Added "allowConnectionsWithOlderPeerVersions" setting (default: true)

This controls whether to allow connections with peers below minPeerVersion.

If true, we won't sync with them but they can still sync with us, and will show in the peers list. This is the default, which allows older nodes to continue functioning, but prevents them from interfering with the sync behaviour of updated nodes.

If false, sync will be blocked both ways, and they will not appear in the peers list at all.

.gitignore

@@ -16,3 +16,6 @@
 /settings*.json
 /testchain.json
 /run-testnet.sh
+/.idea
+/qortal.iml
+*.DS_Store

AutoUpdates.md

@@ -1,5 +1,20 @@
 # Auto Updates
 
+## TL;DR: how-to
+
+* Prepare new release version (see way below for details)
+* Assuming you are in git 'master' branch, at HEAD
+* Shutdown local node if running
+* Build auto-update download: `tools/build-auto-update.sh` - uploads auto-update file into new git branch
+* Restart local node
+* Publish auto-update transaction using *private key* for **non-admin** member of "dev" group:
+	`tools/publish-auto-update.sh non-admin-dev-member-private-key-in-base58`
+* Wait for auto-update `ARBITRARY` transaction to be confirmed into a block
+* Have "dev" group admins 'approve' auto-update using `tools/approve-auto-update.sh`
+	This tool will prompt for *private key* of **admin** of "dev" group
+* A minimum number of admins are required for approval, and a minimum number of blocks must pass also.
+* Nodes will start to download, and apply, the update over the next 20 minutes or so (see CHECK_INTERVAL in AutoUpdate.java)
+
 ## Theory
 * Using a specific git commit (e.g. abcdef123) we produce a determinstic JAR with consistent hash.
 * To avoid issues with over-eager anti-virus / firewalls we obfuscate JAR using very simplistic XOR-based method.
@@ -25,8 +40,8 @@ The same method is used to obfuscate and de-obfuscate:
 
 ## Typical download locations
 The git SHA1 commit hash is used to replace `%s` in various download locations, e.g.:
-* https://github.com/QORT/qortal/raw/%s/qortal.update
-* https://raw.githubusercontent.com@151.101.16.133/QORT/qortal/%s/qortal.update
+* https://github.com/Qortal/qortal/raw/%s/qortal.update
+* https://raw.githubusercontent.com@151.101.16.133/Qortal/qortal/%s/qortal.update
 
 These locations are part of the org.qortal.settings.Settings class and can be overriden in settings.json like:
 ```
@@ -45,4 +60,12 @@ $ java -cp qortal.jar org.qortal.XorUpdate
 usage: XorUpdate <input-file> <output-file>
 $ java -cp qortal.jar org.qortal.XorUpdate qortal.jar qortal.update
 $
-```
+```
+
+## Preparing new release version
+
+* Shutdown local node
+* Modify `pom.xml` and increase version inside `<version>` tag
+* Commit new `pom.xml` and push to github, e.g. `git commit -m 'Bumped to v1.4.2' -- pom.xml; git push`
+* Tag this new commit with same version: `git tag v1.4.2`
+* Push tag up to github: `git push origin v1.4.2`

DATABASE.md

@@ -4,10 +4,10 @@ You can examine your node's database using [HSQLDB's "sqltool"](http://www.hsqld
 It's a good idea to install "rlwrap" (ReadLine wrapper) too as sqltool doesn't support command history/editing.
 
 Typical command line for sqltool would be:
-`rlwrap java -cp ${HSQLDB_JAR}:${SQLTOOL_JAR} org.hsqldb.cmdline.SqlTool --rcFile=${SQLTOOL_RC} qora`
+`rlwrap java -cp ${HSQLDB_JAR}:${SQLTOOL_JAR} org.hsqldb.cmdline.SqlTool --rcFile=${SQLTOOL_RC} qortal`
 
 `${HSQLDB_JAR}` should be set with pathname where Maven downloaded hsqldb, 
-typically `${HOME}/.m2/repository/org/hsqldb/hsqldb/2.5.0/hsqldb-2.5.0.jar`
+typically `${HOME}/.m2/repository/org/hsqldb/hsqldb/2.5.1/hsqldb-2.5.1.jar`
 
 `${SQLTOOL_JAR}` should be set with pathname where Maven downloaded sqltool,
 typically  `${HOME}/.m2/repository/org/hsqldb/sqltool/2.5.0/sqltool-2.5.0.jar`
@@ -25,10 +25,16 @@ Above `url` component `file:db/blockchain` assumes you will call `sqltool` from
 
 Another idea is to assign a shell alias in your `.bashrc` like:
 ```
-export HSQLDB_JAR=${HOME}/.m2/repository/org/hsqldb/hsqldb/2.5.0/hsqldb-2.5.0.jar
+export HSQLDB_JAR=${HOME}/.m2/repository/org/hsqldb/hsqldb/2.5.1/hsqldb-2.5.1.jar
 export SQLTOOL_JAR=${HOME}/.m2/repository/org/hsqldb/sqltool/2.5.0/sqltool-2.5.0.jar
 alias sqltool='rlwrap java -cp ${HSQLDB_JAR}:${SQLTOOL_JAR} org.hsqldb.cmdline.SqlTool --rcFile=${SQLTOOL_RC}'
 ```
 So you can simply type: `sqltool qortal`
 
 Don't forget to use `SHUTDOWN;` before exiting sqltool so that database files are closed cleanly.
+
+## Quick and dirty version
+
+With `sqltool-2.5.0.jar` and `qortal.jar` in current directory, and database in `db/`
+
+`java -cp qortal.jar:sqltool-2.5.0.jar org.hsqldb.cmdline.SqlTool --inlineRc=url=jdbc:hsqldb:file:db/blockchain`

README.md

@@ -9,4 +9,4 @@
 - Create basic *settings.json* file: `echo '{}' > settings.json`
 - Run JAR in same working directory as *settings.json*: `java -jar target/qortal-1.0.jar`
 - Wrap in shell script, add JVM flags, redirection, backgrounding, etc. as necessary.
-- Or use supplied example shell script: *run.sh*
+- Or use supplied example shell script: *start.sh*

TestNets.md

@@ -0,0 +1,69 @@
+# How to build a testnet
+
+## Create testnet blockchain config
+
+- You can begin by copying the mainnet blockchain config `src/main/resources/blockchain.json`
+- Insert `"isTestChain": true,` after the opening `{`
+- Modify testnet genesis block
+
+### Testnet genesis block
+
+- Set `timestamp` to a nearby future value, e.g. 15 mins from 'now'
+	This is to give yourself enough time to set up other testnet nodes
+- Retain the initial `ISSUE_ASSET` transactions!
+- Add `ACCOUNT_FLAGS` transactions with `"andMask": -1, "orMask": 1, "xorMask": 0` to create founders
+- Add at least one `REWARD_SHARE` transaction otherwise no-one can mint initial blocks!
+	You will need to calculate `rewardSharePublicKey` (and private key),
+	or make a new account on mainnet and use self-share key values
+- Add `ACCOUNT_LEVEL` transactions to set initial level of accounts as needed
+- Add `GENESIS` transactions to add QORT/LEGACY_QORA funds to accounts as needed
+
+## Testnet `settings.json`
+
+- Create a new `settings-test.json`
+- Make sure to add `"isTestNet": true,`
+- Make sure to reference testnet blockchain config file: `"blockchainConfig": "testchain.json",`
+- It is a good idea to use a separate database: `"repositoryPath": "db-testnet",`
+- You might also need to add `"bitcoinNet": "TEST3",` and `"litecoinNet": "TEST3",`
+
+## Other nodes
+
+- Copy `testchain.json` and `settings-test.json` to other nodes
+- Alternatively, you can run multiple nodes on the same machine by:
+	* Copying `settings-test.json` to `settings-test-1.json`
+	* Configure different `repositoryPath`
+	* Configure use of different ports:
+		+ `"apiPort": 22391,`
+		+ `"listenPort": 22392,`
+
+## Starting-up
+
+- Start up at least as many nodes as `minBlockchainPeers` (or adjust this value instead)
+- Probably best to perform API call `DELETE /peers/known`
+- Add other nodes via API call `POST /peers <peer-hostname-or-IP>`
+- Add minting private key to node(s) via API call `POST /admin/mintingaccounts <minting-private-key>`
+	This key must have corresponding `REWARD_SHARE` transaction in testnet genesis block
+- Wait for genesis block timestamp to pass
+- A node should mint block 2 approximately 60 seconds after genesis block timestamp
+- Other testnet nodes will sync *as long as there is at least `minBlockchainPeers` peers with an "up-to-date" chain`
+- You can also use API call `POST /admin/forcesync <connected-peer-IP-and-port>` on stuck nodes
+
+## Dealing with stuck chain
+
+Maybe your nodes have been offline and no-one has minted a recent testnet block.
+Your options are:
+
+- Start a new testnet from scratch
+- Fire up your testnet node(s)
+- Force one of your nodes to mint by:
+	+ Set a debugger breakpoint on Settings.getMinBlockchainPeers()
+	+ When breakpoint is hit, change `this.minBlockchainPeers` to zero, then continue
+- Once one of your nodes has minted blocks up to 'now', you can use "forcesync" on the other nodes
+
+## Tools
+
+- `qort` tool, but use `-t` option for default testnet API port (62391)
+- `qort` tool, but first set shell variable: `export BASE_URL=some-node-hostname-or-ip:port`
+- `qort` tool, but prepend with one-time shell variable: `BASE_URL=some-node-hostname-or-ip:port qort ......`
+- `peer-heights`, but use `-t` option, or `BASE_URL` shell variable as above
+

WindowsInstaller/Install Files/AppData/settings.json

@@ -0,0 +1,3 @@
+{
+  "apiDocumentationEnabled": true
+}

WindowsInstaller/Install Files/log4j2.properties

@@ -0,0 +1,70 @@
+rootLogger.level = info
+# On Windows, uncomment next line to set dirname:
+# property.dirname = ${sys:user.home}\\AppData\\Local\\qortal\\
+property.filename = ${sys:log4j2.filenameTemplate:-log.txt}
+
+rootLogger.appenderRef.console.ref = stdout
+rootLogger.appenderRef.rolling.ref = FILE
+
+# Suppress extraneous bitcoinj library output
+logger.bitcoinj.name = org.bitcoinj
+logger.bitcoinj.level = error
+
+# Override HSQLDB logging level to "warn" as too much is logged at "info"
+logger.hsqldb.name = hsqldb.db
+logger.hsqldb.level = warn
+
+# Support optional, per-session HSQLDB debugging
+logger.hsqldbRepository.name = org.qortal.repository.hsqldb
+logger.hsqldbRepository.level = debug
+
+# Suppress extraneous Jersey warning
+logger.jerseyInject.name = org.glassfish.jersey.internal.inject.Providers
+logger.jerseyInject.level = off
+
+# Suppress extraneous Jersey EOF 'errors' (actually remote peers disconnecting early)
+logger.jerseyEOF.name = org.glassfish.jersey.server.internal
+logger.jerseyEOF.level = off
+
+# Suppress extraneous Jetty entries
+# 2019-02-14 11:46:27 INFO  ContextHandler:851 - Started o.e.j.s.ServletContextHandler@6949e948{/,null,AVAILABLE}
+# 2019-02-14 11:46:27 INFO  AbstractConnector:289 - Started ServerConnector@50ad322b{HTTP/1.1,[http/1.1]}{0.0.0.0:9085}
+# 2019-02-14 11:46:27 INFO  Server:374 - jetty-9.4.11.v20180605; built: 2018-06-05T18:24:03.829Z; git: d5fc0523cfa96bfebfbda19606cad384d772f04c; jvm 1.8.0_181-b13
+# 2019-02-14 11:46:27 INFO  Server:411 - Started @2539ms
+logger.jetty.name = org.eclipse.jetty
+logger.jetty.level = warn
+# Even more extraneous Jetty output
+# 2019-01-26 02:18:10 WARN  ResourceService:718 - java.util.concurrent.TimeoutException: Idle timeout expired: 30000/30000 ms
+logger.jettyRS.name = org.eclipse.jetty.server.ResourceService
+logger.jettyRS.level = error
+
+# Suppress extraneous slf4j entries
+# 2019-02-14 11:46:27 INFO  log:193 - Logging initialized @1636ms to org.eclipse.jetty.util.log.Slf4jLog
+logger.slf4j.name = org.slf4j
+logger.slf4j.level = warn
+
+# Suppress extraneous Reflections entry
+# 2019-02-27 10:45:25 WARN  Reflections:179 - given scan urls are empty. set urls in the configuration
+logger.orgReflections.name = org.reflections.Reflections
+logger.orgReflections.level = off
+logger.sunReflections.name = sun.reflect.Reflection
+logger.sunReflections.level = off
+
+appender.console.type = Console
+appender.console.name = stdout
+appender.console.layout.type = PatternLayout
+appender.console.layout.pattern = %d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n
+appender.console.filter.threshold.type = ThresholdFilter
+appender.console.filter.threshold.level = error
+
+appender.rolling.type = RollingFile
+appender.rolling.name = FILE
+appender.rolling.layout.type = PatternLayout
+appender.rolling.layout.pattern = %d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n
+appender.rolling.filePattern = ${dirname:-}${filename}.%i
+appender.rolling.policy.type = SizeBasedTriggeringPolicy
+appender.rolling.policy.size = 4MB
+# Set the immediate flush to true (default)
+# appender.rolling.immediateFlush = true
+# Set the append to true (default), should not overwrite
+# appender.rolling.append=true

WindowsInstaller/Install Files/ntpcfg.bat

@@ -0,0 +1,33 @@
+@echo off
+
+:: BatchGotAdmin
+:-------------------------------------
+REM  --> Check for permissions
+>nul 2>&1 "%SYSTEMROOT%\system32\cacls.exe" "%SYSTEMROOT%\system32\config\system"
+
+REM --> If error flag set, we do not have admin.
+if '%errorlevel%' NEQ '0' (
+    echo Requesting administrative privileges...
+    goto UACPrompt
+) else ( goto gotAdmin )
+
+:UACPrompt
+    echo Set UAC = CreateObject^("Shell.Application"^) > "%temp%\getadmin.vbs"
+    echo UAC.ShellExecute "%~s0", "", "", "runas", 1 >> "%temp%\getadmin.vbs"
+
+    "%temp%\getadmin.vbs"
+    exit /B
+
+:gotAdmin
+    if exist "%temp%\getadmin.vbs" ( del "%temp%\getadmin.vbs" )
+    pushd "%CD%"
+    CD /D "%~dp0"
+:--------------------------------------
+
+net stop "Windows Time"
+
+w32tm /config "/manualpeerlist:pool.ntp.org 0.pool.ntp.org 1.pool.ntp.org 2.pool.ntp.org 3.pool.ntp.org cn.pool.ntp.org 0.cn.pool.ntp.org 1.cn.pool.ntp.org 2.cn.pool.ntp.org 3.cn.pool.ntp.org"
+
+net start "Windows Time"
+
+sc config w32time start= auto

WindowsInstaller/README.md

@@ -0,0 +1,26 @@
+# Windows installer
+
+## Prerequisites
+
+* AdvancedInstaller v16 or better, and enterprise licence if translations are required
+* Installed AdoptOpenJDK v11 64bit, full JDK *not* JRE
+
+## General build instructions
+
+If this is your first time opening the `qortal.aip` file then you might need to adjust
+configured paths, or create a dummy `D:` drive with the expected layout.
+
+Typical build procedure:
+
+* Overwrite the `qortal.jar` file in `Install-Files\`
+* Open AdvancedInstaller with qortal.aip file
+* If releasing a new version, change version number in:
+	+ "Product Information" side menu
+	+ "Product Details" side menu entry
+	+ "Product Details" tab in "Product Details" pane
+	+ "Product Version" entry box
+* Click away to a different side menu entry, e.g. "Resources" -> "Files and Folders"
+* You should be prompted whether to generate a new product key, click "Generate New"
+* Click "Build" button
+* New EXE should be generated in `Qortal-SetupFiles\` folder with correct version number
+

WindowsInstaller/dictionary.ail

@@ -0,0 +1,117 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<DICTIONARY type="multilanguage">
+  <!-- Control table -->
+  <ENTRY id="Control.Text.CustomizeDataPathDlg#Description">
+    <STRING lang="en" value="Do you want to store the blockchain, and other data, in a specific folder?"/>
+	<STRING lang="ru" value="Вы можете выбрать место хранения блокчейна и других данных."/>
+    <STRING lang="zh" value="你想把区块链数据存放在一个特定的文件夹吗？"/>
+    <STRING lang="zh_TW" value="你想把区块链数据存放在一个特定的文件夹吗？"/>
+  </ENTRY>
+  <ENTRY id="Control.Text.CustomizeDataPathDlg#Text">
+    <STRING lang="en" value="Select one of the options below, then click &quot;Next&quot;."/>
+	<STRING lang="ru" value="Выберите один из вариантов ниже, затем нажмите Далее"/>
+    <STRING lang="zh" value="请选择，然后“下一步”"/>
+    <STRING lang="zh_TW" value="请选择，然后“下一步”"/>
+  </ENTRY>
+  <ENTRY id="Control.Text.CustomizeDataPathDlg#Title">
+    <STRING lang="en" value="Choose Custom Data Storage Folder?"/>
+	<STRING lang="ru" value="Выберите место хранения данных."/>
+    <STRING lang="zh" value="选择数据保存的文件夹?"/>
+    <STRING lang="zh_TW" value="选择数据保存的文件夹?"/>
+  </ENTRY>
+  <ENTRY id="Control.Text.CustomizeDbDlg#Description">
+    <STRING lang="en" value="Do you want to store the blockchain, and other data, in a specific folder?"/>
+	<STRING lang="ru" value="Вы можете выбрать место хранения блокчейна и других данных."/>
+    <STRING lang="zh" value="Do you want to store the blockchain, and other data, in a specific folder?"/>
+    <STRING lang="zh_TW" value="Do you want to store the blockchain, and other data, in a specific folder?"/>
+  </ENTRY>
+  <ENTRY id="Control.Text.CustomizeDbDlg#Title">
+    <STRING lang="en" value="Choose Custom Data Storage Folder?"/>
+	<STRING lang="ru" value="Выберите место хранения данных."/>
+    <STRING lang="zh" value="Choose Custom Data Storage Folder?"/>
+    <STRING lang="zh_TW" value="Choose Custom Data Storage Folder?"/>
+  </ENTRY>
+  <ENTRY id="Control.Text.DataFolderDlg#Description">
+    <STRING lang="en" value="This is the folder where the blockchain, and other data, will be stored."/>
+	<STRING lang="ru" value="Это папка, в которой будет храниться блокчейн и другие данные."/>
+    <STRING lang="zh" value="这里是区块链及其它数据存放的文件夹"/>
+    <STRING lang="zh_TW" value="这里是区块链及其它数据存放的文件夹"/>
+  </ENTRY>
+  <ENTRY id="Control.Text.DataFolderDlg#Text">
+    <STRING lang="en" value="To store data in this folder, click &quot;[Text_Next]&quot;. To store data in a different folder, enter it below or click &quot;Browse&quot;."/>
+	<STRING lang="ru" value="Чтобы сохранить данные в этой папке, нажмите &quot;[Text_Next]&quot;. Чтобы сохранить данные в другой папке, введите ее ниже или нажмите &quot;Обзор&quot;."/>
+    <STRING lang="zh" value="如果存放在这个文件夹，点 “下一步”。如果存放在其它位置，请选择“浏览”。"/>
+    <STRING lang="zh_TW" value="如果存放在这个文件夹，点 “下一步”。如果存放在其它位置，请选择“浏览”。"/>
+  </ENTRY>
+  <ENTRY id="Control.Text.DataFolderDlg#Title">
+    <STRING lang="en" value="Select Data Storage Folder"/>
+	<STRING lang="ru" value="Выберите папку для хранения данных"/>
+    <STRING lang="zh" value="请选择文件存储地方"/>
+    <STRING lang="zh_TW" value="请选择文件存储地方"/>
+  </ENTRY>
+  <ENTRY id="Control.Text.DbFolderDlg#Description">
+    <STRING lang="en" value="This is the folder where the blockchain, and other data, will be stored."/>
+	<STRING lang="ru" value="Это папка, в которой будет храниться блокчейн и другие данные."/>
+    <STRING lang="zh" value="This is the folder where the blockchain, and other data, will be stored."/>
+    <STRING lang="zh_TW" value="This is the folder where the blockchain, and other data, will be stored."/>
+  </ENTRY>
+  <ENTRY id="Control.Text.DbFolderDlg#Title">
+    <STRING lang="en" value="Select Data Storage Folder"/>
+	<STRING lang="ru" value="Выберите папку для хранения данных"/>
+    <STRING lang="zh" value="请选择文件存储地方"/>
+    <STRING lang="zh_TW" value="请选择文件存储地方"/>
+  </ENTRY>
+  <ENTRY id="Control.Text.NTPDialog#Description">
+    <STRING lang="en" value="Reconfigure Windows for more accurate time?"/>
+	<STRING lang="ru" value="Настроить синхронизацию времени системы Windows?"/>
+    <STRING lang="zh" value="重新配置Windows以获得更准确的时间？"/>
+  </ENTRY>
+  <ENTRY id="Control.Text.NTPDialog#Text_1">
+    <STRING lang="en" value="An accurate Windows clock is required to connect to the [ProductName] network and make transactions."/>
+	<STRING lang="ru" value="Для подключения к сети Qortal и совершения транзакций требуется точная настройка времени Windows"/>
+    <STRING lang="zh" value="需要准确的Windows时钟才能连接到[ProductName]网络并进行交易。"/>
+  </ENTRY>
+  <ENTRY id="Control.Text.NTPDialog#Text_2">
+    <STRING lang="en" value="Select one of the options below, then click &quot;Next&quot;."/>
+	<STRING lang="ru" value="Выберите один из вариантов ниже, затем нажмите"/>
+    <STRING lang="zh" value="请选择，然后“下一步”"/>
+  </ENTRY>
+  <ENTRY id="Control.Text.NTPDialog#Text_3">
+    <STRING lang="en" value="Your computer&apos;s clock needs to be accurate to within 0.5 seconds."/>
+	<STRING lang="ru" value="Точность времени вашего компьютера должна составлять 0.5 секунд."/>
+    <STRING lang="zh" value="您的计算机时钟需要准确到0.5秒内。"/>
+  </ENTRY>
+  <ENTRY id="Control.Text.NTPDialog#Title">
+    <STRING lang="en" value="Windows clock accuracy"/>
+	<STRING lang="ru" value="Настройка времени системы Windows"/>
+    <STRING lang="zh" value="Windows 时钟精度"/>
+  </ENTRY>
+  <ENTRY id="Control.Text.VerifyRemoveDlg#RemoveBlockchainCheckbox">
+    <STRING lang="en" value="Remove downloaded blockchain and other data"/>
+	<STRING lang="ru" value="Удалить загруженный блокчейн и другие данные"/>
+    <STRING lang="zh" value="删除您下载的区块链"/>
+  </ENTRY>
+  <!-- RadioButton table -->
+  <ENTRY id="RadioButton.Text.CUSTOM_DB_BOOL#choose">
+    <STRING lang="en" value="Choose custom data storage folder..."/>
+	<STRING lang="ru" value="Выбрать папку для хранения данных..."/>
+    <STRING lang="zh" value="选择特定的文件夹存储"/>
+    <STRING lang="zh_TW" value="选择特定的文件夹存储"/>
+  </ENTRY>
+  <ENTRY id="RadioButton.Text.CUSTOM_DB_BOOL#default">
+    <STRING lang="en" value="Use default location "/>
+	<STRING lang="ru" value="Использовать папку по умолчанию"/>
+    <STRING lang="zh" value="使用默认存储地点"/>
+    <STRING lang="zh_TW" value="使用默认存储地点"/>
+  </ENTRY>
+  <ENTRY id="RadioButton.Text.RECONFIG_NTP#1">
+    <STRING lang="en" value="Yes, configure Windows to use internet time servers (Recommended)"/>
+	<STRING lang="ru" value="Да, настроить синхронизацию времени Windows (Рекомендуется)"/>
+    <STRING lang="zh" value="是，将Windows配置为使用多个Internet时间服务器 (推荐的)"/>
+  </ENTRY>
+  <ENTRY id="RadioButton.Text.RECONFIG_NTP#2">
+    <STRING lang="en" value="No, I will manage clock accuracy myself"/>
+	<STRING lang="ru" value="Нет, я сам буду управлять настройками часов"/>
+    <STRING lang="zh" value="不，我会自己管理时钟精度。"/>
+  </ENTRY>
+</DICTIONARY>

lib/org/ciyam/AT/1.3.7/AT-1.3.7.pom

@@ -4,6 +4,6 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>org.ciyam</groupId>
   <artifactId>AT</artifactId>
-  <version>1.3.4</version>
+  <version>1.3.7</version>
   <description>POM was created from install:install-file</description>
 </project>

lib/org/ciyam/AT/1.3.8/AT-1.3.8.pom

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>org.ciyam</groupId>
+  <artifactId>AT</artifactId>
+  <version>1.3.8</version>
+  <description>POM was created from install:install-file</description>
+</project>

lib/org/ciyam/AT/maven-metadata-local.xml

@@ -3,10 +3,14 @@
   <groupId>org.ciyam</groupId>
   <artifactId>AT</artifactId>
   <versioning>
-    <release>1.3.4</release>
+    <release>1.3.8</release>
     <versions>
       <version>1.3.4</version>
+      <version>1.3.5</version>
+      <version>1.3.6</version>
+      <version>1.3.7</version>
+      <version>1.3.8</version>
     </versions>
-    <lastUpdated>20200414162728</lastUpdated>
+    <lastUpdated>20200925114415</lastUpdated>
   </versioning>
 </metadata>

pom.xml

@@ -3,21 +3,22 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>org.qortal</groupId>
 	<artifactId>qortal</artifactId>
-	<version>1.2.0</version>
+	<version>1.5.1</version>
 	<packaging>jar</packaging>
 	<properties>
-		<bitcoinj.version>0.15.5</bitcoinj.version>
+		<skipTests>true</skipTests>
+		<altcoinj.version>bf9fb80</altcoinj.version>
+		<bitcoinj.version>0.15.6</bitcoinj.version>
 		<bouncycastle.version>1.64</bouncycastle.version>
 		<build.timestamp>${maven.build.timestamp}</build.timestamp>
-		<ciyam-at.version>1.3.4</ciyam-at.version>
+		<ciyam-at.version>1.3.8</ciyam-at.version>
 		<commons-net.version>3.6</commons-net.version>
 		<commons-text.version>1.8</commons-text.version>
 		<dagger.version>1.2.2</dagger.version>
 		<guava.version>28.1-jre</guava.version>
-		<hsqldb.version>2.5.0-fixed</hsqldb.version>
-		<hsqldb-sqltool.version>2.5.0</hsqldb-sqltool.version>
+		<hsqldb.version>2.5.1</hsqldb.version>
 		<jersey.version>2.29.1</jersey.version>
-		<jetty.version>9.4.22.v20191022</jetty.version>
+		<jetty.version>9.4.29.v20200521</jetty.version>
 		<log4j.version>2.12.1</log4j.version>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 		<slf4j.version>1.7.12</slf4j.version>
@@ -199,6 +200,10 @@
 							<pattern>org.qortal.api.model**</pattern>
 							<template>${project.build.sourceDirectory}/org/qortal/data/package-info.java</template>
 						</package>
+						<package>
+							<pattern>org.qortal.api.model.**</pattern>
+							<template>${project.build.sourceDirectory}/org/qortal/data/package-info.java</template>
+						</package>
 					</packages>
 					<outputDirectory>${project.build.directory}/generated-sources/package-info</outputDirectory>
 				</configuration>
@@ -313,6 +318,14 @@
 					</execution>
 				</executions>
 			</plugin>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-surefire-plugin</artifactId>
+				<version>2.22.2</version>
+				<configuration>
+					<skipTests>${skipTests}</skipTests>
+				</configuration>
+			</plugin>
 		</plugins>
 		<pluginManagement>
 			<plugins>
@@ -375,6 +388,11 @@
 			<name>project</name>
 			<url>file:${project.basedir}/lib</url>
 		</repository>
+		<!-- jitpack for build-on-demand of altcoinj -->
+		<repository>
+			<id>jitpack.io</id>
+			<url>https://jitpack.io</url>
+		</repository>
 	</repositories>
 	<dependencies>
 		<!-- https://mvnrepository.com/artifact/org.codehaus.mojo/build-helper-maven-plugin -->
@@ -397,12 +415,6 @@
 			<artifactId>hsqldb</artifactId>
 			<version>${hsqldb.version}</version>
 		</dependency>
-		<dependency>
-			<groupId>org.hsqldb</groupId>
-			<artifactId>sqltool</artifactId>
-			<version>${hsqldb-sqltool.version}</version>
-			<scope>test</scope>
-		</dependency>
 		<!-- CIYAM AT (automated transactions) -->
 		<dependency>
 			<groupId>org.ciyam</groupId>
@@ -415,6 +427,12 @@
 			<artifactId>bitcoinj-core</artifactId>
 			<version>${bitcoinj.version}</version>
 		</dependency>
+		<!-- For Litecoin, etc. support, requires bitcoinj -->
+		<dependency>
+			<groupId>com.github.jjos2372</groupId>
+			<artifactId>altcoinj</artifactId>
+			<version>${altcoinj.version}</version>
+		</dependency>
 		<!-- Utilities -->
 		<dependency>
 			<groupId>com.googlecode.json-simple</groupId>

run.sh

@@ -1,51 +0,0 @@
-#!/bin/sh
-
-# There's no need to run as root, so don't allow it, for security reasons
-if [ "$USER" = "root" ]; then
-	echo "Please su to non-root user before running"
-	exit
-fi
-
-# Validate Java is installed and the minimum version is available
-MIN_JAVA_VER='11'
-
-if command -v java > /dev/null 2>&1; then
-    version=$(java -version 2>&1 | awk -F '"' '/version/ {print $2}')
-    version=$(echo $version | cut -d'.' -f1,2)
-    if [ `echo "${version}>=${MIN_JAVA_VER}" | bc` -eq 1 ]; then
-        echo 'Passed Java version check'
-    else
-        echo 'Please upgrade your Java to version 11 or greater'
-        exit 1
-    fi
-else
-  echo 'Java is not available, please install Java 11 or greater'
-  exit 1
-fi
-
-# No qortal.jar but we have a Maven built one?
