Prevent duplicate entries in a list.

These are the same as the /lists/blacklist/address/{address} endpoints but allow a JSON array of addresses to be specified in the request body. They currently return true if

.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 +16,13 @@
 /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

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

@@ -3,12 +3,12 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>org.qortal</groupId>
 	<artifactId>qortal</artifactId>
-	<version>1.4.0</version>
+	<version>1.6.0</version>
 	<packaging>jar</packaging>
 	<properties>
 		<skipTests>true</skipTests>
 		<altcoinj.version>bf9fb80</altcoinj.version>
-		<bitcoinj.version>0.15.6</bitcoinj.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>
@@ -439,6 +439,11 @@
 			<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>

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/api/ApiError.java

@@ -129,7 +129,10 @@ public enum ApiError {
 	// Foreign blockchain
 	FOREIGN_BLOCKCHAIN_NETWORK_ISSUE(1201, 500),
 	FOREIGN_BLOCKCHAIN_BALANCE_ISSUE(1202, 402),
-	FOREIGN_BLOCKCHAIN_TOO_SOON(1203, 408);
+	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/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/model/AddressListRequest.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 AddressListRequest {
+
+	@Schema(description = "A list of addresses")
+	public List<String> addresses;
+
+	public AddressListRequest() {
+	}
+
+}

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/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/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

@@ -25,6 +25,12 @@ public class CrossChainTradeSummary {
 	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
 	private long foreignAmount;
 
+	private String atAddress;
+
+	private String sellerAddress;
+
+	private String buyerReceivingAddress;
+
 	protected CrossChainTradeSummary() {
 		/* For JAXB */
 	}
@@ -34,6 +40,9 @@ public class CrossChainTradeSummary {
 		this.qortAmount = crossChainTradeData.qortAmount;
 		this.foreignAmount = crossChainTradeData.expectedForeignAmount;
 		this.btcAmount = this.foreignAmount;
+		this.sellerAddress = crossChainTradeData.qortalCreator;
+		this.buyerReceivingAddress = crossChainTradeData.qortalPartnerReceivingAddress;
+		this.atAddress = crossChainTradeData.qortalAtAddress;
 	}
 
 	public long getTradeTimestamp() {
@@ -48,7 +57,11 @@ public class CrossChainTradeSummary {
 		return this.btcAmount;
 	}
 
-	public long getForeignAmount() {
-		return this.foreignAmount;
-	}
+	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/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/resource/AdminResource.java

@@ -542,19 +542,8 @@ 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);
 		}
@@ -564,7 +553,7 @@ 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 'import.json' if apiKey is not set.",
 		requestBody = @RequestBody(
 			required = true,
 			content = @Content(
@@ -588,7 +577,7 @@ 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 = "import.json";
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
@@ -628,25 +617,9 @@ 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

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;
@@ -8,6 +9,11 @@ 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.List;
 
@@ -20,10 +26,13 @@ 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.crypto.Crypto;
 import org.qortal.data.account.AccountData;
 import org.qortal.data.block.BlockData;
@@ -32,6 +41,8 @@ import org.qortal.data.transaction.TransactionData;
 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")
@@ -80,6 +91,48 @@ public class BlocksResource {
 		}
 	}
 
+	@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()) {
+			BlockData blockData = repository.getBlockRepository().fromSignature(signature);
+			if (blockData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
+
+			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());
+
+		} 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(
@@ -328,6 +381,59 @@ public class BlocksResource {
 		}
 	}
 
+	@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()) {
+			BlockData blockData = repository.getBlockRepository().fromHeight(height);
+			if (blockData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
+
+			Block block = new Block(repository, blockData);
+			BlockData parentBlockData = repository.getBlockRepository().fromSignature(blockData.getReference());
+			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);
+		}
+	}
+
 	@GET
 	@Path("/timestamp/{timestamp}")
 	@Operation(

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

@@ -22,7 +22,7 @@ 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.CrossChainSecretRequest;
+import org.qortal.api.model.CrossChainDualSecretRequest;
 import org.qortal.api.model.CrossChainTradeRequest;
 import org.qortal.asset.Asset;
 import org.qortal.crosschain.BitcoinACCTv1;
@@ -242,7 +242,7 @@ public class CrossChainBitcoinACCTv1Resource {
 			content = @Content(
 				mediaType = MediaType.APPLICATION_JSON,
 				schema = @Schema(
-					implementation = CrossChainSecretRequest.class
+					implementation = CrossChainDualSecretRequest.class
 				)
 			)
 		),
@@ -257,7 +257,7 @@ public class CrossChainBitcoinACCTv1Resource {
 		}
 	)
 	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.INVALID_DATA, ApiError.INVALID_CRITERIA, ApiError.REPOSITORY_ISSUE})
-	public String buildRedeemMessage(CrossChainSecretRequest secretRequest) {
+	public String buildRedeemMessage(CrossChainDualSecretRequest secretRequest) {
 		Security.checkApiCallAllowed(request);
 
 		byte[] partnerPublicKey = secretRequest.partnerPublicKey;

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

@@ -23,8 +23,8 @@ 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.BitcoinyTransaction;
 import org.qortal.crosschain.ForeignBlockchainException;
+import org.qortal.crosschain.SimpleTransaction;
 
 @Path("/crosschain/btc")
 @Tag(name = "Cross-Chain (Bitcoin)")
@@ -89,12 +89,12 @@ public class CrossChainBitcoinResource {
 		),
 		responses = {
 			@ApiResponse(
-				content = @Content(array = @ArraySchema( schema = @Schema( implementation = BitcoinyTransaction.class ) ) )
+				content = @Content(array = @ArraySchema( schema = @Schema( implementation = SimpleTransaction.class ) ) )
 			)
 		}
 	)
 	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
-	public List<BitcoinyTransaction> getBitcoinWalletTransactions(String key58) {
+	public List<SimpleTransaction> getBitcoinWalletTransactions(String key58) {
 		Security.checkApiCallAllowed(request);
 
 		Bitcoin bitcoin = Bitcoin.getInstance();

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

@@ -16,24 +16,29 @@ import javax.ws.rs.PathParam;
 import javax.ws.rs.core.Context;
 import javax.ws.rs.core.MediaType;
 
-import org.bitcoinj.core.TransactionOutput;
-import org.qortal.api.ApiError;
-import org.qortal.api.ApiErrors;
-import org.qortal.api.ApiExceptionFactory;
-import org.qortal.api.Security;
+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.Bitcoiny;
-import org.qortal.crosschain.ForeignBlockchainException;
-import org.qortal.crosschain.SupportedBlockchain;
-import org.qortal.crosschain.BitcoinyHTLC;
+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;
 
-import com.google.common.hash.HashCode;
-
 @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;
 
@@ -41,7 +46,7 @@ public class CrossChainHtlcResource {
 	@Path("/address/{blockchain}/{refundPKH}/{locktime}/{redeemPKH}/{hashOfSecret}")
 	@Operation(
 		summary = "Returns HTLC address based on trade info",
-		description = "Blockchain can be BITCOIN or LITECOIN. Public key hashes (PKH) and hash of secret should be 20 bytes (hex). Locktime is seconds since epoch.",
+		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"))
@@ -50,21 +55,21 @@ public class CrossChainHtlcResource {
 	)
 	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_CRITERIA})
 	public String deriveHtlcAddress(@PathParam("blockchain") String blockchainName,
-			@PathParam("refundPKH") String refundHex,
+			@PathParam("refundPKH") String refundPKH,
 			@PathParam("locktime") int lockTime,
-			@PathParam("redeemPKH") String redeemHex,
-			@PathParam("hashOfSecret") String hashOfSecretHex) {
+			@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[] hashOfSecret;
+		byte[] decodedHashOfSecret;
 
 		try {
-			refunderPubKeyHash = HashCode.fromString(refundHex).asBytes();
-			redeemerPubKeyHash = HashCode.fromString(redeemHex).asBytes();
+			refunderPubKeyHash = Base58.decode(refundPKH);
+			redeemerPubKeyHash = Base58.decode(redeemPKH);
 
 			if (refunderPubKeyHash.length != 20 || redeemerPubKeyHash.length != 20)
 				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
@@ -73,14 +78,14 @@ public class CrossChainHtlcResource {
 		}
 
 		try {
-			hashOfSecret = HashCode.fromString(hashOfSecretHex).asBytes();
-			if (hashOfSecret.length != 20)
+			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, hashOfSecret);
+		byte[] redeemScript = BitcoinyHTLC.buildScript(refunderPubKeyHash, lockTime, redeemerPubKeyHash, decodedHashOfSecret);
 
 		Bitcoiny bitcoiny = (Bitcoiny) blockchain.getInstance();
 
@@ -91,7 +96,7 @@ public class CrossChainHtlcResource {
 	@Path("/status/{blockchain}/{refundPKH}/{locktime}/{redeemPKH}/{hashOfSecret}")
 	@Operation(
 		summary = "Checks HTLC status",
-		description = "Blockchain can be BITCOIN or LITECOIN. Public key hashes (PKH) and hash of secret should be 20 bytes (hex). Locktime is seconds since epoch.",
+		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))
@@ -100,10 +105,10 @@ public class CrossChainHtlcResource {
 	)
 	@ApiErrors({ApiError.INVALID_CRITERIA, ApiError.INVALID_ADDRESS, ApiError.ADDRESS_UNKNOWN})
 	public CrossChainBitcoinyHTLCStatus checkHtlcStatus(@PathParam("blockchain") String blockchainName,
-			@PathParam("refundPKH") String refundHex,
+			@PathParam("refundPKH") String refundPKH,
 			@PathParam("locktime") int lockTime,
-			@PathParam("redeemPKH") String redeemHex,
-			@PathParam("hashOfSecret") String hashOfSecretHex) {
+			@PathParam("redeemPKH") String redeemPKH,
+			@PathParam("hashOfSecret") String hashOfSecret) {
 		Security.checkApiCallAllowed(request);
 
 		SupportedBlockchain blockchain = SupportedBlockchain.valueOf(blockchainName);
@@ -112,11 +117,11 @@ public class CrossChainHtlcResource {
 
 		byte[] refunderPubKeyHash;
 		byte[] redeemerPubKeyHash;
-		byte[] hashOfSecret;
+		byte[] decodedHashOfSecret;
 
 		try {
-			refunderPubKeyHash = HashCode.fromString(refundHex).asBytes();
-			redeemerPubKeyHash = HashCode.fromString(redeemHex).asBytes();
+			refunderPubKeyHash = Base58.decode(refundPKH);
+			redeemerPubKeyHash = Base58.decode(redeemPKH);
 
 			if (refunderPubKeyHash.length != 20 || redeemerPubKeyHash.length != 20)
 				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
@@ -125,14 +130,14 @@ public class CrossChainHtlcResource {
 		}
 
 		try {
-			hashOfSecret = HashCode.fromString(hashOfSecretHex).asBytes();
-			if (hashOfSecret.length != 20)
+			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, hashOfSecret);
+		byte[] redeemScript = BitcoinyHTLC.buildScript(refunderPubKeyHash, lockTime, redeemerPubKeyHash, decodedHashOfSecret);
 
 		Bitcoiny bitcoiny = (Bitcoiny) blockchain.getInstance();
 
@@ -168,8 +173,475 @@ public class CrossChainHtlcResource {
 		}
 	}
 
-	// TODO: refund
+	@GET
+	@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);
 
-	// TODO: redeem
+		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);
+		}
+	}
+
+	@GET
+	@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;
+	}
+
+	@GET
+	@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);
+		}
+	}
+
+
+	@GET
+	@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);
+
+		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);
+
+			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

@@ -22,9 +22,9 @@ 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.BitcoinyTransaction;
 import org.qortal.crosschain.ForeignBlockchainException;
 import org.qortal.crosschain.Litecoin;
+import org.qortal.crosschain.SimpleTransaction;
 
 @Path("/crosschain/ltc")
 @Tag(name = "Cross-Chain (Litecoin)")
@@ -89,12 +89,12 @@ public class CrossChainLitecoinResource {
 		),
 		responses = {
 			@ApiResponse(
-				content = @Content(array = @ArraySchema( schema = @Schema( implementation = BitcoinyTransaction.class ) ) )
+				content = @Content(array = @ArraySchema( schema = @Schema( implementation = SimpleTransaction.class ) ) )
 			)
 		}
 	)
 	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
-	public List<BitcoinyTransaction> getLitecoinWalletTransactions(String key58) {
+	public List<SimpleTransaction> getLitecoinWalletTransactions(String key58) {
 		Security.checkApiCallAllowed(request);
 
 		Litecoin litecoin = Litecoin.getInstance();

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

@@ -118,6 +118,37 @@ public class CrossChainResource {
 		}
 	}
 
+	@GET
+	@Path("/trade/{ataddress}")
+	@Operation(
+		summary = "Show detailed trade info",
+		responses = {
+			@ApiResponse(
+				content = @Content(
+					schema = @Schema(
+						implementation = CrossChainTradeData.class
+					)
+				)
+			)
+		}
+	)
+	@ApiErrors({ApiError.ADDRESS_UNKNOWN, ApiError.INVALID_CRITERIA, ApiError.REPOSITORY_ISSUE})
+	public CrossChainTradeData getTrade(@PathParam("ataddress") String atAddress) {
+		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);
+
+			return acct.populateTradeData(repository, atData);
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
 	@GET
 	@Path("/trades")
 	@Operation(
@@ -224,13 +255,19 @@ public class CrossChainResource {
 					description = "foreign blockchain",
 					example = "LITECOIN",
 					schema = @Schema(implementation = SupportedBlockchain.class)
-				) @PathParam("blockchain") SupportedBlockchain foreignBlockchain) {
+				) @PathParam("blockchain") SupportedBlockchain foreignBlockchain,
+			@Parameter(
+					description = "Maximum number of trades to include in price calculation",
+					example = "10",
+					schema = @Schema(type = "integer", defaultValue = "10")
+			) @QueryParam("maxtrades") Integer maxtrades) {
 		// foreignBlockchain is required
 		if (foreignBlockchain == null)
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 
 		// We want both a minimum of 5 trades and enough trades to span at least 4 hours
 		int minimumCount = 5;
+		int maximumCount = maxtrades != null ? maxtrades : 10;
 		long minimumPeriod = 4 * 60 * 60 * 1000L; // ms
 		Boolean isFinished = Boolean.TRUE;
 
@@ -245,7 +282,7 @@ public class CrossChainResource {
 				ACCT acct = acctInfo.getValue().get();
 
 				List<ATStateData> atStates = repository.getATRepository().getMatchingFinalATStatesQuorum(codeHash,
-						isFinished, acct.getModeByteOffset(), (long) AcctMode.REDEEMED.value, minimumCount, minimumPeriod);
+						isFinished, acct.getModeByteOffset(), (long) AcctMode.REDEEMED.value, minimumCount, maximumCount, minimumPeriod);
 
 				for (ATStateData atState : atStates) {
 					CrossChainTradeData crossChainTradeData = acct.populateTradeData(repository, atState);

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

@@ -107,7 +107,7 @@ public class CrossChainTradeBotResource {
 			)
 		}
 	)
-	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.INVALID_CRITERIA, ApiError.INSUFFICIENT_BALANCE, ApiError.REPOSITORY_ISSUE})
+	@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);
@@ -128,10 +128,13 @@ public class CrossChainTradeBotResource {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 
 		if (tradeBotCreateRequest.foreignAmount == null || tradeBotCreateRequest.foreignAmount <= 0)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+			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.INVALID_CRITERIA);
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ORDER_SIZE_TOO_SMALL);
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			// Do some simple checking first
@@ -283,4 +286,4 @@ public class CrossChainTradeBotResource {
 		return atData;
 	}
 
-}
+}

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

@@ -0,0 +1,271 @@
+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.api.*;
+import org.qortal.api.model.AddressListRequest;
+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;
+	
+	@POST
+	@Path("/blacklist/address/{address}")
+	@Operation(
+		summary = "Add a QORT address to the local blacklist",
+		responses = {
+			@ApiResponse(
+				description = "Returns true on success, or an exception on failure",
+					content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "boolean"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_ADDRESS, ApiError.ADDRESS_UNKNOWN, ApiError.REPOSITORY_ISSUE})
+	public String addAddressToBlacklist(@PathParam("address") String address) {
+		if (!Crypto.isValidAddress(address))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			AccountData accountData = repository.getAccountRepository().getAccount(address);
+			// Not found?
+			if (accountData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
+
+			// Valid address, so go ahead and blacklist it
+			boolean success = ResourceListManager.getInstance().addAddressToBlacklist(address, true);
+
+			return success ? "true" : "false";
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@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 = AddressListRequest.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(AddressListRequest addressListRequest) {
+		if (addressListRequest == null || addressListRequest.addresses == null) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+		}
+
+		int successCount = 0;
+		int errorCount = 0;
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+
+			for (String address : addressListRequest.addresses) {
+
+				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().addAddressToBlacklist(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().saveBlacklist();
+			return "true";
+		}
+		else {
+			// Something went wrong, so revert
+			ResourceListManager.getInstance().revertBlacklist();
+			return "false";
+		}
+	}
+
+
+	@DELETE
+	@Path("/blacklist/address/{address}")
+	@Operation(
+			summary = "Remove a QORT address from the local blacklist",
+			responses = {
+					@ApiResponse(
+							description = "Returns true on success, or an exception on failure",
+							content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "boolean"))
+					)
+			}
+	)
+	@ApiErrors({ApiError.INVALID_ADDRESS, ApiError.ADDRESS_UNKNOWN, ApiError.REPOSITORY_ISSUE})
+	public String removeAddressFromBlacklist(@PathParam("address") String address) {
+		if (!Crypto.isValidAddress(address))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			AccountData accountData = repository.getAccountRepository().getAccount(address);
+			// Not found?
+			if (accountData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
+
+			// Valid address, so go ahead and blacklist it
+			boolean success = ResourceListManager.getInstance().removeAddressFromBlacklist(address, true);
+
+			return success ? "true" : "false";
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@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 = AddressListRequest.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(AddressListRequest addressListRequest) {
+		if (addressListRequest == null || addressListRequest.addresses == null) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+		}
+
+		int successCount = 0;
+		int errorCount = 0;
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+
+			for (String address : addressListRequest.addresses) {
+
+				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().removeAddressFromBlacklist(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().saveBlacklist();
+			return "true";
+		}
+		else {
+			// Something went wrong, so revert
+			ResourceListManager.getInstance().revertBlacklist();
+			return "false";
+		}
+	}
+
+	@GET
+	@Path("/blacklist/address/{address}")
+	@Operation(
+			summary = "Check if an address is present in the local blacklist",
+			responses = {
+					@ApiResponse(
+							description = "Returns true or false if the list was queried, or an exception on failure",
+							content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "boolean"))
+					)
+			}
+	)
+	@ApiErrors({ApiError.INVALID_ADDRESS, ApiError.ADDRESS_UNKNOWN, ApiError.REPOSITORY_ISSUE})
+	public String checkAddressInBlacklist(@PathParam("address") String address) {
+		if (!Crypto.isValidAddress(address))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			AccountData accountData = repository.getAccountRepository().getAccount(address);
+			// Not found?
+			if (accountData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
+
+			// Valid address, so go ahead and blacklist it
+			boolean blacklisted = ResourceListManager.getInstance().isAddressInBlacklist(address);
+
+			return blacklisted ? "true" : "false";
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+}

