Bump version to 3.3.2

Reduced to 20 sats/byte.

.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:{8C9CFB9D-BC4C-4142-A5A5-5551BF3B9467} 1049:{4A5BDDD9-ED71-431A-A46F-D19E9DE17216} 2052:{0B9DCE00-BE23-434D-BD6A-1CFA6AB3CA43} 2057:{23D81967-556A-41B8-9981-A739E2820624} " Type="16"/>
+    <ROW Property="ProductCode" Value="1033:{BAC69595-0A3F-4B9F-AB21-5DAC9F288F27} 1049:{4ADB3829-2ECB-4DB0-B114-4068417B6F01} 2052:{B830ACAC-079B-49A9-8271-25D89719826C} 2057:{3F18FD2A-1F0F-4A0A-96B7-21DB829CE7EB} " Type="16"/>
     <ROW Property="ProductLanguage" Value="2057"/>
     <ROW Property="ProductName" Value="Qortal"/>
-    <ROW Property="ProductVersion" Value="3.2.5" Type="32"/>
+    <ROW Property="ProductVersion" Value="3.3.1" 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="{D5A1DC7D-914F-4425-8BA6-A1AE05D0F361}" Directory_="APPDIR" Attributes="260" KeyPath="DisplayName" Options="1"/>
+    <ROW Component="AI_CustomARPName" ComponentId="{BD915701-2111-4453-8154-1E88163F5548}" 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>3.2.5</version>
+	<version>3.3.2</version>
 	<packaging>jar</packaging>
 	<properties>
 		<skipTests>true</skipTests>

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/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/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().isTopOnly()) {
+			return "topOnly";
+		}
+		else if (Settings.getInstance().isLite()) {
+			return "lite";
+		}
+		else {
+			return "full";
+		}
+	}
+
 	@GET
 	@Path("/status")
 	@Operation(

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/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(

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

@@ -93,17 +93,10 @@ public class ArbitraryDataFile {
         File outputFile = outputFilePath.toFile();
         try (FileOutputStream outputStream = new FileOutputStream(outputFile)) {
             outputStream.write(fileContent);
-            outputStream.close();
             this.filePath = outputFilePath;
-            // Verify hash
-            String digest58 = this.digest58();
-            if (!this.hash58.equals(digest58)) {
-                LOGGER.error("Hash {} does not match file digest {} for signature: {}", this.hash58, digest58, Base58.encode(signature));
-                this.delete();
-                throw new DataException("Data file digest validation failed");
-            }
         } 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/block/BlockChain.java

@@ -69,7 +69,8 @@ public class BlockChain {
 		newBlockSigHeight,
 		shareBinFix,
 		calcChainWeightTimestamp,
-		transactionV5Timestamp;
+		transactionV5Timestamp,
+		transactionV6Timestamp;
 	}
 
 	// Custom transaction fees
@@ -405,6 +406,10 @@ public class BlockChain {
 		return this.featureTriggers.get(FeatureTrigger.transactionV5Timestamp.name()).longValue();
 	}
 
+	public long getTransactionV6Timestamp() {
+		return this.featureTriggers.get(FeatureTrigger.transactionV6Timestamp.name()).longValue();
+	}
+
 	// More complex getters for aspects that change by height or timestamp
 
 	public long getRewardAtHeight(int ourHeight) {

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

@@ -61,6 +61,11 @@ public class BlockMinter extends Thread {
 	public void run() {
 		Thread.currentThread().setName("BlockMinter");
 
+		if (Settings.getInstance().isLite()) {
+			// Lite nodes do not mint
+			return;
+		}
+
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			if (Settings.getInstance().getWipeUnconfirmedOnStart()) {
 				// Wipe existing unconfirmed transactions
@@ -207,14 +212,6 @@ public class BlockMinter extends Thread {
 				// Do we need to build any potential new blocks?
 				List<PrivateKeyAccount> newBlocksMintingAccounts = mintingAccountsData.stream().map(accountData -> new PrivateKeyAccount(repository, accountData.getPrivateKey())).collect(Collectors.toList());
 
-				// We might need to sit the next block out, if one of our minting accounts signed the previous one
-				final byte[] previousBlockMinter = previousBlockData.getMinterPublicKey();
-				final boolean mintedLastBlock = mintingAccountsData.stream().anyMatch(mintingAccount -> Arrays.equals(mintingAccount.getPublicKey(), previousBlockMinter));
-				if (mintedLastBlock) {
-					LOGGER.trace(String.format("One of our keys signed the last block, so we won't sign the next one"));
-					continue;
-				}
-
 				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

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;
@@ -179,6 +183,52 @@ 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() {
@@ -363,23 +413,27 @@ 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
@@ -737,7 +791,11 @@ public class Controller extends Thread {
 		final Long minLatestBlockTimestamp = NTP.getTime() - (30 * 60 * 1000L);
 
 		synchronized (Synchronizer.getInstance().syncLock) {
-			if (this.isMintingPossible) {
+			if (Settings.getInstance().isLite()) {
+				actionText = Translator.INSTANCE.translate("SysTray", "LITE_NODE");
+				SysTray.getInstance().setTrayIcon(4);
+			}
+			else if (this.isMintingPossible) {
 				actionText = Translator.INSTANCE.translate("SysTray", "MINTING_ENABLED");
 				SysTray.getInstance().setTrayIcon(2);
 			}
@@ -759,7 +817,11 @@ public class Controller extends Thread {
 			}
 		}
 
-		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(() -> {
@@ -916,6 +978,11 @@ 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
@@ -1198,6 +1265,26 @@ 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;
@@ -1434,11 +1521,13 @@ 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());
@@ -1448,6 +1537,193 @@ 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
 
@@ -1499,6 +1775,11 @@ 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

@@ -134,6 +134,11 @@ 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);

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;
@@ -11,14 +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 {
 
@@ -55,12 +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());
             }
@@ -87,7 +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;
@@ -104,8 +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?
@@ -115,34 +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())));
                 }
@@ -155,30 +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 {
@@ -188,14 +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: {
@@ -217,7 +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) {
@@ -240,12 +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);
         }
     }
 
@@ -278,8 +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;

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

@@ -283,8 +283,8 @@ 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);
@@ -636,6 +636,9 @@ 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) {

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;
@@ -54,6 +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;
 
@@ -108,6 +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);
     }
 
 
@@ -490,6 +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/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/TradeBot.java

@@ -94,6 +94,7 @@ 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);

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/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();
 		}
 	},
 

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;
@@ -178,6 +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/Network.java

@@ -8,6 +8,7 @@ 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;
@@ -259,6 +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)
@@ -325,6 +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
@@ -685,6 +699,7 @@ 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);
@@ -1069,11 +1084,13 @@ 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

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

@@ -64,6 +64,11 @@ 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;
@@ -194,6 +199,14 @@ 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 +224,11 @@ 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();
@@ -893,6 +911,10 @@ 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/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/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/MessageType.java

@@ -61,7 +61,21 @@ public enum MessageType {
     GET_TRADE_PRESENCES(141, GetTradePresencesMessage::fromByteBuffer),
 
     ARBITRARY_METADATA(150, ArbitraryMetadataMessage::fromByteBuffer),
-    GET_ARBITRARY_METADATA(151, GetArbitraryMetadataMessage::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;

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;
+	}
+
+}

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

@@ -0,0 +1,76 @@
+package org.qortal.network.message;
+
+import com.google.common.primitives.Ints;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.transaction.TransactionTransformer;
+
+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 TransactionsMessage extends Message {
+
+	private List<TransactionData> transactions;
+
+	public TransactionsMessage(List<TransactionData> transactions) throws MessageException {
+		super(MessageType.TRANSACTIONS);
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			bytes.write(Ints.toByteArray(transactions.size()));
+
+			for (int i = 0; i < transactions.size(); ++i) {
+				TransactionData transactionData = transactions.get(i);
+
+				byte[] serializedTransactionData = TransactionTransformer.toBytes(transactionData);
+				bytes.write(serializedTransactionData);
+			}
+
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		} catch (TransformationException e) {
+			throw new MessageException(e.getMessage(), e);
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
+
+	private TransactionsMessage(int id, List<TransactionData> transactions) {
+		super(id, MessageType.TRANSACTIONS);
+
+		this.transactions = transactions;
+	}
+
+	public List<TransactionData> getTransactions() {
+		return this.transactions;
+	}
+
+	public static Message fromByteBuffer(int id, ByteBuffer byteBuffer) throws MessageException {
+		try {
+			final int transactionCount = byteBuffer.getInt();
+
+			List<TransactionData> transactions = new ArrayList<>();
+
+			for (int i = 0; i < transactionCount; ++i) {
+				TransactionData transactionData = TransactionTransformer.fromByteBuffer(byteBuffer);
+				transactions.add(transactionData);
+			}
+
+			if (byteBuffer.hasRemaining()) {
+				throw new BufferUnderflowException();
+			}
+
+			return new TransactionsMessage(id, transactions);
+
+		} catch (TransformationException e) {
+			throw new MessageException(e.getMessage(), e);
+		}
+	}
+
+}

src/main/java/org/qortal/network/task/ChannelAcceptTask.java

@@ -2,6 +2,7 @@ package org.qortal.network.task;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.qortal.controller.arbitrary.ArbitraryDataFileManager;
 import org.qortal.network.Network;
 import org.qortal.network.Peer;
 import org.qortal.network.PeerAddress;
@@ -65,6 +66,47 @@ public class ChannelAcceptTask implements Task {
             return;
         }
 
