Added test to simulate level 7-8 reward tier activation, including orphaning.

This reverts commit 90e8cfc737.

# Conflicts:
#	src/test/java/org/qortal/test/minting/RewardTests.java

.gitignore

@@ -28,6 +28,7 @@
 /WindowsInstaller/Install Files/qortal.jar
 /*.7z
 /tmp
+/wallets
 /data*
 /src/test/resources/arbitrary/*/.qortal/cache
 apikey.txt

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:{DEA09B3D-AFFA-409F-B208-E148E9A9005D} 1049:{79180B3D-8A6B-4DED-BD60-1A58F941E1DE} 2052:{90F65B96-22CD-41FA-82B0-E65183EA1EF9} 2057:{AB4872AC-E794-42BD-9305-8DFD06243A88} " Type="16"/>
+    <ROW Property="ProductCode" Value="1033:{B786B6C1-86FA-4917-BAF9-7C9D10959D66} 1049:{60881A63-53FC-4DBE-AF3B-0568F55D2150} 2052:{108D1268-8111-49B9-B768-CC0A0A0CEDE1} 2057:{46DB692E-D942-40D5-B32E-FB94458478BF} " Type="16"/>
     <ROW Property="ProductLanguage" Value="2057"/>
     <ROW Property="ProductName" Value="Qortal"/>
-    <ROW Property="ProductVersion" Value="3.2.3" Type="32"/>
+    <ROW Property="ProductVersion" Value="3.4.0" 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="{63FD92A7-4AE2-46A0-9B83-EB27DA636C65}" Directory_="APPDIR" Attributes="260" KeyPath="DisplayName" Options="1"/>
+    <ROW Component="AI_CustomARPName" ComponentId="{D57E945C-0FFB-447C-ADF7-2253CEBF4C0C}" 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"/>

pom.xml

@@ -3,7 +3,7 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>org.qortal</groupId>
 	<artifactId>qortal</artifactId>
-	<version>3.2.3</version>
+	<version>3.4.1</version>
 	<packaging>jar</packaging>
 	<properties>
 		<skipTests>true</skipTests>

src/main/java/org/qortal/ApplyUpdate.java

@@ -8,6 +8,7 @@ import java.nio.file.Paths;
 import java.nio.file.StandardCopyOption;
 import java.security.Security;
 import java.util.*;
+import java.util.stream.Collectors;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -18,6 +19,8 @@ import org.qortal.api.ApiRequest;
 import org.qortal.controller.AutoUpdate;
 import org.qortal.settings.Settings;
 
+import static org.qortal.controller.AutoUpdate.AGENTLIB_JVM_HOLDER_ARG;
+
 public class ApplyUpdate {
 
 	static {
@@ -37,7 +40,7 @@ public class ApplyUpdate {
 	private static final String JAVA_TOOL_OPTIONS_NAME = "JAVA_TOOL_OPTIONS";
 	private static final String JAVA_TOOL_OPTIONS_VALUE = "-XX:MaxRAMFraction=4";
 
-	private static final long CHECK_INTERVAL = 10 * 1000L; // ms
+	private static final long CHECK_INTERVAL = 30 * 1000L; // ms
 	private static final int MAX_ATTEMPTS = 12;
 
 	public static void main(String[] args) {
@@ -197,6 +200,11 @@ public class ApplyUpdate {
 			// JVM arguments
 			javaCmd.addAll(ManagementFactory.getRuntimeMXBean().getInputArguments());
 
+			// Reapply any retained, but disabled, -agentlib JVM arg
+			javaCmd = javaCmd.stream()
+					.map(arg -> arg.replace(AGENTLIB_JVM_HOLDER_ARG, "-agentlib"))
+					.collect(Collectors.toList());
+
 			// Call mainClass in JAR
 			javaCmd.addAll(Arrays.asList("-jar", JAR_FILENAME));
 
@@ -205,7 +213,7 @@ public class ApplyUpdate {
 		}
 
 		try {
-			LOGGER.info(() -> String.format("Restarting node with: %s", String.join(" ", javaCmd)));
+			LOGGER.info(String.format("Restarting node with: %s", String.join(" ", javaCmd)));
 
 			ProcessBuilder processBuilder = new ProcessBuilder(javaCmd);
 
@@ -214,8 +222,15 @@ public class ApplyUpdate {
 				processBuilder.environment().put(JAVA_TOOL_OPTIONS_NAME, JAVA_TOOL_OPTIONS_VALUE);
 			}
 
-			processBuilder.start();
-		} catch (IOException e) {
+			// New process will inherit our stdout and stderr
+			processBuilder.redirectOutput(ProcessBuilder.Redirect.INHERIT);
+			processBuilder.redirectError(ProcessBuilder.Redirect.INHERIT);
+
+			Process process = processBuilder.start();
+
+			// Nothing to pipe to new process, so close output stream (process's stdin)
+			process.getOutputStream().close();
+		} catch (Exception e) {
 			LOGGER.error(String.format("Failed to restart node (BAD): %s", e.getMessage()));
 		}
 	}

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

@@ -8,11 +8,13 @@ import javax.xml.bind.annotation.XmlAccessorType;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.block.BlockChain;
+import org.qortal.controller.LiteNode;
 import org.qortal.data.account.AccountBalanceData;
 import org.qortal.data.account.AccountData;
 import org.qortal.data.account.RewardShareData;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
+import org.qortal.settings.Settings;
 import org.qortal.utils.Base58;
 
 @XmlAccessorType(XmlAccessType.NONE) // Stops JAX-RS errors when unmarshalling blockchain config
@@ -59,7 +61,17 @@ public class Account {
 	// Balance manipulations - assetId is 0 for QORT
 
 	public long getConfirmedBalance(long assetId) throws DataException {
-		AccountBalanceData accountBalanceData = this.repository.getAccountRepository().getBalance(this.address, assetId);
+		AccountBalanceData accountBalanceData;
+
+		if (Settings.getInstance().isLite()) {
+			// Lite nodes request data from peers instead of the local db
+			accountBalanceData = LiteNode.getInstance().fetchAccountBalance(this.address, assetId);
+		}
+		else {
+			// All other node types fetch from the local db
+			accountBalanceData = this.repository.getAccountRepository().getBalance(this.address, assetId);
+		}
+
 		if (accountBalanceData == null)
 			return 0;
 

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

@@ -11,15 +11,15 @@ public class PrivateKeyAccount extends PublicKeyAccount {
 	private final Ed25519PrivateKeyParameters edPrivateKeyParams;
 
 	/**
-	 * Create PrivateKeyAccount using byte[32] seed.
+	 * Create PrivateKeyAccount using byte[32] private key.
 	 * 
-	 * @param seed
+	 * @param privateKey
 	 *            byte[32] used to create private/public key pair
 	 * @throws IllegalArgumentException
-	 *             if passed invalid seed
+	 *             if passed invalid privateKey
 	 */
-	public PrivateKeyAccount(Repository repository, byte[] seed) {
-		this(repository, new Ed25519PrivateKeyParameters(seed, 0));
+	public PrivateKeyAccount(Repository repository, byte[] privateKey) {
+		this(repository, new Ed25519PrivateKeyParameters(privateKey, 0));
 	}
 
 	private PrivateKeyAccount(Repository repository, Ed25519PrivateKeyParameters edPrivateKeyParams) {
@@ -37,10 +37,6 @@ public class PrivateKeyAccount extends PublicKeyAccount {
 		return this.privateKey;
 	}
 
-	public static byte[] toPublicKey(byte[] seed) {
-		return new Ed25519PrivateKeyParameters(seed, 0).generatePublicKey().getEncoded();
-	}
-
 	public byte[] sign(byte[] message) {
 		return Crypto.sign(this.edPrivateKeyParams, message);
 	}

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

@@ -12,6 +12,7 @@ public class NodeInfo {
 	public long buildTimestamp;
 	public String nodeId;
 	public boolean isTestNet;
+	public String type;
 
 	public NodeInfo() {
 	}

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

@@ -4,6 +4,7 @@ import javax.xml.bind.annotation.XmlAccessType;
 import javax.xml.bind.annotation.XmlAccessorType;
 
 import org.qortal.controller.Controller;
+import org.qortal.controller.OnlineAccountsManager;
 import org.qortal.controller.Synchronizer;
 import org.qortal.network.Network;
 
@@ -21,7 +22,7 @@ public class NodeStatus {
 	public final int height;
 
 	public NodeStatus() {
-		this.isMintingPossible = Controller.getInstance().isMintingPossible();
+		this.isMintingPossible = OnlineAccountsManager.getInstance().hasActiveOnlineAccountSignatures();
 
 		this.syncPercent = Synchronizer.getInstance().getSyncPercent();
 		this.isSynchronizing = Synchronizer.getInstance().isSynchronizing();

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/resource/AddressesResource.java

@@ -30,6 +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.LiteNode;
 import org.qortal.controller.OnlineAccountsManager;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.account.AccountData;
@@ -109,18 +110,26 @@ public class AddressesResource {
 		if (!Crypto.isValidAddress(address))
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
 
-		byte[] lastReference = null;
+		AccountData accountData;
 
-		try (final Repository repository = RepositoryManager.getRepository()) {
-			AccountData accountData = repository.getAccountRepository().getAccount(address);
-			// Not found?
-			if (accountData == null)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
-
-			lastReference = accountData.getReference();
-		} catch (DataException e) {
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		if (Settings.getInstance().isLite()) {
+			// Lite nodes request data from peers instead of the local db
+			accountData = LiteNode.getInstance().fetchAccountData(address);
 		}
+		else {
+			// All other node types request data from local db
+			try (final Repository repository = RepositoryManager.getRepository()) {
+				accountData = repository.getAccountRepository().getAccount(address);
+			} catch (DataException e) {
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+			}
+		}
+
+		// Not found?
+		if (accountData == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
+
+		byte[] lastReference = accountData.getReference();
 
 		if (lastReference == null || lastReference.length == 0)
 			return "false";

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

@@ -119,10 +119,23 @@ public class AdminResource {
 		nodeInfo.buildTimestamp = Controller.getInstance().getBuildTimestamp();
 		nodeInfo.nodeId = Network.getInstance().getOurNodeId();
 		nodeInfo.isTestNet = Settings.getInstance().isTestNet();
+		nodeInfo.type = getNodeType();
 
 		return nodeInfo;
 	}
 
+	private String getNodeType() {
+		if (Settings.getInstance().isLite()) {
+			return "lite";
+		}
+		else if (Settings.getInstance().isTopOnly()) {
+			return "topOnly";
+		}
+		else {
+			return "full";
+		}
+	}
+
 	@GET
 	@Path("/status")
 	@Operation(
@@ -381,6 +394,10 @@ 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();
@@ -396,6 +413,13 @@ 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 "";
@@ -416,7 +440,7 @@ 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) {

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

@@ -57,6 +57,7 @@ import org.qortal.transform.TransformationException;
 import org.qortal.transform.transaction.ArbitraryTransactionTransformer;
 import org.qortal.transform.transaction.TransactionTransformer;
 import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
 import org.qortal.utils.ZipUtils;
 
 @Path("/arbitrary")
@@ -1099,7 +1100,8 @@ public class ArbitraryResource {
 				throw ApiExceptionFactory.INSTANCE.createCustomException(request, ApiError.INVALID_CRITERIA, error);
 			}
 
-			if (!Controller.getInstance().isUpToDate()) {
+			final Long minLatestBlockTimestamp = NTP.getTime() - (60 * 60 * 1000L);
+			if (!Controller.getInstance().isUpToDate(minLatestBlockTimestamp)) {
 				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCKCHAIN_NEEDS_SYNC);
 			}
 

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

@@ -114,7 +114,7 @@ public class BlocksResource {
 	@Path("/signature/{signature}/data")
 	@Operation(
 			summary = "Fetch serialized, base58 encoded block data using base58 signature",
-			description = "Returns serialized data for the block that matches the given signature",
+			description = "Returns serialized data for the block that matches the given signature, and an optional block serialization version",
 			responses = {
 					@ApiResponse(
 							description = "the block data",
@@ -125,7 +125,7 @@ public class BlocksResource {
 	@ApiErrors({
 			ApiError.INVALID_SIGNATURE, ApiError.BLOCK_UNKNOWN, ApiError.INVALID_DATA, ApiError.REPOSITORY_ISSUE
 	})
-	public String getSerializedBlockData(@PathParam("signature") String signature58) {
+	public String getSerializedBlockData(@PathParam("signature") String signature58, @QueryParam("version") Integer version) {
 		// Decode signature
 		byte[] signature;
 		try {
@@ -136,20 +136,41 @@ public class BlocksResource {
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
 
+			// Default to version 1
+			if (version == null) {
+				version = 1;
+			}
+
             // Check the database first
 			BlockData blockData = repository.getBlockRepository().fromSignature(signature);
 			if (blockData != null) {
                 Block block = new Block(repository, blockData);
                 ByteArrayOutputStream bytes = new ByteArrayOutputStream();
                 bytes.write(Ints.toByteArray(block.getBlockData().getHeight()));
-                bytes.write(BlockTransformer.toBytes(block));
+
+				switch (version) {
+					case 1:
+						bytes.write(BlockTransformer.toBytes(block));
+						break;
+
+					case 2:
+						bytes.write(BlockTransformer.toBytesV2(block));
+						break;
+
+					default:
+						throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+				}
+
                 return Base58.encode(bytes.toByteArray());
             }
 
             // Not found, so try the block archive
             byte[] bytes = BlockArchiveReader.getInstance().fetchSerializedBlockBytesForSignature(signature, false, repository);
             if (bytes != null) {
-                return Base58.encode(bytes);
+				if (version != 1) {
+					throw ApiExceptionFactory.INSTANCE.createCustomException(request, ApiError.INVALID_CRITERIA, "Archived blocks require version 1");
+				}
+				return Base58.encode(bytes);
             }
 
             throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);

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/CrossChainTradeBotResource.java

@@ -42,6 +42,7 @@ import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryManager;
 import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
 
 @Path("/crosschain/tradebot")
 @Tag(name = "Cross-Chain (Trade-Bot)")
@@ -137,7 +138,8 @@ public class CrossChainTradeBotResource {
 		if (tradeBotCreateRequest.qortAmount <= 0 || tradeBotCreateRequest.fundingQortAmount <= 0)
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ORDER_SIZE_TOO_SMALL);
 
-		if (!Controller.getInstance().isUpToDate())
+		final Long minLatestBlockTimestamp = NTP.getTime() - (60 * 60 * 1000L);
+		if (!Controller.getInstance().isUpToDate(minLatestBlockTimestamp))
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCKCHAIN_NEEDS_SYNC);
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
@@ -198,7 +200,8 @@ public class CrossChainTradeBotResource {
 		if (tradeBotRespondRequest.receivingAddress == null || !Crypto.isValidAddress(tradeBotRespondRequest.receivingAddress))
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
 
-		if (!Controller.getInstance().isUpToDate())
+		final Long minLatestBlockTimestamp = NTP.getTime() - (60 * 60 * 1000L);
+		if (!Controller.getInstance().isUpToDate(minLatestBlockTimestamp))
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCKCHAIN_NEEDS_SYNC);
 
 		// Extract data from cross-chain trading AT

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

@@ -26,6 +26,7 @@ import org.qortal.api.ApiErrors;
 import org.qortal.api.ApiException;
 import org.qortal.api.ApiExceptionFactory;
 import org.qortal.api.model.NameSummary;
+import org.qortal.controller.LiteNode;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.naming.NameData;
 import org.qortal.data.transaction.BuyNameTransactionData;
@@ -101,7 +102,14 @@ public class NamesResource {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			List<NameData> names = repository.getNameRepository().getNamesByOwner(address, limit, offset, reverse);
+			List<NameData> names;
+
+			if (Settings.getInstance().isLite()) {
+				names = LiteNode.getInstance().fetchAccountNames(address);
+			}
+			else {
+				names = repository.getNameRepository().getNamesByOwner(address, limit, offset, reverse);
+			}
 
 			return names.stream().map(NameSummary::new).collect(Collectors.toList());
 		} catch (DataException e) {
@@ -126,10 +134,18 @@ public class NamesResource {
 	@ApiErrors({ApiError.NAME_UNKNOWN, ApiError.REPOSITORY_ISSUE})
 	public NameData getName(@PathParam("name") String name) {
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			NameData nameData = repository.getNameRepository().fromName(name);
+			NameData nameData;
 
-			if (nameData == null)
+			if (Settings.getInstance().isLite()) {
+				nameData = LiteNode.getInstance().fetchNameData(name);
+			}
+			else {
+				nameData = repository.getNameRepository().fromName(name);
+			}
+
+			if (nameData == null) {
 				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.NAME_UNKNOWN);
+			}
 
 			return nameData;
 		} catch (ApiException e) {

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;
@@ -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();
 	}
 

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

@@ -12,6 +12,7 @@ import io.swagger.v3.oas.annotations.tags.Tag;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
 import java.util.ArrayList;
+import java.util.Comparator;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.locks.ReentrantLock;
@@ -32,6 +33,8 @@ import org.qortal.api.ApiException;
 import org.qortal.api.ApiExceptionFactory;
 import org.qortal.api.model.SimpleTransactionSignRequest;
 import org.qortal.controller.Controller;
+import org.qortal.controller.LiteNode;
+import org.qortal.crypto.Crypto;
 import org.qortal.data.transaction.TransactionData;
 import org.qortal.globalization.Translator;
 import org.qortal.repository.DataException;
@@ -250,14 +253,29 @@ public class TransactionsResource {
 		ApiError.REPOSITORY_ISSUE
 	})
 	public List<TransactionData> getUnconfirmedTransactions(@Parameter(
+			description = "A list of transaction types"
+	) @QueryParam("txType") List<TransactionType> txTypes, @Parameter(
+			description = "Transaction creator's base58 encoded public key"
+	) @QueryParam("creator") String creatorPublicKey58, @Parameter(
 		ref = "limit"
 	) @QueryParam("limit") Integer limit, @Parameter(
 		ref = "offset"
 	) @QueryParam("offset") Integer offset, @Parameter(
 		ref = "reverse"
 	) @QueryParam("reverse") Boolean reverse) {
+
+		// Decode public key if supplied
+		byte[] creatorPublicKey = null;
+		if (creatorPublicKey58 != null) {
+			try {
+				creatorPublicKey = Base58.decode(creatorPublicKey58);
+			} catch (NumberFormatException e) {
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY, e);
+			}
+		}
+
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			return repository.getTransactionRepository().getUnconfirmedTransactions(limit, offset, reverse);
+			return repository.getTransactionRepository().getUnconfirmedTransactions(txTypes, creatorPublicKey, limit, offset, reverse);
 		} catch (ApiException e) {
 			throw e;
 		} catch (DataException e) {
@@ -366,6 +384,73 @@ public class TransactionsResource {
 		}
 	}
 
+	@GET
+	@Path("/address/{address}")
+	@Operation(
+			summary = "Returns transactions for given address",
+			responses = {
+					@ApiResponse(
+							description = "transactions",
+							content = @Content(
+									array = @ArraySchema(
+											schema = @Schema(
+													implementation = TransactionData.class
+											)
+									)
+							)
+					)
+			}
+	)
+	@ApiErrors({ApiError.INVALID_ADDRESS,  ApiError.REPOSITORY_ISSUE})
+	public List<TransactionData> getAddressTransactions(@PathParam("address") String address,
+												 		@Parameter(ref = "limit") @QueryParam("limit") Integer limit,
+												 		@Parameter(ref = "offset") @QueryParam("offset") Integer offset,
+														@Parameter(ref = "reverse") @QueryParam("reverse") Boolean reverse) {
+		if (!Crypto.isValidAddress(address)) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+		}
+
+		if (limit == null) {
+			limit = 0;
+		}
+		if (offset == null) {
+			offset = 0;
+		}
+
+		List<TransactionData> transactions;
+
+		if (Settings.getInstance().isLite()) {
+			// Fetch from network
+			transactions = LiteNode.getInstance().fetchAccountTransactions(address, limit, offset);
+
+			// Sort the data, since we can't guarantee the order that a peer sent it in
+			if (reverse) {
+				transactions.sort(Comparator.comparingLong(TransactionData::getTimestamp).reversed());
+			} else {
+				transactions.sort(Comparator.comparingLong(TransactionData::getTimestamp));
+			}
+		}
+		else {
+			// Fetch from local db
+			try (final Repository repository = RepositoryManager.getRepository()) {
+				List<byte[]> signatures = repository.getTransactionRepository().getSignaturesMatchingCriteria(null, null, null,
+						null, null, null, address, TransactionsResource.ConfirmationStatus.CONFIRMED, limit, offset, reverse);
+
+				// Expand signatures to transactions
+				transactions = new ArrayList<>(signatures.size());
+				for (byte[] signature : signatures) {
+					transactions.add(repository.getTransactionRepository().fromSignature(signature));
+				}
+			} catch (ApiException e) {
+				throw e;
+			} catch (DataException e) {
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+			}
+		}
+
+		return transactions;
+	}
+
 	@GET
 	@Path("/unitfee")
 	@Operation(
@@ -638,9 +723,9 @@ public class TransactionsResource {
 		ApiError.BLOCKCHAIN_NEEDS_SYNC, ApiError.INVALID_SIGNATURE, ApiError.INVALID_DATA, ApiError.TRANSFORMATION_ERROR, ApiError.REPOSITORY_ISSUE
 	})
 	public String processTransaction(String rawBytes58) {
-		// Only allow a transaction to be processed if our latest block is less than 30 minutes old
+		// Only allow a transaction to be processed if our latest block is less than 60 minutes old
 		// If older than this, we should first wait until the blockchain is synced
-		final Long minLatestBlockTimestamp = NTP.getTime() - (30 * 60 * 1000L);
+		final Long minLatestBlockTimestamp = NTP.getTime() - (60 * 60 * 1000L);
 		if (!Controller.getInstance().isUpToDate(minLatestBlockTimestamp))
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCKCHAIN_NEEDS_SYNC);
 

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

@@ -94,14 +94,9 @@ public class ArbitraryDataFile {
         try (FileOutputStream outputStream = new FileOutputStream(outputFile)) {
             outputStream.write(fileContent);
             this.filePath = outputFilePath;
-            // Verify hash
-            if (!this.hash58.equals(this.digest58())) {
-                LOGGER.error("Hash {} does not match file digest {} for signature: {}", this.hash58, this.digest58(), Base58.encode(signature));
-                this.delete();
-                throw new DataException("Data file digest validation failed");
-            }
         } catch (IOException e) {
-            throw new DataException("Unable to write data to file");
+            this.delete();
+            throw new DataException(String.format("Unable to write data with hash %s: %s", this.hash58, e.getMessage()));
         }
     }
 

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

@@ -120,7 +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' 'unsafe-eval'; 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());

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

@@ -3,10 +3,14 @@ package org.qortal.block;
 import static java.util.Arrays.stream;
 import static java.util.stream.Collectors.toMap;
 
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
 import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.math.RoundingMode;
+import java.nio.charset.StandardCharsets;
 import java.text.DecimalFormat;
+import java.text.MessageFormat;
 import java.text.NumberFormat;
 import java.util.*;
 import java.util.stream.Collectors;
@@ -24,6 +28,7 @@ import org.qortal.block.BlockChain.BlockTimingByHeight;
 import org.qortal.block.BlockChain.AccountLevelShareBin;
 import org.qortal.controller.OnlineAccountsManager;
 import org.qortal.crypto.Crypto;
+import org.qortal.crypto.Qortal25519Extras;
 import org.qortal.data.account.AccountBalanceData;
 import org.qortal.data.account.AccountData;
 import org.qortal.data.account.EligibleQoraHolderData;
@@ -118,6 +123,8 @@ public class Block {
 
 	/** Remote/imported/loaded AT states */
 	protected List<ATStateData> atStates;
+	/** Remote hash of AT states - in lieu of full AT state data in {@code atStates} */
+	protected byte[] atStatesHash;
 	/** Locally-generated AT states */
 	protected List<ATStateData> ourAtStates;
 	/** Locally-generated AT fees */
@@ -192,6 +199,11 @@ public class Block {
 
 		}
 
+		public boolean hasShareBin(AccountLevelShareBin shareBin, int blockHeight) {
+			AccountLevelShareBin ourShareBin = this.getShareBin(blockHeight);
+			return ourShareBin != null && shareBin.id == ourShareBin.id;
+		}
+
 		public long distribute(long accountAmount, Map<String, Long> balanceChanges) {
 			if (this.isRecipientAlsoMinter) {
 				// minter & recipient the same - simpler case
@@ -216,11 +228,10 @@ public class Block {
 			return accountAmount;
 		}
 	}
+
 	/** Always use getExpandedAccounts() to access this, as it's lazy-instantiated. */
 	private List<ExpandedAccount> cachedExpandedAccounts = null;
 
-	/** Opportunistic cache of this block's valid online accounts. Only created by call to isValid(). */
-	private List<OnlineAccountData> cachedValidOnlineAccounts = null;
 	/** Opportunistic cache of this block's valid online reward-shares. Only created by call to isValid(). */
 	private List<RewardShareData> cachedOnlineRewardShares = null;
 
@@ -255,7 +266,7 @@ public class Block {
 	 * Constructs new Block using passed transaction and AT states.
 	 * <p>
 	 * This constructor typically used when receiving a serialized block over the network.
-	 * 
+	 *
 	 * @param repository
 	 * @param blockData
 	 * @param transactions
@@ -281,6 +292,35 @@ public class Block {
 		this.blockData.setTotalFees(totalFees);
 	}
 
+	/**
+	 * Constructs new Block using passed transaction and minimal AT state info.
+	 * <p>
+	 * This constructor typically used when receiving a serialized block over the network.
+	 *
+	 * @param repository
+	 * @param blockData
+	 * @param transactions
+	 * @param atStatesHash
+	 */
+	public Block(Repository repository, BlockData blockData, List<TransactionData> transactions, byte[] atStatesHash) {
+		this(repository, blockData);
+
+		this.transactions = new ArrayList<>();
+
+		long totalFees = 0;
+
+		// We have to sum fees too
+		for (TransactionData transactionData : transactions) {
+			this.transactions.add(Transaction.fromData(repository, transactionData));
+			totalFees += transactionData.getFee();
+		}
+
+		this.atStatesHash = atStatesHash;
+		totalFees += this.blockData.getATFees();
+
+		this.blockData.setTotalFees(totalFees);
+	}
+
 	/**
 	 * Constructs new Block with empty transaction list, using passed minter account.
 	 * 
@@ -313,18 +353,21 @@ public class Block {
 		int version = parentBlock.getNextBlockVersion();
 		byte[] reference = parentBlockData.getSignature();
 
-		// Fetch our list of online accounts
-		List<OnlineAccountData> onlineAccounts = OnlineAccountsManager.getInstance().getOnlineAccounts();
-		if (onlineAccounts.isEmpty()) {
-			LOGGER.error("No online accounts - not even our own?");
+		// Qortal: minter is always a reward-share, so find actual minter and get their effective minting level
+		int minterLevel = Account.getRewardShareEffectiveMintingLevel(repository, minter.getPublicKey());
+		if (minterLevel == 0) {
+			LOGGER.error("Minter effective level returned zero?");
 			return null;
 		}
 
-		// Find newest online accounts timestamp
-		long onlineAccountsTimestamp = 0;
-		for (OnlineAccountData onlineAccountData : onlineAccounts) {
-			if (onlineAccountData.getTimestamp() > onlineAccountsTimestamp)
-				onlineAccountsTimestamp = onlineAccountData.getTimestamp();
+		long timestamp = calcTimestamp(parentBlockData, minter.getPublicKey(), minterLevel);
+		long onlineAccountsTimestamp = OnlineAccountsManager.getCurrentOnlineAccountTimestamp();
+
+		// Fetch our list of online accounts
+		List<OnlineAccountData> onlineAccounts = OnlineAccountsManager.getInstance().getOnlineAccounts(onlineAccountsTimestamp);
+		if (onlineAccounts.isEmpty()) {
+			LOGGER.error("No online accounts - not even our own?");
+			return null;
 		}
 
 		// Load sorted list of reward share public keys into memory, so that the indexes can be obtained.
@@ -335,10 +378,6 @@ public class Block {
 		// Map using index into sorted list of reward-shares as key
 		Map<Integer, OnlineAccountData> indexedOnlineAccounts = new HashMap<>();
 		for (OnlineAccountData onlineAccountData : onlineAccounts) {
-			// Disregard online accounts with different timestamps
-			if (onlineAccountData.getTimestamp() != onlineAccountsTimestamp)
-				continue;
-
 			Integer accountIndex = getRewardShareIndex(onlineAccountData.getPublicKey(), allRewardSharePublicKeys);
 			if (accountIndex == null)
 				// Online account (reward-share) with current timestamp but reward-share cancelled
@@ -355,26 +394,29 @@ public class Block {
 		byte[] encodedOnlineAccounts = BlockTransformer.encodeOnlineAccounts(onlineAccountsSet);
 		int onlineAccountsCount = onlineAccountsSet.size();
 
-		// Concatenate online account timestamp signatures (in correct order)
-		byte[] onlineAccountsSignatures = new byte[onlineAccountsCount * Transformer.SIGNATURE_LENGTH];
-		for (int i = 0; i < onlineAccountsCount; ++i) {
-			Integer accountIndex = accountIndexes.get(i);
-			OnlineAccountData onlineAccountData = indexedOnlineAccounts.get(accountIndex);
-			System.arraycopy(onlineAccountData.getSignature(), 0, onlineAccountsSignatures, i * Transformer.SIGNATURE_LENGTH, Transformer.SIGNATURE_LENGTH);
+		byte[] onlineAccountsSignatures;
+		if (timestamp >= BlockChain.getInstance().getAggregateSignatureTimestamp()) {
+			// Collate all signatures
+			Collection<byte[]> signaturesToAggregate = indexedOnlineAccounts.values()
+					.stream()
+					.map(OnlineAccountData::getSignature)
+					.collect(Collectors.toList());
+
+			// Aggregated, single signature
+			onlineAccountsSignatures = Qortal25519Extras.aggregateSignatures(signaturesToAggregate);
+		} else {
+			// Concatenate online account timestamp signatures (in correct order)
+			onlineAccountsSignatures = new byte[onlineAccountsCount * Transformer.SIGNATURE_LENGTH];
+			for (int i = 0; i < onlineAccountsCount; ++i) {
+				Integer accountIndex = accountIndexes.get(i);
+				OnlineAccountData onlineAccountData = indexedOnlineAccounts.get(accountIndex);
+				System.arraycopy(onlineAccountData.getSignature(), 0, onlineAccountsSignatures, i * Transformer.SIGNATURE_LENGTH, Transformer.SIGNATURE_LENGTH);
+			}
 		}
 
 		byte[] minterSignature = minter.sign(BlockTransformer.getBytesForMinterSignature(parentBlockData,
 				minter.getPublicKey(), encodedOnlineAccounts));
 
