WIP: refactoring to support multiple foreign blockchains

API support for Litecoin wallet balance and sending LTC.

TradeBotCreateRequest rejigged to use blockchain-agnostic
field names, e.g. bitcoinAmount now foreignAmount,
and added foreignBlockchain field.

The massive API CrossChainResource class has been split into:

CrossChainAtResource: for building TRADE/REDEEM/CANCEL messages
(OFFER missing?)

CrossChainBitcoinResource: for Bitcoin wallet balance/spend
CrossChainLitecoinResource: ditto for Litecoin

CrossChainHtlcResource: for Bitcoiny-HTLC actions like:
deriving P2SH address
checking HTLC status
eventually: building refund/redeem transactions

CrossChainResource: for creating/cancelling/listing trade offers.

CrossChainTradeBotResource: for creating/cancelling trade-bot
entries, including responding to trade offers.

---

Other general trading changes:

TradeBot states are now specific to each individual trade-bot,
e.g. BitcoinACCTv1TradeBot or LitecoinACCTv1TradeBot, etc.

TradeBot states now a combination of int & String, instead of
enums due to above.

Extra columns added to DB TradeBotStates to store
blockchain, which ACCT in use, etc.

---

UNTESTED at this point!

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

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

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

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

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

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

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

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

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

@@ -1,4 +1,4 @@
-package org.qortal.api.model;
+package org.qortal.api.model.crosschain;
 
 import javax.xml.bind.annotation.XmlAccessType;
 import javax.xml.bind.annotation.XmlAccessorType;
@@ -11,9 +11,15 @@ public class TradeBotRespondRequest {
 	@Schema(description = "Qortal AT address", example = "Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
 	public String atAddress;
 
-	@Schema(description = "Bitcoin BIP32 extended private key", example = "xprv___________________________________________________________________________________________________________")
+	@Deprecated
+	@Schema(description = "Bitcoin BIP32 extended private key. DEPRECATED: use foreignKey instead",
+			example = "xprv___________________________________________________________________________________________________________")
 	public String xprv58;
 
+	@Schema(description = "Foreign blockchain private key, e.g. BIP32 'm' key for Bitcoin/Litecoin starting with 'xprv'",
+			example = "xprv___________________________________________________________________________________________________________")
+	public String foreignKey;
+
 	@Schema(description = "Qortal address for receiving QORT from AT", example = "Qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq")
 	public String receivingAddress;
 

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

@@ -0,0 +1,329 @@
+package org.qortal.api.resource;
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.parameters.RequestBody;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.tags.Tag;
+
+import java.util.Arrays;
+import java.util.Random;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+
+import org.qortal.api.ApiError;
+import org.qortal.api.ApiErrors;
+import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.Security;
+import org.qortal.api.model.CrossChainCancelRequest;
+import org.qortal.api.model.CrossChainSecretRequest;
+import org.qortal.api.model.CrossChainTradeRequest;
+import org.qortal.crosschain.BitcoinACCTv1;
+import org.qortal.crosschain.AcctMode;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.transaction.BaseTransactionData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.transaction.Transaction.TransactionType;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.Transformer;
+import org.qortal.transform.transaction.MessageTransactionTransformer;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+@Path("/crosschain/at")
+@Tag(name = "Cross-Chain (AT-related)")
+public class CrossChainAtResource {
+
+	@Context
+	HttpServletRequest request;
+
+	@POST
+	@Path("/trademessage")
+	@Operation(
+		summary = "Builds raw, unsigned 'trade' MESSAGE transaction that sends cross-chain trade recipient address, triggering 'trade' mode",
+		description = "Specify address of cross-chain AT that needs to be messaged, and signature of 'offer' MESSAGE from trade partner.<br>"
+			+ "AT needs to be in 'offer' mode. Messages sent to an AT in any other mode will be ignored, but still cost fees to send!<br>"
+			+ "You need to sign output with trade private key otherwise the MESSAGE transaction will be invalid.",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = CrossChainTradeRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(
+					schema = @Schema(
+						type = "string"
+					)
+				)
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.INVALID_CRITERIA, ApiError.REPOSITORY_ISSUE})
+	public String buildTradeMessage(CrossChainTradeRequest tradeRequest) {
+		Security.checkApiCallAllowed(request);
+
+		byte[] tradePublicKey = tradeRequest.tradePublicKey;
+
+		if (tradePublicKey == null || tradePublicKey.length != Transformer.PUBLIC_KEY_LENGTH)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+
+		if (tradeRequest.atAddress == null || !Crypto.isValidAtAddress(tradeRequest.atAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (tradeRequest.messageTransactionSignature == null || !Crypto.isValidAddress(tradeRequest.messageTransactionSignature))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			ATData atData = fetchAtDataWithChecking(repository, tradeRequest.atAddress);
+			CrossChainTradeData crossChainTradeData = BitcoinACCTv1.getInstance().populateTradeData(repository, atData);
+
+			if (crossChainTradeData.mode != AcctMode.OFFERING)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			// Does supplied public key match trade public key?
+			if (!Crypto.toAddress(tradePublicKey).equals(crossChainTradeData.qortalCreatorTradeAddress))
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+
+			TransactionData transactionData = repository.getTransactionRepository().fromSignature(tradeRequest.messageTransactionSignature);
+			if (transactionData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.TRANSACTION_UNKNOWN);
+
+			if (transactionData.getType() != TransactionType.MESSAGE)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.TRANSACTION_INVALID);
+
+			MessageTransactionData messageTransactionData = (MessageTransactionData) transactionData;
+			byte[] messageData = messageTransactionData.getData();
+			BitcoinACCTv1.OfferMessageData offerMessageData = BitcoinACCTv1.extractOfferMessageData(messageData);
+			if (offerMessageData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.TRANSACTION_INVALID);
+
+			// Good to make MESSAGE
+
+			byte[] aliceForeignPublicKeyHash = offerMessageData.partnerBitcoinPKH;
+			byte[] hashOfSecretA = offerMessageData.hashOfSecretA;
+			int lockTimeA = (int) offerMessageData.lockTimeA;
+
+			String aliceNativeAddress = Crypto.toAddress(messageTransactionData.getCreatorPublicKey());
+			int lockTimeB = BitcoinACCTv1.calcLockTimeB(messageTransactionData.getTimestamp(), lockTimeA);
+
+			byte[] outgoingMessageData = BitcoinACCTv1.buildTradeMessage(aliceNativeAddress, aliceForeignPublicKeyHash, hashOfSecretA, lockTimeA, lockTimeB);
+			byte[] messageTransactionBytes = buildAtMessage(repository, tradePublicKey, tradeRequest.atAddress, outgoingMessageData);
+
+			return Base58.encode(messageTransactionBytes);
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@POST
+	@Path("/redeemmessage")
+	@Operation(
+		summary = "Builds raw, unsigned 'redeem' MESSAGE transaction that sends secrets to AT, releasing funds to partner",
+		description = "Specify address of cross-chain AT that needs to be messaged, both 32-byte secrets and an address for receiving QORT from AT.<br>"
+			+ "AT needs to be in 'trade' mode. Messages sent to an AT in any other mode will be ignored, but still cost fees to send!<br>"
+			+ "You need to sign output with account the AT considers the trade 'partner' otherwise the MESSAGE transaction will be invalid.",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = CrossChainSecretRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(
+					schema = @Schema(
+						type = "string"
+					)
+				)
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.INVALID_DATA, ApiError.INVALID_CRITERIA, ApiError.REPOSITORY_ISSUE})
+	public String buildRedeemMessage(CrossChainSecretRequest secretRequest) {
+		Security.checkApiCallAllowed(request);
+
+		byte[] partnerPublicKey = secretRequest.partnerPublicKey;
+
+		if (partnerPublicKey == null || partnerPublicKey.length != Transformer.PUBLIC_KEY_LENGTH)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+
+		if (secretRequest.atAddress == null || !Crypto.isValidAtAddress(secretRequest.atAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (secretRequest.secretA == null || secretRequest.secretA.length != BitcoinACCTv1.SECRET_LENGTH)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		if (secretRequest.secretB == null || secretRequest.secretB.length != BitcoinACCTv1.SECRET_LENGTH)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		if (secretRequest.receivingAddress == null || !Crypto.isValidAddress(secretRequest.receivingAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			ATData atData = fetchAtDataWithChecking(repository, secretRequest.atAddress);
+			CrossChainTradeData crossChainTradeData = BitcoinACCTv1.getInstance().populateTradeData(repository, atData);
+
+			if (crossChainTradeData.mode != AcctMode.TRADING)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			String partnerAddress = Crypto.toAddress(partnerPublicKey);
+
+			// MESSAGE must come from address that AT considers trade partner
+			if (!crossChainTradeData.qortalPartnerAddress.equals(partnerAddress))
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+			// Good to make MESSAGE
+
+			byte[] messageData = BitcoinACCTv1.buildRedeemMessage(secretRequest.secretA, secretRequest.secretB, secretRequest.receivingAddress);
+			byte[] messageTransactionBytes = buildAtMessage(repository, partnerPublicKey, secretRequest.atAddress, messageData);
+
+			return Base58.encode(messageTransactionBytes);
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@POST
+	@Path("/cancelmessage")
+	@Operation(
+		summary = "Builds raw, unsigned 'cancel' MESSAGE transaction that cancels cross-chain trade offer",
+		description = "Specify address of cross-chain AT that needs to be cancelled.<br>"
+			+ "AT needs to be in 'offer' mode. Messages sent to an AT in 'trade' mode will be ignored, but still cost fees to send!<br>"
+			+ "You need to sign output with AT creator's private key otherwise the MESSAGE transaction will be invalid.",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = CrossChainCancelRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(
+					schema = @Schema(
+						type = "string"
+					)
+				)
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.INVALID_CRITERIA, ApiError.REPOSITORY_ISSUE})
+	public String buildCancelMessage(CrossChainCancelRequest cancelRequest) {
+		Security.checkApiCallAllowed(request);
+
+		byte[] creatorPublicKey = cancelRequest.creatorPublicKey;
+
+		if (creatorPublicKey == null || creatorPublicKey.length != Transformer.PUBLIC_KEY_LENGTH)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+
+		if (cancelRequest.atAddress == null || !Crypto.isValidAtAddress(cancelRequest.atAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			ATData atData = fetchAtDataWithChecking(repository, cancelRequest.atAddress);
+			CrossChainTradeData crossChainTradeData = BitcoinACCTv1.getInstance().populateTradeData(repository, atData);
+
+			if (crossChainTradeData.mode != AcctMode.OFFERING)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			// Does supplied public key match AT creator's public key?
+			if (!Arrays.equals(creatorPublicKey, atData.getCreatorPublicKey()))
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+
+			// Good to make MESSAGE
+
+			String atCreatorAddress = Crypto.toAddress(creatorPublicKey);
+			byte[] messageData = BitcoinACCTv1.buildCancelMessage(atCreatorAddress);
+
+			byte[] messageTransactionBytes = buildAtMessage(repository, creatorPublicKey, cancelRequest.atAddress, messageData);
+
+			return Base58.encode(messageTransactionBytes);
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	private ATData fetchAtDataWithChecking(Repository repository, String atAddress) throws DataException {
+		ATData atData = repository.getATRepository().fromATAddress(atAddress);
+		if (atData == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
+
+		// Must be correct AT - check functionality using code hash
+		if (!Arrays.equals(atData.getCodeHash(), BitcoinACCTv1.CODE_BYTES_HASH))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		// No point sending message to AT that's finished
+		if (atData.getIsFinished())
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		return atData;
+	}
+
+	private byte[] buildAtMessage(Repository repository, byte[] senderPublicKey, String atAddress, byte[] messageData) throws DataException {
+		long txTimestamp = NTP.getTime();
+
+		// senderPublicKey could be ephemeral trade public key where there is no corresponding account and hence no reference
+		String senderAddress = Crypto.toAddress(senderPublicKey);
+		byte[] lastReference = repository.getAccountRepository().getLastReference(senderAddress);
+		final boolean requiresPoW = lastReference == null;
+
+		if (requiresPoW) {
+			Random random = new Random();
+			lastReference = new byte[Transformer.SIGNATURE_LENGTH];
+			random.nextBytes(lastReference);
+		}
+
+		int version = 4;
+		int nonce = 0;
+		long amount = 0L;
+		Long assetId = null; // no assetId as amount is zero
+		Long fee = 0L;
+
+		BaseTransactionData baseTransactionData = new BaseTransactionData(txTimestamp, Group.NO_GROUP, lastReference, senderPublicKey, fee, null);
+		TransactionData messageTransactionData = new MessageTransactionData(baseTransactionData, version, nonce, atAddress, amount, assetId, messageData, false, false);
+
+		MessageTransaction messageTransaction = new MessageTransaction(repository, messageTransactionData);
+
+		if (requiresPoW) {
+			messageTransaction.computeNonce();
+		} else {
+			fee = messageTransaction.calcRecommendedFee();
+			messageTransactionData.setFee(fee);
+		}
+
+		ValidationResult result = messageTransaction.isValidUnconfirmed();
+		if (result != ValidationResult.OK)
+			throw TransactionsResource.createTransactionInvalidException(request, result);
+
+		try {
+			return MessageTransactionTransformer.toBytes(messageTransactionData);
+		} catch (TransformationException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.TRANSFORMATION_ERROR, e);
+		}
+	}
+
+}