+        // We allow up to a maximum of maxPeers connected peers, of which...
+        // - maxDataPeers must be prearranged data connections (these are intentionally short-lived)
+        // - the remainder can be any regular peers
+
+        // Firstly, determine the maximum limits
+        int maxPeers = Settings.getInstance().getMaxPeers();
+        int maxDataPeers = Settings.getInstance().getMaxDataPeers();
+        int maxRegularPeers = maxPeers - maxDataPeers;
+
+        // Next, obtain the current state
+        int connectedDataPeerCount = Network.getInstance().getImmutableConnectedDataPeers().size();
+        int connectedRegularPeerCount = Network.getInstance().getImmutableConnectedNonDataPeers().size();
+
+        // Check if the incoming connection should be considered a data or regular peer
+        boolean isDataPeer = ArbitraryDataFileManager.getInstance().isPeerRequestingData(address.getHost());
+
+        // Finally, decide if we have any capacity for this incoming peer
+        boolean connectionLimitReached;
+        if (isDataPeer) {
+            connectionLimitReached = (connectedDataPeerCount >= maxDataPeers);
+        }
+        else {
+            connectionLimitReached = (connectedRegularPeerCount >= maxRegularPeers);
+        }
+
+        // Extra maxPeers check just to be safe
+        if (Network.getInstance().getImmutableConnectedPeers().size() >= maxPeers) {
+            connectionLimitReached = true;
+        }
+
+        if (connectionLimitReached) {
+            try {
+                // We have enough peers
+                LOGGER.debug("Connection discarded from peer {} because the server is full", address);
+                socketChannel.close();
+            } catch (IOException e) {
+                // IGNORE
+            }
+            return;
+        }
+
         final Long now = NTP.getTime();
         Peer newPeer;
 
@@ -78,6 +120,10 @@ public class ChannelAcceptTask implements Task {
             LOGGER.debug("Connection accepted from peer {}", address);
 
             newPeer = new Peer(socketChannel);
+            if (isDataPeer) {
+                newPeer.setMaxConnectionAge(Settings.getInstance().getMaxDataPeerConnectionTime() * 1000L);
+            }
+            newPeer.setIsDataPeer(isDataPeer);
             network.addConnectedPeer(newPeer);
 
         } catch (IOException e) {

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

@@ -62,6 +62,11 @@ public abstract class RepositoryManager {
 	}
 
 	public static boolean archive(Repository repository) {
+		if (Settings.getInstance().isLite()) {
+			// Lite nodes have no blockchain
+			return false;
+		}
+
 		// Bulk archive the database the first time we use archive mode
 		if (Settings.getInstance().isArchiveEnabled()) {
 			if (RepositoryManager.canArchiveOrPrune()) {
@@ -82,6 +87,11 @@ public abstract class RepositoryManager {
 	}
 
 	public static boolean prune(Repository repository) {
+		if (Settings.getInstance().isLite()) {
+			// Lite nodes have no blockchain
+			return false;
+		}
+
 		// Bulk prune the database the first time we use top-only or block archive mode
 		if (Settings.getInstance().isTopOnly() ||
 			Settings.getInstance().isArchiveEnabled()) {

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

@@ -257,7 +257,8 @@ public interface TransactionRepository {
 	 * @return list of transactions, or empty if none.
 	 * @throws DataException
 	 */
-	public List<TransactionData> getUnconfirmedTransactions(Integer limit, Integer offset, Boolean reverse) throws DataException;
+	public List<TransactionData> getUnconfirmedTransactions(List<TransactionType> txTypes, byte[] creatorPublicKey,
+															Integer limit, Integer offset, Boolean reverse) throws DataException;
 
 	/**
 	 * Returns list of unconfirmed transactions in timestamp-else-signature order.
@@ -266,7 +267,7 @@ public interface TransactionRepository {
 	 * @throws DataException
 	 */
 	public default List<TransactionData> getUnconfirmedTransactions() throws DataException {
-		return getUnconfirmedTransactions(null, null, null);
+		return getUnconfirmedTransactions(null, null, null, null, null);
 	}
 
 	/**

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

@@ -313,7 +313,7 @@ public class HSQLDBTransactionRepository implements TransactionRepository {
 
 	@Override
 	public List<byte[]> getSignaturesInvolvingAddress(String address) throws DataException {
-		String sql = "SELECT signature FROM TransactionRecipients WHERE participant = ?";
+		String sql = "SELECT signature FROM TransactionParticipants WHERE participant = ?";
 
 		List<byte[]> signatures = new ArrayList<>();
 
@@ -1213,11 +1213,56 @@ public class HSQLDBTransactionRepository implements TransactionRepository {
 	}
 
 	@Override
-	public List<TransactionData> getUnconfirmedTransactions(Integer limit, Integer offset, Boolean reverse) throws DataException {
-		StringBuilder sql = new StringBuilder(256);
-		sql.append("SELECT signature FROM UnconfirmedTransactions ");
+	public List<TransactionData> getUnconfirmedTransactions(List<TransactionType> txTypes, byte[] creatorPublicKey,
+															Integer limit, Integer offset, Boolean reverse) throws DataException {
+		List<String> whereClauses = new ArrayList<>();
+		List<Object> bindParams = new ArrayList<>();
 
-		sql.append("ORDER BY created_when");
+		boolean hasCreatorPublicKey = creatorPublicKey != null;
+		boolean hasTxTypes = txTypes != null && !txTypes.isEmpty();
+
+		if (creatorPublicKey != null) {
+			whereClauses.add("Transactions.creator = ?");
+			bindParams.add(creatorPublicKey);
+		}
+
+		StringBuilder sql = new StringBuilder(256);
+		sql.append("SELECT signature FROM UnconfirmedTransactions");
+		if (hasCreatorPublicKey || hasTxTypes) {
+			sql.append(" JOIN Transactions USING (signature) ");
+		}
+
+		if (hasTxTypes) {
+			StringBuilder txTypesIn = new StringBuilder(256);
+			txTypesIn.append("Transactions.type IN (");
+
+			// ints are safe enough to use literally
+			final int txTypesSize = txTypes.size();
+			for (int tti = 0; tti < txTypesSize; ++tti) {
+				if (tti != 0)
+					txTypesIn.append(", ");
+
+				txTypesIn.append(txTypes.get(tti).value);
+			}
+
+			txTypesIn.append(")");
+
+			whereClauses.add(txTypesIn.toString());
+		}
+
+		if (!whereClauses.isEmpty()) {
+			sql.append(" WHERE ");
+
+			final int whereClausesSize = whereClauses.size();
+			for (int wci = 0; wci < whereClausesSize; ++wci) {
+				if (wci != 0)
+					sql.append(" AND ");
+
+				sql.append(whereClauses.get(wci));
+			}
+		}
+
+		sql.append(" ORDER BY created_when");
 		if (reverse != null && reverse)
 			sql.append(" DESC");
 
@@ -1230,7 +1275,7 @@ public class HSQLDBTransactionRepository implements TransactionRepository {
 		List<TransactionData> transactions = new ArrayList<>();
 
 		// Find transactions with no corresponding row in BlockTransactions
-		try (ResultSet resultSet = this.repository.checkedExecute(sql.toString())) {
+		try (ResultSet resultSet = this.repository.checkedExecute(sql.toString(), bindParams.toArray())) {
 			if (resultSet == null)
 				return transactions;
 

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

@@ -145,6 +145,8 @@ public class Settings {
 	 * This has a significant effect on execution time. */
 	private int onlineSignaturesTrimBatchSize = 100; // blocks
 
+	/** Lite nodes don't sync blocks, and instead request "derived data" from peers */
+	private boolean lite = false;
 
 	/** Whether we should prune old data to reduce database size
 	 * This prevents the node from being able to serve older blocks */
@@ -190,7 +192,9 @@ public class Settings {
 	/** Target number of outbound connections to peers we should make. */
 	private int minOutboundPeers = 16;
 	/** Maximum number of peer connections we allow. */
-	private int maxPeers = 32;
+	private int maxPeers = 36;
+	/** Number of slots to reserve for short-lived QDN data transfers */
+	private int maxDataPeers = 4;
 	/** Maximum number of threads for network engine. */
 	private int maxNetworkThreadPoolSize = 32;
 	/** Maximum number of threads for network proof-of-work compute, used during handshaking. */
@@ -209,6 +213,8 @@ public class Settings {
 	private int minPeerConnectionTime = 5 * 60; // seconds
 	/** Maximum time (in seconds) that we should attempt to remain connected to a peer for */
 	private int maxPeerConnectionTime = 60 * 60; // seconds
+	/** Maximum time (in seconds) that a peer should remain connected when requesting QDN data */
+	private int maxDataPeerConnectionTime = 2 * 60; // seconds
 
 	/** Whether to sync multiple blocks at once in normal operation */
 	private boolean fastSyncEnabled = true;
@@ -650,6 +656,10 @@ public class Settings {
 		return this.maxPeers;
 	}
 
+	public int getMaxDataPeers() {
+		return this.maxDataPeers;
+	}
+
 	public int getMaxNetworkThreadPoolSize() {
 		return this.maxNetworkThreadPoolSize;
 	}
@@ -668,6 +678,10 @@ public class Settings {
 
 	public int getMaxPeerConnectionTime() { return this.maxPeerConnectionTime; }
 
+	public int getMaxDataPeerConnectionTime() {
+		return this.maxDataPeerConnectionTime;
+	}
+
 	public String getBlockchainConfig() {
 		return this.blockchainConfig;
 	}
@@ -808,6 +822,10 @@ public class Settings {
 		return this.onlineSignaturesTrimBatchSize;
 	}
 
+	public boolean isLite() {
+		return this.lite;
+	}
+
 	public boolean isTopOnly() {
 		return this.topOnly;
 	}

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

@@ -114,7 +114,7 @@ public class BuyNameTransaction extends Transaction {
 	public void process() throws DataException {
 		// Buy Name
 		Name name = new Name(this.repository, this.buyNameTransactionData.getName());
-		name.buy(this.buyNameTransactionData);
+		name.buy(this.buyNameTransactionData, true);
 
 		// Save transaction with updated "name reference" pointing to previous transaction that changed name
 		this.repository.getTransactionRepository().save(this.buyNameTransactionData);

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

@@ -393,7 +393,10 @@ public abstract class Transaction {
 	 * @return transaction version number
 	 */
 	public static int getVersionByTimestamp(long timestamp) {
-		if (timestamp >= BlockChain.getInstance().getTransactionV5Timestamp()) {
+		if (timestamp >= BlockChain.getInstance().getTransactionV6Timestamp()) {
+			return 6;
+		}
+		else if (timestamp >= BlockChain.getInstance().getTransactionV5Timestamp()) {
 			return 5;
 		}
 		return 4;
@@ -530,11 +533,6 @@ public abstract class Transaction {
 		if (now >= this.getDeadline())
 			return ValidationResult.TIMESTAMP_TOO_OLD;
 