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/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/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/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

@@ -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>

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

@@ -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);
@@ -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;
 	}
@@ -1242,12 +1247,13 @@ 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();
 		}
 
@@ -1332,6 +1338,9 @@ public class Block {
 
 		// Give Controller our cached, valid online accounts data (if any) to help reduce CPU load for next block
 		Controller.getInstance().pushLatestBlocksOnlineAccounts(this.cachedValidOnlineAccounts);
+
+		// Log some debugging info relating to the block weight calculation
+		this.logDebugInfo();
 	}
 
 	protected void increaseAccountLevels() throws DataException {
@@ -1513,6 +1522,9 @@ 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();
 
@@ -1787,7 +1799,7 @@ 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 +1997,38 @@ 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

@@ -70,6 +70,10 @@ 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 +375,22 @@ 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) {

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

@@ -135,16 +135,19 @@ 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 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)
+						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 +168,14 @@ 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()) {
@@ -282,15 +293,17 @@ 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()));
 						}
 

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

@@ -67,8 +67,8 @@ import org.qortal.gui.SysTray;
 import org.qortal.network.Network;
 import org.qortal.network.Peer;
 import org.qortal.network.message.ArbitraryDataMessage;
-import org.qortal.network.message.BlockMessage;
 import org.qortal.network.message.BlockSummariesMessage;
+import org.qortal.network.message.CachedBlockMessage;
 import org.qortal.network.message.GetArbitraryDataMessage;
 import org.qortal.network.message.GetBlockMessage;
 import org.qortal.network.message.GetBlockSummariesMessage;
@@ -121,6 +121,7 @@ public class Controller extends Thread {
 	private static final long NTP_PRE_SYNC_CHECK_PERIOD = 5 * 1000L; // ms
 	private static final long NTP_POST_SYNC_CHECK_PERIOD = 5 * 60 * 1000L; // ms
 	private static final long DELETE_EXPIRED_INTERVAL = 5 * 60 * 1000L; // ms
+	private static final long RECOVERY_MODE_TIMEOUT = 10 * 60 * 1000L; // ms
 
 	// To do with online accounts list
 	private static final long ONLINE_ACCOUNTS_TASKS_INTERVAL = 10 * 1000L; // ms
@@ -143,16 +144,15 @@ public class Controller extends Thread {
 	private ExecutorService callbackExecutor = Executors.newFixedThreadPool(3);
 	private volatile boolean notifyGroupMembershipChange = false;
 
-	private static final int BLOCK_CACHE_SIZE = 10; // To cover typical Synchronizer request + a few spare
 	/** Latest blocks on our chain. Note: tail/last is the latest block. */
 	private final Deque<BlockData> latestBlocks = new LinkedList<>();
 
 	/** Cache of BlockMessages, indexed by block signature */
 	@SuppressWarnings("serial")
-	private final LinkedHashMap<ByteArray, BlockMessage> blockMessageCache = new LinkedHashMap<>() {
+	private final LinkedHashMap<ByteArray, CachedBlockMessage> blockMessageCache = new LinkedHashMap<>() {
 		@Override
-		protected boolean removeEldestEntry(Map.Entry<ByteArray, BlockMessage> eldest) {
-			return this.size() > BLOCK_CACHE_SIZE;
+		protected boolean removeEldestEntry(Map.Entry<ByteArray, CachedBlockMessage> eldest) {
+			return this.size() > Settings.getInstance().getBlockCacheSize();
 		}
 	};
 
@@ -176,6 +176,11 @@ public class Controller extends Thread {
 	/** Latest block signatures from other peers that we know are on inferior chains. */
 	List<ByteArray> inferiorChainSignatures = new ArrayList<>();
 
+	/** Recovery mode, which is used to bring back a stalled network */
+	private boolean recoveryMode = false;
+	private boolean peersAvailable = true; // peersAvailable must default to true
+	private long timePeersLastAvailable = 0;
+
 	/**
 	 * Map of recent requests for ARBITRARY transaction data payloads.
 	 * <p>
@@ -254,17 +259,29 @@ public class Controller extends Thread {
 			throw new RuntimeException("Can't read build.properties resource", e);
 		}
 
+		// Determine build timestamp
 		String buildTimestampProperty = properties.getProperty("build.timestamp");
-		if (buildTimestampProperty == null)
+		if (buildTimestampProperty == null) {
 			throw new RuntimeException("Can't read build.timestamp from build.properties resource");
-
-		this.buildTimestamp = LocalDateTime.parse(buildTimestampProperty, DateTimeFormatter.ofPattern("yyyyMMddHHmmss")).toEpochSecond(ZoneOffset.UTC);
+		}
+		if (buildTimestampProperty.startsWith("$")) {
+			// Maven vars haven't been replaced - this was most likely built using an IDE, not via mvn package
+			this.buildTimestamp = System.currentTimeMillis();
+			buildTimestampProperty = "unknown";
+		} else {
+			this.buildTimestamp = LocalDateTime.parse(buildTimestampProperty, DateTimeFormatter.ofPattern("yyyyMMddHHmmss")).toEpochSecond(ZoneOffset.UTC);
+		}
 		LOGGER.info(String.format("Build timestamp: %s", buildTimestampProperty));
 
+		// Determine build version
 		String buildVersionProperty = properties.getProperty("build.version");
-		if (buildVersionProperty == null)
+		if (buildVersionProperty == null) {
 			throw new RuntimeException("Can't read build.version from build.properties resource");
-
+		}
+		if (buildVersionProperty.contains("${git.commit.id.abbrev}")) {
+			// Maven vars haven't been replaced - this was most likely built using an IDE, not via mvn package
+			buildVersionProperty = buildVersionProperty.replace("${git.commit.id.abbrev}", "debug");
+		}
 		this.buildVersion = VERSION_PREFIX + buildVersionProperty;
 		LOGGER.info(String.format("Build version: %s", this.buildVersion));
 
@@ -319,11 +336,12 @@ public class Controller extends Thread {
 		// Set initial chain height/tip
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			BlockData blockData = repository.getBlockRepository().getLastBlock();
+			int blockCacheSize = Settings.getInstance().getBlockCacheSize();
 
 			synchronized (this.latestBlocks) {
 				this.latestBlocks.clear();
 
-				for (int i = 0; i < BLOCK_CACHE_SIZE && blockData != null; ++i) {
+				for (int i = 0; i < blockCacheSize && blockData != null; ++i) {
 					this.latestBlocks.addFirst(blockData);
 					blockData = repository.getBlockRepository().fromHeight(blockData.getHeight() - 1);
 				}
@@ -358,6 +376,10 @@ public class Controller extends Thread {
 		}
 	}
 
+	public boolean getRecoveryMode() {
+		return this.recoveryMode;
+	}
+
 	// Entry point
 
 	public static void main(String[] args) {
@@ -536,12 +558,7 @@ public class Controller extends Thread {
 				if (now >= repositoryCheckpointTimestamp + repositoryCheckpointInterval) {
 					repositoryCheckpointTimestamp = now + repositoryCheckpointInterval;
 
-					if (Settings.getInstance().getShowCheckpointNotification())
-						SysTray.getInstance().showMessage(Translator.INSTANCE.translate("SysTray", "DB_CHECKPOINT"),
-								Translator.INSTANCE.translate("SysTray", "PERFORMING_DB_CHECKPOINT"),
-								MessageType.INFO);
-
-					RepositoryManager.checkpoint(true);
+					RepositoryManager.setRequestedCheckpoint(Boolean.TRUE);
 				}
 
 				// Give repository a chance to backup (if enabled)
@@ -618,6 +635,11 @@ public class Controller extends Thread {
 		return peerChainTipData == null || peerChainTipData.getLastBlockSignature() == null || inferiorChainTips.contains(new ByteArray(peerChainTipData.getLastBlockSignature()));
 	};
 
+	public static final Predicate<Peer> hasOldVersion = peer -> {
+		final String minPeerVersion = Settings.getInstance().getMinPeerVersion();
+		return peer.isAtLeastVersion(minPeerVersion) == false;
+	};
+
 	private void potentiallySynchronize() throws InterruptedException {
 		// Already synchronizing via another thread?
 		if (this.isSynchronizing)
@@ -634,6 +656,17 @@ public class Controller extends Thread {
 		// Disregard peers that don't have a recent block
 		peers.removeIf(hasNoRecentBlock);
 
+		// Disregard peers that are on an old version
+		peers.removeIf(hasOldVersion);
+
+		checkRecoveryModeForPeers(peers);
+		if (recoveryMode) {
+			peers = Network.getInstance().getHandshakedPeers();
+			peers.removeIf(hasOnlyGenesisBlock);
+			peers.removeIf(hasMisbehaved);
+			peers.removeIf(hasOldVersion);
+		}
+
 		// Check we have enough peers to potentially synchronize
 		if (peers.size() < Settings.getInstance().getMinBlockchainPeers())
 			return;
@@ -644,9 +677,31 @@ public class Controller extends Thread {
 		// Disregard peers that are on the same block as last sync attempt and we didn't like their chain
 		peers.removeIf(hasInferiorChainTip);
 
+		final int peersBeforeComparison = peers.size();
+
+		// Request recent block summaries from the remaining peers, and locate our common block with each
+		Synchronizer.getInstance().findCommonBlocksWithPeers(peers);
+
+		// Compare the peers against each other, and against our chain, which will return an updated list excluding those without common blocks
+		peers = Synchronizer.getInstance().comparePeers(peers);
+
+		// We may have added more inferior chain tips when comparing peers, so remove any peers that are currently on those chains
+		peers.removeIf(hasInferiorChainTip);
+
+		final int peersRemoved = peersBeforeComparison - peers.size();
+		if (peersRemoved > 0 && peers.size() > 0)
+			LOGGER.debug(String.format("Ignoring %d peers on inferior chains. Peers remaining: %d", peersRemoved, peers.size()));
+
 		if (peers.isEmpty())
 			return;
 
+		if (peers.size() > 1) {
+			StringBuilder finalPeersString = new StringBuilder();
+			for (Peer peer : peers)
+				finalPeersString = finalPeersString.length() > 0 ? finalPeersString.append(", ").append(peer) : finalPeersString.append(peer);
+			LOGGER.debug(String.format("Choosing random peer from: [%s]", finalPeersString.toString()));
+		}
+
 		// Pick random peer to sync with
 		int index = new SecureRandom().nextInt(peers.size());
 		Peer peer = peers.get(index);
@@ -667,6 +722,7 @@ public class Controller extends Thread {
 				hasStatusChanged = true;
 			}
 		}
+		peer.setSyncInProgress(true);
 
 		if (hasStatusChanged)
 			updateSysTray();
@@ -746,9 +802,50 @@ public class Controller extends Thread {
 			return syncResult;
 		} finally {
 			isSynchronizing = false;
+			peer.setSyncInProgress(false);
 		}
 	}
 
+	private boolean checkRecoveryModeForPeers(List<Peer> qualifiedPeers) {
+		List<Peer> handshakedPeers = Network.getInstance().getHandshakedPeers();
+
+		if (handshakedPeers.size() > 0) {
+			// There is at least one handshaked peer
+			if (qualifiedPeers.isEmpty()) {
+				// There are no 'qualified' peers - i.e. peers that have a recent block we can sync to
+				boolean werePeersAvailable = peersAvailable;
+				peersAvailable = false;
+
+				// If peers only just became unavailable, update our record of the time they were last available
+				if (werePeersAvailable)
+					timePeersLastAvailable = NTP.getTime();
+
+				// If enough time has passed, enter recovery mode, which lifts some restrictions on who we can sync with and when we can mint
+				if (NTP.getTime() - timePeersLastAvailable > RECOVERY_MODE_TIMEOUT) {
+					if (recoveryMode == false) {
+						LOGGER.info(String.format("Peers have been unavailable for %d minutes. Entering recovery mode...", RECOVERY_MODE_TIMEOUT/60/1000));
+						recoveryMode = true;
+					}
+				}
+			} else {
+				// We now have at least one peer with a recent block, so we can exit recovery mode and sync normally
+				peersAvailable = true;
+				if (recoveryMode) {
+					LOGGER.info("Peers have become available again. Exiting recovery mode...");
+					recoveryMode = false;
+				}
+			}
+		}
+		return recoveryMode;
+	}
+
+	public void addInferiorChainSignature(byte[] inferiorSignature) {
+		// Update our list of inferior chain tips
+		ByteArray inferiorChainSignature = new ByteArray(inferiorSignature);
+		if (!inferiorChainSignatures.contains(inferiorChainSignature))
+			inferiorChainSignatures.add(inferiorChainSignature);
+	}
+
 	public static class StatusChangeEvent implements Event {
 		public StatusChangeEvent() {
 		}
@@ -757,6 +854,7 @@ public class Controller extends Thread {
 	private void updateSysTray() {
 		if (NTP.getTime() == null) {
 			SysTray.getInstance().setToolTipText(Translator.INSTANCE.translate("SysTray", "SYNCHRONIZING_CLOCK"));
+			SysTray.getInstance().setTrayIcon(1);
 			return;
 		}
 
@@ -770,17 +868,25 @@ public class Controller extends Thread {
 		String actionText;
 
 		synchronized (this.syncLock) {
-			if (this.isMintingPossible)
+			if (this.isMintingPossible) {
 				actionText = Translator.INSTANCE.translate("SysTray", "MINTING_ENABLED");
-			else if (this.isSynchronizing)
+				SysTray.getInstance().setTrayIcon(2);
+			}
+			else if (this.isSynchronizing) {
 				actionText = String.format("%s - %d%%", Translator.INSTANCE.translate("SysTray", "SYNCHRONIZING_BLOCKCHAIN"), this.syncPercent);
-			else if (numberOfPeers < Settings.getInstance().getMinBlockchainPeers())
+				SysTray.getInstance().setTrayIcon(3);
+			}
+			else if (numberOfPeers < Settings.getInstance().getMinBlockchainPeers()) {
 				actionText = Translator.INSTANCE.translate("SysTray", "CONNECTING");
-			else
+				SysTray.getInstance().setTrayIcon(3);
+			}
+			else {
 				actionText = Translator.INSTANCE.translate("SysTray", "MINTING_DISABLED");
+				SysTray.getInstance().setTrayIcon(4);
+			}
 		}
 
-		String tooltip = String.format("%s - %d %s - %s %d", actionText, numberOfPeers, connectionsText, heightText, height);
+		String tooltip = String.format("%s - %d %s - %s %d", actionText, numberOfPeers, connectionsText, heightText, height) + "\n" + String.format("Build version: %s", this.buildVersion);
 		SysTray.getInstance().setToolTipText(tooltip);
 
 		this.callbackExecutor.execute(() -> {
@@ -800,18 +906,26 @@ public class Controller extends Thread {
 
 			List<TransactionData> transactions = repository.getTransactionRepository().getUnconfirmedTransactions();
 
+			int deletedCount = 0;
 			for (TransactionData transactionData : transactions) {
 				Transaction transaction = Transaction.fromData(repository, transactionData);
 
 				if (now >= transaction.getDeadline()) {
-					LOGGER.info(() -> String.format("Deleting expired, unconfirmed transaction %s", Base58.encode(transactionData.getSignature())));
+					LOGGER.debug(() -> String.format("Deleting expired, unconfirmed transaction %s", Base58.encode(transactionData.getSignature())));
 					repository.getTransactionRepository().delete(transactionData);
+					deletedCount++;
 				}
 			}
+			if (deletedCount > 0) {
+				LOGGER.info(String.format("Deleted %d expired, unconfirmed transaction%s", deletedCount, (deletedCount == 1 ? "" : "s")));
+			}
 
 			repository.saveChanges();
 		} catch (DataException e) {
-			LOGGER.error("Repository issue while deleting expired unconfirmed transactions", e);
+			if (RepositoryManager.isDeadlockRelated(e))
+				LOGGER.info("Couldn't delete some expired, unconfirmed transactions this round");
+			else
+				LOGGER.error("Repository issue while deleting expired unconfirmed transactions", e);
 		}
 	}
 
@@ -935,6 +1049,7 @@ public class Controller extends Thread {
 	public void onNewBlock(BlockData latestBlockData) {
 		// Protective copy
 		BlockData blockDataCopy = new BlockData(latestBlockData);
+		int blockCacheSize = Settings.getInstance().getBlockCacheSize();
 
 		synchronized (this.latestBlocks) {
 			BlockData cachedChainTip = this.latestBlocks.peekLast();
@@ -944,7 +1059,7 @@ public class Controller extends Thread {
 				this.latestBlocks.addLast(latestBlockData);
 
 				// Trim if necessary
-				if (this.latestBlocks.size() >= BLOCK_CACHE_SIZE)
+				if (this.latestBlocks.size() >= blockCacheSize)
 					this.latestBlocks.pollFirst();
 			} else {
 				if (cachedChainTip != null)
@@ -1152,14 +1267,15 @@ public class Controller extends Thread {
 
 		ByteArray signatureAsByteArray = new ByteArray(signature);
 
-		BlockMessage cachedBlockMessage = this.blockMessageCache.get(signatureAsByteArray);
+		CachedBlockMessage cachedBlockMessage = this.blockMessageCache.get(signatureAsByteArray);
+		int blockCacheSize = Settings.getInstance().getBlockCacheSize();
 
 		// Check cached latest block message
 		if (cachedBlockMessage != null) {
 			this.stats.getBlockMessageStats.cacheHits.incrementAndGet();
 
 			// We need to duplicate it to prevent multiple threads setting ID on the same message
-			BlockMessage clonedBlockMessage = cachedBlockMessage.cloneWithNewId(message.getId());
+			CachedBlockMessage clonedBlockMessage = cachedBlockMessage.cloneWithNewId(message.getId());
 
 			if (!peer.sendMessage(clonedBlockMessage))
 				peer.disconnect("failed to send block");
@@ -1187,15 +1303,18 @@ public class Controller extends Thread {
 
 			Block block = new Block(repository, blockData);
 
-			BlockMessage blockMessage = new BlockMessage(block);
+			CachedBlockMessage blockMessage = new CachedBlockMessage(block);
 			blockMessage.setId(message.getId());
 
 			// This call also causes the other needed data to be pulled in from repository
-			if (!peer.sendMessage(blockMessage))
+			if (!peer.sendMessage(blockMessage)) {
 				peer.disconnect("failed to send block");
+				// Don't fall-through to caching because failure to send might be from failure to build message
+				return;
+			}
 
 			// If request is for a recent block, cache it
-			if (getChainHeight() - blockData.getHeight() <= BLOCK_CACHE_SIZE) {
+			if (getChainHeight() - blockData.getHeight() <= blockCacheSize) {
 				this.stats.getBlockMessageStats.cacheFills.incrementAndGet();
 
 				this.blockMessageCache.put(new ByteArray(blockData.getSignature()), blockMessage);
@@ -1209,6 +1328,18 @@ public class Controller extends Thread {
 		TransactionMessage transactionMessage = (TransactionMessage) message;
 		TransactionData transactionData = transactionMessage.getTransactionData();
 