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

@@ -0,0 +1,125 @@
+package org.qortal.api.resource;
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.parameters.RequestBody;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.tags.Tag;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+
+import org.bitcoinj.core.Transaction;
+import org.qortal.api.ApiError;
+import org.qortal.api.ApiErrors;
+import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.Security;
+import org.qortal.api.model.crosschain.BitcoinSendRequest;
+import org.qortal.crosschain.Bitcoin;
+import org.qortal.crosschain.ForeignBlockchainException;
+
+@Path("/crosschain/btc")
+@Tag(name = "Cross-Chain (Bitcoin)")
+public class CrossChainBitcoinResource {
+
+	@Context
+	HttpServletRequest request;
+
+	@POST
+	@Path("/walletbalance")
+	@Operation(
+		summary = "Returns BTC balance for hierarchical, deterministic BIP32 wallet",
+		description = "Supply BIP32 'm' private key in base58, starting with 'xprv' for mainnet, 'tprv' for testnet",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.TEXT_PLAIN,
+				schema = @Schema(
+					type = "string",
+					description = "BIP32 'm' private key in base58",
+					example = "tprv___________________________________________________________________________________________________________"
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string", description = "balance (satoshis)"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
+	public String getBitcoinWalletBalance(String xprv58) {
+		Security.checkApiCallAllowed(request);
+
+		Bitcoin bitcoin = Bitcoin.getInstance();
+
+		if (!bitcoin.isValidXprv(xprv58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		Long balance = bitcoin.getWalletBalance(xprv58);
+		if (balance == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+
+		return balance.toString();
+	}
+
+	@POST
+	@Path("/send")
+	@Operation(
+		summary = "Sends BTC from hierarchical, deterministic BIP32 wallet to specific address",
+		description = "Currently only supports 'legacy' P2PKH Bitcoin addresses. Supply BIP32 'm' private key in base58, starting with 'xprv' for mainnet, 'tprv' for testnet",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = BitcoinSendRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string", description = "transaction hash"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.INVALID_CRITERIA, ApiError.INVALID_ADDRESS, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
+	public String sendBitcoin(BitcoinSendRequest bitcoinSendRequest) {
+		Security.checkApiCallAllowed(request);
+
+		if (bitcoinSendRequest.bitcoinAmount <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		if (bitcoinSendRequest.feePerByte != null && bitcoinSendRequest.feePerByte <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		Bitcoin bitcoin = Bitcoin.getInstance();
+
+		if (!bitcoin.isValidAddress(bitcoinSendRequest.receivingAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (!bitcoin.isValidXprv(bitcoinSendRequest.xprv58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		Transaction spendTransaction = bitcoin.buildSpend(bitcoinSendRequest.xprv58,
+				bitcoinSendRequest.receivingAddress,
+				bitcoinSendRequest.bitcoinAmount,
+				bitcoinSendRequest.feePerByte);
+
+		if (spendTransaction == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE);
+
+		try {
+			bitcoin.broadcastTransaction(spendTransaction);
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+		}
+
+		return spendTransaction.getTxId().toString();
+	}
+
+}

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

@@ -0,0 +1,176 @@
+package org.qortal.api.resource;
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.tags.Tag;
+
+import java.math.BigDecimal;
+import java.util.List;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.GET;
+import javax.ws.rs.Path;
+import javax.ws.rs.PathParam;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+
+import org.bitcoinj.core.TransactionOutput;
+import org.qortal.api.ApiError;
+import org.qortal.api.ApiErrors;
+import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.Security;
+import org.qortal.api.model.CrossChainBitcoinyHTLCStatus;
+import org.qortal.crosschain.Bitcoiny;
+import org.qortal.crosschain.ForeignBlockchainException;
+import org.qortal.crosschain.SupportedBlockchain;
+import org.qortal.crosschain.BitcoinyHTLC;
+import org.qortal.utils.NTP;
+
+import com.google.common.hash.HashCode;
+
+@Path("/crosschain/htlc")
+@Tag(name = "Cross-Chain (Hash time-locked contracts)")
+public class CrossChainHtlcResource {
+
+	@Context
+	HttpServletRequest request;
+
+	@GET
+	@Path("/address/{blockchain}/{refundPKH}/{locktime}/{redeemPKH}/{hashOfSecret}")
+	@Operation(
+		summary = "Returns HTLC address based on trade info",
+		description = "Blockchain can be BITCOIN or LITECOIN. Public key hashes (PKH) and hash of secret should be 20 bytes (hex). Locktime is seconds since epoch.",
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_CRITERIA})
+	public String deriveHtlcAddress(@PathParam("blockchain") String blockchainName,
+			@PathParam("refundPKH") String refundHex,
+			@PathParam("locktime") int lockTime,
+			@PathParam("redeemPKH") String redeemHex,
+			@PathParam("hashOfSecret") String hashOfSecretHex) {
+		SupportedBlockchain blockchain = SupportedBlockchain.valueOf(blockchainName);
+		if (blockchain == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		byte[] refunderPubKeyHash;
+		byte[] redeemerPubKeyHash;
+		byte[] hashOfSecret;
+
+		try {
+			refunderPubKeyHash = HashCode.fromString(refundHex).asBytes();
+			redeemerPubKeyHash = HashCode.fromString(redeemHex).asBytes();
+
+			if (refunderPubKeyHash.length != 20 || redeemerPubKeyHash.length != 20)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+		} catch (IllegalArgumentException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+		}
+
+		try {
+			hashOfSecret = HashCode.fromString(hashOfSecretHex).asBytes();
+			if (hashOfSecret.length != 20)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+		} catch (IllegalArgumentException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+		}
+
+		byte[] redeemScript = BitcoinyHTLC.buildScript(refunderPubKeyHash, lockTime, redeemerPubKeyHash, hashOfSecret);
+
+		Bitcoiny bitcoiny = (Bitcoiny) blockchain.getInstance();
+
+		return bitcoiny.deriveP2shAddress(redeemScript);
+	}
+
+	@GET
+	@Path("/status/{blockchain}/{refundPKH}/{locktime}/{redeemPKH}/{hashOfSecret}")
+	@Operation(
+		summary = "Checks HTLC status",
+		description = "Blockchain can be BITCOIN or LITECOIN. Public key hashes (PKH) and hash of secret should be 20 bytes (hex). Locktime is seconds since epoch.",
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.APPLICATION_JSON, schema = @Schema(implementation = CrossChainBitcoinyHTLCStatus.class))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_CRITERIA, ApiError.INVALID_ADDRESS, ApiError.ADDRESS_UNKNOWN})
+	public CrossChainBitcoinyHTLCStatus checkHtlcStatus(@PathParam("blockchain") String blockchainName,
+			@PathParam("refundPKH") String refundHex,
+			@PathParam("locktime") int lockTime,
+			@PathParam("redeemPKH") String redeemHex,
+			@PathParam("hashOfSecret") String hashOfSecretHex) {
+		Security.checkApiCallAllowed(request);
+
+		SupportedBlockchain blockchain = SupportedBlockchain.valueOf(blockchainName);
+		if (blockchain == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		byte[] refunderPubKeyHash;
+		byte[] redeemerPubKeyHash;
+		byte[] hashOfSecret;
+
+		try {
+			refunderPubKeyHash = HashCode.fromString(refundHex).asBytes();
+			redeemerPubKeyHash = HashCode.fromString(redeemHex).asBytes();
+
+			if (refunderPubKeyHash.length != 20 || redeemerPubKeyHash.length != 20)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+		} catch (IllegalArgumentException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+		}
+
+		try {
+			hashOfSecret = HashCode.fromString(hashOfSecretHex).asBytes();
+			if (hashOfSecret.length != 20)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+		} catch (IllegalArgumentException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+		}
+
+		byte[] redeemScript = BitcoinyHTLC.buildScript(refunderPubKeyHash, lockTime, redeemerPubKeyHash, hashOfSecret);
+
+		Bitcoiny bitcoiny = (Bitcoiny) blockchain.getInstance();
+
+		String p2shAddress = bitcoiny.deriveP2shAddress(redeemScript);
+
+		long now = NTP.getTime();
+
+		try {
+			int medianBlockTime = bitcoiny.getMedianBlockTime();
+
+			// Check P2SH is funded
+			long p2shBalance = bitcoiny.getConfirmedBalance(p2shAddress.toString());
+
+			CrossChainBitcoinyHTLCStatus htlcStatus = new CrossChainBitcoinyHTLCStatus();
+			htlcStatus.bitcoinP2shAddress = p2shAddress;
+			htlcStatus.bitcoinP2shBalance = BigDecimal.valueOf(p2shBalance, 8);
+
+			List<TransactionOutput> fundingOutputs = bitcoiny.getUnspentOutputs(p2shAddress.toString());
+
+			if (p2shBalance > 0L && !fundingOutputs.isEmpty()) {
+				htlcStatus.canRedeem = now >= medianBlockTime * 1000L;
+				htlcStatus.canRefund = now >= lockTime * 1000L;
+			}
+
+			if (now >= medianBlockTime * 1000L) {
+				// See if we can extract secret
+				List<byte[]> rawTransactions = bitcoiny.getAddressTransactions(htlcStatus.bitcoinP2shAddress);
+				htlcStatus.secret = BitcoinyHTLC.findHtlcSecret(bitcoiny.getNetworkParameters(), htlcStatus.bitcoinP2shAddress, rawTransactions);
+			}
+
+			return htlcStatus;
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+		}
+	}
+
+	// TODO: refund
+
+	// TODO: redeem
+
+}

