
+
+		byte[] tradeForeignPublicKey = TradeBot.deriveTradeForeignPublicKey(tradePrivateKey);
+		byte[] tradeForeignPublicKeyHash = Crypto.hash160(tradeForeignPublicKey);
+
+		// Convert Dogecoin receiving address into public key hash (we only support P2PKH at this time)
+		Address dogecoinReceivingAddress;
+		try {
+			dogecoinReceivingAddress = Address.fromString(Dogecoin.getInstance().getNetworkParameters(), tradeBotCreateRequest.receivingAddress);
+		} catch (AddressFormatException e) {
+			throw new DataException("Unsupported Dogecoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+		}
+		if (dogecoinReceivingAddress.getOutputScriptType() != ScriptType.P2PKH)
+			throw new DataException("Unsupported Dogecoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+
+		byte[] dogecoinReceivingAccountInfo = dogecoinReceivingAddress.getHash();
+
+		PublicKeyAccount creator = new PublicKeyAccount(repository, tradeBotCreateRequest.creatorPublicKey);
+
+		// Deploy AT
+		long timestamp = NTP.getTime();
+		byte[] reference = creator.getLastReference();
+		long fee = 0L;
+		byte[] signature = null;
+		BaseTransactionData baseTransactionData = new BaseTransactionData(timestamp, Group.NO_GROUP, reference, creator.getPublicKey(), fee, signature);
+
+		String name = "QORT/DOGE ACCT";
+		String description = "QORT/DOGE cross-chain trade";
+		String aTType = "ACCT";
+		String tags = "ACCT QORT DOGE";
+		byte[] creationBytes = DogecoinACCTv2.buildQortalAT(tradeNativeAddress, tradeForeignPublicKeyHash, tradeBotCreateRequest.qortAmount,
+				tradeBotCreateRequest.foreignAmount, tradeBotCreateRequest.tradeTimeout);
+		long amount = tradeBotCreateRequest.fundingQortAmount;
+
+		DeployAtTransactionData deployAtTransactionData = new DeployAtTransactionData(baseTransactionData, name, description, aTType, tags, creationBytes, amount, Asset.QORT);
+
+		DeployAtTransaction deployAtTransaction = new DeployAtTransaction(repository, deployAtTransactionData);
+		fee = deployAtTransaction.calcRecommendedFee();
+		deployAtTransactionData.setFee(fee);
+
+		DeployAtTransaction.ensureATAddress(deployAtTransactionData);
+		String atAddress = deployAtTransactionData.getAtAddress();
+
+		TradeBotData tradeBotData =  new TradeBotData(tradePrivateKey, DogecoinACCTv2.NAME,
+				State.BOB_WAITING_FOR_AT_CONFIRM.name(), State.BOB_WAITING_FOR_AT_CONFIRM.value,
+				creator.getAddress(), atAddress, timestamp, tradeBotCreateRequest.qortAmount,
+				tradeNativePublicKey, tradeNativePublicKeyHash, tradeNativeAddress,
+				null, null,
+				SupportedBlockchain.DOGECOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				tradeBotCreateRequest.foreignAmount, null, null, null, dogecoinReceivingAccountInfo);
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Built AT %s. Waiting for deployment", atAddress));
+
+		// Attempt to backup the trade bot data
+		TradeBot.backupTradeBotData(repository, null);
+
+		// Return to user for signing and broadcast as we don't have their Qortal private key
+		try {
+			return DeployAtTransactionTransformer.toBytes(deployAtTransactionData);
+		} catch (TransformationException e) {
+			throw new DataException("Failed to transform DEPLOY_AT transaction?", e);
+		}
+	}
+
+	/**
+	 * Creates a trade-bot entry from the 'Alice' viewpoint, i.e. matching DOGE to an existing offer.
+	 * <p>
+	 * Requires a chosen trade offer from Bob, passed by <tt>crossChainTradeData</tt>
+	 * and access to a Dogecoin wallet via <tt>xprv58</tt>.
+	 * <p>
+	 * The <tt>crossChainTradeData</tt> contains the current trade offer state
+	 * as extracted from the AT's data segment.
+	 * <p>
+	 * Access to a funded wallet is via a Dogecoin BIP32 hierarchical deterministic key,
+	 * passed via <tt>xprv58</tt>.
+	 * <b>This key will be stored in your node's database</b>
+	 * to allow trade-bot to create/fund the necessary P2SH transactions!
+	 * However, due to the nature of BIP32 keys, it is possible to give the trade-bot
+	 * only a subset of wallet access (see BIP32 for more details).
+	 * <p>
+	 * As an example, the xprv58 can be extract from a <i>legacy, password-less</i>
+	 * Electrum wallet by going to the console tab and entering:<br>
+	 * <tt>wallet.keystore.xprv</tt><br>
+	 * which should result in a base58 string starting with either 'xprv' (for Dogecoin main-net)
+	 * or 'tprv' for (Dogecoin test-net).
+	 * <p>
+	 * It is envisaged that the value in <tt>xprv58</tt> will actually come from a Qortal-UI-managed wallet.
+	 * <p>
+	 * If sufficient funds are available, <b>this method will actually fund the P2SH-A</b>
+	 * with the Dogecoin amount expected by 'Bob'.
+	 * <p>
+	 * If the Dogecoin transaction is successfully broadcast to the network then
+	 * we also send a MESSAGE to Bob's trade-bot to let them know.
+	 * <p>
+	 * The trade-bot entry is saved to the repository and the cross-chain trading process commences.
+	 * <p>
+	 * @param repository
+	 * @param crossChainTradeData chosen trade OFFER that Alice wants to match
+	 * @param xprv58 funded wallet xprv in base58
+	 * @return true if P2SH-A funding transaction successfully broadcast to Dogecoin network, false otherwise
+	 * @throws DataException
+	 */
+	public ResponseResult startResponse(Repository repository, ATData atData, ACCT acct, CrossChainTradeData crossChainTradeData, String xprv58, String receivingAddress) throws DataException {
+		byte[] tradePrivateKey = TradeBot.generateTradePrivateKey();
+		byte[] secretA = TradeBot.generateSecret();
+		byte[] hashOfSecretA = Crypto.hash160(secretA);
+
+		byte[] tradeNativePublicKey = TradeBot.deriveTradeNativePublicKey(tradePrivateKey);
+		byte[] tradeNativePublicKeyHash = Crypto.hash160(tradeNativePublicKey);
+		String tradeNativeAddress = Crypto.toAddress(tradeNativePublicKey);
+
+		byte[] tradeForeignPublicKey = TradeBot.deriveTradeForeignPublicKey(tradePrivateKey);
+		byte[] tradeForeignPublicKeyHash = Crypto.hash160(tradeForeignPublicKey);
+		byte[] receivingPublicKeyHash = Base58.decode(receivingAddress); // Actually the whole address, not just PKH
+
+		// We need to generate lockTime-A: add tradeTimeout to now
+		long now = NTP.getTime();
+		int lockTimeA = crossChainTradeData.tradeTimeout * 60 + (int) (now / 1000L);
+
+		TradeBotData tradeBotData =  new TradeBotData(tradePrivateKey, DogecoinACCTv2.NAME,
+				State.ALICE_WAITING_FOR_AT_LOCK.name(), State.ALICE_WAITING_FOR_AT_LOCK.value,
+				receivingAddress, crossChainTradeData.qortalAtAddress, now, crossChainTradeData.qortAmount,
+				tradeNativePublicKey, tradeNativePublicKeyHash, tradeNativeAddress,
+				secretA, hashOfSecretA,
+				SupportedBlockchain.DOGECOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				crossChainTradeData.expectedForeignAmount, xprv58, null, lockTimeA, receivingPublicKeyHash);
+
+		// Attempt to backup the trade bot data
+		// Include tradeBotData as an additional parameter, since it's not in the repository yet
+		TradeBot.backupTradeBotData(repository, Arrays.asList(tradeBotData));
+
+		// Check we have enough funds via xprv58 to fund P2SH to cover expectedForeignAmount
+		long p2shFee;
+		try {
+			p2shFee = Dogecoin.getInstance().getP2shFee(now);
+		} catch (ForeignBlockchainException e) {
+			LOGGER.debug("Couldn't estimate Dogecoin fees?");
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		// Do not include fee for funding transaction as this is covered by buildSpend()
+		long amountA = crossChainTradeData.expectedForeignAmount + p2shFee /*redeeming/refunding P2SH-A*/;
+
+		// P2SH-A to be funded
+		byte[] redeemScriptBytes = BitcoinyHTLC.buildScript(tradeForeignPublicKeyHash, lockTimeA, crossChainTradeData.creatorForeignPKH, hashOfSecretA);
+		String p2shAddress = Dogecoin.getInstance().deriveP2shAddress(redeemScriptBytes);
+
+		// Build transaction for funding P2SH-A
+		Transaction p2shFundingTransaction = Dogecoin.getInstance().buildSpend(tradeBotData.getForeignKey(), p2shAddress, amountA);
+		if (p2shFundingTransaction == null) {
+			LOGGER.debug("Unable to build P2SH-A funding transaction - lack of funds?");
+			return ResponseResult.BALANCE_ISSUE;
+		}
+
+		try {
+			Dogecoin.getInstance().broadcastTransaction(p2shFundingTransaction);
+		} catch (ForeignBlockchainException e) {
+			// We couldn't fund P2SH-A at this time
+			LOGGER.debug("Couldn't broadcast P2SH-A funding transaction?");
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		// Attempt to send MESSAGE to Bob's Qortal trade address
+		byte[] messageData = DogecoinACCTv2.buildOfferMessage(tradeBotData.getTradeForeignPublicKeyHash(), tradeBotData.getHashOfSecret(), tradeBotData.getLockTimeA());
+		String messageRecipient = crossChainTradeData.qortalCreatorTradeAddress;
+
+		boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, messageData);
+		if (!isMessageAlreadySent) {
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK) {
+				LOGGER.warn(() -> String.format("Unable to send MESSAGE to Bob's trade-bot %s: %s", messageRecipient, result.name()));
+				return ResponseResult.NETWORK_ISSUE;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Funding P2SH-A %s. Messaged Bob. Waiting for AT-lock", p2shAddress));
+
+		return ResponseResult.OK;
+	}
+
+	@Override
+	public boolean canDelete(Repository repository, TradeBotData tradeBotData) throws DataException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null)
+			return true;
+
+		// If the AT doesn't exist then we might as well let the user tidy up
+		if (!repository.getATRepository().exists(tradeBotData.getAtAddress()))
+			return true;
+
+		switch (tradeBotState) {
+			case BOB_WAITING_FOR_AT_CONFIRM:
+			case ALICE_DONE:
+			case BOB_DONE:
+			case ALICE_REFUNDED:
+			case BOB_REFUNDED:
+				return true;
+
+			default:
+				return false;
+		}
+	}
+
+	@Override
+	public void progress(Repository repository, TradeBotData tradeBotData) throws DataException, ForeignBlockchainException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null) {
+			LOGGER.info(() -> String.format("Trade-bot entry for AT %s has invalid state?", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		ATData atData = null;
+		CrossChainTradeData tradeData = null;
+
+		if (tradeBotState.requiresAtData) {
+			// Attempt to fetch AT data
+			atData = repository.getATRepository().fromATAddress(tradeBotData.getAtAddress());
+			if (atData == null) {
+				LOGGER.debug(() -> String.format("Unable to fetch trade AT %s from repository", tradeBotData.getAtAddress()));
+				return;
+			}
+
+			if (tradeBotState.requiresTradeData) {
+				tradeData = DogecoinACCTv2.getInstance().populateTradeData(repository, atData);
+				if (tradeData == null) {
+					LOGGER.warn(() -> String.format("Unable to fetch ACCT trade data for AT %s from repository", tradeBotData.getAtAddress()));
+					return;
+				}
+			}
+		}
+
+		switch (tradeBotState) {
+			case BOB_WAITING_FOR_AT_CONFIRM:
+				handleBobWaitingForAtConfirm(repository, tradeBotData);
+				break;
+
+			case BOB_WAITING_FOR_MESSAGE:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleBobWaitingForMessage(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_WAITING_FOR_AT_LOCK:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleAliceWaitingForAtLock(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case BOB_WAITING_FOR_AT_REDEEM:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleBobWaitingForAtRedeem(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_DONE:
+			case BOB_DONE:
+				break;
+
+			case ALICE_REFUNDING_A:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleAliceRefundingP2shA(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_REFUNDED:
+			case BOB_REFUNDED:
+				break;
+		}
+	}
+
+	/**
+	 * Trade-bot is waiting for Bob's AT to deploy.
+	 * <p>
+	 * If AT is deployed, then trade-bot's next step is to wait for MESSAGE from Alice.
+	 */
+	private void handleBobWaitingForAtConfirm(Repository repository, TradeBotData tradeBotData) throws DataException {
+		if (!repository.getATRepository().exists(tradeBotData.getAtAddress())) {
+			if (NTP.getTime() - tradeBotData.getTimestamp() <= MAX_AT_CONFIRMATION_PERIOD)
+				return;
+
+			// We've waited ages for AT to be confirmed into a block but something has gone awry.
+			// After this long we assume transaction loss so give up with trade-bot entry too.
+			tradeBotData.setState(State.BOB_REFUNDED.name());
+			tradeBotData.setStateValue(State.BOB_REFUNDED.value);
+			tradeBotData.setTimestamp(NTP.getTime());
+			// We delete trade-bot entry here instead of saving, hence not using updateTradeBotState()
+			repository.getCrossChainRepository().delete(tradeBotData.getTradePrivateKey());
+			repository.saveChanges();
+
+			LOGGER.info(() -> String.format("AT %s never confirmed. Giving up on trade", tradeBotData.getAtAddress()));
+			TradeBot.notifyStateChange(tradeBotData);
+			return;
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_WAITING_FOR_MESSAGE,
+				() -> String.format("AT %s confirmed ready. Waiting for trade message", tradeBotData.getAtAddress()));
+	}
+
+	/**
+	 * Trade-bot is waiting for MESSAGE from Alice's trade-bot, containing Alice's trade info.
+	 * <p>
+	 * It's possible Bob has cancelling his trade offer, receiving an automatic QORT refund,
+	 * in which case trade-bot is done with this specific trade and finalizes on refunded state.
+	 * <p>
+	 * Assuming trade is still on offer, trade-bot checks the contents of MESSAGE from Alice's trade-bot.
+	 * <p>
+	 * Details from Alice are used to derive P2SH-A address and this is checked for funding balance.
+	 * <p>
+	 * Assuming P2SH-A has at least expected Dogecoin balance,
+	 * Bob's trade-bot constructs a zero-fee, PoW MESSAGE to send to Bob's AT with more trade details.
+	 * <p>
+	 * On processing this MESSAGE, Bob's AT should switch into 'TRADE' mode and only trade with Alice.
+	 * <p>
+	 * Trade-bot's next step is to wait for Alice to redeem the AT, which will allow Bob to
+	 * extract secret-A needed to redeem Alice's P2SH.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleBobWaitingForMessage(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// If AT has finished then Bob likely cancelled his trade offer
+		if (atData.getIsFinished()) {
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_REFUNDED,
+					() -> String.format("AT %s cancelled - trading aborted", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		Dogecoin dogecoin = Dogecoin.getInstance();
+
+		String address = tradeBotData.getTradeNativeAddress();
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(null, address, null, null, null);
+
+		for (MessageTransactionData messageTransactionData : messageTransactionsData) {
+			if (messageTransactionData.isText())
+				continue;
+
+			// We're expecting: HASH160(secret-A), Alice's Dogecoin pubkeyhash and lockTime-A
+			byte[] messageData = messageTransactionData.getData();
+			DogecoinACCTv2.OfferMessageData offerMessageData = DogecoinACCTv2.extractOfferMessageData(messageData);
+			if (offerMessageData == null)
+				continue;
+
+			byte[] aliceForeignPublicKeyHash = offerMessageData.partnerDogecoinPKH;
+			byte[] hashOfSecretA = offerMessageData.hashOfSecretA;
+			int lockTimeA = (int) offerMessageData.lockTimeA;
+			long messageTimestamp = messageTransactionData.getTimestamp();
+			int refundTimeout = DogecoinACCTv2.calcRefundTimeout(messageTimestamp, lockTimeA);
+
+			// Determine P2SH-A address and confirm funded
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(aliceForeignPublicKeyHash, lockTimeA, tradeBotData.getTradeForeignPublicKeyHash(), hashOfSecretA);
+			String p2shAddressA = dogecoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Dogecoin.getInstance().getP2shFee(feeTimestamp);
+			final long minimumAmountA = tradeBotData.getForeignAmount() + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(dogecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+			switch (htlcStatusA) {
+				case UNFUNDED:
+				case FUNDING_IN_PROGRESS:
+					// There might be another MESSAGE from someone else with an actually funded P2SH-A...
+					continue;
+
+				case REDEEM_IN_PROGRESS:
+				case REDEEMED:
+					// We've already redeemed this?
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_DONE,
+							() -> String.format("P2SH-A %s already spent? Assuming trade complete", p2shAddressA));
+					return;
+
+				case REFUND_IN_PROGRESS:
+				case REFUNDED:
+					// This P2SH-A is burnt, but there might be another MESSAGE from someone else with an actually funded P2SH-A...
+					continue;
+
+				case FUNDED:
+					// Fall-through out of switch...
+					break;
+			}
+
+			// Good to go - send MESSAGE to AT
+
+			String aliceNativeAddress = Crypto.toAddress(messageTransactionData.getCreatorPublicKey());
+
+			// Build outgoing message, padding each part to 32 bytes to make it easier for AT to consume
+			byte[] outgoingMessageData = DogecoinACCTv2.buildTradeMessage(aliceNativeAddress, aliceForeignPublicKeyHash, hashOfSecretA, lockTimeA, refundTimeout);
+			String messageRecipient = tradeBotData.getAtAddress();
+
+			boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, outgoingMessageData);
+			if (!isMessageAlreadySent) {
+				PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+				MessageTransaction outgoingMessageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, outgoingMessageData, false, false);
+
+				outgoingMessageTransaction.computeNonce();
+				outgoingMessageTransaction.sign(sender);
+
+				// reset repository state to prevent deadlock
+				repository.discardChanges();
+				ValidationResult result = outgoingMessageTransaction.importAsUnconfirmed();
+
+				if (result != ValidationResult.OK) {
+					LOGGER.warn(() -> String.format("Unable to send MESSAGE to AT %s: %s", messageRecipient, result.name()));
+					return;
+				}
+			}
+
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_WAITING_FOR_AT_REDEEM,
+					() -> String.format("Locked AT %s to %s. Waiting for AT redeem", tradeBotData.getAtAddress(), aliceNativeAddress));
+
+			return;
+		}
+	}
+
+	/**
+	 * Trade-bot is waiting for Bob's AT to switch to TRADE mode and lock trade to Alice only.
+	 * <p>
+	 * It's possible that Bob has cancelled his trade offer in the mean time, or that somehow
+	 * this process has taken so long that we've reached P2SH-A's locktime, or that someone else
+	 * has managed to trade with Bob. In any of these cases, trade-bot switches to begin the refunding process.
+	 * <p>
+	 * Assuming Bob's AT is locked to Alice, trade-bot checks AT's state data to make sure it is correct.
+	 * <p>
+	 * If all is well, trade-bot then redeems AT using Alice's secret-A, releasing Bob's QORT to Alice.
+	 * <p>
+	 * In revealing a valid secret-A, Bob can then redeem the DOGE funds from P2SH-A.
+	 * <p>
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleAliceWaitingForAtLock(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		if (aliceUnexpectedState(repository, tradeBotData, atData, crossChainTradeData))
+			return;
+
+		Dogecoin dogecoin = Dogecoin.getInstance();
+		int lockTimeA = tradeBotData.getLockTimeA();
+
+		// Refund P2SH-A if we've passed lockTime-A
+		if (NTP.getTime() >= lockTimeA * 1000L) {
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeA, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+			String p2shAddressA = dogecoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Dogecoin.getInstance().getP2shFee(feeTimestamp);
+			long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(dogecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+			switch (htlcStatusA) {
+				case UNFUNDED:
+				case FUNDING_IN_PROGRESS:
+				case FUNDED:
+					break;
+
+				case REDEEM_IN_PROGRESS:
+				case REDEEMED:
+					// Already redeemed?
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+							() -> String.format("P2SH-A %s already spent? Assuming trade completed", p2shAddressA));
+					return;
+
+				case REFUND_IN_PROGRESS:
+				case REFUNDED:
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDED,
+							() -> String.format("P2SH-A %s already refunded. Trade aborted", p2shAddressA));
+					return;
+
+			}
+
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+					() -> atData.getIsFinished()
+					? String.format("AT %s cancelled. Refunding P2SH-A %s - aborting trade", tradeBotData.getAtAddress(), p2shAddressA)
+					: String.format("LockTime-A reached, refunding P2SH-A %s - aborting trade", p2shAddressA));
+
+			return;
+		}
+
+		// We're waiting for AT to be in TRADE mode
+		if (crossChainTradeData.mode != AcctMode.TRADING)
+			return;
+
+		// AT is in TRADE mode and locked to us as checked by aliceUnexpectedState() above
+
+		// Find our MESSAGE to AT from previous state
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(tradeBotData.getTradeNativePublicKey(),
+				crossChainTradeData.qortalCreatorTradeAddress, null, null, null);
+		if (messageTransactionsData == null || messageTransactionsData.isEmpty()) {
+			LOGGER.warn(() -> String.format("Unable to find our message to trade creator %s?", crossChainTradeData.qortalCreatorTradeAddress));
+			return;
+		}
+
+		long recipientMessageTimestamp = messageTransactionsData.get(0).getTimestamp();
+		int refundTimeout = DogecoinACCTv2.calcRefundTimeout(recipientMessageTimestamp, lockTimeA);
+
+		// Our calculated refundTimeout should match AT's refundTimeout
+		if (refundTimeout != crossChainTradeData.refundTimeout) {
+			LOGGER.debug(() -> String.format("Trade AT refundTimeout '%d' doesn't match our refundTimeout '%d'", crossChainTradeData.refundTimeout, refundTimeout));
+			// We'll eventually refund
+			return;
+		}
+
+		// We're good to redeem AT
+
+		// Send 'redeem' MESSAGE to AT using both secret
+		byte[] secretA = tradeBotData.getSecret();
+		String qortalReceivingAddress = Base58.encode(tradeBotData.getReceivingAccountInfo()); // Actually contains whole address, not just PKH
+		byte[] messageData = DogecoinACCTv2.buildRedeemMessage(secretA, qortalReceivingAddress);
+		String messageRecipient = tradeBotData.getAtAddress();
+
+		boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, messageData);
+		if (!isMessageAlreadySent) {
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// Reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK) {
+				LOGGER.warn(() -> String.format("Unable to send MESSAGE to AT %s: %s", messageRecipient, result.name()));
+				return;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+				() -> String.format("Redeeming AT %s. Funds should arrive at %s",
+						tradeBotData.getAtAddress(), qortalReceivingAddress));
+	}
+
+	/**
+	 * Trade-bot is waiting for Alice to redeem Bob's AT, thus revealing secret-A which is required to spend the DOGE funds from P2SH-A.
+	 * <p>
+	 * It's possible that Bob's AT has reached its trading timeout and automatically refunded QORT back to Bob. In which case,
+	 * trade-bot is done with this specific trade and finalizes in refunded state.
+	 * <p>
+	 * Assuming trade-bot can extract a valid secret-A from Alice's MESSAGE then trade-bot uses that to redeem the DOGE funds from P2SH-A
+	 * to Bob's 'foreign'/Dogecoin trade legacy-format address, as derived from trade private key.
+	 * <p>
+	 * (This could potentially be 'improved' to send DOGE to any address of Bob's choosing by changing the transaction output).
+	 * <p>
+	 * If trade-bot successfully broadcasts the transaction, then this specific trade is done.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleBobWaitingForAtRedeem(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// AT should be 'finished' once Alice has redeemed QORT funds
+		if (!atData.getIsFinished())
+			// Not finished yet
+			return;
+
+		// If AT is REFUNDED or CANCELLED then something has gone wrong
+		if (crossChainTradeData.mode == AcctMode.REFUNDED || crossChainTradeData.mode == AcctMode.CANCELLED) {
+			// Alice hasn't redeemed the QORT, so there is no point in trying to redeem the DOGE
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_REFUNDED,
+					() -> String.format("AT %s has auto-refunded - trade aborted", tradeBotData.getAtAddress()));
+
+			return;
+		}
+
+		byte[] secretA = DogecoinACCTv2.getInstance().findSecretA(repository, crossChainTradeData);
+		if (secretA == null) {
+			LOGGER.debug(() -> String.format("Unable to find secret-A from redeem message to AT %s?", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		// Use secret-A to redeem P2SH-A
+
+		Dogecoin dogecoin = Dogecoin.getInstance();
+
+		byte[] receivingAccountInfo = tradeBotData.getReceivingAccountInfo();
+		int lockTimeA = crossChainTradeData.lockTimeA;
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(crossChainTradeData.partnerForeignPKH, lockTimeA, crossChainTradeData.creatorForeignPKH, crossChainTradeData.hashOfSecretA);
+		String p2shAddressA = dogecoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Dogecoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(dogecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+		switch (htlcStatusA) {
+			case UNFUNDED:
+			case FUNDING_IN_PROGRESS:
+				// P2SH-A suddenly not funded? Our best bet at this point is to hope for AT auto-refund
+				return;
+
+			case REDEEM_IN_PROGRESS:
+			case REDEEMED:
+				// Double-check that we have redeemed P2SH-A...
+				break;
+
+			case REFUND_IN_PROGRESS:
+			case REFUNDED:
+				// Wait for AT to auto-refund
+				return;
+
+			case FUNDED: {
+				Coin redeemAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
+				ECKey redeemKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
+				List<TransactionOutput> fundingOutputs = dogecoin.getUnspentOutputs(p2shAddressA);
+
+				Transaction p2shRedeemTransaction = BitcoinyHTLC.buildRedeemTransaction(dogecoin.getNetworkParameters(), redeemAmount, redeemKey,
+						fundingOutputs, redeemScriptA, secretA, receivingAccountInfo);
+
+				dogecoin.broadcastTransaction(p2shRedeemTransaction);
+				break;
+			}
+		}
+
+		String receivingAddress = dogecoin.pkhToAddress(receivingAccountInfo);
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_DONE,
+				() -> String.format("P2SH-A %s redeemed. Funds should arrive at %s", tradeBotData.getAtAddress(), receivingAddress));
+	}
+
+	/**
+	 * Trade-bot is attempting to refund P2SH-A.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleAliceRefundingP2shA(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		int lockTimeA = tradeBotData.getLockTimeA();
+
+		// We can't refund P2SH-A until lockTime-A has passed
+		if (NTP.getTime() <= lockTimeA * 1000L)
+			return;
+
+		Dogecoin dogecoin = Dogecoin.getInstance();
+
+		// We can't refund P2SH-A until median block time has passed lockTime-A (see BIP113)
+		int medianBlockTime = dogecoin.getMedianBlockTime();
+		if (medianBlockTime <= lockTimeA)
+			return;
+
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeA, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+		String p2shAddressA = dogecoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Dogecoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(dogecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+		switch (htlcStatusA) {
+			case UNFUNDED:
+			case FUNDING_IN_PROGRESS:
+				// Still waiting for P2SH-A to be funded...
+				return;
+
+			case REDEEM_IN_PROGRESS:
+			case REDEEMED:
+				// Too late!
+				TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+						() -> String.format("P2SH-A %s already spent!", p2shAddressA));
+				return;
+
+			case REFUND_IN_PROGRESS:
+			case REFUNDED:
+				break;
+
+			case FUNDED:{
+				Coin refundAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
+				ECKey refundKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
+				List<TransactionOutput> fundingOutputs = dogecoin.getUnspentOutputs(p2shAddressA);
+
+				// Determine receive address for refund
+				String receiveAddress = dogecoin.getUnusedReceiveAddress(tradeBotData.getForeignKey());
+				Address receiving = Address.fromString(dogecoin.getNetworkParameters(), receiveAddress);
+
+				Transaction p2shRefundTransaction = BitcoinyHTLC.buildRefundTransaction(dogecoin.getNetworkParameters(), refundAmount, refundKey,
+						fundingOutputs, redeemScriptA, lockTimeA, receiving.getHash());
+
+				dogecoin.broadcastTransaction(p2shRefundTransaction);
+				break;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDED,
+				() -> String.format("LockTime-A reached. Refunded P2SH-A %s. Trade aborted", p2shAddressA));
+	}
+
+	/**
+	 * Returns true if Alice finds AT unexpectedly cancelled, refunded, redeemed or locked to someone else.
+	 * <p>
+	 * Will automatically update trade-bot state to <tt>ALICE_REFUNDING_A</tt> or <tt>ALICE_DONE</tt> as necessary.
+	 * 
+	 * @throws DataException
+	 * @throws ForeignBlockchainException
+	 */
+	private boolean aliceUnexpectedState(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// This is OK
+		if (!atData.getIsFinished() && crossChainTradeData.mode == AcctMode.OFFERING)
+			return false;
+
+		boolean isAtLockedToUs = tradeBotData.getTradeNativeAddress().equals(crossChainTradeData.qortalPartnerAddress);
+
+		if (!atData.getIsFinished() && crossChainTradeData.mode == AcctMode.TRADING)
+			if (isAtLockedToUs) {
+				// AT is trading with us - OK
+				return false;
+			} else {
+				TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+						() -> String.format("AT %s trading with someone else: %s. Refunding & aborting trade", tradeBotData.getAtAddress(), crossChainTradeData.qortalPartnerAddress));
+
+				return true;
+			}
+
+		if (atData.getIsFinished() && crossChainTradeData.mode == AcctMode.REDEEMED && isAtLockedToUs) {
+			// We've redeemed already?
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+					() -> String.format("AT %s already redeemed by us. Trade completed", tradeBotData.getAtAddress()));
+		} else {
+			// Any other state is not good, so start defensive refund
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+					() -> String.format("AT %s cancelled/refunded/redeemed by someone else/invalid state. Refunding & aborting trade", tradeBotData.getAtAddress()));
+		}
+
+		return true;
+	}
+
+	private long calcFeeTimestamp(int lockTimeA, int tradeTimeout) {
+		return (lockTimeA - tradeTimeout * 60) * 1000L;
+	}
+
+}

src/main/java/org/qortal/controller/tradebot/DogecoinACCTv3TradeBot.java

@@ -0,0 +1,885 @@
+package org.qortal.controller.tradebot;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.bitcoinj.core.*;
+import org.bitcoinj.script.Script.ScriptType;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.account.PublicKeyAccount;
+import org.qortal.api.model.crosschain.TradeBotCreateRequest;
+import org.qortal.asset.Asset;
+import org.qortal.crosschain.*;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.data.transaction.BaseTransactionData;
+import org.qortal.data.transaction.DeployAtTransactionData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.transaction.DeployAtTransaction;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.transaction.DeployAtTransactionTransformer;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import static java.util.Arrays.stream;
+import static java.util.stream.Collectors.toMap;
+
+/**
+ * Performing cross-chain trading steps on behalf of user.
+ * <p>
+ * We deal with three different independent state-spaces here:
+ * <ul>
+ * 	<li>Qortal blockchain</li>
+ * 	<li>Foreign blockchain</li>
+ * 	<li>Trade-bot entries</li>
+ * </ul>
+ */
+public class DogecoinACCTv3TradeBot implements AcctTradeBot {
+
+	private static final Logger LOGGER = LogManager.getLogger(DogecoinACCTv3TradeBot.class);
+
+	public enum State implements TradeBot.StateNameAndValueSupplier {
+		BOB_WAITING_FOR_AT_CONFIRM(10, false, false),
+		BOB_WAITING_FOR_MESSAGE(15, true, true),
+		BOB_WAITING_FOR_AT_REDEEM(25, true, true),
+		BOB_DONE(30, false, false),
+		BOB_REFUNDED(35, false, false),
+
+		ALICE_WAITING_FOR_AT_LOCK(85, true, true),
+		ALICE_DONE(95, false, false),
+		ALICE_REFUNDING_A(105, true, true),
+		ALICE_REFUNDED(110, false, false);
+
+		private static final Map<Integer, State> map = stream(State.values()).collect(toMap(state -> state.value, state -> state));
+
+		public final int value;
+		public final boolean requiresAtData;
+		public final boolean requiresTradeData;
+
+		State(int value, boolean requiresAtData, boolean requiresTradeData) {
+			this.value = value;
+			this.requiresAtData = requiresAtData;
+			this.requiresTradeData = requiresTradeData;
+		}
+
+		public static State valueOf(int value) {
+			return map.get(value);
+		}
+
+		@Override
+		public String getState() {
+			return this.name();
+		}
+
+		@Override
+		public int getStateValue() {
+			return this.value;
+		}
+	}
+
+	/** Maximum time Bob waits for his AT creation transaction to be confirmed into a block. (milliseconds) */
+	private static final long MAX_AT_CONFIRMATION_PERIOD = 24 * 60 * 60 * 1000L; // ms
+
+	private static DogecoinACCTv3TradeBot instance;
+
+	private final List<String> endStates = Arrays.asList(State.BOB_DONE, State.BOB_REFUNDED, State.ALICE_DONE, State.ALICE_REFUNDING_A, State.ALICE_REFUNDED).stream()
+			.map(State::name)
+			.collect(Collectors.toUnmodifiableList());
+
+	private DogecoinACCTv3TradeBot() {
+	}
+
+	public static synchronized DogecoinACCTv3TradeBot getInstance() {
+		if (instance == null)
+			instance = new DogecoinACCTv3TradeBot();
+
+		return instance;
+	}
+
+	@Override
+	public List<String> getEndStates() {
+		return this.endStates;
+	}
+
+	/**
+	 * Creates a new trade-bot entry from the "Bob" viewpoint, i.e. OFFERing QORT in exchange for DOGE.
+	 * <p>
+	 * Generates:
+	 * <ul>
+	 * 	<li>new 'trade' private key</li>
+	 * </ul>
+	 * Derives:
+	 * <ul>
+	 * 	<li>'native' (as in Qortal) public key, public key hash, address (starting with Q)</li>
+	 * 	<li>'foreign' (as in Dogecoin) public key, public key hash</li>
+	 * </ul>
+	 * A Qortal AT is then constructed including the following as constants in the 'data segment':
+	 * <ul>
+	 * 	<li>'native'/Qortal 'trade' address - used as a MESSAGE contact</li>
+	 * 	<li>'foreign'/Dogecoin public key hash - used by Alice's P2SH scripts to allow redeem</li>
+	 * 	<li>QORT amount on offer by Bob</li>
+	 * 	<li>DOGE amount expected in return by Bob (from Alice)</li>
+	 * 	<li>trading timeout, in case things go wrong and everyone needs to refund</li>
+	 * </ul>
+	 * Returns a DEPLOY_AT transaction that needs to be signed and broadcast to the Qortal network.
+	 * <p>
+	 * Trade-bot will wait for Bob's AT to be deployed before taking next step.
+	 * <p>
+	 * @param repository
+	 * @param tradeBotCreateRequest
+	 * @return raw, unsigned DEPLOY_AT transaction
+	 * @throws DataException
+	 */
+	public byte[] createTrade(Repository repository, TradeBotCreateRequest tradeBotCreateRequest) throws DataException {
+		byte[] tradePrivateKey = TradeBot.generateTradePrivateKey();
+
+		byte[] tradeNativePublicKey = TradeBot.deriveTradeNativePublicKey(tradePrivateKey);
+		byte[] tradeNativePublicKeyHash = Crypto.hash160(tradeNativePublicKey);
+		String tradeNativeAddress = Crypto.toAddress(tradeNativePublicKey);
+
+		byte[] tradeForeignPublicKey = TradeBot.deriveTradeForeignPublicKey(tradePrivateKey);
+		byte[] tradeForeignPublicKeyHash = Crypto.hash160(tradeForeignPublicKey);
+
+		// Convert Dogecoin receiving address into public key hash (we only support P2PKH at this time)
+		Address dogecoinReceivingAddress;
+		try {
+			dogecoinReceivingAddress = Address.fromString(Dogecoin.getInstance().getNetworkParameters(), tradeBotCreateRequest.receivingAddress);
+		} catch (AddressFormatException e) {
+			throw new DataException("Unsupported Dogecoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+		}
+		if (dogecoinReceivingAddress.getOutputScriptType() != ScriptType.P2PKH)
+			throw new DataException("Unsupported Dogecoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+
+		byte[] dogecoinReceivingAccountInfo = dogecoinReceivingAddress.getHash();
+
+		PublicKeyAccount creator = new PublicKeyAccount(repository, tradeBotCreateRequest.creatorPublicKey);
+
+		// Deploy AT
+		long timestamp = NTP.getTime();
+		byte[] reference = creator.getLastReference();
+		long fee = 0L;
+		byte[] signature = null;
+		BaseTransactionData baseTransactionData = new BaseTransactionData(timestamp, Group.NO_GROUP, reference, creator.getPublicKey(), fee, signature);
+
+		String name = "QORT/DOGE ACCT";
+		String description = "QORT/DOGE cross-chain trade";
+		String aTType = "ACCT";
+		String tags = "ACCT QORT DOGE";
+		byte[] creationBytes = DogecoinACCTv3.buildQortalAT(tradeNativeAddress, tradeForeignPublicKeyHash, tradeBotCreateRequest.qortAmount,
+				tradeBotCreateRequest.foreignAmount, tradeBotCreateRequest.tradeTimeout);
+		long amount = tradeBotCreateRequest.fundingQortAmount;
+
+		DeployAtTransactionData deployAtTransactionData = new DeployAtTransactionData(baseTransactionData, name, description, aTType, tags, creationBytes, amount, Asset.QORT);
+
+		DeployAtTransaction deployAtTransaction = new DeployAtTransaction(repository, deployAtTransactionData);
+		fee = deployAtTransaction.calcRecommendedFee();
+		deployAtTransactionData.setFee(fee);
+
+		DeployAtTransaction.ensureATAddress(deployAtTransactionData);
+		String atAddress = deployAtTransactionData.getAtAddress();
+
+		TradeBotData tradeBotData =  new TradeBotData(tradePrivateKey, DogecoinACCTv3.NAME,
+				State.BOB_WAITING_FOR_AT_CONFIRM.name(), State.BOB_WAITING_FOR_AT_CONFIRM.value,
+				creator.getAddress(), atAddress, timestamp, tradeBotCreateRequest.qortAmount,
+				tradeNativePublicKey, tradeNativePublicKeyHash, tradeNativeAddress,
+				null, null,
+				SupportedBlockchain.DOGECOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				tradeBotCreateRequest.foreignAmount, null, null, null, dogecoinReceivingAccountInfo);
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Built AT %s. Waiting for deployment", atAddress));
+
+		// Attempt to backup the trade bot data
+		TradeBot.backupTradeBotData(repository, null);
+
+		// Return to user for signing and broadcast as we don't have their Qortal private key
+		try {
+			return DeployAtTransactionTransformer.toBytes(deployAtTransactionData);
+		} catch (TransformationException e) {
+			throw new DataException("Failed to transform DEPLOY_AT transaction?", e);
+		}
+	}
+
+	/**
+	 * Creates a trade-bot entry from the 'Alice' viewpoint, i.e. matching DOGE to an existing offer.
+	 * <p>
+	 * Requires a chosen trade offer from Bob, passed by <tt>crossChainTradeData</tt>
+	 * and access to a Dogecoin wallet via <tt>xprv58</tt>.
+	 * <p>
+	 * The <tt>crossChainTradeData</tt> contains the current trade offer state
+	 * as extracted from the AT's data segment.
+	 * <p>
+	 * Access to a funded wallet is via a Dogecoin BIP32 hierarchical deterministic key,
+	 * passed via <tt>xprv58</tt>.
+	 * <b>This key will be stored in your node's database</b>
+	 * to allow trade-bot to create/fund the necessary P2SH transactions!
+	 * However, due to the nature of BIP32 keys, it is possible to give the trade-bot
+	 * only a subset of wallet access (see BIP32 for more details).
+	 * <p>
+	 * As an example, the xprv58 can be extract from a <i>legacy, password-less</i>
+	 * Electrum wallet by going to the console tab and entering:<br>
+	 * <tt>wallet.keystore.xprv</tt><br>
+	 * which should result in a base58 string starting with either 'xprv' (for Dogecoin main-net)
+	 * or 'tprv' for (Dogecoin test-net).
+	 * <p>
+	 * It is envisaged that the value in <tt>xprv58</tt> will actually come from a Qortal-UI-managed wallet.
+	 * <p>
+	 * If sufficient funds are available, <b>this method will actually fund the P2SH-A</b>
+	 * with the Dogecoin amount expected by 'Bob'.
+	 * <p>
+	 * If the Dogecoin transaction is successfully broadcast to the network then
+	 * we also send a MESSAGE to Bob's trade-bot to let them know.
+	 * <p>
+	 * The trade-bot entry is saved to the repository and the cross-chain trading process commences.
+	 * <p>
+	 * @param repository
+	 * @param crossChainTradeData chosen trade OFFER that Alice wants to match
+	 * @param xprv58 funded wallet xprv in base58
+	 * @return true if P2SH-A funding transaction successfully broadcast to Dogecoin network, false otherwise
+	 * @throws DataException
+	 */
+	public ResponseResult startResponse(Repository repository, ATData atData, ACCT acct, CrossChainTradeData crossChainTradeData, String xprv58, String receivingAddress) throws DataException {
+		byte[] tradePrivateKey = TradeBot.generateTradePrivateKey();
+		byte[] secretA = TradeBot.generateSecret();
+		byte[] hashOfSecretA = Crypto.hash160(secretA);
+
+		byte[] tradeNativePublicKey = TradeBot.deriveTradeNativePublicKey(tradePrivateKey);
+		byte[] tradeNativePublicKeyHash = Crypto.hash160(tradeNativePublicKey);
+		String tradeNativeAddress = Crypto.toAddress(tradeNativePublicKey);
+
+		byte[] tradeForeignPublicKey = TradeBot.deriveTradeForeignPublicKey(tradePrivateKey);
+		byte[] tradeForeignPublicKeyHash = Crypto.hash160(tradeForeignPublicKey);
+		byte[] receivingPublicKeyHash = Base58.decode(receivingAddress); // Actually the whole address, not just PKH
+
+		// We need to generate lockTime-A: add tradeTimeout to now
+		long now = NTP.getTime();
+		int lockTimeA = crossChainTradeData.tradeTimeout * 60 + (int) (now / 1000L);
+
+		TradeBotData tradeBotData =  new TradeBotData(tradePrivateKey, DogecoinACCTv3.NAME,
+				State.ALICE_WAITING_FOR_AT_LOCK.name(), State.ALICE_WAITING_FOR_AT_LOCK.value,
+				receivingAddress, crossChainTradeData.qortalAtAddress, now, crossChainTradeData.qortAmount,
+				tradeNativePublicKey, tradeNativePublicKeyHash, tradeNativeAddress,
+				secretA, hashOfSecretA,
+				SupportedBlockchain.DOGECOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				crossChainTradeData.expectedForeignAmount, xprv58, null, lockTimeA, receivingPublicKeyHash);
+
+		// Attempt to backup the trade bot data
+		// Include tradeBotData as an additional parameter, since it's not in the repository yet
+		TradeBot.backupTradeBotData(repository, Arrays.asList(tradeBotData));
+
+		// Check we have enough funds via xprv58 to fund P2SH to cover expectedForeignAmount
+		long p2shFee;
+		try {
+			p2shFee = Dogecoin.getInstance().getP2shFee(now);
+		} catch (ForeignBlockchainException e) {
+			LOGGER.debug("Couldn't estimate Dogecoin fees?");
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		// Do not include fee for funding transaction as this is covered by buildSpend()
+		long amountA = crossChainTradeData.expectedForeignAmount + p2shFee /*redeeming/refunding P2SH-A*/;
+
+		// P2SH-A to be funded
+		byte[] redeemScriptBytes = BitcoinyHTLC.buildScript(tradeForeignPublicKeyHash, lockTimeA, crossChainTradeData.creatorForeignPKH, hashOfSecretA);
+		String p2shAddress = Dogecoin.getInstance().deriveP2shAddress(redeemScriptBytes);
+
+		// Build transaction for funding P2SH-A
+		Transaction p2shFundingTransaction = Dogecoin.getInstance().buildSpend(tradeBotData.getForeignKey(), p2shAddress, amountA);
+		if (p2shFundingTransaction == null) {
+			LOGGER.debug("Unable to build P2SH-A funding transaction - lack of funds?");
+			return ResponseResult.BALANCE_ISSUE;
+		}
+
+		try {
+			Dogecoin.getInstance().broadcastTransaction(p2shFundingTransaction);
+		} catch (ForeignBlockchainException e) {
+			// We couldn't fund P2SH-A at this time
+			LOGGER.debug("Couldn't broadcast P2SH-A funding transaction?");
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		// Attempt to send MESSAGE to Bob's Qortal trade address
+		byte[] messageData = DogecoinACCTv3.buildOfferMessage(tradeBotData.getTradeForeignPublicKeyHash(), tradeBotData.getHashOfSecret(), tradeBotData.getLockTimeA());
+		String messageRecipient = crossChainTradeData.qortalCreatorTradeAddress;
+
+		boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, messageData);
+		if (!isMessageAlreadySent) {
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK) {
+				LOGGER.warn(() -> String.format("Unable to send MESSAGE to Bob's trade-bot %s: %s", messageRecipient, result.name()));
+				return ResponseResult.NETWORK_ISSUE;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Funding P2SH-A %s. Messaged Bob. Waiting for AT-lock", p2shAddress));
+
+		return ResponseResult.OK;
+	}
+
+	@Override
+	public boolean canDelete(Repository repository, TradeBotData tradeBotData) throws DataException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null)
+			return true;
+
+		// If the AT doesn't exist then we might as well let the user tidy up
+		if (!repository.getATRepository().exists(tradeBotData.getAtAddress()))
+			return true;
+
+		switch (tradeBotState) {
+			case BOB_WAITING_FOR_AT_CONFIRM:
+			case ALICE_DONE:
+			case BOB_DONE:
+			case ALICE_REFUNDED:
+			case BOB_REFUNDED:
+			case ALICE_REFUNDING_A:
+				return true;
+
+			default:
+				return false;
+		}
+	}
+
+	@Override
+	public void progress(Repository repository, TradeBotData tradeBotData) throws DataException, ForeignBlockchainException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null) {
+			LOGGER.info(() -> String.format("Trade-bot entry for AT %s has invalid state?", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		ATData atData = null;
+		CrossChainTradeData tradeData = null;
+
+		if (tradeBotState.requiresAtData) {
+			// Attempt to fetch AT data
+			atData = repository.getATRepository().fromATAddress(tradeBotData.getAtAddress());
+			if (atData == null) {
+				LOGGER.debug(() -> String.format("Unable to fetch trade AT %s from repository", tradeBotData.getAtAddress()));
+				return;
+			}
+
+			if (tradeBotState.requiresTradeData) {
+				tradeData = DogecoinACCTv3.getInstance().populateTradeData(repository, atData);
+				if (tradeData == null) {
+					LOGGER.warn(() -> String.format("Unable to fetch ACCT trade data for AT %s from repository", tradeBotData.getAtAddress()));
+					return;
+				}
+			}
+		}
+
+		switch (tradeBotState) {
+			case BOB_WAITING_FOR_AT_CONFIRM:
+				handleBobWaitingForAtConfirm(repository, tradeBotData);
+				break;
+
+			case BOB_WAITING_FOR_MESSAGE:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleBobWaitingForMessage(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_WAITING_FOR_AT_LOCK:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleAliceWaitingForAtLock(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case BOB_WAITING_FOR_AT_REDEEM:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleBobWaitingForAtRedeem(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_DONE:
+			case BOB_DONE:
+				break;
+
+			case ALICE_REFUNDING_A:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleAliceRefundingP2shA(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_REFUNDED:
+			case BOB_REFUNDED:
+				break;
+		}
+	}
+
+	/**
+	 * Trade-bot is waiting for Bob's AT to deploy.
+	 * <p>
+	 * If AT is deployed, then trade-bot's next step is to wait for MESSAGE from Alice.
+	 */
+	private void handleBobWaitingForAtConfirm(Repository repository, TradeBotData tradeBotData) throws DataException {
+		if (!repository.getATRepository().exists(tradeBotData.getAtAddress())) {
+			if (NTP.getTime() - tradeBotData.getTimestamp() <= MAX_AT_CONFIRMATION_PERIOD)
+				return;
+
+			// We've waited ages for AT to be confirmed into a block but something has gone awry.
+			// After this long we assume transaction loss so give up with trade-bot entry too.
+			tradeBotData.setState(State.BOB_REFUNDED.name());
+			tradeBotData.setStateValue(State.BOB_REFUNDED.value);
+			tradeBotData.setTimestamp(NTP.getTime());
+			// We delete trade-bot entry here instead of saving, hence not using updateTradeBotState()
+			repository.getCrossChainRepository().delete(tradeBotData.getTradePrivateKey());
+			repository.saveChanges();
+
+			LOGGER.info(() -> String.format("AT %s never confirmed. Giving up on trade", tradeBotData.getAtAddress()));
+			TradeBot.notifyStateChange(tradeBotData);
+			return;
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_WAITING_FOR_MESSAGE,
+				() -> String.format("AT %s confirmed ready. Waiting for trade message", tradeBotData.getAtAddress()));
+	}
+
+	/**
+	 * Trade-bot is waiting for MESSAGE from Alice's trade-bot, containing Alice's trade info.
+	 * <p>
+	 * It's possible Bob has cancelling his trade offer, receiving an automatic QORT refund,
+	 * in which case trade-bot is done with this specific trade and finalizes on refunded state.
+	 * <p>
+	 * Assuming trade is still on offer, trade-bot checks the contents of MESSAGE from Alice's trade-bot.
+	 * <p>
+	 * Details from Alice are used to derive P2SH-A address and this is checked for funding balance.
+	 * <p>
+	 * Assuming P2SH-A has at least expected Dogecoin balance,
+	 * Bob's trade-bot constructs a zero-fee, PoW MESSAGE to send to Bob's AT with more trade details.
+	 * <p>
+	 * On processing this MESSAGE, Bob's AT should switch into 'TRADE' mode and only trade with Alice.
+	 * <p>
+	 * Trade-bot's next step is to wait for Alice to redeem the AT, which will allow Bob to
+	 * extract secret-A needed to redeem Alice's P2SH.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleBobWaitingForMessage(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// If AT has finished then Bob likely cancelled his trade offer
+		if (atData.getIsFinished()) {
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_REFUNDED,
+					() -> String.format("AT %s cancelled - trading aborted", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		Dogecoin dogecoin = Dogecoin.getInstance();
+
+		String address = tradeBotData.getTradeNativeAddress();
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(null, address, null, null, null);
+
+		for (MessageTransactionData messageTransactionData : messageTransactionsData) {
+			if (messageTransactionData.isText())
+				continue;
+
+			// We're expecting: HASH160(secret-A), Alice's Dogecoin pubkeyhash and lockTime-A
+			byte[] messageData = messageTransactionData.getData();
+			DogecoinACCTv3.OfferMessageData offerMessageData = DogecoinACCTv3.extractOfferMessageData(messageData);
+			if (offerMessageData == null)
+				continue;
+
+			byte[] aliceForeignPublicKeyHash = offerMessageData.partnerDogecoinPKH;
+			byte[] hashOfSecretA = offerMessageData.hashOfSecretA;
+			int lockTimeA = (int) offerMessageData.lockTimeA;
+			long messageTimestamp = messageTransactionData.getTimestamp();
+			int refundTimeout = DogecoinACCTv3.calcRefundTimeout(messageTimestamp, lockTimeA);
+
+			// Determine P2SH-A address and confirm funded
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(aliceForeignPublicKeyHash, lockTimeA, tradeBotData.getTradeForeignPublicKeyHash(), hashOfSecretA);
+			String p2shAddressA = dogecoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Dogecoin.getInstance().getP2shFee(feeTimestamp);
+			final long minimumAmountA = tradeBotData.getForeignAmount() + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(dogecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+			switch (htlcStatusA) {
+				case UNFUNDED:
+				case FUNDING_IN_PROGRESS:
+					// There might be another MESSAGE from someone else with an actually funded P2SH-A...
+					continue;
+
+				case REDEEM_IN_PROGRESS:
+				case REDEEMED:
+					// We've already redeemed this?
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_DONE,
+							() -> String.format("P2SH-A %s already spent? Assuming trade complete", p2shAddressA));
+					return;
+
+				case REFUND_IN_PROGRESS:
+				case REFUNDED:
+					// This P2SH-A is burnt, but there might be another MESSAGE from someone else with an actually funded P2SH-A...
+					continue;
+
+				case FUNDED:
+					// Fall-through out of switch...
+					break;
+			}
+
+			// Good to go - send MESSAGE to AT
+
+			String aliceNativeAddress = Crypto.toAddress(messageTransactionData.getCreatorPublicKey());
+
+			// Build outgoing message, padding each part to 32 bytes to make it easier for AT to consume
+			byte[] outgoingMessageData = DogecoinACCTv3.buildTradeMessage(aliceNativeAddress, aliceForeignPublicKeyHash, hashOfSecretA, lockTimeA, refundTimeout);
+			String messageRecipient = tradeBotData.getAtAddress();
+
+			boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, outgoingMessageData);
+			if (!isMessageAlreadySent) {
+				PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+				MessageTransaction outgoingMessageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, outgoingMessageData, false, false);
+
+				outgoingMessageTransaction.computeNonce();
+				outgoingMessageTransaction.sign(sender);
+
+				// reset repository state to prevent deadlock
+				repository.discardChanges();
+				ValidationResult result = outgoingMessageTransaction.importAsUnconfirmed();
+
+				if (result != ValidationResult.OK) {
+					LOGGER.warn(() -> String.format("Unable to send MESSAGE to AT %s: %s", messageRecipient, result.name()));
+					return;
+				}
+			}
+
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_WAITING_FOR_AT_REDEEM,
+					() -> String.format("Locked AT %s to %s. Waiting for AT redeem", tradeBotData.getAtAddress(), aliceNativeAddress));
+
+			return;
+		}
+	}
+
+	/**
+	 * Trade-bot is waiting for Bob's AT to switch to TRADE mode and lock trade to Alice only.
+	 * <p>
+	 * It's possible that Bob has cancelled his trade offer in the mean time, or that somehow
+	 * this process has taken so long that we've reached P2SH-A's locktime, or that someone else
+	 * has managed to trade with Bob. In any of these cases, trade-bot switches to begin the refunding process.
+	 * <p>
+	 * Assuming Bob's AT is locked to Alice, trade-bot checks AT's state data to make sure it is correct.
+	 * <p>
+	 * If all is well, trade-bot then redeems AT using Alice's secret-A, releasing Bob's QORT to Alice.
+	 * <p>
+	 * In revealing a valid secret-A, Bob can then redeem the DOGE funds from P2SH-A.
+	 * <p>
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleAliceWaitingForAtLock(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		if (aliceUnexpectedState(repository, tradeBotData, atData, crossChainTradeData))
+			return;
+
+		Dogecoin dogecoin = Dogecoin.getInstance();
+		int lockTimeA = tradeBotData.getLockTimeA();
+
+		// Refund P2SH-A if we've passed lockTime-A
+		if (NTP.getTime() >= lockTimeA * 1000L) {
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeA, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+			String p2shAddressA = dogecoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Dogecoin.getInstance().getP2shFee(feeTimestamp);
+			long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(dogecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+			switch (htlcStatusA) {
+				case UNFUNDED:
+				case FUNDING_IN_PROGRESS:
+				case FUNDED:
+					break;
+
+				case REDEEM_IN_PROGRESS:
+				case REDEEMED:
+					// Already redeemed?
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+							() -> String.format("P2SH-A %s already spent? Assuming trade completed", p2shAddressA));
+					return;
+
+				case REFUND_IN_PROGRESS:
+				case REFUNDED:
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDED,
+							() -> String.format("P2SH-A %s already refunded. Trade aborted", p2shAddressA));
+					return;
+
+			}
+
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+					() -> atData.getIsFinished()
+					? String.format("AT %s cancelled. Refunding P2SH-A %s - aborting trade", tradeBotData.getAtAddress(), p2shAddressA)
+					: String.format("LockTime-A reached, refunding P2SH-A %s - aborting trade", p2shAddressA));
+
+			return;
+		}
+
+		// We're waiting for AT to be in TRADE mode
+		if (crossChainTradeData.mode != AcctMode.TRADING)
+			return;
+
+		// AT is in TRADE mode and locked to us as checked by aliceUnexpectedState() above
+
+		// Find our MESSAGE to AT from previous state
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(tradeBotData.getTradeNativePublicKey(),
+				crossChainTradeData.qortalCreatorTradeAddress, null, null, null);
+		if (messageTransactionsData == null || messageTransactionsData.isEmpty()) {
+			LOGGER.warn(() -> String.format("Unable to find our message to trade creator %s?", crossChainTradeData.qortalCreatorTradeAddress));
+			return;
+		}
+
+		long recipientMessageTimestamp = messageTransactionsData.get(0).getTimestamp();
+		int refundTimeout = DogecoinACCTv3.calcRefundTimeout(recipientMessageTimestamp, lockTimeA);
+
+		// Our calculated refundTimeout should match AT's refundTimeout
+		if (refundTimeout != crossChainTradeData.refundTimeout) {
+			LOGGER.debug(() -> String.format("Trade AT refundTimeout '%d' doesn't match our refundTimeout '%d'", crossChainTradeData.refundTimeout, refundTimeout));
+			// We'll eventually refund
+			return;
+		}
+
+		// We're good to redeem AT
+
+		// Send 'redeem' MESSAGE to AT using both secret
+		byte[] secretA = tradeBotData.getSecret();
+		String qortalReceivingAddress = Base58.encode(tradeBotData.getReceivingAccountInfo()); // Actually contains whole address, not just PKH
+		byte[] messageData = DogecoinACCTv3.buildRedeemMessage(secretA, qortalReceivingAddress);
+		String messageRecipient = tradeBotData.getAtAddress();
+
+		boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, messageData);
+		if (!isMessageAlreadySent) {
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// Reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK) {
+				LOGGER.warn(() -> String.format("Unable to send MESSAGE to AT %s: %s", messageRecipient, result.name()));
+				return;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+				() -> String.format("Redeeming AT %s. Funds should arrive at %s",
+						tradeBotData.getAtAddress(), qortalReceivingAddress));
+	}
+
+	/**
+	 * Trade-bot is waiting for Alice to redeem Bob's AT, thus revealing secret-A which is required to spend the DOGE funds from P2SH-A.
+	 * <p>
+	 * It's possible that Bob's AT has reached its trading timeout and automatically refunded QORT back to Bob. In which case,
+	 * trade-bot is done with this specific trade and finalizes in refunded state.
+	 * <p>
+	 * Assuming trade-bot can extract a valid secret-A from Alice's MESSAGE then trade-bot uses that to redeem the DOGE funds from P2SH-A
+	 * to Bob's 'foreign'/Dogecoin trade legacy-format address, as derived from trade private key.
+	 * <p>
+	 * (This could potentially be 'improved' to send DOGE to any address of Bob's choosing by changing the transaction output).
+	 * <p>
+	 * If trade-bot successfully broadcasts the transaction, then this specific trade is done.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleBobWaitingForAtRedeem(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// AT should be 'finished' once Alice has redeemed QORT funds
+		if (!atData.getIsFinished())
+			// Not finished yet
+			return;
+
+		// If AT is REFUNDED or CANCELLED then something has gone wrong
+		if (crossChainTradeData.mode == AcctMode.REFUNDED || crossChainTradeData.mode == AcctMode.CANCELLED) {
+			// Alice hasn't redeemed the QORT, so there is no point in trying to redeem the DOGE
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_REFUNDED,
+					() -> String.format("AT %s has auto-refunded - trade aborted", tradeBotData.getAtAddress()));
+
+			return;
+		}
+
+		byte[] secretA = DogecoinACCTv3.getInstance().findSecretA(repository, crossChainTradeData);
+		if (secretA == null) {
+			LOGGER.debug(() -> String.format("Unable to find secret-A from redeem message to AT %s?", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		// Use secret-A to redeem P2SH-A
+
+		Dogecoin dogecoin = Dogecoin.getInstance();
+
+		byte[] receivingAccountInfo = tradeBotData.getReceivingAccountInfo();
+		int lockTimeA = crossChainTradeData.lockTimeA;
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(crossChainTradeData.partnerForeignPKH, lockTimeA, crossChainTradeData.creatorForeignPKH, crossChainTradeData.hashOfSecretA);
+		String p2shAddressA = dogecoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Dogecoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(dogecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+		switch (htlcStatusA) {
+			case UNFUNDED:
+			case FUNDING_IN_PROGRESS:
+				// P2SH-A suddenly not funded? Our best bet at this point is to hope for AT auto-refund
+				return;
+
+			case REDEEM_IN_PROGRESS:
+			case REDEEMED:
+				// Double-check that we have redeemed P2SH-A...
+				break;
+
+			case REFUND_IN_PROGRESS:
+			case REFUNDED:
+				// Wait for AT to auto-refund
+				return;
+
+			case FUNDED: {
+				Coin redeemAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
+				ECKey redeemKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
+				List<TransactionOutput> fundingOutputs = dogecoin.getUnspentOutputs(p2shAddressA);
+
+				Transaction p2shRedeemTransaction = BitcoinyHTLC.buildRedeemTransaction(dogecoin.getNetworkParameters(), redeemAmount, redeemKey,
+						fundingOutputs, redeemScriptA, secretA, receivingAccountInfo);
+
+				dogecoin.broadcastTransaction(p2shRedeemTransaction);
+				break;
+			}
+		}
+
+		String receivingAddress = dogecoin.pkhToAddress(receivingAccountInfo);
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_DONE,
+				() -> String.format("P2SH-A %s redeemed. Funds should arrive at %s", tradeBotData.getAtAddress(), receivingAddress));
+	}
+
+	/**
+	 * Trade-bot is attempting to refund P2SH-A.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleAliceRefundingP2shA(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		int lockTimeA = tradeBotData.getLockTimeA();
+
+		// We can't refund P2SH-A until lockTime-A has passed
+		if (NTP.getTime() <= lockTimeA * 1000L)
+			return;
+
+		Dogecoin dogecoin = Dogecoin.getInstance();
+
+		// We can't refund P2SH-A until median block time has passed lockTime-A (see BIP113)
+		int medianBlockTime = dogecoin.getMedianBlockTime();
+		if (medianBlockTime <= lockTimeA)
+			return;
+
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeA, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+		String p2shAddressA = dogecoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Dogecoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(dogecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+		switch (htlcStatusA) {
+			case UNFUNDED:
+			case FUNDING_IN_PROGRESS:
+				// Still waiting for P2SH-A to be funded...
+				return;
+
+			case REDEEM_IN_PROGRESS:
+			case REDEEMED:
+				// Too late!
+				TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+						() -> String.format("P2SH-A %s already spent!", p2shAddressA));
+				return;
+
+			case REFUND_IN_PROGRESS:
+			case REFUNDED:
+				break;
+
+			case FUNDED:{
+				Coin refundAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
+				ECKey refundKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
+				List<TransactionOutput> fundingOutputs = dogecoin.getUnspentOutputs(p2shAddressA);
+
+				// Determine receive address for refund
+				String receiveAddress = dogecoin.getUnusedReceiveAddress(tradeBotData.getForeignKey());
+				Address receiving = Address.fromString(dogecoin.getNetworkParameters(), receiveAddress);
+
+				Transaction p2shRefundTransaction = BitcoinyHTLC.buildRefundTransaction(dogecoin.getNetworkParameters(), refundAmount, refundKey,
+						fundingOutputs, redeemScriptA, lockTimeA, receiving.getHash());
+
+				dogecoin.broadcastTransaction(p2shRefundTransaction);
+				break;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDED,
+				() -> String.format("LockTime-A reached. Refunded P2SH-A %s. Trade aborted", p2shAddressA));
+	}
+
+	/**
+	 * Returns true if Alice finds AT unexpectedly cancelled, refunded, redeemed or locked to someone else.
+	 * <p>
+	 * Will automatically update trade-bot state to <tt>ALICE_REFUNDING_A</tt> or <tt>ALICE_DONE</tt> as necessary.
+	 * 
+	 * @throws DataException
+	 * @throws ForeignBlockchainException
+	 */
+	private boolean aliceUnexpectedState(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// This is OK
+		if (!atData.getIsFinished() && crossChainTradeData.mode == AcctMode.OFFERING)
+			return false;
+
+		boolean isAtLockedToUs = tradeBotData.getTradeNativeAddress().equals(crossChainTradeData.qortalPartnerAddress);
+
+		if (!atData.getIsFinished() && crossChainTradeData.mode == AcctMode.TRADING)
+			if (isAtLockedToUs) {
+				// AT is trading with us - OK
+				return false;
+			} else {
+				TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+						() -> String.format("AT %s trading with someone else: %s. Refunding & aborting trade", tradeBotData.getAtAddress(), crossChainTradeData.qortalPartnerAddress));
+
+				return true;
+			}
+
+		if (atData.getIsFinished() && crossChainTradeData.mode == AcctMode.REDEEMED && isAtLockedToUs) {
+			// We've redeemed already?
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+					() -> String.format("AT %s already redeemed by us. Trade completed", tradeBotData.getAtAddress()));
+		} else {
+			// Any other state is not good, so start defensive refund
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+					() -> String.format("AT %s cancelled/refunded/redeemed by someone else/invalid state. Refunding & aborting trade", tradeBotData.getAtAddress()));
+		}
+
+		return true;
+	}
+
+	private long calcFeeTimestamp(int lockTimeA, int tradeTimeout) {
+		return (lockTimeA - tradeTimeout * 60) * 1000L;
+	}
+
+}