+		/*
+		 *  If we can't obtain blockchain lock immediately,
+		 *  e.g. Synchronizer is active, or another transaction is taking a while to validate,
+		 *  then we're using up a network thread for ages and clogging things up
+		 *  so bail out early
+		 */
+		ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
+		if (!blockchainLock.tryLock()) {
+			LOGGER.trace(() -> String.format("Too busy to import %s transaction %s from peer %s", transactionData.getType().name(), Base58.encode(transactionData.getSignature()), peer));
+			return;
+		}
+
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			Transaction transaction = Transaction.fromData(repository, transactionData);
 
@@ -1238,6 +1369,8 @@ public class Controller extends Thread {
 			LOGGER.debug(() -> String.format("Imported %s transaction %s from peer %s", transactionData.getType().name(), Base58.encode(transactionData.getSignature()), peer));
 		} catch (DataException e) {
 			LOGGER.error(String.format("Repository issue while processing transaction %s from peer %s", Base58.encode(transactionData.getSignature()), peer), e);
+		} finally {
+			blockchainLock.unlock();
 		}
 	}
 

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

@@ -8,6 +8,7 @@ import java.util.Arrays;
 import java.util.List;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.stream.Collectors;
+import java.util.Iterator;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -15,8 +16,10 @@ 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 +35,32 @@ 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;
 
 	private static Synchronizer instance;
 
@@ -62,6 +80,406 @@ 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);
+							}
+						}
+
+						// 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;
+	}
+
+
 	/**
 	 * Attempt to synchronize blockchain with peer.
 	 * <p>
@@ -91,15 +509,31 @@ 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;
 
 					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 +583,19 @@ 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 +618,7 @@ 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 +647,12 @@ 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 +691,13 @@ 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 +746,9 @@ 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 +770,7 @@ 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 +795,142 @@ 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;
+			}
+
+			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 +939,19 @@ 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;
@@ -422,10 +973,13 @@ 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;
+
 			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()));
 				return SynchronizationResult.INVALID_DATA;
 			}
 
@@ -444,6 +998,7 @@ public class Synchronizer {
 			Controller.getInstance().onNewBlock(newBlock.getBlockData());
 		}
 
+		this.lastReorgSize = reorgSize;
 		return SynchronizationResult.OK;
 	}
 
@@ -469,7 +1024,8 @@ 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 +1044,9 @@ 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,
@@ -571,6 +1129,9 @@ 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/tradebot/AcctTradeBot.java

@@ -23,7 +23,7 @@ public interface AcctTradeBot {
 	public ResponseResult startResponse(Repository repository, ATData atData, ACCT acct,
 			CrossChainTradeData crossChainTradeData, String foreignKey, String receivingAddress) throws DataException;
 
-	public boolean canDelete(Repository repository, TradeBotData tradeBotData);
+	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/BitcoinACCTv1TradeBot.java

@@ -345,11 +345,15 @@ public class BitcoinACCTv1TradeBot implements AcctTradeBot {
 	}
 
 	@Override
-	public boolean canDelete(Repository repository, TradeBotData tradeBotData) {
+	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:
@@ -378,7 +382,7 @@ public class BitcoinACCTv1TradeBot implements AcctTradeBot {
 			// Attempt to fetch AT data
 			atData = repository.getATRepository().fromATAddress(tradeBotData.getAtAddress());
 			if (atData == null) {
-				LOGGER.warn(() -> String.format("Unable to fetch trade AT %s from repository", tradeBotData.getAtAddress()));
+				LOGGER.debug(() -> String.format("Unable to fetch trade AT %s from repository", tradeBotData.getAtAddress()));
 				return;
 			}
 
@@ -1029,7 +1033,7 @@ public class BitcoinACCTv1TradeBot implements AcctTradeBot {
 			return;
 		}
 
-		byte[] secretA = BitcoinACCTv1.findSecretA(repository, crossChainTradeData);
+		byte[] secretA = BitcoinACCTv1.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;

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

@@ -0,0 +1,883 @@
+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);
+
+		// 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
+		TradeBot.backupTradeBotData(repository);
+
+		// 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:
+				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/LitecoinACCTv1TradeBot.java

@@ -211,6 +211,9 @@ public class LitecoinACCTv1TradeBot implements AcctTradeBot {
 
 		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Built AT %s. Waiting for deployment", atAddress));
 
+		// Attempt to backup the trade bot data
+		TradeBot.backupTradeBotData(repository);
+
 		// Return to user for signing and broadcast as we don't have their Qortal private key
 		try {
 			return DeployAtTransactionTransformer.toBytes(deployAtTransactionData);
@@ -283,6 +286,9 @@ public class LitecoinACCTv1TradeBot implements AcctTradeBot {
 				tradeForeignPublicKey, tradeForeignPublicKeyHash,
 				crossChainTradeData.expectedForeignAmount, xprv58, null, lockTimeA, receivingPublicKeyHash);
 
+		// Attempt to backup the trade bot data
+		TradeBot.backupTradeBotData(repository);
+
 		// Check we have enough funds via xprv58 to fund P2SH to cover expectedForeignAmount
 		long p2shFee;
 		try {
@@ -343,11 +349,15 @@ public class LitecoinACCTv1TradeBot implements AcctTradeBot {
 	}
 
 	@Override
-	public boolean canDelete(Repository repository, TradeBotData tradeBotData) {
+	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:
@@ -376,7 +386,7 @@ public class LitecoinACCTv1TradeBot implements AcctTradeBot {
 			// Attempt to fetch AT data
 			atData = repository.getATRepository().fromATAddress(tradeBotData.getAtAddress());
 			if (atData == null) {
-				LOGGER.warn(() -> String.format("Unable to fetch trade AT %s from repository", tradeBotData.getAtAddress()));
+				LOGGER.debug(() -> String.format("Unable to fetch trade AT %s from repository", tradeBotData.getAtAddress()));
 				return;
 			}
 
@@ -706,16 +716,16 @@ public class LitecoinACCTv1TradeBot implements AcctTradeBot {
 			// Not finished yet
 			return;
 
-		// If AT is not REDEEMED then something has gone wrong
-		if (crossChainTradeData.mode != AcctMode.REDEEMED) {
-			// Not redeemed so must be refunded/cancelled
+		// 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.findSecretA(repository, crossChainTradeData);
+		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;

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

@@ -7,6 +7,7 @@ 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;
@@ -16,11 +17,7 @@ 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.ACCT;
-import org.qortal.crosschain.BitcoinACCTv1;
-import org.qortal.crosschain.ForeignBlockchainException;
-import org.qortal.crosschain.LitecoinACCTv1;
-import org.qortal.crosschain.SupportedBlockchain;
+import org.qortal.crosschain.*;
 import org.qortal.data.at.ATData;
 import org.qortal.data.crosschain.CrossChainTradeData;
 import org.qortal.data.crosschain.TradeBotData;
@@ -79,6 +76,7 @@ public class TradeBot implements Listener {
 	static {
 		acctTradeBotSuppliers.put(BitcoinACCTv1.class, BitcoinACCTv1TradeBot::getInstance);
 		acctTradeBotSuppliers.put(LitecoinACCTv1.class, LitecoinACCTv1TradeBot::getInstance);
+		acctTradeBotSuppliers.put(DogecoinACCTv1.class, DogecoinACCTv1TradeBot::getInstance);
 	}
 
 	private static TradeBot instance;
@@ -267,6 +265,16 @@ public class TradeBot implements Listener {
 		return secret;
 	}
 
+	/*package*/ static void backupTradeBotData(Repository repository) {
+		// 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...");
+			repository.exportNodeLocalData();
+		} 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 {

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

@@ -20,4 +20,6 @@ public interface ACCT {
 
 	public byte[] buildCancelMessage(String creatorQortalAddress);
 
+	public byte[] findSecretA(Repository repository, CrossChainTradeData crossChainTradeData) throws DataException;
+
 }

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

@@ -42,35 +42,36 @@ public class Bitcoin extends Bitcoiny {
 			public Collection<ElectrumX.Server> getServers() {
 				return 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("128.0.190.26", Server.ConnectionType.SSL, 50002),
+						new Server("hodlers.beer", Server.ConnectionType.SSL, 50002),
+						new Server("electrumx.erbium.eu", Server.ConnectionType.TCP, 50001),
+						new Server("electrumx.erbium.eu", 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("2electrumx.hopto.me", Server.ConnectionType.SSL, 56022),
+						new Server("185.64.116.15", Server.ConnectionType.SSL, 50002),
+						new Server("kirsche.emzy.de", Server.ConnectionType.SSL, 50002),
+						new Server("alviss.coinjoined.com", Server.ConnectionType.SSL, 50002),
+						new Server("electrum.emzy.de", Server.ConnectionType.SSL, 50002),
 						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));
+						new Server("vmd71287.contaboserver.net", Server.ConnectionType.SSL, 50002),
+						new Server("btc.litepay.ch", Server.ConnectionType.SSL, 50002),
+						new Server("electrum.stippy.com", Server.ConnectionType.SSL, 50002),
+						new Server("xtrum.com", Server.ConnectionType.SSL, 50002),
+						new Server("electrum.acinq.co", Server.ConnectionType.SSL, 50002),
+						new Server("electrum2.taborsky.cz", Server.ConnectionType.SSL, 50002),
+						new Server("vmd63185.contaboserver.net", Server.ConnectionType.SSL, 50002),
+						new Server("electrum2.privateservers.network", Server.ConnectionType.SSL, 50002),
+						new Server("electrumx.alexridevski.net", Server.ConnectionType.SSL, 50002),
+						new Server("192.166.219.200", Server.ConnectionType.SSL, 50002),
+						new Server("2ex.digitaleveryware.com", Server.ConnectionType.SSL, 50002),
+						new Server("dxm.no-ip.biz", Server.ConnectionType.SSL, 50002),
+						new Server("caleb.vegas", Server.ConnectionType.SSL, 50002),
+						new Server("ecdsa.net", Server.ConnectionType.SSL, 110),
+						new Server("electrum.hsmiths.com", Server.ConnectionType.SSL, 995),
+						new Server("elec.luggs.co", Server.ConnectionType.SSL, 443),
+						new Server("btc.smsys.me", Server.ConnectionType.SSL, 995));
 			}
 
 			@Override
@@ -96,10 +97,8 @@ public class Bitcoin extends Bitcoiny {
 			@Override
 			public Collection<ElectrumX.Server> getServers() {
 				return Arrays.asList(
-						new Server("electrum.blockstream.info", Server.ConnectionType.TCP, 60001),
-						new Server("electrum.blockstream.info", Server.ConnectionType.SSL, 60002),
+						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.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),

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

@@ -872,7 +872,8 @@ public class BitcoinACCTv1 implements ACCT {
 		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/Bitcoiny.java

@@ -91,7 +91,7 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 		return this.params;
 	}
 
-	// Interface obligations 
+	// Interface obligations
 
 	@Override
 	public boolean isValidAddress(String address) {
@@ -169,9 +169,14 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 		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
@@ -271,7 +276,7 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 
 	/**
 	 * Returns bitcoinj transaction sending <tt>amount</tt> to <tt>recipient</tt>.
-	 * 
+	 *
 	 * @param xprv58 BIP32 private key
 	 * @param recipient P2PKH address
 	 * @param amount unscaled amount
@@ -303,7 +308,7 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 
 	/**
 	 * 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
@@ -332,7 +337,7 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 		return balance.value;
 	}
 
-	public List<BitcoinyTransaction> getWalletTransactions(String key58) throws ForeignBlockchainException {
+	public List<SimpleTransaction> getWalletTransactions(String key58) throws ForeignBlockchainException {
 		Context.propagate(bitcoinjContext);
 
 		Wallet wallet = walletFromDeterministicKey58(key58);
@@ -344,7 +349,12 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 		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;
@@ -354,6 +364,7 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 
 				// 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
@@ -367,9 +378,19 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 				}
 			}
 
-			if (areAllKeysUnused)
-				// No transactions for this batch of keys so assume we're done searching.
-				break;
+			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));
@@ -377,7 +398,56 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 			// Process new keys
 		} while (true);
 
-		return walletTransactions.stream().collect(Collectors.toList());
+		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);
 	}
 
 	/**
@@ -419,7 +489,7 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 				 * 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.
 				 */
 
@@ -499,7 +569,7 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 					 * 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.
 					 */
 

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

@@ -10,7 +10,6 @@ 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;
@@ -25,6 +24,7 @@ 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;

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/ElectrumX.java

@@ -33,6 +33,7 @@ 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 Bitcoiny-related info like block headers, transaction outputs, etc. */
 public class ElectrumX extends BitcoinyBlockchainProvider {
@@ -171,13 +172,41 @@ public class ElectrumX extends BitcoinyBlockchainProvider {
 		Long returnedCount = (Long) countObj;
 		String hex = (String) hexObj;
 
-		byte[] raw = HashCode.fromString(hex).asBytes();
-		if (raw.length != returnedCount * BLOCK_HEADER_LENGTH)
-			throw new ForeignBlockchainException.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;
 	}
@@ -518,6 +547,7 @@ public class ElectrumX extends BitcoinyBlockchainProvider {
 			}
 
 			// 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));
 		}
 	}

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

@@ -6,4 +6,6 @@ public interface ForeignBlockchain {
 
 	public boolean isValidWalletKey(String walletKey);
 
+	public long getMinimumOrderAmount();
+
 }

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

@@ -51,7 +51,10 @@ public class Litecoin extends Bitcoiny {
 						new Server("ltc.rentonisk.com", Server.ConnectionType.TCP, 50001),
 						new Server("ltc.rentonisk.com", Server.ConnectionType.SSL, 50002),
 						new Server("electrum-ltc.petrkr.net", Server.ConnectionType.SSL, 60002),
-						new Server("ltc.litepay.ch", Server.ConnectionType.SSL, 50022));
+						new Server("ltc.litepay.ch", Server.ConnectionType.SSL, 50022),
+						new Server("electrum-ltc-bysh.me", Server.ConnectionType.TCP, 50002),
+						new Server("electrum.jochen-hoenicke.de", Server.ConnectionType.TCP, 50005),
+						new Server("node.ispol.sk", Server.ConnectionType.TCP, 50004));
 			}
 
 			@Override

src/main/java/org/qortal/crosschain/LitecoinACCTv1.java

@@ -810,7 +810,8 @@ public class LitecoinACCTv1 implements ACCT {
 		return (int) ((lockTimeA - (offerMessageTimestamp / 1000L)) / 2L / 60L);
 	}
 
-	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/SimpleTransaction.java

@@ -0,0 +1,109 @@
+package org.qortal.crosschain;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import java.util.List;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class SimpleTransaction {
+    private String txHash;
+    private Integer timestamp;
+    private long totalAmount;
+    private long feeAmount;
+    private List<Input> inputs;
+    private List<Output> outputs;
+
+
+    @XmlAccessorType(XmlAccessType.FIELD)
+    public static class Input {
+        private String address;
+        private long amount;
+        private boolean addressInWallet;
+
+        public Input() {
+        }
+
+        public Input(String address, long amount, boolean addressInWallet) {
+            this.address = address;
+            this.amount = amount;
+            this.addressInWallet = addressInWallet;
+        }
+
+        public String getAddress() {
+            return address;
+        }
+
+        public long getAmount() {
+            return amount;
+        }
+
+        public boolean getAddressInWallet() {
+            return addressInWallet;
+        }
+    }
+
+    @XmlAccessorType(XmlAccessType.FIELD)
+    public static class Output {
+        private String address;
+        private long amount;
+        private boolean addressInWallet;
+
+        public Output() {
+        }
+
+        public Output(String address, long amount, boolean addressInWallet) {
+            this.address = address;
+            this.amount = amount;
+            this.addressInWallet = addressInWallet;
+        }
+
+        public String getAddress() {
+            return address;
+        }
+
+        public long getAmount() {
+            return amount;
+        }
+
+        public boolean getAddressInWallet() {
+            return addressInWallet;
+        }
+    }
+
+
+    public SimpleTransaction() {
+    }
+
+    public SimpleTransaction(String txHash, Integer timestamp, long totalAmount, long feeAmount, List<Input> inputs, List<Output> outputs) {
+        this.txHash = txHash;
+        this.timestamp = timestamp;
+        this.totalAmount = totalAmount;
+        this.feeAmount = feeAmount;
+        this.inputs = inputs;
+        this.outputs = outputs;
+    }
+
+    public String getTxHash() {
+        return txHash;
+    }
+
+    public Integer getTimestamp() {
+        return timestamp;
+    }
+
+    public long getTotalAmount() {
+        return totalAmount;
+    }
+
+    public long getFeeAmount() {
+        return feeAmount;
+    }
+
+    public List<Input> getInputs() {
+        return this.inputs;
+    }
+
+    public List<Output> getOutputs() {
+        return this.outputs;
+    }
+}

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

@@ -39,6 +39,20 @@ public enum SupportedBlockchain {
 		public ACCT getLatestAcct() {
 			return LitecoinACCTv1.getInstance();
 		}
+	},
+
+	DOGECOIN(Arrays.asList(
+			Triple.valueOf(DogecoinACCTv1.NAME, DogecoinACCTv1.CODE_BYTES_HASH, DogecoinACCTv1::getInstance)
+		)) {
+		@Override
+		public ForeignBlockchain getInstance() {
+			return Dogecoin.getInstance();
+		}
+
+		@Override
+		public ACCT getLatestAcct() {
+			return DogecoinACCTv1.getInstance();
+		}
 	};
 
 	private static final Map<ByteArray, Supplier<ACCT>> supportedAcctsByCodeHash = Arrays.stream(SupportedBlockchain.values())
@@ -110,4 +124,4 @@ public enum SupportedBlockchain {
 		return acctInstanceSupplier.get();
 	}
 
-}
+}

src/main/java/org/qortal/data/at/ATData.java

@@ -23,6 +23,7 @@ public class ATData {
 	private boolean isFrozen;
 	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
 	private Long frozenBalance;
+	private Long sleepUntilMessageTimestamp;
 
 	// Constructors
 
@@ -31,7 +32,8 @@ public class ATData {
 	}
 
 	public ATData(String ATAddress, byte[] creatorPublicKey, long creation, int version, long assetId, byte[] codeBytes, byte[] codeHash,
-			boolean isSleeping, Integer sleepUntilHeight, boolean isFinished, boolean hadFatalError, boolean isFrozen, Long frozenBalance) {
+			boolean isSleeping, Integer sleepUntilHeight, boolean isFinished, boolean hadFatalError, boolean isFrozen, Long frozenBalance,
+			Long sleepUntilMessageTimestamp) {
 		this.ATAddress = ATAddress;
 		this.creatorPublicKey = creatorPublicKey;
 		this.creation = creation;
@@ -45,6 +47,7 @@ public class ATData {
 		this.hadFatalError = hadFatalError;
 		this.isFrozen = isFrozen;
 		this.frozenBalance = frozenBalance;
+		this.sleepUntilMessageTimestamp = sleepUntilMessageTimestamp;
 	}
 