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

@@ -0,0 +1,125 @@
+package org.qortal.api.resource;
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.parameters.RequestBody;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.tags.Tag;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+
+import org.bitcoinj.core.Transaction;
+import org.qortal.api.ApiError;
+import org.qortal.api.ApiErrors;
+import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.Security;
+import org.qortal.api.model.crosschain.LitecoinSendRequest;
+import org.qortal.crosschain.ForeignBlockchainException;
+import org.qortal.crosschain.Litecoin;
+
+@Path("/crosschain/ltc")
+@Tag(name = "Cross-Chain (Bitcoin)")
+public class CrossChainLitecoinResource {
+
+	@Context
+	HttpServletRequest request;
+
+	@POST
+	@Path("/walletbalance")
+	@Operation(
+		summary = "Returns LTC balance for hierarchical, deterministic BIP32 wallet",
+		description = "Supply BIP32 'm' private key in base58, starting with 'xprv' for mainnet, 'tprv' for testnet",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.TEXT_PLAIN,
+				schema = @Schema(
+					type = "string",
+					description = "BIP32 'm' private key in base58",
+					example = "tprv___________________________________________________________________________________________________________"
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string", description = "balance (satoshis)"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
+	public String getLitecoinWalletBalance(String xprv58) {
+		Security.checkApiCallAllowed(request);
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		if (!litecoin.isValidXprv(xprv58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		Long balance = litecoin.getWalletBalance(xprv58);
+		if (balance == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+
+		return balance.toString();
+	}
+
+	@POST
+	@Path("/send")
+	@Operation(
+		summary = "Sends LTC from hierarchical, deterministic BIP32 wallet to specific address",
+		description = "Currently only supports 'legacy' P2PKH Litecoin addresses. Supply BIP32 'm' private key in base58, starting with 'xprv' for mainnet, 'tprv' for testnet",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = LitecoinSendRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string", description = "transaction hash"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.INVALID_CRITERIA, ApiError.INVALID_ADDRESS, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
+	public String sendBitcoin(LitecoinSendRequest litecoinSendRequest) {
+		Security.checkApiCallAllowed(request);
+
+		if (litecoinSendRequest.litecoinAmount <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		if (litecoinSendRequest.feePerByte != null && litecoinSendRequest.feePerByte <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		if (!litecoin.isValidAddress(litecoinSendRequest.receivingAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (!litecoin.isValidXprv(litecoinSendRequest.xprv58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		Transaction spendTransaction = litecoin.buildSpend(litecoinSendRequest.xprv58,
+				litecoinSendRequest.receivingAddress,
+				litecoinSendRequest.litecoinAmount,
+				litecoinSendRequest.feePerByte);
+
+		if (spendTransaction == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE);
+
+		try {
+			litecoin.broadcastTransaction(spendTransaction);
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+		}
+
+		return spendTransaction.getTxId().toString();
+	}
+
+}

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

@@ -0,0 +1,273 @@
+package org.qortal.api.resource;
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.ArraySchema;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.parameters.RequestBody;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.tags.Tag;
+
+import java.util.List;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.DELETE;
+import javax.ws.rs.GET;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+
+import org.qortal.account.Account;
+import org.qortal.account.PublicKeyAccount;
+import org.qortal.api.ApiError;
+import org.qortal.api.ApiErrors;
+import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.Security;
+import org.qortal.api.model.crosschain.TradeBotCreateRequest;
+import org.qortal.api.model.crosschain.TradeBotRespondRequest;
+import org.qortal.asset.Asset;
+import org.qortal.controller.tradebot.AcctTradeBot;
+import org.qortal.controller.tradebot.TradeBot;
+import org.qortal.crosschain.ForeignBlockchain;
+import org.qortal.crosschain.ACCT;
+import org.qortal.crosschain.AcctMode;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.utils.Base58;
+
+@Path("/crosschain/tradebot")
+@Tag(name = "Cross-Chain (Trade-Bot)")
+public class CrossChainTradeBotResource {
+
+	@Context
+	HttpServletRequest request;
+
+	@GET
+	@Operation(
+		summary = "List current trade-bot states",
+		responses = {
+			@ApiResponse(
+				content = @Content(
+					array = @ArraySchema(
+						schema = @Schema(
+							implementation = TradeBotData.class
+						)
+					)
+				)
+			)
+		}
+	)
+	@ApiErrors({ApiError.REPOSITORY_ISSUE})
+	public List<TradeBotData> getTradeBotStates(
+			// TODO: optional filter for foreign blockchain(s)?
+			) {
+		Security.checkApiCallAllowed(request);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			// TODO: maybe sub-class returned trade-bot data according to which trade-bot/ACCT applies?
+			return repository.getCrossChainRepository().getAllTradeBotData();
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@POST
+	@Path("/create")
+	@Operation(
+		summary = "Create a trade offer (trade-bot entry)",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = TradeBotCreateRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.INVALID_CRITERIA, ApiError.INSUFFICIENT_BALANCE, ApiError.REPOSITORY_ISSUE})
+	@SuppressWarnings("deprecation")
+	public String tradeBotCreator(TradeBotCreateRequest tradeBotCreateRequest) {
+		Security.checkApiCallAllowed(request);
+
+		ForeignBlockchain foreignBlockchain = tradeBotCreateRequest.foreignBlockchain.getInstance();
+
+		// We prefer foreignAmount to deprecated bitcoinAmount
+		if (tradeBotCreateRequest.foreignAmount == null)
+			tradeBotCreateRequest.foreignAmount = tradeBotCreateRequest.bitcoinAmount;
+
+		if (!foreignBlockchain.isValidAddress(tradeBotCreateRequest.receivingAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (tradeBotCreateRequest.tradeTimeout < 60)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		if (tradeBotCreateRequest.foreignAmount == null || tradeBotCreateRequest.foreignAmount <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		if (tradeBotCreateRequest.qortAmount <= 0 || tradeBotCreateRequest.fundingQortAmount <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			// Do some simple checking first
+			Account creator = new PublicKeyAccount(repository, tradeBotCreateRequest.creatorPublicKey);
+
+			if (creator.getConfirmedBalance(Asset.QORT) < tradeBotCreateRequest.fundingQortAmount)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INSUFFICIENT_BALANCE);
+
+			byte[] unsignedBytes = TradeBot.getInstance().createTrade(repository, tradeBotCreateRequest);
+			if (unsignedBytes == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			return Base58.encode(unsignedBytes);
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@POST
+	@Path("/respond")
+	@Operation(
+		summary = "Respond to a trade offer. NOTE: WILL SPEND FUNDS!)",
+		description = "Start a new trade-bot entry to respond to chosen trade offer.",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = TradeBotRespondRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.INVALID_ADDRESS, ApiError.INVALID_CRITERIA, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE, ApiError.REPOSITORY_ISSUE})
+	@SuppressWarnings("deprecation")
+	public String tradeBotResponder(TradeBotRespondRequest tradeBotRespondRequest) {
+		Security.checkApiCallAllowed(request);
+
+		final String atAddress = tradeBotRespondRequest.atAddress;
+
+		// We prefer foreignKey to deprecated xprv58
+		if (tradeBotRespondRequest.foreignKey == null)
+			tradeBotRespondRequest.foreignKey = tradeBotRespondRequest.xprv58;
+
+		if (tradeBotRespondRequest.foreignKey == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		if (atAddress == null || !Crypto.isValidAtAddress(atAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		if (tradeBotRespondRequest.receivingAddress == null || !Crypto.isValidAddress(tradeBotRespondRequest.receivingAddress))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+		// Extract data from cross-chain trading AT
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			ATData atData = fetchAtDataWithChecking(repository, atAddress);
+
+			// TradeBot uses AT's code hash to map to ACCT
+			ACCT acct = TradeBot.getInstance().getAcctUsingAtData(atData);
+			if (acct == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+			if (!acct.getBlockchain().isValidWalletKey(tradeBotRespondRequest.foreignKey))
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+			CrossChainTradeData crossChainTradeData = acct.populateTradeData(repository, atData);
+			if (crossChainTradeData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+			if (crossChainTradeData.mode != AcctMode.OFFERING)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+			AcctTradeBot.ResponseResult result = TradeBot.getInstance().startResponse(repository, atData, acct, crossChainTradeData,
+					tradeBotRespondRequest.foreignKey, tradeBotRespondRequest.receivingAddress);
+
+			switch (result) {
+				case OK:
+					return "true";
+
+				case BALANCE_ISSUE:
+					throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_BALANCE_ISSUE);
+
+				case NETWORK_ISSUE:
+					throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+
+				default:
+					return "false";
+			}
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@DELETE
+	@Operation(
+		summary = "Delete completed trade",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.TEXT_PLAIN,
+				schema = @Schema(
+					type = "string",
+					example = "93MB2qRDNVLxbmmPuYpLdAqn3u2x9ZhaVZK5wELHueP8"
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_ADDRESS, ApiError.REPOSITORY_ISSUE})
+	public String tradeBotDelete(String tradePrivateKey58) {
+		Security.checkApiCallAllowed(request);
+
+		final byte[] tradePrivateKey;
+		try {
+			tradePrivateKey = Base58.decode(tradePrivateKey58);
+
+			if (tradePrivateKey.length != 32)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+		} catch (NumberFormatException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+		}
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			// Handed off to TradeBot
+			return TradeBot.getInstance().deleteEntry(repository, tradePrivateKey) ? "true" : "false";
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+
+	private ATData fetchAtDataWithChecking(Repository repository, String atAddress) throws DataException {
+		ATData atData = repository.getATRepository().fromATAddress(atAddress);
+		if (atData == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
+
+		// No point sending message to AT that's finished
+		if (atData.getIsFinished())
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		return atData;
+	}
+
+}

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

@@ -15,7 +15,7 @@ import org.eclipse.jetty.websocket.api.annotations.OnWebSocketError;
 import org.eclipse.jetty.websocket.api.annotations.OnWebSocketMessage;
 import org.eclipse.jetty.websocket.api.annotations.WebSocket;
 import org.eclipse.jetty.websocket.servlet.WebSocketServletFactory;
-import org.qortal.controller.TradeBot;
+import org.qortal.controller.tradebot.TradeBot;
 import org.qortal.data.crosschain.TradeBotData;
 import org.qortal.event.Event;
 import org.qortal.event.EventBus;
@@ -30,7 +30,7 @@ import org.qortal.utils.Base58;
 public class TradeBotWebSocket extends ApiWebSocket implements Listener {
 
 	/** Cache of trade-bot entry states, keyed by trade-bot entry's "trade private key" (base58) */
-	private static final Map<String, TradeBotData.State> PREVIOUS_STATES = new HashMap<>();
+	private static final Map<String, Integer> PREVIOUS_STATES = new HashMap<>();
 
 	@Override
 	public void configure(WebSocketServletFactory factory) {
@@ -42,7 +42,7 @@ public class TradeBotWebSocket extends ApiWebSocket implements Listener {
 				// How do we properly fail here?
 				return;
 
-			PREVIOUS_STATES.putAll(tradeBotEntries.stream().collect(Collectors.toMap(entry -> Base58.encode(entry.getTradePrivateKey()), TradeBotData::getState)));
+			PREVIOUS_STATES.putAll(tradeBotEntries.stream().collect(Collectors.toMap(entry -> Base58.encode(entry.getTradePrivateKey()), TradeBotData::getStateValue)));
 		} catch (DataException e) {
 			// No output this time
 		}
@@ -59,11 +59,11 @@ public class TradeBotWebSocket extends ApiWebSocket implements Listener {
 		String tradePrivateKey58 = Base58.encode(tradeBotData.getTradePrivateKey());
 
 		synchronized (PREVIOUS_STATES) {
-			if (PREVIOUS_STATES.get(tradePrivateKey58) == tradeBotData.getState())
+			if (PREVIOUS_STATES.get(tradePrivateKey58) == tradeBotData.getStateValue())
 				// Not changed
 				return;
 