-# Be helpful and copy across to correct location
-if [ ! -e qortal.jar -a -f target/qortal*.jar ]; then
-	echo "Copying Maven-built Qortal JAR to correct pathname"
-	cp target/qortal*.jar qortal.jar
-fi
-
-# Limits Java JVM stack size and maximum heap usage.
-# Comment out for bigger systems, e.g. non-routers
-# or when API documentation is enabled
-# JVM_MEMORY_ARGS="-Xss256k -Xmx128m"
-
-# Although java.net.preferIPv4Stack is supposed to be false
-# by default in Java 11, on some platforms (e.g. FreeBSD 12),
-# it is overriden to be true by default. Hence we explicitly
-# set it to true to obtain desired behaviour.
-nohup nice -n 20 java \
-	-Djava.net.preferIPv4Stack=false \
-	-XX:NativeMemoryTracking=summary \
-	${JVM_MEMORY_ARGS} \
-	-jar qortal.jar \
-	1>run.log 2>&1 &
-
-# Save backgrounded process's PID
-echo $! > run.pid
-echo qortal running as pid $!

run.sh

@@ -0,0 +1 @@
+start.sh

src/main/java/org/hsqldb/jdbc/HSQLDBPool.java

@@ -21,18 +21,28 @@ public class HSQLDBPool extends JDBCPool {
 	public Connection tryConnection() throws SQLException {
 		for (int i = 0; i < states.length(); i++) {
 			if (states.compareAndSet(i, RefState.available, RefState.allocated)) {
-				return connections[i].getConnection();
+				JDBCPooledConnection pooledConnection = connections[i];
+
+				if (pooledConnection == null)
+					// Probably shutdown situation
+					return null;
+
+				return pooledConnection.getConnection();
 			}
 
 			if (states.compareAndSet(i, RefState.empty, RefState.allocated)) {
 				try {
-					JDBCPooledConnection connection = (JDBCPooledConnection) source.getPooledConnection();
+					JDBCPooledConnection pooledConnection = (JDBCPooledConnection) source.getPooledConnection();
 
-					connection.addConnectionEventListener(this);
-					connection.addStatementEventListener(this);
-					connections[i] = connection;
+					if (pooledConnection == null)
+						// Probably shutdown situation
+						return null;
 
-					return connections[i].getConnection();
+					pooledConnection.addConnectionEventListener(this);
+					pooledConnection.addStatementEventListener(this);
+					connections[i] = pooledConnection;
+
+					return pooledConnection.getConnection();
 				} catch (SQLException e) {
 					states.set(i, RefState.empty);
 				}

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

@@ -35,6 +35,8 @@ public class ApplyUpdate {
 	private static final String JAR_FILENAME = AutoUpdate.JAR_FILENAME;
 	private static final String NEW_JAR_FILENAME = AutoUpdate.NEW_JAR_FILENAME;
 	private static final String WINDOWS_EXE_LAUNCHER = "qortal.exe";
+	private static final String JAVA_TOOL_OPTIONS_NAME = "JAVA_TOOL_OPTIONS";
+	private static final String JAVA_TOOL_OPTIONS_VALUE = "-XX:MaxRAMFraction=4";
 
 	private static final long CHECK_INTERVAL = 10 * 1000L; // ms
 	private static final int MAX_ATTEMPTS = 12;
@@ -65,17 +67,19 @@ public class ApplyUpdate {
 	}
 
 	private static boolean shutdownNode() {
-		String BASE_URI = "http://localhost:" + Settings.getInstance().getApiPort() + "/";
-		LOGGER.info(String.format("Shutting down node using API via %s", BASE_URI));
+		String baseUri = "http://localhost:" + Settings.getInstance().getApiPort() + "/";
+		LOGGER.info(() -> String.format("Shutting down node using API via %s", baseUri));
 
 		int attempt;
 		for (attempt = 0; attempt < MAX_ATTEMPTS; ++attempt) {
-			LOGGER.info(String.format("Attempt #%d out of %d to shutdown node", attempt + 1, MAX_ATTEMPTS));
-			String response = ApiRequest.perform(BASE_URI + "admin/stop", null);
+			final int attemptForLogging = attempt;
+			LOGGER.info(() -> String.format("Attempt #%d out of %d to shutdown node", attemptForLogging + 1, MAX_ATTEMPTS));
+			String response = ApiRequest.perform(baseUri + "admin/stop", null);
 			if (response == null)
-				break;
+				// No response - consider node shut down
+				return true;
 
-			LOGGER.info(String.format("Response from API: %s", response));
+			LOGGER.info(() -> String.format("Response from API: %s", response));
 
 			try {
 				Thread.sleep(CHECK_INTERVAL);
@@ -99,19 +103,20 @@ public class ApplyUpdate {
 		Path newJar = Paths.get(NEW_JAR_FILENAME);
 
 		if (!Files.exists(newJar)) {
-			LOGGER.warn(String.format("Replacement JAR '%s' not found?", newJar));
+			LOGGER.warn(() -> String.format("Replacement JAR '%s' not found?", newJar));
 			return;
 		}
 
 		int attempt;
 		for (attempt = 0; attempt < MAX_ATTEMPTS; ++attempt) {
-			LOGGER.info(String.format("Attempt #%d out of %d to replace JAR", attempt + 1, MAX_ATTEMPTS));
+			final int attemptForLogging = attempt;
+			LOGGER.info(() -> String.format("Attempt #%d out of %d to replace JAR", attemptForLogging + 1, MAX_ATTEMPTS));
 
 			try {
 				Files.copy(newJar, realJar, StandardCopyOption.REPLACE_EXISTING);
 				break;
 			} catch (IOException e) {
-				LOGGER.info(String.format("Unable to replace JAR: %s", e.getMessage()));
+				LOGGER.info(() -> String.format("Unable to replace JAR: %s", e.getMessage()));
 
 				// Try again
 			}
@@ -119,6 +124,7 @@ public class ApplyUpdate {
 			try {
 				Thread.sleep(CHECK_INTERVAL);
 			} catch (InterruptedException e) {
+				LOGGER.warn("Ignoring interrupt...");
 				// Doggedly retry
 			}
 		}
@@ -129,13 +135,13 @@ public class ApplyUpdate {
 
 	private static void restartNode(String[] args) {
 		String javaHome = System.getProperty("java.home");
-		LOGGER.info(String.format("Java home: %s", javaHome));
+		LOGGER.info(() -> String.format("Java home: %s", javaHome));
 
 		Path javaBinary = Paths.get(javaHome, "bin", "java");
-		LOGGER.info(String.format("Java binary: %s", javaBinary));
+		LOGGER.info(() -> String.format("Java binary: %s", javaBinary));
 
 		Path exeLauncher = Paths.get(WINDOWS_EXE_LAUNCHER);
-		LOGGER.info(String.format("Windows EXE launcher: %s", exeLauncher));
+		LOGGER.info(() -> String.format("Windows EXE launcher: %s", exeLauncher));
 
 		List<String> javaCmd;
 		if (Files.exists(exeLauncher)) {
@@ -156,9 +162,16 @@ public class ApplyUpdate {
 		}
 
 		try {
-			LOGGER.info(String.format("Restarting node with: %s", String.join(" ", javaCmd)));
+			LOGGER.info(() -> String.format("Restarting node with: %s", String.join(" ", javaCmd)));
 
-			new ProcessBuilder(javaCmd).start();
+			ProcessBuilder processBuilder = new ProcessBuilder(javaCmd);
+
+			if (Files.exists(exeLauncher)) {
+				LOGGER.info(() -> String.format("Setting env %s to %s", JAVA_TOOL_OPTIONS_NAME, JAVA_TOOL_OPTIONS_VALUE));
+				processBuilder.environment().put(JAVA_TOOL_OPTIONS_NAME, JAVA_TOOL_OPTIONS_VALUE);
+			}
+
+			processBuilder.start();
 		} catch (IOException e) {
 			LOGGER.error(String.format("Failed to restart node (BAD): %s", e.getMessage()));
 		}

src/main/java/org/qortal/RepositoryMaintenance.java

@@ -0,0 +1,75 @@
+package org.qortal;
+
+import java.security.Security;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.bouncycastle.jce.provider.BouncyCastleProvider;
+import org.bouncycastle.jsse.provider.BouncyCastleJsseProvider;
+import org.qortal.controller.Controller;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryFactory;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.repository.hsqldb.HSQLDBRepositoryFactory;
+import org.qortal.settings.Settings;
+
+public class RepositoryMaintenance {
+
+	static {
+		// This must go before any calls to LogManager/Logger
+		System.setProperty("java.util.logging.manager", "org.apache.logging.log4j.jul.LogManager");
+	}
+
+	private static final Logger LOGGER = LogManager.getLogger(RepositoryMaintenance.class);
+
+	public static void main(String[] args) {
+		LOGGER.info("Repository maintenance starting up...");
+
+		Security.insertProviderAt(new BouncyCastleProvider(), 0);
+		Security.insertProviderAt(new BouncyCastleJsseProvider(), 1);
+
+		// Load/check settings, which potentially sets up blockchain config, etc.
+		try {
+			if (args.length > 0)
+				Settings.fileInstance(args[0]);
+			else
+				Settings.getInstance();
+		} catch (Throwable t) {
+			LOGGER.error("Settings file error: " + t.getMessage());
+			System.exit(2);
+		}
+
+		LOGGER.info("Opening repository");
+		try {
+			RepositoryFactory repositoryFactory = new HSQLDBRepositoryFactory(Controller.getRepositoryUrl());
+			RepositoryManager.setRepositoryFactory(repositoryFactory);
+		} catch (DataException e) {
+			// If exception has no cause then repository is in use by some other process.
+			if (e.getCause() == null) {
+				LOGGER.info("Repository in use by another process?");
+			} else {
+				LOGGER.error("Unable to start repository", e);
+			}
+
+			System.exit(1);
+		}
+
+		LOGGER.info("Starting repository periodic maintenance. This can take a while...");
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			repository.performPeriodicMaintenance();
+
+			LOGGER.info("Repository periodic maintenance completed");
+		} catch (DataException e) {
+			LOGGER.error("Repository periodic maintenance failed", e);
+		}
+
+		try {
+			LOGGER.info("Shutting down repository");
+			RepositoryManager.closeRepositoryFactory();
+		} catch (DataException e) {
+			LOGGER.error("Error occurred while shutting down repository", e);
+		}
+	}
+
+}

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, 402),
 	// 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
-	BTC_NETWORK_ISSUE(1201, 500),
-	BTC_BALANCE_ISSUE(1202, 422),
-	BTC_TOO_SOON(1203, 422);
+	// Foreign blockchain
+	FOREIGN_BLOCKCHAIN_NETWORK_ISSUE(1201, 500),
+	FOREIGN_BLOCKCHAIN_BALANCE_ISSUE(1202, 402),
+	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/ApiErrorHandler.java

@@ -3,6 +3,7 @@ package org.qortal.api;
 import java.io.IOException;
 
 import javax.servlet.RequestDispatcher;
+import javax.servlet.ServletException;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
@@ -17,7 +18,7 @@ public class ApiErrorHandler extends ErrorHandler {
 	private static final Logger LOGGER = LogManager.getLogger(ApiErrorHandler.class);
 
 	@Override
-	public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException {
+	public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
 		if (Settings.getInstance().isApiLoggingEnabled()) {
 			String requestURI = request.getRequestURI();
 

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

@@ -18,9 +18,9 @@ import org.eclipse.jetty.http.HttpVersion;
 import org.eclipse.jetty.rewrite.handler.RedirectPatternRule;
 import org.eclipse.jetty.rewrite.handler.RewriteHandler;
 import org.eclipse.jetty.server.CustomRequestLog;
+import org.eclipse.jetty.server.DetectorConnectionFactory;
 import org.eclipse.jetty.server.HttpConfiguration;
 import org.eclipse.jetty.server.HttpConnectionFactory;
-import org.eclipse.jetty.server.OptionalSslConnectionFactory;
 import org.eclipse.jetty.server.RequestLog;
 import org.eclipse.jetty.server.RequestLogWriter;
 import org.eclipse.jetty.server.SecureRequestCustomizer;
@@ -43,6 +43,9 @@ import org.qortal.api.websocket.ActiveChatsWebSocket;
 import org.qortal.api.websocket.AdminStatusWebSocket;
 import org.qortal.api.websocket.BlocksWebSocket;
 import org.qortal.api.websocket.ChatMessagesWebSocket;
+import org.qortal.api.websocket.PresenceWebSocket;
+import org.qortal.api.websocket.TradeBotWebSocket;
+import org.qortal.api.websocket.TradeOffersWebSocket;
 import org.qortal.settings.Settings;
 
 public class ApiService {
@@ -113,8 +116,7 @@ public class ApiService {
 				SslConnectionFactory sslConnectionFactory = new SslConnectionFactory(sslContextFactory, HttpVersion.HTTP_1_1.asString());
 
 				ServerConnector portUnifiedConnector = new ServerConnector(this.server,
-						new OptionalSslConnectionFactory(sslConnectionFactory, HttpVersion.HTTP_1_1.asString()),
-						sslConnectionFactory,
+						new DetectorConnectionFactory(sslConnectionFactory),
 						httpConnectionFactory);
 				portUnifiedConnector.setHost(Settings.getInstance().getBindAddress());
 				portUnifiedConnector.setPort(Settings.getInstance().getApiPort());
@@ -197,6 +199,9 @@ public class ApiService {
 			context.addServlet(BlocksWebSocket.class, "/websockets/blocks");
 			context.addServlet(ActiveChatsWebSocket.class, "/websockets/chat/active/*");
 			context.addServlet(ChatMessagesWebSocket.class, "/websockets/chat/messages");
+			context.addServlet(TradeOffersWebSocket.class, "/websockets/crosschain/tradeoffers");
+			context.addServlet(TradeBotWebSocket.class, "/websockets/crosschain/tradebot");
+			context.addServlet(PresenceWebSocket.class, "/websockets/presence");
 
 			// Start server
 			this.server.start();

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

@@ -5,10 +5,20 @@ import java.net.UnknownHostException;
 
 import javax.servlet.http.HttpServletRequest;
 
-public class Security {
+import org.qortal.settings.Settings;
+
+public abstract class Security {
+
+	public static final String API_KEY_HEADER = "X-API-KEY";
 
-	// TODO: replace with proper authentication
 	public static void checkApiCallAllowed(HttpServletRequest request) {
+		String expectedApiKey = Settings.getInstance().getApiKey();
+		String passedApiKey = request.getHeader(API_KEY_HEADER);
+
+		if ((expectedApiKey != null && !expectedApiKey.equals(passedApiKey)) ||
+				(passedApiKey != null && !passedApiKey.equals(expectedApiKey)))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.UNAUTHORIZED);
+
 		InetAddress remoteAddr;
 		try {
 			remoteAddr = InetAddress.getByName(request.getRemoteAddr());
@@ -19,4 +29,5 @@ public class Security {
 		if (!remoteAddr.isLoopbackAddress())
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.UNAUTHORIZED);
 	}
+
 }

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

@@ -1,5 +1,6 @@
 package org.qortal.api.model;
 
+import java.util.Collections;
 import java.util.EnumMap;
 import java.util.Map;
 
@@ -13,17 +14,61 @@ import org.qortal.transaction.Transaction.TransactionType;
 @XmlAccessorType(XmlAccessType.FIELD)
 public class ActivitySummary {
 
-	public int blockCount;
-	public int transactionCount;
-	public int assetsIssued;
-	public int namesRegistered;
+	private int blockCount;
+	private int assetsIssued;
+	private int namesRegistered;
 
 	// Assuming TransactionType values are contiguous so 'length' equals count
 	@XmlJavaTypeAdapter(TransactionCountMapXmlAdapter.class)
-	public Map<TransactionType, Integer> transactionCountByType = new EnumMap<>(TransactionType.class);
+	private Map<TransactionType, Integer> transactionCountByType = new EnumMap<>(TransactionType.class);
+	private int totalTransactionCount = 0;
 
 	public ActivitySummary() {
 		// Needed for JAXB
 	}
 
+	public int getBlockCount() {
+		return this.blockCount;
+	}
+
+	public void setBlockCount(int blockCount) {
+		this.blockCount = blockCount;
+	}
+
+	public int getTotalTransactionCount() {
+		return this.totalTransactionCount;
+	}
+
+	public int getAssetsIssued() {
+		return this.assetsIssued;
+	}
+
+	public void setAssetsIssued(int assetsIssued) {
+		this.assetsIssued = assetsIssued;
+	}
+
+	public int getNamesRegistered() {
+		return this.namesRegistered;
+	}
+
+	public void setNamesRegistered(int namesRegistered) {
+		this.namesRegistered = namesRegistered;
+	}
+
+	public Map<TransactionType, Integer> getTransactionCountByType() {
+		return Collections.unmodifiableMap(this.transactionCountByType);
+	}
+
+	public void setTransactionCountByType(TransactionType transactionType, int transactionCount) {
+		this.transactionCountByType.put(transactionType, transactionCount);
+
+		this.totalTransactionCount = this.transactionCountByType.values().stream().mapToInt(Integer::intValue).sum();
+	}
+
+	public void setTransactionCountByType(Map<TransactionType, Integer> transactionCountByType) {
+		this.transactionCountByType = new EnumMap<>(transactionCountByType);
+
+		this.totalTransactionCount = this.transactionCountByType.values().stream().mapToInt(Integer::intValue).sum();
+	}
+
 }

src/main/java/org/qortal/api/model/CrossChainBitcoinP2SHStatus.java

@@ -1,31 +0,0 @@
-package org.qortal.api.model;
-
-import java.math.BigDecimal;
-
-import javax.xml.bind.annotation.XmlAccessType;
-import javax.xml.bind.annotation.XmlAccessorType;
-
-import io.swagger.v3.oas.annotations.media.Schema;
-
-@XmlAccessorType(XmlAccessType.FIELD)
-public class CrossChainBitcoinP2SHStatus {
-
-	@Schema(description = "Bitcoin P2SH address", example = "3CdH27kTpV8dcFHVRYjQ8EEV5FJg9X8pSJ (mainnet), 2fMiRRXVsxhZeyfum9ifybZvaMHbQTmwdZw (testnet)")
-	public String bitcoinP2shAddress;
-
-	@Schema(description = "Bitcoin P2SH balance")
-	public BigDecimal bitcoinP2shBalance;
-
-	@Schema(description = "Can P2SH redeem yet?")
-	public boolean canRedeem;
-
-	@Schema(description = "Can P2SH refund yet?")
-	public boolean canRefund;
-
-	@Schema(description = "Secret extracted by P2SH redeemer")
-	public byte[] secret;
-
-	public CrossChainBitcoinP2SHStatus() {
-	}
-
-}

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

@@ -25,6 +25,9 @@ public class CrossChainBitcoinRedeemRequest {
 	@Schema(description = "32-byte secret", example = "6gVbAXCVzJXAWwtAVGAfgAkkXpeXvPUwSciPmCfSfXJG")
 	public byte[] secret;
 
+	@Schema(description = "Bitcoin HASH160(public key) for receiving funds, or omit to derive from private key", example = "u17kBVKkKSp12oUzaxFwNnq1JZf")
+	public byte[] receivingAccountInfo;
+
 	public CrossChainBitcoinRedeemRequest() {
 	}
 

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

@@ -22,6 +22,9 @@ public class CrossChainBitcoinRefundRequest {
 	@Schema(description = "Bitcoin miner fee", example = "0.00001000")
 	public BigDecimal bitcoinMinerFee;
 
+	@Schema(description = "Bitcoin HASH160(public key) for receiving funds, or omit to derive from private key", example = "u17kBVKkKSp12oUzaxFwNnq1JZf")
+	public byte[] receivingAccountInfo;
+
 	public CrossChainBitcoinRefundRequest() {
 	}
 

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

@@ -0,0 +1,31 @@
+package org.qortal.api.model;
+
+import java.math.BigDecimal;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class CrossChainBitcoinyHTLCStatus {
+
+	@Schema(description = "P2SH address", example = "3CdH27kTpV8dcFHVRYjQ8EEV5FJg9X8pSJ (mainnet), 2fMiRRXVsxhZeyfum9ifybZvaMHbQTmwdZw (testnet)")
+	public String bitcoinP2shAddress;
+
+	@Schema(description = "P2SH balance")
+	public BigDecimal bitcoinP2shBalance;
+
+	@Schema(description = "Can HTLC redeem yet?")
+	public boolean canRedeem;
+
+	@Schema(description = "Can HTLC refund yet?")
