Merge pull request #87 from Qortal/master

Merge branch 'master' into new-coins

TestNets.md

@@ -41,13 +41,39 @@
 - 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
+- Add minting private key to nodes via API call `POST /admin/mintingaccounts <minting-private-key>`
+    The keys must have corresponding `REWARD_SHARE` transactions in testnet genesis block
+- You must have at least 2 separate minting keys and two separate nodes. Assign one minting key to each node.
+- Alternatively, comment out the `if (mintedLastBlock) { }` conditional in BlockMinter.java to allow for a single node and key.
 - 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
 
+## Single-node testnet
+
+A single-node testnet is possible with code modifications, for basic testing, or to more easily start a new testnet.
+To do so, follow these steps:
+- Comment out the `if (mintedLastBlock) { }` conditional in BlockMinter.java
+- Comment out the `minBlockchainPeers` validation in Settings.validate()
+- Set `minBlockchainPeers` to 0 in settings.json
+- Set `Synchronizer.RECOVERY_MODE_TIMEOUT` to `0`
+- All other steps should remain the same. Only a single reward share key is needed.
+- Remember to put these values back after introducing other nodes
+
+## Fixed network
+
+To restrict a testnet to a set of private nodes, you can use the "fixed network" feature.
+This ensures that the testnet nodes only communicate with each other and not other known peers.
+To do this, add the following setting to each testnet node, substituting the IP addresses:
+```
+"fixedNetwork": [
+  "192.168.0.101:62392",
+  "192.168.0.102:62392",
+  "192.168.0.103:62392"
+]
+```
+
 ## Dealing with stuck chain
 
 Maybe your nodes have been offline and no-one has minted a recent testnet block.

WindowsInstaller/Qortal.aip

@@ -17,10 +17,10 @@
     <ROW Property="Manufacturer" Value="Qortal"/>
     <ROW Property="MsiLogging" MultiBuildValue="DefaultBuild:vp"/>
     <ROW Property="NTP_GOOD" Value="false"/>
-    <ROW Property="ProductCode" Value="1033:{9BDE0BDF-72A2-44DA-8B55-E7C129DBE603} 1049:{F4FCC1D9-D286-4B3D-A50F-82034010A30F} 2052:{DBE9D682-F666-49BA-8B63-28C0AE06CBCA} 2057:{949F4DFE-E55C-4493-AAB6-5DB13E68C754} " Type="16"/>
+    <ROW Property="ProductCode" Value="1033:{8C9CFB9D-BC4C-4142-A5A5-5551BF3B9467} 1049:{4A5BDDD9-ED71-431A-A46F-D19E9DE17216} 2052:{0B9DCE00-BE23-434D-BD6A-1CFA6AB3CA43} 2057:{23D81967-556A-41B8-9981-A739E2820624} " Type="16"/>
     <ROW Property="ProductLanguage" Value="2057"/>
     <ROW Property="ProductName" Value="Qortal"/>
-    <ROW Property="ProductVersion" Value="3.0.4" Type="32"/>
+    <ROW Property="ProductVersion" Value="3.2.5" Type="32"/>
     <ROW Property="RECONFIG_NTP" Value="true"/>
     <ROW Property="REMOVE_BLOCKCHAIN" Value="YES" Type="4"/>
     <ROW Property="REPAIR_BLOCKCHAIN" Value="YES" Type="4"/>
@@ -212,7 +212,7 @@
     <ROW Component="ADDITIONAL_LICENSE_INFO_71" ComponentId="{12A3ADBE-BB7A-496C-8869-410681E6232F}" Directory_="jdk.zipfs_Dir" Attributes="0" KeyPath="ADDITIONAL_LICENSE_INFO_71" Type="0"/>
     <ROW Component="ADDITIONAL_LICENSE_INFO_8" ComponentId="{D53AD95E-CF96-4999-80FC-5812277A7456}" Directory_="java.naming_Dir" Attributes="0" KeyPath="ADDITIONAL_LICENSE_INFO_8" Type="0"/>
     <ROW Component="ADDITIONAL_LICENSE_INFO_9" ComponentId="{6B7EA9B0-5D17-47A8-B78C-FACE86D15E01}" Directory_="java.net.http_Dir" Attributes="0" KeyPath="ADDITIONAL_LICENSE_INFO_9" Type="0"/>
-    <ROW Component="AI_CustomARPName" ComponentId="{9B71A82D-8C25-40FD-806D-44BAD0B45AA2}" Directory_="APPDIR" Attributes="260" KeyPath="DisplayName" Options="1"/>
+    <ROW Component="AI_CustomARPName" ComponentId="{D5A1DC7D-914F-4425-8BA6-A1AE05D0F361}" Directory_="APPDIR" Attributes="260" KeyPath="DisplayName" Options="1"/>
     <ROW Component="AI_ExePath" ComponentId="{3644948D-AE0B-41BB-9FAF-A79E70490A08}" Directory_="APPDIR" Attributes="260" KeyPath="AI_ExePath"/>
     <ROW Component="APPDIR" ComponentId="{680DFDDE-3FB4-47A5-8FF5-934F576C6F91}" Directory_="APPDIR" Attributes="0"/>
     <ROW Component="AccessBridgeCallbacks.h" ComponentId="{288055D1-1062-47A3-AA44-5601B4E38AED}" Directory_="bridge_Dir" Attributes="0" KeyPath="AccessBridgeCallbacks.h" Type="0"/>

lib/com/dosse/WaifUPnP/1.1/WaifUPnP-1.1.pom

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>com.dosse</groupId>
+  <artifactId>WaifUPnP</artifactId>
+  <version>1.1</version>
+  <description>POM was created from install:install-file</description>
+</project>

lib/com/dosse/WaifUPnP/maven-metadata-local.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<metadata>
+  <groupId>com.dosse</groupId>
+  <artifactId>WaifUPnP</artifactId>
+  <versioning>
+    <release>1.1</release>
+    <versions>
+      <version>1.1</version>
+    </versions>
+    <lastUpdated>20220218200127</lastUpdated>
+  </versioning>
+</metadata>

pom.xml

@@ -3,11 +3,11 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>org.qortal</groupId>
 	<artifactId>qortal</artifactId>
-	<version>3.1.0</version>
+	<version>3.2.5</version>
 	<packaging>jar</packaging>
 	<properties>
 		<skipTests>true</skipTests>
-		<altcoinj.version>bf9fb80</altcoinj.version>
+		<altcoinj.version>6628cfd</altcoinj.version>
 		<bitcoinj.version>0.15.10</bitcoinj.version>
 		<bouncycastle.version>1.64</bouncycastle.version>
 		<build.timestamp>${maven.build.timestamp}</build.timestamp>
@@ -21,6 +21,9 @@
 		<dagger.version>1.2.2</dagger.version>
 		<guava.version>28.1-jre</guava.version>
 		<hsqldb.version>2.5.1</hsqldb.version>
+		<homoglyph.version>1.2.1</homoglyph.version>
+		<icu4j.version>70.1</icu4j.version>
+		<upnp.version>1.1</upnp.version>
 		<jersey.version>2.29.1</jersey.version>
 		<jetty.version>9.4.29.v20200521</jetty.version>
 		<log4j.version>2.17.1</log4j.version>
@@ -427,6 +430,12 @@
 			<artifactId>AT</artifactId>
 			<version>${ciyam-at.version}</version>
 		</dependency>
+		<!-- UPnP support -->
+		<dependency>
+			<groupId>com.dosse</groupId>
+			<artifactId>WaifUPnP</artifactId>
+			<version>${upnp.version}</version>
+		</dependency>
 		<!-- Bitcoin support -->
 		<dependency>
 			<groupId>org.bitcoinj</groupId>
@@ -435,7 +444,7 @@
 		</dependency>
 		<!-- For Litecoin, etc. support, requires bitcoinj -->
 		<dependency>
-			<groupId>com.github.jjos2372</groupId>
+			<groupId>com.github.qortal</groupId>
 			<artifactId>altcoinj</artifactId>
 			<version>${altcoinj.version}</version>
 		</dependency>
@@ -561,7 +570,18 @@
 		<dependency>
 			<groupId>net.codebox</groupId>
 			<artifactId>homoglyph</artifactId>
-			<version>1.2.0</version>
+			<version>${homoglyph.version}</version>
+		</dependency>
+		<!-- Unicode support -->
+		<dependency>
+			<groupId>com.ibm.icu</groupId>
+			<artifactId>icu4j</artifactId>
+			<version>${icu4j.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>com.ibm.icu</groupId>
+			<artifactId>icu4j-charset</artifactId>
+			<version>${icu4j.version}</version>
 		</dependency>
 		<!-- Jetty -->
 		<dependency>

src/main/java/org/qortal/account/Account.java

@@ -205,6 +205,12 @@ public class Account {
 		return false;
 	}
 
+	/** Returns account's blockMinted (0+) or null if account not found in repository. */
+	public Integer getBlocksMinted() throws DataException {
+		return this.repository.getAccountRepository().getMintedBlockCount(this.address);
+	}
+
+
 	/** Returns whether account can build reward-shares.
 	 * <p>
 	 * To be able to create reward-shares, the account needs to pass at least one of these tests:<br>
@@ -272,7 +278,7 @@ public class Account {
 	/**
 	 * Returns 'effective' minting level, or zero if reward-share does not exist.
 	 * <p>
-	 * For founder accounts, this returns "founderEffectiveMintingLevel" from blockchain config.
+	 * this is being used on src/main/java/org/qortal/api/resource/AddressesResource.java to fulfil the online accounts api call
 	 * 
 	 * @param repository
 	 * @param rewardSharePublicKey
@@ -288,5 +294,26 @@ public class Account {
 		Account rewardShareMinter = new Account(repository, rewardShareData.getMinter());
 		return rewardShareMinter.getEffectiveMintingLevel();
 	}
+	/**
+	 * Returns 'effective' minting level, with a fix for the zero level.
+	 * <p>
+	 * For founder accounts, this returns "founderEffectiveMintingLevel" from blockchain config.
+	 *
+	 * @param repository
+	 * @param rewardSharePublicKey
+	 * @return 0+
+	 * @throws DataException
+	 */
+	public static int getRewardShareEffectiveMintingLevelIncludingLevelZero(Repository repository, byte[] rewardSharePublicKey) throws DataException {
+		// Find actual minter and get their effective minting level
+		RewardShareData rewardShareData = repository.getAccountRepository().getRewardShare(rewardSharePublicKey);
+		if (rewardShareData == null)
+			return 0;
 
+		else if(!rewardShareData.getMinter().equals(rewardShareData.getRecipient()))//the minter is different than the recipient this means sponsorship
+			return 0;
+
+		Account rewardShareMinter = new Account(repository, rewardShareData.getMinter());
+		return rewardShareMinter.getEffectiveMintingLevel();
+	}
 }

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

@@ -40,13 +40,7 @@ import org.glassfish.jersey.server.ResourceConfig;
 import org.glassfish.jersey.servlet.ServletContainer;
 import org.qortal.api.resource.AnnotationPostProcessor;
 import org.qortal.api.resource.ApiDefinition;
-import org.qortal.api.websocket.ActiveChatsWebSocket;
-import org.qortal.api.websocket.AdminStatusWebSocket;
-import org.qortal.api.websocket.BlocksWebSocket;
-import org.qortal.api.websocket.ChatMessagesWebSocket;
-import org.qortal.api.websocket.PresenceWebSocket;
-import org.qortal.api.websocket.TradeBotWebSocket;
-import org.qortal.api.websocket.TradeOffersWebSocket;
+import org.qortal.api.websocket.*;
 import org.qortal.settings.Settings;
 
 public class ApiService {
@@ -212,6 +206,9 @@ public class ApiService {
 			context.addServlet(ChatMessagesWebSocket.class, "/websockets/chat/messages");
 			context.addServlet(TradeOffersWebSocket.class, "/websockets/crosschain/tradeoffers");
 			context.addServlet(TradeBotWebSocket.class, "/websockets/crosschain/tradebot");
+			context.addServlet(TradePresenceWebSocket.class, "/websockets/crosschain/tradepresence");
+
+			// Deprecated
 			context.addServlet(PresenceWebSocket.class, "/websockets/presence");
 
 			// Start server

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

@@ -28,6 +28,11 @@ public class HTMLParser {
             // Add base href tag
             String baseElement = String.format("<base href=\"%s\">", baseUrl);
             head.get(0).prepend(baseElement);
+
+            // Add meta charset tag
+            String metaCharsetElement = "<meta charset=\"UTF-8\">";
+            head.get(0).prepend(metaCharsetElement);
+
         }
         String html = document.html();
         this.data = html.getBytes();

src/main/java/org/qortal/api/domainmap/resource/DomainMapResource.java

@@ -17,7 +17,7 @@ import java.util.Map;
 
 
 @Path("/")
-@Tag(name = "Gateway")
+@Tag(name = "Domain Map")
 public class DomainMapResource {
 
     @Context HttpServletRequest request;

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

@@ -24,9 +24,9 @@ public class NodeStatus {
 		this.isMintingPossible = Controller.getInstance().isMintingPossible();
 
 		this.syncPercent = Synchronizer.getInstance().getSyncPercent();
-		this.isSynchronizing = this.syncPercent != null;
+		this.isSynchronizing = Synchronizer.getInstance().isSynchronizing();
 
-		this.numberOfConnections = Network.getInstance().getHandshakedPeers().size();
+		this.numberOfConnections = Network.getInstance().getImmutableHandshakedPeers().size();
 
 		this.height = Controller.getInstance().getChainHeight();
 	}

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

@@ -0,0 +1,29 @@
+package org.qortal.api.model.crosschain;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class DigibyteSendRequest {
+
+	@Schema(description = "Digibyte BIP32 extended private key", example = "tprv___________________________________________________________________________________________________________")
+	public String xprv58;
+
+	@Schema(description = "Recipient's Digibyte address ('legacy' P2PKH only)", example = "1DigByteEaterAddressDontSendf59kuE")
+	public String receivingAddress;
+
+	@Schema(description = "Amount of DGB to send", type = "number")
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	public long digibyteAmount;
+
+	@Schema(description = "Transaction fee per byte (optional). Default is 0.00000100 DGB (100 sats) per byte", example = "0.00000100", type = "number")
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	public Long feePerByte;
+
+	public DigibyteSendRequest() {
+	}
+
+}

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

@@ -0,0 +1,29 @@
+package org.qortal.api.model.crosschain;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class RavencoinSendRequest {
+
+	@Schema(description = "Ravencoin BIP32 extended private key", example = "tprv___________________________________________________________________________________________________________")
+	public String xprv58;
+
+	@Schema(description = "Recipient's Ravencoin address ('legacy' P2PKH only)", example = "1RvnCoinEaterAddressDontSendf59kuE")
+	public String receivingAddress;
+
+	@Schema(description = "Amount of RVN to send", type = "number")
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	public long ravencoinAmount;
+
+	@Schema(description = "Transaction fee per byte (optional). Default is 0.00000100 RVN (100 sats) per byte", example = "0.00000100", type = "number")
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	public Long feePerByte;
+
+	public RavencoinSendRequest() {
+	}
+
+}

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

@@ -30,7 +30,7 @@ import org.qortal.api.Security;
 import org.qortal.api.model.ApiOnlineAccount;
 import org.qortal.api.model.RewardShareKeyRequest;
 import org.qortal.asset.Asset;
-import org.qortal.controller.Controller;
+import org.qortal.controller.OnlineAccountsManager;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.account.AccountData;
 import org.qortal.data.account.RewardShareData;
@@ -156,7 +156,7 @@ public class AddressesResource {
 	)
 	@ApiErrors({ApiError.PUBLIC_KEY_NOT_FOUND, ApiError.REPOSITORY_ISSUE})
 	public List<ApiOnlineAccount> getOnlineAccounts() {
-		List<OnlineAccountData> onlineAccounts = Controller.getInstance().getOnlineAccounts();
+		List<OnlineAccountData> onlineAccounts = OnlineAccountsManager.getInstance().getOnlineAccounts();
 
 		// Map OnlineAccountData entries to OnlineAccount via reward-share data
 		try (final Repository repository = RepositoryManager.getRepository()) {
@@ -191,14 +191,14 @@ public class AddressesResource {
 	)
 	@ApiErrors({ApiError.PUBLIC_KEY_NOT_FOUND, ApiError.REPOSITORY_ISSUE})
 	public List<OnlineAccountLevel> getOnlineAccountsByLevel() {
-		List<OnlineAccountData> onlineAccounts = Controller.getInstance().getOnlineAccounts();
+		List<OnlineAccountData> onlineAccounts = OnlineAccountsManager.getInstance().getOnlineAccounts();
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			List<OnlineAccountLevel> onlineAccountLevels = new ArrayList<>();
 
 			for (OnlineAccountData onlineAccountData : onlineAccounts) {
 				try {
-					final int minterLevel = Account.getRewardShareEffectiveMintingLevel(repository, onlineAccountData.getPublicKey());
+					final int minterLevel = Account.getRewardShareEffectiveMintingLevelIncludingLevelZero(repository, onlineAccountData.getPublicKey());
 
 					OnlineAccountLevel onlineAccountLevel = onlineAccountLevels.stream()
 							.filter(a -> a.getLevel() == minterLevel)

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

@@ -35,7 +35,6 @@ import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.apache.logging.log4j.core.LoggerContext;
 import org.apache.logging.log4j.core.appender.RollingFileAppender;
-import org.checkerframework.checker.units.qual.A;
 import org.qortal.account.Account;
 import org.qortal.account.PrivateKeyAccount;
 import org.qortal.api.*;
@@ -315,6 +314,7 @@ public class AdminResource {
 
 			repository.getAccountRepository().save(mintingAccountData);
 			repository.saveChanges();
+			repository.exportNodeLocalData();//after adding new minting account let's persist it to the backup  MintingAccounts.json 
 		} catch (IllegalArgumentException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY, e);
 		} catch (DataException e) {
@@ -355,6 +355,7 @@ public class AdminResource {
 				return "false";
 
 			repository.saveChanges();
+			repository.exportNodeLocalData();//after removing new minting account let's persist it to the backup  MintingAccounts.json 
 		} catch (IllegalArgumentException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY, e);
 		} catch (DataException e) {
@@ -380,6 +381,10 @@ public class AdminResource {
 			) @QueryParam("limit") Integer limit, @Parameter(
 				ref = "offset"
 			) @QueryParam("offset") Integer offset, @Parameter(
+				name = "tail",
+				description = "Fetch most recent log lines",
+				schema = @Schema(type = "boolean")
+			) @QueryParam("tail") Boolean tail, @Parameter(
 				ref = "reverse"
 			) @QueryParam("reverse") Boolean reverse) {
 		LoggerContext loggerContext = (LoggerContext) LogManager.getContext();
@@ -395,6 +400,13 @@ public class AdminResource {
 			if (reverse != null && reverse)
 				logLines = Lists.reverse(logLines);
 
+			// Tail mode - return the last X lines (where X = limit)
+			if (tail != null && tail) {
+				if (limit != null && limit > 0) {
+					offset = logLines.size() - limit;
+				}
+			}
+
 			// offset out of bounds?
 			if (offset != null && (offset < 0 || offset >= logLines.size()))
 				return "";
@@ -415,7 +427,7 @@ public class AdminResource {
 
 			limit = Math.min(limit, logLines.size());
 
-			logLines.subList(limit - 1, logLines.size()).clear();
+			logLines.subList(limit, logLines.size()).clear();
 
 			return String.join("\n", logLines);
 		} catch (IOException e) {
@@ -512,7 +524,7 @@ public class AdminResource {
 			PeerAddress peerAddress = PeerAddress.fromString(targetPeerAddress);
 			InetSocketAddress resolvedAddress = peerAddress.toSocketAddress();
 
-			List<Peer> peers = Network.getInstance().getHandshakedPeers();
+			List<Peer> peers = Network.getInstance().getImmutableHandshakedPeers();
 			Peer targetPeer = peers.stream().filter(peer -> peer.getResolvedAddress().equals(resolvedAddress)).findFirst().orElse(null);
 
 			if (targetPeer == null)
@@ -546,7 +558,7 @@ public class AdminResource {
 	@Path("/repository/data")
 	@Operation(
 		summary = "Export sensitive/node-local data from repository.",
-		description = "Exports data to .script files on local machine"
+		description = "Exports data to .json files on local machine"
 	)
 	@ApiErrors({ApiError.INVALID_DATA, ApiError.REPOSITORY_ISSUE})
 	@SecurityRequirement(name = "apiKey")
@@ -587,10 +599,6 @@ public class AdminResource {
 	public String importRepository(@HeaderParam(Security.API_KEY_HEADER) String apiKey, String filename) {
 		Security.checkApiCallAllowed(request);
 
-		// Hard-coded because it's too dangerous to allow user-supplied filenames in weaker security contexts
-		if (Settings.getInstance().getApiKey() == null)
-			filename = "qortal-backup/TradeBotStates.json";
-
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
 

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

@@ -12,6 +12,7 @@ import io.swagger.v3.oas.annotations.security.SecurityRequirement;
 import io.swagger.v3.oas.annotations.tags.Tag;
 
 import java.io.*;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Paths;
 import java.util.ArrayList;
@@ -33,13 +34,14 @@ import org.qortal.api.resource.TransactionsResource.ConfirmationStatus;
 import org.qortal.arbitrary.*;
 import org.qortal.arbitrary.ArbitraryDataFile.ResourceIdType;
 import org.qortal.arbitrary.exception.MissingDataException;
+import org.qortal.arbitrary.metadata.ArbitraryDataTransactionMetadata;
+import org.qortal.arbitrary.misc.Category;
 import org.qortal.arbitrary.misc.Service;
 import org.qortal.controller.Controller;
 import org.qortal.controller.arbitrary.ArbitraryDataStorageManager;
+import org.qortal.controller.arbitrary.ArbitraryMetadataManager;
 import org.qortal.data.account.AccountData;
-import org.qortal.data.arbitrary.ArbitraryResourceInfo;
-import org.qortal.data.arbitrary.ArbitraryResourceNameInfo;
-import org.qortal.data.arbitrary.ArbitraryResourceStatus;
+import org.qortal.data.arbitrary.*;
 import org.qortal.data.naming.NameData;
 import org.qortal.data.transaction.ArbitraryTransactionData;
 import org.qortal.data.transaction.TransactionData;
@@ -88,7 +90,8 @@ public class ArbitraryResource {
 			@Parameter(ref = "limit") @QueryParam("limit") Integer limit,
 			@Parameter(ref = "offset") @QueryParam("offset") Integer offset,
 			@Parameter(ref = "reverse") @QueryParam("reverse") Boolean reverse,
-			@Parameter(description = "Include status") @QueryParam("includestatus") Boolean includeStatus) {
+			@Parameter(description = "Include status") @QueryParam("includestatus") Boolean includeStatus,
+			@Parameter(description = "Include metadata") @QueryParam("includemetadata") Boolean includeMetadata) {
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
 
@@ -110,9 +113,12 @@ public class ArbitraryResource {
 				return new ArrayList<>();
 			}
 
-			if (includeStatus != null && includeStatus == true) {
+			if (includeStatus != null && includeStatus) {
 				resources = this.addStatusToResources(resources);
 			}
+			if (includeMetadata != null && includeMetadata) {
+				resources = this.addMetadataToResources(resources);
+			}
 
 			return resources;
 
@@ -140,7 +146,8 @@ public class ArbitraryResource {
 			@Parameter(ref = "limit") @QueryParam("limit") Integer limit,
 			@Parameter(ref = "offset") @QueryParam("offset") Integer offset,
 			@Parameter(ref = "reverse") @QueryParam("reverse") Boolean reverse,
-			@Parameter(description = "Include status") @QueryParam("includestatus") Boolean includeStatus) {
+			@Parameter(description = "Include status") @QueryParam("includestatus") Boolean includeStatus,
+			@Parameter(description = "Include metadata") @QueryParam("includemetadata") Boolean includeMetadata) {
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
 
@@ -153,9 +160,12 @@ public class ArbitraryResource {
 				return new ArrayList<>();
 			}
 
-			if (includeStatus != null && includeStatus == true) {
+			if (includeStatus != null && includeStatus) {
 				resources = this.addStatusToResources(resources);
 			}
+			if (includeMetadata != null && includeMetadata) {
+				resources = this.addMetadataToResources(resources);
+			}
 
 			return resources;
 
@@ -182,7 +192,8 @@ public class ArbitraryResource {
 			@Parameter(ref = "limit") @QueryParam("limit") Integer limit,
 			@Parameter(ref = "offset") @QueryParam("offset") Integer offset,
 			@Parameter(ref = "reverse") @QueryParam("reverse") Boolean reverse,
-			@Parameter(description = "Include status") @QueryParam("includestatus") Boolean includeStatus) {
+			@Parameter(description = "Include status") @QueryParam("includestatus") Boolean includeStatus,
+			@Parameter(description = "Include metadata") @QueryParam("includemetadata") Boolean includeMetadata) {
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
 
@@ -206,9 +217,13 @@ public class ArbitraryResource {
 					List<ArbitraryResourceInfo> resources = repository.getArbitraryRepository()
 							.getArbitraryResources(service, identifier, name, defaultRes, null, null, reverse);
 
-					if (includeStatus != null && includeStatus == true) {
+					if (includeStatus != null && includeStatus) {
 						resources = this.addStatusToResources(resources);
 					}
+					if (includeMetadata != null && includeMetadata) {
+						resources = this.addMetadataToResources(resources);
+					}
+
 					creatorName.resources = resources;
 				}
 			}
@@ -390,6 +405,28 @@ public class ArbitraryResource {
 		return Settings.getInstance().isRelayModeEnabled();
 	}
 
+	@GET
+	@Path("/categories")
+	@Operation(
+			summary = "List arbitrary transaction categories",
+			responses = {
+					@ApiResponse(
+							content = @Content(mediaType = MediaType.APPLICATION_JSON, schema = @Schema(implementation = ArbitraryCategoryInfo.class))
+					)
+			}
+	)
+	@ApiErrors({ApiError.REPOSITORY_ISSUE})
+	public List<ArbitraryCategoryInfo> getCategories() {
+		List<ArbitraryCategoryInfo> categories = new ArrayList<>();
+		for (Category category : Category.values()) {
+			ArbitraryCategoryInfo arbitraryCategory = new ArbitraryCategoryInfo();
+			arbitraryCategory.id = category.toString();
+			arbitraryCategory.name = category.getName();
+			categories.add(arbitraryCategory);
+		}
+		return categories;
+	}
+
 	@GET
 	@Path("/hosted/transactions")
 	@Operation(
@@ -431,15 +468,24 @@ public class ArbitraryResource {
 	public List<ArbitraryResourceInfo> getHostedResources(
 			@HeaderParam(Security.API_KEY_HEADER) String apiKey,
 			@Parameter(description = "Include status") @QueryParam("includestatus") Boolean includeStatus,
+			@Parameter(description = "Include metadata") @QueryParam("includemetadata") Boolean includeMetadata,
 			@Parameter(ref = "limit") @QueryParam("limit") Integer limit,
-			@Parameter(ref = "offset") @QueryParam("offset") Integer offset) {
+			@Parameter(ref = "offset") @QueryParam("offset") Integer offset,
+			@QueryParam("query") String query) {
 		Security.checkApiCallAllowed(request);
 
 		List<ArbitraryResourceInfo> resources = new ArrayList<>();
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
+			
+			List<ArbitraryTransactionData> transactionDataList;
+
+			if (query == null || query.equals("")) {
+				transactionDataList = ArbitraryDataStorageManager.getInstance().listAllHostedTransactions(repository, limit, offset);
+			} else {
+				transactionDataList = ArbitraryDataStorageManager.getInstance().searchHostedTransactions(repository,query, limit, offset);
+			}
 
-			List<ArbitraryTransactionData> transactionDataList = ArbitraryDataStorageManager.getInstance().listAllHostedTransactions(repository, limit, offset);
 			for (ArbitraryTransactionData transactionData : transactionDataList) {
 				ArbitraryResourceInfo arbitraryResourceInfo = new ArbitraryResourceInfo();
 				arbitraryResourceInfo.name = transactionData.getName();
@@ -450,9 +496,12 @@ public class ArbitraryResource {
 				}
 			}
 
-			if (includeStatus != null && includeStatus == true) {
+			if (includeStatus != null && includeStatus) {
 				resources = this.addStatusToResources(resources);
 			}
+			if (includeMetadata != null && includeMetadata) {
+				resources = this.addMetadataToResources(resources);
+			}
 
 			return resources;
 
@@ -461,6 +510,8 @@ public class ArbitraryResource {
 		}
 	}
 
+
+
 	@DELETE
 	@Path("/resource/{service}/{name}/{identifier}")
 	@Operation(
@@ -624,6 +675,54 @@ public class ArbitraryResource {
 	}
 
 
+	// Metadata
+
+	@GET
+	@Path("/metadata/{service}/{name}/{identifier}")
+	@Operation(
+			summary = "Fetch raw metadata from resource with supplied service, name, identifier, and relative path",
+			responses = {
+					@ApiResponse(
+							description = "Path to file structure containing requested data",
+							content = @Content(
+									mediaType = MediaType.APPLICATION_JSON,
+									schema = @Schema(
+											implementation = ArbitraryDataTransactionMetadata.class
+									)
+							)
+					)
+			}
+	)
+	@SecurityRequirement(name = "apiKey")
+	public ArbitraryResourceMetadata getMetadata(@HeaderParam(Security.API_KEY_HEADER) String apiKey,
+							  @PathParam("service") Service service,
+							  @PathParam("name") String name,
+							  @PathParam("identifier") String identifier) {
+		Security.checkApiCallAllowed(request);
+
+		ArbitraryDataResource resource = new ArbitraryDataResource(name, ResourceIdType.NAME, service, identifier);
+
+		try {
+			ArbitraryDataTransactionMetadata transactionMetadata = ArbitraryMetadataManager.getInstance().fetchMetadata(resource, false);
+			if (transactionMetadata != null) {
+				ArbitraryResourceMetadata resourceMetadata = ArbitraryResourceMetadata.fromTransactionMetadata(transactionMetadata);
+				if (resourceMetadata != null) {
+					return resourceMetadata;
+				}
+				else {
+					// The metadata file doesn't contain title, description, category, or tags
+					throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FILE_NOT_FOUND);
+				}
+			}
+		} catch (IllegalArgumentException e) {
+			// No metadata exists for this resource
+			throw ApiExceptionFactory.INSTANCE.createCustomException(request, ApiError.FILE_NOT_FOUND, e.getMessage());
+		}
+
+		throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+	}
+
+
 
 	// Upload data at supplied path
 
@@ -656,6 +755,10 @@ public class ArbitraryResource {
 	public String post(@HeaderParam(Security.API_KEY_HEADER) String apiKey,
 					   @PathParam("service") String serviceString,
 					   @PathParam("name") String name,
+					   @QueryParam("title") String title,
+					   @QueryParam("description") String description,
+					   @QueryParam("tags") List<String> tags,
+					   @QueryParam("category") Category category,
 					   String path) {
 		Security.checkApiCallAllowed(request);
 
@@ -663,7 +766,8 @@ public class ArbitraryResource {
 			throw ApiExceptionFactory.INSTANCE.createCustomException(request, ApiError.INVALID_CRITERIA, "Path not supplied");
 		}
 
-		return this.upload(Service.valueOf(serviceString), name, null, path, null, null, false);
+		return this.upload(Service.valueOf(serviceString), name, null, path, null, null, false,
+				title, description, tags, category);
 	}
 
 	@POST
@@ -696,6 +800,10 @@ public class ArbitraryResource {
 					   @PathParam("service") String serviceString,
 					   @PathParam("name") String name,
 					   @PathParam("identifier") String identifier,
+					   @QueryParam("title") String title,
+					   @QueryParam("description") String description,
+					   @QueryParam("tags") List<String> tags,
+					   @QueryParam("category") Category category,
 					   String path) {
 		Security.checkApiCallAllowed(request);
 
@@ -703,7 +811,8 @@ public class ArbitraryResource {
 			throw ApiExceptionFactory.INSTANCE.createCustomException(request, ApiError.INVALID_CRITERIA, "Path not supplied");
 		}
 
-		return this.upload(Service.valueOf(serviceString), name, identifier, path, null, null, false);
+		return this.upload(Service.valueOf(serviceString), name, identifier, path, null, null, false,
+				title, description, tags, category);
 	}
 
 
@@ -737,6 +846,10 @@ public class ArbitraryResource {
 	public String postBase64EncodedData(@HeaderParam(Security.API_KEY_HEADER) String apiKey,
 										@PathParam("service") String serviceString,
 										@PathParam("name") String name,
+										@QueryParam("title") String title,
+										@QueryParam("description") String description,
+										@QueryParam("tags") List<String> tags,
+										@QueryParam("category") Category category,
 										String base64) {
 		Security.checkApiCallAllowed(request);
 
@@ -744,7 +857,8 @@ public class ArbitraryResource {
 			throw ApiExceptionFactory.INSTANCE.createCustomException(request, ApiError.INVALID_CRITERIA, "Data not supplied");
 		}
 
-		return this.upload(Service.valueOf(serviceString), name, null, null, null, base64, false);
+		return this.upload(Service.valueOf(serviceString), name, null, null, null, base64, false,
+				title, description, tags, category);
 	}
 
 	@POST
@@ -775,6 +889,10 @@ public class ArbitraryResource {
 										@PathParam("service") String serviceString,
 										@PathParam("name") String name,
 										@PathParam("identifier") String identifier,
+										@QueryParam("title") String title,
+										@QueryParam("description") String description,
+										@QueryParam("tags") List<String> tags,
+										@QueryParam("category") Category category,
 										String base64) {
 		Security.checkApiCallAllowed(request);
 
@@ -782,7 +900,8 @@ public class ArbitraryResource {
 			throw ApiExceptionFactory.INSTANCE.createCustomException(request, ApiError.INVALID_CRITERIA, "Data not supplied");
 		}
 
-		return this.upload(Service.valueOf(serviceString), name, identifier, null, null, base64, false);
+		return this.upload(Service.valueOf(serviceString), name, identifier, null, null, base64, false,
+				title, description, tags, category);
 	}
 
 
@@ -815,6 +934,10 @@ public class ArbitraryResource {
 	public String postZippedData(@HeaderParam(Security.API_KEY_HEADER) String apiKey,
 								 @PathParam("service") String serviceString,
 								 @PathParam("name") String name,
+								 @QueryParam("title") String title,
+								 @QueryParam("description") String description,
+								 @QueryParam("tags") List<String> tags,
+								 @QueryParam("category") Category category,
 								 String base64Zip) {
 		Security.checkApiCallAllowed(request);
 
@@ -822,7 +945,8 @@ public class ArbitraryResource {
 			throw ApiExceptionFactory.INSTANCE.createCustomException(request, ApiError.INVALID_CRITERIA, "Data not supplied");
 		}
 
-		return this.upload(Service.valueOf(serviceString), name, null, null, null, base64Zip, true);
+		return this.upload(Service.valueOf(serviceString), name, null, null, null, base64Zip, true,
+				title, description, tags, category);
 	}
 
 	@POST
@@ -853,6 +977,10 @@ public class ArbitraryResource {
 								 @PathParam("service") String serviceString,
 								 @PathParam("name") String name,
 								 @PathParam("identifier") String identifier,
+								 @QueryParam("title") String title,
+								 @QueryParam("description") String description,
+								 @QueryParam("tags") List<String> tags,
+								 @QueryParam("category") Category category,
 								 String base64Zip) {
 		Security.checkApiCallAllowed(request);
 
@@ -860,7 +988,8 @@ public class ArbitraryResource {
 			throw ApiExceptionFactory.INSTANCE.createCustomException(request, ApiError.INVALID_CRITERIA, "Data not supplied");
 		}
 
-		return this.upload(Service.valueOf(serviceString), name, identifier, null, null, base64Zip, true);
+		return this.upload(Service.valueOf(serviceString), name, identifier, null, null, base64Zip, true,
+				title, description, tags, category);
 	}
 
 
@@ -896,6 +1025,10 @@ public class ArbitraryResource {
 	public String postString(@HeaderParam(Security.API_KEY_HEADER) String apiKey,
 							 @PathParam("service") String serviceString,
 							 @PathParam("name") String name,
+							 @QueryParam("title") String title,
+							 @QueryParam("description") String description,
+							 @QueryParam("tags") List<String> tags,
+							 @QueryParam("category") Category category,
 							 String string) {
 		Security.checkApiCallAllowed(request);
 
@@ -903,7 +1036,8 @@ public class ArbitraryResource {
 			throw ApiExceptionFactory.INSTANCE.createCustomException(request, ApiError.INVALID_CRITERIA, "Data string not supplied");
 		}
 
-		return this.upload(Service.valueOf(serviceString), name, null, null, string, null, false);
+		return this.upload(Service.valueOf(serviceString), name, null, null, string, null, false,
+				title, description, tags, category);
 	}
 
 	@POST
@@ -936,6 +1070,10 @@ public class ArbitraryResource {
 							 @PathParam("service") String serviceString,
 							 @PathParam("name") String name,
 							 @PathParam("identifier") String identifier,
+							 @QueryParam("title") String title,
+							 @QueryParam("description") String description,
+							 @QueryParam("tags") List<String> tags,
+							 @QueryParam("category") Category category,
 							 String string) {
 		Security.checkApiCallAllowed(request);
 
@@ -943,13 +1081,16 @@ public class ArbitraryResource {
 			throw ApiExceptionFactory.INSTANCE.createCustomException(request, ApiError.INVALID_CRITERIA, "Data string not supplied");
 		}
 
-		return this.upload(Service.valueOf(serviceString), name, identifier, null, string, null, false);
+		return this.upload(Service.valueOf(serviceString), name, identifier, null, string, null, false,
+				title, description, tags, category);
 	}
 
 
 	// Shared methods
 
-	private String upload(Service service, String name, String identifier, String path, String string, String base64, boolean zipped) {
+	private String upload(Service service, String name, String identifier,
+						  String path, String string, String base64, boolean zipped,
+						  String title, String description, List<String> tags, Category category) {
 		// Fetch public key from registered name
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			NameData nameData = repository.getNameRepository().fromName(name);
@@ -1013,7 +1154,8 @@ public class ArbitraryResource {
 
 			try {
 				ArbitraryDataTransactionBuilder transactionBuilder = new ArbitraryDataTransactionBuilder(
-						repository, publicKey58, Paths.get(path), name, null, service, identifier
+						repository, publicKey58, Paths.get(path), name, null, service, identifier,
+						title, description, tags, category
 				);
 
 				transactionBuilder.build();
@@ -1124,12 +1266,34 @@ public class ArbitraryResource {
 	private List<ArbitraryResourceInfo> addStatusToResources(List<ArbitraryResourceInfo> resources) {
 		// Determine and add the status of each resource
 		List<ArbitraryResourceInfo> updatedResources = new ArrayList<>();
+		for (ArbitraryResourceInfo resourceInfo : resources) {
+			try {
+				ArbitraryDataResource resource = new ArbitraryDataResource(resourceInfo.name, ResourceIdType.NAME,
+						resourceInfo.service, resourceInfo.identifier);
+				ArbitraryResourceStatus status = resource.getStatus(true);
+				if (status != null) {
+					resourceInfo.status = status;
+				}
+				updatedResources.add(resourceInfo);
+
+			} catch (Exception e) {
+				// Catch and log all exceptions, since some systems are experiencing 500 errors when including statuses
+				LOGGER.info("Caught exception when adding status to resource %s: %s", resourceInfo, e.toString());
+			}
+		}
+		return updatedResources;
+	}
+
+	private List<ArbitraryResourceInfo> addMetadataToResources(List<ArbitraryResourceInfo> resources) {
+		// Add metadata fields to each resource if they exist
+		List<ArbitraryResourceInfo> updatedResources = new ArrayList<>();
 		for (ArbitraryResourceInfo resourceInfo : resources) {
 			ArbitraryDataResource resource = new ArbitraryDataResource(resourceInfo.name, ResourceIdType.NAME,
 					resourceInfo.service, resourceInfo.identifier);
-			ArbitraryResourceStatus status = resource.getStatus(true);
-			if (status != null) {
-				resourceInfo.status = status;
+			ArbitraryDataTransactionMetadata transactionMetadata = resource.getLatestTransactionMetadata();
+			ArbitraryResourceMetadata resourceMetadata = ArbitraryResourceMetadata.fromTransactionMetadata(transactionMetadata);
+			if (resourceMetadata != null) {
+				resourceInfo.metadata = resourceMetadata;
 			}
 			updatedResources.add(resourceInfo);
 		}

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

@@ -122,7 +122,7 @@ public class CrossChainBitcoinResource {
 	@Path("/send")
 	@Operation(
 		summary = "Sends BTC from hierarchical, deterministic BIP32 wallet to specific address",
-		description = "Currently only supports 'legacy' P2PKH Bitcoin addresses. Supply BIP32 'm' private key in base58, starting with 'xprv' for mainnet, 'tprv' for testnet",
+		description = "Currently supports 'legacy' P2PKH Bitcoin addresses and Native SegWit (P2WPKH) addresses. Supply BIP32 'm' private key in base58, starting with 'xprv' for mainnet, 'tprv' for testnet",
 		requestBody = @RequestBody(
 			required = true,
 			content = @Content(

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

@@ -0,0 +1,177 @@
+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.security.SecurityRequirement;
+import io.swagger.v3.oas.annotations.tags.Tag;
+
+import java.util.List;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.HeaderParam;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+
+import org.bitcoinj.core.Transaction;
+import org.qortal.api.ApiError;
+import org.qortal.api.ApiErrors;
+import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.Security;
+import org.qortal.api.model.crosschain.DigibyteSendRequest;
+import org.qortal.crosschain.Digibyte;
+import org.qortal.crosschain.ForeignBlockchainException;
+import org.qortal.crosschain.SimpleTransaction;
+
+@Path("/crosschain/dgb")
+@Tag(name = "Cross-Chain (Digibyte)")
+public class CrossChainDigibyteResource {
+
+	@Context
+	HttpServletRequest request;
+
+	@POST
+	@Path("/walletbalance")
+	@Operation(
+		summary = "Returns DGB 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})
+	@SecurityRequirement(name = "apiKey")
+	public String getDigibyteWalletBalance(@HeaderParam(Security.API_KEY_HEADER) String apiKey, String key58) {
+		Security.checkApiCallAllowed(request);
+
+		Digibyte digibyte = Digibyte.getInstance();
+
+		if (!digibyte.isValidDeterministicKey(key58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		try {
+			Long balance = digibyte.getWalletBalanceFromTransactions(key58);
+			if (balance == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+
+			return balance.toString();
+
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+		}
+	}
+
+	@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})
+	@SecurityRequirement(name = "apiKey")
+	public List<SimpleTransaction> getDigibyteWalletTransactions(@HeaderParam(Security.API_KEY_HEADER) String apiKey, String key58) {
+		Security.checkApiCallAllowed(request);
+
+		Digibyte digibyte = Digibyte.getInstance();
+
+		if (!digibyte.isValidDeterministicKey(key58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		try {
+			return digibyte.getWalletTransactions(key58);
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+		}
+	}
+
+	@POST
+	@Path("/send")
+	@Operation(
+		summary = "Sends DGB from hierarchical, deterministic BIP32 wallet to specific address",
+		description = "Currently supports 'legacy' P2PKH Digibyte addresses and Native SegWit (P2WPKH) 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 = DigibyteSendRequest.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})
+	@SecurityRequirement(name = "apiKey")
+	public String sendBitcoin(@HeaderParam(Security.API_KEY_HEADER) String apiKey, DigibyteSendRequest digibyteSendRequest) {
+		Security.checkApiCallAllowed(request);
+
+		if (digibyteSendRequest.digibyteAmount <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		if (digibyteSendRequest.feePerByte != null && digibyteSendRequest.feePerByte <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		Digibyte digibyte = Digibyte.getInstance();
+
+		if (!digibyte.isValidAddress(digibyteSendRequest.receivingAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (!digibyte.isValidDeterministicKey(digibyteSendRequest.xprv58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		Transaction spendTransaction = digibyte.buildSpend(digibyteSendRequest.xprv58,
+				digibyteSendRequest.receivingAddress,
+				digibyteSendRequest.digibyteAmount,
+				digibyteSendRequest.feePerByte);
+
+		if (spendTransaction == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE);
+
+		try {
+			digibyte.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/CrossChainLitecoinResource.java

@@ -122,7 +122,7 @@ public class CrossChainLitecoinResource {
 	@Path("/send")
 	@Operation(
 		summary = "Sends LTC from hierarchical, deterministic BIP32 wallet to specific address",
-		description = "Currently only supports 'legacy' P2PKH Litecoin addresses. Supply BIP32 'm' private key in base58, starting with 'xprv' for mainnet, 'tprv' for testnet",
+		description = "Currently supports 'legacy' P2PKH Litecoin addresses and Native SegWit (P2WPKH) addresses. Supply BIP32 'm' private key in base58, starting with 'xprv' for mainnet, 'tprv' for testnet",
 		requestBody = @RequestBody(
 			required = true,
 			content = @Content(

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

@@ -0,0 +1,177 @@
+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.security.SecurityRequirement;
+import io.swagger.v3.oas.annotations.tags.Tag;
+
+import java.util.List;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.HeaderParam;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+
+import org.bitcoinj.core.Transaction;
+import org.qortal.api.ApiError;
+import org.qortal.api.ApiErrors;
+import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.Security;
+import org.qortal.api.model.crosschain.RavencoinSendRequest;
+import org.qortal.crosschain.Ravencoin;
+import org.qortal.crosschain.ForeignBlockchainException;
+import org.qortal.crosschain.SimpleTransaction;
+
+@Path("/crosschain/rvn")
+@Tag(name = "Cross-Chain (Ravencoin)")
+public class CrossChainRavencoinResource {
+
+	@Context
+	HttpServletRequest request;
+
+	@POST
+	@Path("/walletbalance")
+	@Operation(
+		summary = "Returns RVN 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})
+	@SecurityRequirement(name = "apiKey")
+	public String getRavencoinWalletBalance(@HeaderParam(Security.API_KEY_HEADER) String apiKey, String key58) {
+		Security.checkApiCallAllowed(request);
+
+		Ravencoin ravencoin = Ravencoin.getInstance();
+
+		if (!ravencoin.isValidDeterministicKey(key58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		try {
+			Long balance = ravencoin.getWalletBalanceFromTransactions(key58);
+			if (balance == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+
+			return balance.toString();
+
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+		}
+	}
+
+	@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})
+	@SecurityRequirement(name = "apiKey")
+	public List<SimpleTransaction> getRavencoinWalletTransactions(@HeaderParam(Security.API_KEY_HEADER) String apiKey, String key58) {
+		Security.checkApiCallAllowed(request);
+
+		Ravencoin ravencoin = Ravencoin.getInstance();
+
+		if (!ravencoin.isValidDeterministicKey(key58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		try {
+			return ravencoin.getWalletTransactions(key58);
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+		}
+	}
+
+	@POST
+	@Path("/send")
+	@Operation(
+		summary = "Sends RVN from hierarchical, deterministic BIP32 wallet to specific address",
+		description = "Currently only supports 'legacy' P2PKH Ravencoin 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 = RavencoinSendRequest.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})
+	@SecurityRequirement(name = "apiKey")
+	public String sendBitcoin(@HeaderParam(Security.API_KEY_HEADER) String apiKey, RavencoinSendRequest ravencoinSendRequest) {
+		Security.checkApiCallAllowed(request);
+
+		if (ravencoinSendRequest.ravencoinAmount <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		if (ravencoinSendRequest.feePerByte != null && ravencoinSendRequest.feePerByte <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		Ravencoin ravencoin = Ravencoin.getInstance();
+
+		if (!ravencoin.isValidAddress(ravencoinSendRequest.receivingAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (!ravencoin.isValidDeterministicKey(ravencoinSendRequest.xprv58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		Transaction spendTransaction = ravencoin.buildSpend(ravencoinSendRequest.xprv58,
+				ravencoinSendRequest.receivingAddress,
+				ravencoinSendRequest.ravencoinAmount,
+				ravencoinSendRequest.feePerByte);
+
+		if (spendTransaction == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE);
+
+		try {
+			ravencoin.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/CrossChainResource.java

@@ -25,6 +25,7 @@ import org.qortal.api.ApiExceptionFactory;
 import org.qortal.api.Security;
 import org.qortal.api.model.CrossChainCancelRequest;
 import org.qortal.api.model.CrossChainTradeSummary;
+import org.qortal.controller.tradebot.TradeBot;
 import org.qortal.crosschain.SupportedBlockchain;
 import org.qortal.crosschain.ACCT;
 import org.qortal.crosschain.AcctMode;
@@ -120,6 +121,8 @@ public class CrossChainResource {
 				crossChainTrades = crossChainTrades.subList(0, upperLimit);
 			}
 
+			crossChainTrades.stream().forEach(CrossChainResource::decorateTradeDataWithPresence);
+
 			return crossChainTrades;
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
@@ -151,7 +154,11 @@ public class CrossChainResource {
 			if (acct == null)
 				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 
-			return acct.populateTradeData(repository, atData);
+			CrossChainTradeData crossChainTradeData = acct.populateTradeData(repository, atData);
+
+			decorateTradeDataWithPresence(crossChainTradeData);
+
+			return crossChainTradeData;
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		}
@@ -486,4 +493,7 @@ public class CrossChainResource {
 		}
 	}
 
+	private static void decorateTradeDataWithPresence(CrossChainTradeData crossChainTradeData) {
+		TradeBot.getInstance().decorateTradeDataWithPresence(crossChainTradeData);
+	}
 }

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

@@ -98,7 +98,15 @@ public class GroupsResource {
 		ref = "reverse"
 	) @QueryParam("reverse") Boolean reverse) {
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			return repository.getGroupRepository().getAllGroups(limit, offset, reverse);
+			List<GroupData> allGroupData = repository.getGroupRepository().getAllGroups(limit, offset, reverse);
+			allGroupData.forEach(groupData -> {
+				try {
+					groupData.memberCount = repository.getGroupRepository().countGroupMembers(groupData.getGroupId());
+				} catch (DataException e) {
+					// Exclude memberCount for this group
+				}
+			});
+			return allGroupData;
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		}
@@ -150,7 +158,15 @@ public class GroupsResource {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			return repository.getGroupRepository().getGroupsWithMember(member);
+			List<GroupData> allGroupData = repository.getGroupRepository().getGroupsWithMember(member);
+			allGroupData.forEach(groupData -> {
+				try {
+					groupData.memberCount = repository.getGroupRepository().countGroupMembers(groupData.getGroupId());
+				} catch (DataException e) {
+					// Exclude memberCount for this group
+				}
+			});
+			return allGroupData;
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		}
@@ -177,6 +193,7 @@ public class GroupsResource {
 			if (groupData == null)
 				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.GROUP_UNKNOWN);
 
+			groupData.memberCount = repository.getGroupRepository().countGroupMembers(groupId);
 			return groupData;
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
@@ -922,4 +939,4 @@ public class GroupsResource {
 		}
 	}
 
-}
+}

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

@@ -20,6 +20,11 @@ import javax.ws.rs.*;
 import javax.ws.rs.core.Context;
 import javax.ws.rs.core.MediaType;
 
+import org.apache.logging.log4j.Level;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.core.config.Configuration;
+import org.apache.logging.log4j.core.config.LoggerConfig;
+import org.apache.logging.log4j.core.LoggerContext;
 import org.qortal.api.*;
 import org.qortal.api.model.ConnectedPeer;
 import org.qortal.api.model.PeersSummary;
@@ -61,7 +66,7 @@ public class PeersResource {
 		}
 	)
 	public List<ConnectedPeer> getPeers() {
-		return Network.getInstance().getConnectedPeers().stream().map(ConnectedPeer::new).collect(Collectors.toList());
+		return Network.getInstance().getImmutableConnectedPeers().stream().map(ConnectedPeer::new).collect(Collectors.toList());
 	}
 
 	@GET
@@ -127,9 +132,29 @@ public class PeersResource {
 		}
 	)
 	@SecurityRequirement(name = "apiKey")
-	public ExecuteProduceConsume.StatsSnapshot getEngineStats(@HeaderParam(Security.API_KEY_HEADER) String apiKey) {
+	public ExecuteProduceConsume.StatsSnapshot getEngineStats(@HeaderParam(Security.API_KEY_HEADER) String apiKey, @QueryParam("newLoggingLevel") Level newLoggingLevel) {
 		Security.checkApiCallAllowed(request);
 
+		if (newLoggingLevel != null) {
+			final LoggerContext ctx = (LoggerContext) LogManager.getContext(false);
+			final Configuration config = ctx.getConfiguration();
+
+			String epcClassName = "org.qortal.network.Network.NetworkProcessor";
+			LoggerConfig loggerConfig = config.getLoggerConfig(epcClassName);
+			LoggerConfig specificConfig = loggerConfig;
+
+			// We need a specific configuration for this logger,
+			// otherwise we would change the level of all other loggers
+			// having the original configuration as parent as well
+			if (!loggerConfig.getName().equals(epcClassName)) {
+				specificConfig = new LoggerConfig(epcClassName, newLoggingLevel, true);
+				specificConfig.setParent(loggerConfig);
+				config.addLogger(epcClassName, specificConfig);
+			}
+			specificConfig.setLevel(newLoggingLevel);
+			ctx.updateLoggers();
+		}
+
 		return Network.getInstance().getStatsSnapshot();
 	}
 
@@ -304,7 +329,7 @@ public class PeersResource {
 			PeerAddress peerAddress = PeerAddress.fromString(targetPeerAddress);
 			InetSocketAddress resolvedAddress = peerAddress.toSocketAddress();
 
-			List<Peer> peers = Network.getInstance().getHandshakedPeers();
+			List<Peer> peers = Network.getInstance().getImmutableHandshakedPeers();
 			Peer targetPeer = peers.stream().filter(peer -> peer.getResolvedAddress().equals(resolvedAddress)).findFirst().orElse(null);
 
 			if (targetPeer == null)
@@ -352,9 +377,9 @@ public class PeersResource {
 	public PeersSummary peersSummary() {
 		PeersSummary peersSummary = new PeersSummary();
 
-		List<Peer> connectedPeers = Network.getInstance().getConnectedPeers().stream().collect(Collectors.toList());
+		List<Peer> connectedPeers = Network.getInstance().getImmutableConnectedPeers().stream().collect(Collectors.toList());
 		for (Peer peer : connectedPeers) {
-			if (peer.isOutbound()) {
+			if (!peer.isOutbound()) {
 				peersSummary.inboundConnections++;
 			}
 			else {

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

@@ -74,7 +74,9 @@ public class RenderResource {
         Method method = Method.PUT;
         Compression compression = Compression.ZIP;
 
-        ArbitraryDataWriter arbitraryDataWriter = new ArbitraryDataWriter(Paths.get(directoryPath), null, Service.WEBSITE, null, method, compression);
+        ArbitraryDataWriter arbitraryDataWriter = new ArbitraryDataWriter(Paths.get(directoryPath),
+                null, Service.WEBSITE, null, method, compression,
+                null, null, null, null);
         try {
             arbitraryDataWriter.save();
         } catch (IOException | DataException | InterruptedException | MissingDataException e) {
@@ -136,34 +138,38 @@ public class RenderResource {
     @GET
     @Path("/signature/{signature}")
     @SecurityRequirement(name = "apiKey")
-    public HttpServletResponse getIndexBySignature(@PathParam("signature") String signature) {
+    public HttpServletResponse getIndexBySignature(@PathParam("signature") String signature,
+                                                   @QueryParam("theme") String theme) {
         Security.requirePriorAuthorization(request, signature, Service.WEBSITE, null);
-        return this.get(signature, ResourceIdType.SIGNATURE, null, "/", null, "/render/signature", true, true);
+        return this.get(signature, ResourceIdType.SIGNATURE, null, "/", null, "/render/signature", true, true, theme);
     }
 
     @GET
     @Path("/signature/{signature}/{path:.*}")
     @SecurityRequirement(name = "apiKey")
-    public HttpServletResponse getPathBySignature(@PathParam("signature") String signature, @PathParam("path") String inPath) {
+    public HttpServletResponse getPathBySignature(@PathParam("signature") String signature, @PathParam("path") String inPath,
+                                                  @QueryParam("theme") String theme) {
         Security.requirePriorAuthorization(request, signature, Service.WEBSITE, null);
-        return this.get(signature, ResourceIdType.SIGNATURE, null, inPath,null, "/render/signature", true, true);
+        return this.get(signature, ResourceIdType.SIGNATURE, null, inPath,null, "/render/signature", true, true, theme);
     }
 
     @GET
     @Path("/hash/{hash}")
     @SecurityRequirement(name = "apiKey")
-    public HttpServletResponse getIndexByHash(@PathParam("hash") String hash58, @QueryParam("secret") String secret58) {
+    public HttpServletResponse getIndexByHash(@PathParam("hash") String hash58, @QueryParam("secret") String secret58,
+                                              @QueryParam("theme") String theme) {
         Security.requirePriorAuthorization(request, hash58, Service.WEBSITE, null);
-        return this.get(hash58, ResourceIdType.FILE_HASH, Service.WEBSITE, "/", secret58, "/render/hash", true, false);
+        return this.get(hash58, ResourceIdType.FILE_HASH, Service.WEBSITE, "/", secret58, "/render/hash", true, false, theme);
     }
 
     @GET
     @Path("/hash/{hash}/{path:.*}")
     @SecurityRequirement(name = "apiKey")
     public HttpServletResponse getPathByHash(@PathParam("hash") String hash58, @PathParam("path") String inPath,
-                                             @QueryParam("secret") String secret58) {
+                                             @QueryParam("secret") String secret58,
+                                             @QueryParam("theme") String theme) {
         Security.requirePriorAuthorization(request, hash58, Service.WEBSITE, null);
-        return this.get(hash58, ResourceIdType.FILE_HASH, Service.WEBSITE, inPath, secret58, "/render/hash", true, false);
+        return this.get(hash58, ResourceIdType.FILE_HASH, Service.WEBSITE, inPath, secret58, "/render/hash", true, false, theme);
     }
 
     @GET
@@ -171,29 +177,35 @@ public class RenderResource {
     @SecurityRequirement(name = "apiKey")
     public HttpServletResponse getPathByName(@PathParam("service") Service service,
                                              @PathParam("name") String name,
-                                             @PathParam("path") String inPath) {
+                                             @PathParam("path") String inPath,
+                                             @QueryParam("theme") String theme) {
         Security.requirePriorAuthorization(request, name, service, null);
         String prefix = String.format("/render/%s", service);
-        return this.get(name, ResourceIdType.NAME, service, inPath, null, prefix, true, true);
+        return this.get(name, ResourceIdType.NAME, service, inPath, null, prefix, true, true, theme);
     }
 
     @GET
     @Path("{service}/{name}")
     @SecurityRequirement(name = "apiKey")
     public HttpServletResponse getIndexByName(@PathParam("service") Service service,
-                                              @PathParam("name") String name) {
+                                              @PathParam("name") String name,
+                                              @QueryParam("theme") String theme) {
         Security.requirePriorAuthorization(request, name, service, null);
         String prefix = String.format("/render/%s", service);
-        return this.get(name, ResourceIdType.NAME, service, "/", null, prefix, true, true);
+        return this.get(name, ResourceIdType.NAME, service, "/", null, prefix, true, true, theme);
     }
 
 
 
     private HttpServletResponse get(String resourceId, ResourceIdType resourceIdType, Service service, String inPath,
-                                    String secret58, String prefix, boolean usePrefix, boolean async) {
+                                    String secret58, String prefix, boolean usePrefix, boolean async, String theme) {
 
         ArbitraryDataRenderer renderer = new ArbitraryDataRenderer(resourceId, resourceIdType, service, inPath,
                 secret58, prefix, usePrefix, async, request, response, context);
+
+        if (theme != null) {
+            renderer.setTheme(theme);
+        }
         return renderer.render();
     }
 

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

@@ -638,7 +638,10 @@ public class TransactionsResource {
 		ApiError.BLOCKCHAIN_NEEDS_SYNC, ApiError.INVALID_SIGNATURE, ApiError.INVALID_DATA, ApiError.TRANSFORMATION_ERROR, ApiError.REPOSITORY_ISSUE
 	})
 	public String processTransaction(String rawBytes58) {
-		if (!Controller.getInstance().isUpToDate())
+		// Only allow a transaction to be processed if our latest block is less than 30 minutes old
+		// If older than this, we should first wait until the blockchain is synced
+		final Long minLatestBlockTimestamp = NTP.getTime() - (30 * 60 * 1000L);
+		if (!Controller.getInstance().isUpToDate(minLatestBlockTimestamp))
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCKCHAIN_NEEDS_SYNC);
 
 		byte[] rawBytes = Base58.decode(rawBytes58);

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

@@ -20,6 +20,7 @@ import org.eclipse.jetty.websocket.api.annotations.OnWebSocketMessage;
 import org.eclipse.jetty.websocket.api.annotations.WebSocket;
 import org.eclipse.jetty.websocket.servlet.WebSocketServletFactory;
 import org.qortal.controller.Controller;
+import org.qortal.controller.Synchronizer;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.transaction.PresenceTransactionData;
 import org.qortal.data.transaction.TransactionData;
@@ -99,13 +100,13 @@ public class PresenceWebSocket extends ApiWebSocket implements Listener {
 
 	@Override
 	public void listen(Event event) {
-		// We use NewBlockEvent as a proxy for 1-minute timer
-		if (!(event instanceof Controller.NewTransactionEvent) && !(event instanceof Controller.NewBlockEvent))
+		// We use Synchronizer.NewChainTipEvent as a proxy for 1-minute timer
+		if (!(event instanceof Controller.NewTransactionEvent) && !(event instanceof Synchronizer.NewChainTipEvent))
 			return;
 
 		removeOldEntries();
 
-		if (event instanceof Controller.NewBlockEvent)
+		if (event instanceof Synchronizer.NewChainTipEvent)
 			// We only wanted a chance to cull old entries
 			return;
 

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

@@ -23,6 +23,7 @@ import org.eclipse.jetty.websocket.api.annotations.WebSocket;
 import org.eclipse.jetty.websocket.servlet.WebSocketServletFactory;
 import org.qortal.api.model.CrossChainOfferSummary;
 import org.qortal.controller.Controller;
+import org.qortal.controller.Synchronizer;
 import org.qortal.crosschain.SupportedBlockchain;
 import org.qortal.crosschain.ACCT;
 import org.qortal.crosschain.AcctMode;
@@ -80,10 +81,10 @@ public class TradeOffersWebSocket extends ApiWebSocket implements Listener {
 