-		// Qortal: minter is always a reward-share, so find actual minter and get their effective minting level
-		int minterLevel = Account.getRewardShareEffectiveMintingLevel(repository, minter.getPublicKey());
-		if (minterLevel == 0) {
-			LOGGER.error("Minter effective level returned zero?");
-			return null;
-		}
-
-		long timestamp = calcTimestamp(parentBlockData, minter.getPublicKey(), minterLevel);
-
 		int transactionCount = 0;
 		byte[] transactionsSignature = null;
 		int height = parentBlockData.getHeight() + 1;
@@ -979,49 +1021,59 @@ public class Block {
 		if (this.blockData.getOnlineAccountsSignatures() == null || this.blockData.getOnlineAccountsSignatures().length == 0)
 			return ValidationResult.ONLINE_ACCOUNT_SIGNATURES_MISSING;
 
-		if (this.blockData.getOnlineAccountsSignatures().length != onlineRewardShares.size() * Transformer.SIGNATURE_LENGTH)
-			return ValidationResult.ONLINE_ACCOUNT_SIGNATURES_MALFORMED;
+		if (this.blockData.getTimestamp() >= BlockChain.getInstance().getAggregateSignatureTimestamp()) {
+			// We expect just the one, aggregated signature
+			if (this.blockData.getOnlineAccountsSignatures().length != Transformer.SIGNATURE_LENGTH)
+				return ValidationResult.ONLINE_ACCOUNT_SIGNATURES_MALFORMED;
+		} else {
+			if (this.blockData.getOnlineAccountsSignatures().length != onlineRewardShares.size() * Transformer.SIGNATURE_LENGTH)
+				return ValidationResult.ONLINE_ACCOUNT_SIGNATURES_MALFORMED;
+		}
 
 		// Check signatures
 		long onlineTimestamp = this.blockData.getOnlineAccountsTimestamp();
 		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() - OnlineAccountsManager.ONLINE_TIMESTAMP_MODULUS
-				? null
-				: OnlineAccountsManager.getInstance().getOnlineAccounts();
-		List<OnlineAccountData> latestBlocksOnlineAccounts = OnlineAccountsManager.getInstance().getLatestBlocksOnlineAccounts();
-
-		// Extract online accounts' timestamp signatures from block data
+		// Extract online accounts' timestamp signatures from block data. Only one signature if aggregated.
 		List<byte[]> onlineAccountsSignatures = BlockTransformer.decodeTimestampSignatures(this.blockData.getOnlineAccountsSignatures());
 
-		// We'll build up a list of online accounts to hand over to Controller if block is added to chain
-		// and this will become latestBlocksOnlineAccounts (above) to reduce CPU load when we process next block...
-		List<OnlineAccountData> ourOnlineAccounts = new ArrayList<>();
+		if (this.blockData.getTimestamp() >= BlockChain.getInstance().getAggregateSignatureTimestamp()) {
+			// Aggregate all public keys
+			Collection<byte[]> publicKeys = onlineRewardShares.stream()
+					.map(RewardShareData::getRewardSharePublicKey)
+					.collect(Collectors.toList());
 
-		for (int i = 0; i < onlineAccountsSignatures.size(); ++i) {
-			byte[] signature = onlineAccountsSignatures.get(i);
-			byte[] publicKey = onlineRewardShares.get(i).getRewardSharePublicKey();
+			byte[] aggregatePublicKey = Qortal25519Extras.aggregatePublicKeys(publicKeys);
 
-			OnlineAccountData onlineAccountData = new OnlineAccountData(onlineTimestamp, signature, publicKey);
-			ourOnlineAccounts.add(onlineAccountData);
+			byte[] aggregateSignature = onlineAccountsSignatures.get(0);
 
-			// If signature is still current then no need to perform Ed25519 verify
-			if (currentOnlineAccounts != null && currentOnlineAccounts.remove(onlineAccountData))
-				// remove() returned true, so online account still current
-				// and one less entry in currentOnlineAccounts to check next time
-				continue;
-
-			// If signature was okay in latest block then no need to perform Ed25519 verify
-			if (latestBlocksOnlineAccounts != null && latestBlocksOnlineAccounts.contains(onlineAccountData))
-				continue;
-
-			if (!Crypto.verify(publicKey, signature, onlineTimestampBytes))
+			// One-step verification of aggregate signature using aggregate public key
+			if (!Qortal25519Extras.verifyAggregated(aggregatePublicKey, aggregateSignature, onlineTimestampBytes))
 				return ValidationResult.ONLINE_ACCOUNT_SIGNATURE_INCORRECT;
+		} else {
+			// Build block's view of online accounts
+			Set<OnlineAccountData> onlineAccounts = new HashSet<>();
+			for (int i = 0; i < onlineAccountsSignatures.size(); ++i) {
+				byte[] signature = onlineAccountsSignatures.get(i);
+				byte[] publicKey = onlineRewardShares.get(i).getRewardSharePublicKey();
+
+				OnlineAccountData onlineAccountData = new OnlineAccountData(onlineTimestamp, signature, publicKey);
+				onlineAccounts.add(onlineAccountData);
+			}
+
+			// Remove those already validated & cached by online accounts manager - no need to re-validate them
+			OnlineAccountsManager.getInstance().removeKnown(onlineAccounts, onlineTimestamp);
+
+			// Validate the rest
+			for (OnlineAccountData onlineAccount : onlineAccounts)
+				if (!Crypto.verify(onlineAccount.getPublicKey(), onlineAccount.getSignature(), onlineTimestampBytes))
+					return ValidationResult.ONLINE_ACCOUNT_SIGNATURE_INCORRECT;
+
+			// We've validated these, so allow online accounts manager to cache
+			OnlineAccountsManager.getInstance().addBlocksOnlineAccounts(onlineAccounts, onlineTimestamp);
 		}
 
 		// All online accounts valid, so save our list of online accounts for potential later use
-		this.cachedValidOnlineAccounts = ourOnlineAccounts;
 		this.cachedOnlineRewardShares = onlineRewardShares;
 
 		return ValidationResult.OK;
@@ -1194,7 +1246,7 @@ public class Block {
 	 */
 	private ValidationResult areAtsValid() throws DataException {
 		// Locally generated AT states should be valid so no need to re-execute them
-		if (this.ourAtStates == this.getATStates()) // Note object reference compare
+		if (this.ourAtStates != null && this.ourAtStates == this.atStates) // Note object reference compare
 			return ValidationResult.OK;
 
 		// Generate local AT states for comparison
@@ -1208,8 +1260,33 @@ public class Block {
 		if (this.ourAtFees != this.blockData.getATFees())
 			return ValidationResult.AT_STATES_MISMATCH;
 
-		// Note: this.atStates fully loaded thanks to this.getATStates() call above
-		for (int s = 0; s < this.atStates.size(); ++s) {
+		// If we have a single AT states hash then compare that in preference
+		if (this.atStatesHash != null) {
+			int atBytesLength = blockData.getATCount() * BlockTransformer.AT_ENTRY_LENGTH;
+			ByteArrayOutputStream atHashBytes = new ByteArrayOutputStream(atBytesLength);
+
+			try {
+				for (ATStateData atStateData : this.ourAtStates) {
+					atHashBytes.write(atStateData.getATAddress().getBytes(StandardCharsets.UTF_8));
+					atHashBytes.write(atStateData.getStateHash());
+					atHashBytes.write(Longs.toByteArray(atStateData.getFees()));
+				}
+			} catch (IOException e) {
+				throw new DataException("Couldn't validate AT states hash due to serialization issue?", e);
+			}
+
+			byte[] ourAtStatesHash = Crypto.digest(atHashBytes.toByteArray());
+			if (!Arrays.equals(ourAtStatesHash, this.atStatesHash))
+				return ValidationResult.AT_STATES_MISMATCH;
+
+			// Use our AT state data from now on
+			this.atStates = this.ourAtStates;
+			return ValidationResult.OK;
+		}
+
+		// Note: this.atStates fully loaded thanks to this.getATStates() call:
+		this.getATStates();
+		for (int s = 0; s < this.ourAtStates.size(); ++s) {
 			ATStateData ourAtState = this.ourAtStates.get(s);
 			ATStateData theirAtState = this.atStates.get(s);
 
@@ -1367,9 +1444,6 @@ public class Block {
 
 		postBlockTidy();
 
-		// Give Controller our cached, valid online accounts data (if any) to help reduce CPU load for next block
-		OnlineAccountsManager.getInstance().pushLatestBlocksOnlineAccounts(this.cachedValidOnlineAccounts);
-
 		// Log some debugging info relating to the block weight calculation
 		this.logDebugInfo();
 	}
@@ -1585,9 +1659,6 @@ public class Block {
 		this.blockData.setHeight(null);
 
 		postBlockTidy();
-
-		// Remove any cached, valid online accounts data from Controller
-		OnlineAccountsManager.getInstance().popLatestBlocksOnlineAccounts();
 	}
 
 	protected void orphanTransactionsFromBlock() throws DataException {
@@ -1825,12 +1896,67 @@ public class Block {
 		final boolean haveFounders = !onlineFounderAccounts.isEmpty();
 
 		// Determine reward candidates based on account level
-		List<AccountLevelShareBin> accountLevelShareBins = BlockChain.getInstance().getAccountLevelShareBins();
-		for (int binIndex = 0; binIndex < accountLevelShareBins.size(); ++binIndex) {
-			// Find all accounts in share bin. getShareBin() returns null for minter accounts that are also founders, so they are effectively filtered out.
+		// This needs a deep copy, so the shares can be modified when tiers aren't activated yet
+		List<AccountLevelShareBin> accountLevelShareBins = new ArrayList<>();
+		for (AccountLevelShareBin accountLevelShareBin : BlockChain.getInstance().getAccountLevelShareBins()) {
+			accountLevelShareBins.add((AccountLevelShareBin) accountLevelShareBin.clone());
+		}
+
+		Map<Integer, List<ExpandedAccount>> accountsForShareBin = new HashMap<>();
+
+		// We might need to combine some share bins if they haven't reached the minimum number of minters yet
+		for (int binIndex = accountLevelShareBins.size()-1; binIndex >= 0; --binIndex) {
 			AccountLevelShareBin accountLevelShareBin = accountLevelShareBins.get(binIndex);
-			// Object reference compare is OK as all references are read-only from blockchain config.
-			List<ExpandedAccount> binnedAccounts = expandedAccounts.stream().filter(accountInfo -> accountInfo.getShareBin(this.blockData.getHeight()) == accountLevelShareBin).collect(Collectors.toList());
+
+			// Find all accounts in share bin. getShareBin() returns null for minter accounts that are also founders, so they are effectively filtered out.
+			List<ExpandedAccount> binnedAccounts = expandedAccounts.stream().filter(accountInfo -> accountInfo.hasShareBin(accountLevelShareBin, this.blockData.getHeight())).collect(Collectors.toList());
+			// Add any accounts that have been moved down from a higher tier
+			List<ExpandedAccount> existingBinnedAccounts = accountsForShareBin.get(binIndex);
+			if (existingBinnedAccounts != null)
+				binnedAccounts.addAll(existingBinnedAccounts);
+
+			// Logic below may only apply to higher levels, and only for share bins with a specific range of online accounts
+			if (accountLevelShareBin.levels.get(0) < BlockChain.getInstance().getShareBinActivationMinLevel() ||
+					binnedAccounts.isEmpty() || binnedAccounts.size() >= BlockChain.getInstance().getMinAccountsToActivateShareBin()) {
+				// Add all accounts for this share bin to the accountsForShareBin list
+				accountsForShareBin.put(binIndex, binnedAccounts);
+				continue;
+			}
+
+			// Share bin contains more than one, but less than the minimum number of minters. We treat this share bin
+			// as not activated yet. In these cases, the rewards and minters are combined and paid out to the previous
+			// share bin, to prevent a single or handful of accounts receiving the entire rewards for a share bin.
+			//
+			// Example:
+			//
+			// - Share bin for levels 5 and 6 has 100 minters
+			// - Share bin for levels 7 and 8 has 10 minters
+			//
+			// This is below the minimum of 30, so share bins are reconstructed as follows:
+			//
+			// - Share bin for levels 5 and 6 now contains 110 minters
+			// - Share bin for levels 7 and 8 now contains 0 minters
+			// - Share bin for levels 5 and 6 now pays out rewards for levels 5, 6, 7, and 8
+			// - Share bin for levels 7 and 8 pays zero rewards
+			//
+			// This process is iterative, so will combine several tiers if needed.
+
+			// Designate this share bin as empty
+			accountsForShareBin.put(binIndex, new ArrayList<>());
+
+			// Move the accounts originally intended for this share bin to the previous one
+			accountsForShareBin.put(binIndex - 1, binnedAccounts);
+
+			// Move the block reward from this share bin to the previous one
+			AccountLevelShareBin previousShareBin = accountLevelShareBins.get(binIndex - 1);
+			previousShareBin.share += accountLevelShareBin.share;
+			accountLevelShareBin.share = 0L;
+		}
+
+		// Now loop through (potentially modified) share bins and determine the reward candidates
+		for (int binIndex = 0; binIndex < accountLevelShareBins.size(); ++binIndex) {
+			AccountLevelShareBin accountLevelShareBin = accountLevelShareBins.get(binIndex);
+			List<ExpandedAccount> binnedAccounts = accountsForShareBin.get(binIndex);
 
 			// No online accounts in this bin? Skip to next one
 			if (binnedAccounts.isEmpty())

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

@@ -68,8 +68,12 @@ public class BlockChain {
 		atFindNextTransactionFix,
 		newBlockSigHeight,
 		shareBinFix,
+		rewardShareLimitTimestamp,
 		calcChainWeightTimestamp,
-		transactionV5Timestamp;
+		transactionV5Timestamp,
+		transactionV6Timestamp,
+		disableReferenceTimestamp,
+		aggregateSignatureTimestamp;
 	}
 
 	// Custom transaction fees
@@ -100,10 +104,23 @@ public class BlockChain {
 	private List<RewardByHeight> rewardsByHeight;
 
 	/** Share of block reward/fees by account level */
-	public static class AccountLevelShareBin {
+	public static class AccountLevelShareBin implements Cloneable {
+		public int id;
 		public List<Integer> levels;
 		@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
 		public long share;
+
+		public Object clone() {
+			AccountLevelShareBin shareBinCopy = new AccountLevelShareBin();
+			List<Integer> levelsCopy = new ArrayList<>();
+			for (Integer level : this.levels) {
+				levelsCopy.add(level);
+			}
+			shareBinCopy.id = this.id;
+			shareBinCopy.levels = levelsCopy;
+			shareBinCopy.share = this.share;
+			return shareBinCopy;
+		}
 	}
 	private List<AccountLevelShareBin> sharesByLevel;
 	/** Generated lookup of share-bin by account level */
@@ -117,6 +134,12 @@ public class BlockChain {
 	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
 	private Long qoraPerQortReward;
 
+	/** Minimum number of accounts before a share bin is considered activated */
+	private int minAccountsToActivateShareBin;
+
+	/** Min level at which share bin activation takes place; lower levels allow less than minAccountsPerShareBin */
+	private int shareBinActivationMinLevel;
+
 	/**
 	 * Number of minted blocks required to reach next level from previous.
 	 * <p>
@@ -154,7 +177,7 @@ public class BlockChain {
 	private int minAccountLevelToMint;
 	private int minAccountLevelForBlockSubmissions;
 	private int minAccountLevelToRewardShare;
-	private int maxRewardSharesPerMintingAccount;
+	private int maxRewardSharesPerFounderMintingAccount;
 	private int founderEffectiveMintingLevel;
 
 	/** Minimum time to retain online account signatures (ms) for block validity checks. */
@@ -162,6 +185,13 @@ public class BlockChain {
 	/** Maximum time to retain online account signatures (ms) for block validity checks, to allow for clock variance. */
 	private long onlineAccountSignaturesMaxLifetime;
 
+	/** Max reward shares by block height */
+	public static class MaxRewardSharesByTimestamp {
+		public long timestamp;
+		public int maxShares;
+	}
+	private List<MaxRewardSharesByTimestamp> maxRewardSharesByTimestamp;
+
 	/** Settings relating to CIYAM AT feature. */
 	public static class CiyamAtSettings {
 		/** Fee per step/op-code executed. */
@@ -351,6 +381,14 @@ public class BlockChain {
 		return this.qoraPerQortReward;
 	}
 
+	public int getMinAccountsToActivateShareBin() {
+		return this.minAccountsToActivateShareBin;
+	}
+
+	public int getShareBinActivationMinLevel() {
+		return this.shareBinActivationMinLevel;
+	}
+
 	public int getMinAccountLevelToMint() {
 		return this.minAccountLevelToMint;
 	}
@@ -363,8 +401,8 @@ public class BlockChain {
 		return this.minAccountLevelToRewardShare;
 	}
 
-	public int getMaxRewardSharesPerMintingAccount() {
-		return this.maxRewardSharesPerMintingAccount;
+	public int getMaxRewardSharesPerFounderMintingAccount() {
+		return this.maxRewardSharesPerFounderMintingAccount;
 	}
 
 	public int getFounderEffectiveMintingLevel() {
@@ -397,6 +435,10 @@ public class BlockChain {
 		return this.featureTriggers.get(FeatureTrigger.shareBinFix.name()).intValue();
 	}
 
+	public long getRewardShareLimitTimestamp() {
+		return this.featureTriggers.get(FeatureTrigger.rewardShareLimitTimestamp.name()).longValue();
+	}
+
 	public long getCalcChainWeightTimestamp() {
 		return this.featureTriggers.get(FeatureTrigger.calcChainWeightTimestamp.name()).longValue();
 	}
@@ -405,6 +447,18 @@ public class BlockChain {
 		return this.featureTriggers.get(FeatureTrigger.transactionV5Timestamp.name()).longValue();
 	}
 
+	public long getTransactionV6Timestamp() {
+		return this.featureTriggers.get(FeatureTrigger.transactionV6Timestamp.name()).longValue();
+	}
+
+	public long getDisableReferenceTimestamp() {
+		return this.featureTriggers.get(FeatureTrigger.disableReferenceTimestamp.name()).longValue();
+	}
+
+	public long getAggregateSignatureTimestamp() {
+		return this.featureTriggers.get(FeatureTrigger.aggregateSignatureTimestamp.name()).longValue();
+	}
+
 	// More complex getters for aspects that change by height or timestamp
 
 	public long getRewardAtHeight(int ourHeight) {
@@ -425,15 +479,22 @@ public class BlockChain {
 	}
 
 	public long getNameRegistrationUnitFeeAtTimestamp(long ourTimestamp) {
-		// Scan through for reward at our height
-		for (int i = 0; i < nameRegistrationUnitFees.size(); ++i)
-			if (ourTimestamp >= nameRegistrationUnitFees.get(i).timestamp)
+		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();
 	}
 
+	public int getMaxRewardSharesAtTimestamp(long ourTimestamp) {
+		for (int i = maxRewardSharesByTimestamp.size() - 1; i >= 0; --i)
+			if (maxRewardSharesByTimestamp.get(i).timestamp <= ourTimestamp)
+				return maxRewardSharesByTimestamp.get(i).maxShares;
+
+		return 0;
+	}
+
 	/** Validate blockchain config read from JSON */
 	private void validateConfig() {
 		if (this.genesisInfo == null)

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

@@ -15,6 +15,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.concurrent.TimeoutException;
+import java.util.stream.Collectors;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -40,6 +41,7 @@ public class AutoUpdate extends Thread {
 
 	public static final String JAR_FILENAME = "qortal.jar";
 	public static final String NEW_JAR_FILENAME = "new-" + JAR_FILENAME;
+	public static final String AGENTLIB_JVM_HOLDER_ARG = "-DQORTAL_agentlib=";
 
 	private static final Logger LOGGER = LogManager.getLogger(AutoUpdate.class);
 	private static final long CHECK_INTERVAL = 20 * 60 * 1000L; // ms
@@ -243,6 +245,11 @@ public class AutoUpdate extends Thread {
 			// JVM arguments
 			javaCmd.addAll(ManagementFactory.getRuntimeMXBean().getInputArguments());
 
+			// Disable, but retain, any -agentlib JVM arg as sub-process might fail if it tries to reuse same port
+			javaCmd = javaCmd.stream()
+					.map(arg -> arg.replace("-agentlib", AGENTLIB_JVM_HOLDER_ARG))
+					.collect(Collectors.toList());
+
 			// Remove JNI options as they won't be supported by command-line 'java'
 			// These are typically added by the AdvancedInstaller Java launcher EXE
 			javaCmd.removeAll(Arrays.asList("abort", "exit", "vfprintf"));
@@ -261,10 +268,19 @@ public class AutoUpdate extends Thread {
 					Translator.INSTANCE.translate("SysTray", "APPLYING_UPDATE_AND_RESTARTING"),
 					MessageType.INFO);
 
-			new ProcessBuilder(javaCmd).start();
+			ProcessBuilder processBuilder = new ProcessBuilder(javaCmd);
+
+			// New process will inherit our stdout and stderr
+			processBuilder.redirectOutput(ProcessBuilder.Redirect.INHERIT);
+			processBuilder.redirectError(ProcessBuilder.Redirect.INHERIT);
+
+			Process process = processBuilder.start();
+
+			// Nothing to pipe to new process, so close output stream (process's stdin)
+			process.getOutputStream().close();
 
 			return true; // applying update OK
-		} catch (IOException e) {
+		} catch (Exception e) {
 			LOGGER.error(String.format("Failed to apply update: %s", e.getMessage()));
 
 			try {

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

@@ -61,8 +61,12 @@ public class BlockMinter extends Thread {
 	public void run() {
 		Thread.currentThread().setName("BlockMinter");
 
-		try (final Repository repository = RepositoryManager.getRepository()) {
-			if (Settings.getInstance().getWipeUnconfirmedOnStart()) {
+		if (Settings.getInstance().isLite()) {
+			// Lite nodes do not mint
+			return;
+		}
+		if (Settings.getInstance().getWipeUnconfirmedOnStart()) {
+			try (final Repository repository = RepositoryManager.getRepository()) {
 				// Wipe existing unconfirmed transactions
 				List<TransactionData> unconfirmedTransactions = repository.getTransactionRepository().getUnconfirmedTransactions();
 
@@ -72,30 +76,31 @@ public class BlockMinter extends Thread {
 				}
 
 				repository.saveChanges();
+			} catch (DataException e) {
+				LOGGER.warn("Repository issue trying to wipe unconfirmed transactions on start-up: {}", e.getMessage());
+				// Fall-through to normal behaviour in case we can recover
 			}
+		}
 
-			// Going to need this a lot...
-			BlockRepository blockRepository = repository.getBlockRepository();
-			BlockData previousBlockData = null;
+		BlockData previousBlockData = null;
 
-			// Vars to keep track of blocks that were skipped due to chain weight
-			byte[] parentSignatureForLastLowWeightBlock = null;
-			Long timeOfLastLowWeightBlock = null;
+		// Vars to keep track of blocks that were skipped due to chain weight
+		byte[] parentSignatureForLastLowWeightBlock = null;
+		Long timeOfLastLowWeightBlock = null;
 
-			List<Block> newBlocks = new ArrayList<>();
+		List<Block> newBlocks = new ArrayList<>();
 
-			// Flags for tracking change in whether minting is possible,
-			// so we can notify Controller, and further update SysTray, etc.
-			boolean isMintingPossible = false;
-			boolean wasMintingPossible = isMintingPossible;
-			while (running) {
-				repository.discardChanges(); // Free repository locks, if any
+		// Flags for tracking change in whether minting is possible,
+		// so we can notify Controller, and further update SysTray, etc.
+		boolean isMintingPossible = false;
+		boolean wasMintingPossible = isMintingPossible;
+		while (running) {
+			if (isMintingPossible != wasMintingPossible)
+				Controller.getInstance().onMintingPossibleChange(isMintingPossible);
 
-				if (isMintingPossible != wasMintingPossible)
-					Controller.getInstance().onMintingPossibleChange(isMintingPossible);
-
-				wasMintingPossible = isMintingPossible;
+			wasMintingPossible = isMintingPossible;
 
+			try {
 				// Sleep for a while
 				Thread.sleep(1000);
 
@@ -109,319 +114,338 @@ public class BlockMinter extends Thread {
 				if (minLatestBlockTimestamp == null)
 					continue;
 
-				// No online accounts? (e.g. during startup)
-				if (OnlineAccountsManager.getInstance().getOnlineAccounts().isEmpty())
+				// No online accounts for current timestamp? (e.g. during startup)
+				if (!OnlineAccountsManager.getInstance().hasOnlineAccounts())
 					continue;
 
-				List<MintingAccountData> mintingAccountsData = repository.getAccountRepository().getMintingAccounts();
-				// No minting accounts?
-				if (mintingAccountsData.isEmpty())
-					continue;
+				try (final Repository repository = RepositoryManager.getRepository()) {
+					// Going to need this a lot...
+					BlockRepository blockRepository = repository.getBlockRepository();
 
-				// Disregard minting accounts that are no longer valid, e.g. by transfer/loss of founder flag or account level
-				// Note that minting accounts are actually reward-shares in Qortal
-				Iterator<MintingAccountData> madi = mintingAccountsData.iterator();
-				while (madi.hasNext()) {
-					MintingAccountData mintingAccountData = madi.next();
-
-					RewardShareData rewardShareData = repository.getAccountRepository().getRewardShare(mintingAccountData.getPublicKey());
-					if (rewardShareData == null) {
-						// Reward-share doesn't exist - probably cancelled but not yet removed from node's list of minting accounts
-						madi.remove();
-						continue;
-					}
-
-					Account mintingAccount = new Account(repository, rewardShareData.getMinter());
-					if (!mintingAccount.canMint()) {
-						// Minting-account component of reward-share can no longer mint - disregard
-						madi.remove();
-						continue;
-					}
-
-					// Optional (non-validated) prevention of block submissions below a defined level.
-					// This is an unvalidated version of Blockchain.minAccountLevelToMint
-					// and exists only to reduce block candidates by default.
-					int level = mintingAccount.getEffectiveMintingLevel();
-					if (level < BlockChain.getInstance().getMinAccountLevelForBlockSubmissions()) {
-						madi.remove();
-						continue;
-					}
-				}
-
-				// 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
-				peers.removeIf(Controller.hasMisbehaved);
-
-				// Disregard peers that don't have a recent block, but only if we're not in recovery mode.
-				// In that mode, we want to allow minting on top of older blocks, to recover stalled networks.
-				if (Synchronizer.getInstance().getRecoveryMode() == false)
-					peers.removeIf(Controller.hasNoRecentBlock);
-
-				// Don't mint if we don't have enough up-to-date peers as where would the transactions/consensus come from?
-				if (peers.size() < Settings.getInstance().getMinBlockchainPeers())
-					continue;
-
-				// If we are stuck on an invalid block, we should allow an alternative to be minted
-				boolean recoverInvalidBlock = false;
-				if (Synchronizer.getInstance().timeInvalidBlockLastReceived != null) {
-					// We've had at least one invalid block
-					long timeSinceLastValidBlock = NTP.getTime() - Synchronizer.getInstance().timeValidBlockLastReceived;
-					long timeSinceLastInvalidBlock = NTP.getTime() - Synchronizer.getInstance().timeInvalidBlockLastReceived;
-					if (timeSinceLastValidBlock > INVALID_BLOCK_RECOVERY_TIMEOUT) {
-						if (timeSinceLastInvalidBlock < INVALID_BLOCK_RECOVERY_TIMEOUT) {
-							// Last valid block was more than 10 mins ago, but we've had an invalid block since then
-							// Assume that the chain has stalled because there is no alternative valid candidate
-							// Enter recovery mode to allow alternative, valid candidates to be minted
-							recoverInvalidBlock = true;
-						}
-					}
-				}
-
-				// If our latest block isn't recent then we need to synchronize instead of minting, unless we're in recovery mode.
-				if (!peers.isEmpty() && lastBlockData.getTimestamp() < minLatestBlockTimestamp)
-					if (Synchronizer.getInstance().getRecoveryMode() == false && recoverInvalidBlock == false)
+					List<MintingAccountData> mintingAccountsData = repository.getAccountRepository().getMintingAccounts();
+					// No minting accounts?
+					if (mintingAccountsData.isEmpty())
 						continue;
 
-				// There are enough peers with a recent block and our latest block is recent
-				// so go ahead and mint a block if possible.
-				isMintingPossible = true;
+					// Disregard minting accounts that are no longer valid, e.g. by transfer/loss of founder flag or account level
+					// Note that minting accounts are actually reward-shares in Qortal
+					Iterator<MintingAccountData> madi = mintingAccountsData.iterator();
+					while (madi.hasNext()) {
+						MintingAccountData mintingAccountData = madi.next();
 