-			PREVIOUS_STATES.put(tradePrivateKey58, tradeBotData.getState());
+			PREVIOUS_STATES.put(tradePrivateKey58, tradeBotData.getStateValue());
 		}
 
 		List<TradeBotData> tradeBotEntries = Collections.singletonList(tradeBotData);

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

@@ -38,6 +38,7 @@ import org.qortal.block.Block;
 import org.qortal.block.BlockChain;
 import org.qortal.block.BlockChain.BlockTimingByHeight;
 import org.qortal.controller.Synchronizer.SynchronizationResult;
+import org.qortal.controller.tradebot.TradeBot;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.account.MintingAccountData;
 import org.qortal.data.account.RewardShareData;

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

@@ -0,0 +1,25 @@
+package org.qortal.controller.tradebot;
+
+import org.qortal.api.model.crosschain.TradeBotCreateRequest;
+import org.qortal.crosschain.ACCT;
+import org.qortal.crosschain.ForeignBlockchainException;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+
+public interface AcctTradeBot {
+
+	public enum ResponseResult { OK, BALANCE_ISSUE, NETWORK_ISSUE }
+
+	public byte[] createTrade(Repository repository, TradeBotCreateRequest tradeBotCreateRequest) throws DataException;
+
+	public ResponseResult startResponse(Repository repository, ATData atData, ACCT acct,
+			CrossChainTradeData crossChainTradeData, String foreignKey, String receivingAddress) throws DataException;
+
+	public boolean canDelete(Repository repository, TradeBotData tradeBotData);
+
+	public void progress(Repository repository, TradeBotData tradeBotData) throws DataException, ForeignBlockchainException;
+
+}

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

@@ -0,0 +1,295 @@
+package org.qortal.controller.tradebot;
+
+import java.awt.TrayIcon.MessageType;
+import java.security.SecureRandom;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Random;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.apache.logging.log4j.util.Supplier;
+import org.bitcoinj.core.ECKey;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.api.model.crosschain.TradeBotCreateRequest;
+import org.qortal.controller.Controller;
+import org.qortal.controller.tradebot.AcctTradeBot.ResponseResult;
+import org.qortal.crosschain.ACCT;
+import org.qortal.crosschain.BitcoinACCTv1;
+import org.qortal.crosschain.ForeignBlockchainException;
+import org.qortal.crosschain.LitecoinACCTv1;
+import org.qortal.crosschain.SupportedBlockchain;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.event.Event;
+import org.qortal.event.EventBus;
+import org.qortal.event.Listener;
+import org.qortal.gui.SysTray;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.settings.Settings;
+import org.qortal.utils.NTP;
+
+/**
+ * Performing cross-chain trading steps on behalf of user.
+ * <p>
+ * We deal with three different independent state-spaces here:
+ * <ul>
+ * 	<li>Qortal blockchain</li>
+ * 	<li>Foreign blockchain</li>
+ * 	<li>Trade-bot entries</li>
+ * </ul>
+ */
+public class TradeBot implements Listener {
+
+	private static final Logger LOGGER = LogManager.getLogger(TradeBot.class);
+	private static final Random RANDOM = new SecureRandom();
+
+	public interface StateNameAndValueSupplier {
+		public String getState();
+		public int getStateValue();
+	}
+
+	public static class StateChangeEvent implements Event {
+		private final TradeBotData tradeBotData;
+
+		public StateChangeEvent(TradeBotData tradeBotData) {
+			this.tradeBotData = tradeBotData;
+		}
+
+		public TradeBotData getTradeBotData() {
+			return this.tradeBotData;
+		}
+	}
+
+	private static final Map<Class<? extends ACCT>, Supplier<AcctTradeBot>> acctTradeBotSuppliers = new HashMap<>();
+	static {
+		acctTradeBotSuppliers.put(BitcoinACCTv1.class, BitcoinACCTv1TradeBot::getInstance);
+		// acctTradeBotSuppliers.put(LitecoinACCTv1.class, LitecoinACCTv1TradeBot::getInstance);
+	}
+
+	private static TradeBot instance;
+
+	private TradeBot() {
+		EventBus.INSTANCE.addListener(event -> TradeBot.getInstance().listen(event));
+	}
+
+	public static synchronized TradeBot getInstance() {
+		if (instance == null)
+			instance = new TradeBot();
+
+		return instance;
+	}
+
+	public ACCT getAcctUsingAtData(ATData atData) {
+		byte[] codeHash = atData.getCodeHash();
+		if (codeHash == null)
+			return null;
+
+		return SupportedBlockchain.getAcctByCodeHash(codeHash);
+	}
+
+	public CrossChainTradeData populateTradeData(Repository repository, ATData atData) throws DataException {
+		ACCT acct = this.getAcctUsingAtData(atData);
+		if (acct == null)
+			return null;
+
+		return acct.populateTradeData(repository, atData);
+	}
+
+	/**
+	 * Creates a new trade-bot entry from the "Bob" viewpoint,
+	 * i.e. OFFERing QORT in exchange for foreign blockchain currency.
+	 * <p>
+	 * Generates:
+	 * <ul>
+	 * 	<li>new 'trade' private key</li>
+	 * 	<li>secret(s)</li>
+	 * </ul>
+	 * Derives:
+	 * <ul>
+	 * 	<li>'native' (as in Qortal) public key, public key hash, address (starting with Q)</li>
+	 * 	<li>'foreign' public key, public key hash</li>
+	 *	<li>hash(es) of secret(s)</li>
+	 * </ul>
+	 * A Qortal AT is then constructed including the following as constants in the 'data segment':
+	 * <ul>
+	 * 	<li>'native' (Qortal) 'trade' address - used to MESSAGE AT</li>
+	 * 	<li>'foreign' public key hash - used by Alice's to allow redeem of currency on foreign blockchain</li>
+	 * 	<li>hash(es) of secret(s) - used by AT (optional) and foreign blockchain as needed</li>
+	 * 	<li>QORT amount on offer by Bob</li>
+	 * 	<li>foreign currency amount expected in return by Bob (from Alice)</li>
+	 * 	<li>trading timeout, in case things go wrong and everyone needs to refund</li>
+	 * </ul>
+	 * Returns a DEPLOY_AT transaction that needs to be signed and broadcast to the Qortal network.
+	 * <p>
+	 * Trade-bot will wait for Bob's AT to be deployed before taking next step.
+	 * <p>
+	 * @param repository
+	 * @param tradeBotCreateRequest
+	 * @return raw, unsigned DEPLOY_AT transaction
+	 * @throws DataException
+	 */
+	public byte[] createTrade(Repository repository, TradeBotCreateRequest tradeBotCreateRequest) throws DataException {
+		// Fetch latest ACCT version for requested foreign blockchain
+		ACCT acct = tradeBotCreateRequest.foreignBlockchain.getLatestAcct();
+
+		AcctTradeBot acctTradeBot = findTradeBotForAcct(acct);
+		if (acctTradeBot == null)
+			return null;
+
+		return acctTradeBot.createTrade(repository, tradeBotCreateRequest);
+	}
+
+	/**
+	 * Creates a trade-bot entry from the 'Alice' viewpoint,
+	 * i.e. matching foreign blockchain currency to an existing QORT offer.
+	 * <p>
+	 * Requires a chosen trade offer from Bob, passed by <tt>crossChainTradeData</tt>
+	 * and access to a foreign blockchain wallet via <tt>foreignKey</tt>.
+	 * <p>
+	 * @param repository
+	 * @param crossChainTradeData chosen trade OFFER that Alice wants to match
+	 * @param foreignKey foreign blockchain wallet key
+	 * @throws DataException
+	 */
+	public ResponseResult startResponse(Repository repository, ATData atData, ACCT acct,
+			CrossChainTradeData crossChainTradeData, String foreignKey, String receivingAddress) throws DataException {
+		AcctTradeBot acctTradeBot = findTradeBotForAcct(acct);
+		if (acctTradeBot == null) {
+			LOGGER.debug(() -> String.format("Couldn't find ACCT trade-bot for AT %s", atData.getATAddress()));
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		return acctTradeBot.startResponse(repository, atData, acct, crossChainTradeData, foreignKey, receivingAddress);
+	}
+
+	public boolean deleteEntry(Repository repository, byte[] tradePrivateKey) throws DataException {
+		TradeBotData tradeBotData = repository.getCrossChainRepository().getTradeBotData(tradePrivateKey);
+		if (tradeBotData == null)
+			// Can't delete what we don't have!
+			return false;
+
+		boolean canDelete = false;
+
+		ACCT acct = SupportedBlockchain.getAcctByName(tradeBotData.getAcctName());
+		if (acct == null)
+			// We can't/no longer support this ACCT
+			canDelete = true;
+		else {
+			AcctTradeBot acctTradeBot = findTradeBotForAcct(acct);
+			canDelete = acctTradeBot == null || acctTradeBot.canDelete(repository, tradeBotData);
+		}
+
+		if (canDelete)
+			repository.getCrossChainRepository().delete(tradePrivateKey);
+
+		return canDelete;
+	}
+
+	@Override
+	public void listen(Event event) {
+		if (!(event instanceof Controller.NewBlockEvent))
+			return;
+
+		synchronized (this) {
+			List<TradeBotData> allTradeBotData;
+
+			try (final Repository repository = RepositoryManager.getRepository()) {
+				allTradeBotData = repository.getCrossChainRepository().getAllTradeBotData();
+			} catch (DataException e) {
+				LOGGER.error("Couldn't run trade bot due to repository issue", e);
+				return;
+			}
+
+			for (TradeBotData tradeBotData : allTradeBotData)
+				try (final Repository repository = RepositoryManager.getRepository()) {
+					// Find ACCT-specific trade-bot for this entry
+					ACCT acct = SupportedBlockchain.getAcctByName(tradeBotData.getAcctName());
+					if (acct == null) {
+						LOGGER.debug(() -> String.format("Couldn't find ACCT matching name %s", tradeBotData.getAcctName()));
+						continue;
+					}
+
+					AcctTradeBot acctTradeBot = findTradeBotForAcct(acct);
+					if (acctTradeBot == null) {
+						LOGGER.debug(() -> String.format("Couldn't find ACCT trade-bot matching name %s", tradeBotData.getAcctName()));
+						continue;
+					}
+
+					acctTradeBot.progress(repository, tradeBotData);
+				} catch (DataException e) {
+					LOGGER.error("Couldn't run trade bot due to repository issue", e);
+				} catch (ForeignBlockchainException e) {
+					LOGGER.warn(() -> String.format("Bitcoin issue processing trade-bot entry for AT %s: %s", tradeBotData.getAtAddress(), e.getMessage()));
+				}
+		}
+	}
+
+	/*package*/ static byte[] generateTradePrivateKey() {
+		// The private key is used for both Curve25519 and secp256k1 so needs to be valid for both.
+		// Curve25519 accepts any seed, so generate a valid secp256k1 key and use that.
+		return new ECKey().getPrivKeyBytes();
+	}
+
+	/*package*/ static byte[] deriveTradeNativePublicKey(byte[] privateKey) {
+		return PrivateKeyAccount.toPublicKey(privateKey);
+	}
+
+	/*package*/ static byte[] deriveTradeForeignPublicKey(byte[] privateKey) {
+		return ECKey.fromPrivate(privateKey).getPubKey();
+	}
+
+	/*package*/ static byte[] generateSecret() {
+		byte[] secret = new byte[32];
+		RANDOM.nextBytes(secret);
+		return secret;
+	}
+
+	/** Updates trade-bot entry to new state, with current timestamp, logs message and notifies state-change listeners. */
+	/*package*/ static void updateTradeBotState(Repository repository, TradeBotData tradeBotData,
+			String newState, int newStateValue, Supplier<String> logMessageSupplier) throws DataException {
+		tradeBotData.setState(newState);
+		tradeBotData.setStateValue(newStateValue);
+		tradeBotData.setTimestamp(NTP.getTime());
+		repository.getCrossChainRepository().save(tradeBotData);
+		repository.saveChanges();
+
+		if (Settings.getInstance().isTradebotSystrayEnabled())
+			SysTray.getInstance().showMessage("Trade-Bot", String.format("%s: %s", tradeBotData.getAtAddress(), newState), MessageType.INFO);
+
+		if (logMessageSupplier != null)
+			LOGGER.info(logMessageSupplier);
+
+		LOGGER.debug(() -> String.format("new state for trade-bot entry based on AT %s: %s", tradeBotData.getAtAddress(), newState));
+
+		notifyStateChange(tradeBotData);
+	}
+
+	/** Updates trade-bot entry to new state, with current timestamp, logs message and notifies state-change listeners. */
+	/*package*/ static void updateTradeBotState(Repository repository, TradeBotData tradeBotData, StateNameAndValueSupplier newStateSupplier, Supplier<String> logMessageSupplier) throws DataException {
+		updateTradeBotState(repository, tradeBotData, newStateSupplier.getState(), newStateSupplier.getStateValue(), logMessageSupplier);
+	}
+
+	/** Updates trade-bot entry to new state, with current timestamp, logs message and notifies state-change listeners. */
+	/*package*/ static void updateTradeBotState(Repository repository, TradeBotData tradeBotData, Supplier<String> logMessageSupplier) throws DataException {
+		updateTradeBotState(repository, tradeBotData, tradeBotData.getState(), tradeBotData.getStateValue(), logMessageSupplier);
+	}
+
+	/*package*/ static void notifyStateChange(TradeBotData tradeBotData) {
+		StateChangeEvent stateChangeEvent = new StateChangeEvent(tradeBotData);
+		EventBus.INSTANCE.notify(stateChangeEvent);
+	}
+
+	/*package*/ static AcctTradeBot findTradeBotForAcct(ACCT acct) {
+		Supplier<AcctTradeBot> acctTradeBotSupplier = acctTradeBotSuppliers.get(acct.getClass());
+		if (acctTradeBotSupplier == null)
+			return null;
+
+		return acctTradeBotSupplier.get();
+	}
+
+}