src/main/java/org/qortal/controller/tradebot/LitecoinACCTv1TradeBot.java

@@ -0,0 +1,896 @@
+package org.qortal.controller.tradebot;
+
+import static java.util.Arrays.stream;
+import static java.util.stream.Collectors.toMap;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.bitcoinj.core.Address;
+import org.bitcoinj.core.AddressFormatException;
+import org.bitcoinj.core.Coin;
+import org.bitcoinj.core.ECKey;
+import org.bitcoinj.core.Transaction;
+import org.bitcoinj.core.TransactionOutput;
+import org.bitcoinj.script.Script.ScriptType;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.account.PublicKeyAccount;
+import org.qortal.api.model.crosschain.TradeBotCreateRequest;
+import org.qortal.asset.Asset;
+import org.qortal.crosschain.ACCT;
+import org.qortal.crosschain.AcctMode;
+import org.qortal.crosschain.ForeignBlockchainException;
+import org.qortal.crosschain.Litecoin;
+import org.qortal.crosschain.LitecoinACCTv1;
+import org.qortal.crosschain.SupportedBlockchain;
+import org.qortal.crosschain.BitcoinyHTLC;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.data.transaction.BaseTransactionData;
+import org.qortal.data.transaction.DeployAtTransactionData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.transaction.DeployAtTransaction;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.transaction.DeployAtTransactionTransformer;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+/**
+ * Performing cross-chain trading steps on behalf of user.
+ * <p>
+ * We deal with three different independent state-spaces here:
+ * <ul>
+ * 	<li>Qortal blockchain</li>
+ * 	<li>Foreign blockchain</li>
+ * 	<li>Trade-bot entries</li>
+ * </ul>
+ */
+public class LitecoinACCTv1TradeBot implements AcctTradeBot {
+
+	private static final Logger LOGGER = LogManager.getLogger(LitecoinACCTv1TradeBot.class);
+
+	public enum State implements TradeBot.StateNameAndValueSupplier {
+		BOB_WAITING_FOR_AT_CONFIRM(10, false, false),
+		BOB_WAITING_FOR_MESSAGE(15, true, true),
+		BOB_WAITING_FOR_AT_REDEEM(25, true, true),
+		BOB_DONE(30, false, false),
+		BOB_REFUNDED(35, false, false),
+
+		ALICE_WAITING_FOR_AT_LOCK(85, true, true),
+		ALICE_DONE(95, false, false),
+		ALICE_REFUNDING_A(105, true, true),
+		ALICE_REFUNDED(110, false, false);
+
+		private static final Map<Integer, State> map = stream(State.values()).collect(toMap(state -> state.value, state -> state));
+
+		public final int value;
+		public final boolean requiresAtData;
+		public final boolean requiresTradeData;
+
+		State(int value, boolean requiresAtData, boolean requiresTradeData) {
+			this.value = value;
+			this.requiresAtData = requiresAtData;
+			this.requiresTradeData = requiresTradeData;
+		}
+
+		public static State valueOf(int value) {
+			return map.get(value);
+		}
+
+		@Override
+		public String getState() {
+			return this.name();
+		}
+
+		@Override
+		public int getStateValue() {
+			return this.value;
+		}
+	}
+
+	/** Maximum time Bob waits for his AT creation transaction to be confirmed into a block. (milliseconds) */
+	private static final long MAX_AT_CONFIRMATION_PERIOD = 24 * 60 * 60 * 1000L; // ms
+
+	private static LitecoinACCTv1TradeBot instance;
+
+	private final List<String> endStates = Arrays.asList(State.BOB_DONE, State.BOB_REFUNDED, State.ALICE_DONE, State.ALICE_REFUNDING_A, State.ALICE_REFUNDED).stream()
+			.map(State::name)
+			.collect(Collectors.toUnmodifiableList());
+
+	private LitecoinACCTv1TradeBot() {
+	}
+
+	public static synchronized LitecoinACCTv1TradeBot getInstance() {
+		if (instance == null)
+			instance = new LitecoinACCTv1TradeBot();
+
+		return instance;
+	}
+
+	@Override
+	public List<String> getEndStates() {
+		return this.endStates;
+	}
+
+	/**
+	 * Creates a new trade-bot entry from the "Bob" viewpoint, i.e. OFFERing QORT in exchange for LTC.
+	 * <p>
+	 * Generates:
+	 * <ul>
+	 * 	<li>new 'trade' private key</li>
+	 * </ul>
+	 * Derives:
+	 * <ul>
+	 * 	<li>'native' (as in Qortal) public key, public key hash, address (starting with Q)</li>
+	 * 	<li>'foreign' (as in Litecoin) public key, public key hash</li>
+	 * </ul>
+	 * A Qortal AT is then constructed including the following as constants in the 'data segment':
+	 * <ul>
+	 * 	<li>'native'/Qortal 'trade' address - used as a MESSAGE contact</li>
+	 * 	<li>'foreign'/Litecoin public key hash - used by Alice's P2SH scripts to allow redeem</li>
+	 * 	<li>QORT amount on offer by Bob</li>
+	 * 	<li>LTC amount expected in return by Bob (from Alice)</li>
+	 * 	<li>trading timeout, in case things go wrong and everyone needs to refund</li>
+	 * </ul>
+	 * Returns a DEPLOY_AT transaction that needs to be signed and broadcast to the Qortal network.
+	 * <p>
+	 * Trade-bot will wait for Bob's AT to be deployed before taking next step.
+	 * <p>
+	 * @param repository
+	 * @param tradeBotCreateRequest
+	 * @return raw, unsigned DEPLOY_AT transaction
+	 * @throws DataException
+	 */
+	public byte[] createTrade(Repository repository, TradeBotCreateRequest tradeBotCreateRequest) throws DataException {
+		byte[] tradePrivateKey = TradeBot.generateTradePrivateKey();
+
+		byte[] tradeNativePublicKey = TradeBot.deriveTradeNativePublicKey(tradePrivateKey);
+		byte[] tradeNativePublicKeyHash = Crypto.hash160(tradeNativePublicKey);
+		String tradeNativeAddress = Crypto.toAddress(tradeNativePublicKey);
+
+		byte[] tradeForeignPublicKey = TradeBot.deriveTradeForeignPublicKey(tradePrivateKey);
+		byte[] tradeForeignPublicKeyHash = Crypto.hash160(tradeForeignPublicKey);
+
+		// Convert Litecoin receiving address into public key hash (we only support P2PKH at this time)
+		Address litecoinReceivingAddress;
+		try {
+			litecoinReceivingAddress = Address.fromString(Litecoin.getInstance().getNetworkParameters(), tradeBotCreateRequest.receivingAddress);
+		} catch (AddressFormatException e) {
+			throw new DataException("Unsupported Litecoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+		}
+		if (litecoinReceivingAddress.getOutputScriptType() != ScriptType.P2PKH)
+			throw new DataException("Unsupported Litecoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+
+		byte[] litecoinReceivingAccountInfo = litecoinReceivingAddress.getHash();
+
+		PublicKeyAccount creator = new PublicKeyAccount(repository, tradeBotCreateRequest.creatorPublicKey);
+
+		// Deploy AT
+		long timestamp = NTP.getTime();
+		byte[] reference = creator.getLastReference();
+		long fee = 0L;
+		byte[] signature = null;
+		BaseTransactionData baseTransactionData = new BaseTransactionData(timestamp, Group.NO_GROUP, reference, creator.getPublicKey(), fee, signature);
+
+		String name = "QORT/LTC ACCT";
+		String description = "QORT/LTC cross-chain trade";
+		String aTType = "ACCT";
+		String tags = "ACCT QORT LTC";
+		byte[] creationBytes = LitecoinACCTv1.buildQortalAT(tradeNativeAddress, tradeForeignPublicKeyHash, tradeBotCreateRequest.qortAmount,
+				tradeBotCreateRequest.foreignAmount, tradeBotCreateRequest.tradeTimeout);
+		long amount = tradeBotCreateRequest.fundingQortAmount;
+
+		DeployAtTransactionData deployAtTransactionData = new DeployAtTransactionData(baseTransactionData, name, description, aTType, tags, creationBytes, amount, Asset.QORT);
+
+		DeployAtTransaction deployAtTransaction = new DeployAtTransaction(repository, deployAtTransactionData);
+		fee = deployAtTransaction.calcRecommendedFee();
+		deployAtTransactionData.setFee(fee);
+
+		DeployAtTransaction.ensureATAddress(deployAtTransactionData);
+		String atAddress = deployAtTransactionData.getAtAddress();
+
+		TradeBotData tradeBotData =  new TradeBotData(tradePrivateKey, LitecoinACCTv1.NAME,
+				State.BOB_WAITING_FOR_AT_CONFIRM.name(), State.BOB_WAITING_FOR_AT_CONFIRM.value,
+				creator.getAddress(), atAddress, timestamp, tradeBotCreateRequest.qortAmount,
+				tradeNativePublicKey, tradeNativePublicKeyHash, tradeNativeAddress,
+				null, null,
+				SupportedBlockchain.LITECOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				tradeBotCreateRequest.foreignAmount, null, null, null, litecoinReceivingAccountInfo);
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Built AT %s. Waiting for deployment", atAddress));
+
+		// Attempt to backup the trade bot data
+		TradeBot.backupTradeBotData(repository, null);
+
+		// Return to user for signing and broadcast as we don't have their Qortal private key
+		try {
+			return DeployAtTransactionTransformer.toBytes(deployAtTransactionData);
+		} catch (TransformationException e) {
+			throw new DataException("Failed to transform DEPLOY_AT transaction?", e);
+		}
+	}
+
+	/**
+	 * Creates a trade-bot entry from the 'Alice' viewpoint, i.e. matching LTC to an existing offer.
+	 * <p>
+	 * Requires a chosen trade offer from Bob, passed by <tt>crossChainTradeData</tt>
+	 * and access to a Litecoin wallet via <tt>xprv58</tt>.
+	 * <p>
+	 * The <tt>crossChainTradeData</tt> contains the current trade offer state
+	 * as extracted from the AT's data segment.
+	 * <p>
+	 * Access to a funded wallet is via a Litecoin BIP32 hierarchical deterministic key,
+	 * passed via <tt>xprv58</tt>.
+	 * <b>This key will be stored in your node's database</b>
+	 * to allow trade-bot to create/fund the necessary P2SH transactions!
+	 * However, due to the nature of BIP32 keys, it is possible to give the trade-bot
+	 * only a subset of wallet access (see BIP32 for more details).
+	 * <p>
+	 * As an example, the xprv58 can be extract from a <i>legacy, password-less</i>
+	 * Electrum wallet by going to the console tab and entering:<br>
+	 * <tt>wallet.keystore.xprv</tt><br>
+	 * which should result in a base58 string starting with either 'xprv' (for Litecoin main-net)
+	 * or 'tprv' for (Litecoin test-net).
+	 * <p>
+	 * It is envisaged that the value in <tt>xprv58</tt> will actually come from a Qortal-UI-managed wallet.
+	 * <p>
+	 * If sufficient funds are available, <b>this method will actually fund the P2SH-A</b>
+	 * with the Litecoin amount expected by 'Bob'.
+	 * <p>
+	 * If the Litecoin transaction is successfully broadcast to the network then
+	 * we also send a MESSAGE to Bob's trade-bot to let them know.
+	 * <p>
+	 * The trade-bot entry is saved to the repository and the cross-chain trading process commences.
+	 * <p>
+	 * @param repository
+	 * @param crossChainTradeData chosen trade OFFER that Alice wants to match
+	 * @param xprv58 funded wallet xprv in base58
+	 * @return true if P2SH-A funding transaction successfully broadcast to Litecoin network, false otherwise
+	 * @throws DataException
+	 */
+	public ResponseResult startResponse(Repository repository, ATData atData, ACCT acct, CrossChainTradeData crossChainTradeData, String xprv58, String receivingAddress) throws DataException {
+		byte[] tradePrivateKey = TradeBot.generateTradePrivateKey();
+		byte[] secretA = TradeBot.generateSecret();
+		byte[] hashOfSecretA = Crypto.hash160(secretA);
+
+		byte[] tradeNativePublicKey = TradeBot.deriveTradeNativePublicKey(tradePrivateKey);
+		byte[] tradeNativePublicKeyHash = Crypto.hash160(tradeNativePublicKey);
+		String tradeNativeAddress = Crypto.toAddress(tradeNativePublicKey);
+
+		byte[] tradeForeignPublicKey = TradeBot.deriveTradeForeignPublicKey(tradePrivateKey);
+		byte[] tradeForeignPublicKeyHash = Crypto.hash160(tradeForeignPublicKey);
+		byte[] receivingPublicKeyHash = Base58.decode(receivingAddress); // Actually the whole address, not just PKH
+
+		// We need to generate lockTime-A: add tradeTimeout to now
+		long now = NTP.getTime();
+		int lockTimeA = crossChainTradeData.tradeTimeout * 60 + (int) (now / 1000L);
+
+		TradeBotData tradeBotData =  new TradeBotData(tradePrivateKey, LitecoinACCTv1.NAME,
+				State.ALICE_WAITING_FOR_AT_LOCK.name(), State.ALICE_WAITING_FOR_AT_LOCK.value,
+				receivingAddress, crossChainTradeData.qortalAtAddress, now, crossChainTradeData.qortAmount,
+				tradeNativePublicKey, tradeNativePublicKeyHash, tradeNativeAddress,
+				secretA, hashOfSecretA,
+				SupportedBlockchain.LITECOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				crossChainTradeData.expectedForeignAmount, xprv58, null, lockTimeA, receivingPublicKeyHash);
+
+		// Attempt to backup the trade bot data
+		// Include tradeBotData as an additional parameter, since it's not in the repository yet
+		TradeBot.backupTradeBotData(repository, Arrays.asList(tradeBotData));
+
+		// Check we have enough funds via xprv58 to fund P2SH to cover expectedForeignAmount
+		long p2shFee;
+		try {
+			p2shFee = Litecoin.getInstance().getP2shFee(now);
+		} catch (ForeignBlockchainException e) {
+			LOGGER.debug("Couldn't estimate Litecoin fees?");
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		// Do not include fee for funding transaction as this is covered by buildSpend()
+		long amountA = crossChainTradeData.expectedForeignAmount + p2shFee /*redeeming/refunding P2SH-A*/;
+
+		// P2SH-A to be funded
+		byte[] redeemScriptBytes = BitcoinyHTLC.buildScript(tradeForeignPublicKeyHash, lockTimeA, crossChainTradeData.creatorForeignPKH, hashOfSecretA);
+		String p2shAddress = Litecoin.getInstance().deriveP2shAddress(redeemScriptBytes);
+
+		// Build transaction for funding P2SH-A
+		Transaction p2shFundingTransaction = Litecoin.getInstance().buildSpend(tradeBotData.getForeignKey(), p2shAddress, amountA);
+		if (p2shFundingTransaction == null) {
+			LOGGER.debug("Unable to build P2SH-A funding transaction - lack of funds?");
+			return ResponseResult.BALANCE_ISSUE;
+		}
+
+		try {
+			Litecoin.getInstance().broadcastTransaction(p2shFundingTransaction);
+		} catch (ForeignBlockchainException e) {
+			// We couldn't fund P2SH-A at this time
+			LOGGER.debug("Couldn't broadcast P2SH-A funding transaction?");
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		// Attempt to send MESSAGE to Bob's Qortal trade address
+		byte[] messageData = LitecoinACCTv1.buildOfferMessage(tradeBotData.getTradeForeignPublicKeyHash(), tradeBotData.getHashOfSecret(), tradeBotData.getLockTimeA());
+		String messageRecipient = crossChainTradeData.qortalCreatorTradeAddress;
+
+		boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, messageData);
+		if (!isMessageAlreadySent) {
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK) {
+				LOGGER.warn(() -> String.format("Unable to send MESSAGE to Bob's trade-bot %s: %s", messageRecipient, result.name()));
+				return ResponseResult.NETWORK_ISSUE;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Funding P2SH-A %s. Messaged Bob. Waiting for AT-lock", p2shAddress));
+
+		return ResponseResult.OK;
+	}
+
+	@Override
+	public boolean canDelete(Repository repository, TradeBotData tradeBotData) throws DataException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null)
+			return true;
+
+		// If the AT doesn't exist then we might as well let the user tidy up
+		if (!repository.getATRepository().exists(tradeBotData.getAtAddress()))
+			return true;
+
+		switch (tradeBotState) {
+			case BOB_WAITING_FOR_AT_CONFIRM:
+			case ALICE_DONE:
+			case BOB_DONE:
+			case ALICE_REFUNDED:
+			case BOB_REFUNDED:
+			case ALICE_REFUNDING_A:
+				return true;
+
+			default:
+				return false;
+		}
+	}
+
+	@Override
+	public void progress(Repository repository, TradeBotData tradeBotData) throws DataException, ForeignBlockchainException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null) {
+			LOGGER.info(() -> String.format("Trade-bot entry for AT %s has invalid state?", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		ATData atData = null;
+		CrossChainTradeData tradeData = null;
+
+		if (tradeBotState.requiresAtData) {
+			// Attempt to fetch AT data
+			atData = repository.getATRepository().fromATAddress(tradeBotData.getAtAddress());
+			if (atData == null) {
+				LOGGER.debug(() -> String.format("Unable to fetch trade AT %s from repository", tradeBotData.getAtAddress()));
+				return;
+			}
+
+			if (tradeBotState.requiresTradeData) {
+				tradeData = LitecoinACCTv1.getInstance().populateTradeData(repository, atData);
+				if (tradeData == null) {
+					LOGGER.warn(() -> String.format("Unable to fetch ACCT trade data for AT %s from repository", tradeBotData.getAtAddress()));
+					return;
+				}
+			}
+		}
+
+		switch (tradeBotState) {
+			case BOB_WAITING_FOR_AT_CONFIRM:
+				handleBobWaitingForAtConfirm(repository, tradeBotData);
+				break;
+
+			case BOB_WAITING_FOR_MESSAGE:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleBobWaitingForMessage(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_WAITING_FOR_AT_LOCK:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleAliceWaitingForAtLock(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case BOB_WAITING_FOR_AT_REDEEM:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleBobWaitingForAtRedeem(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_DONE:
+			case BOB_DONE:
+				break;
+
+			case ALICE_REFUNDING_A:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleAliceRefundingP2shA(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_REFUNDED:
+			case BOB_REFUNDED:
+				break;
+		}
+	}
+
+	/**
+	 * Trade-bot is waiting for Bob's AT to deploy.
+	 * <p>
+	 * If AT is deployed, then trade-bot's next step is to wait for MESSAGE from Alice.
+	 */
+	private void handleBobWaitingForAtConfirm(Repository repository, TradeBotData tradeBotData) throws DataException {
+		if (!repository.getATRepository().exists(tradeBotData.getAtAddress())) {
+			if (NTP.getTime() - tradeBotData.getTimestamp() <= MAX_AT_CONFIRMATION_PERIOD)
+				return;
+
+			// We've waited ages for AT to be confirmed into a block but something has gone awry.
+			// After this long we assume transaction loss so give up with trade-bot entry too.
+			tradeBotData.setState(State.BOB_REFUNDED.name());
+			tradeBotData.setStateValue(State.BOB_REFUNDED.value);
+			tradeBotData.setTimestamp(NTP.getTime());
+			// We delete trade-bot entry here instead of saving, hence not using updateTradeBotState()
+			repository.getCrossChainRepository().delete(tradeBotData.getTradePrivateKey());
+			repository.saveChanges();
+
+			LOGGER.info(() -> String.format("AT %s never confirmed. Giving up on trade", tradeBotData.getAtAddress()));
+			TradeBot.notifyStateChange(tradeBotData);
+			return;
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_WAITING_FOR_MESSAGE,
+				() -> String.format("AT %s confirmed ready. Waiting for trade message", tradeBotData.getAtAddress()));
+	}
+
+	/**
+	 * Trade-bot is waiting for MESSAGE from Alice's trade-bot, containing Alice's trade info.
+	 * <p>
+	 * It's possible Bob has cancelling his trade offer, receiving an automatic QORT refund,
+	 * in which case trade-bot is done with this specific trade and finalizes on refunded state.
+	 * <p>
+	 * Assuming trade is still on offer, trade-bot checks the contents of MESSAGE from Alice's trade-bot.
+	 * <p>
+	 * Details from Alice are used to derive P2SH-A address and this is checked for funding balance.
+	 * <p>
+	 * Assuming P2SH-A has at least expected Litecoin balance,
+	 * Bob's trade-bot constructs a zero-fee, PoW MESSAGE to send to Bob's AT with more trade details.
+	 * <p>
+	 * On processing this MESSAGE, Bob's AT should switch into 'TRADE' mode and only trade with Alice.
+	 * <p>
+	 * Trade-bot's next step is to wait for Alice to redeem the AT, which will allow Bob to
+	 * extract secret-A needed to redeem Alice's P2SH.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleBobWaitingForMessage(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// If AT has finished then Bob likely cancelled his trade offer
+		if (atData.getIsFinished()) {
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_REFUNDED,
+					() -> String.format("AT %s cancelled - trading aborted", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		String address = tradeBotData.getTradeNativeAddress();
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(null, address, null, null, null);
+
+		for (MessageTransactionData messageTransactionData : messageTransactionsData) {
+			if (messageTransactionData.isText())
+				continue;
+
+			// We're expecting: HASH160(secret-A), Alice's Litecoin pubkeyhash and lockTime-A
+			byte[] messageData = messageTransactionData.getData();
+			LitecoinACCTv1.OfferMessageData offerMessageData = LitecoinACCTv1.extractOfferMessageData(messageData);
+			if (offerMessageData == null)
+				continue;
+
+			byte[] aliceForeignPublicKeyHash = offerMessageData.partnerLitecoinPKH;
+			byte[] hashOfSecretA = offerMessageData.hashOfSecretA;
+			int lockTimeA = (int) offerMessageData.lockTimeA;
+			long messageTimestamp = messageTransactionData.getTimestamp();
+			int refundTimeout = LitecoinACCTv1.calcRefundTimeout(messageTimestamp, lockTimeA);
+
+			// Determine P2SH-A address and confirm funded
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(aliceForeignPublicKeyHash, lockTimeA, tradeBotData.getTradeForeignPublicKeyHash(), hashOfSecretA);
+			String p2shAddressA = litecoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Litecoin.getInstance().getP2shFee(feeTimestamp);
+			final long minimumAmountA = tradeBotData.getForeignAmount() + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(litecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+			switch (htlcStatusA) {
+				case UNFUNDED:
+				case FUNDING_IN_PROGRESS:
+					// There might be another MESSAGE from someone else with an actually funded P2SH-A...
+					continue;
+
+				case REDEEM_IN_PROGRESS:
+				case REDEEMED:
+					// We've already redeemed this?
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_DONE,
+							() -> String.format("P2SH-A %s already spent? Assuming trade complete", p2shAddressA));
+					return;
+
+				case REFUND_IN_PROGRESS:
+				case REFUNDED:
+					// This P2SH-A is burnt, but there might be another MESSAGE from someone else with an actually funded P2SH-A...
+					continue;
+
+				case FUNDED:
+					// Fall-through out of switch...
+					break;
+			}
+
+			// Good to go - send MESSAGE to AT
+
+			String aliceNativeAddress = Crypto.toAddress(messageTransactionData.getCreatorPublicKey());
+
+			// Build outgoing message, padding each part to 32 bytes to make it easier for AT to consume
+			byte[] outgoingMessageData = LitecoinACCTv1.buildTradeMessage(aliceNativeAddress, aliceForeignPublicKeyHash, hashOfSecretA, lockTimeA, refundTimeout);
+			String messageRecipient = tradeBotData.getAtAddress();
+
+			boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, outgoingMessageData);
+			if (!isMessageAlreadySent) {
+				PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+				MessageTransaction outgoingMessageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, outgoingMessageData, false, false);
+
+				outgoingMessageTransaction.computeNonce();
+				outgoingMessageTransaction.sign(sender);
+
+				// reset repository state to prevent deadlock
+				repository.discardChanges();
+				ValidationResult result = outgoingMessageTransaction.importAsUnconfirmed();
+
+				if (result != ValidationResult.OK) {
+					LOGGER.warn(() -> String.format("Unable to send MESSAGE to AT %s: %s", messageRecipient, result.name()));
+					return;
+				}
+			}
+
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_WAITING_FOR_AT_REDEEM,
+					() -> String.format("Locked AT %s to %s. Waiting for AT redeem", tradeBotData.getAtAddress(), aliceNativeAddress));
+
+			return;
+		}
+	}
+
+	/**
+	 * Trade-bot is waiting for Bob's AT to switch to TRADE mode and lock trade to Alice only.
+	 * <p>
+	 * It's possible that Bob has cancelled his trade offer in the mean time, or that somehow
+	 * this process has taken so long that we've reached P2SH-A's locktime, or that someone else
+	 * has managed to trade with Bob. In any of these cases, trade-bot switches to begin the refunding process.
+	 * <p>
+	 * Assuming Bob's AT is locked to Alice, trade-bot checks AT's state data to make sure it is correct.
+	 * <p>
+	 * If all is well, trade-bot then redeems AT using Alice's secret-A, releasing Bob's QORT to Alice.
+	 * <p>
+	 * In revealing a valid secret-A, Bob can then redeem the LTC funds from P2SH-A.
+	 * <p>
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleAliceWaitingForAtLock(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		if (aliceUnexpectedState(repository, tradeBotData, atData, crossChainTradeData))
+			return;
+
+		Litecoin litecoin = Litecoin.getInstance();
+		int lockTimeA = tradeBotData.getLockTimeA();
+
+		// Refund P2SH-A if we've passed lockTime-A
+		if (NTP.getTime() >= lockTimeA * 1000L) {
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeA, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+			String p2shAddressA = litecoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Litecoin.getInstance().getP2shFee(feeTimestamp);
+			long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(litecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+			switch (htlcStatusA) {
+				case UNFUNDED:
+				case FUNDING_IN_PROGRESS:
+				case FUNDED:
+					break;
+
+				case REDEEM_IN_PROGRESS:
+				case REDEEMED:
+					// Already redeemed?
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+							() -> String.format("P2SH-A %s already spent? Assuming trade completed", p2shAddressA));
+					return;
+
+				case REFUND_IN_PROGRESS:
+				case REFUNDED:
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDED,
+							() -> String.format("P2SH-A %s already refunded. Trade aborted", p2shAddressA));
+					return;
+
+			}
+
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+					() -> atData.getIsFinished()
+					? String.format("AT %s cancelled. Refunding P2SH-A %s - aborting trade", tradeBotData.getAtAddress(), p2shAddressA)
+					: String.format("LockTime-A reached, refunding P2SH-A %s - aborting trade", p2shAddressA));
+
+			return;
+		}
+
+		// We're waiting for AT to be in TRADE mode
+		if (crossChainTradeData.mode != AcctMode.TRADING)
+			return;
+
+		// AT is in TRADE mode and locked to us as checked by aliceUnexpectedState() above
+
+		// Find our MESSAGE to AT from previous state
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(tradeBotData.getTradeNativePublicKey(),
+				crossChainTradeData.qortalCreatorTradeAddress, null, null, null);
+		if (messageTransactionsData == null || messageTransactionsData.isEmpty()) {
+			LOGGER.warn(() -> String.format("Unable to find our message to trade creator %s?", crossChainTradeData.qortalCreatorTradeAddress));
+			return;
+		}
+
+		long recipientMessageTimestamp = messageTransactionsData.get(0).getTimestamp();
+		int refundTimeout = LitecoinACCTv1.calcRefundTimeout(recipientMessageTimestamp, lockTimeA);
+
+		// Our calculated refundTimeout should match AT's refundTimeout
+		if (refundTimeout != crossChainTradeData.refundTimeout) {
+			LOGGER.debug(() -> String.format("Trade AT refundTimeout '%d' doesn't match our refundTimeout '%d'", crossChainTradeData.refundTimeout, refundTimeout));
+			// We'll eventually refund
+			return;
+		}
+
+		// We're good to redeem AT
+
+		// Send 'redeem' MESSAGE to AT using both secret
+		byte[] secretA = tradeBotData.getSecret();
+		String qortalReceivingAddress = Base58.encode(tradeBotData.getReceivingAccountInfo()); // Actually contains whole address, not just PKH
+		byte[] messageData = LitecoinACCTv1.buildRedeemMessage(secretA, qortalReceivingAddress);
+		String messageRecipient = tradeBotData.getAtAddress();
+
+		boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, messageData);
+		if (!isMessageAlreadySent) {
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// Reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK) {
+				LOGGER.warn(() -> String.format("Unable to send MESSAGE to AT %s: %s", messageRecipient, result.name()));
+				return;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+				() -> String.format("Redeeming AT %s. Funds should arrive at %s",
+						tradeBotData.getAtAddress(), qortalReceivingAddress));
+	}
+
+	/**
+	 * Trade-bot is waiting for Alice to redeem Bob's AT, thus revealing secret-A which is required to spend the LTC funds from P2SH-A.
+	 * <p>
+	 * It's possible that Bob's AT has reached its trading timeout and automatically refunded QORT back to Bob. In which case,
+	 * trade-bot is done with this specific trade and finalizes in refunded state.
+	 * <p>
+	 * Assuming trade-bot can extract a valid secret-A from Alice's MESSAGE then trade-bot uses that to redeem the LTC funds from P2SH-A
+	 * to Bob's 'foreign'/Litecoin trade legacy-format address, as derived from trade private key.
+	 * <p>
+	 * (This could potentially be 'improved' to send LTC to any address of Bob's choosing by changing the transaction output).
+	 * <p>
+	 * If trade-bot successfully broadcasts the transaction, then this specific trade is done.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleBobWaitingForAtRedeem(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// AT should be 'finished' once Alice has redeemed QORT funds
+		if (!atData.getIsFinished())
+			// Not finished yet
+			return;
+
+		// If AT is REFUNDED or CANCELLED then something has gone wrong
+		if (crossChainTradeData.mode == AcctMode.REFUNDED || crossChainTradeData.mode == AcctMode.CANCELLED) {
+			// Alice hasn't redeemed the QORT, so there is no point in trying to redeem the LTC
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_REFUNDED,
+					() -> String.format("AT %s has auto-refunded - trade aborted", tradeBotData.getAtAddress()));
+
+			return;
+		}
+
+		byte[] secretA = LitecoinACCTv1.getInstance().findSecretA(repository, crossChainTradeData);
+		if (secretA == null) {
+			LOGGER.debug(() -> String.format("Unable to find secret-A from redeem message to AT %s?", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		// Use secret-A to redeem P2SH-A
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		byte[] receivingAccountInfo = tradeBotData.getReceivingAccountInfo();
+		int lockTimeA = crossChainTradeData.lockTimeA;
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(crossChainTradeData.partnerForeignPKH, lockTimeA, crossChainTradeData.creatorForeignPKH, crossChainTradeData.hashOfSecretA);
+		String p2shAddressA = litecoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Litecoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(litecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+		switch (htlcStatusA) {
+			case UNFUNDED:
+			case FUNDING_IN_PROGRESS:
+				// P2SH-A suddenly not funded? Our best bet at this point is to hope for AT auto-refund
+				return;
+
+			case REDEEM_IN_PROGRESS:
+			case REDEEMED:
+				// Double-check that we have redeemed P2SH-A...
+				break;
+
+			case REFUND_IN_PROGRESS:
+			case REFUNDED:
+				// Wait for AT to auto-refund
+				return;
+
+			case FUNDED: {
+				Coin redeemAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
+				ECKey redeemKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
+				List<TransactionOutput> fundingOutputs = litecoin.getUnspentOutputs(p2shAddressA);
+
+				Transaction p2shRedeemTransaction = BitcoinyHTLC.buildRedeemTransaction(litecoin.getNetworkParameters(), redeemAmount, redeemKey,
+						fundingOutputs, redeemScriptA, secretA, receivingAccountInfo);
+
+				litecoin.broadcastTransaction(p2shRedeemTransaction);
+				break;
+			}
+		}
+
+		String receivingAddress = litecoin.pkhToAddress(receivingAccountInfo);
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_DONE,
+				() -> String.format("P2SH-A %s redeemed. Funds should arrive at %s", tradeBotData.getAtAddress(), receivingAddress));
+	}
+
+	/**
+	 * Trade-bot is attempting to refund P2SH-A.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleAliceRefundingP2shA(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		int lockTimeA = tradeBotData.getLockTimeA();
+
+		// We can't refund P2SH-A until lockTime-A has passed
+		if (NTP.getTime() <= lockTimeA * 1000L)
+			return;
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		// We can't refund P2SH-A until median block time has passed lockTime-A (see BIP113)
+		int medianBlockTime = litecoin.getMedianBlockTime();
+		if (medianBlockTime <= lockTimeA)
+			return;
+
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeA, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+		String p2shAddressA = litecoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Litecoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(litecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+		switch (htlcStatusA) {
+			case UNFUNDED:
+			case FUNDING_IN_PROGRESS:
+				// Still waiting for P2SH-A to be funded...
+				return;
+
+			case REDEEM_IN_PROGRESS:
+			case REDEEMED:
+				// Too late!
+				TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+						() -> String.format("P2SH-A %s already spent!", p2shAddressA));
+				return;
+
+			case REFUND_IN_PROGRESS:
+			case REFUNDED:
+				break;
+
+			case FUNDED:{
+				Coin refundAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
+				ECKey refundKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
+				List<TransactionOutput> fundingOutputs = litecoin.getUnspentOutputs(p2shAddressA);
+
+				// Determine receive address for refund
+				String receiveAddress = litecoin.getUnusedReceiveAddress(tradeBotData.getForeignKey());
+				Address receiving = Address.fromString(litecoin.getNetworkParameters(), receiveAddress);
+
+				Transaction p2shRefundTransaction = BitcoinyHTLC.buildRefundTransaction(litecoin.getNetworkParameters(), refundAmount, refundKey,
+						fundingOutputs, redeemScriptA, lockTimeA, receiving.getHash());
+
+				litecoin.broadcastTransaction(p2shRefundTransaction);
+				break;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDED,
+				() -> String.format("LockTime-A reached. Refunded P2SH-A %s. Trade aborted", p2shAddressA));
+	}
+
+	/**
+	 * Returns true if Alice finds AT unexpectedly cancelled, refunded, redeemed or locked to someone else.
+	 * <p>
+	 * Will automatically update trade-bot state to <tt>ALICE_REFUNDING_A</tt> or <tt>ALICE_DONE</tt> as necessary.
+	 * 
+	 * @throws DataException
+	 * @throws ForeignBlockchainException
+	 */
+	private boolean aliceUnexpectedState(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// This is OK
+		if (!atData.getIsFinished() && crossChainTradeData.mode == AcctMode.OFFERING)
+			return false;
+
+		boolean isAtLockedToUs = tradeBotData.getTradeNativeAddress().equals(crossChainTradeData.qortalPartnerAddress);
+
+		if (!atData.getIsFinished() && crossChainTradeData.mode == AcctMode.TRADING)
+			if (isAtLockedToUs) {
+				// AT is trading with us - OK
+				return false;
+			} else {
+				TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+						() -> String.format("AT %s trading with someone else: %s. Refunding & aborting trade", tradeBotData.getAtAddress(), crossChainTradeData.qortalPartnerAddress));
+
+				return true;
+			}
+
+		if (atData.getIsFinished() && crossChainTradeData.mode == AcctMode.REDEEMED && isAtLockedToUs) {
+			// We've redeemed already?
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+					() -> String.format("AT %s already redeemed by us. Trade completed", tradeBotData.getAtAddress()));
+		} else {
+			// Any other state is not good, so start defensive refund
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+					() -> String.format("AT %s cancelled/refunded/redeemed by someone else/invalid state. Refunding & aborting trade", tradeBotData.getAtAddress()));
+		}
+
+		return true;
+	}
+
+	private long calcFeeTimestamp(int lockTimeA, int tradeTimeout) {
+		return (lockTimeA - tradeTimeout * 60) * 1000L;
+	}
+
+}