-				// Check blockchain hasn't changed
-				if (previousBlockData == null || !Arrays.equals(previousBlockData.getSignature(), lastBlockData.getSignature())) {
-					previousBlockData = lastBlockData;
-					newBlocks.clear();
-
-					// Reduce log timeout
-					logTimeout = 10 * 1000L;
-
-					// Last low weight block is no longer valid
-					parentSignatureForLastLowWeightBlock = null;
-				}
-
-				// Discard accounts we have already built blocks with
-				mintingAccountsData.removeIf(mintingAccountData -> newBlocks.stream().anyMatch(newBlock -> Arrays.equals(newBlock.getBlockData().getMinterPublicKey(), mintingAccountData.getPublicKey())));
-
-				// Do we need to build any potential new blocks?
-				List<PrivateKeyAccount> newBlocksMintingAccounts = mintingAccountsData.stream().map(accountData -> new PrivateKeyAccount(repository, accountData.getPrivateKey())).collect(Collectors.toList());
-
-				// We might need to sit the next block out, if one of our minting accounts signed the previous one
-				final byte[] previousBlockMinter = previousBlockData.getMinterPublicKey();
-				final boolean mintedLastBlock = mintingAccountsData.stream().anyMatch(mintingAccount -> Arrays.equals(mintingAccount.getPublicKey(), previousBlockMinter));
-				if (mintedLastBlock) {
-					LOGGER.trace(String.format("One of our keys signed the last block, so we won't sign the next one"));
-					continue;
-				}
-
-				if (parentSignatureForLastLowWeightBlock != null) {
-					// 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...");
-					Thread.sleep(10 * 1000L);
-				}
-
-				for (PrivateKeyAccount mintingAccount : newBlocksMintingAccounts) {
-					// First block does the AT heavy-lifting
-					if (newBlocks.isEmpty()) {
-						Block newBlock = Block.mint(repository, previousBlockData, mintingAccount);
-						if (newBlock == null) {
-							// For some reason we can't mint right now
-							moderatedLog(() -> LOGGER.error("Couldn't build a to-be-minted block"));
+						RewardShareData rewardShareData = repository.getAccountRepository().getRewardShare(mintingAccountData.getPublicKey());
+						if (rewardShareData == null) {
+							// Reward-share doesn't exist - probably cancelled but not yet removed from node's list of minting accounts
+							madi.remove();
 							continue;
 						}
 
-						newBlocks.add(newBlock);
-					} else {
-						// The blocks for other minters require less effort...
-						Block newBlock = newBlocks.get(0).remint(mintingAccount);
-						if (newBlock == null) {
-							// For some reason we can't mint right now
-							moderatedLog(() -> LOGGER.error("Couldn't rebuild a to-be-minted block"));
+						Account mintingAccount = new Account(repository, rewardShareData.getMinter());
+						if (!mintingAccount.canMint()) {
+							// Minting-account component of reward-share can no longer mint - disregard
+							madi.remove();
 							continue;
 						}
 
-						newBlocks.add(newBlock);
+						// Optional (non-validated) prevention of block submissions below a defined level.
+						// This is an unvalidated version of Blockchain.minAccountLevelToMint
+						// and exists only to reduce block candidates by default.
+						int level = mintingAccount.getEffectiveMintingLevel();
+						if (level < BlockChain.getInstance().getMinAccountLevelForBlockSubmissions()) {
+							madi.remove();
+							continue;
+						}
 					}
-				}
 
-				// No potential block candidates?
-				if (newBlocks.isEmpty())
-					continue;
+					// Needs a mutable copy of the unmodifiableList
+					List<Peer> peers = new ArrayList<>(Network.getInstance().getImmutableHandshakedPeers());
+					BlockData lastBlockData = blockRepository.getLastBlock();
 
-				// Make sure we're the only thread modifying the blockchain
-				ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
-				if (!blockchainLock.tryLock(30, TimeUnit.SECONDS)) {
-					LOGGER.debug("Couldn't acquire blockchain lock even after waiting 30 seconds");
-					continue;
-				}
+					// Disregard peers that have "misbehaved" recently
+					peers.removeIf(Controller.hasMisbehaved);
 
-				boolean newBlockMinted = false;
-				Block newBlock = null;
+					// Disregard peers that don't have a recent block, but only if we're not in recovery mode.
+					// In that mode, we want to allow minting on top of older blocks, to recover stalled networks.
+					if (Synchronizer.getInstance().getRecoveryMode() == false)
+						peers.removeIf(Controller.hasNoRecentBlock);
 
-				try {
-					// Clear repository session state so we have latest view of data
-					repository.discardChanges();
-
-					// Now that we have blockchain lock, do final check that chain hasn't changed
-					BlockData latestBlockData = blockRepository.getLastBlock();
-					if (!Arrays.equals(lastBlockData.getSignature(), latestBlockData.getSignature()))
+					// Don't mint if we don't have enough up-to-date peers as where would the transactions/consensus come from?
+					if (peers.size() < Settings.getInstance().getMinBlockchainPeers())
 						continue;
 
-					List<Block> goodBlocks = new ArrayList<>();
-					for (Block testBlock : newBlocks) {
-						// Is new block's timestamp valid yet?
-						// We do a separate check as some timestamp checks are skipped for testchains
-						if (testBlock.isTimestampValid() != ValidationResult.OK)
-							continue;
-
-						testBlock.preProcess();
-
-						// Is new block valid yet? (Before adding unconfirmed transactions)
-						ValidationResult result = testBlock.isValid();
-						if (result != ValidationResult.OK) {
-							moderatedLog(() -> LOGGER.error(String.format("To-be-minted block invalid '%s' before adding transactions?", result.name())));
-
-							continue;
-						}
-
-						goodBlocks.add(testBlock);
-					}
-
-					if (goodBlocks.isEmpty())
-						continue;
-
-					// Pick best block
-					final int parentHeight = previousBlockData.getHeight();
-					final byte[] parentBlockSignature = previousBlockData.getSignature();
-
-					BigInteger bestWeight = null;
-
-					for (int bi = 0; bi < goodBlocks.size(); ++bi) {
-						BlockData blockData = goodBlocks.get(bi).getBlockData();
-
-						BlockSummaryData blockSummaryData = new BlockSummaryData(blockData);
-						int minterLevel = Account.getRewardShareEffectiveMintingLevel(repository, blockData.getMinterPublicKey());
-						blockSummaryData.setMinterLevel(minterLevel);
-
-						BigInteger blockWeight = Block.calcBlockWeight(parentHeight, parentBlockSignature, blockSummaryData);
-
-						if (bestWeight == null || blockWeight.compareTo(bestWeight) < 0) {
-							newBlock = goodBlocks.get(bi);
-							bestWeight = blockWeight;
-						}
-					}
-
-					try {
-						if (this.higherWeightChainExists(repository, bestWeight)) {
-
-							// Check if the base block has updated since the last time we were here
-							if (parentSignatureForLastLowWeightBlock == null || timeOfLastLowWeightBlock == null ||
-									!Arrays.equals(parentSignatureForLastLowWeightBlock, previousBlockData.getSignature())) {
-								// We've switched to a different chain, so reset the timer
-								timeOfLastLowWeightBlock = NTP.getTime();
+					// If we are stuck on an invalid block, we should allow an alternative to be minted
+					boolean recoverInvalidBlock = false;
+					if (Synchronizer.getInstance().timeInvalidBlockLastReceived != null) {
+						// We've had at least one invalid block
+						long timeSinceLastValidBlock = NTP.getTime() - Synchronizer.getInstance().timeValidBlockLastReceived;
+						long timeSinceLastInvalidBlock = NTP.getTime() - Synchronizer.getInstance().timeInvalidBlockLastReceived;
+						if (timeSinceLastValidBlock > INVALID_BLOCK_RECOVERY_TIMEOUT) {
+							if (timeSinceLastInvalidBlock < INVALID_BLOCK_RECOVERY_TIMEOUT) {
+								// Last valid block was more than 10 mins ago, but we've had an invalid block since then
+								// Assume that the chain has stalled because there is no alternative valid candidate
+								// Enter recovery mode to allow alternative, valid candidates to be minted
+								recoverInvalidBlock = true;
 							}
-							parentSignatureForLastLowWeightBlock = previousBlockData.getSignature();
+						}
+					}
 
-							// 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);
+					// If our latest block isn't recent then we need to synchronize instead of minting, unless we're in recovery mode.
+					if (!peers.isEmpty() && lastBlockData.getTimestamp() < minLatestBlockTimestamp)
+						if (Synchronizer.getInstance().getRecoveryMode() == false && recoverInvalidBlock == false)
+							continue;
+
+					// There are enough peers with a recent block and our latest block is recent
+					// so go ahead and mint a block if possible.
+					isMintingPossible = true;
+
+					// Reattach newBlocks to new repository handle
+					for (Block newBlock : newBlocks)
+						newBlock.setRepository(repository);
+
+					// Check blockchain hasn't changed
+					if (previousBlockData == null || !Arrays.equals(previousBlockData.getSignature(), lastBlockData.getSignature())) {
+						previousBlockData = lastBlockData;
+						newBlocks.clear();
+
+						// Reduce log timeout
+						logTimeout = 10 * 1000L;
+
+						// Last low weight block is no longer valid
+						parentSignatureForLastLowWeightBlock = null;
+					}
+
+					// Discard accounts we have already built blocks with
+					mintingAccountsData.removeIf(mintingAccountData -> newBlocks.stream().anyMatch(newBlock -> Arrays.equals(newBlock.getBlockData().getMinterPublicKey(), mintingAccountData.getPublicKey())));
+
+					// Do we need to build any potential new blocks?
+					List<PrivateKeyAccount> newBlocksMintingAccounts = mintingAccountsData.stream().map(accountData -> new PrivateKeyAccount(repository, accountData.getPrivateKey())).collect(Collectors.toList());
+
+					// We might need to sit the next block out, if one of our minting accounts signed the previous one
+					byte[] previousBlockMinter = previousBlockData.getMinterPublicKey();
+					boolean mintedLastBlock = mintingAccountsData.stream().anyMatch(mintingAccount -> Arrays.equals(mintingAccount.getPublicKey(), previousBlockMinter));
+					if (mintedLastBlock) {
+						LOGGER.trace(String.format("One of our keys signed the last block, so we won't sign the next one"));
+						continue;
+					}
+
+					if (parentSignatureForLastLowWeightBlock != null) {
+						// 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...");
+						Thread.sleep(10 * 1000L);
+					}
+
+					for (PrivateKeyAccount mintingAccount : newBlocksMintingAccounts) {
+						// First block does the AT heavy-lifting
+						if (newBlocks.isEmpty()) {
+							Block newBlock = Block.mint(repository, previousBlockData, mintingAccount);
+							if (newBlock == null) {
+								// For some reason we can't mint right now
+								moderatedLog(() -> LOGGER.error("Couldn't build a to-be-minted block"));
 								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...");
+
+							newBlocks.add(newBlock);
+						} else {
+							// The blocks for other minters require less effort...
+							Block newBlock = newBlocks.get(0).remint(mintingAccount);
+							if (newBlock == null) {
+								// For some reason we can't mint right now
+								moderatedLog(() -> LOGGER.error("Couldn't rebuild a to-be-minted block"));
+								continue;
 							}
+
+							newBlocks.add(newBlock);
 						}
-						else {
-							LOGGER.debug("No higher weight chain found in peers");
-						}
-					} catch (DataException e) {
-						LOGGER.debug("Unable to check for a higher weight chain. Proceeding anyway...");
 					}
 
-					// Discard any uncommitted changes as a result of the higher weight chain detection
-					repository.discardChanges();
+					// No potential block candidates?
+					if (newBlocks.isEmpty())
+						continue;
 
-					// Clear variables that track low weight blocks
-					parentSignatureForLastLowWeightBlock = null;
-					timeOfLastLowWeightBlock = null;
-
-
-					// Add unconfirmed transactions
-					addUnconfirmedTransactions(repository, newBlock);
-
-					// Sign to create block's signature
-					newBlock.sign();
-
-					// Is newBlock still valid?
-					ValidationResult validationResult = newBlock.isValid();
-					if (validationResult != ValidationResult.OK) {
-						// No longer valid? Report and discard
-						LOGGER.error(String.format("To-be-minted block now invalid '%s' after adding unconfirmed transactions?", validationResult.name()));
-
-						// Rebuild block candidates, just to be sure
-						newBlocks.clear();
+					// Make sure we're the only thread modifying the blockchain
+					ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
+					if (!blockchainLock.tryLock(30, TimeUnit.SECONDS)) {
+						LOGGER.debug("Couldn't acquire blockchain lock even after waiting 30 seconds");
 						continue;
 					}
 
-					// Add to blockchain - something else will notice and broadcast new block to network
+					boolean newBlockMinted = false;
+					Block newBlock = null;
+
 					try {
-						newBlock.process();
+						// Clear repository session state so we have latest view of data
+						repository.discardChanges();
 
-						repository.saveChanges();
+						// Now that we have blockchain lock, do final check that chain hasn't changed
+						BlockData latestBlockData = blockRepository.getLastBlock();
+						if (!Arrays.equals(lastBlockData.getSignature(), latestBlockData.getSignature()))
+							continue;
 
-						LOGGER.info(String.format("Minted new block: %d", newBlock.getBlockData().getHeight()));
+						List<Block> goodBlocks = new ArrayList<>();
+						boolean wasInvalidBlockDiscarded = false;
+						Iterator<Block> newBlocksIterator = newBlocks.iterator();
 
-						RewardShareData rewardShareData = repository.getAccountRepository().getRewardShare(newBlock.getBlockData().getMinterPublicKey());
+						while (newBlocksIterator.hasNext()) {
+							Block testBlock = newBlocksIterator.next();
 
-						if (rewardShareData != null) {
-							LOGGER.info(String.format("Minted block %d, sig %.8s, parent sig: %.8s by %s on behalf of %s",
-									newBlock.getBlockData().getHeight(),
-									Base58.encode(newBlock.getBlockData().getSignature()),
-									Base58.encode(newBlock.getParent().getSignature()),
-									rewardShareData.getMinter(),
-									rewardShareData.getRecipient()));
-						} else {
-							LOGGER.info(String.format("Minted block %d, sig %.8s, parent sig: %.8s by %s",
-									newBlock.getBlockData().getHeight(),
-									Base58.encode(newBlock.getBlockData().getSignature()),
-									Base58.encode(newBlock.getParent().getSignature()),
-									newBlock.getMinter().getAddress()));
+							// Is new block's timestamp valid yet?
+							// We do a separate check as some timestamp checks are skipped for testchains
+							if (testBlock.isTimestampValid() != ValidationResult.OK)
+								continue;
+
+							testBlock.preProcess();
+
+							// Is new block valid yet? (Before adding unconfirmed transactions)
+							ValidationResult result = testBlock.isValid();
+							if (result != ValidationResult.OK) {
+								moderatedLog(() -> LOGGER.error(String.format("To-be-minted block invalid '%s' before adding transactions?", result.name())));
+
+								newBlocksIterator.remove();
+								wasInvalidBlockDiscarded = true;
+								/*
+								 * Bail out fast so that we loop around from the top again.
+								 * This gives BlockMinter the possibility to remint this candidate block using another block from newBlocks,
+								 * via the Blocks.remint() method, which avoids having to re-process Block ATs all over again.
+								 * Particularly useful if some aspect of Blocks changes due a timestamp-based feature-trigger (see BlockChain class).
+								 */
+								break;
+							}
+
+							goodBlocks.add(testBlock);
 						}
 
-						// Notify network after we're released blockchain lock
-						newBlockMinted = true;
+						if (wasInvalidBlockDiscarded || goodBlocks.isEmpty())
+							continue;
 
-						// Notify Controller
-						repository.discardChanges(); // clear transaction status to prevent deadlocks
-						Controller.getInstance().onNewBlock(newBlock.getBlockData());
-					} catch (DataException e) {
-						// Unable to process block - report and discard
-						LOGGER.error("Unable to process newly minted block?", e);
-						newBlocks.clear();
+						// Pick best block
+						final int parentHeight = previousBlockData.getHeight();
+						final byte[] parentBlockSignature = previousBlockData.getSignature();
+
+						BigInteger bestWeight = null;
+
+						for (int bi = 0; bi < goodBlocks.size(); ++bi) {
+							BlockData blockData = goodBlocks.get(bi).getBlockData();
+
+							BlockSummaryData blockSummaryData = new BlockSummaryData(blockData);
+							int minterLevel = Account.getRewardShareEffectiveMintingLevel(repository, blockData.getMinterPublicKey());
+							blockSummaryData.setMinterLevel(minterLevel);
+
+							BigInteger blockWeight = Block.calcBlockWeight(parentHeight, parentBlockSignature, blockSummaryData);
+
+							if (bestWeight == null || blockWeight.compareTo(bestWeight) < 0) {
+								newBlock = goodBlocks.get(bi);
+								bestWeight = blockWeight;
+							}
+						}
+
+						try {
+							if (this.higherWeightChainExists(repository, bestWeight)) {
+
+								// Check if the base block has updated since the last time we were here
+								if (parentSignatureForLastLowWeightBlock == null || timeOfLastLowWeightBlock == null ||
+										!Arrays.equals(parentSignatureForLastLowWeightBlock, previousBlockData.getSignature())) {
+									// We've switched to a different chain, so reset the timer
+									timeOfLastLowWeightBlock = NTP.getTime();
+								}
+								parentSignatureForLastLowWeightBlock = previousBlockData.getSignature();
+
+								// 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);
+									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...");
+								}
+							} else {
+								LOGGER.debug("No higher weight chain found in peers");
+							}
+						} catch (DataException e) {
+							LOGGER.debug("Unable to check for a higher weight chain. Proceeding anyway...");
+						}
+
+						// Discard any uncommitted changes as a result of the higher weight chain detection
+						repository.discardChanges();
+
+						// Clear variables that track low weight blocks
+						parentSignatureForLastLowWeightBlock = null;
+						timeOfLastLowWeightBlock = null;
+
+						// Add unconfirmed transactions
+						addUnconfirmedTransactions(repository, newBlock);
+
+						// Sign to create block's signature
+						newBlock.sign();
+
+						// Is newBlock still valid?
+						ValidationResult validationResult = newBlock.isValid();
+						if (validationResult != ValidationResult.OK) {
+							// No longer valid? Report and discard
+							LOGGER.error(String.format("To-be-minted block now invalid '%s' after adding unconfirmed transactions?", validationResult.name()));
+
+							// Rebuild block candidates, just to be sure
+							newBlocks.clear();
+							continue;
+						}
+
+						// Add to blockchain - something else will notice and broadcast new block to network
+						try {
+							newBlock.process();
+
+							repository.saveChanges();
+
+							LOGGER.info(String.format("Minted new block: %d", newBlock.getBlockData().getHeight()));
+
+							RewardShareData rewardShareData = repository.getAccountRepository().getRewardShare(newBlock.getBlockData().getMinterPublicKey());
+
+							if (rewardShareData != null) {
+								LOGGER.info(String.format("Minted block %d, sig %.8s, parent sig: %.8s by %s on behalf of %s",
+										newBlock.getBlockData().getHeight(),
+										Base58.encode(newBlock.getBlockData().getSignature()),
+										Base58.encode(newBlock.getParent().getSignature()),
+										rewardShareData.getMinter(),
+										rewardShareData.getRecipient()));
+							} else {
+								LOGGER.info(String.format("Minted block %d, sig %.8s, parent sig: %.8s by %s",
+										newBlock.getBlockData().getHeight(),
+										Base58.encode(newBlock.getBlockData().getSignature()),
+										Base58.encode(newBlock.getParent().getSignature()),
+										newBlock.getMinter().getAddress()));
+							}
+
+							// Notify network after we're released blockchain lock
+							newBlockMinted = true;
+
+							// Notify Controller
+							repository.discardChanges(); // clear transaction status to prevent deadlocks
+							Controller.getInstance().onNewBlock(newBlock.getBlockData());
+						} catch (DataException e) {
+							// Unable to process block - report and discard
+							LOGGER.error("Unable to process newly minted block?", e);
+							newBlocks.clear();
+						}
+					} finally {
+						blockchainLock.unlock();
 					}
-				} finally {
-					blockchainLock.unlock();
-				}
 
-				if (newBlockMinted) {
-					// Broadcast our new chain to network
-					BlockData newBlockData = newBlock.getBlockData();
+					if (newBlockMinted) {
+						// Broadcast our new chain to network
+						BlockData newBlockData = newBlock.getBlockData();
 
-					Network network = Network.getInstance();
-					network.broadcast(broadcastPeer -> network.buildHeightMessage(broadcastPeer, newBlockData));
+						Network network = Network.getInstance();
+						network.broadcast(broadcastPeer -> network.buildHeightMessage(broadcastPeer, newBlockData));
+					}
+				} catch (DataException e) {
+					LOGGER.warn("Repository issue while running block minter", e);
 				}
+			} catch (InterruptedException e) {
+				// We've been interrupted - time to exit
+				return;
 			}
-		} catch (DataException e) {
-			LOGGER.warn("Repository issue while running block minter", e);
-		} catch (InterruptedException e) {
-			// We've been interrupted - time to exit
-			return;
 		}
 	}
 
@@ -552,18 +576,23 @@ public class BlockMinter extends Thread {
 				// This peer has common block data
 				CommonBlockData commonBlockData = peer.getCommonBlockData();
 				BlockSummaryData commonBlockSummaryData = commonBlockData.getCommonBlockSummary();
-				if (commonBlockData.getChainWeight() != null) {
+				if (commonBlockData.getChainWeight() != null && peer.getCommonBlockData().getBlockSummariesAfterCommonBlock() != null) {
 					// The synchronizer has calculated this peer's chain weight
-					BigInteger ourChainWeightSinceCommonBlock = this.getOurChainWeightSinceBlock(repository, commonBlockSummaryData, commonBlockData.getBlockSummariesAfterCommonBlock());
-					BigInteger ourChainWeight = ourChainWeightSinceCommonBlock.add(blockCandidateWeight);
-					BigInteger peerChainWeight = commonBlockData.getChainWeight();
-					if (peerChainWeight.compareTo(ourChainWeight) >= 0) {
-						// This peer has a higher weight chain than ours
-						LOGGER.debug("Peer {} is on a higher weight chain ({}) than ours ({})", peer, formatter.format(peerChainWeight), formatter.format(ourChainWeight));
-						return true;
+					if (!Synchronizer.getInstance().containsInvalidBlockSummary(peer.getCommonBlockData().getBlockSummariesAfterCommonBlock())) {
+						// .. and it doesn't hold any invalid blocks
+						BigInteger ourChainWeightSinceCommonBlock = this.getOurChainWeightSinceBlock(repository, commonBlockSummaryData, commonBlockData.getBlockSummariesAfterCommonBlock());
+						BigInteger ourChainWeight = ourChainWeightSinceCommonBlock.add(blockCandidateWeight);
+						BigInteger peerChainWeight = commonBlockData.getChainWeight();
+						if (peerChainWeight.compareTo(ourChainWeight) >= 0) {
+							// This peer has a higher weight chain than ours
+							LOGGER.info("Peer {} is on a higher weight chain ({}) than ours ({})", peer, formatter.format(peerChainWeight), formatter.format(ourChainWeight));
+							return true;
 
+						} else {
+							LOGGER.debug("Peer {} is on a lower weight chain ({}) than ours ({})", peer, formatter.format(peerChainWeight), formatter.format(ourChainWeight));
+						}
 					} else {
-						LOGGER.debug("Peer {} is on a lower weight chain ({}) than ours ({})", peer, formatter.format(peerChainWeight), formatter.format(ourChainWeight));
+						LOGGER.debug("Peer {} has an invalid block", peer);
 					}
 				} else {
 					LOGGER.debug("Peer {} has no chain weight", peer);

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

@@ -32,6 +32,7 @@ import org.bouncycastle.jsse.provider.BouncyCastleJsseProvider;
 import org.qortal.api.ApiService;
 import org.qortal.api.DomainMapService;
 import org.qortal.api.GatewayService;
+import org.qortal.api.resource.TransactionsResource;
 import org.qortal.block.Block;
 import org.qortal.block.BlockChain;
 import org.qortal.block.BlockChain.BlockTimingByHeight;
@@ -39,8 +40,11 @@ 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.AccountBalanceData;
+import org.qortal.data.account.AccountData;
 import org.qortal.data.block.BlockData;
 import org.qortal.data.block.BlockSummaryData;
+import org.qortal.data.naming.NameData;
 import org.qortal.data.network.PeerChainTipData;
 import org.qortal.data.network.PeerData;
 import org.qortal.data.transaction.ChatTransactionData;
@@ -58,6 +62,7 @@ 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.transform.TransformationException;
 import org.qortal.utils.*;
 
 public class Controller extends Thread {
@@ -108,6 +113,7 @@ public class Controller extends Thread {
 	private long repositoryBackupTimestamp = startTime; // ms
 	private long repositoryMaintenanceTimestamp = startTime; // ms
 	private long repositoryCheckpointTimestamp = startTime; // ms
+	private long prunePeersTimestamp = startTime; // ms
 	private long ntpCheckTimestamp = startTime; // ms
 	private long deleteExpiredTimestamp = startTime + DELETE_EXPIRED_INTERVAL; // ms
 
@@ -178,6 +184,52 @@ public class Controller extends Thread {
 		}
 		public GetArbitraryMetadataMessageStats getArbitraryMetadataMessageStats = new GetArbitraryMetadataMessageStats();
 
+		public static class GetAccountMessageStats {
+			public AtomicLong requests = new AtomicLong();
+			public AtomicLong cacheHits = new AtomicLong();
+			public AtomicLong unknownAccounts = new AtomicLong();
+
+			public GetAccountMessageStats() {
+			}
+		}
+		public GetAccountMessageStats getAccountMessageStats = new GetAccountMessageStats();
+
+		public static class GetAccountBalanceMessageStats {
+			public AtomicLong requests = new AtomicLong();
+			public AtomicLong unknownAccounts = new AtomicLong();
+
+			public GetAccountBalanceMessageStats() {
+			}
+		}
+		public GetAccountBalanceMessageStats getAccountBalanceMessageStats = new GetAccountBalanceMessageStats();
+
+		public static class GetAccountTransactionsMessageStats {
+			public AtomicLong requests = new AtomicLong();
+			public AtomicLong unknownAccounts = new AtomicLong();
+
+			public GetAccountTransactionsMessageStats() {
+			}
+		}
+		public GetAccountTransactionsMessageStats getAccountTransactionsMessageStats = new GetAccountTransactionsMessageStats();
+
+		public static class GetAccountNamesMessageStats {
+			public AtomicLong requests = new AtomicLong();
+			public AtomicLong unknownAccounts = new AtomicLong();
+
+			public GetAccountNamesMessageStats() {
+			}
+		}
+		public GetAccountNamesMessageStats getAccountNamesMessageStats = new GetAccountNamesMessageStats();
+
+		public static class GetNameMessageStats {
+			public AtomicLong requests = new AtomicLong();
+			public AtomicLong unknownAccounts = new AtomicLong();
+
+			public GetNameMessageStats() {
+			}
+		}
+		public GetNameMessageStats getNameMessageStats = new GetNameMessageStats();
+
 		public AtomicLong latestBlocksCacheRefills = new AtomicLong();
 
 		public StatsSnapshot() {
@@ -362,23 +414,27 @@ public class Controller extends Thread {
 			return; // Not System.exit() so that GUI can display error
 		}
 
-		// Rebuild Names table and check database integrity (if enabled)
-		NamesDatabaseIntegrityCheck namesDatabaseIntegrityCheck = new NamesDatabaseIntegrityCheck();
-		namesDatabaseIntegrityCheck.rebuildAllNames();
-		if (Settings.getInstance().isNamesIntegrityCheckEnabled()) {
-			namesDatabaseIntegrityCheck.runIntegrityCheck();
-		}
+		// If we have a non-lite node, we need to perform some startup actions
+		if (!Settings.getInstance().isLite()) {
 
-		LOGGER.info("Validating blockchain");
-		try {
-			BlockChain.validate();
+			// Rebuild Names table and check database integrity (if enabled)
+			NamesDatabaseIntegrityCheck namesDatabaseIntegrityCheck = new NamesDatabaseIntegrityCheck();
+			namesDatabaseIntegrityCheck.rebuildAllNames();
+			if (Settings.getInstance().isNamesIntegrityCheckEnabled()) {
+				namesDatabaseIntegrityCheck.runIntegrityCheck();
+			}
 
-			Controller.getInstance().refillLatestBlocksCache();
-			LOGGER.info(String.format("Our chain height at start-up: %d", Controller.getInstance().getChainHeight()));
-		} catch (DataException e) {
-			LOGGER.error("Couldn't validate blockchain", e);
-			Gui.getInstance().fatalError("Blockchain validation issue", e);
-			return; // Not System.exit() so that GUI can display error
+			LOGGER.info("Validating blockchain");
+			try {
+				BlockChain.validate();
+
+				Controller.getInstance().refillLatestBlocksCache();
+				LOGGER.info(String.format("Our chain height at start-up: %d", Controller.getInstance().getChainHeight()));
+			} catch (DataException e) {
+				LOGGER.error("Couldn't validate blockchain", e);
+				Gui.getInstance().fatalError("Blockchain validation issue", e);
+				return; // Not System.exit() so that GUI can display error
+			}
 		}
 
 		// Import current trade bot states and minting accounts if they exist
@@ -497,6 +553,7 @@ public class Controller extends Thread {
 		final long repositoryBackupInterval = Settings.getInstance().getRepositoryBackupInterval();
 		final long repositoryCheckpointInterval = Settings.getInstance().getRepositoryCheckpointInterval();
 		long repositoryMaintenanceInterval = getRandomRepositoryMaintenanceInterval();
+		final long prunePeersInterval = 5 * 60 * 1000L; // Every 5 minutes
 
 		// Start executor service for trimming or pruning
 		PruneManager.getInstance().start();
@@ -573,15 +630,20 @@ 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
@@ -589,10 +651,15 @@ public class Controller extends Thread {
 				}
 
 				// Prune stuck/slow/old peers
-				try {
-					Network.getInstance().prunePeers();
-				} catch (DataException e) {
-					LOGGER.warn(String.format("Repository issue when trying to prune peers: %s", e.getMessage()));
+				if (now >= prunePeersTimestamp + prunePeersInterval) {
+					prunePeersTimestamp = now + prunePeersInterval;
+
+					try {
+						LOGGER.debug("Pruning peers...");
+						Network.getInstance().prunePeers();
+					} catch (DataException e) {
+						LOGGER.warn(String.format("Repository issue when trying to prune peers: %s", e.getMessage()));
+					}
 				}
 
 				// Delete expired transactions
@@ -655,29 +722,6 @@ public class Controller extends Thread {
 		return lastMisbehaved != null && lastMisbehaved > NTP.getTime() - MISBEHAVIOUR_COOLOFF;
 	};
 