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

@@ -0,0 +1,16 @@
+package org.qortal.crosschain;
+
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+
+public interface ACCT {
+
+	public byte[] getCodeBytesHash();
+
+	public ForeignBlockchain getBlockchain();
+
+	public CrossChainTradeData populateTradeData(Repository repository, ATData atData) throws DataException;
+
+}

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

@@ -98,11 +98,12 @@ import com.google.common.primitives.Bytes;
  * </li>
  * </ul>
  */
-public class BitcoinACCTv1 {
+public class BitcoinACCTv1 implements ACCT {
+
+	public static final String NAME = "BitcoinACCTv1";
+	public static final byte[] CODE_BYTES_HASH = HashCode.fromString("f7f419522a9aaa3c671149878f8c1374dfc59d4fd86ca43ff2a4d913cfbc9e89").asBytes(); // SHA256 of AT code bytes
 
 	public static final int SECRET_LENGTH = 32;
-	public static final int MIN_LOCKTIME = 1500000000;
-	public static final byte[] CODE_BYTES_HASH = HashCode.fromString("f7f419522a9aaa3c671149878f8c1374dfc59d4fd86ca43ff2a4d913cfbc9e89").asBytes(); // SHA256 of AT code bytes
 
 	/** <b>Value</b> offset into AT segment where 'mode' variable (long) is stored. (Multiply by MachineState.VALUE_SIZE for byte offset). */
 	private static final int MODE_VALUE_OFFSET = 68;
@@ -123,9 +124,26 @@ public class BitcoinACCTv1 {
 	public static final int REDEEM_MESSAGE_LENGTH = 32 /*secret*/ + 32 /*secret*/ + 32 /*partner's Qortal receiving address padded from 25 to 32*/;
 	public static final int CANCEL_MESSAGE_LENGTH = 32 /*AT creator's Qortal address*/;
 
+	private static BitcoinACCTv1 instance;
+
 	private BitcoinACCTv1() {
 	}
 
+	public static synchronized BitcoinACCTv1 getInstance() {
+		if (instance == null)
+			instance = new BitcoinACCTv1();
+
+		return instance;
+	}
+
+	public byte[] getCodeBytesHash() {
+		return CODE_BYTES_HASH;
+	}
+
+	public ForeignBlockchain getBlockchain() {
+		return Bitcoin.getInstance();
+	}
+
 	/**
 	 * Returns Qortal AT creation bytes for cross-chain trading AT.
 	 * <p>
@@ -590,7 +608,7 @@ public class BitcoinACCTv1 {
 	 * @param atAddress
 	 * @throws DataException
 	 */
-	public static CrossChainTradeData populateTradeData(Repository repository, ATData atData) throws DataException {
+	public CrossChainTradeData populateTradeData(Repository repository, ATData atData) throws DataException {
 		ATStateData atStateData = repository.getATRepository().getLatestATState(atData.getATAddress());
 		return populateTradeData(repository, atData.getCreatorPublicKey(), atStateData);
 	}

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

@@ -9,6 +9,7 @@ import java.util.stream.Collectors;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.bitcoinj.core.Address;
+import org.bitcoinj.core.AddressFormatException;
 import org.bitcoinj.core.Coin;
 import org.bitcoinj.core.Context;
 import org.bitcoinj.core.ECKey;
@@ -36,7 +37,7 @@ import org.qortal.utils.BitTwiddling;
 import com.google.common.hash.HashCode;
 
 /** Bitcoin-like (Bitcoin, Litecoin, etc.) support */
-public abstract class Bitcoiny {
+public abstract class Bitcoiny implements ForeignBlockchain {
 
 	protected static final Logger LOGGER = LogManager.getLogger(Bitcoiny.class);
 
@@ -82,6 +83,24 @@ public abstract class Bitcoiny {
 		return this.params;
 	}
 
+	// Interface obligations 
+
+	@Override
+	public boolean isValidAddress(String address) {
+		try {
+			ScriptType addressType = Address.fromString(this.params, address).getOutputScriptType();
+
+			return addressType == ScriptType.P2PKH || addressType == ScriptType.P2SH;
+		} catch (AddressFormatException e) {
+			return false;
+		}
+	}
+
+	@Override
+	public boolean isValidWalletKey(String walletKey) {
+		return this.isValidXprv(walletKey);
+	}
+
 	// Actual useful methods for use by other classes
 
 	public String format(Coin amount) {
@@ -247,9 +266,10 @@ public abstract class Bitcoiny {
 	 * @param xprv58 BIP32 private key
 	 * @param recipient P2PKH address
 	 * @param amount unscaled amount
+	 * @param feePerByte unscaled fee per byte, or null to use default fees
 	 * @return transaction, or null if insufficient funds
 	 */
-	public Transaction buildSpend(String xprv58, String recipient, long amount) {
+	public Transaction buildSpend(String xprv58, String recipient, long amount, Long feePerByte) {
 		Context.propagate(bitcoinjContext);
 
 		Wallet wallet = Wallet.fromSpendingKeyB58(this.params, xprv58, DeterministicHierarchy.BIP32_STANDARDISATION_TIME_SECS);
@@ -258,8 +278,11 @@ public abstract class Bitcoiny {
 		Address destination = Address.fromString(this.params, recipient);
 		SendRequest sendRequest = SendRequest.to(destination, Coin.valueOf(amount));
 
-		// Allow override of default for TestNet3, etc.
+		if (feePerByte != null)
-		sendRequest.feePerKb = this.getFeePerKb();
+			sendRequest.feePerKb = Coin.valueOf(feePerByte * 1000L); // Note: 1000 not 1024
+		else
+			// Allow override of default for TestNet3, etc.
+			sendRequest.feePerKb = this.getFeePerKb();
 
 		try {
 			wallet.completeTx(sendRequest);
@@ -269,6 +292,18 @@ public abstract class Bitcoiny {
 		}
 	}
 
+	/**
+	 * Returns bitcoinj transaction sending <tt>amount</tt> to <tt>recipient</tt> using default fees.
+	 * 
+	 * @param xprv58 BIP32 private key
+	 * @param recipient P2PKH address
+	 * @param amount unscaled amount
+	 * @return transaction, or null if insufficient funds
+	 */
+	public Transaction buildSpend(String xprv58, String recipient, long amount) {
+		return buildSpend(xprv58, recipient, amount, null);
+	}
+
 	/**
 	 * Returns unspent Bitcoin balance given 'm' BIP32 key.
 	 *

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

@@ -0,0 +1,9 @@
+package org.qortal.crosschain;
+
+public interface ForeignBlockchain {
+
+	public boolean isValidAddress(String address);
+
+	public boolean isValidWalletKey(String walletKey);
+
+}

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

@@ -87,11 +87,12 @@ import com.google.common.primitives.Bytes;
  * </li>
  * </ul>
  */
-public class LitecoinACCTv1 {
+public class LitecoinACCTv1 implements ACCT {
+
+	public static final String NAME = "LitcoinACCTv1";
+	public static final byte[] CODE_BYTES_HASH = HashCode.fromString("0fb15ad9ad1867dfbcafa51155481aa15d984ff9506f2b428eca4e2a2feac2b3").asBytes(); // SHA256 of AT code bytes
 
 	public static final int SECRET_LENGTH = 32;
-	public static final int MIN_LOCKTIME = 1500000000;
-	public static final byte[] CODE_BYTES_HASH = HashCode.fromString("0fb15ad9ad1867dfbcafa51155481aa15d984ff9506f2b428eca4e2a2feac2b3").asBytes(); // SHA256 of AT code bytes
 
 	/** <b>Value</b> offset into AT segment where 'mode' variable (long) is stored. (Multiply by MachineState.VALUE_SIZE for byte offset). */
 	private static final int MODE_VALUE_OFFSET = 61;
@@ -112,9 +113,26 @@ public class LitecoinACCTv1 {
 	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 LitecoinACCTv1 instance;
+
 	private LitecoinACCTv1() {
 	}
 
+	public static synchronized LitecoinACCTv1 getInstance() {
+		if (instance == null)
+			instance = new LitecoinACCTv1();
+
+		return instance;
+	}
+
+	public byte[] getCodeBytesHash() {
+		return CODE_BYTES_HASH;
+	}
+
+	public ForeignBlockchain getBlockchain() {
+		return Litecoin.getInstance();
+	}
+
 	/**
 	 * Returns Qortal AT creation bytes for cross-chain trading AT.
 	 * <p>
@@ -541,7 +559,7 @@ public class LitecoinACCTv1 {
 	 * @param atAddress
 	 * @throws DataException
 	 */
-	public static CrossChainTradeData populateTradeData(Repository repository, ATData atData) throws DataException {
+	public CrossChainTradeData populateTradeData(Repository repository, ATData atData) throws DataException {
 		ATStateData atStateData = repository.getATRepository().getLatestATState(atData.getATAddress());
 		return populateTradeData(repository, atData.getCreatorPublicKey(), atStateData);
 	}