 	@Override
 	public void listen(Event event) {
-		if (!(event instanceof Controller.NewBlockEvent))
+		if (!(event instanceof Synchronizer.NewChainTipEvent))
 			return;
 
-		BlockData blockData = ((Controller.NewBlockEvent) event).getBlockData();
+		BlockData blockData = ((Synchronizer.NewChainTipEvent) event).getNewChainTip();
 
 		// Process any new info
 

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

@@ -0,0 +1,137 @@
+package org.qortal.api.websocket;
+
+import org.eclipse.jetty.websocket.api.Session;
+import org.eclipse.jetty.websocket.api.annotations.*;
+import org.eclipse.jetty.websocket.servlet.WebSocketServletFactory;
+import org.qortal.controller.Controller;
+import org.qortal.controller.tradebot.TradeBot;
+import org.qortal.data.network.TradePresenceData;
+import org.qortal.event.Event;
+import org.qortal.event.EventBus;
+import org.qortal.event.Listener;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+import java.io.IOException;
+import java.io.StringWriter;
+import java.util.*;
+
+@WebSocket
+@SuppressWarnings("serial")
+public class TradePresenceWebSocket extends ApiWebSocket implements Listener {
+
+	/** Map key is public key in base58, map value is trade presence */
+	private static final Map<String, TradePresenceData> currentEntries = Collections.synchronizedMap(new HashMap<>());
+
+	@Override
+	public void configure(WebSocketServletFactory factory) {
+		factory.register(TradePresenceWebSocket.class);
+
+		populateCurrentInfo();
+
+		EventBus.INSTANCE.addListener(this::listen);
+	}
+
+	@Override
+	public void listen(Event event) {
+		// XXX - Suggest we change this to something like Synchronizer.NewChainTipEvent?
+		// We use NewBlockEvent as a proxy for 1-minute timer
+		if (!(event instanceof TradeBot.TradePresenceEvent) && !(event instanceof Controller.NewBlockEvent))
+			return;
+
+		removeOldEntries();
+
+		if (event instanceof Controller.NewBlockEvent)
+			// We only wanted a chance to cull old entries
+			return;
+
+		TradePresenceData tradePresence = ((TradeBot.TradePresenceEvent) event).getTradePresenceData();
+
+		boolean somethingChanged = mergePresence(tradePresence);
+
+		if (!somethingChanged)
+			// nothing changed
+			return;
+
+		List<TradePresenceData> tradePresences = Collections.singletonList(tradePresence);
+
+		// Notify sessions
+		for (Session session : getSessions()) {
+			sendTradePresences(session, tradePresences);
+		}
+	}
+
+	@OnWebSocketConnect
+	@Override
+	public void onWebSocketConnect(Session session) {
+		Map<String, List<String>> queryParams = session.getUpgradeRequest().getParameterMap();
+
+		List<TradePresenceData> tradePresences;
+
+		synchronized (currentEntries) {
+			tradePresences = List.copyOf(currentEntries.values());
+		}
+
+		if (!sendTradePresences(session, tradePresences)) {
+			session.close(4002, "websocket issue");
+			return;
+		}
+
+		super.onWebSocketConnect(session);
+	}
+
+	@OnWebSocketClose
+	@Override
+	public void onWebSocketClose(Session session, int statusCode, String reason) {
+		// clean up
+		super.onWebSocketClose(session, statusCode, reason);
+	}
+
+	@OnWebSocketError
+	public void onWebSocketError(Session session, Throwable throwable) {
+		/* ignored */
+	}
+
+	@OnWebSocketMessage
+	public void onWebSocketMessage(Session session, String message) {
+		/* ignored */
+	}
+
+	private boolean sendTradePresences(Session session, List<TradePresenceData> tradePresences) {
+		try {
+			StringWriter stringWriter = new StringWriter();
+			marshall(stringWriter, tradePresences);
+
+			String output = stringWriter.toString();
+			session.getRemote().sendStringByFuture(output);
+		} catch (IOException e) {
+			// No output this time?
+			return false;
+		}
+
+		return true;
+	}
+
+	private static void populateCurrentInfo() {
+		// We want ALL trade presences
+		TradeBot.getInstance().getAllTradePresences().stream()
+				.forEach(TradePresenceWebSocket::mergePresence);
+	}
+
+	/** Merge trade presence into cache of current entries, returns true if cache was updated. */
+	private static boolean mergePresence(TradePresenceData tradePresence) {
+		// Put/replace for this publickey making sure we keep newest timestamp
+		String pubKey58 = Base58.encode(tradePresence.getPublicKey());
+
+		TradePresenceData newEntry = currentEntries.compute(pubKey58, (k, v) -> v == null || v.getTimestamp() < tradePresence.getTimestamp() ? tradePresence : v);
+
+		return newEntry == tradePresence;
+	}
+
+	private static void removeOldEntries() {
+		long now = NTP.getTime();
+
+		currentEntries.values().removeIf(v -> v.getTimestamp() < now);
+	}
+
+}

src/main/java/org/qortal/arbitrary/ArbitraryDataFile.java

@@ -53,7 +53,8 @@ public class ArbitraryDataFile {
     private static final Logger LOGGER = LogManager.getLogger(ArbitraryDataFile.class);
 
     public static final long MAX_FILE_SIZE = 500 * 1024 * 1024; // 500MiB
-    public static final int CHUNK_SIZE = 1 * 1024 * 1024; // 1MiB
+    protected static final int MAX_CHUNK_SIZE = 1 * 1024 * 1024; // 1MiB
+    public static final int CHUNK_SIZE = 512 * 1024; // 0.5MiB
     public static int SHORT_DIGEST_LENGTH = 8;
 
     protected Path filePath;
@@ -72,7 +73,6 @@ public class ArbitraryDataFile {
     }
 
     public ArbitraryDataFile(String hash58, byte[] signature) throws DataException {
-        this.createDataDirectory();
         this.filePath = ArbitraryDataFile.getOutputFilePath(hash58, signature, false);
         this.chunks = new ArrayList<>();
         this.hash58 = hash58;
@@ -93,10 +93,12 @@ public class ArbitraryDataFile {
         File outputFile = outputFilePath.toFile();
         try (FileOutputStream outputStream = new FileOutputStream(outputFile)) {
             outputStream.write(fileContent);
+            outputStream.close();
             this.filePath = outputFilePath;
             // Verify hash
-            if (!this.hash58.equals(this.digest58())) {
-                LOGGER.error("Hash {} does not match file digest {}", this.hash58, this.digest58());
+            String digest58 = this.digest58();
+            if (!this.hash58.equals(digest58)) {
+                LOGGER.error("Hash {} does not match file digest {} for signature: {}", this.hash58, digest58, Base58.encode(signature));
                 this.delete();
                 throw new DataException("Data file digest validation failed");
             }
@@ -110,6 +112,9 @@ public class ArbitraryDataFile {
     }
 
     public static ArbitraryDataFile fromHash(byte[] hash, byte[] signature) throws DataException {
+        if (hash == null) {
+            return null;
+        }
         return ArbitraryDataFile.fromHash58(Base58.encode(hash), signature);
     }
 
@@ -146,19 +151,6 @@ public class ArbitraryDataFile {
         return ArbitraryDataFile.fromPath(Paths.get(file.getPath()), signature);
     }
 
-    private boolean createDataDirectory() {
-        // Create the data directory if it doesn't exist
-        String dataPath = Settings.getInstance().getDataPath();
-        Path dataDirectory = Paths.get(dataPath);
-        try {
-            Files.createDirectories(dataDirectory);
-        } catch (IOException e) {
-            LOGGER.error("Unable to create data directory");
-            return false;
-        }
-        return true;
-    }
-
     private Path copyToDataDirectory(Path sourcePath, byte[] signature) throws DataException {
         if (this.hash58 == null || this.filePath == null) {
             return null;
@@ -366,6 +358,21 @@ public class ArbitraryDataFile {
         return false;
     }
 
+    public boolean delete(int attempts) {
+        // Keep trying to delete the data until it is deleted, or we reach 10 attempts
+        for (int i=0; i<attempts; i++) {
+            if (this.delete()) {
+                return true;
+            }
+            try {
+                Thread.sleep(1000L);
+            } catch (InterruptedException e) {
+                // Fall through to exit method
+            }
+        }
+        return false;
+    }
+
     public boolean deleteAllChunks() {
         boolean success = false;
 
@@ -473,6 +480,14 @@ public class ArbitraryDataFile {
 
             // Read the metadata
             List<byte[]> chunks = metadata.getChunks();
+
+            // If the chunks array is empty, then this resource has no chunks,
+            // so we must return false to avoid confusing the caller.
+            if (chunks.isEmpty()) {
+                return false;
+            }
+
+            // Otherwise, we need to check each chunk individually
             for (byte[] chunkHash : chunks) {
                 ArbitraryDataFileChunk chunk = ArbitraryDataFileChunk.fromHash(chunkHash, this.signature);
                 if (!chunk.exists()) {
@@ -771,6 +786,10 @@ public class ArbitraryDataFile {
         this.loadMetadata();
     }
 
+    public ArbitraryDataTransactionMetadata getMetadata() {
+        return this.metadata;
+    }
+
     @Override
     public String toString() {
         return this.shortHash58();

src/main/java/org/qortal/arbitrary/ArbitraryDataFileChunk.java

@@ -40,8 +40,8 @@ public class ArbitraryDataFileChunk extends ArbitraryDataFile {
         try {
             // Validate the file size (chunks have stricter limits)
             long fileSize = Files.size(this.filePath);
-            if (fileSize > CHUNK_SIZE) {
-                LOGGER.error(String.format("DataFileChunk is too large: %d bytes (max chunk size: %d bytes)", fileSize, CHUNK_SIZE));
+            if (fileSize > MAX_CHUNK_SIZE) {
+                LOGGER.error(String.format("DataFileChunk is too large: %d bytes (max chunk size: %d bytes)", fileSize, MAX_CHUNK_SIZE));
                 return ValidationResult.FILE_TOO_LARGE;
             }
 

src/main/java/org/qortal/arbitrary/ArbitraryDataRenderer.java

@@ -34,6 +34,7 @@ public class ArbitraryDataRenderer {
     private final String resourceId;
     private final ResourceIdType resourceIdType;
     private final Service service;
+    private String theme = "light";
     private String inPath;
     private final String secret58;
     private final String prefix;
@@ -77,7 +78,7 @@ public class ArbitraryDataRenderer {
                 // If async is requested, show a loading screen whilst build is in progress
                 if (async) {
                     arbitraryDataReader.loadAsynchronously(false, 10);
-                    return this.getLoadingResponse(service, resourceId);
+                    return this.getLoadingResponse(service, resourceId, theme);
                 }
 
                 // Otherwise, loop until we have data
@@ -119,7 +120,7 @@ public class ArbitraryDataRenderer {
                 byte[] data = Files.readAllBytes(Paths.get(filePath)); // TODO: limit file size that can be read into memory
                 HTMLParser htmlParser = new HTMLParser(resourceId, inPath, prefix, usePrefix, data);
                 htmlParser.addAdditionalHeaderTags();
-                response.addHeader("Content-Security-Policy", "default-src 'self' 'unsafe-inline'; media-src 'self' blob:");
+                response.addHeader("Content-Security-Policy", "default-src 'self' 'unsafe-inline' 'unsafe-eval'; media-src 'self' blob:; img-src 'self' data: blob:;");
                 response.setContentType(context.getMimeType(filename));
                 response.setContentLength(htmlParser.getData().length);
                 response.getOutputStream().write(htmlParser.getData());
@@ -128,7 +129,7 @@ public class ArbitraryDataRenderer {
                 // Regular file - can be streamed directly
                 File file = new File(filePath);
                 FileInputStream inputStream = new FileInputStream(file);
-                response.addHeader("Content-Security-Policy", "default-src 'self' 'unsafe-inline'; media-src 'self' blob:");
+                response.addHeader("Content-Security-Policy", "default-src 'self'");
                 response.setContentType(context.getMimeType(filename));
                 int bytesRead, length = 0;
                 byte[] buffer = new byte[10240];
@@ -171,7 +172,7 @@ public class ArbitraryDataRenderer {
         return userPath;
     }
 
-    private HttpServletResponse getLoadingResponse(Service service, String name) {
+    private HttpServletResponse getLoadingResponse(Service service, String name, String theme) {
         String responseString = "";
         URL url = Resources.getResource("loading/index.html");
         try {
@@ -180,6 +181,7 @@ public class ArbitraryDataRenderer {
             // Replace vars
             responseString = responseString.replace("%%SERVICE%%", service.toString());
             responseString = responseString.replace("%%NAME%%", name);
+            responseString = responseString.replace("%%THEME%%", theme);
 
         } catch (IOException e) {
             LOGGER.info("Unable to show loading screen: {}", e.getMessage());
@@ -210,4 +212,8 @@ public class ArbitraryDataRenderer {
         return indexFiles;
     }
 
+    public void setTheme(String theme) {
+        this.theme = theme;
+    }
+
 }

src/main/java/org/qortal/arbitrary/ArbitraryDataResource.java

@@ -3,6 +3,7 @@ package org.qortal.arbitrary;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.arbitrary.ArbitraryDataFile.ResourceIdType;
+import org.qortal.arbitrary.metadata.ArbitraryDataTransactionMetadata;
 import org.qortal.arbitrary.misc.Service;
 import org.qortal.controller.arbitrary.ArbitraryDataBuildManager;
 import org.qortal.controller.arbitrary.ArbitraryDataManager;
@@ -37,6 +38,7 @@ public class ArbitraryDataResource {
 
     private List<ArbitraryTransactionData> transactions;
     private ArbitraryTransactionData latestPutTransaction;
+    private ArbitraryTransactionData latestTransaction;
     private int layerCount;
     private Integer localChunkCount = null;
     private Integer totalChunkCount = null;
@@ -105,6 +107,33 @@ public class ArbitraryDataResource {
         return new ArbitraryResourceStatus(Status.DOWNLOADED, this.localChunkCount, this.totalChunkCount);
     }
 
+    public ArbitraryDataTransactionMetadata getLatestTransactionMetadata() {
+        this.fetchLatestTransaction();
+
+        if (latestTransaction != null) {
+            byte[] signature = latestTransaction.getSignature();
+            byte[] metadataHash = latestTransaction.getMetadataHash();
+            if (metadataHash == null) {
+                // This resource doesn't have metadata
+                return null;
+            }
+
+            try {
+                ArbitraryDataFile metadataFile = ArbitraryDataFile.fromHash(metadataHash, signature);
+                if (metadataFile.exists()) {
+                    ArbitraryDataTransactionMetadata transactionMetadata = new ArbitraryDataTransactionMetadata(metadataFile.getFilePath());
+                    transactionMetadata.read();
+                    return transactionMetadata;
+                }
+
+            } catch (DataException | IOException e) {
+                // Do nothing
+            }
+        }
+
+        return null;
+    }
+
     public boolean delete() {
         try {
             this.fetchTransactions();
@@ -306,6 +335,32 @@ public class ArbitraryDataResource {
 
             this.transactions = transactionDataList;
             this.layerCount = transactionDataList.size();
+
+        } catch (DataException e) {
+            LOGGER.info(String.format("Repository error when fetching transactions for resource %s: %s", this, e.getMessage()));
+        }
+    }
+
+    private void fetchLatestTransaction() {
+        if (this.latestTransaction != null) {
+            // Already fetched
+            return;
+        }
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+
+            // Get the most recent transaction
+            ArbitraryTransactionData latestTransaction = repository.getArbitraryRepository()
+                    .getLatestTransaction(this.resourceId, this.service, null, this.identifier);
+            if (latestTransaction == null) {
+                String message = String.format("Couldn't find transaction for name %s, service %s and identifier %s",
+                        this.resourceId, this.service, this.identifierString());
+                throw new DataException(message);
+            }
+            this.latestTransaction = latestTransaction;
+
+        } catch (DataException e) {
+            LOGGER.info(String.format("Repository error when fetching latest transaction for resource %s: %s", this, e.getMessage()));
         }
     }
 

src/main/java/org/qortal/arbitrary/ArbitraryDataTransactionBuilder.java

@@ -6,8 +6,9 @@ import org.qortal.arbitrary.exception.MissingDataException;
 import org.qortal.arbitrary.ArbitraryDataFile.ResourceIdType;
 import org.qortal.arbitrary.ArbitraryDataDiff.*;
 import org.qortal.arbitrary.metadata.ArbitraryDataMetadataPatch;
+import org.qortal.arbitrary.metadata.ArbitraryDataTransactionMetadata;
+import org.qortal.arbitrary.misc.Category;
 import org.qortal.arbitrary.misc.Service;
-import org.qortal.block.BlockChain;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.PaymentData;
 import org.qortal.data.transaction.ArbitraryTransactionData;
@@ -27,6 +28,7 @@ import java.io.IOException;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Objects;
 import java.util.Random;
 
 public class ArbitraryDataTransactionBuilder {
@@ -51,13 +53,20 @@ public class ArbitraryDataTransactionBuilder {
     private final String identifier;
     private final Repository repository;
 
+    // Metadata
+    private final String title;
+    private final String description;
+    private final List<String> tags;
+    private final Category category;
+
     private int chunkSize = ArbitraryDataFile.CHUNK_SIZE;
 
     private ArbitraryTransactionData arbitraryTransactionData;
     private ArbitraryDataFile arbitraryDataFile;
 
     public ArbitraryDataTransactionBuilder(Repository repository, String publicKey58, Path path, String name,
-                                           Method method, Service service, String identifier) {
+                                           Method method, Service service, String identifier,
+                                           String title, String description, List<String> tags, Category category) {
         this.repository = repository;
         this.publicKey58 = publicKey58;
         this.path = path;
@@ -70,6 +79,12 @@ public class ArbitraryDataTransactionBuilder {
             identifier = null;
         }
         this.identifier = identifier;
+
+        // Metadata (optional)
+        this.title = ArbitraryDataTransactionMetadata.limitTitle(title);
+        this.description = ArbitraryDataTransactionMetadata.limitDescription(description);
+        this.tags = ArbitraryDataTransactionMetadata.limitTags(tags);
+        this.category = category;
     }
 
     public void build() throws DataException {
@@ -108,6 +123,10 @@ public class ArbitraryDataTransactionBuilder {
             return Method.PUT;
         }
 
+        // Get existing metadata and see if it matches the new metadata
+        ArbitraryDataResource resource = new ArbitraryDataResource(this.name, ResourceIdType.NAME, this.service, this.identifier);
+        ArbitraryDataTransactionMetadata existingMetadata = resource.getLatestTransactionMetadata();
+
         try {
             // Check layer count
             int layerCount = reader.getLayerCount();
@@ -118,7 +137,23 @@ public class ArbitraryDataTransactionBuilder {
 
             // Check size of differences between this layer and previous layer
             ArbitraryDataCreatePatch patch = new ArbitraryDataCreatePatch(reader.getFilePath(), this.path, reader.getLatestSignature());
-            patch.create();
+            try {
+                patch.create();
+            }
+            catch (DataException | IOException e) {
+                // Handle matching states separately, as it's best to block transactions with duplicate states
+                if (e.getMessage().equals("Current state matches previous state. Nothing to do.")) {
+                    // Only throw an exception if the metadata is also identical, as well as the data
+                    if (this.isMetadataEqual(existingMetadata)) {
+                        throw new DataException(e.getMessage());
+                    }
+                }
+
+                LOGGER.info("Caught exception when creating patch: {}", e.getMessage());
+                LOGGER.info("Unable to load existing resource - using PUT to overwrite it.");
+                return Method.PUT;
+            }
+
             long diffSize = FilesystemUtils.getDirectorySize(patch.getFinalPath());
             long existingStateSize = FilesystemUtils.getDirectorySize(reader.getFilePath());
             double difference = (double) diffSize / (double) existingStateSize;
@@ -155,11 +190,8 @@ public class ArbitraryDataTransactionBuilder {
             // State is appropriate for a PATCH transaction
             return Method.PATCH;
         }
-        catch (IOException | DataException e) {
-            // Handle matching states separately, as it's best to block transactions with duplicate states
-            if (e.getMessage().equals("Current state matches previous state. Nothing to do.")) {
-                throw new DataException(e.getMessage());
-            }
+        catch (IOException e) {
+            // IMPORTANT: Don't catch DataException here, as they must be passed to the caller
             LOGGER.info("Caught exception: {}", e.getMessage());
             LOGGER.info("Unable to load existing resource - using PUT to overwrite it.");
             return Method.PUT;
@@ -200,7 +232,8 @@ public class ArbitraryDataTransactionBuilder {
             // FUTURE? Use zip compression for directories, or no compression for single files
             // Compression compression = (path.toFile().isDirectory()) ? Compression.ZIP : Compression.NONE;
 
-            ArbitraryDataWriter arbitraryDataWriter = new ArbitraryDataWriter(path, name, service, identifier, method, compression);
+            ArbitraryDataWriter arbitraryDataWriter = new ArbitraryDataWriter(path, name, service, identifier, method,
+                    compression, title, description, tags, category);
             try {
                 arbitraryDataWriter.setChunkSize(this.chunkSize);
                 arbitraryDataWriter.save();
@@ -253,6 +286,22 @@ public class ArbitraryDataTransactionBuilder {
 
     }
 
+    private boolean isMetadataEqual(ArbitraryDataTransactionMetadata existingMetadata) {
+        if (!Objects.equals(existingMetadata.getTitle(), this.title)) {
+            return false;
+        }
+        if (!Objects.equals(existingMetadata.getDescription(), this.description)) {
+            return false;
+        }
+        if (!Objects.equals(existingMetadata.getCategory(), this.category)) {
+            return false;
+        }
+        if (!Objects.equals(existingMetadata.getTags(), this.tags)) {
+            return false;
+        }
+        return true;
+    }
+
     public void computeNonce() throws DataException {
         if (this.arbitraryTransactionData == null) {
             throw new DataException("Arbitrary transaction data is required to compute nonce");

src/main/java/org/qortal/arbitrary/ArbitraryDataWriter.java

@@ -5,6 +5,7 @@ import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.arbitrary.exception.MissingDataException;
 import org.qortal.arbitrary.metadata.ArbitraryDataTransactionMetadata;
+import org.qortal.arbitrary.misc.Category;
 import org.qortal.arbitrary.misc.Service;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.transaction.ArbitraryTransactionData.*;
@@ -28,6 +29,10 @@ import java.nio.file.Paths;
 import java.security.InvalidAlgorithmParameterException;
 import java.security.InvalidKeyException;
 import java.security.NoSuchAlgorithmException;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Objects;
 
 public class ArbitraryDataWriter {
 
@@ -40,6 +45,12 @@ public class ArbitraryDataWriter {
     private final Method method;
     private final Compression compression;
 
+    // Metadata
+    private final String title;
+    private final String description;
+    private final List<String> tags;
+    private final Category category;
+
     private int chunkSize = ArbitraryDataFile.CHUNK_SIZE;
 
     private SecretKey aesKey;
@@ -50,7 +61,8 @@ public class ArbitraryDataWriter {
     private Path compressedPath;
     private Path encryptedPath;
 
-    public ArbitraryDataWriter(Path filePath, String name, Service service, String identifier, Method method, Compression compression) {
+    public ArbitraryDataWriter(Path filePath, String name, Service service, String identifier, Method method, Compression compression,
+                               String title, String description, List<String> tags, Category category) {
         this.filePath = filePath;
         this.name = name;
         this.service = service;
@@ -62,6 +74,12 @@ public class ArbitraryDataWriter {
             identifier = null;
         }
         this.identifier = identifier;
+
+        // Metadata (optional)
+        this.title = ArbitraryDataTransactionMetadata.limitTitle(title);
+        this.description = ArbitraryDataTransactionMetadata.limitDescription(description);
+        this.tags = ArbitraryDataTransactionMetadata.limitTags(tags);
+        this.category = category;
     }
 
     public void save() throws IOException, DataException, InterruptedException, MissingDataException {
@@ -258,12 +276,16 @@ public class ArbitraryDataWriter {
 
     private void createMetadataFile() throws IOException, DataException {
         // If we have at least one chunk, we need to create an index file containing their hashes
-        if (this.arbitraryDataFile.chunkCount() > 1) {
+        if (this.needsMetadataFile()) {
             // Create the JSON file
             Path chunkFilePath = Paths.get(this.workingPath.toString(), "metadata.json");
-            ArbitraryDataTransactionMetadata chunkMetadata = new ArbitraryDataTransactionMetadata(chunkFilePath);
-            chunkMetadata.setChunks(this.arbitraryDataFile.chunkHashList());
-            chunkMetadata.write();
+            ArbitraryDataTransactionMetadata metadata = new ArbitraryDataTransactionMetadata(chunkFilePath);
+            metadata.setTitle(this.title);
+            metadata.setDescription(this.description);
+            metadata.setTags(this.tags);
+            metadata.setCategory(this.category);
+            metadata.setChunks(this.arbitraryDataFile.chunkHashList());
+            metadata.write();
 
             // Create an ArbitraryDataFile from the JSON file (we don't have a signature yet)
             ArbitraryDataFile metadataFile = ArbitraryDataFile.fromPath(chunkFilePath, null);
@@ -308,6 +330,20 @@ public class ArbitraryDataWriter {
                     throw new DataException(String.format("Missing chunk %s in metadata file", Base58.encode(chunk)));
                 }
             }
+
+            // Check that the metadata is correct
+            if (!Objects.equals(metadata.getTitle(), this.title)) {
+                throw new DataException("Metadata mismatch: title");
+            }
+            if (!Objects.equals(metadata.getDescription(), this.description)) {
+                throw new DataException("Metadata mismatch: description");
+            }
+            if (!Objects.equals(metadata.getTags(), this.tags)) {
+                throw new DataException("Metadata mismatch: tags");
+            }
+            if (!Objects.equals(metadata.getCategory(), this.category)) {
+                throw new DataException("Metadata mismatch: category");
+            }
         }
     }
 
@@ -330,6 +366,16 @@ public class ArbitraryDataWriter {
         }
     }
 
+    private boolean needsMetadataFile() {
+        if (this.arbitraryDataFile.chunkCount() > 1) {
+            return true;
+        }
+        if (this.title != null || this.description != null || this.tags != null || this.category != null) {
+            return true;
+        }
+        return false;
+    }
+
 
     public ArbitraryDataFile getArbitraryDataFile() {
         return this.arbitraryDataFile;

src/main/java/org/qortal/arbitrary/metadata/ArbitraryDataTransactionMetadata.java

@@ -2,17 +2,28 @@ package org.qortal.arbitrary.metadata;
 
 import org.json.JSONArray;
 import org.json.JSONObject;
+import org.qortal.arbitrary.misc.Category;
 import org.qortal.repository.DataException;
 import org.qortal.utils.Base58;
 
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Iterator;
 import java.util.List;
 
 public class ArbitraryDataTransactionMetadata extends ArbitraryDataMetadata {
 
     private List<byte[]> chunks;
+    private String title;
+    private String description;
+    private List<String> tags;
+    private Category category;
+
+    private static int MAX_TITLE_LENGTH = 80;
+    private static int MAX_DESCRIPTION_LENGTH = 500;
+    private static int MAX_TAG_LENGTH = 20;
+    private static int MAX_TAGS_COUNT = 5;
 
     public ArbitraryDataTransactionMetadata(Path filePath) {
         super(filePath);
@@ -25,10 +36,37 @@ public class ArbitraryDataTransactionMetadata extends ArbitraryDataMetadata {
             throw new DataException("Transaction metadata JSON string is null");
         }
 
+        JSONObject metadata = new JSONObject(this.jsonString);
+
+        if (metadata.has("title")) {
+            this.title = metadata.getString("title");
+        }
+
+        if (metadata.has("description")) {
+            this.description = metadata.getString("description");
+        }
+
+        List<String> tagsList = new ArrayList<>();
+        if (metadata.has("tags")) {
+            JSONArray tags = metadata.getJSONArray("tags");
+            if (tags != null) {
+                for (int i=0; i<tags.length(); i++) {
+                    String tag = tags.getString(i);
+                    if (tag != null) {
+                        tagsList.add(tag);
+                    }
+                }
+            }
+            this.tags = tagsList;
+        }
+
+        if (metadata.has("category")) {
+            this.category = Category.uncategorizedValueOf(metadata.getString("category"));
+        }
+
         List<byte[]> chunksList = new ArrayList<>();
-        JSONObject cache = new JSONObject(this.jsonString);
-        if (cache.has("chunks")) {
-            JSONArray chunks = cache.getJSONArray("chunks");
+        if (metadata.has("chunks")) {
+            JSONArray chunks = metadata.getJSONArray("chunks");
             if (chunks != null) {
                 for (int i=0; i<chunks.length(); i++) {
                     String chunk = chunks.getString(i);
@@ -45,6 +83,26 @@ public class ArbitraryDataTransactionMetadata extends ArbitraryDataMetadata {
     protected void buildJson() {
         JSONObject outer = new JSONObject();
 
+        if (this.title != null && !this.title.isEmpty()) {
+            outer.put("title", this.title);
+        }
+
+        if (this.description != null && !this.description.isEmpty()) {
+            outer.put("description", this.description);
+        }
+
+        JSONArray tags = new JSONArray();
+        if (this.tags != null) {
+            for (String tag : this.tags) {
+                tags.put(tag);
+            }
+            outer.put("tags", tags);
+        }
+
+        if (this.category != null) {
+            outer.put("category", this.category.toString());
+        }
+
         JSONArray chunks = new JSONArray();
         if (this.chunks != null) {
             for (byte[] chunk : this.chunks) {
@@ -66,6 +124,38 @@ public class ArbitraryDataTransactionMetadata extends ArbitraryDataMetadata {
         return this.chunks;
     }
 
+    public void setTitle(String title) {
+        this.title = title;
+    }
+
+    public String getTitle() {
+        return this.title;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+
+    public String getDescription() {
+        return this.description;
+    }
+
+    public void setTags(List<String> tags) {
+        this.tags = tags;
+    }
+
+    public List<String> getTags() {
+        return this.tags;
+    }
+
+    public void setCategory(Category category) {
+        this.category = category;
+    }
+
+    public Category getCategory() {
+        return this.category;
+    }
+
     public boolean containsChunk(byte[] chunk) {
         for (byte[] c : this.chunks) {
             if (Arrays.equals(c, chunk)) {
@@ -75,4 +165,61 @@ public class ArbitraryDataTransactionMetadata extends ArbitraryDataMetadata {
         return false;
     }
 
+
+    // Static helper methods
+
+    public static String limitTitle(String title) {
+        if (title == null) {
+            return null;
+        }
+        if (title.isEmpty()) {
+            return null;
+        }
+
+        return title.substring(0, Math.min(title.length(), MAX_TITLE_LENGTH));
+    }
+
+    public static String limitDescription(String description) {
+        if (description == null) {
+            return null;
+        }
+        if (description.isEmpty()) {
+            return null;
+        }
+
+        return description.substring(0, Math.min(description.length(), MAX_DESCRIPTION_LENGTH));
+    }
+
+    public static List<String> limitTags(List<String> tags) {
+        if (tags == null) {
+            return null;
+        }
+
+        // Ensure tags list is mutable
+        List<String> mutableTags = new ArrayList<>(tags);
+
+        int tagCount = mutableTags.size();
+        if (tagCount == 0) {
+            return null;
+        }
+
+        // Remove tags over the limit
+        // This is cleaner than truncating, which results in malformed tags
+        // Also remove tags that are empty
+        Iterator iterator = mutableTags.iterator();
+        while (iterator.hasNext()) {
+            String tag = (String) iterator.next();
+            if (tag == null || tag.length() > MAX_TAG_LENGTH || tag.isEmpty()) {
+                iterator.remove();
+            }
+        }
+
+        // Limit the total number of tags
+        if (tagCount > MAX_TAGS_COUNT) {
+            mutableTags = mutableTags.subList(0, MAX_TAGS_COUNT);
+        }
+
+        return mutableTags;
+    }
+
 }

src/main/java/org/qortal/arbitrary/misc/Category.java

@@ -0,0 +1,81 @@
+package org.qortal.arbitrary.misc;
+
+public enum Category {
+    ART("Art and Design"),
+    AUTOMOTIVE("Automotive"),
+    BEAUTY("Beauty"),
+    BOOKS("Books and Reference"),
+    BUSINESS("Business"),
+    COMMUNICATIONS("Communications"),
+    CRYPTOCURRENCY("Cryptocurrency and Blockchain"),
+    CULTURE("Culture"),
+    DATING("Dating"),
+    DESIGN("Design"),
+    ENTERTAINMENT("Entertainment"),
+    EVENTS("Events"),
+    FAITH("Faith and Religion"),
+    FASHION("Fashion"),
+    FINANCE("Finance"),
+    FOOD("Food and Drink"),
+    GAMING("Gaming"),
+    GEOGRAPHY("Geography"),
+    HEALTH("Health"),
+    HISTORY("History"),
+    HOME("Home"),
+    KNOWLEDGE("Knowledge Share"),
+    LANGUAGE("Language"),
+    LIFESTYLE("Lifestyle"),
+    MANUFACTURING("Manufacturing"),
+    MAPS("Maps and Navigation"),
+    MUSIC("Music"),
+    NEWS("News"),
+    OTHER("Other"),
+    PETS("Pets"),
+    PHILOSOPHY("Philosophy"),
+    PHOTOGRAPHY("Photography"),
+    POLITICS("Politics"),
+    PRODUCE("Products and Services"),
+    PRODUCTIVITY("Productivity"),
+    PSYCHOLOGY("Psychology"),
+    QORTAL("Qortal"),
+    SCIENCE("Science"),
+    SELF_CARE("Self Care"),
+    SELF_SUFFICIENCY("Self-Sufficiency and Homesteading"),
+    SHOPPING("Shopping"),
+    SOCIAL("Social"),
+    SOFTWARE("Software"),
+    SPIRITUALITY("Spirituality"),
+    SPORTS("Sports"),
+    STORYTELLING("Storytelling"),
+    TECHNOLOGY("Technology"),
+    TOOLS("Tools"),
+    TRAVEL("Travel"),
+    UNCATEGORIZED("Uncategorized"),
+    VIDEO("Video"),
+    WEATHER("Weather");
+
+    private final String name;
+
+    Category(String name) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return this.name;
+    }
+
+    /**
+     * Same as valueOf() but with fallback to UNCATEGORIZED if there's no match
+     * @param name
+     * @return a Category (using UNCATEGORIZED if no match found)
+     */
+    public static Category uncategorizedValueOf(String name) {
+        try {
+            return Category.valueOf(name);
+        }
+        catch (IllegalArgumentException e) {
+            return Category.UNCATEGORIZED;
+        }
+    }
+
+}

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

@@ -551,7 +551,7 @@ public class QortalATAPI extends API {
 	 * <p>
 	 * Otherwise, assume B is a public key.
 	 */
-	private Account getAccountFromB(MachineState state) {
+	/*package*/ Account getAccountFromB(MachineState state) {
 		byte[] bBytes = this.getB(state);
 
 		if ((bBytes[0] == Crypto.ADDRESS_VERSION || bBytes[0] == Crypto.AT_ADDRESS_VERSION)

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

@@ -10,9 +10,11 @@ import org.ciyam.at.ExecutionException;
 import org.ciyam.at.FunctionData;
 import org.ciyam.at.IllegalFunctionCodeException;
 import org.ciyam.at.MachineState;
+import org.qortal.account.Account;
 import org.qortal.crosschain.Bitcoin;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.transaction.TransactionData;
+import org.qortal.repository.DataException;
 import org.qortal.settings.Settings;
 
 /**
@@ -160,6 +162,68 @@ public enum QortalFunctionCode {
 		protected void postCheckExecute(FunctionData functionData, MachineState state, short rawFunctionCode) throws ExecutionException {
 			convertAddressInB(Crypto.ADDRESS_VERSION, state);
 		}
+	},
+	/**
+	 * Returns account level of account in B.<br>
+	 * <tt>0x0520</tt><br>
+	 * B should contain either Qortal address or public key,<br>
+	 * e.g. as a result of calling function {@link org.ciyam.at.FunctionCode#PUT_ADDRESS_FROM_TX_IN_A_INTO_B}</code>.
+	 * <p></p>
+	 * Returns account level, or -1 if account unknown.
+	 * <p></p>
+	 * @see QortalATAPI#getAccountFromB(MachineState)
+	 */
+	GET_ACCOUNT_LEVEL_FROM_ACCOUNT_IN_B(0x0520, 0, true) {
+		@Override
+		protected void postCheckExecute(FunctionData functionData, MachineState state, short rawFunctionCode) throws ExecutionException {
+			QortalATAPI api = (QortalATAPI) state.getAPI();
+			Account account = api.getAccountFromB(state);
+
+			Integer accountLevel = null;
+
+			if (account != null) {
+				try {
+					accountLevel = account.getLevel();
+				} catch (DataException e) {
+					throw new RuntimeException("AT API unable to fetch account level?", e);
+				}
+			}
+
+			functionData.returnValue = accountLevel != null
+					? accountLevel.longValue()
+					: -1;
+		}
+	},
+	/**
+	 * Returns account's minted block count of account in B.<br>
+	 * <tt>0x0521</tt><br>
+	 * B should contain either Qortal address or public key,<br>
+	 * e.g. as a result of calling function {@link org.ciyam.at.FunctionCode#PUT_ADDRESS_FROM_TX_IN_A_INTO_B}</code>.
+	 * <p></p>
+	 * Returns account level, or -1 if account unknown.
+	 * <p></p>
+	 * @see QortalATAPI#getAccountFromB(MachineState)
+	 */
+	GET_BLOCKS_MINTED_FROM_ACCOUNT_IN_B(0x0521, 0, true) {
+		@Override
+		protected void postCheckExecute(FunctionData functionData, MachineState state, short rawFunctionCode) throws ExecutionException {
+			QortalATAPI api = (QortalATAPI) state.getAPI();
+			Account account = api.getAccountFromB(state);
+
+			Integer blocksMinted = null;
+
+			if (account != null) {
+				try {
+					blocksMinted = account.getBlocksMinted();
+				} catch (DataException e) {
+					throw new RuntimeException("AT API unable to fetch account's minted block count?", e);
+				}
+			}
+
+			functionData.returnValue = blocksMinted != null
+					? blocksMinted.longValue()
+					: -1;
+		}
 	};
 
 	public final short value;

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

@@ -8,13 +8,7 @@ import java.math.BigInteger;
 import java.math.RoundingMode;
 import java.text.DecimalFormat;
 import java.text.NumberFormat;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
+import java.util.*;
 import java.util.stream.Collectors;
 
 import org.apache.logging.log4j.Level;
@@ -28,7 +22,7 @@ import org.qortal.asset.Asset;
 import org.qortal.at.AT;
 import org.qortal.block.BlockChain.BlockTimingByHeight;
 import org.qortal.block.BlockChain.AccountLevelShareBin;
-import org.qortal.controller.Controller;
+import org.qortal.controller.OnlineAccountsManager;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.account.AccountBalanceData;
 import org.qortal.data.account.AccountData;
@@ -320,7 +314,7 @@ public class Block {
 		byte[] reference = parentBlockData.getSignature();
 
 		// Fetch our list of online accounts
-		List<OnlineAccountData> onlineAccounts = Controller.getInstance().getOnlineAccounts();
+		List<OnlineAccountData> onlineAccounts = OnlineAccountsManager.getInstance().getOnlineAccounts();
 		if (onlineAccounts.isEmpty()) {
 			LOGGER.error("No online accounts - not even our own?");
 			return null;
@@ -333,6 +327,11 @@ public class Block {
 				onlineAccountsTimestamp = onlineAccountData.getTimestamp();
 		}
 
+		// Load sorted list of reward share public keys into memory, so that the indexes can be obtained.
+		// This is up to 100x faster than querying each index separately. For 4150 reward share keys, it
+		// was taking around 5000ms to query individually, vs 50ms using this approach.
+		List<byte[]> allRewardSharePublicKeys = repository.getAccountRepository().getRewardSharePublicKeys();
+
 		// Map using index into sorted list of reward-shares as key
 		Map<Integer, OnlineAccountData> indexedOnlineAccounts = new HashMap<>();
 		for (OnlineAccountData onlineAccountData : onlineAccounts) {
@@ -340,7 +339,7 @@ public class Block {
 			if (onlineAccountData.getTimestamp() != onlineAccountsTimestamp)
 				continue;
 
-			Integer accountIndex = repository.getAccountRepository().getRewardShareIndex(onlineAccountData.getPublicKey());
+			Integer accountIndex = getRewardShareIndex(onlineAccountData.getPublicKey(), allRewardSharePublicKeys);
 			if (accountIndex == null)
 				// Online account (reward-share) with current timestamp but reward-share cancelled
 				continue;
@@ -988,10 +987,10 @@ public class Block {
 		byte[] onlineTimestampBytes = Longs.toByteArray(onlineTimestamp);
 
 		// If this block is much older than current online timestamp, then there's no point checking current online accounts
-		List<OnlineAccountData> currentOnlineAccounts = onlineTimestamp < NTP.getTime() - Controller.ONLINE_TIMESTAMP_MODULUS
+		List<OnlineAccountData> currentOnlineAccounts = onlineTimestamp < NTP.getTime() - OnlineAccountsManager.ONLINE_TIMESTAMP_MODULUS
 				? null
-				: Controller.getInstance().getOnlineAccounts();
-		List<OnlineAccountData> latestBlocksOnlineAccounts = Controller.getInstance().getLatestBlocksOnlineAccounts();
+				: OnlineAccountsManager.getInstance().getOnlineAccounts();
+		List<OnlineAccountData> latestBlocksOnlineAccounts = OnlineAccountsManager.getInstance().getLatestBlocksOnlineAccounts();
 
 		// Extract online accounts' timestamp signatures from block data
 		List<byte[]> onlineAccountsSignatures = BlockTransformer.decodeTimestampSignatures(this.blockData.getOnlineAccountsSignatures());
@@ -1369,7 +1368,7 @@ public class Block {
 		postBlockTidy();
 
 		// Give Controller our cached, valid online accounts data (if any) to help reduce CPU load for next block
-		Controller.getInstance().pushLatestBlocksOnlineAccounts(this.cachedValidOnlineAccounts);
+		OnlineAccountsManager.getInstance().pushLatestBlocksOnlineAccounts(this.cachedValidOnlineAccounts);
 
 		// Log some debugging info relating to the block weight calculation
 		this.logDebugInfo();
@@ -1588,7 +1587,7 @@ public class Block {
 		postBlockTidy();
 
 		// Remove any cached, valid online accounts data from Controller
-		Controller.getInstance().popLatestBlocksOnlineAccounts();
+		OnlineAccountsManager.getInstance().popLatestBlocksOnlineAccounts();
 	}
 
 	protected void orphanTransactionsFromBlock() throws DataException {
@@ -2029,6 +2028,26 @@ public class Block {
 		this.repository.getAccountRepository().tidy();
 	}
 
+	// Utils
+
+	/**
+	 * Find index of rewardSharePublicKey in list of rewardSharePublicKeys
+	 *
+	 * @param rewardSharePublicKey - the key to query
+	 * @param rewardSharePublicKeys - a sorted list of keys
+	 * @return - the index of the key, or null if not found
+	 */
+	private static Integer getRewardShareIndex(byte[] rewardSharePublicKey, List<byte[]> rewardSharePublicKeys) {
+		int index = 0;
+		for (byte[] publicKey : rewardSharePublicKeys) {
+			if (Arrays.equals(rewardSharePublicKey, publicKey)) {
+				return index;
+			}
+			index++;
+		}
+		return null;
+	}
+
 	private void logDebugInfo() {
 		try {
 			// Avoid calculations if possible. We have to check against INFO here, since Level.isMoreSpecificThan() confusingly uses <= rather than just <

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

@@ -73,9 +73,13 @@ public class BlockChain {
 	}
 
 	// Custom transaction fees
-	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
-	private long nameRegistrationUnitFee;
-	private long nameRegistrationUnitFeeTimestamp;
+	/** Unit fees by transaction timestamp */
+	public static class UnitFeesByTimestamp {
+		public long timestamp;
+		@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+		public long fee;
+	}
+	private List<UnitFeesByTimestamp> nameRegistrationUnitFees;
 
 	/** Map of which blockchain features are enabled when (height/timestamp) */
 	@XmlJavaTypeAdapter(StringLongMapXmlAdapter.class)
@@ -306,16 +310,6 @@ public class BlockChain {
 		return this.maxBlockSize;
 	}
 
-	// Custom transaction fees
-	public long getNameRegistrationUnitFee() {
-		return this.nameRegistrationUnitFee;
-	}
-
-	public long getNameRegistrationUnitFeeTimestamp() {
-		// FUTURE: we could use a separate structure to indicate fee adjustments for different transaction types
-		return this.nameRegistrationUnitFeeTimestamp;
-	}
-
 	/** Returns true if approval-needing transaction types require a txGroupId other than NO_GROUP. */
 	public boolean getRequireGroupForApproval() {
 		return this.requireGroupForApproval;
@@ -430,6 +424,15 @@ public class BlockChain {
 		throw new IllegalStateException(String.format("No block timing info available for height %d", ourHeight));
 	}
 
+	public long getNameRegistrationUnitFeeAtTimestamp(long ourTimestamp) {
+		for (int i = nameRegistrationUnitFees.size() - 1; i >= 0; --i)
+			if (nameRegistrationUnitFees.get(i).timestamp <= ourTimestamp)
+				return nameRegistrationUnitFees.get(i).fee;
+
+		// Default to system-wide unit fee
+		return this.getUnitFee();
+	}
+
 	/** Validate blockchain config read from JSON */
 	private void validateConfig() {
 		if (this.genesisInfo == null)

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

@@ -110,7 +110,7 @@ public class BlockMinter extends Thread {
 					continue;
 
 				// No online accounts? (e.g. during startup)
-				if (Controller.getInstance().getOnlineAccounts().isEmpty())
+				if (OnlineAccountsManager.getInstance().getOnlineAccounts().isEmpty())
 					continue;
 
 				List<MintingAccountData> mintingAccountsData = repository.getAccountRepository().getMintingAccounts();
@@ -148,7 +148,8 @@ public class BlockMinter extends Thread {
 					}
 				}
 
-				List<Peer> peers = Network.getInstance().getHandshakedPeers();
+				// Needs a mutable copy of the unmodifiableList
+				List<Peer> peers = new ArrayList<>(Network.getInstance().getImmutableHandshakedPeers());
 				BlockData lastBlockData = blockRepository.getLastBlock();
 
 				// Disregard peers that have "misbehaved" recently
@@ -218,7 +219,7 @@ public class BlockMinter extends Thread {
 					// The last iteration found a higher weight block in the network, so sleep for a while
 					// to allow is to sync the higher weight chain. We are sleeping here rather than when
 					// detected as we don't want to hold the blockchain lock open.
-					LOGGER.info("Sleeping for 10 seconds...");
+					LOGGER.debug("Sleeping for 10 seconds...");
 					Thread.sleep(10 * 1000L);
 				}
 
@@ -327,13 +328,13 @@ public class BlockMinter extends Thread {
 							// If less than 30 seconds has passed since first detection the higher weight chain,
 							// we should skip our block submission to give us the opportunity to sync to the better chain
 							if (NTP.getTime() - timeOfLastLowWeightBlock < 30*1000L) {
-								LOGGER.info("Higher weight chain found in peers, so not signing a block this round");
-								LOGGER.info("Time since detected: {}", NTP.getTime() - timeOfLastLowWeightBlock);
+								LOGGER.debug("Higher weight chain found in peers, so not signing a block this round");
+								LOGGER.debug("Time since detected: {}ms", NTP.getTime() - timeOfLastLowWeightBlock);
 								continue;
 							}
 							else {
 								// More than 30 seconds have passed, so we should submit our block candidate anyway.
-								LOGGER.info("More than 30 seconds passed, so proceeding to submit block candidate...");
+								LOGGER.debug("More than 30 seconds passed, so proceeding to submit block candidate...");
 							}
 						}
 						else {
@@ -478,7 +479,7 @@ public class BlockMinter extends Thread {
 			throw new DataException("Ignoring attempt to mint testing block for non-test chain!");
 
 		// Ensure mintingAccount is 'online' so blocks can be minted
-		Controller.getInstance().ensureTestingAccountsOnline(mintingAndOnlineAccounts);
+		OnlineAccountsManager.getInstance().ensureTestingAccountsOnline(mintingAndOnlineAccounts);
 
 		PrivateKeyAccount mintingAccount = mintingAndOnlineAccounts[0];
 
@@ -544,7 +545,7 @@ public class BlockMinter extends Thread {
 		}
 		NumberFormat formatter = new DecimalFormat("0.###E0");
 
-		List<Peer> peers = Network.getInstance().getHandshakedPeers();
+		List<Peer> peers = Network.getInstance().getImmutableHandshakedPeers();
 		// Loop through handshaked peers and check for any new block candidates
 		for (Peer peer : peers) {
 			if (peer.getCommonBlockData() != null && peer.getCommonBlockData().getCommonBlockSummary() != null) {

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

@@ -29,10 +29,6 @@ import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.bouncycastle.jce.provider.BouncyCastleProvider;
 import org.bouncycastle.jsse.provider.BouncyCastleJsseProvider;
-import com.google.common.primitives.Longs;
-import org.qortal.account.Account;
-import org.qortal.account.PrivateKeyAccount;
-import org.qortal.account.PublicKeyAccount;
 import org.qortal.api.ApiService;
 import org.qortal.api.DomainMapService;
 import org.qortal.api.GatewayService;
@@ -43,11 +39,8 @@ import org.qortal.controller.arbitrary.*;
 import org.qortal.controller.repository.PruneManager;
 import org.qortal.controller.repository.NamesDatabaseIntegrityCheck;
 import org.qortal.controller.tradebot.TradeBot;
-import org.qortal.data.account.MintingAccountData;
-import org.qortal.data.account.RewardShareData;
 import org.qortal.data.block.BlockData;
 import org.qortal.data.block.BlockSummaryData;
-import org.qortal.data.network.OnlineAccountData;
 import org.qortal.data.network.PeerChainTipData;
 import org.qortal.data.network.PeerData;
 import org.qortal.data.transaction.ChatTransactionData;
@@ -65,7 +58,7 @@ import org.qortal.repository.hsqldb.HSQLDBRepositoryFactory;
 import org.qortal.settings.Settings;
 import org.qortal.transaction.Transaction;
 import org.qortal.transaction.Transaction.TransactionType;
-import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.TransformationException;
 import org.qortal.utils.*;
 
 public class Controller extends Thread {
@@ -88,23 +81,6 @@ 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 int MAX_INCOMING_TRANSACTIONS = 5000;
-
-	/** Minimum time before considering an invalid unconfirmed transaction as "stale" */
-	public static final long INVALID_TRANSACTION_STALE_TIMEOUT = 30 * 60 * 1000L; // ms
-	/** Minimum frequency to re-request stale unconfirmed transactions from peers, to recheck validity */
-	public static final long INVALID_TRANSACTION_RECHECK_INTERVAL = 60 * 60 * 1000L; // ms\
-	/** Minimum frequency to re-request expired unconfirmed transactions from peers, to recheck validity
-	 * This mainly exists to stop expired transactions from bloating the list */
-	public static final long EXPIRED_TRANSACTION_RECHECK_INTERVAL = 10 * 60 * 1000L; // ms
-
-	// To do with online accounts list
-	private static final long ONLINE_ACCOUNTS_TASKS_INTERVAL = 10 * 1000L; // ms
-	private static final long ONLINE_ACCOUNTS_BROADCAST_INTERVAL = 1 * 60 * 1000L; // ms
-	public static final long ONLINE_TIMESTAMP_MODULUS = 5 * 60 * 1000L;
-	private static final long LAST_SEEN_EXPIRY_PERIOD = (ONLINE_TIMESTAMP_MODULUS * 2) + (1 * 60 * 1000L);
-	/** How many (latest) blocks' worth of online accounts we cache */
-	private static final int MAX_BLOCKS_CACHED_ONLINE_ACCOUNTS = 2;
 
 	private static volatile boolean isStopping = false;
 	private static BlockMinter blockMinter = null;
@@ -136,25 +112,12 @@ public class Controller extends Thread {
 	private long ntpCheckTimestamp = startTime; // ms
 	private long deleteExpiredTimestamp = startTime + DELETE_EXPIRED_INTERVAL; // ms
 
-	private long onlineAccountsTasksTimestamp = startTime + ONLINE_ACCOUNTS_TASKS_INTERVAL; // ms
-
 	/** Whether we can mint new blocks, as reported by BlockMinter. */
 	private volatile boolean isMintingPossible = false;
 
-	/** List of incoming transaction that are in the import queue */
-	private List<TransactionData> incomingTransactions = Collections.synchronizedList(new ArrayList<>());
-
-	/** List of recent invalid unconfirmed transactions */
-	private Map<String, Long> invalidUnconfirmedTransactions = Collections.synchronizedMap(new HashMap<>());
-
 	/** Lock for only allowing one blockchain-modifying codepath at a time. e.g. synchronization or newly minted block. */
 	private final ReentrantLock blockchainLock = new ReentrantLock();
 
-	/** Cache of current 'online accounts' */
-	List<OnlineAccountData> onlineAccounts = new ArrayList<>();
-	/** Cache of latest blocks' online accounts */
-	Deque<List<OnlineAccountData>> latestBlocksOnlineAccounts = new ArrayDeque<>(MAX_BLOCKS_CACHED_ONLINE_ACCOUNTS);
-
 	// Stats
 	@XmlAccessorType(XmlAccessType.FIELD)
 	public static class StatsSnapshot {
@@ -207,6 +170,15 @@ public class Controller extends Thread {
 		}
 		public GetArbitraryDataFileListMessageStats getArbitraryDataFileListMessageStats = new GetArbitraryDataFileListMessageStats();
 
+		public static class GetArbitraryMetadataMessageStats {
+			public AtomicLong requests = new AtomicLong();
+			public AtomicLong unknownFiles = new AtomicLong();
+
+			public GetArbitraryMetadataMessageStats() {
+			}
+		}
+		public GetArbitraryMetadataMessageStats getArbitraryMetadataMessageStats = new GetArbitraryMetadataMessageStats();
+
 		public AtomicLong latestBlocksCacheRefills = new AtomicLong();
 
 		public StatsSnapshot() {
@@ -458,6 +430,12 @@ public class Controller extends Thread {
 		ArbitraryDataStorageManager.getInstance().start();
 		ArbitraryDataRenderManager.getInstance().start();
 
+		LOGGER.info("Starting online accounts manager");
+		OnlineAccountsManager.getInstance().start();
+
+		LOGGER.info("Starting transaction importer");
+		TransactionImporter.getInstance().start();
+
 		// Auto-update service?
 		if (Settings.getInstance().isAutoUpdateEnabled()) {
 			LOGGER.info("Starting auto-update");
@@ -555,11 +533,6 @@ public class Controller extends Thread {
 					}
 				}
 
-				// Process incoming transactions queue
-				processIncomingTransactionsQueue();
-				// Clean up invalid incoming transactions list
-				cleanupInvalidTransactionsList(now);
-
 				// Clean up arbitrary data request cache
 				ArbitraryDataManager.getInstance().cleanupRequestCache(now);
 				// Clean up arbitrary data queues and lists
@@ -601,15 +574,20 @@ public class Controller extends Thread {
 								MessageType.INFO);
 
 					LOGGER.info("Starting scheduled repository maintenance. This can take a while...");
-					try (final Repository repository = RepositoryManager.getRepository()) {
+					int attempts = 0;
+					while (attempts <= 5) {
+						try (final Repository repository = RepositoryManager.getRepository()) {
+							attempts++;
 
-						// Timeout if the database isn't ready for maintenance after 60 seconds
-						long timeout = 60 * 1000L;
-						repository.performPeriodicMaintenance(timeout);
+							// Timeout if the database isn't ready for maintenance after 60 seconds
+							long timeout = 60 * 1000L;
+							repository.performPeriodicMaintenance(timeout);
 
-						LOGGER.info("Scheduled repository maintenance completed");
-					} catch (DataException | TimeoutException e) {
-						LOGGER.error("Scheduled repository maintenance failed", e);
+							LOGGER.info("Scheduled repository maintenance completed");
+							break;
+						} catch (DataException | TimeoutException e) {
+							LOGGER.info("Scheduled repository maintenance failed. Retrying up to 5 times...", e);
+						}
 					}
 
 					// Get a new random interval
@@ -628,12 +606,6 @@ public class Controller extends Thread {
 					deleteExpiredTimestamp = now + DELETE_EXPIRED_INTERVAL;
 					deleteExpiredTransactions();
 				}
-
-				// Perform tasks to do with managing online accounts list
-				if (now >= onlineAccountsTasksTimestamp) {
-					onlineAccountsTasksTimestamp = now + ONLINE_ACCOUNTS_TASKS_INTERVAL;
-					performOnlineAccountsTasks();
-				}
 			}
 		} catch (InterruptedException e) {
 			// Clear interrupted flag so we can shutdown trim threads
@@ -709,7 +681,7 @@ public class Controller extends Thread {
 	public static final Predicate<Peer> hasInferiorChainTip = peer -> {
 		final PeerChainTipData peerChainTipData = peer.getChainTipData();
 		final List<ByteArray> inferiorChainTips = Synchronizer.getInstance().inferiorChainSignatures;
-		return peerChainTipData == null || peerChainTipData.getLastBlockSignature() == null || inferiorChainTips.contains(new ByteArray(peerChainTipData.getLastBlockSignature()));
+		return peerChainTipData == null || peerChainTipData.getLastBlockSignature() == null || inferiorChainTips.contains(ByteArray.wrap(peerChainTipData.getLastBlockSignature()));
 	};
 
 	public static final Predicate<Peer> hasOldVersion = peer -> {
@@ -751,7 +723,7 @@ public class Controller extends Thread {
 			return;
 		}
 
-		final int numberOfPeers = Network.getInstance().getHandshakedPeers().size();
+		final int numberOfPeers = Network.getInstance().getImmutableHandshakedPeers().size();
 
 		final int height = getChainHeight();
 
@@ -760,17 +732,25 @@ public class Controller extends Thread {
 
 		String actionText;
 
+		// Use a more tolerant latest block timestamp in the isUpToDate() calls below to reduce misleading statuses.
+		// Any block in the last 30 minutes is considered "up to date" for the purposes of displaying statuses.
+		final Long minLatestBlockTimestamp = NTP.getTime() - (30 * 60 * 1000L);
+
 		synchronized (Synchronizer.getInstance().syncLock) {
 			if (this.isMintingPossible) {
 				actionText = Translator.INSTANCE.translate("SysTray", "MINTING_ENABLED");
 				SysTray.getInstance().setTrayIcon(2);
 			}
-			else if (Synchronizer.getInstance().isSynchronizing()) {
+			else if (numberOfPeers < Settings.getInstance().getMinBlockchainPeers()) {
+				actionText = Translator.INSTANCE.translate("SysTray", "CONNECTING");
+				SysTray.getInstance().setTrayIcon(3);
+			}
+			else if (!this.isUpToDate(minLatestBlockTimestamp) && Synchronizer.getInstance().isSynchronizing()) {
 				actionText = String.format("%s - %d%%", Translator.INSTANCE.translate("SysTray", "SYNCHRONIZING_BLOCKCHAIN"), Synchronizer.getInstance().getSyncPercent());
 				SysTray.getInstance().setTrayIcon(3);
 			}
-			else if (numberOfPeers < Settings.getInstance().getMinBlockchainPeers()) {
-				actionText = Translator.INSTANCE.translate("SysTray", "CONNECTING");
+			else if (!this.isUpToDate(minLatestBlockTimestamp)) {
+				actionText = String.format("%s", Translator.INSTANCE.translate("SysTray", "SYNCHRONIZING_BLOCKCHAIN"));
 				SysTray.getInstance().setTrayIcon(3);
 			}
 			else {
@@ -822,120 +802,6 @@ public class Controller extends Thread {
 		}
 	}
 