src/main/java/org/qortal/controller/tradebot/LitecoinACCTv2TradeBot.java

@@ -0,0 +1,885 @@
+package org.qortal.controller.tradebot;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.bitcoinj.core.*;
+import org.bitcoinj.script.Script.ScriptType;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.account.PublicKeyAccount;
+import org.qortal.api.model.crosschain.TradeBotCreateRequest;
+import org.qortal.asset.Asset;
+import org.qortal.crosschain.*;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.data.transaction.BaseTransactionData;
+import org.qortal.data.transaction.DeployAtTransactionData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.transaction.DeployAtTransaction;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.transaction.DeployAtTransactionTransformer;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import static java.util.Arrays.stream;
+import static java.util.stream.Collectors.toMap;
+
+/**
+ * Performing cross-chain trading steps on behalf of user.
+ * <p>
+ * We deal with three different independent state-spaces here:
+ * <ul>
+ * 	<li>Qortal blockchain</li>
+ * 	<li>Foreign blockchain</li>
+ * 	<li>Trade-bot entries</li>
+ * </ul>
+ */
+public class LitecoinACCTv2TradeBot implements AcctTradeBot {
+
+	private static final Logger LOGGER = LogManager.getLogger(LitecoinACCTv2TradeBot.class);
+
+	public enum State implements TradeBot.StateNameAndValueSupplier {
+		BOB_WAITING_FOR_AT_CONFIRM(10, false, false),
+		BOB_WAITING_FOR_MESSAGE(15, true, true),
+		BOB_WAITING_FOR_AT_REDEEM(25, true, true),
+		BOB_DONE(30, false, false),
+		BOB_REFUNDED(35, false, false),
+
+		ALICE_WAITING_FOR_AT_LOCK(85, true, true),
+		ALICE_DONE(95, false, false),
+		ALICE_REFUNDING_A(105, true, true),
+		ALICE_REFUNDED(110, false, false);
+
+		private static final Map<Integer, State> map = stream(State.values()).collect(toMap(state -> state.value, state -> state));
+
+		public final int value;
+		public final boolean requiresAtData;
+		public final boolean requiresTradeData;
+
+		State(int value, boolean requiresAtData, boolean requiresTradeData) {
+			this.value = value;
+			this.requiresAtData = requiresAtData;
+			this.requiresTradeData = requiresTradeData;
+		}
+
+		public static State valueOf(int value) {
+			return map.get(value);
+		}
+
+		@Override
+		public String getState() {
+			return this.name();
+		}
+
+		@Override
+		public int getStateValue() {
+			return this.value;
+		}
+	}
+
+	/** Maximum time Bob waits for his AT creation transaction to be confirmed into a block. (milliseconds) */
+	private static final long MAX_AT_CONFIRMATION_PERIOD = 24 * 60 * 60 * 1000L; // ms
+
+	private static LitecoinACCTv2TradeBot instance;
+
+	private final List<String> endStates = Arrays.asList(State.BOB_DONE, State.BOB_REFUNDED, State.ALICE_DONE, State.ALICE_REFUNDING_A, State.ALICE_REFUNDED).stream()
+			.map(State::name)
+			.collect(Collectors.toUnmodifiableList());
+
+	private LitecoinACCTv2TradeBot() {
+	}
+
+	public static synchronized LitecoinACCTv2TradeBot getInstance() {
+		if (instance == null)
+			instance = new LitecoinACCTv2TradeBot();
+
+		return instance;
+	}
+
+	@Override
+	public List<String> getEndStates() {
+		return this.endStates;
+	}
+
+	/**
+	 * Creates a new trade-bot entry from the "Bob" viewpoint, i.e. OFFERing QORT in exchange for LTC.
+	 * <p>
+	 * Generates:
+	 * <ul>
+	 * 	<li>new 'trade' private key</li>
+	 * </ul>
+	 * Derives:
+	 * <ul>
+	 * 	<li>'native' (as in Qortal) public key, public key hash, address (starting with Q)</li>
+	 * 	<li>'foreign' (as in Litecoin) public key, public key hash</li>
+	 * </ul>
+	 * A Qortal AT is then constructed including the following as constants in the 'data segment':
+	 * <ul>
+	 * 	<li>'native'/Qortal 'trade' address - used as a MESSAGE contact</li>
+	 * 	<li>'foreign'/Litecoin public key hash - used by Alice's P2SH scripts to allow redeem</li>
+	 * 	<li>QORT amount on offer by Bob</li>
+	 * 	<li>LTC amount expected in return by Bob (from Alice)</li>
+	 * 	<li>trading timeout, in case things go wrong and everyone needs to refund</li>
+	 * </ul>
+	 * Returns a DEPLOY_AT transaction that needs to be signed and broadcast to the Qortal network.
+	 * <p>
+	 * Trade-bot will wait for Bob's AT to be deployed before taking next step.
+	 * <p>
+	 * @param repository
+	 * @param tradeBotCreateRequest
+	 * @return raw, unsigned DEPLOY_AT transaction
+	 * @throws DataException
+	 */
+	public byte[] createTrade(Repository repository, TradeBotCreateRequest tradeBotCreateRequest) throws DataException {
+		byte[] tradePrivateKey = TradeBot.generateTradePrivateKey();
+
+		byte[] tradeNativePublicKey = TradeBot.deriveTradeNativePublicKey(tradePrivateKey);
+		byte[] tradeNativePublicKeyHash = Crypto.hash160(tradeNativePublicKey);
+		String tradeNativeAddress = Crypto.toAddress(tradeNativePublicKey);
+
+		byte[] tradeForeignPublicKey = TradeBot.deriveTradeForeignPublicKey(tradePrivateKey);
+		byte[] tradeForeignPublicKeyHash = Crypto.hash160(tradeForeignPublicKey);
+
+		// Convert Litecoin receiving address into public key hash (we only support P2PKH at this time)
+		Address litecoinReceivingAddress;
+		try {
+			litecoinReceivingAddress = Address.fromString(Litecoin.getInstance().getNetworkParameters(), tradeBotCreateRequest.receivingAddress);
+		} catch (AddressFormatException e) {
+			throw new DataException("Unsupported Litecoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+		}
+		if (litecoinReceivingAddress.getOutputScriptType() != ScriptType.P2PKH)
+			throw new DataException("Unsupported Litecoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+
+		byte[] litecoinReceivingAccountInfo = litecoinReceivingAddress.getHash();
+
+		PublicKeyAccount creator = new PublicKeyAccount(repository, tradeBotCreateRequest.creatorPublicKey);
+
+		// Deploy AT
+		long timestamp = NTP.getTime();
+		byte[] reference = creator.getLastReference();
+		long fee = 0L;
+		byte[] signature = null;
+		BaseTransactionData baseTransactionData = new BaseTransactionData(timestamp, Group.NO_GROUP, reference, creator.getPublicKey(), fee, signature);
+
+		String name = "QORT/LTC ACCT";
+		String description = "QORT/LTC cross-chain trade";
+		String aTType = "ACCT";
+		String tags = "ACCT QORT LTC";
+		byte[] creationBytes = LitecoinACCTv2.buildQortalAT(tradeNativeAddress, tradeForeignPublicKeyHash, tradeBotCreateRequest.qortAmount,
+				tradeBotCreateRequest.foreignAmount, tradeBotCreateRequest.tradeTimeout);
+		long amount = tradeBotCreateRequest.fundingQortAmount;
+
+		DeployAtTransactionData deployAtTransactionData = new DeployAtTransactionData(baseTransactionData, name, description, aTType, tags, creationBytes, amount, Asset.QORT);
+
+		DeployAtTransaction deployAtTransaction = new DeployAtTransaction(repository, deployAtTransactionData);
+		fee = deployAtTransaction.calcRecommendedFee();
+		deployAtTransactionData.setFee(fee);
+
+		DeployAtTransaction.ensureATAddress(deployAtTransactionData);
+		String atAddress = deployAtTransactionData.getAtAddress();
+
+		TradeBotData tradeBotData =  new TradeBotData(tradePrivateKey, LitecoinACCTv2.NAME,
+				State.BOB_WAITING_FOR_AT_CONFIRM.name(), State.BOB_WAITING_FOR_AT_CONFIRM.value,
+				creator.getAddress(), atAddress, timestamp, tradeBotCreateRequest.qortAmount,
+				tradeNativePublicKey, tradeNativePublicKeyHash, tradeNativeAddress,
+				null, null,
+				SupportedBlockchain.LITECOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				tradeBotCreateRequest.foreignAmount, null, null, null, litecoinReceivingAccountInfo);
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Built AT %s. Waiting for deployment", atAddress));
+
+		// Attempt to backup the trade bot data
+		TradeBot.backupTradeBotData(repository, null);
+
+		// Return to user for signing and broadcast as we don't have their Qortal private key
+		try {
+			return DeployAtTransactionTransformer.toBytes(deployAtTransactionData);
+		} catch (TransformationException e) {
+			throw new DataException("Failed to transform DEPLOY_AT transaction?", e);
+		}
+	}
+
+	/**
+	 * Creates a trade-bot entry from the 'Alice' viewpoint, i.e. matching LTC to an existing offer.
+	 * <p>
+	 * Requires a chosen trade offer from Bob, passed by <tt>crossChainTradeData</tt>
+	 * and access to a Litecoin wallet via <tt>xprv58</tt>.
+	 * <p>
+	 * The <tt>crossChainTradeData</tt> contains the current trade offer state
+	 * as extracted from the AT's data segment.
+	 * <p>
+	 * Access to a funded wallet is via a Litecoin BIP32 hierarchical deterministic key,
+	 * passed via <tt>xprv58</tt>.
+	 * <b>This key will be stored in your node's database</b>
+	 * to allow trade-bot to create/fund the necessary P2SH transactions!
+	 * However, due to the nature of BIP32 keys, it is possible to give the trade-bot
+	 * only a subset of wallet access (see BIP32 for more details).
+	 * <p>
+	 * As an example, the xprv58 can be extract from a <i>legacy, password-less</i>
+	 * Electrum wallet by going to the console tab and entering:<br>
+	 * <tt>wallet.keystore.xprv</tt><br>
+	 * which should result in a base58 string starting with either 'xprv' (for Litecoin main-net)
+	 * or 'tprv' for (Litecoin test-net).
+	 * <p>
+	 * It is envisaged that the value in <tt>xprv58</tt> will actually come from a Qortal-UI-managed wallet.
+	 * <p>
+	 * If sufficient funds are available, <b>this method will actually fund the P2SH-A</b>
+	 * with the Litecoin amount expected by 'Bob'.
+	 * <p>
+	 * If the Litecoin transaction is successfully broadcast to the network then
+	 * we also send a MESSAGE to Bob's trade-bot to let them know.
+	 * <p>
+	 * The trade-bot entry is saved to the repository and the cross-chain trading process commences.
+	 * <p>
+	 * @param repository
+	 * @param crossChainTradeData chosen trade OFFER that Alice wants to match
+	 * @param xprv58 funded wallet xprv in base58
+	 * @return true if P2SH-A funding transaction successfully broadcast to Litecoin network, false otherwise
+	 * @throws DataException
+	 */
+	public ResponseResult startResponse(Repository repository, ATData atData, ACCT acct, CrossChainTradeData crossChainTradeData, String xprv58, String receivingAddress) throws DataException {
+		byte[] tradePrivateKey = TradeBot.generateTradePrivateKey();
+		byte[] secretA = TradeBot.generateSecret();
+		byte[] hashOfSecretA = Crypto.hash160(secretA);
+
+		byte[] tradeNativePublicKey = TradeBot.deriveTradeNativePublicKey(tradePrivateKey);
+		byte[] tradeNativePublicKeyHash = Crypto.hash160(tradeNativePublicKey);
+		String tradeNativeAddress = Crypto.toAddress(tradeNativePublicKey);
+
+		byte[] tradeForeignPublicKey = TradeBot.deriveTradeForeignPublicKey(tradePrivateKey);
+		byte[] tradeForeignPublicKeyHash = Crypto.hash160(tradeForeignPublicKey);
+		byte[] receivingPublicKeyHash = Base58.decode(receivingAddress); // Actually the whole address, not just PKH
+
+		// We need to generate lockTime-A: add tradeTimeout to now
+		long now = NTP.getTime();
+		int lockTimeA = crossChainTradeData.tradeTimeout * 60 + (int) (now / 1000L);
+
+		TradeBotData tradeBotData =  new TradeBotData(tradePrivateKey, LitecoinACCTv2.NAME,
+				State.ALICE_WAITING_FOR_AT_LOCK.name(), State.ALICE_WAITING_FOR_AT_LOCK.value,
+				receivingAddress, crossChainTradeData.qortalAtAddress, now, crossChainTradeData.qortAmount,
+				tradeNativePublicKey, tradeNativePublicKeyHash, tradeNativeAddress,
+				secretA, hashOfSecretA,
+				SupportedBlockchain.LITECOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				crossChainTradeData.expectedForeignAmount, xprv58, null, lockTimeA, receivingPublicKeyHash);
+
+		// Attempt to backup the trade bot data
+		// Include tradeBotData as an additional parameter, since it's not in the repository yet
+		TradeBot.backupTradeBotData(repository, Arrays.asList(tradeBotData));
+
+		// Check we have enough funds via xprv58 to fund P2SH to cover expectedForeignAmount
+		long p2shFee;
+		try {
+			p2shFee = Litecoin.getInstance().getP2shFee(now);
+		} catch (ForeignBlockchainException e) {
+			LOGGER.debug("Couldn't estimate Litecoin fees?");
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		// Do not include fee for funding transaction as this is covered by buildSpend()
+		long amountA = crossChainTradeData.expectedForeignAmount + p2shFee /*redeeming/refunding P2SH-A*/;
+
+		// P2SH-A to be funded
+		byte[] redeemScriptBytes = BitcoinyHTLC.buildScript(tradeForeignPublicKeyHash, lockTimeA, crossChainTradeData.creatorForeignPKH, hashOfSecretA);
+		String p2shAddress = Litecoin.getInstance().deriveP2shAddress(redeemScriptBytes);
+
+		// Build transaction for funding P2SH-A
+		Transaction p2shFundingTransaction = Litecoin.getInstance().buildSpend(tradeBotData.getForeignKey(), p2shAddress, amountA);
+		if (p2shFundingTransaction == null) {
+			LOGGER.debug("Unable to build P2SH-A funding transaction - lack of funds?");
+			return ResponseResult.BALANCE_ISSUE;
+		}
+
+		try {
+			Litecoin.getInstance().broadcastTransaction(p2shFundingTransaction);
+		} catch (ForeignBlockchainException e) {
+			// We couldn't fund P2SH-A at this time
+			LOGGER.debug("Couldn't broadcast P2SH-A funding transaction?");
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		// Attempt to send MESSAGE to Bob's Qortal trade address
+		byte[] messageData = LitecoinACCTv2.buildOfferMessage(tradeBotData.getTradeForeignPublicKeyHash(), tradeBotData.getHashOfSecret(), tradeBotData.getLockTimeA());
+		String messageRecipient = crossChainTradeData.qortalCreatorTradeAddress;
+
+		boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, messageData);
+		if (!isMessageAlreadySent) {
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK) {
+				LOGGER.warn(() -> String.format("Unable to send MESSAGE to Bob's trade-bot %s: %s", messageRecipient, result.name()));
+				return ResponseResult.NETWORK_ISSUE;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Funding P2SH-A %s. Messaged Bob. Waiting for AT-lock", p2shAddress));
+
+		return ResponseResult.OK;
+	}
+
+	@Override
+	public boolean canDelete(Repository repository, TradeBotData tradeBotData) throws DataException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null)
+			return true;
+
+		// If the AT doesn't exist then we might as well let the user tidy up
+		if (!repository.getATRepository().exists(tradeBotData.getAtAddress()))
+			return true;
+
+		switch (tradeBotState) {
+			case BOB_WAITING_FOR_AT_CONFIRM:
+			case ALICE_DONE:
+			case BOB_DONE:
+			case ALICE_REFUNDED:
+			case BOB_REFUNDED:
+			case ALICE_REFUNDING_A:
+				return true;
+
+			default:
+				return false;
+		}
+	}
+
+	@Override
+	public void progress(Repository repository, TradeBotData tradeBotData) throws DataException, ForeignBlockchainException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null) {
+			LOGGER.info(() -> String.format("Trade-bot entry for AT %s has invalid state?", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		ATData atData = null;
+		CrossChainTradeData tradeData = null;
+
+		if (tradeBotState.requiresAtData) {
+			// Attempt to fetch AT data
+			atData = repository.getATRepository().fromATAddress(tradeBotData.getAtAddress());
+			if (atData == null) {
+				LOGGER.debug(() -> String.format("Unable to fetch trade AT %s from repository", tradeBotData.getAtAddress()));
+				return;
+			}
+
+			if (tradeBotState.requiresTradeData) {
+				tradeData = LitecoinACCTv2.getInstance().populateTradeData(repository, atData);
+				if (tradeData == null) {
+					LOGGER.warn(() -> String.format("Unable to fetch ACCT trade data for AT %s from repository", tradeBotData.getAtAddress()));
+					return;
+				}
+			}
+		}
+
+		switch (tradeBotState) {
+			case BOB_WAITING_FOR_AT_CONFIRM:
+				handleBobWaitingForAtConfirm(repository, tradeBotData);
+				break;
+
+			case BOB_WAITING_FOR_MESSAGE:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleBobWaitingForMessage(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_WAITING_FOR_AT_LOCK:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleAliceWaitingForAtLock(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case BOB_WAITING_FOR_AT_REDEEM:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleBobWaitingForAtRedeem(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_DONE:
+			case BOB_DONE:
+				break;
+
+			case ALICE_REFUNDING_A:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleAliceRefundingP2shA(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_REFUNDED:
+			case BOB_REFUNDED:
+				break;
+		}
+	}
+
+	/**
+	 * Trade-bot is waiting for Bob's AT to deploy.
+	 * <p>
+	 * If AT is deployed, then trade-bot's next step is to wait for MESSAGE from Alice.
+	 */
+	private void handleBobWaitingForAtConfirm(Repository repository, TradeBotData tradeBotData) throws DataException {
+		if (!repository.getATRepository().exists(tradeBotData.getAtAddress())) {
+			if (NTP.getTime() - tradeBotData.getTimestamp() <= MAX_AT_CONFIRMATION_PERIOD)
+				return;
+
+			// We've waited ages for AT to be confirmed into a block but something has gone awry.
+			// After this long we assume transaction loss so give up with trade-bot entry too.
+			tradeBotData.setState(State.BOB_REFUNDED.name());
+			tradeBotData.setStateValue(State.BOB_REFUNDED.value);
+			tradeBotData.setTimestamp(NTP.getTime());
+			// We delete trade-bot entry here instead of saving, hence not using updateTradeBotState()
+			repository.getCrossChainRepository().delete(tradeBotData.getTradePrivateKey());
+			repository.saveChanges();
+
+			LOGGER.info(() -> String.format("AT %s never confirmed. Giving up on trade", tradeBotData.getAtAddress()));
+			TradeBot.notifyStateChange(tradeBotData);
+			return;
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_WAITING_FOR_MESSAGE,
+				() -> String.format("AT %s confirmed ready. Waiting for trade message", tradeBotData.getAtAddress()));
+	}
+
+	/**
+	 * Trade-bot is waiting for MESSAGE from Alice's trade-bot, containing Alice's trade info.
+	 * <p>
+	 * It's possible Bob has cancelling his trade offer, receiving an automatic QORT refund,
+	 * in which case trade-bot is done with this specific trade and finalizes on refunded state.
+	 * <p>
+	 * Assuming trade is still on offer, trade-bot checks the contents of MESSAGE from Alice's trade-bot.
+	 * <p>
+	 * Details from Alice are used to derive P2SH-A address and this is checked for funding balance.
+	 * <p>
+	 * Assuming P2SH-A has at least expected Litecoin balance,
+	 * Bob's trade-bot constructs a zero-fee, PoW MESSAGE to send to Bob's AT with more trade details.
+	 * <p>
+	 * On processing this MESSAGE, Bob's AT should switch into 'TRADE' mode and only trade with Alice.
+	 * <p>
+	 * Trade-bot's next step is to wait for Alice to redeem the AT, which will allow Bob to
+	 * extract secret-A needed to redeem Alice's P2SH.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleBobWaitingForMessage(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// If AT has finished then Bob likely cancelled his trade offer
+		if (atData.getIsFinished()) {
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_REFUNDED,
+					() -> String.format("AT %s cancelled - trading aborted", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		String address = tradeBotData.getTradeNativeAddress();
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(null, address, null, null, null);
+
+		for (MessageTransactionData messageTransactionData : messageTransactionsData) {
+			if (messageTransactionData.isText())
+				continue;
+
+			// We're expecting: HASH160(secret-A), Alice's Litecoin pubkeyhash and lockTime-A
+			byte[] messageData = messageTransactionData.getData();
+			LitecoinACCTv2.OfferMessageData offerMessageData = LitecoinACCTv2.extractOfferMessageData(messageData);
+			if (offerMessageData == null)
+				continue;
+
+			byte[] aliceForeignPublicKeyHash = offerMessageData.partnerLitecoinPKH;
+			byte[] hashOfSecretA = offerMessageData.hashOfSecretA;
+			int lockTimeA = (int) offerMessageData.lockTimeA;
+			long messageTimestamp = messageTransactionData.getTimestamp();
+			int refundTimeout = LitecoinACCTv2.calcRefundTimeout(messageTimestamp, lockTimeA);
+
+			// Determine P2SH-A address and confirm funded
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(aliceForeignPublicKeyHash, lockTimeA, tradeBotData.getTradeForeignPublicKeyHash(), hashOfSecretA);
+			String p2shAddressA = litecoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Litecoin.getInstance().getP2shFee(feeTimestamp);
+			final long minimumAmountA = tradeBotData.getForeignAmount() + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(litecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+			switch (htlcStatusA) {
+				case UNFUNDED:
+				case FUNDING_IN_PROGRESS:
+					// There might be another MESSAGE from someone else with an actually funded P2SH-A...
+					continue;
+
+				case REDEEM_IN_PROGRESS:
+				case REDEEMED:
+					// We've already redeemed this?
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_DONE,
+							() -> String.format("P2SH-A %s already spent? Assuming trade complete", p2shAddressA));
+					return;
+
+				case REFUND_IN_PROGRESS:
+				case REFUNDED:
+					// This P2SH-A is burnt, but there might be another MESSAGE from someone else with an actually funded P2SH-A...
+					continue;
+
+				case FUNDED:
+					// Fall-through out of switch...
+					break;
+			}
+
+			// Good to go - send MESSAGE to AT
+
+			String aliceNativeAddress = Crypto.toAddress(messageTransactionData.getCreatorPublicKey());
+
+			// Build outgoing message, padding each part to 32 bytes to make it easier for AT to consume
+			byte[] outgoingMessageData = LitecoinACCTv2.buildTradeMessage(aliceNativeAddress, aliceForeignPublicKeyHash, hashOfSecretA, lockTimeA, refundTimeout);
+			String messageRecipient = tradeBotData.getAtAddress();
+
+			boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, outgoingMessageData);
+			if (!isMessageAlreadySent) {
+				PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+				MessageTransaction outgoingMessageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, outgoingMessageData, false, false);
+
+				outgoingMessageTransaction.computeNonce();
+				outgoingMessageTransaction.sign(sender);
+
+				// reset repository state to prevent deadlock
+				repository.discardChanges();
+				ValidationResult result = outgoingMessageTransaction.importAsUnconfirmed();
+
+				if (result != ValidationResult.OK) {
+					LOGGER.warn(() -> String.format("Unable to send MESSAGE to AT %s: %s", messageRecipient, result.name()));
+					return;
+				}
+			}
+
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_WAITING_FOR_AT_REDEEM,
+					() -> String.format("Locked AT %s to %s. Waiting for AT redeem", tradeBotData.getAtAddress(), aliceNativeAddress));
+
+			return;
+		}
+	}
+
+	/**
+	 * Trade-bot is waiting for Bob's AT to switch to TRADE mode and lock trade to Alice only.
+	 * <p>
+	 * It's possible that Bob has cancelled his trade offer in the mean time, or that somehow
+	 * this process has taken so long that we've reached P2SH-A's locktime, or that someone else
+	 * has managed to trade with Bob. In any of these cases, trade-bot switches to begin the refunding process.
+	 * <p>
+	 * Assuming Bob's AT is locked to Alice, trade-bot checks AT's state data to make sure it is correct.
+	 * <p>
+	 * If all is well, trade-bot then redeems AT using Alice's secret-A, releasing Bob's QORT to Alice.
+	 * <p>
+	 * In revealing a valid secret-A, Bob can then redeem the LTC funds from P2SH-A.
+	 * <p>
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleAliceWaitingForAtLock(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		if (aliceUnexpectedState(repository, tradeBotData, atData, crossChainTradeData))
+			return;
+
+		Litecoin litecoin = Litecoin.getInstance();
+		int lockTimeA = tradeBotData.getLockTimeA();
+
+		// Refund P2SH-A if we've passed lockTime-A
+		if (NTP.getTime() >= lockTimeA * 1000L) {
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeA, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+			String p2shAddressA = litecoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Litecoin.getInstance().getP2shFee(feeTimestamp);
+			long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(litecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+			switch (htlcStatusA) {
+				case UNFUNDED:
+				case FUNDING_IN_PROGRESS:
+				case FUNDED:
+					break;
+
+				case REDEEM_IN_PROGRESS:
+				case REDEEMED:
+					// Already redeemed?
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+							() -> String.format("P2SH-A %s already spent? Assuming trade completed", p2shAddressA));
+					return;
+
+				case REFUND_IN_PROGRESS:
+				case REFUNDED:
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDED,
+							() -> String.format("P2SH-A %s already refunded. Trade aborted", p2shAddressA));
+					return;
+
+			}
+
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+					() -> atData.getIsFinished()
+					? String.format("AT %s cancelled. Refunding P2SH-A %s - aborting trade", tradeBotData.getAtAddress(), p2shAddressA)
+					: String.format("LockTime-A reached, refunding P2SH-A %s - aborting trade", p2shAddressA));
+
+			return;
+		}
+
+		// We're waiting for AT to be in TRADE mode
+		if (crossChainTradeData.mode != AcctMode.TRADING)
+			return;
+
+		// AT is in TRADE mode and locked to us as checked by aliceUnexpectedState() above
+
+		// Find our MESSAGE to AT from previous state
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(tradeBotData.getTradeNativePublicKey(),
+				crossChainTradeData.qortalCreatorTradeAddress, null, null, null);
+		if (messageTransactionsData == null || messageTransactionsData.isEmpty()) {
+			LOGGER.warn(() -> String.format("Unable to find our message to trade creator %s?", crossChainTradeData.qortalCreatorTradeAddress));
+			return;
+		}
+
+		long recipientMessageTimestamp = messageTransactionsData.get(0).getTimestamp();
+		int refundTimeout = LitecoinACCTv2.calcRefundTimeout(recipientMessageTimestamp, lockTimeA);
+
+		// Our calculated refundTimeout should match AT's refundTimeout
+		if (refundTimeout != crossChainTradeData.refundTimeout) {
+			LOGGER.debug(() -> String.format("Trade AT refundTimeout '%d' doesn't match our refundTimeout '%d'", crossChainTradeData.refundTimeout, refundTimeout));
+			// We'll eventually refund
+			return;
+		}
+
+		// We're good to redeem AT
+
+		// Send 'redeem' MESSAGE to AT using both secret
+		byte[] secretA = tradeBotData.getSecret();
+		String qortalReceivingAddress = Base58.encode(tradeBotData.getReceivingAccountInfo()); // Actually contains whole address, not just PKH
+		byte[] messageData = LitecoinACCTv2.buildRedeemMessage(secretA, qortalReceivingAddress);
+		String messageRecipient = tradeBotData.getAtAddress();
+
+		boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, messageData);
+		if (!isMessageAlreadySent) {
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// Reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK) {
+				LOGGER.warn(() -> String.format("Unable to send MESSAGE to AT %s: %s", messageRecipient, result.name()));
+				return;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+				() -> String.format("Redeeming AT %s. Funds should arrive at %s",
+						tradeBotData.getAtAddress(), qortalReceivingAddress));
+	}
+
+	/**
+	 * Trade-bot is waiting for Alice to redeem Bob's AT, thus revealing secret-A which is required to spend the LTC funds from P2SH-A.
+	 * <p>
+	 * It's possible that Bob's AT has reached its trading timeout and automatically refunded QORT back to Bob. In which case,
+	 * trade-bot is done with this specific trade and finalizes in refunded state.
+	 * <p>
+	 * Assuming trade-bot can extract a valid secret-A from Alice's MESSAGE then trade-bot uses that to redeem the LTC funds from P2SH-A
+	 * to Bob's 'foreign'/Litecoin trade legacy-format address, as derived from trade private key.
+	 * <p>
+	 * (This could potentially be 'improved' to send LTC to any address of Bob's choosing by changing the transaction output).
+	 * <p>
+	 * If trade-bot successfully broadcasts the transaction, then this specific trade is done.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleBobWaitingForAtRedeem(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// AT should be 'finished' once Alice has redeemed QORT funds
+		if (!atData.getIsFinished())
+			// Not finished yet
+			return;
+
+		// If AT is REFUNDED or CANCELLED then something has gone wrong
+		if (crossChainTradeData.mode == AcctMode.REFUNDED || crossChainTradeData.mode == AcctMode.CANCELLED) {
+			// Alice hasn't redeemed the QORT, so there is no point in trying to redeem the LTC
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_REFUNDED,
+					() -> String.format("AT %s has auto-refunded - trade aborted", tradeBotData.getAtAddress()));
+
+			return;
+		}
+
+		byte[] secretA = LitecoinACCTv2.getInstance().findSecretA(repository, crossChainTradeData);
+		if (secretA == null) {
+			LOGGER.debug(() -> String.format("Unable to find secret-A from redeem message to AT %s?", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		// Use secret-A to redeem P2SH-A
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		byte[] receivingAccountInfo = tradeBotData.getReceivingAccountInfo();
+		int lockTimeA = crossChainTradeData.lockTimeA;
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(crossChainTradeData.partnerForeignPKH, lockTimeA, crossChainTradeData.creatorForeignPKH, crossChainTradeData.hashOfSecretA);
+		String p2shAddressA = litecoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Litecoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(litecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+		switch (htlcStatusA) {
+			case UNFUNDED:
+			case FUNDING_IN_PROGRESS:
+				// P2SH-A suddenly not funded? Our best bet at this point is to hope for AT auto-refund
+				return;
+
+			case REDEEM_IN_PROGRESS:
+			case REDEEMED:
+				// Double-check that we have redeemed P2SH-A...
+				break;
+
+			case REFUND_IN_PROGRESS:
+			case REFUNDED:
+				// Wait for AT to auto-refund
+				return;
+
+			case FUNDED: {
+				Coin redeemAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
+				ECKey redeemKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
+				List<TransactionOutput> fundingOutputs = litecoin.getUnspentOutputs(p2shAddressA);
+
+				Transaction p2shRedeemTransaction = BitcoinyHTLC.buildRedeemTransaction(litecoin.getNetworkParameters(), redeemAmount, redeemKey,
+						fundingOutputs, redeemScriptA, secretA, receivingAccountInfo);
+
+				litecoin.broadcastTransaction(p2shRedeemTransaction);
+				break;
+			}
+		}
+
+		String receivingAddress = litecoin.pkhToAddress(receivingAccountInfo);
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_DONE,
+				() -> String.format("P2SH-A %s redeemed. Funds should arrive at %s", tradeBotData.getAtAddress(), receivingAddress));
+	}
+
+	/**
+	 * Trade-bot is attempting to refund P2SH-A.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleAliceRefundingP2shA(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		int lockTimeA = tradeBotData.getLockTimeA();
+
+		// We can't refund P2SH-A until lockTime-A has passed
+		if (NTP.getTime() <= lockTimeA * 1000L)
+			return;
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		// We can't refund P2SH-A until median block time has passed lockTime-A (see BIP113)
+		int medianBlockTime = litecoin.getMedianBlockTime();
+		if (medianBlockTime <= lockTimeA)
+			return;
+
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeA, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+		String p2shAddressA = litecoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Litecoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(litecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+		switch (htlcStatusA) {
+			case UNFUNDED:
+			case FUNDING_IN_PROGRESS:
+				// Still waiting for P2SH-A to be funded...
+				return;
+
+			case REDEEM_IN_PROGRESS:
+			case REDEEMED:
+				// Too late!
+				TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+						() -> String.format("P2SH-A %s already spent!", p2shAddressA));
+				return;
+
+			case REFUND_IN_PROGRESS:
+			case REFUNDED:
+				break;
+
+			case FUNDED:{
+				Coin refundAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
+				ECKey refundKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
+				List<TransactionOutput> fundingOutputs = litecoin.getUnspentOutputs(p2shAddressA);
+
+				// Determine receive address for refund
+				String receiveAddress = litecoin.getUnusedReceiveAddress(tradeBotData.getForeignKey());
+				Address receiving = Address.fromString(litecoin.getNetworkParameters(), receiveAddress);
+
+				Transaction p2shRefundTransaction = BitcoinyHTLC.buildRefundTransaction(litecoin.getNetworkParameters(), refundAmount, refundKey,
+						fundingOutputs, redeemScriptA, lockTimeA, receiving.getHash());
+
+				litecoin.broadcastTransaction(p2shRefundTransaction);
+				break;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDED,
+				() -> String.format("LockTime-A reached. Refunded P2SH-A %s. Trade aborted", p2shAddressA));
+	}
+
+	/**
+	 * Returns true if Alice finds AT unexpectedly cancelled, refunded, redeemed or locked to someone else.
+	 * <p>
+	 * Will automatically update trade-bot state to <tt>ALICE_REFUNDING_A</tt> or <tt>ALICE_DONE</tt> as necessary.
+	 * 
+	 * @throws DataException
+	 * @throws ForeignBlockchainException
+	 */
+	private boolean aliceUnexpectedState(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// This is OK
+		if (!atData.getIsFinished() && crossChainTradeData.mode == AcctMode.OFFERING)
+			return false;
+
+		boolean isAtLockedToUs = tradeBotData.getTradeNativeAddress().equals(crossChainTradeData.qortalPartnerAddress);
+
+		if (!atData.getIsFinished() && crossChainTradeData.mode == AcctMode.TRADING)
+			if (isAtLockedToUs) {
+				// AT is trading with us - OK
+				return false;
+			} else {
+				TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+						() -> String.format("AT %s trading with someone else: %s. Refunding & aborting trade", tradeBotData.getAtAddress(), crossChainTradeData.qortalPartnerAddress));
+
+				return true;
+			}
+
+		if (atData.getIsFinished() && crossChainTradeData.mode == AcctMode.REDEEMED && isAtLockedToUs) {
+			// We've redeemed already?
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+					() -> String.format("AT %s already redeemed by us. Trade completed", tradeBotData.getAtAddress()));
+		} else {
+			// Any other state is not good, so start defensive refund
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+					() -> String.format("AT %s cancelled/refunded/redeemed by someone else/invalid state. Refunding & aborting trade", tradeBotData.getAtAddress()));
+		}
+
+		return true;
+	}
+
+	private long calcFeeTimestamp(int lockTimeA, int tradeTimeout) {
+		return (lockTimeA - tradeTimeout * 60) * 1000L;
+	}
+
+}

src/main/java/org/qortal/controller/tradebot/LitecoinACCTv3TradeBot.java

@@ -0,0 +1,885 @@
+package org.qortal.controller.tradebot;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.bitcoinj.core.*;
+import org.bitcoinj.script.Script.ScriptType;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.account.PublicKeyAccount;
+import org.qortal.api.model.crosschain.TradeBotCreateRequest;
+import org.qortal.asset.Asset;
+import org.qortal.crosschain.*;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.data.transaction.BaseTransactionData;
+import org.qortal.data.transaction.DeployAtTransactionData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.transaction.DeployAtTransaction;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.transaction.DeployAtTransactionTransformer;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import static java.util.Arrays.stream;
+import static java.util.stream.Collectors.toMap;
+
+/**
+ * Performing cross-chain trading steps on behalf of user.
+ * <p>
+ * We deal with three different independent state-spaces here:
+ * <ul>
+ * 	<li>Qortal blockchain</li>
+ * 	<li>Foreign blockchain</li>
+ * 	<li>Trade-bot entries</li>
+ * </ul>
+ */
+public class LitecoinACCTv3TradeBot implements AcctTradeBot {
+
+	private static final Logger LOGGER = LogManager.getLogger(LitecoinACCTv3TradeBot.class);
+
+	public enum State implements TradeBot.StateNameAndValueSupplier {
+		BOB_WAITING_FOR_AT_CONFIRM(10, false, false),
+		BOB_WAITING_FOR_MESSAGE(15, true, true),
+		BOB_WAITING_FOR_AT_REDEEM(25, true, true),
+		BOB_DONE(30, false, false),
+		BOB_REFUNDED(35, false, false),
+
+		ALICE_WAITING_FOR_AT_LOCK(85, true, true),
+		ALICE_DONE(95, false, false),
+		ALICE_REFUNDING_A(105, true, true),
+		ALICE_REFUNDED(110, false, false);
+
+		private static final Map<Integer, State> map = stream(State.values()).collect(toMap(state -> state.value, state -> state));
+
+		public final int value;
+		public final boolean requiresAtData;
+		public final boolean requiresTradeData;
+
+		State(int value, boolean requiresAtData, boolean requiresTradeData) {
+			this.value = value;
+			this.requiresAtData = requiresAtData;
+			this.requiresTradeData = requiresTradeData;
+		}
+
+		public static State valueOf(int value) {
+			return map.get(value);
+		}
+
+		@Override
+		public String getState() {
+			return this.name();
+		}
+
+		@Override
+		public int getStateValue() {
+			return this.value;
+		}
+	}
+
+	/** Maximum time Bob waits for his AT creation transaction to be confirmed into a block. (milliseconds) */
+	private static final long MAX_AT_CONFIRMATION_PERIOD = 24 * 60 * 60 * 1000L; // ms
+
+	private static LitecoinACCTv3TradeBot instance;
+
+	private final List<String> endStates = Arrays.asList(State.BOB_DONE, State.BOB_REFUNDED, State.ALICE_DONE, State.ALICE_REFUNDING_A, State.ALICE_REFUNDED).stream()
+			.map(State::name)
+			.collect(Collectors.toUnmodifiableList());
+
+	private LitecoinACCTv3TradeBot() {
+	}
+
+	public static synchronized LitecoinACCTv3TradeBot getInstance() {
+		if (instance == null)
+			instance = new LitecoinACCTv3TradeBot();
+
+		return instance;
+	}
+
+	@Override
+	public List<String> getEndStates() {
+		return this.endStates;
+	}
+
+	/**
+	 * Creates a new trade-bot entry from the "Bob" viewpoint, i.e. OFFERing QORT in exchange for LTC.
+	 * <p>
+	 * Generates:
+	 * <ul>
+	 * 	<li>new 'trade' private key</li>
+	 * </ul>
+	 * Derives:
+	 * <ul>
+	 * 	<li>'native' (as in Qortal) public key, public key hash, address (starting with Q)</li>
+	 * 	<li>'foreign' (as in Litecoin) public key, public key hash</li>
+	 * </ul>
+	 * A Qortal AT is then constructed including the following as constants in the 'data segment':
+	 * <ul>
+	 * 	<li>'native'/Qortal 'trade' address - used as a MESSAGE contact</li>
+	 * 	<li>'foreign'/Litecoin public key hash - used by Alice's P2SH scripts to allow redeem</li>
+	 * 	<li>QORT amount on offer by Bob</li>
+	 * 	<li>LTC amount expected in return by Bob (from Alice)</li>
+	 * 	<li>trading timeout, in case things go wrong and everyone needs to refund</li>
+	 * </ul>
+	 * Returns a DEPLOY_AT transaction that needs to be signed and broadcast to the Qortal network.
+	 * <p>
+	 * Trade-bot will wait for Bob's AT to be deployed before taking next step.
+	 * <p>
+	 * @param repository
+	 * @param tradeBotCreateRequest
+	 * @return raw, unsigned DEPLOY_AT transaction
+	 * @throws DataException
+	 */
+	public byte[] createTrade(Repository repository, TradeBotCreateRequest tradeBotCreateRequest) throws DataException {
+		byte[] tradePrivateKey = TradeBot.generateTradePrivateKey();
+
+		byte[] tradeNativePublicKey = TradeBot.deriveTradeNativePublicKey(tradePrivateKey);
+		byte[] tradeNativePublicKeyHash = Crypto.hash160(tradeNativePublicKey);
+		String tradeNativeAddress = Crypto.toAddress(tradeNativePublicKey);
+
+		byte[] tradeForeignPublicKey = TradeBot.deriveTradeForeignPublicKey(tradePrivateKey);
+		byte[] tradeForeignPublicKeyHash = Crypto.hash160(tradeForeignPublicKey);
+
+		// Convert Litecoin receiving address into public key hash (we only support P2PKH at this time)
+		Address litecoinReceivingAddress;
+		try {
+			litecoinReceivingAddress = Address.fromString(Litecoin.getInstance().getNetworkParameters(), tradeBotCreateRequest.receivingAddress);
+		} catch (AddressFormatException e) {
+			throw new DataException("Unsupported Litecoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+		}
+		if (litecoinReceivingAddress.getOutputScriptType() != ScriptType.P2PKH)
+			throw new DataException("Unsupported Litecoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+
+		byte[] litecoinReceivingAccountInfo = litecoinReceivingAddress.getHash();
+
+		PublicKeyAccount creator = new PublicKeyAccount(repository, tradeBotCreateRequest.creatorPublicKey);
+
+		// Deploy AT
+		long timestamp = NTP.getTime();
+		byte[] reference = creator.getLastReference();
+		long fee = 0L;
+		byte[] signature = null;
+		BaseTransactionData baseTransactionData = new BaseTransactionData(timestamp, Group.NO_GROUP, reference, creator.getPublicKey(), fee, signature);
+
+		String name = "QORT/LTC ACCT";
+		String description = "QORT/LTC cross-chain trade";
+		String aTType = "ACCT";
+		String tags = "ACCT QORT LTC";
+		byte[] creationBytes = LitecoinACCTv3.buildQortalAT(tradeNativeAddress, tradeForeignPublicKeyHash, tradeBotCreateRequest.qortAmount,
+				tradeBotCreateRequest.foreignAmount, tradeBotCreateRequest.tradeTimeout);
+		long amount = tradeBotCreateRequest.fundingQortAmount;
+
+		DeployAtTransactionData deployAtTransactionData = new DeployAtTransactionData(baseTransactionData, name, description, aTType, tags, creationBytes, amount, Asset.QORT);
+
+		DeployAtTransaction deployAtTransaction = new DeployAtTransaction(repository, deployAtTransactionData);
+		fee = deployAtTransaction.calcRecommendedFee();
+		deployAtTransactionData.setFee(fee);
+
+		DeployAtTransaction.ensureATAddress(deployAtTransactionData);
+		String atAddress = deployAtTransactionData.getAtAddress();
+
+		TradeBotData tradeBotData =  new TradeBotData(tradePrivateKey, LitecoinACCTv3.NAME,
+				State.BOB_WAITING_FOR_AT_CONFIRM.name(), State.BOB_WAITING_FOR_AT_CONFIRM.value,
+				creator.getAddress(), atAddress, timestamp, tradeBotCreateRequest.qortAmount,
+				tradeNativePublicKey, tradeNativePublicKeyHash, tradeNativeAddress,
+				null, null,
+				SupportedBlockchain.LITECOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				tradeBotCreateRequest.foreignAmount, null, null, null, litecoinReceivingAccountInfo);
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Built AT %s. Waiting for deployment", atAddress));
+
+		// Attempt to backup the trade bot data
+		TradeBot.backupTradeBotData(repository, null);
+
+		// Return to user for signing and broadcast as we don't have their Qortal private key
+		try {
+			return DeployAtTransactionTransformer.toBytes(deployAtTransactionData);
+		} catch (TransformationException e) {
+			throw new DataException("Failed to transform DEPLOY_AT transaction?", e);
+		}
+	}
+
+	/**
+	 * Creates a trade-bot entry from the 'Alice' viewpoint, i.e. matching LTC to an existing offer.
+	 * <p>
+	 * Requires a chosen trade offer from Bob, passed by <tt>crossChainTradeData</tt>
+	 * and access to a Litecoin wallet via <tt>xprv58</tt>.
+	 * <p>
+	 * The <tt>crossChainTradeData</tt> contains the current trade offer state
+	 * as extracted from the AT's data segment.
+	 * <p>
+	 * Access to a funded wallet is via a Litecoin BIP32 hierarchical deterministic key,
+	 * passed via <tt>xprv58</tt>.
+	 * <b>This key will be stored in your node's database</b>
+	 * to allow trade-bot to create/fund the necessary P2SH transactions!
+	 * However, due to the nature of BIP32 keys, it is possible to give the trade-bot
+	 * only a subset of wallet access (see BIP32 for more details).
+	 * <p>
+	 * As an example, the xprv58 can be extract from a <i>legacy, password-less</i>
+	 * Electrum wallet by going to the console tab and entering:<br>
+	 * <tt>wallet.keystore.xprv</tt><br>
+	 * which should result in a base58 string starting with either 'xprv' (for Litecoin main-net)
+	 * or 'tprv' for (Litecoin test-net).
+	 * <p>
+	 * It is envisaged that the value in <tt>xprv58</tt> will actually come from a Qortal-UI-managed wallet.
+	 * <p>
+	 * If sufficient funds are available, <b>this method will actually fund the P2SH-A</b>
+	 * with the Litecoin amount expected by 'Bob'.
+	 * <p>
+	 * If the Litecoin transaction is successfully broadcast to the network then
+	 * we also send a MESSAGE to Bob's trade-bot to let them know.
+	 * <p>
+	 * The trade-bot entry is saved to the repository and the cross-chain trading process commences.
+	 * <p>
+	 * @param repository
+	 * @param crossChainTradeData chosen trade OFFER that Alice wants to match
+	 * @param xprv58 funded wallet xprv in base58
+	 * @return true if P2SH-A funding transaction successfully broadcast to Litecoin network, false otherwise
+	 * @throws DataException
+	 */
+	public ResponseResult startResponse(Repository repository, ATData atData, ACCT acct, CrossChainTradeData crossChainTradeData, String xprv58, String receivingAddress) throws DataException {
+		byte[] tradePrivateKey = TradeBot.generateTradePrivateKey();
+		byte[] secretA = TradeBot.generateSecret();
+		byte[] hashOfSecretA = Crypto.hash160(secretA);
+
+		byte[] tradeNativePublicKey = TradeBot.deriveTradeNativePublicKey(tradePrivateKey);
+		byte[] tradeNativePublicKeyHash = Crypto.hash160(tradeNativePublicKey);
+		String tradeNativeAddress = Crypto.toAddress(tradeNativePublicKey);
+
+		byte[] tradeForeignPublicKey = TradeBot.deriveTradeForeignPublicKey(tradePrivateKey);
+		byte[] tradeForeignPublicKeyHash = Crypto.hash160(tradeForeignPublicKey);
+		byte[] receivingPublicKeyHash = Base58.decode(receivingAddress); // Actually the whole address, not just PKH
+
+		// We need to generate lockTime-A: add tradeTimeout to now
+		long now = NTP.getTime();
+		int lockTimeA = crossChainTradeData.tradeTimeout * 60 + (int) (now / 1000L);
+
+		TradeBotData tradeBotData =  new TradeBotData(tradePrivateKey, LitecoinACCTv3.NAME,
+				State.ALICE_WAITING_FOR_AT_LOCK.name(), State.ALICE_WAITING_FOR_AT_LOCK.value,
+				receivingAddress, crossChainTradeData.qortalAtAddress, now, crossChainTradeData.qortAmount,
+				tradeNativePublicKey, tradeNativePublicKeyHash, tradeNativeAddress,
+				secretA, hashOfSecretA,
+				SupportedBlockchain.LITECOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				crossChainTradeData.expectedForeignAmount, xprv58, null, lockTimeA, receivingPublicKeyHash);
+
+		// Attempt to backup the trade bot data
+		// Include tradeBotData as an additional parameter, since it's not in the repository yet
+		TradeBot.backupTradeBotData(repository, Arrays.asList(tradeBotData));
+
+		// Check we have enough funds via xprv58 to fund P2SH to cover expectedForeignAmount
+		long p2shFee;
+		try {
+			p2shFee = Litecoin.getInstance().getP2shFee(now);
+		} catch (ForeignBlockchainException e) {
+			LOGGER.debug("Couldn't estimate Litecoin fees?");
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		// Do not include fee for funding transaction as this is covered by buildSpend()
+		long amountA = crossChainTradeData.expectedForeignAmount + p2shFee /*redeeming/refunding P2SH-A*/;
+
+		// P2SH-A to be funded
+		byte[] redeemScriptBytes = BitcoinyHTLC.buildScript(tradeForeignPublicKeyHash, lockTimeA, crossChainTradeData.creatorForeignPKH, hashOfSecretA);
+		String p2shAddress = Litecoin.getInstance().deriveP2shAddress(redeemScriptBytes);
+
+		// Build transaction for funding P2SH-A
+		Transaction p2shFundingTransaction = Litecoin.getInstance().buildSpend(tradeBotData.getForeignKey(), p2shAddress, amountA);
+		if (p2shFundingTransaction == null) {
+			LOGGER.debug("Unable to build P2SH-A funding transaction - lack of funds?");
+			return ResponseResult.BALANCE_ISSUE;
+		}
+
+		try {
+			Litecoin.getInstance().broadcastTransaction(p2shFundingTransaction);
+		} catch (ForeignBlockchainException e) {
+			// We couldn't fund P2SH-A at this time
+			LOGGER.debug("Couldn't broadcast P2SH-A funding transaction?");
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		// Attempt to send MESSAGE to Bob's Qortal trade address
+		byte[] messageData = LitecoinACCTv3.buildOfferMessage(tradeBotData.getTradeForeignPublicKeyHash(), tradeBotData.getHashOfSecret(), tradeBotData.getLockTimeA());
+		String messageRecipient = crossChainTradeData.qortalCreatorTradeAddress;
+
+		boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, messageData);
+		if (!isMessageAlreadySent) {
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK) {
+				LOGGER.warn(() -> String.format("Unable to send MESSAGE to Bob's trade-bot %s: %s", messageRecipient, result.name()));
+				return ResponseResult.NETWORK_ISSUE;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Funding P2SH-A %s. Messaged Bob. Waiting for AT-lock", p2shAddress));
+
+		return ResponseResult.OK;
+	}
+
+	@Override
+	public boolean canDelete(Repository repository, TradeBotData tradeBotData) throws DataException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null)
+			return true;
+
+		// If the AT doesn't exist then we might as well let the user tidy up
+		if (!repository.getATRepository().exists(tradeBotData.getAtAddress()))
+			return true;
+
+		switch (tradeBotState) {
+			case BOB_WAITING_FOR_AT_CONFIRM:
+			case ALICE_DONE:
+			case BOB_DONE:
+			case ALICE_REFUNDED:
+			case BOB_REFUNDED:
+			case ALICE_REFUNDING_A:
+				return true;
+
+			default:
+				return false;
+		}
+	}
+
+	@Override
+	public void progress(Repository repository, TradeBotData tradeBotData) throws DataException, ForeignBlockchainException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null) {
+			LOGGER.info(() -> String.format("Trade-bot entry for AT %s has invalid state?", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		ATData atData = null;
+		CrossChainTradeData tradeData = null;
+
+		if (tradeBotState.requiresAtData) {
+			// Attempt to fetch AT data
+			atData = repository.getATRepository().fromATAddress(tradeBotData.getAtAddress());
+			if (atData == null) {
+				LOGGER.debug(() -> String.format("Unable to fetch trade AT %s from repository", tradeBotData.getAtAddress()));
+				return;
+			}
+
+			if (tradeBotState.requiresTradeData) {
+				tradeData = LitecoinACCTv3.getInstance().populateTradeData(repository, atData);
+				if (tradeData == null) {
+					LOGGER.warn(() -> String.format("Unable to fetch ACCT trade data for AT %s from repository", tradeBotData.getAtAddress()));
+					return;
+				}
+			}
+		}
+
+		switch (tradeBotState) {
+			case BOB_WAITING_FOR_AT_CONFIRM:
+				handleBobWaitingForAtConfirm(repository, tradeBotData);
+				break;
+
+			case BOB_WAITING_FOR_MESSAGE:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleBobWaitingForMessage(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_WAITING_FOR_AT_LOCK:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleAliceWaitingForAtLock(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case BOB_WAITING_FOR_AT_REDEEM:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleBobWaitingForAtRedeem(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_DONE:
+			case BOB_DONE:
+				break;
+
+			case ALICE_REFUNDING_A:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleAliceRefundingP2shA(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_REFUNDED:
+			case BOB_REFUNDED:
+				break;
+		}
+	}
+
+	/**
+	 * Trade-bot is waiting for Bob's AT to deploy.
+	 * <p>
+	 * If AT is deployed, then trade-bot's next step is to wait for MESSAGE from Alice.
+	 */
+	private void handleBobWaitingForAtConfirm(Repository repository, TradeBotData tradeBotData) throws DataException {
+		if (!repository.getATRepository().exists(tradeBotData.getAtAddress())) {
+			if (NTP.getTime() - tradeBotData.getTimestamp() <= MAX_AT_CONFIRMATION_PERIOD)
+				return;
+
+			// We've waited ages for AT to be confirmed into a block but something has gone awry.
+			// After this long we assume transaction loss so give up with trade-bot entry too.
+			tradeBotData.setState(State.BOB_REFUNDED.name());
+			tradeBotData.setStateValue(State.BOB_REFUNDED.value);
+			tradeBotData.setTimestamp(NTP.getTime());
+			// We delete trade-bot entry here instead of saving, hence not using updateTradeBotState()
+			repository.getCrossChainRepository().delete(tradeBotData.getTradePrivateKey());
+			repository.saveChanges();
+
+			LOGGER.info(() -> String.format("AT %s never confirmed. Giving up on trade", tradeBotData.getAtAddress()));
+			TradeBot.notifyStateChange(tradeBotData);
+			return;
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_WAITING_FOR_MESSAGE,
+				() -> String.format("AT %s confirmed ready. Waiting for trade message", tradeBotData.getAtAddress()));
+	}
+
+	/**
+	 * Trade-bot is waiting for MESSAGE from Alice's trade-bot, containing Alice's trade info.
+	 * <p>
+	 * It's possible Bob has cancelling his trade offer, receiving an automatic QORT refund,
+	 * in which case trade-bot is done with this specific trade and finalizes on refunded state.
+	 * <p>
+	 * Assuming trade is still on offer, trade-bot checks the contents of MESSAGE from Alice's trade-bot.
+	 * <p>
+	 * Details from Alice are used to derive P2SH-A address and this is checked for funding balance.
+	 * <p>
+	 * Assuming P2SH-A has at least expected Litecoin balance,
+	 * Bob's trade-bot constructs a zero-fee, PoW MESSAGE to send to Bob's AT with more trade details.
+	 * <p>
+	 * On processing this MESSAGE, Bob's AT should switch into 'TRADE' mode and only trade with Alice.
+	 * <p>
+	 * Trade-bot's next step is to wait for Alice to redeem the AT, which will allow Bob to
+	 * extract secret-A needed to redeem Alice's P2SH.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleBobWaitingForMessage(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// If AT has finished then Bob likely cancelled his trade offer
+		if (atData.getIsFinished()) {
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_REFUNDED,
+					() -> String.format("AT %s cancelled - trading aborted", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		String address = tradeBotData.getTradeNativeAddress();
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(null, address, null, null, null);
+
+		for (MessageTransactionData messageTransactionData : messageTransactionsData) {
+			if (messageTransactionData.isText())
+				continue;
+
+			// We're expecting: HASH160(secret-A), Alice's Litecoin pubkeyhash and lockTime-A
+			byte[] messageData = messageTransactionData.getData();
+			LitecoinACCTv3.OfferMessageData offerMessageData = LitecoinACCTv3.extractOfferMessageData(messageData);
+			if (offerMessageData == null)
+				continue;
+
+			byte[] aliceForeignPublicKeyHash = offerMessageData.partnerLitecoinPKH;
+			byte[] hashOfSecretA = offerMessageData.hashOfSecretA;
+			int lockTimeA = (int) offerMessageData.lockTimeA;
+			long messageTimestamp = messageTransactionData.getTimestamp();
+			int refundTimeout = LitecoinACCTv3.calcRefundTimeout(messageTimestamp, lockTimeA);
+
+			// Determine P2SH-A address and confirm funded
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(aliceForeignPublicKeyHash, lockTimeA, tradeBotData.getTradeForeignPublicKeyHash(), hashOfSecretA);
+			String p2shAddressA = litecoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Litecoin.getInstance().getP2shFee(feeTimestamp);
+			final long minimumAmountA = tradeBotData.getForeignAmount() + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(litecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+			switch (htlcStatusA) {
+				case UNFUNDED:
+				case FUNDING_IN_PROGRESS:
+					// There might be another MESSAGE from someone else with an actually funded P2SH-A...
+					continue;
+
+				case REDEEM_IN_PROGRESS:
+				case REDEEMED:
+					// We've already redeemed this?
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_DONE,
+							() -> String.format("P2SH-A %s already spent? Assuming trade complete", p2shAddressA));
+					return;
+
+				case REFUND_IN_PROGRESS:
+				case REFUNDED:
+					// This P2SH-A is burnt, but there might be another MESSAGE from someone else with an actually funded P2SH-A...
+					continue;
+
+				case FUNDED:
+					// Fall-through out of switch...
+					break;
+			}
+
+			// Good to go - send MESSAGE to AT
+
+			String aliceNativeAddress = Crypto.toAddress(messageTransactionData.getCreatorPublicKey());
+
+			// Build outgoing message, padding each part to 32 bytes to make it easier for AT to consume
+			byte[] outgoingMessageData = LitecoinACCTv3.buildTradeMessage(aliceNativeAddress, aliceForeignPublicKeyHash, hashOfSecretA, lockTimeA, refundTimeout);
+			String messageRecipient = tradeBotData.getAtAddress();
+
+			boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, outgoingMessageData);
+			if (!isMessageAlreadySent) {
+				PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+				MessageTransaction outgoingMessageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, outgoingMessageData, false, false);
+
+				outgoingMessageTransaction.computeNonce();
+				outgoingMessageTransaction.sign(sender);
+
+				// reset repository state to prevent deadlock
+				repository.discardChanges();
+				ValidationResult result = outgoingMessageTransaction.importAsUnconfirmed();
+
+				if (result != ValidationResult.OK) {
+					LOGGER.warn(() -> String.format("Unable to send MESSAGE to AT %s: %s", messageRecipient, result.name()));
+					return;
+				}
+			}
+
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_WAITING_FOR_AT_REDEEM,
+					() -> String.format("Locked AT %s to %s. Waiting for AT redeem", tradeBotData.getAtAddress(), aliceNativeAddress));
+
+			return;
+		}
+	}
+
+	/**
+	 * Trade-bot is waiting for Bob's AT to switch to TRADE mode and lock trade to Alice only.
+	 * <p>
+	 * It's possible that Bob has cancelled his trade offer in the mean time, or that somehow
+	 * this process has taken so long that we've reached P2SH-A's locktime, or that someone else
+	 * has managed to trade with Bob. In any of these cases, trade-bot switches to begin the refunding process.
+	 * <p>
+	 * Assuming Bob's AT is locked to Alice, trade-bot checks AT's state data to make sure it is correct.
+	 * <p>
+	 * If all is well, trade-bot then redeems AT using Alice's secret-A, releasing Bob's QORT to Alice.
+	 * <p>
+	 * In revealing a valid secret-A, Bob can then redeem the LTC funds from P2SH-A.
+	 * <p>
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleAliceWaitingForAtLock(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		if (aliceUnexpectedState(repository, tradeBotData, atData, crossChainTradeData))
+			return;
+
+		Litecoin litecoin = Litecoin.getInstance();
+		int lockTimeA = tradeBotData.getLockTimeA();
+
+		// Refund P2SH-A if we've passed lockTime-A
+		if (NTP.getTime() >= lockTimeA * 1000L) {
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeA, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+			String p2shAddressA = litecoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Litecoin.getInstance().getP2shFee(feeTimestamp);
+			long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(litecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+			switch (htlcStatusA) {
+				case UNFUNDED:
+				case FUNDING_IN_PROGRESS:
+				case FUNDED:
+					break;
+
+				case REDEEM_IN_PROGRESS:
+				case REDEEMED:
+					// Already redeemed?
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+							() -> String.format("P2SH-A %s already spent? Assuming trade completed", p2shAddressA));
+					return;
+
+				case REFUND_IN_PROGRESS:
+				case REFUNDED:
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDED,
+							() -> String.format("P2SH-A %s already refunded. Trade aborted", p2shAddressA));
+					return;
+
+			}
+
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+					() -> atData.getIsFinished()
+					? String.format("AT %s cancelled. Refunding P2SH-A %s - aborting trade", tradeBotData.getAtAddress(), p2shAddressA)
+					: String.format("LockTime-A reached, refunding P2SH-A %s - aborting trade", p2shAddressA));
+
+			return;
+		}
+
+		// We're waiting for AT to be in TRADE mode
+		if (crossChainTradeData.mode != AcctMode.TRADING)
+			return;
+
+		// AT is in TRADE mode and locked to us as checked by aliceUnexpectedState() above
+
+		// Find our MESSAGE to AT from previous state
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(tradeBotData.getTradeNativePublicKey(),
+				crossChainTradeData.qortalCreatorTradeAddress, null, null, null);
+		if (messageTransactionsData == null || messageTransactionsData.isEmpty()) {
+			LOGGER.warn(() -> String.format("Unable to find our message to trade creator %s?", crossChainTradeData.qortalCreatorTradeAddress));
+			return;
+		}
+
+		long recipientMessageTimestamp = messageTransactionsData.get(0).getTimestamp();
+		int refundTimeout = LitecoinACCTv3.calcRefundTimeout(recipientMessageTimestamp, lockTimeA);
+
+		// Our calculated refundTimeout should match AT's refundTimeout
+		if (refundTimeout != crossChainTradeData.refundTimeout) {
+			LOGGER.debug(() -> String.format("Trade AT refundTimeout '%d' doesn't match our refundTimeout '%d'", crossChainTradeData.refundTimeout, refundTimeout));
+			// We'll eventually refund
+			return;
+		}
+
+		// We're good to redeem AT
+
+		// Send 'redeem' MESSAGE to AT using both secret
+		byte[] secretA = tradeBotData.getSecret();
+		String qortalReceivingAddress = Base58.encode(tradeBotData.getReceivingAccountInfo()); // Actually contains whole address, not just PKH
+		byte[] messageData = LitecoinACCTv3.buildRedeemMessage(secretA, qortalReceivingAddress);
+		String messageRecipient = tradeBotData.getAtAddress();
+
+		boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, messageData);
+		if (!isMessageAlreadySent) {
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// Reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK) {
+				LOGGER.warn(() -> String.format("Unable to send MESSAGE to AT %s: %s", messageRecipient, result.name()));
+				return;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+				() -> String.format("Redeeming AT %s. Funds should arrive at %s",
+						tradeBotData.getAtAddress(), qortalReceivingAddress));
+	}
+
+	/**
+	 * Trade-bot is waiting for Alice to redeem Bob's AT, thus revealing secret-A which is required to spend the LTC funds from P2SH-A.
+	 * <p>
+	 * It's possible that Bob's AT has reached its trading timeout and automatically refunded QORT back to Bob. In which case,
+	 * trade-bot is done with this specific trade and finalizes in refunded state.
+	 * <p>
+	 * Assuming trade-bot can extract a valid secret-A from Alice's MESSAGE then trade-bot uses that to redeem the LTC funds from P2SH-A
+	 * to Bob's 'foreign'/Litecoin trade legacy-format address, as derived from trade private key.
+	 * <p>
+	 * (This could potentially be 'improved' to send LTC to any address of Bob's choosing by changing the transaction output).
+	 * <p>
+	 * If trade-bot successfully broadcasts the transaction, then this specific trade is done.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleBobWaitingForAtRedeem(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// AT should be 'finished' once Alice has redeemed QORT funds
+		if (!atData.getIsFinished())
+			// Not finished yet
+			return;
+
+		// If AT is REFUNDED or CANCELLED then something has gone wrong
+		if (crossChainTradeData.mode == AcctMode.REFUNDED || crossChainTradeData.mode == AcctMode.CANCELLED) {
+			// Alice hasn't redeemed the QORT, so there is no point in trying to redeem the LTC
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_REFUNDED,
+					() -> String.format("AT %s has auto-refunded - trade aborted", tradeBotData.getAtAddress()));
+
+			return;
+		}
+
+		byte[] secretA = LitecoinACCTv3.getInstance().findSecretA(repository, crossChainTradeData);
+		if (secretA == null) {
+			LOGGER.debug(() -> String.format("Unable to find secret-A from redeem message to AT %s?", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		// Use secret-A to redeem P2SH-A
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		byte[] receivingAccountInfo = tradeBotData.getReceivingAccountInfo();
+		int lockTimeA = crossChainTradeData.lockTimeA;
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(crossChainTradeData.partnerForeignPKH, lockTimeA, crossChainTradeData.creatorForeignPKH, crossChainTradeData.hashOfSecretA);
+		String p2shAddressA = litecoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Litecoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(litecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+		switch (htlcStatusA) {
+			case UNFUNDED:
+			case FUNDING_IN_PROGRESS:
+				// P2SH-A suddenly not funded? Our best bet at this point is to hope for AT auto-refund
+				return;
+
+			case REDEEM_IN_PROGRESS:
+			case REDEEMED:
+				// Double-check that we have redeemed P2SH-A...
+				break;
+
+			case REFUND_IN_PROGRESS:
+			case REFUNDED:
+				// Wait for AT to auto-refund
+				return;
+
+			case FUNDED: {
+				Coin redeemAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
+				ECKey redeemKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
+				List<TransactionOutput> fundingOutputs = litecoin.getUnspentOutputs(p2shAddressA);
+
+				Transaction p2shRedeemTransaction = BitcoinyHTLC.buildRedeemTransaction(litecoin.getNetworkParameters(), redeemAmount, redeemKey,
+						fundingOutputs, redeemScriptA, secretA, receivingAccountInfo);
+
+				litecoin.broadcastTransaction(p2shRedeemTransaction);
+				break;
+			}
+		}
+
+		String receivingAddress = litecoin.pkhToAddress(receivingAccountInfo);
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_DONE,
+				() -> String.format("P2SH-A %s redeemed. Funds should arrive at %s", tradeBotData.getAtAddress(), receivingAddress));
+	}
+
+	/**
+	 * Trade-bot is attempting to refund P2SH-A.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleAliceRefundingP2shA(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		int lockTimeA = tradeBotData.getLockTimeA();
+
+		// We can't refund P2SH-A until lockTime-A has passed
+		if (NTP.getTime() <= lockTimeA * 1000L)
+			return;
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		// We can't refund P2SH-A until median block time has passed lockTime-A (see BIP113)
+		int medianBlockTime = litecoin.getMedianBlockTime();
+		if (medianBlockTime <= lockTimeA)
+			return;
+
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeA, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+		String p2shAddressA = litecoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Litecoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(litecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+		switch (htlcStatusA) {
+			case UNFUNDED:
+			case FUNDING_IN_PROGRESS:
+				// Still waiting for P2SH-A to be funded...
+				return;
+
+			case REDEEM_IN_PROGRESS:
+			case REDEEMED:
+				// Too late!
+				TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+						() -> String.format("P2SH-A %s already spent!", p2shAddressA));
+				return;
+
+			case REFUND_IN_PROGRESS:
+			case REFUNDED:
+				break;
+
+			case FUNDED:{
+				Coin refundAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
+				ECKey refundKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
+				List<TransactionOutput> fundingOutputs = litecoin.getUnspentOutputs(p2shAddressA);
+
+				// Determine receive address for refund
+				String receiveAddress = litecoin.getUnusedReceiveAddress(tradeBotData.getForeignKey());
+				Address receiving = Address.fromString(litecoin.getNetworkParameters(), receiveAddress);
+
+				Transaction p2shRefundTransaction = BitcoinyHTLC.buildRefundTransaction(litecoin.getNetworkParameters(), refundAmount, refundKey,
+						fundingOutputs, redeemScriptA, lockTimeA, receiving.getHash());
+
+				litecoin.broadcastTransaction(p2shRefundTransaction);
+				break;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDED,
+				() -> String.format("LockTime-A reached. Refunded P2SH-A %s. Trade aborted", p2shAddressA));
+	}
+
+	/**
+	 * Returns true if Alice finds AT unexpectedly cancelled, refunded, redeemed or locked to someone else.
+	 * <p>
+	 * Will automatically update trade-bot state to <tt>ALICE_REFUNDING_A</tt> or <tt>ALICE_DONE</tt> as necessary.
+	 * 
+	 * @throws DataException
+	 * @throws ForeignBlockchainException
+	 */
+	private boolean aliceUnexpectedState(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// This is OK
+		if (!atData.getIsFinished() && crossChainTradeData.mode == AcctMode.OFFERING)
+			return false;
+
+		boolean isAtLockedToUs = tradeBotData.getTradeNativeAddress().equals(crossChainTradeData.qortalPartnerAddress);
+
+		if (!atData.getIsFinished() && crossChainTradeData.mode == AcctMode.TRADING)
+			if (isAtLockedToUs) {
+				// AT is trading with us - OK
+				return false;
+			} else {
+				TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+						() -> String.format("AT %s trading with someone else: %s. Refunding & aborting trade", tradeBotData.getAtAddress(), crossChainTradeData.qortalPartnerAddress));
+
+				return true;
+			}
+
+		if (atData.getIsFinished() && crossChainTradeData.mode == AcctMode.REDEEMED && isAtLockedToUs) {
+			// We've redeemed already?
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+					() -> String.format("AT %s already redeemed by us. Trade completed", tradeBotData.getAtAddress()));
+		} else {
+			// Any other state is not good, so start defensive refund
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+					() -> String.format("AT %s cancelled/refunded/redeemed by someone else/invalid state. Refunding & aborting trade", tradeBotData.getAtAddress()));
+		}
+
+		return true;
+	}
+
+	private long calcFeeTimestamp(int lockTimeA, int tradeTimeout) {
+		return (lockTimeA - tradeTimeout * 60) * 1000L;
+	}
+
+}