 	/** For constructing skeleton ATData with bare minimum info. */
@@ -133,4 +136,12 @@ public class ATData {
 		this.frozenBalance = frozenBalance;
 	}
 
+	public Long getSleepUntilMessageTimestamp() {
+		return this.sleepUntilMessageTimestamp;
+	}
+
+	public void setSleepUntilMessageTimestamp(Long sleepUntilMessageTimestamp) {
+		this.sleepUntilMessageTimestamp = sleepUntilMessageTimestamp;
+	}
+
 }

src/main/java/org/qortal/data/at/ATStateData.java

@@ -10,35 +10,32 @@ public class ATStateData {
 	private Long fees;
 	private boolean isInitial;
 
+	// Qortal-AT-specific
+	private Long sleepUntilMessageTimestamp;
+
 	// Constructors
 
 	/** Create new ATStateData */
-	public ATStateData(String ATAddress, Integer height, byte[] stateData, byte[] stateHash, Long fees, boolean isInitial) {
+	public ATStateData(String ATAddress, Integer height, byte[] stateData, byte[] stateHash, Long fees,
+			boolean isInitial, Long sleepUntilMessageTimestamp) {
 		this.ATAddress = ATAddress;
 		this.height = height;
 		this.stateData = stateData;
 		this.stateHash = stateHash;
 		this.fees = fees;
 		this.isInitial = isInitial;
+		this.sleepUntilMessageTimestamp = sleepUntilMessageTimestamp;
 	}
 
 	/** For recreating per-block ATStateData from repository where not all info is needed */
 	public ATStateData(String ATAddress, int height, byte[] stateHash, Long fees, boolean isInitial) {
-		this(ATAddress, height, null, stateHash, fees, isInitial);
-	}
-
-	/** For creating ATStateData from serialized bytes when we don't have all the info */
-	public ATStateData(String ATAddress, byte[] stateHash) {
-		// This won't ever be initial AT state from deployment as that's never serialized over the network,
-		// but generated when the DeployAtTransaction is processed locally.
-		this(ATAddress, null, null, stateHash, null, false);
+		this(ATAddress, height, null, stateHash, fees, isInitial, null);
 	}
 
 	/** For creating ATStateData from serialized bytes when we don't have all the info */
 	public ATStateData(String ATAddress, byte[] stateHash, Long fees) {
-		// This won't ever be initial AT state from deployment as that's never serialized over the network,
-		// but generated when the DeployAtTransaction is processed locally.
-		this(ATAddress, null, null, stateHash, fees, false);
+		// This won't ever be initial AT state from deployment, as that's never serialized over the network.
+		this(ATAddress, null, null, stateHash, fees, false, null);
 	}
 
 	// Getters / setters
@@ -72,4 +69,12 @@ public class ATStateData {
 		return this.isInitial;
 	}
 
+	public Long getSleepUntilMessageTimestamp() {
+		return this.sleepUntilMessageTimestamp;
+	}
+
+	public void setSleepUntilMessageTimestamp(Long sleepUntilMessageTimestamp) {
+		this.sleepUntilMessageTimestamp = sleepUntilMessageTimestamp;
+	}
+
 }

src/main/java/org/qortal/data/block/BlockSummaryData.java

@@ -2,6 +2,7 @@ package org.qortal.data.block;
 
 import javax.xml.bind.annotation.XmlAccessType;
 import javax.xml.bind.annotation.XmlAccessorType;
+import java.util.Arrays;
 
 @XmlAccessorType(XmlAccessType.FIELD)
 public class BlockSummaryData {
@@ -84,4 +85,21 @@ public class BlockSummaryData {
 		this.minterLevel = minterLevel;
 	}
 
+
+	@Override
+	public boolean equals(Object o) {
+		if (this == o)
+			return true;
+
+		if (o == null || getClass() != o.getClass())
+			return false;
+
+		BlockSummaryData otherBlockSummary = (BlockSummaryData) o;
+		if (this.getSignature() == null || otherBlockSummary.getSignature() == null)
+			return false;
+
+		// Treat two block summaries as equal if they have matching signatures
+		return Arrays.equals(this.getSignature(), otherBlockSummary.getSignature());
+	}
+
 }

src/main/java/org/qortal/data/block/CommonBlockData.java

@@ -0,0 +1,56 @@
+package org.qortal.data.block;
+
+import org.qortal.data.network.PeerChainTipData;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import java.math.BigInteger;
+import java.util.List;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class CommonBlockData {
+
+	// Properties
+	private BlockSummaryData commonBlockSummary = null;
+	private List<BlockSummaryData> blockSummariesAfterCommonBlock = null;
+	private BigInteger chainWeight = null;
+	private PeerChainTipData chainTipData = null;
+
+	// Constructors
+
+	protected CommonBlockData() {
+	}
+
+	public CommonBlockData(BlockSummaryData commonBlockSummary, PeerChainTipData chainTipData) {
+		this.commonBlockSummary = commonBlockSummary;
+		this.chainTipData = chainTipData;
+	}
+
+
+	// Getters / setters
+
+	public BlockSummaryData getCommonBlockSummary() {
+		return this.commonBlockSummary;
+	}
+
+	public List<BlockSummaryData> getBlockSummariesAfterCommonBlock() {
+		return this.blockSummariesAfterCommonBlock;
+	}
+
+	public void setBlockSummariesAfterCommonBlock(List<BlockSummaryData> blockSummariesAfterCommonBlock) {
+		this.blockSummariesAfterCommonBlock = blockSummariesAfterCommonBlock;
+	}
+
+	public BigInteger getChainWeight() {
+		return this.chainWeight;
+	}
+
+	public void setChainWeight(BigInteger chainWeight) {
+		this.chainWeight = chainWeight;
+	}
+
+	public PeerChainTipData getChainTipData() {
+		return this.chainTipData;
+	}
+
+}

src/main/java/org/qortal/data/crosschain/TradeBotData.java

@@ -6,6 +6,9 @@ import javax.xml.bind.annotation.XmlTransient;
 import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
 
 import io.swagger.v3.oas.annotations.media.Schema;
+import org.json.JSONObject;
+
+import org.qortal.utils.Base58;
 
 // All properties to be converted to JSON via JAXB
 @XmlAccessorType(XmlAccessType.FIELD)
@@ -205,6 +208,58 @@ public class TradeBotData {
 		return this.receivingAccountInfo;
 	}
 
+	public JSONObject toJson() {
+		JSONObject jsonObject = new JSONObject();
+		jsonObject.put("tradePrivateKey", Base58.encode(this.getTradePrivateKey()));
+		jsonObject.put("acctName", this.getAcctName());
+		jsonObject.put("tradeState", this.getState());
+		jsonObject.put("tradeStateValue", this.getStateValue());
+		jsonObject.put("creatorAddress", this.getCreatorAddress());
+		jsonObject.put("atAddress", this.getAtAddress());
+		jsonObject.put("timestamp", this.getTimestamp());
+		jsonObject.put("qortAmount", this.getQortAmount());
+		if (this.getTradeNativePublicKey() != null) jsonObject.put("tradeNativePublicKey", Base58.encode(this.getTradeNativePublicKey()));
+		if (this.getTradeNativePublicKeyHash() != null) jsonObject.put("tradeNativePublicKeyHash", Base58.encode(this.getTradeNativePublicKeyHash()));
+		jsonObject.put("tradeNativeAddress", this.getTradeNativeAddress());
+		if (this.getSecret() != null) jsonObject.put("secret", Base58.encode(this.getSecret()));
+		if (this.getHashOfSecret() != null) jsonObject.put("hashOfSecret", Base58.encode(this.getHashOfSecret()));
+		jsonObject.put("foreignBlockchain", this.getForeignBlockchain());
+		if (this.getTradeForeignPublicKey() != null) jsonObject.put("tradeForeignPublicKey", Base58.encode(this.getTradeForeignPublicKey()));
+		if (this.getTradeForeignPublicKeyHash() != null) jsonObject.put("tradeForeignPublicKeyHash", Base58.encode(this.getTradeForeignPublicKeyHash()));
+		jsonObject.put("foreignKey", this.getForeignKey());
+        jsonObject.put("foreignAmount", this.getForeignAmount());
+		if (this.getLastTransactionSignature() != null) jsonObject.put("lastTransactionSignature", Base58.encode(this.getLastTransactionSignature()));
+        jsonObject.put("lockTimeA", this.getLockTimeA());
+		if (this.getReceivingAccountInfo() != null) jsonObject.put("receivingAccountInfo", Base58.encode(this.getReceivingAccountInfo()));
+		return jsonObject;
+	}
+
+	public static TradeBotData fromJson(JSONObject json) {
+		return new TradeBotData(
+				json.isNull("tradePrivateKey") ? null : Base58.decode(json.getString("tradePrivateKey")),
+				json.isNull("acctName") ? null : json.getString("acctName"),
+				json.isNull("tradeState") ? null : json.getString("tradeState"),
+				json.isNull("tradeStateValue") ? null : json.getInt("tradeStateValue"),
+				json.isNull("creatorAddress") ? null : json.getString("creatorAddress"),
+				json.isNull("atAddress") ? null : json.getString("atAddress"),
+				json.isNull("timestamp") ? null : json.getLong("timestamp"),
+				json.isNull("qortAmount") ? null : json.getLong("qortAmount"),
+				json.isNull("tradeNativePublicKey") ? null : Base58.decode(json.getString("tradeNativePublicKey")),
+				json.isNull("tradeNativePublicKeyHash") ? null : Base58.decode(json.getString("tradeNativePublicKeyHash")),
+				json.isNull("tradeNativeAddress") ? null : json.getString("tradeNativeAddress"),
+				json.isNull("secret") ? null : Base58.decode(json.getString("secret")),
+				json.isNull("hashOfSecret") ? null : Base58.decode(json.getString("hashOfSecret")),
+				json.isNull("foreignBlockchain") ? null : json.getString("foreignBlockchain"),
+				json.isNull("tradeForeignPublicKey") ? null : Base58.decode(json.getString("tradeForeignPublicKey")),
+				json.isNull("tradeForeignPublicKeyHash") ? null : Base58.decode(json.getString("tradeForeignPublicKeyHash")),
+				json.isNull("foreignAmount") ? null : json.getLong("foreignAmount"),
+				json.isNull("foreignKey") ? null : json.getString("foreignKey"),
+				json.isNull("lastTransactionSignature") ? null : Base58.decode(json.getString("lastTransactionSignature")),
+				json.isNull("lockTimeA") ? null : json.getInt("lockTimeA"),
+				json.isNull("receivingAccountInfo") ? null : Base58.decode(json.getString("receivingAccountInfo"))
+		);
+	}
+
 	// Mostly for debugging
 	public String toString() {
 		return String.format("%s: %s (%d)", this.atAddress, this.tradeState, this.tradeStateValue);

src/main/java/org/qortal/gui/SplashFrame.java

@@ -1,15 +1,11 @@
 package org.qortal.gui;
 
-import java.awt.BorderLayout;
-import java.awt.Image;
+import java.awt.*;
 import java.util.ArrayList;
 import java.util.List;
-import java.awt.Dimension;
-import java.awt.Graphics;
 import java.awt.image.BufferedImage;
 
-import javax.swing.JDialog;
-import javax.swing.JPanel;
+import javax.swing.*;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -19,46 +15,53 @@ public class SplashFrame {
 	protected static final Logger LOGGER = LogManager.getLogger(SplashFrame.class);
 
 	private static SplashFrame instance;
-	private JDialog splashDialog;
+	private JFrame splashDialog;
 
 	@SuppressWarnings("serial")
 	public static class SplashPanel extends JPanel {
 		private BufferedImage image;
 
+		private String defaultSplash = "Qlogo_512.png";
+
 		public SplashPanel() {
-			image = Gui.loadImage("splash.png");
-			this.setPreferredSize(new Dimension(image.getWidth(), image.getHeight()));
-			this.setLayout(new BorderLayout());
+			image = Gui.loadImage(defaultSplash);
+
+			setOpaque(false);
+			setLayout(new GridBagLayout());
 		}
 
 		@Override
 		protected void paintComponent(Graphics g) {
 			super.paintComponent(g);
-			g.drawImage(image, 0, 0, null);
+			g.drawImage(image, 0, 0, getWidth(), getHeight(), this);
+		}
+
+		@Override
+		public Dimension getPreferredSize() {
+			return new Dimension(500, 500);
 		}
 	}
 
 	private SplashFrame() {
-		this.splashDialog = new JDialog();
+		this.splashDialog = new JFrame();
 
 		List<Image> icons = new ArrayList<>();
 		icons.add(Gui.loadImage("icons/icon16.png"));
-		icons.add(Gui.loadImage("icons/icon32.png"));
+		icons.add(Gui.loadImage("icons/qortal_ui_tray_synced.png"));
+		icons.add(Gui.loadImage("icons/qortal_ui_tray_syncing_time-alt.png"));
+		icons.add(Gui.loadImage("icons/qortal_ui_tray_minting.png"));
+		icons.add(Gui.loadImage("icons/qortal_ui_tray_syncing.png"));
 		icons.add(Gui.loadImage("icons/icon64.png"));
-		icons.add(Gui.loadImage("icons/icon128.png"));
+		icons.add(Gui.loadImage("icons/Qlogo_128.png"));
 		this.splashDialog.setIconImages(icons);
 
-		this.splashDialog.setDefaultCloseOperation(JDialog.DO_NOTHING_ON_CLOSE);
-		this.splashDialog.setTitle("qortal");
-		this.splashDialog.setContentPane(new SplashPanel());
-
+		this.splashDialog.getContentPane().add(new SplashPanel());
+		this.splashDialog.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
 		this.splashDialog.setUndecorated(true);
-		this.splashDialog.setModal(false);
 		this.splashDialog.pack();
 		this.splashDialog.setLocationRelativeTo(null);
-		this.splashDialog.toFront();
+		this.splashDialog.setBackground(new Color(0,0,0,0));
 		this.splashDialog.setVisible(true);
-		this.splashDialog.repaint();
 	}
 
 	public static SplashFrame getInstance() {

src/main/java/org/qortal/gui/SysTray.java

@@ -61,7 +61,7 @@ public class SysTray {
 		this.popupMenu = createJPopupMenu();
 
 		// Build TrayIcon without AWT PopupMenu (which doesn't support Unicode)...
-		this.trayIcon = new TrayIcon(Gui.loadImage("icons/icon32.png"), "qortal", null);
+		this.trayIcon = new TrayIcon(Gui.loadImage("icons/qortal_ui_tray_synced.png"), "qortal", null);
 		// ...and attach mouse listener instead so we can use JPopupMenu (which does support Unicode)
 		this.trayIcon.addMouseListener(new MouseAdapter() {
 			@Override
@@ -289,6 +289,25 @@ public class SysTray {
 			this.trayIcon.setToolTip(text);
 	}
 
+	public void setTrayIcon(int iconid) {
+		if (trayIcon != null) {
+			switch (iconid) {
+				case 1:
+					this.trayIcon.setImage(Gui.loadImage("icons/qortal_ui_tray_syncing_time-alt.png"));
+					break;
+				case 2:
+					this.trayIcon.setImage(Gui.loadImage("icons/qortal_ui_tray_minting.png"));
+					break;
+				case 3:
+					this.trayIcon.setImage(Gui.loadImage("icons/qortal_ui_tray_syncing.png"));
+					break;
+				case 4:
+					this.trayIcon.setImage(Gui.loadImage("icons/qortal_ui_tray_synced.png"));
+					break;
+			}
+		}
+	}
+
 	public void dispose() {
 		if (trayIcon != null)
 			SystemTray.getSystemTray().remove(this.trayIcon);

src/main/java/org/qortal/list/ResourceList.java

@@ -0,0 +1,137 @@
+package org.qortal.list;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.json.JSONArray;
+import org.qortal.settings.Settings;
+
+import java.io.BufferedWriter;
+import java.io.File;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.List;
+
+public class ResourceList {
+
+    private static final Logger LOGGER = LogManager.getLogger(ResourceList.class);
+
+    private String category;
+    private String resourceName;
+    private List<String> list;
+
+    /**
+     * ResourceList
+     * Creates or updates a list for the purpose of tracking resources on the Qortal network
+     * This can be used for local blocking, or even for curating and sharing content lists
+     * Lists are backed off to JSON files (in the lists folder) to ease sharing between nodes and users
+     *
+     * @param category - for instance "blacklist", "whitelist", or "userlist"
+     * @param resourceName - for instance "address", "poll", or "group"
+     * @throws IOException
+     */
+    public ResourceList(String category, String resourceName) throws IOException {
+        this.category = category;
+        this.resourceName = resourceName;
+        this.load();
+    }
+
+
+    /* Filesystem */
+
+    private Path getFilePath() {
+        String pathString = String.format("%s%s%s_%s.json", Settings.getInstance().getListsPath(),
+                File.separator, this.resourceName, this.category);
+        Path outputFilePath = Paths.get(pathString);
+        try {
+            Files.createDirectories(outputFilePath.getParent());
+        } catch (IOException e) {
+            throw new IllegalStateException("Unable to create lists directory");
+        }
+        return outputFilePath;
+    }
+
+    public void save() throws IOException {
+        if (this.resourceName == null) {
+            throw new IllegalStateException("Can't save list with missing resource name");
+        }
+        if (this.category == null) {
+            throw new IllegalStateException("Can't save list with missing category");
+        }
+        String jsonString = ResourceList.listToJSONString(this.list);
+
+        Path filePath = this.getFilePath();
+        BufferedWriter writer = new BufferedWriter(new FileWriter(filePath.toString()));
+        writer.write(jsonString);
+        writer.close();
+    }
+
+    private boolean load() throws IOException {
+        Path path = this.getFilePath();
+        File resourceListFile = new File(path.toString());
+        if (!resourceListFile.exists()) {
+            return false;
+        }
+
+        try {
+            String jsonString = new String(Files.readAllBytes(path));
+            this.list = ResourceList.listFromJSONString(jsonString);
+        } catch (IOException e) {
+            throw new IOException(String.format("Couldn't read contents from file %s", path.toString()));
+        }
+
+        return true;
+    }
+
+    public boolean revert() {
+        try {
+            return this.load();
+        } catch (IOException e) {
+            LOGGER.info("Unable to revert {} {}", this.resourceName, this.category);
+        }
+        return false;
+    }
+
+
+    /* List management */
+
+    public void add(String resource) {
+        if (!this.contains(resource)) {
+            this.list.add(resource);
+        }
+    }
+
+    public void remove(String resource) {
+        this.list.remove(resource);
+    }
+
+    public boolean contains(String resource) {
+        return this.list.contains(resource);
+    }
+
+
+
+    /* Utils */
+
+    public static String listToJSONString(List<String> list) {
+        JSONArray items = new JSONArray();
+        for (String item : list) {
+            items.put(item);
+        }
+        return items.toString(4);
+    }
+
+    private static List<String> listFromJSONString(String jsonString) {
+        JSONArray jsonList = new JSONArray(jsonString);
+        List<String> resourceList = new ArrayList<>();
+        for (int i=0; i<jsonList.length(); i++) {
+            String item = (String)jsonList.get(i);
+            resourceList.add(item);
+        }
+        return resourceList;
+    }
+
+}

src/main/java/org/qortal/list/ResourceListManager.java

@@ -0,0 +1,87 @@
+package org.qortal.list;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+import java.io.IOException;
+
+public class ResourceListManager {
+
+    private static final Logger LOGGER = LogManager.getLogger(ResourceListManager.class);
+
+    private static ResourceListManager instance;
+    private ResourceList addressBlacklist;
+
+    public ResourceListManager() {
+        try {
+            this.addressBlacklist = new ResourceList("blacklist", "address");
+        } catch (IOException e) {
+            LOGGER.info("Error while loading address blacklist. Blocking is currently unavailable.");
+        }
+    }
+
+    public static synchronized ResourceListManager getInstance() {
+        if (instance == null) {
+            instance = new ResourceListManager();
+        }
+
+        return instance;
+    }
+
+    public boolean addAddressToBlacklist(String address, boolean save) {
+        try {
+            this.addressBlacklist.add(address);
+            if (save) {
+                this.addressBlacklist.save();
+            }
+            return true;
+
+        } catch (IllegalStateException | IOException e) {
+            LOGGER.info("Unable to add address to blacklist", e);
+            return false;
+        }
+    }
+
+    public boolean removeAddressFromBlacklist(String address, boolean save) {
+        try {
+            this.addressBlacklist.remove(address);
+
+            if (save) {
+                this.addressBlacklist.save();
+            }
+            return true;
+
+        } catch (IllegalStateException | IOException e) {
+            LOGGER.info("Unable to remove address from blacklist", e);
+            return false;
+        }
+    }
+
+    public boolean isAddressInBlacklist(String address) {
+        if (this.addressBlacklist == null) {
+            return false;
+        }
+        return this.addressBlacklist.contains(address);
+    }
+
+    public void saveBlacklist() {
+        if (this.addressBlacklist == null) {
+            return;
+        }
+
+        try {
+            this.addressBlacklist.save();
+        } catch (IOException e) {
+            LOGGER.info("Unable to save blacklist - reverting back to last saved state");
+            this.addressBlacklist.revert();
+        }
+    }
+
+    public void revertBlacklist() {
+        if (this.addressBlacklist == null) {
+            return;
+        }
+        this.addressBlacklist.revert();
+    }
+
+}

src/main/java/org/qortal/network/Handshake.java

@@ -4,7 +4,6 @@ import java.util.Arrays;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -51,7 +50,7 @@ public enum Handshake {
 