-	/** True if peer has unknown height, lower height or same height and same block signature (unless we don't have their block signature). */
-	public static Predicate<Peer> hasShorterBlockchain = peer -> {
-		BlockData highestBlockData = getInstance().getChainTip();
-		int ourHeight = highestBlockData.getHeight();
-		final PeerChainTipData peerChainTipData = peer.getChainTipData();
-
-		// Ensure we have chain tip data for this peer
-		if (peerChainTipData == null)
-			return true;
-
-		// Remove if peer is at a lower height than us
-		Integer peerHeight = peerChainTipData.getLastHeight();
-		if (peerHeight == null || peerHeight < ourHeight)
-			return true;
-
-		// Don't remove if peer is on a greater height chain than us, or if we don't have their block signature
-		if (peerHeight > ourHeight || peerChainTipData.getLastBlockSignature() == null)
-			return false;
-
-		// Remove if signatures match
-		return Arrays.equals(peerChainTipData.getLastBlockSignature(), highestBlockData.getSignature());
-	};
-
 	public static final Predicate<Peer> hasNoRecentBlock = peer -> {
 		final Long minLatestBlockTimestamp = getMinimumLatestBlockTimestamp();
 		final PeerChainTipData peerChainTipData = peer.getChainTipData();
@@ -750,19 +794,24 @@ 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);
+		// Any block in the last 2 hours is considered "up to date" for the purposes of displaying statuses.
+		// This also aligns with the time interval required for continued online account submission.
+		final Long minLatestBlockTimestamp = NTP.getTime() - (2 * 60 * 60 * 1000L);
+
+		// Only show sync percent if it's less than 100, to avoid confusion
+		final Integer syncPercent = Synchronizer.getInstance().getSyncPercent();
+		final boolean isSyncing = (syncPercent != null && syncPercent < 100);
 
 		synchronized (Synchronizer.getInstance().syncLock) {
-			if (this.isMintingPossible) {
-				actionText = Translator.INSTANCE.translate("SysTray", "MINTING_ENABLED");
-				SysTray.getInstance().setTrayIcon(2);
+			if (Settings.getInstance().isLite()) {
+				actionText = Translator.INSTANCE.translate("SysTray", "LITE_NODE");
+				SysTray.getInstance().setTrayIcon(4);
 			}
 			else if (numberOfPeers < Settings.getInstance().getMinBlockchainPeers()) {
 				actionText = Translator.INSTANCE.translate("SysTray", "CONNECTING");
 				SysTray.getInstance().setTrayIcon(3);
 			}
-			else if (!this.isUpToDate(minLatestBlockTimestamp) && Synchronizer.getInstance().isSynchronizing()) {
+			else if (!this.isUpToDate(minLatestBlockTimestamp) && isSyncing) {
 				actionText = String.format("%s - %d%%", Translator.INSTANCE.translate("SysTray", "SYNCHRONIZING_BLOCKCHAIN"), Synchronizer.getInstance().getSyncPercent());
 				SysTray.getInstance().setTrayIcon(3);
 			}
@@ -770,13 +819,21 @@ public class Controller extends Thread {
 				actionText = String.format("%s", Translator.INSTANCE.translate("SysTray", "SYNCHRONIZING_BLOCKCHAIN"));
 				SysTray.getInstance().setTrayIcon(3);
 			}
+			else if (OnlineAccountsManager.getInstance().hasActiveOnlineAccountSignatures()) {
+				actionText = Translator.INSTANCE.translate("SysTray", "MINTING_ENABLED");
+				SysTray.getInstance().setTrayIcon(2);
+			}
 			else {
 				actionText = Translator.INSTANCE.translate("SysTray", "MINTING_DISABLED");
 				SysTray.getInstance().setTrayIcon(4);
 			}
 		}
 
-		String tooltip = String.format("%s - %d %s - %s %d", actionText, numberOfPeers, connectionsText, heightText, height) + "\n" + String.format("%s: %s", Translator.INSTANCE.translate("SysTray", "BUILD_VERSION"), this.buildVersion);
+		String tooltip = String.format("%s - %d %s", actionText, numberOfPeers, connectionsText);
+		if (!Settings.getInstance().isLite()) {
+			tooltip = tooltip.concat(String.format(" - %s %d", heightText, height));
+		}
+		tooltip = tooltip.concat(String.format("\n%s: %s", Translator.INSTANCE.translate("SysTray", "BUILD_VERSION"), this.buildVersion));
 		SysTray.getInstance().setToolTipText(tooltip);
 
 		this.callbackExecutor.execute(() -> {
@@ -933,6 +990,11 @@ public class Controller extends Thread {
 	// Callbacks for/from network
 
 	public void doNetworkBroadcast() {
+		if (Settings.getInstance().isLite()) {
+			// Lite nodes have nothing to broadcast
+			return;
+		}
+
 		Network network = Network.getInstance();
 
 		// Send (if outbound) / Request peer lists
@@ -1179,6 +1241,10 @@ public class Controller extends Thread {
 				OnlineAccountsManager.getInstance().onNetworkOnlineAccountsV2Message(peer, message);
 				break;
 
+			case GET_ONLINE_ACCOUNTS_V3:
+				OnlineAccountsManager.getInstance().onNetworkGetOnlineAccountsV3Message(peer, message);
+				break;
+
 			case GET_ARBITRARY_DATA:
 				// Not currently supported
 				break;
@@ -1215,6 +1281,26 @@ public class Controller extends Thread {
 				TradeBot.getInstance().onTradePresencesMessage(peer, message);
 				break;
 
+			case GET_ACCOUNT:
+				onNetworkGetAccountMessage(peer, message);
+				break;
+
+			case GET_ACCOUNT_BALANCE:
+				onNetworkGetAccountBalanceMessage(peer, message);
+				break;
+
+			case GET_ACCOUNT_TRANSACTIONS:
+				onNetworkGetAccountTransactionsMessage(peer, message);
+				break;
+
+			case GET_ACCOUNT_NAMES:
+				onNetworkGetAccountNamesMessage(peer, message);
+				break;
+
+			case GET_NAME:
+				onNetworkGetNameMessage(peer, message);
+				break;
+
 			default:
 				LOGGER.debug(() -> String.format("Unhandled %s message [ID %d] from peer %s", message.getType().name(), message.getId(), peer));
 				break;
@@ -1236,7 +1322,7 @@ 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");
@@ -1292,10 +1378,21 @@ public class Controller extends Thread {
 
 			Block block = new Block(repository, blockData);
 
+			// V2 support
+			if (peer.getPeersVersion() >= BlockV2Message.MIN_PEER_VERSION) {
+				Message blockMessage = new BlockV2Message(block);
+				blockMessage.setId(message.getId());
+				if (!peer.sendMessage(blockMessage)) {
+					peer.disconnect("failed to send block");
+					// Don't fall-through to caching because failure to send might be from failure to build message
+					return;
+				}
+				return;
+			}
+
 			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
@@ -1309,7 +1406,9 @@ public class Controller extends Thread {
 				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);
+			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);
 		}
 	}
 
@@ -1450,11 +1549,13 @@ public class Controller extends Thread {
 	private void onNetworkHeightV2Message(Peer peer, Message message) {
 		HeightV2Message heightV2Message = (HeightV2Message) message;
 
-		// If peer is inbound and we've not updated their height
-		// then this is probably their initial HEIGHT_V2 message
-		// so they need a corresponding HEIGHT_V2 message from us
-		if (!peer.isOutbound() && (peer.getChainTipData() == null || peer.getChainTipData().getLastHeight() == null))
-			peer.sendMessage(Network.getInstance().buildHeightMessage(peer, getChainTip()));
+		if (!Settings.getInstance().isLite()) {
+			// If peer is inbound and we've not updated their height
+			// then this is probably their initial HEIGHT_V2 message
+			// so they need a corresponding HEIGHT_V2 message from us
+			if (!peer.isOutbound() && (peer.getChainTipData() == null || peer.getChainTipData().getLastHeight() == null))
+				peer.sendMessage(Network.getInstance().buildHeightMessage(peer, getChainTip()));
+		}
 
 		// Update peer chain tip data
 		PeerChainTipData newChainTipData = new PeerChainTipData(heightV2Message.getHeight(), heightV2Message.getSignature(), heightV2Message.getTimestamp(), heightV2Message.getMinterPublicKey());
@@ -1464,6 +1565,193 @@ public class Controller extends Thread {
 		Synchronizer.getInstance().requestSync();
 	}
 
+	private void onNetworkGetAccountMessage(Peer peer, Message message) {
+		GetAccountMessage getAccountMessage = (GetAccountMessage) message;
+		String address = getAccountMessage.getAddress();
+		this.stats.getAccountMessageStats.requests.incrementAndGet();
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			AccountData accountData = repository.getAccountRepository().getAccount(address);
+
+			if (accountData == null) {
+				// We don't have this account
+				this.stats.getAccountMessageStats.unknownAccounts.getAndIncrement();
+
+				// Send valid, yet unexpected message type in response, so peer doesn't have to wait for timeout
+				LOGGER.debug(() -> String.format("Sending 'account unknown' response to peer %s for GET_ACCOUNT request for unknown account %s", peer, address));
+
+				// We'll send empty block summaries message as it's very short
+				Message accountUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+				accountUnknownMessage.setId(message.getId());
+				if (!peer.sendMessage(accountUnknownMessage))
+					peer.disconnect("failed to send account-unknown response");
+				return;
+			}
+
+			AccountMessage accountMessage = new AccountMessage(accountData);
+			accountMessage.setId(message.getId());
+
+			if (!peer.sendMessage(accountMessage)) {
+				peer.disconnect("failed to send account");
+			}
+
+		} catch (DataException e) {
+			LOGGER.error(String.format("Repository issue while send account %s to peer %s", address, peer), e);
+		}
+	}
+
+	private void onNetworkGetAccountBalanceMessage(Peer peer, Message message) {
+		GetAccountBalanceMessage getAccountBalanceMessage = (GetAccountBalanceMessage) message;
+		String address = getAccountBalanceMessage.getAddress();
+		long assetId = getAccountBalanceMessage.getAssetId();
+		this.stats.getAccountBalanceMessageStats.requests.incrementAndGet();
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			AccountBalanceData accountBalanceData = repository.getAccountRepository().getBalance(address, assetId);
+
+			if (accountBalanceData == null) {
+				// We don't have this account
+				this.stats.getAccountBalanceMessageStats.unknownAccounts.getAndIncrement();
+
+				// Send valid, yet unexpected message type in response, so peer doesn't have to wait for timeout
+				LOGGER.debug(() -> String.format("Sending 'account unknown' response to peer %s for GET_ACCOUNT_BALANCE request for unknown account %s and asset ID %d", peer, address, assetId));
+
+				// We'll send empty block summaries message as it's very short
+				Message accountUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+				accountUnknownMessage.setId(message.getId());
+				if (!peer.sendMessage(accountUnknownMessage))
+					peer.disconnect("failed to send account-unknown response");
+				return;
+			}
+
+			AccountBalanceMessage accountMessage = new AccountBalanceMessage(accountBalanceData);
+			accountMessage.setId(message.getId());
+
+			if (!peer.sendMessage(accountMessage)) {
+				peer.disconnect("failed to send account balance");
+			}
+
+		} catch (DataException e) {
+			LOGGER.error(String.format("Repository issue while send balance for account %s and asset ID %d to peer %s", address, assetId, peer), e);
+		}
+	}
+
+	private void onNetworkGetAccountTransactionsMessage(Peer peer, Message message) {
+		GetAccountTransactionsMessage getAccountTransactionsMessage = (GetAccountTransactionsMessage) message;
+		String address = getAccountTransactionsMessage.getAddress();
+		int limit = Math.min(getAccountTransactionsMessage.getLimit(), 100);
+		int offset = getAccountTransactionsMessage.getOffset();
+		this.stats.getAccountTransactionsMessageStats.requests.incrementAndGet();
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			List<byte[]> signatures = repository.getTransactionRepository().getSignaturesMatchingCriteria(null, null, null,
+					null, null, null, address, TransactionsResource.ConfirmationStatus.CONFIRMED, limit, offset, false);
+
+			// Expand signatures to transactions
+			List<TransactionData> transactions = new ArrayList<>(signatures.size());
+			for (byte[] signature : signatures) {
+				transactions.add(repository.getTransactionRepository().fromSignature(signature));
+			}
+
+			if (transactions == null) {
+				// We don't have this account
+				this.stats.getAccountTransactionsMessageStats.unknownAccounts.getAndIncrement();
+
+				// Send valid, yet unexpected message type in response, so peer doesn't have to wait for timeout
+				LOGGER.debug(() -> String.format("Sending 'account unknown' response to peer %s for GET_ACCOUNT_TRANSACTIONS request for unknown account %s", peer, address));
+
+				// We'll send empty block summaries message as it's very short
+				Message accountUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+				accountUnknownMessage.setId(message.getId());
+				if (!peer.sendMessage(accountUnknownMessage))
+					peer.disconnect("failed to send account-unknown response");
+				return;
+			}
+
+			TransactionsMessage transactionsMessage = new TransactionsMessage(transactions);
+			transactionsMessage.setId(message.getId());
+
+			if (!peer.sendMessage(transactionsMessage)) {
+				peer.disconnect("failed to send account transactions");
+			}
+
+		} catch (DataException e) {
+			LOGGER.error(String.format("Repository issue while sending transactions for account %s %d to peer %s", address, peer), e);
+		} catch (MessageException e) {
+			LOGGER.error(String.format("Message serialization issue while sending transactions for account %s %d to peer %s", address, peer), e);
+		}
+	}
+
+	private void onNetworkGetAccountNamesMessage(Peer peer, Message message) {
+		GetAccountNamesMessage getAccountNamesMessage = (GetAccountNamesMessage) message;
+		String address = getAccountNamesMessage.getAddress();
+		this.stats.getAccountNamesMessageStats.requests.incrementAndGet();
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			List<NameData> namesDataList = repository.getNameRepository().getNamesByOwner(address);
+
+			if (namesDataList == null) {
+				// We don't have this account
+				this.stats.getAccountNamesMessageStats.unknownAccounts.getAndIncrement();
+
+				// Send valid, yet unexpected message type in response, so peer doesn't have to wait for timeout
+				LOGGER.debug(() -> String.format("Sending 'account unknown' response to peer %s for GET_ACCOUNT_NAMES request for unknown account %s", peer, address));
+
+				// We'll send empty block summaries message as it's very short
+				Message accountUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+				accountUnknownMessage.setId(message.getId());
+				if (!peer.sendMessage(accountUnknownMessage))
+					peer.disconnect("failed to send account-unknown response");
+				return;
+			}
+
+			NamesMessage namesMessage = new NamesMessage(namesDataList);
+			namesMessage.setId(message.getId());
+
+			if (!peer.sendMessage(namesMessage)) {
+				peer.disconnect("failed to send account names");
+			}
+
+		} catch (DataException e) {
+			LOGGER.error(String.format("Repository issue while send names for account %s to peer %s", address, peer), e);
+		}
+	}
+
+	private void onNetworkGetNameMessage(Peer peer, Message message) {
+		GetNameMessage getNameMessage = (GetNameMessage) message;
+		String name = getNameMessage.getName();
+		this.stats.getNameMessageStats.requests.incrementAndGet();
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			NameData nameData = repository.getNameRepository().fromName(name);
+
+			if (nameData == null) {
+				// We don't have this account
+				this.stats.getNameMessageStats.unknownAccounts.getAndIncrement();
+
+				// Send valid, yet unexpected message type in response, so peer doesn't have to wait for timeout
+				LOGGER.debug(() -> String.format("Sending 'name unknown' response to peer %s for GET_NAME request for unknown name %s", peer, name));
+
+				// We'll send empty block summaries message as it's very short
+				Message nameUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+				nameUnknownMessage.setId(message.getId());
+				if (!peer.sendMessage(nameUnknownMessage))
+					peer.disconnect("failed to send name-unknown response");
+				return;
+			}
+
+			NamesMessage namesMessage = new NamesMessage(Arrays.asList(nameData));
+			namesMessage.setId(message.getId());
+
+			if (!peer.sendMessage(namesMessage)) {
+				peer.disconnect("failed to send name data");
+			}
+
+		} catch (DataException e) {
+			LOGGER.error(String.format("Repository issue while send name %s to peer %s", name, peer), e);
+		}
+	}
+
 
 	// Utilities
 
@@ -1515,6 +1803,11 @@ public class Controller extends Thread {
 	 * @return boolean - whether our node's blockchain is up to date or not
 	 */
 	public boolean isUpToDate(Long minLatestBlockTimestamp) {
+		if (Settings.getInstance().isLite()) {
+			// Lite nodes are always "up to date"
+			return true;
+		}
+
 		// Do we even have a vaguely recent block?
 		if (minLatestBlockTimestamp == null)
 			return false;

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

@@ -0,0 +1,189 @@
+package org.qortal.controller;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.data.account.AccountBalanceData;
+import org.qortal.data.account.AccountData;
+import org.qortal.data.naming.NameData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.network.Network;
+import org.qortal.network.Peer;
+import org.qortal.network.message.*;
+
+import java.security.SecureRandom;
+import java.util.*;
+
+import static org.qortal.network.message.MessageType.*;
+
+public class LiteNode {
+
+    private static final Logger LOGGER = LogManager.getLogger(LiteNode.class);
+
+    private static LiteNode instance;
+
+
+    public Map<Integer, Long> pendingRequests = Collections.synchronizedMap(new HashMap<>());
+
+    public int MAX_TRANSACTIONS_PER_MESSAGE = 100;
+
+
+    public LiteNode() {
+
+    }
+
+    public static synchronized LiteNode getInstance() {
+        if (instance == null) {
+            instance = new LiteNode();
+        }
+
+        return instance;
+    }
+
+
+    /**
+     * Fetch account data from peers for given QORT address
+     * @param address - the QORT address to query
+     * @return accountData - the account data for this address, or null if not retrieved
+     */
+    public AccountData fetchAccountData(String address) {
+        GetAccountMessage getAccountMessage = new GetAccountMessage(address);
+        AccountMessage accountMessage = (AccountMessage) this.sendMessage(getAccountMessage, ACCOUNT);
+        if (accountMessage == null) {
+            return null;
+        }
+        return accountMessage.getAccountData();
+    }
+
+    /**
+     * Fetch account balance data from peers for given QORT address and asset ID
+     * @param address - the QORT address to query
+     * @return balance - the balance for this address and assetId, or null if not retrieved
+     */
+    public AccountBalanceData fetchAccountBalance(String address, long assetId) {
+        GetAccountBalanceMessage getAccountMessage = new GetAccountBalanceMessage(address, assetId);
+        AccountBalanceMessage accountMessage = (AccountBalanceMessage) this.sendMessage(getAccountMessage, ACCOUNT_BALANCE);
+        if (accountMessage == null) {
+            return null;
+        }
+        return accountMessage.getAccountBalanceData();
+    }
+
+    /**
+     * Fetch list of transactions for given QORT address
+     * @param address - the QORT address to query
+     * @param limit - the maximum number of results to return
+     * @param offset - the starting index
+     * @return a list of TransactionData objects, or null if not retrieved
+     */
+    public List<TransactionData> fetchAccountTransactions(String address, int limit, int offset) {
+        List<TransactionData> allTransactions = new ArrayList<>();
+        if (limit == 0) {
+            limit = Integer.MAX_VALUE;
+        }
+        int batchSize = Math.min(limit, MAX_TRANSACTIONS_PER_MESSAGE);
+
+        while (allTransactions.size() < limit) {
+            GetAccountTransactionsMessage getAccountTransactionsMessage = new GetAccountTransactionsMessage(address, batchSize, offset);
+            TransactionsMessage transactionsMessage = (TransactionsMessage) this.sendMessage(getAccountTransactionsMessage, TRANSACTIONS);
+            if (transactionsMessage == null) {
+                // An error occurred, so give up instead of returning partial results
+                return null;
+            }
+            allTransactions.addAll(transactionsMessage.getTransactions());
+            if (transactionsMessage.getTransactions().size() < batchSize) {
+                // No more transactions to fetch
+                break;
+            }
+            offset += batchSize;
+        }
+        return allTransactions;
+    }
+
+    /**
+     * Fetch list of names for given QORT address
+     * @param address - the QORT address to query
+     * @return a list of NameData objects, or null if not retrieved
+     */
+    public List<NameData> fetchAccountNames(String address) {
+        GetAccountNamesMessage getAccountNamesMessage = new GetAccountNamesMessage(address);
+        NamesMessage namesMessage = (NamesMessage) this.sendMessage(getAccountNamesMessage, NAMES);
+        if (namesMessage == null) {
+            return null;
+        }
+        return namesMessage.getNameDataList();
+    }
+
+    /**
+     * Fetch info about a registered name
+     * @param name - the name to query
+     * @return a NameData object, or null if not retrieved
+     */
+    public NameData fetchNameData(String name) {
+        GetNameMessage getNameMessage = new GetNameMessage(name);
+        NamesMessage namesMessage = (NamesMessage) this.sendMessage(getNameMessage, NAMES);
+        if (namesMessage == null) {
+            return null;
+        }
+        List<NameData> nameDataList = namesMessage.getNameDataList();
+        if (nameDataList == null || nameDataList.size() != 1) {
+            return null;
+        }
+        // We are only expecting a single item in the list
+        return nameDataList.get(0);
+    }
+
+
+    private Message sendMessage(Message message, MessageType expectedResponseMessageType) {
+        // This asks a random peer for the data
+        // TODO: ask multiple peers, and disregard everything if there are any significant differences in the responses
+
+        // 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);
+
+        // Disregard peers that only have genesis block
+        // TODO: peers.removeIf(Controller.hasOnlyGenesisBlock);
+
+        // Disregard peers that are on an old version
+        peers.removeIf(Controller.hasOldVersion);
+
+        // Disregard peers that are on a known inferior chain tip
+        // TODO: peers.removeIf(Controller.hasInferiorChainTip);
+
+        if (peers.isEmpty()) {
+            LOGGER.info("No peers available to send {} message to", message.getType());
+            return null;
+        }
+
+        // Pick random peer
+        int index = new SecureRandom().nextInt(peers.size());
+        Peer peer = peers.get(index);
+
+        LOGGER.info("Sending {} message to peer {}...", message.getType(), peer);
+
+        Message responseMessage;
+
+        try {
+            responseMessage = peer.getResponse(message);
+
+        } catch (InterruptedException e) {
+            return null;
+        }
+
+        if (responseMessage == null) {
+            LOGGER.info("Peer {} didn't respond to {} message", peer, message.getType());
+            return null;
+        }
+        else if (responseMessage.getType() != expectedResponseMessageType) {
+            LOGGER.info("Peer responded with unexpected message type {} (should be {})", peer, responseMessage.getType(), expectedResponseMessageType);
+            return null;
+        }
+
+        LOGGER.info("Peer {} responded with {} message", peer, responseMessage.getType());
+
+        return responseMessage;
+    }
+
+}

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

@@ -26,14 +26,7 @@ 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;
-import org.qortal.network.message.BlockSummariesMessage;
-import org.qortal.network.message.GetBlockMessage;
-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.*;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryManager;
@@ -88,7 +81,7 @@ public class Synchronizer extends Thread {
 	private boolean syncRequestPending = false;
 
 	// Keep track of invalid blocks so that we don't keep trying to sync them
-	private Map<String, Long> invalidBlockSignatures = Collections.synchronizedMap(new HashMap<>());
+	private Map<ByteArray, Long> invalidBlockSignatures = Collections.synchronizedMap(new HashMap<>());
 	public Long timeValidBlockLastReceived = null;
 	public Long timeInvalidBlockLastReceived = null;
 
@@ -134,6 +127,11 @@ public class Synchronizer extends Thread {
 	public void run() {
 		Thread.currentThread().setName("Synchronizer");
 
+		if (Settings.getInstance().isLite()) {
+			// Lite nodes don't need to sync
+			return;
+		}
+
 		try {
 			while (running && !Controller.isStopping()) {
 				Thread.sleep(1000);
@@ -173,8 +171,8 @@ 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);
+			// Report as 100% synced if the latest block is within the last 60 mins
+			final Long minLatestBlockTimestamp = NTP.getTime() - (60 * 60 * 1000L);
 			if (Controller.getInstance().isUpToDate(minLatestBlockTimestamp)) {
 				return 100;
 			}
@@ -235,9 +233,6 @@ public class Synchronizer extends Thread {
 		// Disregard peers that are on the same block as last sync attempt and we didn't like their chain
 		peers.removeIf(Controller.hasInferiorChainTip);
 
-		// Remove peers with unknown height, lower height or same height and same block signature (unless we don't have their block signature)
-		peers.removeIf(Controller.hasShorterBlockchain);
-
 		final int peersBeforeComparison = peers.size();
 
 		// Request recent block summaries from the remaining peers, and locate our common block with each
@@ -622,7 +617,7 @@ public class Synchronizer extends Thread {
 							// We have already determined that the correct chain diverged from a lower height. We are safe to skip these peers.
 							for (Peer peer : peersSharingCommonBlock) {
 								LOGGER.debug(String.format("Peer %s has common block at height %d but the superior chain is at height %d. Removing it from this round.", peer, commonBlockSummary.getHeight(), dropPeersAfterCommonBlockHeight));
-								this.addInferiorChainSignature(peer.getChainTipData().getLastBlockSignature());
+								//this.addInferiorChainSignature(peer.getChainTipData().getLastBlockSignature());
 							}
 							continue;
 						}
@@ -633,7 +628,9 @@ public class Synchronizer extends Thread {
 					int minChainLength = this.calculateMinChainLengthOfPeers(peersSharingCommonBlock, commonBlockSummary);
 
 					// Fetch block summaries from each peer
-					for (Peer peer : peersSharingCommonBlock) {
+					Iterator peersSharingCommonBlockIterator = peersSharingCommonBlock.iterator();
+					while (peersSharingCommonBlockIterator.hasNext()) {
+						Peer peer = (Peer) peersSharingCommonBlockIterator.next();
 
 						// If we're shutting down, just return the latest peer list
 						if (Controller.isStopping())
@@ -690,6 +687,8 @@ public class Synchronizer extends Thread {
 						if (this.containsInvalidBlockSummary(peer.getCommonBlockData().getBlockSummariesAfterCommonBlock())) {
 							LOGGER.debug("Ignoring peer %s because it holds an invalid block", peer);
 							peers.remove(peer);
+							peersSharingCommonBlockIterator.remove();
+							continue;
 						}
 
 						// Reduce minChainLength if needed. If we don't have any blocks, this peer will be excluded from chain weight comparisons later in the process, so we shouldn't update minChainLength
@@ -845,6 +844,10 @@ public class Synchronizer extends Thread {
 
 	/* Invalid block signature tracking */
 
+	public Map<ByteArray, Long> getInvalidBlockSignatures() {
+		return this.invalidBlockSignatures;
+	}
+
 	private void addInvalidBlockSignature(byte[] signature) {
 		Long now = NTP.getTime();
 		if (now == null) {
@@ -852,8 +855,7 @@ public class Synchronizer extends Thread {
 		}
 
 		// Add or update existing entry
-		String sig58 = Base58.encode(signature);
-		invalidBlockSignatures.put(sig58, now);
+		invalidBlockSignatures.put(ByteArray.wrap(signature), now);
 	}
 	private void deleteOlderInvalidSignatures(Long now) {
 		if (now == null) {
@@ -872,17 +874,16 @@ public class Synchronizer extends Thread {
 			}
 		}
 	}
-	private boolean containsInvalidBlockSummary(List<BlockSummaryData> blockSummaries) {
+	public boolean containsInvalidBlockSummary(List<BlockSummaryData> blockSummaries) {
 		if (blockSummaries == null || invalidBlockSignatures == null) {
 			return false;
 		}
 
 		// Loop through our known invalid blocks and check each one against supplied block summaries
-		for (String invalidSignature58 : invalidBlockSignatures.keySet()) {
-			byte[] invalidSignature = Base58.decode(invalidSignature58);
+		for (ByteArray invalidSignature : invalidBlockSignatures.keySet()) {
 			for (BlockSummaryData blockSummary : blockSummaries) {
 				byte[] signature = blockSummary.getSignature();
-				if (Arrays.equals(signature, invalidSignature)) {
+				if (Arrays.equals(signature, invalidSignature.value)) {
 					return true;
 				}
 			}
@@ -895,10 +896,9 @@ public class Synchronizer extends Thread {
 		}
 
 		// Loop through our known invalid blocks and check each one against supplied block signatures
-		for (String invalidSignature58 : invalidBlockSignatures.keySet()) {
-			byte[] invalidSignature = Base58.decode(invalidSignature58);
+		for (ByteArray invalidSignature : invalidBlockSignatures.keySet()) {
 			for (byte[] signature : blockSignatures) {
-				if (Arrays.equals(signature, invalidSignature)) {
+				if (Arrays.equals(signature, invalidSignature.value)) {
 					return true;
 				}
 			}
@@ -1577,12 +1577,23 @@ public class Synchronizer extends Thread {
 		Message getBlockMessage = new GetBlockMessage(signature);
 
 		Message message = peer.getResponse(getBlockMessage);
-		if (message == null || message.getType() != MessageType.BLOCK)
+		if (message == null)
 			return null;
 
-		BlockMessage blockMessage = (BlockMessage) message;
+		switch (message.getType()) {
+			case BLOCK: {
+				BlockMessage blockMessage = (BlockMessage) message;
+				return new Block(repository, blockMessage.getBlockData(), blockMessage.getTransactions(), blockMessage.getAtStates());
+			}
 
-		return new Block(repository, blockMessage.getBlockData(), blockMessage.getTransactions(), blockMessage.getAtStates());
+			case BLOCK_V2: {
+				BlockV2Message blockMessage = (BlockV2Message) message;
+				return new Block(repository, blockMessage.getBlockData(), blockMessage.getTransactions(), blockMessage.getAtStatesHash());
+			}
+
+			default:
+				return null;
+		}
 	}
 
 	public void populateBlockSummariesMinterLevels(Repository repository, List<BlockSummaryData> blockSummaries) throws DataException {

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

@@ -2,7 +2,9 @@ package org.qortal.controller;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.qortal.data.block.BlockData;
 import org.qortal.data.transaction.TransactionData;
+import org.qortal.network.Network;
 import org.qortal.network.Peer;
 import org.qortal.network.message.GetTransactionMessage;
 import org.qortal.network.message.Message;
@@ -11,13 +13,15 @@ import org.qortal.network.message.TransactionSignaturesMessage;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryManager;
+import org.qortal.settings.Settings;
 import org.qortal.transaction.Transaction;
+import org.qortal.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;
+import java.util.stream.Collectors;
 
 public class TransactionImporter extends Thread {
 
@@ -54,12 +58,16 @@ public class TransactionImporter extends Thread {
 
     @Override
     public void run() {
+        Thread.currentThread().setName("Transaction Importer");
+
         try {
             while (!Controller.isStopping()) {
-                Thread.sleep(1000L);
+                Thread.sleep(500L);
 