-		// Transactions with a expiry prior to latest block's timestamp are too old
-		BlockData latestBlock = repository.getBlockRepository().getLastBlock();
-		if (this.getDeadline() <= latestBlock.getTimestamp())
-			return ValidationResult.TIMESTAMP_TOO_OLD;
-
 		// Transactions with a timestamp too far into future are too new
 		long maxTimestamp = now + Settings.getInstance().getMaxTransactionTimestampFuture();
 		if (this.transactionData.getTimestamp() > maxTimestamp)
@@ -545,6 +543,15 @@ public abstract class Transaction {
 		if (feeValidationResult != ValidationResult.OK)
 			return feeValidationResult;
 
+		if (Settings.getInstance().isLite()) {
+			// Everything from this point is difficult to validate for a lite node, since it has no blocks.
+			// For now, we will assume it is valid, to allow it to move around the network easily.
+			// If it turns out to be invalid, other full/top-only nodes will reject it on receipt.
+			// Lite nodes would never mint a block, so there's not much risk of holding invalid transactions.
+			// TODO: implement lite-only validation for each transaction type
+			return ValidationResult.OK;
+		}
+
 		PublicKeyAccount creator = this.getCreator();
 		if (creator == null)
 			return ValidationResult.MISSING_CREATOR;
@@ -553,6 +560,12 @@ public abstract class Transaction {
 		if (countUnconfirmedByCreator(creator) >= Settings.getInstance().getMaxUnconfirmedPerAccount())
 			return ValidationResult.TOO_MANY_UNCONFIRMED;
 
+		// Transactions with a expiry prior to latest block's timestamp are too old
+		// Not relevant for lite nodes, as they don't have any blocks
+		BlockData latestBlock = repository.getBlockRepository().getLastBlock();
+		if (this.getDeadline() <= latestBlock.getTimestamp())
+			return ValidationResult.TIMESTAMP_TOO_OLD;
+
 		// Check transaction's txGroupId
 		if (!this.isValidTxGroupId())
 			return ValidationResult.INVALID_TX_GROUP_ID;

src/main/java/org/qortal/transform/transaction/AtTransactionTransformer.java

@@ -4,8 +4,12 @@ import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.nio.ByteBuffer;
 
+import org.qortal.account.NullAccount;
 import org.qortal.data.transaction.ATTransactionData;
+import org.qortal.data.transaction.BaseTransactionData;
 import org.qortal.data.transaction.TransactionData;
+import org.qortal.group.Group;
+import org.qortal.transaction.Transaction;
 import org.qortal.transform.TransformationException;
 import org.qortal.utils.Serialization;
 
@@ -17,12 +21,97 @@ public class AtTransactionTransformer extends TransactionTransformer {
 	protected static final TransactionLayout layout = null;
 
 	// Property lengths
+
+	private static final int MESSAGE_SIZE_LENGTH = INT_LENGTH;
+	private static final int TYPE_LENGTH = INT_LENGTH;
+
+
 	public static TransactionData fromByteBuffer(ByteBuffer byteBuffer) throws TransformationException {
-		throw new TransformationException("Serialized AT transactions should not exist!");
+		long timestamp = byteBuffer.getLong();
+
+		int version = Transaction.getVersionByTimestamp(timestamp);
+
+		byte[] reference = new byte[REFERENCE_LENGTH];
+		byteBuffer.get(reference);
+
+		String atAddress = Serialization.deserializeAddress(byteBuffer);
+
+		String recipient = Serialization.deserializeAddress(byteBuffer);
+
+		// Default to PAYMENT-type, as there were no MESSAGE-type transactions before transaction v6
+		boolean isMessageType = false;
+
+		if (version >= 6) {
+			// Version 6 supports both PAYMENT-type and MESSAGE-type, specified using an integer.
+			// This could be extended to support additional types at a later date, simply by adding
+			// additional integer values.
+			int type = byteBuffer.getInt();
+			isMessageType = (type == 1);
+		}
+
+		int messageLength = 0;
+		byte[] message = null;
+		long assetId = 0L;
+		long amount = 0L;
+
+		if (isMessageType) {
+			messageLength = byteBuffer.getInt();
+
+			message = new byte[messageLength];
+			byteBuffer.get(message);
+		}
+		else {
+			// Assume PAYMENT-type, as there were no MESSAGE-type transactions until this time
+			assetId = byteBuffer.getLong();
+
+			amount = byteBuffer.getLong();
+		}
+
+		long fee = byteBuffer.getLong();
+
+		byte[] signature = new byte[SIGNATURE_LENGTH];
+		byteBuffer.get(signature);
+
+		BaseTransactionData baseTransactionData = new BaseTransactionData(timestamp, Group.NO_GROUP, reference, NullAccount.PUBLIC_KEY, fee, signature);
+
+		if (isMessageType) {
+			// MESSAGE-type
+			return new ATTransactionData(baseTransactionData, atAddress, recipient, message);
+		}
+		else {
+			// PAYMENT-type
+			return new ATTransactionData(baseTransactionData, atAddress, recipient, amount, assetId);
+		}
+
 	}
 
 	public static int getDataLength(TransactionData transactionData) throws TransformationException {
-		throw new TransformationException("Serialized AT transactions should not exist!");
+		ATTransactionData atTransactionData = (ATTransactionData) transactionData;
+		int version = Transaction.getVersionByTimestamp(transactionData.getTimestamp());
+
+		final int baseLength = TYPE_LENGTH + TIMESTAMP_LENGTH + REFERENCE_LENGTH + ADDRESS_LENGTH + ADDRESS_LENGTH +
+				FEE_LENGTH + SIGNATURE_LENGTH;
+
+		int typeSpecificLength = 0;
+
+		byte[] message = atTransactionData.getMessage();
+		boolean isMessageType = (message != null);
+
+		// MESSAGE-type and PAYMENT-type transactions will have differing lengths
+		if (isMessageType) {
+			typeSpecificLength = MESSAGE_SIZE_LENGTH + message.length;
+		}
+		else {
+			typeSpecificLength = ASSET_ID_LENGTH + AMOUNT_LENGTH;
+		}
+
+		// V6 transactions include an extra integer to denote the type
+		int versionSpecificLength = 0;
+		if (version >= 6) {
+			versionSpecificLength = TYPE_LENGTH;
+		}
+
+		return baseLength + typeSpecificLength + versionSpecificLength;
 	}
 
 	// Used for generating fake transaction signatures
@@ -30,6 +119,8 @@ public class AtTransactionTransformer extends TransactionTransformer {
 		try {
 			ATTransactionData atTransactionData = (ATTransactionData) transactionData;
 
+			int version = Transaction.getVersionByTimestamp(atTransactionData.getTimestamp());
+
 			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
 
 			bytes.write(Ints.toByteArray(atTransactionData.getType().value));
@@ -42,7 +133,17 @@ public class AtTransactionTransformer extends TransactionTransformer {
 
 			byte[] message = atTransactionData.getMessage();
 
-			if (message != null) {
+			boolean isMessageType = (message != null);
+			int type = isMessageType ? 1 : 0;
+
+			if (version >= 6) {
+				// Version 6 supports both PAYMENT-type and MESSAGE-type, specified using an integer.
+				// This could be extended to support additional types at a later date, simply by adding
+				// additional integer values.
+				bytes.write(Ints.toByteArray(type));
+			}
+
+			if (isMessageType) {
 				// MESSAGE-type
 				bytes.write(Ints.toByteArray(message.length));
 				bytes.write(message);

src/main/resources/blockchain.json

@@ -58,7 +58,8 @@
 		"newBlockSigHeight": 320000,
 		"shareBinFix": 399000,
 		"calcChainWeightTimestamp": 1620579600000,
-		"transactionV5Timestamp": 1642176000000
+		"transactionV5Timestamp": 1642176000000,
+		"transactionV6Timestamp": 9999999999999
 	},
 	"genesisInfo": {
 		"version": 4,

src/main/resources/i18n/SysTray_de.properties

@@ -27,6 +27,8 @@ DB_MAINTENANCE = Datenbank Instandhaltung
 
 EXIT = Verlassen
 
+LITE_NODE = Lite node
+
 MINTING_DISABLED = NOT minting
 
 MINTING_ENABLED = \u2714 Minting

src/main/resources/i18n/SysTray_en.properties

@@ -27,6 +27,8 @@ DB_MAINTENANCE = Database Maintenance
 
 EXIT = Exit
 
+LITE_NODE = Lite node
+
 MINTING_DISABLED = NOT minting
 
 MINTING_ENABLED = \u2714 Minting

src/main/resources/i18n/SysTray_fi.properties

@@ -27,6 +27,8 @@ DB_MAINTENANCE = Tietokannan ylläpito
 
 EXIT = Pois
 
+LITE_NODE = Lite node
+
 MINTING_DISABLED = EI lyö rahaa
 
 MINTING_ENABLED = \u2714 Lyö rahaa

src/main/resources/i18n/SysTray_fr.properties

@@ -27,6 +27,8 @@ DB_MAINTENANCE = Maintenance de la base de données
 
 EXIT = Quitter
 
+LITE_NODE = Lite node
+
 MINTING_DISABLED = NE mint PAS
 
 MINTING_ENABLED = \u2714 Minting

src/main/resources/i18n/SysTray_hu.properties

@@ -27,6 +27,8 @@ DB_MAINTENANCE = Adatbázis karbantartás
 
 EXIT = Kilépés
 
+LITE_NODE = Lite node
+
 MINTING_DISABLED = QORT-érmeverés jelenleg nincs folyamatban
 