+	public boolean canRefund;
+
+	@Schema(description = "Secret used by HTLC redeemer")
+	public byte[] secret;
+
+	public CrossChainBitcoinyHTLCStatus() {
+	}
+
+}

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

@@ -12,20 +12,19 @@ public class CrossChainBuildRequest {
 	@Schema(description = "AT creator's public key", example = "C6wuddsBV3HzRrXUtezE7P5MoRXp5m3mEDokRDGZB6ry")
 	public byte[] creatorPublicKey;
 
-	@Schema(description = "Initial QORT amount paid when trade agreed", example = "0.00100000")
-	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
-	public long initialQortAmount;
-
 	@Schema(description = "Final QORT amount paid out on successful trade", example = "80.40200000")
 	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
-	public long finalQortAmount;
+	public long qortAmount;
 
 	@Schema(description = "QORT amount funding AT, including covering AT execution fees", example = "123.45670000")
 	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
 	public long fundingQortAmount;
 
+	@Schema(description = "HASH160 of creator's Bitcoin public key", example = "2daMveGc5pdjRyFacbxBzMksCbyC")
+	public byte[] bitcoinPublicKeyHash;
+
 	@Schema(description = "HASH160 of secret", example = "43vnftqkjxrhb5kJdkU1ZFQLEnWV")
-	public byte[] secretHash;
+	public byte[] hashOfSecretB;
 
 	@Schema(description = "Bitcoin P2SH BTC balance for release of secret", example = "0.00864200")
 	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)

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

@@ -8,10 +8,10 @@ import io.swagger.v3.oas.annotations.media.Schema;
 @XmlAccessorType(XmlAccessType.FIELD)
 public class CrossChainCancelRequest {
 
-	@Schema(description = "AT creator's public key", example = "C6wuddsBV3HzRrXUtezE7P5MoRXp5m3mEDokRDGZB6ry")
+	@Schema(description = "AT creator's public key", example = "K6wuddsBV3HzRrXFFezE7P5MoRXp5m3mEDokRDGZB6ry")
 	public byte[] creatorPublicKey;
 
-	@Schema(description = "Qortal AT address")
+	@Schema(description = "Qortal trade AT address")
 	public String atAddress;
 
 	public CrossChainCancelRequest() {

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

@@ -0,0 +1,127 @@
+package org.qortal.api.model;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
+
+import org.qortal.crosschain.AcctMode;
+import org.qortal.data.crosschain.CrossChainTradeData;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+// All properties to be converted to JSON via JAXB
+@XmlAccessorType(XmlAccessType.FIELD)
+public class CrossChainOfferSummary {
+
+	// Properties
+
+	@Schema(description = "AT's Qortal address")
+	private String qortalAtAddress;
+
+	@Schema(description = "AT creator's Qortal address")
+	private String qortalCreator;
+
+	@Schema(description = "AT creator's ephemeral trading key-pair represented as Qortal address")
+	private String qortalCreatorTradeAddress;
+
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	private long qortAmount;
+
+	@Schema(description = "Bitcoin amount - DEPRECATED: use foreignAmount")
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	@Deprecated
+	private long btcAmount;
+
+	@Schema(description = "Foreign blockchain amount")
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	private long foreignAmount;
+
+	@Schema(description = "Suggested trade timeout (minutes)", example = "10080")
+	private int tradeTimeout;
+
+	@Schema(description = "Current AT execution mode")
+	private AcctMode mode;
+
+	private long timestamp;
+
+	@Schema(description = "Trade partner's Qortal receiving address")
+	private String partnerQortalReceivingAddress;
+
+	private String foreignBlockchain;
+
+	private String acctName;
+
+	protected CrossChainOfferSummary() {
+		/* For JAXB */
+	}
+
+	public CrossChainOfferSummary(CrossChainTradeData crossChainTradeData, long timestamp) {
+		this.qortalAtAddress = crossChainTradeData.qortalAtAddress;
+		this.qortalCreator = crossChainTradeData.qortalCreator;
+		this.qortalCreatorTradeAddress = crossChainTradeData.qortalCreatorTradeAddress;
+		this.qortAmount = crossChainTradeData.qortAmount;
+		this.foreignAmount = crossChainTradeData.expectedForeignAmount;
+		this.btcAmount = this.foreignAmount; // Duplicate for deprecated field
+		this.tradeTimeout = crossChainTradeData.tradeTimeout;
+		this.mode = crossChainTradeData.mode;
+		this.timestamp = timestamp;
+		this.partnerQortalReceivingAddress = crossChainTradeData.qortalPartnerReceivingAddress;
+		this.foreignBlockchain = crossChainTradeData.foreignBlockchain;
+		this.acctName = crossChainTradeData.acctName;
+	}
+
+	public String getQortalAtAddress() {
+		return this.qortalAtAddress;
+	}
+
+	public String getQortalCreator() {
+		return this.qortalCreator;
+	}
+
+	public String getQortalCreatorTradeAddress() {
+		return this.qortalCreatorTradeAddress;
+	}
+
+	public long getQortAmount() {
+		return this.qortAmount;
+	}
+
+	public long getBtcAmount() {
+		return this.btcAmount;
+	}
+
+	public long getForeignAmount() {
+		return this.foreignAmount;
+	}
+
+	public int getTradeTimeout() {
+		return this.tradeTimeout;
+	}
+
+	public AcctMode getMode() {
+		return this.mode;
+	}
+
+	public long getTimestamp() {
+		return this.timestamp;
+	}
+
+	public String getPartnerQortalReceivingAddress() {
+		return this.partnerQortalReceivingAddress;
+	}
+
+	public String getForeignBlockchain() {
+		return this.foreignBlockchain;
+	}
+
+	public String getAcctName() {
+		return this.acctName;
+	}
+
+	// For debugging mostly
+
+	public String toString() {
+		return String.format("%s: %s", this.qortalAtAddress, this.mode);
+	}
+
+}

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

@@ -8,14 +8,20 @@ import io.swagger.v3.oas.annotations.media.Schema;
 @XmlAccessorType(XmlAccessType.FIELD)
 public class CrossChainSecretRequest {
 
-	@Schema(description = "Public key to match AT's 'recipient'", example = "C6wuddsBV3HzRrXUtezE7P5MoRXp5m3mEDokRDGZB6ry")
-	public byte[] recipientPublicKey;
+	@Schema(description = "Public key to match AT's trade 'partner'", example = "C6wuddsBV3HzRrXUtezE7P5MoRXp5m3mEDokRDGZB6ry")
+	public byte[] partnerPublicKey;
 
 	@Schema(description = "Qortal AT address")
 	public String atAddress;
 
-	@Schema(description = "32-byte secret", example = "6gVbAXCVzJXAWwtAVGAfgAkkXpeXvPUwSciPmCfSfXJG")
-	public byte[] secret;
+	@Schema(description = "secret-A (32 bytes)", example = "FHMzten4he9jZ4HGb4297Utj6F5g2w7serjq2EnAg2s1")
+	public byte[] secretA;
+
+	@Schema(description = "secret-B (32 bytes)", example = "EN2Bgx3BcEMtxFCewmCVSMkfZjVKYhx3KEXC5A21KBGx")
+	public byte[] secretB;
+
+	@Schema(description = "Qortal address for receiving QORT from AT")
+	public String receivingAddress;
 
 	public CrossChainSecretRequest() {
 	}

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

@@ -8,14 +8,14 @@ import io.swagger.v3.oas.annotations.media.Schema;
 @XmlAccessorType(XmlAccessType.FIELD)
 public class CrossChainTradeRequest {
 
-	@Schema(description = "AT creator's public key", example = "C6wuddsBV3HzRrXUtezE7P5MoRXp5m3mEDokRDGZB6ry")
-	public byte[] creatorPublicKey;
+	@Schema(description = "AT creator's 'trade' public key", example = "C6wuddsBV3HzRrXUtezE7P5MoRXp5m3mEDokRDGZB6ry")
+	public byte[] tradePublicKey;
 
 	@Schema(description = "Qortal AT address")
 	public String atAddress;
 
-	@Schema(description = "Qortal address for trade partner/recipient")
-	public String recipient;
+	@Schema(description = "Signature of trading partner's 'offer' MESSAGE transaction")
+	public byte[] messageTransactionSignature;
 
 	public CrossChainTradeRequest() {
 	}

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

@@ -0,0 +1,54 @@
+package org.qortal.api.model;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
+
+import org.qortal.data.crosschain.CrossChainTradeData;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+// All properties to be converted to JSON via JAXB
+@XmlAccessorType(XmlAccessType.FIELD)
+public class CrossChainTradeSummary {
+
+	private long tradeTimestamp;
+
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	private long qortAmount;
+
+	@Deprecated
+	@Schema(description = "DEPRECATED: use foreignAmount instead")
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	private long btcAmount;
+
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	private long foreignAmount;
+
+	protected CrossChainTradeSummary() {
+		/* For JAXB */
+	}
+
+	public CrossChainTradeSummary(CrossChainTradeData crossChainTradeData, long timestamp) {
+		this.tradeTimestamp = timestamp;
+		this.qortAmount = crossChainTradeData.qortAmount;
+		this.foreignAmount = crossChainTradeData.expectedForeignAmount;
+		this.btcAmount = this.foreignAmount;
+	}
+
+	public long getTradeTimestamp() {
+		return this.tradeTimestamp;
+	}
+
+	public long getQortAmount() {
+		return this.qortAmount;
+	}
+
+	public long getBtcAmount() {
+		return this.btcAmount;
+	}
+
+	public long getForeignAmount() {
+		return this.foreignAmount;
+	}
+}

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

@@ -11,6 +11,7 @@ public class NodeInfo {
 	public String buildVersion;
 	public long buildTimestamp;
 	public String nodeId;
+	public boolean isTestNet;
 
 	public NodeInfo() {
 	}

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

@@ -20,17 +20,14 @@ public class NodeStatus {
 	public final int height;
 
 	public NodeStatus() {
-		isMintingPossible = Controller.getInstance().isMintingPossible();
-		isSynchronizing = Controller.getInstance().isSynchronizing();
+		this.isMintingPossible = Controller.getInstance().isMintingPossible();
 
-		if (isSynchronizing)
-			syncPercent = Controller.getInstance().getSyncPercent();
-		else
-			syncPercent = null;
+		this.syncPercent = Controller.getInstance().getSyncPercent();
+		this.isSynchronizing = this.syncPercent != null;
 
-		numberOfConnections = Network.getInstance().getHandshakedPeers().size();
+		this.numberOfConnections = Network.getInstance().getHandshakedPeers().size();
 
-		height = Controller.getInstance().getChainHeight();
+		this.height = Controller.getInstance().getChainHeight();
 	}
 
 }

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

@@ -0,0 +1,157 @@
+package org.qortal.api.model;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class SimpleForeignTransaction {
+
+	public static class AddressAmount {
+		public final String address;
+		public final long amount;
+
+		protected AddressAmount() {
+			/* For JAXB */
+			this.address = null;
+			this.amount = 0;
+		}
+
+		public AddressAmount(String address, long amount) {
+			this.address = address;
+			this.amount = amount;
+		}
+	}
+
+	private String txHash;
+	private long timestamp;
+
+	private List<AddressAmount> inputs;
+
+	public static class Output {
+		public final List<String> addresses;
+		public final long amount;
+
+		protected Output() {
+			/* For JAXB */
+			this.addresses = null;
+			this.amount = 0;
+		}
+
+		public Output(List<String> addresses, long amount) {
+			this.addresses = addresses;
+			this.amount = amount;
+		}
+	}
+	private List<Output> outputs;
+
+	private long totalAmount;
+	private long fees;
+
+	private Boolean isSentNotReceived;
+
+	protected SimpleForeignTransaction() {
+		/* For JAXB */
+	}
+
+	private SimpleForeignTransaction(Builder builder) {
+		this.txHash = builder.txHash;
+		this.timestamp = builder.timestamp;
+		this.inputs = Collections.unmodifiableList(builder.inputs);
+		this.outputs = Collections.unmodifiableList(builder.outputs);
+
+		Objects.requireNonNull(this.txHash);
+		if (timestamp <= 0)
+			throw new IllegalArgumentException("timestamp must be positive");
+
+		long totalGrossAmount = this.inputs.stream().map(addressAmount -> addressAmount.amount).reduce(0L, Long::sum);
+		this.totalAmount = this.outputs.stream().map(addressAmount -> addressAmount.amount).reduce(0L, Long::sum);
+
+		this.fees = totalGrossAmount - this.totalAmount;
+
+		this.isSentNotReceived = builder.isSentNotReceived;
+	}
+
+	public String getTxHash() {
+		return this.txHash;
+	}
+
+	public long getTimestamp() {
+		return this.timestamp;
+	}
+
+	public List<AddressAmount> getInputs() {
+		return this.inputs;
+	}
+
+	public List<Output> getOutputs() {
+		return this.outputs;
+	}
+
+	public long getTotalAmount() {
+		return this.totalAmount;
+	}
+
+	public long getFees() {
+		return this.fees;
+	}
+
+	public Boolean isSentNotReceived() {
+		return this.isSentNotReceived;
+	}
+
+	public static class Builder {
+		private String txHash;
+		private long timestamp;
+		private List<AddressAmount> inputs = new ArrayList<>();
+		private List<Output> outputs = new ArrayList<>();
+		private Boolean isSentNotReceived;
+
+		public Builder txHash(String txHash) {
+			this.txHash = Objects.requireNonNull(txHash);
+			return this;
+		}
+
+		public Builder timestamp(long timestamp) {
+			if (timestamp <= 0)
+				throw new IllegalArgumentException("timestamp must be positive");
+
+			this.timestamp = timestamp;
+			return this;
+		}
+
+		public Builder input(String address, long amount) {
+			Objects.requireNonNull(address);
+			if (amount < 0)
+				throw new IllegalArgumentException("amount must be zero or positive");
+
+			AddressAmount input = new AddressAmount(address, amount);
+			inputs.add(input);
+			return this;
+		}
+
+		public Builder output(List<String> addresses, long amount) {
+			Objects.requireNonNull(addresses);
+			if (amount < 0)
+				throw new IllegalArgumentException("amount must be zero or positive");
+
+			Output output = new Output(addresses, amount);
+			outputs.add(output);
+			return this;
+		}
+
+		public Builder isSentNotReceived(Boolean isSentNotReceived) {
+			this.isSentNotReceived = isSentNotReceived;
+			return this;
+		}
+
+		public SimpleForeignTransaction build() {
+			return new SimpleForeignTransaction(this);
+		}
+	}
+
+}

src/main/java/org/qortal/api/model/crosschain/BitcoinSendRequest.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 BitcoinSendRequest {
+
+	@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", 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

@@ -0,0 +1,46 @@
+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)
+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 = "80.40000000", type = "number")
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	public long qortAmount;
+
+	@Schema(description = "QORT amount funding AT, including covering AT execution fees", example = "80.50000000", type = "number")
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	public long fundingQortAmount;
+
+	@Deprecated
+	@Schema(description = "Bitcoin amount wanted in return. DEPRECATED: use foreignAmount instead", example = "0.00864200", type = "number", hidden = true)
+	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
+	public Long bitcoinAmount;
+
+	@Schema(description = "Foreign blockchain. Note: default (BITCOIN) to be removed in the future", example = "BITCOIN", implementation = SupportedBlockchain.class)
+	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 = "Foreign blockchain address for receiving", example = "1BitcoinEaterAddressDontSendf59kuE")
+	public String receivingAddress;
+
+	public TradeBotCreateRequest() {
+	}
+
+}

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

@@ -0,0 +1,29 @@
+package org.qortal.api.model.crosschain;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class TradeBotRespondRequest {
+
+	@Schema(description = "Qortal AT address", example = "Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
+	public String atAddress;
+
+	@Deprecated
+	@Schema(description = "Bitcoin BIP32 extended private key. DEPRECATED: use foreignKey instead", hidden = true,
+			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;
+
+	public TradeBotRespondRequest() {
+	}
+
+}

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

@@ -7,6 +7,7 @@ import io.swagger.v3.oas.annotations.media.Content;
 import io.swagger.v3.oas.annotations.media.Schema;
 import io.swagger.v3.oas.annotations.parameters.RequestBody;
 import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.security.SecurityRequirement;
 import io.swagger.v3.oas.annotations.tags.Tag;
 
 import java.math.BigDecimal;
@@ -473,6 +474,7 @@ public class AddressesResource {
 		}
 	)
 	@ApiErrors({ApiError.TRANSACTION_INVALID, ApiError.INVALID_DATA, ApiError.TRANSFORMATION_ERROR, ApiError.REPOSITORY_ISSUE})
+	@SecurityRequirement(name = "apiKey")
 	public String computePublicize(String rawBytes58) {
 		Security.checkApiCallAllowed(request);
 

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

@@ -8,6 +8,7 @@ import io.swagger.v3.oas.annotations.media.Content;
 import io.swagger.v3.oas.annotations.media.Schema;
 import io.swagger.v3.oas.annotations.parameters.RequestBody;
 import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.security.SecurityRequirement;
 import io.swagger.v3.oas.annotations.tags.Tag;
 
 import java.io.IOException;
@@ -40,7 +41,6 @@ import org.qortal.account.Account;
 import org.qortal.account.PrivateKeyAccount;
 import org.qortal.api.ApiError;
 import org.qortal.api.ApiErrors;
-import org.qortal.api.ApiException;
 import org.qortal.api.ApiExceptionFactory;
 import org.qortal.api.Security;
 import org.qortal.api.model.ActivitySummary;
@@ -57,6 +57,7 @@ import org.qortal.network.PeerAddress;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryManager;
+import org.qortal.settings.Settings;
 import org.qortal.utils.Base58;
 import org.qortal.utils.NTP;
 
@@ -118,6 +119,7 @@ public class AdminResource {
 		nodeInfo.buildVersion = Controller.getInstance().getVersionString();
 		nodeInfo.buildTimestamp = Controller.getInstance().getBuildTimestamp();
 		nodeInfo.nodeId = Network.getInstance().getOurNodeId();
+		nodeInfo.isTestNet = Settings.getInstance().isTestNet();
 
 		return nodeInfo;
 	}
@@ -132,6 +134,7 @@ public class AdminResource {
 			)
 		}
 	)
+	@SecurityRequirement(name = "apiKey")
 	public NodeStatus status() {
 		Security.checkApiCallAllowed(request);
 
@@ -152,6 +155,7 @@ public class AdminResource {
 			)
 		}
 	)
+	@SecurityRequirement(name = "apiKey")
 	public String shutdown() {
 		Security.checkApiCallAllowed(request);
 
@@ -180,7 +184,10 @@ public class AdminResource {
 		}
 	)
 	@ApiErrors({ApiError.REPOSITORY_ISSUE})
+	@SecurityRequirement(name = "apiKey")
 	public ActivitySummary summary() {
+		Security.checkApiCallAllowed(request);
+
 		ActivitySummary summary = new ActivitySummary();
 
 		LocalDate date = LocalDate.now();
@@ -192,16 +199,13 @@ public class AdminResource {
 			int startHeight = repository.getBlockRepository().getHeightFromTimestamp(start);
 			int endHeight = repository.getBlockRepository().getBlockchainHeight();
 
-			summary.blockCount = endHeight - startHeight;
+			summary.setBlockCount(endHeight - startHeight);
 
-			summary.transactionCountByType = repository.getTransactionRepository().getTransactionSummary(startHeight + 1, endHeight);
+			summary.setTransactionCountByType(repository.getTransactionRepository().getTransactionSummary(startHeight + 1, endHeight));
 
-			for (Integer count : summary.transactionCountByType.values())
-				summary.transactionCount += count;
+			summary.setAssetsIssued(repository.getAssetRepository().getRecentAssetIds(start).size());
 
-			summary.assetsIssued = repository.getAssetRepository().getRecentAssetIds(start).size();
-
-			summary.namesRegistered = repository.getNameRepository().getRecentNames(start).size();
+			summary.setNamesRegistered (repository.getNameRepository().getRecentNames(start).size());
 
 			return summary;
 		} catch (DataException e) {
@@ -209,6 +213,30 @@ public class AdminResource {
 		}
 	}
 
+	@GET
+	@Path("/enginestats")
+	@Operation(
+		summary = "Fetch statistics snapshot for core engine",
+		responses = {
+			@ApiResponse(
+				content = @Content(
+					mediaType = MediaType.APPLICATION_JSON,
+					array = @ArraySchema(
+						schema = @Schema(
+							implementation = Controller.StatsSnapshot.class
+						)
+					)
+				)
+			)
+		}
+	)
+	@SecurityRequirement(name = "apiKey")
+	public Controller.StatsSnapshot getEngineStats() {
+		Security.checkApiCallAllowed(request);
+
+		return Controller.getInstance().getStatsSnapshot();
+	}
+
 	@GET
 	@Path("/mintingaccounts")
 	@Operation(
@@ -221,6 +249,7 @@ public class AdminResource {
 		}
 	)
 	@ApiErrors({ApiError.REPOSITORY_ISSUE})
+	@SecurityRequirement(name = "apiKey")
 	public List<MintingAccountData> getMintingAccounts() {
 		Security.checkApiCallAllowed(request);
 
@@ -267,6 +296,7 @@ public class AdminResource {
 		}
 	)
 	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.REPOSITORY_ISSUE, ApiError.CANNOT_MINT})
+	@SecurityRequirement(name = "apiKey")
 	public String addMintingAccount(String seed58) {
 		Security.checkApiCallAllowed(request);
 
@@ -302,13 +332,13 @@ public class AdminResource {
 	@DELETE
 	@Path("/mintingaccounts")
 	@Operation(
-		summary = "Remove account/reward-share from use by BlockMinter, using private key",
+		summary = "Remove account/reward-share from use by BlockMinter, using public or private key",
 		requestBody = @RequestBody(
 			required = true,
 			content = @Content(
 				mediaType = MediaType.TEXT_PLAIN,
 				schema = @Schema(
-					type = "string", example = "private key"
+					type = "string", example = "public or private key"
 				)
 			)
 		),
@@ -319,13 +349,14 @@ public class AdminResource {
 		}
 	)
 	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.REPOSITORY_ISSUE})
-	public String deleteMintingAccount(String seed58) {
+	@SecurityRequirement(name = "apiKey")
+	public String deleteMintingAccount(String key58) {
 		Security.checkApiCallAllowed(request);
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			byte[] seed = Base58.decode(seed58.trim());
+			byte[] key = Base58.decode(key58.trim());
 
-			if (repository.getAccountRepository().delete(seed) == 0)
+			if (repository.getAccountRepository().delete(key) == 0)
 				return "false";
 
 			repository.saveChanges();
@@ -418,6 +449,7 @@ public class AdminResource {
 		}
 	)
 	@ApiErrors({ApiError.INVALID_HEIGHT, ApiError.REPOSITORY_ISSUE})
+	@SecurityRequirement(name = "apiKey")
 	public String orphan(String targetHeightString) {
 		Security.checkApiCallAllowed(request);
 
@@ -435,8 +467,6 @@ public class AdminResource {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		} catch (NumberFormatException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_HEIGHT);
-		} catch (ApiException e) {
-			throw e;
 		}
 	}
 
@@ -461,6 +491,7 @@ public class AdminResource {
 		}
 	)
 	@ApiErrors({ApiError.INVALID_DATA, ApiError.REPOSITORY_ISSUE})
+	@SecurityRequirement(name = "apiKey")
 	public String forceSync(String targetPeerAddress) {
 		Security.checkApiCallAllowed(request);
 
@@ -492,8 +523,6 @@ public class AdminResource {
 			return syncResult.name();
 		} catch (IllegalArgumentException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
-		} catch (ApiException e) {
-			throw e;
 		} catch (UnknownHostException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
 		} catch (InterruptedException e) {
@@ -501,4 +530,172 @@ public class AdminResource {
 		}
 	}
 
+	@GET
+	@Path("/repository/data")
+	@Operation(
+		summary = "Export sensitive/node-local data from repository.",
+		description = "Exports data to .script files on local machine"
+	)
+	@ApiErrors({ApiError.INVALID_DATA, ApiError.REPOSITORY_ISSUE})
+	@SecurityRequirement(name = "apiKey")
+	public String exportRepository() {
+		Security.checkApiCallAllowed(request);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
+
+			blockchainLock.lockInterruptibly();
+
+			try {
+				repository.exportNodeLocalData(true);
+				return "true";
+			} finally {
+				blockchainLock.unlock();
+			}
+		} catch (InterruptedException e) {
+			// We couldn't lock blockchain to perform export
+			return "false";
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@POST
+	@Path("/repository/data")
+	@Operation(
+		summary = "Import data into repository.",
+		description = "Imports data from file on local machine. Filename is forced to 'import.script' if apiKey is not set.",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.TEXT_PLAIN,
+				schema = @Schema(
+					type = "string", example = "MintingAccounts.script"
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				description = "\"true\"",
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.REPOSITORY_ISSUE})
+	@SecurityRequirement(name = "apiKey")
+	public String importRepository(String filename) {
+		Security.checkApiCallAllowed(request);
+
+		// Hard-coded because it's too dangerous to allow user-supplied filenames in weaker security contexts
+		if (Settings.getInstance().getApiKey() == null)
+			filename = "import.script";
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
+
+			blockchainLock.lockInterruptibly();
+
+			try {
+				repository.importDataFromFile(filename);
+				repository.saveChanges();
+
+				return "true";
+			} finally {
+				blockchainLock.unlock();
+			}
+		} catch (InterruptedException e) {
+			// We couldn't lock blockchain to perform import
+			return "false";
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@POST
+	@Path("/repository/checkpoint")
+	@Operation(
+		summary = "Checkpoint data in repository.",
+		description = "Forces repository to checkpoint uncommitted writes.",
+		responses = {
+			@ApiResponse(
+				description = "\"true\"",
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.REPOSITORY_ISSUE})
+	@SecurityRequirement(name = "apiKey")
+	public String checkpointRepository() {
+		Security.checkApiCallAllowed(request);
+
+		RepositoryManager.setRequestedCheckpoint(Boolean.TRUE);
+
+		return "true";
+	}
+
+	@POST
+	@Path("/repository/backup")
+	@Operation(
+		summary = "Perform online backup of repository.",
+		responses = {
+			@ApiResponse(
+				description = "\"true\"",
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.REPOSITORY_ISSUE})
+	@SecurityRequirement(name = "apiKey")
+	public String backupRepository() {
+		Security.checkApiCallAllowed(request);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
+
+			blockchainLock.lockInterruptibly();
+
+			try {
+				repository.backup(true);
+				repository.saveChanges();
+
+				return "true";
+			} finally {
+				blockchainLock.unlock();
+			}
+		} catch (InterruptedException e) {
+			// We couldn't lock blockchain to perform backup
+			return "false";
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@DELETE
+	@Path("/repository")
+	@Operation(
+		summary = "Perform maintenance on repository.",
+		description = "Requires enough free space to rebuild repository. This will pause your node for a while."
+	)
+	@ApiErrors({ApiError.REPOSITORY_ISSUE})
+	@SecurityRequirement(name = "apiKey")
+	public void performRepositoryMaintenance() {
+		Security.checkApiCallAllowed(request);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
+
+			blockchainLock.lockInterruptibly();
+
+			try {
+				repository.performPeriodicMaintenance();
+			} finally {
+				blockchainLock.unlock();
+			}
+		} catch (InterruptedException e) {
+			// No big deal
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
 }

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

@@ -1,11 +1,17 @@
 package org.qortal.api.resource;
 
 import io.swagger.v3.oas.annotations.OpenAPIDefinition;
+import io.swagger.v3.oas.annotations.enums.SecuritySchemeIn;
+import io.swagger.v3.oas.annotations.enums.SecuritySchemeType;
 import io.swagger.v3.oas.annotations.extensions.Extension;
 import io.swagger.v3.oas.annotations.extensions.ExtensionProperty;
 import io.swagger.v3.oas.annotations.info.Info;
+import io.swagger.v3.oas.annotations.security.SecurityScheme;
+import io.swagger.v3.oas.annotations.security.SecuritySchemes;
 import io.swagger.v3.oas.annotations.tags.Tag;
 
+import org.qortal.api.Security;
+
 @OpenAPIDefinition(
 		info = @Info( title = "Qortal API", description = "NOTE: byte-arrays are encoded in Base58" ),
 		tags = {
@@ -30,5 +36,9 @@ import io.swagger.v3.oas.annotations.tags.Tag;
 			})
 		}
 )
+@SecuritySchemes({
+	@SecurityScheme(name = "basicAuth", type = SecuritySchemeType.HTTP, scheme = "basic"),
+	@SecurityScheme(name = "apiKey", type = SecuritySchemeType.APIKEY, in = SecuritySchemeIn.HEADER, paramName = Security.API_KEY_HEADER)
+})
 public class ApiDefinition {
 }

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

@@ -25,7 +25,6 @@ import org.qortal.api.ApiError;
 import org.qortal.api.ApiErrors;
 import org.qortal.api.ApiException;
 import org.qortal.api.ApiExceptionFactory;
-import org.qortal.at.QortalAtLoggerFactory;
 import org.qortal.data.at.ATData;
 import org.qortal.data.at.ATStateData;
 import org.qortal.data.transaction.DeployAtTransactionData;
@@ -147,8 +146,7 @@ public class AtResource {
 			ATStateData atStateData = repository.getATRepository().getLatestATState(atAddress);
 			byte[] stateData = atStateData.getStateData();
 
-			QortalAtLoggerFactory loggerFactory = QortalAtLoggerFactory.getInstance();
-			byte[] dataBytes = MachineState.extractDataBytes(loggerFactory, stateData);
+			byte[] dataBytes = MachineState.extractDataBytes(stateData);
 
 			return dataBytes;
 		} catch (ApiException e) {

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

@@ -480,4 +480,44 @@ public class BlocksResource {
 		}
 	}
 
+	@GET
+	@Path("/summaries")
+	@Operation(
+		summary = "Fetch only summary info about a range of blocks",
+		description = "Specify up to 2 out 3 of: start, end and count. If neither start nor end are specified, then end is assumed to be latest block. Where necessary, count is assumed to be 50.",
+		responses = {
+			@ApiResponse(
+				description = "blocks",
+				content = @Content(
+					array = @ArraySchema(
+						schema = @Schema(
+							implementation = BlockSummaryData.class
+						)
+					)
+				)
+			)
+		}
+	)
+	@ApiErrors({
+		ApiError.REPOSITORY_ISSUE
+	})
+	public List<BlockSummaryData> getBlockSummaries(
+			@QueryParam("start") Integer startHeight,
+			@QueryParam("end") Integer endHeight,
+			@Parameter(ref = "count") @QueryParam("count") Integer count) {
+		// Check up to 2 out of 3 params
+		if (startHeight != null && endHeight != null && count != null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		// Check values
+		if ((startHeight != null && startHeight < 1) || (endHeight != null && endHeight < 1) || (count != null && count < 1))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			return repository.getBlockRepository().getBlockSummaries(startHeight, endHeight, count);
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
 }

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

@@ -7,6 +7,7 @@ import io.swagger.v3.oas.annotations.media.Content;