-	// Incoming transactions queue
-
-	private boolean incomingTransactionQueueContains(byte[] signature) {
-		synchronized (incomingTransactions) {
-			return incomingTransactions.stream().anyMatch(t -> Arrays.equals(t.getSignature(), signature));
-		}
-	}
-
-	private void removeIncomingTransaction(byte[] signature) {
-		incomingTransactions.removeIf(t -> Arrays.equals(t.getSignature(), signature));
-	}
-
-	private void processIncomingTransactionsQueue() {
-		if (this.incomingTransactions.size() == 0) {
-			// Don't bother locking if there are no new transactions to process
-			return;
-		}
-
-		if (Synchronizer.getInstance().isSyncRequested() || Synchronizer.getInstance().isSynchronizing()) {
-			// Prioritize syncing, and don't attempt to lock
-			return;
-		}
-
-		try {
-			ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
-			if (!blockchainLock.tryLock(2, TimeUnit.SECONDS)) {
-				LOGGER.trace(() -> String.format("Too busy to process incoming transactions queue"));
-				return;
-			}
-		} catch (InterruptedException e) {
-			LOGGER.info("Interrupted when trying to acquire blockchain lock");
-			return;
-		}
-
-		try (final Repository repository = RepositoryManager.getRepository()) {
-			LOGGER.debug("Processing incoming transactions queue (size {})...", this.incomingTransactions.size());
-
-			// Take a copy of incomingTransactions so we can release the lock
-			List<TransactionData>incomingTransactionsCopy = new ArrayList<>(this.incomingTransactions);
-
-			// Iterate through incoming transactions list
-			Iterator iterator = incomingTransactionsCopy.iterator();
-			while (iterator.hasNext()) {
-				if (isStopping) {
-					return;
-				}
-
-				if (Synchronizer.getInstance().isSyncRequestPending()) {
-					LOGGER.debug("Breaking out of transaction processing loop with {} remaining, because a sync request is pending", incomingTransactionsCopy.size());
-					return;
-				}
-
-				TransactionData transactionData = (TransactionData) iterator.next();
-				Transaction transaction = Transaction.fromData(repository, transactionData);
-
-				// Check signature
-				if (!transaction.isSignatureValid()) {
-					LOGGER.trace(() -> String.format("Ignoring %s transaction %s with invalid signature", transactionData.getType().name(), Base58.encode(transactionData.getSignature())));
-					removeIncomingTransaction(transactionData.getSignature());
-					continue;
-				}
-
-				ValidationResult validationResult = transaction.importAsUnconfirmed();
-
-				if (validationResult == ValidationResult.TRANSACTION_ALREADY_EXISTS) {
-					LOGGER.trace(() -> String.format("Ignoring existing transaction %s", Base58.encode(transactionData.getSignature())));
-					removeIncomingTransaction(transactionData.getSignature());
-					continue;
-				}
-
-				if (validationResult == ValidationResult.NO_BLOCKCHAIN_LOCK) {
-					LOGGER.trace(() -> String.format("Couldn't lock blockchain to import unconfirmed transaction", Base58.encode(transactionData.getSignature())));
-					removeIncomingTransaction(transactionData.getSignature());
-					continue;
-				}
-
-				if (validationResult != ValidationResult.OK) {
-					final String signature58 = Base58.encode(transactionData.getSignature());
-					LOGGER.trace(() -> String.format("Ignoring invalid (%s) %s transaction %s", validationResult.name(), transactionData.getType().name(), signature58));
-					Long now = NTP.getTime();
-					if (now != null && now - transactionData.getTimestamp() > INVALID_TRANSACTION_STALE_TIMEOUT) {
-						Long expiryLength = INVALID_TRANSACTION_RECHECK_INTERVAL;
-						if (validationResult == ValidationResult.TIMESTAMP_TOO_OLD) {
-							// Use shorter recheck interval for expired transactions
-							expiryLength = EXPIRED_TRANSACTION_RECHECK_INTERVAL;
-						}
-						Long expiry = now + expiryLength;
-						LOGGER.debug("Adding stale invalid transaction {} to invalidUnconfirmedTransactions...", signature58);
-						// Invalid, unconfirmed transaction has become stale - add to invalidUnconfirmedTransactions so that we don't keep requesting it
-						invalidUnconfirmedTransactions.put(signature58, expiry);
-					}
-					removeIncomingTransaction(transactionData.getSignature());
-					continue;
-				}
-
-				LOGGER.debug(() -> String.format("Imported %s transaction %s", transactionData.getType().name(), Base58.encode(transactionData.getSignature())));
-				removeIncomingTransaction(transactionData.getSignature());
-			}
-		} catch (DataException e) {
-			LOGGER.error(String.format("Repository issue while processing incoming transactions", e));
-		} finally {
-			LOGGER.debug("Finished processing incoming transactions queue");
-			blockchainLock.unlock();
-		}
-	}
-
-	private void cleanupInvalidTransactionsList(Long now) {
-		if (now == null) {
-			return;
-		}
-		// Periodically remove invalid unconfirmed transactions from the list, so that they can be fetched again
-		invalidUnconfirmedTransactions.entrySet().removeIf(entry -> entry.getValue() == null || entry.getValue() < now);
-	}
-
 
 	// Shutdown
 
@@ -964,6 +830,12 @@ public class Controller extends Thread {
 				ArbitraryDataStorageManager.getInstance().shutdown();
 				ArbitraryDataRenderManager.getInstance().shutdown();
 
+				LOGGER.info("Shutting down online accounts manager");
+				OnlineAccountsManager.getInstance().shutdown();
+
+				LOGGER.info("Shutting down transaction importer");
+				TransactionImporter.getInstance().shutdown();
+
 				if (blockMinter != null) {
 					LOGGER.info("Shutting down block minter");
 					blockMinter.shutdown();
@@ -1246,10 +1118,6 @@ public class Controller extends Thread {
 				onNetworkGetBlockMessage(peer, message);
 				break;
 
-			case TRANSACTION:
-				onNetworkTransactionMessage(peer, message);
-				break;
-
 			case GET_BLOCK_SUMMARIES:
 				onNetworkGetBlockSummariesMessage(peer, message);
 				break;
@@ -1263,23 +1131,35 @@ public class Controller extends Thread {
 				break;
 
 			case GET_TRANSACTION:
-				onNetworkGetTransactionMessage(peer, message);
+				TransactionImporter.getInstance().onNetworkGetTransactionMessage(peer, message);
+				break;
+
+			case TRANSACTION:
+				TransactionImporter.getInstance().onNetworkTransactionMessage(peer, message);
 				break;
 
 			case GET_UNCONFIRMED_TRANSACTIONS:
-				onNetworkGetUnconfirmedTransactionsMessage(peer, message);
+				TransactionImporter.getInstance().onNetworkGetUnconfirmedTransactionsMessage(peer, message);
 				break;
 
 			case TRANSACTION_SIGNATURES:
-				onNetworkTransactionSignaturesMessage(peer, message);
+				TransactionImporter.getInstance().onNetworkTransactionSignaturesMessage(peer, message);
 				break;
 
 			case GET_ONLINE_ACCOUNTS:
-				onNetworkGetOnlineAccountsMessage(peer, message);
+				OnlineAccountsManager.getInstance().onNetworkGetOnlineAccountsMessage(peer, message);
 				break;
 
 			case ONLINE_ACCOUNTS:
-				onNetworkOnlineAccountsMessage(peer, message);
+				OnlineAccountsManager.getInstance().onNetworkOnlineAccountsMessage(peer, message);
+				break;
+
+			case GET_ONLINE_ACCOUNTS_V2:
+				OnlineAccountsManager.getInstance().onNetworkGetOnlineAccountsV2Message(peer, message);
+				break;
+
+			case ONLINE_ACCOUNTS_V2:
+				OnlineAccountsManager.getInstance().onNetworkOnlineAccountsV2Message(peer, message);
 				break;
 
 			case GET_ARBITRARY_DATA:
@@ -1299,7 +1179,23 @@ public class Controller extends Thread {
 				break;
 
 			case ARBITRARY_SIGNATURES:
-				ArbitraryDataManager.getInstance().onNetworkArbitrarySignaturesMessage(peer, message);
+				// Not currently supported
+				break;
+
+			case GET_ARBITRARY_METADATA:
+				ArbitraryMetadataManager.getInstance().onNetworkGetArbitraryMetadataMessage(peer, message);
+				break;
+
+			case ARBITRARY_METADATA:
+				ArbitraryMetadataManager.getInstance().onNetworkArbitraryMetadataMessage(peer, message);
+				break;
+
+			case GET_TRADE_PRESENCES:
+				TradeBot.getInstance().onGetTradePresencesMessage(peer, message);
+				break;
+
+			case TRADE_PRESENCES:
+				TradeBot.getInstance().onTradePresencesMessage(peer, message);
 				break;
 
 			default:
@@ -1313,7 +1209,7 @@ public class Controller extends Thread {
 		byte[] signature = getBlockMessage.getSignature();
 		this.stats.getBlockMessageStats.requests.incrementAndGet();
 
-		ByteArray signatureAsByteArray = new ByteArray(signature);
+		ByteArray signatureAsByteArray = ByteArray.wrap(signature);
 
 		CachedBlockMessage cachedBlockMessage = this.blockMessageCache.get(signatureAsByteArray);
 		int blockCacheSize = Settings.getInstance().getBlockCacheSize();
@@ -1323,7 +1219,7 @@ public class Controller extends Thread {
 			this.stats.getBlockMessageStats.cacheHits.incrementAndGet();
 
 			// We need to duplicate it to prevent multiple threads setting ID on the same message
-			CachedBlockMessage clonedBlockMessage = cachedBlockMessage.cloneWithNewId(message.getId());
+			CachedBlockMessage clonedBlockMessage = Message.cloneWithNewId(cachedBlockMessage, message.getId());
 
 			if (!peer.sendMessage(clonedBlockMessage))
 				peer.disconnect("failed to send block");
@@ -1382,7 +1278,6 @@ public class Controller extends Thread {
 			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)) {
 				peer.disconnect("failed to send block");
 				// Don't fall-through to caching because failure to send might be from failure to build message
@@ -1393,20 +1288,12 @@ public class Controller extends Thread {
 			if (getChainHeight() - blockData.getHeight() <= blockCacheSize) {
 				this.stats.getBlockMessageStats.cacheFills.incrementAndGet();
 
-				this.blockMessageCache.put(new ByteArray(blockData.getSignature()), blockMessage);
+				this.blockMessageCache.put(ByteArray.wrap(blockData.getSignature()), blockMessage);
 			}
 		} catch (DataException e) {
-			LOGGER.error(String.format("Repository issue while send block %s to peer %s", Base58.encode(signature), peer), e);
-		}
-	}
-
-	private void onNetworkTransactionMessage(Peer peer, Message message) {
-		TransactionMessage transactionMessage = (TransactionMessage) message;
-		TransactionData transactionData = transactionMessage.getTransactionData();
-		if (this.incomingTransactions.size() < MAX_INCOMING_TRANSACTIONS) {
-			if (!this.incomingTransactions.contains(transactionData)) {
-				this.incomingTransactions.add(transactionData);
-			}
+			LOGGER.error(String.format("Repository issue while sending block %s to peer %s", Base58.encode(signature), peer), e);
+		} catch (TransformationException e) {
+			LOGGER.error(String.format("Serialization issue while sending block %s to peer %s", Base58.encode(signature), peer), e);
 		}
 	}
 
@@ -1561,392 +1448,17 @@ public class Controller extends Thread {
 		Synchronizer.getInstance().requestSync();
 	}
 
-	private void onNetworkGetTransactionMessage(Peer peer, Message message) {
-		GetTransactionMessage getTransactionMessage = (GetTransactionMessage) message;
-		byte[] signature = getTransactionMessage.getSignature();
-
-		try (final Repository repository = RepositoryManager.getRepository()) {
-			TransactionData transactionData = repository.getTransactionRepository().fromSignature(signature);
-			if (transactionData == null) {
-				LOGGER.debug(() -> String.format("Ignoring GET_TRANSACTION request from peer %s for unknown transaction %s", peer, Base58.encode(signature)));
-				// Send no response at all???
-				return;
-			}
-
-			Message transactionMessage = new TransactionMessage(transactionData);
-			transactionMessage.setId(message.getId());
-			if (!peer.sendMessage(transactionMessage))
-				peer.disconnect("failed to send transaction");
-		} catch (DataException e) {
-			LOGGER.error(String.format("Repository issue while send transaction %s to peer %s", Base58.encode(signature), peer), e);
-		}
-	}
-
-	private void onNetworkGetUnconfirmedTransactionsMessage(Peer peer, Message message) {
-		try (final Repository repository = RepositoryManager.getRepository()) {
-			List<byte[]> signatures = Collections.emptyList();
-
-			// If we're NOT up-to-date then don't send out unconfirmed transactions
-			// as it's possible they are already included in a later block that we don't have.
-			if (isUpToDate())
-				signatures = repository.getTransactionRepository().getUnconfirmedTransactionSignatures();
-
-			Message transactionSignaturesMessage = new TransactionSignaturesMessage(signatures);
-			if (!peer.sendMessage(transactionSignaturesMessage))
-				peer.disconnect("failed to send unconfirmed transaction signatures");
-		} catch (DataException e) {
-			LOGGER.error(String.format("Repository issue while sending unconfirmed transaction signatures to peer %s", peer), e);
-		}
-	}
-
-	private void onNetworkTransactionSignaturesMessage(Peer peer, Message message) {
-		TransactionSignaturesMessage transactionSignaturesMessage = (TransactionSignaturesMessage) message;
-		List<byte[]> signatures = transactionSignaturesMessage.getSignatures();
-
-		try (final Repository repository = RepositoryManager.getRepository()) {
-			for (byte[] signature : signatures) {
-				String signature58 = Base58.encode(signature);
-				if (invalidUnconfirmedTransactions.containsKey(signature58)) {
-					// Previously invalid transaction - don't keep requesting it
-					// It will be periodically removed from invalidUnconfirmedTransactions to allow for rechecks
-					continue;
-				}
-
-				// Ignore if this transaction is in the queue
-				if (incomingTransactionQueueContains(signature)) {
-					LOGGER.trace(() -> String.format("Ignoring existing queued transaction %s from peer %s", Base58.encode(signature), peer));
-					continue;
-				}
-
-				// Do we have it already? (Before requesting transaction data itself)
-				if (repository.getTransactionRepository().exists(signature)) {
-					LOGGER.trace(() -> String.format("Ignoring existing transaction %s from peer %s", Base58.encode(signature), peer));
-					continue;
-				}
-
-				// Check isInterrupted() here and exit fast
-				if (Thread.currentThread().isInterrupted())
-					return;
-
-				// Fetch actual transaction data from peer
-				Message getTransactionMessage = new GetTransactionMessage(signature);
-				if (!peer.sendMessage(getTransactionMessage)) {
-					peer.disconnect("failed to request transaction");
-					return;
-				}
-			}
-		} catch (DataException e) {
-			LOGGER.error(String.format("Repository issue while processing unconfirmed transactions from peer %s", peer), e);
-		}
-	}
-
-	private void onNetworkGetOnlineAccountsMessage(Peer peer, Message message) {
-		GetOnlineAccountsMessage getOnlineAccountsMessage = (GetOnlineAccountsMessage) message;
-
-		List<OnlineAccountData> excludeAccounts = getOnlineAccountsMessage.getOnlineAccounts();
-
-		// Send online accounts info, excluding entries with matching timestamp & public key from excludeAccounts
-		List<OnlineAccountData> accountsToSend;
-		synchronized (this.onlineAccounts) {
-			accountsToSend = new ArrayList<>(this.onlineAccounts);
-		}
-
-		Iterator<OnlineAccountData> iterator = accountsToSend.iterator();
-
-		SEND_ITERATOR:
-		while (iterator.hasNext()) {
-			OnlineAccountData onlineAccountData = iterator.next();
-
-			for (int i = 0; i < excludeAccounts.size(); ++i) {
-				OnlineAccountData excludeAccountData = excludeAccounts.get(i);
-
-				if (onlineAccountData.getTimestamp() == excludeAccountData.getTimestamp() && Arrays.equals(onlineAccountData.getPublicKey(), excludeAccountData.getPublicKey())) {
-					iterator.remove();
-					continue SEND_ITERATOR;
-				}
-			}
-		}
-
-		Message onlineAccountsMessage = new OnlineAccountsMessage(accountsToSend);
-		peer.sendMessage(onlineAccountsMessage);
-
-		LOGGER.trace(() -> String.format("Sent %d of our %d online accounts to %s", accountsToSend.size(), this.onlineAccounts.size(), peer));
-	}
-
-	private void onNetworkOnlineAccountsMessage(Peer peer, Message message) {
-		OnlineAccountsMessage onlineAccountsMessage = (OnlineAccountsMessage) message;
-
-		List<OnlineAccountData> peersOnlineAccounts = onlineAccountsMessage.getOnlineAccounts();
-		LOGGER.trace(() -> String.format("Received %d online accounts from %s", peersOnlineAccounts.size(), peer));
-
-		try (final Repository repository = RepositoryManager.getRepository()) {
-			for (OnlineAccountData onlineAccountData : peersOnlineAccounts)
-				this.verifyAndAddAccount(repository, onlineAccountData);
-		} catch (DataException e) {
-			LOGGER.error(String.format("Repository issue while verifying online accounts from peer %s", peer), e);
-		}
-	}
 
 	// Utilities
 
-	private void verifyAndAddAccount(Repository repository, OnlineAccountData onlineAccountData) throws DataException {
-		final Long now = NTP.getTime();
-		if (now == null)
-			return;
-
-		PublicKeyAccount otherAccount = new PublicKeyAccount(repository, onlineAccountData.getPublicKey());
-
-		// Check timestamp is 'recent' here
-		if (Math.abs(onlineAccountData.getTimestamp() - now) > ONLINE_TIMESTAMP_MODULUS * 2) {
-			LOGGER.trace(() -> String.format("Rejecting online account %s with out of range timestamp %d", otherAccount.getAddress(), onlineAccountData.getTimestamp()));
-			return;
-		}
-
-		// Verify
-		byte[] data = Longs.toByteArray(onlineAccountData.getTimestamp());
-		if (!otherAccount.verify(onlineAccountData.getSignature(), data)) {
-			LOGGER.trace(() -> String.format("Rejecting invalid online account %s", otherAccount.getAddress()));
-			return;
-		}
-
-		// Qortal: check online account is actually reward-share
-		RewardShareData rewardShareData = repository.getAccountRepository().getRewardShare(onlineAccountData.getPublicKey());
-		if (rewardShareData == null) {
-			// Reward-share doesn't even exist - probably not a good sign
-			LOGGER.trace(() -> String.format("Rejecting unknown online reward-share public key %s", Base58.encode(onlineAccountData.getPublicKey())));
-			return;
-		}
-
-		Account mintingAccount = new Account(repository, rewardShareData.getMinter());
-		if (!mintingAccount.canMint()) {
-			// Minting-account component of reward-share can no longer mint - disregard
-			LOGGER.trace(() -> String.format("Rejecting online reward-share with non-minting account %s", mintingAccount.getAddress()));
-			return;
-		}
-
-		synchronized (this.onlineAccounts) {
-			OnlineAccountData existingAccountData = this.onlineAccounts.stream().filter(account -> Arrays.equals(account.getPublicKey(), onlineAccountData.getPublicKey())).findFirst().orElse(null);
-
-			if (existingAccountData != null) {
-				if (existingAccountData.getTimestamp() < onlineAccountData.getTimestamp()) {
-					this.onlineAccounts.remove(existingAccountData);
-
-					LOGGER.trace(() -> String.format("Updated online account %s with timestamp %d (was %d)", otherAccount.getAddress(), onlineAccountData.getTimestamp(), existingAccountData.getTimestamp()));
-				} else {
-					LOGGER.trace(() -> String.format("Not updating existing online account %s", otherAccount.getAddress()));
-
-					return;
-				}
-			} else {
-				LOGGER.trace(() -> String.format("Added online account %s with timestamp %d", otherAccount.getAddress(), onlineAccountData.getTimestamp()));
-			}
-
-			this.onlineAccounts.add(onlineAccountData);
-		}
-	}
-
-	public void ensureTestingAccountsOnline(PrivateKeyAccount... onlineAccounts) {
-		if (!BlockChain.getInstance().isTestChain()) {
-			LOGGER.warn("Ignoring attempt to ensure test account is online for non-test chain!");
-			return;
-		}
-
-		final Long now = NTP.getTime();
-		if (now == null)
-			return;
-
-		final long onlineAccountsTimestamp = Controller.toOnlineAccountTimestamp(now);
-		byte[] timestampBytes = Longs.toByteArray(onlineAccountsTimestamp);
-
-		synchronized (this.onlineAccounts) {
-			this.onlineAccounts.clear();
-
-			for (PrivateKeyAccount onlineAccount : onlineAccounts) {
-				// Check mintingAccount is actually reward-share?
-
-				byte[] signature = onlineAccount.sign(timestampBytes);
-				byte[] publicKey = onlineAccount.getPublicKey();
-
-				OnlineAccountData ourOnlineAccountData = new OnlineAccountData(onlineAccountsTimestamp, signature, publicKey);
-				this.onlineAccounts.add(ourOnlineAccountData);
-			}
-		}
-	}
-
-	private void performOnlineAccountsTasks() {
-		final Long now = NTP.getTime();
-		if (now == null)
-			return;
-
-		// Expire old entries
-		final long cutoffThreshold = now - LAST_SEEN_EXPIRY_PERIOD;
-		synchronized (this.onlineAccounts) {
-			Iterator<OnlineAccountData> iterator = this.onlineAccounts.iterator();
-			while (iterator.hasNext()) {
-				OnlineAccountData onlineAccountData = iterator.next();
-
-				if (onlineAccountData.getTimestamp() < cutoffThreshold) {
-					iterator.remove();
-
-					LOGGER.trace(() -> {
-						PublicKeyAccount otherAccount = new PublicKeyAccount(null, onlineAccountData.getPublicKey());
-						return String.format("Removed expired online account %s with timestamp %d", otherAccount.getAddress(), onlineAccountData.getTimestamp());
-					});
-				}
-			}
-		}
-
-		// Request data from other peers?
-		if ((this.onlineAccountsTasksTimestamp % ONLINE_ACCOUNTS_BROADCAST_INTERVAL) < ONLINE_ACCOUNTS_TASKS_INTERVAL) {
-			Message message;
-			synchronized (this.onlineAccounts) {
-				message = new GetOnlineAccountsMessage(this.onlineAccounts);
-			}
-			Network.getInstance().broadcast(peer -> message);
-		}
-
-		// Refresh our online accounts signatures?
-		sendOurOnlineAccountsInfo();
-	}
-
-	private void sendOurOnlineAccountsInfo() {
-		final Long now = NTP.getTime();
-		if (now != null) {
-
-			List<MintingAccountData> mintingAccounts;
-			try (final Repository repository = RepositoryManager.getRepository()) {
-				mintingAccounts = repository.getAccountRepository().getMintingAccounts();
-
-				// We have no accounts, but don't reset timestamp
-				if (mintingAccounts.isEmpty())
-					return;
-
-				// Only reward-share accounts allowed
-				Iterator<MintingAccountData> iterator = mintingAccounts.iterator();
-				int i = 0;
-				while (iterator.hasNext()) {
-					MintingAccountData mintingAccountData = iterator.next();
-
-					RewardShareData rewardShareData = repository.getAccountRepository().getRewardShare(mintingAccountData.getPublicKey());
-					if (rewardShareData == null) {
-						// Reward-share doesn't even exist - probably not a good sign
-						iterator.remove();
-						continue;
-					}
-
-					Account mintingAccount = new Account(repository, rewardShareData.getMinter());
-					if (!mintingAccount.canMint()) {
-						// Minting-account component of reward-share can no longer mint - disregard
-						iterator.remove();
-						continue;
-					}
-
-					if (++i > 2) {
-						iterator.remove();
-						continue;
-					}
-				}
-			} catch (DataException e) {
-				LOGGER.warn(String.format("Repository issue trying to fetch minting accounts: %s", e.getMessage()));
-				return;
-			}
-
-			// 'current' timestamp
-			final long onlineAccountsTimestamp = Controller.toOnlineAccountTimestamp(now);
-			boolean hasInfoChanged = false;
-
-			byte[] timestampBytes = Longs.toByteArray(onlineAccountsTimestamp);
-			List<OnlineAccountData> ourOnlineAccounts = new ArrayList<>();
-
-			MINTING_ACCOUNTS:
-			for (MintingAccountData mintingAccountData : mintingAccounts) {
-				PrivateKeyAccount mintingAccount = new PrivateKeyAccount(null, mintingAccountData.getPrivateKey());
-
-				byte[] signature = mintingAccount.sign(timestampBytes);
-				byte[] publicKey = mintingAccount.getPublicKey();
-
-				// Our account is online
-				OnlineAccountData ourOnlineAccountData = new OnlineAccountData(onlineAccountsTimestamp, signature, publicKey);
-				synchronized (this.onlineAccounts) {
-					Iterator<OnlineAccountData> iterator = this.onlineAccounts.iterator();
-					while (iterator.hasNext()) {
-						OnlineAccountData existingOnlineAccountData = iterator.next();
-
-						if (Arrays.equals(existingOnlineAccountData.getPublicKey(), ourOnlineAccountData.getPublicKey())) {
-							// If our online account is already present, with same timestamp, then move on to next mintingAccount
-							if (existingOnlineAccountData.getTimestamp() == onlineAccountsTimestamp)
-								continue MINTING_ACCOUNTS;
-
-							// If our online account is already present, but with older timestamp, then remove it
-							iterator.remove();
-							break;
-						}
-					}
-
-					this.onlineAccounts.add(ourOnlineAccountData);
-				}
-
-				LOGGER.trace(() -> String.format("Added our online account %s with timestamp %d", mintingAccount.getAddress(), onlineAccountsTimestamp));
-				ourOnlineAccounts.add(ourOnlineAccountData);
-				hasInfoChanged = true;
-			}
-
-			if (!hasInfoChanged)
-				return;
-
-			Message message = new OnlineAccountsMessage(ourOnlineAccounts);
-			Network.getInstance().broadcast(peer -> message);
-
-			LOGGER.trace(() -> String.format("Broadcasted %d online account%s with timestamp %d", ourOnlineAccounts.size(), (ourOnlineAccounts.size() != 1 ? "s" : ""), onlineAccountsTimestamp));
-		}
-	}
-
-	public static long toOnlineAccountTimestamp(long timestamp) {
-		return (timestamp / ONLINE_TIMESTAMP_MODULUS) * ONLINE_TIMESTAMP_MODULUS;
-	}
-
-	/** Returns list of online accounts with timestamp recent enough to be considered currently online. */
-	public List<OnlineAccountData> getOnlineAccounts() {
-		final long onlineTimestamp = Controller.toOnlineAccountTimestamp(NTP.getTime());
-
-		synchronized (this.onlineAccounts) {
-			return this.onlineAccounts.stream().filter(account -> account.getTimestamp() == onlineTimestamp).collect(Collectors.toList());
-		}
-	}
-
-	/** Returns cached, unmodifiable list of latest block's online accounts. */
-	public List<OnlineAccountData> getLatestBlocksOnlineAccounts() {
-		synchronized (this.latestBlocksOnlineAccounts) {
-			return this.latestBlocksOnlineAccounts.peekFirst();
-		}
-	}
-
-	/** Caches list of latest block's online accounts. Typically called by Block.process() */
-	public void pushLatestBlocksOnlineAccounts(List<OnlineAccountData> latestBlocksOnlineAccounts) {
-		synchronized (this.latestBlocksOnlineAccounts) {
-			if (this.latestBlocksOnlineAccounts.size() == MAX_BLOCKS_CACHED_ONLINE_ACCOUNTS)
-				this.latestBlocksOnlineAccounts.pollLast();
-
-			this.latestBlocksOnlineAccounts.addFirst(latestBlocksOnlineAccounts == null
-					? Collections.emptyList()
-					: Collections.unmodifiableList(latestBlocksOnlineAccounts));
-		}
-	}
-
-	/** Reverts list of latest block's online accounts. Typically called by Block.orphan() */
-	public void popLatestBlocksOnlineAccounts() {
-		synchronized (this.latestBlocksOnlineAccounts) {
-			this.latestBlocksOnlineAccounts.pollFirst();
-		}
-	}
-
 	/** Returns a list of peers that are not misbehaving, and have a recent block. */
 	public List<Peer> getRecentBehavingPeers() {
 		final Long minLatestBlockTimestamp = getMinimumLatestBlockTimestamp();
 		if (minLatestBlockTimestamp == null)
 			return null;
 
-		List<Peer> peers = Network.getInstance().getHandshakedPeers();
+		// Needs a mutable copy of the unmodifiableList
+		List<Peer> peers = new ArrayList<>(Network.getInstance().getImmutableHandshakedPeers());
 
 		// Filter out unsuitable peers
 		Iterator<Peer> iterator = peers.iterator();
@@ -1981,10 +1493,13 @@ public class Controller extends Thread {
 		return peers;
 	}
 
-	/** Returns whether we think our node has up-to-date blockchain based on our info about other peers. */
-	public boolean isUpToDate() {
+	/**
+	 * Returns whether we think our node has up-to-date blockchain based on our info about other peers.
+	 * @param minLatestBlockTimestamp - the minimum block timestamp to be considered recent
+	 * @return boolean - whether our node's blockchain is up to date or not
+	 */
+	public boolean isUpToDate(Long minLatestBlockTimestamp) {
 		// Do we even have a vaguely recent block?
-		final Long minLatestBlockTimestamp = getMinimumLatestBlockTimestamp();
 		if (minLatestBlockTimestamp == null)
 			return false;
 
@@ -1992,7 +1507,8 @@ public class Controller extends Thread {
 		if (latestBlockData == null || latestBlockData.getTimestamp() < minLatestBlockTimestamp)
 			return false;
 
-		List<Peer> peers = Network.getInstance().getHandshakedPeers();
+		// Needs a mutable copy of the unmodifiableList
+		List<Peer> peers = new ArrayList<>(Network.getInstance().getImmutableHandshakedPeers());
 		if (peers == null)
 			return false;
 
@@ -2010,6 +1526,16 @@ public class Controller extends Thread {
 		return !peers.isEmpty();
 	}
 
+	/**
+	 * Returns whether we think our node has up-to-date blockchain based on our info about other peers.
+	 * Uses the default minLatestBlockTimestamp value.
+	 * @return boolean - whether our node's blockchain is up to date or not
+	 */
+	public boolean isUpToDate() {
+		final Long minLatestBlockTimestamp = getMinimumLatestBlockTimestamp();
+		return this.isUpToDate(minLatestBlockTimestamp);
+	}
+
 	/** Returns minimum block timestamp for block to be considered 'recent', or <tt>null</tt> if NTP not synced. */
 	public static Long getMinimumLatestBlockTimestamp() {
 		Long now = NTP.getTime();

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

@@ -0,0 +1,524 @@
+package org.qortal.controller;
+
+import com.google.common.primitives.Longs;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.account.Account;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.account.PublicKeyAccount;
+import org.qortal.block.BlockChain;
+import org.qortal.data.account.MintingAccountData;
+import org.qortal.data.account.RewardShareData;
+import org.qortal.data.network.OnlineAccountData;
+import org.qortal.network.Network;
+import org.qortal.network.Peer;
+import org.qortal.network.message.*;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+import java.util.*;
+import java.util.stream.Collectors;
+
+public class OnlineAccountsManager extends Thread {
+
+    private class OurOnlineAccountsThread extends Thread {
+
+        public void run() {
+            try {
+                while (!isStopping) {
+                    Thread.sleep(10000L);
+
+                    // Refresh our online accounts signatures?
+                    sendOurOnlineAccountsInfo();
+
+                }
+            } catch (InterruptedException e) {
+                // Fall through to exit thread
+            }
+        }
+    }
+
+
+    private static final Logger LOGGER = LogManager.getLogger(OnlineAccountsManager.class);
+
+    private static OnlineAccountsManager instance;
+    private volatile boolean isStopping = false;
+
+    // To do with online accounts list
+    private static final long ONLINE_ACCOUNTS_TASKS_INTERVAL = 10 * 1000L; // ms
+    private static final long ONLINE_ACCOUNTS_BROADCAST_INTERVAL = 1 * 60 * 1000L; // ms
+    public static final long ONLINE_TIMESTAMP_MODULUS = 5 * 60 * 1000L;
+    private static final long LAST_SEEN_EXPIRY_PERIOD = (ONLINE_TIMESTAMP_MODULUS * 2) + (1 * 60 * 1000L);
+    /** How many (latest) blocks' worth of online accounts we cache */
+    private static final int MAX_BLOCKS_CACHED_ONLINE_ACCOUNTS = 2;
+    private static final long ONLINE_ACCOUNTS_V2_PEER_VERSION = 0x0300020000L;
+
+    private long onlineAccountsTasksTimestamp = Controller.startTime + ONLINE_ACCOUNTS_TASKS_INTERVAL; // ms
+
+    private final List<OnlineAccountData> onlineAccountsImportQueue = Collections.synchronizedList(new ArrayList<>());
+
+
+    /** Cache of current 'online accounts' */
+    List<OnlineAccountData> onlineAccounts = new ArrayList<>();
+    /** Cache of latest blocks' online accounts */
+    Deque<List<OnlineAccountData>> latestBlocksOnlineAccounts = new ArrayDeque<>(MAX_BLOCKS_CACHED_ONLINE_ACCOUNTS);
+
+    public OnlineAccountsManager() {
+
+    }
+
+    public static synchronized OnlineAccountsManager getInstance() {
+        if (instance == null) {
+            instance = new OnlineAccountsManager();
+        }
+
+        return instance;
+    }
+
+    public void run() {
+
+        // Start separate thread to prepare our online accounts
+        // This could be converted to a thread pool later if more concurrency is needed
+        OurOnlineAccountsThread ourOnlineAccountsThread = new OurOnlineAccountsThread();
+        ourOnlineAccountsThread.start();
+
+        try {
+            while (!Controller.isStopping()) {
+                Thread.sleep(100L);
+
+                final Long now = NTP.getTime();
+                if (now == null) {
+                    continue;
+                }
+
+                // Perform tasks to do with managing online accounts list
+                if (now >= onlineAccountsTasksTimestamp) {
+                    onlineAccountsTasksTimestamp = now + ONLINE_ACCOUNTS_TASKS_INTERVAL;
+                    performOnlineAccountsTasks();
+                }
+
+                // Process queued online account verifications
+                this.processOnlineAccountsImportQueue();
+
+            }
+        } catch (InterruptedException e) {
+            // Fall through to exit thread
+        }
+
+        ourOnlineAccountsThread.interrupt();
+    }
+
+    public void shutdown() {
+        isStopping = true;
+        this.interrupt();
+    }
+
+
+    // Online accounts import queue
+
+    private void processOnlineAccountsImportQueue() {
+        if (this.onlineAccountsImportQueue.isEmpty()) {
+            // Nothing to do
+            return;
+        }
+
+        LOGGER.debug("Processing online accounts import queue (size: {})", this.onlineAccountsImportQueue.size());
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+
+            List<OnlineAccountData> onlineAccountDataCopy = new ArrayList<>(this.onlineAccountsImportQueue);
+            for (OnlineAccountData onlineAccountData : onlineAccountDataCopy) {
+                if (isStopping) {
+                    return;
+                }
+
+                this.verifyAndAddAccount(repository, onlineAccountData);
+
+                // Remove from queue
+                onlineAccountsImportQueue.remove(onlineAccountData);
+            }
+
+            LOGGER.debug("Finished processing online accounts import queue");
+            
+        } catch (DataException e) {
+            LOGGER.error(String.format("Repository issue while verifying online accounts"), e);
+        }
+    }
+
+
+    // Utilities
+
+    private void verifyAndAddAccount(Repository repository, OnlineAccountData onlineAccountData) throws DataException {
+        final Long now = NTP.getTime();
+        if (now == null)
+            return;
+
+        PublicKeyAccount otherAccount = new PublicKeyAccount(repository, onlineAccountData.getPublicKey());
+
+        // Check timestamp is 'recent' here
+        if (Math.abs(onlineAccountData.getTimestamp() - now) > ONLINE_TIMESTAMP_MODULUS * 2) {
+            LOGGER.trace(() -> String.format("Rejecting online account %s with out of range timestamp %d", otherAccount.getAddress(), onlineAccountData.getTimestamp()));
+            return;
+        }
+
+        // Verify
+        byte[] data = Longs.toByteArray(onlineAccountData.getTimestamp());
+        if (!otherAccount.verify(onlineAccountData.getSignature(), data)) {
+            LOGGER.trace(() -> String.format("Rejecting invalid online account %s", otherAccount.getAddress()));
+            return;
+        }
+
+        // Qortal: check online account is actually reward-share
+        RewardShareData rewardShareData = repository.getAccountRepository().getRewardShare(onlineAccountData.getPublicKey());
+        if (rewardShareData == null) {
+            // Reward-share doesn't even exist - probably not a good sign
+            LOGGER.trace(() -> String.format("Rejecting unknown online reward-share public key %s", Base58.encode(onlineAccountData.getPublicKey())));
+            return;
+        }
+
+        Account mintingAccount = new Account(repository, rewardShareData.getMinter());
+        if (!mintingAccount.canMint()) {
+            // Minting-account component of reward-share can no longer mint - disregard
+            LOGGER.trace(() -> String.format("Rejecting online reward-share with non-minting account %s", mintingAccount.getAddress()));
+            return;
+        }
+
+        synchronized (this.onlineAccounts) {
+            OnlineAccountData existingAccountData = this.onlineAccounts.stream().filter(account -> Arrays.equals(account.getPublicKey(), onlineAccountData.getPublicKey())).findFirst().orElse(null);
+
+            if (existingAccountData != null) {
+                if (existingAccountData.getTimestamp() < onlineAccountData.getTimestamp()) {
+                    this.onlineAccounts.remove(existingAccountData);
+
+                    LOGGER.trace(() -> String.format("Updated online account %s with timestamp %d (was %d)", otherAccount.getAddress(), onlineAccountData.getTimestamp(), existingAccountData.getTimestamp()));
+                } else {
+                    LOGGER.trace(() -> String.format("Not updating existing online account %s", otherAccount.getAddress()));
+
+                    return;
+                }
+            } else {
+                LOGGER.trace(() -> String.format("Added online account %s with timestamp %d", otherAccount.getAddress(), onlineAccountData.getTimestamp()));
+            }
+
+            this.onlineAccounts.add(onlineAccountData);
+        }
+    }
+
+    public void ensureTestingAccountsOnline(PrivateKeyAccount... onlineAccounts) {
+        if (!BlockChain.getInstance().isTestChain()) {
+            LOGGER.warn("Ignoring attempt to ensure test account is online for non-test chain!");
+            return;
+        }
+
+        final Long now = NTP.getTime();
+        if (now == null)
+            return;
+
+        final long onlineAccountsTimestamp = toOnlineAccountTimestamp(now);
+        byte[] timestampBytes = Longs.toByteArray(onlineAccountsTimestamp);
+
+        synchronized (this.onlineAccounts) {
+            this.onlineAccounts.clear();
+
+            for (PrivateKeyAccount onlineAccount : onlineAccounts) {
+                // Check mintingAccount is actually reward-share?
+
+                byte[] signature = onlineAccount.sign(timestampBytes);
+                byte[] publicKey = onlineAccount.getPublicKey();
+
+                OnlineAccountData ourOnlineAccountData = new OnlineAccountData(onlineAccountsTimestamp, signature, publicKey);
+                this.onlineAccounts.add(ourOnlineAccountData);
+            }
+        }
+    }
+
+    private void performOnlineAccountsTasks() {
+        final Long now = NTP.getTime();
+        if (now == null)
+            return;
+
+        // Expire old entries
+        final long cutoffThreshold = now - LAST_SEEN_EXPIRY_PERIOD;
+        synchronized (this.onlineAccounts) {
+            Iterator<OnlineAccountData> iterator = this.onlineAccounts.iterator();
+            while (iterator.hasNext()) {
+                OnlineAccountData onlineAccountData = iterator.next();
+
+                if (onlineAccountData.getTimestamp() < cutoffThreshold) {
+                    iterator.remove();
+
+                    LOGGER.trace(() -> {
+                        PublicKeyAccount otherAccount = new PublicKeyAccount(null, onlineAccountData.getPublicKey());
+                        return String.format("Removed expired online account %s with timestamp %d", otherAccount.getAddress(), onlineAccountData.getTimestamp());
+                    });
+                }
+            }
+        }
+
+        // Request data from other peers?
+        if ((this.onlineAccountsTasksTimestamp % ONLINE_ACCOUNTS_BROADCAST_INTERVAL) < ONLINE_ACCOUNTS_TASKS_INTERVAL) {
+            List<OnlineAccountData> safeOnlineAccounts;
+            synchronized (this.onlineAccounts) {
+                safeOnlineAccounts = new ArrayList<>(this.onlineAccounts);
+            }
+
+            Message messageV1 = new GetOnlineAccountsMessage(safeOnlineAccounts);
+            Message messageV2 = new GetOnlineAccountsV2Message(safeOnlineAccounts);
+
+            Network.getInstance().broadcast(peer ->
+                    peer.getPeersVersion() >= ONLINE_ACCOUNTS_V2_PEER_VERSION ? messageV2 : messageV1
+            );
+        }
+    }
+
+    private void sendOurOnlineAccountsInfo() {
+        final Long now = NTP.getTime();
+        if (now == null) {
+            return;
+        }
+
+        List<MintingAccountData> mintingAccounts;
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            mintingAccounts = repository.getAccountRepository().getMintingAccounts();
+
+            // We have no accounts, but don't reset timestamp
+            if (mintingAccounts.isEmpty())
+                return;
+
+            // Only reward-share accounts allowed
+            Iterator<MintingAccountData> iterator = mintingAccounts.iterator();
+            int i = 0;
+            while (iterator.hasNext()) {
+                MintingAccountData mintingAccountData = iterator.next();
+
+                RewardShareData rewardShareData = repository.getAccountRepository().getRewardShare(mintingAccountData.getPublicKey());
+                if (rewardShareData == null) {
+                    // Reward-share doesn't even exist - probably not a good sign
+                    iterator.remove();
+                    continue;
+                }
+
+                Account mintingAccount = new Account(repository, rewardShareData.getMinter());
+                if (!mintingAccount.canMint()) {
+                    // Minting-account component of reward-share can no longer mint - disregard
+                    iterator.remove();
+                    continue;
+                }
+
+                if (++i > 1+1) {
+                    iterator.remove();
+                    continue;
+                }
+            }
+        } catch (DataException e) {
+            LOGGER.warn(String.format("Repository issue trying to fetch minting accounts: %s", e.getMessage()));
+            return;
+        }
+
+        // 'current' timestamp
+        final long onlineAccountsTimestamp = toOnlineAccountTimestamp(now);
+        boolean hasInfoChanged = false;
+
+        byte[] timestampBytes = Longs.toByteArray(onlineAccountsTimestamp);
+        List<OnlineAccountData> ourOnlineAccounts = new ArrayList<>();
+
+        MINTING_ACCOUNTS:
+        for (MintingAccountData mintingAccountData : mintingAccounts) {
+            PrivateKeyAccount mintingAccount = new PrivateKeyAccount(null, mintingAccountData.getPrivateKey());
+
+            byte[] signature = mintingAccount.sign(timestampBytes);
+            byte[] publicKey = mintingAccount.getPublicKey();
+
+            // Our account is online
+            OnlineAccountData ourOnlineAccountData = new OnlineAccountData(onlineAccountsTimestamp, signature, publicKey);
+            synchronized (this.onlineAccounts) {
+                Iterator<OnlineAccountData> iterator = this.onlineAccounts.iterator();
+                while (iterator.hasNext()) {
+                    OnlineAccountData existingOnlineAccountData = iterator.next();
+
+                    if (Arrays.equals(existingOnlineAccountData.getPublicKey(), ourOnlineAccountData.getPublicKey())) {
+                        // If our online account is already present, with same timestamp, then move on to next mintingAccount
+                        if (existingOnlineAccountData.getTimestamp() == onlineAccountsTimestamp)
+                            continue MINTING_ACCOUNTS;
+
+                        // If our online account is already present, but with older timestamp, then remove it
+                        iterator.remove();
+                        break;
+                    }
+                }
+
+                this.onlineAccounts.add(ourOnlineAccountData);
+            }
+
+            LOGGER.trace(() -> String.format("Added our online account %s with timestamp %d", mintingAccount.getAddress(), onlineAccountsTimestamp));
+            ourOnlineAccounts.add(ourOnlineAccountData);
+            hasInfoChanged = true;
+        }
+
+        if (!hasInfoChanged)
+            return;
+
+        Message messageV1 = new OnlineAccountsMessage(ourOnlineAccounts);
+        Message messageV2 = new OnlineAccountsV2Message(ourOnlineAccounts);
+
+        Network.getInstance().broadcast(peer ->
+                peer.getPeersVersion() >= ONLINE_ACCOUNTS_V2_PEER_VERSION ? messageV2 : messageV1
+        );
+
+        LOGGER.trace(() -> String.format("Broadcasted %d online account%s with timestamp %d", ourOnlineAccounts.size(), (ourOnlineAccounts.size() != 1 ? "s" : ""), onlineAccountsTimestamp));
+    }
+
+    public static long toOnlineAccountTimestamp(long timestamp) {
+        return (timestamp / ONLINE_TIMESTAMP_MODULUS) * ONLINE_TIMESTAMP_MODULUS;
+    }
+
+    /** Returns list of online accounts with timestamp recent enough to be considered currently online. */
+    public List<OnlineAccountData> getOnlineAccounts() {
+        final long onlineTimestamp = toOnlineAccountTimestamp(NTP.getTime());
+
+        synchronized (this.onlineAccounts) {
+            return this.onlineAccounts.stream().filter(account -> account.getTimestamp() == onlineTimestamp).collect(Collectors.toList());
+        }
+    }
+
+
+    /** Returns cached, unmodifiable list of latest block's online accounts. */
+    public List<OnlineAccountData> getLatestBlocksOnlineAccounts() {
+        synchronized (this.latestBlocksOnlineAccounts) {
+            return this.latestBlocksOnlineAccounts.peekFirst();
+        }
+    }
+
+    /** Caches list of latest block's online accounts. Typically called by Block.process() */
+    public void pushLatestBlocksOnlineAccounts(List<OnlineAccountData> latestBlocksOnlineAccounts) {
+        synchronized (this.latestBlocksOnlineAccounts) {
+            if (this.latestBlocksOnlineAccounts.size() == MAX_BLOCKS_CACHED_ONLINE_ACCOUNTS)
+                this.latestBlocksOnlineAccounts.pollLast();
+
+            this.latestBlocksOnlineAccounts.addFirst(latestBlocksOnlineAccounts == null
+                    ? Collections.emptyList()
+                    : Collections.unmodifiableList(latestBlocksOnlineAccounts));
+        }
+    }
+
+    /** Reverts list of latest block's online accounts. Typically called by Block.orphan() */
+    public void popLatestBlocksOnlineAccounts() {
+        synchronized (this.latestBlocksOnlineAccounts) {
+            this.latestBlocksOnlineAccounts.pollFirst();
+        }
+    }
+
+
+    // Network handlers
+
+    public void onNetworkGetOnlineAccountsMessage(Peer peer, Message message) {
+        GetOnlineAccountsMessage getOnlineAccountsMessage = (GetOnlineAccountsMessage) message;
+
+        List<OnlineAccountData> excludeAccounts = getOnlineAccountsMessage.getOnlineAccounts();
+
+        // Send online accounts info, excluding entries with matching timestamp & public key from excludeAccounts
+        List<OnlineAccountData> accountsToSend;
+        synchronized (this.onlineAccounts) {
+            accountsToSend = new ArrayList<>(this.onlineAccounts);
+        }
+
+        Iterator<OnlineAccountData> iterator = accountsToSend.iterator();
+
+        SEND_ITERATOR:
+        while (iterator.hasNext()) {
+            OnlineAccountData onlineAccountData = iterator.next();
+
+            for (int i = 0; i < excludeAccounts.size(); ++i) {
+                OnlineAccountData excludeAccountData = excludeAccounts.get(i);
+
+                if (onlineAccountData.getTimestamp() == excludeAccountData.getTimestamp() && Arrays.equals(onlineAccountData.getPublicKey(), excludeAccountData.getPublicKey())) {
+                    iterator.remove();
+                    continue SEND_ITERATOR;
+                }
+            }
+        }
+
+        Message onlineAccountsMessage = new OnlineAccountsMessage(accountsToSend);
+        peer.sendMessage(onlineAccountsMessage);
+
+        LOGGER.trace(() -> String.format("Sent %d of our %d online accounts to %s", accountsToSend.size(), this.onlineAccounts.size(), peer));
+    }
+
+    public void onNetworkOnlineAccountsMessage(Peer peer, Message message) {
+        OnlineAccountsMessage onlineAccountsMessage = (OnlineAccountsMessage) message;
+
+        List<OnlineAccountData> peersOnlineAccounts = onlineAccountsMessage.getOnlineAccounts();
+        LOGGER.trace(() -> String.format("Received %d online accounts from %s", peersOnlineAccounts.size(), peer));
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            for (OnlineAccountData onlineAccountData : peersOnlineAccounts)
+                this.verifyAndAddAccount(repository, onlineAccountData);
+        } catch (DataException e) {
+            LOGGER.error(String.format("Repository issue while verifying online accounts from peer %s", peer), e);
+        }
+    }
+
+    public void onNetworkGetOnlineAccountsV2Message(Peer peer, Message message) {
+        GetOnlineAccountsV2Message getOnlineAccountsMessage = (GetOnlineAccountsV2Message) message;
+
+        List<OnlineAccountData> excludeAccounts = getOnlineAccountsMessage.getOnlineAccounts();
+
+        // Send online accounts info, excluding entries with matching timestamp & public key from excludeAccounts
+        List<OnlineAccountData> accountsToSend;
+        synchronized (this.onlineAccounts) {
+            accountsToSend = new ArrayList<>(this.onlineAccounts);
+        }
+
+        Iterator<OnlineAccountData> iterator = accountsToSend.iterator();
+
+        SEND_ITERATOR:
+        while (iterator.hasNext()) {
+            OnlineAccountData onlineAccountData = iterator.next();
+
+            for (int i = 0; i < excludeAccounts.size(); ++i) {
+                OnlineAccountData excludeAccountData = excludeAccounts.get(i);
+
+                if (onlineAccountData.getTimestamp() == excludeAccountData.getTimestamp() && Arrays.equals(onlineAccountData.getPublicKey(), excludeAccountData.getPublicKey())) {
+                    iterator.remove();
+                    continue SEND_ITERATOR;
+                }
+            }
+        }
+
+        Message onlineAccountsMessage = new OnlineAccountsV2Message(accountsToSend);
+        peer.sendMessage(onlineAccountsMessage);
+
+        LOGGER.trace(() -> String.format("Sent %d of our %d online accounts to %s", accountsToSend.size(), this.onlineAccounts.size(), peer));
+    }
+
+    public void onNetworkOnlineAccountsV2Message(Peer peer, Message message) {
+        OnlineAccountsV2Message onlineAccountsMessage = (OnlineAccountsV2Message) message;
+
+        List<OnlineAccountData> peersOnlineAccounts = onlineAccountsMessage.getOnlineAccounts();
+        LOGGER.debug(String.format("Received %d online accounts from %s", peersOnlineAccounts.size(), peer));
+
+        int importCount = 0;
+
+        // Add any online accounts to the queue that aren't already present
+        for (OnlineAccountData onlineAccountData : peersOnlineAccounts) {
+
+            // Do we already know about this online account data?
+            if (onlineAccounts.contains(onlineAccountData)) {
+                continue;
+            }
+
+            // Is it already in the import queue?
+            if (onlineAccountsImportQueue.contains(onlineAccountData)) {
+                continue;
+            }
+
+            onlineAccountsImportQueue.add(onlineAccountData);
+            importCount++;
+        }
+
+        LOGGER.debug(String.format("Added %d online accounts to queue", importCount));
+    }
+}

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

@@ -22,6 +22,8 @@ import org.qortal.data.block.CommonBlockData;
 import org.qortal.data.network.PeerChainTipData;
 import org.qortal.data.transaction.RewardShareTransactionData;
 import org.qortal.data.transaction.TransactionData;
+import org.qortal.event.Event;
+import org.qortal.event.EventBus;
 import org.qortal.network.Network;
 import org.qortal.network.Peer;
 import org.qortal.network.message.BlockMessage;
@@ -31,7 +33,7 @@ import org.qortal.network.message.GetBlockSummariesMessage;
 import org.qortal.network.message.GetSignaturesV2Message;
 import org.qortal.network.message.Message;
 import org.qortal.network.message.SignaturesMessage;
-import org.qortal.network.message.Message.MessageType;
+import org.qortal.network.message.MessageType;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryManager;
@@ -93,7 +95,25 @@ public class Synchronizer extends Thread {
 	private static Synchronizer instance;
 
 	public enum SynchronizationResult {
-		OK, NOTHING_TO_DO, GENESIS_ONLY, NO_COMMON_BLOCK, TOO_DIVERGENT, NO_REPLY, INFERIOR_CHAIN, INVALID_DATA, NO_BLOCKCHAIN_LOCK, REPOSITORY_ISSUE, SHUTTING_DOWN;
+		OK, NOTHING_TO_DO, GENESIS_ONLY, NO_COMMON_BLOCK, TOO_DIVERGENT, NO_REPLY, INFERIOR_CHAIN, INVALID_DATA, NO_BLOCKCHAIN_LOCK, REPOSITORY_ISSUE, SHUTTING_DOWN, CHAIN_TIP_TOO_OLD;
+	}
+
+	public static class NewChainTipEvent implements Event {
+		private final BlockData priorChainTip;
+		private final BlockData newChainTip;
+
+		public NewChainTipEvent(BlockData priorChainTip, BlockData newChainTip) {
+			this.priorChainTip = priorChainTip;
+			this.newChainTip = newChainTip;
+		}
+
+		public BlockData getPriorChainTip() {
+			return this.priorChainTip;
+		}
+
+		public BlockData getNewChainTip() {
+			return this.newChainTip;
+		}
 	}
 
 	// Constructors
@@ -153,6 +173,12 @@ public class Synchronizer extends Thread {
 
 	public Integer getSyncPercent() {
 		synchronized (this.syncLock) {
+			// Report as 100% synced if the latest block is within the last 30 mins
+			final Long minLatestBlockTimestamp = NTP.getTime() - (30 * 60 * 1000L);
+			if (Controller.getInstance().isUpToDate(minLatestBlockTimestamp)) {
+				return 100;
+			}
+
 			return this.isSynchronizing ? this.syncPercent : null;
 		}
 	}
@@ -175,7 +201,8 @@ public class Synchronizer extends Thread {
 		if (this.isSynchronizing)
 			return true;
 
-		List<Peer> peers = Network.getInstance().getHandshakedPeers();
+		// Needs a mutable copy of the unmodifiableList
+		List<Peer> peers = new ArrayList<>(Network.getInstance().getImmutableHandshakedPeers());
 
 		// Disregard peers that have "misbehaved" recently
 		peers.removeIf(Controller.hasMisbehaved);
@@ -191,7 +218,8 @@ public class Synchronizer extends Thread {
 
 		checkRecoveryModeForPeers(peers);
 		if (recoveryMode) {
-			peers = Network.getInstance().getHandshakedPeers();
+			// Needs a mutable copy of the unmodifiableList
+			peers = new ArrayList<>(Network.getInstance().getImmutableHandshakedPeers());
 			peers.removeIf(Controller.hasOnlyGenesisBlock);
 			peers.removeIf(Controller.hasMisbehaved);
 			peers.removeIf(Controller.hasOldVersion);
@@ -218,6 +246,12 @@ public class Synchronizer extends Thread {
 		// We may have added more inferior chain tips when comparing peers, so remove any peers that are currently on those chains
 		peers.removeIf(Controller.hasInferiorChainTip);
 
+		// Remove any peers that are no longer on a recent block since the last check
+		// Except for times when we're in recovery mode, in which case we need to keep them
+		if (!recoveryMode) {
+			peers.removeIf(Controller.hasNoRecentBlock);
+		}
+
 		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()));
@@ -280,7 +314,7 @@ public class Synchronizer extends Thread {
 
 				case INFERIOR_CHAIN: {
 					// Update our list of inferior chain tips
-					ByteArray inferiorChainSignature = new ByteArray(peer.getChainTipData().getLastBlockSignature());
+					ByteArray inferiorChainSignature = ByteArray.wrap(peer.getChainTipData().getLastBlockSignature());
 					if (!inferiorChainSignatures.contains(inferiorChainSignature))
 						inferiorChainSignatures.add(inferiorChainSignature);
 
@@ -296,6 +330,7 @@ public class Synchronizer extends Thread {
 				case NO_REPLY:
 				case NO_BLOCKCHAIN_LOCK:
 				case REPOSITORY_ISSUE:
+				case CHAIN_TIP_TOO_OLD:
 					// These are minor failure results so fine to try again
 					LOGGER.debug(() -> String.format("Failed to synchronize with peer %s (%s)", peer, syncResult.name()));
 					break;
@@ -308,7 +343,7 @@ public class Synchronizer extends Thread {
 					// fall-through...
 				case NOTHING_TO_DO: {
 					// Update our list of inferior chain tips
-					ByteArray inferiorChainSignature = new ByteArray(peer.getChainTipData().getLastBlockSignature());
+					ByteArray inferiorChainSignature = ByteArray.wrap(peer.getChainTipData().getLastBlockSignature());
 					if (!inferiorChainSignatures.contains(inferiorChainSignature))
 						inferiorChainSignatures.add(inferiorChainSignature);
 
@@ -338,6 +373,8 @@ public class Synchronizer extends Thread {
 
 				Network network = Network.getInstance();
 				network.broadcast(broadcastPeer -> network.buildHeightMessage(broadcastPeer, newChainTip));
+
+				EventBus.INSTANCE.notify(new NewChainTipEvent(priorChainTip, newChainTip));
 			}
 
 			return syncResult;
@@ -348,7 +385,7 @@ public class Synchronizer extends Thread {
 	}
 
 	private boolean checkRecoveryModeForPeers(List<Peer> qualifiedPeers) {
-		List<Peer> handshakedPeers = Network.getInstance().getHandshakedPeers();
+		List<Peer> handshakedPeers = Network.getInstance().getImmutableHandshakedPeers();
 
 		if (handshakedPeers.size() > 0) {
 			// There is at least one handshaked peer
@@ -382,7 +419,7 @@ public class Synchronizer extends Thread {
 
 	public void addInferiorChainSignature(byte[] inferiorSignature) {
 		// Update our list of inferior chain tips
-		ByteArray inferiorChainSignature = new ByteArray(inferiorSignature);
+		ByteArray inferiorChainSignature = ByteArray.wrap(inferiorSignature);
 		if (!inferiorChainSignatures.contains(inferiorChainSignature))
 			inferiorChainSignatures.add(inferiorChainSignature);
 	}
@@ -533,7 +570,7 @@ public class Synchronizer extends Thread {
 				// 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();
+				Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
 				if (minLatestBlockTimestamp == null)
 					return peers;
 
@@ -689,6 +726,7 @@ public class Synchronizer extends Thread {
 					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 Long peerLastBlockTimestamp = peer.getChainTipData().getLastBlockTimestamp();
 						final int peerAdditionalBlocksAfterCommonBlock = peerHeight - commonBlockSummary.getHeight();
 						final CommonBlockData peerCommonBlockData = peer.getCommonBlockData();
 
@@ -699,6 +737,14 @@ public class Synchronizer extends Thread {
 							continue;
 						}
 
+						// If peer is our of date (since our last check), we should exclude it from this round
+						minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
+						if (peerLastBlockTimestamp == null || peerLastBlockTimestamp < minLatestBlockTimestamp) {
+							LOGGER.debug(String.format("Peer %s is out of date - removing it from this round", peer));
+							peers.remove(peer);
+							continue;
+						}
+
 						final List<BlockSummaryData> peerBlockSummariesAfterCommonBlock = peerCommonBlockData.getBlockSummariesAfterCommonBlock();
 						populateBlockSummariesMinterLevels(repository, peerBlockSummariesAfterCommonBlock);
 
@@ -1261,6 +1307,16 @@ public class Synchronizer extends Thread {
 				return SynchronizationResult.INVALID_DATA;
 			}
 
+			// Final check to make sure the peer isn't out of date (except for when we're in recovery mode)
+			if (!recoveryMode && peer.getChainTipData() != null) {
+				final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
+				final Long peerLastBlockTimestamp = peer.getChainTipData().getLastBlockTimestamp();
+				if (peerLastBlockTimestamp == null || peerLastBlockTimestamp < minLatestBlockTimestamp) {
+					LOGGER.info(String.format("Peer %s is out of date, so abandoning sync attempt", peer));
+					return SynchronizationResult.CHAIN_TIP_TOO_OLD;
+				}
+			}
+
 			byte[] nextPeerSignature = peerBlockSignatures.get(0);
 			int nextHeight = height + 1;
 