                 // Process incoming transactions queue
-                processIncomingTransactionsQueue();
+                validateTransactionsInQueue();
+                importTransactionsInQueue();
+
                 // Clean up invalid incoming transactions list
                 cleanupInvalidTransactionsList(NTP.getTime());
             }
@@ -86,7 +94,26 @@ public class TransactionImporter extends Thread {
         incomingTransactions.keySet().removeIf(t -> Arrays.equals(t.getSignature(), signature));
     }
 
-    private void processIncomingTransactionsQueue() {
+    /**
+     * Retrieve all pending unconfirmed transactions that have had their signatures validated.
+     * @return a list of TransactionData objects, with valid signatures.
+     */
+    private List<TransactionData> getCachedSigValidTransactions() {
+        synchronized (this.incomingTransactions) {
+            return this.incomingTransactions.entrySet().stream()
+                    .filter(t -> Boolean.TRUE.equals(t.getValue()))
+                    .map(Map.Entry::getKey)
+                    .collect(Collectors.toList());
+        }
+    }
+
+    /**
+     * Validate the signatures of any transactions pending import, then update their
+     * entries in the queue to mark them as valid/invalid.
+     *
+     * No database lock is required.
+     */
+    private void validateTransactionsInQueue() {
         if (this.incomingTransactions.isEmpty()) {
             // Nothing to do?
             return;
@@ -103,8 +130,17 @@ public class TransactionImporter extends Thread {
                 LOGGER.debug("Validating signatures in incoming transactions queue (size {})...", unvalidatedCount);
             }
 
+            // A list of all currently pending transactions that have valid signatures
             List<Transaction> sigValidTransactions = new ArrayList<>();
 
+            // A list of signatures that became valid in this round
+            List<byte[]> newlyValidSignatures = new ArrayList<>();
+
+            boolean isLiteNode = Settings.getInstance().isLite();
+
+            // We need the latest block in order to check for expired transactions
+            BlockData latestBlock = Controller.getInstance().getChainTip();
+
             // Signature validation round - does not require blockchain lock
             for (Map.Entry<TransactionData, Boolean> transactionEntry : incomingTransactionsCopy.entrySet()) {
                 // Quick exit?
@@ -114,34 +150,59 @@ public class TransactionImporter extends Thread {
 
                 TransactionData transactionData = transactionEntry.getKey();
                 Transaction transaction = Transaction.fromData(repository, transactionData);
+                String signature58 = Base58.encode(transactionData.getSignature());
+
+                Long now = NTP.getTime();
+                if (now == null) {
+                    return;
+                }
+
+                // Drop expired transactions before they are considered "sig valid"
+                if (latestBlock != null && transaction.getDeadline() <= latestBlock.getTimestamp()) {
+                    LOGGER.debug("Removing expired {} transaction {} from import queue", transactionData.getType().name(), signature58);
+                    removeIncomingTransaction(transactionData.getSignature());
+                    invalidUnconfirmedTransactions.put(signature58, (now + EXPIRED_TRANSACTION_RECHECK_INTERVAL));
+                    continue;
+                }
 
                 // 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());
+                    if (isLiteNode) {
+                        // Lite nodes can't easily validate transactions, so for now we will have to assume that everything is valid
+                        sigValidTransactions.add(transaction);
+                        newlyValidSignatures.add(transactionData.getSignature());
+                        // Add mark signature as valid if transaction still exists in import queue
+                        incomingTransactions.computeIfPresent(transactionData, (k, v) -> Boolean.TRUE);
+                        continue;
+                    }
 
-                        LOGGER.trace("Ignoring {} transaction {} with invalid signature", transactionData.getType().name(), signature58);
+                    if (!transaction.isSignatureValid()) {
+                        LOGGER.debug("Ignoring {} transaction {} with invalid signature", transactionData.getType().name(), signature58);
                         removeIncomingTransaction(transactionData.getSignature());
 
                         // Also add to invalidIncomingTransactions map
-                        Long now = NTP.getTime();
+                        now = NTP.getTime();
                         if (now != null) {
                             Long expiry = now + INVALID_TRANSACTION_RECHECK_INTERVAL;
-                            LOGGER.trace("Adding stale invalid transaction {} to invalidUnconfirmedTransactions...", signature58);
+                            LOGGER.trace("Adding invalid transaction {} to invalidUnconfirmedTransactions...", signature58);
                             // Add to invalidUnconfirmedTransactions so that we don't keep requesting it
                             invalidUnconfirmedTransactions.put(signature58, expiry);
                         }
 
+                        // We're done with this transaction
                         continue;
                     }
-                    else {
-                        // Count the number that were validated in this round, for logging purposes
-                        validatedCount++;
-                    }
+
+                    // 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);
+
+                    // Signature validated in this round
+                    newlyValidSignatures.add(transactionData.getSignature());
+
                 } else {
                     LOGGER.trace(() -> String.format("Transaction %s known to have valid signature", Base58.encode(transactionData.getSignature())));
                 }
@@ -154,30 +215,44 @@ public class TransactionImporter extends Thread {
                 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 (!newlyValidSignatures.isEmpty()) {
+                LOGGER.debug("Broadcasting {} newly valid signatures ahead of import", newlyValidSignatures.size());
+                Message newTransactionSignatureMessage = new TransactionSignaturesMessage(newlyValidSignatures);
+                Network.getInstance().broadcast(broadcastPeer -> newTransactionSignatureMessage);
             }
 
-            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;
-            }
+        } catch (DataException e) {
+            LOGGER.error("Repository issue while processing incoming transactions", e);
+        }
+    }
 
-            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;
-            }
+    /**
+     * Import any transactions in the queue that have valid signatures.
+     *
+     * A database lock is required.
+     */
+    private void importTransactionsInQueue() {
+        List<TransactionData> sigValidTransactions = this.getCachedSigValidTransactions();
+        if (sigValidTransactions.isEmpty()) {
+            // Don't bother locking if there are no new transactions to process
+            return;
+        }
 
-            LOGGER.debug("Processing incoming transactions queue (size {})...", sigValidTransactions.size());
+        if (Synchronizer.getInstance().isSyncRequested() || Synchronizer.getInstance().isSynchronizing()) {
+            // Prioritize syncing, and don't attempt to lock
+            return;
+        }
+
+        ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
+        if (!blockchainLock.tryLock()) {
+            LOGGER.debug("Too busy to import incoming transactions queue");
+            return;
+        }
+
+        LOGGER.debug("Importing incoming transactions queue (size {})...", sigValidTransactions.size());
+
+        int processedCount = 0;
+        try (final Repository repository = RepositoryManager.getRepository()) {
 
             // Import transactions with valid signatures
             try {
@@ -187,14 +262,15 @@ public class TransactionImporter extends Thread {
                     }
 
                     if (Synchronizer.getInstance().isSyncRequestPending()) {
-                        LOGGER.debug("Breaking out of transaction processing with {} remaining, because a sync request is pending", sigValidTransactions.size() - i);
+                        LOGGER.debug("Breaking out of transaction importing with {} remaining, because a sync request is pending", sigValidTransactions.size() - i);
                         return;
                     }
 
-                    Transaction transaction = sigValidTransactions.get(i);
-                    TransactionData transactionData = transaction.getTransactionData();
+                    TransactionData transactionData = sigValidTransactions.get(i);
+                    Transaction transaction = Transaction.fromData(repository, transactionData);
 
                     Transaction.ValidationResult validationResult = transaction.importAsUnconfirmed();
+                    processedCount++;
 
                     switch (validationResult) {
                         case TRANSACTION_ALREADY_EXISTS: {
@@ -216,7 +292,7 @@ public class TransactionImporter extends Thread {
                         // 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));
+                            LOGGER.debug(() -> 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) {
@@ -239,12 +315,11 @@ public class TransactionImporter extends Thread {
                     removeIncomingTransaction(transactionData.getSignature());
                 }
             } finally {
-                LOGGER.debug("Finished processing incoming transactions queue");
-                ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
+                LOGGER.debug("Finished importing {} incoming transaction{}", processedCount, (processedCount == 1 ? "" : "s"));
                 blockchainLock.unlock();
             }
         } catch (DataException e) {
-            LOGGER.error("Repository issue while processing incoming transactions", e);
+            LOGGER.error("Repository issue while importing incoming transactions", e);
         }
     }
 
@@ -277,8 +352,18 @@ public class TransactionImporter extends Thread {
         byte[] signature = getTransactionMessage.getSignature();
 
         try (final Repository repository = RepositoryManager.getRepository()) {
-            TransactionData transactionData = repository.getTransactionRepository().fromSignature(signature);
+            // Firstly check the sig-valid transactions that are currently queued for import
+            TransactionData transactionData = this.getCachedSigValidTransactions().stream()
+                    .filter(t -> Arrays.equals(signature, t.getSignature()))
+                    .findFirst().orElse(null);
+
             if (transactionData == null) {
+                // Not found in import queue, so try the database
+                transactionData = repository.getTransactionRepository().fromSignature(signature);
+            }
+
+            if (transactionData == null) {
+                // Still not found - so we don't have this transaction
                 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;
@@ -289,7 +374,9 @@ public class TransactionImporter extends Thread {
             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);
+            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);
         }
     }
 

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

@@ -67,6 +67,9 @@ public class ArbitraryDataFileListManager {
     /** Maximum number of hops that a file list relay request is allowed to make */
     public static int RELAY_REQUEST_MAX_HOPS = 4;
 
+    /** Minimum peer version to use relay */
+    public static String RELAY_MIN_PEER_VERSION = "3.4.0";
+
 
     private ArbitraryDataFileListManager() {
     }
@@ -283,8 +286,8 @@ public class ArbitraryDataFileListManager {
 
         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();
+        // Send our address as requestingPeer, to allow for potential direct connections with seeds/peers
+        String requestingPeer = Network.getInstance().getOurExternalIpAddressAndPort();
 
         // Build request
         Message getArbitraryDataFileListMessage = new GetArbitraryDataFileListMessage(signature, missingHashes, now, 0, requestingPeer);
@@ -511,18 +514,24 @@ public class ArbitraryDataFileListManager {
 
                     // Bump requestHops if it exists
                     if (requestHops != null) {
-                        arbitraryDataFileListMessage.setRequestHops(++requestHops);
+                        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)) {
-                        arbitraryDataFileListMessage.removeOptionalStats();
+                        forwardArbitraryDataFileListMessage = new ArbitraryDataFileListMessage(signature, hashes);
+                    } else {
+                        forwardArbitraryDataFileListMessage = new ArbitraryDataFileListMessage(signature, hashes, requestTime, requestHops,
+                                arbitraryDataFileListMessage.getPeerAddress(), arbitraryDataFileListMessage.isRelayPossible());
                     }
+                    forwardArbitraryDataFileListMessage.setId(message.getId());
 
                     // 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");
                     }
                 }
@@ -631,6 +640,9 @@ public class ArbitraryDataFileListManager {
         // We should only respond if we have at least one hash
         if (hashes.size() > 0) {
 
+            // Firstly we should keep track of the requesting peer, to allow for potential direct connections later
+            ArbitraryDataFileManager.getInstance().addRecentDataRequest(requestingPeer);
+
             // We have all the chunks, so update requests map to reflect that we've sent it
             // There is no need to keep track of the request, as we can serve all the chunks
             if (allChunksExist) {
@@ -639,16 +651,19 @@ public class ArbitraryDataFileListManager {
             }
 
             String ourAddress = Network.getInstance().getOurExternalIpAddressAndPort();
-            ArbitraryDataFileListMessage arbitraryDataFileListMessage = new ArbitraryDataFileListMessage(signature,
-                    hashes, NTP.getTime(), 0, ourAddress, true);
-            arbitraryDataFileListMessage.setId(message.getId());
+            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.removeOptionalStats();
+                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");
@@ -670,8 +685,7 @@ 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) {
@@ -679,11 +693,15 @@ 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);
+                    relayGetArbitraryDataFileListMessage.setId(message.getId());
+
                     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);
+                            broadcastPeer ->
+                                    !broadcastPeer.isAtLeastVersion(RELAY_MIN_PEER_VERSION) ? null :
+                                    broadcastPeer == peer || Objects.equals(broadcastPeer.getPeerData().getAddress().getHost(), peer.getPeerData().getAddress().getHost()) ? null : relayGetArbitraryDataFileListMessage
+                    );
 
                 }
                 else {

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

@@ -1,5 +1,6 @@
 package org.qortal.controller.arbitrary;
 
+import com.google.common.net.InetAddresses;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.arbitrary.ArbitraryDataFile;
@@ -7,7 +8,6 @@ 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;
@@ -55,6 +55,13 @@ public class ArbitraryDataFileManager extends Thread {
      */
     private List<ArbitraryDirectConnectionInfo> directConnectionInfo = Collections.synchronizedList(new ArrayList<>());
 
+    /**
+     * Map to keep track of peers requesting QDN data that we hold.
+     * Key = peer address string, value = time of last request.
+     * This allows for additional "burst" connections beyond existing limits.
+     */
+    private Map<String, Long> recentDataRequests = Collections.synchronizedMap(new HashMap<>());
+
 
     public static int MAX_FILE_HASH_RESPONSES = 1000;
 
@@ -109,6 +116,9 @@ public class ArbitraryDataFileManager extends Thread {
 
         final long directConnectionInfoMinimumTimestamp = now - ArbitraryDataManager.getInstance().ARBITRARY_DIRECT_CONNECTION_INFO_TIMEOUT;
         directConnectionInfo.removeIf(entry -> entry.getTimestamp() < directConnectionInfoMinimumTimestamp);
+
+        final long recentDataRequestMinimumTimestamp = now - ArbitraryDataManager.getInstance().ARBITRARY_RECENT_DATA_REQUESTS_TIMEOUT;
+        recentDataRequests.entrySet().removeIf(entry -> entry.getValue() < recentDataRequestMinimumTimestamp);
     }
 
 
@@ -187,7 +197,7 @@ 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) {
@@ -195,10 +205,11 @@ 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));
@@ -206,22 +217,24 @@ 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) {
@@ -488,6 +501,45 @@ public class ArbitraryDataFileManager extends Thread {
     }
 
 
+    // Peers requesting QDN data from us
+
+    /**
+     * Add an address string of a peer that is trying to request data from us.
+     * @param peerAddress
+     */
+    public void addRecentDataRequest(String peerAddress) {
+        if (peerAddress == null) {
+            return;
+        }
+
+        Long now = NTP.getTime();
+        if (now == null) {
+            return;
+        }
+
+        // Make sure to remove the port, since it isn't guaranteed to match next time
+        String[] parts = peerAddress.split(":");
+        if (parts.length == 0) {
+            return;
+        }
+        String host = parts[0];
+        if (!InetAddresses.isInetAddress(host)) {
+            // Invalid host
+            return;
+        }
+
+        this.recentDataRequests.put(host, now);
+    }
+
+    public boolean isPeerRequestingData(String peerAddressWithoutPort) {
+        return this.recentDataRequests.containsKey(peerAddressWithoutPort);
+    }
+
+    public boolean hasPendingDataRequest() {
+        return !this.recentDataRequests.isEmpty();
+    }
+
+
     // Network handlers
 
     public void onNetworkGetArbitraryDataFileMessage(Peer peer, Message message) {

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

@@ -47,6 +47,9 @@ public class ArbitraryDataManager extends Thread {
 	/** Maximum time to hold direct peer connection information */
 	public static final long ARBITRARY_DIRECT_CONNECTION_INFO_TIMEOUT = 2 * 60 * 1000L; // ms
 
+	/** Maximum time to hold information about recent data requests that we can fulfil */
+	public static final long ARBITRARY_RECENT_DATA_REQUESTS_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;
 

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

@@ -22,8 +22,7 @@ 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;
+import static org.qortal.controller.arbitrary.ArbitraryDataFileListManager.*;
 
 public class ArbitraryMetadataManager {
 
@@ -338,9 +337,12 @@ public class ArbitraryMetadataManager {
                 Peer requestingPeer = request.getB();
                 if (requestingPeer != null) {
 
+                    ArbitraryMetadataMessage forwardArbitraryMetadataMessage = new ArbitraryMetadataMessage(signature, arbitraryMetadataMessage.getArbitraryMetadataFile());
+                    forwardArbitraryMetadataMessage.setId(arbitraryMetadataMessage.getId());
+
                     // Forward to requesting peer
                     LOGGER.debug("Forwarding metadata to requesting peer: {}", requestingPeer);
-                    if (!requestingPeer.sendMessage(arbitraryMetadataMessage)) {
+                    if (!requestingPeer.sendMessage(forwardArbitraryMetadataMessage)) {
                         requestingPeer.disconnect("failed to forward arbitrary metadata");
                     }
                 }
@@ -423,8 +425,7 @@ public class ArbitraryMetadataManager {
             // In relay mode - so ask our other peers if they have it
 
             long requestTime = getArbitraryMetadataMessage.getRequestTime();
-            int requestHops = getArbitraryMetadataMessage.getRequestHops();
-            getArbitraryMetadataMessage.setRequestHops(++requestHops);
+            int requestHops = getArbitraryMetadataMessage.getRequestHops() + 1;
             long totalRequestTime = now - requestTime;
 
             if (totalRequestTime < RELAY_REQUEST_MAX_DURATION) {
@@ -432,11 +433,14 @@ public class ArbitraryMetadataManager {
                 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);
+                    relayGetArbitraryMetadataMessage.setId(message.getId());
+
                     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 : getArbitraryMetadataMessage);
+                            broadcastPeer ->
+                                    !broadcastPeer.isAtLeastVersion(RELAY_MIN_PEER_VERSION) ? null :
+                                    broadcastPeer == peer || Objects.equals(broadcastPeer.getPeerData().getAddress().getHost(), peer.getPeerData().getAddress().getHost()) ? null : relayGetArbitraryMetadataMessage);
 
                 }
                 else {

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

@@ -19,6 +19,11 @@ public class AtStatesPruner implements Runnable {
 	public void run() {
 		Thread.currentThread().setName("AT States pruner");
 
+		if (Settings.getInstance().isLite()) {
+			// Nothing to prune in lite mode
+			return;
+		}
+
 		boolean archiveMode = false;
 		if (!Settings.getInstance().isTopOnly()) {
 			// Top-only mode isn't enabled, but we might want to prune for the purposes of archiving

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

@@ -19,6 +19,11 @@ public class AtStatesTrimmer implements Runnable {
 	public void run() {
 		Thread.currentThread().setName("AT States trimmer");
 
+		if (Settings.getInstance().isLite()) {
+			// Nothing to trim in lite mode
+			return;
+		}
+
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			int trimStartHeight = repository.getATRepository().getAtTrimHeight();
 

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

@@ -21,7 +21,7 @@ public class BlockArchiver implements Runnable {
 	public void run() {
 		Thread.currentThread().setName("Block archiver");
 
-		if (!Settings.getInstance().isArchiveEnabled()) {
+		if (!Settings.getInstance().isArchiveEnabled() || Settings.getInstance().isLite()) {
 			return;
 		}
 

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

@@ -19,6 +19,11 @@ public class BlockPruner implements Runnable {
 	public void run() {
 		Thread.currentThread().setName("Block pruner");
 
+		if (Settings.getInstance().isLite()) {
+			// Nothing to prune in lite mode
+			return;
+		}
+
 		boolean archiveMode = false;
 		if (!Settings.getInstance().isTopOnly()) {
 			// Top-only mode isn't enabled, but we might want to prune for the purposes of archiving

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

@@ -107,7 +107,7 @@ public class NamesDatabaseIntegrityCheck {
                     BuyNameTransactionData buyNameTransactionData = (BuyNameTransactionData) currentTransaction;
                     Name nameObj = new Name(repository, buyNameTransactionData.getName());
                     if (nameObj != null && nameObj.getNameData() != null) {
-                        nameObj.buy(buyNameTransactionData);
+                        nameObj.buy(buyNameTransactionData, false);
                         modificationCount++;
                         LOGGER.trace("Processed BUY_NAME transaction for name {}", name);
                     }

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

@@ -21,6 +21,11 @@ public class OnlineAccountsSignaturesTrimmer implements Runnable {
 	public void run() {
 		Thread.currentThread().setName("Online Accounts trimmer");
 
+		if (Settings.getInstance().isLite()) {
+			// Nothing to trim in lite mode
+			return;
+		}
+
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			// Don't even start trimming until initial rush has ended
 			Thread.sleep(INITIAL_SLEEP_PERIOD);

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/TradeBot.java

@@ -94,12 +94,14 @@ public class TradeBot implements Listener {
 	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);
 	}
 
@@ -240,8 +242,8 @@ public class TradeBot implements Listener {
 		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);
+		// Don't process trade bots or broadcast presence timestamps if our chain is more than 60 minutes old
+		final Long minLatestBlockTimestamp = NTP.getTime() - (60 * 60 * 1000L);
 		if (!Controller.getInstance().isUpToDate(minLatestBlockTimestamp))
 			return;
 
@@ -290,7 +292,7 @@ public class TradeBot implements Listener {
 	}
 
 	public static byte[] deriveTradeNativePublicKey(byte[] privateKey) {
-		return PrivateKeyAccount.toPublicKey(privateKey);
+		return Crypto.toPublicKey(privateKey);
 	}
 
 	public static byte[] deriveTradeForeignPublicKey(byte[] privateKey) {

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

@@ -7,6 +7,7 @@ import java.util.Map;
 
 import org.bitcoinj.core.Context;
 import org.bitcoinj.core.NetworkParameters;
+import org.bitcoinj.core.Transaction;
 import org.bitcoinj.params.MainNetParams;
 import org.bitcoinj.params.RegTestParams;
 import org.bitcoinj.params.TestNet3Params;
@@ -18,10 +19,12 @@ public class Bitcoin extends Bitcoiny {
 
 	public static final String CURRENCY_CODE = "BTC";
 
+	private static final long MINIMUM_ORDER_AMOUNT = 100000; // 0.001 BTC minimum order, due to high fees
+
 	// Temporary values until a dynamic fee system is written.
 	private static final long OLD_FEE_AMOUNT = 4_000L; // Not 5000 so that existing P2SH-B can output 1000, avoiding dust issue, leaving 4000 for fees.
 	private static final long NEW_FEE_TIMESTAMP = 1598280000000L; // milliseconds since epoch
-	private static final long NEW_FEE_AMOUNT = 10_000L;
+	private static final long NEW_FEE_AMOUNT = 6_000L;
 
 	private static final long NON_MAINNET_FEE = 1000L; // enough for TESTNET3 and should be OK for REGTEST
 
@@ -182,6 +185,11 @@ public class Bitcoin extends Bitcoiny {
 		instance = null;
 	}
 
+	@Override
+	public long getMinimumOrderAmount() {
+		return MINIMUM_ORDER_AMOUNT;
+	}
+
 	// Actual useful methods for use by other classes
 
 	/**
@@ -195,4 +203,17 @@ public class Bitcoin extends Bitcoiny {
 		return this.bitcoinNet.getP2shFee(timestamp);
 	}
 
+	/**
+ 	* Returns bitcoinj transaction sending <tt>amount</tt> to <tt>recipient</tt> using 20 sat/byte fee.
+ 	*
+ 	* @param xprv58 BIP32 private key
+ 	* @param recipient P2PKH address
+ 	* @param amount unscaled amount
+ 	* @return transaction, or null if insufficient funds
+ 	*/
+	@Override
+	public Transaction buildSpend(String xprv58, String recipient, long amount) {
+		return buildSpend(xprv58, recipient, amount, 20L);
+	}
+
 }

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

@@ -375,7 +375,7 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 
 	public Long getWalletBalanceFromTransactions(String key58) throws ForeignBlockchainException {
 		long balance = 0;
-		Comparator<SimpleTransaction> oldestTimestampFirstComparator = Comparator.comparingInt(SimpleTransaction::getTimestamp);
+		Comparator<SimpleTransaction> oldestTimestampFirstComparator = Comparator.comparingLong(SimpleTransaction::getTimestamp);
 		List<SimpleTransaction> transactions = getWalletTransactions(key58).stream().sorted(oldestTimestampFirstComparator).collect(Collectors.toList());
 		for (SimpleTransaction transaction : transactions) {
 			balance += transaction.getTotalAmount();
@@ -455,7 +455,7 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 				// Process new keys
 			} while (true);
 
-			Comparator<SimpleTransaction> newestTimestampFirstComparator = Comparator.comparingInt(SimpleTransaction::getTimestamp).reversed();
+			Comparator<SimpleTransaction> newestTimestampFirstComparator = Comparator.comparingLong(SimpleTransaction::getTimestamp).reversed();
 
 			// Update cache and return
 			transactionsCacheTimestamp = NTP.getTime();
@@ -537,7 +537,8 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 			// 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);
+		long timestampMillis = t.timestamp * 1000L;
+		return new SimpleTransaction(t.txHash, timestampMillis, amount, fee, inputs, outputs);
 	}
 
 	/**

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/SimpleTransaction.java

@@ -7,7 +7,7 @@ import java.util.List;
 @XmlAccessorType(XmlAccessType.FIELD)
 public class SimpleTransaction {
     private String txHash;
-    private Integer timestamp;
+    private Long timestamp;
     private long totalAmount;
     private long feeAmount;
     private List<Input> inputs;
@@ -74,7 +74,7 @@ public class SimpleTransaction {
     public SimpleTransaction() {
     }
 
-    public SimpleTransaction(String txHash, Integer timestamp, long totalAmount, long feeAmount, List<Input> inputs, List<Output> outputs) {
+    public SimpleTransaction(String txHash, Long timestamp, long totalAmount, long feeAmount, List<Input> inputs, List<Output> outputs) {
         this.txHash = txHash;
         this.timestamp = timestamp;
         this.totalAmount = totalAmount;
@@ -87,7 +87,7 @@ public class SimpleTransaction {
         return txHash;
     }
 
-    public Integer getTimestamp() {
+    public Long getTimestamp() {
         return timestamp;
     }
 

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();
 		}
 	},
 
@@ -59,6 +59,20 @@ public enum SupportedBlockchain {
 		}
 	},
 
+	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)
 		)) {

src/main/java/org/qortal/crypto/BouncyCastle25519.java

@@ -1,99 +0,0 @@
-package org.qortal.crypto;
-
-import java.lang.reflect.Constructor;
-import java.lang.reflect.Field;
-import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Method;
-import java.util.Arrays;
-
-import org.bouncycastle.crypto.Digest;
-import org.bouncycastle.math.ec.rfc7748.X25519;
-import org.bouncycastle.math.ec.rfc7748.X25519Field;
-import org.bouncycastle.math.ec.rfc8032.Ed25519;
-
-/** Additions to BouncyCastle providing Ed25519 to X25519 key conversion. */
-public class BouncyCastle25519 {
-
-	private static final Class<?> pointAffineClass;
-	private static final Constructor<?> pointAffineCtor;
-	private static final Method decodePointVarMethod;
-	private static final Field yField;
-
-	static {
-		try {
-			Class<?> ed25519Class = Ed25519.class;
-			pointAffineClass = Arrays.stream(ed25519Class.getDeclaredClasses()).filter(clazz -> clazz.getSimpleName().equals("PointAffine")).findFirst().get();
-			if (pointAffineClass == null)
-				throw new ClassNotFoundException("Can't locate PointExt inner class inside Ed25519");
-
-			decodePointVarMethod = ed25519Class.getDeclaredMethod("decodePointVar", byte[].class, int.class, boolean.class, pointAffineClass);
-			decodePointVarMethod.setAccessible(true);
-
-			pointAffineCtor = pointAffineClass.getDeclaredConstructors()[0];
-			pointAffineCtor.setAccessible(true);
-
-			yField = pointAffineClass.getDeclaredField("y");
-			yField.setAccessible(true);
-		} catch (NoSuchMethodException | SecurityException | IllegalArgumentException | NoSuchFieldException | ClassNotFoundException e) {
-			throw new RuntimeException("Can't initialize BouncyCastle25519 shim", e);
-		}
-	}
-
-	private static int[] obtainYFromPublicKey(byte[] ed25519PublicKey) {
-		try {
-			Object pA = pointAffineCtor.newInstance();
-
-			Boolean result = (Boolean) decodePointVarMethod.invoke(null, ed25519PublicKey, 0, true, pA);
-			if (result == null || !result)
-				return null;
-
-			return (int[]) yField.get(pA);
-		} catch (SecurityException | InstantiationException | IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
-			throw new RuntimeException("Can't reflect into BouncyCastle", e);
-		}
-	}
-
-	public static byte[] toX25519PublicKey(byte[] ed25519PublicKey) {
-		int[] one = new int[X25519Field.SIZE];
-		X25519Field.one(one);
-
-		int[] y = obtainYFromPublicKey(ed25519PublicKey);
-
-		int[] oneMinusY = new int[X25519Field.SIZE];
-		X25519Field.sub(one, y, oneMinusY);
-
-		int[] onePlusY = new int[X25519Field.SIZE];
-		X25519Field.add(one, y, onePlusY);
-
-		int[] oneMinusYInverted = new int[X25519Field.SIZE];
-		X25519Field.inv(oneMinusY, oneMinusYInverted);
-
-		int[] u = new int[X25519Field.SIZE];
-		X25519Field.mul(onePlusY, oneMinusYInverted, u);
-
-		X25519Field.normalize(u);
-
-		byte[] x25519PublicKey = new byte[X25519.SCALAR_SIZE];
-		X25519Field.encode(u, x25519PublicKey, 0);
-
-		return x25519PublicKey;
-	}
-
-	public static byte[] toX25519PrivateKey(byte[] ed25519PrivateKey) {
-		Digest d = Ed25519.createPrehash();
-		byte[] h = new byte[d.getDigestSize()];
-
-		d.update(ed25519PrivateKey, 0, ed25519PrivateKey.length);
-		d.doFinal(h, 0);
-
-		byte[] s = new byte[X25519.SCALAR_SIZE];
-
-		System.arraycopy(h, 0, s, 0, X25519.SCALAR_SIZE);
-		s[0] &= 0xF8;
-		s[X25519.SCALAR_SIZE - 1] &= 0x7F;
-		s[X25519.SCALAR_SIZE - 1] |= 0x40;
-
-		return s;
-	}
-
-}

src/main/java/org/qortal/crypto/Crypto.java

@@ -253,6 +253,10 @@ public abstract class Crypto {
 		return false;
 	}
 
+	public static byte[] toPublicKey(byte[] privateKey) {
+		return new Ed25519PrivateKeyParameters(privateKey, 0).generatePublicKey().getEncoded();
+	}
+
 	public static boolean verify(byte[] publicKey, byte[] signature, byte[] message) {
 		try {
 			return Ed25519.verify(signature, 0, publicKey, 0, message, 0, message.length);
@@ -264,16 +268,24 @@ public abstract class Crypto {
 	public static byte[] sign(Ed25519PrivateKeyParameters edPrivateKeyParams, byte[] message) {
 		byte[] signature = new byte[SIGNATURE_LENGTH];
 