src/main/java/org/qortal/controller/tradebot/TradeBot.java

@@ -0,0 +1,375 @@
+package org.qortal.controller.tradebot;
+
+import java.awt.TrayIcon.MessageType;
+import java.security.SecureRandom;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Random;
+import java.util.concurrent.locks.ReentrantLock;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.apache.logging.log4j.util.Supplier;
+import org.bitcoinj.core.ECKey;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.api.model.crosschain.TradeBotCreateRequest;
+import org.qortal.controller.Controller;
+import org.qortal.controller.tradebot.AcctTradeBot.ResponseResult;
+import org.qortal.crosschain.*;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.data.transaction.BaseTransactionData;
+import org.qortal.data.transaction.PresenceTransactionData;
+import org.qortal.event.Event;
+import org.qortal.event.EventBus;
+import org.qortal.event.Listener;
+import org.qortal.group.Group;
+import org.qortal.gui.SysTray;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.repository.hsqldb.HSQLDBImportExport;
+import org.qortal.settings.Settings;
+import org.qortal.transaction.PresenceTransaction;
+import org.qortal.transaction.PresenceTransaction.PresenceType;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.transaction.TransactionTransformer;
+import org.qortal.utils.NTP;
+
+import com.google.common.primitives.Longs;
+
+/**
+ * Performing cross-chain trading steps on behalf of user.
+ * <p>
+ * We deal with three different independent state-spaces here:
+ * <ul>
+ * 	<li>Qortal blockchain</li>
+ * 	<li>Foreign blockchain</li>
+ * 	<li>Trade-bot entries</li>
+ * </ul>
+ */
+public class TradeBot implements Listener {
+
+	private static final Logger LOGGER = LogManager.getLogger(TradeBot.class);
+	private static final Random RANDOM = new SecureRandom();
+
+	public interface StateNameAndValueSupplier {
+		public String getState();
+		public int getStateValue();
+	}
+
+	public static class StateChangeEvent implements Event {
+		private final TradeBotData tradeBotData;
+
+		public StateChangeEvent(TradeBotData tradeBotData) {
+			this.tradeBotData = tradeBotData;
+		}
+
+		public TradeBotData getTradeBotData() {
+			return this.tradeBotData;
+		}
+	}
+
+	private static final Map<Class<? extends ACCT>, Supplier<AcctTradeBot>> acctTradeBotSuppliers = new HashMap<>();
+	static {
+		acctTradeBotSuppliers.put(BitcoinACCTv1.class, BitcoinACCTv1TradeBot::getInstance);
+		acctTradeBotSuppliers.put(LitecoinACCTv1.class, LitecoinACCTv1TradeBot::getInstance);
+		acctTradeBotSuppliers.put(LitecoinACCTv2.class, LitecoinACCTv2TradeBot::getInstance);
+		acctTradeBotSuppliers.put(LitecoinACCTv3.class, LitecoinACCTv3TradeBot::getInstance);
+		acctTradeBotSuppliers.put(DogecoinACCTv1.class, DogecoinACCTv1TradeBot::getInstance);
+		acctTradeBotSuppliers.put(DogecoinACCTv2.class, DogecoinACCTv2TradeBot::getInstance);
+		acctTradeBotSuppliers.put(DogecoinACCTv3.class, DogecoinACCTv3TradeBot::getInstance);
+	}
+
+	private static TradeBot instance;
+
+	private final Map<String, Long> presenceTimestampsByAtAddress = Collections.synchronizedMap(new HashMap<>());
+
+	private TradeBot() {
+		EventBus.INSTANCE.addListener(event -> TradeBot.getInstance().listen(event));
+	}
+
+	public static synchronized TradeBot getInstance() {
+		if (instance == null)
+			instance = new TradeBot();
+
+		return instance;
+	}
+
+	public ACCT getAcctUsingAtData(ATData atData) {
+		byte[] codeHash = atData.getCodeHash();
+		if (codeHash == null)
+			return null;
+
+		return SupportedBlockchain.getAcctByCodeHash(codeHash);
+	}
+
+	public CrossChainTradeData populateTradeData(Repository repository, ATData atData) throws DataException {
+		ACCT acct = this.getAcctUsingAtData(atData);
+		if (acct == null)
+			return null;
+
+		return acct.populateTradeData(repository, atData);
+	}
+
+	/**
+	 * Creates a new trade-bot entry from the "Bob" viewpoint,
+	 * i.e. OFFERing QORT in exchange for foreign blockchain currency.
+	 * <p>
+	 * Generates:
+	 * <ul>
+	 * 	<li>new 'trade' private key</li>
+	 * 	<li>secret(s)</li>
+	 * </ul>
+	 * Derives:
+	 * <ul>
+	 * 	<li>'native' (as in Qortal) public key, public key hash, address (starting with Q)</li>
+	 * 	<li>'foreign' public key, public key hash</li>
+	 *	<li>hash(es) of secret(s)</li>
+	 * </ul>
+	 * A Qortal AT is then constructed including the following as constants in the 'data segment':
+	 * <ul>
+	 * 	<li>'native' (Qortal) 'trade' address - used to MESSAGE AT</li>
+	 * 	<li>'foreign' public key hash - used by Alice's to allow redeem of currency on foreign blockchain</li>
+	 * 	<li>hash(es) of secret(s) - used by AT (optional) and foreign blockchain as needed</li>
+	 * 	<li>QORT amount on offer by Bob</li>
+	 * 	<li>foreign currency amount expected in return by Bob (from Alice)</li>
+	 * 	<li>trading timeout, in case things go wrong and everyone needs to refund</li>
+	 * </ul>
+	 * Returns a DEPLOY_AT transaction that needs to be signed and broadcast to the Qortal network.
+	 * <p>
+	 * Trade-bot will wait for Bob's AT to be deployed before taking next step.
+	 * <p>
+	 * @param repository
+	 * @param tradeBotCreateRequest
+	 * @return raw, unsigned DEPLOY_AT transaction
+	 * @throws DataException
+	 */
+	public byte[] createTrade(Repository repository, TradeBotCreateRequest tradeBotCreateRequest) throws DataException {
+		// Fetch latest ACCT version for requested foreign blockchain
+		ACCT acct = tradeBotCreateRequest.foreignBlockchain.getLatestAcct();
+
+		AcctTradeBot acctTradeBot = findTradeBotForAcct(acct);
+		if (acctTradeBot == null)
+			return null;
+
+		return acctTradeBot.createTrade(repository, tradeBotCreateRequest);
+	}
+
+	/**
+	 * Creates a trade-bot entry from the 'Alice' viewpoint,
+	 * i.e. matching foreign blockchain currency to an existing QORT offer.
+	 * <p>
+	 * Requires a chosen trade offer from Bob, passed by <tt>crossChainTradeData</tt>
+	 * and access to a foreign blockchain wallet via <tt>foreignKey</tt>.
+	 * <p>
+	 * @param repository
+	 * @param crossChainTradeData chosen trade OFFER that Alice wants to match
+	 * @param foreignKey foreign blockchain wallet key
+	 * @throws DataException
+	 */
+	public ResponseResult startResponse(Repository repository, ATData atData, ACCT acct,
+			CrossChainTradeData crossChainTradeData, String foreignKey, String receivingAddress) throws DataException {
+		AcctTradeBot acctTradeBot = findTradeBotForAcct(acct);
+		if (acctTradeBot == null) {
+			LOGGER.debug(() -> String.format("Couldn't find ACCT trade-bot for AT %s", atData.getATAddress()));
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		// Check Alice doesn't already have an existing, on-going trade-bot entry for this AT.
+		if (repository.getCrossChainRepository().existsTradeWithAtExcludingStates(atData.getATAddress(), acctTradeBot.getEndStates()))
+			return ResponseResult.TRADE_ALREADY_EXISTS;
+
+		return acctTradeBot.startResponse(repository, atData, acct, crossChainTradeData, foreignKey, receivingAddress);
+	}
+
+	public boolean deleteEntry(Repository repository, byte[] tradePrivateKey) throws DataException {
+		TradeBotData tradeBotData = repository.getCrossChainRepository().getTradeBotData(tradePrivateKey);
+		if (tradeBotData == null)
+			// Can't delete what we don't have!
+			return false;
+
+		boolean canDelete = false;
+
+		ACCT acct = SupportedBlockchain.getAcctByName(tradeBotData.getAcctName());
+		if (acct == null)
+			// We can't/no longer support this ACCT
+			canDelete = true;
+		else {
+			AcctTradeBot acctTradeBot = findTradeBotForAcct(acct);
+			canDelete = acctTradeBot == null || acctTradeBot.canDelete(repository, tradeBotData);
+		}
+
+		if (canDelete) {
+			repository.getCrossChainRepository().delete(tradePrivateKey);
+			repository.saveChanges();
+		}
+
+		return canDelete;
+	}
+
+	@Override
+	public void listen(Event event) {
+		if (!(event instanceof Controller.NewBlockEvent))
+			return;
+
+		synchronized (this) {
+			List<TradeBotData> allTradeBotData;
+
+			try (final Repository repository = RepositoryManager.getRepository()) {
+				allTradeBotData = repository.getCrossChainRepository().getAllTradeBotData();
+			} catch (DataException e) {
+				LOGGER.error("Couldn't run trade bot due to repository issue", e);
+				return;
+			}
+
+			for (TradeBotData tradeBotData : allTradeBotData)
+				try (final Repository repository = RepositoryManager.getRepository()) {
+					// Find ACCT-specific trade-bot for this entry
+					ACCT acct = SupportedBlockchain.getAcctByName(tradeBotData.getAcctName());
+					if (acct == null) {
+						LOGGER.debug(() -> String.format("Couldn't find ACCT matching name %s", tradeBotData.getAcctName()));
+						continue;
+					}
+
+					AcctTradeBot acctTradeBot = findTradeBotForAcct(acct);
+					if (acctTradeBot == null) {
+						LOGGER.debug(() -> String.format("Couldn't find ACCT trade-bot matching name %s", tradeBotData.getAcctName()));
+						continue;
+					}
+
+					acctTradeBot.progress(repository, tradeBotData);
+				} catch (DataException e) {
+					LOGGER.error("Couldn't run trade bot due to repository issue", e);
+				} catch (ForeignBlockchainException e) {
+					LOGGER.warn(() -> String.format("Foreign blockchain issue processing trade-bot entry for AT %s: %s", tradeBotData.getAtAddress(), e.getMessage()));
+				}
+		}
+	}
+
+	public static byte[] generateTradePrivateKey() {
+		// The private key is used for both Curve25519 and secp256k1 so needs to be valid for both.
+		// Curve25519 accepts any seed, so generate a valid secp256k1 key and use that.
+		return new ECKey().getPrivKeyBytes();
+	}
+
+	public static byte[] deriveTradeNativePublicKey(byte[] privateKey) {
+		return PrivateKeyAccount.toPublicKey(privateKey);
+	}
+
+	public static byte[] deriveTradeForeignPublicKey(byte[] privateKey) {
+		return ECKey.fromPrivate(privateKey).getPubKey();
+	}
+
+	/*package*/ static byte[] generateSecret() {
+		byte[] secret = new byte[32];
+		RANDOM.nextBytes(secret);
+		return secret;
+	}
+
+	/*package*/ static void backupTradeBotData(Repository repository, List<TradeBotData> additional) {
+		// Attempt to backup the trade bot data. This an optional step and doesn't impact trading, so don't throw an exception on failure
+		try {
+			LOGGER.info("About to backup trade bot data...");
+			HSQLDBImportExport.backupTradeBotStates(repository, additional);
+		} catch (DataException e) {
+			LOGGER.info(String.format("Repository issue when exporting trade bot data: %s", e.getMessage()));
+		}
+	}
+
+	/** Updates trade-bot entry to new state, with current timestamp, logs message and notifies state-change listeners. */
+	/*package*/ static void updateTradeBotState(Repository repository, TradeBotData tradeBotData,
+			String newState, int newStateValue, Supplier<String> logMessageSupplier) throws DataException {
+		tradeBotData.setState(newState);
+		tradeBotData.setStateValue(newStateValue);
+		tradeBotData.setTimestamp(NTP.getTime());
+		repository.getCrossChainRepository().save(tradeBotData);
+		repository.saveChanges();
+
+		if (Settings.getInstance().isTradebotSystrayEnabled())
+			SysTray.getInstance().showMessage("Trade-Bot", String.format("%s: %s", tradeBotData.getAtAddress(), newState), MessageType.INFO);
+
+		if (logMessageSupplier != null)
+			LOGGER.info(logMessageSupplier);
+
+		LOGGER.debug(() -> String.format("new state for trade-bot entry based on AT %s: %s", tradeBotData.getAtAddress(), newState));
+
+		notifyStateChange(tradeBotData);
+	}
+
+	/** Updates trade-bot entry to new state, with current timestamp, logs message and notifies state-change listeners. */
+	/*package*/ static void updateTradeBotState(Repository repository, TradeBotData tradeBotData, StateNameAndValueSupplier newStateSupplier, Supplier<String> logMessageSupplier) throws DataException {
+		updateTradeBotState(repository, tradeBotData, newStateSupplier.getState(), newStateSupplier.getStateValue(), logMessageSupplier);
+	}
+
+	/** Updates trade-bot entry to new state, with current timestamp, logs message and notifies state-change listeners. */
+	/*package*/ static void updateTradeBotState(Repository repository, TradeBotData tradeBotData, Supplier<String> logMessageSupplier) throws DataException {
+		updateTradeBotState(repository, tradeBotData, tradeBotData.getState(), tradeBotData.getStateValue(), logMessageSupplier);
+	}
+
+	/*package*/ static void notifyStateChange(TradeBotData tradeBotData) {
+		StateChangeEvent stateChangeEvent = new StateChangeEvent(tradeBotData);
+		EventBus.INSTANCE.notify(stateChangeEvent);
+	}
+
+	/*package*/ static AcctTradeBot findTradeBotForAcct(ACCT acct) {
+		Supplier<AcctTradeBot> acctTradeBotSupplier = acctTradeBotSuppliers.get(acct.getClass());
+		if (acctTradeBotSupplier == null)
+			return null;
+
+		return acctTradeBotSupplier.get();
+	}
+
+	// PRESENCE-related
+	/*package*/ void updatePresence(Repository repository, TradeBotData tradeBotData, CrossChainTradeData tradeData)
+			throws DataException {
+		String atAddress = tradeBotData.getAtAddress();
+
+		PrivateKeyAccount tradeNativeAccount = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+		String signerAddress = tradeNativeAccount.getAddress();
+
+		/*
+		 * There's no point in Alice trying to build a PRESENCE transaction
+		 * for an AT that isn't locked to her, as other peers won't be able
+		 * to validate the PRESENCE transaction as signing public key won't
+		 * be visible.
+		 */
+		if (!signerAddress.equals(tradeData.qortalCreatorTradeAddress) && !signerAddress.equals(tradeData.qortalPartnerAddress))
+			// Signer is neither Bob, nor Alice, or trade not yet locked to Alice
+			return;
+
+		long now = NTP.getTime();
+		long threshold = now - PresenceType.TRADE_BOT.getLifetime();
+
+		long timestamp = presenceTimestampsByAtAddress.compute(atAddress, (k, v) -> (v == null || v < threshold) ? now : v);
+
+		// If timestamp hasn't been updated then nothing to do
+		if (timestamp != now)
+			return;
+
+		int txGroupId = Group.NO_GROUP;
+		byte[] reference = new byte[TransactionTransformer.SIGNATURE_LENGTH];
+		byte[] creatorPublicKey = tradeNativeAccount.getPublicKey();
+		long fee = 0L;
+
+		BaseTransactionData baseTransactionData = new BaseTransactionData(timestamp, txGroupId, reference, creatorPublicKey, fee, null);
+
+		int nonce = 0;
+		byte[] timestampSignature = tradeNativeAccount.sign(Longs.toByteArray(timestamp));
+
+		PresenceTransactionData transactionData = new PresenceTransactionData(baseTransactionData, nonce, PresenceType.TRADE_BOT, timestampSignature);
+
+		PresenceTransaction presenceTransaction = new PresenceTransaction(repository, transactionData);
+		presenceTransaction.computeNonce();
+
+		presenceTransaction.sign(tradeNativeAccount);
+
+		ValidationResult result = presenceTransaction.importAsUnconfirmed();
+		if (result != ValidationResult.OK)
+			LOGGER.debug(() -> String.format("Unable to build trade-bot PRESENCE transaction for %s: %s", tradeBotData.getAtAddress(), result.name()));
+	}
+
+}

src/main/java/org/qortal/crosschain/ACCT.java

@@ -0,0 +1,25 @@
+package org.qortal.crosschain;
+
+import org.qortal.data.at.ATData;
+import org.qortal.data.at.ATStateData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+
+public interface ACCT {
+
+	public byte[] getCodeBytesHash();
+
+	public int getModeByteOffset();
+
+	public ForeignBlockchain getBlockchain();
+
+	public CrossChainTradeData populateTradeData(Repository repository, ATData atData) throws DataException;
+
+	public CrossChainTradeData populateTradeData(Repository repository, ATStateData atStateData) throws DataException;
+
+	public byte[] buildCancelMessage(String creatorQortalAddress);
+
+	public byte[] findSecretA(Repository repository, CrossChainTradeData crossChainTradeData) throws DataException;
+
+}

src/main/java/org/qortal/crosschain/AcctMode.java

@@ -0,0 +1,21 @@
+package org.qortal.crosschain;
+
+import static java.util.Arrays.stream;
+import static java.util.stream.Collectors.toMap;
+
+import java.util.Map;
+
+public enum AcctMode {
+	OFFERING(0), TRADING(1), CANCELLED(2), REFUNDED(3), REDEEMED(4);
+
+	public final int value;
+	private static final Map<Integer, AcctMode> map = stream(AcctMode.values()).collect(toMap(mode -> mode.value, mode -> mode));
+
+	AcctMode(int value) {
+		this.value = value;
+	}
+
+	public static AcctMode valueOf(int value) {
+		return map.get(value);
+	}
+}

src/main/java/org/qortal/crosschain/BTC.java

@@ -1,559 +0,0 @@
-package org.qortal.crosschain;
-
-import java.util.ArrayList;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Set;
-import java.util.stream.Collectors;
-
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
-import org.bitcoinj.core.Address;
-import org.bitcoinj.core.Coin;
-import org.bitcoinj.core.Context;
-import org.bitcoinj.core.ECKey;
-import org.bitcoinj.core.InsufficientMoneyException;
-import org.bitcoinj.core.LegacyAddress;
-import org.bitcoinj.core.NetworkParameters;
-import org.bitcoinj.core.Sha256Hash;
-import org.bitcoinj.core.Transaction;
-import org.bitcoinj.core.TransactionOutput;
-import org.bitcoinj.core.UTXO;
-import org.bitcoinj.core.UTXOProvider;
-import org.bitcoinj.core.UTXOProviderException;
-import org.bitcoinj.crypto.ChildNumber;
-import org.bitcoinj.crypto.DeterministicHierarchy;
-import org.bitcoinj.crypto.DeterministicKey;
-import org.bitcoinj.params.MainNetParams;
-import org.bitcoinj.params.RegTestParams;
-import org.bitcoinj.params.TestNet3Params;
-import org.bitcoinj.script.Script.ScriptType;
-import org.bitcoinj.script.ScriptBuilder;
-import org.bitcoinj.utils.MonetaryFormat;
-import org.bitcoinj.wallet.DeterministicKeyChain;
-import org.bitcoinj.wallet.SendRequest;
-import org.bitcoinj.wallet.Wallet;
-import org.qortal.crypto.Crypto;
-import org.qortal.settings.Settings;
-import org.qortal.utils.BitTwiddling;
-
-import com.google.common.hash.HashCode;
-
-public class BTC {
-
-	public static final long NO_LOCKTIME_NO_RBF_SEQUENCE = 0xFFFFFFFFL;
-	public static final long LOCKTIME_NO_RBF_SEQUENCE = NO_LOCKTIME_NO_RBF_SEQUENCE - 1;
-	public static final int HASH160_LENGTH = 20;
-
-	public static final boolean INCLUDE_UNCONFIRMED = true;
-	public static final boolean EXCLUDE_UNCONFIRMED = false;
-
-	protected static final Logger LOGGER = LogManager.getLogger(BTC.class);
-
-	// Temporary values until a dynamic fee system is written.
-	private static final long OLD_FEE_AMOUNT = 4_000L; // Not 5000 so that existing P2SH-B can output 1000, avoiding dust issue, leaving 4000 for fees.
-	private static final long NEW_FEE_TIMESTAMP = 1598280000000L; // milliseconds since epoch
-	private static final long NEW_FEE_AMOUNT = 10_000L;
-	private static final long NON_MAINNET_FEE = 1000L; // enough for TESTNET3 and should be OK for REGTEST
-
-	private static final int TIMESTAMP_OFFSET = 4 + 32 + 32;
-	private static final MonetaryFormat FORMAT = new MonetaryFormat().minDecimals(8).postfixCode();
-
-	public enum BitcoinNet {
-		MAIN {
-			@Override
-			public NetworkParameters getParams() {
-				return MainNetParams.get();
-			}
-		},
-		TEST3 {
-			@Override
-			public NetworkParameters getParams() {
-				return TestNet3Params.get();
-			}
-		},
-		REGTEST {
-			@Override
-			public NetworkParameters getParams() {
-				return RegTestParams.get();
-			}
-		};
-
-		public abstract NetworkParameters getParams();
-	}
-
-	private static BTC instance;
-	private final NetworkParameters params;
-	private final ElectrumX electrumX;
-	private final Context bitcoinjContext;
-
-	// Let ECKey.equals() do the hard work
-	private final Set<ECKey> spentKeys = new HashSet<>();
-
-	// Constructors and instance
-
-	private BTC() {
-		BitcoinNet bitcoinNet = Settings.getInstance().getBitcoinNet();
-		this.params = bitcoinNet.getParams();
-
-		LOGGER.info(() -> String.format("Starting Bitcoin support using %s", bitcoinNet.name()));
-
-		this.electrumX = ElectrumX.getInstance(bitcoinNet.name());
-		this.bitcoinjContext = new Context(this.params);
-	}
-
-	public static synchronized BTC getInstance() {
-		if (instance == null)
-			instance = new BTC();
-
-		return instance;
-	}
-
-	// Getters & setters
-
-	public NetworkParameters getNetworkParameters() {
-		return this.params;
-	}
-
-	public static synchronized void resetForTesting() {
-		instance = null;
-	}
-
-	// Actual useful methods for use by other classes
-
-	public static String format(Coin amount) {
-		return BTC.FORMAT.format(amount).toString();
-	}
-
-	public static String format(long amount) {
-		return format(Coin.valueOf(amount));
-	}
-
-	public boolean isValidXprv(String xprv58) {
-		try {
-			Context.propagate(bitcoinjContext);
-			DeterministicKey.deserializeB58(null, xprv58, this.params);
-			return true;
-		} catch (IllegalArgumentException e) {
-			return false;
-		}
-	}
-
-	/** Returns P2PKH Bitcoin address using passed public key hash. */
-	public String pkhToAddress(byte[] publicKeyHash) {
-		Context.propagate(bitcoinjContext);
-		return LegacyAddress.fromPubKeyHash(this.params, publicKeyHash).toString();
-	}
-
-	public String deriveP2shAddress(byte[] redeemScriptBytes) {
-		byte[] redeemScriptHash = Crypto.hash160(redeemScriptBytes);
-		Context.propagate(bitcoinjContext);
-		Address p2shAddress = LegacyAddress.fromScriptHash(params, redeemScriptHash);
-		return p2shAddress.toString();
-	}
-
-	/**
-	 * Returns median timestamp from latest 11 blocks, in seconds.
-	 * <p>
-	 * @throws BitcoinException if error occurs
-	 */
-	public Integer getMedianBlockTime() throws BitcoinException {
-		int height = this.electrumX.getCurrentHeight();
-
-		// Grab latest 11 blocks
-		List<byte[]> blockHeaders = this.electrumX.getBlockHeaders(height - 11, 11);
-		if (blockHeaders.size() < 11)
-			throw new BitcoinException("Not enough blocks to determine median block time");
-
-		List<Integer> blockTimestamps = blockHeaders.stream().map(blockHeader -> BitTwiddling.intFromLEBytes(blockHeader, TIMESTAMP_OFFSET)).collect(Collectors.toList());
-
-		// Descending order
-		blockTimestamps.sort((a, b) -> Integer.compare(b, a));
-
-		// Pick median
-		return blockTimestamps.get(5);
-	}
-
-	/**
-	 * Returns estimated BTC fee, in sats per 1000bytes, optionally for historic timestamp.
-	 * 
-	 * @param timestamp optional milliseconds since epoch, or null for 'now'
-	 * @return sats per 1000bytes, or throws BitcoinException if something went wrong
-	 */
-	public long estimateFee(Long timestamp) throws BitcoinException {
-		if (!this.params.getId().equals(NetworkParameters.ID_MAINNET))
-			return NON_MAINNET_FEE;
-
-		// TODO: This will need to be replaced with something better in the near future!
-		if (timestamp != null && timestamp < NEW_FEE_TIMESTAMP)
-			return OLD_FEE_AMOUNT;
-
-		return NEW_FEE_AMOUNT;
-	}
-
-	/**
-	 * Returns confirmed balance, based on passed payment script.
-	 * <p>
-	 * @return confirmed balance, or zero if script unknown
-	 * @throws BitcoinException if there was an error
-	 */
-	public long getConfirmedBalance(String base58Address) throws BitcoinException {
-		return this.electrumX.getConfirmedBalance(addressToScript(base58Address));
-	}
-
-	/**
-	 * Returns list of unspent outputs pertaining to passed address.
-	 * <p>
-	 * @return list of unspent outputs, or empty list if address unknown
-	 * @throws BitcoinException if there was an error.
-	 */
-	public List<TransactionOutput> getUnspentOutputs(String base58Address) throws BitcoinException {
-		List<UnspentOutput> unspentOutputs = this.electrumX.getUnspentOutputs(addressToScript(base58Address), false);
-
-		List<TransactionOutput> unspentTransactionOutputs = new ArrayList<>();
-		for (UnspentOutput unspentOutput : unspentOutputs) {
-			List<TransactionOutput> transactionOutputs = this.getOutputs(unspentOutput.hash);
-
-			unspentTransactionOutputs.add(transactionOutputs.get(unspentOutput.index));
-		}
-
-		return unspentTransactionOutputs;
-	}
-
-	/**
-	 * Returns list of outputs pertaining to passed transaction hash.
-	 * <p>
-	 * @return list of outputs, or empty list if transaction unknown
-	 * @throws BitcoinException if there was an error.
-	 */
-	public List<TransactionOutput> getOutputs(byte[] txHash) throws BitcoinException {
-		byte[] rawTransactionBytes = this.electrumX.getRawTransaction(txHash);
-
-		// XXX bitcoinj: replace with getTransaction() below
-		Context.propagate(bitcoinjContext);
-		Transaction transaction = new Transaction(this.params, rawTransactionBytes);
-		return transaction.getOutputs();
-	}
-
-	/**
-	 * Returns list of transaction hashes pertaining to passed address.
-	 * <p>
-	 * @return list of unspent outputs, or empty list if script unknown
-	 * @throws BitcoinException if there was an error.
-	 */
-	public List<TransactionHash> getAddressTransactions(String base58Address, boolean includeUnconfirmed) throws BitcoinException {
-		return this.electrumX.getAddressTransactions(addressToScript(base58Address), includeUnconfirmed);
-	}
-
-	/**
-	 * Returns list of raw, confirmed transactions involving given address.
-	 * <p>
-	 * @throws BitcoinException if there was an error
-	 */
-	public List<byte[]> getAddressTransactions(String base58Address) throws BitcoinException {
-		List<TransactionHash> transactionHashes = this.electrumX.getAddressTransactions(addressToScript(base58Address), false);
-
-		List<byte[]> rawTransactions = new ArrayList<>();
-		for (TransactionHash transactionInfo : transactionHashes) {
-			byte[] rawTransaction = this.electrumX.getRawTransaction(HashCode.fromString(transactionInfo.txHash).asBytes());
-			rawTransactions.add(rawTransaction);
-		}
-
-		return rawTransactions;
-	}
-
-	/**
-	 * Returns transaction info for passed transaction hash.
-	 * <p>
-	 * @throws BitcoinException.NotFoundException if transaction unknown
-	 * @throws BitcoinException if error occurs
-	 */
-	public BitcoinTransaction getTransaction(String txHash) throws BitcoinException {
-		return this.electrumX.getTransaction(txHash);
-	}
-
-	/**
-	 * Broadcasts raw transaction to Bitcoin network.
-	 * <p>
-	 * @throws BitcoinException if error occurs
-	 */
-	public void broadcastTransaction(Transaction transaction) throws BitcoinException {
-		this.electrumX.broadcastTransaction(transaction.bitcoinSerialize());
-	}
-
-	/**
-	 * Returns bitcoinj transaction sending <tt>amount</tt> to <tt>recipient</tt>.
-	 * 
-	 * @param xprv58 BIP32 extended Bitcoin private key
-	 * @param recipient P2PKH address
-	 * @param amount unscaled amount
-	 * @return transaction, or null if insufficient funds
-	 */
-	public Transaction buildSpend(String xprv58, String recipient, long amount) {
-		Context.propagate(bitcoinjContext);
-		Wallet wallet = Wallet.fromSpendingKeyB58(this.params, xprv58, DeterministicHierarchy.BIP32_STANDARDISATION_TIME_SECS);
-		wallet.setUTXOProvider(new WalletAwareUTXOProvider(this, wallet, WalletAwareUTXOProvider.KeySearchMode.REQUEST_MORE_IF_ANY_SPENT));
-
-		Address destination = Address.fromString(this.params, recipient);
-		SendRequest sendRequest = SendRequest.to(destination, Coin.valueOf(amount));
-
-		if (this.params == TestNet3Params.get())
-			// Much smaller fee for TestNet3
-			sendRequest.feePerKb = Coin.valueOf(2000L);
-
-		try {
-			wallet.completeTx(sendRequest);
-			return sendRequest.tx;
-		} catch (InsufficientMoneyException e) {
-			return null;
-		}
-	}
-
-	/**
-	 * Returns unspent Bitcoin balance given 'm' BIP32 key.
-	 *
-	 * @param xprv58 BIP32 extended Bitcoin private key
-	 * @return unspent BTC balance, or null if unable to determine balance
-	 */
-	public Long getWalletBalance(String xprv58) {
-		Context.propagate(bitcoinjContext);
-		Wallet wallet = Wallet.fromSpendingKeyB58(this.params, xprv58, DeterministicHierarchy.BIP32_STANDARDISATION_TIME_SECS);
-		wallet.setUTXOProvider(new WalletAwareUTXOProvider(this, wallet, WalletAwareUTXOProvider.KeySearchMode.REQUEST_MORE_IF_ANY_SPENT));
-
-		Coin balance = wallet.getBalance();
-		if (balance == null)
-			return null;
-
-		return balance.value;
-	}
-
-	/**
-	 * Returns first unused receive address given 'm' BIP32 key.
-	 *
-	 * @param xprv58 BIP32 extended Bitcoin private key
-	 * @return Bitcoin P2PKH address
-	 * @throws BitcoinException if something went wrong
-	 */
-	public String getUnusedReceiveAddress(String xprv58) throws BitcoinException {
-		Context.propagate(bitcoinjContext);
-		Wallet wallet = Wallet.fromSpendingKeyB58(this.params, xprv58, DeterministicHierarchy.BIP32_STANDARDISATION_TIME_SECS);
-		DeterministicKeyChain keyChain = wallet.getActiveKeyChain();
-
-		keyChain.setLookaheadSize(WalletAwareUTXOProvider.LOOKAHEAD_INCREMENT);
-		keyChain.maybeLookAhead();
-
-		final int keyChainPathSize = keyChain.getAccountPath().size();
-		List<DeterministicKey> keys = new ArrayList<>(keyChain.getLeafKeys());
-
-		int ki = 0;
-		do {
-			for (; ki < keys.size(); ++ki) {
-				DeterministicKey dKey = keys.get(ki);
-				List<ChildNumber> dKeyPath = dKey.getPath();
-
-				// If keyChain is based on 'm', then make sure dKey is m/0/ki
-				if (dKeyPath.size() != keyChainPathSize + 2 || dKeyPath.get(dKeyPath.size() - 2) != ChildNumber.ZERO)
-					continue;
-
-				// Check unspent
-				Address address = Address.fromKey(this.params, dKey, ScriptType.P2PKH);
-				byte[] script = ScriptBuilder.createOutputScript(address).getProgram();
-
-				List<UnspentOutput> unspentOutputs = this.electrumX.getUnspentOutputs(script, false);
-
-				/*
-				 * If there are no unspent outputs then either:
-				 * a) all the outputs have been spent
-				 * b) address has never been used
-				 * 
-				 * For case (a) we want to remember not to check this address (key) again.
-				 */
-
-				if (unspentOutputs.isEmpty()) {
-					// If this is a known key that has been spent before, then we can skip asking for transaction history
-					if (this.spentKeys.contains(dKey)) {
-						wallet.getActiveKeyChain().markKeyAsUsed((DeterministicKey) dKey);
-						continue;
-					}
-
-					// Ask for transaction history - if it's empty then key has never been used
-					List<TransactionHash> historicTransactionHashes = this.electrumX.getAddressTransactions(script, false);
-
-					if (!historicTransactionHashes.isEmpty()) {
-						// Fully spent key - case (a)
-						this.spentKeys.add(dKey);
-						wallet.getActiveKeyChain().markKeyAsUsed(dKey);
-					} else {
-						// Key never been used - case (b)
-						return address.toString();
-					}
-				}
-
-				// Key has unspent outputs, hence used, so no good to us
-				this.spentKeys.remove(dKey);
-			}
-
-			// Generate some more keys
-			keyChain.setLookaheadSize(keyChain.getLookaheadSize() + WalletAwareUTXOProvider.LOOKAHEAD_INCREMENT);
-			keyChain.maybeLookAhead();
-
-			// This returns all keys, including those already in 'keys'
-			List<DeterministicKey> allLeafKeys = keyChain.getLeafKeys();
-			// Add only new keys onto our list of keys to search
-			List<DeterministicKey> newKeys = allLeafKeys.subList(ki, allLeafKeys.size());
-			keys.addAll(newKeys);
-			// Fall-through to checking more keys as now 'ki' is smaller than 'keys.size()' again
-
-			// Process new keys
-		} while (true);
-	}
-
-	// UTXOProvider support
-
-	static class WalletAwareUTXOProvider implements UTXOProvider {
-		private static final int LOOKAHEAD_INCREMENT = 3;
-
-		private final BTC btc;
-		private final Wallet wallet;
-
-		enum KeySearchMode {
-			REQUEST_MORE_IF_ALL_SPENT, REQUEST_MORE_IF_ANY_SPENT;
-		}
-		private final KeySearchMode keySearchMode;
-		private final DeterministicKeyChain keyChain;
-
-		public WalletAwareUTXOProvider(BTC btc, Wallet wallet, KeySearchMode keySearchMode) {
-			this.btc = btc;
-			this.wallet = wallet;
-			this.keySearchMode = keySearchMode;
-			this.keyChain = this.wallet.getActiveKeyChain();
-
-			// Set up wallet's key chain
-			this.keyChain.setLookaheadSize(LOOKAHEAD_INCREMENT);
-			this.keyChain.maybeLookAhead();
-		}
-
-		public List<UTXO> getOpenTransactionOutputs(List<ECKey> keys) throws UTXOProviderException {
-			List<UTXO> allUnspentOutputs = new ArrayList<>();
-			final boolean coinbase = false;
-
-			int ki = 0;
-			do {
-				boolean areAllKeysUnspent = true;
-				boolean areAllKeysSpent = true;
-
-				for (; ki < keys.size(); ++ki) {
-					ECKey key = keys.get(ki);
-
-					Address address = Address.fromKey(btc.params, key, ScriptType.P2PKH);
-					byte[] script = ScriptBuilder.createOutputScript(address).getProgram();
-
-					List<UnspentOutput> unspentOutputs;
-					try {
-						unspentOutputs = btc.electrumX.getUnspentOutputs(script, false);
-					} catch (BitcoinException e) {
-						throw new UTXOProviderException(String.format("Unable to fetch unspent outputs for %s", address));
-					}
-
-					/*
-					 * If there are no unspent outputs then either:
-					 * a) all the outputs have been spent
-					 * b) address has never been used
-					 * 
-					 * For case (a) we want to remember not to check this address (key) again.
-					 */
-
-					if (unspentOutputs.isEmpty()) {
-						// If this is a known key that has been spent before, then we can skip asking for transaction history
-						if (btc.spentKeys.contains(key)) {
-							wallet.getActiveKeyChain().markKeyAsUsed((DeterministicKey) key);
-							areAllKeysUnspent = false;
-							continue;
-						}
-
-						// Ask for transaction history - if it's empty then key has never been used
-						List<TransactionHash> historicTransactionHashes;
-						try {
-							historicTransactionHashes = btc.electrumX.getAddressTransactions(script, false);
-						} catch (BitcoinException e) {
-							throw new UTXOProviderException(String.format("Unable to fetch transaction history for %s", address));
-						}
-
-						if (!historicTransactionHashes.isEmpty()) {
-							// Fully spent key - case (a)
-							btc.spentKeys.add(key);
-							wallet.getActiveKeyChain().markKeyAsUsed((DeterministicKey) key);
-							areAllKeysUnspent = false;
-						} else {
-							// Key never been used - case (b)
-							areAllKeysSpent = false;
-						}
-
-						continue;
-					}
-
-					// If we reach here, then there's definitely at least one unspent key
-					btc.spentKeys.remove(key);
-					areAllKeysSpent = false;
-
-					for (UnspentOutput unspentOutput : unspentOutputs) {
-						List<TransactionOutput> transactionOutputs;
-						try {
-							transactionOutputs = btc.getOutputs(unspentOutput.hash);
-						} catch (BitcoinException e) {
-							throw new UTXOProviderException(String.format("Unable to fetch outputs for TX %s",
-									HashCode.fromBytes(unspentOutput.hash)));
-						}
-
-						TransactionOutput transactionOutput = transactionOutputs.get(unspentOutput.index);
-
-						UTXO utxo = new UTXO(Sha256Hash.wrap(unspentOutput.hash), unspentOutput.index,
-								Coin.valueOf(unspentOutput.value), unspentOutput.height, coinbase,
-								transactionOutput.getScriptPubKey());
-
-						allUnspentOutputs.add(utxo);
-					}
-				}
-
-				if ((this.keySearchMode == KeySearchMode.REQUEST_MORE_IF_ALL_SPENT && areAllKeysSpent)
-						|| (this.keySearchMode == KeySearchMode.REQUEST_MORE_IF_ANY_SPENT && !areAllKeysUnspent)) {
-					// Generate some more keys
-					this.keyChain.setLookaheadSize(this.keyChain.getLookaheadSize() + LOOKAHEAD_INCREMENT);
-					this.keyChain.maybeLookAhead();
-
-					// This returns all keys, including those already in 'keys'
-					List<DeterministicKey> allLeafKeys = this.keyChain.getLeafKeys();
-					// Add only new keys onto our list of keys to search
-					List<DeterministicKey> newKeys = allLeafKeys.subList(ki, allLeafKeys.size());
-					keys.addAll(newKeys);
-					// Fall-through to checking more keys as now 'ki' is smaller than 'keys.size()' again
-				}
-
-				// If we have processed all keys, then we're done
-			} while (ki < keys.size());
-
-			return allUnspentOutputs;
-		}
-
-		public int getChainHeadHeight() throws UTXOProviderException {
-			try {
-				return btc.electrumX.getCurrentHeight();
-			} catch (BitcoinException e) {
-				throw new UTXOProviderException("Unable to determine Bitcoin chain height");
-			}
-		}
-
-		public NetworkParameters getParams() {
-			return btc.params;
-		}
-	}
-
-	// Utility methods for us
-
-	private byte[] addressToScript(String base58Address) {
-		Context.propagate(bitcoinjContext);
-		Address address = Address.fromString(this.params, base58Address);
-		return ScriptBuilder.createOutputScript(address).getProgram();
-	}
-
-}

src/main/java/org/qortal/crosschain/Bitcoin.java

@@ -0,0 +1,188 @@
+package org.qortal.crosschain;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.EnumMap;
+import java.util.Map;
+
+import org.bitcoinj.core.Context;
+import org.bitcoinj.core.NetworkParameters;
+import org.bitcoinj.params.MainNetParams;
+import org.bitcoinj.params.RegTestParams;
+import org.bitcoinj.params.TestNet3Params;
+import org.qortal.crosschain.ElectrumX.Server;
+import org.qortal.crosschain.ElectrumX.Server.ConnectionType;
+import org.qortal.settings.Settings;
+
+public class Bitcoin extends Bitcoiny {
+
+	public static final String CURRENCY_CODE = "BTC";
+
+	// Temporary values until a dynamic fee system is written.
+	private static final long OLD_FEE_AMOUNT = 4_000L; // Not 5000 so that existing P2SH-B can output 1000, avoiding dust issue, leaving 4000 for fees.
+	private static final long NEW_FEE_TIMESTAMP = 1598280000000L; // milliseconds since epoch
+	private static final long NEW_FEE_AMOUNT = 10_000L;
+
+	private static final long NON_MAINNET_FEE = 1000L; // enough for TESTNET3 and should be OK for REGTEST
+
+	private static final Map<ElectrumX.Server.ConnectionType, Integer> DEFAULT_ELECTRUMX_PORTS = new EnumMap<>(ElectrumX.Server.ConnectionType.class);
+	static {
+		DEFAULT_ELECTRUMX_PORTS.put(ConnectionType.TCP, 50001);
+		DEFAULT_ELECTRUMX_PORTS.put(ConnectionType.SSL, 50002);
+	}
+
+	public enum BitcoinNet {
+		MAIN {
+			@Override
+			public NetworkParameters getParams() {
+				return MainNetParams.get();
+			}
+
+			@Override
+			public Collection<ElectrumX.Server> getServers() {
+				return Arrays.asList(
+						// Servers chosen on NO BASIS WHATSOEVER from various sources!
+						new Server("hodlers.beer", Server.ConnectionType.SSL, 50002),
+						new Server("btc.lastingcoin.net", Server.ConnectionType.SSL, 50002),
+						new Server("electrum.bitaroo.net", Server.ConnectionType.SSL, 50002),
+						new Server("bitcoin.grey.pw", Server.ConnectionType.SSL, 50002),
+						new Server("185.64.116.15", Server.ConnectionType.SSL, 50002),
+						new Server("alviss.coinjoined.com", Server.ConnectionType.SSL, 50002),
+						new Server("btc.litepay.ch", Server.ConnectionType.SSL, 50002),
+						new Server("xtrum.com", Server.ConnectionType.SSL, 50002),
+						new Server("electrum.acinq.co", Server.ConnectionType.SSL, 50002),
+						new Server("caleb.vegas", Server.ConnectionType.SSL, 50002),
+						new Server("electrum.coinext.com.br", Server.ConnectionType.TCP, 50001),
+						new Server("korea.electrum-server.com", Server.ConnectionType.TCP, 50001),
+						new Server("eai.coincited.net", Server.ConnectionType.TCP, 50001),
+						new Server("electrum.coinext.com.br", Server.ConnectionType.SSL, 50002),
+						new Server("node1.btccuracao.com", Server.ConnectionType.SSL, 50002),
+						new Server("korea.electrum-server.com", Server.ConnectionType.SSL, 50002),
+						new Server("btce.iiiiiii.biz", Server.ConnectionType.SSL, 50002),
+						new Server("bitcoin.lukechilds.co", Server.ConnectionType.SSL, 50002),
+						new Server("guichet.centure.cc", Server.ConnectionType.SSL, 50002),
+						new Server("electrumx.hodlwallet.com", Server.ConnectionType.SSL, 50002),
+						new Server("eai.coincited.net", Server.ConnectionType.SSL, 50002),
+						new Server("prospero.bitsrc.net", Server.ConnectionType.SSL, 50002),
+						new Server("gd42.org", Server.ConnectionType.SSL, 50002),
+						new Server("electrum.pabu.io", Server.ConnectionType.SSL, 50002));
+			}
+
+			@Override
+			public String getGenesisHash() {
+				return "000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f";
+			}
+
+			@Override
+			public long getP2shFee(Long timestamp) {
+				// TODO: This will need to be replaced with something better in the near future!
+				if (timestamp != null && timestamp < NEW_FEE_TIMESTAMP)
+					return OLD_FEE_AMOUNT;
+
+				return NEW_FEE_AMOUNT;
+			}
+		},
+		TEST3 {
+			@Override
+			public NetworkParameters getParams() {
+				return TestNet3Params.get();
+			}
+
+			@Override
+			public Collection<ElectrumX.Server> getServers() {
+				return Arrays.asList(
+						new Server("tn.not.fyi", Server.ConnectionType.SSL, 55002),
+						new Server("electrumx-test.1209k.com", Server.ConnectionType.SSL, 50002),
+						new Server("testnet.qtornado.com", Server.ConnectionType.SSL, 51002),
+						new Server("testnet.aranguren.org", Server.ConnectionType.TCP, 51001),
+						new Server("testnet.aranguren.org", Server.ConnectionType.SSL, 51002),
+						new Server("testnet.hsmiths.com", Server.ConnectionType.SSL, 53012));
+			}
+
+			@Override
+			public String getGenesisHash() {
+				return "000000000933ea01ad0ee984209779baaec3ced90fa3f408719526f8d77f4943";
+			}
+
+			@Override
+			public long getP2shFee(Long timestamp) {
+				return NON_MAINNET_FEE;
+			}
+		},
+		REGTEST {
+			@Override
+			public NetworkParameters getParams() {
+				return RegTestParams.get();
+			}
+
+			@Override
+			public Collection<ElectrumX.Server> getServers() {
+				return Arrays.asList(
+						new Server("localhost", Server.ConnectionType.TCP, 50001),
+						new Server("localhost", Server.ConnectionType.SSL, 50002));
+			}
+
+			@Override
+			public String getGenesisHash() {
+				// This is unique to each regtest instance
+				return null;
+			}
+
+			@Override
+			public long getP2shFee(Long timestamp) {
+				return NON_MAINNET_FEE;
+			}
+		};
+
+		public abstract NetworkParameters getParams();
+		public abstract Collection<ElectrumX.Server> getServers();
+		public abstract String getGenesisHash();
+		public abstract long getP2shFee(Long timestamp) throws ForeignBlockchainException;
+	}
+
+	private static Bitcoin instance;
+
+	private final BitcoinNet bitcoinNet;
+
+	// Constructors and instance
+
+	private Bitcoin(BitcoinNet bitcoinNet, BitcoinyBlockchainProvider blockchain, Context bitcoinjContext, String currencyCode) {
+		super(blockchain, bitcoinjContext, currencyCode);
+		this.bitcoinNet = bitcoinNet;
+
+		LOGGER.info(() -> String.format("Starting Bitcoin support using %s", this.bitcoinNet.name()));
+	}
+
+	public static synchronized Bitcoin getInstance() {
+		if (instance == null) {
+			BitcoinNet bitcoinNet = Settings.getInstance().getBitcoinNet();
+
+			BitcoinyBlockchainProvider electrumX = new ElectrumX("Bitcoin-" + bitcoinNet.name(), bitcoinNet.getGenesisHash(), bitcoinNet.getServers(), DEFAULT_ELECTRUMX_PORTS);
+			Context bitcoinjContext = new Context(bitcoinNet.getParams());
+
+			instance = new Bitcoin(bitcoinNet, electrumX, bitcoinjContext, CURRENCY_CODE);
+		}
+
+		return instance;
+	}
+
+	// Getters & setters
+
+	public static synchronized void resetForTesting() {
+		instance = null;
+	}
+
+	// Actual useful methods for use by other classes
+
+	/**
+	 * Returns estimated BTC fee, in sats per 1000bytes, optionally for historic timestamp.
+	 * 
+	 * @param timestamp optional milliseconds since epoch, or null for 'now'
+	 * @return sats per 1000bytes, or throws ForeignBlockchainException if something went wrong
+	 */
+	@Override
+	public long getP2shFee(Long timestamp) throws ForeignBlockchainException {
+		return this.bitcoinNet.getP2shFee(timestamp);
+	}
+
+}

src/main/java/org/qortal/crosschain/BitcoinACCTv1.java

@@ -1,13 +1,10 @@
 package org.qortal.crosschain;
 
-import static java.util.Arrays.stream;
-import static java.util.stream.Collectors.toMap;
 import static org.ciyam.at.OpCode.calcOffset;
 
 import java.nio.ByteBuffer;
 import java.util.Arrays;
 import java.util.List;
-import java.util.Map;
 
 import org.ciyam.at.API;
 import org.ciyam.at.CompilationException;
@@ -101,11 +98,12 @@ import com.google.common.primitives.Bytes;
  * </li>
  * </ul>
  */
-public class BTCACCT {
+public class BitcoinACCTv1 implements ACCT {
+
+	public static final String NAME = BitcoinACCTv1.class.getSimpleName();
+	public static final byte[] CODE_BYTES_HASH = HashCode.fromString("f7f419522a9aaa3c671149878f8c1374dfc59d4fd86ca43ff2a4d913cfbc9e89").asBytes(); // SHA256 of AT code bytes
 
 	public static final int SECRET_LENGTH = 32;
-	public static final int MIN_LOCKTIME = 1500000000;
-	public static final byte[] CODE_BYTES_HASH = HashCode.fromString("f7f419522a9aaa3c671149878f8c1374dfc59d4fd86ca43ff2a4d913cfbc9e89").asBytes(); // SHA256 of AT code bytes
 
 	/** <b>Value</b> offset into AT segment where 'mode' variable (long) is stored. (Multiply by MachineState.VALUE_SIZE for byte offset). */
 	private static final int MODE_VALUE_OFFSET = 68;
@@ -126,22 +124,31 @@ public class BTCACCT {
 	public static final int REDEEM_MESSAGE_LENGTH = 32 /*secret*/ + 32 /*secret*/ + 32 /*partner's Qortal receiving address padded from 25 to 32*/;
 	public static final int CANCEL_MESSAGE_LENGTH = 32 /*AT creator's Qortal address*/;
 
-	public enum Mode {
-		OFFERING(0), TRADING(1), CANCELLED(2), REFUNDED(3), REDEEMED(4);
+	private static BitcoinACCTv1 instance;
 
-		public final int value;
-		private static final Map<Integer, Mode> map = stream(Mode.values()).collect(toMap(mode -> mode.value, mode -> mode));
-
-		Mode(int value) {
-			this.value = value;
-		}
-
-		public static Mode valueOf(int value) {
-			return map.get(value);
-		}
+	private BitcoinACCTv1() {
 	}
 
-	private BTCACCT() {
+	public static synchronized BitcoinACCTv1 getInstance() {
+		if (instance == null)
+			instance = new BitcoinACCTv1();
+
+		return instance;
+	}
+
+	@Override
+	public byte[] getCodeBytesHash() {
+		return CODE_BYTES_HASH;
+	}
+
+	@Override
+	public int getModeByteOffset() {
+		return MODE_BYTE_OFFSET;
+	}
+
+	@Override
+	public ForeignBlockchain getBlockchain() {
+		return Bitcoin.getInstance();
 	}
 
 	/**
@@ -156,7 +163,6 @@ public class BTCACCT {
 	 * @param qortAmount how much QORT to pay trade partner if they send correct 32-byte secrets to AT
 	 * @param bitcoinAmount how much BTC the AT creator is expecting to trade
 	 * @param tradeTimeout suggested timeout for entire trade
-	 * @return
 	 */
 	public static byte[] buildQortalAT(String creatorTradeAddress, byte[] bitcoinPublicKeyHash, byte[] hashOfSecretB, long qortAmount, long bitcoinAmount, int tradeTimeout) {
 		// Labels for data segment addresses
@@ -419,7 +425,7 @@ public class BTCACCT {
 				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrCreatorAddress3, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
 				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrCreatorAddress4, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
 				// Partner address is AT creator's address, so cancel offer and finish.
-				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, Mode.CANCELLED.value));
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.CANCELLED.value));
 				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
 				codeByteBuffer.put(OpCode.FIN_IMD.compile());
 
@@ -470,7 +476,7 @@ public class BTCACCT {
 				codeByteBuffer.put(OpCode.EXT_FUN_RET_DAT_2.compile(FunctionCode.ADD_MINUTES_TO_TIMESTAMP, addrRefundTimestamp, addrLastTxnTimestamp, addrRefundTimeout));
 
 				/* We are in 'trade mode' */
-				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, Mode.TRADING.value));
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.TRADING.value));
 
 				// Set restart position to after this opcode
 				codeByteBuffer.put(OpCode.SET_PCS.compile());
@@ -568,7 +574,7 @@ public class BTCACCT {
 				// Pay AT's balance to receiving address
 				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PAY_TO_ADDRESS_IN_B, addrQortAmount));
 				// Set redeemed mode
-				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, Mode.REDEEMED.value));
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.REDEEMED.value));
 				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
 				codeByteBuffer.put(OpCode.FIN_IMD.compile());
 
@@ -578,7 +584,7 @@ public class BTCACCT {
 				labelRefund = codeByteBuffer.position();
 
 				// Set refunded mode
-				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, Mode.REFUNDED.value));
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.REFUNDED.value));
 				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
 				codeByteBuffer.put(OpCode.FIN_IMD.compile());
 			} catch (CompilationException e) {
@@ -591,7 +597,7 @@ public class BTCACCT {
 		byte[] codeBytes = new byte[codeByteBuffer.limit()];
 		codeByteBuffer.get(codeBytes);
 