 MINTING_ENABLED = \u2714 QORT-érmeverés folyamatban

src/main/resources/i18n/SysTray_it.properties

@@ -27,6 +27,8 @@ DB_MAINTENANCE = Manutenzione del database
 
 EXIT = Uscita
 
+LITE_NODE = Lite node
+
 MINTING_DISABLED = Conio disabilitato
 
 MINTING_ENABLED = \u2714 Conio abilitato

src/main/resources/i18n/SysTray_nl.properties

@@ -27,6 +27,8 @@ DB_MAINTENANCE = Database Onderhoud
 
 EXIT = Verlaten
 
+LITE_NODE = Lite node
+
 MINTING_DISABLED = Minten is uitgeschakeld
 
 MINTING_ENABLED = \u2714 Minten is ingeschakeld

src/main/resources/i18n/SysTray_ru.properties

@@ -27,6 +27,8 @@ DB_MAINTENANCE = Обслуживание базы данных
 
 EXIT = Выход
 
+LITE_NODE = Lite node
+
 MINTING_DISABLED = Чеканка отключена
 
 MINTING_ENABLED = \u2714 Чеканка активна

src/main/resources/i18n/SysTray_zh_CN.properties

@@ -27,6 +27,8 @@ DB_MAINTENANCE = 数据库维护
 
 EXIT = 退出核心
 
+LITE_NODE = Lite node
+
 MINTING_DISABLED = 没有铸币
 
 MINTING_ENABLED = \u2714 铸币

src/main/resources/i18n/SysTray_zh_TW.properties

@@ -27,6 +27,8 @@ DB_MAINTENANCE = 數據庫維護
 
 EXIT = 退出核心
 
+LITE_NODE = Lite node
+
 MINTING_DISABLED = 沒有鑄幣
 
 MINTING_ENABLED = \u2714 鑄幣

src/test/java/org/qortal/test/SerializationTests.java

@@ -47,7 +47,6 @@ public class SerializationTests extends Common {
 				switch (txType) {
 					case GENESIS:
 					case ACCOUNT_FLAGS:
-					case AT:
 					case CHAT:
 					case PUBLICIZE:
 					case AIRDROP:

src/test/java/org/qortal/test/api/TransactionsApiTests.java

@@ -36,8 +36,8 @@ public class TransactionsApiTests extends ApiCommon {
 
 	@Test
 	public void testGetUnconfirmedTransactions() {
-		assertNotNull(this.transactionsResource.getUnconfirmedTransactions(null, null, null));
-		assertNotNull(this.transactionsResource.getUnconfirmedTransactions(1, 1, true));
+		assertNotNull(this.transactionsResource.getUnconfirmedTransactions(null, null, null, null, null));
+		assertNotNull(this.transactionsResource.getUnconfirmedTransactions(null, null, 1, 1, true));
 	}
 
 	@Test

src/test/java/org/qortal/test/apps/CheckTranslations.java

@@ -15,7 +15,7 @@ public class CheckTranslations {
 	private static final String[] SUPPORTED_LANGS = new String[] { "en", "de", "zh", "ru" };
 	private static final Set<String> SYSTRAY_KEYS = Set.of("AUTO_UPDATE", "APPLYING_UPDATE_AND_RESTARTING", "BLOCK_HEIGHT",
 			"BUILD_VERSION", "CHECK_TIME_ACCURACY", "CONNECTING", "CONNECTION", "CONNECTIONS", "CREATING_BACKUP_OF_DB_FILES",
-			"DB_BACKUP", "DB_CHECKPOINT", "EXIT", "MINTING_DISABLED", "MINTING_ENABLED", "OPEN_UI", "PERFORMING_DB_CHECKPOINT",
+			"DB_BACKUP", "DB_CHECKPOINT", "EXIT", "LITE_NODE", "MINTING_DISABLED", "MINTING_ENABLED", "OPEN_UI", "PERFORMING_DB_CHECKPOINT",
 			"SYNCHRONIZE_CLOCK", "SYNCHRONIZING_BLOCKCHAIN", "SYNCHRONIZING_CLOCK");
 
 	private static String failurePrefix;

src/test/java/org/qortal/test/at/AtSerializationTests.java

@@ -0,0 +1,96 @@
+package org.qortal.test.at;
+
+import com.google.common.hash.HashCode;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.data.transaction.ATTransactionData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.test.common.Common;
+import org.qortal.test.common.transaction.AtTestTransaction;
+import org.qortal.transaction.Transaction;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.transaction.TransactionTransformer;
+import org.qortal.utils.Base58;
+
+import static org.junit.Assert.assertEquals;
+
+public class AtSerializationTests extends Common {
+
+    @Before
+    public void beforeTest() throws DataException {
+        Common.useDefaultSettings();
+    }
+
+    @After
+    public void afterTest() throws DataException {
+        Common.orphanCheck();
+    }
+
+
+    @Test
+    public void testPaymentTypeAtSerialization() throws DataException, TransformationException {
+        try (final Repository repository = RepositoryManager.getRepository()) {
+
+            // Build PAYMENT-type AT transaction
+            PrivateKeyAccount signingAccount = Common.getTestAccount(repository, "alice");
+            ATTransactionData transactionData = (ATTransactionData) AtTestTransaction.paymentType(repository, signingAccount, true);
+            Transaction transaction = Transaction.fromData(repository, transactionData);
+            transaction.sign(signingAccount);
+
+            final int claimedLength = TransactionTransformer.getDataLength(transactionData);
+            byte[] serializedTransaction = TransactionTransformer.toBytes(transactionData);
+            assertEquals("Serialized PAYMENT-type AT transaction length differs from declared length", claimedLength, serializedTransaction.length);
+
+            TransactionData deserializedTransactionData = TransactionTransformer.fromBytes(serializedTransaction);
+            // Re-sign
+            Transaction deserializedTransaction = Transaction.fromData(repository, deserializedTransactionData);
+            deserializedTransaction.sign(signingAccount);
+            assertEquals("Deserialized PAYMENT-type AT transaction signature differs", Base58.encode(transactionData.getSignature()), Base58.encode(deserializedTransactionData.getSignature()));
+
+            // Re-serialize to check new length and bytes
+            final int reclaimedLength = TransactionTransformer.getDataLength(deserializedTransactionData);
+            assertEquals("Reserialized PAYMENT-type AT transaction declared length differs", claimedLength, reclaimedLength);
+
+            byte[] reserializedTransaction = TransactionTransformer.toBytes(deserializedTransactionData);
+            assertEquals("Reserialized PAYMENT-type AT transaction bytes differ", HashCode.fromBytes(serializedTransaction).toString(), HashCode.fromBytes(reserializedTransaction).toString());
+        }
+    }
+
+    @Test
+    public void testMessageTypeAtSerialization() throws DataException, TransformationException {
+        try (final Repository repository = RepositoryManager.getRepository()) {
+
+            // Build MESSAGE-type AT transaction
+            PrivateKeyAccount signingAccount = Common.getTestAccount(repository, "alice");
+            ATTransactionData transactionData = (ATTransactionData) AtTestTransaction.messageType(repository, signingAccount, true);
+            Transaction transaction = Transaction.fromData(repository, transactionData);
+            transaction.sign(signingAccount);
+
+            // MESSAGE-type AT transactions are only fully supported since transaction V6
+            assertEquals(6, Transaction.getVersionByTimestamp(transactionData.getTimestamp()));
+
+            final int claimedLength = TransactionTransformer.getDataLength(transactionData);
+            byte[] serializedTransaction = TransactionTransformer.toBytes(transactionData);
+            assertEquals("Serialized MESSAGE-type AT transaction length differs from declared length", claimedLength, serializedTransaction.length);
+
+            TransactionData deserializedTransactionData = TransactionTransformer.fromBytes(serializedTransaction);
+            // Re-sign
+            Transaction deserializedTransaction = Transaction.fromData(repository, deserializedTransactionData);
+            deserializedTransaction.sign(signingAccount);
+            assertEquals("Deserialized MESSAGE-type AT transaction signature differs", Base58.encode(transactionData.getSignature()), Base58.encode(deserializedTransactionData.getSignature()));
+
+            // Re-serialize to check new length and bytes
+            final int reclaimedLength = TransactionTransformer.getDataLength(deserializedTransactionData);
+            assertEquals("Reserialized MESSAGE-type AT transaction declared length differs", claimedLength, reclaimedLength);
+
+            byte[] reserializedTransaction = TransactionTransformer.toBytes(deserializedTransactionData);
+            assertEquals("Reserialized MESSAGE-type AT transaction bytes differ", HashCode.fromBytes(serializedTransaction).toString(), HashCode.fromBytes(reserializedTransaction).toString());
+        }
+    }
+
+}

src/test/java/org/qortal/test/common/transaction/AtTestTransaction.java

@@ -12,16 +12,33 @@ import org.qortal.utils.Amounts;
 public class AtTestTransaction extends TestTransaction {
 
 	public static TransactionData randomTransaction(Repository repository, PrivateKeyAccount account, boolean wantValid) throws DataException {
+		return AtTestTransaction.paymentType(repository, account, wantValid);
+	}
+
+	public static TransactionData paymentType(Repository repository, PrivateKeyAccount account, boolean wantValid) throws DataException {
 		byte[] signature = new byte[64];
 		random.nextBytes(signature);
 		String atAddress = Crypto.toATAddress(signature);
 		String recipient = account.getAddress();
+
+		// Use PAYMENT-type
 		long amount = 123L * Amounts.MULTIPLIER;
 		final long assetId = Asset.QORT;
+
+		return new ATTransactionData(generateBase(account), atAddress, recipient, amount, assetId);
+	}
+
+	public static TransactionData messageType(Repository repository, PrivateKeyAccount account, boolean wantValid) throws DataException {
+		byte[] signature = new byte[64];
+		random.nextBytes(signature);
+		String atAddress = Crypto.toATAddress(signature);
+		String recipient = account.getAddress();
+
+		// Use MESSAGE-type
 		byte[] message = new byte[32];
 		random.nextBytes(message);
 
-		return new ATTransactionData(generateBase(account), atAddress, recipient, amount, assetId, message);
+		return new ATTransactionData(generateBase(account), atAddress, recipient, message);
 	}
 
 }

src/test/java/org/qortal/test/crosschain/DigibyteTests.java

@@ -82,7 +82,7 @@ public class DigibyteTests extends Common {
 
 	@Test
 	public void testGetWalletBalance() {
-		String xprv58 = "tprv8ZgxMBicQKsPdahhFSrCdvC1bsWyzHHZfTneTVqUXN6s1wEtZLwAkZXzFP6TYLg2aQMecZLXLre5bTVGajEB55L1HYJcawpdFG66STVAWPJ";
+		String xprv58 = "xpub661MyMwAqRbcEnabTLX5uebYcsE3uG5y7ve9jn1VK8iY1MaU3YLoLJEe8sTu2YVav5Zka5qf2dmMssfxmXJTqZnazZL2kL7M2tNKwEoC34R";
 
 		Long balance = digibyte.getWalletBalance(xprv58);
 