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

@@ -0,0 +1,80 @@
+package org.qortal.crosschain;
+
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Supplier;
+
+import org.qortal.utils.ByteArray;
+import org.qortal.utils.Triple;
+
+public enum SupportedBlockchain {
+
+	BITCOIN(Arrays.asList(
+				Triple.valueOf(BitcoinACCTv1.NAME, BitcoinACCTv1.CODE_BYTES_HASH, BitcoinACCTv1::getInstance)
+			)) {
+		@Override
+		public ForeignBlockchain getInstance() {
+			return Bitcoin.getInstance();
+		}
+
+		@Override
+		public ACCT getLatestAcct() {
+			return BitcoinACCTv1.getInstance();
+		}
+	},
+
+	LITECOIN(Arrays.asList(
+			Triple.valueOf(LitecoinACCTv1.NAME, LitecoinACCTv1.CODE_BYTES_HASH, LitecoinACCTv1::getInstance)
+		)) {
+		@Override
+		public ForeignBlockchain getInstance() {
+			return Litecoin.getInstance();
+		}
+
+		@Override
+		public ACCT getLatestAcct() {
+			return LitecoinACCTv1.getInstance();
+		}
+	};
+
+	private final Map<ByteArray, Supplier<ACCT>> supportedAcctsByCodeHash = new HashMap<>();
+	private final Map<String, Supplier<ACCT>> supportedAcctsByName = new HashMap<>();
+
+	SupportedBlockchain(List<Triple<String, byte[], Supplier<ACCT>>> supportedAccts) {
+		supportedAccts.forEach(triple -> triple.consume((acctName, hashBytes, supplier) -> {
+			supportedAcctsByCodeHash.put(new ByteArray(hashBytes), supplier);
+			supportedAcctsByName.put(acctName, supplier);
+		}));
+	}
+
+	public abstract ForeignBlockchain getInstance();
+
+	public abstract ACCT getLatestAcct();
+
+	public static ACCT getAcctByCodeHash(byte[] codeHash) {
+		for (SupportedBlockchain supportedBlockchain : SupportedBlockchain.values()) {
+
+			@SuppressWarnings("unlikely-arg-type") // OK, because ByteArray is designed to work with byte[]
+			Supplier<ACCT> acctInstanceSupplier = supportedBlockchain.supportedAcctsByCodeHash.get(codeHash);
+
+			if (acctInstanceSupplier != null)
+				return acctInstanceSupplier.get();
+		}
+
+		return null;
+	}
+
+	public static ACCT getAcctByName(String acctName) {
+		for (SupportedBlockchain supportedBlockchain : SupportedBlockchain.values()) {
+			Supplier<ACCT> acctInstanceSupplier = supportedBlockchain.supportedAcctsByName.get(acctName);
+
+			if (acctInstanceSupplier != null)
+				return acctInstanceSupplier.get();
+		}
+
+		return null;
+	}
+
+}

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

@@ -1,10 +1,5 @@
 package org.qortal.data.crosschain;
 
-import static java.util.Arrays.stream;
-import static java.util.stream.Collectors.toMap;
-
-import java.util.Map;
-
 import javax.xml.bind.annotation.XmlAccessType;
 import javax.xml.bind.annotation.XmlAccessorType;
 import javax.xml.bind.annotation.XmlTransient;
@@ -18,22 +13,13 @@ public class TradeBotData {
 
 	private byte[] tradePrivateKey;
 
-	public enum State {
+	private String acctName;
-		BOB_WAITING_FOR_AT_CONFIRM(10), BOB_WAITING_FOR_MESSAGE(15), BOB_WAITING_FOR_P2SH_B(20), BOB_WAITING_FOR_AT_REDEEM(25), BOB_DONE(30), BOB_REFUNDED(35),
+	private String tradeState;
-		ALICE_WAITING_FOR_P2SH_A(80), ALICE_WAITING_FOR_AT_LOCK(85), ALICE_WATCH_P2SH_B(90), ALICE_DONE(95), ALICE_REFUNDING_B(100), ALICE_REFUNDING_A(105), ALICE_REFUNDED(110);
 
-		public final int value;
+	// Internal use - not shown via API
-		private static final Map<Integer, State> map = stream(State.values()).collect(toMap(state -> state.value, state -> state));
+	@XmlTransient
-
+	@Schema(hidden = true)
-		State(int value) {
+	private int tradeStateValue;
-			this.value = value;
-		}
-
-		public static State valueOf(int value) {
-			return map.get(value);
-		}
-	}
-	private State tradeState;
 
 	private String creatorAddress;
 	private String atAddress;
@@ -50,19 +36,25 @@ public class TradeBotData {
 	private byte[] secret;
 	private byte[] hashOfSecret;
 
+	private String foreignBlockchain;
 	private byte[] tradeForeignPublicKey;
 	private byte[] tradeForeignPublicKeyHash;
 
+	@Deprecated
+	@Schema(description = "DEPRECATED: use foreignAmount instead", type = "number")
 	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
 	private long bitcoinAmount;
 
+	@Schema(description = "amount in foreign blockchain currency", type = "number")
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	private long foreignAmount;
+
 	// Never expose this via API
 	@XmlTransient
 	@Schema(hidden = true)
-	private String xprv58;
+	private String foreignKey;
 
 	private byte[] lastTransactionSignature;
-
 	private Integer lockTimeA;
 
 	// Could be Bitcoin or Qortal...
@@ -72,14 +64,18 @@ public class TradeBotData {
 		/* JAXB */
 	}
 
-	public TradeBotData(byte[] tradePrivateKey, State tradeState, String creatorAddress, String atAddress,
+	public TradeBotData(byte[] tradePrivateKey, String acctName, String tradeState, int tradeStateValue,
+			String creatorAddress, String atAddress,
 			long timestamp, long qortAmount,
 			byte[] tradeNativePublicKey, byte[] tradeNativePublicKeyHash, String tradeNativeAddress,
 			byte[] secret, byte[] hashOfSecret,
-			byte[] tradeForeignPublicKey, byte[] tradeForeignPublicKeyHash,
+			String foreignBlockchain, byte[] tradeForeignPublicKey, byte[] tradeForeignPublicKeyHash,
-			long bitcoinAmount, String xprv58, byte[] lastTransactionSignature, Integer lockTimeA, byte[] receivingAccountInfo) {
+			long foreignAmount, String foreignKey,
+			byte[] lastTransactionSignature, Integer lockTimeA, byte[] receivingAccountInfo) {
 		this.tradePrivateKey = tradePrivateKey;
+		this.acctName = acctName;
 		this.tradeState = tradeState;
+		this.tradeStateValue = tradeStateValue;
 		this.creatorAddress = creatorAddress;
 		this.atAddress = atAddress;
 		this.timestamp = timestamp;
@@ -89,10 +85,13 @@ public class TradeBotData {
 		this.tradeNativeAddress = tradeNativeAddress;
 		this.secret = secret;
 		this.hashOfSecret = hashOfSecret;
+		this.foreignBlockchain = foreignBlockchain;
 		this.tradeForeignPublicKey = tradeForeignPublicKey;
 		this.tradeForeignPublicKeyHash = tradeForeignPublicKeyHash;
-		this.bitcoinAmount = bitcoinAmount;
+		// deprecated copy
-		this.xprv58 = xprv58;
+		this.bitcoinAmount = foreignAmount;
+		this.foreignAmount = foreignAmount;
+		this.foreignKey = foreignKey;
 		this.lastTransactionSignature = lastTransactionSignature;
 		this.lockTimeA = lockTimeA;
 		this.receivingAccountInfo = receivingAccountInfo;
@@ -102,14 +101,26 @@ public class TradeBotData {
 		return this.tradePrivateKey;
 	}
 
-	public State getState() {
+	public String getAcctName() {
+		return this.acctName;
+	}
+
+	public String getState() {
 		return this.tradeState;
 	}
 
-	public void setState(State state) {
+	public void setState(String state) {
 		this.tradeState = state;
 	}
 
+	public int getStateValue() {
+		return this.tradeStateValue;
+	}
+
+	public void setStateValue(int stateValue) {
+		this.tradeStateValue = stateValue;
+	}
+
 	public String getCreatorAddress() {
 		return this.creatorAddress;
 	}
@@ -154,6 +165,10 @@ public class TradeBotData {
 		return this.hashOfSecret;
 	}
 
+	public String getForeignBlockchain() {
+		return this.foreignBlockchain;
+	}
+
 	public byte[] getTradeForeignPublicKey() {
 		return this.tradeForeignPublicKey;
 	}
@@ -162,12 +177,12 @@ public class TradeBotData {
 		return this.tradeForeignPublicKeyHash;
 	}
 
-	public long getBitcoinAmount() {
+	public long getForeignAmount() {
-		return this.bitcoinAmount;
+		return this.foreignAmount;
 	}
 
-	public String getXprv58() {
+	public String getForeignKey() {
-		return this.xprv58;
+		return this.foreignKey;
 	}
 
 	public byte[] getLastTransactionSignature() {
@@ -192,7 +207,7 @@ public class TradeBotData {
 
 	// Mostly for debugging
 	public String toString() {
-		return String.format("%s: %s", this.atAddress, this.tradeState.name());
+		return String.format("%s: %s (%d)", this.atAddress, this.tradeState, this.tradeStateValue);
 	}
 
 }

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

@@ -19,12 +19,13 @@ public class HSQLDBCrossChainRepository implements CrossChainRepository {
 
 	@Override
 	public TradeBotData getTradeBotData(byte[] tradePrivateKey) throws DataException {
-		String sql = "SELECT trade_state, creator_address, at_address, "
+		String sql = "SELECT acct_name, trade_state, trade_state_value, "
+				+ "creator_address, at_address, "
 				+ "updated_when, qort_amount, "
 				+ "trade_native_public_key, trade_native_public_key_hash, "
 				+ "trade_native_address, secret, hash_of_secret, "
-				+ "trade_foreign_public_key, trade_foreign_public_key_hash, "
+				+ "foreign_blockchain, trade_foreign_public_key, trade_foreign_public_key_hash, "
-				+ "bitcoin_amount, xprv58, last_transaction_signature, locktime_a, receiving_account_info "
+				+ "foreign_amount, foreign_key, last_transaction_signature, locktime_a, receiving_account_info "
 				+ "FROM TradeBotStates "
 				+ "WHERE trade_private_key = ?";
 
@@ -32,36 +33,36 @@ public class HSQLDBCrossChainRepository implements CrossChainRepository {
 			if (resultSet == null)
 				return null;
 