-		assert Arrays.equals(Crypto.digest(codeBytes), BTCACCT.CODE_BYTES_HASH)
+		assert Arrays.equals(Crypto.digest(codeBytes), BitcoinACCTv1.CODE_BYTES_HASH)
 			: String.format("BTCACCT.CODE_BYTES_HASH mismatch: expected %s, actual %s", HashCode.fromBytes(CODE_BYTES_HASH), HashCode.fromBytes(Crypto.digest(codeBytes)));
 
 		final short ciyamAtVersion = 2;
@@ -604,41 +610,34 @@ public class BTCACCT {
 
 	/**
 	 * Returns CrossChainTradeData with useful info extracted from AT.
-	 * 
-	 * @param repository
-	 * @param atAddress
-	 * @throws DataException
 	 */
-	public static CrossChainTradeData populateTradeData(Repository repository, ATData atData) throws DataException {
+	@Override
+	public CrossChainTradeData populateTradeData(Repository repository, ATData atData) throws DataException {
 		ATStateData atStateData = repository.getATRepository().getLatestATState(atData.getATAddress());
 		return populateTradeData(repository, atData.getCreatorPublicKey(), atData.getCreation(), atStateData);
 	}
 
 	/**
 	 * Returns CrossChainTradeData with useful info extracted from AT.
-	 * 
-	 * @param repository
-	 * @param atAddress
-	 * @throws DataException
 	 */
-	public static CrossChainTradeData populateTradeData(Repository repository, ATStateData atStateData) throws DataException {
+	@Override
+	public CrossChainTradeData populateTradeData(Repository repository, ATStateData atStateData) throws DataException {
 		ATData atData = repository.getATRepository().fromATAddress(atStateData.getATAddress());
 		return populateTradeData(repository, atData.getCreatorPublicKey(), atData.getCreation(), atStateData);
 	}
 
 	/**
 	 * Returns CrossChainTradeData with useful info extracted from AT.
-	 * 
-	 * @param repository
-	 * @param atAddress
-	 * @throws DataException
 	 */
-	public static CrossChainTradeData populateTradeData(Repository repository, byte[] creatorPublicKey, long creationTimestamp, ATStateData atStateData) throws DataException {
+	public CrossChainTradeData populateTradeData(Repository repository, byte[] creatorPublicKey, long creationTimestamp, ATStateData atStateData) throws DataException {
 		byte[] addressBytes = new byte[25]; // for general use
 		String atAddress = atStateData.getATAddress();
 
 		CrossChainTradeData tradeData = new CrossChainTradeData();
 
+		tradeData.foreignBlockchain = SupportedBlockchain.BITCOIN.name();
+		tradeData.acctName = NAME;
+
 		tradeData.qortalAtAddress = atAddress;
 		tradeData.qortalCreator = Crypto.toAddress(creatorPublicKey);
 		tradeData.creationTimestamp = creationTimestamp;
@@ -658,9 +657,9 @@ public class BTCACCT {
 		dataByteBuffer.position(dataByteBuffer.position() + 32 - addressBytes.length);
 
 		// Creator's Bitcoin/foreign public key hash
-		tradeData.creatorBitcoinPKH = new byte[20];
-		dataByteBuffer.get(tradeData.creatorBitcoinPKH);
-		dataByteBuffer.position(dataByteBuffer.position() + 32 - tradeData.creatorBitcoinPKH.length); // skip to 32 bytes
+		tradeData.creatorForeignPKH = new byte[20];
+		dataByteBuffer.get(tradeData.creatorForeignPKH);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - tradeData.creatorForeignPKH.length); // skip to 32 bytes
 
 		// Hash of secret B
 		tradeData.hashOfSecretB = new byte[20];
@@ -671,7 +670,7 @@ public class BTCACCT {
 		tradeData.qortAmount = dataByteBuffer.getLong();
 
 		// Expected BTC amount
-		tradeData.expectedBitcoin = dataByteBuffer.getLong();
+		tradeData.expectedForeignAmount = dataByteBuffer.getLong();
 
 		// Trade timeout
 		tradeData.tradeTimeout = (int) dataByteBuffer.getLong();
@@ -784,26 +783,28 @@ public class BTCACCT {
 
 		// Trade AT's 'mode'
 		long modeValue = dataByteBuffer.getLong();
-		Mode mode = Mode.valueOf((int) (modeValue & 0xffL));
+		AcctMode acctMode = AcctMode.valueOf((int) (modeValue & 0xffL));
 
 		/* End of variables */
 
-		if (mode != null && mode != Mode.OFFERING) {
-			tradeData.mode = mode;
+		if (acctMode != null && acctMode != AcctMode.OFFERING) {
+			tradeData.mode = acctMode;
 			tradeData.refundTimeout = refundTimeout;
 			tradeData.tradeRefundHeight = new Timestamp(tradeRefundTimestamp).blockHeight;
 			tradeData.qortalPartnerAddress = qortalRecipient;
 			tradeData.hashOfSecretA = hashOfSecretA;
-			tradeData.partnerBitcoinPKH = partnerBitcoinPKH;
+			tradeData.partnerForeignPKH = partnerBitcoinPKH;
 			tradeData.lockTimeA = lockTimeA;
 			tradeData.lockTimeB = lockTimeB;
 
-			if (mode == Mode.REDEEMED)
+			if (acctMode == AcctMode.REDEEMED)
 				tradeData.qortalPartnerReceivingAddress = Base58.encode(partnerReceivingAddress);
 		} else {
-			tradeData.mode = Mode.OFFERING;
+			tradeData.mode = AcctMode.OFFERING;
 		}
 
+		tradeData.duplicateDeprecated();
+
 		return tradeData;
 	}
 
@@ -843,7 +844,8 @@ public class BTCACCT {
 	}
 
 	/** Returns 'cancel' MESSAGE payload for AT creator to cancel trade AT. */
-	public static byte[] buildCancelMessage(String creatorQortalAddress) {
+	@Override
+	public byte[] buildCancelMessage(String creatorQortalAddress) {
 		byte[] data = new byte[CANCEL_MESSAGE_LENGTH];
 		byte[] creatorQortalAddressBytes = Base58.decode(creatorQortalAddress);
 
@@ -866,11 +868,12 @@ public class BTCACCT {
 
 	/** Returns P2SH-B lockTime (epoch seconds) based on trade partner's 'offer' MESSAGE timestamp and P2SH-A locktime. */
 	public static int calcLockTimeB(long offerMessageTimestamp, int lockTimeA) {
-		// lockTimeB is halfway between offerMessageTimesamp and lockTimeA
+		// lockTimeB is halfway between offerMessageTimestamp and lockTimeA
 		return (int) ((lockTimeA + (offerMessageTimestamp / 1000L)) / 2L);
 	}
 
-	public static byte[] findSecretA(Repository repository, CrossChainTradeData crossChainTradeData) throws DataException {
+	@Override
+	public byte[] findSecretA(Repository repository, CrossChainTradeData crossChainTradeData) throws DataException {
 		String atAddress = crossChainTradeData.qortalAtAddress;
 		String redeemerAddress = crossChainTradeData.qortalPartnerAddress;
 

src/main/java/org/qortal/crosschain/BitcoinException.java

@@ -1,57 +0,0 @@
-package org.qortal.crosschain;
-
-@SuppressWarnings("serial")
-public class BitcoinException extends Exception {
-
-	public BitcoinException() {
-		super();
-	}
-
-	public BitcoinException(String message) {
-		super(message);
-	}
-
-	public static class NetworkException extends BitcoinException {
-		private final Integer daemonErrorCode;
-
-		public NetworkException() {
-			super();
-			this.daemonErrorCode = null;
-		}
-
-		public NetworkException(String message) {
-			super(message);
-			this.daemonErrorCode = null;
-		}
-
-		public NetworkException(int errorCode, String message) {
-			super(message);
-			this.daemonErrorCode = errorCode;
-		}
-
-		public Integer getDaemonErrorCode() {
-			return this.daemonErrorCode;
-		}
-	}
-
-	public static class NotFoundException extends BitcoinException {
-		public NotFoundException() {
-			super();
-		}
-
-		public NotFoundException(String message) {
-			super(message);
-		}
-	}
-
-	public static class InsufficientFundsException extends BitcoinException {
-		public InsufficientFundsException() {
-			super();
-		}
-
-		public InsufficientFundsException(String message) {
-			super(message);
-		}
-	}
-
-}

src/main/java/org/qortal/crosschain/BitcoinNetworkProvider.java

@@ -1,31 +0,0 @@
-package org.qortal.crosschain;
-
-import java.util.List;
-
-interface BitcoinNetworkProvider {
-
-	/** Returns current blockchain height. */
-	int getCurrentHeight() throws BitcoinException;
-
-	/** Returns a list of raw block headers, starting at <tt>startHeight</tt> (inclusive), up to <tt>count</tt> max. */
-	List<byte[]> getRawBlockHeaders(int startHeight, int count) throws BitcoinException;
-
-	/** Returns balance of address represented by <tt>scriptPubKey</tt>. */
-	long getConfirmedBalance(byte[] scriptPubKey) throws BitcoinException;
-
-	/** Returns raw, serialized, transaction bytes given <tt>txHash</tt>. */
-	byte[] getRawTransaction(String txHash) throws BitcoinException;
-
-	/** Returns unpacked transaction given <tt>txHash</tt>. */
-	BitcoinTransaction getTransaction(String txHash) throws BitcoinException;
-
-	/** Returns list of transaction hashes (and heights) for address represented by <tt>scriptPubKey</tt>, optionally including unconfirmed transactions. */
-	List<TransactionHash> getAddressTransactions(byte[] scriptPubKey, boolean includeUnconfirmed) throws BitcoinException;
-
-	/** Returns list of unspent transaction outputs for address represented by <tt>scriptPubKey</tt>, optionally including unconfirmed transactions. */
-	List<UnspentOutput> getUnspentOutputs(byte[] scriptPubKey, boolean includeUnconfirmed) throws BitcoinException;
-
-	/** Broadcasts raw, serialized, transaction bytes to network, returning success/failure. */
-	boolean broadcastTransaction(byte[] rawTransaction) throws BitcoinException;
-
-}

src/main/java/org/qortal/crosschain/Bitcoiny.java

@@ -0,0 +1,774 @@
+package org.qortal.crosschain;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.bitcoinj.core.Address;
+import org.bitcoinj.core.AddressFormatException;
+import org.bitcoinj.core.Coin;
+import org.bitcoinj.core.Context;
+import org.bitcoinj.core.ECKey;
+import org.bitcoinj.core.InsufficientMoneyException;
+import org.bitcoinj.core.LegacyAddress;
+import org.bitcoinj.core.NetworkParameters;
+import org.bitcoinj.core.Sha256Hash;
+import org.bitcoinj.core.Transaction;
+import org.bitcoinj.core.TransactionOutput;
+import org.bitcoinj.core.UTXO;
+import org.bitcoinj.core.UTXOProvider;
+import org.bitcoinj.core.UTXOProviderException;
+import org.bitcoinj.crypto.ChildNumber;
+import org.bitcoinj.crypto.DeterministicHierarchy;
+import org.bitcoinj.crypto.DeterministicKey;
+import org.bitcoinj.script.Script.ScriptType;
+import org.bitcoinj.script.ScriptBuilder;
+import org.bitcoinj.wallet.DeterministicKeyChain;
+import org.bitcoinj.wallet.SendRequest;
+import org.bitcoinj.wallet.Wallet;
+import org.qortal.api.model.SimpleForeignTransaction;
+import org.qortal.crypto.Crypto;
+import org.qortal.utils.Amounts;
+import org.qortal.utils.BitTwiddling;
+
+import com.google.common.hash.HashCode;
+
+/** Bitcoin-like (Bitcoin, Litecoin, etc.) support */
+public abstract class Bitcoiny implements ForeignBlockchain {
+
+	protected static final Logger LOGGER = LogManager.getLogger(Bitcoiny.class);
+
+	public static final int HASH160_LENGTH = 20;
+
+	protected final BitcoinyBlockchainProvider blockchain;
+	protected final Context bitcoinjContext;
+	protected final String currencyCode;
+
+	protected final NetworkParameters params;
+
+	/** Keys that have been previously marked as fully spent,<br>
+	 * i.e. keys with transactions but with no unspent outputs. */
+	protected final Set<ECKey> spentKeys = Collections.synchronizedSet(new HashSet<>());
+
+	/** How many bitcoinj wallet keys to generate in each batch. */
+	private static final int WALLET_KEY_LOOKAHEAD_INCREMENT = 3;
+
+	/** Byte offset into raw block headers to block timestamp. */
+	private static final int TIMESTAMP_OFFSET = 4 + 32 + 32;
+
+	// Constructors and instance
+
+	protected Bitcoiny(BitcoinyBlockchainProvider blockchain, Context bitcoinjContext, String currencyCode) {
+		this.blockchain = blockchain;
+		this.bitcoinjContext = bitcoinjContext;
+		this.currencyCode = currencyCode;
+
+		this.params = this.bitcoinjContext.getParams();
+	}
+
+	// Getters & setters
+
+	public BitcoinyBlockchainProvider getBlockchainProvider() {
+		return this.blockchain;
+	}
+
+	public Context getBitcoinjContext() {
+		return this.bitcoinjContext;
+	}
+
+	public String getCurrencyCode() {
+		return this.currencyCode;
+	}
+
+	public NetworkParameters getNetworkParameters() {
+		return this.params;
+	}
+
+	// Interface obligations
+
+	@Override
+	public boolean isValidAddress(String address) {
+		try {
+			ScriptType addressType = Address.fromString(this.params, address).getOutputScriptType();
+
+			return addressType == ScriptType.P2PKH || addressType == ScriptType.P2SH;
+		} catch (AddressFormatException e) {
+			return false;
+		}
+	}
+
+	@Override
+	public boolean isValidWalletKey(String walletKey) {
+		return this.isValidDeterministicKey(walletKey);
+	}
+
+	// Actual useful methods for use by other classes
+
+	public String format(Coin amount) {
+		return this.format(amount.value);
+	}
+
+	public String format(long amount) {
+		return Amounts.prettyAmount(amount) + " " + this.currencyCode;
+	}
+
+	public boolean isValidDeterministicKey(String key58) {
+		try {
+			Context.propagate(this.bitcoinjContext);
+			DeterministicKey.deserializeB58(null, key58, this.params);
+			return true;
+		} catch (IllegalArgumentException e) {
+			return false;
+		}
+	}
+
+	/** Returns P2PKH address using passed public key hash. */
+	public String pkhToAddress(byte[] publicKeyHash) {
+		Context.propagate(this.bitcoinjContext);
+		return LegacyAddress.fromPubKeyHash(this.params, publicKeyHash).toString();
+	}
+
+	/** Returns P2SH address using passed redeem script. */
+	public String deriveP2shAddress(byte[] redeemScriptBytes) {
+		Context.propagate(bitcoinjContext);
+		byte[] redeemScriptHash = Crypto.hash160(redeemScriptBytes);
+		return LegacyAddress.fromScriptHash(this.params, redeemScriptHash).toString();
+	}
+
+	/**
+	 * Returns median timestamp from latest 11 blocks, in seconds.
+	 * <p>
+	 * @throws ForeignBlockchainException if error occurs
+	 */
+	public int getMedianBlockTime() throws ForeignBlockchainException {
+		int height = this.blockchain.getCurrentHeight();
+
+		// Grab latest 11 blocks
+		List<byte[]> blockHeaders = this.blockchain.getRawBlockHeaders(height - 11, 11);
+		if (blockHeaders.size() < 11)
+			throw new ForeignBlockchainException("Not enough blocks to determine median block time");
+
+		List<Integer> blockTimestamps = blockHeaders.stream().map(blockHeader -> BitTwiddling.intFromLEBytes(blockHeader, TIMESTAMP_OFFSET)).collect(Collectors.toList());
+
+		// Descending order
+		blockTimestamps.sort((a, b) -> Integer.compare(b, a));
+
+		// Pick median
+		return blockTimestamps.get(5);
+	}
+
+	/** Returns fee per transaction KB. To be overridden for testnet/regtest. */
+	public Coin getFeePerKb() {
+		return this.bitcoinjContext.getFeePerKb();
+	}
+
+	/** Returns minimum order size in sats. To be overridden for coins that need to restrict order size. */
+	public long getMinimumOrderAmount() {
+		return 0L;
+	}
+
+	/**
+	 * Returns fixed P2SH spending fee, in sats per 1000bytes, optionally for historic timestamp.
+	 *
+	 * @param timestamp optional milliseconds since epoch, or null for 'now'
+	 * @return sats per 1000bytes
+	 * @throws ForeignBlockchainException if something went wrong
+	 */
+	public abstract long getP2shFee(Long timestamp) throws ForeignBlockchainException;
+
+	/**
+	 * Returns confirmed balance, based on passed payment script.
+	 * <p>
+	 * @return confirmed balance, or zero if script unknown
+	 * @throws ForeignBlockchainException if there was an error
+	 */
+	public long getConfirmedBalance(String base58Address) throws ForeignBlockchainException {
+		return this.blockchain.getConfirmedBalance(addressToScriptPubKey(base58Address));
+	}
+
+	/**
+	 * Returns list of unspent outputs pertaining to passed address.
+	 * <p>
+	 * @return list of unspent outputs, or empty list if address unknown
+	 * @throws ForeignBlockchainException if there was an error.
+	 */
+	// TODO: don't return bitcoinj-based objects like TransactionOutput, use BitcoinyTransaction.Output instead
+	public List<TransactionOutput> getUnspentOutputs(String base58Address) throws ForeignBlockchainException {
+		List<UnspentOutput> unspentOutputs = this.blockchain.getUnspentOutputs(addressToScriptPubKey(base58Address), false);
+
+		List<TransactionOutput> unspentTransactionOutputs = new ArrayList<>();
+		for (UnspentOutput unspentOutput : unspentOutputs) {
+			List<TransactionOutput> transactionOutputs = this.getOutputs(unspentOutput.hash);
+
+			unspentTransactionOutputs.add(transactionOutputs.get(unspentOutput.index));
+		}
+
+		return unspentTransactionOutputs;
+	}
+
+	/**
+	 * Returns list of outputs pertaining to passed transaction hash.
+	 * <p>
+	 * @return list of outputs, or empty list if transaction unknown
+	 * @throws ForeignBlockchainException if there was an error.
+	 */
+	// TODO: don't return bitcoinj-based objects like TransactionOutput, use BitcoinyTransaction.Output instead
+	public List<TransactionOutput> getOutputs(byte[] txHash) throws ForeignBlockchainException {
+		byte[] rawTransactionBytes = this.blockchain.getRawTransaction(txHash);
+
+		Context.propagate(bitcoinjContext);
+		Transaction transaction = new Transaction(this.params, rawTransactionBytes);
+		return transaction.getOutputs();
+	}
+
+	/**
+	 * Returns list of transaction hashes pertaining to passed address.
+	 * <p>
+	 * @return list of unspent outputs, or empty list if script unknown
+	 * @throws ForeignBlockchainException if there was an error.
+	 */
+	public List<TransactionHash> getAddressTransactions(String base58Address, boolean includeUnconfirmed) throws ForeignBlockchainException {
+		return this.blockchain.getAddressTransactions(addressToScriptPubKey(base58Address), includeUnconfirmed);
+	}
+
+	/**
+	 * Returns list of raw, confirmed transactions involving given address.
+	 * <p>
+	 * @throws ForeignBlockchainException if there was an error
+	 */
+	public List<byte[]> getAddressTransactions(String base58Address) throws ForeignBlockchainException {
+		List<TransactionHash> transactionHashes = this.blockchain.getAddressTransactions(addressToScriptPubKey(base58Address), false);
+
+		List<byte[]> rawTransactions = new ArrayList<>();
+		for (TransactionHash transactionInfo : transactionHashes) {
+			byte[] rawTransaction = this.blockchain.getRawTransaction(HashCode.fromString(transactionInfo.txHash).asBytes());
+			rawTransactions.add(rawTransaction);
+		}
+
+		return rawTransactions;
+	}
+
+	/**
+	 * Returns transaction info for passed transaction hash.
+	 * <p>
+	 * @throws ForeignBlockchainException.NotFoundException if transaction unknown
+	 * @throws ForeignBlockchainException if error occurs
+	 */
+	public BitcoinyTransaction getTransaction(String txHash) throws ForeignBlockchainException {
+		return this.blockchain.getTransaction(txHash);
+	}
+
+	/**
+	 * Broadcasts raw transaction to network.
+	 * <p>
+	 * @throws ForeignBlockchainException if error occurs
+	 */
+	public void broadcastTransaction(Transaction transaction) throws ForeignBlockchainException {
+		this.blockchain.broadcastTransaction(transaction.bitcoinSerialize());
+	}
+
+	/**
+	 * Returns bitcoinj transaction sending <tt>amount</tt> to <tt>recipient</tt>.
+	 *
+	 * @param xprv58 BIP32 private key
+	 * @param recipient P2PKH address
+	 * @param amount unscaled amount
+	 * @param feePerByte unscaled fee per byte, or null to use default fees
+	 * @return transaction, or null if insufficient funds
+	 */
+	public Transaction buildSpend(String xprv58, String recipient, long amount, Long feePerByte) {
+		Context.propagate(bitcoinjContext);
+
+		Wallet wallet = Wallet.fromSpendingKeyB58(this.params, xprv58, DeterministicHierarchy.BIP32_STANDARDISATION_TIME_SECS);
+		wallet.setUTXOProvider(new WalletAwareUTXOProvider(this, wallet));
+
+		Address destination = Address.fromString(this.params, recipient);
+		SendRequest sendRequest = SendRequest.to(destination, Coin.valueOf(amount));
+
+		if (feePerByte != null)
+			sendRequest.feePerKb = Coin.valueOf(feePerByte * 1000L); // Note: 1000 not 1024
+		else
+			// Allow override of default for TestNet3, etc.
+			sendRequest.feePerKb = this.getFeePerKb();
+
+		try {
+			wallet.completeTx(sendRequest);
+			return sendRequest.tx;
+		} catch (InsufficientMoneyException e) {
+			return null;
+		}
+	}
+
+	/**
+	 * Returns bitcoinj transaction sending <tt>amount</tt> to <tt>recipient</tt> using default fees.
+	 *
+	 * @param xprv58 BIP32 private key
+	 * @param recipient P2PKH address
+	 * @param amount unscaled amount
+	 * @return transaction, or null if insufficient funds
+	 */
+	public Transaction buildSpend(String xprv58, String recipient, long amount) {
+		return buildSpend(xprv58, recipient, amount, null);
+	}
+
+	/**
+	 * Returns unspent Bitcoin balance given 'm' BIP32 key.
+	 *
+	 * @param key58 BIP32/HD extended Bitcoin private/public key
+	 * @return unspent BTC balance, or null if unable to determine balance
+	 */
+	public Long getWalletBalance(String key58) {
+		Context.propagate(bitcoinjContext);
+
+		Wallet wallet = walletFromDeterministicKey58(key58);
+		wallet.setUTXOProvider(new WalletAwareUTXOProvider(this, wallet));
+
+		Coin balance = wallet.getBalance();
+		if (balance == null)
+			return null;
+
+		return balance.value;
+	}
+
+	public List<SimpleTransaction> getWalletTransactions(String key58) throws ForeignBlockchainException {
+		Context.propagate(bitcoinjContext);
+
+		Wallet wallet = walletFromDeterministicKey58(key58);
+		DeterministicKeyChain keyChain = wallet.getActiveKeyChain();
+
+		keyChain.setLookaheadSize(Bitcoiny.WALLET_KEY_LOOKAHEAD_INCREMENT);
+		keyChain.maybeLookAhead();
+
+		List<DeterministicKey> keys = new ArrayList<>(keyChain.getLeafKeys());
+
+		Set<BitcoinyTransaction> walletTransactions = new HashSet<>();
+		Set<String> keySet = new HashSet<>();
+
+		// Set the number of consecutive empty batches required before giving up
+		final int numberOfAdditionalBatchesToSearch = 5;
+
+		int unusedCounter = 0;
+		int ki = 0;
+		do {
+			boolean areAllKeysUnused = true;
+
+			for (; ki < keys.size(); ++ki) {
+				DeterministicKey dKey = keys.get(ki);
+
+				// Check for transactions
+				Address address = Address.fromKey(this.params, dKey, ScriptType.P2PKH);
+				keySet.add(address.toString());
+				byte[] script = ScriptBuilder.createOutputScript(address).getProgram();
+
+				// Ask for transaction history - if it's empty then key has never been used
+				List<TransactionHash> historicTransactionHashes = this.blockchain.getAddressTransactions(script, false);
+
+				if (!historicTransactionHashes.isEmpty()) {
+					areAllKeysUnused = false;
+
+					for (TransactionHash transactionHash : historicTransactionHashes)
+						walletTransactions.add(this.getTransaction(transactionHash.txHash));
+				}
+			}
+
+			if (areAllKeysUnused) {
+				// No transactions
+				if (unusedCounter >= numberOfAdditionalBatchesToSearch) {
+					// ... and we've hit our search limit
+					break;
+				}
+				// We haven't hit our search limit yet so increment the counter and keep looking
+				unusedCounter++;
+			}
+			else {
+				// Some keys in this batch were used, so reset the counter
+				unusedCounter = 0;
+			}
+
+			// Generate some more keys
+			keys.addAll(generateMoreKeys(keyChain));
+
+			// Process new keys
+		} while (true);
+
+		Comparator<SimpleTransaction> newestTimestampFirstComparator = Comparator.comparingInt(SimpleTransaction::getTimestamp).reversed();
+
+		return walletTransactions.stream().map(t -> convertToSimpleTransaction(t, keySet)).sorted(newestTimestampFirstComparator).collect(Collectors.toList());
+	}
+
+	protected SimpleTransaction convertToSimpleTransaction(BitcoinyTransaction t, Set<String> keySet) {
+		long amount = 0;
+		long total = 0L;
+		long totalInputAmount = 0L;
+		long totalOutputAmount = 0L;
+		List<SimpleTransaction.Input> inputs = new ArrayList<>();
+		List<SimpleTransaction.Output> outputs = new ArrayList<>();
+
+		for (BitcoinyTransaction.Input input : t.inputs) {
+			try {
+				BitcoinyTransaction t2 = getTransaction(input.outputTxHash);
+				List<String> senders = t2.outputs.get(input.outputVout).addresses;
+				long inputAmount = t2.outputs.get(input.outputVout).value;
+				totalInputAmount += inputAmount;
+				for (String sender : senders) {
+					boolean addressInWallet = false;
+					if (keySet.contains(sender)) {
+						total += inputAmount;
+						addressInWallet = true;
+					}
+					inputs.add(new SimpleTransaction.Input(sender, inputAmount, addressInWallet));
+				}
+			} catch (ForeignBlockchainException e) {
+				LOGGER.trace("Failed to retrieve transaction information {}", input.outputTxHash);
+			}
+		}
+		if (t.outputs != null && !t.outputs.isEmpty()) {
+			for (BitcoinyTransaction.Output output : t.outputs) {
+				for (String address : output.addresses) {
+					boolean addressInWallet = false;
+					if (keySet.contains(address)) {
+						if (total > 0L) {
+							amount -= (total - output.value);
+						} else {
+							amount += output.value;
+						}
+						addressInWallet = true;
+					}
+					outputs.add(new SimpleTransaction.Output(address, output.value, addressInWallet));
+				}
+				totalOutputAmount += output.value;
+			}
+		}
+		long fee = totalInputAmount - totalOutputAmount;
+		return new SimpleTransaction(t.txHash, t.timestamp, amount, fee, inputs, outputs);
+	}
+
+	/**
+	 * Returns first unused receive address given 'm' BIP32 key.
+	 *
+	 * @param key58 BIP32/HD extended Bitcoin private/public key
+	 * @return P2PKH address
+	 * @throws ForeignBlockchainException if something went wrong
+	 */
+	public String getUnusedReceiveAddress(String key58) throws ForeignBlockchainException {
+		Context.propagate(bitcoinjContext);
+
+		Wallet wallet = walletFromDeterministicKey58(key58);
+		DeterministicKeyChain keyChain = wallet.getActiveKeyChain();
+
+		keyChain.setLookaheadSize(Bitcoiny.WALLET_KEY_LOOKAHEAD_INCREMENT);
+		keyChain.maybeLookAhead();
+
+		final int keyChainPathSize = keyChain.getAccountPath().size();
+		List<DeterministicKey> keys = new ArrayList<>(keyChain.getLeafKeys());
+
+		int ki = 0;
+		do {
+			for (; ki < keys.size(); ++ki) {
+				DeterministicKey dKey = keys.get(ki);
+				List<ChildNumber> dKeyPath = dKey.getPath();
+
+				// If keyChain is based on 'm', then make sure dKey is m/0/ki - i.e. a 'receive' address, not 'change' (m/1/ki)
+				if (dKeyPath.size() != keyChainPathSize + 2 || dKeyPath.get(dKeyPath.size() - 2) != ChildNumber.ZERO)
+					continue;
+
+				// Check unspent
+				Address address = Address.fromKey(this.params, dKey, ScriptType.P2PKH);
+				byte[] script = ScriptBuilder.createOutputScript(address).getProgram();
+
+				List<UnspentOutput> unspentOutputs = this.blockchain.getUnspentOutputs(script, false);
+
+				/*
+				 * If there are no unspent outputs then either:
+				 * a) all the outputs have been spent
+				 * b) address has never been used
+				 *
+				 * For case (a) we want to remember not to check this address (key) again.
+				 */
+
+				if (unspentOutputs.isEmpty()) {
+					// If this is a known key that has been spent before, then we can skip asking for transaction history
+					if (this.spentKeys.contains(dKey)) {
+						wallet.getActiveKeyChain().markKeyAsUsed(dKey);
+						continue;
+					}
+
+					// Ask for transaction history - if it's empty then key has never been used
+					List<TransactionHash> historicTransactionHashes = this.blockchain.getAddressTransactions(script, false);
+
+					if (!historicTransactionHashes.isEmpty()) {
+						// Fully spent key - case (a)
+						this.spentKeys.add(dKey);
+						wallet.getActiveKeyChain().markKeyAsUsed(dKey);
+						continue;
+					}
+
+					// Key never been used - case (b)
+					return address.toString();
+				}
+
+				// Key has unspent outputs, hence used, so no good to us
+				this.spentKeys.remove(dKey);
+			}
+
+			// Generate some more keys
+			keys.addAll(generateMoreKeys(keyChain));
+
+			// Process new keys
+		} while (true);
+	}
+
+	// UTXOProvider support
+
+	static class WalletAwareUTXOProvider implements UTXOProvider {
+		private final Bitcoiny bitcoiny;
+		private final Wallet wallet;
+
+		private final DeterministicKeyChain keyChain;
+
+		public WalletAwareUTXOProvider(Bitcoiny bitcoiny, Wallet wallet) {
+			this.bitcoiny = bitcoiny;
+			this.wallet = wallet;
+			this.keyChain = this.wallet.getActiveKeyChain();
+
+			// Set up wallet's key chain
+			this.keyChain.setLookaheadSize(Bitcoiny.WALLET_KEY_LOOKAHEAD_INCREMENT);
+			this.keyChain.maybeLookAhead();
+		}
+
+		@Override
+		public List<UTXO> getOpenTransactionOutputs(List<ECKey> keys) throws UTXOProviderException {
+			List<UTXO> allUnspentOutputs = new ArrayList<>();
+			final boolean coinbase = false;
+
+			int ki = 0;
+			do {
+				boolean areAllKeysUnspent = true;
+
+				for (; ki < keys.size(); ++ki) {
+					ECKey key = keys.get(ki);
+
+					Address address = Address.fromKey(this.bitcoiny.params, key, ScriptType.P2PKH);
+					byte[] script = ScriptBuilder.createOutputScript(address).getProgram();
+
+					List<UnspentOutput> unspentOutputs;
+					try {
+						unspentOutputs = this.bitcoiny.blockchain.getUnspentOutputs(script, false);
+					} catch (ForeignBlockchainException e) {
+						throw new UTXOProviderException(String.format("Unable to fetch unspent outputs for %s", address));
+					}
+
+					/*
+					 * If there are no unspent outputs then either:
+					 * a) all the outputs have been spent
+					 * b) address has never been used
+					 *
+					 * For case (a) we want to remember not to check this address (key) again.
+					 */
+
+					if (unspentOutputs.isEmpty()) {
+						// If this is a known key that has been spent before, then we can skip asking for transaction history
+						if (this.bitcoiny.spentKeys.contains(key)) {
+							this.wallet.getActiveKeyChain().markKeyAsUsed((DeterministicKey) key);
+							areAllKeysUnspent = false;
+							continue;
+						}
+
+						// Ask for transaction history - if it's empty then key has never been used
+						List<TransactionHash> historicTransactionHashes;
+						try {
+							historicTransactionHashes = this.bitcoiny.blockchain.getAddressTransactions(script, false);
+						} catch (ForeignBlockchainException e) {
+							throw new UTXOProviderException(String.format("Unable to fetch transaction history for %s", address));
+						}
+
+						if (!historicTransactionHashes.isEmpty()) {
+							// Fully spent key - case (a)
+							this.bitcoiny.spentKeys.add(key);
+							this.wallet.getActiveKeyChain().markKeyAsUsed((DeterministicKey) key);
+							areAllKeysUnspent = false;
+						} else {
+							// Key never been used - case (b)
+						}
+
+						continue;
+					}
+
+					// If we reach here, then there's definitely at least one unspent key
+					this.bitcoiny.spentKeys.remove(key);
+
+					for (UnspentOutput unspentOutput : unspentOutputs) {
+						List<TransactionOutput> transactionOutputs;
+						try {
+							transactionOutputs = this.bitcoiny.getOutputs(unspentOutput.hash);
+						} catch (ForeignBlockchainException e) {
+							throw new UTXOProviderException(String.format("Unable to fetch outputs for TX %s",
+									HashCode.fromBytes(unspentOutput.hash)));
+						}
+
+						TransactionOutput transactionOutput = transactionOutputs.get(unspentOutput.index);
+
+						UTXO utxo = new UTXO(Sha256Hash.wrap(unspentOutput.hash), unspentOutput.index,
+								Coin.valueOf(unspentOutput.value), unspentOutput.height, coinbase,
+								transactionOutput.getScriptPubKey());
+
+						allUnspentOutputs.add(utxo);
+					}
+				}
+
+				if (areAllKeysUnspent)
+					// No transactions for this batch of keys so assume we're done searching.
+					return allUnspentOutputs;
+
+				// Generate some more keys
+				keys.addAll(Bitcoiny.generateMoreKeys(this.keyChain));
+
+				// Process new keys
+			} while (true);
+		}
+
+		@Override
+		public int getChainHeadHeight() throws UTXOProviderException {
+			try {
+				return this.bitcoiny.blockchain.getCurrentHeight();
+			} catch (ForeignBlockchainException e) {
+				throw new UTXOProviderException("Unable to determine Bitcoiny chain height");
+			}
+		}
+
+		@Override
+		public NetworkParameters getParams() {
+			return this.bitcoiny.params;
+		}
+	}
+
+	// Utility methods for others
+
+	public static List<SimpleForeignTransaction> simplifyWalletTransactions(List<BitcoinyTransaction> transactions) {
+		// Sort by oldest timestamp first
+		transactions.sort(Comparator.comparingInt(t -> t.timestamp));
+
+		// Manual 2nd-level sort same-timestamp transactions so that a transaction's input comes first
+		int fromIndex = 0;
+		do {
+			int timestamp = transactions.get(fromIndex).timestamp;
+
+			int toIndex;
+			for (toIndex = fromIndex + 1; toIndex < transactions.size(); ++toIndex)
+				if (transactions.get(toIndex).timestamp != timestamp)
+					break;
+
+			// Process same-timestamp sub-list
+			List<BitcoinyTransaction> subList = transactions.subList(fromIndex, toIndex);
+
+			// Only if necessary
+			if (subList.size() > 1) {
+				// Quick index lookup
+				Map<String, Integer> indexByTxHash = subList.stream().collect(Collectors.toMap(t -> t.txHash, t -> t.timestamp));
+
+				int restartIndex = 0;
+				boolean isSorted;
+				do {
+					isSorted = true;
+
+					for (int ourIndex = restartIndex; ourIndex < subList.size(); ++ourIndex) {
+						BitcoinyTransaction ourTx = subList.get(ourIndex);
+
+						for (BitcoinyTransaction.Input input : ourTx.inputs) {
+							Integer inputIndex = indexByTxHash.get(input.outputTxHash);
+
+							if (inputIndex != null && inputIndex > ourIndex) {
+								// Input tx is currently after current tx, so swap
+								BitcoinyTransaction tmpTx = subList.get(inputIndex);
+								subList.set(inputIndex, ourTx);
+								subList.set(ourIndex, tmpTx);
+
+								// Update index lookup too
+								indexByTxHash.put(ourTx.txHash, inputIndex);
+								indexByTxHash.put(tmpTx.txHash, ourIndex);
+
+								if (isSorted)
+									restartIndex = Math.max(restartIndex, ourIndex);
+
+								isSorted = false;
+								break;
+							}
+						}
+					}
+				} while (!isSorted);
+			}
+
+			fromIndex = toIndex;
+		} while (fromIndex < transactions.size());
+
+		// Simplify
+		List<SimpleForeignTransaction> simpleTransactions = new ArrayList<>();
+
+		// Quick lookup of txs in our wallet
+		Set<String> walletTxHashes = transactions.stream().map(t -> t.txHash).collect(Collectors.toSet());
+
+		for (BitcoinyTransaction transaction : transactions) {
+			SimpleForeignTransaction.Builder builder = new SimpleForeignTransaction.Builder();
+			builder.txHash(transaction.txHash);
+			builder.timestamp(transaction.timestamp);
+
+			builder.isSentNotReceived(false);
+
+			for (BitcoinyTransaction.Input input : transaction.inputs) {
+				// TODO: add input via builder
+
+				if (walletTxHashes.contains(input.outputTxHash))
+					builder.isSentNotReceived(true);
+			}
+
+			for (BitcoinyTransaction.Output output : transaction.outputs)
+				builder.output(output.addresses, output.value);
+
+			simpleTransactions.add(builder.build());
+		}
+
+		return simpleTransactions;
+	}
+
+	// Utility methods for us
+
+	protected static List<DeterministicKey> generateMoreKeys(DeterministicKeyChain keyChain) {
+		int existingLeafKeyCount = keyChain.getLeafKeys().size();
+
+		// Increase lookahead size...
+		keyChain.setLookaheadSize(keyChain.getLookaheadSize() + Bitcoiny.WALLET_KEY_LOOKAHEAD_INCREMENT);
+		// ...and lookahead threshold (minimum number of keys to generate)...
+		keyChain.setLookaheadThreshold(0);
+		// ...so that this call will generate more keys
+		keyChain.maybeLookAhead();
+
+		// This returns *all* keys
+		List<DeterministicKey> allLeafKeys = keyChain.getLeafKeys();
+
+		// Only return newly generated keys
+		return allLeafKeys.subList(existingLeafKeyCount, allLeafKeys.size());
+	}
+
+	protected byte[] addressToScriptPubKey(String base58Address) {
+		Context.propagate(this.bitcoinjContext);
+		Address address = Address.fromString(this.params, base58Address);
+		return ScriptBuilder.createOutputScript(address).getProgram();
+	}
+
+	protected Wallet walletFromDeterministicKey58(String key58) {
+		DeterministicKey dKey = DeterministicKey.deserializeB58(null, key58, this.params);
+
+		if (dKey.hasPrivKey())
+			return Wallet.fromSpendingKeyB58(this.params, key58, DeterministicHierarchy.BIP32_STANDARDISATION_TIME_SECS);
+		else
+			return Wallet.fromWatchingKeyB58(this.params, key58, DeterministicHierarchy.BIP32_STANDARDISATION_TIME_SECS);
+	}
+
+}

src/main/java/org/qortal/crosschain/BitcoinyBlockchainProvider.java

@@ -0,0 +1,40 @@
+package org.qortal.crosschain;
+
+import java.util.List;
+
+public abstract class BitcoinyBlockchainProvider {
+
+	public static final boolean INCLUDE_UNCONFIRMED = true;
+	public static final boolean EXCLUDE_UNCONFIRMED = false;
+
+	/** Returns ID unique to bitcoiny network (e.g. "Litecoin-TEST3") */
+	public abstract String getNetId();
+
+	/** Returns current blockchain height. */
+	public abstract int getCurrentHeight() throws ForeignBlockchainException;
+
+	/** Returns a list of raw block headers, starting at <tt>startHeight</tt> (inclusive), up to <tt>count</tt> max. */
+	public abstract List<byte[]> getRawBlockHeaders(int startHeight, int count) throws ForeignBlockchainException;
+
+	/** Returns balance of address represented by <tt>scriptPubKey</tt>. */
+	public abstract long getConfirmedBalance(byte[] scriptPubKey) throws ForeignBlockchainException;
+
+	/** Returns raw, serialized, transaction bytes given <tt>txHash</tt>. */
+	public abstract byte[] getRawTransaction(String txHash) throws ForeignBlockchainException;
+
+	/** Returns raw, serialized, transaction bytes given <tt>txHash</tt>. */
+	public abstract byte[] getRawTransaction(byte[] txHash) throws ForeignBlockchainException;
+
+	/** Returns unpacked transaction given <tt>txHash</tt>. */
+	public abstract BitcoinyTransaction getTransaction(String txHash) throws ForeignBlockchainException;
+
+	/** Returns list of transaction hashes (and heights) for address represented by <tt>scriptPubKey</tt>, optionally including unconfirmed transactions. */
+	public abstract List<TransactionHash> getAddressTransactions(byte[] scriptPubKey, boolean includeUnconfirmed) throws ForeignBlockchainException;
+
+	/** Returns list of unspent transaction outputs for address represented by <tt>scriptPubKey</tt>, optionally including unconfirmed transactions. */
+	public abstract List<UnspentOutput> getUnspentOutputs(byte[] scriptPubKey, boolean includeUnconfirmed) throws ForeignBlockchainException;
+
+	/** Broadcasts raw, serialized, transaction bytes to network, returning success/failure. */
+	public abstract void broadcastTransaction(byte[] rawTransaction) throws ForeignBlockchainException;
+
+}

src/main/java/org/qortal/crosschain/BitcoinyHTLC.java

@@ -4,12 +4,12 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.function.Function;
 
 import org.bitcoinj.core.Address;
-import org.bitcoinj.core.Base58;
 import org.bitcoinj.core.Coin;
 import org.bitcoinj.core.ECKey;
 import org.bitcoinj.core.LegacyAddress;
@@ -24,12 +24,13 @@ import org.bitcoinj.script.ScriptBuilder;
 import org.bitcoinj.script.ScriptChunk;
 import org.bitcoinj.script.ScriptOpCodes;
 import org.qortal.crypto.Crypto;
+import org.qortal.utils.Base58;
 import org.qortal.utils.BitTwiddling;
 
 import com.google.common.hash.HashCode;
 import com.google.common.primitives.Bytes;
 
-public class BTCP2SH {
+public class BitcoinyHTLC {
 
 	public enum Status {
 		UNFUNDED, FUNDING_IN_PROGRESS, FUNDED, REDEEM_IN_PROGRESS, REDEEMED, REFUND_IN_PROGRESS, REFUNDED
@@ -38,6 +39,34 @@ public class BTCP2SH {
 	public static final int SECRET_LENGTH = 32;
 	public static final int MIN_LOCKTIME = 1500000000;
 
+	public static final long NO_LOCKTIME_NO_RBF_SEQUENCE = 0xFFFFFFFFL;
+	public static final long LOCKTIME_NO_RBF_SEQUENCE = NO_LOCKTIME_NO_RBF_SEQUENCE - 1;
+
+	// Assuming node's trade-bot has no more than 100 entries?
+	private static final int MAX_CACHE_ENTRIES = 100;
+
+	// Max time-to-live for cache entries (milliseconds)
+	private static final long CACHE_TIMEOUT = 30_000L;
+
+	@SuppressWarnings("serial")
+	private static final Map<String, byte[]> SECRET_CACHE = new LinkedHashMap<>(MAX_CACHE_ENTRIES + 1, 0.75F, true) {
+		// This method is called just after a new entry has been added
+		@Override
+		public boolean removeEldestEntry(Map.Entry<String, byte[]> eldest) {
+			return size() > MAX_CACHE_ENTRIES;
+		}
+	};
+	private static final byte[] NO_SECRET_CACHE_ENTRY = new byte[0];
+
+	@SuppressWarnings("serial")
+	private static final Map<String, Status> STATUS_CACHE = new LinkedHashMap<>(MAX_CACHE_ENTRIES + 1, 0.75F, true) {
+		// This method is called just after a new entry has been added
+		@Override
+		public boolean removeEldestEntry(Map.Entry<String, Status> eldest) {
+			return size() > MAX_CACHE_ENTRIES;
+		}
+	};
+
 	/*
 	 * OP_TUCK (to copy public key to before signature)
 	 * OP_CHECKSIGVERIFY (sig & pubkey must verify or script fails)
@@ -62,24 +91,24 @@ public class BTCP2SH {
 	private static final byte[] redeemScript5 = HashCode.fromString("8768").asBytes(); // OP_EQUAL OP_ENDIF
 
 	/**
-	 * Returns Bitcoin redeemScript used for cross-chain trading.
+	 * Returns redeemScript used for cross-chain trading.
 	 * <p>
-	 * See comments in {@link BTCP2SH} for more details.
+	 * See comments in {@link BitcoinyHTLC} for more details.
 	 * 
 	 * @param refunderPubKeyHash 20-byte HASH160 of P2SH funder's public key, for refunding purposes
 	 * @param lockTime seconds-since-epoch threshold, after which P2SH funder can claim refund
 	 * @param redeemerPubKeyHash 20-byte HASH160 of P2SH redeemer's public key
-	 * @param secretHash 20-byte HASH160 of secret, used by P2SH redeemer to claim funds
-	 * @return
+	 * @param hashOfSecret 20-byte HASH160 of secret, used by P2SH redeemer to claim funds
 	 */
-	public static byte[] buildScript(byte[] refunderPubKeyHash, int lockTime, byte[] redeemerPubKeyHash, byte[] secretHash) {
+	public static byte[] buildScript(byte[] refunderPubKeyHash, int lockTime, byte[] redeemerPubKeyHash, byte[] hashOfSecret) {
 		return Bytes.concat(redeemScript1, refunderPubKeyHash, redeemScript2, BitTwiddling.toLEByteArray((int) (lockTime & 0xffffffffL)),
-				redeemScript3, redeemerPubKeyHash, redeemScript4, secretHash, redeemScript5);
+				redeemScript3, redeemerPubKeyHash, redeemScript4, hashOfSecret, redeemScript5);
 	}
 
 	/**
-	 * Builds a custom transaction to spend P2SH.
+	 * Builds a custom transaction to spend HTLC P2SH.
 	 * 
+	 * @param params blockchain network parameters
 	 * @param amount output amount, should be total of input amounts, less miner fees
 	 * @param spendKey key for signing transaction, and also where funds are 'sent' (output)
 	 * @param fundingOutput output from transaction that funded P2SH address
@@ -87,12 +116,11 @@ public class BTCP2SH {
 	 * @param lockTime (optional) transaction nLockTime, used in refund scenario
 	 * @param scriptSigBuilder function for building scriptSig using transaction input signature
 	 * @param outputPublicKeyHash PKH used to create P2PKH output
-	 * @return Signed Bitcoin transaction for spending P2SH
+	 * @return Signed transaction for spending P2SH
 	 */
-	public static Transaction buildP2shTransaction(Coin amount, ECKey spendKey, List<TransactionOutput> fundingOutputs, byte[] redeemScriptBytes,
+	public static Transaction buildP2shTransaction(NetworkParameters params, Coin amount, ECKey spendKey,
+			List<TransactionOutput> fundingOutputs, byte[] redeemScriptBytes,
 			Long lockTime, Function<byte[], Script> scriptSigBuilder, byte[] outputPublicKeyHash) {
-		NetworkParameters params = BTC.getInstance().getNetworkParameters();
-
 		Transaction transaction = new Transaction(params);
 		transaction.setVersion(2);
 
@@ -105,9 +133,9 @@ public class BTCP2SH {
 			// Input (without scriptSig prior to signing)
 			TransactionInput input = new TransactionInput(params, null, redeemScriptBytes, fundingOutput.getOutPointFor());
 			if (lockTime != null)
-				input.setSequenceNumber(BTC.LOCKTIME_NO_RBF_SEQUENCE); // Use max-value - 1, so lockTime can be used but not RBF
+				input.setSequenceNumber(LOCKTIME_NO_RBF_SEQUENCE); // Use max-value - 1, so lockTime can be used but not RBF
 			else
-				input.setSequenceNumber(BTC.NO_LOCKTIME_NO_RBF_SEQUENCE); // Use max-value, so no lockTime and no RBF
+				input.setSequenceNumber(NO_LOCKTIME_NO_RBF_SEQUENCE); // Use max-value, so no lockTime and no RBF
 			transaction.addInput(input);
 		}
 
@@ -134,17 +162,19 @@ public class BTCP2SH {
 	}
 
 	/**
-	 * Returns signed Bitcoin transaction claiming refund from P2SH address.
+	 * Returns signed transaction claiming refund from HTLC P2SH.
 	 * 
+	 * @param params blockchain network parameters
 	 * @param refundAmount refund amount, should be total of input amounts, less miner fees
-	 * @param refundKey key for signing transaction, and also where refund is 'sent' (output)
-	 * @param fundingOutput output from transaction that funded P2SH address
+	 * @param refundKey key for signing transaction
+	 * @param fundingOutputs outputs from transaction that funded P2SH address
 	 * @param redeemScriptBytes the redeemScript itself, in byte[] form
 	 * @param lockTime transaction nLockTime - must be at least locktime used in redeemScript
-	 * @param receivingAccountInfo Bitcoin PKH used for output
-	 * @return Signed Bitcoin transaction for refunding P2SH
+	 * @param receivingAccountInfo public-key-hash used for P2PKH output
+	 * @return Signed transaction for refunding P2SH
 	 */
-	public static Transaction buildRefundTransaction(Coin refundAmount, ECKey refundKey, List<TransactionOutput> fundingOutputs, byte[] redeemScriptBytes, long lockTime, byte[] receivingAccountInfo) {
+	public static Transaction buildRefundTransaction(NetworkParameters params, Coin refundAmount, ECKey refundKey,
+			List<TransactionOutput> fundingOutputs, byte[] redeemScriptBytes, long lockTime, byte[] receivingAccountInfo) {
 		Function<byte[], Script> refundSigScriptBuilder = (txSigBytes) -> {
 			// Build scriptSig with...
 			ScriptBuilder scriptBuilder = new ScriptBuilder();
@@ -163,21 +193,23 @@ public class BTCP2SH {
 		};
 
 		// Send funds back to funding address
-		return buildP2shTransaction(refundAmount, refundKey, fundingOutputs, redeemScriptBytes, lockTime, refundSigScriptBuilder, receivingAccountInfo);
+		return buildP2shTransaction(params, refundAmount, refundKey, fundingOutputs, redeemScriptBytes, lockTime, refundSigScriptBuilder, receivingAccountInfo);
 	}
 
 	/**
-	 * Returns signed Bitcoin transaction redeeming funds from P2SH address.
+	 * Returns signed transaction redeeming funds from P2SH address.
 	 * 
+	 * @param params blockchain network parameters
 	 * @param redeemAmount redeem amount, should be total of input amounts, less miner fees
-	 * @param redeemKey key for signing transaction, and also where funds are 'sent' (output)
-	 * @param fundingOutput output from transaction that funded P2SH address
+	 * @param redeemKey key for signing transaction
+	 * @param fundingOutputs outputs from transaction that funded P2SH address
 	 * @param redeemScriptBytes the redeemScript itself, in byte[] form
 	 * @param secret actual 32-byte secret used when building redeemScript
 	 * @param receivingAccountInfo Bitcoin PKH used for output
-	 * @return Signed Bitcoin transaction for redeeming P2SH
+	 * @return Signed transaction for redeeming P2SH
 	 */
-	public static Transaction buildRedeemTransaction(Coin redeemAmount, ECKey redeemKey, List<TransactionOutput> fundingOutputs, byte[] redeemScriptBytes, byte[] secret, byte[] receivingAccountInfo) {
+	public static Transaction buildRedeemTransaction(NetworkParameters params, Coin redeemAmount, ECKey redeemKey,
+			List<TransactionOutput> fundingOutputs, byte[] redeemScriptBytes, byte[] secret, byte[] receivingAccountInfo) {
 		Function<byte[], Script> redeemSigScriptBuilder = (txSigBytes) -> {
 			// Build scriptSig with...
 			ScriptBuilder scriptBuilder = new ScriptBuilder();
@@ -198,17 +230,28 @@ public class BTCP2SH {
 			return scriptBuilder.build();
 		};
 
-		return buildP2shTransaction(redeemAmount, redeemKey, fundingOutputs, redeemScriptBytes, null, redeemSigScriptBuilder, receivingAccountInfo);
+		return buildP2shTransaction(params, redeemAmount, redeemKey, fundingOutputs, redeemScriptBytes, null, redeemSigScriptBuilder, receivingAccountInfo);
 	}
 
-	/** Returns 'secret', if any, given list of raw bitcoin transactions. */
-	public static byte[] findP2shSecret(String p2shAddress, List<byte[]> rawTransactions) {
-		NetworkParameters params = BTC.getInstance().getNetworkParameters();
+	/**
+	 * Returns 'secret', if any, given HTLC's P2SH address.
+	 * <p>
+	 * @throws ForeignBlockchainException
+	 */
+	public static byte[] findHtlcSecret(Bitcoiny bitcoiny, String p2shAddress) throws ForeignBlockchainException {
+		NetworkParameters params = bitcoiny.getNetworkParameters();
+		String compoundKey = String.format("%s-%s-%d", params.getId(), p2shAddress, System.currentTimeMillis() / CACHE_TIMEOUT);
+
+		byte[] secret = SECRET_CACHE.getOrDefault(compoundKey, NO_SECRET_CACHE_ENTRY);
+		if (secret != NO_SECRET_CACHE_ENTRY)
+			return secret;
+
+		List<byte[]> rawTransactions = bitcoiny.getAddressTransactions(p2shAddress);
 
 		for (byte[] rawTransaction : rawTransactions) {
 			Transaction transaction = new Transaction(params, rawTransaction);
 
-			// Cycle through inputs, looking for one that spends our P2SH
+			// Cycle through inputs, looking for one that spends our HTLC
 			for (TransactionInput input : transaction.getInputs()) {
 				Script scriptSig = input.getScriptSig();
 				List<ScriptChunk> scriptChunks = scriptSig.getChunks();
@@ -230,92 +273,115 @@ public class BTCP2SH {
 				Address inputAddress = LegacyAddress.fromScriptHash(params, redeemScriptHash);
 
 				if (!inputAddress.toString().equals(p2shAddress))
-					// Input isn't spending our P2SH
+					// Input isn't spending our HTLC
 					continue;
 
-				byte[] secret = scriptChunks.get(0).data;
-				if (secret.length != BTCP2SH.SECRET_LENGTH)
+				secret = scriptChunks.get(0).data;
+				if (secret.length != BitcoinyHTLC.SECRET_LENGTH)
 					continue;
 
+				// Cache secret for a while
+				SECRET_CACHE.put(compoundKey, secret);
+
 				return secret;
 			}
 		}
 
+		// Cache negative result
+		SECRET_CACHE.put(compoundKey, null);
+
 		return null;
 	}
 
-	/** Returns P2SH status, given P2SH address and expected redeem/refund amount, or throws BitcoinException if error occurs. */
-	public static Status determineP2shStatus(String p2shAddress, long minimumAmount) throws BitcoinException {
-		final BTC btc = BTC.getInstance();
+	/**
+	 * Returns HTLC status, given P2SH address and expected redeem/refund amount
+	 * <p>
+	 * @throws ForeignBlockchainException if error occurs
+	 */
+	public static Status determineHtlcStatus(BitcoinyBlockchainProvider blockchain, String p2shAddress, long minimumAmount) throws ForeignBlockchainException {
+		String compoundKey = String.format("%s-%s-%d", blockchain.getNetId(), p2shAddress, System.currentTimeMillis() / CACHE_TIMEOUT);
 
-		List<TransactionHash> transactionHashes = btc.getAddressTransactions(p2shAddress, BTC.INCLUDE_UNCONFIRMED);
+		Status cachedStatus = STATUS_CACHE.getOrDefault(compoundKey, null);
+		if (cachedStatus != null)
+			return cachedStatus;
+
+		byte[] ourScriptPubKey = addressToScriptPubKey(p2shAddress);
+		List<TransactionHash> transactionHashes = blockchain.getAddressTransactions(ourScriptPubKey, BitcoinyBlockchainProvider.INCLUDE_UNCONFIRMED);
 
 		// Sort by confirmed first, followed by ascending height
 		transactionHashes.sort(TransactionHash.CONFIRMED_FIRST.thenComparing(TransactionHash::getHeight));
 