@@ -103,7 +103,7 @@ public class DigibyteTests extends Common {
 
 	@Test
 	public void testGetUnusedReceiveAddress() throws ForeignBlockchainException {
-		String xprv58 = "tprv8ZgxMBicQKsPdahhFSrCdvC1bsWyzHHZfTneTVqUXN6s1wEtZLwAkZXzFP6TYLg2aQMecZLXLre5bTVGajEB55L1HYJcawpdFG66STVAWPJ";
+		String xprv58 = "xpub661MyMwAqRbcEnabTLX5uebYcsE3uG5y7ve9jn1VK8iY1MaU3YLoLJEe8sTu2YVav5Zka5qf2dmMssfxmXJTqZnazZL2kL7M2tNKwEoC34R";
 
 		String address = digibyte.getUnusedReceiveAddress(xprv58);
 

src/test/java/org/qortal/test/crosschain/RavencoinTests.java

@@ -82,7 +82,7 @@ public class RavencoinTests extends Common {
 
 	@Test
 	public void testGetWalletBalance() {
-		String xprv58 = "tprv8ZgxMBicQKsPdahhFSrCdvC1bsWyzHHZfTneTVqUXN6s1wEtZLwAkZXzFP6TYLg2aQMecZLXLre5bTVGajEB55L1HYJcawpdFG66STVAWPJ";
+		String xprv58 = "xpub661MyMwAqRbcEt3Ge1wNmkagyb1J7yTQu4Kquvy77Ycg2iPoh7Urg8s9Jdwp7YmrqGkDKJpUVjsZXSSsQgmAVUC17ZVQQeoWMzm7vDTt1y7";
 
 		Long balance = ravencoin.getWalletBalance(xprv58);
 
@@ -103,7 +103,7 @@ public class RavencoinTests extends Common {
 
 	@Test
 	public void testGetUnusedReceiveAddress() throws ForeignBlockchainException {
-		String xprv58 = "tprv8ZgxMBicQKsPdahhFSrCdvC1bsWyzHHZfTneTVqUXN6s1wEtZLwAkZXzFP6TYLg2aQMecZLXLre5bTVGajEB55L1HYJcawpdFG66STVAWPJ";
+		String xprv58 = "xpub661MyMwAqRbcEt3Ge1wNmkagyb1J7yTQu4Kquvy77Ycg2iPoh7Urg8s9Jdwp7YmrqGkDKJpUVjsZXSSsQgmAVUC17ZVQQeoWMzm7vDTt1y7";
 
 		String address = ravencoin.getUnusedReceiveAddress(xprv58);
 