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

@@ -0,0 +1,357 @@
+package org.qortal.controller;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.network.Peer;
+import org.qortal.network.message.GetTransactionMessage;
+import org.qortal.network.message.Message;
+import org.qortal.network.message.TransactionMessage;
+import org.qortal.network.message.TransactionSignaturesMessage;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.transaction.Transaction;
+import org.qortal.transform.TransformationException;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+import java.util.*;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.ReentrantLock;
+
+public class TransactionImporter extends Thread {
+
+    private static final Logger LOGGER = LogManager.getLogger(TransactionImporter.class);
+
+    private static TransactionImporter instance;
+    private volatile boolean isStopping = false;
+
+    private static final int MAX_INCOMING_TRANSACTIONS = 5000;
+
+    /** Minimum time before considering an invalid unconfirmed transaction as "stale" */
+    public static final long INVALID_TRANSACTION_STALE_TIMEOUT = 30 * 60 * 1000L; // ms
+    /** Minimum frequency to re-request stale unconfirmed transactions from peers, to recheck validity */
+    public static final long INVALID_TRANSACTION_RECHECK_INTERVAL = 60 * 60 * 1000L; // ms\
+    /** Minimum frequency to re-request expired unconfirmed transactions from peers, to recheck validity
+     * This mainly exists to stop expired transactions from bloating the list */
+    public static final long EXPIRED_TRANSACTION_RECHECK_INTERVAL = 10 * 60 * 1000L; // ms
+
+
+    /** Map of incoming transaction that are in the import queue. Key is transaction data, value is whether signature has been validated. */
+    private final Map<TransactionData, Boolean> incomingTransactions = Collections.synchronizedMap(new HashMap<>());
+
+    /** Map of recent invalid unconfirmed transactions. Key is base58 transaction signature, value is do-not-request expiry timestamp. */
+    private final Map<String, Long> invalidUnconfirmedTransactions = Collections.synchronizedMap(new HashMap<>());
+
+
+    public static synchronized TransactionImporter getInstance() {
+        if (instance == null) {
+            instance = new TransactionImporter();
+        }
+
+        return instance;
+    }
+
+    @Override
+    public void run() {
+        try {
+            while (!Controller.isStopping()) {
+                Thread.sleep(1000L);
+
+                // Process incoming transactions queue
+                processIncomingTransactionsQueue();
+                // Clean up invalid incoming transactions list
+                cleanupInvalidTransactionsList(NTP.getTime());
+            }
+        } catch (InterruptedException e) {
+            // Fall through to exit thread
+        }
+    }
+
+    public void shutdown() {
+        isStopping = true;
+        this.interrupt();
+    }
+
+
+    // Incoming transactions queue
+
+    private boolean incomingTransactionQueueContains(byte[] signature) {
+        synchronized (incomingTransactions) {
+            return incomingTransactions.keySet().stream().anyMatch(t -> Arrays.equals(t.getSignature(), signature));
+        }
+    }
+
+    private void removeIncomingTransaction(byte[] signature) {
+        incomingTransactions.keySet().removeIf(t -> Arrays.equals(t.getSignature(), signature));
+    }
+
+    private void processIncomingTransactionsQueue() {
+        if (this.incomingTransactions.isEmpty()) {
+            // Nothing to do?
+            return;
+        }
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            // Take a snapshot of incomingTransactions, so we don't need to lock it while processing
+            Map<TransactionData, Boolean> incomingTransactionsCopy = Map.copyOf(this.incomingTransactions);
+
+            int unvalidatedCount = Collections.frequency(incomingTransactionsCopy.values(), Boolean.FALSE);
+            int validatedCount = 0;
+
+            if (unvalidatedCount > 0) {
+                LOGGER.debug("Validating signatures in incoming transactions queue (size {})...", unvalidatedCount);
+            }
+
+            List<Transaction> sigValidTransactions = new ArrayList<>();
+
+            // Signature validation round - does not require blockchain lock
+            for (Map.Entry<TransactionData, Boolean> transactionEntry : incomingTransactionsCopy.entrySet()) {
+                // Quick exit?
+                if (isStopping) {
+                    return;
+                }
+
+                TransactionData transactionData = transactionEntry.getKey();
+                Transaction transaction = Transaction.fromData(repository, transactionData);
+
+                // Only validate signature if we haven't already done so
+                Boolean isSigValid = transactionEntry.getValue();
+                if (!Boolean.TRUE.equals(isSigValid)) {
+                    if (!transaction.isSignatureValid()) {
+                        String signature58 = Base58.encode(transactionData.getSignature());
+
+                        LOGGER.trace("Ignoring {} transaction {} with invalid signature", transactionData.getType().name(), signature58);
+                        removeIncomingTransaction(transactionData.getSignature());
+
+                        // Also add to invalidIncomingTransactions map
+                        Long now = NTP.getTime();
+                        if (now != null) {
+                            Long expiry = now + INVALID_TRANSACTION_RECHECK_INTERVAL;
+                            LOGGER.trace("Adding stale invalid transaction {} to invalidUnconfirmedTransactions...", signature58);
+                            // Add to invalidUnconfirmedTransactions so that we don't keep requesting it
+                            invalidUnconfirmedTransactions.put(signature58, expiry);
+                        }
+
+                        continue;
+                    }
+                    else {
+                        // Count the number that were validated in this round, for logging purposes
+                        validatedCount++;
+                    }
+
+                    // Add mark signature as valid if transaction still exists in import queue
+                    incomingTransactions.computeIfPresent(transactionData, (k, v) -> Boolean.TRUE);
+                } else {
+                    LOGGER.trace(() -> String.format("Transaction %s known to have valid signature", Base58.encode(transactionData.getSignature())));
+                }
+
+                // Signature valid - add to shortlist
+                sigValidTransactions.add(transaction);
+            }
+
+            if (unvalidatedCount > 0) {
+                LOGGER.debug("Finished validating signatures in incoming transactions queue (valid this round: {}, total pending import: {})...", validatedCount, sigValidTransactions.size());
+            }
+
+            if (sigValidTransactions.isEmpty()) {
+                // Don't bother locking if there are no new transactions to process
+                return;
+            }
+
+            if (Synchronizer.getInstance().isSyncRequested() || Synchronizer.getInstance().isSynchronizing()) {
+                // Prioritize syncing, and don't attempt to lock
+                // Signature validity is retained in the incomingTransactions map, to avoid the above work being wasted
+                return;
+            }
+
+            try {
+                ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
+                if (!blockchainLock.tryLock(2, TimeUnit.SECONDS)) {
+                    // Signature validity is retained in the incomingTransactions map, to avoid the above work being wasted
+                    LOGGER.debug("Too busy to process incoming transactions queue");
+                    return;
+                }
+            } catch (InterruptedException e) {
+                LOGGER.debug("Interrupted when trying to acquire blockchain lock");
+                return;
+            }
+
+            LOGGER.debug("Processing incoming transactions queue (size {})...", sigValidTransactions.size());
+
+            // Import transactions with valid signatures
+            try {
+                for (int i = 0; i < sigValidTransactions.size(); ++i) {
+                    if (isStopping) {
+                        return;
+                    }
+
+                    if (Synchronizer.getInstance().isSyncRequestPending()) {
+                        LOGGER.debug("Breaking out of transaction processing with {} remaining, because a sync request is pending", sigValidTransactions.size() - i);
+                        return;
+                    }
+
+                    Transaction transaction = sigValidTransactions.get(i);
+                    TransactionData transactionData = transaction.getTransactionData();
+
+                    Transaction.ValidationResult validationResult = transaction.importAsUnconfirmed();
+
+                    switch (validationResult) {
+                        case TRANSACTION_ALREADY_EXISTS: {
+                            LOGGER.trace(() -> String.format("Ignoring existing transaction %s", Base58.encode(transactionData.getSignature())));
+                            break;
+                        }
+
+                        case NO_BLOCKCHAIN_LOCK: {
+                            // Is this even possible considering we acquired blockchain lock above?
+                            LOGGER.trace(() -> String.format("Couldn't lock blockchain to import unconfirmed transaction %s", Base58.encode(transactionData.getSignature())));
+                            break;
+                        }
+
+                        case OK: {
+                            LOGGER.debug(() -> String.format("Imported %s transaction %s", transactionData.getType().name(), Base58.encode(transactionData.getSignature())));
+                            break;
+                        }
+
+                        // All other invalid cases:
+                        default: {
+                            final String signature58 = Base58.encode(transactionData.getSignature());
+                            LOGGER.trace(() -> String.format("Ignoring invalid (%s) %s transaction %s", validationResult.name(), transactionData.getType().name(), signature58));
+
+                            Long now = NTP.getTime();
+                            if (now != null && now - transactionData.getTimestamp() > INVALID_TRANSACTION_STALE_TIMEOUT) {
+                                Long expiryLength = INVALID_TRANSACTION_RECHECK_INTERVAL;
+
+                                if (validationResult == Transaction.ValidationResult.TIMESTAMP_TOO_OLD) {
+                                    // Use shorter recheck interval for expired transactions
+                                    expiryLength = EXPIRED_TRANSACTION_RECHECK_INTERVAL;
+                                }
+
+                                Long expiry = now + expiryLength;
+                                LOGGER.trace("Adding stale invalid transaction {} to invalidUnconfirmedTransactions...", signature58);
+                                // Invalid, unconfirmed transaction has become stale - add to invalidUnconfirmedTransactions so that we don't keep requesting it
+                                invalidUnconfirmedTransactions.put(signature58, expiry);
+                            }
+                        }
+                    }
+
+                    // Transaction has been processed, even if only to reject it
+                    removeIncomingTransaction(transactionData.getSignature());
+                }
+            } finally {
+                LOGGER.debug("Finished processing incoming transactions queue");
+                ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
+                blockchainLock.unlock();
+            }
+        } catch (DataException e) {
+            LOGGER.error("Repository issue while processing incoming transactions", e);
+        }
+    }
+
+    private void cleanupInvalidTransactionsList(Long now) {
+        if (now == null) {
+            return;
+        }
+        // Periodically remove invalid unconfirmed transactions from the list, so that they can be fetched again
+        invalidUnconfirmedTransactions.entrySet().removeIf(entry -> entry.getValue() == null || entry.getValue() < now);
+    }
+
+
+    // Network handlers
+
+    public void onNetworkTransactionMessage(Peer peer, Message message) {
+        TransactionMessage transactionMessage = (TransactionMessage) message;
+        TransactionData transactionData = transactionMessage.getTransactionData();
+
+        if (this.incomingTransactions.size() < MAX_INCOMING_TRANSACTIONS) {
+            synchronized (this.incomingTransactions) {
+                if (!incomingTransactionQueueContains(transactionData.getSignature())) {
+                    this.incomingTransactions.put(transactionData, Boolean.FALSE);
+                }
+            }
+        }
+    }
+
+    public void onNetworkGetTransactionMessage(Peer peer, Message message) {
+        GetTransactionMessage getTransactionMessage = (GetTransactionMessage) message;
+        byte[] signature = getTransactionMessage.getSignature();
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            TransactionData transactionData = repository.getTransactionRepository().fromSignature(signature);
+            if (transactionData == null) {
+                LOGGER.debug(() -> String.format("Ignoring GET_TRANSACTION request from peer %s for unknown transaction %s", peer, Base58.encode(signature)));
+                // Send no response at all???
+                return;
+            }
+
+            Message transactionMessage = new TransactionMessage(transactionData);
+            transactionMessage.setId(message.getId());
+            if (!peer.sendMessage(transactionMessage))
+                peer.disconnect("failed to send transaction");
+        } catch (DataException e) {
+            LOGGER.error(String.format("Repository issue while sending transaction %s to peer %s", Base58.encode(signature), peer), e);
+        } catch (TransformationException e) {
+            LOGGER.error(String.format("Serialization issue while sending transaction %s to peer %s", Base58.encode(signature), peer), e);
+        }
+    }
+
+    public void onNetworkGetUnconfirmedTransactionsMessage(Peer peer, Message message) {
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            List<byte[]> signatures = Collections.emptyList();
+
+            // If we're NOT up-to-date then don't send out unconfirmed transactions
+            // as it's possible they are already included in a later block that we don't have.
+            if (Controller.getInstance().isUpToDate())
+                signatures = repository.getTransactionRepository().getUnconfirmedTransactionSignatures();
+
+            Message transactionSignaturesMessage = new TransactionSignaturesMessage(signatures);
+            if (!peer.sendMessage(transactionSignaturesMessage))
+                peer.disconnect("failed to send unconfirmed transaction signatures");
+        } catch (DataException e) {
+            LOGGER.error(String.format("Repository issue while sending unconfirmed transaction signatures to peer %s", peer), e);
+        }
+    }
+
+    public void onNetworkTransactionSignaturesMessage(Peer peer, Message message) {
+        TransactionSignaturesMessage transactionSignaturesMessage = (TransactionSignaturesMessage) message;
+        List<byte[]> signatures = transactionSignaturesMessage.getSignatures();
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            for (byte[] signature : signatures) {
+                String signature58 = Base58.encode(signature);
+                if (invalidUnconfirmedTransactions.containsKey(signature58)) {
+                    // Previously invalid transaction - don't keep requesting it
+                    // It will be periodically removed from invalidUnconfirmedTransactions to allow for rechecks
+                    continue;
+                }
+
+                // Ignore if this transaction is in the queue
+                if (incomingTransactionQueueContains(signature)) {
+                    LOGGER.trace(() -> String.format("Ignoring existing queued transaction %s from peer %s", Base58.encode(signature), peer));
+                    continue;
+                }
+
+                // Do we have it already? (Before requesting transaction data itself)
+                if (repository.getTransactionRepository().exists(signature)) {
+                    LOGGER.trace(() -> String.format("Ignoring existing transaction %s from peer %s", Base58.encode(signature), peer));
+                    continue;
+                }
+
+                // Check isInterrupted() here and exit fast
+                if (Thread.currentThread().isInterrupted())
+                    return;
+
+                // Fetch actual transaction data from peer
+                Message getTransactionMessage = new GetTransactionMessage(signature);
+                if (!peer.sendMessage(getTransactionMessage)) {
+                    peer.disconnect("failed to request transaction");
+                    return;
+                }
+            }
+        } catch (DataException e) {
+            LOGGER.error(String.format("Repository issue while processing unconfirmed transactions from peer %s", peer), e);
+        }
+    }
+
+}

src/main/java/org/qortal/controller/arbitrary/ArbitraryDataCleanupManager.java

@@ -180,9 +180,6 @@ public class ArbitraryDataCleanupManager extends Thread {
 									arbitraryTransactionData.getName(), Base58.encode(signature)));
 
 							ArbitraryTransactionUtils.deleteCompleteFileAndChunks(arbitraryTransactionData);
-
-							// We should also remove peers for this transaction from the lookup table to save space
-							this.removePeersHostingTransactionData(repository, arbitraryTransactionData);
 							continue;
 						}
 
@@ -222,7 +219,11 @@ public class ArbitraryDataCleanupManager extends Thread {
 				try (final Repository repository = RepositoryManager.getRepository()) {
 
 					// Check if there are any hosted files that don't have matching transactions
-					this.checkForExpiredTransactions(repository);
+					// UPDATE: This has been disabled for now as it was deleting valid transactions
+					// and causing chunks to go missing on the network. If ever re-enabled, we MUST
+					// ensure that original copies of data aren't deleted, and that sufficient time
+					// is allowed (ideally several hours) before treating a transaction as missing.
+					// this.checkForExpiredTransactions(repository);
 
 					// Delete additional data at random if we're over our storage limit
 					// Use the DELETION_THRESHOLD so that we only start deleting once the hard limit is reached
@@ -433,16 +434,6 @@ public class ArbitraryDataCleanupManager extends Thread {
 		return false;
 	}
 
-	private void removePeersHostingTransactionData(Repository repository, ArbitraryTransactionData transactionData) {
-		byte[] signature = transactionData.getSignature();
-		try {
-			repository.getArbitraryRepository().deleteArbitraryPeersWithSignature(signature);
-			repository.saveChanges();
-		} catch (DataException e) {
-			LOGGER.debug("Unable to delete peers from lookup table for signature: {}", Base58.encode(signature));
-		}
-	}
-
 	private void cleanupTempDirectory(String folder, long now, long minAge) {
 		String baseDir = Settings.getInstance().getTempDataPath();
 		Path tempDir = Paths.get(baseDir, folder);

src/main/java/org/qortal/controller/arbitrary/ArbitraryDataFileListManager.java

@@ -5,6 +5,8 @@ import org.apache.logging.log4j.Logger;
 import org.qortal.arbitrary.ArbitraryDataFile;
 import org.qortal.arbitrary.ArbitraryDataFileChunk;
 import org.qortal.controller.Controller;
+import org.qortal.data.arbitrary.ArbitraryDirectConnectionInfo;
+import org.qortal.data.arbitrary.ArbitraryFileListResponseInfo;
 import org.qortal.data.arbitrary.ArbitraryRelayInfo;
 import org.qortal.data.transaction.ArbitraryTransactionData;
 import org.qortal.data.transaction.TransactionData;
@@ -23,12 +25,15 @@ import org.qortal.utils.Triple;
 
 import java.util.*;
 
+import static org.qortal.controller.arbitrary.ArbitraryDataFileManager.MAX_FILE_HASH_RESPONSES;
+
 public class ArbitraryDataFileListManager {
 
     private static final Logger LOGGER = LogManager.getLogger(ArbitraryDataFileListManager.class);
 
     private static ArbitraryDataFileListManager instance;
 
+    private static String MIN_PEER_VERSION_FOR_FILE_LIST_STATS = "3.2.0";
 
     /**
      * Map of recent incoming requests for ARBITRARY transaction data file lists.
@@ -58,9 +63,9 @@ public class ArbitraryDataFileListManager {
 
 
     /** Maximum number of seconds that a file list relay request is able to exist on the network */
-    private static long RELAY_REQUEST_MAX_DURATION = 5000L;
+    public static long RELAY_REQUEST_MAX_DURATION = 5000L;
     /** Maximum number of hops that a file list relay request is allowed to make */
-    private static int RELAY_REQUEST_MAX_HOPS = 4;
+    public static int RELAY_REQUEST_MAX_HOPS = 4;
 
 
     private ArbitraryDataFileListManager() {
@@ -263,25 +268,26 @@ public class ArbitraryDataFileListManager {
         }
         this.addToSignatureRequests(signature58, true, false);
 
-        List<Peer> handshakedPeers = Network.getInstance().getHandshakedPeers();
+        List<Peer> handshakedPeers = Network.getInstance().getImmutableHandshakedPeers();
         List<byte[]> missingHashes = null;
 
-//        // TODO: uncomment after GetArbitraryDataFileListMessage updates are deployed
-//        // Find hashes that we are missing
-//        try {
-//            ArbitraryDataFile arbitraryDataFile = ArbitraryDataFile.fromHash(digest, signature);
-//            arbitraryDataFile.setMetadataHash(metadataHash);
-//            missingHashes = arbitraryDataFile.missingHashes();
-//        } catch (DataException e) {
-//            // Leave missingHashes as null, so that all hashes are requested
-//        }
-//        int hashCount = missingHashes != null ? missingHashes.size() : 0;
+        // Find hashes that we are missing
+        try {
+            ArbitraryDataFile arbitraryDataFile = ArbitraryDataFile.fromHash(digest, signature);
+            arbitraryDataFile.setMetadataHash(metadataHash);
+            missingHashes = arbitraryDataFile.missingHashes();
+        } catch (DataException e) {
+            // Leave missingHashes as null, so that all hashes are requested
+        }
+        int hashCount = missingHashes != null ? missingHashes.size() : 0;
 
-        int hashCount = 0;
         LOGGER.debug(String.format("Sending data file list request for signature %s with %d hashes to %d peers...", signature58, hashCount, handshakedPeers.size()));
 
+        // FUTURE: send our address as requestingPeer once enough peers have switched to the new protocol
+        String requestingPeer = null; // Network.getInstance().getOurExternalIpAddressAndPort();
+
         // Build request
-        Message getArbitraryDataFileListMessage = new GetArbitraryDataFileListMessage(signature, missingHashes, now, 0);
+        Message getArbitraryDataFileListMessage = new GetArbitraryDataFileListMessage(signature, missingHashes, now, 0, requestingPeer);
 
         // Save our request into requests map
         Triple<String, Peer, Long> requestEntry = new Triple<>(signature58, null, NTP.getTime());
@@ -339,7 +345,7 @@ public class ArbitraryDataFileListManager {
         // This could be optimized in the future
         long timestamp = now - 60000L;
         List<byte[]> hashes = null;
-        Message getArbitraryDataFileListMessage = new GetArbitraryDataFileListMessage(signature, hashes, timestamp, 0);
+        Message getArbitraryDataFileListMessage = new GetArbitraryDataFileListMessage(signature, hashes, timestamp, 0, null);
 
         // Save our request into requests map
         Triple<String, Peer, Long> requestEntry = new Triple<>(signature58, null, NTP.getTime());
@@ -405,6 +411,13 @@ public class ArbitraryDataFileListManager {
         ArbitraryDataFileListMessage arbitraryDataFileListMessage = (ArbitraryDataFileListMessage) message;
         LOGGER.debug("Received hash list from peer {} with {} hashes", peer, arbitraryDataFileListMessage.getHashes().size());
 
+        if (LOGGER.isDebugEnabled() && arbitraryDataFileListMessage.getRequestTime() != null) {
+            long totalRequestTime = NTP.getTime() - arbitraryDataFileListMessage.getRequestTime();
+            LOGGER.debug("totalRequestTime: {}, requestHops: {}, peerAddress: {}, isRelayPossible: {}",
+                    totalRequestTime, arbitraryDataFileListMessage.getRequestHops(),
+                    arbitraryDataFileListMessage.getPeerAddress(), arbitraryDataFileListMessage.isRelayPossible());
+        }
+
         // Do we have a pending request for this data?
         Triple<String, Peer, Long> request = arbitraryDataFileListRequests.get(message.getId());
         if (request == null || request.getA() == null) {
@@ -425,7 +438,6 @@ public class ArbitraryDataFileListManager {
         }
 
         ArbitraryTransactionData arbitraryTransactionData = null;
-        ArbitraryDataFileManager arbitraryDataFileManager = ArbitraryDataFileManager.getInstance();
 
         // Check transaction exists and hashes are correct
         try (final Repository repository = RepositoryManager.getRepository()) {
@@ -452,16 +464,28 @@ public class ArbitraryDataFileListManager {
 //			}
 
             if (!isRelayRequest || !Settings.getInstance().isRelayModeEnabled()) {
-                // Keep track of the hashes this peer reports to have access to
                 Long now = NTP.getTime();
-                for (byte[] hash : hashes) {
-                    String hash58 = Base58.encode(hash);
-                    String sig58 = Base58.encode(signature);
-                    ArbitraryDataFileManager.getInstance().arbitraryDataFileHashResponses.put(hash58, new Triple<>(peer, sig58, now));
+
+                if (ArbitraryDataFileManager.getInstance().arbitraryDataFileHashResponses.size() < MAX_FILE_HASH_RESPONSES) {
+                    // Keep track of the hashes this peer reports to have access to
+                    for (byte[] hash : hashes) {
+                        String hash58 = Base58.encode(hash);
+
+                        // Treat null request hops as 100, so that they are able to be sorted (and put to the end of the list)
+                        int requestHops = arbitraryDataFileListMessage.getRequestHops() != null ? arbitraryDataFileListMessage.getRequestHops() : 100;
+
+                        ArbitraryFileListResponseInfo responseInfo = new ArbitraryFileListResponseInfo(hash58, signature58,
+                                peer, now, arbitraryDataFileListMessage.getRequestTime(), requestHops);
+
+                        ArbitraryDataFileManager.getInstance().arbitraryDataFileHashResponses.add(responseInfo);
+                    }
                 }
 
-                // Go and fetch the actual data, since this isn't a relay request
-                arbitraryDataFileManager.fetchArbitraryDataFiles(repository, peer, signature, arbitraryTransactionData, hashes);
+                // Keep track of the source peer, for direct connections
+                if (arbitraryDataFileListMessage.getPeerAddress() != null) {
+                    ArbitraryDataFileManager.getInstance().addDirectConnectionInfoIfUnique(
+                            new ArbitraryDirectConnectionInfo(signature, arbitraryDataFileListMessage.getPeerAddress(), hashes, now));
+                }
             }
 
         } catch (DataException e) {
@@ -474,17 +498,36 @@ public class ArbitraryDataFileListManager {
             if (!isBlocked) {
                 Peer requestingPeer = request.getB();
                 if (requestingPeer != null) {
+                    Long requestTime = arbitraryDataFileListMessage.getRequestTime();
+                    Integer requestHops = arbitraryDataFileListMessage.getRequestHops();
+
                     // Add each hash to our local mapping so we know who to ask later
                     Long now = NTP.getTime();
                     for (byte[] hash : hashes) {
                         String hash58 = Base58.encode(hash);
-                        ArbitraryRelayInfo relayMap = new ArbitraryRelayInfo(hash58, signature58, peer, now);
-                        ArbitraryDataFileManager.getInstance().addToRelayMap(relayMap);
+                        ArbitraryRelayInfo relayInfo = new ArbitraryRelayInfo(hash58, signature58, peer, now, requestTime, requestHops);
+                        ArbitraryDataFileManager.getInstance().addToRelayMap(relayInfo);
+                    }
+
+                    // Bump requestHops if it exists
+                    if (requestHops != null) {
+                        requestHops++;
+                    }
+
+                    ArbitraryDataFileListMessage forwardArbitraryDataFileListMessage;
+
+                    // Remove optional parameters if the requesting peer doesn't support it yet
+                    // A message with less statistical data is better than no message at all
+                    if (!requestingPeer.isAtLeastVersion(MIN_PEER_VERSION_FOR_FILE_LIST_STATS)) {
+                        forwardArbitraryDataFileListMessage = new ArbitraryDataFileListMessage(signature, hashes);
+                    } else {
+                        forwardArbitraryDataFileListMessage = new ArbitraryDataFileListMessage(signature, hashes, requestTime, requestHops,
+                                arbitraryDataFileListMessage.getPeerAddress(), arbitraryDataFileListMessage.isRelayPossible());
                     }
 
                     // Forward to requesting peer
                     LOGGER.debug("Forwarding file list with {} hashes to requesting peer: {}", hashes.size(), requestingPeer);
-                    if (!requestingPeer.sendMessage(arbitraryDataFileListMessage)) {
+                    if (!requestingPeer.sendMessage(forwardArbitraryDataFileListMessage)) {
                         requestingPeer.disconnect("failed to forward arbitrary data file list");
                     }
                 }
@@ -503,21 +546,30 @@ public class ArbitraryDataFileListManager {
         GetArbitraryDataFileListMessage getArbitraryDataFileListMessage = (GetArbitraryDataFileListMessage) message;
         byte[] signature = getArbitraryDataFileListMessage.getSignature();
         String signature58 = Base58.encode(signature);
-        List<byte[]> requestedHashes = getArbitraryDataFileListMessage.getHashes();
         Long now = NTP.getTime();
         Triple<String, Peer, Long> newEntry = new Triple<>(signature58, peer, now);
 
         // If we've seen this request recently, then ignore
         if (arbitraryDataFileListRequests.putIfAbsent(message.getId(), newEntry) != null) {
-            LOGGER.debug("Ignoring hash list request from peer {} for signature {}", peer, signature58);
+            LOGGER.trace("Ignoring hash list request from peer {} for signature {}", peer, signature58);
             return;
         }
 
-        LOGGER.debug("Received hash list request from peer {} for signature {}", peer, signature58);
+        List<byte[]> requestedHashes = getArbitraryDataFileListMessage.getHashes();
+        int hashCount = requestedHashes != null ? requestedHashes.size() : 0;
+        String requestingPeer = getArbitraryDataFileListMessage.getRequestingPeer();
+
+        if (requestingPeer != null) {
+            LOGGER.debug("Received hash list request with {} hashes from peer {} (requesting peer {}) for signature {}", hashCount, peer, requestingPeer, signature58);
+        }
+        else {
+            LOGGER.debug("Received hash list request with {} hashes from peer {} for signature {}", hashCount, peer, signature58);
+        }
 
         List<byte[]> hashes = new ArrayList<>();
         ArbitraryTransactionData transactionData = null;
         boolean allChunksExist = false;
+        boolean hasMetadata = false;
 
         try (final Repository repository = RepositoryManager.getRepository()) {
 
@@ -542,6 +594,7 @@ public class ArbitraryDataFileListManager {
                         // Add the metadata file
                         if (arbitraryDataFile.getMetadataHash() != null) {
                             requestedHashes.add(arbitraryDataFile.getMetadataHash());
+                            hasMetadata = true;
                         }
 
                         // Add the chunk hashes
@@ -574,6 +627,12 @@ public class ArbitraryDataFileListManager {
             LOGGER.error(String.format("Repository issue while fetching arbitrary file list for peer %s", peer), e);
         }
 
+        // If the only file we have is the metadata then we shouldn't respond. Most nodes will already have that,
+        // or can use the separate metadata protocol to fetch it. This should greatly reduce network spam.
+        if (hasMetadata && hashes.size() == 1) {
+            hashes.clear();
+        }
+
         // We should only respond if we have at least one hash
         if (hashes.size() > 0) {
 
@@ -584,8 +643,20 @@ public class ArbitraryDataFileListManager {
                 arbitraryDataFileListRequests.put(message.getId(), newEntry);
             }
 
-            ArbitraryDataFileListMessage arbitraryDataFileListMessage = new ArbitraryDataFileListMessage(signature, hashes);
+            String ourAddress = Network.getInstance().getOurExternalIpAddressAndPort();
+            ArbitraryDataFileListMessage arbitraryDataFileListMessage;
+
+            // Remove optional parameters if the requesting peer doesn't support it yet
+            // A message with less statistical data is better than no message at all
+            if (!peer.isAtLeastVersion(MIN_PEER_VERSION_FOR_FILE_LIST_STATS)) {
+                arbitraryDataFileListMessage = new ArbitraryDataFileListMessage(signature, hashes);
+            } else {
+                arbitraryDataFileListMessage = new ArbitraryDataFileListMessage(signature,
+                        hashes, NTP.getTime(), 0, ourAddress, true);
+            }
+
             arbitraryDataFileListMessage.setId(message.getId());
+
             if (!peer.sendMessage(arbitraryDataFileListMessage)) {
                 LOGGER.debug("Couldn't send list of hashes");
                 peer.disconnect("failed to send list of hashes");
@@ -607,8 +678,7 @@ public class ArbitraryDataFileListManager {
             // In relay mode - so ask our other peers if they have it
 
             long requestTime = getArbitraryDataFileListMessage.getRequestTime();
-            int requestHops = getArbitraryDataFileListMessage.getRequestHops();
-            getArbitraryDataFileListMessage.setRequestHops(++requestHops);
+            int requestHops = getArbitraryDataFileListMessage.getRequestHops() + 1;
             long totalRequestTime = now - requestTime;
 
             if (totalRequestTime < RELAY_REQUEST_MAX_DURATION) {
@@ -616,11 +686,13 @@ public class ArbitraryDataFileListManager {
                 if (requestHops < RELAY_REQUEST_MAX_HOPS) {
                     // Relay request hasn't reached the maximum number of hops yet, so can be rebroadcast
 
+                    Message relayGetArbitraryDataFileListMessage = new GetArbitraryDataFileListMessage(signature, hashes, requestTime, requestHops, requestingPeer);
+
                     LOGGER.debug("Rebroadcasting hash list request from peer {} for signature {} to our other peers... totalRequestTime: {}, requestHops: {}", peer, Base58.encode(signature), totalRequestTime, requestHops);
                     Network.getInstance().broadcast(
                             broadcastPeer -> broadcastPeer == peer ||
                                     Objects.equals(broadcastPeer.getPeerData().getAddress().getHost(), peer.getPeerData().getAddress().getHost())
-                                    ? null : getArbitraryDataFileListMessage);
+                                    ? null : relayGetArbitraryDataFileListMessage);
 
                 }
                 else {

src/main/java/org/qortal/controller/arbitrary/ArbitraryDataFileManager.java

@@ -4,8 +4,9 @@ import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.arbitrary.ArbitraryDataFile;
 import org.qortal.controller.Controller;
+import org.qortal.data.arbitrary.ArbitraryDirectConnectionInfo;
+import org.qortal.data.arbitrary.ArbitraryFileListResponseInfo;
 import org.qortal.data.arbitrary.ArbitraryRelayInfo;
-import org.qortal.data.network.ArbitraryPeerData;
 import org.qortal.data.network.PeerData;
 import org.qortal.data.transaction.ArbitraryTransactionData;
 import org.qortal.network.Network;
@@ -18,7 +19,6 @@ import org.qortal.settings.Settings;
 import org.qortal.utils.ArbitraryTransactionUtils;
 import org.qortal.utils.Base58;
 import org.qortal.utils.NTP;
-import org.qortal.utils.Triple;
 
 import java.security.SecureRandom;
 import java.util.*;
@@ -37,7 +37,7 @@ public class ArbitraryDataFileManager extends Thread {
     /**
      * Map to keep track of our in progress (outgoing) arbitrary data file requests
      */
-    private Map<String, Long> arbitraryDataFileRequests = Collections.synchronizedMap(new HashMap<>());
+    public Map<String, Long> arbitraryDataFileRequests = Collections.synchronizedMap(new HashMap<>());
 
     /**
      * Map to keep track of hashes that we might need to relay
@@ -45,11 +45,17 @@ public class ArbitraryDataFileManager extends Thread {
     public List<ArbitraryRelayInfo> arbitraryRelayMap = Collections.synchronizedList(new ArrayList<>());
 
     /**
-     * Map to keep track of any arbitrary data file hash responses
-     * Key: string - the hash encoded in base58
-     * Value: Triple<respondingPeer, signature58, timeResponded>
+     * List to keep track of any arbitrary data file hash responses
      */
-    public Map<String, Triple<Peer, String, Long>> arbitraryDataFileHashResponses = Collections.synchronizedMap(new HashMap<>());
+    public final List<ArbitraryFileListResponseInfo> arbitraryDataFileHashResponses = Collections.synchronizedList(new ArrayList<>());
+
+    /**
+     * List to keep track of peers potentially available for direct connections, based on recent requests
+     */
+    private List<ArbitraryDirectConnectionInfo> directConnectionInfo = Collections.synchronizedList(new ArrayList<>());
+
+
+    public static int MAX_FILE_HASH_RESPONSES = 1000;
 
 
     private ArbitraryDataFileManager() {
@@ -98,7 +104,10 @@ public class ArbitraryDataFileManager extends Thread {
 
         final long relayMinimumTimestamp = now - ArbitraryDataManager.getInstance().ARBITRARY_RELAY_TIMEOUT;
         arbitraryRelayMap.removeIf(entry -> entry == null || entry.getTimestamp() == null || entry.getTimestamp() < relayMinimumTimestamp);
-        arbitraryDataFileHashResponses.entrySet().removeIf(entry -> entry.getValue().getC() == null || entry.getValue().getC() < relayMinimumTimestamp);
+        arbitraryDataFileHashResponses.removeIf(entry -> entry.getTimestamp() < relayMinimumTimestamp);
+
+        final long directConnectionInfoMinimumTimestamp = now - ArbitraryDataManager.getInstance().ARBITRARY_DIRECT_CONNECTION_INFO_TIMEOUT;
+        directConnectionInfo.removeIf(entry -> entry.getTimestamp() < directConnectionInfoMinimumTimestamp);
     }
 
 
@@ -130,7 +139,7 @@ public class ArbitraryDataFileManager extends Thread {
                     Long startTime = NTP.getTime();
                     ArbitraryDataFileMessage receivedArbitraryDataFileMessage = fetchArbitraryDataFile(peer, null, signature, hash, null);
                     Long endTime = NTP.getTime();
-                    if (receivedArbitraryDataFileMessage != null) {
+                    if (receivedArbitraryDataFileMessage != null && receivedArbitraryDataFileMessage.getArbitraryDataFile() != null) {
                         LOGGER.debug("Received data file {} from peer {}. Time taken: {} ms", receivedArbitraryDataFileMessage.getArbitraryDataFile().getHash58(), peer, (endTime-startTime));
                         receivedAtLeastOneFile = true;
 
@@ -148,7 +157,7 @@ public class ArbitraryDataFileManager extends Thread {
                     }
                 }
                 else {
-                    LOGGER.trace("Already requesting data file {} for signature {}", arbitraryDataFile, Base58.encode(signature));
+                    LOGGER.trace("Already requesting data file {} for signature {} from peer {}", arbitraryDataFile, Base58.encode(signature), peer);
                 }
             }
             else {
@@ -158,16 +167,6 @@ public class ArbitraryDataFileManager extends Thread {
         }
 
         if (receivedAtLeastOneFile) {
-            // Update our lookup table to indicate that this peer holds data for this signature
-            String peerAddress = peer.getPeerData().getAddress().toString();
-            ArbitraryPeerData arbitraryPeerData = new ArbitraryPeerData(signature, peer);
-            repository.discardChanges();
-            if (arbitraryPeerData.isPeerAddressValid()) {
-                LOGGER.debug("Adding arbitrary peer: {} for signature {}", peerAddress, Base58.encode(signature));
-                repository.getArbitraryRepository().save(arbitraryPeerData);
-                repository.saveChanges();
-            }
-
             // Invalidate the hosted transactions cache as we are now hosting something new
             ArbitraryDataStorageManager.getInstance().invalidateHostedTransactionsCache();
 
@@ -177,16 +176,7 @@ public class ArbitraryDataFileManager extends Thread {
                 // We have all the chunks for this transaction, so we should invalidate the transaction's name's
                 // data cache so that it is rebuilt the next time we serve it
                 ArbitraryDataManager.getInstance().invalidateCache(arbitraryTransactionData);
-
-                // We may also need to broadcast to the network that we are now hosting files for this transaction,
-                // but only if these files are in accordance with our storage policy
-                if (ArbitraryDataStorageManager.getInstance().canStoreData(arbitraryTransactionData)) {
-                    // Use a null peer address to indicate our own
-                    Message newArbitrarySignatureMessage = new ArbitrarySignaturesMessage(null, 0, Arrays.asList(signature));
-                    Network.getInstance().broadcast(broadcastPeer -> newArbitrarySignatureMessage);
-                }
             }
-
         }
 
         return receivedAtLeastOneFile;
@@ -196,7 +186,7 @@ public class ArbitraryDataFileManager extends Thread {
         ArbitraryDataFile existingFile = ArbitraryDataFile.fromHash(hash, signature);
         boolean fileAlreadyExists = existingFile.exists();
         String hash58 = Base58.encode(hash);
-        Message message = null;
+        ArbitraryDataFileMessage arbitraryDataFileMessage;
 
         // Fetch the file if it doesn't exist locally
         if (!fileAlreadyExists) {
@@ -204,10 +194,11 @@ public class ArbitraryDataFileManager extends Thread {
             arbitraryDataFileRequests.put(hash58, NTP.getTime());
             Message getArbitraryDataFileMessage = new GetArbitraryDataFileMessage(signature, hash);
 
+            Message response = null;
             try {
-                message = peer.getResponseWithTimeout(getArbitraryDataFileMessage, (int) ArbitraryDataManager.ARBITRARY_REQUEST_TIMEOUT);
+                response = peer.getResponseWithTimeout(getArbitraryDataFileMessage, (int) ArbitraryDataManager.ARBITRARY_REQUEST_TIMEOUT);
             } catch (InterruptedException e) {
-                // Will return below due to null message
+                // Will return below due to null response
             }
             arbitraryDataFileRequests.remove(hash58);
             LOGGER.trace(String.format("Removed hash %.8s from arbitraryDataFileRequests", hash58));
@@ -215,22 +206,24 @@ public class ArbitraryDataFileManager extends Thread {
             // We may need to remove the file list request, if we have all the files for this transaction
             this.handleFileListRequests(signature);
 
-            if (message == null) {
-                LOGGER.debug("Received null message from peer {}", peer);
+            if (response == null) {
+                LOGGER.debug("Received null response from peer {}", peer);
                 return null;
             }
-            if (message.getType() != Message.MessageType.ARBITRARY_DATA_FILE) {
-                LOGGER.debug("Received message with invalid type: {} from peer {}", message.getType(), peer);
+            if (response.getType() != MessageType.ARBITRARY_DATA_FILE) {
+                LOGGER.debug("Received response with invalid type: {} from peer {}", response.getType(), peer);
                 return null;
             }
-        }
-        else {
+
+            ArbitraryDataFileMessage peersArbitraryDataFileMessage = (ArbitraryDataFileMessage) response;
+            arbitraryDataFileMessage = new ArbitraryDataFileMessage(signature, peersArbitraryDataFileMessage.getArbitraryDataFile());
+        } else {
             LOGGER.debug(String.format("File hash %s already exists, so skipping the request", hash58));
+            arbitraryDataFileMessage = new ArbitraryDataFileMessage(signature, existingFile);
         }
-        ArbitraryDataFileMessage arbitraryDataFileMessage = (ArbitraryDataFileMessage) message;
 
         // We might want to forward the request to the peer that originally requested it
-        this.handleArbitraryDataFileForwarding(requestingPeer, message, originalMessage);
+        this.handleArbitraryDataFileForwarding(requestingPeer, arbitraryDataFileMessage, originalMessage);
 
         boolean isRelayRequest = (requestingPeer != null);
         if (isRelayRequest) {
@@ -240,16 +233,7 @@ public class ArbitraryDataFileManager extends Thread {
                 ArbitraryDataFile dataFile = arbitraryDataFileMessage.getArbitraryDataFile();
 
                 // Keep trying to delete the data until it is deleted, or we reach 10 attempts
-                for (int i=0; i<10; i++) {
-                    if (dataFile.delete()) {
-                        break;
-                    }
-                    try {
-                        Thread.sleep(1000L);
-                    } catch (InterruptedException e) {
-                        // Fall through to exit method
-                    }
-                }
+                dataFile.delete(10);
             }
         }
 
@@ -305,89 +289,135 @@ public class ArbitraryDataFileManager extends Thread {
 
     // Fetch data directly from peers
 
+    private List<ArbitraryDirectConnectionInfo> getDirectConnectionInfoForSignature(byte[] signature) {
+        synchronized (directConnectionInfo) {
+            return directConnectionInfo.stream().filter(i -> Arrays.equals(i.getSignature(), signature)).collect(Collectors.toList());
+        }
+    }
+
+    /**
+     * Add an ArbitraryDirectConnectionInfo item, but only if one with this peer-signature combination
+     * doesn't already exist.
+     * @param connectionInfo - the direct connection info to add
+     */
+    public void addDirectConnectionInfoIfUnique(ArbitraryDirectConnectionInfo connectionInfo) {
+        boolean peerAlreadyExists;
+        synchronized (directConnectionInfo) {
+            peerAlreadyExists = directConnectionInfo.stream()
+                    .anyMatch(i -> Arrays.equals(i.getSignature(), connectionInfo.getSignature())
+                            && Objects.equals(i.getPeerAddress(), connectionInfo.getPeerAddress()));
+        }
+        if (!peerAlreadyExists) {
+            directConnectionInfo.add(connectionInfo);
+        }
+    }
+
+    private void removeDirectConnectionInfo(ArbitraryDirectConnectionInfo connectionInfo) {
+        this.directConnectionInfo.remove(connectionInfo);
+    }
+
     public boolean fetchDataFilesFromPeersForSignature(byte[] signature) {
         String signature58 = Base58.encode(signature);
-        ArbitraryDataFileListManager.getInstance().addToSignatureRequests(signature58, false, true);
 
-        // Firstly fetch peers that claim to be hosting files for this signature
-        try (final Repository repository = RepositoryManager.getRepository()) {
+        boolean success = false;
 
-            List<ArbitraryPeerData> peers = repository.getArbitraryRepository().getArbitraryPeerDataForSignature(signature);
-            if (peers == null || peers.isEmpty()) {
-                LOGGER.debug("No peers found for signature {}", signature58);
-                return false;
-            }
-
-            LOGGER.debug("Attempting a direct peer connection for signature {}...", signature58);
-
-            // Peers found, so pick a random one and request data from it
-            int index = new SecureRandom().nextInt(peers.size());
-            ArbitraryPeerData arbitraryPeerData = peers.get(index);
-            String peerAddressString = arbitraryPeerData.getPeerAddress();
-            boolean success = Network.getInstance().requestDataFromPeer(peerAddressString, signature);
-
-            // Parse the peer address to find the host and port
-            String host = null;
-            int port = -1;
-            String[] parts = peerAddressString.split(":");
-            if (parts.length > 1) {
-                host = parts[0];
-                port = Integer.parseInt(parts[1]);
-            }
-
-            // If unsuccessful, and using a non-standard port, try a second connection with the default listen port,
-            // since almost all nodes use that. This is a workaround to account for any ephemeral ports that may
-            // have made it into the dataset.
-            if (!success) {
-                if (host != null && port > 0) {
-                    int defaultPort = Settings.getInstance().getDefaultListenPort();
-                    if (port != defaultPort) {
-                        String newPeerAddressString = String.format("%s:%d", host, defaultPort);
-                        success = Network.getInstance().requestDataFromPeer(newPeerAddressString, signature);
-                    }
+        try {
+            while (!success) {
+                if (isStopping) {
+                    return false;
                 }
-            }
+                Thread.sleep(500L);
 
-            // If _still_ unsuccessful, try matching the peer's IP address with some known peers, and then connect
-            // to each of those in turn until one succeeds.
-            if (!success) {
-                if (host != null) {
-                    final String finalHost = host;
-                    List<PeerData> knownPeers = Network.getInstance().getAllKnownPeers().stream()
-                            .filter(knownPeerData -> knownPeerData.getAddress().getHost().equals(finalHost))
-                            .collect(Collectors.toList());
-                    // Loop through each match and attempt a connection
-                    for (PeerData matchingPeer : knownPeers) {
-                        String matchingPeerAddress = matchingPeer.getAddress().toString();
-                        success = Network.getInstance().requestDataFromPeer(matchingPeerAddress, signature);
-                        if (success) {
-                            // Successfully connected, so stop making connections
-                            break;
+                // Firstly fetch peers that claim to be hosting files for this signature
+                List<ArbitraryDirectConnectionInfo> connectionInfoList = getDirectConnectionInfoForSignature(signature);
+                if (connectionInfoList == null || connectionInfoList.isEmpty()) {
+                    LOGGER.debug("No remaining direct connection peers found for signature {}", signature58);
+                    return false;
+                }
+
+                LOGGER.debug("Attempting a direct peer connection for signature {}...", signature58);
+
+                // Peers found, so pick one with the highest number of chunks
+                Comparator<ArbitraryDirectConnectionInfo> highestChunkCountFirstComparator =
+                        Comparator.comparingInt(ArbitraryDirectConnectionInfo::getHashCount).reversed();
+                ArbitraryDirectConnectionInfo directConnectionInfo = connectionInfoList.stream()
+                        .sorted(highestChunkCountFirstComparator).findFirst().orElse(null);
+
+                if (directConnectionInfo == null) {
+                    return false;
+                }
+
+                // Remove from the list so that a different peer is tried next time
+                removeDirectConnectionInfo(directConnectionInfo);
+
+                String peerAddressString = directConnectionInfo.getPeerAddress();
+
+                // Parse the peer address to find the host and port
+                String host = null;
+                int port = -1;
+                String[] parts = peerAddressString.split(":");
+                if (parts.length > 1) {
+                    host = parts[0];
+                    port = Integer.parseInt(parts[1]);
+                } else {
+                    // Assume no port included
+                    host = peerAddressString;
+                    // Use default listen port
+                    port = Settings.getInstance().getDefaultListenPort();
+                }
+
+                String peerAddressStringWithPort = String.format("%s:%d", host, port);
+                success = Network.getInstance().requestDataFromPeer(peerAddressStringWithPort, signature);
+
+                int defaultPort = Settings.getInstance().getDefaultListenPort();
+
+                // If unsuccessful, and using a non-standard port, try a second connection with the default listen port,
+                // since almost all nodes use that. This is a workaround to account for any ephemeral ports that may
+                // have made it into the dataset.
+                if (!success) {
+                    if (host != null && port > 0) {
+                        if (port != defaultPort) {
+                            String newPeerAddressString = String.format("%s:%d", host, defaultPort);
+                            success = Network.getInstance().requestDataFromPeer(newPeerAddressString, signature);
                         }
                     }
                 }
-            }
 
-            // Keep track of the success or failure
-            arbitraryPeerData.markAsAttempted();
-            if (success) {
-                arbitraryPeerData.markAsRetrieved();
-                arbitraryPeerData.incrementSuccesses();
-            }
-            else {
-                arbitraryPeerData.incrementFailures();
-            }
-            repository.discardChanges();
-            repository.getArbitraryRepository().save(arbitraryPeerData);
-            repository.saveChanges();
+                // If _still_ unsuccessful, try matching the peer's IP address with some known peers, and then connect
+                // to each of those in turn until one succeeds.
+                if (!success) {
+                    if (host != null) {
+                        final String finalHost = host;
+                        List<PeerData> knownPeers = Network.getInstance().getAllKnownPeers().stream()
+                                .filter(knownPeerData -> knownPeerData.getAddress().getHost().equals(finalHost))
+                                .collect(Collectors.toList());
+                        // Loop through each match and attempt a connection
+                        for (PeerData matchingPeer : knownPeers) {
+                            String matchingPeerAddress = matchingPeer.getAddress().toString();
+                            int matchingPeerPort = matchingPeer.getAddress().getPort();
+                            // Make sure that it's not a port we've already tried
+                            if (matchingPeerPort != port && matchingPeerPort != defaultPort) {
+                                success = Network.getInstance().requestDataFromPeer(matchingPeerAddress, signature);
+                                if (success) {
+                                    // Successfully connected, so stop making connections
+                                    break;
+                                }
+                            }
+                        }
+                    }
+                }
 
-            return success;
+                if (success) {
+                    // We were able to connect with a peer, so track the request
+                    ArbitraryDataFileListManager.getInstance().addToSignatureRequests(signature58, false, true);
+                }
 
-        } catch (DataException e) {
-            LOGGER.debug("Unable to fetch peer list from repository");
+            }
+        } catch (InterruptedException e) {
+            // Do nothing
         }
 
-        return false;
+        return success;
     }
 
 
@@ -401,6 +431,33 @@ public class ArbitraryDataFileManager extends Thread {
         }
     }
 
+    private ArbitraryRelayInfo getOptimalRelayInfoEntryForHash(String hash58) {
+        LOGGER.trace("Fetching relay info for hash: {}", hash58);
+        List<ArbitraryRelayInfo> relayInfoList = this.getRelayInfoListForHash(hash58);
+        if (relayInfoList != null && !relayInfoList.isEmpty()) {
+
+            // Remove any with null requestHops
+            relayInfoList.removeIf(r -> r.getRequestHops() == null);
+
+            // If list is now empty, then just return one at random
+            if (relayInfoList.isEmpty()) {
+                return this.getRandomRelayInfoEntryForHash(hash58);
+            }
+
+            // Sort by number of hops (lowest first)
+            relayInfoList.sort(Comparator.comparingInt(ArbitraryRelayInfo::getRequestHops));
+
+            // FUTURE: secondary sort by requestTime?
+
+            ArbitraryRelayInfo relayInfo = relayInfoList.get(0);
+
+            LOGGER.trace("Returning optimal relay info for hash: {} (requestHops {})", hash58, relayInfo.getRequestHops());
+            return relayInfo;
+        }
+        LOGGER.trace("No relay info exists for hash: {}", hash58);
+        return null;
+    }
+
     private ArbitraryRelayInfo getRandomRelayInfoEntryForHash(String hash58) {
         LOGGER.trace("Fetching random relay info for hash: {}", hash58);
         List<ArbitraryRelayInfo> relayInfoList = this.getRelayInfoListForHash(hash58);
@@ -451,7 +508,7 @@ public class ArbitraryDataFileManager extends Thread {
 
         try {
             ArbitraryDataFile arbitraryDataFile = ArbitraryDataFile.fromHash(hash, signature);
-            ArbitraryRelayInfo relayInfo = this.getRandomRelayInfoEntryForHash(hash58);
+            ArbitraryRelayInfo relayInfo = this.getOptimalRelayInfoEntryForHash(hash58);
 
             if (arbitraryDataFile.exists()) {
                 LOGGER.trace("Hash {} exists", hash58);

src/main/java/org/qortal/controller/arbitrary/ArbitraryDataFileRequestThread.java

@@ -3,6 +3,7 @@ package org.qortal.controller.arbitrary;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.controller.Controller;
+import org.qortal.data.arbitrary.ArbitraryFileListResponseInfo;
 import org.qortal.data.transaction.ArbitraryTransactionData;
 import org.qortal.network.Peer;
 import org.qortal.repository.DataException;
@@ -11,11 +12,9 @@ import org.qortal.repository.RepositoryManager;
 import org.qortal.utils.ArbitraryTransactionUtils;
 import org.qortal.utils.Base58;
 import org.qortal.utils.NTP;
-import org.qortal.utils.Triple;
 
-import java.util.Arrays;
-import java.util.Iterator;
-import java.util.Map;
+import java.util.*;
+import java.util.stream.Collectors;
 
 public class ArbitraryDataFileRequestThread implements Runnable {
 
@@ -31,8 +30,6 @@ public class ArbitraryDataFileRequestThread implements Runnable {
 
         try {
             while (!Controller.isStopping()) {
-                Thread.sleep(1000);
-
                 Long now = NTP.getTime();
                 this.processFileHashes(now);
             }
@@ -41,7 +38,7 @@ public class ArbitraryDataFileRequestThread implements Runnable {
         }
     }
 
-    private void processFileHashes(Long now) {
+    private void processFileHashes(Long now) throws InterruptedException {
 		if (Controller.isStopping()) {
             return;
         }
@@ -53,44 +50,53 @@ public class ArbitraryDataFileRequestThread implements Runnable {
         boolean shouldProcess = false;
 
         synchronized (arbitraryDataFileManager.arbitraryDataFileHashResponses) {
-            Iterator iterator = arbitraryDataFileManager.arbitraryDataFileHashResponses.entrySet().iterator();
-            while (iterator.hasNext()) {
-                if (Controller.isStopping()) {
-                    return;
-                }
+            if (!arbitraryDataFileManager.arbitraryDataFileHashResponses.isEmpty()) {
 
-                Map.Entry entry = (Map.Entry) iterator.next();
-                if (entry == null || entry.getKey() == null || entry.getValue() == null) {
+                // Sort by lowest number of node hops first
+                Comparator<ArbitraryFileListResponseInfo> lowestHopsFirstComparator =
+                        Comparator.comparingInt(ArbitraryFileListResponseInfo::getRequestHops);
+                arbitraryDataFileManager.arbitraryDataFileHashResponses.sort(lowestHopsFirstComparator);
+
+                Iterator iterator = arbitraryDataFileManager.arbitraryDataFileHashResponses.iterator();
+                while (iterator.hasNext()) {
+                    if (Controller.isStopping()) {
+                        return;
+                    }
+
+                    ArbitraryFileListResponseInfo responseInfo = (ArbitraryFileListResponseInfo) iterator.next();
+                    if (responseInfo == null) {
+                        iterator.remove();
+                        continue;
+                    }
+
+                    hash58 = responseInfo.getHash58();
+                    peer = responseInfo.getPeer();
+                    signature58 = responseInfo.getSignature58();
+                    Long timestamp = responseInfo.getTimestamp();
+
+                    if (now - timestamp >= ArbitraryDataManager.ARBITRARY_RELAY_TIMEOUT || signature58 == null || peer == null) {
+                        // Ignore - to be deleted
+                        iterator.remove();
+                        continue;
+                    }
+
+                    // Skip if already requesting, but don't remove, as we might want to retry later
+                    if (arbitraryDataFileManager.arbitraryDataFileRequests.containsKey(hash58)) {
+                        // Already requesting - leave this attempt for later
+                        continue;
+                    }
+
+                    // We want to process this file
+                    shouldProcess = true;
                     iterator.remove();
-                    continue;
+                    break;
                 }
-
-                hash58 = (String) entry.getKey();
-                Triple<Peer, String, Long> value = (Triple<Peer, String, Long>) entry.getValue();
-                if (value == null) {
-                    iterator.remove();
-                    continue;
-                }
-
-                peer = value.getA();
-                signature58 = value.getB();
-                Long timestamp = value.getC();
-
-                if (now - timestamp >= ArbitraryDataManager.ARBITRARY_RELAY_TIMEOUT || signature58 == null || peer == null) {
-                    // Ignore - to be deleted
-                    iterator.remove();
-                    continue;
-                }
-
-                // We want to process this file
-                shouldProcess = true;
-                iterator.remove();
-                break;
             }
         }
 
         if (!shouldProcess) {
             // Nothing to do
+            Thread.sleep(1000L);
             return;
         }
 

src/main/java/org/qortal/controller/arbitrary/ArbitraryDataManager.java

@@ -1,23 +1,24 @@
 package org.qortal.controller.arbitrary;
 
 import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
 import java.util.*;
-import java.util.stream.Collectors;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.api.resource.TransactionsResource.ConfirmationStatus;
 import org.qortal.arbitrary.ArbitraryDataFile;
 import org.qortal.arbitrary.ArbitraryDataResource;
+import org.qortal.arbitrary.metadata.ArbitraryDataTransactionMetadata;
 import org.qortal.arbitrary.misc.Service;
 import org.qortal.controller.Controller;
-import org.qortal.data.network.ArbitraryPeerData;
 import org.qortal.data.transaction.ArbitraryTransactionData;
 import org.qortal.data.transaction.TransactionData;
 import org.qortal.list.ResourceListManager;
 import org.qortal.network.Network;
 import org.qortal.network.Peer;
-import org.qortal.network.message.*;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryManager;
@@ -38,14 +39,23 @@ public class ArbitraryDataManager extends Thread {
 	private int powDifficulty = 14; // Must not be final, as unit tests need to reduce this value
 
 	/** Request timeout when transferring arbitrary data */
-	public static final long ARBITRARY_REQUEST_TIMEOUT = 10 * 1000L; // ms
+	public static final long ARBITRARY_REQUEST_TIMEOUT = 12 * 1000L; // ms
 
 	/** Maximum time to hold information about an in-progress relay */
 	public static final long ARBITRARY_RELAY_TIMEOUT = 60 * 1000L; // ms
 
+	/** Maximum time to hold direct peer connection information */
+	public static final long ARBITRARY_DIRECT_CONNECTION_INFO_TIMEOUT = 2 * 60 * 1000L; // ms
+
 	/** Maximum number of hops that an arbitrary signatures request is allowed to make */
 	private static int ARBITRARY_SIGNATURES_REQUEST_MAX_HOPS = 3;
 
+	private long lastMetadataFetchTime = 0L;
+	private static long METADATA_FETCH_INTERVAL = 5 * 60 * 1000L;
+
+	private long lastDataFetchTime = 0L;
+	private static long DATA_FETCH_INTERVAL = 1 * 60 * 1000L;
+
 	private static ArbitraryDataManager instance;
 	private final Object peerDataLock = new Object();
 
@@ -79,7 +89,13 @@ public class ArbitraryDataManager extends Thread {
 	public void run() {
 		Thread.currentThread().setName("Arbitrary Data Manager");
 
+		// Create data directory in case it doesn't exist yet
+		this.createDataDirectory();
+
 		try {
+			// Wait for node to finish starting up and making connections
+			Thread.sleep(2 * 60 * 1000L);
+
 			while (!isStopping) {
 				Thread.sleep(2000);
 
@@ -89,7 +105,13 @@ public class ArbitraryDataManager extends Thread {
 					continue;
 				}
 
-				List<Peer> peers = Network.getInstance().getHandshakedPeers();
+				Long now = NTP.getTime();
+				if (now == null) {
+					continue;
+				}
+
+				// Needs a mutable copy of the unmodifiableList
+				List<Peer> peers = new ArrayList<>(Network.getInstance().getImmutableHandshakedPeers());
 
 				// Disregard peers that have "misbehaved" recently
 				peers.removeIf(Controller.hasMisbehaved);
@@ -99,6 +121,21 @@ public class ArbitraryDataManager extends Thread {
 					continue;
 				}
 
+				// Fetch metadata
+				if (NTP.getTime() - lastMetadataFetchTime >= METADATA_FETCH_INTERVAL) {
+					this.fetchAllMetadata();
+					lastMetadataFetchTime = NTP.getTime();
+				}
+
+				// Check if we need to fetch any data
+				if (NTP.getTime() - lastDataFetchTime < DATA_FETCH_INTERVAL) {
+					// Nothing to do yet
+					continue;
+				}
+
+				// In case the data directory has been deleted...
+				this.createDataDirectory();
+
 				// Fetch data according to storage policy
 				switch (Settings.getInstance().getStoragePolicy()) {
 					case FOLLOWED:
@@ -108,6 +145,7 @@ public class ArbitraryDataManager extends Thread {
 
 					case ALL:
 						this.processAll();
+						break;
 
 					case NONE:
 					case VIEWED:
@@ -116,6 +154,8 @@ public class ArbitraryDataManager extends Thread {
 						Thread.sleep(60000);
 						break;
 				}
+
+				lastDataFetchTime = NTP.getTime();
 			}
 		} catch (InterruptedException e) {
 			// Fall-through to exit thread...
@@ -127,7 +167,7 @@ public class ArbitraryDataManager extends Thread {
 		this.interrupt();
 	}
 
-	private void processNames() {
+	private void processNames() throws InterruptedException {
 		// Fetch latest list of followed names
 		List<String> followedNames = ResourceListManager.getInstance().getStringsInList("followedNames");
 		if (followedNames == null || followedNames.isEmpty()) {
@@ -140,11 +180,11 @@ public class ArbitraryDataManager extends Thread {
 		}
 	}
 
-	private void processAll() {
+	private void processAll() throws InterruptedException {
 		this.fetchAndProcessTransactions(null);
 	}
 
-	private void fetchAndProcessTransactions(String name) {
+	private void fetchAndProcessTransactions(String name) throws InterruptedException {
 		ArbitraryDataStorageManager storageManager = ArbitraryDataStorageManager.getInstance();
 
 		// Paginate queries when fetching arbitrary transactions
@@ -152,6 +192,7 @@ public class ArbitraryDataManager extends Thread {
 		int offset = 0;
 
 		while (!isStopping) {
+			Thread.sleep(1000L);
 
 			// Any arbitrary transactions we want to fetch data for?
 			try (final Repository repository = RepositoryManager.getRepository()) {
@@ -166,6 +207,7 @@ public class ArbitraryDataManager extends Thread {
 				// Loop through signatures and remove ones we don't need to process
 				Iterator iterator = signatures.iterator();
 				while (iterator.hasNext()) {
+					Thread.sleep(25L); // Reduce CPU usage
 					byte[] signature = (byte[]) iterator.next();
 
 					ArbitraryTransaction arbitraryTransaction = fetchTransaction(repository, signature);
@@ -222,6 +264,85 @@ public class ArbitraryDataManager extends Thread {
 		}
 	}
 
+	private void fetchAllMetadata() throws InterruptedException {
+		ArbitraryDataStorageManager storageManager = ArbitraryDataStorageManager.getInstance();
+
+		// Paginate queries when fetching arbitrary transactions
+		final int limit = 100;
+		int offset = 0;
+
+		while (!isStopping) {
+			Thread.sleep(1000L);
+
+			// Any arbitrary transactions we want to fetch data for?
+			try (final Repository repository = RepositoryManager.getRepository()) {
+				List<byte[]> signatures = repository.getTransactionRepository().getSignaturesMatchingCriteria(null, null, null, ARBITRARY_TX_TYPE, null, null, null, ConfirmationStatus.BOTH, limit, offset, true);
+				// LOGGER.trace("Found {} arbitrary transactions at offset: {}, limit: {}", signatures.size(), offset, limit);
+				if (signatures == null || signatures.isEmpty()) {
+					offset = 0;
+					break;
+				}
+				offset += limit;
+
+				// Loop through signatures and remove ones we don't need to process
+				Iterator iterator = signatures.iterator();
+				while (iterator.hasNext()) {
+					Thread.sleep(25L); // Reduce CPU usage
+					byte[] signature = (byte[]) iterator.next();
+
+					ArbitraryTransaction arbitraryTransaction = fetchTransaction(repository, signature);
+					if (arbitraryTransaction == null) {
+						// Best not to process this one
+						iterator.remove();
+						continue;
+					}
+					ArbitraryTransactionData arbitraryTransactionData = (ArbitraryTransactionData) arbitraryTransaction.getTransactionData();
+
+					// Skip transactions that are blocked
+					if (storageManager.isBlocked(arbitraryTransactionData)) {
+						iterator.remove();
+						continue;
+					}
+
+					// Remove transactions that we already have local data for
+					if (hasLocalMetadata(arbitraryTransaction)) {
+						iterator.remove();
+						continue;
+					}
+				}
+
+				if (signatures.isEmpty()) {
+					continue;
+				}
+
+				// Pick one at random
+				final int index = new Random().nextInt(signatures.size());
+				byte[] signature = signatures.get(index);
+
+				if (signature == null) {
+					continue;
+				}
+
+				// Check to see if we have had a more recent PUT
+				ArbitraryTransactionData arbitraryTransactionData = ArbitraryTransactionUtils.fetchTransactionData(repository, signature);
+				boolean hasMoreRecentPutTransaction = ArbitraryTransactionUtils.hasMoreRecentPutTransaction(repository, arbitraryTransactionData);
+				if (hasMoreRecentPutTransaction) {
+					// There is a more recent PUT transaction than the one we are currently processing.
+					// When a PUT is issued, it replaces any layers that would have been there before.
+					// Therefore any data relating to this older transaction is no longer needed and we
+					// shouldn't fetch it from the network.
+					continue;
+				}
+
+				// Ask our connected peers if they have metadata for this signature
+				fetchMetadata(arbitraryTransactionData);
+
+			} catch (DataException e) {
+				LOGGER.error("Repository issue when fetching arbitrary transaction data", e);
+			}
+		}
+	}
+
 	private ArbitraryTransaction fetchTransaction(final Repository repository, byte[] signature) {
 		try {
 			TransactionData transactionData = repository.getTransactionRepository().fromSignature(signature);
@@ -241,16 +362,48 @@ public class ArbitraryDataManager extends Thread {
 