 		// Transaction cache
-		Map<String, BitcoinTransaction> transactionsByHash = new HashMap<>();
+		Map<String, BitcoinyTransaction> transactionsByHash = new HashMap<>();
 		// HASH160(redeem script) for this p2shAddress
 		byte[] ourRedeemScriptHash = addressToRedeemScriptHash(p2shAddress);
 
 		// Check for spends first, caching full transaction info as we progress just in case we don't return in this loop
 		for (TransactionHash transactionInfo : transactionHashes) {
-			BitcoinTransaction bitcoinTransaction = btc.getTransaction(transactionInfo.txHash);
+			BitcoinyTransaction bitcoinyTransaction = blockchain.getTransaction(transactionInfo.txHash);
 
 			// Cache for possible later reuse
-			transactionsByHash.put(transactionInfo.txHash, bitcoinTransaction);
+			transactionsByHash.put(transactionInfo.txHash, bitcoinyTransaction);
 
 			// Acceptable funding is one transaction output, so we're expecting only one input
-			if (bitcoinTransaction.inputs.size() != 1)
+			if (bitcoinyTransaction.inputs.size() != 1)
 				// Wrong number of inputs
 				continue;
 
-			String scriptSig = bitcoinTransaction.inputs.get(0).scriptSig;
+			String scriptSig = bitcoinyTransaction.inputs.get(0).scriptSig;
 
 			List<byte[]> scriptSigChunks = extractScriptSigChunks(HashCode.fromString(scriptSig).asBytes());
 			if (scriptSigChunks.size() < 3 || scriptSigChunks.size() > 4)
-				// Not spending one of these P2SH
+				// Not valid chunks for our form of HTLC
 				continue;
 
 			// Last chunk is redeem script
 			byte[] redeemScriptBytes = scriptSigChunks.get(scriptSigChunks.size() - 1);
 			byte[] redeemScriptHash = Crypto.hash160(redeemScriptBytes);
 			if (!Arrays.equals(redeemScriptHash, ourRedeemScriptHash))
-				// Not spending our specific P2SH
+				// Not spending our specific HTLC redeem script
 				continue;
 
-			// If we have 4 chunks, then secret is present
-			return scriptSigChunks.size() == 4
-					? (transactionInfo.height == 0 ? Status.REDEEM_IN_PROGRESS : Status.REDEEMED)
-					: (transactionInfo.height == 0 ? Status.REFUND_IN_PROGRESS : Status.REFUNDED);
+			if (scriptSigChunks.size() == 4)
+				// If we have 4 chunks, then secret is present, hence redeem
+				cachedStatus = transactionInfo.height == 0 ? Status.REDEEM_IN_PROGRESS : Status.REDEEMED;
+			else
+				cachedStatus = transactionInfo.height == 0 ? Status.REFUND_IN_PROGRESS : Status.REFUNDED;
+
+			STATUS_CACHE.put(compoundKey, cachedStatus);
+			return cachedStatus;
 		}
 
-		String ourScriptPubKey = HashCode.fromBytes(addressToScriptPubKey(p2shAddress)).toString();
+		String ourScriptPubKeyHex = HashCode.fromBytes(ourScriptPubKey).toString();
 
 		// Check for funding
 		for (TransactionHash transactionInfo : transactionHashes) {
-			BitcoinTransaction bitcoinTransaction = transactionsByHash.get(transactionInfo.txHash);
-			if (bitcoinTransaction == null)
+			BitcoinyTransaction bitcoinyTransaction = transactionsByHash.get(transactionInfo.txHash);
+			if (bitcoinyTransaction == null)
 				// Should be present in map!
-				throw new BitcoinException("Cached Bitcoin transaction now missing?");
+				throw new ForeignBlockchainException("Cached Bitcoin transaction now missing?");
 
 			// Check outputs for our specific P2SH
-			for (BitcoinTransaction.Output output : bitcoinTransaction.outputs) {
+			for (BitcoinyTransaction.Output output : bitcoinyTransaction.outputs) {
 				// Check amount
 				if (output.value < minimumAmount)
 					// Output amount too small (not taking fees into account)
 					continue;
 
-				String scriptPubKey = output.scriptPubKey;
-				if (!scriptPubKey.equals(ourScriptPubKey))
+				String scriptPubKeyHex = output.scriptPubKey;
+				if (!scriptPubKeyHex.equals(ourScriptPubKeyHex))
 					// Not funding our specific P2SH
 					continue;
 
-				return transactionInfo.height == 0 ? Status.FUNDING_IN_PROGRESS : Status.FUNDED;
+				cachedStatus = transactionInfo.height == 0 ? Status.FUNDING_IN_PROGRESS : Status.FUNDED;
+				STATUS_CACHE.put(compoundKey, cachedStatus);
+				return cachedStatus;
 			}
 		}
 
-		return Status.UNFUNDED;
+		cachedStatus = Status.UNFUNDED;
+		STATUS_CACHE.put(compoundKey, cachedStatus);
+		return cachedStatus;
 	}
 
 	private static List<byte[]> extractScriptSigChunks(byte[] scriptSigBytes) {

src/main/java/org/qortal/crosschain/BitcoinyTransaction.java

@@ -3,20 +3,43 @@ package org.qortal.crosschain;
 import java.util.List;
 import java.util.stream.Collectors;
 
-public class BitcoinTransaction {
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.XmlTransient;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class BitcoinyTransaction {
 
 	public final String txHash;
+
+	@XmlTransient
 	public final int size;
+
+	@XmlTransient
 	public final int locktime;
+
 	// Not present if transaction is unconfirmed
 	public final Integer timestamp;
 
 	public static class Input {
+		@XmlTransient
 		public final String scriptSig;
+
+		@XmlTransient
 		public final int sequence;
+
 		public final String outputTxHash;
+
 		public final int outputVout;
 
+		// For JAXB
+		protected Input() {
+			this.scriptSig = null;
+			this.sequence = 0;
+			this.outputTxHash = null;
+			this.outputVout = 0;
+		}
+
 		public Input(String scriptSig, int sequence, String outputTxHash, int outputVout) {
 			this.scriptSig = scriptSig;
 			this.sequence = sequence;
@@ -29,15 +52,34 @@ public class BitcoinTransaction {
 					this.outputTxHash, this.outputVout, this.sequence, this.scriptSig);
 		}
 	}
+	@XmlTransient
 	public final List<Input> inputs;
 
 	public static class Output {
+		@XmlTransient
 		public final String scriptPubKey;
+
 		public final long value;
 
+		public final List<String> addresses;
+
+		// For JAXB
+		protected Output() {
+			this.scriptPubKey = null;
+			this.value = 0;
+			this.addresses = null;
+		}
+
 		public Output(String scriptPubKey, long value) {
 			this.scriptPubKey = scriptPubKey;
 			this.value = value;
+			this.addresses = null;
+		}
+
+		public Output(String scriptPubKey, long value, List<String> addresses) {
+			this.scriptPubKey = scriptPubKey;
+			this.value = value;
+			this.addresses = addresses;
 		}
 
 		public String toString() {
@@ -46,7 +88,20 @@ public class BitcoinTransaction {
 	}
 	public final List<Output> outputs;
 
-	public BitcoinTransaction(String txHash, int size, int locktime, Integer timestamp,
+	public final long totalAmount;
+
+	// For JAXB
+	protected BitcoinyTransaction() {
+		this.txHash = null;
+		this.size = 0;
+		this.locktime = 0;
+		this.timestamp = 0;
+		this.inputs = null;
+		this.outputs = null;
+		this.totalAmount = 0;
+	}
+
+	public BitcoinyTransaction(String txHash, int size, int locktime, Integer timestamp,
 			List<Input> inputs, List<Output> outputs) {
 		this.txHash = txHash;
 		this.size = size;
@@ -54,6 +109,8 @@ public class BitcoinTransaction {
 		this.timestamp = timestamp;
 		this.inputs = inputs;
 		this.outputs = outputs;
+
+		this.totalAmount = outputs.stream().map(output -> output.value).reduce(0L, Long::sum);
 	}
 
 	public String toString() {
@@ -67,4 +124,23 @@ public class BitcoinTransaction {
 				this.inputs.stream().map(Input::toString).collect(Collectors.joining(",\n\t\t")),
 				this.outputs.stream().map(Output::toString).collect(Collectors.joining(",\n\t\t")));
 	}
+
+	@Override
+	public boolean equals(Object other) {
+		if (other == this)
+			return true;
+
+		if (!(other instanceof BitcoinyTransaction))
+			return false;
+
+		BitcoinyTransaction otherTransaction = (BitcoinyTransaction) other;
+
+		return this.txHash.equals(otherTransaction.txHash);
+	}
+
+	@Override
+	public int hashCode() {
+		return this.txHash.hashCode();
+	}
+
 }

src/main/java/org/qortal/crosschain/Dogecoin.java

@@ -0,0 +1,171 @@
+package org.qortal.crosschain;
+
+import org.bitcoinj.core.Coin;
+import org.bitcoinj.core.Context;
+import org.bitcoinj.core.NetworkParameters;
+import org.libdohj.params.DogecoinMainNetParams;
+//import org.libdohj.params.DogecoinRegTestParams;
+import org.libdohj.params.DogecoinTestNet3Params;
+import org.qortal.crosschain.ElectrumX.Server;
+import org.qortal.crosschain.ElectrumX.Server.ConnectionType;
+import org.qortal.settings.Settings;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.EnumMap;
+import java.util.Map;
+
+public class Dogecoin extends Bitcoiny {
+
+	public static final String CURRENCY_CODE = "DOGE";
+
+	private static final Coin DEFAULT_FEE_PER_KB = Coin.valueOf(500000000); // 5 DOGE per 1000 bytes
+
+	private static final long MINIMUM_ORDER_AMOUNT = 300000000L; // 3 DOGE minimum order. The RPC dust threshold is around 2 DOGE
+
+	// Temporary values until a dynamic fee system is written.
+	private static final long MAINNET_FEE = 110000000L;
+	private static final long NON_MAINNET_FEE = 10000L; // TODO: calibrate this
+
+	private static final Map<ConnectionType, Integer> DEFAULT_ELECTRUMX_PORTS = new EnumMap<>(ConnectionType.class);
+	static {
+		DEFAULT_ELECTRUMX_PORTS.put(ConnectionType.TCP, 50001);
+		DEFAULT_ELECTRUMX_PORTS.put(ConnectionType.SSL, 50002);
+	}
+
+	public enum DogecoinNet {
+		MAIN {
+			@Override
+			public NetworkParameters getParams() {
+				return DogecoinMainNetParams.get();
+			}
+
+			@Override
+			public Collection<Server> getServers() {
+				return Arrays.asList(
+						// Servers chosen on NO BASIS WHATSOEVER from various sources!
+						new Server("electrum1.cipig.net", ConnectionType.TCP, 10060),
+						new Server("electrum2.cipig.net", ConnectionType.TCP, 10060),
+						new Server("electrum3.cipig.net", ConnectionType.TCP, 10060));
+						// TODO: add more mainnet servers. It's too centralized.
+			}
+
+			@Override
+			public String getGenesisHash() {
+				return "1a91e3dace36e2be3bf030a65679fe821aa1d6ef92e7c9902eb318182c355691";
+			}
+
+			@Override
+			public long getP2shFee(Long timestamp) {
+				// TODO: This will need to be replaced with something better in the near future!
+				return MAINNET_FEE;
+			}
+		},
+		TEST3 {
+			@Override
+			public NetworkParameters getParams() {
+				return DogecoinTestNet3Params.get();
+			}
+
+			@Override
+			public Collection<Server> getServers() {
+				return Arrays.asList(); // TODO: find testnet servers
+			}
+
+			@Override
+			public String getGenesisHash() {
+				return "4966625a4b2851d9fdee139e56211a0d88575f59ed816ff5e6a63deb4e3e29a0";
+			}
+
+			@Override
+			public long getP2shFee(Long timestamp) {
+				return NON_MAINNET_FEE;
+			}
+		},
+		REGTEST {
+			@Override
+			public NetworkParameters getParams() {
+				return null; // TODO: DogecoinRegTestParams.get();
+			}
+
+			@Override
+			public Collection<Server> getServers() {
+				return Arrays.asList(
+						new Server("localhost", ConnectionType.TCP, 50001),
+						new Server("localhost", ConnectionType.SSL, 50002));
+			}
+
+			@Override
+			public String getGenesisHash() {
+				// This is unique to each regtest instance
+				return null;
+			}
+
+			@Override
+			public long getP2shFee(Long timestamp) {
+				return NON_MAINNET_FEE;
+			}
+		};
+
+		public abstract NetworkParameters getParams();
+		public abstract Collection<Server> getServers();
+		public abstract String getGenesisHash();
+		public abstract long getP2shFee(Long timestamp) throws ForeignBlockchainException;
+	}
+
+	private static Dogecoin instance;
+
+	private final DogecoinNet dogecoinNet;
+
+	// Constructors and instance
+
+	private Dogecoin(DogecoinNet dogecoinNet, BitcoinyBlockchainProvider blockchain, Context bitcoinjContext, String currencyCode) {
+		super(blockchain, bitcoinjContext, currencyCode);
+		this.dogecoinNet = dogecoinNet;
+
+		LOGGER.info(() -> String.format("Starting Dogecoin support using %s", this.dogecoinNet.name()));
+	}
+
+	public static synchronized Dogecoin getInstance() {
+		if (instance == null) {
+			DogecoinNet dogecoinNet = Settings.getInstance().getDogecoinNet();
+
+			BitcoinyBlockchainProvider electrumX = new ElectrumX("Dogecoin-" + dogecoinNet.name(), dogecoinNet.getGenesisHash(), dogecoinNet.getServers(), DEFAULT_ELECTRUMX_PORTS);
+			Context bitcoinjContext = new Context(dogecoinNet.getParams());
+
+			instance = new Dogecoin(dogecoinNet, electrumX, bitcoinjContext, CURRENCY_CODE);
+		}
+
+		return instance;
+	}
+
+	// Getters & setters
+
+	public static synchronized void resetForTesting() {
+		instance = null;
+	}
+
+	// Actual useful methods for use by other classes
+
+	@Override
+	public Coin getFeePerKb() {
+		return DEFAULT_FEE_PER_KB;
+	}
+
+	@Override
+	public long getMinimumOrderAmount() {
+		return MINIMUM_ORDER_AMOUNT;
+	}
+
+	/**
+	 * Returns estimated DOGE fee, in sats per 1000bytes, optionally for historic timestamp.
+	 * 
+	 * @param timestamp optional milliseconds since epoch, or null for 'now'
+	 * @return sats per 1000bytes, or throws ForeignBlockchainException if something went wrong
+	 */
+	@Override
+	public long getP2shFee(Long timestamp) throws ForeignBlockchainException {
+		return this.dogecoinNet.getP2shFee(timestamp);
+	}
+
+}

src/main/java/org/qortal/crosschain/DogecoinACCTv1.java

@@ -0,0 +1,855 @@
+package org.qortal.crosschain;
+
+import com.google.common.hash.HashCode;
+import com.google.common.primitives.Bytes;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.ciyam.at.*;
+import org.qortal.account.Account;
+import org.qortal.asset.Asset;
+import org.qortal.at.QortalFunctionCode;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.at.ATStateData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.utils.Base58;
+import org.qortal.utils.BitTwiddling;
+
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.List;
+
+import static org.ciyam.at.OpCode.calcOffset;
+
+/**
+ * Cross-chain trade AT
+ * 
+ * <p>
+ * <ul>
+ * <li>Bob generates Dogecoin & Qortal 'trade' keys
+ * 		<ul>
+ * 			<li>private key required to sign P2SH redeem tx</li>
+ * 			<li>private key could be used to create 'secret' (e.g. double-SHA256)</li>
+ * 			<li>encrypted private key could be stored in Qortal AT for access by Bob from any node</li>
+ * 		</ul>
+ * </li>
+ * <li>Bob deploys Qortal AT
+ * 		<ul>
+ * 		</ul>
+ * </li>
+ * <li>Alice finds Qortal AT and wants to trade
+ * 		<ul>
+ * 			<li>Alice generates Dogecoin & Qortal 'trade' keys</li>
+ * 			<li>Alice funds Dogecoin P2SH-A</li>
+ * 			<li>Alice sends 'offer' MESSAGE to Bob from her Qortal trade address, containing:
+ * 				<ul>
+ * 					<li>hash-of-secret-A</li>
+ * 					<li>her 'trade' Dogecoin PKH</li>
+ * 				</ul>
+ * 			</li>
+ * 		</ul>
+ * </li>
+ * <li>Bob receives "offer" MESSAGE
+ * 		<ul>
+ * 			<li>Checks Alice's P2SH-A</li>
+ * 			<li>Sends 'trade' MESSAGE to Qortal AT from his trade address, containing:
+ * 				<ul>
+ * 					<li>Alice's trade Qortal address</li>
+ * 					<li>Alice's trade Dogecoin PKH</li>
+ * 					<li>hash-of-secret-A</li>
+ * 				</ul>
+ * 			</li>
+ * 		</ul>
+ * </li>
+ * <li>Alice checks Qortal AT to confirm it's locked to her
+ * 		<ul>
+ * 			<li>Alice sends 'redeem' MESSAGE to Qortal AT from her trade address, containing:
+ * 				<ul>
+ * 					<li>secret-A</li>
+ * 					<li>Qortal receiving address of her chosing</li>
+ * 				</ul>
+ * 			</li>
+ * 			<li>AT's QORT funds are sent to Qortal receiving address</li>
+ * 		</ul>
+ * </li>
+ * <li>Bob checks AT, extracts secret-A
+ * 		<ul>
+ * 			<li>Bob redeems P2SH-A using his Dogecoin trade key and secret-A</li>
+ * 			<li>P2SH-A DOGE funds end up at Dogecoin address determined by redeem transaction output(s)</li>
+ * 		</ul>
+ * </li>
+ * </ul>
+ */
+public class DogecoinACCTv1 implements ACCT {
+
+	private static final Logger LOGGER = LogManager.getLogger(DogecoinACCTv1.class);
+
+	public static final String NAME = DogecoinACCTv1.class.getSimpleName();
+	public static final byte[] CODE_BYTES_HASH = HashCode.fromString("0eb49b0313ff3855a29d860c2a8203faa2ef62e28ea30459321f176079cfa3a5").asBytes(); // SHA256 of AT code bytes
+
+	public static final int SECRET_LENGTH = 32;
+
+	/** <b>Value</b> offset into AT segment where 'mode' variable (long) is stored. (Multiply by MachineState.VALUE_SIZE for byte offset). */
+	private static final int MODE_VALUE_OFFSET = 61;
+	/** <b>Byte</b> offset into AT state data where 'mode' variable (long) is stored. */
+	public static final int MODE_BYTE_OFFSET = MachineState.HEADER_LENGTH + (MODE_VALUE_OFFSET * MachineState.VALUE_SIZE);
+
+	public static class OfferMessageData {
+		public byte[] partnerDogecoinPKH;
+		public byte[] hashOfSecretA;
+		public long lockTimeA;
+	}
+	public static final int OFFER_MESSAGE_LENGTH = 20 /*partnerDogecoinPKH*/ + 20 /*hashOfSecretA*/ + 8 /*lockTimeA*/;
+	public static final int TRADE_MESSAGE_LENGTH = 32 /*partner's Qortal trade address (padded from 25 to 32)*/
+			+ 24 /*partner's Dogecoin PKH (padded from 20 to 24)*/
+			+ 8 /*AT trade timeout (minutes)*/
+			+ 24 /*hash of secret-A (padded from 20 to 24)*/
+			+ 8 /*lockTimeA*/;
+	public static final int REDEEM_MESSAGE_LENGTH = 32 /*secret-A*/ + 32 /*partner's Qortal receiving address padded from 25 to 32*/;
+	public static final int CANCEL_MESSAGE_LENGTH = 32 /*AT creator's Qortal address*/;
+
+	private static DogecoinACCTv1 instance;
+
+	private DogecoinACCTv1() {
+	}
+
+	public static synchronized DogecoinACCTv1 getInstance() {
+		if (instance == null)
+			instance = new DogecoinACCTv1();
+
+		return instance;
+	}
+
+	@Override
+	public byte[] getCodeBytesHash() {
+		return CODE_BYTES_HASH;
+	}
+
+	@Override
+	public int getModeByteOffset() {
+		return MODE_BYTE_OFFSET;
+	}
+
+	@Override
+	public ForeignBlockchain getBlockchain() {
+		return Dogecoin.getInstance();
+	}
+
+	/**
+	 * Returns Qortal AT creation bytes for cross-chain trading AT.
+	 * <p>
+	 * <tt>tradeTimeout</tt> (minutes) is the time window for the trade partner to send the
+	 * 32-byte secret to the AT, before the AT automatically refunds the AT's creator.
+	 * 
+	 * @param creatorTradeAddress AT creator's trade Qortal address
+	 * @param dogecoinPublicKeyHash 20-byte HASH160 of creator's trade Dogecoin public key
+	 * @param qortAmount how much QORT to pay trade partner if they send correct 32-byte secrets to AT
+	 * @param dogecoinAmount how much DOGE the AT creator is expecting to trade
+	 * @param tradeTimeout suggested timeout for entire trade
+	 */
+	public static byte[] buildQortalAT(String creatorTradeAddress, byte[] dogecoinPublicKeyHash, long qortAmount, long dogecoinAmount, int tradeTimeout) {
+		if (dogecoinPublicKeyHash.length != 20)
+			throw new IllegalArgumentException("Dogecoin public key hash should be 20 bytes");
+
+		// Labels for data segment addresses
+		int addrCounter = 0;
+
+		// Constants (with corresponding dataByteBuffer.put*() calls below)
+
+		final int addrCreatorTradeAddress1 = addrCounter++;
+		final int addrCreatorTradeAddress2 = addrCounter++;
+		final int addrCreatorTradeAddress3 = addrCounter++;
+		final int addrCreatorTradeAddress4 = addrCounter++;
+
+		final int addrDogecoinPublicKeyHash = addrCounter;
+		addrCounter += 4;
+
+		final int addrQortAmount = addrCounter++;
+		final int addrDogecoinAmount = addrCounter++;
+		final int addrTradeTimeout = addrCounter++;
+
+		final int addrMessageTxnType = addrCounter++;
+		final int addrExpectedTradeMessageLength = addrCounter++;
+		final int addrExpectedRedeemMessageLength = addrCounter++;
+
+		final int addrCreatorAddressPointer = addrCounter++;
+		final int addrQortalPartnerAddressPointer = addrCounter++;
+		final int addrMessageSenderPointer = addrCounter++;
+
+		final int addrTradeMessagePartnerDogecoinPKHOffset = addrCounter++;
+		final int addrPartnerDogecoinPKHPointer = addrCounter++;
+		final int addrTradeMessageHashOfSecretAOffset = addrCounter++;
+		final int addrHashOfSecretAPointer = addrCounter++;
+
+		final int addrRedeemMessageReceivingAddressOffset = addrCounter++;
+
+		final int addrMessageDataPointer = addrCounter++;
+		final int addrMessageDataLength = addrCounter++;
+
+		final int addrPartnerReceivingAddressPointer = addrCounter++;
+
+		final int addrEndOfConstants = addrCounter;
+
+		// Variables
+
+		final int addrCreatorAddress1 = addrCounter++;
+		final int addrCreatorAddress2 = addrCounter++;
+		final int addrCreatorAddress3 = addrCounter++;
+		final int addrCreatorAddress4 = addrCounter++;
+
+		final int addrQortalPartnerAddress1 = addrCounter++;
+		final int addrQortalPartnerAddress2 = addrCounter++;
+		final int addrQortalPartnerAddress3 = addrCounter++;
+		final int addrQortalPartnerAddress4 = addrCounter++;
+
+		final int addrLockTimeA = addrCounter++;
+		final int addrRefundTimeout = addrCounter++;
+		final int addrRefundTimestamp = addrCounter++;
+		final int addrLastTxnTimestamp = addrCounter++;
+		final int addrBlockTimestamp = addrCounter++;
+		final int addrTxnType = addrCounter++;
+		final int addrResult = addrCounter++;
+
+		final int addrMessageSender1 = addrCounter++;
+		final int addrMessageSender2 = addrCounter++;
+		final int addrMessageSender3 = addrCounter++;
+		final int addrMessageSender4 = addrCounter++;
+
+		final int addrMessageLength = addrCounter++;
+
+		final int addrMessageData = addrCounter;
+		addrCounter += 4;
+
+		final int addrHashOfSecretA = addrCounter;
+		addrCounter += 4;
+
+		final int addrPartnerDogecoinPKH = addrCounter;
+		addrCounter += 4;
+
+		final int addrPartnerReceivingAddress = addrCounter;
+		addrCounter += 4;
+
+		final int addrMode = addrCounter++;
+		assert addrMode == MODE_VALUE_OFFSET : String.format("addrMode %d does not match MODE_VALUE_OFFSET %d", addrMode, MODE_VALUE_OFFSET);
+
+		// Data segment
+		ByteBuffer dataByteBuffer = ByteBuffer.allocate(addrCounter * MachineState.VALUE_SIZE);
+
+		// AT creator's trade Qortal address, decoded from Base58
+		assert dataByteBuffer.position() == addrCreatorTradeAddress1 * MachineState.VALUE_SIZE : "addrCreatorTradeAddress1 incorrect";
+		byte[] creatorTradeAddressBytes = Base58.decode(creatorTradeAddress);
+		dataByteBuffer.put(Bytes.ensureCapacity(creatorTradeAddressBytes, 32, 0));
+
+		// Dogecoin public key hash
+		assert dataByteBuffer.position() == addrDogecoinPublicKeyHash * MachineState.VALUE_SIZE : "addrDogecoinPublicKeyHash incorrect";
+		dataByteBuffer.put(Bytes.ensureCapacity(dogecoinPublicKeyHash, 32, 0));
+
+		// Redeem Qort amount
+		assert dataByteBuffer.position() == addrQortAmount * MachineState.VALUE_SIZE : "addrQortAmount incorrect";
+		dataByteBuffer.putLong(qortAmount);
+
+		// Expected Dogecoin amount
+		assert dataByteBuffer.position() == addrDogecoinAmount * MachineState.VALUE_SIZE : "addrDogecoinAmount incorrect";
+		dataByteBuffer.putLong(dogecoinAmount);
+
+		// Suggested trade timeout (minutes)
+		assert dataByteBuffer.position() == addrTradeTimeout * MachineState.VALUE_SIZE : "addrTradeTimeout incorrect";
+		dataByteBuffer.putLong(tradeTimeout);
+
+		// We're only interested in MESSAGE transactions
+		assert dataByteBuffer.position() == addrMessageTxnType * MachineState.VALUE_SIZE : "addrMessageTxnType incorrect";
+		dataByteBuffer.putLong(API.ATTransactionType.MESSAGE.value);
+
+		// Expected length of 'trade' MESSAGE data from AT creator
+		assert dataByteBuffer.position() == addrExpectedTradeMessageLength * MachineState.VALUE_SIZE : "addrExpectedTradeMessageLength incorrect";
+		dataByteBuffer.putLong(TRADE_MESSAGE_LENGTH);
+
+		// Expected length of 'redeem' MESSAGE data from trade partner
+		assert dataByteBuffer.position() == addrExpectedRedeemMessageLength * MachineState.VALUE_SIZE : "addrExpectedRedeemMessageLength incorrect";
+		dataByteBuffer.putLong(REDEEM_MESSAGE_LENGTH);
+
+		// Index into data segment of AT creator's address, used by GET_B_IND
+		assert dataByteBuffer.position() == addrCreatorAddressPointer * MachineState.VALUE_SIZE : "addrCreatorAddressPointer incorrect";
+		dataByteBuffer.putLong(addrCreatorAddress1);
+
+		// Index into data segment of partner's Qortal address, used by SET_B_IND
+		assert dataByteBuffer.position() == addrQortalPartnerAddressPointer * MachineState.VALUE_SIZE : "addrQortalPartnerAddressPointer incorrect";
+		dataByteBuffer.putLong(addrQortalPartnerAddress1);
+
+		// Index into data segment of (temporary) transaction's sender's address, used by GET_B_IND
+		assert dataByteBuffer.position() == addrMessageSenderPointer * MachineState.VALUE_SIZE : "addrMessageSenderPointer incorrect";
+		dataByteBuffer.putLong(addrMessageSender1);
+
+		// Offset into 'trade' MESSAGE data payload for extracting partner's Dogecoin PKH
+		assert dataByteBuffer.position() == addrTradeMessagePartnerDogecoinPKHOffset * MachineState.VALUE_SIZE : "addrTradeMessagePartnerDogecoinPKHOffset incorrect";
+		dataByteBuffer.putLong(32L);
+
+		// Index into data segment of partner's Dogecoin PKH, used by GET_B_IND
+		assert dataByteBuffer.position() == addrPartnerDogecoinPKHPointer * MachineState.VALUE_SIZE : "addrPartnerDogecoinPKHPointer incorrect";
+		dataByteBuffer.putLong(addrPartnerDogecoinPKH);
+
+		// Offset into 'trade' MESSAGE data payload for extracting hash-of-secret-A
+		assert dataByteBuffer.position() == addrTradeMessageHashOfSecretAOffset * MachineState.VALUE_SIZE : "addrTradeMessageHashOfSecretAOffset incorrect";
+		dataByteBuffer.putLong(64L);
+
+		// Index into data segment to hash of secret A, used by GET_B_IND
+		assert dataByteBuffer.position() == addrHashOfSecretAPointer * MachineState.VALUE_SIZE : "addrHashOfSecretAPointer incorrect";
+		dataByteBuffer.putLong(addrHashOfSecretA);
+
+		// Offset into 'redeem' MESSAGE data payload for extracting Qortal receiving address
+		assert dataByteBuffer.position() == addrRedeemMessageReceivingAddressOffset * MachineState.VALUE_SIZE : "addrRedeemMessageReceivingAddressOffset incorrect";
+		dataByteBuffer.putLong(32L);
+
+		// Source location and length for hashing any passed secret
+		assert dataByteBuffer.position() == addrMessageDataPointer * MachineState.VALUE_SIZE : "addrMessageDataPointer incorrect";
+		dataByteBuffer.putLong(addrMessageData);
+		assert dataByteBuffer.position() == addrMessageDataLength * MachineState.VALUE_SIZE : "addrMessageDataLength incorrect";
+		dataByteBuffer.putLong(32L);
+
+		// Pointer into data segment of where to save partner's receiving Qortal address, used by GET_B_IND
+		assert dataByteBuffer.position() == addrPartnerReceivingAddressPointer * MachineState.VALUE_SIZE : "addrPartnerReceivingAddressPointer incorrect";
+		dataByteBuffer.putLong(addrPartnerReceivingAddress);
+
+		assert dataByteBuffer.position() == addrEndOfConstants * MachineState.VALUE_SIZE : "dataByteBuffer position not at end of constants";
+
+		// Code labels
+		Integer labelRefund = null;
+
+		Integer labelTradeTxnLoop = null;
+		Integer labelCheckTradeTxn = null;
+		Integer labelCheckCancelTxn = null;
+		Integer labelNotTradeNorCancelTxn = null;
+		Integer labelCheckNonRefundTradeTxn = null;
+		Integer labelTradeTxnExtract = null;
+		Integer labelRedeemTxnLoop = null;
+		Integer labelCheckRedeemTxn = null;
+		Integer labelCheckRedeemTxnSender = null;
+		Integer labelPayout = null;
+
+		ByteBuffer codeByteBuffer = ByteBuffer.allocate(768);
+
+		// Two-pass version
+		for (int pass = 0; pass < 2; ++pass) {
+			codeByteBuffer.clear();
+
+			try {
+				/* Initialization */
+
+				/* NOP - to ensure DOGECOIN ACCT is unique */
+				codeByteBuffer.put(OpCode.NOP.compile());
+
+				// Use AT creation 'timestamp' as starting point for finding transactions sent to AT
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_CREATION_TIMESTAMP, addrLastTxnTimestamp));
+
+				// Load B register with AT creator's address so we can save it into addrCreatorAddress1-4
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_CREATOR_INTO_B));
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrCreatorAddressPointer));
+
+				// Set restart position to after this opcode
+				codeByteBuffer.put(OpCode.SET_PCS.compile());
+
+				/* Loop, waiting for message from AT creator's trade address containing trade partner details, or AT owner's address to cancel offer */
+
+				/* Transaction processing loop */
+				labelTradeTxnLoop = codeByteBuffer.position();
+
+				// Find next transaction (if any) to this AT since the last one (referenced by addrLastTxnTimestamp)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PUT_TX_AFTER_TIMESTAMP_INTO_A, addrLastTxnTimestamp));
+				// If no transaction found, A will be zero. If A is zero, set addrResult to 1, otherwise 0.
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.CHECK_A_IS_ZERO, addrResult));
+				// If addrResult is zero (i.e. A is non-zero, transaction was found) then go check transaction
+				codeByteBuffer.put(OpCode.BZR_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelCheckTradeTxn)));
+				// Stop and wait for next block
+				codeByteBuffer.put(OpCode.STP_IMD.compile());
+
+				/* Check transaction */
+				labelCheckTradeTxn = codeByteBuffer.position();
+
+				// Update our 'last found transaction's timestamp' using 'timestamp' from transaction
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TIMESTAMP_FROM_TX_IN_A, addrLastTxnTimestamp));
+				// Extract transaction type (message/payment) from transaction and save type in addrTxnType
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TYPE_FROM_TX_IN_A, addrTxnType));
+				// If transaction type is not MESSAGE type then go look for another transaction
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrTxnType, addrMessageTxnType, calcOffset(codeByteBuffer, labelTradeTxnLoop)));
+
+				/* Check transaction's sender. We're expecting AT creator's trade address for 'trade' message, or AT creator's own address for 'cancel' message. */
+
+				// Extract sender address from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_ADDRESS_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrMessageSender1 (as pointed to by addrMessageSenderPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageSenderPointer));
+				// Compare each part of message sender's address with AT creator's trade address. If they don't match, check for cancel situation.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrCreatorTradeAddress1, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrCreatorTradeAddress2, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrCreatorTradeAddress3, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrCreatorTradeAddress4, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				// Message sender's address matches AT creator's trade address so go process 'trade' message
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelCheckNonRefundTradeTxn == null ? 0 : labelCheckNonRefundTradeTxn));
+
+				/* Checking message sender for possible cancel message */
+				labelCheckCancelTxn = codeByteBuffer.position();
+
+				// Compare each part of message sender's address with AT creator's address. If they don't match, look for another transaction.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrCreatorAddress1, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrCreatorAddress2, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrCreatorAddress3, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrCreatorAddress4, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				// Partner address is AT creator's address, so cancel offer and finish.
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.CANCELLED.value));
+				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
+				codeByteBuffer.put(OpCode.FIN_IMD.compile());
+
+				/* Not trade nor cancel message */
+				labelNotTradeNorCancelTxn = codeByteBuffer.position();
+
+				// Loop to find another transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelTradeTxnLoop == null ? 0 : labelTradeTxnLoop));
+
+				/* Possible switch-to-trade-mode message */
+				labelCheckNonRefundTradeTxn = codeByteBuffer.position();
+
+				// Check 'trade' message we received has expected number of message bytes
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(QortalFunctionCode.GET_MESSAGE_LENGTH_FROM_TX_IN_A.value, addrMessageLength));
+				// If message length matches, branch to info extraction code
+				codeByteBuffer.put(OpCode.BEQ_DAT.compile(addrMessageLength, addrExpectedTradeMessageLength, calcOffset(codeByteBuffer, labelTradeTxnExtract)));
+				// Message length didn't match - go back to finding another 'trade' MESSAGE transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelTradeTxnLoop == null ? 0 : labelTradeTxnLoop));
+
+				/* Extracting info from 'trade' MESSAGE transaction */
+				labelTradeTxnExtract = codeByteBuffer.position();
+
+				// Extract message from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_MESSAGE_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrQortalPartnerAddress1 (as pointed to by addrQortalPartnerAddressPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrQortalPartnerAddressPointer));
+
+				// Extract trade partner's Dogecoin public key hash (PKH) from message into B
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.PUT_PARTIAL_MESSAGE_FROM_TX_IN_A_INTO_B.value, addrTradeMessagePartnerDogecoinPKHOffset));
+				// Store partner's Dogecoin PKH (we only really use values from B1-B3)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrPartnerDogecoinPKHPointer));
+				// Extract AT trade timeout (minutes) (from B4)
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_B4, addrRefundTimeout));
+
+				// Grab next 32 bytes
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.PUT_PARTIAL_MESSAGE_FROM_TX_IN_A_INTO_B.value, addrTradeMessageHashOfSecretAOffset));
+
+				// Extract hash-of-secret-A (we only really use values from B1-B3)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrHashOfSecretAPointer));
+				// Extract lockTime-A (from B4)
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_B4, addrLockTimeA));
+
+				// Calculate trade timeout refund 'timestamp' by adding addrRefundTimeout minutes to this transaction's 'timestamp', then save into addrRefundTimestamp
+				codeByteBuffer.put(OpCode.EXT_FUN_RET_DAT_2.compile(FunctionCode.ADD_MINUTES_TO_TIMESTAMP, addrRefundTimestamp, addrLastTxnTimestamp, addrRefundTimeout));
+
+				/* We are in 'trade mode' */
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.TRADING.value));
+
+				// Set restart position to after this opcode
+				codeByteBuffer.put(OpCode.SET_PCS.compile());
+
+				/* Loop, waiting for trade timeout or 'redeem' MESSAGE from Qortal trade partner */
+
+				// Fetch current block 'timestamp'
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_BLOCK_TIMESTAMP, addrBlockTimestamp));
+				// If we're not past refund 'timestamp' then look for next transaction
+				codeByteBuffer.put(OpCode.BLT_DAT.compile(addrBlockTimestamp, addrRefundTimestamp, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+				// We're past refund 'timestamp' so go refund everything back to AT creator
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelRefund == null ? 0 : labelRefund));
+
+				/* Transaction processing loop */
+				labelRedeemTxnLoop = codeByteBuffer.position();
+
+				// Find next transaction to this AT since the last one (if any)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PUT_TX_AFTER_TIMESTAMP_INTO_A, addrLastTxnTimestamp));
+				// If no transaction found, A will be zero. If A is zero, set addrComparator to 1, otherwise 0.
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.CHECK_A_IS_ZERO, addrResult));
+				// If addrResult is zero (i.e. A is non-zero, transaction was found) then go check transaction
+				codeByteBuffer.put(OpCode.BZR_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelCheckRedeemTxn)));
+				// Stop and wait for next block
+				codeByteBuffer.put(OpCode.STP_IMD.compile());
+
+				/* Check transaction */
+				labelCheckRedeemTxn = codeByteBuffer.position();
+
+				// Update our 'last found transaction's timestamp' using 'timestamp' from transaction
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TIMESTAMP_FROM_TX_IN_A, addrLastTxnTimestamp));
+				// Extract transaction type (message/payment) from transaction and save type in addrTxnType
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TYPE_FROM_TX_IN_A, addrTxnType));
+				// If transaction type is not MESSAGE type then go look for another transaction
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrTxnType, addrMessageTxnType, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+
+				/* Check message payload length */
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(QortalFunctionCode.GET_MESSAGE_LENGTH_FROM_TX_IN_A.value, addrMessageLength));
+				// If message length matches, branch to sender checking code
+				codeByteBuffer.put(OpCode.BEQ_DAT.compile(addrMessageLength, addrExpectedRedeemMessageLength, calcOffset(codeByteBuffer, labelCheckRedeemTxnSender)));
+				// Message length didn't match - go back to finding another 'redeem' MESSAGE transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelRedeemTxnLoop == null ? 0 : labelRedeemTxnLoop));
+
+				/* Check transaction's sender */
+				labelCheckRedeemTxnSender = codeByteBuffer.position();
+
+				// Extract sender address from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_ADDRESS_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrMessageSender1 (as pointed to by addrMessageSenderPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageSenderPointer));
+				// Compare each part of transaction's sender's address with expected address. If they don't match, look for another transaction.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrQortalPartnerAddress1, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrQortalPartnerAddress2, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrQortalPartnerAddress3, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrQortalPartnerAddress4, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+
+				/* Check 'secret-A' in transaction's message */
+
+				// Extract secret-A from first 32 bytes of message from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_MESSAGE_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrMessageData (as pointed to by addrMessageDataPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageDataPointer));
+				// Load B register with expected hash result (as pointed to by addrHashOfSecretAPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.SET_B_IND, addrHashOfSecretAPointer));
+				// Perform HASH160 using source data at addrMessageData. (Location and length specified via addrMessageDataPointer and addrMessageDataLength).
+				// Save the equality result (1 if they match, 0 otherwise) into addrResult.
+				codeByteBuffer.put(OpCode.EXT_FUN_RET_DAT_2.compile(FunctionCode.CHECK_HASH160_WITH_B, addrResult, addrMessageDataPointer, addrMessageDataLength));
+				// If hashes don't match, addrResult will be zero so go find another transaction
+				codeByteBuffer.put(OpCode.BNZ_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelPayout)));
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelRedeemTxnLoop == null ? 0 : labelRedeemTxnLoop));
+
+				/* Success! Pay arranged amount to receiving address */
+				labelPayout = codeByteBuffer.position();
+
+				// Extract Qortal receiving address from next 32 bytes of message from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.PUT_PARTIAL_MESSAGE_FROM_TX_IN_A_INTO_B.value, addrRedeemMessageReceivingAddressOffset));
+				// Save B register into data segment starting at addrPartnerReceivingAddress (as pointed to by addrPartnerReceivingAddressPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrPartnerReceivingAddressPointer));
+				// Pay AT's balance to receiving address
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PAY_TO_ADDRESS_IN_B, addrQortAmount));
+				// Set redeemed mode
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.REDEEMED.value));
+				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
+				codeByteBuffer.put(OpCode.FIN_IMD.compile());
+
+				// Fall-through to refunding any remaining balance back to AT creator
+
+				/* Refund balance back to AT creator */
+				labelRefund = codeByteBuffer.position();
+
+				// Set refunded mode
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.REFUNDED.value));
+				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
+				codeByteBuffer.put(OpCode.FIN_IMD.compile());
+			} catch (CompilationException e) {
+				throw new IllegalStateException("Unable to compile DOGE-QORT ACCT?", e);
+			}
+		}
+
+		codeByteBuffer.flip();
+
+		byte[] codeBytes = new byte[codeByteBuffer.limit()];
+		codeByteBuffer.get(codeBytes);
+
+		assert Arrays.equals(Crypto.digest(codeBytes), DogecoinACCTv1.CODE_BYTES_HASH)
+			: String.format("BTCACCT.CODE_BYTES_HASH mismatch: expected %s, actual %s", HashCode.fromBytes(CODE_BYTES_HASH), HashCode.fromBytes(Crypto.digest(codeBytes)));
+
+		final short ciyamAtVersion = 2;
+		final short numCallStackPages = 0;
+		final short numUserStackPages = 0;
+		final long minActivationAmount = 0L;
+
+		return MachineState.toCreationBytes(ciyamAtVersion, codeBytes, dataByteBuffer.array(), numCallStackPages, numUserStackPages, minActivationAmount);
+	}
+
+	/**
+	 * Returns CrossChainTradeData with useful info extracted from AT.
+	 */
+	@Override
+	public CrossChainTradeData populateTradeData(Repository repository, ATData atData) throws DataException {
+		ATStateData atStateData = repository.getATRepository().getLatestATState(atData.getATAddress());
+		return populateTradeData(repository, atData.getCreatorPublicKey(), atData.getCreation(), atStateData);
+	}
+
+	/**
+	 * Returns CrossChainTradeData with useful info extracted from AT.
+	 */
+	@Override
+	public CrossChainTradeData populateTradeData(Repository repository, ATStateData atStateData) throws DataException {
+		ATData atData = repository.getATRepository().fromATAddress(atStateData.getATAddress());
+		return populateTradeData(repository, atData.getCreatorPublicKey(), atData.getCreation(), atStateData);
+	}
+
+	/**
+	 * Returns CrossChainTradeData with useful info extracted from AT.
+	 */
+	public CrossChainTradeData populateTradeData(Repository repository, byte[] creatorPublicKey, long creationTimestamp, ATStateData atStateData) throws DataException {
+		byte[] addressBytes = new byte[25]; // for general use
+		String atAddress = atStateData.getATAddress();
+
+		CrossChainTradeData tradeData = new CrossChainTradeData();
+
+		tradeData.foreignBlockchain = SupportedBlockchain.DOGECOIN.name();
+		tradeData.acctName = NAME;
+
+		tradeData.qortalAtAddress = atAddress;
+		tradeData.qortalCreator = Crypto.toAddress(creatorPublicKey);
+		tradeData.creationTimestamp = creationTimestamp;
+
+		Account atAccount = new Account(repository, atAddress);
+		tradeData.qortBalance = atAccount.getConfirmedBalance(Asset.QORT);
+
+		byte[] stateData = atStateData.getStateData();
+		ByteBuffer dataByteBuffer = ByteBuffer.wrap(stateData);
+		dataByteBuffer.position(MachineState.HEADER_LENGTH);
+
+		/* Constants */
+
+		// Skip creator's trade address
+		dataByteBuffer.get(addressBytes);
+		tradeData.qortalCreatorTradeAddress = Base58.encode(addressBytes);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - addressBytes.length);
+
+		// Creator's Dogecoin/foreign public key hash
+		tradeData.creatorForeignPKH = new byte[20];
+		dataByteBuffer.get(tradeData.creatorForeignPKH);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - tradeData.creatorForeignPKH.length); // skip to 32 bytes
+
+		// We don't use secret-B
+		tradeData.hashOfSecretB = null;
+
+		// Redeem payout
+		tradeData.qortAmount = dataByteBuffer.getLong();
+
+		// Expected DOGE amount
+		tradeData.expectedForeignAmount = dataByteBuffer.getLong();
+
+		// Trade timeout
+		tradeData.tradeTimeout = (int) dataByteBuffer.getLong();
+
+		// Skip MESSAGE transaction type
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip expected 'trade' message length
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip expected 'redeem' message length
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to creator's address
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to partner's Qortal trade address
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to message sender
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip 'trade' message data offset for partner's Dogecoin PKH
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to partner's Dogecoin PKH
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip 'trade' message data offset for hash-of-secret-A
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to hash-of-secret-A
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip 'redeem' message data offset for partner's Qortal receiving address
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to message data
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip message data length
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to partner's receiving address
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		/* End of constants / begin variables */
+
+		// Skip AT creator's address
+		dataByteBuffer.position(dataByteBuffer.position() + 8 * 4);
+
+		// Partner's trade address (if present)
+		dataByteBuffer.get(addressBytes);
+		String qortalRecipient = Base58.encode(addressBytes);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - addressBytes.length);
+
+		// Potential lockTimeA (if in trade mode)
+		int lockTimeA = (int) dataByteBuffer.getLong();
+
+		// AT refund timeout (probably only useful for debugging)
+		int refundTimeout = (int) dataByteBuffer.getLong();
+
+		// Trade-mode refund timestamp (AT 'timestamp' converted to Qortal block height)
+		long tradeRefundTimestamp = dataByteBuffer.getLong();
+
+		// Skip last transaction timestamp
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip block timestamp
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip transaction type
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip temporary result
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip temporary message sender
+		dataByteBuffer.position(dataByteBuffer.position() + 8 * 4);
+
+		// Skip message length
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip temporary message data
+		dataByteBuffer.position(dataByteBuffer.position() + 8 * 4);
+
+		// Potential hash160 of secret A
+		byte[] hashOfSecretA = new byte[20];
+		dataByteBuffer.get(hashOfSecretA);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - hashOfSecretA.length); // skip to 32 bytes
+
+		// Potential partner's Dogecoin PKH
+		byte[] partnerDogecoinPKH = new byte[20];
+		dataByteBuffer.get(partnerDogecoinPKH);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - partnerDogecoinPKH.length); // skip to 32 bytes
+
+		// Partner's receiving address (if present)
+		byte[] partnerReceivingAddress = new byte[25];
+		dataByteBuffer.get(partnerReceivingAddress);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - partnerReceivingAddress.length); // skip to 32 bytes
+
+		// Trade AT's 'mode'
+		long modeValue = dataByteBuffer.getLong();
+		AcctMode mode = AcctMode.valueOf((int) (modeValue & 0xffL));
+
+		/* End of variables */
+
+		if (mode != null && mode != AcctMode.OFFERING) {
+			tradeData.mode = mode;
+			tradeData.refundTimeout = refundTimeout;
+			tradeData.tradeRefundHeight = new Timestamp(tradeRefundTimestamp).blockHeight;
+			tradeData.qortalPartnerAddress = qortalRecipient;
+			tradeData.hashOfSecretA = hashOfSecretA;
+			tradeData.partnerForeignPKH = partnerDogecoinPKH;
+			tradeData.lockTimeA = lockTimeA;
+
+			if (mode == AcctMode.REDEEMED)
+				tradeData.qortalPartnerReceivingAddress = Base58.encode(partnerReceivingAddress);
+		} else {
+			tradeData.mode = AcctMode.OFFERING;
+		}
+
+		tradeData.duplicateDeprecated();
+
+		return tradeData;
+	}
+
+	/** Returns 'offer' MESSAGE payload for trade partner to send to AT creator's trade address. */
+	public static byte[] buildOfferMessage(byte[] partnerBitcoinPKH, byte[] hashOfSecretA, int lockTimeA) {
+		byte[] lockTimeABytes = BitTwiddling.toBEByteArray((long) lockTimeA);
+		return Bytes.concat(partnerBitcoinPKH, hashOfSecretA, lockTimeABytes);
+	}
+
+	/** Returns info extracted from 'offer' MESSAGE payload sent by trade partner to AT creator's trade address, or null if not valid. */
+	public static OfferMessageData extractOfferMessageData(byte[] messageData) {
+		if (messageData == null || messageData.length != OFFER_MESSAGE_LENGTH)
+			return null;
+
+		OfferMessageData offerMessageData = new OfferMessageData();
+		offerMessageData.partnerDogecoinPKH = Arrays.copyOfRange(messageData, 0, 20);
+		offerMessageData.hashOfSecretA = Arrays.copyOfRange(messageData, 20, 40);
+		offerMessageData.lockTimeA = BitTwiddling.longFromBEBytes(messageData, 40);
+
+		return offerMessageData;
+	}
+
+	/** Returns 'trade' MESSAGE payload for AT creator to send to AT. */
+	public static byte[] buildTradeMessage(String partnerQortalTradeAddress, byte[] partnerBitcoinPKH, byte[] hashOfSecretA, int lockTimeA, int refundTimeout) {
+		byte[] data = new byte[TRADE_MESSAGE_LENGTH];
+		byte[] partnerQortalAddressBytes = Base58.decode(partnerQortalTradeAddress);
+		byte[] lockTimeABytes = BitTwiddling.toBEByteArray((long) lockTimeA);
+		byte[] refundTimeoutBytes = BitTwiddling.toBEByteArray((long) refundTimeout);
+
+		System.arraycopy(partnerQortalAddressBytes, 0, data, 0, partnerQortalAddressBytes.length);
+		System.arraycopy(partnerBitcoinPKH, 0, data, 32, partnerBitcoinPKH.length);
+		System.arraycopy(refundTimeoutBytes, 0, data, 56, refundTimeoutBytes.length);
+		System.arraycopy(hashOfSecretA, 0, data, 64, hashOfSecretA.length);
+		System.arraycopy(lockTimeABytes, 0, data, 88, lockTimeABytes.length);
+
+		return data;
+	}
+
+	/** Returns 'cancel' MESSAGE payload for AT creator to cancel trade AT. */
+	@Override
+	public byte[] buildCancelMessage(String creatorQortalAddress) {
+		byte[] data = new byte[CANCEL_MESSAGE_LENGTH];
+		byte[] creatorQortalAddressBytes = Base58.decode(creatorQortalAddress);
+
+		System.arraycopy(creatorQortalAddressBytes, 0, data, 0, creatorQortalAddressBytes.length);
+
+		return data;
+	}
+
+	/** Returns 'redeem' MESSAGE payload for trade partner to send to AT. */
+	public static byte[] buildRedeemMessage(byte[] secretA, String qortalReceivingAddress) {
+		byte[] data = new byte[REDEEM_MESSAGE_LENGTH];
+		byte[] qortalReceivingAddressBytes = Base58.decode(qortalReceivingAddress);
+
+		System.arraycopy(secretA, 0, data, 0, secretA.length);
+		System.arraycopy(qortalReceivingAddressBytes, 0, data, 32, qortalReceivingAddressBytes.length);
+
+		return data;
+	}
+
+	/** Returns refund timeout (minutes) based on trade partner's 'offer' MESSAGE timestamp and P2SH-A locktime. */
+	public static int calcRefundTimeout(long offerMessageTimestamp, int lockTimeA) {
+		// refund should be triggered halfway between offerMessageTimestamp and lockTimeA
+		return (int) ((lockTimeA - (offerMessageTimestamp / 1000L)) / 2L / 60L);
+	}
+
+	@Override
+	public byte[] findSecretA(Repository repository, CrossChainTradeData crossChainTradeData) throws DataException {
+		String atAddress = crossChainTradeData.qortalAtAddress;
+		String redeemerAddress = crossChainTradeData.qortalPartnerAddress;
+
+		// We don't have partner's public key so we check every message to AT
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(null, atAddress, null, null, null);
+		if (messageTransactionsData == null)
+			return null;
+
+		// Find 'redeem' message
+		for (MessageTransactionData messageTransactionData : messageTransactionsData) {
+			// Check message payload type/encryption
+			if (messageTransactionData.isText() || messageTransactionData.isEncrypted())
+				continue;
+
+			// Check message payload size
+			byte[] messageData = messageTransactionData.getData();
+			if (messageData.length != REDEEM_MESSAGE_LENGTH)
+				// Wrong payload length
+				continue;
+
+			// Check sender
+			if (!Crypto.toAddress(messageTransactionData.getSenderPublicKey()).equals(redeemerAddress))
+				// Wrong sender;
+				continue;
+
+			// Extract secretA
+			byte[] secretA = new byte[32];
+			System.arraycopy(messageData, 0, secretA, 0, secretA.length);
+
+			byte[] hashOfSecretA = Crypto.hash160(secretA);
+			if (!Arrays.equals(hashOfSecretA, crossChainTradeData.hashOfSecretA))
+				continue;
+
+			return secretA;
+		}
+
+		return null;
+	}
+
+}