 			String versionString = helloMessage.getVersionString();
 
-			Matcher matcher = VERSION_PATTERN.matcher(versionString);
+			Matcher matcher = peer.VERSION_PATTERN.matcher(versionString);
 			if (!matcher.lookingAt()) {
 				LOGGER.debug(() -> String.format("Peer %s sent invalid HELLO version string '%s'", peer, versionString));
 				return null;
@@ -72,6 +71,15 @@ public enum Handshake {
 			peer.setPeersConnectionTimestamp(peersConnectionTimestamp);
 			peer.setPeersVersion(versionString, version);
 
+			if (Settings.getInstance().getAllowConnectionsWithOlderPeerVersions() == false) {
+				// Ensure the peer is running at least the minimum version allowed for connections
+				final String minPeerVersion = Settings.getInstance().getMinPeerVersion();
+				if (peer.isAtLeastVersion(minPeerVersion) == false) {
+					LOGGER.debug(String.format("Ignoring peer %s because it is on an old version (%s)", peer, versionString));
+					return null;
+				}
+			}
+
 			return CHALLENGE;
 		}
 
@@ -244,8 +252,6 @@ public enum Handshake {
 	/** Maximum allowed difference between peer's reported timestamp and when they connected, in milliseconds. */
 	private static final long MAX_TIMESTAMP_DELTA = 30 * 1000L; // ms
 
-	private static final Pattern VERSION_PATTERN = Pattern.compile(Controller.VERSION_PREFIX + "(\\d{1,3})\\.(\\d{1,5})\\.(\\d{1,5})");
-
 	private static final long PEER_VERSION_131 = 0x0100030001L;
 
 	private static final int POW_BUFFER_SIZE_PRE_131 = 8 * 1024 * 1024; // bytes

src/main/java/org/qortal/network/message/CachedBlockMessage.java

@@ -0,0 +1,70 @@
+package org.qortal.network.message;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.UnsupportedEncodingException;
+import java.nio.ByteBuffer;
+
+import org.qortal.block.Block;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.block.BlockTransformer;
+
+import com.google.common.primitives.Ints;
+
+// This is an OUTGOING-only Message which more readily lends itself to being cached
+public class CachedBlockMessage extends Message {
+
+	private Block block = null;
+	private byte[] cachedBytes = null;
+
+	public CachedBlockMessage(Block block) {
+		super(MessageType.BLOCK);
+
+		this.block = block;
+	}
+
+	private CachedBlockMessage(byte[] cachedBytes) {
+		super(MessageType.BLOCK);
+
+		this.block = null;
+		this.cachedBytes = cachedBytes;
+	}
+	
+	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) throws UnsupportedEncodingException {
+		throw new UnsupportedOperationException("CachedBlockMessage is for outgoing messages only");
+	}
+
+	@Override
+	protected byte[] toData() {
+		// Already serialized?
+		if (this.cachedBytes != null)
+			return cachedBytes;
+
+		if (this.block == null)
+			return null;
+
+		try {
+			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+			bytes.write(Ints.toByteArray(this.block.getBlockData().getHeight()));
+
+			bytes.write(BlockTransformer.toBytes(this.block));
+
+			this.cachedBytes = bytes.toByteArray();
+			// We no longer need source Block
+			// and Block contains repository handle which is highly likely to be invalid after this call
+			this.block = null;
+
+			return this.cachedBytes;
+		} catch (TransformationException | IOException e) {
+			return null;
+		}
+	}
+
+	public CachedBlockMessage cloneWithNewId(int newId) {
+		CachedBlockMessage clone = new CachedBlockMessage(this.cachedBytes);
+		clone.setId(newId);
+		return clone;
+	}
+
+}

src/main/java/org/qortal/network/message/GetOnlineAccountsMessage.java

@@ -6,6 +6,7 @@ import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.Collectors;
 
 import org.qortal.data.network.OnlineAccountData;
 import org.qortal.transform.Transformer;
@@ -25,7 +26,7 @@ public class GetOnlineAccountsMessage extends Message {
 	private GetOnlineAccountsMessage(int id, List<OnlineAccountData> onlineAccounts) {
 		super(id, MessageType.GET_ONLINE_ACCOUNTS);
 
-		this.onlineAccounts = onlineAccounts;
+		this.onlineAccounts = onlineAccounts.stream().limit(MAX_ACCOUNT_COUNT).collect(Collectors.toList());
 	}
 
 	public List<OnlineAccountData> getOnlineAccounts() {
@@ -35,12 +36,9 @@ public class GetOnlineAccountsMessage extends Message {
 	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
 		final int accountCount = bytes.getInt();
 
-		if (accountCount > MAX_ACCOUNT_COUNT)
-			return null;
-
 		List<OnlineAccountData> onlineAccounts = new ArrayList<>(accountCount);
 
-		for (int i = 0; i < accountCount; ++i) {
+		for (int i = 0; i < Math.min(MAX_ACCOUNT_COUNT, accountCount); ++i) {
 			long timestamp = bytes.getLong();
 
 			byte[] publicKey = new byte[Transformer.PUBLIC_KEY_LENGTH];

src/main/java/org/qortal/network/message/OnlineAccountsMessage.java

@@ -6,6 +6,7 @@ import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.Collectors;
 
 import org.qortal.data.network.OnlineAccountData;
 import org.qortal.transform.Transformer;
@@ -25,7 +26,7 @@ public class OnlineAccountsMessage extends Message {
 	private OnlineAccountsMessage(int id, List<OnlineAccountData> onlineAccounts) {
 		super(id, MessageType.ONLINE_ACCOUNTS);
 
-		this.onlineAccounts = onlineAccounts;
+		this.onlineAccounts = onlineAccounts.stream().limit(MAX_ACCOUNT_COUNT).collect(Collectors.toList());
 	}
 
 	public List<OnlineAccountData> getOnlineAccounts() {
@@ -35,12 +36,9 @@ public class OnlineAccountsMessage extends Message {
 	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
 		final int accountCount = bytes.getInt();
 
-		if (accountCount > MAX_ACCOUNT_COUNT)
-			return null;
-
 		List<OnlineAccountData> onlineAccounts = new ArrayList<>(accountCount);
 
-		for (int i = 0; i < accountCount; ++i) {
+		for (int i = 0; i < Math.min(MAX_ACCOUNT_COUNT, accountCount); ++i) {
 			long timestamp = bytes.getLong();
 
 			byte[] signature = new byte[Transformer.SIGNATURE_LENGTH];

src/main/java/org/qortal/repository/ATRepository.java

@@ -98,12 +98,12 @@ public interface ATRepository {
 	 */
 	public List<ATStateData> getMatchingFinalATStatesQuorum(byte[] codeHash, Boolean isFinished,
 			Integer dataByteOffset, Long expectedValue,
-			int minimumCount, long minimumPeriod) throws DataException;
+			int minimumCount, int maximumCount, long minimumPeriod) throws DataException;
 
 	/**
 	 * Returns all ATStateData for a given block height.
 	 * <p>
-	 * Unlike <tt>getATState</tt>, only returns ATStateData saved at the given height.
+	 * Unlike <tt>getATState</tt>, only returns <i>partial</i> ATStateData saved at the given height.
 	 *
 	 * @param height
 	 *            - block height

src/main/java/org/qortal/repository/Repository.java

@@ -47,8 +47,6 @@ public interface Repository extends AutoCloseable {
 
 	public void backup(boolean quick) throws DataException;
 
-	public void checkpoint(boolean quick) throws DataException;
-
 	public void performPeriodicMaintenance() throws DataException;
 
 	public void exportNodeLocalData() throws DataException;

src/main/java/org/qortal/repository/RepositoryFactory.java

@@ -1,5 +1,7 @@
 package org.qortal.repository;
 
+import java.sql.SQLException;
+
 public interface RepositoryFactory {
 
 	public boolean wasPristineAtOpen();
@@ -12,4 +14,7 @@ public interface RepositoryFactory {
 
 	public void close() throws DataException;
 
+	// Not ideal place for this but implementating class will know the answer without having to open a new DB session
+	public boolean isDeadlockException(SQLException e);
+
 }

src/main/java/org/qortal/repository/RepositoryManager.java

@@ -1,9 +1,14 @@
 package org.qortal.repository;
 
+import java.sql.SQLException;
+
 public abstract class RepositoryManager {
 
 	private static RepositoryFactory repositoryFactory = null;
 
+	/** null if no checkpoint requested, TRUE for quick checkpoint, false for slow/full checkpoint. */
+	private static Boolean quickCheckpointRequested = null;
+
 	public static RepositoryFactory getRepositoryFactory() {
 		return repositoryFactory;
 	}
@@ -46,12 +51,12 @@ public abstract class RepositoryManager {
 		}
 	}
 
-	public static void checkpoint(boolean quick) {
-		try (final Repository repository = getRepository()) {
-			repository.checkpoint(quick);
-		} catch (DataException e) {
-			// Checkpoint is best-effort so don't complain
-		}
+	public static void setRequestedCheckpoint(Boolean quick) {
+		quickCheckpointRequested = quick;
+	}
+
+	public static Boolean getRequestedCheckpoint() {
+		return quickCheckpointRequested;
 	}
 
 	public static void rebuild() throws DataException {
@@ -66,4 +71,10 @@ public abstract class RepositoryManager {
 		repositoryFactory = oldRepositoryFactory.reopen();
 	}
 
+	public static boolean isDeadlockRelated(Throwable e) {
+		Throwable cause = e.getCause();
+
+		return SQLException.class.isInstance(cause) && repositoryFactory.isDeadlockException((SQLException) cause);
+	}
+
 }

src/main/java/org/qortal/repository/TransactionRepository.java

@@ -1,5 +1,6 @@
 package org.qortal.repository;
 
+import java.util.EnumSet;
 import java.util.List;
 import java.util.Map;
 
@@ -251,6 +252,14 @@ public interface TransactionRepository {
 	 */
 	public List<TransactionData> getUnconfirmedTransactions(TransactionType txType, byte[] creatorPublicKey) throws DataException;
 
+	/**
+	 * Returns list of unconfirmed transactions excluding specified type(s).
+	 * 
+	 * @return list of transactions, or empty if none.
+	 * @throws DataException
+	 */
+	public List<TransactionData> getUnconfirmedTransactions(EnumSet<TransactionType> excludedTxTypes) throws DataException;
+
 	/**
 	 * Remove transaction from unconfirmed transactions pile.
 	 * 

src/main/java/org/qortal/repository/hsqldb/HSQLDBATRepository.java

@@ -32,7 +32,7 @@ public class HSQLDBATRepository implements ATRepository {
 	public ATData fromATAddress(String atAddress) throws DataException {
 		String sql = "SELECT creator, created_when, version, asset_id, code_bytes, code_hash, "
 				+ "is_sleeping, sleep_until_height, is_finished, had_fatal_error, "
-				+ "is_frozen, frozen_balance "
+				+ "is_frozen, frozen_balance, sleep_until_message_timestamp "
 				+ "FROM ATs "
 				+ "WHERE AT_address = ? LIMIT 1";
 
@@ -60,8 +60,13 @@ public class HSQLDBATRepository implements ATRepository {
 			if (frozenBalance == 0 && resultSet.wasNull())
 				frozenBalance = null;
 
+			Long sleepUntilMessageTimestamp = resultSet.getLong(13);
+			if (sleepUntilMessageTimestamp == 0 && resultSet.wasNull())
+				sleepUntilMessageTimestamp = null;
+
 			return new ATData(atAddress, creatorPublicKey, created, version, assetId, codeBytes, codeHash,
-					isSleeping, sleepUntilHeight, isFinished, hadFatalError, isFrozen, frozenBalance);
+					isSleeping, sleepUntilHeight, isFinished, hadFatalError, isFrozen, frozenBalance,
+					sleepUntilMessageTimestamp);
 		} catch (SQLException e) {
 			throw new DataException("Unable to fetch AT from repository", e);
 		}
@@ -94,7 +99,7 @@ public class HSQLDBATRepository implements ATRepository {
 	public List<ATData> getAllExecutableATs() throws DataException {
 		String sql = "SELECT AT_address, creator, created_when, version, asset_id, code_bytes, code_hash, "
 				+ "is_sleeping, sleep_until_height, had_fatal_error, "
-				+ "is_frozen, frozen_balance "
+				+ "is_frozen, frozen_balance, sleep_until_message_timestamp "
 				+ "FROM ATs "
 				+ "WHERE is_finished = false "
 				+ "ORDER BY created_when ASC";
@@ -128,8 +133,13 @@ public class HSQLDBATRepository implements ATRepository {
 				if (frozenBalance == 0 && resultSet.wasNull())
 					frozenBalance = null;
 
+				Long sleepUntilMessageTimestamp = resultSet.getLong(13);
+				if (sleepUntilMessageTimestamp == 0 && resultSet.wasNull())
+					sleepUntilMessageTimestamp = null;
+
 				ATData atData = new ATData(atAddress, creatorPublicKey, created, version, assetId, codeBytes, codeHash,
-						isSleeping, sleepUntilHeight, isFinished, hadFatalError, isFrozen, frozenBalance);
+						isSleeping, sleepUntilHeight, isFinished, hadFatalError, isFrozen, frozenBalance,
+						sleepUntilMessageTimestamp);
 
 				executableATs.add(atData);
 			} while (resultSet.next());
@@ -147,7 +157,7 @@ public class HSQLDBATRepository implements ATRepository {
 
 		sql.append("SELECT AT_address, creator, created_when, version, asset_id, code_bytes, ")
 				.append("is_sleeping, sleep_until_height, is_finished, had_fatal_error, ")
-				.append("is_frozen, frozen_balance ")
+				.append("is_frozen, frozen_balance, sleep_until_message_timestamp ")
 				.append("FROM ATs ")
 				.append("WHERE code_hash = ? ");
 		bindParams.add(codeHash);
@@ -191,8 +201,13 @@ public class HSQLDBATRepository implements ATRepository {
 				if (frozenBalance == 0 && resultSet.wasNull())
 					frozenBalance = null;
 
+				Long sleepUntilMessageTimestamp = resultSet.getLong(13);
+				if (sleepUntilMessageTimestamp == 0 && resultSet.wasNull())
+					sleepUntilMessageTimestamp = null;
+
 				ATData atData = new ATData(atAddress, creatorPublicKey, created, version, assetId, codeBytes, codeHash,
-						isSleeping, sleepUntilHeight, isFinished, hadFatalError, isFrozen, frozenBalance);
+						isSleeping, sleepUntilHeight, isFinished, hadFatalError, isFrozen, frozenBalance,
+						sleepUntilMessageTimestamp);
 
 				matchingATs.add(atData);
 			} while (resultSet.next());
@@ -210,7 +225,7 @@ public class HSQLDBATRepository implements ATRepository {
 
 		sql.append("SELECT AT_address, creator, created_when, version, asset_id, code_bytes, ")
 				.append("is_sleeping, sleep_until_height, is_finished, had_fatal_error, ")
-				.append("is_frozen, frozen_balance, code_hash ")
+				.append("is_frozen, frozen_balance, code_hash, sleep_until_message_timestamp ")
 				.append("FROM ");
 
 		// (VALUES (?), (?), ...) AS ATCodeHashes (code_hash)
@@ -264,9 +279,10 @@ public class HSQLDBATRepository implements ATRepository {
 					frozenBalance = null;
 
 				byte[] codeHash = resultSet.getBytes(13);
+				Long sleepUntilMessageTimestamp = resultSet.getLong(14);
 
 				ATData atData = new ATData(atAddress, creatorPublicKey, created, version, assetId, codeBytes, codeHash,
-						isSleeping, sleepUntilHeight, isFinished, hadFatalError, isFrozen, frozenBalance);
+						isSleeping, sleepUntilHeight, isFinished, hadFatalError, isFrozen, frozenBalance, sleepUntilMessageTimestamp);
 
 				matchingATs.add(atData);
 			} while (resultSet.next());
@@ -305,7 +321,7 @@ public class HSQLDBATRepository implements ATRepository {
 				.bind("code_bytes", atData.getCodeBytes()).bind("code_hash", atData.getCodeHash())
 				.bind("is_sleeping", atData.getIsSleeping()).bind("sleep_until_height", atData.getSleepUntilHeight())
 				.bind("is_finished", atData.getIsFinished()).bind("had_fatal_error", atData.getHadFatalError()).bind("is_frozen", atData.getIsFrozen())
-				.bind("frozen_balance", atData.getFrozenBalance());
+				.bind("frozen_balance", atData.getFrozenBalance()).bind("sleep_until_message_timestamp", atData.getSleepUntilMessageTimestamp());
 
 		try {
 			saveHelper.execute(this.repository);
@@ -328,7 +344,7 @@ public class HSQLDBATRepository implements ATRepository {
 