 		} catch (DataException e) {
 			LOGGER.error("Repository issue when checking arbitrary transaction's data is local", e);
-			return true;
+			return true; // Assume true for now, to avoid network spam on error
 		}
 	}
 
+	private boolean hasLocalMetadata(ArbitraryTransaction arbitraryTransaction) {
+		try {
+			ArbitraryTransactionData arbitraryTransactionData = (ArbitraryTransactionData) arbitraryTransaction.getTransactionData();
+			byte[] signature = arbitraryTransactionData.getSignature();
+			byte[] metadataHash = arbitraryTransactionData.getMetadataHash();
+
+			if (metadataHash == null) {
+				// This transaction doesn't have metadata associated with it, so return true to indicate that we have everything
+				return true;
+			}
+
+			ArbitraryDataFile metadataFile = ArbitraryDataFile.fromHash(metadataHash, signature);
+
+			return metadataFile.exists();
+
+		} catch (DataException e) {
+			LOGGER.error("Repository issue when checking arbitrary transaction's metadata is local", e);
+			return true; // Assume true for now, to avoid network spam on error
+		}
+	}
 
 	// Entrypoint to request new data from peers
 	public boolean fetchData(ArbitraryTransactionData arbitraryTransactionData) {
 		return ArbitraryDataFileListManager.getInstance().fetchArbitraryDataFileList(arbitraryTransactionData);
 	}
 
+	// Entrypoint to request new metadata from peers
+	public ArbitraryDataTransactionMetadata fetchMetadata(ArbitraryTransactionData arbitraryTransactionData) {
+
+		ArbitraryDataResource resource = new ArbitraryDataResource(
+				arbitraryTransactionData.getName(),
+				ArbitraryDataFile.ResourceIdType.NAME,
+				arbitraryTransactionData.getService(),
+				arbitraryTransactionData.getIdentifier()
+		);
+		return ArbitraryMetadataManager.getInstance().fetchMetadata(resource, true);
+	}
+
 
 	// Useful methods used by other parts of the app
 
@@ -275,6 +428,9 @@ public class ArbitraryDataManager extends Thread {
 
 		// Cleanup file request caches
 		ArbitraryDataFileManager.getInstance().cleanupRequestCache(now);
+
+		// Clean up metadata request caches
+		ArbitraryMetadataManager.getInstance().cleanupRequestCache(now);
 	}
 
 	public boolean isResourceCached(ArbitraryDataResource resource) {
@@ -362,95 +518,19 @@ public class ArbitraryDataManager extends Thread {
 		}
 	}
 
-
-	// Broadcast list of hosted signatures
-
-	public void broadcastHostedSignatureList() {
-		try (final Repository repository = RepositoryManager.getRepository()) {
-			List<ArbitraryTransactionData> hostedTransactions = ArbitraryDataStorageManager.getInstance().listAllHostedTransactions(repository, null, null);
-			List<byte[]> hostedSignatures = hostedTransactions.stream().map(ArbitraryTransactionData::getSignature).collect(Collectors.toList());
-			if (!hostedSignatures.isEmpty()) {
-				// Broadcast the list, using null to represent our peer address
-				LOGGER.info("Broadcasting list of hosted signatures...");
-				Message arbitrarySignatureMessage = new ArbitrarySignaturesMessage(null, 0, hostedSignatures);
-				Network.getInstance().broadcast(broadcastPeer -> arbitrarySignatureMessage);
-			}
-		} catch (DataException e) {
-			LOGGER.error("Repository issue when fetching arbitrary transaction data for broadcast", e);
+	private boolean createDataDirectory() {
+		// Create the data directory if it doesn't exist
+		String dataPath = Settings.getInstance().getDataPath();
+		Path dataDirectory = Paths.get(dataPath);
+		try {
+			Files.createDirectories(dataDirectory);
+		} catch (IOException e) {
+			LOGGER.error("Unable to create data directory");
+			return false;
 		}
+		return true;
 	}
 
-
-	// Handle incoming arbitrary signatures messages
-
-	public void onNetworkArbitrarySignaturesMessage(Peer peer, Message message) {
-		// Don't process if QDN is disabled
-		if (!Settings.getInstance().isQdnEnabled()) {
-			return;
-		}
-
-		LOGGER.debug("Received arbitrary signature list from peer {}", peer);
-
-		ArbitrarySignaturesMessage arbitrarySignaturesMessage = (ArbitrarySignaturesMessage) message;
-		List<byte[]> signatures = arbitrarySignaturesMessage.getSignatures();
-
-		String peerAddress = peer.getPeerData().getAddress().toString();
-		if (arbitrarySignaturesMessage.getPeerAddress() != null && !arbitrarySignaturesMessage.getPeerAddress().isEmpty()) {
-			// This message is about a different peer than the one that sent it
-			peerAddress = arbitrarySignaturesMessage.getPeerAddress();
-		}
-
-		boolean containsNewEntry = false;
-
-		// Synchronize peer data lookups to make this process thread safe. Otherwise we could broadcast
-		// the same data multiple times, due to more than one thread processing the same message from different peers
-		synchronized (this.peerDataLock) {
-			try (final Repository repository = RepositoryManager.getRepository()) {
-				for (byte[] signature : signatures) {
-
-					// Check if a record already exists for this hash/host combination
-					// The port is not checked here - only the host/ip - in order to avoid duplicates
-					// from filling up the db due to dynamic/ephemeral ports
-					ArbitraryPeerData existingEntry = repository.getArbitraryRepository()
-							.getArbitraryPeerDataForSignatureAndHost(signature, peer.getPeerData().getAddress().getHost());
-
-					if (existingEntry == null) {
-						// We haven't got a record of this mapping yet, so add it
-						ArbitraryPeerData arbitraryPeerData = new ArbitraryPeerData(signature, peerAddress);
-						repository.discardChanges();
-						if (arbitraryPeerData.isPeerAddressValid()) {
-							LOGGER.debug("Adding arbitrary peer: {} for signature {}", peerAddress, Base58.encode(signature));
-							repository.getArbitraryRepository().save(arbitraryPeerData);
-							repository.saveChanges();
-
-							// Remember that this data is new, so that it can be rebroadcast later
-							containsNewEntry = true;
-						}
-					}
-				}
-
-				// If at least one signature in this batch was new to us, we should rebroadcast the message to the
-				// network in case some peers haven't received it yet
-				if (containsNewEntry) {
-					int requestHops = arbitrarySignaturesMessage.getRequestHops();
-					arbitrarySignaturesMessage.setRequestHops(++requestHops);
-					if (requestHops < ARBITRARY_SIGNATURES_REQUEST_MAX_HOPS) {
-						LOGGER.debug("Rebroadcasting arbitrary signature list for peer {}. requestHops: {}", peerAddress, requestHops);
-						Network.getInstance().broadcast(broadcastPeer -> broadcastPeer == peer ? null : arbitrarySignaturesMessage);
-					}
-				} else {
-					// Don't rebroadcast as otherwise we could get into a loop
-				}
-
-				// If anything needed saving, it would already have called saveChanges() above
-				repository.discardChanges();
-			} catch (DataException e) {
-				LOGGER.error(String.format("Repository issue while processing arbitrary transaction signature list from peer %s", peer), e);
-			}
-		}
-	}
-
-
 	public int getPowDifficulty() {
 		return this.powDifficulty;
 	}

src/main/java/org/qortal/controller/arbitrary/ArbitraryDataStorageManager.java

@@ -16,6 +16,7 @@ import org.qortal.utils.FilesystemUtils;
 import org.qortal.utils.NTP;
 
 import java.io.IOException;
+import java.io.UncheckedIOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
@@ -46,6 +47,9 @@ public class ArbitraryDataStorageManager extends Thread {
 
     private List<ArbitraryTransactionData> hostedTransactions;
 
+    private String searchQuery;
+    private List<ArbitraryTransactionData> searchResultsTransactions;
+
     private static final long DIRECTORY_SIZE_CHECK_INTERVAL = 10 * 60 * 1000L; // 10 minutes
 
     /** Treat storage as full at 90% usage, to reduce risk of going over the limit.
@@ -225,6 +229,16 @@ public class ArbitraryDataStorageManager extends Thread {
         }
     }
 
+    /**
+     * Check if data relating to a transaction is blocked by this node.
+     *
+     * @param arbitraryTransactionData - the transaction
+     * @return boolean - whether the resource is blocked or not
+     */
+    public boolean isBlocked(ArbitraryTransactionData arbitraryTransactionData) {
+        return isNameBlocked(arbitraryTransactionData.getName());
+    }
+
     private boolean isDataTypeAllowed(ArbitraryTransactionData arbitraryTransactionData) {
         byte[] secret = arbitraryTransactionData.getSecret();
         boolean hasSecret = (secret != null && secret.length == 32);
@@ -257,14 +271,8 @@ public class ArbitraryDataStorageManager extends Thread {
     }
 
 
-    // Hosted data
-
-    public List<ArbitraryTransactionData> listAllHostedTransactions(Repository repository, Integer limit, Integer offset) {
-        // Load from cache if we can, to avoid disk reads
-        if (this.hostedTransactions != null) {
-            return ArbitraryTransactionUtils.limitOffsetTransactions(this.hostedTransactions, limit, offset);
-        }
-
+    public List<ArbitraryTransactionData> loadAllHostedTransactions(Repository repository) {
+        
         List<ArbitraryTransactionData> arbitraryTransactionDataList = new ArrayList<>();
 
         // Find all hosted paths
@@ -285,7 +293,21 @@ public class ArbitraryDataStorageManager extends Thread {
                 if (transactionData == null || transactionData.getType() != Transaction.TransactionType.ARBITRARY) {
                     continue;
                 }
-                arbitraryTransactionDataList.add((ArbitraryTransactionData) transactionData);
+                ArbitraryTransactionData arbitraryTransactionData = (ArbitraryTransactionData) transactionData;
+
+                // Make sure to exclude metadata-only resources
+                if (arbitraryTransactionData.getMetadataHash() != null) {
+                    if (contents.length == 1) {
+                        String metadataHash58 = Base58.encode(arbitraryTransactionData.getMetadataHash());
+                        if (Objects.equals(metadataHash58, contents[0])) {
+                            // We only have the metadata file for this resource, not the actual data, so exclude it
+                            continue;
+                        }
+                    }
+                }
+
+                // Found some data matching a transaction, so add it to the list
+                arbitraryTransactionDataList.add(arbitraryTransactionData);
 
             } catch (DataException e) {
                 continue;
@@ -295,10 +317,69 @@ public class ArbitraryDataStorageManager extends Thread {
         // Sort by newest first
         arbitraryTransactionDataList.sort(Comparator.comparingLong(ArbitraryTransactionData::getTimestamp).reversed());
 
-        // Update cache
-        this.hostedTransactions = arbitraryTransactionDataList;
+        return arbitraryTransactionDataList;
+    }
+    // Hosted data
 
-        return ArbitraryTransactionUtils.limitOffsetTransactions(arbitraryTransactionDataList, limit, offset);
+    public List<ArbitraryTransactionData> listAllHostedTransactions(Repository repository, Integer limit, Integer offset) {
+        // Load from cache if we can, to avoid disk reads
+
+        if (this.hostedTransactions != null) {
+            return ArbitraryTransactionUtils.limitOffsetTransactions(this.hostedTransactions, limit, offset);
+        }
+
+        this.hostedTransactions = this.loadAllHostedTransactions(repository);
+
+        return ArbitraryTransactionUtils.limitOffsetTransactions(this.hostedTransactions, limit, offset);
+    }
+    
+    /**
+     * searchHostedTransactions
+     * Allow to run a query against hosted data names and return matches if there are any
+     * @param repository
+     * @param query
+     * @param limit
+     * @param offset
+     * @return
+     */
+
+    public List<ArbitraryTransactionData> searchHostedTransactions(Repository repository, String query, Integer limit, Integer offset) {
+        // Load from results cache if we can (results that exists for the same query), to avoid disk reads
+        if (this.searchResultsTransactions != null && this.searchQuery.equals(query.toLowerCase())) {
+            return ArbitraryTransactionUtils.limitOffsetTransactions(this.searchResultsTransactions, limit, offset);
+        }
+
+        // Using cache if we can, to avoid disk reads
+        if (this.hostedTransactions == null) {
+            this.hostedTransactions = this.loadAllHostedTransactions(repository);
+        }
+
+        this.searchQuery = query.toLowerCase(); //set the searchQuery so that it can be checked on the next call
+
+        List<ArbitraryTransactionData> searchResultsList = new ArrayList<>();
+
+        // Loop through cached hostedTransactions
+        for (ArbitraryTransactionData atd : this.hostedTransactions) {
+            try {
+               if (atd.getName() != null && atd.getName().toLowerCase().contains(this.searchQuery)) {
+                   searchResultsList.add(atd);
+               }
+               else if (atd.getIdentifier() != null && atd.getIdentifier().toLowerCase().contains(this.searchQuery)) {
+                   searchResultsList.add(atd);
+               }
+
+            } catch (Exception e) {
+                continue;
+            }
+        }
+
+        // Sort by newest first
+        searchResultsList.sort(Comparator.comparingLong(ArbitraryTransactionData::getTimestamp).reversed());
+
+        // Update cache
+        this.searchResultsTransactions = searchResultsList;
+
+        return ArbitraryTransactionUtils.limitOffsetTransactions(this.searchResultsTransactions, limit, offset);
     }
 
     /**
@@ -322,7 +403,7 @@ public class ArbitraryDataStorageManager extends Thread {
                             && path.getFileName().toString().length() > 32)
                     .collect(Collectors.toList());
         }
-        catch (IOException e) {
+        catch (IOException | UncheckedIOException e) {
             LOGGER.info("Unable to walk through hosted data: {}", e.getMessage());
         }
 

src/main/java/org/qortal/controller/arbitrary/ArbitraryMetadataManager.java

@@ -0,0 +1,455 @@
+package org.qortal.controller.arbitrary;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.arbitrary.ArbitraryDataFile;
+import org.qortal.arbitrary.ArbitraryDataResource;
+import org.qortal.arbitrary.metadata.ArbitraryDataTransactionMetadata;
+import org.qortal.controller.Controller;
+import org.qortal.data.transaction.ArbitraryTransactionData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.network.Network;
+import org.qortal.network.Peer;
+import org.qortal.network.message.*;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.settings.Settings;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+import org.qortal.utils.Triple;
+
+import java.io.IOException;
+import java.util.*;
+
+import static org.qortal.controller.arbitrary.ArbitraryDataFileListManager.RELAY_REQUEST_MAX_DURATION;
+import static org.qortal.controller.arbitrary.ArbitraryDataFileListManager.RELAY_REQUEST_MAX_HOPS;
+
+public class ArbitraryMetadataManager {
+
+    private static final Logger LOGGER = LogManager.getLogger(ArbitraryMetadataManager.class);
+
+    private static ArbitraryMetadataManager instance;
+
+    /**
+     * Map of recent incoming requests for ARBITRARY transaction metadata.
+     * <p>
+     * Key is original request's message ID<br>
+     * Value is Triple&lt;transaction signature in base58, first requesting peer, first request's timestamp&gt;
+     * <p>
+     * If peer is null then either:<br>
+     * <ul>
+     * <li>we are the original requesting peer</li>
+     * <li>we have already sent data payload to original requesting peer.</li>
+     * </ul>
+     * If signature is null then we have already received the file list and either:<br>
+     * <ul>
+     * <li>we are the original requesting peer and have processed it</li>
+     * <li>we have forwarded the metadata</li>
+     * </ul>
+     */
+    public Map<Integer, Triple<String, Peer, Long>> arbitraryMetadataRequests = Collections.synchronizedMap(new HashMap<>());
+
+    /**
+     * Map to keep track of in progress arbitrary metadata requests
+     * Key: string - the signature encoded in base58
+     * Value: Triple<networkBroadcastCount, directPeerRequestCount, lastAttemptTimestamp>
+     */
+    private Map<String, Triple<Integer, Integer, Long>> arbitraryMetadataSignatureRequests = Collections.synchronizedMap(new HashMap<>());
+
+
+    private ArbitraryMetadataManager() {
+    }
+
+    public static ArbitraryMetadataManager getInstance() {
+        if (instance == null)
+            instance = new ArbitraryMetadataManager();
+
+        return instance;
+    }
+
+    public void cleanupRequestCache(Long now) {
+        if (now == null) {
+            return;
+        }
+        final long requestMinimumTimestamp = now - ArbitraryDataManager.ARBITRARY_REQUEST_TIMEOUT;
+        arbitraryMetadataRequests.entrySet().removeIf(entry -> entry.getValue().getC() == null || entry.getValue().getC() < requestMinimumTimestamp);
+    }
+
+
+    public ArbitraryDataTransactionMetadata fetchMetadata(ArbitraryDataResource arbitraryDataResource, boolean useRateLimiter) {
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            // Find latest transaction
+            ArbitraryTransactionData latestTransaction = repository.getArbitraryRepository()
+                    .getLatestTransaction(arbitraryDataResource.getResourceId(), arbitraryDataResource.getService(),
+                            null, arbitraryDataResource.getIdentifier());
+
+            if (latestTransaction != null) {
+                byte[] signature = latestTransaction.getSignature();
+                byte[] metadataHash = latestTransaction.getMetadataHash();
+                if (metadataHash == null) {
+                    // This resource doesn't have metadata
+                    throw new IllegalArgumentException("This resource doesn't have metadata");
+                }
+
+                ArbitraryDataFile metadataFile = ArbitraryDataFile.fromHash(metadataHash, signature);
+                if (!metadataFile.exists()) {
+                    // Request from network
+                    this.fetchArbitraryMetadata(latestTransaction, useRateLimiter);
+                }
+
+                // Now check again as it may have been downloaded above
+                if (metadataFile.exists()) {
+                    // Use local copy
+                    ArbitraryDataTransactionMetadata transactionMetadata = new ArbitraryDataTransactionMetadata(metadataFile.getFilePath());
+                    transactionMetadata.read();
+                    return transactionMetadata;
+                }
+            }
+
+        } catch (DataException | IOException e) {
+            LOGGER.error("Repository issue when fetching arbitrary transaction metadata", e);
+        }
+
+        return null;
+    }
+
+
+    // Request metadata from network
+
+    public byte[] fetchArbitraryMetadata(ArbitraryTransactionData arbitraryTransactionData, boolean useRateLimiter) {
+        byte[] metadataHash = arbitraryTransactionData.getMetadataHash();
+        if (metadataHash == null) {
+            return null;
+        }
+
+        byte[] signature = arbitraryTransactionData.getSignature();
+        String signature58 = Base58.encode(signature);
+
+        // Require an NTP sync
+        Long now = NTP.getTime();
+        if (now == null) {
+            return null;
+        }
+
+        // If we've already tried too many times in a short space of time, make sure to give up
+        if (useRateLimiter && !this.shouldMakeMetadataRequestForSignature(signature58)) {
+            LOGGER.trace("Skipping metadata request for signature {} due to rate limit", signature58);
+            return null;
+        }
+        this.addToSignatureRequests(signature58, true, false);
+
+        List<Peer> handshakedPeers = Network.getInstance().getImmutableHandshakedPeers();
+        LOGGER.debug(String.format("Sending metadata request for signature %s to %d peers...", signature58, handshakedPeers.size()));
+
+        // Build request
+        Message getArbitraryMetadataMessage = new GetArbitraryMetadataMessage(signature, now, 0);
+
+        // Save our request into requests map
+        Triple<String, Peer, Long> requestEntry = new Triple<>(signature58, null, NTP.getTime());
+
+        // Assign random ID to this message
+        int id;
+        do {
+            id = new Random().nextInt(Integer.MAX_VALUE - 1) + 1;
+
+            // Put queue into map (keyed by message ID) so we can poll for a response
+            // If putIfAbsent() doesn't return null, then this ID is already taken
+        } while (arbitraryMetadataRequests.put(id, requestEntry) != null);
+        getArbitraryMetadataMessage.setId(id);
+
+        // Broadcast request
+        Network.getInstance().broadcast(peer -> getArbitraryMetadataMessage);
+
+        // Poll to see if data has arrived
+        final long singleWait = 100;
+        long totalWait = 0;
+        while (totalWait < ArbitraryDataManager.ARBITRARY_REQUEST_TIMEOUT) {
+            try {
+                Thread.sleep(singleWait);
+            } catch (InterruptedException e) {
+                break;
+            }
+
+            requestEntry = arbitraryMetadataRequests.get(id);
+            if (requestEntry == null)
+                return null;
+
+            if (requestEntry.getA() == null)
+                break;
+
+            totalWait += singleWait;
+        }
+
+        try {
+            ArbitraryDataFile metadataFile = ArbitraryDataFile.fromHash(metadataHash, signature);
+            if (metadataFile.exists()) {
+                return metadataFile.getBytes();
+            }
+        } catch (DataException e) {
+            // Do nothing
+        }
+
+        return null;
+    }
+
+
+    // Track metadata lookups by signature
+
+    private boolean shouldMakeMetadataRequestForSignature(String signature58) {
+        Triple<Integer, Integer, Long> request = arbitraryMetadataSignatureRequests.get(signature58);
+
+        if (request == null) {
+            // Not attempted yet
+            return true;
+        }
+
+        // Extract the components
+        Integer networkBroadcastCount = request.getA();
+        // Integer directPeerRequestCount = request.getB();
+        Long lastAttemptTimestamp = request.getC();
+
+        if (lastAttemptTimestamp == null) {
+            // Not attempted yet
+            return true;
+        }
+
+        long timeSinceLastAttempt = NTP.getTime() - lastAttemptTimestamp;
+
+        // Allow a second attempt after 60 seconds
+        if (timeSinceLastAttempt > 60 * 1000L) {
+            // We haven't tried for at least 60 seconds
+
+            if (networkBroadcastCount < 2) {
+                // We've made less than 2 total attempts
+                return true;
+            }
+        }
+
+        // Then allow another attempt after 60 minutes
+        if (timeSinceLastAttempt > 60 * 60 * 1000L) {
+            // We haven't tried for at least 60 minutes
+
+            if (networkBroadcastCount < 3) {
+                // We've made less than 3 total attempts
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    public boolean isSignatureRateLimited(byte[] signature) {
+        String signature58 = Base58.encode(signature);
+        return !this.shouldMakeMetadataRequestForSignature(signature58);
+    }
+
+    public long lastRequestForSignature(byte[] signature) {
+        String signature58 = Base58.encode(signature);
+        Triple<Integer, Integer, Long> request = arbitraryMetadataSignatureRequests.get(signature58);
+
+        if (request == null) {
+            // Not attempted yet
+            return 0;
+        }
+
+        // Extract the components
+        Long lastAttemptTimestamp = request.getC();
+        if (lastAttemptTimestamp != null) {
+            return  lastAttemptTimestamp;
+        }
+        return 0;
+    }
+
+    public void addToSignatureRequests(String signature58, boolean incrementNetworkRequests, boolean incrementPeerRequests) {
+        Triple<Integer, Integer, Long> request  = arbitraryMetadataSignatureRequests.get(signature58);
+        Long now = NTP.getTime();
+
+        if (request == null) {
+            // No entry yet
+            Triple<Integer, Integer, Long> newRequest = new Triple<>(0, 0, now);
+            arbitraryMetadataSignatureRequests.put(signature58, newRequest);
+        }
+        else {
+            // There is an existing entry
+            if (incrementNetworkRequests) {
+                request.setA(request.getA() + 1);
+            }
+            if (incrementPeerRequests) {
+                request.setB(request.getB() + 1);
+            }
+            request.setC(now);
+            arbitraryMetadataSignatureRequests.put(signature58, request);
+        }
+    }
+
+    public void removeFromSignatureRequests(String signature58) {
+        arbitraryMetadataSignatureRequests.remove(signature58);
+    }
+
+
+    // Network handlers
+
+    public void onNetworkArbitraryMetadataMessage(Peer peer, Message message) {
+        // Don't process if QDN is disabled
+        if (!Settings.getInstance().isQdnEnabled()) {
+            return;
+        }
+
+        ArbitraryMetadataMessage arbitraryMetadataMessage = (ArbitraryMetadataMessage) message;
+        LOGGER.debug("Received metadata from peer {}", peer);
+
+        // Do we have a pending request for this data?
+        Triple<String, Peer, Long> request = arbitraryMetadataRequests.get(message.getId());
+        if (request == null || request.getA() == null) {
+            return;
+        }
+        boolean isRelayRequest = (request.getB() != null);
+
+        // Does this message's signature match what we're expecting?
+        byte[] signature = arbitraryMetadataMessage.getSignature();
+        String signature58 = Base58.encode(signature);
+        if (!request.getA().equals(signature58)) {
+            return;
+        }
+
+        // Update requests map to reflect that we've received all chunks
+        Triple<String, Peer, Long> newEntry = new Triple<>(null, null, request.getC());
+        arbitraryMetadataRequests.put(message.getId(), newEntry);
+
+        ArbitraryTransactionData arbitraryTransactionData = null;
+
+        // Forwarding
+        if (isRelayRequest && Settings.getInstance().isRelayModeEnabled()) {
+
+            // Get transaction info
+            try (final Repository repository = RepositoryManager.getRepository()) {
+                TransactionData transactionData = repository.getTransactionRepository().fromSignature(signature);
+                if (!(transactionData instanceof ArbitraryTransactionData))
+                    return;
+                arbitraryTransactionData = (ArbitraryTransactionData) transactionData;
+            } catch (DataException e) {
+                LOGGER.error(String.format("Repository issue while finding arbitrary transaction metadata for peer %s", peer), e);
+            }
+
+            // Check if the name is blocked
+            boolean isBlocked = (arbitraryTransactionData == null || ArbitraryDataStorageManager.getInstance().isNameBlocked(arbitraryTransactionData.getName()));
+            if (!isBlocked) {
+                Peer requestingPeer = request.getB();
+                if (requestingPeer != null) {
+
+                    ArbitraryMetadataMessage forwardArbitraryMetadataMessage = new ArbitraryMetadataMessage(signature, arbitraryMetadataMessage.getArbitraryMetadataFile());
+
+                    // Forward to requesting peer
+                    LOGGER.debug("Forwarding metadata to requesting peer: {}", requestingPeer);
+                    if (!requestingPeer.sendMessage(forwardArbitraryMetadataMessage)) {
+                        requestingPeer.disconnect("failed to forward arbitrary metadata");
+                    }
+                }
+            }
+        }
+    }
+
+    public void onNetworkGetArbitraryMetadataMessage(Peer peer, Message message) {
+        // Don't respond if QDN is disabled
+        if (!Settings.getInstance().isQdnEnabled()) {
+            return;
+        }
+
+        Controller.getInstance().stats.getArbitraryMetadataMessageStats.requests.incrementAndGet();
+
+        GetArbitraryMetadataMessage getArbitraryMetadataMessage = (GetArbitraryMetadataMessage) message;
+        byte[] signature = getArbitraryMetadataMessage.getSignature();
+        String signature58 = Base58.encode(signature);
+        Long now = NTP.getTime();
+        Triple<String, Peer, Long> newEntry = new Triple<>(signature58, peer, now);
+
+        // If we've seen this request recently, then ignore
+        if (arbitraryMetadataRequests.putIfAbsent(message.getId(), newEntry) != null) {
+            LOGGER.debug("Ignoring metadata request from peer {} for signature {}", peer, signature58);
+            return;
+        }
+
+        LOGGER.debug("Received metadata request from peer {} for signature {}", peer, signature58);
+
+        ArbitraryTransactionData transactionData = null;
+        ArbitraryDataFile metadataFile = null;
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+
+            // Firstly we need to lookup this file on chain to get its metadata hash
+            transactionData = (ArbitraryTransactionData)repository.getTransactionRepository().fromSignature(signature);
+            if (transactionData instanceof ArbitraryTransactionData) {
+
+                // Check if we're even allowed to serve metadata for this transaction
+                if (ArbitraryDataStorageManager.getInstance().canStoreData(transactionData)) {
+
+                    byte[] metadataHash = transactionData.getMetadataHash();
+                    if (metadataHash != null) {
+
+                        // Load metadata file
+                        metadataFile = ArbitraryDataFile.fromHash(metadataHash, signature);
+                    }
+                }
+            }
+
+        } catch (DataException e) {
+            LOGGER.error(String.format("Repository issue while fetching arbitrary metadata for peer %s", peer), e);
+        }
+
+        // We should only respond if we have the metadata file
+        if (metadataFile != null && metadataFile.exists()) {
+
+            // We have the metadata file, so update requests map to reflect that we've sent it
+            newEntry = new Triple<>(null, null, now);
+            arbitraryMetadataRequests.put(message.getId(), newEntry);
+
+            ArbitraryMetadataMessage arbitraryMetadataMessage = new ArbitraryMetadataMessage(signature, metadataFile);
+            arbitraryMetadataMessage.setId(message.getId());
+            if (!peer.sendMessage(arbitraryMetadataMessage)) {
+                LOGGER.debug("Couldn't send metadata");
+                peer.disconnect("failed to send metadata");
+                return;
+            }
+            LOGGER.debug("Sent metadata");
+
+            // Nothing left to do, so return to prevent any unnecessary forwarding from occurring
+            LOGGER.debug("No need for any forwarding because metadata request is fully served");
+            return;
+
+        }
+
+        // We may need to forward this request on
+        boolean isBlocked = (transactionData == null || ArbitraryDataStorageManager.getInstance().isNameBlocked(transactionData.getName()));
+        if (Settings.getInstance().isRelayModeEnabled() && !isBlocked) {
+            // In relay mode - so ask our other peers if they have it
+
+            long requestTime = getArbitraryMetadataMessage.getRequestTime();
+            int requestHops = getArbitraryMetadataMessage.getRequestHops() + 1;
+            long totalRequestTime = now - requestTime;
+
+            if (totalRequestTime < RELAY_REQUEST_MAX_DURATION) {
+                // Relay request hasn't timed out yet, so can potentially be rebroadcast
+                if (requestHops < RELAY_REQUEST_MAX_HOPS) {
+                    // Relay request hasn't reached the maximum number of hops yet, so can be rebroadcast
+
+                    Message relayGetArbitraryMetadataMessage = new GetArbitraryMetadataMessage(signature, requestTime, requestHops);
+
+                    LOGGER.debug("Rebroadcasting metadata request from peer {} for signature {} to our other peers... totalRequestTime: {}, requestHops: {}", peer, Base58.encode(signature), totalRequestTime, requestHops);
+                    Network.getInstance().broadcast(
+                            broadcastPeer -> broadcastPeer == peer ||
+                                    Objects.equals(broadcastPeer.getPeerData().getAddress().getHost(), peer.getPeerData().getAddress().getHost())
+                                    ? null : relayGetArbitraryMetadataMessage);
+
+                }
+                else {
+                    // This relay request has reached the maximum number of allowed hops
+                }
+            }
+            else {
+                // This relay request has timed out
+            }
+        }
+    }
+
+}

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

@@ -29,6 +29,15 @@ public class NamesDatabaseIntegrityCheck {
     private List<TransactionData> nameTransactions = new ArrayList<>();
 
     public int rebuildName(String name, Repository repository) {
+        return this.rebuildName(name, repository, null);
+    }
+
+    public int rebuildName(String name, Repository repository, List<String> referenceNames) {
+        // "referenceNames" tracks the linked names that have already been rebuilt, to prevent circular dependencies
+        if (referenceNames == null) {
+            referenceNames = new ArrayList<>();
+        }
+
         int modificationCount = 0;
         try {
             List<TransactionData> transactions = this.fetchAllTransactionsInvolvingName(name, repository);
@@ -56,7 +65,14 @@ public class NamesDatabaseIntegrityCheck {
                     if (Objects.equals(updateNameTransactionData.getNewName(), name) &&
                             !Objects.equals(updateNameTransactionData.getName(), updateNameTransactionData.getNewName())) {
                         // This renames an existing name, so we need to process that instead
-                        this.rebuildName(updateNameTransactionData.getName(), repository);
+
+                        if (!referenceNames.contains(name)) {
+                            referenceNames.add(name);
+                            this.rebuildName(updateNameTransactionData.getName(), repository, referenceNames);
+                        }
+                        else {
+                            // We've already processed this name so there's nothing more to do
+                        }
                     }
                     else {
                         Name nameObj = new Name(repository, name);
@@ -193,7 +209,12 @@ public class NamesDatabaseIntegrityCheck {
                                 newName = registeredName;
                             }
                             NameData newNameData = repository.getNameRepository().fromName(newName);
-                            if (!Objects.equals(creator.getAddress(), newNameData.getOwner())) {
+                            if (newNameData == null) {
+                                LOGGER.info("Error: registered name {} has no new name data. This is likely due to account {} " +
+                                                "being renamed another time, which is a scenario that is not yet checked automatically.",
+                                        updateNameTransactionData.getNewName(), creator.getAddress());
+                            }
+                            else if (!Objects.equals(creator.getAddress(), newNameData.getOwner())) {
                                 LOGGER.info("Error: registered name {} is owned by {}, but it should be {}",
                                         updateNameTransactionData.getNewName(), newNameData.getOwner(), creator.getAddress());
                                 integrityCheckFailed = true;
@@ -313,6 +334,10 @@ public class NamesDatabaseIntegrityCheck {
                 transactions.add(transactionData);
             }
         }
+
+        // Sort by lowest timestamp first
+        transactions.sort(Comparator.comparingLong(TransactionData::getTimestamp));
+
         return transactions;
     }
 

src/main/java/org/qortal/controller/tradebot/BitcoinACCTv3TradeBot.java

@@ -0,0 +1,885 @@
+package org.qortal.controller.tradebot;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.bitcoinj.core.*;
+import org.bitcoinj.script.Script.ScriptType;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.account.PublicKeyAccount;
+import org.qortal.api.model.crosschain.TradeBotCreateRequest;
+import org.qortal.asset.Asset;
+import org.qortal.crosschain.*;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.data.transaction.BaseTransactionData;
+import org.qortal.data.transaction.DeployAtTransactionData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.transaction.DeployAtTransaction;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.transaction.DeployAtTransactionTransformer;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import static java.util.Arrays.stream;
+import static java.util.stream.Collectors.toMap;
+
+/**
+ * Performing cross-chain trading steps on behalf of user.
+ * <p>
+ * We deal with three different independent state-spaces here:
+ * <ul>
+ * 	<li>Qortal blockchain</li>
+ * 	<li>Foreign blockchain</li>
+ * 	<li>Trade-bot entries</li>
+ * </ul>
+ */
+public class BitcoinACCTv3TradeBot implements AcctTradeBot {
+
+	private static final Logger LOGGER = LogManager.getLogger(BitcoinACCTv3TradeBot.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 BitcoinACCTv3TradeBot 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 BitcoinACCTv3TradeBot() {
+	}
+
+	public static synchronized BitcoinACCTv3TradeBot getInstance() {
+		if (instance == null)
+			instance = new BitcoinACCTv3TradeBot();
+
+		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 BTC.
+	 * <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 Bitcoin) 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'/Bitcoin public key hash - used by Alice's P2SH scripts to allow redeem</li>
+	 * 	<li>QORT amount on offer by Bob</li>
+	 * 	<li>BTC 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 Bitcoin receiving address into public key hash (we only support P2PKH at this time)
+		Address bitcoinReceivingAddress;
+		try {
+			bitcoinReceivingAddress = Address.fromString(Bitcoin.getInstance().getNetworkParameters(), tradeBotCreateRequest.receivingAddress);
+		} catch (AddressFormatException e) {
+			throw new DataException("Unsupported Bitcoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+		}
+		if (bitcoinReceivingAddress.getOutputScriptType() != ScriptType.P2PKH)
+			throw new DataException("Unsupported Bitcoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+
+		byte[] bitcoinReceivingAccountInfo = bitcoinReceivingAddress.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/BTC ACCT";
+		String description = "QORT/BTC cross-chain trade";
+		String aTType = "ACCT";
+		String tags = "ACCT QORT BTC";
+		byte[] creationBytes = BitcoinACCTv3.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, BitcoinACCTv3.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.BITCOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				tradeBotCreateRequest.foreignAmount, null, null, null, bitcoinReceivingAccountInfo);
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Built AT %s. Waiting for deployment", atAddress));
+
+		// Attempt to backup the trade bot data
+		TradeBot.backupTradeBotData(repository, null);
+
+		// Return to user for signing and broadcast as we don't have their Qortal private key
+		try {
+			return DeployAtTransactionTransformer.toBytes(deployAtTransactionData);
+		} catch (TransformationException e) {
+			throw new DataException("Failed to transform DEPLOY_AT transaction?", e);
+		}
+	}
+
+	/**
+	 * Creates a trade-bot entry from the 'Alice' viewpoint, i.e. matching BTC to an existing offer.
+	 * <p>
+	 * Requires a chosen trade offer from Bob, passed by <tt>crossChainTradeData</tt>
+	 * and access to a Bitcoin 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 Bitcoin 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 Bitcoin main-net)
+	 * or 'tprv' for (Bitcoin 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 Bitcoin amount expected by 'Bob'.
+	 * <p>
+	 * If the Bitcoin 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 Bitcoin 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, BitcoinACCTv3.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.BITCOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				crossChainTradeData.expectedForeignAmount, xprv58, null, lockTimeA, receivingPublicKeyHash);
+
+		// Attempt to backup the trade bot data
+		// Include tradeBotData as an additional parameter, since it's not in the repository yet
+		TradeBot.backupTradeBotData(repository, Arrays.asList(tradeBotData));
+
+		// Check we have enough funds via xprv58 to fund P2SH to cover expectedForeignAmount
+		long p2shFee;
+		try {
+			p2shFee = Bitcoin.getInstance().getP2shFee(now);
+		} catch (ForeignBlockchainException e) {
+			LOGGER.debug("Couldn't estimate Bitcoin 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 = Bitcoin.getInstance().deriveP2shAddress(redeemScriptBytes);
+
+		// Build transaction for funding P2SH-A
+		Transaction p2shFundingTransaction = Bitcoin.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 {
+			Bitcoin.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 = BitcoinACCTv3.buildOfferMessage(tradeBotData.getTradeForeignPublicKeyHash(), tradeBotData.getHashOfSecret(), tradeBotData.getLockTimeA());
+		String messageRecipient = crossChainTradeData.qortalCreatorTradeAddress;
+
+		boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, messageData);
+		if (!isMessageAlreadySent) {
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK) {
+				LOGGER.warn(() -> String.format("Unable to send MESSAGE to Bob's trade-bot %s: %s", messageRecipient, result.name()));
+				return ResponseResult.NETWORK_ISSUE;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Funding P2SH-A %s. Messaged Bob. Waiting for AT-lock", p2shAddress));
+
+		return ResponseResult.OK;
+	}
+
+	@Override
+	public boolean canDelete(Repository repository, TradeBotData tradeBotData) throws DataException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null)
+			return true;
+
+		// If the AT doesn't exist then we might as well let the user tidy up
+		if (!repository.getATRepository().exists(tradeBotData.getAtAddress()))
+			return true;
+
+		switch (tradeBotState) {
+			case BOB_WAITING_FOR_AT_CONFIRM:
+			case ALICE_DONE:
+			case BOB_DONE:
+			case ALICE_REFUNDED:
+			case BOB_REFUNDED:
+			case ALICE_REFUNDING_A:
+				return true;
+
+			default:
+				return false;
+		}
+	}
+
+	@Override
+	public void progress(Repository repository, TradeBotData tradeBotData) throws DataException, ForeignBlockchainException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null) {
+			LOGGER.info(() -> String.format("Trade-bot entry for AT %s has invalid state?", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		ATData atData = null;
+		CrossChainTradeData tradeData = null;
+
+		if (tradeBotState.requiresAtData) {
+			// Attempt to fetch AT data
+			atData = repository.getATRepository().fromATAddress(tradeBotData.getAtAddress());
+			if (atData == null) {
+				LOGGER.debug(() -> String.format("Unable to fetch trade AT %s from repository", tradeBotData.getAtAddress()));
+				return;
+			}
+
+			if (tradeBotState.requiresTradeData) {
+				tradeData = BitcoinACCTv3.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 Bitcoin 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;
+		}
+
+		Bitcoin bitcoin = Bitcoin.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 Bitcoin pubkeyhash and lockTime-A
+			byte[] messageData = messageTransactionData.getData();
+			BitcoinACCTv3.OfferMessageData offerMessageData = BitcoinACCTv3.extractOfferMessageData(messageData);
+			if (offerMessageData == null)
+				continue;
+
+			byte[] aliceForeignPublicKeyHash = offerMessageData.partnerBitcoinPKH;
+			byte[] hashOfSecretA = offerMessageData.hashOfSecretA;
+			int lockTimeA = (int) offerMessageData.lockTimeA;
+			long messageTimestamp = messageTransactionData.getTimestamp();
+			int refundTimeout = BitcoinACCTv3.calcRefundTimeout(messageTimestamp, lockTimeA);
+
+			// Determine P2SH-A address and confirm funded
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(aliceForeignPublicKeyHash, lockTimeA, tradeBotData.getTradeForeignPublicKeyHash(), hashOfSecretA);
+			String p2shAddressA = bitcoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Bitcoin.getInstance().getP2shFee(feeTimestamp);
+			final long minimumAmountA = tradeBotData.getForeignAmount() + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(bitcoin.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 = BitcoinACCTv3.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 BTC 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;
+
+		Bitcoin bitcoin = Bitcoin.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 = bitcoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Bitcoin.getInstance().getP2shFee(feeTimestamp);
+			long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(bitcoin.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 = BitcoinACCTv3.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 = BitcoinACCTv3.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 BTC 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 BTC funds from P2SH-A
+	 * to Bob's 'foreign'/Bitcoin trade legacy-format address, as derived from trade private key.
+	 * <p>
+	 * (This could potentially be 'improved' to send BTC 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 BTC
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_REFUNDED,
+					() -> String.format("AT %s has auto-refunded - trade aborted", tradeBotData.getAtAddress()));
+
+			return;
+		}
+
+		byte[] secretA = BitcoinACCTv3.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
+
+		Bitcoin bitcoin = Bitcoin.getInstance();
+
+		byte[] receivingAccountInfo = tradeBotData.getReceivingAccountInfo();
+		int lockTimeA = crossChainTradeData.lockTimeA;
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(crossChainTradeData.partnerForeignPKH, lockTimeA, crossChainTradeData.creatorForeignPKH, crossChainTradeData.hashOfSecretA);
+		String p2shAddressA = bitcoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Bitcoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(bitcoin.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 = bitcoin.getUnspentOutputs(p2shAddressA);
+
+				Transaction p2shRedeemTransaction = BitcoinyHTLC.buildRedeemTransaction(bitcoin.getNetworkParameters(), redeemAmount, redeemKey,
+						fundingOutputs, redeemScriptA, secretA, receivingAccountInfo);
+
+				bitcoin.broadcastTransaction(p2shRedeemTransaction);
+				break;
+			}
+		}
+
+		String receivingAddress = bitcoin.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;
+
+		Bitcoin bitcoin = Bitcoin.getInstance();
+
+		// We can't refund P2SH-A until median block time has passed lockTime-A (see BIP113)
+		int medianBlockTime = bitcoin.getMedianBlockTime();
+		if (medianBlockTime <= lockTimeA)
+			return;
+
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeA, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+		String p2shAddressA = bitcoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Bitcoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(bitcoin.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 = bitcoin.getUnspentOutputs(p2shAddressA);
+
+				// Determine receive address for refund
+				String receiveAddress = bitcoin.getUnusedReceiveAddress(tradeBotData.getForeignKey());
+				Address receiving = Address.fromString(bitcoin.getNetworkParameters(), receiveAddress);
+
+				Transaction p2shRefundTransaction = BitcoinyHTLC.buildRefundTransaction(bitcoin.getNetworkParameters(), refundAmount, refundKey,
+						fundingOutputs, redeemScriptA, lockTimeA, receiving.getHash());
+
+				bitcoin.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/DigibyteACCTv3TradeBot.java

@@ -0,0 +1,885 @@
+package org.qortal.controller.tradebot;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.bitcoinj.core.*;
+import org.bitcoinj.script.Script.ScriptType;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.account.PublicKeyAccount;
+import org.qortal.api.model.crosschain.TradeBotCreateRequest;
+import org.qortal.asset.Asset;
+import org.qortal.crosschain.*;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.data.transaction.BaseTransactionData;
+import org.qortal.data.transaction.DeployAtTransactionData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.transaction.DeployAtTransaction;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.transaction.DeployAtTransactionTransformer;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import static java.util.Arrays.stream;
+import static java.util.stream.Collectors.toMap;
+
+/**
+ * Performing cross-chain trading steps on behalf of user.
+ * <p>
+ * We deal with three different independent state-spaces here:
+ * <ul>
+ * 	<li>Qortal blockchain</li>
+ * 	<li>Foreign blockchain</li>
+ * 	<li>Trade-bot entries</li>
+ * </ul>
+ */
+public class DigibyteACCTv3TradeBot implements AcctTradeBot {
+
+	private static final Logger LOGGER = LogManager.getLogger(DigibyteACCTv3TradeBot.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 DigibyteACCTv3TradeBot 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 DigibyteACCTv3TradeBot() {
+	}
+
+	public static synchronized DigibyteACCTv3TradeBot getInstance() {
+		if (instance == null)
+			instance = new DigibyteACCTv3TradeBot();
+
+		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 DGB.
+	 * <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 Digibyte) 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'/Digibyte public key hash - used by Alice's P2SH scripts to allow redeem</li>
+	 * 	<li>QORT amount on offer by Bob</li>
+	 * 	<li>DGB 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 Digibyte receiving address into public key hash (we only support P2PKH at this time)
+		Address digibyteReceivingAddress;
+		try {
+			digibyteReceivingAddress = Address.fromString(Digibyte.getInstance().getNetworkParameters(), tradeBotCreateRequest.receivingAddress);
+		} catch (AddressFormatException e) {
+			throw new DataException("Unsupported Digibyte receiving address: " + tradeBotCreateRequest.receivingAddress);
+		}
+		if (digibyteReceivingAddress.getOutputScriptType() != ScriptType.P2PKH)
+			throw new DataException("Unsupported Digibyte receiving address: " + tradeBotCreateRequest.receivingAddress);
+
+		byte[] digibyteReceivingAccountInfo = digibyteReceivingAddress.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/DGB ACCT";
+		String description = "QORT/DGB cross-chain trade";
+		String aTType = "ACCT";
+		String tags = "ACCT QORT DGB";
+		byte[] creationBytes = DigibyteACCTv3.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, DigibyteACCTv3.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.DIGIBYTE.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				tradeBotCreateRequest.foreignAmount, null, null, null, digibyteReceivingAccountInfo);
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Built AT %s. Waiting for deployment", atAddress));
+
+		// Attempt to backup the trade bot data
+		TradeBot.backupTradeBotData(repository, null);
+
+		// Return to user for signing and broadcast as we don't have their Qortal private key
+		try {
+			return DeployAtTransactionTransformer.toBytes(deployAtTransactionData);
+		} catch (TransformationException e) {
+			throw new DataException("Failed to transform DEPLOY_AT transaction?", e);
+		}
+	}
+
+	/**
+	 * Creates a trade-bot entry from the 'Alice' viewpoint, i.e. matching DGB to an existing offer.
+	 * <p>
+	 * Requires a chosen trade offer from Bob, passed by <tt>crossChainTradeData</tt>
+	 * and access to a Digibyte 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 Digibyte 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 Digibyte main-net)
+	 * or 'tprv' for (Digibyte 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 Digibyte amount expected by 'Bob'.
+	 * <p>
+	 * If the Digibyte 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 Digibyte 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, DigibyteACCTv3.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.DIGIBYTE.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				crossChainTradeData.expectedForeignAmount, xprv58, null, lockTimeA, receivingPublicKeyHash);
+
+		// Attempt to backup the trade bot data
+		// Include tradeBotData as an additional parameter, since it's not in the repository yet
+		TradeBot.backupTradeBotData(repository, Arrays.asList(tradeBotData));
+
+		// Check we have enough funds via xprv58 to fund P2SH to cover expectedForeignAmount
+		long p2shFee;
+		try {
+			p2shFee = Digibyte.getInstance().getP2shFee(now);
+		} catch (ForeignBlockchainException e) {
+			LOGGER.debug("Couldn't estimate Digibyte 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 = Digibyte.getInstance().deriveP2shAddress(redeemScriptBytes);
+
+		// Build transaction for funding P2SH-A
+		Transaction p2shFundingTransaction = Digibyte.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 {
+			Digibyte.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 = DigibyteACCTv3.buildOfferMessage(tradeBotData.getTradeForeignPublicKeyHash(), tradeBotData.getHashOfSecret(), tradeBotData.getLockTimeA());
+		String messageRecipient = crossChainTradeData.qortalCreatorTradeAddress;
+
+		boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, messageData);
+		if (!isMessageAlreadySent) {
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK) {
+				LOGGER.warn(() -> String.format("Unable to send MESSAGE to Bob's trade-bot %s: %s", messageRecipient, result.name()));
+				return ResponseResult.NETWORK_ISSUE;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Funding P2SH-A %s. Messaged Bob. Waiting for AT-lock", p2shAddress));
+
+		return ResponseResult.OK;
+	}
+
+	@Override
+	public boolean canDelete(Repository repository, TradeBotData tradeBotData) throws DataException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null)
+			return true;
+
+		// If the AT doesn't exist then we might as well let the user tidy up
+		if (!repository.getATRepository().exists(tradeBotData.getAtAddress()))
+			return true;
+
+		switch (tradeBotState) {
+			case BOB_WAITING_FOR_AT_CONFIRM:
+			case ALICE_DONE:
+			case BOB_DONE:
+			case ALICE_REFUNDED:
+			case BOB_REFUNDED:
+			case ALICE_REFUNDING_A:
+				return true;
+
+			default:
+				return false;
+		}
+	}
+
+	@Override
+	public void progress(Repository repository, TradeBotData tradeBotData) throws DataException, ForeignBlockchainException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null) {
+			LOGGER.info(() -> String.format("Trade-bot entry for AT %s has invalid state?", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		ATData atData = null;
+		CrossChainTradeData tradeData = null;
+
+		if (tradeBotState.requiresAtData) {
+			// Attempt to fetch AT data
+			atData = repository.getATRepository().fromATAddress(tradeBotData.getAtAddress());
+			if (atData == null) {
+				LOGGER.debug(() -> String.format("Unable to fetch trade AT %s from repository", tradeBotData.getAtAddress()));
+				return;
+			}
+
+			if (tradeBotState.requiresTradeData) {
+				tradeData = DigibyteACCTv3.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 Digibyte 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;
+		}
+
+		Digibyte digibyte = Digibyte.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 Digibyte pubkeyhash and lockTime-A
+			byte[] messageData = messageTransactionData.getData();
+			DigibyteACCTv3.OfferMessageData offerMessageData = DigibyteACCTv3.extractOfferMessageData(messageData);
+			if (offerMessageData == null)
+				continue;
+
+			byte[] aliceForeignPublicKeyHash = offerMessageData.partnerDigibytePKH;
+			byte[] hashOfSecretA = offerMessageData.hashOfSecretA;
+			int lockTimeA = (int) offerMessageData.lockTimeA;
+			long messageTimestamp = messageTransactionData.getTimestamp();
+			int refundTimeout = DigibyteACCTv3.calcRefundTimeout(messageTimestamp, lockTimeA);
+
+			// Determine P2SH-A address and confirm funded
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(aliceForeignPublicKeyHash, lockTimeA, tradeBotData.getTradeForeignPublicKeyHash(), hashOfSecretA);
+			String p2shAddressA = digibyte.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Digibyte.getInstance().getP2shFee(feeTimestamp);
+			final long minimumAmountA = tradeBotData.getForeignAmount() + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(digibyte.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 = DigibyteACCTv3.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 DGB 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;
+
+		Digibyte digibyte = Digibyte.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 = digibyte.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Digibyte.getInstance().getP2shFee(feeTimestamp);
+			long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(digibyte.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 = DigibyteACCTv3.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 = DigibyteACCTv3.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 DGB 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 DGB funds from P2SH-A
+	 * to Bob's 'foreign'/Digibyte trade legacy-format address, as derived from trade private key.
+	 * <p>
+	 * (This could potentially be 'improved' to send DGB 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 DGB
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_REFUNDED,
+					() -> String.format("AT %s has auto-refunded - trade aborted", tradeBotData.getAtAddress()));
+
+			return;
+		}
+
+		byte[] secretA = DigibyteACCTv3.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
+
+		Digibyte digibyte = Digibyte.getInstance();
+
+		byte[] receivingAccountInfo = tradeBotData.getReceivingAccountInfo();
+		int lockTimeA = crossChainTradeData.lockTimeA;
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(crossChainTradeData.partnerForeignPKH, lockTimeA, crossChainTradeData.creatorForeignPKH, crossChainTradeData.hashOfSecretA);
+		String p2shAddressA = digibyte.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Digibyte.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(digibyte.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 = digibyte.getUnspentOutputs(p2shAddressA);
+
+				Transaction p2shRedeemTransaction = BitcoinyHTLC.buildRedeemTransaction(digibyte.getNetworkParameters(), redeemAmount, redeemKey,
+						fundingOutputs, redeemScriptA, secretA, receivingAccountInfo);
+
+				digibyte.broadcastTransaction(p2shRedeemTransaction);
+				break;
+			}
+		}
+
+		String receivingAddress = digibyte.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;
+
+		Digibyte digibyte = Digibyte.getInstance();
+
+		// We can't refund P2SH-A until median block time has passed lockTime-A (see BIP113)
+		int medianBlockTime = digibyte.getMedianBlockTime();
+		if (medianBlockTime <= lockTimeA)
+			return;
+
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeA, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+		String p2shAddressA = digibyte.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Digibyte.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(digibyte.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 = digibyte.getUnspentOutputs(p2shAddressA);
+
+				// Determine receive address for refund
+				String receiveAddress = digibyte.getUnusedReceiveAddress(tradeBotData.getForeignKey());
+				Address receiving = Address.fromString(digibyte.getNetworkParameters(), receiveAddress);
+
+				Transaction p2shRefundTransaction = BitcoinyHTLC.buildRefundTransaction(digibyte.getNetworkParameters(), refundAmount, refundKey,
+						fundingOutputs, redeemScriptA, lockTimeA, receiving.getHash());
+
+				digibyte.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/RavencoinACCTv3TradeBot.java

@@ -0,0 +1,885 @@
+package org.qortal.controller.tradebot;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.bitcoinj.core.*;
+import org.bitcoinj.script.Script.ScriptType;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.account.PublicKeyAccount;
+import org.qortal.api.model.crosschain.TradeBotCreateRequest;
+import org.qortal.asset.Asset;
+import org.qortal.crosschain.*;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.data.transaction.BaseTransactionData;
+import org.qortal.data.transaction.DeployAtTransactionData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.transaction.DeployAtTransaction;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.transaction.DeployAtTransactionTransformer;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import static java.util.Arrays.stream;
+import static java.util.stream.Collectors.toMap;
+
+/**
+ * Performing cross-chain trading steps on behalf of user.
+ * <p>
+ * We deal with three different independent state-spaces here:
+ * <ul>
+ * 	<li>Qortal blockchain</li>
+ * 	<li>Foreign blockchain</li>
+ * 	<li>Trade-bot entries</li>
+ * </ul>
+ */
+public class RavencoinACCTv3TradeBot implements AcctTradeBot {
+
+	private static final Logger LOGGER = LogManager.getLogger(RavencoinACCTv3TradeBot.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 RavencoinACCTv3TradeBot 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 RavencoinACCTv3TradeBot() {
+	}
+
+	public static synchronized RavencoinACCTv3TradeBot getInstance() {
+		if (instance == null)
+			instance = new RavencoinACCTv3TradeBot();
+
+		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 RVN.
+	 * <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 Ravencoin) 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'/Ravencoin public key hash - used by Alice's P2SH scripts to allow redeem</li>
+	 * 	<li>QORT amount on offer by Bob</li>
+	 * 	<li>RVN 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 Ravencoin receiving address into public key hash (we only support P2PKH at this time)
+		Address ravencoinReceivingAddress;
+		try {
+			ravencoinReceivingAddress = Address.fromString(Ravencoin.getInstance().getNetworkParameters(), tradeBotCreateRequest.receivingAddress);
+		} catch (AddressFormatException e) {
+			throw new DataException("Unsupported Ravencoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+		}
+		if (ravencoinReceivingAddress.getOutputScriptType() != ScriptType.P2PKH)
+			throw new DataException("Unsupported Ravencoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+
+		byte[] ravencoinReceivingAccountInfo = ravencoinReceivingAddress.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/RVN ACCT";
+		String description = "QORT/RVN cross-chain trade";
+		String aTType = "ACCT";
+		String tags = "ACCT QORT RVN";
+		byte[] creationBytes = RavencoinACCTv3.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, RavencoinACCTv3.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.RAVENCOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				tradeBotCreateRequest.foreignAmount, null, null, null, ravencoinReceivingAccountInfo);
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Built AT %s. Waiting for deployment", atAddress));
+
+		// Attempt to backup the trade bot data
+		TradeBot.backupTradeBotData(repository, null);
+
+		// Return to user for signing and broadcast as we don't have their Qortal private key
+		try {
+			return DeployAtTransactionTransformer.toBytes(deployAtTransactionData);
+		} catch (TransformationException e) {
+			throw new DataException("Failed to transform DEPLOY_AT transaction?", e);
+		}
+	}
+
+	/**
+	 * Creates a trade-bot entry from the 'Alice' viewpoint, i.e. matching RVN to an existing offer.
+	 * <p>
+	 * Requires a chosen trade offer from Bob, passed by <tt>crossChainTradeData</tt>
+	 * and access to a Ravencoin 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 Ravencoin 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 Ravencoin main-net)
+	 * or 'tprv' for (Ravencoin 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 Ravencoin amount expected by 'Bob'.
+	 * <p>
+	 * If the Ravencoin 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 Ravencoin 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, RavencoinACCTv3.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.RAVENCOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				crossChainTradeData.expectedForeignAmount, xprv58, null, lockTimeA, receivingPublicKeyHash);
+
+		// Attempt to backup the trade bot data
+		// Include tradeBotData as an additional parameter, since it's not in the repository yet
+		TradeBot.backupTradeBotData(repository, Arrays.asList(tradeBotData));
+
+		// Check we have enough funds via xprv58 to fund P2SH to cover expectedForeignAmount
+		long p2shFee;
+		try {
+			p2shFee = Ravencoin.getInstance().getP2shFee(now);
+		} catch (ForeignBlockchainException e) {
+			LOGGER.debug("Couldn't estimate Ravencoin 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 = Ravencoin.getInstance().deriveP2shAddress(redeemScriptBytes);
+
+		// Build transaction for funding P2SH-A
+		Transaction p2shFundingTransaction = Ravencoin.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 {
+			Ravencoin.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 = RavencoinACCTv3.buildOfferMessage(tradeBotData.getTradeForeignPublicKeyHash(), tradeBotData.getHashOfSecret(), tradeBotData.getLockTimeA());
+		String messageRecipient = crossChainTradeData.qortalCreatorTradeAddress;
+
+		boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, messageData);
+		if (!isMessageAlreadySent) {
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK) {
+				LOGGER.warn(() -> String.format("Unable to send MESSAGE to Bob's trade-bot %s: %s", messageRecipient, result.name()));
+				return ResponseResult.NETWORK_ISSUE;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Funding P2SH-A %s. Messaged Bob. Waiting for AT-lock", p2shAddress));
+
+		return ResponseResult.OK;
+	}
+
+	@Override
+	public boolean canDelete(Repository repository, TradeBotData tradeBotData) throws DataException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null)
+			return true;
+
+		// If the AT doesn't exist then we might as well let the user tidy up
+		if (!repository.getATRepository().exists(tradeBotData.getAtAddress()))
+			return true;
+
+		switch (tradeBotState) {
+			case BOB_WAITING_FOR_AT_CONFIRM:
+			case ALICE_DONE:
+			case BOB_DONE:
+			case ALICE_REFUNDED:
+			case BOB_REFUNDED:
+			case ALICE_REFUNDING_A:
+				return true;
+
+			default:
+				return false;
+		}
+	}
+
+	@Override
+	public void progress(Repository repository, TradeBotData tradeBotData) throws DataException, ForeignBlockchainException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null) {
+			LOGGER.info(() -> String.format("Trade-bot entry for AT %s has invalid state?", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		ATData atData = null;
+		CrossChainTradeData tradeData = null;
+
+		if (tradeBotState.requiresAtData) {
+			// Attempt to fetch AT data
+			atData = repository.getATRepository().fromATAddress(tradeBotData.getAtAddress());
+			if (atData == null) {
+				LOGGER.debug(() -> String.format("Unable to fetch trade AT %s from repository", tradeBotData.getAtAddress()));
+				return;
+			}
+
+			if (tradeBotState.requiresTradeData) {
+				tradeData = RavencoinACCTv3.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 Ravencoin 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;
+		}
+
+		Ravencoin ravencoin = Ravencoin.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 Ravencoin pubkeyhash and lockTime-A
+			byte[] messageData = messageTransactionData.getData();
+			RavencoinACCTv3.OfferMessageData offerMessageData = RavencoinACCTv3.extractOfferMessageData(messageData);
+			if (offerMessageData == null)
+				continue;
+
+			byte[] aliceForeignPublicKeyHash = offerMessageData.partnerRavencoinPKH;
+			byte[] hashOfSecretA = offerMessageData.hashOfSecretA;
+			int lockTimeA = (int) offerMessageData.lockTimeA;
+			long messageTimestamp = messageTransactionData.getTimestamp();
+			int refundTimeout = RavencoinACCTv3.calcRefundTimeout(messageTimestamp, lockTimeA);
+
+			// Determine P2SH-A address and confirm funded
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(aliceForeignPublicKeyHash, lockTimeA, tradeBotData.getTradeForeignPublicKeyHash(), hashOfSecretA);
+			String p2shAddressA = ravencoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Ravencoin.getInstance().getP2shFee(feeTimestamp);
+			final long minimumAmountA = tradeBotData.getForeignAmount() + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(ravencoin.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 = RavencoinACCTv3.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 RVN 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;
+
+		Ravencoin ravencoin = Ravencoin.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 = ravencoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Ravencoin.getInstance().getP2shFee(feeTimestamp);
+			long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(ravencoin.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 = RavencoinACCTv3.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 = RavencoinACCTv3.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 RVN 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 RVN funds from P2SH-A
+	 * to Bob's 'foreign'/Ravencoin trade legacy-format address, as derived from trade private key.
+	 * <p>
+	 * (This could potentially be 'improved' to send RVN 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 RVN
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_REFUNDED,
+					() -> String.format("AT %s has auto-refunded - trade aborted", tradeBotData.getAtAddress()));
+
+			return;
+		}
+
+		byte[] secretA = RavencoinACCTv3.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
+
+		Ravencoin ravencoin = Ravencoin.getInstance();
+
+		byte[] receivingAccountInfo = tradeBotData.getReceivingAccountInfo();
+		int lockTimeA = crossChainTradeData.lockTimeA;
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(crossChainTradeData.partnerForeignPKH, lockTimeA, crossChainTradeData.creatorForeignPKH, crossChainTradeData.hashOfSecretA);
+		String p2shAddressA = ravencoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Ravencoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(ravencoin.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 = ravencoin.getUnspentOutputs(p2shAddressA);
+
+				Transaction p2shRedeemTransaction = BitcoinyHTLC.buildRedeemTransaction(ravencoin.getNetworkParameters(), redeemAmount, redeemKey,
+						fundingOutputs, redeemScriptA, secretA, receivingAccountInfo);
+
+				ravencoin.broadcastTransaction(p2shRedeemTransaction);
+				break;
+			}
+		}
+
+		String receivingAddress = ravencoin.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;
+
+		Ravencoin ravencoin = Ravencoin.getInstance();
+
+		// We can't refund P2SH-A until median block time has passed lockTime-A (see BIP113)
+		int medianBlockTime = ravencoin.getMedianBlockTime();
+		if (medianBlockTime <= lockTimeA)
+			return;
+
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeA, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+		String p2shAddressA = ravencoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Ravencoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(ravencoin.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 = ravencoin.getUnspentOutputs(p2shAddressA);
+
+				// Determine receive address for refund
+				String receiveAddress = ravencoin.getUnusedReceiveAddress(tradeBotData.getForeignKey());
+				Address receiving = Address.fromString(ravencoin.getNetworkParameters(), receiveAddress);
+
+				Transaction p2shRefundTransaction = BitcoinyHTLC.buildRefundTransaction(ravencoin.getNetworkParameters(), refundAmount, refundKey,
+						fundingOutputs, redeemScriptA, lockTimeA, receiving.getHash());
+
+				ravencoin.broadcastTransaction(p2shRefundTransaction);
+				break;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDED,
+				() -> String.format("LockTime-A reached. Refunded P2SH-A %s. Trade aborted", p2shAddressA));
+	}
+
+	/**
+	 * Returns true if Alice finds AT unexpectedly cancelled, refunded, redeemed or locked to someone else.
+	 * <p>
+	 * Will automatically update trade-bot state to <tt>ALICE_REFUNDING_A</tt> or <tt>ALICE_DONE</tt> as necessary.
+	 * 
+	 * @throws DataException
+	 * @throws ForeignBlockchainException
+	 */
+	private boolean aliceUnexpectedState(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// This is OK
+		if (!atData.getIsFinished() && crossChainTradeData.mode == AcctMode.OFFERING)
+			return false;
+
+		boolean isAtLockedToUs = tradeBotData.getTradeNativeAddress().equals(crossChainTradeData.qortalPartnerAddress);
+
+		if (!atData.getIsFinished() && crossChainTradeData.mode == AcctMode.TRADING)
+			if (isAtLockedToUs) {
+				// AT is trading with us - OK
+				return false;
+			} else {
+				TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+						() -> String.format("AT %s trading with someone else: %s. Refunding & aborting trade", tradeBotData.getAtAddress(), crossChainTradeData.qortalPartnerAddress));
+
+				return true;
+			}
+
+		if (atData.getIsFinished() && crossChainTradeData.mode == AcctMode.REDEEMED && isAtLockedToUs) {
+			// We've redeemed already?
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+					() -> String.format("AT %s already redeemed by us. Trade completed", tradeBotData.getAtAddress()));
+		} else {
+			// Any other state is not good, so start defensive refund
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+					() -> String.format("AT %s cancelled/refunded/redeemed by someone else/invalid state. Refunding & aborting trade", tradeBotData.getAtAddress()));
+		}
+
+		return true;
+	}
+
+	private long calcFeeTimestamp(int lockTimeA, int tradeTimeout) {
+		return (lockTimeA - tradeTimeout * 60) * 1000L;
+	}
+
+}