 import io.swagger.v3.oas.annotations.media.Schema;
 import io.swagger.v3.oas.annotations.parameters.RequestBody;
 import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.security.SecurityRequirement;
 import io.swagger.v3.oas.annotations.tags.Tag;
 
 import java.util.List;
@@ -156,6 +157,7 @@ public class ChatResource {
 		}
 	)
 	@ApiErrors({ApiError.TRANSACTION_INVALID, ApiError.TRANSFORMATION_ERROR, ApiError.REPOSITORY_ISSUE})
+	@SecurityRequirement(name = "apiKey")
 	public String buildChat(ChatTransactionData transactionData) {
 		Security.checkApiCallAllowed(request);
 
@@ -203,6 +205,7 @@ public class ChatResource {
 		}
 	)
 	@ApiErrors({ApiError.TRANSACTION_INVALID, ApiError.INVALID_DATA, ApiError.TRANSFORMATION_ERROR, ApiError.REPOSITORY_ISSUE})
+	@SecurityRequirement(name = "apiKey")
 	public String buildChat(String rawBytes58) {
 		Security.checkApiCallAllowed(request);
 

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

@@ -0,0 +1,363 @@
+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.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.CrossChainBuildRequest;
+import org.qortal.api.model.CrossChainSecretRequest;
+import org.qortal.api.model.CrossChainTradeRequest;
+import org.qortal.asset.Asset;
+import org.qortal.crosschain.BitcoinACCTv1;
+import org.qortal.crosschain.Bitcoiny;
+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.DeployAtTransactionData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.transaction.DeployAtTransaction;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.transaction.Transaction;
+import org.qortal.transaction.Transaction.TransactionType;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.Transformer;
+import org.qortal.transform.transaction.DeployAtTransactionTransformer;
+import org.qortal.transform.transaction.MessageTransactionTransformer;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+@Path("/crosschain/BitcoinACCTv1")
+@Tag(name = "Cross-Chain (BitcoinACCTv1)")
+public class CrossChainBitcoinACCTv1Resource {
+
+	@Context
+	HttpServletRequest request;
+
+	@POST
+	@Path("/build")
+	@Operation(
+		summary = "Build Bitcoin cross-chain trading AT",
+		description = "Returns raw, unsigned DEPLOY_AT transaction",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.APPLICATION_JSON,
+				schema = @Schema(
+					implementation = CrossChainBuildRequest.class
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_DATA, ApiError.INVALID_REFERENCE, ApiError.TRANSFORMATION_ERROR, ApiError.REPOSITORY_ISSUE})
+	public String buildTrade(CrossChainBuildRequest tradeRequest) {
+		Security.checkApiCallAllowed(request);
+
+		byte[] creatorPublicKey = tradeRequest.creatorPublicKey;
+
+		if (creatorPublicKey == null || creatorPublicKey.length != Transformer.PUBLIC_KEY_LENGTH)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+
+		if (tradeRequest.hashOfSecretB == null || tradeRequest.hashOfSecretB.length != Bitcoiny.HASH160_LENGTH)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		if (tradeRequest.tradeTimeout == null)
+			tradeRequest.tradeTimeout = 7 * 24 * 60; // 7 days
+		else
+			if (tradeRequest.tradeTimeout < 10 || tradeRequest.tradeTimeout > 50000)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		if (tradeRequest.qortAmount <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		if (tradeRequest.fundingQortAmount <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		// funding amount must exceed initial + final
+		if (tradeRequest.fundingQortAmount <= tradeRequest.qortAmount)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		if (tradeRequest.bitcoinAmount <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PublicKeyAccount creatorAccount = new PublicKeyAccount(repository, creatorPublicKey);
+
+			byte[] creationBytes = BitcoinACCTv1.buildQortalAT(creatorAccount.getAddress(), tradeRequest.bitcoinPublicKeyHash, tradeRequest.hashOfSecretB,
+					tradeRequest.qortAmount, tradeRequest.bitcoinAmount, tradeRequest.tradeTimeout);
+
+			long txTimestamp = NTP.getTime();
+			byte[] lastReference = creatorAccount.getLastReference();
+			if (lastReference == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_REFERENCE);
+
+			long fee = 0;
+			String name = "QORT-BTC cross-chain trade";
+			String description = "Qortal-Bitcoin cross-chain trade";
+			String atType = "ACCT";
+			String tags = "QORT-BTC ACCT";
+
+			BaseTransactionData baseTransactionData = new BaseTransactionData(txTimestamp, Group.NO_GROUP, lastReference, creatorAccount.getPublicKey(), fee, null);
+			TransactionData deployAtTransactionData = new DeployAtTransactionData(baseTransactionData, name, description, atType, tags, creationBytes, tradeRequest.fundingQortAmount, Asset.QORT);
+
+			Transaction deployAtTransaction = new DeployAtTransaction(repository, deployAtTransactionData);
+
+			fee = deployAtTransaction.calcRecommendedFee();
+			deployAtTransactionData.setFee(fee);
+
+			ValidationResult result = deployAtTransaction.isValidUnconfirmed();
+			if (result != ValidationResult.OK)
+				throw TransactionsResource.createTransactionInvalidException(request, result);
+
+			byte[] bytes = DeployAtTransactionTransformer.toBytes(deployAtTransactionData);
+			return Base58.encode(bytes);
+		} catch (TransformationException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.TRANSFORMATION_ERROR, e);
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@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);
+		}
+	}
+
+	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 +1,167 @@
+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.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.BitcoinyTransaction;
+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/public key in base58, starting with 'xprv'/'xpub' for mainnet, 'tprv'/'tpub' for testnet",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.TEXT_PLAIN,
+				schema = @Schema(
+					type = "string",
+					description = "BIP32 'm' private/public key in base58",
+					example = "tpubD6NzVbkrYhZ4XTPc4btCZ6SMgn8CxmWkj6VBVZ1tfcJfMq4UwAjZbG8U74gGSypL9XBYk2R2BLbDBe8pcEyBKM1edsGQEPKXNbEskZozeZc"
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string", description = "balance (satoshis)"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
+	public String getBitcoinWalletBalance(String key58) {
+		Security.checkApiCallAllowed(request);
+
+		Bitcoin bitcoin = Bitcoin.getInstance();
+
+		if (!bitcoin.isValidDeterministicKey(key58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		Long balance = bitcoin.getWalletBalance(key58);
+		if (balance == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+
+		return balance.toString();
+	}
+
+	@POST
+	@Path("/wallettransactions")
+	@Operation(
+		summary = "Returns transactions for hierarchical, deterministic BIP32 wallet",
+		description = "Supply BIP32 'm' private/public key in base58, starting with 'xprv'/'xpub' for mainnet, 'tprv'/'tpub' for testnet",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.TEXT_PLAIN,
+				schema = @Schema(
+					type = "string",
+					description = "BIP32 'm' private/public key in base58",
+					example = "tpubD6NzVbkrYhZ4XTPc4btCZ6SMgn8CxmWkj6VBVZ1tfcJfMq4UwAjZbG8U74gGSypL9XBYk2R2BLbDBe8pcEyBKM1edsGQEPKXNbEskZozeZc"
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(array = @ArraySchema( schema = @Schema( implementation = BitcoinyTransaction.class ) ) )
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
+	public List<BitcoinyTransaction> getBitcoinWalletTransactions(String key58) {
+		Security.checkApiCallAllowed(request);
+
+		Bitcoin bitcoin = Bitcoin.getInstance();
+
+		if (!bitcoin.isValidDeterministicKey(key58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		try {
+			return bitcoin.getWalletTransactions(key58);
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+		}
+	}
+
+	@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.isValidDeterministicKey(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 +1,175 @@
+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
+				htlcStatus.secret = BitcoinyHTLC.findHtlcSecret(bitcoiny, htlcStatus.bitcoinP2shAddress);
+			}
+
+			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 +1,167 @@
+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.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.BitcoinyTransaction;
+import org.qortal.crosschain.ForeignBlockchainException;
+import org.qortal.crosschain.Litecoin;
+
+@Path("/crosschain/ltc")
+@Tag(name = "Cross-Chain (Litecoin)")
+public class CrossChainLitecoinResource {
+
+	@Context
+	HttpServletRequest request;
+
+	@POST
+	@Path("/walletbalance")
+	@Operation(
+		summary = "Returns LTC balance for hierarchical, deterministic BIP32 wallet",
+		description = "Supply BIP32 'm' private/public key in base58, starting with 'xprv'/'xpub' for mainnet, 'tprv'/'tpub' for testnet",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.TEXT_PLAIN,
+				schema = @Schema(
+					type = "string",
+					description = "BIP32 'm' private/public key in base58",
+					example = "tpubD6NzVbkrYhZ4XTPc4btCZ6SMgn8CxmWkj6VBVZ1tfcJfMq4UwAjZbG8U74gGSypL9XBYk2R2BLbDBe8pcEyBKM1edsGQEPKXNbEskZozeZc"
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string", description = "balance (satoshis)"))
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
+	public String getLitecoinWalletBalance(String key58) {
+		Security.checkApiCallAllowed(request);
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		if (!litecoin.isValidDeterministicKey(key58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		Long balance = litecoin.getWalletBalance(key58);
+		if (balance == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+
+		return balance.toString();
+	}
+
+	@POST
+	@Path("/wallettransactions")
+	@Operation(
+		summary = "Returns transactions for hierarchical, deterministic BIP32 wallet",
+		description = "Supply BIP32 'm' private/public key in base58, starting with 'xprv'/'xpub' for mainnet, 'tprv'/'tpub' for testnet",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.TEXT_PLAIN,
+				schema = @Schema(
+					type = "string",
+					description = "BIP32 'm' private/public key in base58",
+					example = "tpubD6NzVbkrYhZ4XTPc4btCZ6SMgn8CxmWkj6VBVZ1tfcJfMq4UwAjZbG8U74gGSypL9XBYk2R2BLbDBe8pcEyBKM1edsGQEPKXNbEskZozeZc"
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				content = @Content(array = @ArraySchema( schema = @Schema( implementation = BitcoinyTransaction.class ) ) )
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_PRIVATE_KEY, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE})
+	public List<BitcoinyTransaction> getLitecoinWalletTransactions(String key58) {
+		Security.checkApiCallAllowed(request);
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		if (!litecoin.isValidDeterministicKey(key58))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
+
+		try {
+			return litecoin.getWalletTransactions(key58);
+		} catch (ForeignBlockchainException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_NETWORK_ISSUE);
+		}
+	}
+
+	@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.isValidDeterministicKey(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/CrossChainResource.java

@@ -7,69 +7,56 @@ import io.swagger.v3.oas.annotations.media.Content;
 import io.swagger.v3.oas.annotations.media.Schema;
 import io.swagger.v3.oas.annotations.parameters.RequestBody;
 import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.security.SecurityRequirement;
 import io.swagger.v3.oas.annotations.tags.Tag;
 
-import java.math.BigDecimal;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
+import java.util.Map;
+import java.util.Random;
+import java.util.function.Supplier;
 
 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.PathParam;
 import javax.ws.rs.QueryParam;
 import javax.ws.rs.core.Context;
 import javax.ws.rs.core.MediaType;
 
-import org.bitcoinj.core.Address;
-import org.bitcoinj.core.Coin;
-import org.bitcoinj.core.ECKey;
-import org.bitcoinj.core.LegacyAddress;
-import org.bitcoinj.core.NetworkParameters;
-import org.bitcoinj.core.TransactionOutput;
-import org.qortal.account.PublicKeyAccount;
 import org.qortal.api.ApiError;
 import org.qortal.api.ApiErrors;
-import org.qortal.api.ApiException;
 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.api.model.CrossChainBitcoinP2SHStatus;
-import org.qortal.api.model.CrossChainBitcoinRedeemRequest;
-import org.qortal.api.model.CrossChainBitcoinRefundRequest;
-import org.qortal.api.model.CrossChainBitcoinTemplateRequest;
-import org.qortal.api.model.CrossChainBuildRequest;
-import org.qortal.asset.Asset;
-import org.qortal.crosschain.BTC;
-import org.qortal.crosschain.BTCACCT;
+import org.qortal.api.model.CrossChainTradeSummary;
+import org.qortal.crosschain.SupportedBlockchain;
+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.at.ATStateData;
 import org.qortal.data.crosschain.CrossChainTradeData;
-import org.qortal.data.crosschain.CrossChainTradeData.Mode;
 import org.qortal.data.transaction.BaseTransactionData;
-import org.qortal.data.transaction.DeployAtTransactionData;
 import org.qortal.data.transaction.MessageTransactionData;
 import org.qortal.data.transaction.TransactionData;
 import org.qortal.group.Group;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryManager;
-import org.qortal.transaction.DeployAtTransaction;
 import org.qortal.transaction.MessageTransaction;
-import org.qortal.transaction.Transaction;
 import org.qortal.transaction.Transaction.ValidationResult;
 import org.qortal.transform.TransformationException;
 import org.qortal.transform.Transformer;
-import org.qortal.transform.transaction.DeployAtTransactionTransformer;
 import org.qortal.transform.transaction.MessageTransactionTransformer;
+import org.qortal.utils.Amounts;
 import org.qortal.utils.Base58;
+import org.qortal.utils.ByteArray;
 import org.qortal.utils.NTP;
 
-import com.google.common.primitives.Bytes;
-
 @Path("/crosschain")
 @Tag(name = "Cross-Chain")
 public class CrossChainResource {
@@ -83,7 +70,6 @@ public class CrossChainResource {
 		summary = "Find cross-chain trade offers",
 		responses = {
 			@ApiResponse(
-				description = "automated transactions",
 				content = @Content(
 					array = @ArraySchema(
 						schema = @Schema(
@@ -96,6 +82,11 @@ public class CrossChainResource {
 	)
 	@ApiErrors({ApiError.INVALID_CRITERIA, ApiError.REPOSITORY_ISSUE})
 	public List<CrossChainTradeData> getTradeOffers(
+			@Parameter(
+				description = "Limit to specific blockchain",
+				example = "LITECOIN",
+				schema = @Schema(implementation = SupportedBlockchain.class)
+			) @QueryParam("foreignBlockchain") SupportedBlockchain foreignBlockchain,
 			@Parameter( ref = "limit") @QueryParam("limit") Integer limit,
 			@Parameter( ref = "offset" ) @QueryParam("offset") Integer offset,
 			@Parameter( ref = "reverse" ) @QueryParam("reverse") Boolean reverse) {
@@ -103,230 +94,199 @@ public class CrossChainResource {
 		if (limit != null && limit > 100)
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 
-		byte[] codeHash = BTCACCT.CODE_BYTES_HASH;
-		boolean isExecutable = true;
+		final boolean isExecutable = true;
+		List<CrossChainTradeData> crossChainTradesData = new ArrayList<>();
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			List<ATData> atsData = repository.getATRepository().getATsByFunctionality(codeHash, isExecutable, limit, offset, reverse);
+			Map<ByteArray, Supplier<ACCT>> acctsByCodeHash = SupportedBlockchain.getFilteredAcctMap(foreignBlockchain);
 
-			List<CrossChainTradeData> crossChainTradesData = new ArrayList<>();
-			for (ATData atData : atsData) {
-				CrossChainTradeData crossChainTradeData = BTCACCT.populateTradeData(repository, atData);
-				crossChainTradesData.add(crossChainTradeData);
+			for (Map.Entry<ByteArray, Supplier<ACCT>> acctInfo : acctsByCodeHash.entrySet()) {
+				byte[] codeHash = acctInfo.getKey().value;
+				ACCT acct = acctInfo.getValue().get();
+
+				List<ATData> atsData = repository.getATRepository().getATsByFunctionality(codeHash, isExecutable, limit, offset, reverse);
+
+				for (ATData atData : atsData) {
+					CrossChainTradeData crossChainTradeData = acct.populateTradeData(repository, atData);
+					crossChainTradesData.add(crossChainTradeData);
+				}
 			}
 
 			return crossChainTradesData;
-		} catch (ApiException e) {
-			throw e;
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		}
 	}
 
-	@POST
-	@Path("/build")
+	@GET
+	@Path("/trade/{ataddress}")
 	@Operation(
-		summary = "Build cross-chain trading AT",
-		description = "Returns raw, unsigned DEPLOY_AT transaction",
-		requestBody = @RequestBody(
-			required = true,
-			content = @Content(
-				mediaType = MediaType.APPLICATION_JSON,
-				schema = @Schema(
-					implementation = CrossChainBuildRequest.class
-				)
-			)
-		),
-		responses = {
-			@ApiResponse(
-				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
-			)
-		}
-	)
-	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_DATA, ApiError.INVALID_REFERENCE, ApiError.TRANSFORMATION_ERROR, ApiError.REPOSITORY_ISSUE})
-	public String buildTrade(CrossChainBuildRequest tradeRequest) {
-		byte[] creatorPublicKey = tradeRequest.creatorPublicKey;
-
-		if (creatorPublicKey == null || creatorPublicKey.length != Transformer.PUBLIC_KEY_LENGTH)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
-
-		if (tradeRequest.secretHash == null || tradeRequest.secretHash.length != BTC.HASH160_LENGTH)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
-
-		if (tradeRequest.tradeTimeout == null)
-			tradeRequest.tradeTimeout = 7 * 24 * 60; // 7 days
-		else
-			if (tradeRequest.tradeTimeout < 10 || tradeRequest.tradeTimeout > 50000)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
-
-		if (tradeRequest.initialQortAmount < 0)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
-
-		if (tradeRequest.finalQortAmount <= 0)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
-
-		if (tradeRequest.fundingQortAmount <= 0)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
-
-		// funding amount must exceed initial + final
-		if (tradeRequest.fundingQortAmount <= tradeRequest.initialQortAmount + tradeRequest.finalQortAmount)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
-
-		if (tradeRequest.bitcoinAmount <= 0)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
-
-		try (final Repository repository = RepositoryManager.getRepository()) {
-			PublicKeyAccount creatorAccount = new PublicKeyAccount(repository, creatorPublicKey);
-
-			byte[] creationBytes = BTCACCT.buildQortalAT(creatorAccount.getAddress(), tradeRequest.secretHash, tradeRequest.tradeTimeout, tradeRequest.initialQortAmount, tradeRequest.finalQortAmount, tradeRequest.bitcoinAmount);
-
-			long txTimestamp = NTP.getTime();
-			byte[] lastReference = creatorAccount.getLastReference();
-			if (lastReference == null)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_REFERENCE);
-
-			long fee = 0;
-			String name = "QORT-BTC cross-chain trade";
-			String description = "Qortal-Bitcoin cross-chain trade";
-			String atType = "ACCT";
-			String tags = "QORT-BTC ACCT";
-
-			BaseTransactionData baseTransactionData = new BaseTransactionData(txTimestamp, Group.NO_GROUP, lastReference, creatorAccount.getPublicKey(), fee, null);
-			TransactionData deployAtTransactionData = new DeployAtTransactionData(baseTransactionData, name, description, atType, tags, creationBytes, tradeRequest.fundingQortAmount, Asset.QORT);
-
-			Transaction deployAtTransaction = new DeployAtTransaction(repository, deployAtTransactionData);
-
-			fee = deployAtTransaction.calcRecommendedFee();
-			deployAtTransactionData.setFee(fee);
-
-			ValidationResult result = deployAtTransaction.isValidUnconfirmed();
-			if (result != ValidationResult.OK)
-				throw TransactionsResource.createTransactionInvalidException(request, result);
-
-			byte[] bytes = DeployAtTransactionTransformer.toBytes(deployAtTransactionData);
-			return Base58.encode(bytes);
-		} catch (TransformationException e) {
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.TRANSFORMATION_ERROR, e);
-		} catch (DataException e) {
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
-		}
-	}
-
-	@POST
-	@Path("/tradeoffer/recipient")
-	@Operation(
-		summary = "Builds raw, unsigned 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 address of Qortal recipient.<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 same account as the AT creator otherwise the MESSAGE transaction will be invalid.",
-		requestBody = @RequestBody(
-			required = true,
-			content = @Content(
-				mediaType = MediaType.APPLICATION_JSON,
-				schema = @Schema(
-					implementation = CrossChainTradeRequest.class
-				)
-			)
-		),
+		summary = "Show detailed trade info",
 		responses = {
 			@ApiResponse(
 				content = @Content(
 					schema = @Schema(
-						type = "string"
+						implementation = CrossChainTradeData.class
 					)
 				)
 			)
 		}
 	)
-	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.INVALID_CRITERIA, ApiError.REPOSITORY_ISSUE})
-	public String sendTradeRecipient(CrossChainTradeRequest tradeRequest) {
-		byte[] creatorPublicKey = tradeRequest.creatorPublicKey;
-
-		if (creatorPublicKey == null || creatorPublicKey.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.recipient == null || !Crypto.isValidAddress(tradeRequest.recipient))
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
-
+	@ApiErrors({ApiError.ADDRESS_UNKNOWN, ApiError.INVALID_CRITERIA, ApiError.REPOSITORY_ISSUE})
+	public CrossChainTradeData getTrade(@PathParam("ataddress") String atAddress) {
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			ATData atData = fetchAtDataWithChecking(repository, creatorPublicKey, tradeRequest.atAddress);
-			CrossChainTradeData crossChainTradeData = BTCACCT.populateTradeData(repository, atData);
+			ATData atData = repository.getATRepository().fromATAddress(atAddress);
+			if (atData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
 
-			if (crossChainTradeData.mode == CrossChainTradeData.Mode.TRADE)
+			ACCT acct = SupportedBlockchain.getAcctByCodeHash(atData.getCodeHash());
+			if (acct == null)
 				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 
-			// Good to make MESSAGE
-
-			byte[] recipientAddressBytes = Bytes.ensureCapacity(Base58.decode(tradeRequest.recipient), 32, 0);
-			byte[] messageTransactionBytes = buildAtMessage(repository, creatorPublicKey, tradeRequest.atAddress, recipientAddressBytes);
-
-			return Base58.encode(messageTransactionBytes);
+			return acct.populateTradeData(repository, atData);
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		}
 	}
 
-	@POST
-	@Path("/tradeoffer/secret")
+	@GET
+	@Path("/trades")
 	@Operation(
-		summary = "Builds raw, unsigned MESSAGE transaction that sends secret to AT, releasing funds to recipient",
-		description = "Specify address of cross-chain AT that needs to be messaged, and 32-byte secret.<br>"
-			+ "AT needs to be in 'trade' 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 account the AT considers the 'recipient' otherwise the MESSAGE transaction will be invalid.",
-		requestBody = @RequestBody(
-			required = true,
-			content = @Content(
-				mediaType = MediaType.APPLICATION_JSON,
-				schema = @Schema(
-					implementation = CrossChainSecretRequest.class
-				)
-			)
-		),
+		summary = "Find completed cross-chain trades",
+		description = "Returns summary info about successfully completed cross-chain trades",
 		responses = {
 			@ApiResponse(
 				content = @Content(
-					schema = @Schema(
-						type = "string"
+					array = @ArraySchema(
+						schema = @Schema(
+							implementation = CrossChainTradeSummary.class
+						)
 					)
 				)
 			)
 		}
 	)
-	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.INVALID_DATA, ApiError.INVALID_CRITERIA, ApiError.REPOSITORY_ISSUE})
-	public String sendSecret(CrossChainSecretRequest secretRequest) {
-		byte[] recipientPublicKey = secretRequest.recipientPublicKey;
+	@ApiErrors({ApiError.INVALID_CRITERIA, ApiError.REPOSITORY_ISSUE})
+	public List<CrossChainTradeSummary> getCompletedTrades(
+			@Parameter(
+					description = "Limit to specific blockchain",
+					example = "LITECOIN",
+					schema = @Schema(implementation = SupportedBlockchain.class)
+				) @QueryParam("foreignBlockchain") SupportedBlockchain foreignBlockchain,
+			@Parameter(
+				description = "Only return trades that completed on/after this timestamp (milliseconds since epoch)",
+				example = "1597310000000"
+			) @QueryParam("minimumTimestamp") Long minimumTimestamp,
+			@Parameter( ref = "limit") @QueryParam("limit") Integer limit,
+			@Parameter( ref = "offset" ) @QueryParam("offset") Integer offset,
+			@Parameter( ref = "reverse" ) @QueryParam("reverse") Boolean reverse) {
+		// Impose a limit on 'limit'
+		if (limit != null && limit > 100)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 
-		if (recipientPublicKey == null || recipientPublicKey.length != Transformer.PUBLIC_KEY_LENGTH)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
+		// minimumTimestamp (if given) needs to be positive
+		if (minimumTimestamp != null && minimumTimestamp <= 0)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 
-		if (secretRequest.atAddress == null || !Crypto.isValidAtAddress(secretRequest.atAddress))
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
-
-		if (secretRequest.secret == null || secretRequest.secret.length != BTCACCT.SECRET_LENGTH)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+		final Boolean isFinished = Boolean.TRUE;
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			ATData atData = fetchAtDataWithChecking(repository, null, secretRequest.atAddress); // null to skip creator check
-			CrossChainTradeData crossChainTradeData = BTCACCT.populateTradeData(repository, atData);
+			Integer minimumFinalHeight = null;
 
-			if (crossChainTradeData.mode == CrossChainTradeData.Mode.OFFER)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+			if (minimumTimestamp != null) {
+				minimumFinalHeight = repository.getBlockRepository().getHeightFromTimestamp(minimumTimestamp);
 
-			PublicKeyAccount recipientAccount = new PublicKeyAccount(repository, recipientPublicKey);
-			String recipientAddress = recipientAccount.getAddress();
+				if (minimumFinalHeight == 0)
+					// We don't have any blocks since minimumTimestamp, let alone trades, so nothing to return
+					return Collections.emptyList();
 
-			// MESSAGE must come from address that AT considers trade partner / 'recipient'
-			if (!crossChainTradeData.qortalRecipient.equals(recipientAddress))
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+				// height returned from repository is for block BEFORE timestamp
+				// but we want trades AFTER timestamp so bump height accordingly
+				minimumFinalHeight++;
+			}
 
-			// Good to make MESSAGE
+			List<CrossChainTradeSummary> crossChainTrades = new ArrayList<>();
 
-			byte[] messageTransactionBytes = buildAtMessage(repository, recipientPublicKey, secretRequest.atAddress, secretRequest.secret);
+			Map<ByteArray, Supplier<ACCT>> acctsByCodeHash = SupportedBlockchain.getFilteredAcctMap(foreignBlockchain);
 
-			return Base58.encode(messageTransactionBytes);
+			for (Map.Entry<ByteArray, Supplier<ACCT>> acctInfo : acctsByCodeHash.entrySet()) {
+				byte[] codeHash = acctInfo.getKey().value;
+				ACCT acct = acctInfo.getValue().get();
+
+				List<ATStateData> atStates = repository.getATRepository().getMatchingFinalATStates(codeHash,
+						isFinished, acct.getModeByteOffset(), (long) AcctMode.REDEEMED.value, minimumFinalHeight,
+						limit, offset, reverse);
+
+				for (ATStateData atState : atStates) {
+					CrossChainTradeData crossChainTradeData = acct.populateTradeData(repository, atState);
+
+					// We also need block timestamp for use as trade timestamp
+					long timestamp = repository.getBlockRepository().getTimestampFromHeight(atState.getHeight());
+
+					CrossChainTradeSummary crossChainTradeSummary = new CrossChainTradeSummary(crossChainTradeData, timestamp);
+					crossChainTrades.add(crossChainTradeSummary);
+				}
+			}
+
+			return crossChainTrades;
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
+	@GET
+	@Path("/price/{blockchain}")
+	@Operation(
+		summary = "Request current estimated trading price",
+		description = "Returns price based on most recent completed trades. Price is expressed in terms of QORT per unit foreign currency.",
+		responses = {
+			@ApiResponse(
+				content = @Content(
+					schema = @Schema(
+						type = "number"
+					)
+				)
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_CRITERIA, ApiError.REPOSITORY_ISSUE})
+	public long getTradePriceEstimate(
+			@Parameter(
+					description = "foreign blockchain",
+					example = "LITECOIN",
+					schema = @Schema(implementation = SupportedBlockchain.class)
+				) @PathParam("blockchain") SupportedBlockchain foreignBlockchain) {
+		// foreignBlockchain is required
+		if (foreignBlockchain == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		// We want both a minimum of 5 trades and enough trades to span at least 4 hours
+		int minimumCount = 5;
+		int maximumCount = 10;
+		long minimumPeriod = 4 * 60 * 60 * 1000L; // ms
+		Boolean isFinished = Boolean.TRUE;
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			Map<ByteArray, Supplier<ACCT>> acctsByCodeHash = SupportedBlockchain.getFilteredAcctMap(foreignBlockchain);
+
+			long totalForeign = 0;
+			long totalQort = 0;
+
+			for (Map.Entry<ByteArray, Supplier<ACCT>> acctInfo : acctsByCodeHash.entrySet()) {
+				byte[] codeHash = acctInfo.getKey().value;
+				ACCT acct = acctInfo.getValue().get();
+
+				List<ATStateData> atStates = repository.getATRepository().getMatchingFinalATStatesQuorum(codeHash,
+						isFinished, acct.getModeByteOffset(), (long) AcctMode.REDEEMED.value, minimumCount, maximumCount, minimumPeriod);
+
+				for (ATStateData atState : atStates) {
+					CrossChainTradeData crossChainTradeData = acct.populateTradeData(repository, atState);
+					totalForeign += crossChainTradeData.expectedForeignAmount;
+					totalQort += crossChainTradeData.qortAmount;
+				}
+			}
+
+			return Amounts.scaledDivide(totalQort, totalForeign);
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		}
@@ -335,10 +295,11 @@ public class CrossChainResource {
 	@DELETE
 	@Path("/tradeoffer")
 	@Operation(
-		summary = "Builds raw, unsigned MESSAGE transaction that cancels cross-chain trade offer",
+		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 same account as the AT creator otherwise the MESSAGE transaction will be invalid.",