 	@Override
 	public ATStateData getATStateAtHeight(String atAddress, int height) throws DataException {
-		String sql = "SELECT state_data, state_hash, fees, is_initial "
+		String sql = "SELECT state_data, state_hash, fees, is_initial, sleep_until_message_timestamp "
 				+ "FROM ATStates "
 				+ "LEFT OUTER JOIN ATStatesData USING (AT_address, height) "
 				+ "WHERE ATStates.AT_address = ? AND ATStates.height = ? "
@@ -343,7 +359,11 @@ public class HSQLDBATRepository implements ATRepository {
 			long fees = resultSet.getLong(3);
 			boolean isInitial = resultSet.getBoolean(4);
 
-			return new ATStateData(atAddress, height, stateData, stateHash, fees, isInitial);
+			Long sleepUntilMessageTimestamp = resultSet.getLong(5);
+			if (sleepUntilMessageTimestamp == 0 && resultSet.wasNull())
+				sleepUntilMessageTimestamp = null;
+
+			return new ATStateData(atAddress, height, stateData, stateHash, fees, isInitial, sleepUntilMessageTimestamp);
 		} catch (SQLException e) {
 			throw new DataException("Unable to fetch AT state from repository", e);
 		}
@@ -351,7 +371,7 @@ public class HSQLDBATRepository implements ATRepository {
 
 	@Override
 	public ATStateData getLatestATState(String atAddress) throws DataException {
-		String sql = "SELECT height, state_data, state_hash, fees, is_initial "
+		String sql = "SELECT height, state_data, state_hash, fees, is_initial, sleep_until_message_timestamp "
 				+ "FROM ATStates "
 				+ "JOIN ATStatesData USING (AT_address, height) "
 				+ "WHERE ATStates.AT_address = ? "
@@ -370,7 +390,11 @@ public class HSQLDBATRepository implements ATRepository {
 			long fees = resultSet.getLong(4);
 			boolean isInitial = resultSet.getBoolean(5);
 
-			return new ATStateData(atAddress, height, stateData, stateHash, fees, isInitial);
+			Long sleepUntilMessageTimestamp = resultSet.getLong(6);
+			if (sleepUntilMessageTimestamp == 0 && resultSet.wasNull())
+				sleepUntilMessageTimestamp = null;
+
+			return new ATStateData(atAddress, height, stateData, stateHash, fees, isInitial, sleepUntilMessageTimestamp);
 		} catch (SQLException e) {
 			throw new DataException("Unable to fetch latest AT state from repository", e);
 		}
@@ -383,10 +407,10 @@ public class HSQLDBATRepository implements ATRepository {
 		StringBuilder sql = new StringBuilder(1024);
 		List<Object> bindParams = new ArrayList<>();
 
-		sql.append("SELECT AT_address, height, state_data, state_hash, fees, is_initial "
+		sql.append("SELECT AT_address, height, state_data, state_hash, fees, is_initial, FinalATStates.sleep_until_message_timestamp "
 				+ "FROM ATs "
 				+ "CROSS JOIN LATERAL("
-					+ "SELECT height, state_data, state_hash, fees, is_initial "
+					+ "SELECT height, state_data, state_hash, fees, is_initial, sleep_until_message_timestamp "
 					+ "FROM ATStates "
 					+ "JOIN ATStatesData USING (AT_address, height) "
 					+ "WHERE ATStates.AT_address = ATs.AT_address ");
@@ -440,7 +464,11 @@ public class HSQLDBATRepository implements ATRepository {
 				long fees = resultSet.getLong(5);
 				boolean isInitial = resultSet.getBoolean(6);
 
-				ATStateData atStateData = new ATStateData(atAddress, height, stateData, stateHash, fees, isInitial);
+				Long sleepUntilMessageTimestamp = resultSet.getLong(7);
+				if (sleepUntilMessageTimestamp == 0 && resultSet.wasNull())
+					sleepUntilMessageTimestamp = null;
+
+				ATStateData atStateData = new ATStateData(atAddress, height, stateData, stateHash, fees, isInitial, sleepUntilMessageTimestamp);
 
 				atStates.add(atStateData);
 			} while (resultSet.next());
@@ -454,7 +482,7 @@ public class HSQLDBATRepository implements ATRepository {
 	@Override
 	public List<ATStateData> getMatchingFinalATStatesQuorum(byte[] codeHash, Boolean isFinished,
 			Integer dataByteOffset, Long expectedValue,
-			int minimumCount, long minimumPeriod) throws DataException {
+			int minimumCount, int maximumCount, long minimumPeriod) throws DataException {
 		// We need most recent entry first so we can use its timestamp to slice further results
 		List<ATStateData> mostRecentStates = this.getMatchingFinalATStates(codeHash, isFinished,
 				dataByteOffset, expectedValue, null,
@@ -471,7 +499,7 @@ public class HSQLDBATRepository implements ATRepository {
 		StringBuilder sql = new StringBuilder(1024);
 		List<Object> bindParams = new ArrayList<>();
 
-		sql.append("SELECT AT_address, height, state_data, state_hash, fees, is_initial "
+		sql.append("SELECT AT_address, height, state_data, state_hash, fees, is_initial, sleep_until_message_timestamp "
 				+ "FROM ATs "
 				+ "CROSS JOIN LATERAL("
 					+ "SELECT height, state_data, state_hash, fees, is_initial "
@@ -510,7 +538,8 @@ public class HSQLDBATRepository implements ATRepository {
 		bindParams.add(minimumHeight);
 		bindParams.add(minimumCount);
 
-		sql.append("ORDER BY FinalATStates.height DESC");
+		sql.append("ORDER BY FinalATStates.height DESC LIMIT ?");
+		bindParams.add(maximumCount);
 
 		List<ATStateData> atStates = new ArrayList<>();
 
@@ -525,8 +554,10 @@ public class HSQLDBATRepository implements ATRepository {
 				byte[] stateHash = resultSet.getBytes(4);
 				long fees = resultSet.getLong(5);
 				boolean isInitial = resultSet.getBoolean(6);
+				Long sleepUntilMessageTimestamp = resultSet.getLong(7);
 
-				ATStateData atStateData = new ATStateData(atAddress, height, stateData, stateHash, fees, isInitial);
+				ATStateData atStateData = new ATStateData(atAddress, height, stateData, stateHash, fees, isInitial,
+						sleepUntilMessageTimestamp);
 
 				atStates.add(atStateData);
 			} while (resultSet.next());
@@ -541,9 +572,9 @@ public class HSQLDBATRepository implements ATRepository {
 	public List<ATStateData> getBlockATStatesAtHeight(int height) throws DataException {
 		String sql = "SELECT AT_address, state_hash, fees, is_initial "
 				+ "FROM ATs "
-				+ "LEFT OUTER JOIN ATStates "
-				+ "ON ATStates.AT_address = ATs.AT_address AND height = ? "
-				+ "WHERE ATStates.AT_address IS NOT NULL "
+				+ "JOIN ATStates "
+				+ "ON ATStates.AT_address = ATs.AT_address "
+				+ "WHERE height = ? "
 				+ "ORDER BY created_when ASC";
 
 		List<ATStateData> atStates = new ArrayList<>();
@@ -661,7 +692,8 @@ public class HSQLDBATRepository implements ATRepository {
 
 		atStatesSaver.bind("AT_address", atStateData.getATAddress()).bind("height", atStateData.getHeight())
 				.bind("state_hash", atStateData.getStateHash())
-				.bind("fees", atStateData.getFees()).bind("is_initial", atStateData.isInitial());
+				.bind("fees", atStateData.getFees()).bind("is_initial", atStateData.isInitial())
+				.bind("sleep_until_message_timestamp", atStateData.getSleepUntilMessageTimestamp());
 
 		try {
 			atStatesSaver.execute(this.repository);

src/main/java/org/qortal/repository/hsqldb/HSQLDBDatabaseUpdates.java

@@ -699,7 +699,7 @@ public class HSQLDBDatabaseUpdates {
 					stmt.execute("CHECKPOINT");
 					break;
 
-				case 30:
+				case 30: {
 					// Split AT state data off to new table for better performance/management.
 
 					if (!wasPristine && !"mem".equals(HSQLDBRepository.getDbPathname(connection.getMetaData().getURL()))) {
@@ -774,6 +774,7 @@ public class HSQLDBDatabaseUpdates {
 					stmt.execute("ALTER TABLE ATStatesNew RENAME TO ATStates");
 					stmt.execute("CHECKPOINT");
 					break;
+				}
 
 				case 31:
 					// Fix latest AT state cache which was previous created as TEMPORARY
@@ -822,6 +823,41 @@ public class HSQLDBDatabaseUpdates {
 							+ "timestamp_signature Signature NOT NULL, " + TRANSACTION_KEYS + ")");
 					break;
 
+				case 34: {
+					// AT sleep-until-message support
+					LOGGER.info("Altering AT table in repository - this might take a while... (approx. 20 seconds on high-spec)");
+					stmt.execute("ALTER TABLE ATs ADD sleep_until_message_timestamp BIGINT");
+
+					// Create new AT-states table with new column
+					stmt.execute("CREATE TABLE ATStatesNew ("
+							+ "AT_address QortalAddress, height INTEGER NOT NULL, state_hash ATStateHash NOT NULL, "
+							+ "fees QortalAmount NOT NULL, is_initial BOOLEAN NOT NULL, sleep_until_message_timestamp BIGINT, "
+							+ "PRIMARY KEY (AT_address, height), "
+							+ "FOREIGN KEY (AT_address) REFERENCES ATs (AT_address) ON DELETE CASCADE)");
+					stmt.execute("SET TABLE ATStatesNew NEW SPACE");
+					stmt.execute("CHECKPOINT");
+
+					ResultSet resultSet = stmt.executeQuery("SELECT height FROM Blocks ORDER BY height DESC LIMIT 1");
+					final int blockchainHeight = resultSet.next() ? resultSet.getInt(1) : 0;
+					final int heightStep = 100;
+
+					LOGGER.info("Altering AT states table in repository - this might take a while... (approx. 3 mins on high-spec)");
+					for (int minHeight = 1; minHeight < blockchainHeight; minHeight += heightStep) {
+						stmt.execute("INSERT INTO ATStatesNew ("
+								+ "SELECT AT_address, height, state_hash, fees, is_initial, NULL "
+								+ "FROM ATStates "
+								+ "WHERE height BETWEEN " + minHeight + " AND " + (minHeight + heightStep - 1)
+								+ ")");
+						stmt.execute("COMMIT");
+					}
+					stmt.execute("CHECKPOINT");
+
+					stmt.execute("DROP TABLE ATStates");
+					stmt.execute("ALTER TABLE ATStatesNew RENAME TO ATStates");
+					stmt.execute("CHECKPOINT");
+					break;
+				}
+
 				default:
 					// nothing to do
 					return false;

src/main/java/org/qortal/repository/hsqldb/HSQLDBRepository.java

@@ -1,6 +1,8 @@
 package org.qortal.repository.hsqldb;
 
+import java.awt.TrayIcon.MessageType;
 import java.io.File;
+import java.io.FileWriter;
 import java.io.IOException;
 import java.math.BigDecimal;
 import java.nio.file.Files;
@@ -14,23 +16,21 @@ import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Savepoint;
 import java.sql.Statement;
-import java.util.ArrayDeque;
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.Comparator;
-import java.util.Deque;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.stream.Stream;
 
+import org.json.JSONArray;
+import org.json.JSONObject;
+
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.account.PrivateKeyAccount;
 import org.qortal.crypto.Crypto;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.globalization.Translator;
+import org.qortal.gui.SysTray;
 import org.qortal.repository.ATRepository;
 import org.qortal.repository.AccountRepository;
 import org.qortal.repository.ArbitraryRepository;
@@ -49,11 +49,17 @@ import org.qortal.repository.TransactionRepository;
 import org.qortal.repository.VotingRepository;
 import org.qortal.repository.hsqldb.transaction.HSQLDBTransactionRepository;
 import org.qortal.settings.Settings;
+import org.qortal.utils.Base58;
 
 public class HSQLDBRepository implements Repository {
 
 	private static final Logger LOGGER = LogManager.getLogger(HSQLDBRepository.class);
 
+	public static final Object CHECKPOINT_LOCK = new Object();
+
+	// "serialization failure"
+	private static final Integer DEADLOCK_ERROR_CODE = Integer.valueOf(-4861);
+
 	protected Connection connection;
 	protected final Deque<Savepoint> savepoints = new ArrayDeque<>(3);
 	protected boolean debugState = false;
@@ -103,7 +109,10 @@ public class HSQLDBRepository implements Repository {
 			throw new DataException("Unable to fetch session ID from repository", e);
 		}
 
-		assertEmptyTransaction("connection creation");
+		// synchronize to block new connections if checkpointing in progress 
+		synchronized (CHECKPOINT_LOCK) {
+			assertEmptyTransaction("connection creation");
+		}
 	}
 
 	// Getters / setters
@@ -276,7 +285,7 @@ public class HSQLDBRepository implements Repository {
 			return;
 		}
 
-		try (Statement stmt = this.connection.createStatement()) {
+		try {
 			assertEmptyTransaction("connection close");
 
 			// Assume we are not going to be GC'd for a while
@@ -284,6 +293,9 @@ public class HSQLDBRepository implements Repository {
 			this.sqlStatements = null;
 			this.savepoints.clear();
 
+			// If a checkpoint has been requested, we could perform that now
+			this.maybeCheckpoint();
+
 			// Give connection back to the pool
 			this.connection.close();
 			this.connection = null;
@@ -292,6 +304,58 @@ public class HSQLDBRepository implements Repository {
 		}
 	}
 
+	private void maybeCheckpoint() throws DataException {
+		// To serialize checkpointing and to block new sessions when checkpointing in progress
+		synchronized (CHECKPOINT_LOCK) {
+			Boolean quickCheckpointRequest = RepositoryManager.getRequestedCheckpoint();
+			if (quickCheckpointRequest == null)
+				return;
+
+			// We can only perform a CHECKPOINT if no other HSQLDB session is mid-transaction,
+			// otherwise the CHECKPOINT blocks for COMMITs and other threads can't open HSQLDB sessions
+			// due to HSQLDB blocking until CHECKPOINT finishes - i.e. deadlock
+			String sql = "SELECT COUNT(*) "
+					+ "FROM Information_schema.system_sessions "
+					+ "WHERE transaction = TRUE";
+
+			try {
+				PreparedStatement pstmt = this.cachePreparedStatement(sql);
+
+				if (!pstmt.execute())
+					throw new DataException("Unable to check repository session status");
+
+				try (ResultSet resultSet = pstmt.getResultSet()) {
+					if (resultSet == null || !resultSet.next())
+						// Failed to even find HSQLDB session info!
+						throw new DataException("No results when checking repository session status");
+
+					int transactionCount = resultSet.getInt(1);
+
+					if (transactionCount > 0)
+						// We can't safely perform CHECKPOINT due to ongoing SQL transactions
+						return;
+				}
+
+				LOGGER.info("Performing repository CHECKPOINT...");
+
+				if (Settings.getInstance().getShowCheckpointNotification())
+					SysTray.getInstance().showMessage(Translator.INSTANCE.translate("SysTray", "DB_CHECKPOINT"),
+							Translator.INSTANCE.translate("SysTray", "PERFORMING_DB_CHECKPOINT"),
+							MessageType.INFO);
+
+				try (Statement stmt = this.connection.createStatement()) {
+					stmt.execute(Boolean.TRUE.equals(quickCheckpointRequest) ? "CHECKPOINT" : "CHECKPOINT DEFRAG");
+				}
+
+				// Completed!
+				LOGGER.info("Repository CHECKPOINT completed!");
+				RepositoryManager.setRequestedCheckpoint(null);
+			} catch (SQLException e) {
+				throw new DataException("Unable to check repository session status", e);
+			}
+		}
+	}
+
 	@Override
 	public void rebuild() throws DataException {
 		LOGGER.info("Rebuilding repository from scratch");
@@ -379,15 +443,6 @@ public class HSQLDBRepository implements Repository {
 		}
 	}
 
-	@Override
-	public void checkpoint(boolean quick) throws DataException {
-		try (Statement stmt = this.connection.createStatement()) {
-			stmt.execute(quick ? "CHECKPOINT" : "CHECKPOINT DEFRAG");
-		} catch (SQLException e) {
-			throw new DataException("Unable to perform repository checkpoint");
-		}
-	}
-
 	@Override
 	public void performPeriodicMaintenance() throws DataException {
 		// Defrag DB - takes a while!
@@ -403,28 +458,68 @@ public class HSQLDBRepository implements Repository {
 
 	@Override
 	public void exportNodeLocalData() throws DataException {
-		try (Statement stmt = this.connection.createStatement()) {
-			stmt.execute("PERFORM EXPORT SCRIPT FOR TABLE MintingAccounts DATA TO 'MintingAccounts.script'");
-			stmt.execute("PERFORM EXPORT SCRIPT FOR TABLE TradeBotStates DATA TO 'TradeBotStates.script'");
-			LOGGER.info("Exported sensitive/node-local data: minting keys and trade bot states");
-		} catch (SQLException e) {
-			throw new DataException("Unable to export sensitive/node-local data from repository");
+		// Create the qortal-backup folder if it doesn't exist
+		Path backupPath = Paths.get("qortal-backup");
+		try {
+			Files.createDirectories(backupPath);
+		} catch (IOException e) {
+			LOGGER.info("Unable to create backup folder");
+			throw new DataException("Unable to create backup folder");
+		}
+
+		try {
+			// Load trade bot data
+			List<TradeBotData> allTradeBotData = this.getCrossChainRepository().getAllTradeBotData();
+			JSONArray allTradeBotDataJson = new JSONArray();
+			for (TradeBotData tradeBotData : allTradeBotData) {
+				JSONObject tradeBotDataJson = tradeBotData.toJson();
+				allTradeBotDataJson.put(tradeBotDataJson);
+			}
+
+			// We need to combine existing TradeBotStates data before overwriting
+			String fileName = "qortal-backup/TradeBotStates.json";
+			File tradeBotStatesBackupFile = new File(fileName);
+			if (tradeBotStatesBackupFile.exists()) {
+				String jsonString = new String(Files.readAllBytes(Paths.get(fileName)));
+				JSONArray allExistingTradeBotData = new JSONArray(jsonString);
+				Iterator<Object> iterator = allExistingTradeBotData.iterator();
+				while(iterator.hasNext()) {
+					JSONObject existingTradeBotData = (JSONObject)iterator.next();
+					String existingTradePrivateKey = (String) existingTradeBotData.get("tradePrivateKey");
+						// Check if we already have an entry for this trade
+						boolean found = allTradeBotData.stream().anyMatch(tradeBotData -> Base58.encode(tradeBotData.getTradePrivateKey()).equals(existingTradePrivateKey));
+						if (found == false)
+							// We need to add this to our list
+							allTradeBotDataJson.put(existingTradeBotData);
+				}
+			}
+
+			FileWriter writer = new FileWriter(fileName);
+			writer.write(allTradeBotDataJson.toString());
+			writer.close();
+			LOGGER.info("Exported sensitive/node-local data: trade bot states");
+
+		} catch (DataException | IOException e) {
+			throw new DataException("Unable to export trade bot states from repository");
 		}
 	}
 