src/main/java/org/qortal/crosschain/DogecoinACCTv2.java

@@ -0,0 +1,861 @@
+package org.qortal.crosschain;
+
+import com.google.common.hash.HashCode;
+import com.google.common.primitives.Bytes;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.ciyam.at.*;
+import org.qortal.account.Account;
+import org.qortal.asset.Asset;
+import org.qortal.at.QortalFunctionCode;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.at.ATStateData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.utils.Base58;
+import org.qortal.utils.BitTwiddling;
+
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.List;
+
+import static org.ciyam.at.OpCode.calcOffset;
+
+/**
+ * Cross-chain trade AT
+ * 
+ * <p>
+ * <ul>
+ * <li>Bob generates Dogecoin & Qortal 'trade' keys
+ * 		<ul>
+ * 			<li>private key required to sign P2SH redeem tx</li>
+ * 			<li>private key could be used to create 'secret' (e.g. double-SHA256)</li>
+ * 			<li>encrypted private key could be stored in Qortal AT for access by Bob from any node</li>
+ * 		</ul>
+ * </li>
+ * <li>Bob deploys Qortal AT
+ * 		<ul>
+ * 		</ul>
+ * </li>
+ * <li>Alice finds Qortal AT and wants to trade
+ * 		<ul>
+ * 			<li>Alice generates Dogecoin & Qortal 'trade' keys</li>
+ * 			<li>Alice funds Dogecoin P2SH-A</li>
+ * 			<li>Alice sends 'offer' MESSAGE to Bob from her Qortal trade address, containing:
+ * 				<ul>
+ * 					<li>hash-of-secret-A</li>
+ * 					<li>her 'trade' Dogecoin PKH</li>
+ * 				</ul>
+ * 			</li>
+ * 		</ul>
+ * </li>
+ * <li>Bob receives "offer" MESSAGE
+ * 		<ul>
+ * 			<li>Checks Alice's P2SH-A</li>
+ * 			<li>Sends 'trade' MESSAGE to Qortal AT from his trade address, containing:
+ * 				<ul>
+ * 					<li>Alice's trade Qortal address</li>
+ * 					<li>Alice's trade Dogecoin PKH</li>
+ * 					<li>hash-of-secret-A</li>
+ * 				</ul>
+ * 			</li>
+ * 		</ul>
+ * </li>
+ * <li>Alice checks Qortal AT to confirm it's locked to her
+ * 		<ul>
+ * 			<li>Alice sends 'redeem' MESSAGE to Qortal AT from her trade address, containing:
+ * 				<ul>
+ * 					<li>secret-A</li>
+ * 					<li>Qortal receiving address of her chosing</li>
+ * 				</ul>
+ * 			</li>
+ * 			<li>AT's QORT funds are sent to Qortal receiving address</li>
+ * 		</ul>
+ * </li>
+ * <li>Bob checks AT, extracts secret-A
+ * 		<ul>
+ * 			<li>Bob redeems P2SH-A using his Dogecoin trade key and secret-A</li>
+ * 			<li>P2SH-A DOGE funds end up at Dogecoin address determined by redeem transaction output(s)</li>
+ * 		</ul>
+ * </li>
+ * </ul>
+ */
+public class DogecoinACCTv2 implements ACCT {
+
+	private static final Logger LOGGER = LogManager.getLogger(DogecoinACCTv2.class);
+
+	public static final String NAME = DogecoinACCTv2.class.getSimpleName();
+	public static final byte[] CODE_BYTES_HASH = HashCode.fromString("6fff38d6eeb06568a9c879c5628527730319844aa0de53f5f4ffab5506efe885").asBytes(); // SHA256 of AT code bytes
+
+	public static final int SECRET_LENGTH = 32;
+
+	/** <b>Value</b> offset into AT segment where 'mode' variable (long) is stored. (Multiply by MachineState.VALUE_SIZE for byte offset). */
+	private static final int MODE_VALUE_OFFSET = 61;
+	/** <b>Byte</b> offset into AT state data where 'mode' variable (long) is stored. */
+	public static final int MODE_BYTE_OFFSET = MachineState.HEADER_LENGTH + (MODE_VALUE_OFFSET * MachineState.VALUE_SIZE);
+
+	public static class OfferMessageData {
+		public byte[] partnerDogecoinPKH;
+		public byte[] hashOfSecretA;
+		public long lockTimeA;
+	}
+	public static final int OFFER_MESSAGE_LENGTH = 20 /*partnerDogecoinPKH*/ + 20 /*hashOfSecretA*/ + 8 /*lockTimeA*/;
+	public static final int TRADE_MESSAGE_LENGTH = 32 /*partner's Qortal trade address (padded from 25 to 32)*/
+			+ 24 /*partner's Dogecoin PKH (padded from 20 to 24)*/
+			+ 8 /*AT trade timeout (minutes)*/
+			+ 24 /*hash of secret-A (padded from 20 to 24)*/
+			+ 8 /*lockTimeA*/;
+	public static final int REDEEM_MESSAGE_LENGTH = 32 /*secret-A*/ + 32 /*partner's Qortal receiving address padded from 25 to 32*/;
+	public static final int CANCEL_MESSAGE_LENGTH = 32 /*AT creator's Qortal address*/;
+
+	private static DogecoinACCTv2 instance;
+
+	private DogecoinACCTv2() {
+	}
+
+	public static synchronized DogecoinACCTv2 getInstance() {
+		if (instance == null)
+			instance = new DogecoinACCTv2();
+
+		return instance;
+	}
+
+	@Override
+	public byte[] getCodeBytesHash() {
+		return CODE_BYTES_HASH;
+	}
+
+	@Override
+	public int getModeByteOffset() {
+		return MODE_BYTE_OFFSET;
+	}
+
+	@Override
+	public ForeignBlockchain getBlockchain() {
+		return Dogecoin.getInstance();
+	}
+
+	/**
+	 * Returns Qortal AT creation bytes for cross-chain trading AT.
+	 * <p>
+	 * <tt>tradeTimeout</tt> (minutes) is the time window for the trade partner to send the
+	 * 32-byte secret to the AT, before the AT automatically refunds the AT's creator.
+	 * 
+	 * @param creatorTradeAddress AT creator's trade Qortal address
+	 * @param dogecoinPublicKeyHash 20-byte HASH160 of creator's trade Dogecoin public key
+	 * @param qortAmount how much QORT to pay trade partner if they send correct 32-byte secrets to AT
+	 * @param dogecoinAmount how much DOGE the AT creator is expecting to trade
+	 * @param tradeTimeout suggested timeout for entire trade
+	 */
+	public static byte[] buildQortalAT(String creatorTradeAddress, byte[] dogecoinPublicKeyHash, long qortAmount, long dogecoinAmount, int tradeTimeout) {
+		if (dogecoinPublicKeyHash.length != 20)
+			throw new IllegalArgumentException("Dogecoin public key hash should be 20 bytes");
+
+		// Labels for data segment addresses
+		int addrCounter = 0;
+
+		// Constants (with corresponding dataByteBuffer.put*() calls below)
+
+		final int addrCreatorTradeAddress1 = addrCounter++;
+		final int addrCreatorTradeAddress2 = addrCounter++;
+		final int addrCreatorTradeAddress3 = addrCounter++;
+		final int addrCreatorTradeAddress4 = addrCounter++;
+
+		final int addrDogecoinPublicKeyHash = addrCounter;
+		addrCounter += 4;
+
+		final int addrQortAmount = addrCounter++;
+		final int addrDogecoinAmount = addrCounter++;
+		final int addrTradeTimeout = addrCounter++;
+
+		final int addrMessageTxnType = addrCounter++;
+		final int addrExpectedTradeMessageLength = addrCounter++;
+		final int addrExpectedRedeemMessageLength = addrCounter++;
+
+		final int addrCreatorAddressPointer = addrCounter++;
+		final int addrQortalPartnerAddressPointer = addrCounter++;
+		final int addrMessageSenderPointer = addrCounter++;
+
+		final int addrTradeMessagePartnerDogecoinPKHOffset = addrCounter++;
+		final int addrPartnerDogecoinPKHPointer = addrCounter++;
+		final int addrTradeMessageHashOfSecretAOffset = addrCounter++;
+		final int addrHashOfSecretAPointer = addrCounter++;
+
+		final int addrRedeemMessageReceivingAddressOffset = addrCounter++;
+
+		final int addrMessageDataPointer = addrCounter++;
+		final int addrMessageDataLength = addrCounter++;
+
+		final int addrPartnerReceivingAddressPointer = addrCounter++;
+
+		final int addrEndOfConstants = addrCounter;
+
+		// Variables
+
+		final int addrCreatorAddress1 = addrCounter++;
+		final int addrCreatorAddress2 = addrCounter++;
+		final int addrCreatorAddress3 = addrCounter++;
+		final int addrCreatorAddress4 = addrCounter++;
+
+		final int addrQortalPartnerAddress1 = addrCounter++;
+		final int addrQortalPartnerAddress2 = addrCounter++;
+		final int addrQortalPartnerAddress3 = addrCounter++;
+		final int addrQortalPartnerAddress4 = addrCounter++;
+
+		final int addrLockTimeA = addrCounter++;
+		final int addrRefundTimeout = addrCounter++;
+		final int addrRefundTimestamp = addrCounter++;
+		final int addrLastTxnTimestamp = addrCounter++;
+		final int addrBlockTimestamp = addrCounter++;
+		final int addrTxnType = addrCounter++;
+		final int addrResult = addrCounter++;
+
+		final int addrMessageSender1 = addrCounter++;
+		final int addrMessageSender2 = addrCounter++;
+		final int addrMessageSender3 = addrCounter++;
+		final int addrMessageSender4 = addrCounter++;
+
+		final int addrMessageLength = addrCounter++;
+
+		final int addrMessageData = addrCounter;
+		addrCounter += 4;
+
+		final int addrHashOfSecretA = addrCounter;
+		addrCounter += 4;
+
+		final int addrPartnerDogecoinPKH = addrCounter;
+		addrCounter += 4;
+
+		final int addrPartnerReceivingAddress = addrCounter;
+		addrCounter += 4;
+
+		final int addrMode = addrCounter++;
+		assert addrMode == MODE_VALUE_OFFSET : String.format("addrMode %d does not match MODE_VALUE_OFFSET %d", addrMode, MODE_VALUE_OFFSET);
+
+		// Data segment
+		ByteBuffer dataByteBuffer = ByteBuffer.allocate(addrCounter * MachineState.VALUE_SIZE);
+
+		// AT creator's trade Qortal address, decoded from Base58
+		assert dataByteBuffer.position() == addrCreatorTradeAddress1 * MachineState.VALUE_SIZE : "addrCreatorTradeAddress1 incorrect";
+		byte[] creatorTradeAddressBytes = Base58.decode(creatorTradeAddress);
+		dataByteBuffer.put(Bytes.ensureCapacity(creatorTradeAddressBytes, 32, 0));
+
+		// Dogecoin public key hash
+		assert dataByteBuffer.position() == addrDogecoinPublicKeyHash * MachineState.VALUE_SIZE : "addrDogecoinPublicKeyHash incorrect";
+		dataByteBuffer.put(Bytes.ensureCapacity(dogecoinPublicKeyHash, 32, 0));
+
+		// Redeem Qort amount
+		assert dataByteBuffer.position() == addrQortAmount * MachineState.VALUE_SIZE : "addrQortAmount incorrect";
+		dataByteBuffer.putLong(qortAmount);
+
+		// Expected Dogecoin amount
+		assert dataByteBuffer.position() == addrDogecoinAmount * MachineState.VALUE_SIZE : "addrDogecoinAmount incorrect";
+		dataByteBuffer.putLong(dogecoinAmount);
+
+		// Suggested trade timeout (minutes)
+		assert dataByteBuffer.position() == addrTradeTimeout * MachineState.VALUE_SIZE : "addrTradeTimeout incorrect";
+		dataByteBuffer.putLong(tradeTimeout);
+
+		// We're only interested in MESSAGE transactions
+		assert dataByteBuffer.position() == addrMessageTxnType * MachineState.VALUE_SIZE : "addrMessageTxnType incorrect";
+		dataByteBuffer.putLong(API.ATTransactionType.MESSAGE.value);
+
+		// Expected length of 'trade' MESSAGE data from AT creator
+		assert dataByteBuffer.position() == addrExpectedTradeMessageLength * MachineState.VALUE_SIZE : "addrExpectedTradeMessageLength incorrect";
+		dataByteBuffer.putLong(TRADE_MESSAGE_LENGTH);
+
+		// Expected length of 'redeem' MESSAGE data from trade partner
+		assert dataByteBuffer.position() == addrExpectedRedeemMessageLength * MachineState.VALUE_SIZE : "addrExpectedRedeemMessageLength incorrect";
+		dataByteBuffer.putLong(REDEEM_MESSAGE_LENGTH);
+
+		// Index into data segment of AT creator's address, used by GET_B_IND
+		assert dataByteBuffer.position() == addrCreatorAddressPointer * MachineState.VALUE_SIZE : "addrCreatorAddressPointer incorrect";
+		dataByteBuffer.putLong(addrCreatorAddress1);
+
+		// Index into data segment of partner's Qortal address, used by SET_B_IND
+		assert dataByteBuffer.position() == addrQortalPartnerAddressPointer * MachineState.VALUE_SIZE : "addrQortalPartnerAddressPointer incorrect";
+		dataByteBuffer.putLong(addrQortalPartnerAddress1);
+
+		// Index into data segment of (temporary) transaction's sender's address, used by GET_B_IND
+		assert dataByteBuffer.position() == addrMessageSenderPointer * MachineState.VALUE_SIZE : "addrMessageSenderPointer incorrect";
+		dataByteBuffer.putLong(addrMessageSender1);
+
+		// Offset into 'trade' MESSAGE data payload for extracting partner's Dogecoin PKH
+		assert dataByteBuffer.position() == addrTradeMessagePartnerDogecoinPKHOffset * MachineState.VALUE_SIZE : "addrTradeMessagePartnerDogecoinPKHOffset incorrect";
+		dataByteBuffer.putLong(32L);
+
+		// Index into data segment of partner's Dogecoin PKH, used by GET_B_IND
+		assert dataByteBuffer.position() == addrPartnerDogecoinPKHPointer * MachineState.VALUE_SIZE : "addrPartnerDogecoinPKHPointer incorrect";
+		dataByteBuffer.putLong(addrPartnerDogecoinPKH);
+
+		// Offset into 'trade' MESSAGE data payload for extracting hash-of-secret-A
+		assert dataByteBuffer.position() == addrTradeMessageHashOfSecretAOffset * MachineState.VALUE_SIZE : "addrTradeMessageHashOfSecretAOffset incorrect";
+		dataByteBuffer.putLong(64L);
+
+		// Index into data segment to hash of secret A, used by GET_B_IND
+		assert dataByteBuffer.position() == addrHashOfSecretAPointer * MachineState.VALUE_SIZE : "addrHashOfSecretAPointer incorrect";
+		dataByteBuffer.putLong(addrHashOfSecretA);
+
+		// Offset into 'redeem' MESSAGE data payload for extracting Qortal receiving address
+		assert dataByteBuffer.position() == addrRedeemMessageReceivingAddressOffset * MachineState.VALUE_SIZE : "addrRedeemMessageReceivingAddressOffset incorrect";
+		dataByteBuffer.putLong(32L);
+
+		// Source location and length for hashing any passed secret
+		assert dataByteBuffer.position() == addrMessageDataPointer * MachineState.VALUE_SIZE : "addrMessageDataPointer incorrect";
+		dataByteBuffer.putLong(addrMessageData);
+		assert dataByteBuffer.position() == addrMessageDataLength * MachineState.VALUE_SIZE : "addrMessageDataLength incorrect";
+		dataByteBuffer.putLong(32L);
+
+		// Pointer into data segment of where to save partner's receiving Qortal address, used by GET_B_IND
+		assert dataByteBuffer.position() == addrPartnerReceivingAddressPointer * MachineState.VALUE_SIZE : "addrPartnerReceivingAddressPointer incorrect";
+		dataByteBuffer.putLong(addrPartnerReceivingAddress);
+
+		assert dataByteBuffer.position() == addrEndOfConstants * MachineState.VALUE_SIZE : "dataByteBuffer position not at end of constants";
+
+		// Code labels
+		Integer labelRefund = null;
+
+		Integer labelTradeTxnLoop = null;
+		Integer labelCheckTradeTxn = null;
+		Integer labelCheckCancelTxn = null;
+		Integer labelNotTradeNorCancelTxn = null;
+		Integer labelCheckNonRefundTradeTxn = null;
+		Integer labelTradeTxnExtract = null;
+		Integer labelRedeemTxnLoop = null;
+		Integer labelCheckRedeemTxn = null;
+		Integer labelCheckRedeemTxnSender = null;
+		Integer labelPayout = null;
+
+		ByteBuffer codeByteBuffer = ByteBuffer.allocate(768);
+
+		// Two-pass version
+		for (int pass = 0; pass < 2; ++pass) {
+			codeByteBuffer.clear();
+
+			try {
+				/* Initialization */
+
+				/* NOP - to ensure DOGECOIN ACCT is unique */
+				codeByteBuffer.put(OpCode.NOP.compile());
+
+				// Use AT creation 'timestamp' as starting point for finding transactions sent to AT
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_CREATION_TIMESTAMP, addrLastTxnTimestamp));
+
+				// Load B register with AT creator's address so we can save it into addrCreatorAddress1-4
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_CREATOR_INTO_B));
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrCreatorAddressPointer));
+
+				// Set restart position to after this opcode
+				codeByteBuffer.put(OpCode.SET_PCS.compile());
+
+				/* Loop, waiting for message from AT creator's trade address containing trade partner details, or AT owner's address to cancel offer */
+
+				/* Transaction processing loop */
+				labelTradeTxnLoop = codeByteBuffer.position();
+
+				/* Sleep until message arrives */
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.SLEEP_UNTIL_MESSAGE.value, addrLastTxnTimestamp));
+
+				// Find next transaction (if any) to this AT since the last one (referenced by addrLastTxnTimestamp)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PUT_TX_AFTER_TIMESTAMP_INTO_A, addrLastTxnTimestamp));
+				// If no transaction found, A will be zero. If A is zero, set addrResult to 1, otherwise 0.
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.CHECK_A_IS_ZERO, addrResult));
+				// If addrResult is zero (i.e. A is non-zero, transaction was found) then go check transaction
+				codeByteBuffer.put(OpCode.BZR_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelCheckTradeTxn)));
+				// Stop and wait for next block
+				codeByteBuffer.put(OpCode.STP_IMD.compile());
+
+				/* Check transaction */
+				labelCheckTradeTxn = codeByteBuffer.position();
+
+				// Update our 'last found transaction's timestamp' using 'timestamp' from transaction
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TIMESTAMP_FROM_TX_IN_A, addrLastTxnTimestamp));
+				// Extract transaction type (message/payment) from transaction and save type in addrTxnType
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TYPE_FROM_TX_IN_A, addrTxnType));
+				// If transaction type is not MESSAGE type then go look for another transaction
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrTxnType, addrMessageTxnType, calcOffset(codeByteBuffer, labelTradeTxnLoop)));
+
+				/* Check transaction's sender. We're expecting AT creator's trade address for 'trade' message, or AT creator's own address for 'cancel' message. */
+
+				// Extract sender address from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_ADDRESS_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrMessageSender1 (as pointed to by addrMessageSenderPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageSenderPointer));
+				// Compare each part of message sender's address with AT creator's trade address. If they don't match, check for cancel situation.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrCreatorTradeAddress1, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrCreatorTradeAddress2, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrCreatorTradeAddress3, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrCreatorTradeAddress4, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				// Message sender's address matches AT creator's trade address so go process 'trade' message
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelCheckNonRefundTradeTxn == null ? 0 : labelCheckNonRefundTradeTxn));
+
+				/* Checking message sender for possible cancel message */
+				labelCheckCancelTxn = codeByteBuffer.position();
+
+				// Compare each part of message sender's address with AT creator's address. If they don't match, look for another transaction.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrCreatorAddress1, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrCreatorAddress2, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrCreatorAddress3, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrCreatorAddress4, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				// Partner address is AT creator's address, so cancel offer and finish.
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.CANCELLED.value));
+				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
+				codeByteBuffer.put(OpCode.FIN_IMD.compile());
+
+				/* Not trade nor cancel message */
+				labelNotTradeNorCancelTxn = codeByteBuffer.position();
+
+				// Loop to find another transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelTradeTxnLoop == null ? 0 : labelTradeTxnLoop));
+
+				/* Possible switch-to-trade-mode message */
+				labelCheckNonRefundTradeTxn = codeByteBuffer.position();
+
+				// Check 'trade' message we received has expected number of message bytes
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(QortalFunctionCode.GET_MESSAGE_LENGTH_FROM_TX_IN_A.value, addrMessageLength));
+				// If message length matches, branch to info extraction code
+				codeByteBuffer.put(OpCode.BEQ_DAT.compile(addrMessageLength, addrExpectedTradeMessageLength, calcOffset(codeByteBuffer, labelTradeTxnExtract)));
+				// Message length didn't match - go back to finding another 'trade' MESSAGE transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelTradeTxnLoop == null ? 0 : labelTradeTxnLoop));
+
+				/* Extracting info from 'trade' MESSAGE transaction */
+				labelTradeTxnExtract = codeByteBuffer.position();
+
+				// Extract message from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_MESSAGE_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrQortalPartnerAddress1 (as pointed to by addrQortalPartnerAddressPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrQortalPartnerAddressPointer));
+
+				// Extract trade partner's Dogecoin public key hash (PKH) from message into B
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.PUT_PARTIAL_MESSAGE_FROM_TX_IN_A_INTO_B.value, addrTradeMessagePartnerDogecoinPKHOffset));
+				// Store partner's Dogecoin PKH (we only really use values from B1-B3)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrPartnerDogecoinPKHPointer));
+				// Extract AT trade timeout (minutes) (from B4)
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_B4, addrRefundTimeout));
+
+				// Grab next 32 bytes
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.PUT_PARTIAL_MESSAGE_FROM_TX_IN_A_INTO_B.value, addrTradeMessageHashOfSecretAOffset));
+
+				// Extract hash-of-secret-A (we only really use values from B1-B3)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrHashOfSecretAPointer));
+				// Extract lockTime-A (from B4)
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_B4, addrLockTimeA));
+
+				// Calculate trade timeout refund 'timestamp' by adding addrRefundTimeout minutes to this transaction's 'timestamp', then save into addrRefundTimestamp
+				codeByteBuffer.put(OpCode.EXT_FUN_RET_DAT_2.compile(FunctionCode.ADD_MINUTES_TO_TIMESTAMP, addrRefundTimestamp, addrLastTxnTimestamp, addrRefundTimeout));
+
+				/* We are in 'trade mode' */
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.TRADING.value));
+
+				// Set restart position to after this opcode
+				codeByteBuffer.put(OpCode.SET_PCS.compile());
+
+				/* Loop, waiting for trade timeout or 'redeem' MESSAGE from Qortal trade partner */
+
+				// Fetch current block 'timestamp'
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_BLOCK_TIMESTAMP, addrBlockTimestamp));
+				// If we're not past refund 'timestamp' then look for next transaction
+				codeByteBuffer.put(OpCode.BLT_DAT.compile(addrBlockTimestamp, addrRefundTimestamp, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+				// We're past refund 'timestamp' so go refund everything back to AT creator
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelRefund == null ? 0 : labelRefund));
+
+				/* Transaction processing loop */
+				labelRedeemTxnLoop = codeByteBuffer.position();
+
+				/* Sleep until message arrives */
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.SLEEP_UNTIL_MESSAGE.value, addrLastTxnTimestamp));
+
+				// Find next transaction to this AT since the last one (if any)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PUT_TX_AFTER_TIMESTAMP_INTO_A, addrLastTxnTimestamp));
+				// If no transaction found, A will be zero. If A is zero, set addrComparator to 1, otherwise 0.
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.CHECK_A_IS_ZERO, addrResult));
+				// If addrResult is zero (i.e. A is non-zero, transaction was found) then go check transaction
+				codeByteBuffer.put(OpCode.BZR_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelCheckRedeemTxn)));
+				// Stop and wait for next block
+				codeByteBuffer.put(OpCode.STP_IMD.compile());
+
+				/* Check transaction */
+				labelCheckRedeemTxn = codeByteBuffer.position();
+
+				// Update our 'last found transaction's timestamp' using 'timestamp' from transaction
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TIMESTAMP_FROM_TX_IN_A, addrLastTxnTimestamp));
+				// Extract transaction type (message/payment) from transaction and save type in addrTxnType
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TYPE_FROM_TX_IN_A, addrTxnType));
+				// If transaction type is not MESSAGE type then go look for another transaction
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrTxnType, addrMessageTxnType, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+
+				/* Check message payload length */
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(QortalFunctionCode.GET_MESSAGE_LENGTH_FROM_TX_IN_A.value, addrMessageLength));
+				// If message length matches, branch to sender checking code
+				codeByteBuffer.put(OpCode.BEQ_DAT.compile(addrMessageLength, addrExpectedRedeemMessageLength, calcOffset(codeByteBuffer, labelCheckRedeemTxnSender)));
+				// Message length didn't match - go back to finding another 'redeem' MESSAGE transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelRedeemTxnLoop == null ? 0 : labelRedeemTxnLoop));
+
+				/* Check transaction's sender */
+				labelCheckRedeemTxnSender = codeByteBuffer.position();
+
+				// Extract sender address from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_ADDRESS_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrMessageSender1 (as pointed to by addrMessageSenderPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageSenderPointer));
+				// Compare each part of transaction's sender's address with expected address. If they don't match, look for another transaction.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrQortalPartnerAddress1, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrQortalPartnerAddress2, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrQortalPartnerAddress3, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrQortalPartnerAddress4, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+
+				/* Check 'secret-A' in transaction's message */
+
+				// Extract secret-A from first 32 bytes of message from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_MESSAGE_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrMessageData (as pointed to by addrMessageDataPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageDataPointer));
+				// Load B register with expected hash result (as pointed to by addrHashOfSecretAPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.SET_B_IND, addrHashOfSecretAPointer));
+				// Perform HASH160 using source data at addrMessageData. (Location and length specified via addrMessageDataPointer and addrMessageDataLength).
+				// Save the equality result (1 if they match, 0 otherwise) into addrResult.
+				codeByteBuffer.put(OpCode.EXT_FUN_RET_DAT_2.compile(FunctionCode.CHECK_HASH160_WITH_B, addrResult, addrMessageDataPointer, addrMessageDataLength));
+				// If hashes don't match, addrResult will be zero so go find another transaction
+				codeByteBuffer.put(OpCode.BNZ_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelPayout)));
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelRedeemTxnLoop == null ? 0 : labelRedeemTxnLoop));
+
+				/* Success! Pay arranged amount to receiving address */
+				labelPayout = codeByteBuffer.position();
+
+				// Extract Qortal receiving address from next 32 bytes of message from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.PUT_PARTIAL_MESSAGE_FROM_TX_IN_A_INTO_B.value, addrRedeemMessageReceivingAddressOffset));
+				// Save B register into data segment starting at addrPartnerReceivingAddress (as pointed to by addrPartnerReceivingAddressPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrPartnerReceivingAddressPointer));
+				// Pay AT's balance to receiving address
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PAY_TO_ADDRESS_IN_B, addrQortAmount));
+				// Set redeemed mode
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.REDEEMED.value));
+				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
+				codeByteBuffer.put(OpCode.FIN_IMD.compile());
+
+				// Fall-through to refunding any remaining balance back to AT creator
+
+				/* Refund balance back to AT creator */
+				labelRefund = codeByteBuffer.position();
+
+				// Set refunded mode
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.REFUNDED.value));
+				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
+				codeByteBuffer.put(OpCode.FIN_IMD.compile());
+			} catch (CompilationException e) {
+				throw new IllegalStateException("Unable to compile DOGE-QORT ACCT?", e);
+			}
+		}
+
+		codeByteBuffer.flip();
+
+		byte[] codeBytes = new byte[codeByteBuffer.limit()];
+		codeByteBuffer.get(codeBytes);
+
+		assert Arrays.equals(Crypto.digest(codeBytes), DogecoinACCTv2.CODE_BYTES_HASH)
+			: String.format("BTCACCT.CODE_BYTES_HASH mismatch: expected %s, actual %s", HashCode.fromBytes(CODE_BYTES_HASH), HashCode.fromBytes(Crypto.digest(codeBytes)));
+
+		final short ciyamAtVersion = 2;
+		final short numCallStackPages = 0;
+		final short numUserStackPages = 0;
+		final long minActivationAmount = 0L;
+
+		return MachineState.toCreationBytes(ciyamAtVersion, codeBytes, dataByteBuffer.array(), numCallStackPages, numUserStackPages, minActivationAmount);
+	}
+
+	/**
+	 * Returns CrossChainTradeData with useful info extracted from AT.
+	 */
+	@Override
+	public CrossChainTradeData populateTradeData(Repository repository, ATData atData) throws DataException {
+		ATStateData atStateData = repository.getATRepository().getLatestATState(atData.getATAddress());
+		return populateTradeData(repository, atData.getCreatorPublicKey(), atData.getCreation(), atStateData);
+	}
+
+	/**
+	 * Returns CrossChainTradeData with useful info extracted from AT.
+	 */
+	@Override
+	public CrossChainTradeData populateTradeData(Repository repository, ATStateData atStateData) throws DataException {
+		ATData atData = repository.getATRepository().fromATAddress(atStateData.getATAddress());
+		return populateTradeData(repository, atData.getCreatorPublicKey(), atData.getCreation(), atStateData);
+	}
+
+	/**
+	 * Returns CrossChainTradeData with useful info extracted from AT.
+	 */
+	public CrossChainTradeData populateTradeData(Repository repository, byte[] creatorPublicKey, long creationTimestamp, ATStateData atStateData) throws DataException {
+		byte[] addressBytes = new byte[25]; // for general use
+		String atAddress = atStateData.getATAddress();
+
+		CrossChainTradeData tradeData = new CrossChainTradeData();
+
+		tradeData.foreignBlockchain = SupportedBlockchain.DOGECOIN.name();
+		tradeData.acctName = NAME;
+
+		tradeData.qortalAtAddress = atAddress;
+		tradeData.qortalCreator = Crypto.toAddress(creatorPublicKey);
+		tradeData.creationTimestamp = creationTimestamp;
+
+		Account atAccount = new Account(repository, atAddress);
+		tradeData.qortBalance = atAccount.getConfirmedBalance(Asset.QORT);
+
+		byte[] stateData = atStateData.getStateData();
+		ByteBuffer dataByteBuffer = ByteBuffer.wrap(stateData);
+		dataByteBuffer.position(MachineState.HEADER_LENGTH);
+
+		/* Constants */
+
+		// Skip creator's trade address
+		dataByteBuffer.get(addressBytes);
+		tradeData.qortalCreatorTradeAddress = Base58.encode(addressBytes);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - addressBytes.length);
+
+		// Creator's Dogecoin/foreign public key hash
+		tradeData.creatorForeignPKH = new byte[20];
+		dataByteBuffer.get(tradeData.creatorForeignPKH);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - tradeData.creatorForeignPKH.length); // skip to 32 bytes
+
+		// We don't use secret-B
+		tradeData.hashOfSecretB = null;
+
+		// Redeem payout
+		tradeData.qortAmount = dataByteBuffer.getLong();
+
+		// Expected DOGE amount
+		tradeData.expectedForeignAmount = dataByteBuffer.getLong();
+
+		// Trade timeout
+		tradeData.tradeTimeout = (int) dataByteBuffer.getLong();
+
+		// Skip MESSAGE transaction type
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip expected 'trade' message length
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip expected 'redeem' message length
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to creator's address
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to partner's Qortal trade address
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to message sender
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip 'trade' message data offset for partner's Dogecoin PKH
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to partner's Dogecoin PKH
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip 'trade' message data offset for hash-of-secret-A
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to hash-of-secret-A
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip 'redeem' message data offset for partner's Qortal receiving address
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to message data
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip message data length
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to partner's receiving address
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		/* End of constants / begin variables */
+
+		// Skip AT creator's address
+		dataByteBuffer.position(dataByteBuffer.position() + 8 * 4);
+
+		// Partner's trade address (if present)
+		dataByteBuffer.get(addressBytes);
+		String qortalRecipient = Base58.encode(addressBytes);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - addressBytes.length);
+
+		// Potential lockTimeA (if in trade mode)
+		int lockTimeA = (int) dataByteBuffer.getLong();
+
+		// AT refund timeout (probably only useful for debugging)
+		int refundTimeout = (int) dataByteBuffer.getLong();
+
+		// Trade-mode refund timestamp (AT 'timestamp' converted to Qortal block height)
+		long tradeRefundTimestamp = dataByteBuffer.getLong();
+
+		// Skip last transaction timestamp
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip block timestamp
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip transaction type
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip temporary result
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip temporary message sender
+		dataByteBuffer.position(dataByteBuffer.position() + 8 * 4);
+
+		// Skip message length
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip temporary message data
+		dataByteBuffer.position(dataByteBuffer.position() + 8 * 4);
+
+		// Potential hash160 of secret A
+		byte[] hashOfSecretA = new byte[20];
+		dataByteBuffer.get(hashOfSecretA);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - hashOfSecretA.length); // skip to 32 bytes
+
+		// Potential partner's Dogecoin PKH
+		byte[] partnerDogecoinPKH = new byte[20];
+		dataByteBuffer.get(partnerDogecoinPKH);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - partnerDogecoinPKH.length); // skip to 32 bytes
+
+		// Partner's receiving address (if present)
+		byte[] partnerReceivingAddress = new byte[25];
+		dataByteBuffer.get(partnerReceivingAddress);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - partnerReceivingAddress.length); // skip to 32 bytes
+
+		// Trade AT's 'mode'
+		long modeValue = dataByteBuffer.getLong();
+		AcctMode mode = AcctMode.valueOf((int) (modeValue & 0xffL));
+
+		/* End of variables */
+
+		if (mode != null && mode != AcctMode.OFFERING) {
+			tradeData.mode = mode;
+			tradeData.refundTimeout = refundTimeout;
+			tradeData.tradeRefundHeight = new Timestamp(tradeRefundTimestamp).blockHeight;
+			tradeData.qortalPartnerAddress = qortalRecipient;
+			tradeData.hashOfSecretA = hashOfSecretA;
+			tradeData.partnerForeignPKH = partnerDogecoinPKH;
+			tradeData.lockTimeA = lockTimeA;
+
+			if (mode == AcctMode.REDEEMED)
+				tradeData.qortalPartnerReceivingAddress = Base58.encode(partnerReceivingAddress);
+		} else {
+			tradeData.mode = AcctMode.OFFERING;
+		}
+
+		tradeData.duplicateDeprecated();
+
+		return tradeData;
+	}
+
+	/** Returns 'offer' MESSAGE payload for trade partner to send to AT creator's trade address. */
+	public static byte[] buildOfferMessage(byte[] partnerBitcoinPKH, byte[] hashOfSecretA, int lockTimeA) {
+		byte[] lockTimeABytes = BitTwiddling.toBEByteArray((long) lockTimeA);
+		return Bytes.concat(partnerBitcoinPKH, hashOfSecretA, lockTimeABytes);
+	}
+
+	/** Returns info extracted from 'offer' MESSAGE payload sent by trade partner to AT creator's trade address, or null if not valid. */
+	public static OfferMessageData extractOfferMessageData(byte[] messageData) {
+		if (messageData == null || messageData.length != OFFER_MESSAGE_LENGTH)
+			return null;
+
+		OfferMessageData offerMessageData = new OfferMessageData();
+		offerMessageData.partnerDogecoinPKH = Arrays.copyOfRange(messageData, 0, 20);
+		offerMessageData.hashOfSecretA = Arrays.copyOfRange(messageData, 20, 40);
+		offerMessageData.lockTimeA = BitTwiddling.longFromBEBytes(messageData, 40);
+
+		return offerMessageData;
+	}
+
+	/** Returns 'trade' MESSAGE payload for AT creator to send to AT. */
+	public static byte[] buildTradeMessage(String partnerQortalTradeAddress, byte[] partnerBitcoinPKH, byte[] hashOfSecretA, int lockTimeA, int refundTimeout) {
+		byte[] data = new byte[TRADE_MESSAGE_LENGTH];
+		byte[] partnerQortalAddressBytes = Base58.decode(partnerQortalTradeAddress);
+		byte[] lockTimeABytes = BitTwiddling.toBEByteArray((long) lockTimeA);
+		byte[] refundTimeoutBytes = BitTwiddling.toBEByteArray((long) refundTimeout);
+
+		System.arraycopy(partnerQortalAddressBytes, 0, data, 0, partnerQortalAddressBytes.length);
+		System.arraycopy(partnerBitcoinPKH, 0, data, 32, partnerBitcoinPKH.length);
+		System.arraycopy(refundTimeoutBytes, 0, data, 56, refundTimeoutBytes.length);
+		System.arraycopy(hashOfSecretA, 0, data, 64, hashOfSecretA.length);
+		System.arraycopy(lockTimeABytes, 0, data, 88, lockTimeABytes.length);
+
+		return data;
+	}
+
+	/** Returns 'cancel' MESSAGE payload for AT creator to cancel trade AT. */
+	@Override
+	public byte[] buildCancelMessage(String creatorQortalAddress) {
+		byte[] data = new byte[CANCEL_MESSAGE_LENGTH];
+		byte[] creatorQortalAddressBytes = Base58.decode(creatorQortalAddress);
+
+		System.arraycopy(creatorQortalAddressBytes, 0, data, 0, creatorQortalAddressBytes.length);
+
+		return data;
+	}
+
+	/** Returns 'redeem' MESSAGE payload for trade partner to send to AT. */
+	public static byte[] buildRedeemMessage(byte[] secretA, String qortalReceivingAddress) {
+		byte[] data = new byte[REDEEM_MESSAGE_LENGTH];
+		byte[] qortalReceivingAddressBytes = Base58.decode(qortalReceivingAddress);
+
+		System.arraycopy(secretA, 0, data, 0, secretA.length);
+		System.arraycopy(qortalReceivingAddressBytes, 0, data, 32, qortalReceivingAddressBytes.length);
+
+		return data;
+	}
+
+	/** Returns refund timeout (minutes) based on trade partner's 'offer' MESSAGE timestamp and P2SH-A locktime. */
+	public static int calcRefundTimeout(long offerMessageTimestamp, int lockTimeA) {
+		// refund should be triggered halfway between offerMessageTimestamp and lockTimeA
+		return (int) ((lockTimeA - (offerMessageTimestamp / 1000L)) / 2L / 60L);
+	}
+
+	@Override
+	public byte[] findSecretA(Repository repository, CrossChainTradeData crossChainTradeData) throws DataException {
+		String atAddress = crossChainTradeData.qortalAtAddress;
+		String redeemerAddress = crossChainTradeData.qortalPartnerAddress;
+
+		// We don't have partner's public key so we check every message to AT
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(null, atAddress, null, null, null);
+		if (messageTransactionsData == null)
+			return null;
+
+		// Find 'redeem' message
+		for (MessageTransactionData messageTransactionData : messageTransactionsData) {
+			// Check message payload type/encryption
+			if (messageTransactionData.isText() || messageTransactionData.isEncrypted())
+				continue;
+
+			// Check message payload size
+			byte[] messageData = messageTransactionData.getData();
+			if (messageData.length != REDEEM_MESSAGE_LENGTH)
+				// Wrong payload length
+				continue;
+
+			// Check sender
+			if (!Crypto.toAddress(messageTransactionData.getSenderPublicKey()).equals(redeemerAddress))
+				// Wrong sender;
+				continue;
+
+			// Extract secretA
+			byte[] secretA = new byte[32];
+			System.arraycopy(messageData, 0, secretA, 0, secretA.length);
+
+			byte[] hashOfSecretA = Crypto.hash160(secretA);
+			if (!Arrays.equals(hashOfSecretA, crossChainTradeData.hashOfSecretA))
+				continue;
+
+			return secretA;
+		}
+
+		return null;
+	}
+
+}