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

@@ -2,41 +2,38 @@ package org.qortal.controller.tradebot;
 
 import java.awt.TrayIcon.MessageType;
 import java.security.SecureRandom;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Random;
-import java.util.concurrent.locks.ReentrantLock;
+import java.util.*;
+import java.util.function.Supplier;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
-import org.apache.logging.log4j.util.Supplier;
 import org.bitcoinj.core.ECKey;
 import org.qortal.account.PrivateKeyAccount;
 import org.qortal.api.model.crosschain.TradeBotCreateRequest;
 import org.qortal.controller.Controller;
+import org.qortal.controller.Synchronizer;
 import org.qortal.controller.tradebot.AcctTradeBot.ResponseResult;
 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.PresenceTransactionData;
+import org.qortal.data.network.TradePresenceData;
 import org.qortal.event.Event;
 import org.qortal.event.EventBus;
 import org.qortal.event.Listener;
-import org.qortal.group.Group;
 import org.qortal.gui.SysTray;
+import org.qortal.network.Network;
+import org.qortal.network.Peer;
+import org.qortal.network.message.GetTradePresencesMessage;
+import org.qortal.network.message.Message;
+import org.qortal.network.message.TradePresencesMessage;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryManager;
 import org.qortal.repository.hsqldb.HSQLDBImportExport;
 import org.qortal.settings.Settings;
-import org.qortal.transaction.PresenceTransaction;
-import org.qortal.transaction.PresenceTransaction.PresenceType;
-import org.qortal.transaction.Transaction.ValidationResult;
-import org.qortal.transform.transaction.TransactionTransformer;
+import org.qortal.utils.ByteArray;
 import org.qortal.utils.NTP;
 
 import com.google.common.primitives.Longs;
@@ -56,6 +53,15 @@ public class TradeBot implements Listener {
 	private static final Logger LOGGER = LogManager.getLogger(TradeBot.class);
 	private static final Random RANDOM = new SecureRandom();
 
+	/** Maximum lifetime of trade presence timestamp. 30 mins in ms. */
+	private static final long PRESENCE_LIFETIME = 30 * 60 * 1000L;
+	/** How soon before expiry of our own trade presence timestamp that we want to trigger renewal. 5 mins in ms. */
+	private static final long EARLY_RENEWAL_PERIOD = 5 * 60 * 1000L;
+	/** Trade presence timestamps are rounded up to this nearest interval. Bigger values improve grouping of entries in [GET_]TRADE_PRESENCES network messages. 15 mins in ms. */
+	private static final long EXPIRY_ROUNDING = 15 * 60 * 1000L;
+	/** How often we want to broadcast our list of all known trade presences to peers. 5 mins in ms. */
+	private static final long PRESENCE_BROADCAST_INTERVAL = 5 * 60 * 1000L;
+
 	public interface StateNameAndValueSupplier {
 		public String getState();
 		public int getStateValue();
@@ -73,20 +79,40 @@ public class TradeBot implements Listener {
 		}
 	}
 
+	public static class TradePresenceEvent implements Event {
+		private final TradePresenceData tradePresenceData;
+
+		public TradePresenceEvent(TradePresenceData tradePresenceData) {
+			this.tradePresenceData = tradePresenceData;
+		}
+
+		public TradePresenceData getTradePresenceData() {
+			return this.tradePresenceData;
+		}
+	}
+
 	private static final Map<Class<? extends ACCT>, Supplier<AcctTradeBot>> acctTradeBotSuppliers = new HashMap<>();
 	static {
 		acctTradeBotSuppliers.put(BitcoinACCTv1.class, BitcoinACCTv1TradeBot::getInstance);
+		acctTradeBotSuppliers.put(BitcoinACCTv3.class, BitcoinACCTv3TradeBot::getInstance);
 		acctTradeBotSuppliers.put(LitecoinACCTv1.class, LitecoinACCTv1TradeBot::getInstance);
 		acctTradeBotSuppliers.put(LitecoinACCTv2.class, LitecoinACCTv2TradeBot::getInstance);
 		acctTradeBotSuppliers.put(LitecoinACCTv3.class, LitecoinACCTv3TradeBot::getInstance);
 		acctTradeBotSuppliers.put(DogecoinACCTv1.class, DogecoinACCTv1TradeBot::getInstance);
 		acctTradeBotSuppliers.put(DogecoinACCTv2.class, DogecoinACCTv2TradeBot::getInstance);
 		acctTradeBotSuppliers.put(DogecoinACCTv3.class, DogecoinACCTv3TradeBot::getInstance);
+		acctTradeBotSuppliers.put(DigibyteACCTv3.class, DigibyteACCTv3TradeBot::getInstance);
+		acctTradeBotSuppliers.put(RavencoinACCTv3.class, RavencoinACCTv3TradeBot::getInstance);
 	}
 
 	private static TradeBot instance;
 
-	private final Map<String, Long> presenceTimestampsByAtAddress = Collections.synchronizedMap(new HashMap<>());
+	private final Map<ByteArray, Long> ourTradePresenceTimestampsByPubkey = Collections.synchronizedMap(new HashMap<>());
+	private final List<TradePresenceData> pendingTradePresences = Collections.synchronizedList(new ArrayList<>());
+
+	private final Map<ByteArray, TradePresenceData> allTradePresencesByPubkey = Collections.synchronizedMap(new HashMap<>());
+	private Map<ByteArray, TradePresenceData> safeAllTradePresencesByPubkey = Collections.emptyMap();
+	private long nextTradePresenceBroadcastTimestamp = 0L;
 
 	private TradeBot() {
 		EventBus.INSTANCE.addListener(event -> TradeBot.getInstance().listen(event));
@@ -213,10 +239,17 @@ public class TradeBot implements Listener {
 
 	@Override
 	public void listen(Event event) {
-		if (!(event instanceof Controller.NewBlockEvent))
+		if (!(event instanceof Synchronizer.NewChainTipEvent))
+			return;
+
+		// Don't process trade bots or broadcast presence timestamps if our chain is more than 30 minutes old
+		final Long minLatestBlockTimestamp = NTP.getTime() - (30 * 60 * 1000L);
+		if (!Controller.getInstance().isUpToDate(minLatestBlockTimestamp))
 			return;
 
 		synchronized (this) {
+			expireOldPresenceTimestamps();
+
 			List<TradeBotData> allTradeBotData;
 
 			try (final Repository repository = RepositoryManager.getRepository()) {
@@ -247,6 +280,8 @@ public class TradeBot implements Listener {
 				} catch (ForeignBlockchainException e) {
 					LOGGER.warn(() -> String.format("Foreign blockchain issue processing trade-bot entry for AT %s: %s", tradeBotData.getAtAddress(), e.getMessage()));
 				}
+
+			broadcastPresenceTimestamps();
 		}
 	}
 
@@ -324,6 +359,33 @@ public class TradeBot implements Listener {
 	}
 
 	// PRESENCE-related
+
+	public Collection<TradePresenceData> getAllTradePresences() {
+		return this.safeAllTradePresencesByPubkey.values();
+	}
+
+	/** Trade presence timestamps expire in the 'future' so any that reach 'now' have expired and are removed. */
+	private void expireOldPresenceTimestamps() {
+		long now = NTP.getTime();
+
+		int allRemovedCount = 0;
+		synchronized (this.allTradePresencesByPubkey) {
+			int preRemoveCount = this.allTradePresencesByPubkey.size();
+			this.allTradePresencesByPubkey.values().removeIf(tradePresenceData -> tradePresenceData.getTimestamp() <= now);
+			allRemovedCount = this.allTradePresencesByPubkey.size() - preRemoveCount;
+		}
+
+		int ourRemovedCount = 0;
+		synchronized (this.ourTradePresenceTimestampsByPubkey) {
+			int preRemoveCount = this.ourTradePresenceTimestampsByPubkey.size();
+			this.ourTradePresenceTimestampsByPubkey.values().removeIf(timestamp -> timestamp < now);
+			ourRemovedCount = this.ourTradePresenceTimestampsByPubkey.size() - preRemoveCount;
+		}
+
+		if (allRemovedCount > 0)
+			LOGGER.debug("Removed {} expired trade presences, of which {} ours", allRemovedCount, ourRemovedCount);
+	}
+
 	/*package*/ void updatePresence(Repository repository, TradeBotData tradeBotData, CrossChainTradeData tradeData)
 			throws DataException {
 		String atAddress = tradeBotData.getAtAddress();
@@ -332,44 +394,292 @@ public class TradeBot implements Listener {
 		String signerAddress = tradeNativeAccount.getAddress();
 
 		/*
-		 * There's no point in Alice trying to build a PRESENCE transaction
-		 * for an AT that isn't locked to her, as other peers won't be able
-		 * to validate the PRESENCE transaction as signing public key won't
-		 * be visible.
-		 */
-		if (!signerAddress.equals(tradeData.qortalCreatorTradeAddress) && !signerAddress.equals(tradeData.qortalPartnerAddress))
-			// Signer is neither Bob, nor Alice, or trade not yet locked to Alice
+		* There's no point in Alice trying to broadcast presence for an AT that isn't locked to her,
+		* as other peers won't be able to verify as signing public key isn't yet in the AT's data segment.
+		*/
+		if (!signerAddress.equals(tradeData.qortalCreatorTradeAddress) && !signerAddress.equals(tradeData.qortalPartnerAddress)) {
+			// Signer is neither Bob, nor trade locked to Alice
+			LOGGER.trace("Can't provide trade presence for our AT {} as it's not yet locked to Alice", atAddress);
 			return;
+		}
 
 		long now = NTP.getTime();
-		long threshold = now - PresenceType.TRADE_BOT.getLifetime();
+		long newExpiry = generateExpiry(now);
+		ByteArray pubkeyByteArray = ByteArray.wrap(tradeNativeAccount.getPublicKey());
 
-		long timestamp = presenceTimestampsByAtAddress.compute(atAddress, (k, v) -> (v == null || v < threshold) ? now : v);
+		// If map entry's timestamp is missing, or within early renewal period, use the new expiry - otherwise use existing timestamp.
+		synchronized (this.ourTradePresenceTimestampsByPubkey) {
+			Long currentTimestamp = this.ourTradePresenceTimestampsByPubkey.get(pubkeyByteArray);
 
-		// If timestamp hasn't been updated then nothing to do
-		if (timestamp != now)
+			if (currentTimestamp != null && currentTimestamp - now > EARLY_RENEWAL_PERIOD) {
+				// timestamp still good
+				LOGGER.trace("Current trade presence timestamp {} still good for our trade {}", currentTimestamp, atAddress);
+				return;
+			}
+
+			this.ourTradePresenceTimestampsByPubkey.put(pubkeyByteArray, newExpiry);
+		}
+
+		// Create signature
+		byte[] signature = tradeNativeAccount.sign(Longs.toByteArray(newExpiry));
+
+		// Add new trade presence to queue to be broadcast around network
+		TradePresenceData tradePresenceData = new TradePresenceData(newExpiry, tradeNativeAccount.getPublicKey(), signature, atAddress);
+		this.pendingTradePresences.add(tradePresenceData);
+
+		this.allTradePresencesByPubkey.put(pubkeyByteArray, tradePresenceData);
+		rebuildSafeAllTradePresences();
+
+		LOGGER.trace("New trade presence timestamp {} for our trade {}", newExpiry, atAddress);
+
+		EventBus.INSTANCE.notify(new TradePresenceEvent(tradePresenceData));
+	}
+
+	private void rebuildSafeAllTradePresences() {
+		synchronized (this.allTradePresencesByPubkey) {
+			// Collect into a *new* unmodifiable map.
+			this.safeAllTradePresencesByPubkey = Map.copyOf(this.allTradePresencesByPubkey);
+		}
+	}
+
+	private void broadcastPresenceTimestamps() {
+		// If we have new trade presences that are pending broadcast, send those as a priority
+		if (!this.pendingTradePresences.isEmpty()) {
+			// Create a copy for Network to safely use in another thread
+			List<TradePresenceData> safeTradePresences;
+			synchronized (this.pendingTradePresences) {
+				safeTradePresences = List.copyOf(this.pendingTradePresences);
+				this.pendingTradePresences.clear();
+			}
+
+			LOGGER.debug("Broadcasting {} new trade presences", safeTradePresences.size());
+
+			TradePresencesMessage tradePresencesMessage = new TradePresencesMessage(safeTradePresences);
+			Network.getInstance().broadcast(peer -> tradePresencesMessage);
+
+			return;
+		}
+
+		// As we have no new trade presences, check whether it's time to do a general broadcast
+		Long now = NTP.getTime();
+		if (now == null || now < nextTradePresenceBroadcastTimestamp)
 			return;
 
-		int txGroupId = Group.NO_GROUP;
-		byte[] reference = new byte[TransactionTransformer.SIGNATURE_LENGTH];
-		byte[] creatorPublicKey = tradeNativeAccount.getPublicKey();
-		long fee = 0L;
+		nextTradePresenceBroadcastTimestamp = now + PRESENCE_BROADCAST_INTERVAL;
 
-		BaseTransactionData baseTransactionData = new BaseTransactionData(timestamp, txGroupId, reference, creatorPublicKey, fee, null);
+		List<TradePresenceData> safeTradePresences = List.copyOf(this.safeAllTradePresencesByPubkey.values());
 
-		int nonce = 0;
-		byte[] timestampSignature = tradeNativeAccount.sign(Longs.toByteArray(timestamp));
+		if (safeTradePresences.isEmpty())
+			return;
 
-		PresenceTransactionData transactionData = new PresenceTransactionData(baseTransactionData, nonce, PresenceType.TRADE_BOT, timestampSignature);
+		LOGGER.debug("Broadcasting all {} known trade presences. Next broadcast timestamp: {}",
+				safeTradePresences.size(), nextTradePresenceBroadcastTimestamp
+		);
 
-		PresenceTransaction presenceTransaction = new PresenceTransaction(repository, transactionData);
-		presenceTransaction.computeNonce();
+		GetTradePresencesMessage getTradePresencesMessage = new GetTradePresencesMessage(safeTradePresences);
+		Network.getInstance().broadcast(peer -> getTradePresencesMessage);
+	}
 
-		presenceTransaction.sign(tradeNativeAccount);
+	// Network message processing
 
-		ValidationResult result = presenceTransaction.importAsUnconfirmed();
-		if (result != ValidationResult.OK)
-			LOGGER.debug(() -> String.format("Unable to build trade-bot PRESENCE transaction for %s: %s", tradeBotData.getAtAddress(), result.name()));
+	public void onGetTradePresencesMessage(Peer peer, Message message) {
+		GetTradePresencesMessage getTradePresencesMessage = (GetTradePresencesMessage) message;
+
+		List<TradePresenceData> peersTradePresences = getTradePresencesMessage.getTradePresences();
+
+		// Create mutable copy from safe snapshot
+		Map<ByteArray, TradePresenceData> entriesUnknownToPeer = new HashMap<>(this.safeAllTradePresencesByPubkey);
+		int knownCount = entriesUnknownToPeer.size();
+
+		for (TradePresenceData peersTradePresence : peersTradePresences) {
+			ByteArray pubkeyByteArray = ByteArray.wrap(peersTradePresence.getPublicKey());
+
+			TradePresenceData ourEntry = entriesUnknownToPeer.get(pubkeyByteArray);
+
+			if (ourEntry != null && ourEntry.getTimestamp() == peersTradePresence.getTimestamp())
+				entriesUnknownToPeer.remove(pubkeyByteArray);
+		}
+
+		if (entriesUnknownToPeer.isEmpty())
+			return;
+
+		LOGGER.debug("Sending {} trade presences to peer {} after excluding their {} from known {}",
+				entriesUnknownToPeer.size(), peer, peersTradePresences.size(), knownCount
+		);
+
+		// Send complement to peer
+		List<TradePresenceData> safeTradePresences = List.copyOf(entriesUnknownToPeer.values());
+		Message responseMessage = new TradePresencesMessage(safeTradePresences);
+		if (!peer.sendMessage(responseMessage)) {
+			peer.disconnect("failed to send TRADE_PRESENCES response");
+			return;
+		}
+	}
+
+	public void onTradePresencesMessage(Peer peer, Message message) {
+		TradePresencesMessage tradePresencesMessage = (TradePresencesMessage) message;
+
+		List<TradePresenceData> peersTradePresences = tradePresencesMessage.getTradePresences();
+
+		long now = NTP.getTime();
+		// Timestamps before this are too far into the past
+		long pastThreshold = now;
+		// Timestamps after this are too far into the future
+		long futureThreshold = now + PRESENCE_LIFETIME;
+
+		Map<ByteArray, Supplier<ACCT>> acctSuppliersByCodeHash = SupportedBlockchain.getAcctMap();
+
+		int newCount = 0;
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			for (TradePresenceData peersTradePresence : peersTradePresences) {
+				long timestamp = peersTradePresence.getTimestamp();
+
+				// Ignore if timestamp is out of bounds
+				if (timestamp < pastThreshold || timestamp > futureThreshold) {
+					if (timestamp < pastThreshold)
+						LOGGER.trace("Ignoring trade presence {} from peer {} as timestamp {} is too old vs {}",
+								peersTradePresence.getAtAddress(), peer, timestamp, pastThreshold
+								);
+					else
+						LOGGER.trace("Ignoring trade presence {} from peer {} as timestamp {} is too new vs {}",
+								peersTradePresence.getAtAddress(), peer, timestamp, pastThreshold
+						);
+
+					continue;
+				}
+
+				ByteArray pubkeyByteArray = ByteArray.wrap(peersTradePresence.getPublicKey());
+
+				// Ignore if we've previously verified this timestamp+publickey combo or sent timestamp is older
+				TradePresenceData existingTradeData = this.safeAllTradePresencesByPubkey.get(pubkeyByteArray);
+				if (existingTradeData != null && timestamp <= existingTradeData.getTimestamp()) {
+					if (timestamp == existingTradeData.getTimestamp())
+						LOGGER.trace("Ignoring trade presence {} from peer {} as we have verified timestamp {} before",
+								peersTradePresence.getAtAddress(), peer, timestamp
+						);
+					else
+						LOGGER.trace("Ignoring trade presence {} from peer {} as timestamp {} is older than latest {}",
+								peersTradePresence.getAtAddress(), peer, timestamp, existingTradeData.getTimestamp()
+						);
+
+					continue;
+				}
+
+				// Check timestamp signature
+				byte[] timestampSignature = peersTradePresence.getSignature();
+				byte[] timestampBytes = Longs.toByteArray(timestamp);
+				byte[] publicKey = peersTradePresence.getPublicKey();
+				if (!Crypto.verify(publicKey, timestampSignature, timestampBytes)) {
+					LOGGER.trace("Ignoring trade presence {} from peer {} as signature failed to verify",
+							peersTradePresence.getAtAddress(), peer
+					);
+
+					continue;
+				}
+
+				ATData atData = repository.getATRepository().fromATAddress(peersTradePresence.getAtAddress());
+				if (atData == null || atData.getIsFrozen() || atData.getIsFinished()) {
+					if (atData == null)
+						LOGGER.trace("Ignoring trade presence {} from peer {} as AT doesn't exist",
+								peersTradePresence.getAtAddress(), peer
+						);
+					else
+						LOGGER.trace("Ignoring trade presence {} from peer {} as AT is frozen or finished",
+								peersTradePresence.getAtAddress(), peer
+						);
+
+					continue;
+				}
+
+				ByteArray atCodeHash = ByteArray.wrap(atData.getCodeHash());
+				Supplier<ACCT> acctSupplier = acctSuppliersByCodeHash.get(atCodeHash);
+				if (acctSupplier == null) {
+					LOGGER.trace("Ignoring trade presence {} from peer {} as AT isn't a known ACCT?",
+							peersTradePresence.getAtAddress(), peer
+					);
+
+					continue;
+				}
+
+				CrossChainTradeData tradeData = acctSupplier.get().populateTradeData(repository, atData);
+				if (tradeData == null) {
+					LOGGER.trace("Ignoring trade presence {} from peer {} as trade data not found?",
+							peersTradePresence.getAtAddress(), peer
+					);
+
+					continue;
+				}
+
+				// Convert signer's public key to address form
+				String signerAddress = peersTradePresence.getTradeAddress();
+
+				// Signer's public key (in address form) must match Bob's / Alice's trade public key (in address form)
+				if (!signerAddress.equals(tradeData.qortalCreatorTradeAddress) && !signerAddress.equals(tradeData.qortalPartnerAddress)) {
+					LOGGER.trace("Ignoring trade presence {} from peer {} as signer isn't Alice or Bob?",
+							peersTradePresence.getAtAddress(), peer
+					);
+
+					continue;
+				}
+
+				// This is new to us
+				this.allTradePresencesByPubkey.put(pubkeyByteArray, peersTradePresence);
+				++newCount;
+
+				LOGGER.trace("Added trade presence {} from peer {} with timestamp {}",
+						peersTradePresence.getAtAddress(), peer, timestamp
+				);
+
+				EventBus.INSTANCE.notify(new TradePresenceEvent(peersTradePresence));
+			}
+		} catch (DataException e) {
+			LOGGER.error("Couldn't process TRADE_PRESENCES message due to repository issue", e);
+		}
+
+		if (newCount > 0) {
+			LOGGER.debug("New trade presences: {}", newCount);
+			rebuildSafeAllTradePresences();
+		}
+	}
+
+	public void bridgePresence(long timestamp, byte[] publicKey, byte[] signature, String atAddress) {
+		long expiry = generateExpiry(timestamp);
+		ByteArray pubkeyByteArray = ByteArray.wrap(publicKey);
+
+		TradePresenceData fakeTradePresenceData = new TradePresenceData(expiry, publicKey, signature, atAddress);
+
+		// Only bridge if trade presence expiry timestamp is newer
+		TradePresenceData computedTradePresenceData = this.allTradePresencesByPubkey.compute(pubkeyByteArray, (k, v) ->
+				v == null || v.getTimestamp() < expiry ? fakeTradePresenceData : v
+		);
+
+		if (computedTradePresenceData == fakeTradePresenceData) {
+			LOGGER.trace("Bridged PRESENCE transaction for trade {} with timestamp {}", atAddress, expiry);
+			rebuildSafeAllTradePresences();
+
+			EventBus.INSTANCE.notify(new TradePresenceEvent(fakeTradePresenceData));
+		}
+	}
+
+	/** Decorates a CrossChainTradeData object with Alice / Bob trade-bot presence timestamp, if available. */
+	public void decorateTradeDataWithPresence(CrossChainTradeData crossChainTradeData) {
+		// Match by AT address, then check for Bob vs Alice
+		this.safeAllTradePresencesByPubkey.values().stream()
+				.filter(tradePresenceData -> tradePresenceData.getAtAddress().equals(crossChainTradeData.qortalAtAddress))
+				.forEach(tradePresenceData -> {
+					String signerAddress = tradePresenceData.getTradeAddress();
+
+					// Signer's public key (in address form) must match Bob's / Alice's trade public key (in address form)
+					if (signerAddress.equals(crossChainTradeData.qortalCreatorTradeAddress))
+						crossChainTradeData.creatorPresenceExpiry = tradePresenceData.getTimestamp();
+					else if (signerAddress.equals(crossChainTradeData.qortalPartnerAddress))
+						crossChainTradeData.partnerPresenceExpiry = tradePresenceData.getTimestamp();
+				});
+	}
+
+	private long generateExpiry(long timestamp) {
+		return ((timestamp - 1) / EXPIRY_ROUNDING) * EXPIRY_ROUNDING + PRESENCE_LIFETIME;
 	}
 
 }

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

@@ -42,30 +42,40 @@ public class Bitcoin extends Bitcoiny {
 			public Collection<ElectrumX.Server> getServers() {
 				return Arrays.asList(
 						// Servers chosen on NO BASIS WHATSOEVER from various sources!
-						new Server("hodlers.beer", Server.ConnectionType.SSL, 50002),
-						new Server("btc.lastingcoin.net", Server.ConnectionType.SSL, 50002),
-						new Server("electrum.bitaroo.net", Server.ConnectionType.SSL, 50002),
-						new Server("bitcoin.grey.pw", Server.ConnectionType.SSL, 50002),
+						// Status verified at https://1209k.com/bitcoin-eye/ele.php?chain=btc
+						//CLOSED new Server("bitcoin.grey.pw", Server.ConnectionType.SSL, 50002),
+						//CLOSED new Server("btc.litepay.ch", Server.ConnectionType.SSL, 50002),
+						//CLOSED new Server("electrum.pabu.io", Server.ConnectionType.SSL, 50002),
+						//CLOSED new Server("electrumx.hodlwallet.com", Server.ConnectionType.SSL, 50002),
+						//CLOSED new Server("gd42.org", Server.ConnectionType.SSL, 50002),
+						//CLOSED new Server("korea.electrum-server.com", Server.ConnectionType.SSL, 50002),
+						//CLOSED new Server("prospero.bitsrc.net", Server.ConnectionType.SSL, 50002),
+						//1.15.0 new Server("alviss.coinjoined.com", Server.ConnectionType.SSL, 50002),
+						//1.15.0 new Server("electrum.acinq.co", Server.ConnectionType.SSL, 50002),
+						//1.14.0 new Server("electrum.coinext.com.br", Server.ConnectionType.SSL, 50002),
+						new Server("104.248.139.211", Server.ConnectionType.SSL, 50002),
+						new Server("142.93.6.38", Server.ConnectionType.SSL, 50002),
+						new Server("157.245.172.236", Server.ConnectionType.SSL, 50002),
+						new Server("167.172.226.175", Server.ConnectionType.SSL, 50002),
+						new Server("167.172.42.31", Server.ConnectionType.SSL, 50002),
+						new Server("178.62.80.20", Server.ConnectionType.SSL, 50002),
 						new Server("185.64.116.15", Server.ConnectionType.SSL, 50002),
-						new Server("alviss.coinjoined.com", Server.ConnectionType.SSL, 50002),
-						new Server("btc.litepay.ch", Server.ConnectionType.SSL, 50002),
-						new Server("xtrum.com", Server.ConnectionType.SSL, 50002),
-						new Server("electrum.acinq.co", Server.ConnectionType.SSL, 50002),
-						new Server("caleb.vegas", Server.ConnectionType.SSL, 50002),
-						new Server("electrum.coinext.com.br", Server.ConnectionType.TCP, 50001),
-						new Server("korea.electrum-server.com", Server.ConnectionType.TCP, 50001),
-						new Server("eai.coincited.net", Server.ConnectionType.TCP, 50001),
-						new Server("electrum.coinext.com.br", Server.ConnectionType.SSL, 50002),
-						new Server("node1.btccuracao.com", Server.ConnectionType.SSL, 50002),
-						new Server("korea.electrum-server.com", Server.ConnectionType.SSL, 50002),
-						new Server("btce.iiiiiii.biz", Server.ConnectionType.SSL, 50002),
+						new Server("68.183.188.105", Server.ConnectionType.SSL, 50002),
 						new Server("bitcoin.lukechilds.co", Server.ConnectionType.SSL, 50002),
-						new Server("guichet.centure.cc", Server.ConnectionType.SSL, 50002),
-						new Server("electrumx.hodlwallet.com", Server.ConnectionType.SSL, 50002),
+						new Server("blkhub.net", Server.ConnectionType.SSL, 50002),
+						new Server("btc.lastingcoin.net", Server.ConnectionType.SSL, 50002),
+						new Server("btce.iiiiiii.biz", Server.ConnectionType.SSL, 50002),
+						new Server("caleb.vegas", Server.ConnectionType.SSL, 50002),
 						new Server("eai.coincited.net", Server.ConnectionType.SSL, 50002),
-						new Server("prospero.bitsrc.net", Server.ConnectionType.SSL, 50002),
-						new Server("gd42.org", Server.ConnectionType.SSL, 50002),
-						new Server("electrum.pabu.io", Server.ConnectionType.SSL, 50002));
+						new Server("electrum.bitaroo.net", Server.ConnectionType.SSL, 50002),
+						new Server("electrumx.dev", Server.ConnectionType.SSL, 50002),
+						new Server("elx.bitske.com", Server.ConnectionType.SSL, 50002),
+						new Server("fortress.qtornado.com", Server.ConnectionType.SSL, 50002),
+						new Server("guichet.centure.cc", Server.ConnectionType.SSL, 50002),
+						new Server("kareoke.qoppa.org", Server.ConnectionType.SSL, 50002),
+						new Server("hodlers.beer", Server.ConnectionType.SSL, 50002),
+						new Server("node1.btccuracao.com", Server.ConnectionType.SSL, 50002),
+						new Server("xtrum.com", Server.ConnectionType.SSL, 50002));
 			}
 
 			@Override

src/main/java/org/qortal/crosschain/BitcoinACCTv3.java

@@ -0,0 +1,858 @@
+package org.qortal.crosschain;
+
+import com.google.common.hash.HashCode;
+import com.google.common.primitives.Bytes;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.ciyam.at.*;
+import org.qortal.account.Account;
+import org.qortal.asset.Asset;
+import org.qortal.at.QortalFunctionCode;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.at.ATStateData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.utils.Base58;
+import org.qortal.utils.BitTwiddling;
+
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.List;
+
+import static org.ciyam.at.OpCode.calcOffset;
+
+/**
+ * Cross-chain trade AT
+ * 
+ * <p>
+ * <ul>
+ * <li>Bob generates Bitcoin & 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 Bitcoin & Qortal 'trade' keys</li>
+ * 			<li>Alice funds Bitcoin 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' Bitcoin 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 Bitcoin 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 Bitcoin trade key and secret-A</li>
+ * 			<li>P2SH-A BTC funds end up at Bitcoin address determined by redeem transaction output(s)</li>
+ * 		</ul>
+ * </li>
+ * </ul>
+ */
+public class BitcoinACCTv3 implements ACCT {
+
+	private static final Logger LOGGER = LogManager.getLogger(BitcoinACCTv3.class);
+
+	public static final String NAME = BitcoinACCTv3.class.getSimpleName();
+	public static final byte[] CODE_BYTES_HASH = HashCode.fromString("676fb9350708dafa054eb0262d655039e393c1eb4918ec582f8d45524c9b4860").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[] partnerBitcoinPKH;
+		public byte[] hashOfSecretA;
+		public long lockTimeA;
+	}
+	public static final int OFFER_MESSAGE_LENGTH = 20 /*partnerBitcoinPKH*/ + 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 Bitcoin 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 BitcoinACCTv3 instance;
+
+	private BitcoinACCTv3() {
+	}
+
+	public static synchronized BitcoinACCTv3 getInstance() {
+		if (instance == null)
+			instance = new BitcoinACCTv3();
+
+		return instance;
+	}
+
+	@Override
+	public byte[] getCodeBytesHash() {
+		return CODE_BYTES_HASH;
+	}
+
+	@Override
+	public int getModeByteOffset() {
+		return MODE_BYTE_OFFSET;
+	}
+
+	@Override
+	public ForeignBlockchain getBlockchain() {
+		return Bitcoin.getInstance();
+	}
+
+	/**
+	 * 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 bitcoinPublicKeyHash 20-byte HASH160 of creator's trade Bitcoin public key
+	 * @param qortAmount how much QORT to pay trade partner if they send correct 32-byte secrets to AT
+	 * @param bitcoinAmount how much BTC the AT creator is expecting to trade
+	 * @param tradeTimeout suggested timeout for entire trade
+	 */
+	public static byte[] buildQortalAT(String creatorTradeAddress, byte[] bitcoinPublicKeyHash, long qortAmount, long bitcoinAmount, int tradeTimeout) {
+		if (bitcoinPublicKeyHash.length != 20)
+			throw new IllegalArgumentException("Bitcoin 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 addrBitcoinPublicKeyHash = addrCounter;
+		addrCounter += 4;
+
+		final int addrQortAmount = addrCounter++;
+		final int addrBitcoinAmount = 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 addrTradeMessagePartnerBitcoinPKHOffset = addrCounter++;
+		final int addrPartnerBitcoinPKHPointer = 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 addrPartnerBitcoinPKH = 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));
+
+		// Bitcoin public key hash
+		assert dataByteBuffer.position() == addrBitcoinPublicKeyHash * MachineState.VALUE_SIZE : "addrBitcoinPublicKeyHash incorrect";
+		dataByteBuffer.put(Bytes.ensureCapacity(bitcoinPublicKeyHash, 32, 0));
+
+		// Redeem Qort amount
+		assert dataByteBuffer.position() == addrQortAmount * MachineState.VALUE_SIZE : "addrQortAmount incorrect";
+		dataByteBuffer.putLong(qortAmount);
+
+		// Expected Bitcoin amount
+		assert dataByteBuffer.position() == addrBitcoinAmount * MachineState.VALUE_SIZE : "addrBitcoinAmount incorrect";
+		dataByteBuffer.putLong(bitcoinAmount);
+
+		// 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 Bitcoin PKH
+		assert dataByteBuffer.position() == addrTradeMessagePartnerBitcoinPKHOffset * MachineState.VALUE_SIZE : "addrTradeMessagePartnerBitcoinPKHOffset incorrect";
+		dataByteBuffer.putLong(32L);
+
+		// Index into data segment of partner's Bitcoin PKH, used by GET_B_IND
+		assert dataByteBuffer.position() == addrPartnerBitcoinPKHPointer * MachineState.VALUE_SIZE : "addrPartnerBitcoinPKHPointer incorrect";
+		dataByteBuffer.putLong(addrPartnerBitcoinPKH);
+
+		// 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 */
+
+				// Use AT creation 'timestamp' as starting point for finding transactions sent to AT
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_CREATION_TIMESTAMP, addrLastTxnTimestamp));
+
+				// Load B register with AT creator's address so we can save it into addrCreatorAddress1-4
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_CREATOR_INTO_B));
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrCreatorAddressPointer));
+
+				// Set restart position to after this opcode
+				codeByteBuffer.put(OpCode.SET_PCS.compile());
+
+				/* Loop, waiting for message from AT creator's trade address containing trade partner details, or AT owner's address to cancel offer */
+
+				/* Transaction processing loop */
+				labelTradeTxnLoop = codeByteBuffer.position();
+
+				/* Sleep until message arrives */
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.SLEEP_UNTIL_MESSAGE.value, addrLastTxnTimestamp));
+
+				// Find next transaction (if any) to this AT since the last one (referenced by addrLastTxnTimestamp)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PUT_TX_AFTER_TIMESTAMP_INTO_A, addrLastTxnTimestamp));
+				// If no transaction found, A will be zero. If A is zero, set addrResult to 1, otherwise 0.
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.CHECK_A_IS_ZERO, addrResult));
+				// If addrResult is zero (i.e. A is non-zero, transaction was found) then go check transaction
+				codeByteBuffer.put(OpCode.BZR_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelCheckTradeTxn)));
+				// Stop and wait for next block
+				codeByteBuffer.put(OpCode.STP_IMD.compile());
+
+				/* Check transaction */
+				labelCheckTradeTxn = codeByteBuffer.position();
+
+				// Update our 'last found transaction's timestamp' using 'timestamp' from transaction
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TIMESTAMP_FROM_TX_IN_A, addrLastTxnTimestamp));
+				// Extract transaction type (message/payment) from transaction and save type in addrTxnType
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TYPE_FROM_TX_IN_A, addrTxnType));
+				// If transaction type is not MESSAGE type then go look for another transaction
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrTxnType, addrMessageTxnType, calcOffset(codeByteBuffer, labelTradeTxnLoop)));
+
+				/* Check transaction's sender. We're expecting AT creator's trade address for 'trade' message, or AT creator's own address for 'cancel' message. */
+
+				// Extract sender address from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_ADDRESS_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrMessageSender1 (as pointed to by addrMessageSenderPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageSenderPointer));
+				// Compare each part of message sender's address with AT creator's trade address. If they don't match, check for cancel situation.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrCreatorTradeAddress1, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrCreatorTradeAddress2, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrCreatorTradeAddress3, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrCreatorTradeAddress4, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				// Message sender's address matches AT creator's trade address so go process 'trade' message
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelCheckNonRefundTradeTxn == null ? 0 : labelCheckNonRefundTradeTxn));
+
+				/* Checking message sender for possible cancel message */
+				labelCheckCancelTxn = codeByteBuffer.position();
+
+				// Compare each part of message sender's address with AT creator's address. If they don't match, look for another transaction.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrCreatorAddress1, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrCreatorAddress2, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrCreatorAddress3, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrCreatorAddress4, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				// Partner address is AT creator's address, so cancel offer and finish.
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.CANCELLED.value));
+				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
+				codeByteBuffer.put(OpCode.FIN_IMD.compile());
+
+				/* Not trade nor cancel message */
+				labelNotTradeNorCancelTxn = codeByteBuffer.position();
+
+				// Loop to find another transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelTradeTxnLoop == null ? 0 : labelTradeTxnLoop));
+
+				/* Possible switch-to-trade-mode message */
+				labelCheckNonRefundTradeTxn = codeByteBuffer.position();
+
+				// Check 'trade' message we received has expected number of message bytes
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(QortalFunctionCode.GET_MESSAGE_LENGTH_FROM_TX_IN_A.value, addrMessageLength));
+				// If message length matches, branch to info extraction code
+				codeByteBuffer.put(OpCode.BEQ_DAT.compile(addrMessageLength, addrExpectedTradeMessageLength, calcOffset(codeByteBuffer, labelTradeTxnExtract)));
+				// Message length didn't match - go back to finding another 'trade' MESSAGE transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelTradeTxnLoop == null ? 0 : labelTradeTxnLoop));
+
+				/* Extracting info from 'trade' MESSAGE transaction */
+				labelTradeTxnExtract = codeByteBuffer.position();
+
+				// Extract message from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_MESSAGE_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrQortalPartnerAddress1 (as pointed to by addrQortalPartnerAddressPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrQortalPartnerAddressPointer));
+
+				// Extract trade partner's Bitcoin 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, addrTradeMessagePartnerBitcoinPKHOffset));
+				// Store partner's Bitcoin PKH (we only really use values from B1-B3)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrPartnerBitcoinPKHPointer));
+				// 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();
+
+				/* NOP - to ensure BITCOIN ACCT is unique */
+				codeByteBuffer.put(OpCode.NOP.compile());
+
+				// 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 BTC-QORT ACCT?", e);
+			}
+		}
+
+		codeByteBuffer.flip();
+
+		byte[] codeBytes = new byte[codeByteBuffer.limit()];
+		codeByteBuffer.get(codeBytes);
+
+		assert Arrays.equals(Crypto.digest(codeBytes), BitcoinACCTv3.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.BITCOIN.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 Bitcoin/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 BTC 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 Bitcoin PKH
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to partner's Bitcoin 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 Bitcoin PKH
+		byte[] partnerBitcoinPKH = new byte[20];
+		dataByteBuffer.get(partnerBitcoinPKH);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - partnerBitcoinPKH.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 = partnerBitcoinPKH;
+			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.partnerBitcoinPKH = 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/Bitcoiny.java

@@ -58,9 +58,14 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 	 * i.e. keys with transactions but with no unspent outputs. */
 	protected final Set<ECKey> spentKeys = Collections.synchronizedSet(new HashSet<>());
 
-	/** How many bitcoinj wallet keys to generate in each batch. */
+	/** How many wallet keys to generate in each batch. */
 	private static final int WALLET_KEY_LOOKAHEAD_INCREMENT = 3;
 
+	/** How many wallet keys to generate when using bitcoinj as the data provider.
+	 * We must use a higher value here since we are unable to request multiple batches of keys.
+	 * Without this, the bitcoinj state can be missing transactions, causing errors such as "insufficient balance". */
+	private static final int WALLET_KEY_LOOKAHEAD_INCREMENT_BITCOINJ = 50;
+
 	/** Byte offset into raw block headers to block timestamp. */
 	private static final int TIMESTAMP_OFFSET = 4 + 32 + 32;
 
@@ -99,8 +104,9 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 		try {
 			ScriptType addressType = Address.fromString(this.params, address).getOutputScriptType();
 
-			return addressType == ScriptType.P2PKH || addressType == ScriptType.P2SH;
+			return addressType == ScriptType.P2PKH || addressType == ScriptType.P2SH || addressType == ScriptType.P2WPKH;
 		} catch (AddressFormatException e) {
+			LOGGER.error(String.format("Unrecognised address format: %s", address));
 			return false;
 		}
 	}
@@ -404,7 +410,7 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 			Set<String> keySet = new HashSet<>();
 
 			// Set the number of consecutive empty batches required before giving up
-			final int numberOfAdditionalBatchesToSearch = 5;
+			final int numberOfAdditionalBatchesToSearch = 7;
 
 			int unusedCounter = 0;
 			int ki = 0;
@@ -470,6 +476,9 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 		List<SimpleTransaction.Input> inputs = new ArrayList<>();
 		List<SimpleTransaction.Output> outputs = new ArrayList<>();
 
+		boolean anyOutputAddressInWallet = false;
+		boolean transactionInvolvesExternalWallet = false;
+
 		for (BitcoinyTransaction.Input input : t.inputs) {
 			try {
 				BitcoinyTransaction t2 = getTransaction(input.outputTxHash);
@@ -483,6 +492,9 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 							total += inputAmount;
 							addressInWallet = true;
 						}
+						else {
+							transactionInvolvesExternalWallet = true;
+						}
 						inputs.add(new SimpleTransaction.Input(sender, inputAmount, addressInWallet));
 					}
 				}
@@ -496,12 +508,16 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 					for (String address : output.addresses) {
 						boolean addressInWallet = false;
 						if (keySet.contains(address)) {
-							if (total > 0L) {
+							if (total > 0L) { // Change returned from sent amount
 								amount -= (total - output.value);
-							} else {
+							} else { // Amount received
 								amount += output.value;
 							}
 							addressInWallet = true;
+							anyOutputAddressInWallet = true;
+						}
+						else {
+							transactionInvolvesExternalWallet = true;
 						}
 						outputs.add(new SimpleTransaction.Output(address, output.value, addressInWallet));
 					}
@@ -510,6 +526,17 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 			}
 		}
 		long fee = totalInputAmount - totalOutputAmount;
+
+		if (!anyOutputAddressInWallet) {
+			// No outputs relate to this wallet - check if any inputs did (which is signified by a positive total)
+			if (total > 0) {
+				amount = total * -1;
+			}
+		}
+		else if (!transactionInvolvesExternalWallet) {
+			// All inputs and outputs relate to this wallet, so the balance should be unaffected
+			amount = 0;
+		}
 		return new SimpleTransaction(t.txHash, t.timestamp, amount, fee, inputs, outputs);
 	}
 
@@ -602,7 +629,7 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 			this.keyChain = this.wallet.getActiveKeyChain();
 
 			// Set up wallet's key chain
-			this.keyChain.setLookaheadSize(Bitcoiny.WALLET_KEY_LOOKAHEAD_INCREMENT);
+			this.keyChain.setLookaheadSize(Bitcoiny.WALLET_KEY_LOOKAHEAD_INCREMENT_BITCOINJ);
 			this.keyChain.maybeLookAhead();
 		}
 

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

@@ -0,0 +1,171 @@
+package org.qortal.crosschain;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.EnumMap;
+import java.util.Map;
+
+import org.bitcoinj.core.Coin;
+import org.bitcoinj.core.Context;
+import org.bitcoinj.core.NetworkParameters;
+import org.bitcoinj.params.RegTestParams;
+import org.bitcoinj.params.TestNet3Params;
+import org.libdohj.params.DigibyteMainNetParams;
+import org.qortal.crosschain.ElectrumX.Server;
+import org.qortal.crosschain.ElectrumX.Server.ConnectionType;
+import org.qortal.settings.Settings;
+
+public class Digibyte extends Bitcoiny {
+
+	public static final String CURRENCY_CODE = "DGB";
+
+	private static final Coin DEFAULT_FEE_PER_KB = Coin.valueOf(100000); // 0.001 DGB per 1000 bytes
+
+	private static final long MINIMUM_ORDER_AMOUNT = 1000000; // 0.01 DGB minimum order, to avoid dust errors
+
+	// Temporary values until a dynamic fee system is written.
+	private static final long MAINNET_FEE = 10000L;
+	private static final long NON_MAINNET_FEE = 10000L; // enough for TESTNET3 and should be OK for REGTEST
+
+	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 DigibyteNet {
+		MAIN {
+			@Override
+			public NetworkParameters getParams() {
+				return DigibyteMainNetParams.get();
+			}
+
+			@Override
+			public Collection<Server> getServers() {
+				return Arrays.asList(
+						// Servers chosen on NO BASIS WHATSOEVER from various sources!
+						// Status verified at https://1209k.com/bitcoin-eye/ele.php?chain=dgb
+						new Server("electrum1.cipig.net", ConnectionType.SSL, 20059),
+						new Server("electrum2.cipig.net", ConnectionType.SSL, 20059),
+						new Server("electrum3.cipig.net", ConnectionType.SSL, 20059));
+			}
+
+			@Override
+			public String getGenesisHash() {
+				return "7497ea1b465eb39f1c8f507bc877078fe016d6fcb6dfad3a64c98dcc6e1e8496";
+			}
+
+			@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 TestNet3Params.get();
+			}
+
+			@Override
+			public Collection<Server> getServers() {
+				return Arrays.asList(); // TODO: find testnet servers
+			}
+
+			@Override
+			public String getGenesisHash() {
+				return "308ea0711d5763be2995670dd9ca9872753561285a84da1d58be58acaa822252";
+			}
+
+			@Override
+			public long getP2shFee(Long timestamp) {
+				return NON_MAINNET_FEE;
+			}
+		},
+		REGTEST {
+			@Override
+			public NetworkParameters getParams() {
+				return RegTestParams.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 Digibyte instance;
+
+	private final DigibyteNet digibyteNet;
+
+	// Constructors and instance
+
+	private Digibyte(DigibyteNet digibyteNet, BitcoinyBlockchainProvider blockchain, Context bitcoinjContext, String currencyCode) {
+		super(blockchain, bitcoinjContext, currencyCode);
+		this.digibyteNet = digibyteNet;
+
+		LOGGER.info(() -> String.format("Starting Digibyte support using %s", this.digibyteNet.name()));
+	}
+
+	public static synchronized Digibyte getInstance() {
+		if (instance == null) {
+			DigibyteNet digibyteNet = Settings.getInstance().getDigibyteNet();
+
+			BitcoinyBlockchainProvider electrumX = new ElectrumX("Digibyte-" + digibyteNet.name(), digibyteNet.getGenesisHash(), digibyteNet.getServers(), DEFAULT_ELECTRUMX_PORTS);
+			Context bitcoinjContext = new Context(digibyteNet.getParams());
+
+			instance = new Digibyte(digibyteNet, 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 DGB 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.digibyteNet.getP2shFee(timestamp);
+	}
+
+}

src/main/java/org/qortal/crosschain/DigibyteACCTv3.java

@@ -0,0 +1,858 @@
+package org.qortal.crosschain;
+
+import com.google.common.hash.HashCode;
+import com.google.common.primitives.Bytes;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.ciyam.at.*;
+import org.qortal.account.Account;
+import org.qortal.asset.Asset;
+import org.qortal.at.QortalFunctionCode;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.at.ATStateData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.utils.Base58;
+import org.qortal.utils.BitTwiddling;
+
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.List;
+
+import static org.ciyam.at.OpCode.calcOffset;
+
+/**
+ * Cross-chain trade AT
+ * 
+ * <p>
+ * <ul>
+ * <li>Bob generates Digibyte & 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 Digibyte & Qortal 'trade' keys</li>
+ * 			<li>Alice funds Digibyte 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' Digibyte 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 Digibyte 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 Digibyte trade key and secret-A</li>
+ * 			<li>P2SH-A DGB funds end up at Digibyte address determined by redeem transaction output(s)</li>
+ * 		</ul>
+ * </li>
+ * </ul>
+ */
+public class DigibyteACCTv3 implements ACCT {
+
+	private static final Logger LOGGER = LogManager.getLogger(DigibyteACCTv3.class);
+
+	public static final String NAME = DigibyteACCTv3.class.getSimpleName();
+	public static final byte[] CODE_BYTES_HASH = HashCode.fromString("e6a7dcd87296fae3ce7d80183bf7660c8e2cb4f8746c6a0421a17148f87a0e1d").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[] partnerDigibytePKH;
+		public byte[] hashOfSecretA;
+		public long lockTimeA;
+	}
+	public static final int OFFER_MESSAGE_LENGTH = 20 /*partnerDigibytePKH*/ + 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 Digibyte 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 DigibyteACCTv3 instance;
+
+	private DigibyteACCTv3() {
+	}
+
+	public static synchronized DigibyteACCTv3 getInstance() {
+		if (instance == null)
+			instance = new DigibyteACCTv3();
+
+		return instance;
+	}
+
+	@Override
+	public byte[] getCodeBytesHash() {
+		return CODE_BYTES_HASH;
+	}
+
+	@Override
+	public int getModeByteOffset() {
+		return MODE_BYTE_OFFSET;
+	}
+
+	@Override
+	public ForeignBlockchain getBlockchain() {
+		return Digibyte.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 digibytePublicKeyHash 20-byte HASH160 of creator's trade Digibyte public key
+	 * @param qortAmount how much QORT to pay trade partner if they send correct 32-byte secrets to AT
+	 * @param digibyteAmount how much DGB the AT creator is expecting to trade
+	 * @param tradeTimeout suggested timeout for entire trade
+	 */
+	public static byte[] buildQortalAT(String creatorTradeAddress, byte[] digibytePublicKeyHash, long qortAmount, long digibyteAmount, int tradeTimeout) {
+		if (digibytePublicKeyHash.length != 20)
+			throw new IllegalArgumentException("Digibyte 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 addrDigibytePublicKeyHash = addrCounter;
+		addrCounter += 4;
+
+		final int addrQortAmount = addrCounter++;
+		final int addrDigibyteAmount = 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 addrTradeMessagePartnerDigibytePKHOffset = addrCounter++;
+		final int addrPartnerDigibytePKHPointer = 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 addrPartnerDigibytePKH = 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));
+
+		// Digibyte public key hash
+		assert dataByteBuffer.position() == addrDigibytePublicKeyHash * MachineState.VALUE_SIZE : "addrDigibytePublicKeyHash incorrect";
+		dataByteBuffer.put(Bytes.ensureCapacity(digibytePublicKeyHash, 32, 0));
+
+		// Redeem Qort amount
+		assert dataByteBuffer.position() == addrQortAmount * MachineState.VALUE_SIZE : "addrQortAmount incorrect";
+		dataByteBuffer.putLong(qortAmount);
+
+		// Expected Digibyte amount
+		assert dataByteBuffer.position() == addrDigibyteAmount * MachineState.VALUE_SIZE : "addrDigibyteAmount incorrect";
+		dataByteBuffer.putLong(digibyteAmount);
+
+		// 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 Digibyte PKH
+		assert dataByteBuffer.position() == addrTradeMessagePartnerDigibytePKHOffset * MachineState.VALUE_SIZE : "addrTradeMessagePartnerDigibytePKHOffset incorrect";
+		dataByteBuffer.putLong(32L);
+
+		// Index into data segment of partner's Digibyte PKH, used by GET_B_IND
+		assert dataByteBuffer.position() == addrPartnerDigibytePKHPointer * MachineState.VALUE_SIZE : "addrPartnerDigibytePKHPointer incorrect";
+		dataByteBuffer.putLong(addrPartnerDigibytePKH);
+
+		// 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 */
+
+				// 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));
+
+				/* NOP - to ensure DIGIBYTE ACCT is unique */
+				codeByteBuffer.put(OpCode.NOP.compile());
+
+				// Load B register with AT creator's address so we can save it into addrCreatorAddress1-4
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_CREATOR_INTO_B));
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrCreatorAddressPointer));
+
+				// Set restart position to after this opcode
+				codeByteBuffer.put(OpCode.SET_PCS.compile());
+
+				/* Loop, waiting for message from AT creator's trade address containing trade partner details, or AT owner's address to cancel offer */
+
+				/* Transaction processing loop */
+				labelTradeTxnLoop = codeByteBuffer.position();
+
+				/* Sleep until message arrives */
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.SLEEP_UNTIL_MESSAGE.value, addrLastTxnTimestamp));
+
+				// Find next transaction (if any) to this AT since the last one (referenced by addrLastTxnTimestamp)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PUT_TX_AFTER_TIMESTAMP_INTO_A, addrLastTxnTimestamp));
+				// If no transaction found, A will be zero. If A is zero, set addrResult to 1, otherwise 0.
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.CHECK_A_IS_ZERO, addrResult));
+				// If addrResult is zero (i.e. A is non-zero, transaction was found) then go check transaction
+				codeByteBuffer.put(OpCode.BZR_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelCheckTradeTxn)));
+				// Stop and wait for next block
+				codeByteBuffer.put(OpCode.STP_IMD.compile());
+
+				/* Check transaction */
+				labelCheckTradeTxn = codeByteBuffer.position();
+
+				// Update our 'last found transaction's timestamp' using 'timestamp' from transaction
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TIMESTAMP_FROM_TX_IN_A, addrLastTxnTimestamp));
+				// Extract transaction type (message/payment) from transaction and save type in addrTxnType
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TYPE_FROM_TX_IN_A, addrTxnType));
+				// If transaction type is not MESSAGE type then go look for another transaction
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrTxnType, addrMessageTxnType, calcOffset(codeByteBuffer, labelTradeTxnLoop)));
+
+				/* Check transaction's sender. We're expecting AT creator's trade address for 'trade' message, or AT creator's own address for 'cancel' message. */
+
+				// Extract sender address from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_ADDRESS_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrMessageSender1 (as pointed to by addrMessageSenderPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageSenderPointer));
+				// Compare each part of message sender's address with AT creator's trade address. If they don't match, check for cancel situation.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrCreatorTradeAddress1, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrCreatorTradeAddress2, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrCreatorTradeAddress3, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrCreatorTradeAddress4, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				// Message sender's address matches AT creator's trade address so go process 'trade' message
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelCheckNonRefundTradeTxn == null ? 0 : labelCheckNonRefundTradeTxn));
+
+				/* Checking message sender for possible cancel message */
+				labelCheckCancelTxn = codeByteBuffer.position();
+
+				// Compare each part of message sender's address with AT creator's address. If they don't match, look for another transaction.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrCreatorAddress1, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrCreatorAddress2, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrCreatorAddress3, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrCreatorAddress4, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				// Partner address is AT creator's address, so cancel offer and finish.
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.CANCELLED.value));
+				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
+				codeByteBuffer.put(OpCode.FIN_IMD.compile());
+
+				/* Not trade nor cancel message */
+				labelNotTradeNorCancelTxn = codeByteBuffer.position();
+
+				// Loop to find another transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelTradeTxnLoop == null ? 0 : labelTradeTxnLoop));
+
+				/* Possible switch-to-trade-mode message */
+				labelCheckNonRefundTradeTxn = codeByteBuffer.position();
+
+				// Check 'trade' message we received has expected number of message bytes
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(QortalFunctionCode.GET_MESSAGE_LENGTH_FROM_TX_IN_A.value, addrMessageLength));
+				// If message length matches, branch to info extraction code
+				codeByteBuffer.put(OpCode.BEQ_DAT.compile(addrMessageLength, addrExpectedTradeMessageLength, calcOffset(codeByteBuffer, labelTradeTxnExtract)));
+				// Message length didn't match - go back to finding another 'trade' MESSAGE transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelTradeTxnLoop == null ? 0 : labelTradeTxnLoop));
+
+				/* Extracting info from 'trade' MESSAGE transaction */
+				labelTradeTxnExtract = codeByteBuffer.position();
+
+				// Extract message from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_MESSAGE_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrQortalPartnerAddress1 (as pointed to by addrQortalPartnerAddressPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrQortalPartnerAddressPointer));
+
+				// Extract trade partner's Digibyte 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, addrTradeMessagePartnerDigibytePKHOffset));
+				// Store partner's Digibyte PKH (we only really use values from B1-B3)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrPartnerDigibytePKHPointer));
+				// 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 DGB-QORT ACCT?", e);
+			}
+		}
+
+		codeByteBuffer.flip();
+
+		byte[] codeBytes = new byte[codeByteBuffer.limit()];
+		codeByteBuffer.get(codeBytes);
+
+		assert Arrays.equals(Crypto.digest(codeBytes), DigibyteACCTv3.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.DIGIBYTE.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 Digibyte/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 DGB 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 Digibyte PKH
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to partner's Digibyte 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 Digibyte PKH
+		byte[] partnerDigibytePKH = new byte[20];
+		dataByteBuffer.get(partnerDigibytePKH);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - partnerDigibytePKH.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 = partnerDigibytePKH;
+			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.partnerDigibytePKH = 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/Dogecoin.java

@@ -45,9 +45,9 @@ public class Dogecoin extends Bitcoiny {
 			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));
+						new Server("electrum1.cipig.net", ConnectionType.SSL, 20060),
+						new Server("electrum2.cipig.net", ConnectionType.SSL, 20060),
+						new Server("electrum3.cipig.net", ConnectionType.SSL, 20060));
 						// TODO: add more mainnet servers. It's too centralized.
 			}
 

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

@@ -401,13 +401,36 @@ public class ElectrumX extends BitcoinyBlockchainProvider {
 				String scriptPubKey = (String) ((JSONObject) outputJson.get("scriptPubKey")).get("hex");
 				long value = BigDecimal.valueOf((Double) outputJson.get("value")).setScale(8).unscaledValue().longValue();
 
-				// address too, if present
+				// address too, if present in the "addresses" array
 				List<String> addresses = null;
 				Object addressesObj = ((JSONObject) outputJson.get("scriptPubKey")).get("addresses");
 				if (addressesObj instanceof JSONArray) {
 					addresses = new ArrayList<>();
-					for (Object addressObj : (JSONArray) addressesObj)
+					for (Object addressObj : (JSONArray) addressesObj) {
 						addresses.add((String) addressObj);
+					}
+				}
+
+				// some peers return a single "address" string
+				Object addressObj = ((JSONObject) outputJson.get("scriptPubKey")).get("address");
+				if (addressObj instanceof String) {
+					if (addresses == null) {
+						addresses = new ArrayList<>();
+					}
+					addresses.add((String) addressObj);
+				}
+
+				// For the purposes of Qortal we require all outputs to contain addresses
+				// Some servers omit this info, causing problems down the line with balance calculations
+				// Update: it turns out that they were just using a different key - "address" instead of "addresses"
+				// The code below can remain in place, just in case a peer returns a missing address in the future
+				if (addresses == null || addresses.isEmpty()) {
+					if (this.currentServer != null) {
+						this.uselessServers.add(this.currentServer);
+						this.closeServer(this.currentServer);
+					}
+					LOGGER.info("No output addresses returned for transaction {}", txHash);
+					throw new ForeignBlockchainException(String.format("No output addresses returned for transaction %s", txHash));
 				}
 
 				outputs.add(new BitcoinyTransaction.Output(scriptPubKey, value, addresses));