-		edPrivateKeyParams.sign(Ed25519.Algorithm.Ed25519, edPrivateKeyParams.generatePublicKey(), null, message, 0, message.length, signature, 0);
+		edPrivateKeyParams.sign(Ed25519.Algorithm.Ed25519,null, message, 0, message.length, signature, 0);
+
+		return signature;
+	}
+
+	public static byte[] sign(byte[] privateKey, byte[] message) {
+		byte[] signature = new byte[SIGNATURE_LENGTH];
+
+		new Ed25519PrivateKeyParameters(privateKey, 0).sign(Ed25519.Algorithm.Ed25519,null, message, 0, message.length, signature, 0);
 
 		return signature;
 	}
 
 	public static byte[] getSharedSecret(byte[] privateKey, byte[] publicKey) {
-		byte[] x25519PrivateKey = BouncyCastle25519.toX25519PrivateKey(privateKey);
+		byte[] x25519PrivateKey = Qortal25519Extras.toX25519PrivateKey(privateKey);
 		X25519PrivateKeyParameters xPrivateKeyParams = new X25519PrivateKeyParameters(x25519PrivateKey, 0);
 
-		byte[] x25519PublicKey = BouncyCastle25519.toX25519PublicKey(publicKey);
+		byte[] x25519PublicKey = Qortal25519Extras.toX25519PublicKey(publicKey);
 		X25519PublicKeyParameters xPublicKeyParams = new X25519PublicKeyParameters(x25519PublicKey, 0);
 
 		byte[] sharedSecret = new byte[SHARED_SECRET_LENGTH];
@@ -281,5 +293,4 @@ public abstract class Crypto {
 
 		return sharedSecret;
 	}
-
 }

src/main/java/org/qortal/crypto/Qortal25519Extras.java

@@ -0,0 +1,234 @@
+package org.qortal.crypto;
+
+import org.bouncycastle.crypto.Digest;
+import org.bouncycastle.crypto.digests.SHA512Digest;
+import org.bouncycastle.math.ec.rfc7748.X25519;
+import org.bouncycastle.math.ec.rfc7748.X25519Field;
+import org.bouncycastle.math.ec.rfc8032.Ed25519;
+import org.bouncycastle.math.raw.Nat256;
+
+import java.security.SecureRandom;
+import java.util.Arrays;
+import java.util.Collection;
+
+/**
+ * Additions to BouncyCastle providing:
+ * <p></p>
+ * <ul>
+ *     <li>Ed25519 to X25519 key conversion</li>
+ *     <li>Aggregate public keys</li>
+ *     <li>Aggregate signatures</li>
+ * </ul>
+ */
+public abstract class Qortal25519Extras extends BouncyCastleEd25519 {
+
+	private static final SecureRandom SECURE_RANDOM = new SecureRandom();
+
+	public static byte[] toX25519PublicKey(byte[] ed25519PublicKey) {
+		int[] one = new int[X25519Field.SIZE];
+		X25519Field.one(one);
+
+		PointAffine pA = new PointAffine();
+		if (!decodePointVar(ed25519PublicKey, 0, true, pA))
+			return null;
+
+		int[] y = pA.y;
+
+		int[] oneMinusY = new int[X25519Field.SIZE];
+		X25519Field.sub(one, y, oneMinusY);
+
+		int[] onePlusY = new int[X25519Field.SIZE];
+		X25519Field.add(one, y, onePlusY);
+
+		int[] oneMinusYInverted = new int[X25519Field.SIZE];
+		X25519Field.inv(oneMinusY, oneMinusYInverted);
+
+		int[] u = new int[X25519Field.SIZE];
+		X25519Field.mul(onePlusY, oneMinusYInverted, u);
+
+		X25519Field.normalize(u);
+
+		byte[] x25519PublicKey = new byte[X25519.SCALAR_SIZE];
+		X25519Field.encode(u, x25519PublicKey, 0);
+
+		return x25519PublicKey;
+	}
+
+	public static byte[] toX25519PrivateKey(byte[] ed25519PrivateKey) {
+		Digest d = Ed25519.createPrehash();
+		byte[] h = new byte[d.getDigestSize()];
+
+		d.update(ed25519PrivateKey, 0, ed25519PrivateKey.length);
+		d.doFinal(h, 0);
+
+		byte[] s = new byte[X25519.SCALAR_SIZE];
+
+		System.arraycopy(h, 0, s, 0, X25519.SCALAR_SIZE);
+		s[0] &= 0xF8;
+		s[X25519.SCALAR_SIZE - 1] &= 0x7F;
+		s[X25519.SCALAR_SIZE - 1] |= 0x40;
+
+		return s;
+	}
+
+	// Mostly for test support
+	public static PointAccum newPointAccum() {
+		return new PointAccum();
+	}
+
+	public static byte[] aggregatePublicKeys(Collection<byte[]> publicKeys) {
+		PointAccum rAccum = null;
+
+		for (byte[] publicKey : publicKeys) {
+			PointAffine pA = new PointAffine();
+			if (!decodePointVar(publicKey, 0, false, pA))
+				// Failed to decode
+				return null;
+
+			if (rAccum == null) {
+				rAccum = new PointAccum();
+				pointCopy(pA, rAccum);
+			} else {
+				pointAdd(pointCopy(pA), rAccum);
+			}
+		}
+
+		byte[] publicKey = new byte[SCALAR_BYTES];
+		if (0 == encodePoint(rAccum, publicKey, 0))
+			// Failed to encode
+			return null;
+
+		return publicKey;
+	}
+
+	public static byte[] aggregateSignatures(Collection<byte[]> signatures) {
+		// Signatures are (R, s)
+		// R is a point
+		// s is a scalar
+		PointAccum rAccum = null;
+		int[] sAccum = new int[SCALAR_INTS];
+
+		byte[] rEncoded = new byte[POINT_BYTES];
+		int[] sPart = new int[SCALAR_INTS];
+		for (byte[] signature : signatures) {
+			System.arraycopy(signature,0, rEncoded, 0, rEncoded.length);
+
+			PointAffine pA = new PointAffine();
+			if (!decodePointVar(rEncoded, 0, false, pA))
+				// Failed to decode
+				return null;
+
+			if (rAccum == null) {
+				rAccum = new PointAccum();
+				pointCopy(pA, rAccum);
+
+				decode32(signature, rEncoded.length, sAccum, 0, SCALAR_INTS);
+			} else {
+				pointAdd(pointCopy(pA), rAccum);
+
+				decode32(signature, rEncoded.length, sPart, 0, SCALAR_INTS);
+				Nat256.addTo(sPart, sAccum);
+
+				// "mod L" on sAccum
+				if (Nat256.gte(sAccum, L))
+					Nat256.subFrom(L, sAccum);
+			}
+		}
+
+		byte[] signature = new byte[SIGNATURE_SIZE];
+		if (0 == encodePoint(rAccum, signature, 0))
+			// Failed to encode
+			return null;
+
+		for (int i = 0; i < sAccum.length; ++i) {
+			encode32(sAccum[i], signature, POINT_BYTES + i * 4);
+		}
+
+		return signature;
+	}
+
+	public static byte[] signForAggregation(byte[] privateKey, byte[] message) {
+		// Very similar to BouncyCastle's implementation except we use secure random nonce and different hash
+		Digest d = new SHA512Digest();
+		byte[] h = new byte[d.getDigestSize()];
+
+		d.reset();
+		d.update(privateKey, 0, privateKey.length);
+		d.doFinal(h, 0);
+
+		byte[] sH = new byte[SCALAR_BYTES];
+		pruneScalar(h, 0, sH);
+
+		byte[] publicKey = new byte[SCALAR_BYTES];
+		scalarMultBaseEncoded(sH, publicKey, 0);
+
+		byte[] rSeed = new byte[d.getDigestSize()];
+		SECURE_RANDOM.nextBytes(rSeed);
+
+		byte[] r = new byte[SCALAR_BYTES];
+		pruneScalar(rSeed, 0, r);
+
+		byte[] R = new byte[POINT_BYTES];
+		scalarMultBaseEncoded(r, R, 0);
+
+		d.reset();
+		d.update(message, 0, message.length);
+		d.doFinal(h, 0);
+		byte[] k = reduceScalar(h);
+
+		byte[] s = calculateS(r, k, sH);
+
+		byte[] signature = new byte[SIGNATURE_SIZE];
+		System.arraycopy(R, 0, signature, 0, POINT_BYTES);
+		System.arraycopy(s, 0, signature, POINT_BYTES, SCALAR_BYTES);
+
+		return signature;
+	}
+
+	public static boolean verifyAggregated(byte[] publicKey, byte[] signature, byte[] message) {
+		byte[] R = Arrays.copyOfRange(signature, 0, POINT_BYTES);
+
+		byte[] s = Arrays.copyOfRange(signature, POINT_BYTES, POINT_BYTES + SCALAR_BYTES);
+
+		if (!checkPointVar(R))
+			// R out of bounds
+			return false;
+
+		if (!checkScalarVar(s))
+			// s out of bounds
+			return false;
+
+		byte[] S = new byte[POINT_BYTES];
+		scalarMultBaseEncoded(s, S, 0);
+
+		PointAffine pA = new PointAffine();
+		if (!decodePointVar(publicKey, 0, true, pA))
+			// Failed to decode
+			return false;
+
+		Digest d = new SHA512Digest();
+		byte[] h = new byte[d.getDigestSize()];
+
+		d.update(message, 0, message.length);
+		d.doFinal(h, 0);
+
+		byte[] k = reduceScalar(h);
+
+		int[] nS = new int[SCALAR_INTS];
+		decodeScalar(s, 0, nS);
+
+		int[] nA = new int[SCALAR_INTS];
+		decodeScalar(k, 0, nA);
+
+		/*PointAccum*/
+		PointAccum pR = new PointAccum();
+		scalarMultStrausVar(nS, nA, pA, pR);
+
+		byte[] check = new byte[POINT_BYTES];
+		if (0 == encodePoint(pR, check, 0))
+			// Failed to encode
+			return false;
+
+		return Arrays.equals(check, R);
+	}
+}

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

@@ -5,6 +5,7 @@ import java.util.Arrays;
 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 org.qortal.account.PublicKeyAccount;
 
@@ -16,6 +17,9 @@ public class OnlineAccountData {
 	protected byte[] signature;
 	protected byte[] publicKey;
 
+	@XmlTransient
+	private int hash;
+
 	// Constructors
 
 	// necessary for JAXB serialization
@@ -62,20 +66,23 @@ public class OnlineAccountData {
 		if (otherOnlineAccountData.timestamp != this.timestamp)
 			return false;
 
-		// Signature more likely to be unique than public key
-		if (!Arrays.equals(otherOnlineAccountData.signature, this.signature))
-			return false;
-
 		if (!Arrays.equals(otherOnlineAccountData.publicKey, this.publicKey))
 			return false;
 
+		// We don't compare signature because it's not our remit to verify and newer aggregate signatures use random nonces
+
 		return true;
 	}
 
 	@Override
 	public int hashCode() {
-		// Pretty lazy implementation
-		return (int) this.timestamp;
+		int h = this.hash;
+		if (h == 0) {
+			this.hash = h = Long.hashCode(this.timestamp)
+					^ Arrays.hashCode(this.publicKey);
+			// We don't use signature because newer aggregate signatures use random nonces
+		}
+		return h;
 	}
 
 }

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

@@ -47,12 +47,12 @@ public class Gui {
 		this.splashFrame = SplashFrame.getInstance();
 	}
 
-	protected static BufferedImage loadImage(String resourceName) throws IOException {
+	protected static BufferedImage loadImage(String resourceName) {
 		try (InputStream in = Gui.class.getResourceAsStream("/images/" + resourceName)) {
 			return ImageIO.read(in);
 		} catch (IllegalArgumentException | IOException | ServiceConfigurationError e) {
 			LOGGER.warn(String.format("Couldn't locate image resource \"images/%s\"", resourceName));
-			throw new IOException(String.format("Couldn't locate image resource \"images/%s\"", resourceName));
+			return null;
 		}
 	}
 

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

@@ -1,7 +1,6 @@
 package org.qortal.gui;
 
 import java.awt.*;
-import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 import java.awt.image.BufferedImage;
@@ -30,23 +29,18 @@ public class SplashFrame {
 		private JLabel statusLabel;
 
 		public SplashPanel() {
-			try {
-				image = Gui.loadImage(defaultSplash);
-
-				// Add logo
-				JLabel imageLabel = new JLabel(new ImageIcon(image));
-				imageLabel.setSize(new Dimension(300, 300));
-				add(imageLabel);
-			}
-			catch (IOException e) {
-				LOGGER.warn("Unable to load splash panel image");
-			}
+			image = Gui.loadImage(defaultSplash);
 
 			setOpaque(true);
 			setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
 			setBorder(new EmptyBorder(10, 10, 10, 10));
 			setBackground(Color.BLACK);
 
+			// Add logo
+			JLabel imageLabel = new JLabel(new ImageIcon(image));
+			imageLabel.setSize(new Dimension(300, 300));
+			add(imageLabel);
+
 			// Add spacing
 			add(Box.createRigidArea(new Dimension(0, 16)));
 
@@ -81,20 +75,15 @@ public class SplashFrame {
 
 		this.splashDialog = new JFrame();
 
-		try {
-			List<Image> icons = new ArrayList<>();
-			icons.add(Gui.loadImage("icons/icon16.png"));
-			icons.add(Gui.loadImage("icons/qortal_ui_tray_synced.png"));
-			icons.add(Gui.loadImage("icons/qortal_ui_tray_syncing_time-alt.png"));
-			icons.add(Gui.loadImage("icons/qortal_ui_tray_minting.png"));
-			icons.add(Gui.loadImage("icons/qortal_ui_tray_syncing.png"));
-			icons.add(Gui.loadImage("icons/icon64.png"));
-			icons.add(Gui.loadImage("icons/Qlogo_128.png"));
-			this.splashDialog.setIconImages(icons);
-		}
-		catch (IOException e) {
-			LOGGER.warn("Unable to load splash frame icons");
-		}
+		List<Image> icons = new ArrayList<>();
+		icons.add(Gui.loadImage("icons/icon16.png"));
+		icons.add(Gui.loadImage("icons/qortal_ui_tray_synced.png"));
+		icons.add(Gui.loadImage("icons/qortal_ui_tray_syncing_time-alt.png"));
+		icons.add(Gui.loadImage("icons/qortal_ui_tray_minting.png"));
+		icons.add(Gui.loadImage("icons/qortal_ui_tray_syncing.png"));
+		icons.add(Gui.loadImage("icons/icon64.png"));
+		icons.add(Gui.loadImage("icons/Qlogo_128.png"));
+		this.splashDialog.setIconImages(icons);
 
 		this.splashPanel = new SplashPanel();
 		this.splashDialog.getContentPane().add(this.splashPanel);

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

@@ -23,6 +23,7 @@ import java.util.List;
 
 import javax.swing.JDialog;
 import javax.swing.JMenuItem;
+import javax.swing.JOptionPane;
 import javax.swing.JPopupMenu;
 import javax.swing.SwingWorker;
 import javax.swing.event.PopupMenuEvent;
@@ -61,13 +62,7 @@ public class SysTray {
 		this.popupMenu = createJPopupMenu();
 
 		// Build TrayIcon without AWT PopupMenu (which doesn't support Unicode)...
-		try {
-			this.trayIcon = new TrayIcon(Gui.loadImage("icons/qortal_ui_tray_synced.png"), "qortal", null);
-		}
-		catch (IOException e) {
-			LOGGER.warn("Unable to load system tray icon");
-			return;
-		}
+		this.trayIcon = new TrayIcon(Gui.loadImage("icons/qortal_ui_tray_synced.png"), "qortal", null);
 		// ...and attach mouse listener instead so we can use JPopupMenu (which does support Unicode)
 		this.trayIcon.addMouseListener(new MouseAdapter() {
 			@Override
@@ -184,6 +179,14 @@ public class SysTray {
 			menu.add(syncTime);
 		}
 
+		JMenuItem about = new JMenuItem(Translator.INSTANCE.translate("SysTray", "BUILD_VERSION"));
+		about.addActionListener(actionEvent -> {
+			destroyHiddenDialog();
+
+			JOptionPane.showMessageDialog(null,"Qortal Core\n" + Translator.INSTANCE.translate("SysTray", "BUILD_VERSION") + ":\n" + Controller.getInstance().getVersionStringWithoutPrefix(),"Qortal Core",1);
+		});
+		menu.add(about);
+
 		JMenuItem exit = new JMenuItem(Translator.INSTANCE.translate("SysTray", "EXIT"));
 		exit.addActionListener(actionEvent -> {
 			destroyHiddenDialog();

src/main/java/org/qortal/naming/Name.java

@@ -195,7 +195,7 @@ public class Name {
 		this.repository.getNameRepository().save(this.nameData);
 	}
 
-	public void buy(BuyNameTransactionData buyNameTransactionData) throws DataException {
+	public void buy(BuyNameTransactionData buyNameTransactionData, boolean modifyBalances) throws DataException {
 		// Save previous name-changing reference in this transaction's data
 		// Caller is expected to save
 		buyNameTransactionData.setNameReference(this.nameData.getReference());
@@ -203,15 +203,20 @@ public class Name {
 		// Mark not for-sale but leave price in case we want to orphan
 		this.nameData.setIsForSale(false);
 
-		// Update seller's balance
-		Account seller = new Account(this.repository, this.nameData.getOwner());
-		seller.modifyAssetBalance(Asset.QORT, buyNameTransactionData.getAmount());
+		if (modifyBalances) {
+			// Update seller's balance
+			Account seller = new Account(this.repository, this.nameData.getOwner());
+			seller.modifyAssetBalance(Asset.QORT, buyNameTransactionData.getAmount());
+		}
 
 		// Set new owner
 		Account buyer = new PublicKeyAccount(this.repository, buyNameTransactionData.getBuyerPublicKey());
 		this.nameData.setOwner(buyer.getAddress());
-		// Update buyer's balance
-		buyer.modifyAssetBalance(Asset.QORT, - buyNameTransactionData.getAmount());
+
+		if (modifyBalances) {
+			// Update buyer's balance
+			buyer.modifyAssetBalance(Asset.QORT, -buyNameTransactionData.getAmount());
+		}
 
 		// Set name-changing reference to this transaction
 		this.nameData.setReference(buyNameTransactionData.getSignature());

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;

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

@@ -8,11 +8,13 @@ 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 +34,7 @@ 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 +44,8 @@ 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.
      */
@@ -122,14 +124,8 @@ public class Network {
     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();
 
@@ -137,6 +133,8 @@ public class Network {
     private String ourExternalIpAddress = null;
     private int ourExternalPort = Settings.getInstance().getListenPort();
 
+    private volatile boolean isShuttingDown = false;
+
     // Constructors
 
     private Network() {
@@ -170,7 +168,7 @@ 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);
@@ -180,7 +178,8 @@ 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";
@@ -214,12 +213,16 @@ public class Network {
 
     // 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() {
@@ -257,6 +260,18 @@ public class Network {
         return this.immutableConnectedPeers;
     }
 
+    public List<Peer> getImmutableConnectedDataPeers() {
+        return this.getImmutableConnectedPeers().stream()
+                .filter(p -> p.isDataPeer())
+                .collect(Collectors.toList());
+    }
+
+    public List<Peer> getImmutableConnectedNonDataPeers() {
+        return this.getImmutableConnectedPeers().stream()
+                .filter(p -> !p.isDataPeer())
+                .collect(Collectors.toList());
+    }
+
     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)
@@ -323,6 +338,7 @@ public class Network {
                         // Add this signature to the list of pending requests for this peer
                         LOGGER.info("Making connection to peer {} to request files for signature {}...", peerAddressString, Base58.encode(signature));
                         Peer peer = new Peer(peerData);
+                        peer.setIsDataPeer(true);
                         peer.addPendingSignatureRequest(signature);
                         return this.connectPeer(peer);
                         // If connection (and handshake) is successful, data will automatically be requested
@@ -453,6 +469,13 @@ public class Network {
 
     class NetworkProcessor extends ExecuteProduceConsume {
 
+        private final Logger LOGGER = LogManager.getLogger(NetworkProcessor.class);
+
+        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);
         }
@@ -494,43 +517,23 @@ public class Network {
         }
 
         private Task maybeProducePeerMessageTask() {
-            for (Peer peer : getImmutableConnectedPeers()) {
-                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 : getImmutableHandshakedPeers()) {
-                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;
             }
 
@@ -538,7 +541,7 @@ public class Network {
                 return null;
             }
 
-            nextConnectTaskTimestamp = now + 1000L;
+            nextConnectTaskTimestamp.set(now + 1000L);
 
             Peer targetPeer = getConnectablePeer(now);
             if (targetPeer == null) {
@@ -550,66 +553,15 @@ 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?
@@ -630,91 +582,73 @@ 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;
-            }
-
-            if (getImmutableConnectedPeers().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.addConnectedPeer(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])) {
@@ -750,8 +684,9 @@ public class Network {
             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);
+            // 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);
 
@@ -766,6 +701,7 @@ public class Network {
             // Pick candidate
             PeerData peerData = peers.get(peerIndex);
             Peer newPeer = new Peer(peerData);
+            newPeer.setIsDataPeer(false);
 
             // Update connection attempt info
             peerData.setLastAttempted(now);
@@ -781,8 +717,12 @@ 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;
         }
@@ -797,7 +737,7 @@ public class Network {
         return true;
     }
 
-    private Peer getPeerFromChannel(SocketChannel socketChannel) {
+    public Peer getPeerFromChannel(SocketChannel socketChannel) {
         for (Peer peer : this.getImmutableConnectedPeers()) {
             if (peer.getSocketChannel() == socketChannel) {
                 return peer;
@@ -830,7 +770,74 @@ 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();
@@ -856,8 +863,6 @@ 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 {
@@ -865,6 +870,25 @@ public class Network {
         }
 
         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) {
@@ -1062,11 +1086,13 @@ public class Network {
         // (If inbound sent anything here, it's possible it could be processed out-of-order with handshake message).
 
         if (peer.isOutbound()) {
-            // Send our height
-            Message heightMessage = buildHeightMessage(peer, Controller.getInstance().getChainTip());
-            if (!peer.sendMessage(heightMessage)) {
-                peer.disconnect("failed to send height/info");
-                return;
+            if (!Settings.getInstance().isLite()) {
+                // Send our height
+                Message heightMessage = buildHeightMessage(peer, Controller.getInstance().getChainTip());
+                if (!peer.sendMessage(heightMessage)) {
+                    peer.disconnect("failed to send height/info");
+                    return;
+                }
             }
 
             // Send our peers list
@@ -1302,8 +1328,9 @@ public class Network {
         try {
             InetSocketAddress knownAddress = peerAddress.toSocketAddress();
 
-            List<Peer> peers = this.getImmutableConnectedPeers();
-            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");
@@ -1348,17 +1375,26 @@ public class Network {
                 // We attempted to connect within the last day
                 // but we last managed to connect over a week ago.
                 Predicate<PeerData> isNotOldPeer = peerData -> {
-                    if (peerData.getLastAttempted() == null
-                            || peerData.getLastAttempted() < now - OLD_PEER_ATTEMPTED_PERIOD) {
+
+                    // First check if there was a connection attempt within the last day
+                    if (peerData.getLastAttempted() != null
+                            && peerData.getLastAttempted() > now - OLD_PEER_ATTEMPTED_PERIOD) {
+
+                        // There was, so now check if we had a successful connection in the last 7 days
+                        if (peerData.getLastConnected() != null
+                                && peerData.getLastConnected() > now - OLD_PEER_CONNECTION_PERIOD) {
+
+                            // We did, so this is NOT an 'old' peer
+                            return true;
+                        }
+
+                        // Last successful connection was more than 1 week ago - this is an 'old' peer
+                        return false;
+                    }
+                    else {
+                        // Best to wait until we have a connection attempt - assume not an 'old' peer until then
                         return true;
                     }
-
-                    if (peerData.getLastConnected() == null
-                            || peerData.getLastConnected() > now - OLD_PEER_CONNECTION_PERIOD) {
-                        return true;
-                    }
-
-                    return false;
                 };
 
                 // Disregard peers that are NOT 'old'
@@ -1461,54 +1497,27 @@ 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.getImmutableHandshakedPeers(), 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 {
@@ -1527,16 +1536,6 @@ 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.getImmutableConnectedPeers()) {
             peer.shutdown();

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

@@ -11,25 +11,22 @@ 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.message.MessageType;
+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 +45,9 @@ 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)
@@ -68,13 +65,22 @@ public class Peer {
      */
     private boolean isLocal;
 
+    /**
+     * True if connected for the purposes of transfering specific QDN data
+     */
+    private boolean isDataPeer;
+
     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 +104,7 @@ 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 +166,10 @@ 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());
@@ -194,6 +200,14 @@ public class Peer {
         return this.isOutbound;
     }
 
+    public boolean isDataPeer() {
+        return isDataPeer;
+    }
+
+    public void setIsDataPeer(boolean isDataPeer) {
+        this.isDataPeer = isDataPeer;
+    }
+
     public Handshake getHandshakeStatus() {
         synchronized (this.handshakingLock) {
             return this.handshakeStatus;
@@ -211,6 +225,11 @@ public class Peer {
     }
 
     private void generateRandomMaxConnectionAge() {
+        if (this.maxConnectionAge > 0L) {
+            // Already generated, so we don't want to overwrite the existing value
+            return;
+        }
+
         // Retrieve the min and max connection time from the settings, and calculate the range
         final int minPeerConnectionTime = Settings.getInstance().getMinPeerConnectionTime();
         final int maxPeerConnectionTime = Settings.getInstance().getMaxPeerConnectionTime();
@@ -276,7 +295,7 @@ public class Peer {
         }
     }
 
-    protected void setLastPing(long lastPing) {
+    public void setLastPing(long lastPing) {
         synchronized (this.peerInfoLock) {
             this.lastPing = lastPing;
         }
@@ -346,12 +365,6 @@ 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 +409,14 @@ 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 +424,7 @@ 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 +432,8 @@ 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 +448,7 @@ 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 +466,7 @@ 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()) {
@@ -531,6 +547,10 @@ public class Peer {
                     // adjusting position accordingly, reset limit to capacity
                     this.byteBuffer.compact();
 
+                    // Unsupported message type? Discard with no further processing
+                    if (message.getType() == MessageType.UNSUPPORTED)
+                        continue;
+
                     BlockingQueue<Message> queue = this.replyQueues.get(message.getId());
                     if (queue != null) {
                         // Adding message to queue will unblock thread waiting for response
@@ -556,7 +576,67 @@ 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 +660,7 @@ public class Peer {
         }
 
         // Return a task to process message in queue
-        return () -> Network.getInstance().onMessage(this, nextMessage);
+        return new MessageTask(this, nextMessage);
     }
 
     /**
@@ -605,54 +685,25 @@ 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 +771,7 @@ 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 +785,7 @@ 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) {
@@ -877,6 +916,10 @@ public class Peer {
         return maxConnectionAge;
     }
 
+    public void setMaxConnectionAge(long maxConnectionAge) {
+        this.maxConnectionAge = maxConnectionAge;
+    }
+
     public boolean hasReachedMaxConnectionAge() {
         return this.getConnectionAge() > this.getMaxConnectionAge();
     }

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

@@ -0,0 +1,70 @@
+package org.qortal.network.message;
+
+import com.google.common.primitives.Longs;
+import org.qortal.data.account.AccountBalanceData;
+import org.qortal.transform.Transformer;
+import org.qortal.utils.Base58;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+public class AccountBalanceMessage extends Message {
+
+	private static final int ADDRESS_LENGTH = Transformer.ADDRESS_LENGTH;
+
+	private AccountBalanceData accountBalanceData;
+
+	public AccountBalanceMessage(AccountBalanceData accountBalanceData) {
+		super(MessageType.ACCOUNT_BALANCE);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			// Send raw address instead of base58 encoded
+			byte[] address = Base58.decode(accountBalanceData.getAddress());
+			bytes.write(address);
+
+			bytes.write(Longs.toByteArray(accountBalanceData.getAssetId()));
+
+			bytes.write(Longs.toByteArray(accountBalanceData.getBalance()));
+
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
+
+	public AccountBalanceMessage(int id, AccountBalanceData accountBalanceData) {
+		super(id, MessageType.ACCOUNT_BALANCE);
+
+		this.accountBalanceData = accountBalanceData;
+	}
+
+	public AccountBalanceData getAccountBalanceData() {
+		return this.accountBalanceData;
+	}
+
+
+	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) {
+		byte[] addressBytes = new byte[ADDRESS_LENGTH];
+		byteBuffer.get(addressBytes);
+		String address = Base58.encode(addressBytes);
+
+		long assetId = byteBuffer.getLong();
+
+		long balance = byteBuffer.getLong();
+
+		AccountBalanceData accountBalanceData = new AccountBalanceData(address, assetId, balance);
+		return new AccountBalanceMessage(id, accountBalanceData);
+	}
+
+	public AccountBalanceMessage cloneWithNewId(int newId) {
+		AccountBalanceMessage clone = new AccountBalanceMessage(this.accountBalanceData);
+		clone.setId(newId);
+		return clone;
+	}
+
+}