src/test/java/org/qortal/test/crosschain/bitcoinv3/BitcoinACCTv3Tests.java

@@ -0,0 +1,769 @@
+package org.qortal.test.crosschain.bitcoinv3;
+
+import com.google.common.hash.HashCode;
+import com.google.common.primitives.Bytes;
+import org.junit.Before;
+import org.junit.Test;
+import org.qortal.account.Account;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.asset.Asset;
+import org.qortal.block.Block;
+import org.qortal.crosschain.AcctMode;
+import org.qortal.crosschain.BitcoinACCTv3;
+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.BaseTransactionData;
+import org.qortal.data.transaction.DeployAtTransactionData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.test.common.BlockUtils;
+import org.qortal.test.common.Common;
+import org.qortal.test.common.TransactionUtils;
+import org.qortal.transaction.DeployAtTransaction;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.utils.Amounts;
+
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.ZoneOffset;
+import java.time.format.DateTimeFormatter;
+import java.time.format.FormatStyle;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Random;
+import java.util.function.Function;
+
+import static org.junit.Assert.*;
+
+public class BitcoinACCTv3Tests extends Common {
+
+	public static final byte[] secretA = "This string is exactly 32 bytes!".getBytes();
+	public static final byte[] hashOfSecretA = Crypto.hash160(secretA); // daf59884b4d1aec8c1b17102530909ee43c0151a
+	public static final byte[] bitcoinPublicKeyHash = HashCode.fromString("bb00bb11bb22bb33bb44bb55bb66bb77bb88bb99").asBytes();
+	public static final int tradeTimeout = 20; // blocks
+	public static final long redeemAmount = 80_40200000L;
+	public static final long fundingAmount = 123_45600000L;
+	public static final long bitcoinAmount = 864200L; // 0.00864200 BTC
+
+	private static final Random RANDOM = new Random();
+
+	@Before
+	public void beforeTest() throws DataException {
+		Common.useDefaultSettings();
+	}
+
+	@Test
+	public void testCompile() {
+		PrivateKeyAccount tradeAccount = createTradeAccount(null);
+
+		byte[] creationBytes = BitcoinACCTv3.buildQortalAT(tradeAccount.getAddress(), bitcoinPublicKeyHash, redeemAmount, bitcoinAmount, tradeTimeout);
+		assertNotNull(creationBytes);
+
+		System.out.println("AT creation bytes: " + HashCode.fromBytes(creationBytes).toString());
+	}
+
+	@Test
+	public void testDeploy() throws DataException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PrivateKeyAccount deployer = Common.getTestAccount(repository, "chloe");
+			PrivateKeyAccount tradeAccount = createTradeAccount(repository);
+
+			PrivateKeyAccount partner = Common.getTestAccount(repository, "dilbert");
+
+			long deployersInitialBalance = deployer.getConfirmedBalance(Asset.QORT);
+			long partnersInitialBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			DeployAtTransaction deployAtTransaction = doDeploy(repository, deployer, tradeAccount.getAddress());
+
+			long expectedBalance = deployersInitialBalance - fundingAmount - deployAtTransaction.getTransactionData().getFee();
+			long actualBalance = deployer.getConfirmedBalance(Asset.QORT);
+
+			assertEquals("Deployer's post-deployment balance incorrect", expectedBalance, actualBalance);
+
+			expectedBalance = fundingAmount;
+			actualBalance = deployAtTransaction.getATAccount().getConfirmedBalance(Asset.QORT);
+
+			assertEquals("AT's post-deployment balance incorrect", expectedBalance, actualBalance);
+
+			expectedBalance = partnersInitialBalance;
+			actualBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			assertEquals("Partner's post-deployment balance incorrect", expectedBalance, actualBalance);
+
+			// Test orphaning
+			BlockUtils.orphanLastBlock(repository);
+
+			expectedBalance = deployersInitialBalance;
+			actualBalance = deployer.getConfirmedBalance(Asset.QORT);
+
+			assertEquals("Deployer's post-orphan/pre-deployment balance incorrect", expectedBalance, actualBalance);
+
+			expectedBalance = 0;
+			actualBalance = deployAtTransaction.getATAccount().getConfirmedBalance(Asset.QORT);
+
+			assertEquals("AT's post-orphan/pre-deployment balance incorrect", expectedBalance, actualBalance);
+
+			expectedBalance = partnersInitialBalance;
+			actualBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			assertEquals("Partner's post-orphan/pre-deployment balance incorrect", expectedBalance, actualBalance);
+		}
+	}
+
+	@SuppressWarnings("unused")
+	@Test
+	public void testOfferCancel() throws DataException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PrivateKeyAccount deployer = Common.getTestAccount(repository, "chloe");
+			PrivateKeyAccount tradeAccount = createTradeAccount(repository);
+
+			PrivateKeyAccount partner = Common.getTestAccount(repository, "dilbert");
+
+			long deployersInitialBalance = deployer.getConfirmedBalance(Asset.QORT);
+			long partnersInitialBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			DeployAtTransaction deployAtTransaction = doDeploy(repository, deployer, tradeAccount.getAddress());
+			Account at = deployAtTransaction.getATAccount();
+			String atAddress = at.getAddress();
+
+			long deployAtFee = deployAtTransaction.getTransactionData().getFee();
+			long deployersPostDeploymentBalance = deployersInitialBalance - fundingAmount - deployAtFee;
+
+			// Send creator's address to AT, instead of typical partner's address
+			byte[] messageData = BitcoinACCTv3.getInstance().buildCancelMessage(deployer.getAddress());
+			MessageTransaction messageTransaction = sendMessage(repository, deployer, messageData, atAddress);
+			long messageFee = messageTransaction.getTransactionData().getFee();
+
+			// AT should process 'cancel' message in next block
+			BlockUtils.mintBlock(repository);
+
+			describeAt(repository, atAddress);
+
+			// Check AT is finished
+			ATData atData = repository.getATRepository().fromATAddress(atAddress);
+			assertTrue(atData.getIsFinished());
+
+			// AT should be in CANCELLED mode
+			CrossChainTradeData tradeData = BitcoinACCTv3.getInstance().populateTradeData(repository, atData);
+			assertEquals(AcctMode.CANCELLED, tradeData.mode);
+
+			// Check balances
+			long expectedMinimumBalance = deployersPostDeploymentBalance;
+			long expectedMaximumBalance = deployersInitialBalance - deployAtFee - messageFee;
+
+			long actualBalance = deployer.getConfirmedBalance(Asset.QORT);
+
+			assertTrue(String.format("Deployer's balance %s should be above minimum %s", actualBalance, expectedMinimumBalance), actualBalance > expectedMinimumBalance);
+			assertTrue(String.format("Deployer's balance %s should be below maximum %s", actualBalance, expectedMaximumBalance), actualBalance < expectedMaximumBalance);
+
+			// Test orphaning
+			BlockUtils.orphanLastBlock(repository);
+
+			// Check balances
+			long expectedBalance = deployersPostDeploymentBalance - messageFee;
+			actualBalance = deployer.getConfirmedBalance(Asset.QORT);
+
+			assertEquals("Deployer's post-orphan/pre-refund balance incorrect", expectedBalance, actualBalance);
+		}
+	}
+
+	@SuppressWarnings("unused")
+	@Test
+	public void testOfferCancelInvalidLength() throws DataException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PrivateKeyAccount deployer = Common.getTestAccount(repository, "chloe");
+			PrivateKeyAccount tradeAccount = createTradeAccount(repository);
+
+			PrivateKeyAccount partner = Common.getTestAccount(repository, "dilbert");
+
+			long deployersInitialBalance = deployer.getConfirmedBalance(Asset.QORT);
+			long partnersInitialBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			DeployAtTransaction deployAtTransaction = doDeploy(repository, deployer, tradeAccount.getAddress());
+			Account at = deployAtTransaction.getATAccount();
+			String atAddress = at.getAddress();
+
+			long deployAtFee = deployAtTransaction.getTransactionData().getFee();
+			long deployersPostDeploymentBalance = deployersInitialBalance - fundingAmount - deployAtFee;
+
+			// Instead of sending creator's address to AT, send too-short/invalid message
+			byte[] messageData = new byte[7];
+			RANDOM.nextBytes(messageData);
+			MessageTransaction messageTransaction = sendMessage(repository, deployer, messageData, atAddress);
+			long messageFee = messageTransaction.getTransactionData().getFee();
+
+			// AT should process 'cancel' message in next block
+			// As message is too short, it will be padded to 32bytes but cancel code doesn't care about message content, so should be ok
+			BlockUtils.mintBlock(repository);
+
+			describeAt(repository, atAddress);
+
+			// Check AT is finished
+			ATData atData = repository.getATRepository().fromATAddress(atAddress);
+			assertTrue(atData.getIsFinished());
+
+			// AT should be in CANCELLED mode
+			CrossChainTradeData tradeData = BitcoinACCTv3.getInstance().populateTradeData(repository, atData);
+			assertEquals(AcctMode.CANCELLED, tradeData.mode);
+		}
+	}
+
+	@SuppressWarnings("unused")
+	@Test
+	public void testTradingInfoProcessing() throws DataException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PrivateKeyAccount deployer = Common.getTestAccount(repository, "chloe");
+			PrivateKeyAccount tradeAccount = createTradeAccount(repository);
+
+			PrivateKeyAccount partner = Common.getTestAccount(repository, "dilbert");
+
+			long deployersInitialBalance = deployer.getConfirmedBalance(Asset.QORT);
+			long partnersInitialBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			DeployAtTransaction deployAtTransaction = doDeploy(repository, deployer, tradeAccount.getAddress());
+			Account at = deployAtTransaction.getATAccount();
+			String atAddress = at.getAddress();
+
+			long partnersOfferMessageTransactionTimestamp = System.currentTimeMillis();
+			int lockTimeA = calcTestLockTimeA(partnersOfferMessageTransactionTimestamp);
+			int refundTimeout = BitcoinACCTv3.calcRefundTimeout(partnersOfferMessageTransactionTimestamp, lockTimeA);
+
+			// Send trade info to AT
+			byte[] messageData = BitcoinACCTv3.buildTradeMessage(partner.getAddress(), bitcoinPublicKeyHash, hashOfSecretA, lockTimeA, refundTimeout);
+			MessageTransaction messageTransaction = sendMessage(repository, tradeAccount, messageData, atAddress);
+
+			Block postDeploymentBlock = BlockUtils.mintBlock(repository);
+			int postDeploymentBlockHeight = postDeploymentBlock.getBlockData().getHeight();
+
+			long deployAtFee = deployAtTransaction.getTransactionData().getFee();
+			long deployersPostDeploymentBalance = deployersInitialBalance - fundingAmount - deployAtFee;
+
+			describeAt(repository, atAddress);
+
+			ATData atData = repository.getATRepository().fromATAddress(atAddress);
+			CrossChainTradeData tradeData = BitcoinACCTv3.getInstance().populateTradeData(repository, atData);
+
+			// AT should be in TRADE mode
+			assertEquals(AcctMode.TRADING, tradeData.mode);
+
+			// Check hashOfSecretA was extracted correctly
+			assertTrue(Arrays.equals(hashOfSecretA, tradeData.hashOfSecretA));
+
+			// Check trade partner Qortal address was extracted correctly
+			assertEquals(partner.getAddress(), tradeData.qortalPartnerAddress);
+
+			// Check trade partner's Bitcoin PKH was extracted correctly
+			assertTrue(Arrays.equals(bitcoinPublicKeyHash, tradeData.partnerForeignPKH));
+
+			// Test orphaning
+			BlockUtils.orphanToBlock(repository, postDeploymentBlockHeight);
+
+			// Check balances
+			long expectedBalance = deployersPostDeploymentBalance;
+			long actualBalance = deployer.getConfirmedBalance(Asset.QORT);
+
+			assertEquals("Deployer's post-orphan/pre-refund balance incorrect", expectedBalance, actualBalance);
+		}
+	}
+
+	// TEST SENDING TRADING INFO BUT NOT FROM AT CREATOR (SHOULD BE IGNORED)
+	@SuppressWarnings("unused")
+	@Test
+	public void testIncorrectTradeSender() throws DataException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PrivateKeyAccount deployer = Common.getTestAccount(repository, "chloe");
+			PrivateKeyAccount tradeAccount = createTradeAccount(repository);
+
+			PrivateKeyAccount partner = Common.getTestAccount(repository, "dilbert");
+
+			PrivateKeyAccount bystander = Common.getTestAccount(repository, "bob");
+
+			long deployersInitialBalance = deployer.getConfirmedBalance(Asset.QORT);
+			long partnersInitialBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			DeployAtTransaction deployAtTransaction = doDeploy(repository, deployer, tradeAccount.getAddress());
+			Account at = deployAtTransaction.getATAccount();
+			String atAddress = at.getAddress();
+
+			long partnersOfferMessageTransactionTimestamp = System.currentTimeMillis();
+			int lockTimeA = calcTestLockTimeA(partnersOfferMessageTransactionTimestamp);
+			int refundTimeout = BitcoinACCTv3.calcRefundTimeout(partnersOfferMessageTransactionTimestamp, lockTimeA);
+
+			// Send trade info to AT BUT NOT FROM AT CREATOR
+			byte[] messageData = BitcoinACCTv3.buildTradeMessage(partner.getAddress(), bitcoinPublicKeyHash, hashOfSecretA, lockTimeA, refundTimeout);
+			MessageTransaction messageTransaction = sendMessage(repository, bystander, messageData, atAddress);
+
+			BlockUtils.mintBlock(repository);
+
+			long expectedBalance = partnersInitialBalance;
+			long actualBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			assertEquals("Partner's post-initial-payout balance incorrect", expectedBalance, actualBalance);
+
+			describeAt(repository, atAddress);
+
+			ATData atData = repository.getATRepository().fromATAddress(atAddress);
+			CrossChainTradeData tradeData = BitcoinACCTv3.getInstance().populateTradeData(repository, atData);
+
+			// AT should still be in OFFER mode
+			assertEquals(AcctMode.OFFERING, tradeData.mode);
+		}
+	}
+
+	@SuppressWarnings("unused")
+	@Test
+	public void testAutomaticTradeRefund() throws DataException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PrivateKeyAccount deployer = Common.getTestAccount(repository, "chloe");
+			PrivateKeyAccount tradeAccount = createTradeAccount(repository);
+
+			PrivateKeyAccount partner = Common.getTestAccount(repository, "dilbert");
+
+			long deployersInitialBalance = deployer.getConfirmedBalance(Asset.QORT);
+			long partnersInitialBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			DeployAtTransaction deployAtTransaction = doDeploy(repository, deployer, tradeAccount.getAddress());
+			Account at = deployAtTransaction.getATAccount();
+			String atAddress = at.getAddress();
+
+			long partnersOfferMessageTransactionTimestamp = System.currentTimeMillis();
+			int lockTimeA = calcTestLockTimeA(partnersOfferMessageTransactionTimestamp);
+			int refundTimeout = BitcoinACCTv3.calcRefundTimeout(partnersOfferMessageTransactionTimestamp, lockTimeA);
+
+			// Send trade info to AT
+			byte[] messageData = BitcoinACCTv3.buildTradeMessage(partner.getAddress(), bitcoinPublicKeyHash, hashOfSecretA, lockTimeA, refundTimeout);
+			MessageTransaction messageTransaction = sendMessage(repository, tradeAccount, messageData, atAddress);
+
+			Block postDeploymentBlock = BlockUtils.mintBlock(repository);
+			int postDeploymentBlockHeight = postDeploymentBlock.getBlockData().getHeight();
+
+			// Check refund
+			long deployAtFee = deployAtTransaction.getTransactionData().getFee();
+			long deployersPostDeploymentBalance = deployersInitialBalance - fundingAmount - deployAtFee;
+
+			checkTradeRefund(repository, deployer, deployersInitialBalance, deployAtFee);
+
+			describeAt(repository, atAddress);
+
+			// Check AT is finished
+			ATData atData = repository.getATRepository().fromATAddress(atAddress);
+			assertTrue(atData.getIsFinished());
+
+			// AT should be in REFUNDED mode
+			CrossChainTradeData tradeData = BitcoinACCTv3.getInstance().populateTradeData(repository, atData);
+			assertEquals(AcctMode.REFUNDED, tradeData.mode);
+
+			// Test orphaning
+			BlockUtils.orphanToBlock(repository, postDeploymentBlockHeight);
+
+			// Check balances
+			long expectedBalance = deployersPostDeploymentBalance;
+			long actualBalance = deployer.getConfirmedBalance(Asset.QORT);
+
+			assertEquals("Deployer's post-orphan/pre-refund balance incorrect", expectedBalance, actualBalance);
+		}
+	}
+
+	@SuppressWarnings("unused")
+	@Test
+	public void testCorrectSecretCorrectSender() throws DataException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PrivateKeyAccount deployer = Common.getTestAccount(repository, "chloe");
+			PrivateKeyAccount tradeAccount = createTradeAccount(repository);
+
+			PrivateKeyAccount partner = Common.getTestAccount(repository, "dilbert");
+
+			long deployersInitialBalance = deployer.getConfirmedBalance(Asset.QORT);
+			long partnersInitialBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			DeployAtTransaction deployAtTransaction = doDeploy(repository, deployer, tradeAccount.getAddress());
+			Account at = deployAtTransaction.getATAccount();
+			String atAddress = at.getAddress();
+
+			long partnersOfferMessageTransactionTimestamp = System.currentTimeMillis();
+			int lockTimeA = calcTestLockTimeA(partnersOfferMessageTransactionTimestamp);