+			+ "AT needs to be in 'offer' mode. Messages sent to an AT in 'trade' mode will be ignored.<br>"
+			+ "Performs MESSAGE proof-of-work.<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(
@@ -359,7 +320,10 @@ public class CrossChainResource {
 		}
 	)
 	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.INVALID_CRITERIA, ApiError.REPOSITORY_ISSUE})
-	public String cancelTradeOffer(CrossChainCancelRequest cancelRequest) {
+	@SecurityRequirement(name = "apiKey")
+	public String cancelTrade(CrossChainCancelRequest cancelRequest) {
+		Security.checkApiCallAllowed(request);
+
 		byte[] creatorPublicKey = cancelRequest.creatorPublicKey;
 
 		if (creatorPublicKey == null || creatorPublicKey.length != Transformer.PUBLIC_KEY_LENGTH)
@@ -369,19 +333,27 @@ public class CrossChainResource {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			ATData atData = fetchAtDataWithChecking(repository, creatorPublicKey, cancelRequest.atAddress);
-			CrossChainTradeData crossChainTradeData = BTCACCT.populateTradeData(repository, atData);
+			ATData atData = fetchAtDataWithChecking(repository, cancelRequest.atAddress);
 
-			if (crossChainTradeData.mode == CrossChainTradeData.Mode.TRADE)
+			ACCT acct = SupportedBlockchain.getAcctByCodeHash(atData.getCodeHash());
+			if (acct == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+
+			CrossChainTradeData crossChainTradeData = acct.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
 
-			PublicKeyAccount creatorAccount = new PublicKeyAccount(repository, creatorPublicKey);
-			String creatorAddress = creatorAccount.getAddress();
-			byte[] recipientAddressBytes = Bytes.ensureCapacity(Base58.decode(creatorAddress), 32, 0);
+			String atCreatorAddress = Crypto.toAddress(creatorPublicKey);
+			byte[] messageData = acct.buildCancelMessage(atCreatorAddress);
 
-			byte[] messageTransactionBytes = buildAtMessage(repository, creatorPublicKey, cancelRequest.atAddress, recipientAddressBytes);
+			byte[] messageTransactionBytes = buildAtMessage(repository, creatorPublicKey, cancelRequest.atAddress, messageData);
 
 			return Base58.encode(messageTransactionBytes);
 		} catch (DataException e) {
@@ -389,347 +361,11 @@ public class CrossChainResource {
 		}
 	}
 
-	@POST
-	@Path("/p2sh")
-	@Operation(
-		summary = "Returns Bitcoin P2SH address based on trade info",
-		requestBody = @RequestBody(
-			required = true,
-			content = @Content(
-				mediaType = MediaType.APPLICATION_JSON,
-				schema = @Schema(
-					implementation = CrossChainBitcoinTemplateRequest.class
-				)
-			)
-		),
-		responses = {
-			@ApiResponse(
-				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
-			)
-		}
-	)
-	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.REPOSITORY_ISSUE})
-	public String deriveP2sh(CrossChainBitcoinTemplateRequest templateRequest) {
-		BTC btc = BTC.getInstance();
-		NetworkParameters params = btc.getNetworkParameters();
-
-		if (templateRequest.refundPublicKeyHash == null || templateRequest.refundPublicKeyHash.length != 20)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
-
-		if (templateRequest.redeemPublicKeyHash == null || templateRequest.redeemPublicKeyHash.length != 20)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
-
-		if (templateRequest.atAddress == null || !Crypto.isValidAtAddress(templateRequest.atAddress))
-			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, null, templateRequest.atAddress); // null to skip creator check
-			CrossChainTradeData crossChainTradeData = BTCACCT.populateTradeData(repository, atData);
-
-			if (crossChainTradeData.mode == Mode.OFFER)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
-
-			byte[] redeemScriptBytes = BTCACCT.buildScript(templateRequest.refundPublicKeyHash, crossChainTradeData.lockTime, templateRequest.redeemPublicKeyHash, crossChainTradeData.secretHash);
-			byte[] redeemScriptHash = Crypto.hash160(redeemScriptBytes);
-
-			Address p2shAddress = LegacyAddress.fromScriptHash(params, redeemScriptHash);
-			return p2shAddress.toString();
-		} catch (DataException e) {
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
-		}
-	}
-
-	@POST
-	@Path("/p2sh/check")
-	@Operation(
-		summary = "Checks Bitcoin P2SH address based on trade info",
-		requestBody = @RequestBody(
-			required = true,
-			content = @Content(
-				mediaType = MediaType.APPLICATION_JSON,
-				schema = @Schema(
-					implementation = CrossChainBitcoinTemplateRequest.class
-				)
-			)
-		),
-		responses = {
-			@ApiResponse(
-				content = @Content(mediaType = MediaType.APPLICATION_JSON, schema = @Schema(implementation = CrossChainBitcoinP2SHStatus.class))
-			)
-		}
-	)
-	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.ADDRESS_UNKNOWN, ApiError.REPOSITORY_ISSUE})
-	public CrossChainBitcoinP2SHStatus checkP2sh(CrossChainBitcoinTemplateRequest templateRequest) {
-		BTC btc = BTC.getInstance();
-		NetworkParameters params = btc.getNetworkParameters();
-
-		if (templateRequest.refundPublicKeyHash == null || templateRequest.refundPublicKeyHash.length != 20)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
-
-		if (templateRequest.redeemPublicKeyHash == null || templateRequest.redeemPublicKeyHash.length != 20)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
-
-		if (templateRequest.atAddress == null || !Crypto.isValidAtAddress(templateRequest.atAddress))
-			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, null, templateRequest.atAddress); // null to skip creator check
-			CrossChainTradeData crossChainTradeData = BTCACCT.populateTradeData(repository, atData);
-
-			if (crossChainTradeData.mode == Mode.OFFER)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
-
-			byte[] redeemScriptBytes = BTCACCT.buildScript(templateRequest.refundPublicKeyHash, crossChainTradeData.lockTime, templateRequest.redeemPublicKeyHash, crossChainTradeData.secretHash);
-			byte[] redeemScriptHash = Crypto.hash160(redeemScriptBytes);
-
-			Address p2shAddress = LegacyAddress.fromScriptHash(params, redeemScriptHash);
-
-			Integer medianBlockTime = BTC.getInstance().getMedianBlockTime();
-			if (medianBlockTime == null)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BTC_NETWORK_ISSUE);
-
-			long now = NTP.getTime();
-
-			// Check P2SH is funded
-
-			Coin p2shBalance = BTC.getInstance().getBalance(p2shAddress.toString());
-			if (p2shBalance == null)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
-
-			CrossChainBitcoinP2SHStatus p2shStatus = new CrossChainBitcoinP2SHStatus();
-			p2shStatus.bitcoinP2shAddress = p2shAddress.toString();
-			p2shStatus.bitcoinP2shBalance = BigDecimal.valueOf(p2shBalance.value, 8);
-
-			List<TransactionOutput> fundingOutputs = BTC.getInstance().getUnspentOutputs(p2shAddress.toString());
-
-			if (p2shBalance.value >= crossChainTradeData.expectedBitcoin && !fundingOutputs.isEmpty()) {
-				p2shStatus.canRedeem = now >= medianBlockTime * 1000L;
-				p2shStatus.canRefund = now >= crossChainTradeData.lockTime * 1000L;
-			}
-
-			if (now >= medianBlockTime * 1000L) {
-				// See if we can extract secret
-				List<byte[]> rawTransactions = BTC.getInstance().getAddressTransactions(p2shStatus.bitcoinP2shAddress);
-				p2shStatus.secret = BTCACCT.findP2shSecret(p2shStatus.bitcoinP2shAddress, rawTransactions);
-			}
-
-			return p2shStatus;
-		} catch (DataException e) {
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
-		}
-	}
-
-	@POST
-	@Path("/p2sh/refund")
-	@Operation(
-		summary = "Returns serialized Bitcoin transaction attempting refund from P2SH address",
-		requestBody = @RequestBody(
-			required = true,
-			content = @Content(
-				mediaType = MediaType.APPLICATION_JSON,
-				schema = @Schema(
-					implementation = CrossChainBitcoinRefundRequest.class
-				)
-			)
-		),
-		responses = {
-			@ApiResponse(
-				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
-			)
-		}
-	)
-	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.ADDRESS_UNKNOWN,
-		ApiError.BTC_TOO_SOON, ApiError.BTC_BALANCE_ISSUE, ApiError.BTC_NETWORK_ISSUE, ApiError.REPOSITORY_ISSUE})
-	public String refundP2sh(CrossChainBitcoinRefundRequest refundRequest) {
-		BTC btc = BTC.getInstance();
-		NetworkParameters params = btc.getNetworkParameters();
-
-		byte[] refundPrivateKey = refundRequest.refundPrivateKey;
-		if (refundPrivateKey == null)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
-
-		ECKey refundKey = null;
-
-		try {
-			// Auto-trim
-			if (refundPrivateKey.length >= 37 && refundPrivateKey.length <= 38)
-				refundPrivateKey = Arrays.copyOfRange(refundPrivateKey, 1, 33);
-			if (refundPrivateKey.length != 32)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
-
-			refundKey = ECKey.fromPrivate(refundPrivateKey);
-		} catch (IllegalArgumentException e) {
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
-		}
-
-		if (refundRequest.redeemPublicKeyHash == null || refundRequest.redeemPublicKeyHash.length != 20)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
-
-		if (refundRequest.atAddress == null || !Crypto.isValidAtAddress(refundRequest.atAddress))
-			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, null, refundRequest.atAddress); // null to skip creator check
-			CrossChainTradeData crossChainTradeData = BTCACCT.populateTradeData(repository, atData);
-
-			if (crossChainTradeData.mode == Mode.OFFER)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
-
-			byte[] redeemScriptBytes = BTCACCT.buildScript(refundKey.getPubKeyHash(), crossChainTradeData.lockTime, refundRequest.redeemPublicKeyHash, crossChainTradeData.secretHash);
-			byte[] redeemScriptHash = Crypto.hash160(redeemScriptBytes);
-
-			Address p2shAddress = LegacyAddress.fromScriptHash(params, redeemScriptHash);
-
-			long now = NTP.getTime();
-
-			// Check P2SH is funded
-
-			Coin p2shBalance = BTC.getInstance().getBalance(p2shAddress.toString());
-			if (p2shBalance == null)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
-
-			List<TransactionOutput> fundingOutputs = BTC.getInstance().getUnspentOutputs(p2shAddress.toString());
-			if (fundingOutputs.isEmpty())
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
-
-			boolean canRefund = now >= crossChainTradeData.lockTime * 1000L;
-			if (!canRefund)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BTC_TOO_SOON);
-
-			if (p2shBalance.value < crossChainTradeData.expectedBitcoin)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BTC_BALANCE_ISSUE);
-
-			Coin refundAmount = p2shBalance.subtract(Coin.valueOf(refundRequest.bitcoinMinerFee.unscaledValue().longValue()));
-
-			org.bitcoinj.core.Transaction refundTransaction = BTCACCT.buildRefundTransaction(refundAmount, refundKey, fundingOutputs, redeemScriptBytes, crossChainTradeData.lockTime);
-			boolean wasBroadcast = BTC.getInstance().broadcastTransaction(refundTransaction);
-
-			if (!wasBroadcast)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BTC_NETWORK_ISSUE);
-
-			return refundTransaction.getTxId().toString();
-		} catch (DataException e) {
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
-		}
-	}
-
-	@POST
-	@Path("/p2sh/redeem")
-	@Operation(
-		summary = "Returns serialized Bitcoin transaction attempting redeem from P2SH address",
-		requestBody = @RequestBody(
-			required = true,
-			content = @Content(
-				mediaType = MediaType.APPLICATION_JSON,
-				schema = @Schema(
-					implementation = CrossChainBitcoinRedeemRequest.class
-				)
-			)
-		),
-		responses = {
-			@ApiResponse(
-				content = @Content(mediaType = MediaType.TEXT_PLAIN, schema = @Schema(type = "string"))
-			)
-		}
-	)
-	@ApiErrors({ApiError.INVALID_PUBLIC_KEY, ApiError.INVALID_ADDRESS, ApiError.ADDRESS_UNKNOWN,
-		ApiError.BTC_TOO_SOON, ApiError.BTC_BALANCE_ISSUE, ApiError.BTC_NETWORK_ISSUE, ApiError.REPOSITORY_ISSUE})
-	public String redeemP2sh(CrossChainBitcoinRedeemRequest redeemRequest) {
-		BTC btc = BTC.getInstance();
-		NetworkParameters params = btc.getNetworkParameters();
-
-		byte[] redeemPrivateKey = redeemRequest.redeemPrivateKey;
-		if (redeemPrivateKey == null)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
-
-		ECKey redeemKey = null;
-
-		try {
-			// Auto-trim
-			if (redeemPrivateKey.length >= 37 && redeemPrivateKey.length <= 38)
-				redeemPrivateKey = Arrays.copyOfRange(redeemPrivateKey, 1, 33);
-			if (redeemPrivateKey.length != 32)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
-
-			redeemKey = ECKey.fromPrivate(redeemPrivateKey);
-		} catch (IllegalArgumentException e) {
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PRIVATE_KEY);
-		}
-
-		if (redeemRequest.refundPublicKeyHash == null || redeemRequest.refundPublicKeyHash.length != 20)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
-
-		if (redeemRequest.atAddress == null || !Crypto.isValidAtAddress(redeemRequest.atAddress))
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
-
-		if (redeemRequest.secret == null || redeemRequest.secret.length != BTCACCT.SECRET_LENGTH)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
-
-		// Extract data from cross-chain trading AT
-		try (final Repository repository = RepositoryManager.getRepository()) {
-			ATData atData = fetchAtDataWithChecking(repository, null, redeemRequest.atAddress); // null to skip creator check
-			CrossChainTradeData crossChainTradeData = BTCACCT.populateTradeData(repository, atData);
-
-			if (crossChainTradeData.mode == Mode.OFFER)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
-
-			byte[] redeemScriptBytes = BTCACCT.buildScript(redeemRequest.refundPublicKeyHash, crossChainTradeData.lockTime, redeemKey.getPubKeyHash(), crossChainTradeData.secretHash);
-			byte[] redeemScriptHash = Crypto.hash160(redeemScriptBytes);
-
-			Address p2shAddress = LegacyAddress.fromScriptHash(params, redeemScriptHash);
-
-			Integer medianBlockTime = BTC.getInstance().getMedianBlockTime();
-			if (medianBlockTime == null)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BTC_NETWORK_ISSUE);
-
-			long now = NTP.getTime();
-
-			// Check P2SH is funded
-			Coin p2shBalance = BTC.getInstance().getBalance(p2shAddress.toString());
-			if (p2shBalance == null)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.ADDRESS_UNKNOWN);
-
-			if (p2shBalance.value < crossChainTradeData.expectedBitcoin)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BTC_BALANCE_ISSUE);
-
-			List<TransactionOutput> fundingOutputs = BTC.getInstance().getUnspentOutputs(p2shAddress.toString());
-			if (fundingOutputs.isEmpty())
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
-
-			boolean canRedeem = now >= medianBlockTime * 1000L;
-			if (!canRedeem)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BTC_TOO_SOON);
-
-			Coin redeemAmount = p2shBalance.subtract(Coin.valueOf(redeemRequest.bitcoinMinerFee.unscaledValue().longValue()));
-
-			org.bitcoinj.core.Transaction redeemTransaction = BTCACCT.buildRedeemTransaction(redeemAmount, redeemKey, fundingOutputs, redeemScriptBytes, redeemRequest.secret);
-			boolean wasBroadcast = BTC.getInstance().broadcastTransaction(redeemTransaction);
-
-			if (!wasBroadcast)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BTC_NETWORK_ISSUE);
-
-			return redeemTransaction.getTxId().toString();
-		} catch (DataException e) {
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
-		}
-	}
-
-	private ATData fetchAtDataWithChecking(Repository repository, byte[] creatorPublicKey, String atAddress) throws DataException {
+	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);
 
-		// Does supplied public key match that of AT?
-		if (creatorPublicKey != null && !Arrays.equals(creatorPublicKey, atData.getCreatorPublicKey()))
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_PUBLIC_KEY);
-
-		// Must be correct AT - check functionality using code hash
-		if (!Arrays.equals(atData.getCodeHash(), BTCACCT.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);
@@ -738,27 +374,36 @@ public class CrossChainResource {
 	}
 
 	private byte[] buildAtMessage(Repository repository, byte[] senderPublicKey, String atAddress, byte[] messageData) throws DataException {
-		PublicKeyAccount creatorAccount = new PublicKeyAccount(repository, senderPublicKey);
-
 		long txTimestamp = NTP.getTime();
-		byte[] lastReference = creatorAccount.getLastReference();
 
-		if (lastReference == null)
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_REFERENCE);
+		// 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 = null;
+		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);
 
-		fee = messageTransaction.calcRecommendedFee();
-		messageTransactionData.setFee(fee);
+		if (requiresPoW) {
+			messageTransaction.computeNonce();
+		} else {
+			fee = messageTransaction.calcRecommendedFee();
+			messageTransactionData.setFee(fee);
+		}
 
 		ValidationResult result = messageTransaction.isValidUnconfirmed();
 		if (result != ValidationResult.OK)

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

@@ -0,0 +1,286 @@
+package org.qortal.api.resource;
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.Parameter;
+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 java.util.stream.Collectors;
+
+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.QueryParam;
+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.SupportedBlockchain;
+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(
+			@Parameter(
+					description = "Limit to specific blockchain",
+					example = "LITECOIN",
+					schema = @Schema(implementation = SupportedBlockchain.class)
+				) @QueryParam("foreignBlockchain") SupportedBlockchain foreignBlockchain) {
+		Security.checkApiCallAllowed(request);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			List<TradeBotData> allTradeBotData = repository.getCrossChainRepository().getAllTradeBotData();
+
+			if (foreignBlockchain == null)
+				return allTradeBotData;
+
+			return allTradeBotData.stream().filter(tradeBotData -> tradeBotData.getForeignBlockchain().equals(foreignBlockchain.name())).collect(Collectors.toList());
+		} 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);
+
+		if (tradeBotCreateRequest.foreignBlockchain == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+		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/resource/PeersResource.java

@@ -6,8 +6,11 @@ import io.swagger.v3.oas.annotations.media.Content;
 import io.swagger.v3.oas.annotations.media.Schema;
 import io.swagger.v3.oas.annotations.parameters.RequestBody;
 import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.security.SecurityRequirement;
 import io.swagger.v3.oas.annotations.tags.Tag;
 
+import java.net.InetSocketAddress;
+import java.net.UnknownHostException;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.stream.Collectors;
@@ -26,10 +29,17 @@ import org.qortal.api.ApiException;
 import org.qortal.api.ApiExceptionFactory;
 import org.qortal.api.Security;
 import org.qortal.api.model.ConnectedPeer;
+import org.qortal.controller.Controller;
+import org.qortal.controller.Synchronizer;
+import org.qortal.controller.Synchronizer.SynchronizationResult;
+import org.qortal.data.block.BlockSummaryData;
 import org.qortal.data.network.PeerData;
 import org.qortal.network.Network;
+import org.qortal.network.Peer;
 import org.qortal.network.PeerAddress;
 import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
 import org.qortal.utils.ExecuteProduceConsume;
 import org.qortal.utils.NTP;
 
@@ -122,6 +132,7 @@ public class PeersResource {
 			)
 		}
 	)
+	@SecurityRequirement(name = "apiKey")
 	public ExecuteProduceConsume.StatsSnapshot getEngineStats() {
 		Security.checkApiCallAllowed(request);
 
@@ -159,6 +170,7 @@ public class PeersResource {
 	@ApiErrors({
 		ApiError.INVALID_NETWORK_ADDRESS, ApiError.REPOSITORY_ISSUE
 	})
+	@SecurityRequirement(name = "apiKey")
 	public String addPeer(String address) {
 		Security.checkApiCallAllowed(request);
 
@@ -213,6 +225,7 @@ public class PeersResource {
 	@ApiErrors({
 		ApiError.INVALID_NETWORK_ADDRESS, ApiError.REPOSITORY_ISSUE
 	})
+	@SecurityRequirement(name = "apiKey")
 	public String removePeer(String address) {
 		Security.checkApiCallAllowed(request);
 
@@ -248,6 +261,7 @@ public class PeersResource {
 	@ApiErrors({
 		ApiError.REPOSITORY_ISSUE
 	})
+	@SecurityRequirement(name = "apiKey")
 	public String removeKnownPeers(String address) {
 		Security.checkApiCallAllowed(request);
 
@@ -260,4 +274,68 @@ public class PeersResource {
 		}
 	}
 
+	@POST
+	@Path("/commonblock")
+	@Operation(
+		summary = "Report common block with given peer.",
+		requestBody = @RequestBody(
+			required = true,
+			content = @Content(
+				mediaType = MediaType.TEXT_PLAIN,
+				schema = @Schema(
+					type = "string", example = "node2.qortal.org"
+				)
+			)
+		),
+		responses = {
+			@ApiResponse(
+				description = "the block",
+				content = @Content(
+					array = @ArraySchema(
+						schema = @Schema(
+							implementation = BlockSummaryData.class
+						)
+					)
+				)
+			)
+		}
+	)
+	@ApiErrors({ApiError.INVALID_DATA, ApiError.REPOSITORY_ISSUE})
+	@SecurityRequirement(name = "apiKey")
+	public List<BlockSummaryData> commonBlock(String targetPeerAddress) {
+		Security.checkApiCallAllowed(request);
+
+		try {
+			// Try to resolve passed address to make things easier
+			PeerAddress peerAddress = PeerAddress.fromString(targetPeerAddress);
+			InetSocketAddress resolvedAddress = peerAddress.toSocketAddress();
+
+			List<Peer> peers = Network.getInstance().getHandshakedPeers();
+			Peer targetPeer = peers.stream().filter(peer -> peer.getResolvedAddress().equals(resolvedAddress)).findFirst().orElse(null);
+
+			if (targetPeer == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+			try (final Repository repository = RepositoryManager.getRepository()) {
+				int ourInitialHeight = Controller.getInstance().getChainHeight();
+				boolean force = true;
+				List<BlockSummaryData> peerBlockSummaries = new ArrayList<>();
+
+				SynchronizationResult findCommonBlockResult = Synchronizer.getInstance().fetchSummariesFromCommonBlock(repository, targetPeer, ourInitialHeight, force, peerBlockSummaries);
+				if (findCommonBlockResult != SynchronizationResult.OK)
+					return null;
+
+				return peerBlockSummaries;
+			}
+		} catch (IllegalArgumentException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+		} catch (UnknownHostException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		} catch (InterruptedException e) {
+			return null;
+		}
+	}
+
 }

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

@@ -510,14 +510,19 @@ public class TransactionsResource {
 		if (!Controller.getInstance().isUpToDate())
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCKCHAIN_NEEDS_SYNC);
 
+		byte[] rawBytes = Base58.decode(rawBytes58);
+
+		TransactionData transactionData;
+		try {
+			transactionData = TransactionTransformer.fromBytes(rawBytes);
+		} catch (TransformationException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.TRANSFORMATION_ERROR, e);
+		}
+
+		if (transactionData == null)
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			byte[] rawBytes = Base58.decode(rawBytes58);
-
-			TransactionData transactionData = TransactionTransformer.fromBytes(rawBytes);
-
-			if (transactionData == null)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
-
 			Transaction transaction = Transaction.fromData(repository, transactionData);
 
 			if (!transaction.isSignatureValid())
@@ -535,16 +540,9 @@ public class TransactionsResource {
 				blockchainLock.unlock();
 			}
 
-			// Notify controller of new transaction
-			Controller.getInstance().onNewTransaction(transactionData, null);
-
 			return "true";
 		} catch (NumberFormatException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA, e);
-		} catch (TransformationException e) {
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.TRANSFORMATION_ERROR, e);
-		} catch (ApiException e) {
-			throw e;
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		} catch (InterruptedException e) {

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

@@ -6,11 +6,12 @@ import java.util.Map;
 import java.util.concurrent.atomic.AtomicReference;
 
 import org.eclipse.jetty.websocket.api.Session;
+import org.eclipse.jetty.websocket.api.WebSocketException;
 import org.eclipse.jetty.websocket.api.annotations.OnWebSocketClose;
 import org.eclipse.jetty.websocket.api.annotations.OnWebSocketConnect;
+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.WebSocketServlet;
 import org.eclipse.jetty.websocket.servlet.WebSocketServletFactory;
 import org.qortal.controller.ChatNotifier;
 import org.qortal.crypto.Crypto;
@@ -22,7 +23,7 @@ import org.qortal.repository.RepositoryManager;
 
 @WebSocket
 @SuppressWarnings("serial")
-public class ActiveChatsWebSocket extends WebSocketServlet implements ApiWebSocket {
+public class ActiveChatsWebSocket extends ApiWebSocket {
 
 	@Override
 	public void configure(WebSocketServletFactory factory) {
@@ -30,8 +31,9 @@ public class ActiveChatsWebSocket extends WebSocketServlet implements ApiWebSock
 	}
 
 	@OnWebSocketConnect
+	@Override
 	public void onWebSocketConnect(Session session) {
-		Map<String, String> pathParams = this.getPathParams(session, "/{address}");
+		Map<String, String> pathParams = getPathParams(session, "/{address}");
 
 		String address = pathParams.get("address");
 		if (address == null || !Crypto.isValidAddress(address)) {
@@ -48,12 +50,19 @@ public class ActiveChatsWebSocket extends WebSocketServlet implements ApiWebSock
 	}
 
 	@OnWebSocketClose
+	@Override
 	public void onWebSocketClose(Session session, int statusCode, String reason) {
 		ChatNotifier.getInstance().deregister(session);
 	}
 
+	@OnWebSocketError
+	public void onWebSocketError(Session session, Throwable throwable) {
+		/* ignored */
+	}
+
 	@OnWebSocketMessage
 	public void onWebSocketMessage(Session session, String message) {
+		/* ignored */
 	}
 
 	private void onNotify(Session session, ChatTransactionData chatTransactionData, String ourAddress, AtomicReference<String> previousOutput) {
@@ -70,7 +79,7 @@ public class ActiveChatsWebSocket extends WebSocketServlet implements ApiWebSock
 
 			StringWriter stringWriter = new StringWriter();
 
-			this.marshall(stringWriter, activeChats);
+			marshall(stringWriter, activeChats);
 
 			// Only output if something has changed
 			String output = stringWriter.toString();
@@ -78,8 +87,8 @@ public class ActiveChatsWebSocket extends WebSocketServlet implements ApiWebSock
 				return;
 
 			previousOutput.set(output);
-			session.getRemote().sendString(output);
-		} catch (DataException | IOException e) {
+			session.getRemote().sendStringByFuture(output);
+		} catch (DataException | IOException | WebSocketException e) {
 			// No output this time?
 		}
 	}

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

@@ -5,62 +5,95 @@ import java.io.StringWriter;
 import java.util.concurrent.atomic.AtomicReference;
 
 import org.eclipse.jetty.websocket.api.Session;
+import org.eclipse.jetty.websocket.api.WebSocketException;
 import org.eclipse.jetty.websocket.api.annotations.OnWebSocketClose;
 import org.eclipse.jetty.websocket.api.annotations.OnWebSocketConnect;
+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.WebSocketServlet;
 import org.eclipse.jetty.websocket.servlet.WebSocketServletFactory;
 import org.qortal.api.model.NodeStatus;
-import org.qortal.controller.StatusNotifier;
-import org.qortal.repository.DataException;
-import org.qortal.repository.Repository;
-import org.qortal.repository.RepositoryManager;
+import org.qortal.controller.Controller;
+import org.qortal.event.Event;
+import org.qortal.event.EventBus;
+import org.qortal.event.Listener;
 
 @WebSocket
 @SuppressWarnings("serial")
-public class AdminStatusWebSocket extends WebSocketServlet implements ApiWebSocket {
+public class AdminStatusWebSocket extends ApiWebSocket implements Listener {
+
+	private static final AtomicReference<String> previousOutput = new AtomicReference<>(null);
 
 	@Override
 	public void configure(WebSocketServletFactory factory) {
 		factory.register(AdminStatusWebSocket.class);
+
+		try {
+			previousOutput.set(buildStatusString());
+		} catch (IOException e) {
+			// How to fail properly?
+			return;
+		}
+
+		EventBus.INSTANCE.addListener(this::listen);
+	}
+
+	@Override
+	public void listen(Event event) {
+		if (!(event instanceof Controller.StatusChangeEvent))
+			return;
+
+		String newOutput;
+		try {
+			newOutput = buildStatusString();
+		} catch (IOException e) {
+			// Ignore this time?
+			return;
+		}
+
+		if (previousOutput.getAndUpdate(currentValue -> newOutput).equals(newOutput))
+			// Output hasn't changed, so don't send anything
+			return;
+
+		for (Session session : getSessions())
+			this.sendStatus(session, newOutput);
 	}
 
 	@OnWebSocketConnect
+	@Override
 	public void onWebSocketConnect(Session session) {
-		AtomicReference<String> previousOutput = new AtomicReference<>(null);
+		this.sendStatus(session, previousOutput.get());
 
-		StatusNotifier.Listener listener = timestamp -> onNotify(session, previousOutput);
-		StatusNotifier.getInstance().register(session, listener);
-
-		this.onNotify(session, previousOutput);
+		super.onWebSocketConnect(session);
 	}
 
 	@OnWebSocketClose
+	@Override
 	public void onWebSocketClose(Session session, int statusCode, String reason) {
-		StatusNotifier.getInstance().deregister(session);
+		super.onWebSocketClose(session, statusCode, reason);
+	}
+
+	@OnWebSocketError
+	public void onWebSocketError(Session session, Throwable throwable) {
+		/* We ignore errors for now, but method here to silence log spam */
 	}
 
 	@OnWebSocketMessage
 	public void onWebSocketMessage(Session session, String message) {
+		/* ignored */
 	}
 
-	private void onNotify(Session session,AtomicReference<String> previousOutput) {
-		try (final Repository repository = RepositoryManager.getRepository()) {
-			NodeStatus nodeStatus = new NodeStatus();
+	private static String buildStatusString() throws IOException {
+		NodeStatus nodeStatus = new NodeStatus();
+		StringWriter stringWriter = new StringWriter();
+		marshall(stringWriter, nodeStatus);
+		return stringWriter.toString();
+	}
 
-			StringWriter stringWriter = new StringWriter();
-
-			this.marshall(stringWriter, nodeStatus);
-
-			// Only output if something has changed
-			String output = stringWriter.toString();
-			if (output.equals(previousOutput.get()))
-				return;
-
-			previousOutput.set(output);
-			session.getRemote().sendString(output);
-		} catch (DataException | IOException e) {
+	private void sendStatus(Session session, String status) {
+		try {
+			session.getRemote().sendStringByFuture(status);
+		} catch (WebSocketException e) {
 			// No output this time?