-			int tradeStateValue = resultSet.getInt(1);
+			String acctName = resultSet.getString(1);
-			TradeBotData.State tradeState = TradeBotData.State.valueOf(tradeStateValue);
+			String tradeState = resultSet.getString(2);
-			if (tradeState == null)
+			int tradeStateValue = resultSet.getInt(3);
-				throw new DataException("Illegal trade-bot trade-state fetched from repository");
+			String creatorAddress = resultSet.getString(4);
-
+			String atAddress = resultSet.getString(5);
-			String creatorAddress = resultSet.getString(2);
+			long timestamp = resultSet.getLong(6);
-			String atAddress = resultSet.getString(3);
+			long qortAmount = resultSet.getLong(7);
-			long timestamp = resultSet.getLong(4);
+			byte[] tradeNativePublicKey = resultSet.getBytes(8);
-			long qortAmount = resultSet.getLong(5);
+			byte[] tradeNativePublicKeyHash = resultSet.getBytes(9);
-			byte[] tradeNativePublicKey = resultSet.getBytes(6);
+			String tradeNativeAddress = resultSet.getString(10);
-			byte[] tradeNativePublicKeyHash = resultSet.getBytes(7);
+			byte[] secret = resultSet.getBytes(11);
-			String tradeNativeAddress = resultSet.getString(8);
+			byte[] hashOfSecret = resultSet.getBytes(12);
-			byte[] secret = resultSet.getBytes(9);
+			String foreignBlockchain = resultSet.getString(13);
-			byte[] hashOfSecret = resultSet.getBytes(10);
+			byte[] tradeForeignPublicKey = resultSet.getBytes(14);
-			byte[] tradeForeignPublicKey = resultSet.getBytes(11);
+			byte[] tradeForeignPublicKeyHash = resultSet.getBytes(15);
-			byte[] tradeForeignPublicKeyHash = resultSet.getBytes(12);
+			long foreignAmount = resultSet.getLong(16);
-			long bitcoinAmount = resultSet.getLong(13);
+			String foreignKey = resultSet.getString(17);
-			String xprv58 = resultSet.getString(14);
+			byte[] lastTransactionSignature = resultSet.getBytes(18);
-			byte[] lastTransactionSignature = resultSet.getBytes(15);
+			Integer lockTimeA = resultSet.getInt(19);
-			Integer lockTimeA = resultSet.getInt(16);
 			if (lockTimeA == 0 && resultSet.wasNull())
 				lockTimeA = null;
-			byte[] receivingAccountInfo = resultSet.getBytes(17);
+			byte[] receivingAccountInfo = resultSet.getBytes(20);
 
-			return new TradeBotData(tradePrivateKey, tradeState,
+			return new TradeBotData(tradePrivateKey, acctName,
+					tradeState, tradeStateValue,
 					creatorAddress, atAddress, timestamp, qortAmount,
 					tradeNativePublicKey, tradeNativePublicKeyHash, tradeNativeAddress,
 					secret, hashOfSecret,
-					tradeForeignPublicKey, tradeForeignPublicKeyHash,
+					foreignBlockchain, tradeForeignPublicKey, tradeForeignPublicKeyHash,
-					bitcoinAmount, xprv58, lastTransactionSignature, lockTimeA, receivingAccountInfo);
+					foreignAmount, foreignKey, lastTransactionSignature, lockTimeA, receivingAccountInfo);
 		} catch (SQLException e) {
 			throw new DataException("Unable to fetch trade-bot trading state from repository", e);
 		}
@@ -69,12 +70,13 @@ public class HSQLDBCrossChainRepository implements CrossChainRepository {
 
 	@Override
 	public List<TradeBotData> getAllTradeBotData() throws DataException {
-		String sql = "SELECT trade_private_key, trade_state, creator_address, at_address, "
+		String sql = "SELECT trade_private_key, acct_name, trade_state, trade_state_value, "
+				+ "creator_address, at_address, "
 				+ "updated_when, qort_amount, "
 				+ "trade_native_public_key, trade_native_public_key_hash, "
 				+ "trade_native_address, secret, hash_of_secret, "
-				+ "trade_foreign_public_key, trade_foreign_public_key_hash, "
+				+ "foreign_blockchain, trade_foreign_public_key, trade_foreign_public_key_hash, "
-				+ "bitcoin_amount, xprv58, last_transaction_signature, locktime_a, receiving_account_info "
+				+ "foreign_amount, foreign_key, last_transaction_signature, locktime_a, receiving_account_info "
 				+ "FROM TradeBotStates";
 
 		List<TradeBotData> allTradeBotData = new ArrayList<>();
@@ -85,36 +87,36 @@ public class HSQLDBCrossChainRepository implements CrossChainRepository {
 
 			do {
 				byte[] tradePrivateKey = resultSet.getBytes(1);
-				int tradeStateValue = resultSet.getInt(2);
+				String acctName = resultSet.getString(2);
-				TradeBotData.State tradeState = TradeBotData.State.valueOf(tradeStateValue);
+				String tradeState = resultSet.getString(3);
-				if (tradeState == null)
+				int tradeStateValue = resultSet.getInt(4);
-					throw new DataException("Illegal trade-bot trade-state fetched from repository");
+				String creatorAddress = resultSet.getString(5);
-
+				String atAddress = resultSet.getString(6);
-				String creatorAddress = resultSet.getString(3);
+				long timestamp = resultSet.getLong(7);
-				String atAddress = resultSet.getString(4);
+				long qortAmount = resultSet.getLong(8);
-				long timestamp = resultSet.getLong(5);
+				byte[] tradeNativePublicKey = resultSet.getBytes(9);
-				long qortAmount = resultSet.getLong(6);
+				byte[] tradeNativePublicKeyHash = resultSet.getBytes(10);
-				byte[] tradeNativePublicKey = resultSet.getBytes(7);
+				String tradeNativeAddress = resultSet.getString(11);
-				byte[] tradeNativePublicKeyHash = resultSet.getBytes(8);
+				byte[] secret = resultSet.getBytes(12);
-				String tradeNativeAddress = resultSet.getString(9);
+				byte[] hashOfSecret = resultSet.getBytes(13);
-				byte[] secret = resultSet.getBytes(10);
+				String foreignBlockchain = resultSet.getString(14);
-				byte[] hashOfSecret = resultSet.getBytes(11);
+				byte[] tradeForeignPublicKey = resultSet.getBytes(15);
-				byte[] tradeForeignPublicKey = resultSet.getBytes(12);
+				byte[] tradeForeignPublicKeyHash = resultSet.getBytes(16);
-				byte[] tradeForeignPublicKeyHash = resultSet.getBytes(13);
+				long foreignAmount = resultSet.getLong(17);
-				long bitcoinAmount = resultSet.getLong(14);
+				String foreignKey = resultSet.getString(18);
-				String xprv58 = resultSet.getString(15);
+				byte[] lastTransactionSignature = resultSet.getBytes(19);
-				byte[] lastTransactionSignature = resultSet.getBytes(16);
+				Integer lockTimeA = resultSet.getInt(20);
-				Integer lockTimeA = resultSet.getInt(17);
 				if (lockTimeA == 0 && resultSet.wasNull())
 					lockTimeA = null;
-				byte[] receivingAccountInfo = resultSet.getBytes(18);
+				byte[] receivingAccountInfo = resultSet.getBytes(21);
 
-				TradeBotData tradeBotData = new TradeBotData(tradePrivateKey, tradeState,
+				TradeBotData tradeBotData = new TradeBotData(tradePrivateKey, acctName,
+						tradeState, tradeStateValue,
 						creatorAddress, atAddress, timestamp, qortAmount,
 						tradeNativePublicKey, tradeNativePublicKeyHash, tradeNativeAddress,
 						secret, hashOfSecret,
-						tradeForeignPublicKey, tradeForeignPublicKeyHash,
+						foreignBlockchain, tradeForeignPublicKey, tradeForeignPublicKeyHash,
-						bitcoinAmount, xprv58, lastTransactionSignature, lockTimeA, receivingAccountInfo);
+						foreignAmount, foreignKey, lastTransactionSignature, lockTimeA, receivingAccountInfo);
 				allTradeBotData.add(tradeBotData);
 			} while (resultSet.next());
 
@@ -129,7 +131,9 @@ public class HSQLDBCrossChainRepository implements CrossChainRepository {
 		HSQLDBSaver saveHelper = new HSQLDBSaver("TradeBotStates");
 
 		saveHelper.bind("trade_private_key", tradeBotData.getTradePrivateKey())
-				.bind("trade_state", tradeBotData.getState().value)
+				.bind("acct_name", tradeBotData.getAcctName())
+				.bind("trade_state", tradeBotData.getState())
+				.bind("trade_state_value", tradeBotData.getStateValue())
 				.bind("creator_address", tradeBotData.getCreatorAddress())
 				.bind("at_address", tradeBotData.getAtAddress())
 				.bind("updated_when", tradeBotData.getTimestamp())
@@ -137,11 +141,13 @@ public class HSQLDBCrossChainRepository implements CrossChainRepository {
 				.bind("trade_native_public_key", tradeBotData.getTradeNativePublicKey())
 				.bind("trade_native_public_key_hash", tradeBotData.getTradeNativePublicKeyHash())
 				.bind("trade_native_address", tradeBotData.getTradeNativeAddress())
-				.bind("secret", tradeBotData.getSecret()).bind("hash_of_secret", tradeBotData.getHashOfSecret())
+				.bind("secret", tradeBotData.getSecret())
+				.bind("hash_of_secret", tradeBotData.getHashOfSecret())
+				.bind("foreign_blockchain", tradeBotData.getForeignBlockchain())
 				.bind("trade_foreign_public_key", tradeBotData.getTradeForeignPublicKey())
 				.bind("trade_foreign_public_key_hash", tradeBotData.getTradeForeignPublicKeyHash())
-				.bind("bitcoin_amount", tradeBotData.getBitcoinAmount())
+				.bind("foreign_amount", tradeBotData.getForeignAmount())
-				.bind("xprv58", tradeBotData.getXprv58())
+				.bind("foreign_key", tradeBotData.getForeignKey())
 				.bind("last_transaction_signature", tradeBotData.getLastTransactionSignature())
 				.bind("locktime_a", tradeBotData.getLockTimeA())
 				.bind("receiving_account_info", tradeBotData.getReceivingAccountInfo());

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

@@ -4,9 +4,12 @@ import java.sql.Connection;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Statement;
+import java.util.Arrays;
+import java.util.stream.Collectors;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.qortal.controller.tradebot.BitcoinACCTv1TradeBot;
 
 public class HSQLDBDatabaseUpdates {
 
@@ -609,6 +612,7 @@ public class HSQLDBDatabaseUpdates {
 
 				case 20:
 					// Trade bot
+					// See case 25 below for changes
 					stmt.execute("CREATE TABLE TradeBotStates (trade_private_key QortalKeySeed NOT NULL, trade_state TINYINT NOT NULL, "
 							+ "creator_address QortalAddress NOT NULL, at_address QortalAddress, updated_when BIGINT NOT NULL, qort_amount QortalAmount NOT NULL, "
 							+ "trade_native_public_key QortalPublicKey NOT NULL, trade_native_public_key_hash VARBINARY(32) NOT NULL, "
@@ -653,6 +657,35 @@ public class HSQLDBDatabaseUpdates {
 					stmt.execute("DROP TABLE IF EXISTS NextBlockHeight");
 					break;
 
+				case 25:
+					// Multiple blockchains, ACCTs and trade-bots
+					stmt.execute("ALTER TABLE TradeBotStates ADD COLUMN acct_name VARCHAR(40) BEFORE trade_state");
+					stmt.execute("UPDATE TradeBotStates SET acct_name = 'BitcoinACCTv1' WHERE acct_name IS NULL");
+					stmt.execute("ALTER TABLE TradeBotStates ALTER COLUMN acct_name SET NOT NULL");
+
+					stmt.execute("ALTER TABLE TradeBotStates ALTER COLUMN trade_state RENAME TO trade_state_value");
+
+					stmt.execute("ALTER TABLE TradeBotStates ADD COLUMN trade_state VARCHAR(40) BEFORE trade_state_value");
+					// Any existing values will be BitcoinACCTv1
+					StringBuilder updateTradeBotStatesSql = new StringBuilder(1024);
+					updateTradeBotStatesSql.append("UPDATE TradeBotStates SET (trade_state) = (")
+							.append("SELECT state_name FROM (VALUES ")
+							.append(
+									Arrays.stream(BitcoinACCTv1TradeBot.State.values())
+									.map(state -> String.format("(%d, '%s')", state.value, state.name()))
+									.collect(Collectors.joining(", ")))
+							.append(") AS BitcoinACCTv1States (state_value, state_name) ")
+							.append("WHERE state_value = trade_state_value)");
+					stmt.execute(updateTradeBotStatesSql.toString());
+					stmt.execute("ALTER TABLE TradeBotStates ALTER COLUMN trade_state SET NOT NULL");
+
+					stmt.execute("ALTER TABLE TradeBotStates ADD COLUMN foreign_blockchain VARCHAR(40) BEFORE trade_foreign_public_key");
+
+					stmt.execute("ALTER TABLE TradeBotStates ALTER COLUMN bitcoin_amount RENAME TO foreign_amount");
+
+					stmt.execute("ALTER TABLE TradeBotStates ALTER COLUMN xprv58 RENAME TO foreign_key");
+					break;
+
 				default:
 					// nothing to do
 					return false;