+			int refundTimeout = BitcoinACCTv3.calcRefundTimeout(partnersOfferMessageTransactionTimestamp, lockTimeA);
+
+			// Send trade info to AT
+			byte[] messageData = BitcoinACCTv3.buildTradeMessage(partner.getAddress(), bitcoinPublicKeyHash, hashOfSecretA, lockTimeA, refundTimeout);
+			MessageTransaction messageTransaction = sendMessage(repository, tradeAccount, messageData, atAddress);
+
+			// Give AT time to process message
+			BlockUtils.mintBlock(repository);
+
+			// Send correct secret to AT, from correct account
+			messageData = BitcoinACCTv3.buildRedeemMessage(secretA,  partner.getAddress());
+			messageTransaction = sendMessage(repository, partner, messageData, atAddress);
+
+			// AT should send funds in the next block
+			ATStateData preRedeemAtStateData = repository.getATRepository().getLatestATState(atAddress);
+			BlockUtils.mintBlock(repository);
+
+			describeAt(repository, atAddress);
+
+			// Check AT is finished
+			ATData atData = repository.getATRepository().fromATAddress(atAddress);
+			assertTrue(atData.getIsFinished());
+
+			// AT should be in REDEEMED mode
+			CrossChainTradeData tradeData = BitcoinACCTv3.getInstance().populateTradeData(repository, atData);
+			assertEquals(AcctMode.REDEEMED, tradeData.mode);
+
+			// Check balances
+			long expectedBalance = partnersInitialBalance - messageTransaction.getTransactionData().getFee() + redeemAmount;
+			long actualBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			assertEquals("Partner's post-redeem balance incorrect", expectedBalance, actualBalance);
+
+			// Orphan redeem
+			BlockUtils.orphanLastBlock(repository);
+
+			// Check balances
+			expectedBalance = partnersInitialBalance - messageTransaction.getTransactionData().getFee();
+			actualBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			assertEquals("Partner's post-orphan/pre-redeem balance incorrect", expectedBalance, actualBalance);
+
+			// Check AT state
+			ATStateData postOrphanAtStateData = repository.getATRepository().getLatestATState(atAddress);
+
+			assertTrue("AT states mismatch", Arrays.equals(preRedeemAtStateData.getStateData(), postOrphanAtStateData.getStateData()));
+		}
+	}
+
+	@SuppressWarnings("unused")
+	@Test
+	public void testCorrectSecretIncorrectSender() throws DataException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PrivateKeyAccount deployer = Common.getTestAccount(repository, "chloe");
+			PrivateKeyAccount tradeAccount = createTradeAccount(repository);
+
+			PrivateKeyAccount partner = Common.getTestAccount(repository, "dilbert");
+
+			PrivateKeyAccount bystander = Common.getTestAccount(repository, "bob");
+
+			long deployersInitialBalance = deployer.getConfirmedBalance(Asset.QORT);
+			long partnersInitialBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			DeployAtTransaction deployAtTransaction = doDeploy(repository, deployer, tradeAccount.getAddress());
+			long deployAtFee = deployAtTransaction.getTransactionData().getFee();
+
+			Account at = deployAtTransaction.getATAccount();
+			String atAddress = at.getAddress();
+
+			long partnersOfferMessageTransactionTimestamp = System.currentTimeMillis();
+			int lockTimeA = calcTestLockTimeA(partnersOfferMessageTransactionTimestamp);
+			int refundTimeout = BitcoinACCTv3.calcRefundTimeout(partnersOfferMessageTransactionTimestamp, lockTimeA);
+
+			// Send trade info to AT
+			byte[] messageData = BitcoinACCTv3.buildTradeMessage(partner.getAddress(), bitcoinPublicKeyHash, hashOfSecretA, lockTimeA, refundTimeout);
+			MessageTransaction messageTransaction = sendMessage(repository, tradeAccount, messageData, atAddress);
+
+			// Give AT time to process message
+			BlockUtils.mintBlock(repository);
+
+			// Send correct secret to AT, but from wrong account
+			messageData = BitcoinACCTv3.buildRedeemMessage(secretA, partner.getAddress());
+			messageTransaction = sendMessage(repository, bystander, messageData, atAddress);
+
+			// AT should NOT send funds in the next block
+			ATStateData preRedeemAtStateData = repository.getATRepository().getLatestATState(atAddress);
+			BlockUtils.mintBlock(repository);
+
+			describeAt(repository, atAddress);
+
+			// Check AT is NOT finished
+			ATData atData = repository.getATRepository().fromATAddress(atAddress);
+			assertFalse(atData.getIsFinished());
+
+			// AT should still be in TRADE mode
+			CrossChainTradeData tradeData = BitcoinACCTv3.getInstance().populateTradeData(repository, atData);
+			assertEquals(AcctMode.TRADING, tradeData.mode);
+
+			// Check balances
+			long expectedBalance = partnersInitialBalance;
+			long actualBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			assertEquals("Partner's balance incorrect", expectedBalance, actualBalance);
+
+			// Check eventual refund
+			checkTradeRefund(repository, deployer, deployersInitialBalance, deployAtFee);
+		}
+	}
+
+	@SuppressWarnings("unused")
+	@Test
+	public void testIncorrectSecretCorrectSender() throws DataException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PrivateKeyAccount deployer = Common.getTestAccount(repository, "chloe");
+			PrivateKeyAccount tradeAccount = createTradeAccount(repository);
+
+			PrivateKeyAccount partner = Common.getTestAccount(repository, "dilbert");
+
+			long deployersInitialBalance = deployer.getConfirmedBalance(Asset.QORT);
+			long partnersInitialBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			DeployAtTransaction deployAtTransaction = doDeploy(repository, deployer, tradeAccount.getAddress());
+			long deployAtFee = deployAtTransaction.getTransactionData().getFee();
+
+			Account at = deployAtTransaction.getATAccount();
+			String atAddress = at.getAddress();
+
+			long partnersOfferMessageTransactionTimestamp = System.currentTimeMillis();
+			int lockTimeA = calcTestLockTimeA(partnersOfferMessageTransactionTimestamp);
+			int refundTimeout = BitcoinACCTv3.calcRefundTimeout(partnersOfferMessageTransactionTimestamp, lockTimeA);
+
+			// Send trade info to AT
+			byte[] messageData = BitcoinACCTv3.buildTradeMessage(partner.getAddress(), bitcoinPublicKeyHash, hashOfSecretA, lockTimeA, refundTimeout);
+			MessageTransaction messageTransaction = sendMessage(repository, tradeAccount, messageData, atAddress);
+
+			// Give AT time to process message
+			BlockUtils.mintBlock(repository);
+
+			// Send incorrect secret to AT, from correct account
+			byte[] wrongSecret = new byte[32];
+			RANDOM.nextBytes(wrongSecret);
+			messageData = BitcoinACCTv3.buildRedeemMessage(wrongSecret, partner.getAddress());
+			messageTransaction = sendMessage(repository, partner, messageData, atAddress);
+
+			// AT should NOT send funds in the next block
+			ATStateData preRedeemAtStateData = repository.getATRepository().getLatestATState(atAddress);
+			BlockUtils.mintBlock(repository);
+
+			describeAt(repository, atAddress);
+
+			// Check AT is NOT finished
+			ATData atData = repository.getATRepository().fromATAddress(atAddress);
+			assertFalse(atData.getIsFinished());
+
+			// AT should still be in TRADE mode
+			CrossChainTradeData tradeData = BitcoinACCTv3.getInstance().populateTradeData(repository, atData);
+			assertEquals(AcctMode.TRADING, tradeData.mode);
+
+			long expectedBalance = partnersInitialBalance - messageTransaction.getTransactionData().getFee();
+			long actualBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			assertEquals("Partner's balance incorrect", expectedBalance, actualBalance);
+
+			// Check eventual refund
+			checkTradeRefund(repository, deployer, deployersInitialBalance, deployAtFee);
+		}
+	}
+
+	@SuppressWarnings("unused")
+	@Test
+	public void testCorrectSecretCorrectSenderInvalidMessageLength() throws DataException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PrivateKeyAccount deployer = Common.getTestAccount(repository, "chloe");
+			PrivateKeyAccount tradeAccount = createTradeAccount(repository);
+
+			PrivateKeyAccount partner = Common.getTestAccount(repository, "dilbert");
+
+			long deployersInitialBalance = deployer.getConfirmedBalance(Asset.QORT);
+			long partnersInitialBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			DeployAtTransaction deployAtTransaction = doDeploy(repository, deployer, tradeAccount.getAddress());
+			Account at = deployAtTransaction.getATAccount();
+			String atAddress = at.getAddress();
+
+			long partnersOfferMessageTransactionTimestamp = System.currentTimeMillis();
+			int lockTimeA = calcTestLockTimeA(partnersOfferMessageTransactionTimestamp);
+			int refundTimeout = BitcoinACCTv3.calcRefundTimeout(partnersOfferMessageTransactionTimestamp, lockTimeA);
+
+			// Send trade info to AT
+			byte[] messageData = BitcoinACCTv3.buildTradeMessage(partner.getAddress(), bitcoinPublicKeyHash, hashOfSecretA, lockTimeA, refundTimeout);
+			MessageTransaction messageTransaction = sendMessage(repository, tradeAccount, messageData, atAddress);
+
+			// Give AT time to process message
+			BlockUtils.mintBlock(repository);
+
+			// Send correct secret to AT, from correct account, but missing receive address, hence incorrect length
+			messageData = Bytes.concat(secretA);
+			messageTransaction = sendMessage(repository, partner, messageData, atAddress);
+
+			// AT should NOT send funds in the next block
+			ATStateData preRedeemAtStateData = repository.getATRepository().getLatestATState(atAddress);
+			BlockUtils.mintBlock(repository);
+
+			describeAt(repository, atAddress);
+
+			// Check AT is NOT finished
+			ATData atData = repository.getATRepository().fromATAddress(atAddress);
+			assertFalse(atData.getIsFinished());
+
+			// AT should be in TRADING mode
+			CrossChainTradeData tradeData = BitcoinACCTv3.getInstance().populateTradeData(repository, atData);
+			assertEquals(AcctMode.TRADING, tradeData.mode);
+		}
+	}
+
+	@SuppressWarnings("unused")
+	@Test
+	public void testDescribeDeployed() throws DataException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PrivateKeyAccount deployer = Common.getTestAccount(repository, "chloe");
+			PrivateKeyAccount tradeAccount = createTradeAccount(repository);
+
+			PrivateKeyAccount partner = Common.getTestAccount(repository, "dilbert");
+
+			long deployersInitialBalance = deployer.getConfirmedBalance(Asset.QORT);
+			long partnersInitialBalance = partner.getConfirmedBalance(Asset.QORT);
+
+			DeployAtTransaction deployAtTransaction = doDeploy(repository, deployer, tradeAccount.getAddress());
+
+			List<ATData> executableAts = repository.getATRepository().getAllExecutableATs();
+
+			for (ATData atData : executableAts) {
+				String atAddress = atData.getATAddress();
+				byte[] codeBytes = atData.getCodeBytes();
+				byte[] codeHash = Crypto.digest(codeBytes);
+
+				System.out.println(String.format("%s: code length: %d byte%s, code hash: %s",
+						atAddress,
+						codeBytes.length,
+						(codeBytes.length != 1 ? "s": ""),
+						HashCode.fromBytes(codeHash)));
+
+				// Not one of ours?
+				if (!Arrays.equals(codeHash, BitcoinACCTv3.CODE_BYTES_HASH))
+					continue;
+
+				describeAt(repository, atAddress);
+			}
+		}
+	}
+
+	private int calcTestLockTimeA(long messageTimestamp) {
+		return (int) (messageTimestamp / 1000L + tradeTimeout * 60);
+	}
+
+	private DeployAtTransaction doDeploy(Repository repository, PrivateKeyAccount deployer, String tradeAddress) throws DataException {
+		byte[] creationBytes = BitcoinACCTv3.buildQortalAT(tradeAddress, bitcoinPublicKeyHash, redeemAmount, bitcoinAmount, tradeTimeout);
+
+		long txTimestamp = System.currentTimeMillis();
+		byte[] lastReference = deployer.getLastReference();
+
+		if (lastReference == null) {
+			System.err.println(String.format("Qortal account %s has no last reference", deployer.getAddress()));
+			System.exit(2);
+		}
+
+		Long fee = null;
+		String name = "QORT-BTC cross-chain trade";
+		String description = String.format("Qortal-Bitcoin cross-chain trade");
+		String atType = "ACCT";
+		String tags = "QORT-BTC ACCT";
+
+		BaseTransactionData baseTransactionData = new BaseTransactionData(txTimestamp, Group.NO_GROUP, lastReference, deployer.getPublicKey(), fee, null);
+		TransactionData deployAtTransactionData = new DeployAtTransactionData(baseTransactionData, name, description, atType, tags, creationBytes, fundingAmount, Asset.QORT);
+
+		DeployAtTransaction deployAtTransaction = new DeployAtTransaction(repository, deployAtTransactionData);
+
+		fee = deployAtTransaction.calcRecommendedFee();
+		deployAtTransactionData.setFee(fee);
+
+		TransactionUtils.signAndMint(repository, deployAtTransactionData, deployer);
+
+		return deployAtTransaction;
+	}
+
+	private MessageTransaction sendMessage(Repository repository, PrivateKeyAccount sender, byte[] data, String recipient) throws DataException {
+		long txTimestamp = System.currentTimeMillis();
+		byte[] lastReference = sender.getLastReference();
+
+		if (lastReference == null) {
+			System.err.println(String.format("Qortal account %s has no last reference", sender.getAddress()));
+			System.exit(2);
+		}
+
+		Long fee = null;
+		int version = 4;
+		int nonce = 0;
+		long amount = 0;
+		Long assetId = null; // because amount is zero
+
+		BaseTransactionData baseTransactionData = new BaseTransactionData(txTimestamp, Group.NO_GROUP, lastReference, sender.getPublicKey(), fee, null);
+		TransactionData messageTransactionData = new MessageTransactionData(baseTransactionData, version, nonce, recipient, amount, assetId, data, false, false);
+
+		MessageTransaction messageTransaction = new MessageTransaction(repository, messageTransactionData);
+
+		fee = messageTransaction.calcRecommendedFee();
+		messageTransactionData.setFee(fee);
+
+		TransactionUtils.signAndMint(repository, messageTransactionData, sender);
+
+		return messageTransaction;
+	}
+
+	private void checkTradeRefund(Repository repository, Account deployer, long deployersInitialBalance, long deployAtFee) throws DataException {
+		long deployersPostDeploymentBalance = deployersInitialBalance - fundingAmount - deployAtFee;
+		int refundTimeout = tradeTimeout / 2 + 1; // close enough
+
+		// AT should automatically refund deployer after 'refundTimeout' blocks
+		for (int blockCount = 0; blockCount <= refundTimeout; ++blockCount)
+			BlockUtils.mintBlock(repository);
+
+		// We don't bother to exactly calculate QORT spent running AT for several blocks, but we do know the expected range
+		long expectedMinimumBalance = deployersPostDeploymentBalance;
+		long expectedMaximumBalance = deployersInitialBalance - deployAtFee;
+
+		long actualBalance = deployer.getConfirmedBalance(Asset.QORT);
+
+		assertTrue(String.format("Deployer's balance %s should be above minimum %s", actualBalance, expectedMinimumBalance), actualBalance > expectedMinimumBalance);
+		assertTrue(String.format("Deployer's balance %s should be below maximum %s", actualBalance, expectedMaximumBalance), actualBalance < expectedMaximumBalance);
+	}
+
+	private void describeAt(Repository repository, String atAddress) throws DataException {
+		ATData atData = repository.getATRepository().fromATAddress(atAddress);
+		CrossChainTradeData tradeData = BitcoinACCTv3.getInstance().populateTradeData(repository, atData);
+
+		Function<Long, String> epochMilliFormatter = (timestamp) -> LocalDateTime.ofInstant(Instant.ofEpochMilli(timestamp), ZoneOffset.UTC).format(DateTimeFormatter.ofLocalizedDateTime(FormatStyle.MEDIUM));
+		int currentBlockHeight = repository.getBlockRepository().getBlockchainHeight();
+
+		System.out.print(String.format("%s:\n"
+				+ "\tmode: %s\n"
+				+ "\tcreator: %s,\n"
+				+ "\tcreation timestamp: %s,\n"
+				+ "\tcurrent balance: %s QORT,\n"
+				+ "\tis finished: %b,\n"
+				+ "\tredeem payout: %s QORT,\n"
+				+ "\texpected Bitcoin: %s BTC,\n"
+				+ "\tcurrent block height: %d,\n",
+				tradeData.qortalAtAddress,
+				tradeData.mode,
+				tradeData.qortalCreator,
+				epochMilliFormatter.apply(tradeData.creationTimestamp),
+				Amounts.prettyAmount(tradeData.qortBalance),
+				atData.getIsFinished(),
+				Amounts.prettyAmount(tradeData.qortAmount),
+				Amounts.prettyAmount(tradeData.expectedForeignAmount),
+				currentBlockHeight));
+
+		if (tradeData.mode != AcctMode.OFFERING && tradeData.mode != AcctMode.CANCELLED) {
+			System.out.println(String.format("\trefund timeout: %d minutes,\n"
+					+ "\trefund height: block %d,\n"
+					+ "\tHASH160 of secret-A: %s,\n"
+					+ "\tBitcoin P2SH-A nLockTime: %d (%s),\n"
+					+ "\ttrade partner: %s\n"
+					+ "\tpartner's receiving address: %s",
+					tradeData.refundTimeout,
+					tradeData.tradeRefundHeight,
+					HashCode.fromBytes(tradeData.hashOfSecretA).toString().substring(0, 40),
+					tradeData.lockTimeA, epochMilliFormatter.apply(tradeData.lockTimeA * 1000L),
+					tradeData.qortalPartnerAddress,
+					tradeData.qortalPartnerReceivingAddress));
+		}
+	}
+
+	private PrivateKeyAccount createTradeAccount(Repository repository) {
+		// We actually use a known test account with funds to avoid PoW compute
+		return Common.getTestAccount(repository, "alice");
+	}
+
+}