 		}
 	}

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

@@ -3,7 +3,10 @@ package org.qortal.api.websocket;
 import java.io.IOException;
 import java.io.StringWriter;
 import java.io.Writer;
+import java.util.ArrayList;
 import java.util.Collection;
+import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import javax.xml.bind.JAXBContext;
@@ -13,24 +16,28 @@ import javax.xml.bind.Marshaller;
 import org.eclipse.jetty.http.pathmap.UriTemplatePathSpec;
 import org.eclipse.jetty.websocket.api.Session;
 import org.eclipse.jetty.websocket.servlet.ServletUpgradeRequest;
+import org.eclipse.jetty.websocket.servlet.WebSocketServlet;
 import org.eclipse.persistence.jaxb.JAXBContextFactory;
 import org.eclipse.persistence.jaxb.MarshallerProperties;
 import org.qortal.api.ApiError;
 import org.qortal.api.ApiErrorRoot;
 
-interface ApiWebSocket {
+@SuppressWarnings("serial")
+abstract class ApiWebSocket extends WebSocketServlet {
 
-	default String getPathInfo(Session session) {
+	private static final Map<Class<? extends ApiWebSocket>, List<Session>> SESSIONS_BY_CLASS = new HashMap<>();
+
+	protected static String getPathInfo(Session session) {
 		ServletUpgradeRequest upgradeRequest = (ServletUpgradeRequest) session.getUpgradeRequest();
 		return upgradeRequest.getHttpServletRequest().getPathInfo();
 	}
 
-	default Map<String, String> getPathParams(Session session, String pathSpec) {
+	protected static Map<String, String> getPathParams(Session session, String pathSpec) {
 		UriTemplatePathSpec uriTemplatePathSpec = new UriTemplatePathSpec(pathSpec);
-		return uriTemplatePathSpec.getPathParams(this.getPathInfo(session));
+		return uriTemplatePathSpec.getPathParams(getPathInfo(session));
 	}
 
-	default void sendError(Session session, ApiError apiError) {
+	protected static void sendError(Session session, ApiError apiError) {
 		ApiErrorRoot apiErrorRoot = new ApiErrorRoot();
 		apiErrorRoot.setApiError(apiError);
 
@@ -43,7 +50,7 @@ interface ApiWebSocket {
 		}
 	}
 
-	default void marshall(Writer writer, Object object) throws IOException {
+	protected static void marshall(Writer writer, Object object) throws IOException {
 		Marshaller marshaller = createMarshaller(object.getClass());
 
 		try {
@@ -53,7 +60,7 @@ interface ApiWebSocket {
 		}
 	}
 
-	default void marshall(Writer writer, Collection<?> collection) throws IOException {
+	protected static void marshall(Writer writer, Collection<?> collection) throws IOException {
 		// If collection is empty then we're returning "[]" anyway
 		if (collection.isEmpty()) {
 			writer.append("[]");
@@ -92,4 +99,24 @@ interface ApiWebSocket {
 		}
 	}
 
+	public void onWebSocketConnect(Session session) {
+		synchronized (SESSIONS_BY_CLASS) {
+			SESSIONS_BY_CLASS.computeIfAbsent(this.getClass(), clazz -> new ArrayList<>()).add(session);
+		}
+	}
+
+	public void onWebSocketClose(Session session, int statusCode, String reason) {
+		synchronized (SESSIONS_BY_CLASS) {
+			List<Session> sessions = SESSIONS_BY_CLASS.get(this.getClass());
+			if (sessions != null)
+				sessions.remove(session);
+		}
+	}
+
+	protected List<Session> getSessions() {
+		synchronized (SESSIONS_BY_CLASS) {
+			return new ArrayList<>(SESSIONS_BY_CLASS.get(this.getClass()));
+		}
+	}
+
 }

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

@@ -2,17 +2,23 @@ package org.qortal.api.websocket;
 
 import java.io.IOException;
 import java.io.StringWriter;
+import java.util.List;
 
 import org.eclipse.jetty.websocket.api.Session;
+import org.eclipse.jetty.websocket.api.WebSocketException;
 import org.eclipse.jetty.websocket.api.annotations.OnWebSocketClose;
 import org.eclipse.jetty.websocket.api.annotations.OnWebSocketConnect;
+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.WebSocketServlet;
 import org.eclipse.jetty.websocket.servlet.WebSocketServletFactory;
 import org.qortal.api.ApiError;
-import org.qortal.controller.BlockNotifier;
+import org.qortal.controller.Controller;
 import org.qortal.data.block.BlockData;
+import org.qortal.data.block.BlockSummaryData;
+import org.qortal.event.Event;
+import org.qortal.event.EventBus;
+import org.qortal.event.Listener;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryManager;
@@ -20,22 +26,42 @@ import org.qortal.utils.Base58;
 
 @WebSocket
 @SuppressWarnings("serial")
-public class BlocksWebSocket extends WebSocketServlet implements ApiWebSocket {
+public class BlocksWebSocket extends ApiWebSocket implements Listener {
 
 	@Override
 	public void configure(WebSocketServletFactory factory) {
 		factory.register(BlocksWebSocket.class);
+
+		EventBus.INSTANCE.addListener(this::listen);
+	}
+
+	@Override
+	public void listen(Event event) {
+		if (!(event instanceof Controller.NewBlockEvent))
+			return;
+
+		BlockData blockData = ((Controller.NewBlockEvent) event).getBlockData();
+		BlockSummaryData blockSummary = new BlockSummaryData(blockData);
+
+		for (Session session : getSessions())
+			sendBlockSummary(session, blockSummary);
 	}
 
 	@OnWebSocketConnect
+	@Override
 	public void onWebSocketConnect(Session session) {
-		BlockNotifier.Listener listener = blockData -> onNotify(session, blockData);
-		BlockNotifier.getInstance().register(session, listener);
+		super.onWebSocketConnect(session);
 	}
 
 	@OnWebSocketClose
+	@Override
 	public void onWebSocketClose(Session session, int statusCode, String reason) {
-		BlockNotifier.getInstance().deregister(session);
+		super.onWebSocketClose(session, statusCode, reason);
+	}
+
+	@OnWebSocketError
+	public void onWebSocketError(Session session, Throwable throwable) {
+		/* We ignore errors for now, but method here to silence log spam */
 	}
 
 	@OnWebSocketMessage
@@ -53,13 +79,19 @@ public class BlocksWebSocket extends WebSocketServlet implements ApiWebSocket {
 			}
 
 			try (final Repository repository = RepositoryManager.getRepository()) {
-				BlockData blockData = repository.getBlockRepository().fromSignature(signature);
-				if (blockData == null) {
+				int height = repository.getBlockRepository().getHeightFromSignature(signature);
+				if (height == 0) {
 					sendError(session, ApiError.BLOCK_UNKNOWN);
 					return;
 				}
 
-				onNotify(session, blockData);
+				List<BlockSummaryData> blockSummaries = repository.getBlockRepository().getBlockSummaries(height, height);
+				if (blockSummaries == null || blockSummaries.isEmpty()) {
+					sendError(session, ApiError.BLOCK_UNKNOWN);
+					return;
+				}
+
+				sendBlockSummary(session, blockSummaries.get(0));
 			} catch (DataException e) {
 				sendError(session, ApiError.REPOSITORY_ISSUE);
 			}
@@ -82,26 +114,26 @@ public class BlocksWebSocket extends WebSocketServlet implements ApiWebSocket {
 		}
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			BlockData blockData = repository.getBlockRepository().fromHeight(height);
-			if (blockData == null) {
+			List<BlockSummaryData> blockSummaries = repository.getBlockRepository().getBlockSummaries(height, height);
+			if (blockSummaries == null || blockSummaries.isEmpty()) {
 				sendError(session, ApiError.BLOCK_UNKNOWN);
 				return;
 			}
 
-			onNotify(session, blockData);
+			sendBlockSummary(session, blockSummaries.get(0));
 		} catch (DataException e) {
 			sendError(session, ApiError.REPOSITORY_ISSUE);
 		}
 	}
 
-	private void onNotify(Session session, BlockData blockData) {
+	private void sendBlockSummary(Session session, BlockSummaryData blockSummary) {
 		StringWriter stringWriter = new StringWriter();
 
 		try {
-			this.marshall(stringWriter, blockData);
+			marshall(stringWriter, blockSummary);
 
-			session.getRemote().sendString(stringWriter.toString());
-		} catch (IOException e) {
+			session.getRemote().sendStringByFuture(stringWriter.toString());
+		} catch (IOException | WebSocketException e) {
 			// No output this time
 		}
 	}

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

@@ -8,11 +8,12 @@ import java.util.List;
 import java.util.Map;
 
 import org.eclipse.jetty.websocket.api.Session;
+import org.eclipse.jetty.websocket.api.WebSocketException;
 import org.eclipse.jetty.websocket.api.annotations.OnWebSocketClose;
 import org.eclipse.jetty.websocket.api.annotations.OnWebSocketConnect;
+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.WebSocketServlet;
 import org.eclipse.jetty.websocket.servlet.WebSocketServletFactory;
 import org.qortal.controller.ChatNotifier;
 import org.qortal.data.chat.ChatMessage;
@@ -23,7 +24,7 @@ import org.qortal.repository.RepositoryManager;
 
 @WebSocket
 @SuppressWarnings("serial")
-public class ChatMessagesWebSocket extends WebSocketServlet implements ApiWebSocket {
+public class ChatMessagesWebSocket extends ApiWebSocket {
 
 	@Override
 	public void configure(WebSocketServletFactory factory) {
@@ -31,6 +32,7 @@ public class ChatMessagesWebSocket extends WebSocketServlet implements ApiWebSoc
 	}
 
 	@OnWebSocketConnect
+	@Override
 	public void onWebSocketConnect(Session session) {
 		Map<String, List<String>> queryParams = session.getUpgradeRequest().getParameterMap();
 
@@ -85,12 +87,19 @@ public class ChatMessagesWebSocket extends WebSocketServlet implements ApiWebSoc
 	}
 
 	@OnWebSocketClose
+	@Override
 	public void onWebSocketClose(Session session, int statusCode, String reason) {
 		ChatNotifier.getInstance().deregister(session);
 	}
 
+	@OnWebSocketError
+	public void onWebSocketError(Session session, Throwable throwable) {
+		/* ignored */
+	}
+
 	@OnWebSocketMessage
 	public void onWebSocketMessage(Session session, String message) {
+		/* ignored */
 	}
 
 	private void onNotify(Session session, ChatTransactionData chatTransactionData, int txGroupId) {
@@ -123,10 +132,10 @@ public class ChatMessagesWebSocket extends WebSocketServlet implements ApiWebSoc
 		StringWriter stringWriter = new StringWriter();
 
 		try {
-			this.marshall(stringWriter, chatMessages);
+			marshall(stringWriter, chatMessages);
 
-			session.getRemote().sendString(stringWriter.toString());
-		} catch (IOException e) {
+			session.getRemote().sendStringByFuture(stringWriter.toString());
+		} catch (IOException | WebSocketException e) {
 			// No output this time?
 		}
 	}

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

@@ -0,0 +1,244 @@
+package org.qortal.api.websocket;
+
+import java.io.IOException;
+import java.io.StringWriter;
+import java.util.Collections;
+import java.util.EnumMap;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+
+import org.eclipse.jetty.websocket.api.Session;
+import org.eclipse.jetty.websocket.api.annotations.OnWebSocketClose;
+import org.eclipse.jetty.websocket.api.annotations.OnWebSocketConnect;
+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.Controller;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.transaction.PresenceTransactionData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.event.Event;
+import org.qortal.event.EventBus;
+import org.qortal.event.Listener;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.transaction.PresenceTransaction.PresenceType;
+import org.qortal.transaction.Transaction.TransactionType;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+@WebSocket
+@SuppressWarnings("serial")
+public class PresenceWebSocket extends ApiWebSocket implements Listener {
+
+	@XmlAccessorType(XmlAccessType.FIELD)
+	@SuppressWarnings("unused")
+	private static class PresenceInfo {
+		private final PresenceType presenceType;
+		private final String publicKey;
+		private final long timestamp;
+		private final String address;
+
+		protected PresenceInfo() {
+			this.presenceType = null;
+			this.publicKey = null;
+			this.timestamp = 0L;
+			this.address = null;
+		}
+
+		public PresenceInfo(PresenceType presenceType, String pubKey58, long timestamp) {
+			this.presenceType = presenceType;
+			this.publicKey = pubKey58;
+			this.timestamp = timestamp;
+			this.address = Crypto.toAddress(Base58.decode(this.publicKey));
+		}
+
+		public PresenceType getPresenceType() {
+			return this.presenceType;
+		}
+
+		public String getPublicKey() {
+			return this.publicKey;
+		}
+
+		public long getTimestamp() {
+			return this.timestamp;
+		}
+
+		public String getAddress() {
+			return this.address;
+		}
+	}
+
+	/** Outer map key is PresenceType (enum), inner map key is public key in base58, inner map value is timestamp */
+	private static final Map<PresenceType, Map<String, Long>> currentEntries = Collections.synchronizedMap(new EnumMap<>(PresenceType.class));
+
+	/** (Optional) PresenceType used for filtering by that Session. */
+	private static final Map<Session, PresenceType> sessionPresenceTypes = Collections.synchronizedMap(new HashMap<>());
+
+	@Override
+	public void configure(WebSocketServletFactory factory) {
+		factory.register(PresenceWebSocket.class);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			populateCurrentInfo(repository);
+		} catch (DataException e) {
+			// How to fail properly?
+			return;
+		}
+
+		EventBus.INSTANCE.addListener(this::listen);
+	}
+
+	@Override
+	public void listen(Event event) {
+		// We use NewBlockEvent as a proxy for 1-minute timer
+		if (!(event instanceof Controller.NewTransactionEvent) && !(event instanceof Controller.NewBlockEvent))
+			return;
+
+		removeOldEntries();
+
+		if (event instanceof Controller.NewBlockEvent)
+			// We only wanted a chance to cull old entries
+			return;
+
+		TransactionData transactionData = ((Controller.NewTransactionEvent) event).getTransactionData();
+
+		if (transactionData.getType() != TransactionType.PRESENCE)
+			return;
+
+		PresenceTransactionData presenceData = (PresenceTransactionData) transactionData;
+		PresenceType presenceType = presenceData.getPresenceType();
+
+		// Put/replace for this publickey making sure we keep newest timestamp
+		String pubKey58 = Base58.encode(presenceData.getCreatorPublicKey());
+		long ourTimestamp = presenceData.getTimestamp();
+		long computedTimestamp = mergePresence(presenceType, pubKey58, ourTimestamp);
+
+		if (computedTimestamp != ourTimestamp)
+			// nothing changed
+			return;
+
+		List<PresenceInfo> presenceInfo = Collections.singletonList(new PresenceInfo(presenceType, pubKey58, computedTimestamp));
+
+		// Notify sessions
+		for (Session session : getSessions()) {
+			PresenceType sessionPresenceType = sessionPresenceTypes.get(session);
+
+			if (sessionPresenceType == null || sessionPresenceType == presenceType)
+				sendPresenceInfo(session, presenceInfo);
+		}
+	}
+
+	@OnWebSocketConnect
+	@Override
+	public void onWebSocketConnect(Session session) {
+		Map<String, List<String>> queryParams = session.getUpgradeRequest().getParameterMap();
+		List<String> presenceTypes = queryParams.get("presenceType");
+
+		// We only support ONE presenceType
+		String presenceTypeName = presenceTypes == null || presenceTypes.isEmpty() ? null : presenceTypes.get(0);
+
+		PresenceType presenceType = presenceTypeName == null ? null : PresenceType.fromString(presenceTypeName);
+
+		// Make sure that if caller does give a presenceType, that it is a valid/known one.
+		if (presenceTypeName != null && presenceType == null) {
+			session.close(4003, "unknown presenceType: " + presenceTypeName);
+			return;
+		}
+
+		// Save session's requested PresenceType, if given
+		if (presenceType != null)
+			sessionPresenceTypes.put(session, presenceType);
+
+		List<PresenceInfo> presenceInfo;
+
+		synchronized (currentEntries) {
+			presenceInfo = currentEntries.entrySet().stream()
+					.filter(entry -> presenceType == null ? true : entry.getKey() == presenceType)
+					.flatMap(entry -> entry.getValue().entrySet().stream().map(innerEntry -> new PresenceInfo(entry.getKey(), innerEntry.getKey(), innerEntry.getValue())))
+					.collect(Collectors.toList());
+		}
+
+		if (!sendPresenceInfo(session, presenceInfo)) {
+			session.close(4002, "websocket issue");
+			return;
+		}
+
+		super.onWebSocketConnect(session);
+	}
+
+	@OnWebSocketClose
+	@Override
+	public void onWebSocketClose(Session session, int statusCode, String reason) {
+		// clean up
+		sessionPresenceTypes.remove(session);
+
+		super.onWebSocketClose(session, statusCode, reason);
+	}
+
+	@OnWebSocketError
+	public void onWebSocketError(Session session, Throwable throwable) {
+		/* ignored */
+	}
+
+	@OnWebSocketMessage
+	public void onWebSocketMessage(Session session, String message) {
+		/* ignored */
+	}
+
+	private boolean sendPresenceInfo(Session session, List<PresenceInfo> presenceInfo) {
+		try {
+			StringWriter stringWriter = new StringWriter();
+			marshall(stringWriter, presenceInfo);
+
+			String output = stringWriter.toString();
+			session.getRemote().sendStringByFuture(output);
+		} catch (IOException e) {
+			// No output this time?
+			return false;
+		}
+
+		return true;
+	}
+
+	private static void populateCurrentInfo(Repository repository) throws DataException {
+		// We want ALL PRESENCE transactions
+
+		List<TransactionData> presenceTransactionsData = repository.getTransactionRepository().getUnconfirmedTransactions(TransactionType.PRESENCE, null);
+
+		for (TransactionData transactionData : presenceTransactionsData) {
+			PresenceTransactionData presenceData = (PresenceTransactionData) transactionData;
+
+			PresenceType presenceType = presenceData.getPresenceType();
+
+			// Put/replace for this publickey making sure we keep newest timestamp
+			String pubKey58 = Base58.encode(presenceData.getCreatorPublicKey());
+			long ourTimestamp = presenceData.getTimestamp();
+
+			mergePresence(presenceType, pubKey58, ourTimestamp);
+		}
+	}
+
+	private static long mergePresence(PresenceType presenceType, String pubKey58, long ourTimestamp) {
+		Map<String, Long> typedPubkeyTimestamps = currentEntries.computeIfAbsent(presenceType, someType -> Collections.synchronizedMap(new HashMap<>()));
+		return typedPubkeyTimestamps.compute(pubKey58, (somePubKey58, currentTimestamp) -> (currentTimestamp == null || currentTimestamp < ourTimestamp) ? ourTimestamp : currentTimestamp);
+	}
+
+	private static void removeOldEntries() {
+		long now = NTP.getTime();
+
+		currentEntries.entrySet().forEach(entry -> {
+			long expiryThreshold = now - entry.getKey().getLifetime();
+			entry.getValue().entrySet().removeIf(pubkeyTimestamp -> pubkeyTimestamp.getValue() < expiryThreshold);
+		});
+	}
+
+}

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

@@ -0,0 +1,157 @@
+package org.qortal.api.websocket;
+
+import java.io.IOException;
+import java.io.StringWriter;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import org.eclipse.jetty.websocket.api.Session;
+import org.eclipse.jetty.websocket.api.annotations.OnWebSocketClose;
+import org.eclipse.jetty.websocket.api.annotations.OnWebSocketConnect;
+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.TradeBot;
+import org.qortal.crosschain.SupportedBlockchain;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.event.Event;
+import org.qortal.event.EventBus;
+import org.qortal.event.Listener;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.utils.Base58;
+
+@WebSocket
+@SuppressWarnings("serial")
+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, Integer> PREVIOUS_STATES = new HashMap<>();
+
+	private static final Map<Session, String> sessionBlockchain = Collections.synchronizedMap(new HashMap<>());
+
+	@Override
+	public void configure(WebSocketServletFactory factory) {
+		factory.register(TradeBotWebSocket.class);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			List<TradeBotData> tradeBotEntries = repository.getCrossChainRepository().getAllTradeBotData();
+			if (tradeBotEntries == null)
+				// How do we properly fail here?
+				return;
+
+			PREVIOUS_STATES.putAll(tradeBotEntries.stream().collect(Collectors.toMap(entry -> Base58.encode(entry.getTradePrivateKey()), TradeBotData::getStateValue)));
+		} catch (DataException e) {
+			// No output this time
+		}
+
+		EventBus.INSTANCE.addListener(this::listen);
+	}
+
+	@Override
+	public void listen(Event event) {
+		if (!(event instanceof TradeBot.StateChangeEvent))
+			return;
+
+		TradeBotData tradeBotData = ((TradeBot.StateChangeEvent) event).getTradeBotData();
+		String tradePrivateKey58 = Base58.encode(tradeBotData.getTradePrivateKey());
+
+		synchronized (PREVIOUS_STATES) {
+			Integer previousStateValue = PREVIOUS_STATES.get(tradePrivateKey58);
+			if (previousStateValue != null && previousStateValue == tradeBotData.getStateValue())
+				// Not changed
+				return;
+
+			PREVIOUS_STATES.put(tradePrivateKey58, tradeBotData.getStateValue());
+		}
+
+		List<TradeBotData> tradeBotEntries = Collections.singletonList(tradeBotData);
+
+		for (Session session : getSessions()) {
+			// Only send if this session has this/no preferred blockchain
+			String preferredBlockchain = sessionBlockchain.get(session);
+
+			if (preferredBlockchain == null || preferredBlockchain.equals(tradeBotData.getForeignBlockchain()))
+				sendEntries(session, tradeBotEntries);
+		}
+	}
+
+	@OnWebSocketConnect
+	@Override
+	public void onWebSocketConnect(Session session) {
+		Map<String, List<String>> queryParams = session.getUpgradeRequest().getParameterMap();
+
+		List<String> foreignBlockchains = queryParams.get("foreignBlockchain");
+		final String foreignBlockchain = foreignBlockchains == null ? null : foreignBlockchains.get(0);
+
+		// Make sure blockchain (if any) is valid
+		if (foreignBlockchain != null && SupportedBlockchain.fromString(foreignBlockchain) == null) {
+			session.close(4003, "unknown blockchain: " + foreignBlockchain);
+			return;
+		}
+
+		// save session's preferred blockchain (if any)
+		sessionBlockchain.put(session, foreignBlockchain);
+
+		// Send all known trade-bot entries
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			List<TradeBotData> tradeBotEntries = repository.getCrossChainRepository().getAllTradeBotData();
+
+			// Optional filtering
+			if (foreignBlockchain != null)
+				tradeBotEntries = tradeBotEntries.stream()
+						.filter(tradeBotData -> tradeBotData.getForeignBlockchain().equals(foreignBlockchain))
+						.collect(Collectors.toList());
+
+			if (!sendEntries(session, tradeBotEntries)) {
+				session.close(4002, "websocket issue");
+				return;
+			}
+		} catch (DataException e) {
+			session.close(4001, "repository issue fetching trade-bot entries");
+			return;
+		}
+
+		super.onWebSocketConnect(session);
+	}
+
+	@OnWebSocketClose
+	@Override
+	public void onWebSocketClose(Session session, int statusCode, String reason) {
+		// clean up
+		sessionBlockchain.remove(session);
+
+		super.onWebSocketClose(session, statusCode, reason);
+	}
+
+	@OnWebSocketError
+	public void onWebSocketError(Session session, Throwable throwable) {
+		/* ignored */
+	}
+
+	@OnWebSocketMessage
+	public void onWebSocketMessage(Session session, String message) {
+		/* ignored */
+	}
+
+	private boolean sendEntries(Session session, List<TradeBotData> tradeBotEntries) {
+		try {
+			StringWriter stringWriter = new StringWriter();
+			marshall(stringWriter, tradeBotEntries);
+
+			String output = stringWriter.toString();
+			session.getRemote().sendStringByFuture(output);
+		} catch (IOException e) {
+			// No output this time?
+			return false;
+		}
+
+		return true;
+	}
+
+}

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

@@ -0,0 +1,351 @@
+package org.qortal.api.websocket;
+
+import java.io.IOException;
+import java.io.StringWriter;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Predicate;
+import java.util.function.Supplier;
+import java.util.stream.Collectors;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.eclipse.jetty.websocket.api.Session;
+import org.eclipse.jetty.websocket.api.annotations.OnWebSocketClose;
+import org.eclipse.jetty.websocket.api.annotations.OnWebSocketConnect;
+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.api.model.CrossChainOfferSummary;
+import org.qortal.controller.Controller;
+import org.qortal.crosschain.SupportedBlockchain;
+import org.qortal.crosschain.ACCT;
+import org.qortal.crosschain.AcctMode;
+import org.qortal.data.at.ATStateData;
+import org.qortal.data.block.BlockData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.event.Event;
+import org.qortal.event.EventBus;
+import org.qortal.event.Listener;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.utils.ByteArray;
+import org.qortal.utils.NTP;
+
+@WebSocket
+@SuppressWarnings("serial")
+public class TradeOffersWebSocket extends ApiWebSocket implements Listener {
+
+	private static final Logger LOGGER = LogManager.getLogger(TradeOffersWebSocket.class);
+
+	private static class CachedOfferInfo {
+		public final Map<String, AcctMode> previousAtModes = new HashMap<>();
+
+		// OFFERING
+		public final Map<String, CrossChainOfferSummary> currentSummaries = new HashMap<>();
+		// REDEEMED/REFUNDED/CANCELLED
+		public final Map<String, CrossChainOfferSummary> historicSummaries = new HashMap<>();
+	}
+	// Manual synchronization
+	private static final Map<String, CachedOfferInfo> cachedInfoByBlockchain = new HashMap<>();
+
+	private static final Predicate<CrossChainOfferSummary> isHistoric = offerSummary
+			-> offerSummary.getMode() == AcctMode.REDEEMED
+			|| offerSummary.getMode() == AcctMode.REFUNDED
+			|| offerSummary.getMode() == AcctMode.CANCELLED;
+
+	private static final Map<Session, String> sessionBlockchain = Collections.synchronizedMap(new HashMap<>());
+
+	@Override
+	public void configure(WebSocketServletFactory factory) {
+		factory.register(TradeOffersWebSocket.class);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			populateCurrentSummaries(repository);
+
+			populateHistoricSummaries(repository);
+		} catch (DataException e) {
+			// How to fail properly?
+			return;
+		}
+
+		EventBus.INSTANCE.addListener(this::listen);
+	}
+
+	@Override
+	public void listen(Event event) {
+		if (!(event instanceof Controller.NewBlockEvent))
+			return;
+
+		BlockData blockData = ((Controller.NewBlockEvent) event).getBlockData();
+
+		// Process any new info
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			// Find any new/changed trade ATs since this block
+			final Boolean isFinished = null;
+			final Integer dataByteOffset = null;
+			final Long expectedValue = null;
+			final Integer minimumFinalHeight = blockData.getHeight();
+
+			for (SupportedBlockchain blockchain : SupportedBlockchain.values()) {
+				Map<ByteArray, Supplier<ACCT>> acctsByCodeHash = SupportedBlockchain.getFilteredAcctMap(blockchain);
+
+				List<CrossChainOfferSummary> crossChainOfferSummaries = new ArrayList<>();
+
+				synchronized (cachedInfoByBlockchain) {
+					CachedOfferInfo cachedInfo = cachedInfoByBlockchain.computeIfAbsent(blockchain.name(), k -> new CachedOfferInfo());
+
+					for (Map.Entry<ByteArray, Supplier<ACCT>> acctInfo : acctsByCodeHash.entrySet()) {
+						byte[] codeHash = acctInfo.getKey().value;
+						ACCT acct = acctInfo.getValue().get();
+
+						List<ATStateData> atStates = repository.getATRepository().getMatchingFinalATStates(codeHash,
+								isFinished, dataByteOffset, expectedValue, minimumFinalHeight,
+								null, null, null);
+
+						crossChainOfferSummaries.addAll(produceSummaries(repository, acct, atStates, blockData.getTimestamp()));
+					}
+
+					// Remove any entries unchanged from last time
+					crossChainOfferSummaries.removeIf(offerSummary -> cachedInfo.previousAtModes.get(offerSummary.getQortalAtAddress()) == offerSummary.getMode());
+
+					// Skip to next blockchain if nothing has changed (for this blockchain)
+					if (crossChainOfferSummaries.isEmpty())
+						continue;
+
+					// Update
+					for (CrossChainOfferSummary offerSummary : crossChainOfferSummaries) {
+						String offerAtAddress = offerSummary.getQortalAtAddress();
+
+						cachedInfo.previousAtModes.put(offerAtAddress, offerSummary.getMode());
+						LOGGER.trace(() -> String.format("Block height: %d, AT: %s, mode: %s", blockData.getHeight(), offerAtAddress, offerSummary.getMode().name()));
+
+						switch (offerSummary.getMode()) {
+							case OFFERING:
+								cachedInfo.currentSummaries.put(offerAtAddress, offerSummary);
+								cachedInfo.historicSummaries.remove(offerAtAddress);
+								break;
+
+							case REDEEMED:
+							case REFUNDED:
+							case CANCELLED:
+								cachedInfo.currentSummaries.remove(offerAtAddress);
+								cachedInfo.historicSummaries.put(offerAtAddress, offerSummary);
+								break;
+
+							case TRADING:
+								cachedInfo.currentSummaries.remove(offerAtAddress);
+								cachedInfo.historicSummaries.remove(offerAtAddress);
+								break;
+						}
+					}
+
+					// Remove any historic offers that are over 24 hours old
+					final long tooOldTimestamp = NTP.getTime() - 24 * 60 * 60 * 1000L;
+					cachedInfo.historicSummaries.values().removeIf(historicSummary -> historicSummary.getTimestamp() < tooOldTimestamp);
+				}
+
+				// Notify sessions
+				for (Session session : getSessions()) {
+					// Only send if this session has this/no preferred blockchain
+					String preferredBlockchain = sessionBlockchain.get(session);
+
+					if (preferredBlockchain == null || preferredBlockchain.equals(blockchain.name()))
+						sendOfferSummaries(session, crossChainOfferSummaries);
+				}
+
+			}
+		} catch (DataException e) {
+			// No output this time
+		}
+	}
+
+	@OnWebSocketConnect
+	@Override
+	public void onWebSocketConnect(Session session) {
+		Map<String, List<String>> queryParams = session.getUpgradeRequest().getParameterMap();
+		final boolean includeHistoric = queryParams.get("includeHistoric") != null;
+
+		List<String> foreignBlockchains = queryParams.get("foreignBlockchain");
+		final String foreignBlockchain = foreignBlockchains == null ? null : foreignBlockchains.get(0);
+
+		// Make sure blockchain (if any) is valid
+		if (foreignBlockchain != null && SupportedBlockchain.fromString(foreignBlockchain) == null) {
+			session.close(4003, "unknown blockchain: " + foreignBlockchain);
+			return;
+		}
+
+		// Save session's preferred blockchain, if given
+		if (foreignBlockchain != null)
+			sessionBlockchain.put(session, foreignBlockchain);
+
+		List<CrossChainOfferSummary> crossChainOfferSummaries = new ArrayList<>();
+
+		synchronized (cachedInfoByBlockchain) {
+			Collection<CachedOfferInfo> cachedInfos;
+
+			if (foreignBlockchain == null)
+				// No preferred blockchain, so iterate through all of them
+				cachedInfos = cachedInfoByBlockchain.values();
+			else
+				cachedInfos = Collections.singleton(cachedInfoByBlockchain.computeIfAbsent(foreignBlockchain, k -> new CachedOfferInfo()));
+
+			for (CachedOfferInfo cachedInfo : cachedInfos) {
+				crossChainOfferSummaries.addAll(cachedInfo.currentSummaries.values());
+
+				if (includeHistoric)
+					crossChainOfferSummaries.addAll(cachedInfo.historicSummaries.values());
+			}
+		}
+
+		if (!sendOfferSummaries(session, crossChainOfferSummaries)) {
+			session.close(4002, "websocket issue");
+			return;
+		}
+
+		super.onWebSocketConnect(session);
+	}
+
+	@OnWebSocketClose
+	@Override
+	public void onWebSocketClose(Session session, int statusCode, String reason) {
+		// clean up
+		sessionBlockchain.remove(session);
+
+		super.onWebSocketClose(session, statusCode, reason);
+	}
+
+	@OnWebSocketError
+	public void onWebSocketError(Session session, Throwable throwable) {
+		/* ignored */
+	}
+
+	@OnWebSocketMessage
+	public void onWebSocketMessage(Session session, String message) {
+		/* ignored */
+	}
+
+	private boolean sendOfferSummaries(Session session, List<CrossChainOfferSummary> crossChainOfferSummaries) {
+		try {
+			StringWriter stringWriter = new StringWriter();
+			marshall(stringWriter, crossChainOfferSummaries);
+
+			String output = stringWriter.toString();
+			session.getRemote().sendStringByFuture(output);
+		} catch (IOException e) {
+			// No output this time?