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

@@ -0,0 +1,93 @@
+package org.qortal.network.message;
+
+import com.google.common.primitives.Ints;
+import org.qortal.data.account.AccountData;
+import org.qortal.transform.Transformer;
+import org.qortal.utils.Base58;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+public class AccountMessage extends Message {
+
+	private static final int ADDRESS_LENGTH = Transformer.ADDRESS_LENGTH;
+	private static final int REFERENCE_LENGTH = Transformer.SIGNATURE_LENGTH;
+	private static final int PUBLIC_KEY_LENGTH = Transformer.PUBLIC_KEY_LENGTH;
+
+	private AccountData accountData;
+
+	public AccountMessage(AccountData accountData) {
+		super(MessageType.ACCOUNT);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			// Send raw address instead of base58 encoded
+			byte[] address = Base58.decode(accountData.getAddress());
+			bytes.write(address);
+
+			bytes.write(accountData.getReference());
+
+			bytes.write(accountData.getPublicKey());
+
+			bytes.write(Ints.toByteArray(accountData.getDefaultGroupId()));
+
+			bytes.write(Ints.toByteArray(accountData.getFlags()));
+
+			bytes.write(Ints.toByteArray(accountData.getLevel()));
+
+			bytes.write(Ints.toByteArray(accountData.getBlocksMinted()));
+
+			bytes.write(Ints.toByteArray(accountData.getBlocksMintedAdjustment()));
+
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
+
+	public AccountMessage(int id, AccountData accountData) {
+		super(id, MessageType.ACCOUNT);
+
+		this.accountData = accountData;
+	}
+
+	public AccountData getAccountData() {
+		return this.accountData;
+	}
+
+	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) {
+		byte[] addressBytes = new byte[ADDRESS_LENGTH];
+		byteBuffer.get(addressBytes);
+		String address = Base58.encode(addressBytes);
+
+		byte[] reference = new byte[REFERENCE_LENGTH];
+		byteBuffer.get(reference);
+
+		byte[] publicKey = new byte[PUBLIC_KEY_LENGTH];
+		byteBuffer.get(publicKey);
+
+		int defaultGroupId = byteBuffer.getInt();
+
+		int flags = byteBuffer.getInt();
+
+		int level = byteBuffer.getInt();
+
+		int blocksMinted = byteBuffer.getInt();
+
+		int blocksMintedAdjustment = byteBuffer.getInt();
+
+		AccountData accountData = new AccountData(address, reference, publicKey, defaultGroupId, flags, level, blocksMinted, blocksMintedAdjustment);
+		return new AccountMessage(id, accountData);
+	}
+
+	public AccountMessage cloneWithNewId(int newId) {
+		AccountMessage clone = new AccountMessage(this.accountData);
+		clone.setId(newId);
+		return clone;
+	}
+
+}

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

@@ -9,38 +9,59 @@ 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 static final int MAX_PEER_ADDRESS_LENGTH = PeerData.MAX_PEER_ADDRESS_SIZE;
-
-	private final byte[] signature;
-	private final List<byte[]> hashes;
+	private byte[] signature;
+	private List<byte[]> hashes;
 	private Long requestTime;
 	private Integer requestHops;
 	private String peerAddress;
 	private Boolean isRelayPossible;
 
-
 	public ArbitraryDataFileListMessage(byte[] signature, List<byte[]> hashes, Long requestTime,
-										Integer requestHops, String peerAddress, boolean isRelayPossible) {
+										Integer requestHops, String peerAddress, Boolean isRelayPossible) {
 		super(MessageType.ARBITRARY_DATA_FILE_LIST);
 
-		this.signature = signature;
-		this.hashes = hashes;
-		this.requestTime = requestTime;
-		this.requestHops = requestHops;
-		this.peerAddress = peerAddress;
-		this.isRelayPossible = isRelayPossible;
+		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, Long requestTime,
+	/** 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);
 
@@ -52,24 +73,39 @@ public class ArbitraryDataFileListMessage extends Message {
 		this.isRelayPossible = isRelayPossible;
 	}
 
-	public List<byte[]> getHashes() {
-		return this.hashes;
-	}
-
 	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();
 
 		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);
 		}
@@ -80,99 +116,21 @@ public class ArbitraryDataFileListMessage extends Message {
 		boolean isRelayPossible = true; // Legacy versions only send this message when relaying is possible
 
 		// The remaining fields are optional
-
 		if (bytes.hasRemaining()) {
+			try {
+				requestTime = bytes.getLong();
 
-			requestTime = bytes.getLong();
+				requestHops = bytes.getInt();
 
-			requestHops = bytes.getInt();
-
-			peerAddress = Serialization.deserializeSizedStringV2(bytes, MAX_PEER_ADDRESS_LENGTH);
-
-			isRelayPossible = bytes.getInt() > 0;
+				peerAddress = Serialization.deserializeSizedStringV2(bytes, PeerData.MAX_PEER_ADDRESS_SIZE);
 
+				isRelayPossible = bytes.getInt() > 0;
+			} catch (TransformationException e) {
+				throw new MessageException(e.getMessage(), e);
+			}
 		}
 
 		return new ArbitraryDataFileListMessage(id, signature, hashes, requestTime, requestHops, peerAddress, isRelayPossible);
 	}
 
-	@Override
-	protected byte[] toData() {
-		try {
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
-
-			bytes.write(this.signature);
-
-			bytes.write(Ints.toByteArray(this.hashes.size()));
-
-			for (byte[] hash : this.hashes) {
-				bytes.write(hash);
-			}
-
-			if (this.requestTime == null) { // To maintain backwards support
-				return bytes.toByteArray();
-			}
-
-			// The remaining fields are optional
-
-			bytes.write(Longs.toByteArray(this.requestTime));
-
-			bytes.write(Ints.toByteArray(this.requestHops));
-
-			Serialization.serializeSizedStringV2(bytes, this.peerAddress);
-
-			bytes.write(Ints.toByteArray(this.isRelayPossible ? 1 : 0));
-
-			return bytes.toByteArray();
-		} catch (IOException e) {
-			return null;
-		}
-	}
-
-	public ArbitraryDataFileListMessage cloneWithNewId(int newId) {
-		ArbitraryDataFileListMessage clone = new ArbitraryDataFileListMessage(this.signature, this.hashes,
-				this.requestTime, this.requestHops, this.peerAddress, this.isRelayPossible);
-		clone.setId(newId);
-		return clone;
-	}
-
-	public void removeOptionalStats() {
-		this.requestTime = null;
-		this.requestHops = null;
-		this.peerAddress = null;
-		this.isRelayPossible = null;
-	}
-
-	public Long getRequestTime() {
-		return this.requestTime;
-	}
-
-	public void setRequestTime(Long requestTime) {
-		this.requestTime = requestTime;
-	}
-
-	public Integer getRequestHops() {
-		return this.requestHops;
-	}
-
-	public void setRequestHops(Integer requestHops) {
-		this.requestHops = requestHops;
-	}
-
-	public String getPeerAddress() {
-		return this.peerAddress;
-	}
-
-	public void setPeerAddress(String peerAddress) {
-		this.peerAddress = peerAddress;
-	}
-
-	public Boolean isRelayPossible() {
-		return this.isRelayPossible;
-	}
-
-	public void setIsRelayPossible(Boolean isRelayPossible) {
-		this.isRelayPossible = isRelayPossible;
-	}
-
 }

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

@@ -9,44 +9,60 @@ 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 Logger LOGGER = LogManager.getLogger(ArbitraryDataFileMessage.class);
 
-	private static final int SIGNATURE_LENGTH = Transformer.SIGNATURE_LENGTH;
-
-	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);
@@ -54,43 +70,10 @@ public class ArbitraryDataFileMessage extends Message {
 		try {
 			ArbitraryDataFile arbitraryDataFile = new ArbitraryDataFile(data, signature);
 			return new ArbitraryDataFileMessage(id, signature, arbitraryDataFile);
-		}
-		catch (DataException e) {
+		} catch (DataException e) {
 			LOGGER.info("Unable to process received file: {}", e.getMessage());
-			return null;
+			throw new MessageException("Unable to process received file: " + e.getMessage(), e);
 		}
 	}
 
-	@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

@@ -7,28 +7,40 @@ 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 ArbitraryMetadataMessage extends Message {
 
-	private static final int SIGNATURE_LENGTH = Transformer.SIGNATURE_LENGTH;
+	private byte[] signature;
+	private ArbitraryDataFile arbitraryMetadataFile;
 
-	private final byte[] signature;
-	private final ArbitraryDataFile arbitraryMetadataFile;
-
-	public ArbitraryMetadataMessage(byte[] signature, ArbitraryDataFile arbitraryDataFile) {
+	public ArbitraryMetadataMessage(byte[] signature, ArbitraryDataFile arbitraryMetadataFile) {
 		super(MessageType.ARBITRARY_METADATA);
 
-		this.signature = signature;
-		this.arbitraryMetadataFile = arbitraryDataFile;
+		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);
 	}
 
-	public ArbitraryMetadataMessage(int id, byte[] signature, ArbitraryDataFile arbitraryDataFile) {
+	private ArbitraryMetadataMessage(int id, byte[] signature, ArbitraryDataFile arbitraryMetadataFile) {
 		super(id, MessageType.ARBITRARY_METADATA);
 
 		this.signature = signature;
-		this.arbitraryMetadataFile = arbitraryDataFile;
+		this.arbitraryMetadataFile = arbitraryMetadataFile;
 	}
 
 	public byte[] getSignature() {
@@ -39,14 +51,14 @@ public class ArbitraryMetadataMessage extends Message {
 		return this.arbitraryMetadataFile;
 	}
 
-	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);
@@ -54,42 +66,9 @@ public class ArbitraryMetadataMessage extends Message {
 		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);
 		}
-		catch (DataException e) {
-			return null;
-		}
-	}
-
-	@Override
-	protected byte[] toData() {
-		if (this.arbitraryMetadataFile == null) {
-			return null;
-		}
-
-		byte[] data = this.arbitraryMetadataFile.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 ArbitraryMetadataMessage cloneWithNewId(int newId) {
-		ArbitraryMetadataMessage clone = new ArbitraryMetadataMessage(this.signature, this.arbitraryMetadataFile);
-		clone.setId(newId);
-		return clone;
 	}
 
 }

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

@@ -1,42 +1,27 @@
 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;
 import org.qortal.transform.TransformationException;
+import org.qortal.transform.block.BlockTransformation;
 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 +29,6 @@ public class BlockMessage extends Message {
 		this.blockData = blockData;
 		this.transactions = transactions;
 		this.atStates = atStates;
-
-		this.height = blockData.getHeight();
 	}
 
 	public BlockData getBlockData() {
@@ -60,44 +43,20 @@ 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();
 
-			Triple<BlockData, List<TransactionData>, List<ATStateData>> blockInfo = BlockTransformer.fromByteBuffer(byteBuffer);
+			BlockTransformation blockTransformation = BlockTransformer.fromByteBuffer(byteBuffer);
 
-			BlockData blockData = blockInfo.getA();
+			BlockData blockData = blockTransformation.getBlockData();
 			blockData.setHeight(height);
 
-			return new BlockMessage(id, blockData, blockInfo.getB(), blockInfo.getC());
+			return new BlockMessage(id, blockData, blockTransformation.getTransactions(), blockTransformation.getAtStates());
 		} 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/BlockV2Message.java

@@ -0,0 +1,87 @@
+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.block.Block;
+import org.qortal.data.block.BlockData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.block.BlockTransformation;
+import org.qortal.transform.block.BlockTransformer;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.List;
+
+public class BlockV2Message extends Message {
+
+	private static final Logger LOGGER = LogManager.getLogger(BlockV2Message.class);
+	public static final long MIN_PEER_VERSION = 0x300030003L; // 3.3.3
+
+	private BlockData blockData;
+	private List<TransactionData> transactions;
+	private byte[] atStatesHash;
+
+	public BlockV2Message(Block block) throws TransformationException {
+		super(MessageType.BLOCK_V2);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			bytes.write(Ints.toByteArray(block.getBlockData().getHeight()));
+
+			bytes.write(BlockTransformer.toBytesV2(block));
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
+
+	public BlockV2Message(byte[] cachedBytes) {
+		super(MessageType.BLOCK_V2);
+
+		this.dataBytes = cachedBytes;
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
+
+	private BlockV2Message(int id, BlockData blockData, List<TransactionData> transactions, byte[] atStatesHash) {
+		super(id, MessageType.BLOCK_V2);
+
+		this.blockData = blockData;
+		this.transactions = transactions;
+		this.atStatesHash = atStatesHash;
+	}
+
+	public BlockData getBlockData() {
+		return this.blockData;
+	}
+
+	public List<TransactionData> getTransactions() {
+		return this.transactions;
+	}
+
+	public byte[] getAtStatesHash() {
+		return this.atStatesHash;
+	}
+
+	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) throws MessageException {
+		try {
+			int height = byteBuffer.getInt();
+
+			BlockTransformation blockTransformation = BlockTransformer.fromByteBufferV2(byteBuffer);
+
+			BlockData blockData = blockTransformation.getBlockData();
+			blockData.setHeight(height);
+
+			return new BlockV2Message(id, blockData, blockTransformation.getTransactions(), blockTransformation.getAtStatesHash());
+		} catch (TransformationException e) {
+			LOGGER.info(String.format("Received garbled BLOCK_V2 message: %s", e.getMessage()));
+			throw new MessageException(e.getMessage(), e);
+		}
+	}
+
+}

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/GetAccountBalanceMessage.java

@@ -0,0 +1,63 @@
+package org.qortal.network.message;
+
+import com.google.common.primitives.Longs;
+import org.qortal.transform.Transformer;
+import org.qortal.utils.Base58;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+public class GetAccountBalanceMessage extends Message {
+
+	private static final int ADDRESS_LENGTH = Transformer.ADDRESS_LENGTH;
+
+	private String address;
+	private long assetId;
+
+	public GetAccountBalanceMessage(String address, long assetId) {
+		super(MessageType.GET_ACCOUNT_BALANCE);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			// Send raw address instead of base58 encoded
+			byte[] addressBytes = Base58.decode(address);
+			bytes.write(addressBytes);
+
+			bytes.write(Longs.toByteArray(assetId));
+
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
+
+	private GetAccountBalanceMessage(int id, String address, long assetId) {
+		super(id, MessageType.GET_ACCOUNT_BALANCE);
+
+		this.address = address;
+		this.assetId = assetId;
+	}
+
+	public String getAddress() {
+		return this.address;
+	}
+
+	public long getAssetId() {
+		return this.assetId;
+	}
+
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
+		byte[] addressBytes = new byte[ADDRESS_LENGTH];
+		bytes.get(addressBytes);
+		String address = Base58.encode(addressBytes);
+
+		long assetId = bytes.getLong();
+
+		return new GetAccountBalanceMessage(id, address, assetId);
+	}
+
+}

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

@@ -0,0 +1,56 @@
+package org.qortal.network.message;
+
+import org.qortal.transform.Transformer;
+import org.qortal.utils.Base58;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.BufferUnderflowException;
+import java.nio.ByteBuffer;
+
+public class GetAccountMessage extends Message {
+
+	private static final int ADDRESS_LENGTH = Transformer.ADDRESS_LENGTH;
+
+	private String address;
+
+	public GetAccountMessage(String address) {
+		super(MessageType.GET_ACCOUNT);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			// Send raw address instead of base58 encoded
+			byte[] addressBytes = Base58.decode(address);
+			bytes.write(addressBytes);
+
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
+
+	private GetAccountMessage(int id, String address) {
+		super(id, MessageType.GET_ACCOUNT);
+
+		this.address = address;
+	}
+
+	public String getAddress() {
+		return this.address;
+	}
+
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
+		if (bytes.remaining() != ADDRESS_LENGTH)
+			throw new BufferUnderflowException();
+
+		byte[] addressBytes = new byte[ADDRESS_LENGTH];
+		bytes.get(addressBytes);
+		String address = Base58.encode(addressBytes);
+
+		return new GetAccountMessage(id, address);
+	}
+
+}

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

@@ -0,0 +1,53 @@
+package org.qortal.network.message;
+
+import org.qortal.transform.Transformer;
+import org.qortal.utils.Base58;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+public class GetAccountNamesMessage extends Message {
+
+	private static final int ADDRESS_LENGTH = Transformer.ADDRESS_LENGTH;
+
+	private String address;
+
+	public GetAccountNamesMessage(String address) {
+		super(MessageType.GET_ACCOUNT_NAMES);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			// Send raw address instead of base58 encoded
+			byte[] addressBytes = Base58.decode(address);
+			bytes.write(addressBytes);
+
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
+
+	private GetAccountNamesMessage(int id, String address) {
+		super(id, MessageType.GET_ACCOUNT_NAMES);
+
+		this.address = address;
+	}
+
+	public String getAddress() {
+		return this.address;
+	}
+
+
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
+		byte[] addressBytes = new byte[ADDRESS_LENGTH];
+		bytes.get(addressBytes);
+		String address = Base58.encode(addressBytes);
+
+		return new GetAccountNamesMessage(id, address);
+	}
+
+}

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

@@ -0,0 +1,69 @@
+package org.qortal.network.message;
+
+import com.google.common.primitives.Ints;
+import org.qortal.transform.Transformer;
+import org.qortal.utils.Base58;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+public class GetAccountTransactionsMessage extends Message {
+
+	private static final int ADDRESS_LENGTH = Transformer.ADDRESS_LENGTH;
+
+	private String address;
+	private int limit;
+	private int offset;
+
+	public GetAccountTransactionsMessage(String address, int limit, int offset) {
+		super(MessageType.GET_ACCOUNT_TRANSACTIONS);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			// Send raw address instead of base58 encoded
+			byte[] addressBytes = Base58.decode(address);
+			bytes.write(addressBytes);
+
+			bytes.write(Ints.toByteArray(limit));
+
+			bytes.write(Ints.toByteArray(offset));
+
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
+
+	private GetAccountTransactionsMessage(int id, String address, int limit, int offset) {
+		super(id, MessageType.GET_ACCOUNT_TRANSACTIONS);
+
+		this.address = address;
+		this.limit = limit;
+		this.offset = offset;
+	}
+
+	public String getAddress() {
+		return this.address;
+	}
+
+	public int getLimit() { return this.limit; }
+
+	public int getOffset() { return this.offset; }
+
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
+		byte[] addressBytes = new byte[ADDRESS_LENGTH];
+		bytes.get(addressBytes);
+		String address = Base58.encode(addressBytes);
+
+		int limit = bytes.getInt();
+
+		int offset = bytes.getInt();
+
+		return new GetAccountTransactionsMessage(id, address, limit, offset);
+	}
+
+}

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

@@ -5,33 +5,54 @@ 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 static final int MAX_PEER_ADDRESS_LENGTH = PeerData.MAX_PEER_ADDRESS_SIZE;
-
-	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, String requestingPeer) {
-		this(-1, signature, hashes, requestTime, requestHops, 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, String requestingPeer) {
@@ -52,8 +73,20 @@ public class GetArbitraryDataFileListMessage extends Message {
 		return this.hashes;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException, TransformationException {
-		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);
 
@@ -67,7 +100,7 @@ public class GetArbitraryDataFileListMessage extends Message {
 
 			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);
 			}
@@ -75,57 +108,14 @@ public class GetArbitraryDataFileListMessage extends Message {
 
 		String requestingPeer = null;
 		if (bytes.hasRemaining()) {
-			requestingPeer = Serialization.deserializeSizedStringV2(bytes, MAX_PEER_ADDRESS_LENGTH);
+			try {
+				requestingPeer = Serialization.deserializeSizedStringV2(bytes, PeerData.MAX_PEER_ADDRESS_SIZE);
+			} catch (TransformationException e) {
+				throw new MessageException(e.getMessage(), e);
+			}
 		}
 
 		return new GetArbitraryDataFileListMessage(id, signature, hashes, requestTime, requestHops, requestingPeer);
 	}
 
-	@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);
-				}
-			}
-			else {
-				bytes.write(Ints.toByteArray(0));
-			}
-
-			if (this.requestingPeer != null) {
-				Serialization.serializeSizedStringV2(bytes, this.requestingPeer);
-			}
-
-			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;
-	}
-
-	public String getRequestingPeer() {
-		return this.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

@@ -6,22 +6,31 @@ import org.qortal.transform.Transformer;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
 
-import static org.qortal.transform.Transformer.INT_LENGTH;
-import static org.qortal.transform.Transformer.LONG_LENGTH;
-
 public class GetArbitraryMetadataMessage extends Message {
 
-	private static final int SIGNATURE_LENGTH = Transformer.SIGNATURE_LENGTH;
-
-	private final byte[] signature;
-	private final long requestTime;
+	private byte[] signature;
+	private long requestTime;
 	private int requestHops;
 
 	public GetArbitraryMetadataMessage(byte[] signature, long requestTime, int requestHops) {
-		this(-1, signature, requestTime, 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) {
@@ -36,12 +45,16 @@ public class GetArbitraryMetadataMessage extends Message {
 		return this.signature;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
-		if (bytes.remaining() != SIGNATURE_LENGTH + LONG_LENGTH + INT_LENGTH)
-			return null;
+	public long getRequestTime() {
+		return this.requestTime;
+	}
 
-		byte[] signature = new byte[SIGNATURE_LENGTH];
+	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();
@@ -51,33 +64,4 @@ public class GetArbitraryMetadataMessage extends Message {
 		return new GetArbitraryMetadataMessage(id, signature, 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));
-
-			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;
-	}
-
 }

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/GetNameMessage.java

@@ -0,0 +1,53 @@
+package org.qortal.network.message;
+
+import org.qortal.naming.Name;
+import org.qortal.transform.TransformationException;
+import org.qortal.utils.Serialization;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+public class GetNameMessage extends Message {
+
+	private String name;
+
+	public GetNameMessage(String address) {
+		super(MessageType.GET_NAME);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			Serialization.serializeSizedStringV2(bytes, name);
+
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
+
+	private GetNameMessage(int id, String name) {
+		super(id, MessageType.GET_NAME);
+
+		this.name = name;
+	}
+
+	public String getName() {
+		return this.name;
+	}
+
+
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws MessageException {
+		try {
+			String name = Serialization.deserializeSizedStringV2(bytes, Name.MAX_NAME_SIZE);
+
+			return new GetNameMessage(id, name);
+
+		} catch (TransformationException e) {
+			throw new MessageException(e.getMessage(), e);
+		}
+	}
+
+}

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

@@ -7,7 +7,6 @@ import org.qortal.transform.Transformer;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -24,11 +23,51 @@ import java.util.Map;
  * Also V2 only builds online accounts message once!
  */
 public class GetOnlineAccountsV2Message extends Message {
+
 	private List<OnlineAccountData> onlineAccounts;
-	private byte[] cachedData;
 
 	public GetOnlineAccountsV2Message(List<OnlineAccountData> onlineAccounts) {
-		this(-1, 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) {
@@ -41,7 +80,7 @@ public class GetOnlineAccountsV2Message extends Message {
 		return this.onlineAccounts;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
 		int accountCount = bytes.getInt();
 
 		List<OnlineAccountData> onlineAccounts = new ArrayList<>(accountCount);
@@ -67,51 +106,4 @@ public class GetOnlineAccountsV2Message extends Message {
 		return new GetOnlineAccountsV2Message(id, onlineAccounts);
 	}
 
-	@Override
-	protected synchronized byte[] toData() {
-		if (this.cachedData != null)
-			return this.cachedData;
-
-		// Shortcut in case we have no online accounts
-		if (this.onlineAccounts.isEmpty()) {
-			this.cachedData = Ints.toByteArray(0);
-			return this.cachedData;
-		}
-
-		// How many of each timestamp
-		Map<Long, Integer> countByTimestamp = new HashMap<>();
-
-		for (int i = 0; i < this.onlineAccounts.size(); ++i) {
-			OnlineAccountData onlineAccountData = this.onlineAccounts.get(i);
-			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)
-				+ this.onlineAccounts.size() * Transformer.PUBLIC_KEY_LENGTH;
-
-		try {
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream(byteSize);
-
-			for (long timestamp : countByTimestamp.keySet()) {
-				bytes.write(Ints.toByteArray(countByTimestamp.get(timestamp)));
-
-				bytes.write(Longs.toByteArray(timestamp));
-
-				for (int i = 0; i < this.onlineAccounts.size(); ++i) {
-					OnlineAccountData onlineAccountData = this.onlineAccounts.get(i);
-
-					if (onlineAccountData.getTimestamp() == timestamp)
-						bytes.write(onlineAccountData.getPublicKey());
-				}
-			}
-
-			this.cachedData = bytes.toByteArray();
-			return this.cachedData;
-		} catch (IOException e) {
-			return null;
-		}
-	}
-
 }

src/main/java/org/qortal/network/message/GetOnlineAccountsV3Message.java

@@ -0,0 +1,112 @@
+package org.qortal.network.message;
+
+import com.google.common.primitives.Longs;
+import org.qortal.transform.Transformer;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.*;
+
+/**
+ * For requesting online accounts info from remote peer, given our list of online accounts.
+ * <p></p>
+ * Different format to V1 and V2:<br>
+ * <ul>
+ * 	<li>V1 is: number of entries, then timestamp + pubkey for each entry</li>
+ * 	<li>V2 is: groups of: number of entries, timestamp, then pubkey for each entry</li>
+ * 	<li>V3 is: groups of: timestamp, number of entries (one per leading byte), then hash(pubkeys) for each entry</li>
+ * </ul>
+ * <p></p>
+ * End
+ */
+public class GetOnlineAccountsV3Message extends Message {
+
+	private static final Map<Long, Map<Byte, byte[]>> EMPTY_ONLINE_ACCOUNTS = Collections.emptyMap();
+	private Map<Long, Map<Byte, byte[]>> hashesByTimestampThenByte;
+
+	public GetOnlineAccountsV3Message(Map<Long, Map<Byte, byte[]>> hashesByTimestampThenByte) {
+		super(MessageType.GET_ONLINE_ACCOUNTS_V3);
+
+		// If we don't have ANY online accounts then it's an easier construction...
+		if (hashesByTimestampThenByte.isEmpty()) {
+			this.dataBytes = EMPTY_DATA_BYTES;
+			return;
+		}
+
+		// We should know exactly how many bytes to allocate now
+		int byteSize = hashesByTimestampThenByte.size() * (Transformer.TIMESTAMP_LENGTH + Transformer.BYTE_LENGTH);
+
+		byteSize += hashesByTimestampThenByte.values()
+				.stream()
+				.mapToInt(map -> map.size() * Transformer.PUBLIC_KEY_LENGTH)
+				.sum();
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream(byteSize);
+
+		// Warning: no double-checking/fetching! We must be ConcurrentMap compatible.
+		// So no contains() then get() or multiple get()s on the same key/map.
+		try {
+			for (var outerMapEntry : hashesByTimestampThenByte.entrySet()) {
+				bytes.write(Longs.toByteArray(outerMapEntry.getKey()));
+
+				var innerMap = outerMapEntry.getValue();
+
+				// Number of entries: 1 - 256, where 256 is represented by 0
+				bytes.write(innerMap.size() & 0xFF);
+
+				for (byte[] hashBytes : innerMap.values()) {
+					bytes.write(hashBytes);
+				}
+			}
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
+
+	private GetOnlineAccountsV3Message(int id, Map<Long, Map<Byte, byte[]>> hashesByTimestampThenByte) {
+		super(id, MessageType.GET_ONLINE_ACCOUNTS_V3);
+
+		this.hashesByTimestampThenByte = hashesByTimestampThenByte;
+	}
+
+	public Map<Long, Map<Byte, byte[]>> getHashesByTimestampThenByte() {
+		return this.hashesByTimestampThenByte;
+	}
+
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
+		// 'empty' case
+		if (!bytes.hasRemaining()) {
+			return new GetOnlineAccountsV3Message(id, EMPTY_ONLINE_ACCOUNTS);
+		}
+
+		Map<Long, Map<Byte, byte[]>> hashesByTimestampThenByte = new HashMap<>();
+
+		while (bytes.hasRemaining()) {
+			long timestamp = bytes.getLong();
+
+			int hashCount = bytes.get();
+			if (hashCount <= 0)
+				// 256 is represented by 0.
+				// Also converts negative signed value (e.g. -1) to proper positive unsigned value (255)
+				hashCount += 256;
+
+			Map<Byte, byte[]> hashesByByte = new HashMap<>();
+
+			for (int i = 0; i < hashCount; ++i) {
+				byte[] publicKeyHash = new byte[Transformer.PUBLIC_KEY_LENGTH];
+				bytes.get(publicKeyHash);
+
+				hashesByByte.put(publicKeyHash[0], publicKeyHash);
+			}
+
+			hashesByTimestampThenByte.put(timestamp, hashesByByte);
+		}
+
+		return new GetOnlineAccountsV3Message(id, hashesByTimestampThenByte);
+	}
+
+}

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];
-	}
-
 }

src/main/java/org/qortal/network/message/GetSignaturesV2Message.java

@@ -2,24 +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 GetSignaturesV2Message extends Message {
 
-	private static final int BLOCK_SIGNATURE_LENGTH = BlockTransformer.BLOCK_SIGNATURE_LENGTH;
-	private static final int NUMBER_REQUESTED_LENGTH = Transformer.INT_LENGTH;
-
 	private byte[] parentSignature;
 	private int numberRequested;
 
 	public GetSignaturesV2Message(byte[] parentSignature, int numberRequested) {
-		this(-1, parentSignature, numberRequested);
+		super(MessageType.GET_SIGNATURES_V2);
+
+		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 GetSignaturesV2Message(int id, byte[] parentSignature, int numberRequested) {
@@ -37,11 +45,8 @@ public class GetSignaturesV2Message extends Message {
 		return this.numberRequested;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
-		if (bytes.remaining() != BLOCK_SIGNATURE_LENGTH + NUMBER_REQUESTED_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();
@@ -49,19 +54,4 @@ public class GetSignaturesV2Message extends Message {
 		return new GetSignaturesV2Message(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/GetTradePresencesMessage.java

@@ -7,7 +7,6 @@ import org.qortal.transform.Transformer;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -21,10 +20,48 @@ import java.util.Map;
  */
 public class GetTradePresencesMessage extends Message {
 	private List<TradePresenceData> tradePresences;
-	private byte[] cachedData;
 
 	public GetTradePresencesMessage(List<TradePresenceData> tradePresences) {
-		this(-1, tradePresences);
+		super(MessageType.GET_TRADE_PRESENCES);
+
+		// Shortcut in case we have no trade presences
+		if (tradePresences.isEmpty()) {
+			this.dataBytes = Ints.toByteArray(0);
+			this.checksumBytes = Message.generateChecksum(this.dataBytes);
+			return;
+		}
+
+		// How many of each timestamp
+		Map<Long, Integer> countByTimestamp = new HashMap<>();
+
+		for (TradePresenceData tradePresenceData : tradePresences) {
+			Long timestamp = tradePresenceData.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)
+				+ tradePresences.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 (TradePresenceData tradePresenceData : tradePresences) {
+					if (tradePresenceData.getTimestamp() == timestamp)
+						bytes.write(tradePresenceData.getPublicKey());
+				}
+			}
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
 	}
 
 	private GetTradePresencesMessage(int id, List<TradePresenceData> tradePresences) {
@@ -37,7 +74,7 @@ public class GetTradePresencesMessage extends Message {
 		return this.tradePresences;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
 		int groupedEntriesCount = bytes.getInt();
 