 	@Override
 	public void importDataFromFile(String filename) throws DataException {
-		try (Statement stmt = this.connection.createStatement()) {
-			LOGGER.info(() -> String.format("Importing data into repository from %s", filename));
-
-			String escapedFilename = stmt.enquoteLiteral(filename);
-			stmt.execute("PERFORM IMPORT SCRIPT DATA FROM " + escapedFilename + " STOP ON ERROR");
-
-			LOGGER.info(() -> String.format("Imported data into repository from %s", filename));
-		} catch (SQLException e) {
-			LOGGER.info(() -> String.format("Failed to import data into repository from %s: %s", filename, e.getMessage()));
-			throw new DataException("Unable to export sensitive/node-local data from repository: " + e.getMessage());
+		LOGGER.info(() -> String.format("Importing data into repository from %s", filename));
+		try {
+			String jsonString = new String(Files.readAllBytes(Paths.get(filename)));
+			JSONArray tradeBotDataToImport = new JSONArray(jsonString);
+			Iterator<Object> iterator = tradeBotDataToImport.iterator();
+			while(iterator.hasNext()) {
+				JSONObject tradeBotDataJson = (JSONObject)iterator.next();
+				TradeBotData tradeBotData = TradeBotData.fromJson(tradeBotDataJson);
+				this.getCrossChainRepository().save(tradeBotData);
+			}
+		} catch (IOException e) {
+			throw new DataException("Unable to import sensitive/node-local trade bot states to repository: " + e.getMessage());
 		}
+		LOGGER.info(() -> String.format("Imported trade bot states into repository from %s", filename));
 	}
 
 	@Override
@@ -608,8 +703,11 @@ public class HSQLDBRepository implements Repository {
 	private ResultSet checkedExecuteResultSet(PreparedStatement preparedStatement, Object... objects) throws SQLException {
 		bindStatementParams(preparedStatement, objects);
 
-		if (!preparedStatement.execute())
-			throw new SQLException("Fetching from database produced no results");
+		// synchronize to block new executions if checkpointing in progress
+		synchronized (CHECKPOINT_LOCK) {
+			if (!preparedStatement.execute())
+				throw new SQLException("Fetching from database produced no results");
+		}
 
 		ResultSet resultSet = preparedStatement.getResultSet();
 		if (resultSet == null)
@@ -624,7 +722,7 @@ public class HSQLDBRepository implements Repository {
 	/**
 	 * Execute PreparedStatement and return changed row count.
 	 * 
-	 * @param preparedStatement
+	 * @param sql
 	 * @param objects
 	 * @return number of changed rows
 	 * @throws SQLException
@@ -636,8 +734,8 @@ public class HSQLDBRepository implements Repository {
 	/**
 	 * Execute batched PreparedStatement
 	 * 
-	 * @param preparedStatement
-	 * @param objects
+	 * @param sql
+	 * @param batchedObjects
 	 * @return number of changed rows
 	 * @throws SQLException
 	 */
@@ -654,7 +752,16 @@ public class HSQLDBRepository implements Repository {
 
 		long beforeQuery = this.slowQueryThreshold == null ? 0 : System.currentTimeMillis();
 
-		int[] updateCounts = preparedStatement.executeBatch();
+		int[] updateCounts = null;
+		try {
+			updateCounts = preparedStatement.executeBatch();
+		} catch (SQLException e) {
+			if (isDeadlockException(e))
+				// We want more info on what other DB sessions are doing to cause this
+				examineException(e);
+
+			throw e;
+		}
 
 		if (this.slowQueryThreshold != null) {
 			long queryTime = System.currentTimeMillis() - beforeQuery;
@@ -752,7 +859,7 @@ public class HSQLDBRepository implements Repository {
 	 * 
 	 * @param tableName
 	 * @param whereClause
-	 * @param objects
+	 * @param batchedObjects
 	 * @throws SQLException
 	 */
 	public int deleteBatch(String tableName, String whereClause, List<Object[]> batchedObjects) throws SQLException {
@@ -865,6 +972,8 @@ public class HSQLDBRepository implements Repository {
 
 	/** Logs other HSQLDB sessions then returns passed exception */
 	public SQLException examineException(SQLException e) {
+		// TODO: could log at DEBUG for deadlocks by checking RepositoryManager.isDeadlockRelated(e)?
+
 		LOGGER.error(() -> String.format("[Session %d] HSQLDB error: %s", this.sessionId, e.getMessage()), e);
 
 		logStatements();
@@ -946,4 +1055,8 @@ public class HSQLDBRepository implements Repository {
 		return Crypto.toAddress(publicKey);
 	}
 
-}
+	/*package*/ static boolean isDeadlockException(SQLException e) {
+		return DEADLOCK_ERROR_CODE.equals(e.getErrorCode());
+	}
+
+}

src/main/java/org/qortal/repository/hsqldb/HSQLDBRepositoryFactory.java

@@ -14,11 +14,11 @@ import org.hsqldb.jdbc.HSQLDBPool;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryFactory;
+import org.qortal.settings.Settings;
 
 public class HSQLDBRepositoryFactory implements RepositoryFactory {
 
 	private static final Logger LOGGER = LogManager.getLogger(HSQLDBRepositoryFactory.class);
-	private static final int POOL_SIZE = 100;
 
 	/** Log getConnection() calls that take longer than this. (ms) */
 	private static final long SLOW_CONNECTION_THRESHOLD = 1000L;
@@ -57,7 +57,7 @@ public class HSQLDBRepositoryFactory implements RepositoryFactory {
 			HSQLDBRepository.attemptRecovery(connectionUrl);
 		}
 
-		this.connectionPool = new HSQLDBPool(POOL_SIZE);
+		this.connectionPool = new HSQLDBPool(Settings.getInstance().getRepositoryConnectionPoolSize());
 		this.connectionPool.setUrl(this.connectionUrl);
 
 		Properties properties = new Properties();
@@ -94,7 +94,11 @@ public class HSQLDBRepositoryFactory implements RepositoryFactory {
 	@Override
 	public Repository tryRepository() throws DataException {
 		try {
-			return new HSQLDBRepository(this.tryConnection());
+			Connection connection = this.tryConnection();
+			if (connection == null)
+				return null;
+
+			return new HSQLDBRepository(connection);
 		} catch (SQLException e) {
 			throw new DataException("Repository instantiation error", e);
 		}
@@ -144,4 +148,9 @@ public class HSQLDBRepositoryFactory implements RepositoryFactory {
 		}
 	}
 
+	@Override
+	public boolean isDeadlockException(SQLException e) {
+		return HSQLDBRepository.isDeadlockException(e);
+	}
+
 }

src/main/java/org/qortal/repository/hsqldb/HSQLDBSaver.java

@@ -61,13 +61,15 @@ public class HSQLDBSaver {
 	public boolean execute(HSQLDBRepository repository) throws SQLException {
 		String sql = this.formatInsertWithPlaceholders();
 
-		try {
-			PreparedStatement preparedStatement = repository.prepareStatement(sql);
-			this.bindValues(preparedStatement);
+		synchronized (HSQLDBRepository.CHECKPOINT_LOCK) {
+			try {
+				PreparedStatement preparedStatement = repository.prepareStatement(sql);
+				this.bindValues(preparedStatement);
 
-			return preparedStatement.execute();
-		} catch (SQLException e) {
-			throw repository.examineException(e);
+				return preparedStatement.execute();
+			} catch (SQLException e) {
+				throw repository.examineException(e);
+			}
 		}
 	}
 

src/main/java/org/qortal/repository/hsqldb/transaction/HSQLDBTransactionRepository.java

@@ -9,6 +9,7 @@ import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.EnumMap;
+import java.util.EnumSet;
 import java.util.List;
 import java.util.Map;
 
@@ -1181,6 +1182,51 @@ public class HSQLDBTransactionRepository implements TransactionRepository {
 		}
 	}
 
+	@Override
+	public List<TransactionData> getUnconfirmedTransactions(EnumSet<TransactionType> excludedTxTypes) throws DataException {
+		StringBuilder sql = new StringBuilder(1024);
+		sql.append("SELECT signature FROM UnconfirmedTransactions ");
+		sql.append("JOIN Transactions USING (signature) ");
+		sql.append("WHERE type NOT IN (");
+
+		boolean firstTxType = true;
+		for (TransactionType txType : excludedTxTypes) {
+			if (firstTxType)
+				firstTxType = false;
+			else
+				sql.append(", ");
+
+			sql.append(txType.value);
+		}
+
+		sql.append(")");
+		sql.append("ORDER BY created_when, signature");
+
+		List<TransactionData> transactions = new ArrayList<>();
+
+		// Find transactions with no corresponding row in BlockTransactions
+		try (ResultSet resultSet = this.repository.checkedExecute(sql.toString())) {
+			if (resultSet == null)
+				return transactions;
+
+			do {
+				byte[] signature = resultSet.getBytes(1);
+
+				TransactionData transactionData = this.fromSignature(signature);
+
+				if (transactionData == null)
+					// Something inconsistent with the repository
+					throw new DataException(String.format("Unable to fetch unconfirmed transaction %s from repository?", Base58.encode(signature)));
+
+				transactions.add(transactionData);
+			} while (resultSet.next());
+
+			return transactions;
+		} catch (SQLException | DataException e) {
+			throw new DataException("Unable to fetch unconfirmed transactions from repository", e);
+		}
+	}
+
 	@Override
 	public void confirmTransaction(byte[] signature) throws DataException {
 		try {

src/main/java/org/qortal/settings/Settings.java

@@ -23,6 +23,7 @@ import org.eclipse.persistence.jaxb.UnmarshallerProperties;
 import org.qortal.block.BlockChain;
 import org.qortal.crosschain.Bitcoin.BitcoinNet;
 import org.qortal.crosschain.Litecoin.LitecoinNet;
+import org.qortal.crosschain.Dogecoin.DogecoinNet;
 
 // All properties to be converted to JSON via JAXB
 @XmlAccessorType(XmlAccessType.FIELD)
@@ -52,7 +53,7 @@ public class Settings {
 	// UI servers
 	private int uiPort = 12388;
 	private String[] uiLocalServers = new String[] {
-		"localhost", "127.0.0.1", "172.24.1.1", "qor.tal"
+		"localhost", "127.0.0.1"
 	};
 	private String[] uiRemoteServers = new String[] {
 		"node1.qortal.org", "node2.qortal.org", "node3.qortal.org", "node4.qortal.org", "node5.qortal.org",
@@ -89,6 +90,8 @@ public class Settings {
 	private long repositoryCheckpointInterval = 60 * 60 * 1000L; // 1 hour (ms) default
 	/** Whether to show a notification when we perform repository 'checkpoint'. */
 	private boolean showCheckpointNotification = false;
+	/* How many blocks to cache locally. Defaulted to 10, which covers a typical Synchronizer request + a few spare */
+	private int blockCacheSize = 10;
 
 	/** How long to keep old, full, AT state data (ms). */
 	private long atStatesMaxLifetime = 2 * 7 * 24 * 60 * 60 * 1000L; // milliseconds
@@ -120,11 +123,26 @@ public class Settings {
 	private int maxNetworkThreadPoolSize = 20;
 	/** Maximum number of threads for network proof-of-work compute, used during handshaking. */
 	private int networkPoWComputePoolSize = 2;
+	/** Maximum number of retry attempts if a peer fails to respond with the requested data */
+	private int maxRetries = 2;
+
+	/** Minimum peer version number required in order to sync with them */
+	private String minPeerVersion = "1.5.0";
+	/** Whether to allow connections with peers below minPeerVersion
+	 * If true, we won't sync with them but they can still sync with us, and will show in the peers list
+	 * If false, sync will be blocked both ways, and they will not appear in the peers list */
+	private boolean allowConnectionsWithOlderPeerVersions = true;
+
+	/** Minimum time (in seconds) that we should attempt to remain connected to a peer for */
+	private int minPeerConnectionTime = 2 * 60; // seconds
+	/** Maximum time (in seconds) that we should attempt to remain connected to a peer for */
+	private int maxPeerConnectionTime = 20 * 60; // seconds
 
 	// Which blockchains this node is running
 	private String blockchainConfig = null; // use default from resources
 	private BitcoinNet bitcoinNet = BitcoinNet.MAIN;
 	private LitecoinNet litecoinNet = LitecoinNet.MAIN;
+	private DogecoinNet dogecoinNet = DogecoinNet.MAIN;
 	// Also crosschain-related:
 	/** Whether to show SysTray pop-up notifications when trade-bot entries change state */
 	private boolean tradebotSystrayEnabled = false;
@@ -134,6 +152,8 @@ public class Settings {
 	private Long slowQueryThreshold = null;
 	/** Repository storage path. */
 	private String repositoryPath = "db";
+	/** Repository connection pool size. Needs to be a bit bigger than maxNetworkThreadPoolSize */
+	private int repositoryConnectionPoolSize = 100;
 
 	// Auto-update sources
 	private String[] autoUpdateRepos = new String[] {
@@ -141,6 +161,9 @@ public class Settings {
 		"https://raw.githubusercontent.com@151.101.16.133/Qortal/qortal/%s/qortal.update"
 	};
 
+	// Lists
+	private String listsPath = "lists";
+
 	/** Array of NTP server hostnames. */
 	private String[] ntpServers = new String[] {
 		"pool.ntp.org",
@@ -361,6 +384,10 @@ public class Settings {
 		return this.maxTransactionTimestampFuture;
 	}
 
+	public int getBlockCacheSize() {
+		return this.blockCacheSize;
+	}
+
 	public boolean isTestNet() {
 		return this.isTestNet;
 	}
@@ -400,6 +427,16 @@ public class Settings {
 		return this.networkPoWComputePoolSize;
 	}
 
+	public int getMaxRetries() { return this.maxRetries; }
+
+	public String getMinPeerVersion() { return this.minPeerVersion; }
+
+	public boolean getAllowConnectionsWithOlderPeerVersions() { return this.allowConnectionsWithOlderPeerVersions; }
+
+	public int getMinPeerConnectionTime() { return this.minPeerConnectionTime; }
+
+	public int getMaxPeerConnectionTime() { return this.maxPeerConnectionTime; }
+
 	public String getBlockchainConfig() {
 		return this.blockchainConfig;
 	}
@@ -412,6 +449,10 @@ public class Settings {
 		return this.litecoinNet;
 	}
 
+	public DogecoinNet getDogecoinNet() {
+		return this.dogecoinNet;
+	}
+
 	public boolean isTradebotSystrayEnabled() {
 		return this.tradebotSystrayEnabled;
 	}
@@ -424,6 +465,10 @@ public class Settings {
 		return this.repositoryPath;
 	}
 
+	public int getRepositoryConnectionPoolSize() {
+		return this.repositoryConnectionPoolSize;
+	}
+
 	public boolean isAutoUpdateEnabled() {
 		return this.autoUpdateEnabled;
 	}
@@ -432,6 +477,10 @@ public class Settings {
 		return this.autoUpdateRepos;
 	}
 
+	public String getListsPath() {
+		return this.listsPath;
+	}
+
 	public String[] getNtpServers() {
 		return this.ntpServers;
 	}

src/main/java/org/qortal/transaction/ChatTransaction.java

@@ -11,6 +11,7 @@ import org.qortal.crypto.MemoryPoW;
 import org.qortal.data.transaction.ChatTransactionData;
 import org.qortal.data.transaction.TransactionData;
 import org.qortal.group.Group;
+import org.qortal.list.ResourceListManager;
 import org.qortal.repository.DataException;
 import org.qortal.repository.GroupRepository;
 import org.qortal.repository.Repository;
@@ -138,6 +139,12 @@ public class ChatTransaction extends Transaction {
 	public ValidationResult isValid() throws DataException {
 		// Nonce checking is done via isSignatureValid() as that method is only called once per import
 
+		// Check for blacklisted author by address
+		ResourceListManager listManager = ResourceListManager.getInstance();
+		if (listManager.isAddressInBlacklist(this.chatTransactionData.getSender())) {
+			return ValidationResult.ADDRESS_IN_BLACKLIST;
+		}
+
 		// If we exist in the repository then we've been imported as unconfirmed,
 		// but we don't want to make it into a block, so return fake non-OK result.
 		if (this.repository.getTransactionRepository().exists(this.chatTransactionData.getSignature()))

src/main/java/org/qortal/transaction/PresenceTransaction.java

@@ -234,10 +234,11 @@ public class PresenceTransaction extends Transaction {
 		if (creatorsPresenceTransactions.isEmpty())
 			return;
 
-		// List should contain oldest transaction first, so remove all but last from repository.
-		creatorsPresenceTransactions.remove(creatorsPresenceTransactions.size() - 1);
 		for (TransactionData transactionData : creatorsPresenceTransactions) {
-			LOGGER.info(() -> String.format("Deleting older PRESENCE transaction %s", Base58.encode(transactionData.getSignature())));
+			if (transactionData.getTimestamp() >= this.transactionData.getTimestamp())
+				continue;
+
+			LOGGER.debug(() -> String.format("Deleting older PRESENCE transaction %s", Base58.encode(transactionData.getSignature())));
 			this.repository.getTransactionRepository().delete(transactionData);
 		}
 	}

src/main/java/org/qortal/transaction/Transaction.java

@@ -4,6 +4,7 @@ import java.math.BigInteger;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Comparator;
+import java.util.EnumSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
@@ -246,6 +247,7 @@ public abstract class Transaction {
 		INVALID_GROUP_BLOCK_DELAY(93),
 		INCORRECT_NONCE(94),
 		INVALID_TIMESTAMP_SIGNATURE(95),
+		ADDRESS_IN_BLACKLIST(96),
 		INVALID_BUT_OK(999),
 		NOT_YET_RELEASED(1000);
 
@@ -605,7 +607,8 @@ public abstract class Transaction {
 	public static List<TransactionData> getUnconfirmedTransactions(Repository repository) throws DataException {
 		BlockData latestBlockData = repository.getBlockRepository().getLastBlock();
 
-		List<TransactionData> unconfirmedTransactions = repository.getTransactionRepository().getUnconfirmedTransactions();
+		EnumSet<TransactionType> excludedTxTypes = EnumSet.of(TransactionType.CHAT, TransactionType.PRESENCE);
+		List<TransactionData> unconfirmedTransactions = repository.getTransactionRepository().getUnconfirmedTransactions(excludedTxTypes);
 
 		unconfirmedTransactions.sort(getDataComparator());
 