src/main/java/org/qortal/crosschain/DogecoinACCTv3.java

@@ -0,0 +1,858 @@
+package org.qortal.crosschain;
+
+import com.google.common.hash.HashCode;
+import com.google.common.primitives.Bytes;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.ciyam.at.*;
+import org.qortal.account.Account;
+import org.qortal.asset.Asset;
+import org.qortal.at.QortalFunctionCode;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.at.ATStateData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.utils.Base58;
+import org.qortal.utils.BitTwiddling;
+
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.List;
+
+import static org.ciyam.at.OpCode.calcOffset;
+
+/**
+ * Cross-chain trade AT
+ * 
+ * <p>
+ * <ul>
+ * <li>Bob generates Dogecoin & Qortal 'trade' keys
+ * 		<ul>
+ * 			<li>private key required to sign P2SH redeem tx</li>
+ * 			<li>private key could be used to create 'secret' (e.g. double-SHA256)</li>
+ * 			<li>encrypted private key could be stored in Qortal AT for access by Bob from any node</li>
+ * 		</ul>
+ * </li>
+ * <li>Bob deploys Qortal AT
+ * 		<ul>
+ * 		</ul>
+ * </li>
+ * <li>Alice finds Qortal AT and wants to trade
+ * 		<ul>
+ * 			<li>Alice generates Dogecoin & Qortal 'trade' keys</li>
+ * 			<li>Alice funds Dogecoin P2SH-A</li>
+ * 			<li>Alice sends 'offer' MESSAGE to Bob from her Qortal trade address, containing:
+ * 				<ul>
+ * 					<li>hash-of-secret-A</li>
+ * 					<li>her 'trade' Dogecoin PKH</li>
+ * 				</ul>
+ * 			</li>
+ * 		</ul>
+ * </li>
+ * <li>Bob receives "offer" MESSAGE
+ * 		<ul>
+ * 			<li>Checks Alice's P2SH-A</li>
+ * 			<li>Sends 'trade' MESSAGE to Qortal AT from his trade address, containing:
+ * 				<ul>
+ * 					<li>Alice's trade Qortal address</li>
+ * 					<li>Alice's trade Dogecoin PKH</li>
+ * 					<li>hash-of-secret-A</li>
+ * 				</ul>
+ * 			</li>
+ * 		</ul>
+ * </li>
+ * <li>Alice checks Qortal AT to confirm it's locked to her
+ * 		<ul>
+ * 			<li>Alice sends 'redeem' MESSAGE to Qortal AT from her trade address, containing:
+ * 				<ul>
+ * 					<li>secret-A</li>
+ * 					<li>Qortal receiving address of her chosing</li>
+ * 				</ul>
+ * 			</li>
+ * 			<li>AT's QORT funds are sent to Qortal receiving address</li>
+ * 		</ul>
+ * </li>
+ * <li>Bob checks AT, extracts secret-A
+ * 		<ul>
+ * 			<li>Bob redeems P2SH-A using his Dogecoin trade key and secret-A</li>
+ * 			<li>P2SH-A DOGE funds end up at Dogecoin address determined by redeem transaction output(s)</li>
+ * 		</ul>
+ * </li>
+ * </ul>
+ */
+public class DogecoinACCTv3 implements ACCT {
+
+	private static final Logger LOGGER = LogManager.getLogger(DogecoinACCTv3.class);
+
+	public static final String NAME = DogecoinACCTv3.class.getSimpleName();
+	public static final byte[] CODE_BYTES_HASH = HashCode.fromString("03b44087f6325463eb745aa32d9a782add03148bcfbe73ffd8854ce55ff863d4").asBytes(); // SHA256 of AT code bytes
+
+	public static final int SECRET_LENGTH = 32;
+
+	/** <b>Value</b> offset into AT segment where 'mode' variable (long) is stored. (Multiply by MachineState.VALUE_SIZE for byte offset). */
+	private static final int MODE_VALUE_OFFSET = 61;
+	/** <b>Byte</b> offset into AT state data where 'mode' variable (long) is stored. */
+	public static final int MODE_BYTE_OFFSET = MachineState.HEADER_LENGTH + (MODE_VALUE_OFFSET * MachineState.VALUE_SIZE);
+
+	public static class OfferMessageData {
+		public byte[] partnerDogecoinPKH;
+		public byte[] hashOfSecretA;
+		public long lockTimeA;
+	}
+	public static final int OFFER_MESSAGE_LENGTH = 20 /*partnerDogecoinPKH*/ + 20 /*hashOfSecretA*/ + 8 /*lockTimeA*/;
+	public static final int TRADE_MESSAGE_LENGTH = 32 /*partner's Qortal trade address (padded from 25 to 32)*/
+			+ 24 /*partner's Dogecoin PKH (padded from 20 to 24)*/
+			+ 8 /*AT trade timeout (minutes)*/
+			+ 24 /*hash of secret-A (padded from 20 to 24)*/
+			+ 8 /*lockTimeA*/;
+	public static final int REDEEM_MESSAGE_LENGTH = 32 /*secret-A*/ + 32 /*partner's Qortal receiving address padded from 25 to 32*/;
+	public static final int CANCEL_MESSAGE_LENGTH = 32 /*AT creator's Qortal address*/;
+
+	private static DogecoinACCTv3 instance;
+
+	private DogecoinACCTv3() {
+	}
+
+	public static synchronized DogecoinACCTv3 getInstance() {
+		if (instance == null)
+			instance = new DogecoinACCTv3();
+
+		return instance;
+	}
+
+	@Override
+	public byte[] getCodeBytesHash() {
+		return CODE_BYTES_HASH;
+	}
+
+	@Override
+	public int getModeByteOffset() {
+		return MODE_BYTE_OFFSET;
+	}
+
+	@Override
+	public ForeignBlockchain getBlockchain() {
+		return Dogecoin.getInstance();
+	}
+
+	/**
+	 * Returns Qortal AT creation bytes for cross-chain trading AT.
+	 * <p>
+	 * <tt>tradeTimeout</tt> (minutes) is the time window for the trade partner to send the
+	 * 32-byte secret to the AT, before the AT automatically refunds the AT's creator.
+	 * 
+	 * @param creatorTradeAddress AT creator's trade Qortal address
+	 * @param dogecoinPublicKeyHash 20-byte HASH160 of creator's trade Dogecoin public key
+	 * @param qortAmount how much QORT to pay trade partner if they send correct 32-byte secrets to AT
+	 * @param dogecoinAmount how much DOGE the AT creator is expecting to trade
+	 * @param tradeTimeout suggested timeout for entire trade
+	 */
+	public static byte[] buildQortalAT(String creatorTradeAddress, byte[] dogecoinPublicKeyHash, long qortAmount, long dogecoinAmount, int tradeTimeout) {
+		if (dogecoinPublicKeyHash.length != 20)
+			throw new IllegalArgumentException("Dogecoin public key hash should be 20 bytes");
+
+		// Labels for data segment addresses
+		int addrCounter = 0;
+
+		// Constants (with corresponding dataByteBuffer.put*() calls below)
+
+		final int addrCreatorTradeAddress1 = addrCounter++;
+		final int addrCreatorTradeAddress2 = addrCounter++;
+		final int addrCreatorTradeAddress3 = addrCounter++;
+		final int addrCreatorTradeAddress4 = addrCounter++;
+
+		final int addrDogecoinPublicKeyHash = addrCounter;
+		addrCounter += 4;
+
+		final int addrQortAmount = addrCounter++;
+		final int addrDogecoinAmount = addrCounter++;
+		final int addrTradeTimeout = addrCounter++;
+
+		final int addrMessageTxnType = addrCounter++;
+		final int addrExpectedTradeMessageLength = addrCounter++;
+		final int addrExpectedRedeemMessageLength = addrCounter++;
+
+		final int addrCreatorAddressPointer = addrCounter++;
+		final int addrQortalPartnerAddressPointer = addrCounter++;
+		final int addrMessageSenderPointer = addrCounter++;
+
+		final int addrTradeMessagePartnerDogecoinPKHOffset = addrCounter++;
+		final int addrPartnerDogecoinPKHPointer = addrCounter++;
+		final int addrTradeMessageHashOfSecretAOffset = addrCounter++;
+		final int addrHashOfSecretAPointer = addrCounter++;
+
+		final int addrRedeemMessageReceivingAddressOffset = addrCounter++;
+
+		final int addrMessageDataPointer = addrCounter++;
+		final int addrMessageDataLength = addrCounter++;
+
+		final int addrPartnerReceivingAddressPointer = addrCounter++;
+
+		final int addrEndOfConstants = addrCounter;
+
+		// Variables
+
+		final int addrCreatorAddress1 = addrCounter++;
+		final int addrCreatorAddress2 = addrCounter++;
+		final int addrCreatorAddress3 = addrCounter++;
+		final int addrCreatorAddress4 = addrCounter++;
+
+		final int addrQortalPartnerAddress1 = addrCounter++;
+		final int addrQortalPartnerAddress2 = addrCounter++;
+		final int addrQortalPartnerAddress3 = addrCounter++;
+		final int addrQortalPartnerAddress4 = addrCounter++;
+
+		final int addrLockTimeA = addrCounter++;
+		final int addrRefundTimeout = addrCounter++;
+		final int addrRefundTimestamp = addrCounter++;
+		final int addrLastTxnTimestamp = addrCounter++;
+		final int addrBlockTimestamp = addrCounter++;
+		final int addrTxnType = addrCounter++;
+		final int addrResult = addrCounter++;
+
+		final int addrMessageSender1 = addrCounter++;
+		final int addrMessageSender2 = addrCounter++;
+		final int addrMessageSender3 = addrCounter++;
+		final int addrMessageSender4 = addrCounter++;
+
+		final int addrMessageLength = addrCounter++;
+
+		final int addrMessageData = addrCounter;
+		addrCounter += 4;
+
+		final int addrHashOfSecretA = addrCounter;
+		addrCounter += 4;
+
+		final int addrPartnerDogecoinPKH = addrCounter;
+		addrCounter += 4;
+
+		final int addrPartnerReceivingAddress = addrCounter;
+		addrCounter += 4;
+
+		final int addrMode = addrCounter++;
+		assert addrMode == MODE_VALUE_OFFSET : String.format("addrMode %d does not match MODE_VALUE_OFFSET %d", addrMode, MODE_VALUE_OFFSET);
+
+		// Data segment
+		ByteBuffer dataByteBuffer = ByteBuffer.allocate(addrCounter * MachineState.VALUE_SIZE);
+
+		// AT creator's trade Qortal address, decoded from Base58
+		assert dataByteBuffer.position() == addrCreatorTradeAddress1 * MachineState.VALUE_SIZE : "addrCreatorTradeAddress1 incorrect";
+		byte[] creatorTradeAddressBytes = Base58.decode(creatorTradeAddress);
+		dataByteBuffer.put(Bytes.ensureCapacity(creatorTradeAddressBytes, 32, 0));
+
+		// Dogecoin public key hash
+		assert dataByteBuffer.position() == addrDogecoinPublicKeyHash * MachineState.VALUE_SIZE : "addrDogecoinPublicKeyHash incorrect";
+		dataByteBuffer.put(Bytes.ensureCapacity(dogecoinPublicKeyHash, 32, 0));
+
+		// Redeem Qort amount
+		assert dataByteBuffer.position() == addrQortAmount * MachineState.VALUE_SIZE : "addrQortAmount incorrect";
+		dataByteBuffer.putLong(qortAmount);
+
+		// Expected Dogecoin amount
+		assert dataByteBuffer.position() == addrDogecoinAmount * MachineState.VALUE_SIZE : "addrDogecoinAmount incorrect";
+		dataByteBuffer.putLong(dogecoinAmount);
+
+		// Suggested trade timeout (minutes)
+		assert dataByteBuffer.position() == addrTradeTimeout * MachineState.VALUE_SIZE : "addrTradeTimeout incorrect";
+		dataByteBuffer.putLong(tradeTimeout);
+
+		// We're only interested in MESSAGE transactions
+		assert dataByteBuffer.position() == addrMessageTxnType * MachineState.VALUE_SIZE : "addrMessageTxnType incorrect";
+		dataByteBuffer.putLong(API.ATTransactionType.MESSAGE.value);
+
+		// Expected length of 'trade' MESSAGE data from AT creator
+		assert dataByteBuffer.position() == addrExpectedTradeMessageLength * MachineState.VALUE_SIZE : "addrExpectedTradeMessageLength incorrect";
+		dataByteBuffer.putLong(TRADE_MESSAGE_LENGTH);
+
+		// Expected length of 'redeem' MESSAGE data from trade partner
+		assert dataByteBuffer.position() == addrExpectedRedeemMessageLength * MachineState.VALUE_SIZE : "addrExpectedRedeemMessageLength incorrect";
+		dataByteBuffer.putLong(REDEEM_MESSAGE_LENGTH);
+
+		// Index into data segment of AT creator's address, used by GET_B_IND
+		assert dataByteBuffer.position() == addrCreatorAddressPointer * MachineState.VALUE_SIZE : "addrCreatorAddressPointer incorrect";
+		dataByteBuffer.putLong(addrCreatorAddress1);
+
+		// Index into data segment of partner's Qortal address, used by SET_B_IND
+		assert dataByteBuffer.position() == addrQortalPartnerAddressPointer * MachineState.VALUE_SIZE : "addrQortalPartnerAddressPointer incorrect";
+		dataByteBuffer.putLong(addrQortalPartnerAddress1);
+
+		// Index into data segment of (temporary) transaction's sender's address, used by GET_B_IND
+		assert dataByteBuffer.position() == addrMessageSenderPointer * MachineState.VALUE_SIZE : "addrMessageSenderPointer incorrect";
+		dataByteBuffer.putLong(addrMessageSender1);
+
+		// Offset into 'trade' MESSAGE data payload for extracting partner's Dogecoin PKH
+		assert dataByteBuffer.position() == addrTradeMessagePartnerDogecoinPKHOffset * MachineState.VALUE_SIZE : "addrTradeMessagePartnerDogecoinPKHOffset incorrect";
+		dataByteBuffer.putLong(32L);
+
+		// Index into data segment of partner's Dogecoin PKH, used by GET_B_IND
+		assert dataByteBuffer.position() == addrPartnerDogecoinPKHPointer * MachineState.VALUE_SIZE : "addrPartnerDogecoinPKHPointer incorrect";
+		dataByteBuffer.putLong(addrPartnerDogecoinPKH);
+
+		// Offset into 'trade' MESSAGE data payload for extracting hash-of-secret-A
+		assert dataByteBuffer.position() == addrTradeMessageHashOfSecretAOffset * MachineState.VALUE_SIZE : "addrTradeMessageHashOfSecretAOffset incorrect";
+		dataByteBuffer.putLong(64L);
+
+		// Index into data segment to hash of secret A, used by GET_B_IND
+		assert dataByteBuffer.position() == addrHashOfSecretAPointer * MachineState.VALUE_SIZE : "addrHashOfSecretAPointer incorrect";
+		dataByteBuffer.putLong(addrHashOfSecretA);
+
+		// Offset into 'redeem' MESSAGE data payload for extracting Qortal receiving address
+		assert dataByteBuffer.position() == addrRedeemMessageReceivingAddressOffset * MachineState.VALUE_SIZE : "addrRedeemMessageReceivingAddressOffset incorrect";
+		dataByteBuffer.putLong(32L);
+
+		// Source location and length for hashing any passed secret
+		assert dataByteBuffer.position() == addrMessageDataPointer * MachineState.VALUE_SIZE : "addrMessageDataPointer incorrect";
+		dataByteBuffer.putLong(addrMessageData);
+		assert dataByteBuffer.position() == addrMessageDataLength * MachineState.VALUE_SIZE : "addrMessageDataLength incorrect";
+		dataByteBuffer.putLong(32L);
+
+		// Pointer into data segment of where to save partner's receiving Qortal address, used by GET_B_IND
+		assert dataByteBuffer.position() == addrPartnerReceivingAddressPointer * MachineState.VALUE_SIZE : "addrPartnerReceivingAddressPointer incorrect";
+		dataByteBuffer.putLong(addrPartnerReceivingAddress);
+
+		assert dataByteBuffer.position() == addrEndOfConstants * MachineState.VALUE_SIZE : "dataByteBuffer position not at end of constants";
+
+		// Code labels
+		Integer labelRefund = null;
+
+		Integer labelTradeTxnLoop = null;
+		Integer labelCheckTradeTxn = null;
+		Integer labelCheckCancelTxn = null;
+		Integer labelNotTradeNorCancelTxn = null;
+		Integer labelCheckNonRefundTradeTxn = null;
+		Integer labelTradeTxnExtract = null;
+		Integer labelRedeemTxnLoop = null;
+		Integer labelCheckRedeemTxn = null;
+		Integer labelCheckRedeemTxnSender = null;
+		Integer labelPayout = null;
+
+		ByteBuffer codeByteBuffer = ByteBuffer.allocate(768);
+
+		// Two-pass version
+		for (int pass = 0; pass < 2; ++pass) {
+			codeByteBuffer.clear();
+
+			try {
+				/* Initialization */
+
+				/* NOP - to ensure DOGECOIN ACCT is unique */
+				codeByteBuffer.put(OpCode.NOP.compile());
+
+				// Use AT creation 'timestamp' as starting point for finding transactions sent to AT
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_CREATION_TIMESTAMP, addrLastTxnTimestamp));
+
+				// Load B register with AT creator's address so we can save it into addrCreatorAddress1-4
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_CREATOR_INTO_B));
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrCreatorAddressPointer));
+
+				// Set restart position to after this opcode
+				codeByteBuffer.put(OpCode.SET_PCS.compile());
+
+				/* Loop, waiting for message from AT creator's trade address containing trade partner details, or AT owner's address to cancel offer */
+
+				/* Transaction processing loop */
+				labelTradeTxnLoop = codeByteBuffer.position();
+
+				/* Sleep until message arrives */
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.SLEEP_UNTIL_MESSAGE.value, addrLastTxnTimestamp));
+
+				// Find next transaction (if any) to this AT since the last one (referenced by addrLastTxnTimestamp)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PUT_TX_AFTER_TIMESTAMP_INTO_A, addrLastTxnTimestamp));
+				// If no transaction found, A will be zero. If A is zero, set addrResult to 1, otherwise 0.
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.CHECK_A_IS_ZERO, addrResult));
+				// If addrResult is zero (i.e. A is non-zero, transaction was found) then go check transaction
+				codeByteBuffer.put(OpCode.BZR_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelCheckTradeTxn)));
+				// Stop and wait for next block
+				codeByteBuffer.put(OpCode.STP_IMD.compile());
+
+				/* Check transaction */
+				labelCheckTradeTxn = codeByteBuffer.position();
+
+				// Update our 'last found transaction's timestamp' using 'timestamp' from transaction
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TIMESTAMP_FROM_TX_IN_A, addrLastTxnTimestamp));
+				// Extract transaction type (message/payment) from transaction and save type in addrTxnType
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TYPE_FROM_TX_IN_A, addrTxnType));
+				// If transaction type is not MESSAGE type then go look for another transaction
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrTxnType, addrMessageTxnType, calcOffset(codeByteBuffer, labelTradeTxnLoop)));
+
+				/* Check transaction's sender. We're expecting AT creator's trade address for 'trade' message, or AT creator's own address for 'cancel' message. */
+
+				// Extract sender address from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_ADDRESS_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrMessageSender1 (as pointed to by addrMessageSenderPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageSenderPointer));
+				// Compare each part of message sender's address with AT creator's trade address. If they don't match, check for cancel situation.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrCreatorTradeAddress1, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrCreatorTradeAddress2, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrCreatorTradeAddress3, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrCreatorTradeAddress4, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				// Message sender's address matches AT creator's trade address so go process 'trade' message
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelCheckNonRefundTradeTxn == null ? 0 : labelCheckNonRefundTradeTxn));
+
+				/* Checking message sender for possible cancel message */
+				labelCheckCancelTxn = codeByteBuffer.position();
+
+				// Compare each part of message sender's address with AT creator's address. If they don't match, look for another transaction.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrCreatorAddress1, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrCreatorAddress2, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrCreatorAddress3, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrCreatorAddress4, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				// Partner address is AT creator's address, so cancel offer and finish.
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.CANCELLED.value));
+				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
+				codeByteBuffer.put(OpCode.FIN_IMD.compile());
+
+				/* Not trade nor cancel message */
+				labelNotTradeNorCancelTxn = codeByteBuffer.position();
+
+				// Loop to find another transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelTradeTxnLoop == null ? 0 : labelTradeTxnLoop));
+
+				/* Possible switch-to-trade-mode message */
+				labelCheckNonRefundTradeTxn = codeByteBuffer.position();
+
+				// Check 'trade' message we received has expected number of message bytes
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(QortalFunctionCode.GET_MESSAGE_LENGTH_FROM_TX_IN_A.value, addrMessageLength));
+				// If message length matches, branch to info extraction code
+				codeByteBuffer.put(OpCode.BEQ_DAT.compile(addrMessageLength, addrExpectedTradeMessageLength, calcOffset(codeByteBuffer, labelTradeTxnExtract)));
+				// Message length didn't match - go back to finding another 'trade' MESSAGE transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelTradeTxnLoop == null ? 0 : labelTradeTxnLoop));
+
+				/* Extracting info from 'trade' MESSAGE transaction */
+				labelTradeTxnExtract = codeByteBuffer.position();
+
+				// Extract message from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_MESSAGE_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrQortalPartnerAddress1 (as pointed to by addrQortalPartnerAddressPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrQortalPartnerAddressPointer));
+
+				// Extract trade partner's Dogecoin public key hash (PKH) from message into B
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.PUT_PARTIAL_MESSAGE_FROM_TX_IN_A_INTO_B.value, addrTradeMessagePartnerDogecoinPKHOffset));
+				// Store partner's Dogecoin PKH (we only really use values from B1-B3)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrPartnerDogecoinPKHPointer));
+				// Extract AT trade timeout (minutes) (from B4)
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_B4, addrRefundTimeout));
+
+				// Grab next 32 bytes
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.PUT_PARTIAL_MESSAGE_FROM_TX_IN_A_INTO_B.value, addrTradeMessageHashOfSecretAOffset));
+
+				// Extract hash-of-secret-A (we only really use values from B1-B3)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrHashOfSecretAPointer));
+				// Extract lockTime-A (from B4)
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_B4, addrLockTimeA));
+
+				// Calculate trade timeout refund 'timestamp' by adding addrRefundTimeout minutes to this transaction's 'timestamp', then save into addrRefundTimestamp
+				codeByteBuffer.put(OpCode.EXT_FUN_RET_DAT_2.compile(FunctionCode.ADD_MINUTES_TO_TIMESTAMP, addrRefundTimestamp, addrLastTxnTimestamp, addrRefundTimeout));
+
+				/* We are in 'trade mode' */
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.TRADING.value));
+
+				// Set restart position to after this opcode
+				codeByteBuffer.put(OpCode.SET_PCS.compile());
+
+				/* Loop, waiting for trade timeout or 'redeem' MESSAGE from Qortal trade partner */
+
+				// Fetch current block 'timestamp'
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_BLOCK_TIMESTAMP, addrBlockTimestamp));
+				// If we're not past refund 'timestamp' then look for next transaction
+				codeByteBuffer.put(OpCode.BLT_DAT.compile(addrBlockTimestamp, addrRefundTimestamp, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+				// We're past refund 'timestamp' so go refund everything back to AT creator
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelRefund == null ? 0 : labelRefund));
+
+				/* Transaction processing loop */
+				labelRedeemTxnLoop = codeByteBuffer.position();
+
+				// Find next transaction to this AT since the last one (if any)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PUT_TX_AFTER_TIMESTAMP_INTO_A, addrLastTxnTimestamp));
+				// If no transaction found, A will be zero. If A is zero, set addrComparator to 1, otherwise 0.
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.CHECK_A_IS_ZERO, addrResult));
+				// If addrResult is zero (i.e. A is non-zero, transaction was found) then go check transaction
+				codeByteBuffer.put(OpCode.BZR_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelCheckRedeemTxn)));
+				// Stop and wait for next block
+				codeByteBuffer.put(OpCode.STP_IMD.compile());
+
+				/* Check transaction */
+				labelCheckRedeemTxn = codeByteBuffer.position();
+
+				// Update our 'last found transaction's timestamp' using 'timestamp' from transaction
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TIMESTAMP_FROM_TX_IN_A, addrLastTxnTimestamp));
+				// Extract transaction type (message/payment) from transaction and save type in addrTxnType
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TYPE_FROM_TX_IN_A, addrTxnType));
+				// If transaction type is not MESSAGE type then go look for another transaction
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrTxnType, addrMessageTxnType, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+
+				/* Check message payload length */
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(QortalFunctionCode.GET_MESSAGE_LENGTH_FROM_TX_IN_A.value, addrMessageLength));
+				// If message length matches, branch to sender checking code
+				codeByteBuffer.put(OpCode.BEQ_DAT.compile(addrMessageLength, addrExpectedRedeemMessageLength, calcOffset(codeByteBuffer, labelCheckRedeemTxnSender)));
+				// Message length didn't match - go back to finding another 'redeem' MESSAGE transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelRedeemTxnLoop == null ? 0 : labelRedeemTxnLoop));
+
+				/* Check transaction's sender */
+				labelCheckRedeemTxnSender = codeByteBuffer.position();
+
+				// Extract sender address from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_ADDRESS_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrMessageSender1 (as pointed to by addrMessageSenderPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageSenderPointer));
+				// Compare each part of transaction's sender's address with expected address. If they don't match, look for another transaction.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrQortalPartnerAddress1, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrQortalPartnerAddress2, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrQortalPartnerAddress3, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrQortalPartnerAddress4, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+
+				/* Check 'secret-A' in transaction's message */
+
+				// Extract secret-A from first 32 bytes of message from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_MESSAGE_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrMessageData (as pointed to by addrMessageDataPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageDataPointer));
+				// Load B register with expected hash result (as pointed to by addrHashOfSecretAPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.SET_B_IND, addrHashOfSecretAPointer));
+				// Perform HASH160 using source data at addrMessageData. (Location and length specified via addrMessageDataPointer and addrMessageDataLength).
+				// Save the equality result (1 if they match, 0 otherwise) into addrResult.
+				codeByteBuffer.put(OpCode.EXT_FUN_RET_DAT_2.compile(FunctionCode.CHECK_HASH160_WITH_B, addrResult, addrMessageDataPointer, addrMessageDataLength));
+				// If hashes don't match, addrResult will be zero so go find another transaction
+				codeByteBuffer.put(OpCode.BNZ_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelPayout)));
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelRedeemTxnLoop == null ? 0 : labelRedeemTxnLoop));
+
+				/* Success! Pay arranged amount to receiving address */
+				labelPayout = codeByteBuffer.position();
+
+				// Extract Qortal receiving address from next 32 bytes of message from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.PUT_PARTIAL_MESSAGE_FROM_TX_IN_A_INTO_B.value, addrRedeemMessageReceivingAddressOffset));
+				// Save B register into data segment starting at addrPartnerReceivingAddress (as pointed to by addrPartnerReceivingAddressPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrPartnerReceivingAddressPointer));
+				// Pay AT's balance to receiving address
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PAY_TO_ADDRESS_IN_B, addrQortAmount));
+				// Set redeemed mode
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.REDEEMED.value));
+				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
+				codeByteBuffer.put(OpCode.FIN_IMD.compile());
+
+				// Fall-through to refunding any remaining balance back to AT creator
+
+				/* Refund balance back to AT creator */
+				labelRefund = codeByteBuffer.position();
+
+				// Set refunded mode
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.REFUNDED.value));
+				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
+				codeByteBuffer.put(OpCode.FIN_IMD.compile());
+			} catch (CompilationException e) {
+				throw new IllegalStateException("Unable to compile DOGE-QORT ACCT?", e);
+			}
+		}
+
+		codeByteBuffer.flip();
+
+		byte[] codeBytes = new byte[codeByteBuffer.limit()];
+		codeByteBuffer.get(codeBytes);
+
+		assert Arrays.equals(Crypto.digest(codeBytes), DogecoinACCTv3.CODE_BYTES_HASH)
+			: String.format("BTCACCT.CODE_BYTES_HASH mismatch: expected %s, actual %s", HashCode.fromBytes(CODE_BYTES_HASH), HashCode.fromBytes(Crypto.digest(codeBytes)));
+
+		final short ciyamAtVersion = 2;
+		final short numCallStackPages = 0;
+		final short numUserStackPages = 0;
+		final long minActivationAmount = 0L;
+
+		return MachineState.toCreationBytes(ciyamAtVersion, codeBytes, dataByteBuffer.array(), numCallStackPages, numUserStackPages, minActivationAmount);
+	}
+
+	/**
+	 * Returns CrossChainTradeData with useful info extracted from AT.
+	 */
+	@Override
+	public CrossChainTradeData populateTradeData(Repository repository, ATData atData) throws DataException {
+		ATStateData atStateData = repository.getATRepository().getLatestATState(atData.getATAddress());
+		return populateTradeData(repository, atData.getCreatorPublicKey(), atData.getCreation(), atStateData);
+	}
+
+	/**
+	 * Returns CrossChainTradeData with useful info extracted from AT.
+	 */
+	@Override
+	public CrossChainTradeData populateTradeData(Repository repository, ATStateData atStateData) throws DataException {
+		ATData atData = repository.getATRepository().fromATAddress(atStateData.getATAddress());
+		return populateTradeData(repository, atData.getCreatorPublicKey(), atData.getCreation(), atStateData);
+	}
+
+	/**
+	 * Returns CrossChainTradeData with useful info extracted from AT.
+	 */
+	public CrossChainTradeData populateTradeData(Repository repository, byte[] creatorPublicKey, long creationTimestamp, ATStateData atStateData) throws DataException {
+		byte[] addressBytes = new byte[25]; // for general use
+		String atAddress = atStateData.getATAddress();
+
+		CrossChainTradeData tradeData = new CrossChainTradeData();
+
+		tradeData.foreignBlockchain = SupportedBlockchain.DOGECOIN.name();
+		tradeData.acctName = NAME;
+
+		tradeData.qortalAtAddress = atAddress;
+		tradeData.qortalCreator = Crypto.toAddress(creatorPublicKey);
+		tradeData.creationTimestamp = creationTimestamp;
+
+		Account atAccount = new Account(repository, atAddress);
+		tradeData.qortBalance = atAccount.getConfirmedBalance(Asset.QORT);
+
+		byte[] stateData = atStateData.getStateData();
+		ByteBuffer dataByteBuffer = ByteBuffer.wrap(stateData);
+		dataByteBuffer.position(MachineState.HEADER_LENGTH);
+
+		/* Constants */
+
+		// Skip creator's trade address
+		dataByteBuffer.get(addressBytes);
+		tradeData.qortalCreatorTradeAddress = Base58.encode(addressBytes);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - addressBytes.length);
+
+		// Creator's Dogecoin/foreign public key hash
+		tradeData.creatorForeignPKH = new byte[20];
+		dataByteBuffer.get(tradeData.creatorForeignPKH);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - tradeData.creatorForeignPKH.length); // skip to 32 bytes
+
+		// We don't use secret-B
+		tradeData.hashOfSecretB = null;
+
+		// Redeem payout
+		tradeData.qortAmount = dataByteBuffer.getLong();
+
+		// Expected DOGE amount
+		tradeData.expectedForeignAmount = dataByteBuffer.getLong();
+
+		// Trade timeout
+		tradeData.tradeTimeout = (int) dataByteBuffer.getLong();
+
+		// Skip MESSAGE transaction type
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip expected 'trade' message length
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip expected 'redeem' message length
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to creator's address
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to partner's Qortal trade address
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to message sender
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip 'trade' message data offset for partner's Dogecoin PKH
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to partner's Dogecoin PKH
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip 'trade' message data offset for hash-of-secret-A
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to hash-of-secret-A
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip 'redeem' message data offset for partner's Qortal receiving address
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to message data
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip message data length
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to partner's receiving address
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		/* End of constants / begin variables */
+
+		// Skip AT creator's address
+		dataByteBuffer.position(dataByteBuffer.position() + 8 * 4);
+
+		// Partner's trade address (if present)
+		dataByteBuffer.get(addressBytes);
+		String qortalRecipient = Base58.encode(addressBytes);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - addressBytes.length);
+
+		// Potential lockTimeA (if in trade mode)
+		int lockTimeA = (int) dataByteBuffer.getLong();
+
+		// AT refund timeout (probably only useful for debugging)
+		int refundTimeout = (int) dataByteBuffer.getLong();
+
+		// Trade-mode refund timestamp (AT 'timestamp' converted to Qortal block height)
+		long tradeRefundTimestamp = dataByteBuffer.getLong();
+
+		// Skip last transaction timestamp
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip block timestamp
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip transaction type
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip temporary result
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip temporary message sender
+		dataByteBuffer.position(dataByteBuffer.position() + 8 * 4);
+
+		// Skip message length
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip temporary message data
+		dataByteBuffer.position(dataByteBuffer.position() + 8 * 4);
+
+		// Potential hash160 of secret A
+		byte[] hashOfSecretA = new byte[20];
+		dataByteBuffer.get(hashOfSecretA);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - hashOfSecretA.length); // skip to 32 bytes
+
+		// Potential partner's Dogecoin PKH
+		byte[] partnerDogecoinPKH = new byte[20];
+		dataByteBuffer.get(partnerDogecoinPKH);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - partnerDogecoinPKH.length); // skip to 32 bytes
+
+		// Partner's receiving address (if present)
+		byte[] partnerReceivingAddress = new byte[25];
+		dataByteBuffer.get(partnerReceivingAddress);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - partnerReceivingAddress.length); // skip to 32 bytes
+
+		// Trade AT's 'mode'
+		long modeValue = dataByteBuffer.getLong();
+		AcctMode mode = AcctMode.valueOf((int) (modeValue & 0xffL));
+
+		/* End of variables */
+
+		if (mode != null && mode != AcctMode.OFFERING) {
+			tradeData.mode = mode;
+			tradeData.refundTimeout = refundTimeout;
+			tradeData.tradeRefundHeight = new Timestamp(tradeRefundTimestamp).blockHeight;
+			tradeData.qortalPartnerAddress = qortalRecipient;
+			tradeData.hashOfSecretA = hashOfSecretA;
+			tradeData.partnerForeignPKH = partnerDogecoinPKH;
+			tradeData.lockTimeA = lockTimeA;
+
+			if (mode == AcctMode.REDEEMED)
+				tradeData.qortalPartnerReceivingAddress = Base58.encode(partnerReceivingAddress);
+		} else {
+			tradeData.mode = AcctMode.OFFERING;
+		}
+
+		tradeData.duplicateDeprecated();
+
+		return tradeData;
+	}
+
+	/** Returns 'offer' MESSAGE payload for trade partner to send to AT creator's trade address. */
+	public static byte[] buildOfferMessage(byte[] partnerBitcoinPKH, byte[] hashOfSecretA, int lockTimeA) {
+		byte[] lockTimeABytes = BitTwiddling.toBEByteArray((long) lockTimeA);
+		return Bytes.concat(partnerBitcoinPKH, hashOfSecretA, lockTimeABytes);
+	}
+
+	/** Returns info extracted from 'offer' MESSAGE payload sent by trade partner to AT creator's trade address, or null if not valid. */
+	public static OfferMessageData extractOfferMessageData(byte[] messageData) {
+		if (messageData == null || messageData.length != OFFER_MESSAGE_LENGTH)
+			return null;
+
+		OfferMessageData offerMessageData = new OfferMessageData();
+		offerMessageData.partnerDogecoinPKH = Arrays.copyOfRange(messageData, 0, 20);
+		offerMessageData.hashOfSecretA = Arrays.copyOfRange(messageData, 20, 40);
+		offerMessageData.lockTimeA = BitTwiddling.longFromBEBytes(messageData, 40);
+
+		return offerMessageData;
+	}
+
+	/** Returns 'trade' MESSAGE payload for AT creator to send to AT. */
+	public static byte[] buildTradeMessage(String partnerQortalTradeAddress, byte[] partnerBitcoinPKH, byte[] hashOfSecretA, int lockTimeA, int refundTimeout) {
+		byte[] data = new byte[TRADE_MESSAGE_LENGTH];
+		byte[] partnerQortalAddressBytes = Base58.decode(partnerQortalTradeAddress);
+		byte[] lockTimeABytes = BitTwiddling.toBEByteArray((long) lockTimeA);
+		byte[] refundTimeoutBytes = BitTwiddling.toBEByteArray((long) refundTimeout);
+
+		System.arraycopy(partnerQortalAddressBytes, 0, data, 0, partnerQortalAddressBytes.length);
+		System.arraycopy(partnerBitcoinPKH, 0, data, 32, partnerBitcoinPKH.length);
+		System.arraycopy(refundTimeoutBytes, 0, data, 56, refundTimeoutBytes.length);
+		System.arraycopy(hashOfSecretA, 0, data, 64, hashOfSecretA.length);
+		System.arraycopy(lockTimeABytes, 0, data, 88, lockTimeABytes.length);
+
+		return data;
+	}
+
+	/** Returns 'cancel' MESSAGE payload for AT creator to cancel trade AT. */
+	@Override
+	public byte[] buildCancelMessage(String creatorQortalAddress) {
+		byte[] data = new byte[CANCEL_MESSAGE_LENGTH];
+		byte[] creatorQortalAddressBytes = Base58.decode(creatorQortalAddress);
+
+		System.arraycopy(creatorQortalAddressBytes, 0, data, 0, creatorQortalAddressBytes.length);
+
+		return data;
+	}
+
+	/** Returns 'redeem' MESSAGE payload for trade partner to send to AT. */
+	public static byte[] buildRedeemMessage(byte[] secretA, String qortalReceivingAddress) {
+		byte[] data = new byte[REDEEM_MESSAGE_LENGTH];
+		byte[] qortalReceivingAddressBytes = Base58.decode(qortalReceivingAddress);
+
+		System.arraycopy(secretA, 0, data, 0, secretA.length);
+		System.arraycopy(qortalReceivingAddressBytes, 0, data, 32, qortalReceivingAddressBytes.length);
+
+		return data;
+	}
+
+	/** Returns refund timeout (minutes) based on trade partner's 'offer' MESSAGE timestamp and P2SH-A locktime. */
+	public static int calcRefundTimeout(long offerMessageTimestamp, int lockTimeA) {
+		// refund should be triggered halfway between offerMessageTimestamp and lockTimeA
+		return (int) ((lockTimeA - (offerMessageTimestamp / 1000L)) / 2L / 60L);
+	}
+
+	@Override
+	public byte[] findSecretA(Repository repository, CrossChainTradeData crossChainTradeData) throws DataException {
+		String atAddress = crossChainTradeData.qortalAtAddress;
+		String redeemerAddress = crossChainTradeData.qortalPartnerAddress;
+
+		// We don't have partner's public key so we check every message to AT
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(null, atAddress, null, null, null);
+		if (messageTransactionsData == null)
+			return null;
+
+		// Find 'redeem' message
+		for (MessageTransactionData messageTransactionData : messageTransactionsData) {
+			// Check message payload type/encryption
+			if (messageTransactionData.isText() || messageTransactionData.isEncrypted())
+				continue;
+
+			// Check message payload size
+			byte[] messageData = messageTransactionData.getData();
+			if (messageData.length != REDEEM_MESSAGE_LENGTH)
+				// Wrong payload length
+				continue;
+
+			// Check sender
+			if (!Crypto.toAddress(messageTransactionData.getSenderPublicKey()).equals(redeemerAddress))
+				// Wrong sender;
+				continue;
+
+			// Extract secretA
+			byte[] secretA = new byte[32];
+			System.arraycopy(messageData, 0, secretA, 0, secretA.length);
+
+			byte[] hashOfSecretA = Crypto.hash160(secretA);
+			if (!Arrays.equals(hashOfSecretA, crossChainTradeData.hashOfSecretA))
+				continue;
+
+			return secretA;
+		}
+
+		return null;
+	}
+
+}

src/main/java/org/qortal/crosschain/ElectrumX.java

@@ -1,13 +1,17 @@
 package org.qortal.crosschain;
 
 import java.io.IOException;
+import java.math.BigDecimal;
 import java.net.InetSocketAddress;
 import java.net.Socket;
 import java.net.SocketAddress;
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.HashMap;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.EnumMap;
 import java.util.HashSet;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.NoSuchElementException;
@@ -29,34 +33,27 @@ import org.qortal.crypto.TrustlessSSLSocketFactory;
 
 import com.google.common.hash.HashCode;
 import com.google.common.primitives.Bytes;
+import org.qortal.utils.BitTwiddling;
 
-/** ElectrumX network support for querying Bitcoin-related info like block headers, transaction outputs, etc. */
-public class ElectrumX {
+/** ElectrumX network support for querying Bitcoiny-related info like block headers, transaction outputs, etc. */
+public class ElectrumX extends BitcoinyBlockchainProvider {
 
 	private static final Logger LOGGER = LogManager.getLogger(ElectrumX.class);
 	private static final Random RANDOM = new Random();
 
 	private static final double MIN_PROTOCOL_VERSION = 1.2;
-
-	private static final int DEFAULT_TCP_PORT = 50001;
-	private static final int DEFAULT_SSL_PORT = 50002;
-
 	private static final int BLOCK_HEADER_LENGTH = 80;
 
-	private static final String MAIN_GENESIS_HASH = "000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f";
-	private static final String TEST3_GENESIS_HASH = "000000000933ea01ad0ee984209779baaec3ced90fa3f408719526f8d77f4943";
-	// We won't know REGTEST (i.e. local) genesis block hash
-
 	// "message": "daemon error: DaemonError({'code': -5, 'message': 'No such mempool or blockchain transaction. Use gettransaction for wallet transactions.'})"
 	private static final Pattern DAEMON_ERROR_REGEX = Pattern.compile("DaemonError\\(\\{.*'code': ?(-?[0-9]+).*\\}\\)\\z"); // Capture 'code' inside curly-brace content
 
-	// Key: Bitcoin network (e.g. "MAIN", "TEST3", "REGTEST"), value: ElectrumX instance
-	private static final Map<String, ElectrumX> instances = new HashMap<>();
+	/** Error message sent by some ElectrumX servers when they don't support returning verbose transactions. */
+	private static final String VERBOSE_TRANSACTIONS_UNSUPPORTED_MESSAGE = "verbose transactions are currently unsupported";
 
-	private static class Server {
+	public static class Server {
 		String hostname;
 
-		enum ConnectionType { TCP, SSL }
+		public enum ConnectionType { TCP, SSL }
 		ConnectionType connectionType;
 
 		int port;
@@ -94,108 +91,61 @@ public class ElectrumX {
 	}
 	private Set<Server> servers = new HashSet<>();
 	private List<Server> remainingServers = new ArrayList<>();
+	private Set<Server> uselessServers = Collections.synchronizedSet(new HashSet<>());
 
-	private String expectedGenesisHash;
+	private final String netId;
+	private final String expectedGenesisHash;
+	private final Map<Server.ConnectionType, Integer> defaultPorts = new EnumMap<>(Server.ConnectionType.class);
+
+	private final Object serverLock = new Object();
 	private Server currentServer;
 	private Socket socket;
 	private Scanner scanner;
 	private int nextId = 1;
 
+	private static final int TX_CACHE_SIZE = 200;
+	@SuppressWarnings("serial")
+	private final Map<String, BitcoinyTransaction> transactionCache = Collections.synchronizedMap(new LinkedHashMap<>(TX_CACHE_SIZE + 1, 0.75F, true) {
+		// This method is called just after a new entry has been added
+		@Override
+		public boolean removeEldestEntry(Map.Entry<String, BitcoinyTransaction> eldest) {
+			return size() > TX_CACHE_SIZE;
+		}
+	});
+
 	// Constructors
 
-	private ElectrumX(String bitcoinNetwork) {
-		switch (bitcoinNetwork) {
-			case "MAIN":
-				this.expectedGenesisHash = MAIN_GENESIS_HASH;
-
-				this.servers.addAll(Arrays.asList(
-						// Servers chosen on NO BASIS WHATSOEVER from various sources!
-						new Server("enode.duckdns.org", Server.ConnectionType.SSL, 50002),
-						new Server("electrumx.ml", Server.ConnectionType.SSL, 50002),
-						new Server("electrum.bitkoins.nl", Server.ConnectionType.SSL, 50512),
-						new Server("btc.electroncash.dk", Server.ConnectionType.SSL, 60002),
-						new Server("electrumx.electricnewyear.net", Server.ConnectionType.SSL, 50002),
-						new Server("dxm.no-ip.biz", Server.ConnectionType.TCP, 50001),
-						new Server("kirsche.emzy.de", Server.ConnectionType.TCP, 50001),
-						new Server("2AZZARITA.hopto.org", Server.ConnectionType.TCP, 50001),
-						new Server("xtrum.com", Server.ConnectionType.TCP, 50001),
-						new Server("electrum.srvmin.network", Server.ConnectionType.TCP, 50001),
-						new Server("electrumx.alexridevski.net", Server.ConnectionType.TCP, 50001),
-						new Server("bitcoin.lukechilds.co", Server.ConnectionType.TCP, 50001),
-						new Server("electrum.poiuty.com", Server.ConnectionType.TCP, 50001),
-						new Server("horsey.cryptocowboys.net", Server.ConnectionType.TCP, 50001),
-						new Server("electrum.emzy.de", Server.ConnectionType.TCP, 50001),
-						new Server("electrum-server.ninja", Server.ConnectionType.TCP, 50081),
-						new Server("bitcoin.electrumx.multicoin.co", Server.ConnectionType.TCP, 50001),
-						new Server("esx.geekhosters.com", Server.ConnectionType.TCP, 50001),
-						new Server("bitcoin.grey.pw", Server.ConnectionType.TCP, 50003),
-						new Server("exs.ignorelist.com", Server.ConnectionType.TCP, 50001),
-						new Server("electrum.coinext.com.br", Server.ConnectionType.TCP, 50001),
-						new Server("bitcoin.aranguren.org", Server.ConnectionType.TCP, 50001),
-						new Server("skbxmit.coinjoined.com", Server.ConnectionType.TCP, 50001),
-						new Server("alviss.coinjoined.com", Server.ConnectionType.TCP, 50001),
-						new Server("electrum2.privateservers.network", Server.ConnectionType.TCP, 50001),
-						new Server("electrumx.schulzemic.net", Server.ConnectionType.TCP, 50001),
-						new Server("bitcoins.sk", Server.ConnectionType.TCP, 56001),
-						new Server("node.mendonca.xyz", Server.ConnectionType.TCP, 50001),
-						new Server("bitcoin.aranguren.org", Server.ConnectionType.TCP, 50001)));
-				break;
-
-			case "TEST3":
-				this.expectedGenesisHash = TEST3_GENESIS_HASH;
-
-				this.servers.addAll(Arrays.asList(
-						new Server("electrum.blockstream.info", Server.ConnectionType.TCP, 60001),
-						new Server("electrum.blockstream.info", Server.ConnectionType.SSL, 60002),
-						new Server("electrumx-test.1209k.com", Server.ConnectionType.SSL, 50002),
-						new Server("testnet.qtornado.com", Server.ConnectionType.TCP, 51001),
-						new Server("testnet.qtornado.com", Server.ConnectionType.SSL, 51002),
-						new Server("testnet.aranguren.org", Server.ConnectionType.TCP, 51001),
-						new Server("testnet.aranguren.org", Server.ConnectionType.SSL, 51002),
-						new Server("testnet.hsmiths.com", Server.ConnectionType.SSL, 53012)));
-				break;
-
-			case "REGTEST":
-				this.expectedGenesisHash = null;
-
-				this.servers.addAll(Arrays.asList(
-						new Server("localhost", Server.ConnectionType.TCP, DEFAULT_TCP_PORT),
-						new Server("localhost", Server.ConnectionType.SSL, DEFAULT_SSL_PORT)));
-				break;
-
-			default:
-				throw new IllegalArgumentException(String.format("Bitcoin network '%s' unknown", bitcoinNetwork));
-		}
-
-		LOGGER.debug(() -> String.format("Starting ElectrumX support for %s Bitcoin network", bitcoinNetwork));
-	}
-
-	/** Returns ElectrumX instance linked to passed Bitcoin network, one of "MAIN", "TEST3" or "REGTEST". */
-	public static synchronized ElectrumX getInstance(String bitcoinNetwork) {
-		if (!instances.containsKey(bitcoinNetwork))
-			instances.put(bitcoinNetwork, new ElectrumX(bitcoinNetwork));
-
-		return instances.get(bitcoinNetwork);
+	public ElectrumX(String netId, String genesisHash, Collection<Server> initialServerList, Map<Server.ConnectionType, Integer> defaultPorts) {
+		this.netId = netId;
+		this.expectedGenesisHash = genesisHash;
+		this.servers.addAll(initialServerList);
+		this.defaultPorts.putAll(defaultPorts);
 	}
 
 	// Methods for use by other classes
 
+	@Override
+	public String getNetId() {
+		return this.netId;
+	}
+
 	/**
 	 * Returns current blockchain height.
 	 * <p>
-	 * @throws BitcoinException if error occurs
+	 * @throws ForeignBlockchainException if error occurs
 	 */
-	public int getCurrentHeight() throws BitcoinException {
+	@Override
+	public int getCurrentHeight() throws ForeignBlockchainException {
 		Object blockObj = this.rpc("blockchain.headers.subscribe");
 		if (!(blockObj instanceof JSONObject))
-			throw new BitcoinException.NetworkException("Unexpected output from ElectrumX blockchain.headers.subscribe RPC");
+			throw new ForeignBlockchainException.NetworkException("Unexpected output from ElectrumX blockchain.headers.subscribe RPC");
 
 		JSONObject blockJson = (JSONObject) blockObj;
 
 		Object heightObj = blockJson.get("height");
 
 		if (!(heightObj instanceof Long))
-			throw new BitcoinException.NetworkException("Missing/invalid 'height' in JSON from ElectrumX blockchain.headers.subscribe RPC");
+			throw new ForeignBlockchainException.NetworkException("Missing/invalid 'height' in JSON from ElectrumX blockchain.headers.subscribe RPC");
 
 		return ((Long) heightObj).intValue();
 	}
@@ -203,12 +153,13 @@ public class ElectrumX {
 	/**
 	 * Returns list of raw block headers, starting from <tt>startHeight</tt> inclusive.
 	 * <p>
-	 * @throws BitcoinException if error occurs
+	 * @throws ForeignBlockchainException if error occurs
 	 */
-	public List<byte[]> getBlockHeaders(int startHeight, long count) throws BitcoinException {
+	@Override
+	public List<byte[]> getRawBlockHeaders(int startHeight, int count) throws ForeignBlockchainException {
 		Object blockObj = this.rpc("blockchain.block.headers", startHeight, count);
 		if (!(blockObj instanceof JSONObject))
-			throw new BitcoinException.NetworkException("Unexpected output from ElectrumX blockchain.block.headers RPC");
+			throw new ForeignBlockchainException.NetworkException("Unexpected output from ElectrumX blockchain.block.headers RPC");
 
 		JSONObject blockJson = (JSONObject) blockObj;
 
@@ -216,18 +167,46 @@ public class ElectrumX {
 		Object hexObj = blockJson.get("hex");
 
 		if (!(countObj instanceof Long) || !(hexObj instanceof String))
-			throw new BitcoinException.NetworkException("Missing/invalid 'count' or 'hex' entries in JSON from ElectrumX blockchain.block.headers RPC");
+			throw new ForeignBlockchainException.NetworkException("Missing/invalid 'count' or 'hex' entries in JSON from ElectrumX blockchain.block.headers RPC");
 
 		Long returnedCount = (Long) countObj;
 		String hex = (String) hexObj;
 
-		byte[] raw = HashCode.fromString(hex).asBytes();
-		if (raw.length != returnedCount * BLOCK_HEADER_LENGTH)
-			throw new BitcoinException.NetworkException("Unexpected raw header length in JSON from ElectrumX blockchain.block.headers RPC");
-
 		List<byte[]> rawBlockHeaders = new ArrayList<>(returnedCount.intValue());
-		for (int i = 0; i < returnedCount; ++i)
-			rawBlockHeaders.add(Arrays.copyOfRange(raw, i * BLOCK_HEADER_LENGTH, (i + 1) * BLOCK_HEADER_LENGTH));
+
+		byte[] raw = HashCode.fromString(hex).asBytes();
+
+		// Most chains use a fixed length 80 byte header, so block headers can be split up by dividing the hex into
+		// 80-byte segments. However, some chains such as DOGE use variable length headers due to AuxPoW or other
+		// reasons. In these cases we can identify the start of each block header by the location of the block version
+		// numbers. Each block starts with a version number, and for DOGE this is easily identifiable (6422788) at the
+		// time of writing (Jul 2021). If we encounter a chain that is using more generic version numbers (e.g. 1)
+		// and can't be used to accurately identify block indexes, then there are sufficient checks to ensure an
+		// exception is thrown.
+
+		if (raw.length == returnedCount * BLOCK_HEADER_LENGTH) {
+			// Fixed-length header (BTC, LTC, etc)
+			for (int i = 0; i < returnedCount; ++i) {
+				rawBlockHeaders.add(Arrays.copyOfRange(raw, i * BLOCK_HEADER_LENGTH, (i + 1) * BLOCK_HEADER_LENGTH));
+			}
+		}
+		else if (raw.length > returnedCount * BLOCK_HEADER_LENGTH) {
+			// Assume AuxPoW variable length header (DOGE)
+			int referenceVersion = BitTwiddling.intFromLEBytes(raw, 0); // DOGE uses 6422788 at time of commit (Jul 2021)
+			for (int i = 0; i < raw.length - 4; ++i) {
+				// Locate the start of each block by its version number
+				if (BitTwiddling.intFromLEBytes(raw, i) == referenceVersion) {
+					rawBlockHeaders.add(Arrays.copyOfRange(raw, i, i + BLOCK_HEADER_LENGTH));
+				}
+			}
+			// Ensure that we found the correct number of block headers
+			if (rawBlockHeaders.size() != count) {
+				throw new ForeignBlockchainException.NetworkException("Unexpected raw header contents in JSON from ElectrumX blockchain.block.headers RPC.");
+			}
+		}
+		else if (raw.length != returnedCount * BLOCK_HEADER_LENGTH) {
+			throw new ForeignBlockchainException.NetworkException("Unexpected raw header length in JSON from ElectrumX blockchain.block.headers RPC");
+		}
 
 		return rawBlockHeaders;
 	}
@@ -236,22 +215,23 @@ public class ElectrumX {
 	 * Returns confirmed balance, based on passed payment script.
 	 * <p>
 	 * @return confirmed balance, or zero if script unknown
-	 * @throws BitcoinException if there was an error
+	 * @throws ForeignBlockchainException if there was an error
 	 */
-	public long getConfirmedBalance(byte[] script) throws BitcoinException {
+	@Override
+	public long getConfirmedBalance(byte[] script) throws ForeignBlockchainException {
 		byte[] scriptHash = Crypto.digest(script);
 		Bytes.reverse(scriptHash);
 
 		Object balanceObj = this.rpc("blockchain.scripthash.get_balance", HashCode.fromBytes(scriptHash).toString());
 		if (!(balanceObj instanceof JSONObject))
-			throw new BitcoinException.NetworkException("Unexpected output from ElectrumX blockchain.scripthash.get_balance RPC");
+			throw new ForeignBlockchainException.NetworkException("Unexpected output from ElectrumX blockchain.scripthash.get_balance RPC");
 
 		JSONObject balanceJson = (JSONObject) balanceObj;
 
 		Object confirmedBalanceObj = balanceJson.get("confirmed");
 
 		if (!(confirmedBalanceObj instanceof Long))
-			throw new BitcoinException.NetworkException("Missing confirmed balance from ElectrumX blockchain.scripthash.get_balance RPC");
+			throw new ForeignBlockchainException.NetworkException("Missing confirmed balance from ElectrumX blockchain.scripthash.get_balance RPC");
 
 		return (Long) balanceJson.get("confirmed");
 	}
@@ -260,15 +240,16 @@ public class ElectrumX {
 	 * Returns list of unspent outputs pertaining to passed payment script.
 	 * <p>
 	 * @return list of unspent outputs, or empty list if script unknown
-	 * @throws BitcoinException if there was an error.
+	 * @throws ForeignBlockchainException if there was an error.
 	 */
-	public List<UnspentOutput> getUnspentOutputs(byte[] script, boolean includeUnconfirmed) throws BitcoinException {
+	@Override
+	public List<UnspentOutput> getUnspentOutputs(byte[] script, boolean includeUnconfirmed) throws ForeignBlockchainException {
 		byte[] scriptHash = Crypto.digest(script);
 		Bytes.reverse(scriptHash);
 
 		Object unspentJson = this.rpc("blockchain.scripthash.listunspent", HashCode.fromBytes(scriptHash).toString());
 		if (!(unspentJson instanceof JSONArray))
-			throw new BitcoinException("Expected array output from ElectrumX blockchain.scripthash.listunspent RPC");
+			throw new ForeignBlockchainException("Expected array output from ElectrumX blockchain.scripthash.listunspent RPC");
 
 		List<UnspentOutput> unspentOutputs = new ArrayList<>();
 		for (Object rawUnspent : (JSONArray) unspentJson) {
@@ -292,57 +273,93 @@ public class ElectrumX {
 	/**
 	 * Returns raw transaction for passed transaction hash.
 	 * <p>
-	 * @throws BitcoinException.NotFoundException if transaction not found
-	 * @throws BitcoinException if error occurs
+	 * NOTE: Do not mutate returned byte[]!
+	 * 
+	 * @throws ForeignBlockchainException.NotFoundException if transaction not found
+	 * @throws ForeignBlockchainException if error occurs
 	 */
-	public byte[] getRawTransaction(byte[] txHash) throws BitcoinException {
+	@Override
+	public byte[] getRawTransaction(String txHash) throws ForeignBlockchainException {
 		Object rawTransactionHex;
 		try {
-			rawTransactionHex = this.rpc("blockchain.transaction.get", HashCode.fromBytes(txHash).toString());
-		} catch (BitcoinException.NetworkException e) {
+			rawTransactionHex = this.rpc("blockchain.transaction.get", txHash, false);
+		} catch (ForeignBlockchainException.NetworkException e) {
 			// DaemonError({'code': -5, 'message': 'No such mempool or blockchain transaction. Use gettransaction for wallet transactions.'})
 			if (Integer.valueOf(-5).equals(e.getDaemonErrorCode()))
-				throw new BitcoinException.NotFoundException(e.getMessage());
+				throw new ForeignBlockchainException.NotFoundException(e.getMessage());
 
 			throw e;
 		}
 
 		if (!(rawTransactionHex instanceof String))
-			throw new BitcoinException.NetworkException("Expected hex string as raw transaction from ElectrumX blockchain.transaction.get RPC");
+			throw new ForeignBlockchainException.NetworkException("Expected hex string as raw transaction from ElectrumX blockchain.transaction.get RPC");
 
 		return HashCode.fromString((String) rawTransactionHex).asBytes();
 	}
 
+	/**
+	 * Returns raw transaction for passed transaction hash.
+	 * <p>
+	 * NOTE: Do not mutate returned byte[]!
+	 * 
+	 * @throws ForeignBlockchainException.NotFoundException if transaction not found
+	 * @throws ForeignBlockchainException if error occurs
+	 */
+	@Override
+	public byte[] getRawTransaction(byte[] txHash) throws ForeignBlockchainException {
+		return getRawTransaction(HashCode.fromBytes(txHash).toString());
+	}
+
 	/**
 	 * Returns transaction info for passed transaction hash.
 	 * <p>
-	 * @throws BitcoinException.NotFoundException if transaction not found
-	 * @throws BitcoinException if error occurs
+	 * @throws ForeignBlockchainException.NotFoundException if transaction not found
+	 * @throws ForeignBlockchainException if error occurs
 	 */
-	public BitcoinTransaction getTransaction(String txHash) throws BitcoinException {
-		Object transactionObj;
-		try {
-			transactionObj = this.rpc("blockchain.transaction.get", txHash, true);
-		} catch (BitcoinException.NetworkException e) {
-			// DaemonError({'code': -5, 'message': 'No such mempool or blockchain transaction. Use gettransaction for wallet transactions.'})
-			if (Integer.valueOf(-5).equals(e.getDaemonErrorCode()))
-				throw new BitcoinException.NotFoundException(e.getMessage());
+	@Override
+	public BitcoinyTransaction getTransaction(String txHash) throws ForeignBlockchainException {
+		// Check cache first
+		BitcoinyTransaction transaction = transactionCache.get(txHash);
+		if (transaction != null)
+			return transaction;
 
-			throw e;
-		}
+		Object transactionObj = null;
+
+		do {
+			try {
+				transactionObj = this.rpc("blockchain.transaction.get", txHash, true);
+			} catch (ForeignBlockchainException.NetworkException e) {
+				// DaemonError({'code': -5, 'message': 'No such mempool or blockchain transaction. Use gettransaction for wallet transactions.'})
+				if (Integer.valueOf(-5).equals(e.getDaemonErrorCode()))
+					throw new ForeignBlockchainException.NotFoundException(e.getMessage());
+
+				// Some servers also return non-standard responses like this:
+				// {"error":"verbose transactions are currently unsupported","id":3,"jsonrpc":"2.0"}
+				// We should probably not use this server any more
+				if (e.getServer() != null && e.getMessage() != null && e.getMessage().contains(VERBOSE_TRANSACTIONS_UNSUPPORTED_MESSAGE)) {
+					Server uselessServer = (Server) e.getServer();
+					LOGGER.trace(() -> String.format("Server %s doesn't support verbose transactions - barring use of that server", uselessServer));
+					this.uselessServers.add(uselessServer);
+					this.closeServer(uselessServer);
+					continue;
+				}
+
+				throw e;
+			}
+		} while (transactionObj == null);
 
 		if (!(transactionObj instanceof JSONObject))
-			throw new BitcoinException.NetworkException("Expected JSONObject as response from ElectrumX blockchain.transaction.get RPC");
+			throw new ForeignBlockchainException.NetworkException("Expected JSONObject as response from ElectrumX blockchain.transaction.get RPC");
 
 		JSONObject transactionJson = (JSONObject) transactionObj;
 
 		Object inputsObj = transactionJson.get("vin");
 		if (!(inputsObj instanceof JSONArray))
-			throw new BitcoinException.NetworkException("Expected JSONArray for 'vin' from ElectrumX blockchain.transaction.get RPC");
+			throw new ForeignBlockchainException.NetworkException("Expected JSONArray for 'vin' from ElectrumX blockchain.transaction.get RPC");
 
 		Object outputsObj = transactionJson.get("vout");
 		if (!(outputsObj instanceof JSONArray))
-			throw new BitcoinException.NetworkException("Expected JSONArray for 'vout' from ElectrumX blockchain.transaction.get RPC");
+			throw new ForeignBlockchainException.NetworkException("Expected JSONArray for 'vout' from ElectrumX blockchain.transaction.get RPC");
 
 		try {
 			int size = ((Long) transactionJson.get("size")).intValue();
@@ -354,7 +371,7 @@ public class ElectrumX {
 					? ((Long) timeObj).intValue()
 					: null;
 
-			List<BitcoinTransaction.Input> inputs = new ArrayList<>();
+			List<BitcoinyTransaction.Input> inputs = new ArrayList<>();
 			for (Object inputObj : (JSONArray) inputsObj) {
 				JSONObject inputJson = (JSONObject) inputObj;
 
@@ -363,40 +380,55 @@ public class ElectrumX {
 				String outputTxHash = (String) inputJson.get("txid");
 				int outputVout = ((Long) inputJson.get("vout")).intValue();
 
-				inputs.add(new BitcoinTransaction.Input(scriptSig, sequence, outputTxHash, outputVout));
+				inputs.add(new BitcoinyTransaction.Input(scriptSig, sequence, outputTxHash, outputVout));
 			}
 
-			List<BitcoinTransaction.Output> outputs = new ArrayList<>();
+			List<BitcoinyTransaction.Output> outputs = new ArrayList<>();
 			for (Object outputObj : (JSONArray) outputsObj) {
 				JSONObject outputJson = (JSONObject) outputObj;
 
 				String scriptPubKey = (String) ((JSONObject) outputJson.get("scriptPubKey")).get("hex");
-				long value = (long) (((Double) outputJson.get("value")) * 1e8);
+				long value = BigDecimal.valueOf((Double) outputJson.get("value")).setScale(8).unscaledValue().longValue();
 
-				outputs.add(new BitcoinTransaction.Output(scriptPubKey, value));
+				// address too, if present
+				List<String> addresses = null;
+				Object addressesObj = ((JSONObject) outputJson.get("scriptPubKey")).get("addresses");
+				if (addressesObj instanceof JSONArray) {
+					addresses = new ArrayList<>();
+					for (Object addressObj : (JSONArray) addressesObj)
+						addresses.add((String) addressObj);
+				}
+
+				outputs.add(new BitcoinyTransaction.Output(scriptPubKey, value, addresses));
 			}
 
-			return new BitcoinTransaction(txHash, size, locktime, timestamp, inputs, outputs);
+			transaction = new BitcoinyTransaction(txHash, size, locktime, timestamp, inputs, outputs);
+
+			// Save into cache
+			transactionCache.put(txHash, transaction);
+
+			return transaction;
 		} catch (NullPointerException | ClassCastException e) {
 			// Unexpected / invalid response from ElectrumX server
 		}
 
-		throw new BitcoinException.NetworkException("Unexpected JSON format from ElectrumX blockchain.transaction.get RPC");
+		throw new ForeignBlockchainException.NetworkException("Unexpected JSON format from ElectrumX blockchain.transaction.get RPC");
 	}
 
 	/**
 	 * Returns list of transactions, relating to passed payment script.
 	 * <p>
 	 * @return list of related transactions, or empty list if script unknown
-	 * @throws BitcoinException if error occurs
+	 * @throws ForeignBlockchainException if error occurs
 	 */
-	public List<TransactionHash> getAddressTransactions(byte[] script, boolean includeUnconfirmed) throws BitcoinException {
+	@Override
+	public List<TransactionHash> getAddressTransactions(byte[] script, boolean includeUnconfirmed) throws ForeignBlockchainException {
 		byte[] scriptHash = Crypto.digest(script);
 		Bytes.reverse(scriptHash);
 
 		Object transactionsJson = this.rpc("blockchain.scripthash.get_history", HashCode.fromBytes(scriptHash).toString());
 		if (!(transactionsJson instanceof JSONArray))
-			throw new BitcoinException.NetworkException("Expected array output from ElectrumX blockchain.scripthash.get_history RPC");
+			throw new ForeignBlockchainException.NetworkException("Expected array output from ElectrumX blockchain.scripthash.get_history RPC");
 
 		List<TransactionHash> transactionHashes = new ArrayList<>();
 
@@ -417,16 +449,17 @@ public class ElectrumX {
 	}
 
 	/**
-	 * Broadcasts raw transaction to Bitcoin network.
+	 * Broadcasts raw transaction to network.
 	 * <p>
-	 * @throws BitcoinException if error occurs
+	 * @throws ForeignBlockchainException if error occurs
 	 */
-	public void broadcastTransaction(byte[] transactionBytes) throws BitcoinException {
+	@Override
+	public void broadcastTransaction(byte[] transactionBytes) throws ForeignBlockchainException {
 		Object rawBroadcastResult = this.rpc("blockchain.transaction.broadcast", HashCode.fromBytes(transactionBytes).toString());
 
 		// We're expecting a simple string that is the transaction hash
 		if (!(rawBroadcastResult instanceof String))
-			throw new BitcoinException.NetworkException("Unexpected response from ElectrumX blockchain.transaction.broadcast RPC");
+			throw new ForeignBlockchainException.NetworkException("Unexpected response from ElectrumX blockchain.transaction.broadcast RPC");
 	}
 
 	// Class-private utility methods
@@ -434,10 +467,10 @@ public class ElectrumX {
 	/**
 	 * Query current server for its list of peer servers, and return those we can parse.
 	 * <p>
-	 * @throws BitcoinException
+	 * @throws ForeignBlockchainException
 	 * @throws ClassCastException to be handled by caller
 	 */
-	private Set<Server> serverPeersSubscribe() throws BitcoinException {
+	private Set<Server> serverPeersSubscribe() throws ForeignBlockchainException {
 		Set<Server> newServers = new HashSet<>();
 
 		Object peers = this.connectedRpc("server.peers.subscribe");
@@ -454,17 +487,17 @@ public class ElectrumX {
 			for (Object rawFeature : features) {
 				String feature = (String) rawFeature;
 				Server.ConnectionType connectionType = null;
-				int port = -1;
+				Integer port = null;
 
 				switch (feature.charAt(0)) {
 					case 's':
 						connectionType = Server.ConnectionType.SSL;
-						port = DEFAULT_SSL_PORT;
+						port = this.defaultPorts.get(connectionType);
 						break;
 
 					case 't':
 						connectionType = Server.ConnectionType.TCP;
-						port = DEFAULT_TCP_PORT;
+						port = this.defaultPorts.get(connectionType);
 						break;
 
 					default:
@@ -472,7 +505,7 @@ public class ElectrumX {
 						break;
 				}
 
-				if (connectionType == null)
+				if (connectionType == null || port == null)
 					// We couldn't extract any peer connection info?
 					continue;
 
@@ -497,32 +530,30 @@ public class ElectrumX {
 	 * Performs RPC call, with automatic reconnection to different server if needed.
 	 * <p>
 	 * @return "result" object from within JSON output
-	 * @throws BitcoinException if server returns error or something goes wrong
+	 * @throws ForeignBlockchainException if server returns error or something goes wrong
 	 */
-	private synchronized Object rpc(String method, Object...params) throws BitcoinException {
-		if (this.remainingServers.isEmpty())
-			this.remainingServers.addAll(this.servers);
+	private Object rpc(String method, Object...params) throws ForeignBlockchainException {
+		synchronized (this.serverLock) {
+			if (this.remainingServers.isEmpty())
+				this.remainingServers.addAll(this.servers);
 
-		while (haveConnection()) {
-			Object response = connectedRpc(method, params);
-			if (response != null)
-				return response;
+			while (haveConnection()) {
+				Object response = connectedRpc(method, params);
+				if (response != null)
+					return response;
 
-			this.currentServer = null;
-			try {
-				this.socket.close();
-			} catch (IOException e) {
-				/* ignore */
+				// Didn't work, try another server...
+				this.closeServer();
 			}
-			this.scanner = null;
-		}
 
-		// Failed to perform RPC - maybe lack of servers?
-		throw new BitcoinException.NetworkException("Failed to perform Bitcoin RPC");
+			// Failed to perform RPC - maybe lack of servers?
+			LOGGER.info("Error: No connected Electrum servers when trying to make RPC call");
+			throw new ForeignBlockchainException.NetworkException(String.format("Failed to perform ElectrumX RPC %s", method));
+		}
 	}
 
 	/** Returns true if we have, or create, a connection to an ElectrumX server. */
-	private boolean haveConnection() throws BitcoinException {
+	private boolean haveConnection() throws ForeignBlockchainException {
 		if (this.currentServer != null)
 			return true;
 
@@ -566,17 +597,9 @@ public class ElectrumX {
 				LOGGER.debug(() -> String.format("Connected to %s", server));
 				this.currentServer = server;
 				return true;
-			} catch (IOException | BitcoinException | ClassCastException | NullPointerException e) {
-				// Try another server...
-				if (this.socket != null && !this.socket.isClosed())
-					try {
-						this.socket.close();
-					} catch (IOException e1) {
-						// We did try...
-					}
-
-				this.socket = null;
-				this.scanner = null;
+			} catch (IOException | ForeignBlockchainException | ClassCastException | NullPointerException e) {
+				// Didn't work, try another server...
+				closeServer();
 			}
 		}
 
@@ -589,10 +612,10 @@ public class ElectrumX {
 	 * @param method
 	 * @param params
 	 * @return response Object, or null if server fails to respond
-	 * @throws BitcoinException if server returns error
+	 * @throws ForeignBlockchainException if server returns error
 	 */
 	@SuppressWarnings("unchecked")
-	private Object connectedRpc(String method, Object...params) throws BitcoinException {
+	private Object connectedRpc(String method, Object...params) throws ForeignBlockchainException {
 		JSONObject requestJson = new JSONObject();
 		requestJson.put("id", this.nextId++);
 		requestJson.put("method", method);
@@ -630,15 +653,27 @@ public class ElectrumX {
 
 		Object errorObj = responseJson.get("error");
 		if (errorObj != null) {
-			if (!(errorObj instanceof JSONObject))
-				throw new BitcoinException.NetworkException(String.format("Unexpected error response from ElectrumX RPC %s", method));
+			if (errorObj instanceof String) {
+				LOGGER.debug(String.format("Unexpected error message from ElectrumX server %s for RPC method %s: %s", this.currentServer, method, (String) errorObj));
+				// Try another server
+				return null;
+			}
+
+			if (!(errorObj instanceof JSONObject)) {
+				LOGGER.debug(String.format("Unexpected error response from ElectrumX server %s for RPC method %s", this.currentServer, method));
+				// Try another server
+				return null;
+			}
 
 			JSONObject errorJson = (JSONObject) errorObj;
 
 			Object messageObj = errorJson.get("message");
 
-			if (!(messageObj instanceof String))
-				throw new BitcoinException.NetworkException(String.format("Missing/invalid message in error response from ElectrumX RPC %s", method));
+			if (!(messageObj instanceof String)) {
+				LOGGER.debug(String.format("Missing/invalid message in error response from ElectrumX server %s for RPC method %s", this.currentServer, method));
+				// Try another server
+				return null;
+			}
 
 			String message = (String) messageObj;
 
@@ -649,15 +684,44 @@ public class ElectrumX {
 			if (messageMatcher.find())
 				try {
 					int daemonErrorCode = Integer.parseInt(messageMatcher.group(1));
-					throw new BitcoinException.NetworkException(daemonErrorCode, message);
+					throw new ForeignBlockchainException.NetworkException(daemonErrorCode, message, this.currentServer);
 				} catch (NumberFormatException e) {
 					// We couldn't parse the error code integer? Fall-through to generic exception...
 				}
 
-			throw new BitcoinException.NetworkException(message);
+			throw new ForeignBlockchainException.NetworkException(message, this.currentServer);
 		}
 
 		return responseJson.get("result");
 	}
 
+	/**
+	 * Closes connection to <tt>server</tt> if it is currently connected server.
+	 * @param server
+	 */
+	private void closeServer(Server server) {
+		synchronized (this.serverLock) {
+			if (this.currentServer == null || !this.currentServer.equals(server))
+				return;
+
+			if (this.socket != null && !this.socket.isClosed())
+				try {
+					this.socket.close();
+				} catch (IOException e) {
+					// We did try...
+				}
+
+			this.socket = null;
+			this.scanner = null;
+			this.currentServer = null;
+		}
+	}
+
+	/** Closes connection to currently connected server (if any). */
+	private void closeServer() {
+		synchronized (this.serverLock) {
+			this.closeServer(this.currentServer);
+		}
+	}
+
 }

src/main/java/org/qortal/crosschain/ForeignBlockchain.java

@@ -0,0 +1,11 @@
+package org.qortal.crosschain;
+
+public interface ForeignBlockchain {
+
+	public boolean isValidAddress(String address);
+
+	public boolean isValidWalletKey(String walletKey);
+
+	public long getMinimumOrderAmount();
+
+}