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

@@ -44,23 +44,17 @@ public class Litecoin extends Bitcoiny {
 			public Collection<ElectrumX.Server> getServers() {
 				return Arrays.asList(
 						// Servers chosen on NO BASIS WHATSOEVER from various sources!
-						new Server("electrum-ltc.someguy123.net", Server.ConnectionType.SSL, 50002),
-						new Server("backup.electrum-ltc.org", Server.ConnectionType.TCP, 50001),
+						// Status verified at https://1209k.com/bitcoin-eye/ele.php?chain=ltc
+						//CLOSED new Server("electrum-ltc.petrkr.net", Server.ConnectionType.SSL, 60002),
+						//CLOSED new Server("electrum-ltc.someguy123.net", Server.ConnectionType.SSL, 50002),
+						//PHISHY new Server("electrum-ltc.bysh.me", Server.ConnectionType.SSL, 50002),
 						new Server("backup.electrum-ltc.org", Server.ConnectionType.SSL, 443),
-						new Server("electrum.ltc.xurious.com", Server.ConnectionType.TCP, 50001),
 						new Server("electrum.ltc.xurious.com", Server.ConnectionType.SSL, 50002),
-						new Server("electrum-ltc.bysh.me", Server.ConnectionType.SSL, 50002),
+						new Server("electrum1.cipig.net", Server.ConnectionType.SSL, 20063),
 						new Server("electrum2.cipig.net", Server.ConnectionType.SSL, 20063),
 						new Server("electrum3.cipig.net", Server.ConnectionType.SSL, 20063),
-						new Server("electrum3.cipig.net", ConnectionType.TCP, 10063),
-						new Server("electrum2.cipig.net", Server.ConnectionType.TCP, 10063),
-						new Server("electrum1.cipig.net", Server.ConnectionType.SSL, 20063),
-						new Server("electrum1.cipig.net", Server.ConnectionType.TCP, 10063),
-						new Server("electrum-ltc.petrkr.net", Server.ConnectionType.SSL, 60002),
 						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));
+						new Server("ltc.rentonrisk.com", Server.ConnectionType.SSL, 50002));
 			}
 
 			@Override

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

@@ -0,0 +1,175 @@
+package org.qortal.crosschain;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.EnumMap;
+import java.util.Map;
+
+import org.bitcoinj.core.Coin;
+import org.bitcoinj.core.Context;
+import org.bitcoinj.core.NetworkParameters;
+import org.bitcoinj.params.RegTestParams;
+import org.bitcoinj.params.TestNet3Params;
+import org.libdohj.params.RavencoinMainNetParams;
+import org.qortal.crosschain.ElectrumX.Server;
+import org.qortal.crosschain.ElectrumX.Server.ConnectionType;
+import org.qortal.settings.Settings;
+
+public class Ravencoin extends Bitcoiny {
+
+	public static final String CURRENCY_CODE = "RVN";
+
+	private static final Coin DEFAULT_FEE_PER_KB = Coin.valueOf(1125000); // 0.01125 RVN per 1000 bytes
+
+	private static final long MINIMUM_ORDER_AMOUNT = 1000000; // 0.01 RVN minimum order, to avoid dust errors
+
+	// Temporary values until a dynamic fee system is written.
+	private static final long MAINNET_FEE = 1000000L;
+	private static final long NON_MAINNET_FEE = 1000000L; // enough for TESTNET3 and should be OK for REGTEST
+
+	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 RavencoinNet {
+		MAIN {
+			@Override
+			public NetworkParameters getParams() {
+				return RavencoinMainNetParams.get();
+			}
+
+			@Override
+			public Collection<Server> getServers() {
+				return Arrays.asList(
+						// Servers chosen on NO BASIS WHATSOEVER from various sources!
+						// Status verified at https://1209k.com/bitcoin-eye/ele.php?chain=rvn
+						new Server("aethyn.com", ConnectionType.SSL, 50002),
+						new Server("electrum2.rvn.rocks", ConnectionType.SSL, 50002),
+						new Server("rvn-dashboard.com", ConnectionType.SSL, 50002),
+						new Server("rvn4lyfe.com", ConnectionType.SSL, 50002),
+						new Server("electrum1.cipig.net", ConnectionType.SSL, 20051),
+						new Server("electrum2.cipig.net", ConnectionType.SSL, 20051),
+						new Server("electrum3.cipig.net", ConnectionType.SSL, 20051));
+			}
+
+			@Override
+			public String getGenesisHash() {
+				return "0000006b444bc2f2ffe627be9d9e7e7a0730000870ef6eb6da46c8eae389df90";
+			}
+
+			@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 TestNet3Params.get();
+			}
+
+			@Override
+			public Collection<Server> getServers() {
+				return Arrays.asList(); // TODO: find testnet servers
+			}
+
+			@Override
+			public String getGenesisHash() {
+				return "000000ecfc5e6324a079542221d00e10362bdc894d56500c414060eea8a3ad5a";
+			}
+
+			@Override
+			public long getP2shFee(Long timestamp) {
+				return NON_MAINNET_FEE;
+			}
+		},
+		REGTEST {
+			@Override
+			public NetworkParameters getParams() {
+				return RegTestParams.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 Ravencoin instance;
+
+	private final RavencoinNet ravencoinNet;
+
+	// Constructors and instance
+
+	private Ravencoin(RavencoinNet ravencoinNet, BitcoinyBlockchainProvider blockchain, Context bitcoinjContext, String currencyCode) {
+		super(blockchain, bitcoinjContext, currencyCode);
+		this.ravencoinNet = ravencoinNet;
+
+		LOGGER.info(() -> String.format("Starting Ravencoin support using %s", this.ravencoinNet.name()));
+	}
+
+	public static synchronized Ravencoin getInstance() {
+		if (instance == null) {
+			RavencoinNet ravencoinNet = Settings.getInstance().getRavencoinNet();
+
+			BitcoinyBlockchainProvider electrumX = new ElectrumX("Ravencoin-" + ravencoinNet.name(), ravencoinNet.getGenesisHash(), ravencoinNet.getServers(), DEFAULT_ELECTRUMX_PORTS);
+			Context bitcoinjContext = new Context(ravencoinNet.getParams());
+
+			instance = new Ravencoin(ravencoinNet, 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 RVN 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.ravencoinNet.getP2shFee(timestamp);
+	}
+
+}

src/main/java/org/qortal/crosschain/RavencoinACCTv3.java

@@ -0,0 +1,858 @@
+package org.qortal.crosschain;
+
+import com.google.common.hash.HashCode;
+import com.google.common.primitives.Bytes;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.ciyam.at.*;
+import org.qortal.account.Account;
+import org.qortal.asset.Asset;
+import org.qortal.at.QortalFunctionCode;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.at.ATStateData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.utils.Base58;
+import org.qortal.utils.BitTwiddling;
+
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.List;
+
+import static org.ciyam.at.OpCode.calcOffset;
+
+/**
+ * Cross-chain trade AT
+ * 
+ * <p>
+ * <ul>
+ * <li>Bob generates Ravencoin & 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 Ravencoin & Qortal 'trade' keys</li>
+ * 			<li>Alice funds Ravencoin 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' Ravencoin 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 Ravencoin 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 Ravencoin trade key and secret-A</li>
+ * 			<li>P2SH-A RVN funds end up at Ravencoin address determined by redeem transaction output(s)</li>
+ * 		</ul>
+ * </li>
+ * </ul>
+ */
+public class RavencoinACCTv3 implements ACCT {
+
+	private static final Logger LOGGER = LogManager.getLogger(RavencoinACCTv3.class);
+
+	public static final String NAME = RavencoinACCTv3.class.getSimpleName();
+	public static final byte[] CODE_BYTES_HASH = HashCode.fromString("91395fa1ec0dfa35beddb0a7f4cc0a1bede157c38787ddb0af0cf03dfdc10f77").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[] partnerRavencoinPKH;
+		public byte[] hashOfSecretA;
+		public long lockTimeA;
+	}
+	public static final int OFFER_MESSAGE_LENGTH = 20 /*partnerRavencoinPKH*/ + 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 Ravencoin 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 RavencoinACCTv3 instance;
+
+	private RavencoinACCTv3() {
+	}
+
+	public static synchronized RavencoinACCTv3 getInstance() {
+		if (instance == null)
+			instance = new RavencoinACCTv3();
+
+		return instance;
+	}
+
+	@Override
+	public byte[] getCodeBytesHash() {
+		return CODE_BYTES_HASH;
+	}
+
+	@Override
+	public int getModeByteOffset() {
+		return MODE_BYTE_OFFSET;
+	}
+
+	@Override
+	public ForeignBlockchain getBlockchain() {
+		return Ravencoin.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 ravencoinPublicKeyHash 20-byte HASH160 of creator's trade Ravencoin public key
+	 * @param qortAmount how much QORT to pay trade partner if they send correct 32-byte secrets to AT
+	 * @param ravencoinAmount how much RVN the AT creator is expecting to trade
+	 * @param tradeTimeout suggested timeout for entire trade
+	 */
+	public static byte[] buildQortalAT(String creatorTradeAddress, byte[] ravencoinPublicKeyHash, long qortAmount, long ravencoinAmount, int tradeTimeout) {
+		if (ravencoinPublicKeyHash.length != 20)
+			throw new IllegalArgumentException("Ravencoin 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 addrRavencoinPublicKeyHash = addrCounter;
+		addrCounter += 4;
+
+		final int addrQortAmount = addrCounter++;
+		final int addrRavencoinAmount = 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 addrTradeMessagePartnerRavencoinPKHOffset = addrCounter++;
+		final int addrPartnerRavencoinPKHPointer = 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 addrPartnerRavencoinPKH = 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));
+
+		// Ravencoin public key hash
+		assert dataByteBuffer.position() == addrRavencoinPublicKeyHash * MachineState.VALUE_SIZE : "addrRavencoinPublicKeyHash incorrect";
+		dataByteBuffer.put(Bytes.ensureCapacity(ravencoinPublicKeyHash, 32, 0));
+
+		// Redeem Qort amount
+		assert dataByteBuffer.position() == addrQortAmount * MachineState.VALUE_SIZE : "addrQortAmount incorrect";
+		dataByteBuffer.putLong(qortAmount);
+
+		// Expected Ravencoin amount
+		assert dataByteBuffer.position() == addrRavencoinAmount * MachineState.VALUE_SIZE : "addrRavencoinAmount incorrect";
+		dataByteBuffer.putLong(ravencoinAmount);
+
+		// 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 Ravencoin PKH
+		assert dataByteBuffer.position() == addrTradeMessagePartnerRavencoinPKHOffset * MachineState.VALUE_SIZE : "addrTradeMessagePartnerRavencoinPKHOffset incorrect";
+		dataByteBuffer.putLong(32L);
+
+		// Index into data segment of partner's Ravencoin PKH, used by GET_B_IND
+		assert dataByteBuffer.position() == addrPartnerRavencoinPKHPointer * MachineState.VALUE_SIZE : "addrPartnerRavencoinPKHPointer incorrect";
+		dataByteBuffer.putLong(addrPartnerRavencoinPKH);
+
+		// 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 */
+
+				// 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));
+
+				/* NOP - to ensure RAVENCOIN ACCT is unique */
+				codeByteBuffer.put(OpCode.NOP.compile());
+
+				// Set restart position to after this opcode
+				codeByteBuffer.put(OpCode.SET_PCS.compile());
+
+				/* Loop, waiting for message from AT creator's trade address containing trade partner details, or AT owner's address to cancel offer */
+
+				/* Transaction processing loop */
+				labelTradeTxnLoop = codeByteBuffer.position();
+
+				/* Sleep until message arrives */
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.SLEEP_UNTIL_MESSAGE.value, addrLastTxnTimestamp));
+
+				// Find next transaction (if any) to this AT since the last one (referenced by addrLastTxnTimestamp)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PUT_TX_AFTER_TIMESTAMP_INTO_A, addrLastTxnTimestamp));
+				// If no transaction found, A will be zero. If A is zero, set addrResult to 1, otherwise 0.
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.CHECK_A_IS_ZERO, addrResult));
+				// If addrResult is zero (i.e. A is non-zero, transaction was found) then go check transaction
+				codeByteBuffer.put(OpCode.BZR_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelCheckTradeTxn)));
+				// Stop and wait for next block
+				codeByteBuffer.put(OpCode.STP_IMD.compile());
+
+				/* Check transaction */
+				labelCheckTradeTxn = codeByteBuffer.position();
+
+				// Update our 'last found transaction's timestamp' using 'timestamp' from transaction
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TIMESTAMP_FROM_TX_IN_A, addrLastTxnTimestamp));
+				// Extract transaction type (message/payment) from transaction and save type in addrTxnType
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TYPE_FROM_TX_IN_A, addrTxnType));
+				// If transaction type is not MESSAGE type then go look for another transaction
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrTxnType, addrMessageTxnType, calcOffset(codeByteBuffer, labelTradeTxnLoop)));
+
+				/* Check transaction's sender. We're expecting AT creator's trade address for 'trade' message, or AT creator's own address for 'cancel' message. */
+
+				// Extract sender address from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_ADDRESS_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrMessageSender1 (as pointed to by addrMessageSenderPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageSenderPointer));
+				// Compare each part of message sender's address with AT creator's trade address. If they don't match, check for cancel situation.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrCreatorTradeAddress1, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrCreatorTradeAddress2, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrCreatorTradeAddress3, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrCreatorTradeAddress4, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				// Message sender's address matches AT creator's trade address so go process 'trade' message
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelCheckNonRefundTradeTxn == null ? 0 : labelCheckNonRefundTradeTxn));
+
+				/* Checking message sender for possible cancel message */
+				labelCheckCancelTxn = codeByteBuffer.position();
+
+				// Compare each part of message sender's address with AT creator's address. If they don't match, look for another transaction.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrCreatorAddress1, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrCreatorAddress2, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrCreatorAddress3, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrCreatorAddress4, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				// Partner address is AT creator's address, so cancel offer and finish.
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.CANCELLED.value));
+				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
+				codeByteBuffer.put(OpCode.FIN_IMD.compile());
+
+				/* Not trade nor cancel message */
+				labelNotTradeNorCancelTxn = codeByteBuffer.position();
+
+				// Loop to find another transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelTradeTxnLoop == null ? 0 : labelTradeTxnLoop));
+
+				/* Possible switch-to-trade-mode message */
+				labelCheckNonRefundTradeTxn = codeByteBuffer.position();
+
+				// Check 'trade' message we received has expected number of message bytes
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(QortalFunctionCode.GET_MESSAGE_LENGTH_FROM_TX_IN_A.value, addrMessageLength));
+				// If message length matches, branch to info extraction code
+				codeByteBuffer.put(OpCode.BEQ_DAT.compile(addrMessageLength, addrExpectedTradeMessageLength, calcOffset(codeByteBuffer, labelTradeTxnExtract)));
+				// Message length didn't match - go back to finding another 'trade' MESSAGE transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelTradeTxnLoop == null ? 0 : labelTradeTxnLoop));
+
+				/* Extracting info from 'trade' MESSAGE transaction */
+				labelTradeTxnExtract = codeByteBuffer.position();
+
+				// Extract message from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_MESSAGE_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrQortalPartnerAddress1 (as pointed to by addrQortalPartnerAddressPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrQortalPartnerAddressPointer));
+
+				// Extract trade partner's Ravencoin 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, addrTradeMessagePartnerRavencoinPKHOffset));
+				// Store partner's Ravencoin PKH (we only really use values from B1-B3)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrPartnerRavencoinPKHPointer));
+				// 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 RVN-QORT ACCT?", e);
+			}
+		}
+
+		codeByteBuffer.flip();
+
+		byte[] codeBytes = new byte[codeByteBuffer.limit()];
+		codeByteBuffer.get(codeBytes);
+
+		assert Arrays.equals(Crypto.digest(codeBytes), RavencoinACCTv3.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.RAVENCOIN.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 Ravencoin/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 RVN 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 Ravencoin PKH
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to partner's Ravencoin 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 Ravencoin PKH
+		byte[] partnerRavencoinPKH = new byte[20];
+		dataByteBuffer.get(partnerRavencoinPKH);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - partnerRavencoinPKH.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 = partnerRavencoinPKH;
+			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.partnerRavencoinPKH = 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/SupportedBlockchain.java

@@ -13,8 +13,8 @@ import org.qortal.utils.Triple;
 public enum SupportedBlockchain {
 
 	BITCOIN(Arrays.asList(
-				Triple.valueOf(BitcoinACCTv1.NAME, BitcoinACCTv1.CODE_BYTES_HASH, BitcoinACCTv1::getInstance)
-				// Could add improved BitcoinACCTv2 here in the future
+				Triple.valueOf(BitcoinACCTv1.NAME, BitcoinACCTv1.CODE_BYTES_HASH, BitcoinACCTv1::getInstance),
+				Triple.valueOf(BitcoinACCTv3.NAME, BitcoinACCTv3.CODE_BYTES_HASH, BitcoinACCTv3::getInstance)
 			)) {
 		@Override
 		public ForeignBlockchain getInstance() {
@@ -23,7 +23,7 @@ public enum SupportedBlockchain {
 
 		@Override
 		public ACCT getLatestAcct() {
-			return BitcoinACCTv1.getInstance();
+			return BitcoinACCTv3.getInstance();
 		}
 	},
 
@@ -57,12 +57,40 @@ public enum SupportedBlockchain {
 		public ACCT getLatestAcct() {
 			return DogecoinACCTv3.getInstance();
 		}
+	},
+
+	DIGIBYTE(Arrays.asList(
+			Triple.valueOf(DigibyteACCTv3.NAME, DigibyteACCTv3.CODE_BYTES_HASH, DigibyteACCTv3::getInstance)
+		)) {
+		@Override
+		public ForeignBlockchain getInstance() {
+			return Digibyte.getInstance();
+		}
+
+		@Override
+		public ACCT getLatestAcct() {
+			return DigibyteACCTv3.getInstance();
+		}
+	},
+
+	RAVENCOIN(Arrays.asList(
+			Triple.valueOf(RavencoinACCTv3.NAME, RavencoinACCTv3.CODE_BYTES_HASH, RavencoinACCTv3::getInstance)
+		)) {
+		@Override
+		public ForeignBlockchain getInstance() {
+			return Ravencoin.getInstance();
+		}
+
+		@Override
+		public ACCT getLatestAcct() {
+			return RavencoinACCTv3.getInstance();
+		}
 	};
 
 	private static final Map<ByteArray, Supplier<ACCT>> supportedAcctsByCodeHash = Arrays.stream(SupportedBlockchain.values())
 			.map(supportedBlockchain -> supportedBlockchain.supportedAccts)
 			.flatMap(List::stream)
-			.collect(Collectors.toUnmodifiableMap(triple -> new ByteArray(triple.getB()), Triple::getC));
+			.collect(Collectors.toUnmodifiableMap(triple -> ByteArray.wrap(triple.getB()), Triple::getC));
 
 	private static final Map<String, Supplier<ACCT>> supportedAcctsByName = Arrays.stream(SupportedBlockchain.values())
 			.map(supportedBlockchain -> supportedBlockchain.supportedAccts)
@@ -94,7 +122,7 @@ public enum SupportedBlockchain {
 			return getAcctMap();
 
 		return blockchain.supportedAccts.stream()
-				.collect(Collectors.toUnmodifiableMap(triple -> new ByteArray(triple.getB()), Triple::getC));
+				.collect(Collectors.toUnmodifiableMap(triple -> ByteArray.wrap(triple.getB()), Triple::getC));
 	}
 
 	public static Map<ByteArray, Supplier<ACCT>> getFilteredAcctMap(String specificBlockchain) {
@@ -109,7 +137,7 @@ public enum SupportedBlockchain {
 	}
 
 	public static ACCT getAcctByCodeHash(byte[] codeHash) {
-		ByteArray wrappedCodeHash = new ByteArray(codeHash);
+		ByteArray wrappedCodeHash = ByteArray.wrap(codeHash);
 
 		Supplier<ACCT> acctInstanceSupplier = supportedAcctsByCodeHash.get(wrappedCodeHash);
 

src/main/java/org/qortal/data/arbitrary/ArbitraryCategoryInfo.java

@@ -0,0 +1,12 @@
+package org.qortal.data.arbitrary;
+
+public class ArbitraryCategoryInfo {
+
+    public String id;
+    public String name;
+
+    public ArbitraryCategoryInfo() {
+
+    }
+
+}

src/main/java/org/qortal/data/arbitrary/ArbitraryDirectConnectionInfo.java

@@ -0,0 +1,59 @@
+package org.qortal.data.arbitrary;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Objects;
+
+public class ArbitraryDirectConnectionInfo {
+
+    private final byte[] signature;
+    private final String peerAddress;
+    private final List<byte[]> hashes;
+    private final long timestamp;
+
+    public ArbitraryDirectConnectionInfo(byte[] signature, String peerAddress, List<byte[]> hashes, long timestamp) {
+        this.signature = signature;
+        this.peerAddress = peerAddress;
+        this.hashes = hashes;
+        this.timestamp = timestamp;
+    }
+
+    public byte[] getSignature() {
+        return this.signature;
+    }
+
+    public String getPeerAddress() {
+        return this.peerAddress;
+    }
+
+    public List<byte[]> getHashes() {
+        return this.hashes;
+    }
+    
+    public long getTimestamp() {
+        return this.timestamp;
+    }
+
+    public int getHashCount() {
+        if (this.hashes == null) {
+            return 0;
+        }
+        return this.hashes.size();
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        if (other == this)
+            return true;
+
+        if (!(other instanceof ArbitraryDirectConnectionInfo))
+            return false;
+
+        ArbitraryDirectConnectionInfo otherDirectConnectionInfo = (ArbitraryDirectConnectionInfo) other;
+
+        return Arrays.equals(this.signature, otherDirectConnectionInfo.getSignature())
+                && Objects.equals(this.peerAddress, otherDirectConnectionInfo.getPeerAddress())
+                && Objects.equals(this.hashes, otherDirectConnectionInfo.getHashes())
+                && Objects.equals(this.timestamp, otherDirectConnectionInfo.getTimestamp());
+    }
+}

src/main/java/org/qortal/data/arbitrary/ArbitraryFileListResponseInfo.java

@@ -0,0 +1,11 @@
+package org.qortal.data.arbitrary;
+
+import org.qortal.network.Peer;
+
+public class ArbitraryFileListResponseInfo extends  ArbitraryRelayInfo {
+
+    public ArbitraryFileListResponseInfo(String hash58, String signature58, Peer peer, Long timestamp, Long requestTime, Integer requestHops) {
+        super(hash58, signature58, peer, timestamp, requestTime, requestHops);
+    }
+
+}

src/main/java/org/qortal/data/arbitrary/ArbitraryRelayInfo.java

@@ -9,12 +9,16 @@ public class ArbitraryRelayInfo {
     private final String signature58;
     private final Peer peer;
     private final Long timestamp;
+    private final Long requestTime;
+    private final Integer requestHops;
 
-    public ArbitraryRelayInfo(String hash58, String signature58, Peer peer, Long timestamp) {
+    public ArbitraryRelayInfo(String hash58, String signature58, Peer peer, Long timestamp, Long requestTime, Integer requestHops) {
         this.hash58 = hash58;
         this.signature58 = signature58;
         this.peer = peer;
         this.timestamp = timestamp;
+        this.requestTime = requestTime;
+        this.requestHops = requestHops;
     }
 
     public boolean isValid() {
@@ -38,6 +42,14 @@ public class ArbitraryRelayInfo {
         return timestamp;
     }
 
+    public Long getRequestTime() {
+        return this.requestTime;
+    }
+
+    public Integer getRequestHops() {
+        return this.requestHops;
+    }
+
     @Override
     public String toString() {
         return String.format("%s = %s, %s, %d", this.hash58, this.signature58, this.peer, this.timestamp);

src/main/java/org/qortal/data/arbitrary/ArbitraryResourceInfo.java

@@ -13,6 +13,7 @@ public class ArbitraryResourceInfo {
 	public Service service;
 	public String identifier;
 	public ArbitraryResourceStatus status;
+	public ArbitraryResourceMetadata metadata;
 
 	public Long size;
 

src/main/java/org/qortal/data/arbitrary/ArbitraryResourceMetadata.java

@@ -0,0 +1,45 @@
+package org.qortal.data.arbitrary;
+
+import org.qortal.arbitrary.metadata.ArbitraryDataTransactionMetadata;
+import org.qortal.arbitrary.misc.Category;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import java.util.List;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class ArbitraryResourceMetadata {
+
+    private String title;
+    private String description;
+    private List<String> tags;
+    private Category category;
+    private String categoryName;
+
+    public ArbitraryResourceMetadata() {
+    }
+
+    public ArbitraryResourceMetadata(String title, String description, List<String> tags, Category category) {
+        this.title = title;
+        this.description = description;
+        this.tags = tags;
+        this.category = category;
+        this.categoryName = category.getName();
+    }
+
+    public static ArbitraryResourceMetadata fromTransactionMetadata(ArbitraryDataTransactionMetadata transactionMetadata) {
+        if (transactionMetadata == null) {
+            return null;
+        }
+        String title = transactionMetadata.getTitle();
+        String description = transactionMetadata.getDescription();
+        List<String> tags = transactionMetadata.getTags();
+        Category category = transactionMetadata.getCategory();
+
+        if (title == null && description == null && tags == null && category == null) {
+            return null;
+        }
+
+        return new ArbitraryResourceMetadata(title, description, tags, category);
+    }
+}

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

@@ -94,6 +94,12 @@ public class CrossChainTradeData {
 
 	public String acctName;
 
+	@Schema(description = "Timestamp when AT creator's trade-bot presence expires")
+	public Long creatorPresenceExpiry;
+
+	@Schema(description = "Timestamp when trade partner's trade-bot presence expires")
+	public Long partnerPresenceExpiry;
+
 	// Constructors
 
 	// Necessary for JAXB

src/main/java/org/qortal/data/group/GroupData.java

@@ -23,6 +23,7 @@ public class GroupData {
 	private ApprovalThreshold approvalThreshold;
 	private int minimumBlockDelay;
 	private int maximumBlockDelay;
+	public int memberCount;
 
 	/** Reference to CREATE_GROUP or UPDATE_GROUP transaction, used to rebuild group during orphaning. */
 	// No need to ever expose this via API

src/main/java/org/qortal/data/network/TradePresenceData.java

@@ -0,0 +1,114 @@
+package org.qortal.data.network;
+
+import org.qortal.crypto.Crypto;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.XmlElement;
+import javax.xml.bind.annotation.XmlTransient;
+import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
+import java.util.Arrays;
+
+// All properties to be converted to JSON via JAXB
+@XmlAccessorType(XmlAccessType.FIELD)
+public class TradePresenceData {
+
+	protected long timestamp;
+
+	@XmlJavaTypeAdapter(
+			type = byte[].class,
+			value = org.qortal.api.Base58TypeAdapter.class
+	)
+	protected byte[] publicKey; // Could be BOB's or ALICE's
+
+	// No need to send this via websocket / API
+	@XmlTransient
+	protected byte[] signature; // Not always present
+
+	protected String atAddress; // Not always present
+
+	// Have JAXB use getter instead
+	@XmlTransient
+	protected String tradeAddress; // Lazily instantiated
+
+	// Constructors
+
+	// necessary for JAXB serialization
+	protected TradePresenceData() {
+	}
+
+	public TradePresenceData(long timestamp, byte[] publicKey, byte[] signature, String atAddress) {
+		this.timestamp = timestamp;
+		this.publicKey = publicKey;
+		this.signature = signature;
+		this.atAddress = atAddress;
+	}
+
+	public TradePresenceData(long timestamp, byte[] publicKey) {
+		this(timestamp, publicKey, null, null);
+	}
+
+	public long getTimestamp() {
+		return this.timestamp;
+	}
+
+	public byte[] getPublicKey() {
+		return this.publicKey;
+	}
+
+	public byte[] getSignature() {
+		return this.signature;
+	}
+
+	public String getAtAddress() {
+		return this.atAddress;
+	}
+
+	// Probably doesn't need synchronization
+	@XmlElement
+	public String getTradeAddress() {
+		if (tradeAddress != null)
+			return tradeAddress;
+
+		tradeAddress = Crypto.toAddress(this.publicKey);
+		return tradeAddress;
+	}
+
+	// Comparison
+
+	@Override
+	public boolean equals(Object other) {
+		if (other == this)
+			return true;
+
+		if (!(other instanceof TradePresenceData))
+			return false;
+
+		TradePresenceData otherTradePresenceData = (TradePresenceData) other;
+
+		// Very quick comparison
+		if (otherTradePresenceData.timestamp != this.timestamp)
+			return false;
+
+		if (!Arrays.equals(otherTradePresenceData.publicKey, this.publicKey))
+			return false;
+
+		if (otherTradePresenceData.atAddress != null && !otherTradePresenceData.atAddress.equals(this.atAddress))
+			return false;
+
+		if (this.atAddress != null && !this.atAddress.equals(otherTradePresenceData.atAddress))
+			return false;
+
+		if (!Arrays.equals(otherTradePresenceData.signature, this.signature))
+			return false;
+
+		return true;
+	}
+
+	@Override
+	public int hashCode() {
+		// Pretty lazy implementation
+		return (int) this.timestamp;
+	}
+
+}

src/main/java/org/qortal/data/transaction/UpdateNameTransactionData.java

@@ -48,6 +48,7 @@ public class UpdateNameTransactionData extends TransactionData {
 
 	public void afterUnmarshal(Unmarshaller u, Object parent) {
 		this.creatorPublicKey = this.ownerPublicKey;
+		this.reducedNewName = this.newName != null ? Unicode.sanitize(this.newName) : null;
 	}
 
 	/** From repository */
@@ -62,7 +63,7 @@ public class UpdateNameTransactionData extends TransactionData {
 		this.nameReference = nameReference;
 	}
 
-	/** From network/API */
+	/** From network */
 	public UpdateNameTransactionData(BaseTransactionData baseTransactionData, String name, String newName, String newData) {
 		this(baseTransactionData, name, newName, newData, Unicode.sanitize(newName), null);
 	}

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

@@ -4,6 +4,7 @@ import java.awt.GraphicsEnvironment;
 import java.awt.image.BufferedImage;
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.ServiceConfigurationError;
 
 import javax.imageio.ImageIO;
 import javax.swing.JOptionPane;
@@ -49,7 +50,7 @@ public class Gui {
 	protected static BufferedImage loadImage(String resourceName) {
 		try (InputStream in = Gui.class.getResourceAsStream("/images/" + resourceName)) {
 			return ImageIO.read(in);
-		} catch (IllegalArgumentException | IOException e) {
+		} catch (IllegalArgumentException | IOException | ServiceConfigurationError e) {
 			LOGGER.warn(String.format("Couldn't locate image resource \"images/%s\"", resourceName));
 			return null;
 		}

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

@@ -13,7 +13,7 @@ import org.qortal.crypto.MemoryPoW;
 import org.qortal.network.message.ChallengeMessage;
 import org.qortal.network.message.HelloMessage;
 import org.qortal.network.message.Message;
-import org.qortal.network.message.Message.MessageType;
+import org.qortal.network.message.MessageType;
 import org.qortal.settings.Settings;
 import org.qortal.network.message.ResponseMessage;
 import org.qortal.utils.DaemonThreadFactory;
@@ -74,6 +74,12 @@ public enum Handshake {
 			peer.setPeersConnectionTimestamp(peersConnectionTimestamp);
 			peer.setPeersVersion(versionString, version);
 
+			// Ensure the peer is running at least the version specified in MIN_PEER_VERSION
+			if (peer.isAtLeastVersion(MIN_PEER_VERSION) == false) {
+				LOGGER.debug(String.format("Ignoring peer %s because it is on an old version (%s)", peer, versionString));
+				return null;
+			}
+
 			if (Settings.getInstance().getAllowConnectionsWithOlderPeerVersions() == false) {
 				// Ensure the peer is running at least the minimum version allowed for connections
 				final String minPeerVersion = Settings.getInstance().getMinPeerVersion();
@@ -258,6 +264,9 @@ public enum Handshake {
 
 	private static final long PEER_VERSION_131 = 0x0100030001L;
 
+	/** Minimum peer version that we are allowed to communicate with */
+	private static final String MIN_PEER_VERSION = "3.1.0";
+
 	private static final int POW_BUFFER_SIZE_PRE_131 = 8 * 1024 * 1024; // bytes
 	private static final int POW_DIFFICULTY_PRE_131 = 8; // leading zero bits
 	// Can always be made harder in the future...

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

@@ -1,5 +1,6 @@
 package org.qortal.network;
 
+import com.dosse.upnp.UPnP;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.bouncycastle.crypto.params.Ed25519PrivateKeyParameters;
@@ -7,12 +8,12 @@ import org.bouncycastle.crypto.params.Ed25519PublicKeyParameters;
 import org.qortal.block.BlockChain;
 import org.qortal.controller.Controller;
 import org.qortal.controller.arbitrary.ArbitraryDataFileListManager;
-import org.qortal.controller.arbitrary.ArbitraryDataManager;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.block.BlockData;
 import org.qortal.data.network.PeerData;
 import org.qortal.data.transaction.TransactionData;
 import org.qortal.network.message.*;
+import org.qortal.network.task.*;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryManager;
@@ -32,6 +33,7 @@ import java.nio.channels.*;
 import java.security.SecureRandom;
 import java.util.*;
 import java.util.concurrent.*;
+import java.util.concurrent.atomic.AtomicLong;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Function;
@@ -41,9 +43,8 @@ import java.util.stream.Collectors;
 // For managing peers
 public class Network {
     private static final Logger LOGGER = LogManager.getLogger(Network.class);
-    private static Network instance;
 
-    private static final int LISTEN_BACKLOG = 10;
+    private static final int LISTEN_BACKLOG = 5;
     /**
      * How long before retrying after a connection failure, in milliseconds.
      */
@@ -100,25 +101,38 @@ public class Network {
     private long nextDisconnectionCheck = 0L;
 
     private final List<PeerData> allKnownPeers = new ArrayList<>();
-    private final List<Peer> connectedPeers = new ArrayList<>();
+
+    /**
+     * Maintain two lists for each subset of peers:
+     * - A synchronizedList, to be modified when peers are added/removed
+     * - An immutable List, which is rebuilt automatically to mirror the synchronized list, and is then served to consumers
+     * This allows for thread safety without having to synchronize every time a thread requests a peer list
+     */
+    private final List<Peer> connectedPeers = Collections.synchronizedList(new ArrayList<>());
+    private List<Peer> immutableConnectedPeers = Collections.emptyList(); // always rebuilt from mutable, synced list above
+
+    private final List<Peer> handshakedPeers = Collections.synchronizedList(new ArrayList<>());
+    private List<Peer> immutableHandshakedPeers = Collections.emptyList(); // always rebuilt from mutable, synced list above
+
+    private final List<Peer> outboundHandshakedPeers = Collections.synchronizedList(new ArrayList<>());
+    private List<Peer> immutableOutboundHandshakedPeers = Collections.emptyList(); // always rebuilt from mutable, synced list above
+
+
     private final List<PeerAddress> selfPeers = new ArrayList<>();
 
     private final ExecuteProduceConsume networkEPC;
     private Selector channelSelector;
     private ServerSocketChannel serverChannel;
-    private Iterator<SelectionKey> channelIterator = null;
-
-    // volatile because value is updated inside any one of the EPC threads
-    private volatile long nextConnectTaskTimestamp = 0L; // ms - try first connect once NTP syncs
-
-    private final ExecutorService broadcastExecutor = Executors.newCachedThreadPool();
-    // volatile because value is updated inside any one of the EPC threads
-    private volatile long nextBroadcastTimestamp = 0L; // ms - try first broadcast once NTP syncs
+    private SelectionKey serverSelectionKey;
+    private final Set<SelectableChannel> channelsPendingWrite = ConcurrentHashMap.newKeySet();
 
     private final Lock mergePeersLock = new ReentrantLock();
 
     private List<String> ourExternalIpAddressHistory = new ArrayList<>();
     private String ourExternalIpAddress = null;
+    private int ourExternalPort = Settings.getInstance().getListenPort();
+
+    private volatile boolean isShuttingDown = false;
 
     // Constructors
 
@@ -153,7 +167,7 @@ public class Network {
             serverChannel.configureBlocking(false);
             serverChannel.setOption(StandardSocketOptions.SO_REUSEADDR, true);
             serverChannel.bind(endpoint, LISTEN_BACKLOG);
-            serverChannel.register(channelSelector, SelectionKey.OP_ACCEPT);
+            serverSelectionKey = serverChannel.register(channelSelector, SelectionKey.OP_ACCEPT);
         } catch (UnknownHostException e) {
             LOGGER.error("Can't bind listen socket to address {}", Settings.getInstance().getBindAddress());
             throw new IOException("Can't bind listen socket to address", e);
@@ -163,7 +177,8 @@ public class Network {
         }
 
         // Load all known peers from repository
-        synchronized (this.allKnownPeers) { List<String> fixedNetwork = Settings.getInstance().getFixedNetwork();
+        synchronized (this.allKnownPeers) {
+            List<String> fixedNetwork = Settings.getInstance().getFixedNetwork();
             if (fixedNetwork != null && !fixedNetwork.isEmpty()) {
                 Long addedWhen = NTP.getTime();
                 String addedBy = "fixedNetwork";
@@ -183,18 +198,30 @@ public class Network {
             }
         }
 
+        // Attempt to set up UPnP. All errors are ignored.
+        if (Settings.getInstance().isUPnPEnabled()) {
+            UPnP.openPortTCP(Settings.getInstance().getListenPort());
+        }
+        else {
+            UPnP.closePortTCP(Settings.getInstance().getListenPort());
+        }
+
         // Start up first networking thread
         networkEPC.start();
     }
 
     // Getters / setters
 
-    public static synchronized Network getInstance() {
-        if (instance == null) {
-            instance = new Network();
-        }
+    private static class SingletonContainer {
+        private static final Network INSTANCE = new Network();
+    }
 
-        return instance;
+    public static Network getInstance() {
+        return SingletonContainer.INSTANCE;
+    }
+
+    public int getMaxPeers() {
+        return this.maxPeers;
     }
 
     public byte[] getMessageMagic() {
@@ -228,10 +255,21 @@ public class Network {
         }
     }
 
-    public List<Peer> getConnectedPeers() {
-        synchronized (this.connectedPeers) {
-            return new ArrayList<>(this.connectedPeers);
-        }
+    public List<Peer> getImmutableConnectedPeers() {
+        return this.immutableConnectedPeers;
+    }
+
+    public void addConnectedPeer(Peer peer) {
+        this.connectedPeers.add(peer); // thread safe thanks to synchronized list
+        this.immutableConnectedPeers = List.copyOf(this.connectedPeers); // also thread safe thanks to synchronized collection's toArray() being fed to List.of(array)
+    }
+
+    public void removeConnectedPeer(Peer peer) {
+        // Firstly remove from handshaked peers
+        this.removeHandshakedPeer(peer);
+
+        this.connectedPeers.remove(peer); // thread safe thanks to synchronized list
+        this.immutableConnectedPeers = List.copyOf(this.connectedPeers); // also thread safe thanks to synchronized collection's toArray() being fed to List.of(array)
     }
 
     public List<PeerAddress> getSelfPeers() {
@@ -243,12 +281,15 @@ public class Network {
     public boolean requestDataFromPeer(String peerAddressString, byte[] signature) {
         if (peerAddressString != null) {
             PeerAddress peerAddress = PeerAddress.fromString(peerAddressString);
+            PeerData peerData = null;
 
             // Reuse an existing PeerData instance if it's already in the known peers list
-            PeerData peerData = this.allKnownPeers.stream()
-                    .filter(knownPeerData -> knownPeerData.getAddress().equals(peerAddress))
-                    .findFirst()
-                    .orElse(null);
+            synchronized (this.allKnownPeers) {
+                peerData = this.allKnownPeers.stream()
+                        .filter(knownPeerData -> knownPeerData.getAddress().equals(peerAddress))
+                        .findFirst()
+                        .orElse(null);
+            }
 
             if (peerData == null) {
                 // Not a known peer, so we need to create one
@@ -263,13 +304,14 @@ public class Network {
             }
 
             // Check if we're already connected to and handshaked with this peer
-            Peer connectedPeer = this.connectedPeers.stream()
-                    .filter(p -> p.getPeerData().getAddress().equals(peerAddress))
-                    .findFirst()
-                    .orElse(null);
+            Peer connectedPeer = this.getImmutableConnectedPeers().stream()
+                        .filter(p -> p.getPeerData().getAddress().equals(peerAddress))
+                        .findFirst()
+                        .orElse(null);
+
             boolean isConnected = (connectedPeer != null);
 
-            boolean isHandshaked = this.getHandshakedPeers().stream()
+            boolean isHandshaked = this.getImmutableHandshakedPeers().stream()
                     .anyMatch(p -> p.getPeerData().getAddress().equals(peerAddress));
 
             if (isConnected && isHandshaked) {
@@ -313,35 +355,61 @@ public class Network {
     /**
      * Returns list of connected peers that have completed handshaking.
      */
-    public List<Peer> getHandshakedPeers() {
-        synchronized (this.connectedPeers) {
-            return this.connectedPeers.stream()
-                    .filter(peer -> peer.getHandshakeStatus() == Handshake.COMPLETED)
-                    .collect(Collectors.toList());
+    public List<Peer> getImmutableHandshakedPeers() {
+        return this.immutableHandshakedPeers;
+    }
+
+    public void addHandshakedPeer(Peer peer) {
+        this.handshakedPeers.add(peer); // thread safe thanks to synchronized list
+        this.immutableHandshakedPeers = List.copyOf(this.handshakedPeers); // also thread safe thanks to synchronized collection's toArray() being fed to List.of(array)
+
+        // Also add to outbound handshaked peers cache
+        if (peer.isOutbound()) {
+            this.addOutboundHandshakedPeer(peer);
+        }
+    }
+
+    public void removeHandshakedPeer(Peer peer) {
+        this.handshakedPeers.remove(peer); // thread safe thanks to synchronized list
+        this.immutableHandshakedPeers = List.copyOf(this.handshakedPeers); // also thread safe thanks to synchronized collection's toArray() being fed to List.of(array)
+
+        // Also remove from outbound handshaked peers cache
+        if (peer.isOutbound()) {
+            this.removeOutboundHandshakedPeer(peer);
         }
     }
 
     /**
      * Returns list of peers we connected to that have completed handshaking.
      */
-    public List<Peer> getOutboundHandshakedPeers() {
-        synchronized (this.connectedPeers) {
-            return this.connectedPeers.stream()
-                    .filter(peer -> peer.isOutbound() && peer.getHandshakeStatus() == Handshake.COMPLETED)
-                    .collect(Collectors.toList());
+    public List<Peer> getImmutableOutboundHandshakedPeers() {
+        return this.immutableOutboundHandshakedPeers;
+    }
+
+    public void addOutboundHandshakedPeer(Peer peer) {
+        if (!peer.isOutbound()) {
+            return;
         }
+        this.outboundHandshakedPeers.add(peer); // thread safe thanks to synchronized list
+        this.immutableOutboundHandshakedPeers = List.copyOf(this.outboundHandshakedPeers); // also thread safe thanks to synchronized collection's toArray() being fed to List.of(array)
+    }
+
+    public void removeOutboundHandshakedPeer(Peer peer) {
+        if (!peer.isOutbound()) {
+            return;
+        }
+        this.outboundHandshakedPeers.remove(peer); // thread safe thanks to synchronized list
+        this.immutableOutboundHandshakedPeers = List.copyOf(this.outboundHandshakedPeers); // also thread safe thanks to synchronized collection's toArray() being fed to List.of(array)
     }
 
     /**
      * Returns first peer that has completed handshaking and has matching public key.
      */
     public Peer getHandshakedPeerWithPublicKey(byte[] publicKey) {
-        synchronized (this.connectedPeers) {
-            return this.connectedPeers.stream()
-                    .filter(peer -> peer.getHandshakeStatus() == Handshake.COMPLETED
-                            && Arrays.equals(peer.getPeersPublicKey(), publicKey))
-                    .findFirst().orElse(null);
-        }
+        return this.getImmutableConnectedPeers().stream()
+                .filter(peer -> peer.getHandshakeStatus() == Handshake.COMPLETED
+                        && Arrays.equals(peer.getPeersPublicKey(), publicKey))
+                .findFirst().orElse(null);
     }
 
     // Peer list filters
@@ -354,21 +422,15 @@ public class Network {
         return this.selfPeers.stream().anyMatch(selfPeer -> selfPeer.equals(peerAddress));
     };
 
-    /**
-     * Must be inside <tt>synchronized (this.connectedPeers) {...}</tt>
-     */
     private final Predicate<PeerData> isConnectedPeer = peerData -> {
         PeerAddress peerAddress = peerData.getAddress();
-        return this.connectedPeers.stream().anyMatch(peer -> peer.getPeerData().getAddress().equals(peerAddress));
+        return this.getImmutableConnectedPeers().stream().anyMatch(peer -> peer.getPeerData().getAddress().equals(peerAddress));
     };
 
-    /**
-     * Must be inside <tt>synchronized (this.connectedPeers) {...}</tt>
-     */
     private final Predicate<PeerData> isResolvedAsConnectedPeer = peerData -> {
         try {
             InetSocketAddress resolvedSocketAddress = peerData.getAddress().toSocketAddress();
-            return this.connectedPeers.stream()
+            return this.getImmutableConnectedPeers().stream()
                     .anyMatch(peer -> peer.getResolvedAddress().equals(resolvedSocketAddress));
         } catch (UnknownHostException e) {
             // Can't resolve - no point even trying to connect
@@ -393,6 +455,11 @@ public class Network {
 
     class NetworkProcessor extends ExecuteProduceConsume {
 
+        private final AtomicLong nextConnectTaskTimestamp = new AtomicLong(0L); // ms - try first connect once NTP syncs
+        private final AtomicLong nextBroadcastTimestamp = new AtomicLong(0L); // ms - try first broadcast once NTP syncs
+
+        private Iterator<SelectionKey> channelIterator = null;
+
         NetworkProcessor(ExecutorService executor) {
             super(executor);
         }
@@ -434,51 +501,31 @@ public class Network {
         }
 
         private Task maybeProducePeerMessageTask() {
-            for (Peer peer : getConnectedPeers()) {
-                Task peerTask = peer.getMessageTask();
-                if (peerTask != null) {
-                    return peerTask;
-                }
-            }
-
-            return null;
+            return getImmutableConnectedPeers().stream()
+                    .map(Peer::getMessageTask)
+                    .filter(Objects::nonNull)
+                    .findFirst()
+                    .orElse(null);
         }
 
         private Task maybeProducePeerPingTask(Long now) {
-            // Ask connected peers whether they need a ping
-            for (Peer peer : getHandshakedPeers()) {
-                Task peerTask = peer.getPingTask(now);
-                if (peerTask != null) {
-                    return peerTask;
-                }
-            }
-
-            return null;
-        }
-
-        class PeerConnectTask implements ExecuteProduceConsume.Task {
-            private final Peer peer;
-
-            PeerConnectTask(Peer peer) {
-                this.peer = peer;
-            }
-
-            @Override
-            public void perform() throws InterruptedException {
-                connectPeer(peer);
-            }
+            return getImmutableHandshakedPeers().stream()
+                    .map(peer -> peer.getPingTask(now))
+                    .filter(Objects::nonNull)
+                    .findFirst()
+                    .orElse(null);
         }
 
         private Task maybeProduceConnectPeerTask(Long now) throws InterruptedException {
-            if (now == null || now < nextConnectTaskTimestamp) {
+            if (now == null || now < nextConnectTaskTimestamp.get()) {
                 return null;
             }
 
-            if (getOutboundHandshakedPeers().size() >= minOutboundPeers) {
+            if (getImmutableOutboundHandshakedPeers().size() >= minOutboundPeers) {
                 return null;
             }
 
-            nextConnectTaskTimestamp = now + 1000L;
+            nextConnectTaskTimestamp.set(now + 1000L);
 
             Peer targetPeer = getConnectablePeer(now);
             if (targetPeer == null) {
@@ -490,66 +537,15 @@ public class Network {
         }
 
         private Task maybeProduceBroadcastTask(Long now) {
-            if (now == null || now < nextBroadcastTimestamp) {
+            if (now == null || now < nextBroadcastTimestamp.get()) {
                 return null;
             }
 
-            nextBroadcastTimestamp = now + BROADCAST_INTERVAL;
-            return () -> Controller.getInstance().doNetworkBroadcast();
-        }
-
-        class ChannelTask implements ExecuteProduceConsume.Task {
-            private final SelectionKey selectionKey;
-
-            ChannelTask(SelectionKey selectionKey) {
-                this.selectionKey = selectionKey;
-            }
-
-            @Override
-            public void perform() throws InterruptedException {
-                try {
-                    LOGGER.trace("Thread {} has pending channel: {}, with ops {}",
-                            Thread.currentThread().getId(), selectionKey.channel(), selectionKey.readyOps());
-
-                    // process pending channel task
-                    if (selectionKey.isReadable()) {
-                        connectionRead((SocketChannel) selectionKey.channel());
-                    } else if (selectionKey.isAcceptable()) {
-                        acceptConnection((ServerSocketChannel) selectionKey.channel());
-                    }
-
-                    LOGGER.trace("Thread {} processed channel: {}",
-                            Thread.currentThread().getId(), selectionKey.channel());
-                } catch (CancelledKeyException e) {
-                    LOGGER.trace("Thread {} encountered cancelled channel: {}",
-                            Thread.currentThread().getId(), selectionKey.channel());
-                }
-            }
-
-            private void connectionRead(SocketChannel socketChannel) {
-                Peer peer = getPeerFromChannel(socketChannel);
-                if (peer == null) {
-                    return;
-                }
-
-                try {
-                    peer.readChannel();
-                } catch (IOException e) {
-                    if (e.getMessage() != null && e.getMessage().toLowerCase().contains("connection reset")) {
-                        peer.disconnect("Connection reset");
-                        return;
-                    }
-
-                    LOGGER.trace("[{}] Network thread {} encountered I/O error: {}", peer.getPeerConnectionId(),
-                            Thread.currentThread().getId(), e.getMessage(), e);
-                    peer.disconnect("I/O error");
-                }
-            }
+            nextBroadcastTimestamp.set(now + BROADCAST_INTERVAL);
+            return new BroadcastTask();
         }
 
         private Task maybeProduceChannelTask(boolean canBlock) throws InterruptedException {
-            final SelectionKey nextSelectionKey;
-
             // Synchronization here to enforce thread-safety on channelIterator
             synchronized (channelSelector) {
                 // anything to do?
@@ -570,92 +566,73 @@ public class Network {
                     }
 
                     channelIterator = channelSelector.selectedKeys().iterator();
+                    LOGGER.trace("Thread {}, after {} select, channelIterator now {}",
+                            Thread.currentThread().getId(),
+                            canBlock ? "blocking": "non-blocking",
+                            channelIterator);
                 }
 
-                if (channelIterator.hasNext()) {
-                    nextSelectionKey = channelIterator.next();
-                    channelIterator.remove();
-                } else {
-                    nextSelectionKey = null;
+                if (!channelIterator.hasNext()) {
                     channelIterator = null; // Nothing to do so reset iterator to cause new select
+
+                    LOGGER.trace("Thread {}, channelIterator now null", Thread.currentThread().getId());
+                    return null;
                 }
 
-                LOGGER.trace("Thread {}, nextSelectionKey {}, channelIterator now {}",
-                        Thread.currentThread().getId(), nextSelectionKey, channelIterator);
-            }
+                final SelectionKey nextSelectionKey = channelIterator.next();
+                channelIterator.remove();
 
-            if (nextSelectionKey == null) {
-                return null;
-            }
+                // Just in case underlying socket channel already closed elsewhere, etc.
+                if (!nextSelectionKey.isValid())
+                    return null;
 
-            return new ChannelTask(nextSelectionKey);
-        }
-    }
+                LOGGER.trace("Thread {}, nextSelectionKey {}", Thread.currentThread().getId(), nextSelectionKey);
 
-    private void acceptConnection(ServerSocketChannel serverSocketChannel) throws InterruptedException {
-        SocketChannel socketChannel;
+                SelectableChannel socketChannel = nextSelectionKey.channel();
 
-        try {
-            socketChannel = serverSocketChannel.accept();
-        } catch (IOException e) {
-            return;
-        }
-
-        // No connection actually accepted?
-        if (socketChannel == null) {
-            return;
-        }
-        PeerAddress address = PeerAddress.fromSocket(socketChannel.socket());
-        List<String> fixedNetwork = Settings.getInstance().getFixedNetwork();
-        if (fixedNetwork != null && !fixedNetwork.isEmpty() && ipNotInFixedList(address, fixedNetwork)) {
-            try {
-                LOGGER.debug("Connection discarded from peer {} as not in the fixed network list", address);
-                socketChannel.close();
-            } catch (IOException e) {
-                // IGNORE
-            }
-            return;
-        }
-
-        final Long now = NTP.getTime();
-        Peer newPeer;
-
-        try {
-            if (now == null) {
-                LOGGER.debug("Connection discarded from peer {} due to lack of NTP sync", address);
-                socketChannel.close();
-                return;
-            }
-
-            synchronized (this.connectedPeers) {
-                if (connectedPeers.size() >= maxPeers) {
-                    // We have enough peers
-                    LOGGER.debug("Connection discarded from peer {} because the server is full", address);
-                    socketChannel.close();
-                    return;
-                }
-
-                LOGGER.debug("Connection accepted from peer {}", address);
-
-                newPeer = new Peer(socketChannel, channelSelector);
-                this.connectedPeers.add(newPeer);
-            }
-        } catch (IOException e) {
-            if (socketChannel.isOpen()) {
                 try {
-                    LOGGER.debug("Connection failed from peer {} while connecting/closing", address);
-                    socketChannel.close();
-                } catch (IOException ce) {
-                    // Couldn't close?
+                    if (nextSelectionKey.isReadable()) {
+                        clearInterestOps(nextSelectionKey, SelectionKey.OP_READ);
+                        Peer peer = getPeerFromChannel((SocketChannel) socketChannel);
+                        if (peer == null)
+                            return null;
+
+                        return new ChannelReadTask((SocketChannel) socketChannel, peer);
+                    }
+
+                    if (nextSelectionKey.isWritable()) {
+                        clearInterestOps(nextSelectionKey, SelectionKey.OP_WRITE);
+                        Peer peer = getPeerFromChannel((SocketChannel) socketChannel);
+                        if (peer == null)
+                            return null;
+
+                        // Any thread that queues a message to send can set OP_WRITE,
+                        // but we only allow one pending/active ChannelWriteTask per Peer
+                        if (!channelsPendingWrite.add(socketChannel))
+                            return null;
+
+                        return new ChannelWriteTask((SocketChannel) socketChannel, peer);
+                    }
+
+                    if (nextSelectionKey.isAcceptable()) {
+                        clearInterestOps(nextSelectionKey, SelectionKey.OP_ACCEPT);
+                        return new ChannelAcceptTask((ServerSocketChannel) socketChannel);
+                    }
+                } catch (CancelledKeyException e) {
+                    /*
+                     * Sometimes nextSelectionKey is cancelled / becomes invalid between the isValid() test at line 586
+                     * and later calls to isReadable() / isWritable() / isAcceptable() which themselves call isValid()!
+                     * Those isXXXable() calls could throw CancelledKeyException, so we catch it here and return null.
+                     */
+                    return null;
                 }
             }
-            return;
-        }
 
-        this.onPeerReady(newPeer);
+            return null;
+        }
     }
 
-    private boolean ipNotInFixedList(PeerAddress address, List<String> fixedNetwork) {
+    public boolean ipNotInFixedList(PeerAddress address, List<String> fixedNetwork) {
         for (String ipAddress : fixedNetwork) {
             String[] bits = ipAddress.split(":");
             if (bits.length >= 1 && bits.length <= 2 && address.getHost().equals(bits[0])) {
@@ -687,16 +664,15 @@ public class Network {
                 peers.removeIf(isSelfPeer);
             }
 
-            synchronized (this.connectedPeers) {
-                // Don't consider already connected peers (simple address match)
-                peers.removeIf(isConnectedPeer);
+            // Don't consider already connected peers (simple address match)
+            peers.removeIf(isConnectedPeer);
 
-                // Don't consider already connected peers (resolved address match)
-                // XXX This might be too slow if we end up waiting a long time for hostnames to resolve via DNS
-                peers.removeIf(isResolvedAsConnectedPeer);
+            // Don't consider already connected peers (resolved address match)
+            // Disabled because this might be too slow if we end up waiting a long time for hostnames to resolve via DNS
+            // Which is ok because duplicate connections to the same peer are handled during handshaking
+            // peers.removeIf(isResolvedAsConnectedPeer);
 
-                this.checkLongestConnection(now);
-            }
+            this.checkLongestConnection(now);
 
             // Any left?
             if (peers.isEmpty()) {
@@ -724,8 +700,12 @@ public class Network {
         }
     }
 
-    private boolean connectPeer(Peer newPeer) throws InterruptedException {
-        SocketChannel socketChannel = newPeer.connect(this.channelSelector);
+    public boolean connectPeer(Peer newPeer) throws InterruptedException {
+        // Also checked before creating PeerConnectTask
+        if (getImmutableOutboundHandshakedPeers().size() >= minOutboundPeers)
+            return false;
+
+        SocketChannel socketChannel = newPeer.connect();
         if (socketChannel == null) {
             return false;
         }
@@ -734,21 +714,16 @@ public class Network {
             return false;
         }
 
-        synchronized (this.connectedPeers) {
-            this.connectedPeers.add(newPeer);
-        }
-
+        this.addConnectedPeer(newPeer);
         this.onPeerReady(newPeer);
 
         return true;
     }
 
-    private Peer getPeerFromChannel(SocketChannel socketChannel) {
-        synchronized (this.connectedPeers) {
-            for (Peer peer : this.connectedPeers) {
-                if (peer.getSocketChannel() == socketChannel) {
-                    return peer;
-                }
+    public Peer getPeerFromChannel(SocketChannel socketChannel) {
+        for (Peer peer : this.getImmutableConnectedPeers()) {
+            if (peer.getSocketChannel() == socketChannel) {
+                return peer;
             }
         }
 
@@ -761,7 +736,7 @@ public class Network {
         }
 
         // Find peers that have reached their maximum connection age, and disconnect them
-        List<Peer> peersToDisconnect = this.connectedPeers.stream()
+        List<Peer> peersToDisconnect = this.getImmutableConnectedPeers().stream()
                 .filter(peer -> !peer.isSyncInProgress())
                 .filter(peer -> peer.hasReachedMaxConnectionAge())
                 .collect(Collectors.toList());
@@ -778,7 +753,74 @@ public class Network {
         nextDisconnectionCheck = now + DISCONNECTION_CHECK_INTERVAL;
     }
 
-    // Peer callbacks
+    // SocketChannel interest-ops manipulations
+
+    private static final String[] OP_NAMES = new String[SelectionKey.OP_ACCEPT * 2];
+    static {
+        for (int i = 0; i < OP_NAMES.length; i++) {
+            StringJoiner joiner = new StringJoiner(",");
+
+            if ((i & SelectionKey.OP_READ) != 0) joiner.add("OP_READ");
+            if ((i & SelectionKey.OP_WRITE) != 0) joiner.add("OP_WRITE");
+            if ((i & SelectionKey.OP_CONNECT) != 0) joiner.add("OP_CONNECT");
+            if ((i & SelectionKey.OP_ACCEPT) != 0) joiner.add("OP_ACCEPT");
+
+            OP_NAMES[i] = joiner.toString();
+        }
+    }
+
+    public void clearInterestOps(SelectableChannel socketChannel, int interestOps) {
+        SelectionKey selectionKey = socketChannel.keyFor(channelSelector);
+        if (selectionKey == null)
+            return;
+
+        clearInterestOps(selectionKey, interestOps);
+    }
+
+    private void clearInterestOps(SelectionKey selectionKey, int interestOps) {
+        if (!selectionKey.channel().isOpen())
+            return;
+
+        LOGGER.trace("Thread {} clearing {} interest-ops on channel: {}",
+                Thread.currentThread().getId(),
+                OP_NAMES[interestOps],
+                selectionKey.channel());
+
+        selectionKey.interestOpsAnd(~interestOps);
+    }
+
+    public void setInterestOps(SelectableChannel socketChannel, int interestOps) {
+        SelectionKey selectionKey = socketChannel.keyFor(channelSelector);
+        if (selectionKey == null) {
+            try {
+                selectionKey = socketChannel.register(this.channelSelector, interestOps);
+            } catch (ClosedChannelException e) {
+                // Channel already closed so ignore
+                return;
+            }
+            // Fall-through to allow logging
+        }
+
+        setInterestOps(selectionKey, interestOps);
+    }
+
+    private void setInterestOps(SelectionKey selectionKey, int interestOps) {
+        if (!selectionKey.channel().isOpen())
+            return;
+
+        LOGGER.trace("Thread {} setting {} interest-ops on channel: {}",
+                Thread.currentThread().getId(),
+                OP_NAMES[interestOps],
+                selectionKey.channel());
+
+        selectionKey.interestOpsOr(interestOps);
+    }
+
+    // Peer / Task callbacks
+
+    public void notifyChannelNotWriting(SelectableChannel socketChannel) {
+        this.channelsPendingWrite.remove(socketChannel);
+    }
 
     protected void wakeupChannelSelector() {
         this.channelSelector.wakeup();
@@ -804,17 +846,32 @@ public class Network {
     }
 
     public void onDisconnect(Peer peer) {
-        // Notify Controller
-        Controller.getInstance().onPeerDisconnect(peer);
         if (peer.getConnectionEstablishedTime() > 0L) {
             LOGGER.debug("[{}] Disconnected from peer {}", peer.getPeerConnectionId(), peer);
         } else {
             LOGGER.debug("[{}] Failed to connect to peer {}", peer.getPeerConnectionId(), peer);
         }
 