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

@@ -1,42 +1,55 @@
 package org.qortal.utils;
 
-public class Triple<T, U, V> {
+public class Triple<A, B, C> {
 
-	private T a;
+	@FunctionalInterface
-	private U b;
+	public interface TripleConsumer<A, B, C> {
-	private V c;
+		public void accept(A a, B b, C c);
+	}
+
+	private A a;
+	private B b;
+	private C c;
+
+	public static <A, B, C> Triple<A, B, C> valueOf(A a, B b, C c) {
+		return new Triple<>(a, b, c);
+	}
 
 	public Triple() {
 	}
 
-	public Triple(T a, U b, V c) {
+	public Triple(A a, B b, C c) {
 		this.a = a;
 		this.b = b;
 		this.c = c;
 	}
 
-	public void setA(T a) {
+	public void setA(A a) {
 		this.a = a;
 	}
 
-	public T getA() {
+	public A getA() {
 		return a;
 	}
 
-	public void setB(U b) {
+	public void setB(B b) {
 		this.b = b;
 	}
 
-	public U getB() {
+	public B getB() {
 		return b;
 	}
 
-	public void setC(V c) {
+	public void setC(C c) {
 		this.c = c;
 	}
 
-	public V getC() {
+	public C getC() {
 		return c;
 	}
 
+	public void consume(TripleConsumer<A, B, C> consumer) {
+		consumer.accept(this.a, this.b, this.c);
+	}
+
 }

src/test/java/org/qortal/test/crosschain/bitcoinv1/BitcoinACCTv1Tests.java

@@ -153,7 +153,7 @@ public class BitcoinACCTv1Tests extends Common {
 			assertTrue(atData.getIsFinished());
 
 			// AT should be in CANCELLED mode
-			CrossChainTradeData tradeData = BitcoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = BitcoinACCTv1.getInstance().populateTradeData(repository, atData);
 			assertEquals(AcctMode.CANCELLED, tradeData.mode);
 
 			// Check balances
@@ -212,7 +212,7 @@ public class BitcoinACCTv1Tests extends Common {
 			assertTrue(atData.getIsFinished());
 
 			// AT should be in CANCELLED mode
-			CrossChainTradeData tradeData = BitcoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = BitcoinACCTv1.getInstance().populateTradeData(repository, atData);
 			assertEquals(AcctMode.CANCELLED, tradeData.mode);
 		}
 	}
@@ -250,7 +250,7 @@ public class BitcoinACCTv1Tests extends Common {
 			describeAt(repository, atAddress);
 
 			ATData atData = repository.getATRepository().fromATAddress(atAddress);
-			CrossChainTradeData tradeData = BitcoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = BitcoinACCTv1.getInstance().populateTradeData(repository, atData);
 
 			// AT should be in TRADE mode
 			assertEquals(AcctMode.TRADING, tradeData.mode);
@@ -312,7 +312,7 @@ public class BitcoinACCTv1Tests extends Common {
 			describeAt(repository, atAddress);
 
 			ATData atData = repository.getATRepository().fromATAddress(atAddress);
-			CrossChainTradeData tradeData = BitcoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = BitcoinACCTv1.getInstance().populateTradeData(repository, atData);
 
 			// AT should still be in OFFER mode
 			assertEquals(AcctMode.OFFERING, tradeData.mode);
@@ -359,7 +359,7 @@ public class BitcoinACCTv1Tests extends Common {
 			assertTrue(atData.getIsFinished());
 
 			// AT should be in REFUNDED mode
-			CrossChainTradeData tradeData = BitcoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = BitcoinACCTv1.getInstance().populateTradeData(repository, atData);
 			assertEquals(AcctMode.REFUNDED, tradeData.mode);
 
 			// Test orphaning
@@ -415,7 +415,7 @@ public class BitcoinACCTv1Tests extends Common {
 			assertTrue(atData.getIsFinished());
 
 			// AT should be in REDEEMED mode
-			CrossChainTradeData tradeData = BitcoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = BitcoinACCTv1.getInstance().populateTradeData(repository, atData);
 			assertEquals(AcctMode.REDEEMED, tradeData.mode);
 
 			// Check balances
@@ -486,7 +486,7 @@ public class BitcoinACCTv1Tests extends Common {
 			assertFalse(atData.getIsFinished());
 
 			// AT should still be in TRADE mode
-			CrossChainTradeData tradeData = BitcoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = BitcoinACCTv1.getInstance().populateTradeData(repository, atData);
 			assertEquals(AcctMode.TRADING, tradeData.mode);
 
 			// Check balances
@@ -546,7 +546,7 @@ public class BitcoinACCTv1Tests extends Common {
 			assertFalse(atData.getIsFinished());
 
 			// AT should still be in TRADE mode
-			CrossChainTradeData tradeData = BitcoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = BitcoinACCTv1.getInstance().populateTradeData(repository, atData);
 			assertEquals(AcctMode.TRADING, tradeData.mode);
 
 			long expectedBalance = partnersInitialBalance - messageTransaction.getTransactionData().getFee();
@@ -568,7 +568,7 @@ public class BitcoinACCTv1Tests extends Common {
 			assertFalse(atData.getIsFinished());
 
 			// AT should still be in TRADE mode
-			tradeData = BitcoinACCTv1.populateTradeData(repository, atData);
+			tradeData = BitcoinACCTv1.getInstance().populateTradeData(repository, atData);
 			assertEquals(AcctMode.TRADING, tradeData.mode);
 
 			// Check balances
@@ -624,7 +624,7 @@ public class BitcoinACCTv1Tests extends Common {
 			assertFalse(atData.getIsFinished());
 
 			// AT should be in TRADING mode
-			CrossChainTradeData tradeData = BitcoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = BitcoinACCTv1.getInstance().populateTradeData(repository, atData);
 			assertEquals(AcctMode.TRADING, tradeData.mode);
 		}
 	}
@@ -747,7 +747,7 @@ public class BitcoinACCTv1Tests extends Common {
 
 	private void describeAt(Repository repository, String atAddress) throws DataException {
 		ATData atData = repository.getATRepository().fromATAddress(atAddress);
-		CrossChainTradeData tradeData = BitcoinACCTv1.populateTradeData(repository, atData);
+		CrossChainTradeData tradeData = BitcoinACCTv1.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();

src/test/java/org/qortal/test/crosschain/litecoinv1/LitecoinACCTv1Tests.java

@@ -151,7 +151,7 @@ public class LitecoinACCTv1Tests extends Common {
 			assertTrue(atData.getIsFinished());
 
 			// AT should be in CANCELLED mode
-			CrossChainTradeData tradeData = LitecoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = LitecoinACCTv1.getInstance().populateTradeData(repository, atData);
 			assertEquals(AcctMode.CANCELLED, tradeData.mode);
 
 			// Check balances
@@ -210,7 +210,7 @@ public class LitecoinACCTv1Tests extends Common {
 			assertTrue(atData.getIsFinished());
 
 			// AT should be in CANCELLED mode
-			CrossChainTradeData tradeData = LitecoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = LitecoinACCTv1.getInstance().populateTradeData(repository, atData);
 			assertEquals(AcctMode.CANCELLED, tradeData.mode);
 		}
 	}
@@ -248,7 +248,7 @@ public class LitecoinACCTv1Tests extends Common {
 			describeAt(repository, atAddress);
 
 			ATData atData = repository.getATRepository().fromATAddress(atAddress);
-			CrossChainTradeData tradeData = LitecoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = LitecoinACCTv1.getInstance().populateTradeData(repository, atData);
 
 			// AT should be in TRADE mode
 			assertEquals(AcctMode.TRADING, tradeData.mode);
@@ -310,7 +310,7 @@ public class LitecoinACCTv1Tests extends Common {
 			describeAt(repository, atAddress);
 
 			ATData atData = repository.getATRepository().fromATAddress(atAddress);
-			CrossChainTradeData tradeData = LitecoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = LitecoinACCTv1.getInstance().populateTradeData(repository, atData);
 
 			// AT should still be in OFFER mode
 			assertEquals(AcctMode.OFFERING, tradeData.mode);
@@ -357,7 +357,7 @@ public class LitecoinACCTv1Tests extends Common {
 			assertTrue(atData.getIsFinished());
 
 			// AT should be in REFUNDED mode
-			CrossChainTradeData tradeData = LitecoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = LitecoinACCTv1.getInstance().populateTradeData(repository, atData);
 			assertEquals(AcctMode.REFUNDED, tradeData.mode);
 
 			// Test orphaning
@@ -413,7 +413,7 @@ public class LitecoinACCTv1Tests extends Common {
 			assertTrue(atData.getIsFinished());
 
 			// AT should be in REDEEMED mode
-			CrossChainTradeData tradeData = LitecoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = LitecoinACCTv1.getInstance().populateTradeData(repository, atData);
 			assertEquals(AcctMode.REDEEMED, tradeData.mode);
 
 			// Check balances
@@ -484,7 +484,7 @@ public class LitecoinACCTv1Tests extends Common {
 			assertFalse(atData.getIsFinished());
 
 			// AT should still be in TRADE mode
-			CrossChainTradeData tradeData = LitecoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = LitecoinACCTv1.getInstance().populateTradeData(repository, atData);
 			assertEquals(AcctMode.TRADING, tradeData.mode);
 
 			// Check balances
@@ -544,7 +544,7 @@ public class LitecoinACCTv1Tests extends Common {
 			assertFalse(atData.getIsFinished());
 
 			// AT should still be in TRADE mode
-			CrossChainTradeData tradeData = LitecoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = LitecoinACCTv1.getInstance().populateTradeData(repository, atData);
 			assertEquals(AcctMode.TRADING, tradeData.mode);
 
 			long expectedBalance = partnersInitialBalance - messageTransaction.getTransactionData().getFee();
@@ -599,7 +599,7 @@ public class LitecoinACCTv1Tests extends Common {
 			assertFalse(atData.getIsFinished());
 
 			// AT should be in TRADING mode
-			CrossChainTradeData tradeData = LitecoinACCTv1.populateTradeData(repository, atData);
+			CrossChainTradeData tradeData = LitecoinACCTv1.getInstance().populateTradeData(repository, atData);
 			assertEquals(AcctMode.TRADING, tradeData.mode);
 		}
 	}
@@ -722,7 +722,7 @@ public class LitecoinACCTv1Tests extends Common {
 
 	private void describeAt(Repository repository, String atAddress) throws DataException {
 		ATData atData = repository.getATRepository().fromATAddress(atAddress);
-		CrossChainTradeData tradeData = LitecoinACCTv1.populateTradeData(repository, atData);
+		CrossChainTradeData tradeData = LitecoinACCTv1.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();