 		List<TradePresenceData> tradePresences = new ArrayList<>(groupedEntriesCount);
@@ -63,48 +100,4 @@ public class GetTradePresencesMessage extends Message {
 		return new GetTradePresencesMessage(id, tradePresences);
 	}
 
-	@Override
-	protected synchronized byte[] toData() {
-		if (this.cachedData != null)
-			return this.cachedData;
-
-		// Shortcut in case we have no trade presences
-		if (this.tradePresences.isEmpty()) {
-			this.cachedData = Ints.toByteArray(0);
-			return this.cachedData;
-		}
-
-		// How many of each timestamp
-		Map<Long, Integer> countByTimestamp = new HashMap<>();
-
-		for (TradePresenceData tradePresenceData : this.tradePresences) {
-			Long timestamp = tradePresenceData.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)
-				+ this.tradePresences.size() * Transformer.PUBLIC_KEY_LENGTH;
-
-		try {
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream(byteSize);
-
-			for (long timestamp : countByTimestamp.keySet()) {
-				bytes.write(Ints.toByteArray(countByTimestamp.get(timestamp)));
-
-				bytes.write(Longs.toByteArray(timestamp));
-
-				for (TradePresenceData tradePresenceData : this.tradePresences) {
-					if (tradePresenceData.getTimestamp() == timestamp)
-						bytes.write(tradePresenceData.getPublicKey());
-				}
-			}
-
-			this.cachedData = bytes.toByteArray();
-			return this.cachedData;
-		} catch (IOException e) {
-			return null;
-		}
-	}
-
 }

src/main/java/org/qortal/network/message/GetTransactionMessage.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 GetTransactionMessage extends Message {
 
-	private static final int TRANSACTION_SIGNATURE_LENGTH = Transformer.SIGNATURE_LENGTH;
-
 	private byte[] signature;
 
 	public GetTransactionMessage(byte[] signature) {
-		this(-1, signature);
+		super(MessageType.GET_TRANSACTION);
+
+		this.dataBytes = Arrays.copyOf(signature, signature.length);
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
 	}
 
 	private GetTransactionMessage(int id, byte[] signature) {
@@ -27,28 +26,12 @@ public class GetTransactionMessage extends Message {
 		return this.signature;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
-		if (bytes.remaining() != TRANSACTION_SIGNATURE_LENGTH)
-			return null;
-
-		byte[] signature = new byte[TRANSACTION_SIGNATURE_LENGTH];
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
+		byte[] signature = new byte[Transformer.SIGNATURE_LENGTH];
 
 		bytes.get(signature);
 
 		return new GetTransactionMessage(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/GetUnconfirmedTransactionsMessage.java

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

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

@@ -3,7 +3,6 @@ package org.qortal.network.message;
 import static java.util.Arrays.stream;
 import static java.util.stream.Collectors.toMap;
 
-import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.util.Map;
 
@@ -22,7 +21,7 @@ public class GoodbyeMessage extends Message {
 		private static final Map<Integer, Reason> map = stream(Reason.values())
 				.collect(toMap(reason -> reason.value, reason -> reason));
 
-		private Reason(int value) {
+		Reason(int value) {
 			this.value = value;
 		}
 
@@ -31,7 +30,14 @@ public class GoodbyeMessage extends Message {
 		}
 	}
 
-	private final Reason reason;
+	private Reason reason;
+
+	public GoodbyeMessage(Reason reason) {
+		super(MessageType.GOODBYE);
+
+		this.dataBytes = Ints.toByteArray(reason.value);
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
 
 	private GoodbyeMessage(int id, Reason reason) {
 		super(id, MessageType.GOODBYE);
@@ -39,27 +45,18 @@ public class GoodbyeMessage extends Message {
 		this.reason = reason;
 	}
 
-	public GoodbyeMessage(Reason reason) {
-		this(-1, reason);
-	}
-
 	public Reason getReason() {
 		return this.reason;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) {
+	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) throws MessageException {
 		int reasonValue = byteBuffer.getInt();
 
 		Reason reason = Reason.valueOf(reasonValue);
 		if (reason == null)
-			return null;
+			throw new MessageException("Invalid reason " + reasonValue + " in GOODBYE message");
 
 		return new GoodbyeMessage(id, reason);
 	}
 
-	@Override
-	protected byte[] toData() throws IOException {
-		return Ints.toByteArray(this.reason.value);
-	}
-
 }

src/main/java/org/qortal/network/message/HeightV2Message.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.transform.Transformer;
@@ -19,7 +18,24 @@ public class HeightV2Message extends Message {
 	private byte[] minterPublicKey;
 
 	public HeightV2Message(int height, byte[] signature, long timestamp, byte[] minterPublicKey) {
-		this(-1, height, signature, timestamp, minterPublicKey);
+		super(MessageType.HEIGHT_V2);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			bytes.write(Ints.toByteArray(height));
+
+			bytes.write(signature);
+
+			bytes.write(Longs.toByteArray(timestamp));
+
+			bytes.write(minterPublicKey);
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
 	}
 
 	private HeightV2Message(int id, int height, byte[] signature, long timestamp, byte[] minterPublicKey) {
@@ -47,7 +63,7 @@ public class HeightV2Message extends Message {
 		return this.minterPublicKey;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
 		int height = bytes.getInt();
 
 		byte[] signature = new byte[BlockTransformer.BLOCK_SIGNATURE_LENGTH];
@@ -61,23 +77,4 @@ public class HeightV2Message extends Message {
 		return new HeightV2Message(id, height, signature, timestamp, minterPublicKey);
 	}
 
-	@Override
-	protected byte[] toData() {
-		try {
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
-
-			bytes.write(Ints.toByteArray(this.height));
-
-			bytes.write(this.signature);
-
-			bytes.write(Longs.toByteArray(this.timestamp));
-
-			bytes.write(this.minterPublicKey);
-
-			return bytes.toByteArray();
-		} catch (IOException e) {
-			return null;
-		}
-	}
-
 }

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

@@ -11,9 +11,28 @@ import com.google.common.primitives.Longs;
 
 public class HelloMessage extends Message {
 
-	private final long timestamp;
-	private final String versionString;
-	private final String senderPeerAddress;
+	private long timestamp;
+	private String versionString;
+	private String senderPeerAddress;
+
+	public HelloMessage(long timestamp, String versionString, String senderPeerAddress) {
+		super(MessageType.HELLO);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			bytes.write(Longs.toByteArray(timestamp));
+
+			Serialization.serializeSizedString(bytes, versionString);
+
+			Serialization.serializeSizedString(bytes, senderPeerAddress);
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
 
 	private HelloMessage(int id, long timestamp, String versionString, String senderPeerAddress) {
 		super(id, MessageType.HELLO);
@@ -23,10 +42,6 @@ public class HelloMessage extends Message {
 		this.senderPeerAddress = senderPeerAddress;
 	}
 
-	public HelloMessage(long timestamp, String versionString, String senderPeerAddress) {
-		this(-1, timestamp, versionString, senderPeerAddress);
-	}
-
 	public long getTimestamp() {
 		return this.timestamp;
 	}
@@ -39,31 +54,23 @@ public class HelloMessage extends Message {
 		return this.senderPeerAddress;
 	}
 
-	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) throws TransformationException {
+	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) throws MessageException {
 		long timestamp = byteBuffer.getLong();
 
-		String versionString = Serialization.deserializeSizedString(byteBuffer, 255);
-
-		// Sender peer address added in v3.0, so is an optional field. Older versions won't send it.
+		String versionString;
 		String senderPeerAddress = null;
-		if (byteBuffer.hasRemaining()) {
-			senderPeerAddress = Serialization.deserializeSizedString(byteBuffer, 255);
+		try {
+			versionString = Serialization.deserializeSizedString(byteBuffer, 255);
+
+			// Sender peer address added in v3.0, so is an optional field. Older versions won't send it.
+			if (byteBuffer.hasRemaining()) {
+				senderPeerAddress = Serialization.deserializeSizedString(byteBuffer, 255);
+			}
+		} catch (TransformationException e) {
+			throw new MessageException(e.getMessage(), e);
 		}
 
 		return new HelloMessage(id, timestamp, versionString, senderPeerAddress);
 	}
 
-	@Override
-	protected byte[] toData() throws IOException {
-		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
-
-		bytes.write(Longs.toByteArray(this.timestamp));
-
-		Serialization.serializeSizedString(bytes, this.versionString);
-
-		Serialization.serializeSizedString(bytes, this.senderPeerAddress);
-
-		return bytes.toByteArray();
-	}
-
 }

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

@@ -1,161 +1,68 @@
 package org.qortal.network.message;
 
-import java.util.Map;
-
 import org.qortal.crypto.Crypto;
 import org.qortal.network.Network;
-import org.qortal.transform.TransformationException;
 
 import com.google.common.primitives.Ints;
 
-import static java.util.Arrays.stream;
-import static java.util.stream.Collectors.toMap;
-
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Method;
 import java.nio.BufferUnderflowException;
 import java.nio.ByteBuffer;
 import java.util.Arrays;
 
+/**
+ * Network message for sending over network, or unpacked data received from network.
+ * <p></p>
+ * <p>
+ * For messages received from network, subclass's {@code fromByteBuffer()} method is used
+ * to construct a subclassed instance. Original bytes from network are not retained.
+ * Access to deserialized data should be via subclass's getters. Ideally there should be NO setters!
+ * </p>
+ * <p></p>
+ * <p>
+ * Each subclass's <b>public</b> constructor is for building a message to send <b>only</b>.
+ * The constructor will serialize into byte form but <b>not</b> store the passed args.
+ * Serialized bytes are saved into superclass (Message) {@code dataBytes} and, if not empty,
+ * a checksum is created and saved into {@code checksumBytes}.
+ * Therefore: <i>do not use subclass's getters after using constructor!</i>
+ * </p>
+ * <p></p>
+ * <p>
+ * For subclasses where outgoing versions might be usefully cached, they can implement Clonable
+ * as long if they are safe to use {@link Object#clone()}.
+ * </p>
+ */
 public abstract class Message {
 
 	// MAGIC(4) + TYPE(4) + HAS-ID(1) + ID?(4) + DATA-SIZE(4) + CHECKSUM?(4) + DATA?(*)
 	private static final int MAGIC_LENGTH = 4;
+	private static final int TYPE_LENGTH = 4;
+	private static final int HAS_ID_LENGTH = 1;
+	private static final int ID_LENGTH = 4;
+	private static final int DATA_SIZE_LENGTH = 4;
 	private static final int CHECKSUM_LENGTH = 4;
 
 	private static final int MAX_DATA_SIZE = 10 * 1024 * 1024; // 10MB
 
-	@SuppressWarnings("serial")
-	public static class MessageException extends Exception {
-		public MessageException() {
-		}
+	protected static final byte[] EMPTY_DATA_BYTES = new byte[0];
+	private static final ByteBuffer EMPTY_READ_ONLY_BYTE_BUFFER = ByteBuffer.wrap(EMPTY_DATA_BYTES).asReadOnlyBuffer();
 
-		public MessageException(String message) {
-			super(message);
-		}
+	protected int id;
+	protected final MessageType type;
 
-		public MessageException(String message, Throwable cause) {
-			super(message, cause);
-		}
-
-		public MessageException(Throwable cause) {
-			super(cause);
-		}
-	}
-
-	public enum MessageType {
-		// Handshaking
-		HELLO(0),
-		GOODBYE(1),
-		CHALLENGE(2),
-		RESPONSE(3),
-
-		// Status / notifications
-		HEIGHT_V2(10),
-		PING(11),
-		PONG(12),
-
-		// Requesting data
-		PEERS_V2(20),
-		GET_PEERS(21),
-
-		TRANSACTION(30),
-		GET_TRANSACTION(31),
-
-		TRANSACTION_SIGNATURES(40),
-		GET_UNCONFIRMED_TRANSACTIONS(41),
-
-		BLOCK(50),
-		GET_BLOCK(51),
-
-		SIGNATURES(60),
-		GET_SIGNATURES_V2(61),
-
-		BLOCK_SUMMARIES(70),
-		GET_BLOCK_SUMMARIES(71),
-
-		ONLINE_ACCOUNTS(80),
-		GET_ONLINE_ACCOUNTS(81),
-		ONLINE_ACCOUNTS_V2(82),
-		GET_ONLINE_ACCOUNTS_V2(83),
-
-		ARBITRARY_DATA(90),
-		GET_ARBITRARY_DATA(91),
-
-		BLOCKS(100),
-		GET_BLOCKS(101),
-
-		ARBITRARY_DATA_FILE(110),
-		GET_ARBITRARY_DATA_FILE(111),
-
-		ARBITRARY_DATA_FILE_LIST(120),
-		GET_ARBITRARY_DATA_FILE_LIST(121),
-
-		ARBITRARY_SIGNATURES(130),
-
-		TRADE_PRESENCES(140),
-		GET_TRADE_PRESENCES(141),
-		
-		ARBITRARY_METADATA(150),
-		GET_ARBITRARY_METADATA(151);
-
-		public final int value;
-		public final Method fromByteBufferMethod;
-
-		private static final Map<Integer, MessageType> map = stream(MessageType.values())
-				.collect(toMap(messageType -> messageType.value, messageType -> messageType));
-
-		private MessageType(int value) {
-			this.value = value;
-
-			String[] classNameParts = this.name().toLowerCase().split("_");
-
-			for (int i = 0; i < classNameParts.length; ++i)
-				classNameParts[i] = classNameParts[i].substring(0, 1).toUpperCase().concat(classNameParts[i].substring(1));
-
-			String className = String.join("", classNameParts);
-
-			Method method;
-			try {
-				Class<?> subclass = Class.forName(String.join("", Message.class.getPackage().getName(), ".", className, "Message"));
-
-				method = subclass.getDeclaredMethod("fromByteBuffer", int.class, ByteBuffer.class);
-			} catch (ClassNotFoundException | NoSuchMethodException | SecurityException e) {
-				method = null;
-			}
-
-			this.fromByteBufferMethod = method;
-		}
-
-		public static MessageType valueOf(int value) {
-			return map.get(value);
-		}
-
-		public Message fromByteBuffer(int id, ByteBuffer byteBuffer) throws MessageException {
-			if (this.fromByteBufferMethod == null)
-				throw new MessageException("Unsupported message type [" + value + "] during conversion from bytes");
-
-			try {
-				return (Message) this.fromByteBufferMethod.invoke(null, id, byteBuffer);
-			} catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
-				if (e.getCause() instanceof BufferUnderflowException)
-					throw new MessageException("Byte data too short for " + name() + " message");
-
-				throw new MessageException("Internal error with " + name() + " message during conversion from bytes");
-			}
-		}
-	}
-
-	private int id;
-	private MessageType type;
+	/** Serialized outgoing message data. Expected to be written to by subclass. */
+	protected byte[] dataBytes;
+	/** Serialized outgoing message checksum. Expected to be written to by subclass. */
+	protected byte[] checksumBytes;
 
+	/** Typically called by subclass when constructing message from received network data. */
 	protected Message(int id, MessageType type) {
 		this.id = id;
 		this.type = type;
 	}
 
+	/** Typically called by subclass when constructing outgoing message. */
 	protected Message(MessageType type) {
 		this(-1, type);
 	}
@@ -179,9 +86,9 @@ public abstract class Message {
 	/**
 	 * Attempt to read a message from byte buffer.
 	 * 
-	 * @param readOnlyBuffer
+	 * @param readOnlyBuffer ByteBuffer containing bytes read from network
 	 * @return null if no complete message can be read
-	 * @throws MessageException
+	 * @throws MessageException if message could not be decoded or is invalid
 	 */
 	public static Message fromByteBuffer(ByteBuffer readOnlyBuffer) throws MessageException {
 		try {
@@ -197,8 +104,7 @@ public abstract class Message {
 			int typeValue = readOnlyBuffer.getInt();
 			MessageType messageType = MessageType.valueOf(typeValue);
 			if (messageType == null)
-				// Unrecognised message type
-				throw new MessageException(String.format("Received unknown message type [%d]", typeValue));
+				messageType = MessageType.UNSUPPORTED;
 
 			// Optional message ID
 			byte hasId = readOnlyBuffer.get();
@@ -221,7 +127,7 @@ public abstract class Message {
 			if (dataSize > 0 && dataSize + CHECKSUM_LENGTH > readOnlyBuffer.remaining())
 				return null;
 
-			ByteBuffer dataSlice = null;
+			ByteBuffer dataSlice = EMPTY_READ_ONLY_BYTE_BUFFER;
 			if (dataSize > 0) {
 				byte[] expectedChecksum = new byte[CHECKSUM_LENGTH];
 				readOnlyBuffer.get(expectedChecksum);
@@ -256,9 +162,27 @@ public abstract class Message {
 		return Arrays.copyOfRange(Crypto.digest(dataBuffer), 0, CHECKSUM_LENGTH);
 	}
 
+	public void checkValidOutgoing() throws MessageException {
+		// We expect subclass to have initialized these
+		if (this.dataBytes == null)
+			throw new MessageException("Missing data payload");
+		if (this.dataBytes.length > 0 && this.checksumBytes == null)
+			throw new MessageException("Missing data checksum");
+	}
+
 	public byte[] toBytes() throws MessageException {
+		checkValidOutgoing();
+
+		// We can calculate exact length
+		int messageLength = MAGIC_LENGTH + TYPE_LENGTH + HAS_ID_LENGTH;
+		messageLength += this.hasId() ? ID_LENGTH : 0;
+		messageLength += DATA_SIZE_LENGTH + this.dataBytes.length > 0 ? CHECKSUM_LENGTH + this.dataBytes.length : 0;
+
+		if (messageLength > MAX_DATA_SIZE)
+			throw new MessageException(String.format("About to send message with length %d larger than allowed %d", messageLength, MAX_DATA_SIZE));
+
 		try {
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream(256);
+			ByteArrayOutputStream bytes = new ByteArrayOutputStream(messageLength);
 
 			// Magic
 			bytes.write(Network.getInstance().getMessageMagic());
@@ -273,26 +197,30 @@ public abstract class Message {
 				bytes.write(0);
 			}
 
-			byte[] data = this.toData();
-			if (data == null)
-				throw new MessageException("Missing data payload");
+			bytes.write(Ints.toByteArray(this.dataBytes.length));
 
-			bytes.write(Ints.toByteArray(data.length));
-
-			if (data.length > 0) {
-				bytes.write(generateChecksum(data));
-				bytes.write(data);
+			if (this.dataBytes.length > 0) {
+				bytes.write(this.checksumBytes);
+				bytes.write(this.dataBytes);
 			}
 
-			if (bytes.size() > MAX_DATA_SIZE)
-				throw new MessageException(String.format("About to send message with length %d larger than allowed %d", bytes.size(), MAX_DATA_SIZE));
-
 			return bytes.toByteArray();
-		} catch (IOException | TransformationException e) {
+		} catch (IOException e) {
 			throw new MessageException("Failed to serialize message", e);
 		}
 	}
 
-	protected abstract byte[] toData() throws IOException, TransformationException;
+	public static <M extends Message> M cloneWithNewId(M message, int newId) {
+		M clone;
+
+		try {
+			clone = (M) message.clone();
+		} catch (CloneNotSupportedException e) {
+			throw new UnsupportedOperationException("Message sub-class not cloneable");
+		}
+
+		clone.setId(newId);
+		return clone;
+	}
 
 }

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

@@ -0,0 +1,19 @@
+package org.qortal.network.message;
+
+@SuppressWarnings("serial")
+public class MessageException extends Exception {
+    public MessageException() {
+    }
+
+    public MessageException(String message) {
+        super(message);
+    }
+
+    public MessageException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public MessageException(Throwable cause) {
+        super(cause);
+    }
+}

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

@@ -0,0 +1,8 @@
+package org.qortal.network.message;
+
+import java.nio.ByteBuffer;
+
+@FunctionalInterface
+public interface MessageProducer {
+    Message fromByteBuffer(int id, ByteBuffer byteBuffer) throws MessageException;
+}

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

@@ -0,0 +1,116 @@
+package org.qortal.network.message;
+
+import java.nio.BufferUnderflowException;
+import java.nio.ByteBuffer;
+import java.util.Map;
+
+import static java.util.Arrays.stream;
+import static java.util.stream.Collectors.toMap;
+
+public enum MessageType {
+    // Pseudo-message, not sent over the wire
+    UNSUPPORTED(-1, UnsupportedMessage::fromByteBuffer),
+
+    // Handshaking
+    HELLO(0, HelloMessage::fromByteBuffer),
+    GOODBYE(1, GoodbyeMessage::fromByteBuffer),
+    CHALLENGE(2, ChallengeMessage::fromByteBuffer),
+    RESPONSE(3, ResponseMessage::fromByteBuffer),
+
+    // Status / notifications
+    HEIGHT_V2(10, HeightV2Message::fromByteBuffer),
+    PING(11, PingMessage::fromByteBuffer),
+    PONG(12, PongMessage::fromByteBuffer),
+
+    // Requesting data
+    PEERS_V2(20, PeersV2Message::fromByteBuffer),
+    GET_PEERS(21, GetPeersMessage::fromByteBuffer),
+
+    TRANSACTION(30, TransactionMessage::fromByteBuffer),
+    GET_TRANSACTION(31, GetTransactionMessage::fromByteBuffer),
+
+    TRANSACTION_SIGNATURES(40, TransactionSignaturesMessage::fromByteBuffer),
+    GET_UNCONFIRMED_TRANSACTIONS(41, GetUnconfirmedTransactionsMessage::fromByteBuffer),
+
+    BLOCK(50, BlockMessage::fromByteBuffer),
+    GET_BLOCK(51, GetBlockMessage::fromByteBuffer),
+    BLOCK_V2(52, BlockV2Message::fromByteBuffer),
+
+    SIGNATURES(60, SignaturesMessage::fromByteBuffer),
+    GET_SIGNATURES_V2(61, GetSignaturesV2Message::fromByteBuffer),
+
+    BLOCK_SUMMARIES(70, BlockSummariesMessage::fromByteBuffer),
+    GET_BLOCK_SUMMARIES(71, GetBlockSummariesMessage::fromByteBuffer),
+
+    ONLINE_ACCOUNTS(80, OnlineAccountsMessage::fromByteBuffer),
+    GET_ONLINE_ACCOUNTS(81, GetOnlineAccountsMessage::fromByteBuffer),
+    ONLINE_ACCOUNTS_V2(82, OnlineAccountsV2Message::fromByteBuffer),
+    GET_ONLINE_ACCOUNTS_V2(83, GetOnlineAccountsV2Message::fromByteBuffer),
+    // ONLINE_ACCOUNTS_V3(84, OnlineAccountsV3Message::fromByteBuffer),
+    GET_ONLINE_ACCOUNTS_V3(85, GetOnlineAccountsV3Message::fromByteBuffer),
+
+    ARBITRARY_DATA(90, ArbitraryDataMessage::fromByteBuffer),
+    GET_ARBITRARY_DATA(91, GetArbitraryDataMessage::fromByteBuffer),
+
+    BLOCKS(100, null), // unsupported
+    GET_BLOCKS(101, null), // unsupported
+
+    ARBITRARY_DATA_FILE(110, ArbitraryDataFileMessage::fromByteBuffer),
+    GET_ARBITRARY_DATA_FILE(111, GetArbitraryDataFileMessage::fromByteBuffer),
+
+    ARBITRARY_DATA_FILE_LIST(120, ArbitraryDataFileListMessage::fromByteBuffer),
+    GET_ARBITRARY_DATA_FILE_LIST(121, GetArbitraryDataFileListMessage::fromByteBuffer),
+
+    ARBITRARY_SIGNATURES(130, ArbitrarySignaturesMessage::fromByteBuffer),
+
+    TRADE_PRESENCES(140, TradePresencesMessage::fromByteBuffer),
+    GET_TRADE_PRESENCES(141, GetTradePresencesMessage::fromByteBuffer),
+
+    ARBITRARY_METADATA(150, ArbitraryMetadataMessage::fromByteBuffer),
+    GET_ARBITRARY_METADATA(151, GetArbitraryMetadataMessage::fromByteBuffer),
+
+    // Lite node support
+    ACCOUNT(160, AccountMessage::fromByteBuffer),
+    GET_ACCOUNT(161, GetAccountMessage::fromByteBuffer),
+
+    ACCOUNT_BALANCE(170, AccountBalanceMessage::fromByteBuffer),
+    GET_ACCOUNT_BALANCE(171, GetAccountBalanceMessage::fromByteBuffer),
+
+    NAMES(180, NamesMessage::fromByteBuffer),
+    GET_ACCOUNT_NAMES(181, GetAccountNamesMessage::fromByteBuffer),
+    GET_NAME(182, GetNameMessage::fromByteBuffer),
+
+    TRANSACTIONS(190, TransactionsMessage::fromByteBuffer),
+    GET_ACCOUNT_TRANSACTIONS(191, GetAccountTransactionsMessage::fromByteBuffer);
+
+    public final int value;
+    public final MessageProducer fromByteBufferMethod;
+
+    private static final Map<Integer, MessageType> map = stream(MessageType.values())
+            .collect(toMap(messageType -> messageType.value, messageType -> messageType));
+
+    MessageType(int value, MessageProducer fromByteBufferMethod) {
+        this.value = value;
+        this.fromByteBufferMethod = fromByteBufferMethod;
+    }
+
+    public static MessageType valueOf(int value) {
+        return map.get(value);
+    }
+
+    /**
+     * Attempt to read a message from byte buffer.
+     *
+     * @param id message ID or -1
+     * @param byteBuffer ByteBuffer source for message
+     * @return null if no complete message can be read
+     * @throws MessageException if message could not be decoded or is invalid
+     * @throws BufferUnderflowException if not enough bytes in buffer to read message
+     */
+    public Message fromByteBuffer(int id, ByteBuffer byteBuffer) throws MessageException {
+        if (this.fromByteBufferMethod == null)
+            throw new MessageException("Message type " + this.name() + " unsupported");
+
+        return this.fromByteBufferMethod.fromByteBuffer(id, byteBuffer);
+    }
+}

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

@@ -0,0 +1,142 @@
+package org.qortal.network.message;
+
+import com.google.common.primitives.Ints;
+import com.google.common.primitives.Longs;
+import org.qortal.data.naming.NameData;
+import org.qortal.naming.Name;
+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.nio.BufferUnderflowException;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.List;
+
+public class NamesMessage extends Message {
+
+	private static final int SIGNATURE_LENGTH = Transformer.SIGNATURE_LENGTH;
+
+	private List<NameData> nameDataList;
+
+	public NamesMessage(List<NameData> nameDataList) {
+		super(MessageType.NAMES);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			bytes.write(Ints.toByteArray(nameDataList.size()));
+
+			for (int i = 0; i < nameDataList.size(); ++i) {
+				NameData nameData = nameDataList.get(i);
+
+				Serialization.serializeSizedStringV2(bytes, nameData.getName());
+
+				Serialization.serializeSizedStringV2(bytes, nameData.getReducedName());
+
+				Serialization.serializeAddress(bytes, nameData.getOwner());
+
+				Serialization.serializeSizedStringV2(bytes, nameData.getData());
+
+				bytes.write(Longs.toByteArray(nameData.getRegistered()));
+
+				Long updated = nameData.getUpdated();
+				int wasUpdated = (updated != null) ? 1 : 0;
+				bytes.write(Ints.toByteArray(wasUpdated));
+
+				if (updated != null) {
+					bytes.write(Longs.toByteArray(nameData.getUpdated()));
+				}
+
+				int isForSale = nameData.isForSale() ? 1 : 0;
+				bytes.write(Ints.toByteArray(isForSale));
+
+				if (nameData.isForSale()) {
+					bytes.write(Longs.toByteArray(nameData.getSalePrice()));
+				}
+
+				bytes.write(nameData.getReference());
+
+				bytes.write(Ints.toByteArray(nameData.getCreationGroupId()));
+			}
+
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
+
+	public NamesMessage(int id, List<NameData> nameDataList) {
+		super(id, MessageType.NAMES);
+
+		this.nameDataList = nameDataList;
+	}
+
+	public List<NameData> getNameDataList() {
+		return this.nameDataList;
+	}
+
+
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws MessageException {
+		try {
+			final int nameCount = bytes.getInt();
+
+			List<NameData> nameDataList = new ArrayList<>(nameCount);
+
+			for (int i = 0; i < nameCount; ++i) {
+				String name = Serialization.deserializeSizedStringV2(bytes, Name.MAX_NAME_SIZE);
+
+				String reducedName = Serialization.deserializeSizedStringV2(bytes, Name.MAX_NAME_SIZE);
+
+				String owner = Serialization.deserializeAddress(bytes);
+
+				String data = Serialization.deserializeSizedStringV2(bytes, Name.MAX_DATA_SIZE);
+
+				long registered = bytes.getLong();
+
+				int wasUpdated = bytes.getInt();
+
+				Long updated = null;
+				if (wasUpdated == 1) {
+					updated = bytes.getLong();
+				}
+
+				boolean isForSale = (bytes.getInt() == 1);
+
+				Long salePrice = null;
+				if (isForSale) {
+					salePrice = bytes.getLong();
+				}
+
+				byte[] reference = new byte[SIGNATURE_LENGTH];
+				bytes.get(reference);
+
+				int creationGroupId = bytes.getInt();
+
+				NameData nameData = new NameData(name, reducedName, owner, data, registered, updated,
+						isForSale, salePrice, reference, creationGroupId);
+				nameDataList.add(nameData);
+			}
+
+			if (bytes.hasRemaining()) {
+				throw new BufferUnderflowException();
+			}
+
+			return new NamesMessage(id, nameDataList);
+
+		} catch (TransformationException e) {
+			throw new MessageException(e.getMessage(), e);
+		}
+	}
+
+	public NamesMessage cloneWithNewId(int newId) {
+		NamesMessage clone = new NamesMessage(this.nameDataList);
+		clone.setId(newId);
+		return clone;
+	}
+
+}