@@ -814,6 +817,23 @@ public abstract class Transaction {
 
 			return ValidationResult.OK;
 		} finally {
+			/*
+			 * We call discardChanges() to restart repository 'transaction', discarding any
+			 * transactional table locks, hence reducing possibility of deadlock or
+			 * "serialization failure" with HSQLDB due to reads.
+			 * 
+			 * "Serialization failure" most likely caused by existing transaction check above,
+			 * where multiple threads are importing transactions
+			 * and one thread finds existing an transaction, returns (unlocking blockchain lock),
+			 * then another thread immediately obtains lock, tries to delete above existing transaction
+			 * (e.g. older PRESENCE transaction) but can't because first thread's repository
+			 * session still has row-lock on existing transaction and hasn't yet closed
+			 * repository session. Deadlock caused by race condition.
+			 * 
+			 * Hence we clear any repository-based locks before releasing blockchain lock.
+			 */
+			repository.discardChanges();
+
 			blockchainLock.unlock();
 		}
 	}

src/main/java/org/qortal/transform/block/BlockTransformer.java

@@ -326,24 +326,36 @@ public class BlockTransformer extends Transformer {
 		}
 	}
 
-	public static byte[] getMinterSignatureFromReference(byte[] blockReference) {
-		return Arrays.copyOf(blockReference, MINTER_SIGNATURE_LENGTH);
+	private static byte[] getReferenceBytesForMinterSignature(int blockHeight, byte[] reference) {
+		int newBlockSigTriggerHeight = BlockChain.getInstance().getNewBlockSigHeight();
+
+		return blockHeight >= newBlockSigTriggerHeight
+				// 'new' block sig uses all of previous block's signature
+				? reference
+				// 'old' block sig only uses first 64 bytes of previous block's signature
+				: Arrays.copyOf(reference, MINTER_SIGNATURE_LENGTH);
 	}
 
-	public static byte[] getBytesForMinterSignature(BlockData blockData) throws TransformationException {
-		byte[] minterSignature = getMinterSignatureFromReference(blockData.getReference());
+	public static byte[] getBytesForMinterSignature(BlockData blockData) {
+		byte[] referenceBytes = getReferenceBytesForMinterSignature(blockData.getHeight(), blockData.getReference());
 
-		return getBytesForMinterSignature(minterSignature, blockData.getMinterPublicKey(), blockData.getEncodedOnlineAccounts());
+		return getBytesForMinterSignature(referenceBytes, blockData.getMinterPublicKey(), blockData.getEncodedOnlineAccounts());
 	}
 
-	public static byte[] getBytesForMinterSignature(byte[] minterSignature, byte[] minterPublicKey, byte[] encodedOnlineAccounts) {
-		byte[] bytes = new byte[MINTER_SIGNATURE_LENGTH + MINTER_PUBLIC_KEY_LENGTH + encodedOnlineAccounts.length];
+	public static byte[] getBytesForMinterSignature(BlockData parentBlockData, byte[] minterPublicKey, byte[] encodedOnlineAccounts) {
+		byte[] referenceBytes = getReferenceBytesForMinterSignature(parentBlockData.getHeight() + 1, parentBlockData.getSignature());
 
-		System.arraycopy(minterSignature, 0, bytes, 0, MINTER_SIGNATURE_LENGTH);
+		return getBytesForMinterSignature(referenceBytes, minterPublicKey, encodedOnlineAccounts);
+	}
 
-		System.arraycopy(minterPublicKey, 0, bytes, MINTER_SIGNATURE_LENGTH, MINTER_PUBLIC_KEY_LENGTH);
+	private static byte[] getBytesForMinterSignature(byte[] referenceBytes, byte[] minterPublicKey, byte[] encodedOnlineAccounts) {
+		byte[] bytes = new byte[referenceBytes.length + MINTER_PUBLIC_KEY_LENGTH + encodedOnlineAccounts.length];
 
-		System.arraycopy(encodedOnlineAccounts, 0, bytes, MINTER_SIGNATURE_LENGTH + MINTER_PUBLIC_KEY_LENGTH, encodedOnlineAccounts.length);
+		System.arraycopy(referenceBytes, 0, bytes, 0, referenceBytes.length);
+
+		System.arraycopy(minterPublicKey, 0, bytes, referenceBytes.length, MINTER_PUBLIC_KEY_LENGTH);
+
+		System.arraycopy(encodedOnlineAccounts, 0, bytes, referenceBytes.length + MINTER_PUBLIC_KEY_LENGTH, encodedOnlineAccounts.length);
 
 		return bytes;
 	}

src/main/java/org/qortal/utils/BIP39.java

@@ -1,86 +0,0 @@
-package org.qortal.utils;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import org.qortal.globalization.BIP39WordList;
-
-public class BIP39 {
-
-	private static final int BITS_PER_WORD = 11;
-
-	/** Convert BIP39 mnemonic to binary 'entropy' */
-	public static byte[] decode(String[] phraseWords, String lang) {
-		if (lang == null)
-			lang = "en";
-
-		List<String> wordList = BIP39WordList.INSTANCE.getByLang(lang);
-		if (wordList == null)
-			throw new IllegalStateException("BIP39 word list for lang '" + lang + "' unavailable");
-
-		byte[] entropy = new byte[(phraseWords.length * BITS_PER_WORD + 7) / 8];
-		int byteIndex = 0;
-		int bitShift = 3;
-
-		for (int i = 0; i < phraseWords.length; ++i) {
-			int wordListIndex = wordList.indexOf(phraseWords[i]);
-			if (wordListIndex == -1)
-				// Word not found
-				return null;
-
-			entropy[byteIndex++] |= (byte) (wordListIndex >> bitShift);
-
-			bitShift = 8 - bitShift;
-			if (bitShift >= 0) {
-				// Leftover fits inside one byte
-				entropy[byteIndex] |= (byte) ((wordListIndex << bitShift));
-				bitShift = BITS_PER_WORD - bitShift;
-			} else {
-				// Leftover spread over next two bytes
-				bitShift = - bitShift;
-				entropy[byteIndex++] |= (byte) (wordListIndex >> bitShift);
-
-				entropy[byteIndex] |= (byte) (wordListIndex << (8 - bitShift));
-				bitShift = bitShift + BITS_PER_WORD - 8;
-			}
-		}
-
-		return entropy;
-	}
-
-	/** Convert binary entropy to BIP39 mnemonic */
-	public static String encode(byte[] entropy, String lang) {
-		if (lang == null)
-			lang = "en";
-
-		List<String> wordList = BIP39WordList.INSTANCE.getByLang(lang);
-		if (wordList == null)
-			throw new IllegalStateException("BIP39 word list for lang '" + lang + "' unavailable");
-
-		List<String> phraseWords = new ArrayList<>();
-
-		int bitMask = 128; // MSB first
-		int byteIndex = 0;
-		while (true) {
-			int wordListIndex = 0;
-			for (int bitCount = 0; bitCount < BITS_PER_WORD; ++bitCount) {
-				wordListIndex <<= 1;
-
-				if ((entropy[byteIndex] & bitMask) != 0)
-					++wordListIndex;
-
-				bitMask >>= 1;
-				if (bitMask == 0) {
-					bitMask = 128;
-					++byteIndex;
-
-					if (byteIndex >= entropy.length)
-						return String.join(" ", phraseWords);
-				}
-			}
-
-			phraseWords.add(wordList.get(wordListIndex));
-		}
-	}
-
-}

src/main/java/org/qortal/utils/ExecuteProduceConsume.java

@@ -125,8 +125,8 @@ public abstract class ExecuteProduceConsume implements Runnable {
 			// It's possible this might need to become a class instance private volatile
 			boolean canBlock = false;
 
-			while (true) {
-				final Task task;
+			while (!Thread.currentThread().isInterrupted()) {
+				Task task = null;
 
 				this.logger.trace(() -> String.format("[%d] waiting to produce...", Thread.currentThread().getId()));
 
@@ -142,7 +142,16 @@ public abstract class ExecuteProduceConsume implements Runnable {
 							Thread.currentThread().getId(), this.activeThreadCount, this.consumerCount, lambdaCanIdle));
 
 					final long beforeProduce = isLoggerTraceEnabled ? System.currentTimeMillis() : 0;
-					task = produceTask(canBlock);
+
+					try {
+						task = produceTask(canBlock);
+					} catch (InterruptedException e) {
+						// We're in shutdown situation so exit
+						Thread.currentThread().interrupt();
+					} catch (Exception e) {
+						this.logger.warn(() -> String.format("[%d] exception while trying to produce task", Thread.currentThread().getId()), e);
+					}
+
 					this.logger.trace(() -> String.format("[%d] producing took %dms", Thread.currentThread().getId(), System.currentTimeMillis() - beforeProduce));
 				}
 
@@ -155,7 +164,8 @@ public abstract class ExecuteProduceConsume implements Runnable {
 							--this.activeThreadCount;
 							this.logger.trace(() -> String.format("[%d] ending, activeThreadCount now: %d",
 									Thread.currentThread().getId(), this.activeThreadCount));
-							break;
+
+							return;
 						}
 
 						// We're the last surviving thread - producer can afford to block next round
@@ -192,7 +202,16 @@ public abstract class ExecuteProduceConsume implements Runnable {
 				}
 
 				this.logger.trace(() -> String.format("[%d] performing task...", Thread.currentThread().getId()));
-				task.perform(); // This can block for a while
+
+				try {
+					task.perform(); // This can block for a while
+				} catch (InterruptedException e) {
+					// We're in shutdown situation so exit
+					Thread.currentThread().interrupt();
+				} catch (Exception e) {
+					this.logger.warn(() -> String.format("[%d] exception while performing task", Thread.currentThread().getId()), e);
+				}
+
 				this.logger.trace(() -> String.format("[%d] finished task", Thread.currentThread().getId()));
 
 				synchronized (this) {
@@ -206,8 +225,6 @@ public abstract class ExecuteProduceConsume implements Runnable {
 					canBlock = false;
 				}
 			}
-		} catch (InterruptedException e) {
-			// We're in shutdown situation so exit
 		} finally {
 			if (this.isLoggerTraceEnabled)
 				Thread.currentThread().setName(this.className);

src/main/resources/blockchain.json

@@ -48,6 +48,10 @@
 		"minutesPerBlock": 1
 	},
 	"featureTriggers": {
+		"atFindNextTransactionFix": 275000,
+		"newBlockSigHeight": 320000,
+		"shareBinFix": 399000,
+		"calcChainWeightTimestamp": 1620579600000
 	},
 	"genesisInfo": {
 		"version": 4,

src/main/resources/i18n/ApiError_en.properties

@@ -64,3 +64,5 @@ TRANSACTION_UNKNOWN = transaction unknown
 TRANSFORMATION_ERROR = could not transform JSON into transaction
 
 UNAUTHORIZED = API call unauthorized
+
+ORDER_SIZE_TOO_SMALL = order size too small

src/main/resources/i18n/ApiError_fi.properties

@@ -0,0 +1,71 @@
+#Generated by ResourceBundle Editor (http://essiembre.github.io/eclipse-rbe/)
+# Keys are from api.ApiError enum
+#
+# Kielen muuttaminen suomeksi tapahtuu settings.json-tiedostossa
+#
+# "localeLang": "fi",
+# muista pilkku lopussa  jos komento ei ole viimeisellä rivillä
+
+ADDRESS_UNKNOWN = tilin osoite on tuntematon
+
+BLOCKCHAIN_NEEDS_SYNC = lohkoketjun tarvitsee ensin synkronisoitua
+
+# Blocks
+BLOCK_UNKNOWN = tuntematon lohko
+
+BTC_BALANCE_ISSUE = riittämätön Bitcoin-saldo
+
+BTC_NETWORK_ISSUE = Bitcoin/ElectrumX -verkon ongelma
+
+BTC_TOO_SOON = liian aikaista julkistaa Bitcoin-tapahtumaa (lukitusaika/mediiaanilohkoaika)
+
+CANNOT_MINT = tili ei voi lyödä rahaa
+
+GROUP_UNKNOWN = tuntematon ryhmä
+
+INVALID_ADDRESS = osoite on kelvoton
+
+# Assets
+INVALID_ASSET_ID = kelvoton ID resurssille
+
+INVALID_CRITERIA = kelvoton hakuehto
+
+INVALID_DATA = kelvoton data
+
+INVALID_HEIGHT = kelvoton lohkon korkeus
+
+INVALID_NETWORK_ADDRESS = kelvoton verkko-osoite
+
+INVALID_ORDER_ID = kelvoton resurssin tilaus-ID
+
+INVALID_PRIVATE_KEY = kelvoton yksityinen avain
+
+INVALID_PUBLIC_KEY = kelvoton julkinen avain
+
+INVALID_REFERENCE = kelvoton viite
+
+# Validation
+INVALID_SIGNATURE = kelvoton allekirjoitus
+
+JSON = JSON-viestin jaottelu epäonnistui
+
+NAME_UNKNOWN = tuntematon nimi
+
+NON_PRODUCTION = tämä API-kutsu on kielletty tuotantoversiossa
+
+NO_TIME_SYNC = kello vielä synkronisoimatta
+
+ORDER_UNKNOWN = tuntematon resurssin tilaus-ID
+
+PUBLIC_KEY_NOT_FOUND = julkista avainta ei löytynyt
+
+REPOSITORY_ISSUE = tietovarantovirhe (repo)
+
+# This one is special in that caller expected to pass two additional strings, hence the two %s
+TRANSACTION_INVALID = kelvoton transaktio: %s (%s)
+
+TRANSACTION_UNKNOWN = tuntematon transaktio
+
+TRANSFORMATION_ERROR = JSON:in muuntaminen transaktioksi epäonnistui
+
+UNAUTHORIZED = luvaton API-kutsu

src/main/resources/i18n/ApiError_it.properties

@@ -0,0 +1,72 @@
+#Generated by ResourceBundle Editor (http://essiembre.github.io/eclipse-rbe/)
+# Keys are from api.ApiError enum
+# Italian translation by Pabs 2021
+
+# La modifica della lingua dell'UI è fatta nel file Settings.json
+#
+# "localeLang": "it",
+# Si prega ricordare la virgola alla fine, se questo comando non è sull'ultima riga
+
+ADDRESS_UNKNOWN = indirizzo account sconosciuto
+
+BLOCKCHAIN_NEEDS_SYNC = blockchain deve prima sincronizzarsi
+
+# Blocks
+BLOCK_UNKNOWN = blocco sconosciuto
+
+BTC_BALANCE_ISSUE = saldo Bitcoin insufficiente
+
+BTC_NETWORK_ISSUE = Bitcoin/ElectrumX problema di rete
+
+BTC_TOO_SOON = troppo presto per trasmettere transazione Bitcoin (tempo di blocco / tempo di blocco mediano)
+
+CANNOT_MINT = l'account non può coniare
+
+GROUP_UNKNOWN = gruppo sconosciuto
+
+INVALID_ADDRESS = indirizzo non valido
+
+# Assets
+INVALID_ASSET_ID = identificazione risorsa non valida
+
+INVALID_CRITERIA = criteri di ricerca non validi
+
+INVALID_DATA = dati non validi
+
+INVALID_HEIGHT = altezza blocco non valida
+
+INVALID_NETWORK_ADDRESS = indirizzo di rete non valido
+
+INVALID_ORDER_ID = identificazione di ordine di risorsa non valida
+
+INVALID_PRIVATE_KEY = chiave privata non valida
+
+INVALID_PUBLIC_KEY = chiave pubblica non valida
+
+INVALID_REFERENCE = riferimento non valido
+
+# Validation
+INVALID_SIGNATURE = firma non valida
+
+JSON = Impossibile analizzare il messaggio JSON
+
+NAME_UNKNOWN = nome sconosciuto
+
+NON_PRODUCTION = questa chiamata API non è consentita per i sistemi di produzione
+
+NO_TIME_SYNC = nessuna sincronizzazione dell'orologio ancora
+
+ORDER_UNKNOWN = identificazione di ordine di risorsa sconosciuta
+
+PUBLIC_KEY_NOT_FOUND = chiave pubblica non trovata
+
+REPOSITORY_ISSUE = errore del repositorio
+
+# This one is special in that caller expected to pass two additional strings, hence the two %s
+TRANSACTION_INVALID = transazione non valida: %s (%s)
+
+TRANSACTION_UNKNOWN = transazione sconosciuta
+
+TRANSFORMATION_ERROR = non è stato possibile trasformare JSON in transazione
+
+UNAUTHORIZED = Chiamata API non autorizzata

src/main/resources/i18n/ApiError_nl.properties

@@ -0,0 +1,66 @@
+#Generated by ResourceBundle Editor (http://essiembre.github.io/eclipse-rbe/)
+# Keys are from api.ApiError enum
+
+ADDRESS_UNKNOWN = account adres onbekend
+
+BLOCKCHAIN_NEEDS_SYNC = blockchain dient eerst gesynchronizeerd te worden
+
+# Blocks
+BLOCK_UNKNOWN = blok onbekend
+
+BTC_BALANCE_ISSUE = onvoldoende Bitcoin balans
+
+BTC_NETWORK_ISSUE = Bitcoin/ElectrumX netwerk probleem
+
+BTC_TOO_SOON = te vroeg om Bitcoin transactie te versturen (vergrendelingstijd/gemiddelde bloktijd)
+
+CANNOT_MINT = account kan niet munten
+
+GROUP_UNKNOWN = onbekende groep
+
+INVALID_ADDRESS = ongeldig adres
+
+# Assets
+INVALID_ASSET_ID = ongeldige asset ID
+
+INVALID_CRITERIA = ongeldige zoekcriteria
+
+INVALID_DATA = ongeldige gegevens
+
+INVALID_HEIGHT = ongeldige blokhoogte
+
+INVALID_NETWORK_ADDRESS = ongeldig netwerkadres
+
+INVALID_ORDER_ID = ongeldige asset order ID
+
+INVALID_PRIVATE_KEY = ongeldige private key
+
+INVALID_PUBLIC_KEY = ongeldige public key
+
+INVALID_REFERENCE = ongeldige verwijzing
+
+# Validation
+INVALID_SIGNATURE = ongeldige handtekening
+
+JSON = lezen van JSON bericht gefaald
+
+NAME_UNKNOWN = onbekende naam
+
+NON_PRODUCTION = deze API call is niet toegestaan voor productiesystemen
+
+NO_TIME_SYNC = klok nog niet gesynchronizeerd
+
+ORDER_UNKNOWN = onbekende asset order ID
+
+PUBLIC_KEY_NOT_FOUND = public key niet gevonden
+
+REPOSITORY_ISSUE = repository fout
+
+# This one is special in that caller expected to pass two additional strings, hence the two %s
+TRANSACTION_INVALID = ongeldige transactie: %s (%s)
+
+TRANSACTION_UNKNOWN = onbekende transactie
+
+TRANSFORMATION_ERROR = JSON kon niet omgezet worden in transactie
+
+UNAUTHORIZED = ongeautoriseerde API call