+			return false;
+		}
+
+		return true;
+	}
+
+	private static void populateCurrentSummaries(Repository repository) throws DataException {
+		// We want ALL OFFERING trades
+		Boolean isFinished = Boolean.FALSE;
+		Long expectedValue = (long) AcctMode.OFFERING.value;
+		Integer minimumFinalHeight = null;
+
+		for (SupportedBlockchain blockchain : SupportedBlockchain.values()) {
+			Map<ByteArray, Supplier<ACCT>> acctsByCodeHash = SupportedBlockchain.getFilteredAcctMap(blockchain);
+
+			CachedOfferInfo cachedInfo = cachedInfoByBlockchain.computeIfAbsent(blockchain.name(), k -> new CachedOfferInfo());
+
+			for (Map.Entry<ByteArray, Supplier<ACCT>> acctInfo : acctsByCodeHash.entrySet()) {
+				byte[] codeHash = acctInfo.getKey().value;
+				ACCT acct = acctInfo.getValue().get();
+
+				Integer dataByteOffset = acct.getModeByteOffset();
+				List<ATStateData> initialAtStates = repository.getATRepository().getMatchingFinalATStates(codeHash,
+					isFinished, dataByteOffset, expectedValue, minimumFinalHeight,
+					null, null, null);
+
+				if (initialAtStates == null)
+					throw new DataException("Couldn't fetch current trades from repository");
+
+				// Save initial AT modes
+				cachedInfo.previousAtModes.putAll(initialAtStates.stream().collect(Collectors.toMap(ATStateData::getATAddress, atState -> AcctMode.OFFERING)));
+
+				// Convert to offer summaries
+				cachedInfo.currentSummaries.putAll(produceSummaries(repository, acct, initialAtStates, null).stream()
+										.collect(Collectors.toMap(CrossChainOfferSummary::getQortalAtAddress, offerSummary -> offerSummary)));
+			}
+		}
+	}
+
+	private static void populateHistoricSummaries(Repository repository) throws DataException {
+		// We want REDEEMED/REFUNDED/CANCELLED trades over the last 24 hours
+		long timestamp = System.currentTimeMillis() - 24 * 60 * 60 * 1000L;
+		int minimumFinalHeight = repository.getBlockRepository().getHeightFromTimestamp(timestamp);
+
+		if (minimumFinalHeight == 0)
+			throw new DataException("Couldn't fetch block timestamp from repository");
+
+		Boolean isFinished = Boolean.TRUE;
+		Integer dataByteOffset = null;
+		Long expectedValue = null;
+		++minimumFinalHeight; // because height is just *before* timestamp
+
+		for (SupportedBlockchain blockchain : SupportedBlockchain.values()) {
+			Map<ByteArray, Supplier<ACCT>> acctsByCodeHash = SupportedBlockchain.getFilteredAcctMap(blockchain);
+
+			CachedOfferInfo cachedInfo = cachedInfoByBlockchain.computeIfAbsent(blockchain.name(), k -> new CachedOfferInfo());
+
+			for (Map.Entry<ByteArray, Supplier<ACCT>> acctInfo : acctsByCodeHash.entrySet()) {
+				byte[] codeHash = acctInfo.getKey().value;
+				ACCT acct = acctInfo.getValue().get();
+
+				List<ATStateData> historicAtStates = repository.getATRepository().getMatchingFinalATStates(codeHash,
+					isFinished, dataByteOffset, expectedValue, minimumFinalHeight,
+					null, null, null);
+
+				if (historicAtStates == null)
+					throw new DataException("Couldn't fetch historic trades from repository");
+
+				for (ATStateData historicAtState : historicAtStates) {
+					CrossChainOfferSummary historicOfferSummary = produceSummary(repository, acct, historicAtState, null);
+
+					if (!isHistoric.test(historicOfferSummary))
+						continue;
+
+					// Add summary to initial burst
+					cachedInfo.historicSummaries.put(historicOfferSummary.getQortalAtAddress(), historicOfferSummary);
+
+					// Save initial AT mode
+					cachedInfo.previousAtModes.put(historicOfferSummary.getQortalAtAddress(), historicOfferSummary.getMode());
+				}
+			}
+		}
+	}
+
+	private static CrossChainOfferSummary produceSummary(Repository repository, ACCT acct, ATStateData atState, Long timestamp) throws DataException {
+		CrossChainTradeData crossChainTradeData = acct.populateTradeData(repository, atState);
+
+		long atStateTimestamp;
+
+		if (crossChainTradeData.mode == AcctMode.OFFERING)
+			// We want when trade was created, not when it was last updated
+			atStateTimestamp = crossChainTradeData.creationTimestamp;
+		else
+			atStateTimestamp = timestamp != null ? timestamp : repository.getBlockRepository().getTimestampFromHeight(atState.getHeight());
+
+		return new CrossChainOfferSummary(crossChainTradeData, atStateTimestamp);
+	}
+
+	private static List<CrossChainOfferSummary> produceSummaries(Repository repository, ACCT acct, List<ATStateData> atStates, Long timestamp) throws DataException {
+		List<CrossChainOfferSummary> offerSummaries = new ArrayList<>();
+
+		for (ATStateData atState : atStates)
+			offerSummaries.add(produceSummary(repository, acct, atState, timestamp));
+
+		return offerSummaries;
+	}
+
+}

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

@@ -51,16 +51,17 @@ public class AT {
 
 		MachineState machineState = new MachineState(api, loggerFactory, deployATTransactionData.getCreationBytes());
 
-		byte[] codeHash = Crypto.digest(machineState.getCodeBytes());
+		byte[] codeBytes = machineState.getCodeBytes();
+		byte[] codeHash = Crypto.digest(codeBytes);
 
-		this.atData = new ATData(atAddress, creatorPublicKey, creation, machineState.version, assetId, machineState.getCodeBytes(), codeHash,
+		this.atData = new ATData(atAddress, creatorPublicKey, creation, machineState.version, assetId, codeBytes, codeHash,
 				machineState.isSleeping(), machineState.getSleepUntilHeight(), machineState.isFinished(), machineState.hadFatalError(),
 				machineState.isFrozen(), machineState.getFrozenBalance());
 
 		byte[] stateData = machineState.toBytes();
 		byte[] stateHash = Crypto.digest(stateData);
 
-		this.atStateData = new ATStateData(atAddress, height, creation, stateData, stateHash, 0L, true);
+		this.atStateData = new ATStateData(atAddress, height, stateData, stateHash, 0L, true);
 	}
 
 	// Getters / setters
@@ -106,23 +107,18 @@ public class AT {
 			throw new DataException(String.format("Uncaught exception while running AT '%s'", atAddress), e);
 		}
 
-		long creation = this.atData.getCreation();
 		byte[] stateData = state.toBytes();
 		byte[] stateHash = Crypto.digest(stateData);
 		long atFees = api.calcFinalFees(state);
 
-		this.atStateData = new ATStateData(atAddress, blockHeight, creation, stateData, stateHash, atFees, false);
+		this.atStateData = new ATStateData(atAddress, blockHeight, stateData, stateHash, atFees, false);
 
 		return api.getTransactions();
 	}
 
 	public void update(int blockHeight, long blockTimestamp) throws DataException {
-		// [Re]create AT machine state using AT state data or from scratch as applicable
-		QortalATAPI api = new QortalATAPI(repository, this.atData, blockTimestamp);
-		QortalAtLoggerFactory loggerFactory = QortalAtLoggerFactory.getInstance();
-
-		byte[] codeBytes = this.atData.getCodeBytes();
-		MachineState state = MachineState.fromBytes(api, loggerFactory, this.atStateData.getStateData(), codeBytes);
+		// Extract minimal/flags-only AT machine state using AT state data
+		MachineState state = MachineState.flagsOnlyfromBytes(this.atStateData.getStateData());
 
 		// Save latest AT state data
 		this.repository.getATRepository().save(this.atStateData);
@@ -151,12 +147,8 @@ public class AT {
 		if (previousStateData == null)
 			throw new DataException("Can't find previous AT state data for " + atAddress);
 
-		// [Re]create AT machine state using AT state data or from scratch as applicable
-		QortalATAPI api = new QortalATAPI(repository, this.atData, blockTimestamp);
-		QortalAtLoggerFactory loggerFactory = QortalAtLoggerFactory.getInstance();
-
-		byte[] codeBytes = this.atData.getCodeBytes();
-		MachineState state = MachineState.fromBytes(api, loggerFactory, previousStateData.getStateData(), codeBytes);
+		// Extract minimal/flags-only AT machine state using AT state data
+		MachineState state = MachineState.flagsOnlyfromBytes(previousStateData.getStateData());
 
 		// Update AT info in repository
 		this.atData.setIsSleeping(state.isSleeping());

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

@@ -17,7 +17,6 @@ import org.qortal.account.Account;
 import org.qortal.account.NullAccount;
 import org.qortal.account.PublicKeyAccount;
 import org.qortal.asset.Asset;
-import org.qortal.block.Block;
 import org.qortal.block.BlockChain;
 import org.qortal.block.BlockChain.CiyamAtSettings;
 import org.qortal.crypto.Crypto;
@@ -30,13 +29,13 @@ import org.qortal.data.transaction.MessageTransactionData;
 import org.qortal.data.transaction.PaymentTransactionData;
 import org.qortal.data.transaction.TransactionData;
 import org.qortal.group.Group;
-import org.qortal.repository.BlockRepository;
+import org.qortal.repository.ATRepository;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.transaction.AtTransaction;
-import org.qortal.transaction.Transaction;
 import org.qortal.transaction.Transaction.TransactionType;
 import org.qortal.utils.Base58;
+import org.qortal.utils.BitTwiddling;
 
 import com.google.common.primitives.Bytes;
 
@@ -133,9 +132,9 @@ public class QortalATAPI extends API {
 
 			byte[] signature = blockSummaries.get(0).getSignature();
 			// Save some of minter's signature and transactions signature, so middle 24 bytes of the full 128 byte signature.
-			this.setA2(state, fromBytes(signature, 52));
-			this.setA3(state, fromBytes(signature, 60));
-			this.setA4(state, fromBytes(signature, 68));
+			this.setA2(state, BitTwiddling.longFromBEBytes(signature, 52));
+			this.setA3(state, BitTwiddling.longFromBEBytes(signature, 60));
+			this.setA4(state, BitTwiddling.longFromBEBytes(signature, 68));
 		} catch (DataException e) {
 			throw new RuntimeException("AT API unable to fetch previous block?", e);
 		}
@@ -147,61 +146,33 @@ public class QortalATAPI extends API {
 		String atAddress = this.atData.getATAddress();
 
 		int height = timestamp.blockHeight;
-		int sequence = timestamp.transactionSequence + 1;
+		int sequence = timestamp.transactionSequence;
 
-		BlockRepository blockRepository = this.getRepository().getBlockRepository();
+		if (state.getCurrentBlockHeight() < BlockChain.getInstance().getAtFindNextTransactionFixHeight())
+			// Off-by-one bug still in effect
+			sequence += 1;
 
+		ATRepository.NextTransactionInfo nextTransactionInfo;
 		try {
-			int currentHeight = blockRepository.getBlockchainHeight();
-			List<Transaction> blockTransactions = null;
-
-			while (height <= currentHeight) {
-				if (blockTransactions == null) {
-					BlockData blockData = blockRepository.fromHeight(height);
-
-					if (blockData == null)
-						throw new DataException("Unable to fetch block " + height + " from repository?");
-
-					Block block = new Block(this.getRepository(), blockData);
-
-					blockTransactions = block.getTransactions();
-				}
-
-				// No more transactions in this block? Try next block
-				if (sequence >= blockTransactions.size()) {
-					++height;
-					sequence = 0;
-					blockTransactions = null;
-					continue;
-				}
-
-				Transaction transaction = blockTransactions.get(sequence);
-
-				// Transaction needs to be sent to specified recipient
-				List<String> recipientAddresses = transaction.getRecipientAddresses();
-				if (recipientAddresses.contains(atAddress)) {
-					// Found a transaction
-
-					this.setA1(state, new Timestamp(height, timestamp.blockchainId, sequence).longValue());
-
-					// Copy transaction's partial signature into the other three A fields for future verification that it's the same transaction
-					byte[] signature = transaction.getTransactionData().getSignature();
-					this.setA2(state, fromBytes(signature, 8));
-					this.setA3(state, fromBytes(signature, 16));
-					this.setA4(state, fromBytes(signature, 24));
-
-					return;
-				}
-
-				// Transaction wasn't for us - keep going
-				++sequence;
-			}
-
-			// No more transactions - zero A and exit
-			this.zeroA(state);
+			nextTransactionInfo = this.getRepository().getATRepository().findNextTransaction(atAddress, height, sequence);
 		} catch (DataException e) {
 			throw new RuntimeException("AT API unable to fetch next transaction?", e);
 		}
+
+		if (nextTransactionInfo == null) {
+			// No more transactions for AT at this time - zero A and exit
+			this.zeroA(state);
+			return;
+		}
+
+		// Found a transaction
+
+		this.setA1(state, new Timestamp(nextTransactionInfo.height, timestamp.blockchainId, nextTransactionInfo.sequence).longValue());
+
+		// Copy transaction's partial signature into the other three A fields for future verification that it's the same transaction
+		this.setA2(state, BitTwiddling.longFromBEBytes(nextTransactionInfo.signature, 8));
+		this.setA3(state, BitTwiddling.longFromBEBytes(nextTransactionInfo.signature, 16));
+		this.setA4(state, BitTwiddling.longFromBEBytes(nextTransactionInfo.signature, 24));
 	}
 
 	@Override
@@ -282,7 +253,7 @@ public class QortalATAPI extends API {
 
 				byte[] hash = Crypto.digest(input);
 
-				return fromBytes(hash, 0);
+				return BitTwiddling.longFromBEBytes(hash, 0);
 			} catch (DataException e) {
 				throw new RuntimeException("AT API unable to fetch latest block from repository?", e);
 			}
@@ -296,30 +267,14 @@ public class QortalATAPI extends API {
 
 		TransactionData transactionData = this.getTransactionFromA(state);
 
-		byte[] messageData = null;
-
-		switch (transactionData.getType()) {
-			case MESSAGE:
-				messageData = ((MessageTransactionData) transactionData).getData();
-				break;
-
-			case AT:
-				messageData = ((ATTransactionData) transactionData).getMessage();
-				break;
-
-			default:
-				return;
-		}
-
-		// Check data length is appropriate, i.e. not larger than B
-		if (messageData.length > 4 * 8)
-			return;
+		byte[] messageData = this.getMessageFromTransaction(transactionData);
 
 		// Pad messageData to fit B
-		byte[] paddedMessageData = Bytes.ensureCapacity(messageData, 4 * 8, 0);
+		if (messageData.length < 4 * 8)
+			messageData = Bytes.ensureCapacity(messageData, 4 * 8, 0);
 
 		// Endian must be correct here so that (for example) a SHA256 message can be compared to one generated locally
-		this.setB(state, paddedMessageData);
+		this.setB(state, messageData);
 	}
 
 	@Override
@@ -457,12 +412,6 @@ public class QortalATAPI extends API {
 
 	// Utility methods
 
-	/** Convert part of little-endian byte[] to long */
-	/* package */ static long fromBytes(byte[] bytes, int start) {
-		return (bytes[start] & 0xffL) | (bytes[start + 1] & 0xffL) << 8 | (bytes[start + 2] & 0xffL) << 16 | (bytes[start + 3] & 0xffL) << 24
-				| (bytes[start + 4] & 0xffL) << 32 | (bytes[start + 5] & 0xffL) << 40 | (bytes[start + 6] & 0xffL) << 48 | (bytes[start + 7] & 0xffL) << 56;
-	}
-
 	/** Returns partial transaction signature, used to verify we're operating on the same transaction and not naively using block height & sequence. */
 	public static byte[] partialSignature(byte[] fullSignature) {
 		return Arrays.copyOfRange(fullSignature, 8, 32);
@@ -473,7 +422,7 @@ public class QortalATAPI extends API {
 		// Compare end of transaction's signature against A2 thru A4
 		byte[] sig = transactionData.getSignature();
 
-		if (this.getA2(state) != fromBytes(sig, 8) || this.getA3(state) != fromBytes(sig, 16) || this.getA4(state) != fromBytes(sig, 24))
+		if (this.getA2(state) != BitTwiddling.longFromBEBytes(sig, 8) || this.getA3(state) != BitTwiddling.longFromBEBytes(sig, 16) || this.getA4(state) != BitTwiddling.longFromBEBytes(sig, 24))
 			throw new IllegalStateException("Transaction signature in A no longer matches signature from repository");
 	}
 
@@ -497,6 +446,20 @@ public class QortalATAPI extends API {
 		}
 	}
 
+	/** Returns message data from transaction. */
+	/*package*/ byte[] getMessageFromTransaction(TransactionData transactionData) {
+		switch (transactionData.getType()) {
+			case MESSAGE:
+				return ((MessageTransactionData) transactionData).getData();
+
+			case AT:
+				return ((ATTransactionData) transactionData).getMessage();
+
+			default:
+				return null;
+		}
+	}
+
 	/** Returns AT's account */
 	/* package */ Account getATAccount() {
 		return new Account(this.repository, this.atData.getATAddress());
@@ -563,4 +526,8 @@ public class QortalATAPI extends API {
 		super.setB(state, bBytes);
 	}
 
+	protected void zeroB(MachineState state) {
+		super.zeroB(state);
+	}
+
 }

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

@@ -691,6 +691,11 @@ public final class QortalAtLogger extends ExtendedLoggerWrapper implements org.c
         logger.logIfEnabled(FQCN, ERROR, null, msgSupplier, (Throwable) null);
     }
 
+    /** Java 8 version */
+    public void error(final java.util.function.Supplier<String> msgSupplier) {
+        logger.logIfEnabled(FQCN, ERROR, null, () -> msgSupplier.get(), (Throwable) null);
+    }
+
     /**
      * Logs a message (only to be constructed if the logging level is the {@code ERROR}
      * level) including the stack trace of the {@link Throwable} <code>t</code> passed as parameter.
@@ -1375,6 +1380,11 @@ public final class QortalAtLogger extends ExtendedLoggerWrapper implements org.c
         logger.logIfEnabled(FQCN, DEBUG, null, msgSupplier, (Throwable) null);
     }
 
+    /** Java 8 version */
+    public void debug(final java.util.function.Supplier<String> msgSupplier) {
+        logger.logIfEnabled(FQCN, DEBUG, null, () -> msgSupplier.get(), (Throwable) null);
+    }
+
     /**
      * Logs a message (only to be constructed if the logging level is the {@code DEBUG}
      * level) including the stack trace of the {@link Throwable} <code>t</code> passed as parameter.
@@ -2059,6 +2069,11 @@ public final class QortalAtLogger extends ExtendedLoggerWrapper implements org.c
         logger.logIfEnabled(FQCN, ECHO, null, msgSupplier, (Throwable) null);
     }
 
+    /** Java 8 version */
+    public void echo(final java.util.function.Supplier<String> msgSupplier) {
+        logger.logIfEnabled(FQCN, ECHO, null, () -> msgSupplier.get(), (Throwable) null);
+    }
+
     /**
      * Logs a message (only to be constructed if the logging level is the {@code ECHO}
      * level) including the stack trace of the {@link Throwable} <code>t</code> passed as parameter.

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

@@ -10,8 +10,9 @@ import org.ciyam.at.ExecutionException;
 import org.ciyam.at.FunctionData;
 import org.ciyam.at.IllegalFunctionCodeException;
 import org.ciyam.at.MachineState;
-import org.qortal.crosschain.BTC;
+import org.qortal.crosschain.Bitcoin;
 import org.qortal.crypto.Crypto;
+import org.qortal.data.transaction.TransactionData;
 import org.qortal.settings.Settings;
 
 /**
@@ -22,8 +23,70 @@ import org.qortal.settings.Settings;
  */
 public enum QortalFunctionCode {
 	/**
-	 * <tt>0x0510</tt><br>
-	 * Convert address in B to 20-byte value in LSB of B1, and all of B2 & B3.
+	 * Returns length of message data from transaction in A.<br>
+	 * <tt>0x0501</tt><br>
+	 * If transaction has no 'message', returns -1.
+	 */
+	GET_MESSAGE_LENGTH_FROM_TX_IN_A(0x0501, 0, true) {
+		@Override
+		protected void postCheckExecute(FunctionData functionData, MachineState state, short rawFunctionCode) throws ExecutionException {
+			QortalATAPI api = (QortalATAPI) state.getAPI();
+
+			TransactionData transactionData = api.getTransactionFromA(state);
+
+			byte[] messageData = api.getMessageFromTransaction(transactionData);
+
+			if (messageData == null)
+				functionData.returnValue = -1L;
+			else
+				functionData.returnValue = (long) messageData.length;
+		}
+	},
+	/**
+	 * Put offset 'message' from transaction in A into B<br>
+	 * <tt>0x0502 start-offset</tt><br>
+	 * Copies up to 32 bytes of message data, starting at <tt>start-offset</tt> into B.<br>
+	 * If transaction has no 'message', or <tt>start-offset</tt> out of bounds, then zero B<br>
+	 * Example 'message' could be 256-bit shared secret
+	 */
+	PUT_PARTIAL_MESSAGE_FROM_TX_IN_A_INTO_B(0x0502, 1, false) {
+		@Override
+		protected void postCheckExecute(FunctionData functionData, MachineState state, short rawFunctionCode) throws ExecutionException {
+			QortalATAPI api = (QortalATAPI) state.getAPI();
+
+			// In case something goes wrong, or we don't have enough message data.
+			api.zeroB(state);
+
+			if (functionData.value1 < 0 || functionData.value1 > Integer.MAX_VALUE)
+				return;
+
+			int startOffset = functionData.value1.intValue();
+
+			TransactionData transactionData = api.getTransactionFromA(state);
+
+			byte[] messageData = api.getMessageFromTransaction(transactionData);
+
+			if (messageData == null || startOffset > messageData.length)
+				return;
+
+			/*
+			 * Copy up to 32 bytes of message data into B,
+			 * retain order but pad with zeros in lower bytes.
+			 * 
+			 * So a 4-byte message "a b c d" would copy thusly:
+			 * a b c d 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+			 */
+			int byteCount = Math.min(32, messageData.length - startOffset);
+			byte[] bBytes = new byte[32];
+
+			System.arraycopy(messageData, startOffset, bBytes, 0, byteCount);
+
+			api.setB(state, bBytes);
+		}
+	},
+	/**
+	 * Convert address in B to 20-byte value in LSB of B1, and all of B2 & B3.<br>
+	 * <tt>0x0510</tt>
 	 */
 	CONVERT_B_TO_PKH(0x0510, 0, false) {
 		@Override
@@ -38,21 +101,21 @@ public enum QortalFunctionCode {
 		}
 	},
 	/**
-	 * <tt>0x0511</tt><br>
 	 * Convert 20-byte value in LSB of B1, and all of B2 & B3 to P2SH.<br>
+	 * <tt>0x0511</tt><br>
 	 * P2SH stored in lower 25 bytes of B.
 	 */
 	CONVERT_B_TO_P2SH(0x0511, 0, false) {
 		@Override
 		protected void postCheckExecute(FunctionData functionData, MachineState state, short rawFunctionCode) throws ExecutionException {
-			byte addressPrefix = Settings.getInstance().getBitcoinNet() == BTC.BitcoinNet.MAIN ? 0x05 : (byte) 0xc4;
+			byte addressPrefix = Settings.getInstance().getBitcoinNet() == Bitcoin.BitcoinNet.MAIN ? 0x05 : (byte) 0xc4;
 
 			convertAddressInB(addressPrefix, state);
 		}
 	},
 	/**
-	 * <tt>0x0512</tt><br>
 	 * Convert 20-byte value in LSB of B1, and all of B2 & B3 to Qortal address.<br>
+	 * <tt>0x0512</tt><br>
 	 * Qortal address stored in lower 25 bytes of B.
 	 */
 	CONVERT_B_TO_QORTAL(0x0512, 0, false) {

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

@@ -6,6 +6,8 @@ import static java.util.stream.Collectors.toMap;
 import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.math.RoundingMode;
+import java.text.DecimalFormat;
+import java.text.NumberFormat;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
@@ -15,6 +17,7 @@ import java.util.Map;
 import java.util.Set;
 import java.util.stream.Collectors;
 
+import org.apache.logging.log4j.Level;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.account.Account;
@@ -29,6 +32,7 @@ import org.qortal.controller.Controller;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.account.AccountBalanceData;
 import org.qortal.data.account.AccountData;
+import org.qortal.data.account.EligibleQoraHolderData;
 import org.qortal.data.account.QortFromQoraData;
 import org.qortal.data.account.RewardShareData;
 import org.qortal.data.at.ATData;
@@ -53,7 +57,6 @@ import org.qortal.transform.transaction.TransactionTransformer;
 import org.qortal.utils.Amounts;
 import org.qortal.utils.Base58;
 import org.qortal.utils.NTP;
-import org.roaringbitmap.IntIterator;
 
 import com.google.common.primitives.Bytes;
 import com.google.common.primitives.Longs;
@@ -128,7 +131,7 @@ public class Block {
 
 	@FunctionalInterface
 	private interface BlockRewardDistributor {
-		long distribute(long amount, Map<Account, Long> balanceChanges) throws DataException;
+		long distribute(long amount, Map<String, Long> balanceChanges) throws DataException;
 	}
 
 	/** Lazy-instantiated expanded info on block's online accounts. */
@@ -144,8 +147,8 @@ public class Block {
 		private final Account recipientAccount;
 		private final AccountData recipientAccountData;
 
-		ExpandedAccount(Repository repository, int accountIndex) throws DataException {
-			this.rewardShareData = repository.getAccountRepository().getRewardShareByIndex(accountIndex);
+		ExpandedAccount(Repository repository, RewardShareData rewardShareData) throws DataException {
+			this.rewardShareData = rewardShareData;
 			this.sharePercent = this.rewardShareData.getSharePercent();
 
 			this.mintingAccount = new Account(repository, this.rewardShareData.getMinter());
@@ -173,27 +176,34 @@ public class Block {
 		 * 
 		 *  @return account-level share "bin" from blockchain config, or null if founder / none found
 		 */
-		public AccountLevelShareBin getShareBin() {
+		public AccountLevelShareBin getShareBin(int blockHeight) {
 			if (this.isMinterFounder)
 				return null;
 
 			final int accountLevel = this.mintingAccountData.getLevel();
 			if (accountLevel <= 0)
-					return null;
+				return null; // level 0 isn't included in any share bins
 
-			final AccountLevelShareBin[] shareBinsByLevel = BlockChain.getInstance().getShareBinsByAccountLevel();
+			final BlockChain blockChain = BlockChain.getInstance();
+			final AccountLevelShareBin[] shareBinsByLevel = blockChain.getShareBinsByAccountLevel();
 			if (accountLevel > shareBinsByLevel.length)
 				return null;
 
-			return shareBinsByLevel[accountLevel];
+			if (blockHeight < blockChain.getShareBinFixHeight())
+				// Off-by-one bug still in effect
+				return shareBinsByLevel[accountLevel];
+
+			// level 1 stored at index 0, level 2 stored at index 1, etc.
+			return shareBinsByLevel[accountLevel-1];
+
 		}
 
-		public long distribute(long accountAmount, Map<Account, Long> balanceChanges) {
+		public long distribute(long accountAmount, Map<String, Long> balanceChanges) {
 			if (this.isRecipientAlsoMinter) {
 				// minter & recipient the same - simpler case
 				LOGGER.trace(() -> String.format("Minter/recipient account %s share: %s", this.mintingAccount.getAddress(), Amounts.prettyAmount(accountAmount)));
 				if (accountAmount != 0)
-					balanceChanges.merge(this.mintingAccount, accountAmount, Long::sum);
+					balanceChanges.merge(this.mintingAccount.getAddress(), accountAmount, Long::sum);
 			} else {
 				// minter & recipient different - extra work needed
 				long recipientAmount = (accountAmount * this.sharePercent) / 100L / 100L; // because scaled by 2dp and 'percent' means "per 100"
@@ -201,11 +211,11 @@ public class Block {
 
 				LOGGER.trace(() -> String.format("Minter account %s share: %s", this.mintingAccount.getAddress(), Amounts.prettyAmount(minterAmount)));
 				if (minterAmount != 0)
-					balanceChanges.merge(this.mintingAccount, minterAmount, Long::sum);
+					balanceChanges.merge(this.mintingAccount.getAddress(), minterAmount, Long::sum);
 
 				LOGGER.trace(() -> String.format("Recipient account %s share: %s", this.recipientAccount.getAddress(), Amounts.prettyAmount(recipientAmount)));
 				if (recipientAmount != 0)
-					balanceChanges.merge(this.recipientAccount, recipientAmount, Long::sum);
+					balanceChanges.merge(this.recipientAccount.getAddress(), recipientAmount, Long::sum);
 			}
 
 			// We always distribute all of the amount
@@ -215,6 +225,11 @@ public class Block {
 	/** Always use getExpandedAccounts() to access this, as it's lazy-instantiated. */
 	private List<ExpandedAccount> cachedExpandedAccounts = null;
 
+	/** Opportunistic cache of this block's valid online accounts. Only created by call to isValid(). */
+	private List<OnlineAccountData> cachedValidOnlineAccounts = null;
+	/** Opportunistic cache of this block's valid online reward-shares. Only created by call to isValid(). */
+	private List<RewardShareData> cachedOnlineRewardShares = null;
+
 	// Other useful constants
 
 	private static final BigInteger MAX_DISTANCE;
@@ -349,12 +364,8 @@ public class Block {
 			System.arraycopy(onlineAccountData.getSignature(), 0, onlineAccountsSignatures, i * Transformer.SIGNATURE_LENGTH, Transformer.SIGNATURE_LENGTH);
 		}
 
-		byte[] minterSignature;
-		try {
-			minterSignature = minter.sign(BlockTransformer.getBytesForMinterSignature(parentBlockData.getMinterSignature(), minter, encodedOnlineAccounts));
-		} catch (TransformationException e) {
-			throw new DataException("Unable to calculate next block minter signature", e);
-		}
+		byte[] minterSignature = minter.sign(BlockTransformer.getBytesForMinterSignature(parentBlockData,
+				minter.getPublicKey(), encodedOnlineAccounts));
 
 		// Qortal: minter is always a reward-share, so find actual minter and get their effective minting level
 		int minterLevel = Account.getRewardShareEffectiveMintingLevel(repository, minter.getPublicKey());
@@ -420,12 +431,8 @@ public class Block {
 		int version = this.blockData.getVersion();
 		byte[] reference = this.blockData.getReference();
 
-		byte[] minterSignature;
-		try {
-			minterSignature = minter.sign(BlockTransformer.getBytesForMinterSignature(parentBlockData.getMinterSignature(), minter, this.blockData.getEncodedOnlineAccounts()));
-		} catch (TransformationException e) {
-			throw new DataException("Unable to calculate next block's minter signature", e);
-		}
+		byte[] minterSignature = minter.sign(BlockTransformer.getBytesForMinterSignature(parentBlockData,
+				minter.getPublicKey(), this.blockData.getEncodedOnlineAccounts()));
 
 		// Qortal: minter is always a reward-share, so find actual minter and get their effective minting level
 		int minterLevel = Account.getRewardShareEffectiveMintingLevel(repository, minter.getPublicKey());
@@ -564,22 +571,28 @@ public class Block {
 	/**
 	 * Return expanded info on block's online accounts.