-        synchronized (this.connectedPeers) {
-            this.connectedPeers.remove(peer);
+        this.removeConnectedPeer(peer);
+        this.channelsPendingWrite.remove(peer.getSocketChannel());
+
+        if (this.isShuttingDown)
+            // No need to do any further processing, like re-enabling listen socket or notifying Controller
+            return;
+
+        if (getImmutableConnectedPeers().size() < maxPeers - 1
+                && serverSelectionKey.isValid()
+                && (serverSelectionKey.interestOps() & SelectionKey.OP_ACCEPT) == 0) {
+            try {
+                LOGGER.debug("Re-enabling accepting incoming connections because the server is not longer full");
+                setInterestOps(serverSelectionKey, SelectionKey.OP_ACCEPT);
+            } catch (CancelledKeyException e) {
+                LOGGER.error("Failed to re-enable accepting of incoming connections: {}", e.getMessage());
+            }
         }
+
+        // Notify Controller
+        Controller.getInstance().onPeerDisconnect(peer);
     }
 
     public void peerMisbehaved(Peer peer) {
@@ -975,6 +1032,9 @@ public class Network {
             return;
         }
 
+        // Add to handshaked peers cache
+        this.addHandshakedPeer(peer);
+
         // Make a note that we've successfully completed handshake (and when)
         peer.getPeerData().setLastConnected(NTP.getTime());
 
@@ -1114,6 +1174,7 @@ public class Network {
             return;
         }
         String host = parts[0];
+        
         try {
             InetAddress addr = InetAddress.getByName(host);
             if (addr.isAnyLocalAddress() || addr.isSiteLocalAddress()) {
@@ -1124,6 +1185,9 @@ public class Network {
             return;
         }
 
+        // Keep track of the port
+        this.ourExternalPort = Integer.parseInt(parts[1]);
+
         // Add to the list
         this.ourExternalIpAddressHistory.add(host);
 
@@ -1177,8 +1241,19 @@ public class Network {
 
     public void onExternalIpUpdate(String ipAddress) {
         LOGGER.info("External IP address updated to {}", ipAddress);
+    }
 
-        ArbitraryDataManager.getInstance().broadcastHostedSignatureList();
+    public String getOurExternalIpAddress() {
+        // FUTURE: replace port if UPnP is active, as it will be more accurate
+        return this.ourExternalIpAddress;
+    }
+
+    public String getOurExternalIpAddressAndPort() {
+        String ipAddress = this.getOurExternalIpAddress();
+        if (ipAddress == null) {
+            return null;
+        }
+        return String.format("%s:%d", ipAddress, this.ourExternalPort);
     }
 
 
@@ -1222,7 +1297,7 @@ public class Network {
             }
         }
 
-        for (Peer peer : this.getConnectedPeers()) {
+        for (Peer peer : this.getImmutableConnectedPeers()) {
             peer.disconnect("to be forgotten");
         }
 
@@ -1234,8 +1309,9 @@ public class Network {
         try {
             InetSocketAddress knownAddress = peerAddress.toSocketAddress();
 
-            List<Peer> peers = this.getConnectedPeers();
-            peers.removeIf(peer -> !Peer.addressEquals(knownAddress, peer.getResolvedAddress()));
+            List<Peer> peers = this.getImmutableConnectedPeers().stream()
+                    .filter(peer -> Peer.addressEquals(knownAddress, peer.getResolvedAddress()))
+                    .collect(Collectors.toList());
 
             for (Peer peer : peers) {
                 peer.disconnect("to be forgotten");
@@ -1254,7 +1330,8 @@ public class Network {
         }
 
         // Disconnect peers that are stuck during handshake
-        List<Peer> handshakePeers = this.getConnectedPeers();
+        // Needs a mutable copy of the unmodifiableList
+        List<Peer> handshakePeers = new ArrayList<>(this.getImmutableConnectedPeers());
 
         // Disregard peers that have completed handshake or only connected recently
         handshakePeers.removeIf(peer -> peer.getHandshakeStatus() == Handshake.COMPLETED
@@ -1296,9 +1373,7 @@ public class Network {
                 peers.removeIf(isNotOldPeer);
 
                 // Don't consider already connected peers (simple address match)
-                synchronized (this.connectedPeers) {
-                    peers.removeIf(isConnectedPeer);
-                }
+                peers.removeIf(isConnectedPeer);
 
                 for (PeerData peerData : peers) {
                     LOGGER.debug("Deleting old peer {} from repository", peerData.getAddress().toString());
@@ -1394,54 +1469,27 @@ public class Network {
     }
 
     public void broadcast(Function<Peer, Message> peerMessageBuilder) {
-        class Broadcaster implements Runnable {
-            private final Random random = new Random();
+        for (Peer peer : getImmutableHandshakedPeers()) {
+            if (this.isShuttingDown)
+                return;
 
-            private List<Peer> targetPeers;
-            private Function<Peer, Message> peerMessageBuilder;
+            Message message = peerMessageBuilder.apply(peer);
 
-            Broadcaster(List<Peer> targetPeers, Function<Peer, Message> peerMessageBuilder) {
-                this.targetPeers = targetPeers;
-                this.peerMessageBuilder = peerMessageBuilder;
+            if (message == null) {
+                continue;
             }
 
-            @Override
-            public void run() {
-                Thread.currentThread().setName("Network Broadcast");
-
-                for (Peer peer : targetPeers) {
-                    // Very short sleep to reduce strain, improve multi-threading and catch interrupts
-                    try {
-                        Thread.sleep(random.nextInt(20) + 20L);
-                    } catch (InterruptedException e) {
-                        break;
-                    }
-
-                    Message message = peerMessageBuilder.apply(peer);
-
-                    if (message == null) {
-                        continue;
-                    }
-
-                    if (!peer.sendMessage(message)) {
-                        peer.disconnect("failed to broadcast message");
-                    }
-                }
-
-                Thread.currentThread().setName("Network Broadcast (dormant)");
+            if (!peer.sendMessage(message)) {
+                peer.disconnect("failed to broadcast message");
             }
         }
-
-        try {
-            broadcastExecutor.execute(new Broadcaster(this.getHandshakedPeers(), peerMessageBuilder));
-        } catch (RejectedExecutionException e) {
-            // Can't execute - probably because we're shutting down, so ignore
-        }
     }
 
     // Shutdown
 
     public void shutdown() {
+        this.isShuttingDown = true;
+
         // Close listen socket to prevent more incoming connections
         if (this.serverChannel.isOpen()) {
             try {
@@ -1460,18 +1508,8 @@ public class Network {
             LOGGER.warn("Interrupted while waiting for networking threads to terminate");
         }
 
-        // Stop broadcasts
-        this.broadcastExecutor.shutdownNow();
-        try {
-            if (!this.broadcastExecutor.awaitTermination(1000, TimeUnit.MILLISECONDS)) {
-                LOGGER.warn("Broadcast threads failed to terminate");
-            }
-        } catch (InterruptedException e) {
-            LOGGER.warn("Interrupted while waiting for broadcast threads failed to terminate");
-        }
-
         // Close all peer connections
-        for (Peer peer : this.getConnectedPeers()) {
+        for (Peer peer : this.getImmutableConnectedPeers()) {
             peer.shutdown();
         }
     }

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

@@ -11,25 +11,21 @@ import org.qortal.data.network.PeerChainTipData;
 import org.qortal.data.network.PeerData;
 import org.qortal.network.message.ChallengeMessage;
 import org.qortal.network.message.Message;
-import org.qortal.network.message.Message.MessageException;
-import org.qortal.network.message.Message.MessageType;
-import org.qortal.network.message.PingMessage;
+import org.qortal.network.message.MessageException;
+import org.qortal.network.task.MessageTask;
+import org.qortal.network.task.PingTask;
 import org.qortal.settings.Settings;
-import org.qortal.utils.ExecuteProduceConsume;
+import org.qortal.utils.ExecuteProduceConsume.Task;
 import org.qortal.utils.NTP;
 
 import java.io.IOException;
 import java.net.*;
 import java.nio.ByteBuffer;
 import java.nio.channels.SelectionKey;
-import java.nio.channels.Selector;
 import java.nio.channels.SocketChannel;
 import java.security.SecureRandom;
 import java.util.*;
-import java.util.concurrent.ArrayBlockingQueue;
-import java.util.concurrent.BlockingQueue;
-import java.util.concurrent.LinkedBlockingQueue;
-import java.util.concurrent.TimeUnit;
+import java.util.concurrent.*;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -48,9 +44,9 @@ public class Peer {
     private static final int RESPONSE_TIMEOUT = 3000; // ms
 
     /**
-     * Maximum time to wait for a peer to respond with blocks (ms)
+     * Maximum time to wait for a message to be added to sendQueue (ms)
      */
-    public static final int FETCH_BLOCKS_TIMEOUT = 10000;
+    private static final int QUEUE_TIMEOUT = 1000; // ms
 
     /**
      * Interval between PING messages to a peer. (ms)
@@ -71,10 +67,14 @@ public class Peer {
     private final UUID peerConnectionId = UUID.randomUUID();
     private final Object byteBufferLock = new Object();
     private ByteBuffer byteBuffer;
-
     private Map<Integer, BlockingQueue<Message>> replyQueues;
     private LinkedBlockingQueue<Message> pendingMessages;
 
+    private TransferQueue<Message> sendQueue;
+    private ByteBuffer outputBuffer;
+    private String outputMessageType;
+    private int outputMessageId;
+
     /**
      * True if we created connection to peer, false if we accepted incoming connection from peer.
      */
@@ -98,7 +98,7 @@ public class Peer {
     /**
      * When last PING message was sent, or null if pings not started yet.
      */
-    private Long lastPingSent;
+    private Long lastPingSent = null;
 
     byte[] ourChallenge;
 
@@ -160,10 +160,10 @@ public class Peer {
     /**
      * Construct Peer using existing, connected socket
      */
-    public Peer(SocketChannel socketChannel, Selector channelSelector) throws IOException {
+    public Peer(SocketChannel socketChannel) throws IOException {
         this.isOutbound = false;
         this.socketChannel = socketChannel;
-        sharedSetup(channelSelector);
+        sharedSetup();
 
         this.resolvedAddress = ((InetSocketAddress) socketChannel.socket().getRemoteSocketAddress());
         this.isLocal = isAddressLocal(this.resolvedAddress.getAddress());
@@ -276,7 +276,7 @@ public class Peer {
         }
     }
 
-    protected void setLastPing(long lastPing) {
+    public void setLastPing(long lastPing) {
         synchronized (this.peerInfoLock) {
             this.lastPing = lastPing;
         }
@@ -346,12 +346,6 @@ public class Peer {
         }
     }
 
-    protected void queueMessage(Message message) {
-        if (!this.pendingMessages.offer(message)) {
-            LOGGER.info("[{}] No room to queue message from peer {} - discarding", this.peerConnectionId, this);
-        }
-    }
-
     public boolean isSyncInProgress() {
         return this.syncInProgress;
     }
@@ -396,13 +390,14 @@ public class Peer {
 
     // Processing
 
-    private void sharedSetup(Selector channelSelector) throws IOException {
+    private void sharedSetup() throws IOException {
         this.connectionTimestamp = NTP.getTime();
         this.socketChannel.setOption(StandardSocketOptions.TCP_NODELAY, true);
         this.socketChannel.configureBlocking(false);
-        this.socketChannel.register(channelSelector, SelectionKey.OP_READ);
+        Network.getInstance().setInterestOps(this.socketChannel, SelectionKey.OP_READ);
         this.byteBuffer = null; // Defer allocation to when we need it, to save memory. Sorry GC!
-        this.replyQueues = Collections.synchronizedMap(new HashMap<Integer, BlockingQueue<Message>>());
+        this.sendQueue = new LinkedTransferQueue<>();
+        this.replyQueues = new ConcurrentHashMap<>();
         this.pendingMessages = new LinkedBlockingQueue<>();
 
         Random random = new SecureRandom();
@@ -410,7 +405,7 @@ public class Peer {
         random.nextBytes(this.ourChallenge);
     }
 
-    public SocketChannel connect(Selector channelSelector) {
+    public SocketChannel connect() {
         LOGGER.trace("[{}] Connecting to peer {}", this.peerConnectionId, this);
 
         try {
@@ -418,6 +413,8 @@ public class Peer {
             this.isLocal = isAddressLocal(this.resolvedAddress.getAddress());
 
             this.socketChannel = SocketChannel.open();
+            InetAddress bindAddr = InetAddress.getByName(Settings.getInstance().getBindAddress());
+            this.socketChannel.socket().bind(new InetSocketAddress(bindAddr, 0));
             this.socketChannel.socket().connect(resolvedAddress, CONNECT_TIMEOUT);
         } catch (SocketTimeoutException e) {
             LOGGER.trace("[{}] Connection timed out to peer {}", this.peerConnectionId, this);
@@ -432,7 +429,7 @@ public class Peer {
 
         try {
             LOGGER.debug("[{}] Connected to peer {}", this.peerConnectionId, this);
-            sharedSetup(channelSelector);
+            sharedSetup();
             return socketChannel;
         } catch (IOException e) {
             LOGGER.trace("[{}] Post-connection setup failed, peer {}", this.peerConnectionId, this);
@@ -450,7 +447,7 @@ public class Peer {
      *
      * @throws IOException If this channel is not yet connected
      */
-    protected void readChannel() throws IOException {
+    public void readChannel() throws IOException {
         synchronized (this.byteBufferLock) {
             while (true) {
                 if (!this.socketChannel.isOpen() || this.socketChannel.socket().isClosed()) {
@@ -556,7 +553,67 @@ public class Peer {
         }
     }
 
-    protected ExecuteProduceConsume.Task getMessageTask() {
+    /** Maybe send some pending outgoing messages.
+     *
+     * @return true if more data is pending to be sent
+     */
+    public boolean writeChannel() throws IOException {
+        // It is the responsibility of ChannelWriteTask's producer to produce only one call to writeChannel() at a time
+
+        while (true) {
+            // If output byte buffer is null, fetch next message from queue (if any)
+            while (this.outputBuffer == null) {
+                Message message;
+
+                try {
+                    // Allow other thread time to add message to queue having raised OP_WRITE.
+                    // Timeout is overkill but not excessive enough to clog up networking / EPC.
+                    // This is to avoid race condition in sendMessageWithTimeout() below.
+                    message = this.sendQueue.poll(QUEUE_TIMEOUT, TimeUnit.MILLISECONDS);
+                } catch (InterruptedException e) {
+                    // Shutdown situation
+                    return false;
+                }
+
+                // No message? No further work to be done
+                if (message == null)
+                    return false;
+
+                try {
+                    this.outputBuffer = ByteBuffer.wrap(message.toBytes());
+                    this.outputMessageType = message.getType().name();
+                    this.outputMessageId = message.getId();
+
+                    LOGGER.trace("[{}] Sending {} message with ID {} to peer {}",
+                            this.peerConnectionId, this.outputMessageType, this.outputMessageId, this);
+                } catch (MessageException e) {
+                    // Something went wrong converting message to bytes, so discard but allow another round
+                    LOGGER.warn("[{}] Failed to send {} message with ID {} to peer {}: {}", this.peerConnectionId,
+                            message.getType().name(), message.getId(), this, e.getMessage());
+                }
+            }
+
+            // If output byte buffer is not null, send from that
+            int bytesWritten = this.socketChannel.write(outputBuffer);
+
+            LOGGER.trace("[{}] Sent {} bytes of {} message with ID {} to peer {} ({} total)", this.peerConnectionId,
+                    bytesWritten, this.outputMessageType, this.outputMessageId, this, outputBuffer.limit());
+
+            // If we've sent 0 bytes then socket buffer is full so we need to wait until it's empty again
+            if (bytesWritten == 0) {
+                return true;
+            }
+
+            // If we then exhaust the byte buffer, set it to null (otherwise loop and try to send more)
+            if (!this.outputBuffer.hasRemaining()) {
+                this.outputMessageType = null;
+                this.outputMessageId = 0;
+                this.outputBuffer = null;
+            }
+        }
+    }
+
+    protected Task getMessageTask() {
         /*
          * If we are still handshaking and there is a message yet to be processed then
          * don't produce another message task. This allows us to process handshake
@@ -580,7 +637,7 @@ public class Peer {
         }
 
         // Return a task to process message in queue
-        return () -> Network.getInstance().onMessage(this, nextMessage);
+        return new MessageTask(this, nextMessage);
     }
 
     /**
@@ -605,54 +662,25 @@ public class Peer {
         }
 
         try {
-            // Send message
-            LOGGER.trace("[{}] Sending {} message with ID {} to peer {}", this.peerConnectionId,
+            // Queue message, to be picked up by ChannelWriteTask and then peer.writeChannel()
+            LOGGER.trace("[{}] Queuing {} message with ID {} to peer {}", this.peerConnectionId,
                     message.getType().name(), message.getId(), this);
 
-            ByteBuffer outputBuffer = ByteBuffer.wrap(message.toBytes());
+            // Check message properly constructed
+            message.checkValidOutgoing();
 
-            synchronized (this.socketChannel) {
-                final long sendStart = System.currentTimeMillis();
-                long totalBytes = 0;
-
-                while (outputBuffer.hasRemaining()) {
-                    int bytesWritten = this.socketChannel.write(outputBuffer);
-                    totalBytes += bytesWritten;
-
-                    LOGGER.trace("[{}] Sent {} bytes of {} message with ID {} to peer {} ({} total)", this.peerConnectionId,
-                            bytesWritten, message.getType().name(), message.getId(), this, totalBytes);
-
-                    if (bytesWritten == 0) {
-                        // Underlying socket's internal buffer probably full,
-                        // so wait a short while for bytes to actually be transmitted over the wire
-
-                        /*
-                         * NOSONAR squid:S2276 - we don't want to use this.socketChannel.wait()
-                         * as this releases the lock held by synchronized() above
-                         * and would allow another thread to send another message,
-                         * potentially interleaving them on-the-wire, causing checksum failures
-                         * and connection loss.
-                         */
-                        Thread.sleep(1L); //NOSONAR squid:S2276
-
-                        if (System.currentTimeMillis() - sendStart > timeout) {
-                            // We've taken too long to send this message
-                            return false;
-                        }
-                    }
-                }
-            }
-        } catch (MessageException e) {
-            LOGGER.warn("[{}] Failed to send {} message with ID {} to peer {}: {}", this.peerConnectionId,
-                    message.getType().name(), message.getId(), this, e.getMessage());
-            return false;
-        } catch (IOException | InterruptedException e) {
+            // Possible race condition:
+            // We set OP_WRITE, EPC creates ChannelWriteTask which calls Peer.writeChannel, writeChannel's poll() finds no message to send
+            // Avoided by poll-with-timeout in writeChannel() above.
+            Network.getInstance().setInterestOps(this.socketChannel, SelectionKey.OP_WRITE);
+            return this.sendQueue.tryTransfer(message, timeout, TimeUnit.MILLISECONDS);
+        } catch (InterruptedException e) {
             // Send failure
             return false;
+        } catch (MessageException e) {
+            LOGGER.error(e.getMessage(), e);
+            return false;
         }
-
-        // Sent OK
-        return true;
     }
 
     /**
@@ -720,7 +748,7 @@ public class Peer {
         this.lastPingSent = NTP.getTime();
     }
 
-    protected ExecuteProduceConsume.Task getPingTask(Long now) {
+    protected Task getPingTask(Long now) {
         // Pings not enabled yet?
         if (now == null || this.lastPingSent == null) {
             return null;
@@ -734,19 +762,7 @@ public class Peer {
         // Not strictly true, but prevents this peer from being immediately chosen again
         this.lastPingSent = now;
 
-        return () -> {
-            PingMessage pingMessage = new PingMessage();
-            Message message = this.getResponse(pingMessage);
-
-            if (message == null || message.getType() != MessageType.PING) {
-                LOGGER.debug("[{}] Didn't receive reply from {} for PING ID {}", this.peerConnectionId, this,
-                        pingMessage.getId());
-                this.disconnect("no ping received");
-                return;
-            }
-
-            this.setLastPing(NTP.getTime() - now);
-        };
+        return new PingTask(this, now);
     }
 
     public void disconnect(String reason) {

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

@@ -1,90 +1,136 @@
 package org.qortal.network.message;
 
 import com.google.common.primitives.Ints;
+import com.google.common.primitives.Longs;
+import org.qortal.data.network.PeerData;
 import org.qortal.transform.TransformationException;
 import org.qortal.transform.Transformer;
 import org.qortal.utils.Serialization;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.List;
 
 public class ArbitraryDataFileListMessage extends Message {
 
-	private static final int SIGNATURE_LENGTH = Transformer.SIGNATURE_LENGTH;
-	private static final int HASH_LENGTH = Transformer.SHA256_LENGTH;
+	private byte[] signature;
+	private List<byte[]> hashes;
+	private Long requestTime;
+	private Integer requestHops;
+	private String peerAddress;
+	private Boolean isRelayPossible;
 
-	private final byte[] signature;
-	private final List<byte[]> hashes;
-
-	public ArbitraryDataFileListMessage(byte[] signature, List<byte[]> hashes) {
+	public ArbitraryDataFileListMessage(byte[] signature, List<byte[]> hashes, Long requestTime,
+										Integer requestHops, String peerAddress, Boolean isRelayPossible) {
 		super(MessageType.ARBITRARY_DATA_FILE_LIST);
 
-		this.signature = signature;
-		this.hashes = hashes;
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			bytes.write(signature);
+
+			bytes.write(Ints.toByteArray(hashes.size()));
+
+			for (byte[] hash : hashes) {
+				bytes.write(hash);
+			}
+
+			if (requestTime != null) {
+				// The remaining fields are optional
+
+				bytes.write(Longs.toByteArray(requestTime));
+
+				bytes.write(Ints.toByteArray(requestHops));
+
+				Serialization.serializeSizedStringV2(bytes, peerAddress);
+
+				bytes.write(Ints.toByteArray(Boolean.TRUE.equals(isRelayPossible) ? 1 : 0));
+			}
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
 	}
 
-	public ArbitraryDataFileListMessage(int id, byte[] signature, List<byte[]> hashes) {
+	/** Legacy version */
+	public ArbitraryDataFileListMessage(byte[] signature, List<byte[]> hashes) {
+		this(signature, hashes, null, null, null, null);
+	}
+
+	private ArbitraryDataFileListMessage(int id, byte[] signature, List<byte[]> hashes, Long requestTime,
+										Integer requestHops, String peerAddress, boolean isRelayPossible) {
 		super(id, MessageType.ARBITRARY_DATA_FILE_LIST);
 
 		this.signature = signature;
 		this.hashes = hashes;
-	}
-
-	public List<byte[]> getHashes() {
-		return this.hashes;
+		this.requestTime = requestTime;
+		this.requestHops = requestHops;
+		this.peerAddress = peerAddress;
+		this.isRelayPossible = isRelayPossible;
 	}
 
 	public byte[] getSignature() {
 		return this.signature;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException, TransformationException {
-		byte[] signature = new byte[SIGNATURE_LENGTH];
+	public List<byte[]> getHashes() {
+		return this.hashes;
+	}
+
+	public Long getRequestTime() {
+		return this.requestTime;
+	}
+
+	public Integer getRequestHops() {
+		return this.requestHops;
+	}
+
+	public String getPeerAddress() {
+		return this.peerAddress;
+	}
+
+	public Boolean isRelayPossible() {
+		return this.isRelayPossible;
+	}
+
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws MessageException {
+		byte[] signature = new byte[Transformer.SIGNATURE_LENGTH];
 		bytes.get(signature);
 
 		int count = bytes.getInt();
 
-		if (bytes.remaining() != count * HASH_LENGTH)
-			return null;
-
 		List<byte[]> hashes = new ArrayList<>();
 		for (int i = 0; i < count; ++i) {
-
-			byte[] hash = new byte[HASH_LENGTH];
+			byte[] hash = new byte[Transformer.SHA256_LENGTH];
 			bytes.get(hash);
 			hashes.add(hash);
 		}
 
-		return new ArbitraryDataFileListMessage(id, signature, hashes);
-	}
+		Long requestTime = null;
+		Integer requestHops = null;
+		String peerAddress = null;
+		boolean isRelayPossible = true; // Legacy versions only send this message when relaying is possible
 
-	@Override
-	protected byte[] toData() {
-		try {
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+		// The remaining fields are optional
+		if (bytes.hasRemaining()) {
+			try {
+				requestTime = bytes.getLong();
 
-			bytes.write(this.signature);
+				requestHops = bytes.getInt();
 
-			bytes.write(Ints.toByteArray(this.hashes.size()));
+				peerAddress = Serialization.deserializeSizedStringV2(bytes, PeerData.MAX_PEER_ADDRESS_SIZE);
 
-			for (byte[] hash : this.hashes) {
-				bytes.write(hash);
+				isRelayPossible = bytes.getInt() > 0;
+			} catch (TransformationException e) {
+				throw new MessageException(e.getMessage(), e);
 			}
-
-			return bytes.toByteArray();
-		} catch (IOException e) {
-			return null;
 		}
-	}
 
-	public ArbitraryDataFileListMessage cloneWithNewId(int newId) {
-		ArbitraryDataFileListMessage clone = new ArbitraryDataFileListMessage(this.signature, this.hashes);
-		clone.setId(newId);
-		return clone;
+		return new ArbitraryDataFileListMessage(id, signature, hashes, requestTime, requestHops, peerAddress, isRelayPossible);
 	}
 
 }

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

@@ -1,48 +1,68 @@
 package org.qortal.network.message;
 
 import com.google.common.primitives.Ints;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 import org.qortal.arbitrary.ArbitraryDataFile;
 import org.qortal.repository.DataException;
 import org.qortal.transform.Transformer;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.UnsupportedEncodingException;
+import java.nio.BufferUnderflowException;
 import java.nio.ByteBuffer;
 
 public class ArbitraryDataFileMessage extends Message {
 
-	private static final int SIGNATURE_LENGTH = Transformer.SIGNATURE_LENGTH;
+	private static final Logger LOGGER = LogManager.getLogger(ArbitraryDataFileMessage.class);
 
-	private final byte[] signature;
-	private final ArbitraryDataFile arbitraryDataFile;
+	private byte[] signature;
+	private ArbitraryDataFile arbitraryDataFile;
 
 	public ArbitraryDataFileMessage(byte[] signature, ArbitraryDataFile arbitraryDataFile) {
 		super(MessageType.ARBITRARY_DATA_FILE);
 
-		this.signature = signature;
-		this.arbitraryDataFile = arbitraryDataFile;
+		byte[] data = arbitraryDataFile.getBytes();
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			bytes.write(signature);
+
+			bytes.write(Ints.toByteArray(data.length));
+
+			bytes.write(data);
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
 	}
 
-	public ArbitraryDataFileMessage(int id, byte[] signature, ArbitraryDataFile arbitraryDataFile) {
+	private ArbitraryDataFileMessage(int id, byte[] signature, ArbitraryDataFile arbitraryDataFile) {
 		super(id, MessageType.ARBITRARY_DATA_FILE);
 
 		this.signature = signature;
 		this.arbitraryDataFile = arbitraryDataFile;
 	}
 
+	public byte[] getSignature() {
+		return this.signature;
+	}
+
 	public ArbitraryDataFile getArbitraryDataFile() {
 		return this.arbitraryDataFile;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) throws UnsupportedEncodingException {
-		byte[] signature = new byte[SIGNATURE_LENGTH];
+	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) throws MessageException {
+		byte[] signature = new byte[Transformer.SIGNATURE_LENGTH];
 		byteBuffer.get(signature);
 
 		int dataLength = byteBuffer.getInt();
 
-		if (byteBuffer.remaining() != dataLength)
-			return null;
+		if (byteBuffer.remaining() < dataLength)
+			throw new BufferUnderflowException();
 
 		byte[] data = new byte[dataLength];
 		byteBuffer.get(data);
@@ -50,42 +70,10 @@ public class ArbitraryDataFileMessage extends Message {
 		try {
 			ArbitraryDataFile arbitraryDataFile = new ArbitraryDataFile(data, signature);
 			return new ArbitraryDataFileMessage(id, signature, arbitraryDataFile);
+		} catch (DataException e) {
+			LOGGER.info("Unable to process received file: {}", e.getMessage());
+			throw new MessageException("Unable to process received file: " + e.getMessage(), e);
 		}
-		catch (DataException e) {
-			return null;
-		}
-	}
-
-	@Override
-	protected byte[] toData() {
-		if (this.arbitraryDataFile == null) {
-			return null;
-		}
-
-		byte[] data = this.arbitraryDataFile.getBytes();
-		if (data == null) {
-			return null;
-		}
-
-		try {
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
-
-			bytes.write(signature);
-
-			bytes.write(Ints.toByteArray(data.length));
-
-			bytes.write(data);
-
-			return bytes.toByteArray();
-		} catch (IOException e) {
-			return null;
-		}
-	}
-
-	public ArbitraryDataFileMessage cloneWithNewId(int newId) {
-		ArbitraryDataFileMessage clone = new ArbitraryDataFileMessage(this.signature, this.arbitraryDataFile);
-		clone.setId(newId);
-		return clone;
 	}
 
 }

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

@@ -2,7 +2,7 @@ package org.qortal.network.message;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.UnsupportedEncodingException;
+import java.nio.BufferUnderflowException;
 import java.nio.ByteBuffer;
 
 import org.qortal.transform.Transformer;
@@ -11,13 +11,26 @@ import com.google.common.primitives.Ints;
 
 public class ArbitraryDataMessage extends Message {
 
-	private static final int SIGNATURE_LENGTH = Transformer.SIGNATURE_LENGTH;
-
 	private byte[] signature;
 	private byte[] data;
 
 	public ArbitraryDataMessage(byte[] signature, byte[] data) {
-		this(-1, signature, data);
+		super(MessageType.ARBITRARY_DATA);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			bytes.write(signature);
+
+			bytes.write(Ints.toByteArray(data.length));
+
+			bytes.write(data);
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
 	}
 
 	private ArbitraryDataMessage(int id, byte[] signature, byte[] data) {
@@ -35,14 +48,14 @@ public class ArbitraryDataMessage extends Message {
 		return this.data;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) throws UnsupportedEncodingException {
-		byte[] signature = new byte[SIGNATURE_LENGTH];
+	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) {
+		byte[] signature = new byte[Transformer.SIGNATURE_LENGTH];
 		byteBuffer.get(signature);
 
 		int dataLength = byteBuffer.getInt();
 
-		if (byteBuffer.remaining() != dataLength)
-			return null;
+		if (byteBuffer.remaining() < dataLength)
+			throw new BufferUnderflowException();
 
 		byte[] data = new byte[dataLength];
 		byteBuffer.get(data);
@@ -50,24 +63,4 @@ public class ArbitraryDataMessage extends Message {
 		return new ArbitraryDataMessage(id, signature, data);
 	}
 
-	@Override
-	protected byte[] toData() {
-		if (this.data == null)
-			return null;
-
-		try {
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
-
-			bytes.write(this.signature);
-
-			bytes.write(Ints.toByteArray(this.data.length));
-
-			bytes.write(this.data);
-
-			return bytes.toByteArray();
-		} catch (IOException e) {
-			return null;
-		}
-	}
-
 }

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

@@ -0,0 +1,74 @@
+package org.qortal.network.message;
+
+import com.google.common.primitives.Ints;
+import org.qortal.arbitrary.ArbitraryDataFile;
+import org.qortal.repository.DataException;
+import org.qortal.transform.Transformer;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.BufferUnderflowException;
+import java.nio.ByteBuffer;
+
+public class ArbitraryMetadataMessage extends Message {
+
+	private byte[] signature;
+	private ArbitraryDataFile arbitraryMetadataFile;
+
+	public ArbitraryMetadataMessage(byte[] signature, ArbitraryDataFile arbitraryMetadataFile) {
+		super(MessageType.ARBITRARY_METADATA);
+
+		byte[] data = arbitraryMetadataFile.getBytes();
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			bytes.write(signature);
+
+			bytes.write(Ints.toByteArray(data.length));
+
+			bytes.write(data);
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
+
+	private ArbitraryMetadataMessage(int id, byte[] signature, ArbitraryDataFile arbitraryMetadataFile) {
+		super(id, MessageType.ARBITRARY_METADATA);
+
+		this.signature = signature;
+		this.arbitraryMetadataFile = arbitraryMetadataFile;
+	}
+
+	public byte[] getSignature() {
+		return this.signature;
+	}
+
+	public ArbitraryDataFile getArbitraryMetadataFile() {
+		return this.arbitraryMetadataFile;
+	}
+
+	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) throws MessageException {
+		byte[] signature = new byte[Transformer.SIGNATURE_LENGTH];
+		byteBuffer.get(signature);
+
+		int dataLength = byteBuffer.getInt();
+
+		if (byteBuffer.remaining() < dataLength)
+			throw new BufferUnderflowException();
+
+		byte[] data = new byte[dataLength];
+		byteBuffer.get(data);
+
+		try {
+			ArbitraryDataFile arbitraryMetadataFile = new ArbitraryDataFile(data, signature);
+			return new ArbitraryMetadataMessage(id, signature, arbitraryMetadataFile);
+		} catch (DataException e) {
+			throw new MessageException("Unable to process arbitrary metadata message: " + e.getMessage(), e);
+		}
+	}
+
+}

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

@@ -8,21 +8,37 @@ import org.qortal.utils.Serialization;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.UnsupportedEncodingException;
+import java.nio.BufferUnderflowException;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.List;
 
 public class ArbitrarySignaturesMessage extends Message {
 
-	private static final int SIGNATURE_LENGTH = Transformer.SIGNATURE_LENGTH;
-
 	private String peerAddress;
 	private int requestHops;
 	private List<byte[]> signatures;
 
 	public ArbitrarySignaturesMessage(String peerAddress, int requestHops, List<byte[]> signatures) {
-		this(-1, peerAddress, requestHops, signatures);
+		super(MessageType.ARBITRARY_SIGNATURES);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			Serialization.serializeSizedStringV2(bytes, peerAddress);
+
+			bytes.write(Ints.toByteArray(requestHops));
+
+			bytes.write(Ints.toByteArray(signatures.size()));
+
+			for (byte[] signature : signatures)
+				bytes.write(signature);
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
 	}
 
 	private ArbitrarySignaturesMessage(int id, String peerAddress, int requestHops, List<byte[]> signatures) {
@@ -41,27 +57,24 @@ public class ArbitrarySignaturesMessage extends Message {
 		return this.signatures;
 	}
 
-	public int getRequestHops() {
-		return this.requestHops;
-	}
-
-	public void setRequestHops(int requestHops) {
-		this.requestHops = requestHops;
-	}
-
-	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException, TransformationException {
-		String peerAddress = Serialization.deserializeSizedStringV2(bytes, PeerData.MAX_PEER_ADDRESS_SIZE);
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws MessageException {
+		String peerAddress;
+		try {
+			peerAddress = Serialization.deserializeSizedStringV2(bytes, PeerData.MAX_PEER_ADDRESS_SIZE);
+		} catch (TransformationException e) {
+			throw new MessageException(e.getMessage(), e);
+		}
 
 		int requestHops = bytes.getInt();
 
 		int signatureCount = bytes.getInt();
 
-		if (bytes.remaining() != signatureCount * SIGNATURE_LENGTH)
-			return null;
+		if (bytes.remaining() < signatureCount * Transformer.SIGNATURE_LENGTH)
+			throw new BufferUnderflowException();
 
 		List<byte[]> signatures = new ArrayList<>();
 		for (int i = 0; i < signatureCount; ++i) {
-			byte[] signature = new byte[SIGNATURE_LENGTH];
+			byte[] signature = new byte[Transformer.SIGNATURE_LENGTH];
 			bytes.get(signature);
 			signatures.add(signature);
 		}
@@ -69,24 +82,4 @@ public class ArbitrarySignaturesMessage extends Message {
 		return new ArbitrarySignaturesMessage(id, peerAddress, requestHops, signatures);
 	}
 
-	@Override
-	protected byte[] toData() {
-		try {
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
-
-			Serialization.serializeSizedStringV2(bytes, this.peerAddress);
-
-			bytes.write(Ints.toByteArray(this.requestHops));
-
-			bytes.write(Ints.toByteArray(this.signatures.size()));
-
-			for (byte[] signature : this.signatures)
-				bytes.write(signature);
-
-			return bytes.toByteArray();
-		} catch (IOException e) {
-			return null;
-		}
-	}
-
 }

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

@@ -1,14 +1,10 @@
 package org.qortal.network.message;
 
-import java.io.ByteArrayOutputStream;
-import java.io.IOException;
-import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
 import java.util.List;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
-import org.qortal.block.Block;
 import org.qortal.data.at.ATStateData;
 import org.qortal.data.block.BlockData;
 import org.qortal.data.transaction.TransactionData;
@@ -16,27 +12,15 @@ import org.qortal.transform.TransformationException;
 import org.qortal.transform.block.BlockTransformer;
 import org.qortal.utils.Triple;
 
-import com.google.common.primitives.Ints;
-
 public class BlockMessage extends Message {
 
 	private static final Logger LOGGER = LogManager.getLogger(BlockMessage.class);
 
-	private Block block = null;
+	private final BlockData blockData;
+	private final List<TransactionData> transactions;
+	private final List<ATStateData> atStates;
 
-	private BlockData blockData = null;
-	private List<TransactionData> transactions = null;
-	private List<ATStateData> atStates = null;
-
-	private int height;
-
-	public BlockMessage(Block block) {
-		super(MessageType.BLOCK);
-
-		this.block = block;
-		this.blockData = block.getBlockData();
-		this.height = block.getBlockData().getHeight();
-	}
+	// No public constructor as we're an incoming-only message type.
 
 	private BlockMessage(int id, BlockData blockData, List<TransactionData> transactions, List<ATStateData> atStates) {
 		super(id, MessageType.BLOCK);
@@ -44,8 +28,6 @@ public class BlockMessage extends Message {
 		this.blockData = blockData;
 		this.transactions = transactions;
 		this.atStates = atStates;
-
-		this.height = blockData.getHeight();
 	}
 
 	public BlockData getBlockData() {
@@ -60,7 +42,7 @@ public class BlockMessage extends Message {
 		return this.atStates;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) throws UnsupportedEncodingException {
+	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) throws MessageException {
 		try {
 			int height = byteBuffer.getInt();
 
@@ -72,32 +54,8 @@ public class BlockMessage extends Message {
 			return new BlockMessage(id, blockData, blockInfo.getB(), blockInfo.getC());
 		} catch (TransformationException e) {
 			LOGGER.info(String.format("Received garbled BLOCK message: %s", e.getMessage()));
-			return null;
+			throw new MessageException(e.getMessage(), e);
 		}
 	}
 
-	@Override
-	protected byte[] toData() {
-		if (this.block == null)
-			return null;
-
-		try {
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
-
-			bytes.write(Ints.toByteArray(this.height));
-
-			bytes.write(BlockTransformer.toBytes(this.block));
-
-			return bytes.toByteArray();
-		} catch (TransformationException | IOException e) {
-			return null;
-		}
-	}
-
-	public BlockMessage cloneWithNewId(int newId) {
-		BlockMessage clone = new BlockMessage(this.block);
-		clone.setId(newId);
-		return clone;
-	}
-
 }

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

@@ -2,7 +2,7 @@ package org.qortal.network.message;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.UnsupportedEncodingException;
+import java.nio.BufferUnderflowException;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.List;
@@ -20,7 +20,25 @@ public class BlockSummariesMessage extends Message {
 	private List<BlockSummaryData> blockSummaries;
 
 	public BlockSummariesMessage(List<BlockSummaryData> blockSummaries) {
-		this(-1, blockSummaries);
+		super(MessageType.BLOCK_SUMMARIES);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			bytes.write(Ints.toByteArray(blockSummaries.size()));
+
+			for (BlockSummaryData blockSummary : blockSummaries) {
+				bytes.write(Ints.toByteArray(blockSummary.getHeight()));
+				bytes.write(blockSummary.getSignature());
+				bytes.write(blockSummary.getMinterPublicKey());
+				bytes.write(Ints.toByteArray(blockSummary.getOnlineAccountsCount()));
+			}
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
 	}
 
 	private BlockSummariesMessage(int id, List<BlockSummaryData> blockSummaries) {
@@ -33,11 +51,11 @@ public class BlockSummariesMessage extends Message {
 		return this.blockSummaries;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
 		int count = bytes.getInt();
 
-		if (bytes.remaining() != count * BLOCK_SUMMARY_LENGTH)
-			return null;
+		if (bytes.remaining() < count * BLOCK_SUMMARY_LENGTH)
+			throw new BufferUnderflowException();
 
 		List<BlockSummaryData> blockSummaries = new ArrayList<>();
 		for (int i = 0; i < count; ++i) {
@@ -58,24 +76,4 @@ public class BlockSummariesMessage extends Message {
 		return new BlockSummariesMessage(id, blockSummaries);
 	}
 
-	@Override
-	protected byte[] toData() {
-		try {
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
-
-			bytes.write(Ints.toByteArray(this.blockSummaries.size()));
-
-			for (BlockSummaryData blockSummary : this.blockSummaries) {
-				bytes.write(Ints.toByteArray(blockSummary.getHeight()));
-				bytes.write(blockSummary.getSignature());
-				bytes.write(blockSummary.getMinterPublicKey());
-				bytes.write(Ints.toByteArray(blockSummary.getOnlineAccountsCount()));
-			}
-
-			return bytes.toByteArray();
-		} catch (IOException e) {
-			return null;
-		}
-	}
-
 }

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

@@ -2,7 +2,6 @@ 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;
@@ -12,59 +11,34 @@ 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 {
+public class CachedBlockMessage extends Message implements Cloneable {
 
-	private Block block = null;
-	private byte[] cachedBytes = null;
-
-	public CachedBlockMessage(Block block) {
+	public CachedBlockMessage(Block block) throws TransformationException {
 		super(MessageType.BLOCK);
 
-		this.block = block;
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			bytes.write(Ints.toByteArray(block.getBlockData().getHeight()));
+
+			bytes.write(BlockTransformer.toBytes(block));
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
 	}
 
 	public CachedBlockMessage(byte[] cachedBytes) {
 		super(MessageType.BLOCK);
 
-		this.block = null;
-		this.cachedBytes = cachedBytes;
+		this.dataBytes = cachedBytes;
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
 	}
-	
-	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) throws UnsupportedEncodingException {
+
+	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) {
 		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/ChallengeMessage.java

@@ -10,8 +10,25 @@ public class ChallengeMessage extends Message {
 
 	public static final int CHALLENGE_LENGTH = 32;
 
-	private final byte[] publicKey;
-	private final byte[] challenge;
+	private byte[] publicKey;
+	private byte[] challenge;
+
+	public ChallengeMessage(byte[] publicKey, byte[] challenge) {
+		super(MessageType.CHALLENGE);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream(publicKey.length + challenge.length);
+
+		try {
+			bytes.write(publicKey);
+
+			bytes.write(challenge);
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
 
 	private ChallengeMessage(int id, byte[] publicKey, byte[] challenge) {
 		super(id, MessageType.CHALLENGE);
@@ -20,10 +37,6 @@ public class ChallengeMessage extends Message {
 		this.challenge = challenge;
 	}
 
-	public ChallengeMessage(byte[] publicKey, byte[] challenge) {
-		this(-1, publicKey, challenge);
-	}
-
 	public byte[] getPublicKey() {
 		return this.publicKey;
 	}
@@ -42,15 +55,4 @@ public class ChallengeMessage extends Message {
 		return new ChallengeMessage(id, publicKey, challenge);
 	}
 
-	@Override
-	protected byte[] toData() throws IOException {
-		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
-
-		bytes.write(this.publicKey);
-
-		bytes.write(this.challenge);
-
-		return bytes.toByteArray();
-	}
-
 }

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

@@ -2,40 +2,67 @@ package org.qortal.network.message;
 
 import com.google.common.primitives.Ints;
 import com.google.common.primitives.Longs;
+import org.qortal.data.network.PeerData;
+import org.qortal.transform.TransformationException;
 import org.qortal.transform.Transformer;
-import org.qortal.transform.transaction.TransactionTransformer;
+import org.qortal.utils.Serialization;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.List;
 
-import static org.qortal.transform.Transformer.INT_LENGTH;
-import static org.qortal.transform.Transformer.LONG_LENGTH;
-
 public class GetArbitraryDataFileListMessage extends Message {
 
-	private static final int SIGNATURE_LENGTH = Transformer.SIGNATURE_LENGTH;
-	private static final int HASH_LENGTH = TransactionTransformer.SHA256_LENGTH;
-
-	private final byte[] signature;
+	private byte[] signature;
 	private List<byte[]> hashes;
-	private final long requestTime;
+	private long requestTime;
 	private int requestHops;
+	private String requestingPeer;
 
-	public GetArbitraryDataFileListMessage(byte[] signature, List<byte[]> hashes, long requestTime, int requestHops) {
-		this(-1, signature, hashes, requestTime, requestHops);
+	public GetArbitraryDataFileListMessage(byte[] signature, List<byte[]> hashes, long requestTime, int requestHops, String requestingPeer) {
+		super(MessageType.GET_ARBITRARY_DATA_FILE_LIST);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			bytes.write(signature);
+
+			bytes.write(Longs.toByteArray(requestTime));
+
+			bytes.write(Ints.toByteArray(requestHops));
+
+			if (hashes != null) {
+				bytes.write(Ints.toByteArray(hashes.size()));
+
+				for (byte[] hash : hashes) {
+					bytes.write(hash);
+				}
+			}
+			else {
+				bytes.write(Ints.toByteArray(0));
+			}
+
+			if (requestingPeer != null) {
+				Serialization.serializeSizedStringV2(bytes, requestingPeer);
+			}
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
 	}
 
-	private GetArbitraryDataFileListMessage(int id, byte[] signature, List<byte[]> hashes, long requestTime, int requestHops) {
+	private GetArbitraryDataFileListMessage(int id, byte[] signature, List<byte[]> hashes, long requestTime, int requestHops, String requestingPeer) {
 		super(id, MessageType.GET_ARBITRARY_DATA_FILE_LIST);
 
 		this.signature = signature;
 		this.hashes = hashes;
 		this.requestTime = requestTime;
 		this.requestHops = requestHops;
+		this.requestingPeer = requestingPeer;
 	}
 
 	public byte[] getSignature() {
@@ -46,8 +73,20 @@ public class GetArbitraryDataFileListMessage extends Message {
 		return this.hashes;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
-		byte[] signature = new byte[SIGNATURE_LENGTH];
+	public long getRequestTime() {
+		return this.requestTime;
+	}
+
+	public int getRequestHops() {
+		return this.requestHops;
+	}
+
+	public String getRequestingPeer() {
+		return this.requestingPeer;
+	}
+
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws MessageException {
+		byte[] signature = new byte[Transformer.SIGNATURE_LENGTH];
 
 		bytes.get(signature);
 
@@ -59,55 +98,24 @@ public class GetArbitraryDataFileListMessage extends Message {
 		if (bytes.hasRemaining()) {
 			int hashCount = bytes.getInt();
 
-			if (bytes.remaining() != hashCount * HASH_LENGTH) {
-				return null;
-			}
-
 			hashes = new ArrayList<>();
 			for (int i = 0; i < hashCount; ++i) {
-				byte[] hash = new byte[HASH_LENGTH];
+				byte[] hash = new byte[Transformer.SHA256_LENGTH];
 				bytes.get(hash);
 				hashes.add(hash);
 			}
 		}
 
-		return new GetArbitraryDataFileListMessage(id, signature, hashes, requestTime, requestHops);
-	}
-
-	@Override
-	protected byte[] toData() {
-		try {
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
-
-			bytes.write(this.signature);
-
-			bytes.write(Longs.toByteArray(this.requestTime));
-
-			bytes.write(Ints.toByteArray(this.requestHops));
-
-			if (this.hashes != null) {
-				bytes.write(Ints.toByteArray(this.hashes.size()));
-
-				for (byte[] hash : this.hashes) {
-					bytes.write(hash);
-				}
+		String requestingPeer = null;
+		if (bytes.hasRemaining()) {
+			try {
+				requestingPeer = Serialization.deserializeSizedStringV2(bytes, PeerData.MAX_PEER_ADDRESS_SIZE);
+			} catch (TransformationException e) {
+				throw new MessageException(e.getMessage(), e);
 			}
-
-			return bytes.toByteArray();
-		} catch (IOException e) {
-			return null;
 		}
-	}
 
-	public long getRequestTime() {
-		return this.requestTime;
-	}
-
-	public int getRequestHops() {
-		return this.requestHops;
-	}
-	public void setRequestHops(int requestHops) {
-		this.requestHops = requestHops;
+		return new GetArbitraryDataFileListMessage(id, signature, hashes, requestTime, requestHops, requestingPeer);
 	}
 
 }

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

@@ -1,23 +1,31 @@
 package org.qortal.network.message;
 
 import org.qortal.transform.Transformer;
-import org.qortal.transform.transaction.TransactionTransformer;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
 
 public class GetArbitraryDataFileMessage extends Message {
 
-	private static final int SIGNATURE_LENGTH = Transformer.SIGNATURE_LENGTH;
-	private static final int HASH_LENGTH = TransactionTransformer.SHA256_LENGTH;
-
-	private final byte[] signature;
-	private final byte[] hash;
+	private byte[] signature;
+	private byte[] hash;
 
 	public GetArbitraryDataFileMessage(byte[] signature, byte[] hash) {
-		this(-1, signature, hash);
+		super(MessageType.GET_ARBITRARY_DATA_FILE);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream(signature.length + hash.length);
+
+		try {
+			bytes.write(signature);
+
+			bytes.write(hash);
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
 	}
 
 	private GetArbitraryDataFileMessage(int id, byte[] signature, byte[] hash) {
@@ -35,32 +43,14 @@ public class GetArbitraryDataFileMessage extends Message {
 		return this.hash;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
-		if (bytes.remaining() != HASH_LENGTH + SIGNATURE_LENGTH)
-			return null;
-
-		byte[] signature = new byte[SIGNATURE_LENGTH];
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
+		byte[] signature = new byte[Transformer.SIGNATURE_LENGTH];
 		bytes.get(signature);
 
-		byte[] hash = new byte[HASH_LENGTH];
+		byte[] hash = new byte[Transformer.SHA256_LENGTH];
 		bytes.get(hash);
 
 		return new GetArbitraryDataFileMessage(id, signature, hash);
 	}
 
-	@Override
-	protected byte[] toData() {
-		try {
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
-
-			bytes.write(this.signature);
-
-			bytes.write(this.hash);
-
-			return bytes.toByteArray();
-		} catch (IOException e) {
-			return null;
-		}
-	}
-
 }

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

@@ -1,20 +1,19 @@
 package org.qortal.network.message;
 
-import java.io.ByteArrayOutputStream;
-import java.io.IOException;
-import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
+import java.util.Arrays;
 
 import org.qortal.transform.Transformer;
 
 public class GetArbitraryDataMessage extends Message {
 
-	private static final int SIGNATURE_LENGTH = Transformer.SIGNATURE_LENGTH;
-
 	private byte[] signature;
 
 	public GetArbitraryDataMessage(byte[] signature) {
-		this(-1, signature);
+		super(MessageType.GET_ARBITRARY_DATA);
+
+		this.dataBytes = Arrays.copyOf(signature, signature.length);
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
 	}
 
 	private GetArbitraryDataMessage(int id, byte[] signature) {
@@ -27,28 +26,12 @@ public class GetArbitraryDataMessage extends Message {
 		return this.signature;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
-		if (bytes.remaining() != SIGNATURE_LENGTH)
-			return null;
-
-		byte[] signature = new byte[SIGNATURE_LENGTH];
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
+		byte[] signature = new byte[Transformer.SIGNATURE_LENGTH];
 
 		bytes.get(signature);
 
 		return new GetArbitraryDataMessage(id, signature);
 	}
 
-	@Override
-	protected byte[] toData() {
-		try {
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
-
-			bytes.write(this.signature);
-
-			return bytes.toByteArray();
-		} catch (IOException e) {
-			return null;
-		}
-	}
-
 }

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

@@ -0,0 +1,67 @@
+package org.qortal.network.message;
+
+import com.google.common.primitives.Ints;
+import com.google.common.primitives.Longs;
+import org.qortal.transform.Transformer;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+public class GetArbitraryMetadataMessage extends Message {
+
+	private byte[] signature;
+	private long requestTime;
+	private int requestHops;
+
+	public GetArbitraryMetadataMessage(byte[] signature, long requestTime, int requestHops) {
+		super(MessageType.GET_ARBITRARY_METADATA);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			bytes.write(signature);
+
+			bytes.write(Longs.toByteArray(requestTime));
+
+			bytes.write(Ints.toByteArray(requestHops));
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
+
+	private GetArbitraryMetadataMessage(int id, byte[] signature, long requestTime, int requestHops) {
+		super(id, MessageType.GET_ARBITRARY_METADATA);
+
+		this.signature = signature;
+		this.requestTime = requestTime;
+		this.requestHops = requestHops;
+	}
+
+	public byte[] getSignature() {
+		return this.signature;
+	}
+
+	public long getRequestTime() {
+		return this.requestTime;
+	}
+
+	public int getRequestHops() {
+		return this.requestHops;
+	}
+
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
+		byte[] signature = new byte[Transformer.SIGNATURE_LENGTH];
+		bytes.get(signature);
+
+		long requestTime = bytes.getLong();
+
+		int requestHops = bytes.getInt();
+
+		return new GetArbitraryMetadataMessage(id, signature, requestTime, requestHops);
+	}
+
+}

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

@@ -1,20 +1,19 @@
 package org.qortal.network.message;
 
-import java.io.ByteArrayOutputStream;
-import java.io.IOException;
-import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
+import java.util.Arrays;
 
 import org.qortal.transform.block.BlockTransformer;
 
 public class GetBlockMessage extends Message {
 
-	private static final int BLOCK_SIGNATURE_LENGTH = BlockTransformer.BLOCK_SIGNATURE_LENGTH;
-
 	private byte[] signature;
 
 	public GetBlockMessage(byte[] signature) {
-		this(-1, signature);
+		super(MessageType.GET_BLOCK);
+
+		this.dataBytes = Arrays.copyOf(signature, signature.length);
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
 	}
 
 	private GetBlockMessage(int id, byte[] signature) {
@@ -27,28 +26,11 @@ public class GetBlockMessage extends Message {
 		return this.signature;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
-		if (bytes.remaining() != BLOCK_SIGNATURE_LENGTH)
-			return null;
-
-		byte[] signature = new byte[BLOCK_SIGNATURE_LENGTH];
-
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
+		byte[] signature = new byte[BlockTransformer.BLOCK_SIGNATURE_LENGTH];
 		bytes.get(signature);
 
 		return new GetBlockMessage(id, signature);
 	}
 
-	@Override
-	protected byte[] toData() {
-		try {
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
-
-			bytes.write(this.signature);
-
-			return bytes.toByteArray();
-		} catch (IOException e) {
-			return null;
-		}
-	}
-
 }

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

@@ -2,23 +2,32 @@ package org.qortal.network.message;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
 
-import org.qortal.transform.Transformer;
 import org.qortal.transform.block.BlockTransformer;
 
 import com.google.common.primitives.Ints;
 
 public class GetBlockSummariesMessage extends Message {
 
-	private static final int BLOCK_SIGNATURE_LENGTH = BlockTransformer.BLOCK_SIGNATURE_LENGTH;
-
 	private byte[] parentSignature;
 	private int numberRequested;
 
 	public GetBlockSummariesMessage(byte[] parentSignature, int numberRequested) {
-		this(-1, parentSignature, numberRequested);
+		super(MessageType.GET_BLOCK_SUMMARIES);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			bytes.write(parentSignature);
+
+			bytes.write(Ints.toByteArray(numberRequested));
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
 	}
 
 	private GetBlockSummariesMessage(int id, byte[] parentSignature, int numberRequested) {
@@ -36,11 +45,8 @@ public class GetBlockSummariesMessage extends Message {
 		return this.numberRequested;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
-		if (bytes.remaining() != BLOCK_SIGNATURE_LENGTH + Transformer.INT_LENGTH)
-			return null;
-
-		byte[] parentSignature = new byte[BLOCK_SIGNATURE_LENGTH];
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
+		byte[] parentSignature = new byte[BlockTransformer.BLOCK_SIGNATURE_LENGTH];
 		bytes.get(parentSignature);
 
 		int numberRequested = bytes.getInt();
@@ -48,19 +54,4 @@ public class GetBlockSummariesMessage extends Message {
 		return new GetBlockSummariesMessage(id, parentSignature, numberRequested);
 	}
 
-	@Override
-	protected byte[] toData() {
-		try {
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
-
-			bytes.write(this.parentSignature);
-
-			bytes.write(Ints.toByteArray(this.numberRequested));
-
-			return bytes.toByteArray();
-		} catch (IOException e) {
-			return null;
-		}
-	}
-
 }

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

@@ -2,7 +2,6 @@ package org.qortal.network.message;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.List;
@@ -20,7 +19,24 @@ public class GetOnlineAccountsMessage extends Message {
 	private List<OnlineAccountData> onlineAccounts;
 
 	public GetOnlineAccountsMessage(List<OnlineAccountData> onlineAccounts) {
-		this(-1, onlineAccounts);
+		super(MessageType.GET_ONLINE_ACCOUNTS);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			bytes.write(Ints.toByteArray(onlineAccounts.size()));
+
+			for (OnlineAccountData onlineAccountData : onlineAccounts) {
+				bytes.write(Longs.toByteArray(onlineAccountData.getTimestamp()));
+
+				bytes.write(onlineAccountData.getPublicKey());
+			}
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
 	}
 
 	private GetOnlineAccountsMessage(int id, List<OnlineAccountData> onlineAccounts) {
@@ -33,7 +49,7 @@ public class GetOnlineAccountsMessage extends Message {
 		return this.onlineAccounts;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
 		final int accountCount = bytes.getInt();
 
 		List<OnlineAccountData> onlineAccounts = new ArrayList<>(accountCount);
@@ -50,24 +66,4 @@ public class GetOnlineAccountsMessage extends Message {
 		return new GetOnlineAccountsMessage(id, onlineAccounts);
 	}
 
-	@Override
-	protected byte[] toData() {
-		try {
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
-
-			bytes.write(Ints.toByteArray(this.onlineAccounts.size()));
-
-			for (int i = 0; i < this.onlineAccounts.size(); ++i) {
-				OnlineAccountData onlineAccountData = this.onlineAccounts.get(i);
-				bytes.write(Longs.toByteArray(onlineAccountData.getTimestamp()));
-
-				bytes.write(onlineAccountData.getPublicKey());
-			}
-
-			return bytes.toByteArray();
-		} catch (IOException e) {
-			return null;
-		}
-	}
-
 }

src/main/java/org/qortal/network/message/GetOnlineAccountsV2Message.java

@@ -0,0 +1,109 @@
+package org.qortal.network.message;
+
+import com.google.common.primitives.Ints;
+import com.google.common.primitives.Longs;
+import org.qortal.data.network.OnlineAccountData;
+import org.qortal.transform.Transformer;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * For requesting online accounts info from remote peer, given our list of online accounts.
+ *
+ * Different format to V1:
+ * V1 is: number of entries, then timestamp + pubkey for each entry
+ * V2 is: groups of: number of entries, timestamp, then pubkey for each entry
+ *
+ * Also V2 only builds online accounts message once!
+ */
+public class GetOnlineAccountsV2Message extends Message {
+
+	private List<OnlineAccountData> onlineAccounts;
+
+	public GetOnlineAccountsV2Message(List<OnlineAccountData> onlineAccounts) {
+		super(MessageType.GET_ONLINE_ACCOUNTS_V2);
+
+		// If we don't have ANY online accounts then it's an easier construction...
+		if (onlineAccounts.isEmpty()) {
+			// Always supply a number of accounts
+			this.dataBytes = Ints.toByteArray(0);
+			this.checksumBytes = Message.generateChecksum(this.dataBytes);
+			return;
+		}
+
+		// How many of each timestamp
+		Map<Long, Integer> countByTimestamp = new HashMap<>();
+
+		for (OnlineAccountData onlineAccountData : onlineAccounts) {
+			Long timestamp = onlineAccountData.getTimestamp();
+			countByTimestamp.compute(timestamp, (k, v) -> v == null ? 1 : ++v);
+		}
+
+		// We should know exactly how many bytes to allocate now
+		int byteSize = countByTimestamp.size() * (Transformer.INT_LENGTH + Transformer.TIMESTAMP_LENGTH)
+				+ onlineAccounts.size() * Transformer.PUBLIC_KEY_LENGTH;
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream(byteSize);
+
+		try {
+			for (long timestamp : countByTimestamp.keySet()) {
+				bytes.write(Ints.toByteArray(countByTimestamp.get(timestamp)));
+
+				bytes.write(Longs.toByteArray(timestamp));
+
+				for (OnlineAccountData onlineAccountData : onlineAccounts) {
+					if (onlineAccountData.getTimestamp() == timestamp)
+						bytes.write(onlineAccountData.getPublicKey());
+				}
+			}
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
+
+	private GetOnlineAccountsV2Message(int id, List<OnlineAccountData> onlineAccounts) {
+		super(id, MessageType.GET_ONLINE_ACCOUNTS_V2);
+
+		this.onlineAccounts = onlineAccounts;
+	}
+
+	public List<OnlineAccountData> getOnlineAccounts() {
+		return this.onlineAccounts;
+	}
+
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
+		int accountCount = bytes.getInt();
+
+		List<OnlineAccountData> onlineAccounts = new ArrayList<>(accountCount);
+
+		while (accountCount > 0) {
+			long timestamp = bytes.getLong();
+
+			for (int i = 0; i < accountCount; ++i) {
+				byte[] publicKey = new byte[Transformer.PUBLIC_KEY_LENGTH];
+				bytes.get(publicKey);
+
+				onlineAccounts.add(new OnlineAccountData(timestamp, null, publicKey));
+			}
+
+			if (bytes.hasRemaining()) {
+				accountCount = bytes.getInt();
+			} else {
+				// we've finished
+				accountCount = 0;
+			}
+		}
+
+		return new GetOnlineAccountsV2Message(id, onlineAccounts);
+	}
+
+}

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

@@ -1,25 +1,21 @@
 package org.qortal.network.message;
 
-import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
 
 public class GetPeersMessage extends Message {
 
 	public GetPeersMessage() {
-		this(-1);
+		super(MessageType.GET_PEERS);
+
+		this.dataBytes = EMPTY_DATA_BYTES;
 	}
 
 	private GetPeersMessage(int id) {
 		super(id, MessageType.GET_PEERS);
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
 		return new GetPeersMessage(id);
 	}
 
-	@Override
-	protected byte[] toData() {
-		return new byte[0];
-	}
-
 }