src/test/resources/test-chain-v2-founder-rewards.json

@@ -52,7 +52,8 @@
 		"newBlockSigHeight": 999999,
 		"shareBinFix": 999999,
 		"calcChainWeightTimestamp": 0,
-		"transactionV5Timestamp": 0
+		"transactionV5Timestamp": 0,
+		"transactionV6Timestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2-leftover-reward.json

@@ -52,7 +52,8 @@
 		"newBlockSigHeight": 999999,
 		"shareBinFix": 999999,
 		"calcChainWeightTimestamp": 0,
-		"transactionV5Timestamp": 0
+		"transactionV5Timestamp": 0,
+		"transactionV6Timestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2-minting.json

@@ -52,7 +52,8 @@
 		"newBlockSigHeight": 999999,
 		"shareBinFix": 999999,
 		"calcChainWeightTimestamp": 0,
-		"transactionV5Timestamp": 0
+		"transactionV5Timestamp": 0,
+		"transactionV6Timestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2-qora-holder-extremes.json

@@ -52,7 +52,8 @@
 		"newBlockSigHeight": 999999,
 		"shareBinFix": 999999,
 		"calcChainWeightTimestamp": 0,
-		"transactionV5Timestamp": 0
+		"transactionV5Timestamp": 0,
+		"transactionV6Timestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2-qora-holder.json

@@ -52,7 +52,8 @@
 		"newBlockSigHeight": 999999,
 		"shareBinFix": 999999,
 		"calcChainWeightTimestamp": 0,
-		"transactionV5Timestamp": 0
+		"transactionV5Timestamp": 0,
+		"transactionV6Timestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2-reward-levels.json

@@ -52,7 +52,8 @@
 		"newBlockSigHeight": 999999,
 		"shareBinFix": 6,
 		"calcChainWeightTimestamp": 0,
-		"transactionV5Timestamp": 0
+		"transactionV5Timestamp": 0,
+		"transactionV6Timestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2-reward-scaling.json

@@ -52,7 +52,8 @@
 		"newBlockSigHeight": 999999,
 		"shareBinFix": 999999,
 		"calcChainWeightTimestamp": 0,
-		"transactionV5Timestamp": 0
+		"transactionV5Timestamp": 0,
+		"transactionV6Timestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2.json

@@ -52,7 +52,8 @@
 		"newBlockSigHeight": 999999,
 		"shareBinFix": 999999,
 		"calcChainWeightTimestamp": 0,
-		"transactionV5Timestamp": 0
+		"transactionV5Timestamp": 0,
+		"transactionV6Timestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,