 	 * <p>
+	 * Typically called as part of Block.process() or Block.orphan()
+	 * so ideally after any calls to Block.isValid().
+	 * 
 	 * @throws DataException
 	 */
 	public List<ExpandedAccount> getExpandedAccounts() throws DataException {
 		if (this.cachedExpandedAccounts != null)
 			return this.cachedExpandedAccounts;
 
-		ConciseSet accountIndexes = BlockTransformer.decodeOnlineAccounts(this.blockData.getEncodedOnlineAccounts());
+		// We might already have a cache of online, reward-shares thanks to isValid()
+		if (this.cachedOnlineRewardShares == null) {
+			ConciseSet accountIndexes = BlockTransformer.decodeOnlineAccounts(this.blockData.getEncodedOnlineAccounts());
+			this.cachedOnlineRewardShares = repository.getAccountRepository().getRewardSharesByIndexes(accountIndexes.toArray());
+
+			if (this.cachedOnlineRewardShares == null)
+				throw new DataException("Online accounts invalid?");
+		}
+
 		List<ExpandedAccount> expandedAccounts = new ArrayList<>();
 
-		IntIterator iterator = accountIndexes.iterator();
-		while (iterator.hasNext()) {
-			int accountIndex = iterator.next();
-
-			ExpandedAccount accountInfo = new ExpandedAccount(repository, accountIndex);
-			expandedAccounts.add(accountInfo);
-		}
+		for (RewardShareData rewardShare : this.cachedOnlineRewardShares)
+			expandedAccounts.add(new ExpandedAccount(repository, rewardShare));
 
 		this.cachedExpandedAccounts = expandedAccounts;
 
@@ -732,11 +745,7 @@ public class Block {
 		if (!(this.minter instanceof PrivateKeyAccount))
 			throw new IllegalStateException("Block's minter is not a PrivateKeyAccount - can't sign!");
 
-		try {
-			this.blockData.setMinterSignature(((PrivateKeyAccount) this.minter).sign(BlockTransformer.getBytesForMinterSignature(this.blockData)));
-		} catch (TransformationException e) {
-			throw new RuntimeException("Unable to calculate block's minter signature", e);
-		}
+		this.blockData.setMinterSignature(((PrivateKeyAccount) this.minter).sign(BlockTransformer.getBytesForMinterSignature(this.blockData)));
 	}
 
 	/**
@@ -780,16 +789,49 @@ public class Block {
 		return BigInteger.valueOf(blockSummaryData.getOnlineAccountsCount()).shiftLeft(ACCOUNTS_COUNT_SHIFT).add(keyDistance);
 	}
 
-	public static BigInteger calcChainWeight(int commonBlockHeight, byte[] commonBlockSignature, List<BlockSummaryData> blockSummaries) {
+	public static BigInteger calcChainWeight(int commonBlockHeight, byte[] commonBlockSignature, List<BlockSummaryData> blockSummaries, int maxHeight) {
 		BigInteger cumulativeWeight = BigInteger.ZERO;
 		int parentHeight = commonBlockHeight;
 		byte[] parentBlockSignature = commonBlockSignature;
+		NumberFormat formatter = new DecimalFormat("0.###E0");
+		boolean isLogging = LOGGER.getLevel().isLessSpecificThan(Level.TRACE);
 
+		int blockCount = 0;
 		for (BlockSummaryData blockSummaryData : blockSummaries) {
-			cumulativeWeight = cumulativeWeight.shiftLeft(CHAIN_WEIGHT_SHIFT).add(calcBlockWeight(parentHeight, parentBlockSignature, blockSummaryData));
+			blockCount++;
+			StringBuilder stringBuilder = isLogging ? new StringBuilder(512) : null;
+
+			if (isLogging)
+				stringBuilder.append(formatter.format(cumulativeWeight)).append(" -> ");
+
+			cumulativeWeight = cumulativeWeight.shiftLeft(CHAIN_WEIGHT_SHIFT);
+			if (isLogging)
+				stringBuilder.append(formatter.format(cumulativeWeight)).append(" + ");
+
+			BigInteger blockWeight = calcBlockWeight(parentHeight, parentBlockSignature, blockSummaryData);
+			if (isLogging)
+				stringBuilder.append("(height: ")
+						.append(parentHeight + 1)
+						.append(", online: ")
+						.append(blockSummaryData.getOnlineAccountsCount())
+						.append(") ")
+						.append(formatter.format(blockWeight));
+
+			cumulativeWeight = cumulativeWeight.add(blockWeight);
+			if (isLogging)
+				stringBuilder.append(" -> ").append(formatter.format(cumulativeWeight));
+
+			if (isLogging && blockSummaries.size() > 1)
+				LOGGER.debug(() -> stringBuilder.toString()); //NOSONAR S1612 (false positive?)
+
 			parentHeight = blockSummaryData.getHeight();
 			parentBlockSignature = blockSummaryData.getSignature();
+
+			// After this timestamp, we only compare the same number of blocks
+			if (NTP.getTime() >= BlockChain.getInstance().getCalcChainWeightTimestamp() && parentHeight >= maxHeight)
+				break;
 		}
+		LOGGER.debug(String.format("Chain weight calculation was based on %d blocks", blockCount));
 
 		return cumulativeWeight;
 	}
@@ -914,19 +956,9 @@ public class Block {
 		if (accountIndexes.size() != this.blockData.getOnlineAccountsCount())
 			return ValidationResult.ONLINE_ACCOUNTS_INVALID;
 
-		List<RewardShareData> expandedAccounts = new ArrayList<>();
-
-		IntIterator iterator = accountIndexes.iterator();
-		while (iterator.hasNext()) {
-			int accountIndex = iterator.next();
-			RewardShareData rewardShareData = repository.getAccountRepository().getRewardShareByIndex(accountIndex);
-
-			// Check that claimed online account actually exists
-			if (rewardShareData == null)
-				return ValidationResult.ONLINE_ACCOUNT_UNKNOWN;
-
-			expandedAccounts.add(rewardShareData);
-		}
+		List<RewardShareData> onlineRewardShares = repository.getAccountRepository().getRewardSharesByIndexes(accountIndexes.toArray());
+		if (onlineRewardShares == null)
+			return ValidationResult.ONLINE_ACCOUNT_UNKNOWN;
 
 		// If block is past a certain age then we simply assume the signatures were correct
 		long signatureRequirementThreshold = NTP.getTime() - BlockChain.getInstance().getOnlineAccountSignaturesMinLifetime();
@@ -936,28 +968,51 @@ public class Block {
 		if (this.blockData.getOnlineAccountsSignatures() == null || this.blockData.getOnlineAccountsSignatures().length == 0)
 			return ValidationResult.ONLINE_ACCOUNT_SIGNATURES_MISSING;
 
-		if (this.blockData.getOnlineAccountsSignatures().length != expandedAccounts.size() * Transformer.SIGNATURE_LENGTH)
+		if (this.blockData.getOnlineAccountsSignatures().length != onlineRewardShares.size() * Transformer.SIGNATURE_LENGTH)
 			return ValidationResult.ONLINE_ACCOUNT_SIGNATURES_MALFORMED;
 
 		// Check signatures
-		List<byte[]> onlineAccountsSignatures = BlockTransformer.decodeTimestampSignatures(this.blockData.getOnlineAccountsSignatures());
 		long onlineTimestamp = this.blockData.getOnlineAccountsTimestamp();
 		byte[] onlineTimestampBytes = Longs.toByteArray(onlineTimestamp);
-		List<OnlineAccountData> onlineAccounts = Controller.getInstance().getOnlineAccounts();
+
+		// If this block is much older than current online timestamp, then there's no point checking current online accounts
+		List<OnlineAccountData> currentOnlineAccounts = onlineTimestamp < NTP.getTime() - Controller.ONLINE_TIMESTAMP_MODULUS
+				? null
+				: Controller.getInstance().getOnlineAccounts();
+		List<OnlineAccountData> latestBlocksOnlineAccounts = Controller.getInstance().getLatestBlocksOnlineAccounts();
+
+		// Extract online accounts' timestamp signatures from block data
+		List<byte[]> onlineAccountsSignatures = BlockTransformer.decodeTimestampSignatures(this.blockData.getOnlineAccountsSignatures());
+
+		// We'll build up a list of online accounts to hand over to Controller if block is added to chain
+		// and this will become latestBlocksOnlineAccounts (above) to reduce CPU load when we process next block...
+		List<OnlineAccountData> ourOnlineAccounts = new ArrayList<>();
 
 		for (int i = 0; i < onlineAccountsSignatures.size(); ++i) {
 			byte[] signature = onlineAccountsSignatures.get(i);
-			byte[] publicKey = expandedAccounts.get(i).getRewardSharePublicKey();
+			byte[] publicKey = onlineRewardShares.get(i).getRewardSharePublicKey();
+
+			OnlineAccountData onlineAccountData = new OnlineAccountData(onlineTimestamp, signature, publicKey);
+			ourOnlineAccounts.add(onlineAccountData);
 
 			// If signature is still current then no need to perform Ed25519 verify
-			OnlineAccountData onlineAccountData = new OnlineAccountData(onlineTimestamp, signature, publicKey);
-			if (onlineAccounts.remove(onlineAccountData)) // remove() is like contains() but also reduces the number to check next time
+			if (currentOnlineAccounts != null && currentOnlineAccounts.remove(onlineAccountData))
+				// remove() returned true, so online account still current
+				// and one less entry in currentOnlineAccounts to check next time
+				continue;
+
+			// If signature was okay in latest block then no need to perform Ed25519 verify
+			if (latestBlocksOnlineAccounts != null && latestBlocksOnlineAccounts.contains(onlineAccountData))
 				continue;
 
 			if (!Crypto.verify(publicKey, signature, onlineTimestampBytes))
 				return ValidationResult.ONLINE_ACCOUNT_SIGNATURE_INCORRECT;
 		}
 
+		// All online accounts valid, so save our list of online accounts for potential later use
+		this.cachedValidOnlineAccounts = ourOnlineAccounts;
+		this.cachedOnlineRewardShares = onlineRewardShares;
+
 		return ValidationResult.OK;
 	}
 
@@ -1037,6 +1092,10 @@ public class Block {
 			// Create repository savepoint here so we can rollback to it after testing transactions
 			repository.setSavepoint();
 
+			if (this.blockData.getHeight() == 212937)
+				// Apply fix for block 212937 but fix will be rolled back before we exit method
+				Block212937.processFix(this);
+
 			for (Transaction transaction : this.getTransactions()) {
 				TransactionData transactionData = transaction.getTransactionData();
 
@@ -1240,6 +1299,10 @@ public class Block {
 
 			// Distribute block rewards, including transaction fees, before transactions processed
 			processBlockRewards();
+
+			if (this.blockData.getHeight() == 212937)
+				// Apply fix for block 212937
+				Block212937.processFix(this);
 		}
 
 		// We're about to (test-)process a batch of transactions,
@@ -1271,6 +1334,12 @@ public class Block {
 		linkTransactionsToBlock();
 
 		postBlockTidy();
+
+		// Give Controller our cached, valid online accounts data (if any) to help reduce CPU load for next block
+		Controller.getInstance().pushLatestBlocksOnlineAccounts(this.cachedValidOnlineAccounts);
+
+		// Log some debugging info relating to the block weight calculation
+		this.logDebugInfo();
 	}
 
 	protected void increaseAccountLevels() throws DataException {
@@ -1288,13 +1357,16 @@ public class Block {
 				allUniqueExpandedAccounts.add(expandedAccount.recipientAccountData);
 		}
 
-		// Decrease blocks minted count for all accounts
+		// Increase blocks minted count for all accounts
+
+		// Batch update in repository
+		repository.getAccountRepository().modifyMintedBlockCounts(allUniqueExpandedAccounts.stream().map(AccountData::getAddress).collect(Collectors.toList()), +1);
+
+		// Local changes and also checks for level bump
 		for (AccountData accountData : allUniqueExpandedAccounts) {
 			// Adjust count locally (in Java)
 			accountData.setBlocksMinted(accountData.getBlocksMinted() + 1);
-
-			int rowCount = repository.getAccountRepository().modifyMintedBlockCount(accountData.getAddress(), +1);
-			LOGGER.trace(() -> String.format("Block minter %s up to %d minted block%s (rowCount: %d)", accountData.getAddress(), accountData.getBlocksMinted(), (accountData.getBlocksMinted() != 1 ? "s" : ""), rowCount));
+			LOGGER.trace(() -> String.format("Block minter %s up to %d minted block%s", accountData.getAddress(), accountData.getBlocksMinted(), (accountData.getBlocksMinted() != 1 ? "s" : "")));
 
 			final int effectiveBlocksMinted = accountData.getBlocksMinted() + accountData.getBlocksMintedAdjustment();
 
@@ -1449,6 +1521,9 @@ public class Block {
 	public void orphan() throws DataException {
 		LOGGER.trace(() -> String.format("Orphaning block %d", this.blockData.getHeight()));
 
+		// Log some debugging info relating to the block weight calculation
+		this.logDebugInfo();
+
 		// Return AT fees and delete AT states from repository
 		orphanAtFeesAndStates();
 
@@ -1462,6 +1537,10 @@ public class Block {
 			// Invalidate expandedAccounts as they may have changed due to orphaning TRANSFER_PRIVS transactions, etc.
 			this.cachedExpandedAccounts = null;
 
+			if (this.blockData.getHeight() == 212937)
+				// Revert fix for block 212937
+				Block212937.orphanFix(this);
+
 			// Block rewards, including transaction fees, removed after transactions undone
 			orphanBlockRewards();
 
@@ -1474,6 +1553,9 @@ public class Block {
 		this.blockData.setHeight(null);
 
 		postBlockTidy();
+
+		// Remove any cached, valid online accounts data from Controller
+		Controller.getInstance().popLatestBlocksOnlineAccounts();
 	}
 
 	protected void orphanTransactionsFromBlock() throws DataException {
@@ -1581,12 +1663,14 @@ public class Block {
 		}
 
 		// Decrease blocks minted count for all accounts
+
+		// Batch update in repository
+		repository.getAccountRepository().modifyMintedBlockCounts(allUniqueExpandedAccounts.stream().map(AccountData::getAddress).collect(Collectors.toList()), -1);
+
 		for (AccountData accountData : allUniqueExpandedAccounts) {
 			// Adjust count locally (in Java)
 			accountData.setBlocksMinted(accountData.getBlocksMinted() - 1);
-
-			int rowCount = repository.getAccountRepository().modifyMintedBlockCount(accountData.getAddress(), -1);
-			LOGGER.trace(() -> String.format("Block minter %s down to %d minted block%s (rowCount: %d)", accountData.getAddress(), accountData.getBlocksMinted(), (accountData.getBlocksMinted() != 1 ? "s" : ""), rowCount));
+			LOGGER.trace(() -> String.format("Block minter %s down to %d minted block%s", accountData.getAddress(), accountData.getBlocksMinted(), (accountData.getBlocksMinted() != 1 ? "s" : "")));
 
 			final int effectiveBlocksMinted = accountData.getBlocksMinted() + accountData.getBlocksMintedAdjustment();
 
@@ -1615,7 +1699,7 @@ public class Block {
 			this.distributionMethod = distributionMethod;
 		}
 
-		public long distribute(long distibutionAmount, Map<Account, Long> balanceChanges) throws DataException {
+		public long distribute(long distibutionAmount, Map<String, Long> balanceChanges) throws DataException {
 			return this.distributionMethod.distribute(distibutionAmount, balanceChanges);
 		}
 	}
@@ -1632,7 +1716,7 @@ public class Block {
 		// Now distribute to candidates
 
 		// Collate all balance changes and then apply in one final step
-		Map<Account, Long> balanceChanges = new HashMap<>();
+		Map<String, Long> balanceChanges = new HashMap<>();
 
 		long remainingAmount = totalAmount;
 		for (int r = 0; r < rewardCandidates.size(); ++r) {
@@ -1657,8 +1741,10 @@ public class Block {
 		}
 
 		// Apply balance changes
-		for (Map.Entry<Account, Long> balanceChange : balanceChanges.entrySet())
-			balanceChange.getKey().modifyAssetBalance(Asset.QORT, balanceChange.getValue());
+		List<AccountBalanceData> accountBalanceDeltas = balanceChanges.entrySet().stream()
+				.map(entry -> new AccountBalanceData(entry.getKey(), Asset.QORT, entry.getValue()))
+				.collect(Collectors.toList());
+		this.repository.getAccountRepository().modifyAssetBalances(accountBalanceDeltas);
 	}
 
 	protected List<BlockRewardCandidate> determineBlockRewardCandidates(boolean isProcessingNotOrphaning) throws DataException {
@@ -1712,7 +1798,7 @@ public class Block {
 			// Find all accounts in share bin. getShareBin() returns null for minter accounts that are also founders, so they are effectively filtered out.
 			AccountLevelShareBin accountLevelShareBin = accountLevelShareBins.get(binIndex);
 			// Object reference compare is OK as all references are read-only from blockchain config.
-			List<ExpandedAccount> binnedAccounts = expandedAccounts.stream().filter(accountInfo -> accountInfo.getShareBin() == accountLevelShareBin).collect(Collectors.toList());
+			List<ExpandedAccount> binnedAccounts = expandedAccounts.stream().filter(accountInfo -> accountInfo.getShareBin(this.blockData.getHeight()) == accountLevelShareBin).collect(Collectors.toList());
 
 			// No online accounts in this bin? Skip to next one
 			if (binnedAccounts.isEmpty())
@@ -1728,7 +1814,7 @@ public class Block {
 		}
 
 		// Fetch list of legacy QORA holders who haven't reached their cap of QORT reward.
-		List<AccountBalanceData> qoraHolders = this.repository.getAccountRepository().getEligibleLegacyQoraHolders(isProcessingNotOrphaning ? null : this.blockData.getHeight());
+		List<EligibleQoraHolderData> qoraHolders = this.repository.getAccountRepository().getEligibleLegacyQoraHolders(isProcessingNotOrphaning ? null : this.blockData.getHeight());
 		final boolean haveQoraHolders = !qoraHolders.isEmpty();
 		final long qoraHoldersShare = BlockChain.getInstance().getQoraHoldersShare();
 
@@ -1781,7 +1867,7 @@ public class Block {
 		return rewardCandidates;
 	}
 
-	private static long distributeBlockRewardShare(long distributionAmount, List<ExpandedAccount> accounts, Map<Account, Long> balanceChanges) {
+	private static long distributeBlockRewardShare(long distributionAmount, List<ExpandedAccount> accounts, Map<String, Long> balanceChanges) {
 		// Collate all expanded accounts by minting account
 		Map<String, List<ExpandedAccount>> accountsByMinter = new HashMap<>();
 
@@ -1810,7 +1896,7 @@ public class Block {
 		return sharedAmount;
 	}
 
-	private static long distributeBlockRewardToQoraHolders(long qoraHoldersAmount, List<AccountBalanceData> qoraHolders, Map<Account, Long> balanceChanges, Block block) throws DataException {
+	private static long distributeBlockRewardToQoraHolders(long qoraHoldersAmount, List<EligibleQoraHolderData> qoraHolders, Map<String, Long> balanceChanges, Block block) throws DataException {
 		final boolean isProcessingNotOrphaning = qoraHoldersAmount >= 0;
 
 		long qoraPerQortReward = BlockChain.getInstance().getQoraPerQortReward();
@@ -1818,7 +1904,7 @@ public class Block {
 
 		long totalQoraHeld = 0;
 		for (int i = 0; i < qoraHolders.size(); ++i)
-			totalQoraHeld += qoraHolders.get(i).getBalance();
+			totalQoraHeld += qoraHolders.get(i).getQoraBalance();
 
 		long finalTotalQoraHeld = totalQoraHeld;
 		LOGGER.trace(() -> String.format("Total legacy QORA held: %s", Amounts.prettyAmount(finalTotalQoraHeld)));
@@ -1831,9 +1917,13 @@ public class Block {
 		BigInteger totalQoraHeldBI = BigInteger.valueOf(totalQoraHeld);
 
 		long sharedAmount = 0;
+		// For batched update of QORT_FROM_QORA balances
+		List<AccountBalanceData> newQortFromQoraBalances = new ArrayList<>();
+
 		for (int h = 0; h < qoraHolders.size(); ++h) {
-			AccountBalanceData qoraHolder = qoraHolders.get(h);
-			BigInteger qoraHolderBalanceBI = BigInteger.valueOf(qoraHolder.getBalance());
+			EligibleQoraHolderData qoraHolder = qoraHolders.get(h);
+			BigInteger qoraHolderBalanceBI = BigInteger.valueOf(qoraHolder.getQoraBalance());
+			String qoraHolderAddress = qoraHolder.getAddress();
 
 			// This is where a 128bit integer library could help:
 			// long holderReward = (qoraHoldersAmount * qoraHolder.getBalance()) / totalQoraHeld;
@@ -1841,15 +1931,13 @@ public class Block {
 
 			final long holderRewardForLogging = holderReward;
 			LOGGER.trace(() -> String.format("QORA holder %s has %s / %s QORA so share: %s",
-					qoraHolder.getAddress(), Amounts.prettyAmount(qoraHolder.getBalance()), finalTotalQoraHeld, Amounts.prettyAmount(holderRewardForLogging)));
+					qoraHolderAddress, Amounts.prettyAmount(qoraHolder.getQoraBalance()), finalTotalQoraHeld, Amounts.prettyAmount(holderRewardForLogging)));
 
 			// Too small to register this time?
 			if (holderReward == 0)
 				continue;
 
-			Account qoraHolderAccount = new Account(block.repository, qoraHolder.getAddress());
-
-			long newQortFromQoraBalance = qoraHolderAccount.getConfirmedBalance(Asset.QORT_FROM_QORA) + holderReward;
+			long newQortFromQoraBalance = qoraHolder.getQortFromQoraBalance() + holderReward;
 
 			// If processing, make sure we don't overpay
 			if (isProcessingNotOrphaning) {
@@ -1863,44 +1951,43 @@ public class Block {
 					newQortFromQoraBalance -= adjustment;
 
 					// This is also the QORA holder's final QORT-from-QORA block
-					QortFromQoraData qortFromQoraData = new QortFromQoraData(qoraHolder.getAddress(), holderReward, block.blockData.getHeight());
+					QortFromQoraData qortFromQoraData = new QortFromQoraData(qoraHolderAddress, holderReward, block.blockData.getHeight());
 					block.repository.getAccountRepository().save(qortFromQoraData);
 
 					long finalAdjustedHolderReward = holderReward;
 					LOGGER.trace(() -> String.format("QORA holder %s final share %s at height %d",
-							qoraHolder.getAddress(), Amounts.prettyAmount(finalAdjustedHolderReward), block.blockData.getHeight()));
+							qoraHolderAddress, Amounts.prettyAmount(finalAdjustedHolderReward), block.blockData.getHeight()));
 				}
 			} else {
 				// Orphaning
-				QortFromQoraData qortFromQoraData = block.repository.getAccountRepository().getQortFromQoraInfo(qoraHolder.getAddress());
-				if (qortFromQoraData != null) {
+				if (qoraHolder.getFinalBlockHeight() != null) {
 					// Final QORT-from-QORA amount from repository was stored during processing, and hence positive.
 					// So we use + here as qortFromQora is negative during orphaning.
 					// More efficient than "holderReward - (0 - final-qort-from-qora)"
-					long adjustment = holderReward + qortFromQoraData.getFinalQortFromQora();
+					long adjustment = holderReward + qoraHolder.getFinalQortFromQora();
 
 					holderReward -= adjustment;
 					newQortFromQoraBalance -= adjustment;
 
-					block.repository.getAccountRepository().deleteQortFromQoraInfo(qoraHolder.getAddress());
+					block.repository.getAccountRepository().deleteQortFromQoraInfo(qoraHolderAddress);
 
 					long finalAdjustedHolderReward = holderReward;
 					LOGGER.trace(() -> String.format("QORA holder %s final share %s was at height %d",
-							qoraHolder.getAddress(), Amounts.prettyAmount(finalAdjustedHolderReward), block.blockData.getHeight()));
+							qoraHolderAddress, Amounts.prettyAmount(finalAdjustedHolderReward), block.blockData.getHeight()));
 				}
 			}
 
-			balanceChanges.merge(qoraHolderAccount, holderReward, Long::sum);
+			balanceChanges.merge(qoraHolderAddress, holderReward, Long::sum);
 
-			if (newQortFromQoraBalance > 0)
-				qoraHolderAccount.setConfirmedBalance(Asset.QORT_FROM_QORA, newQortFromQoraBalance);
-			else
-				// Remove QORT_FROM_QORA balance as it's zero
-				qoraHolderAccount.deleteBalance(Asset.QORT_FROM_QORA);
+			// Add to batched QORT_FROM_QORA balance update list
+			newQortFromQoraBalances.add(new AccountBalanceData(qoraHolderAddress, Asset.QORT_FROM_QORA, newQortFromQoraBalance));
 
 			sharedAmount += holderReward;
 		}
 
+		// Perform batched update of QORT_FROM_QORA balances
+		block.repository.getAccountRepository().setAssetBalances(newQortFromQoraBalances);
+
 		return sharedAmount;
 	}
 
@@ -1909,4 +1996,37 @@ public class Block {
 		this.repository.getAccountRepository().tidy();
 	}
 
+	private void logDebugInfo() {
+		try {
+			// Avoid calculations if possible. We have to check against INFO here, since Level.isMoreSpecificThan() confusingly uses <= rather than just <
+			if (LOGGER.getLevel().isMoreSpecificThan(Level.INFO))
+				return;
+
+			if (this.repository == null || this.getMinter() == null || this.getBlockData() == null)
+				return;
+
+			int minterLevel = Account.getRewardShareEffectiveMintingLevel(this.repository, this.getMinter().getPublicKey());
+
+			LOGGER.debug(String.format("======= BLOCK %d (%.8s) =======", this.getBlockData().getHeight(), Base58.encode(this.getSignature())));
+			LOGGER.debug(String.format("Timestamp: %d", this.getBlockData().getTimestamp()));
+			LOGGER.debug(String.format("Minter level: %d", minterLevel));
+			LOGGER.debug(String.format("Online accounts: %d", this.getBlockData().getOnlineAccountsCount()));
+
+			BlockSummaryData blockSummaryData = new BlockSummaryData(this.getBlockData());
+			if (this.getParent() == null || this.getParent().getSignature() == null || blockSummaryData == null || minterLevel == 0)
+				return;
+
+			blockSummaryData.setMinterLevel(minterLevel);
+			BigInteger blockWeight = calcBlockWeight(this.getParent().getHeight(), this.getParent().getSignature(), blockSummaryData);
+			BigInteger keyDistance = calcKeyDistance(this.getParent().getHeight(), this.getParent().getSignature(), blockSummaryData.getMinterPublicKey(), blockSummaryData.getMinterLevel());
+			NumberFormat formatter = new DecimalFormat("0.###E0");
+
+			LOGGER.debug(String.format("Key distance: %s", formatter.format(keyDistance)));
+			LOGGER.debug(String.format("Weight: %s", formatter.format(blockWeight)));
+
+		} catch (DataException e) {
+			LOGGER.info(() -> String.format("Unable to log block debugging info: %s", e.getMessage()));
+		}
+	}
+
 }

src/main/java/org/qortal/block/Block212937.java

@@ -0,0 +1,153 @@
+package org.qortal.block;
+
+import java.io.InputStream;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import javax.xml.bind.JAXBContext;
+import javax.xml.bind.JAXBException;
+import javax.xml.bind.UnmarshalException;
+import javax.xml.bind.Unmarshaller;
+import javax.xml.transform.stream.StreamSource;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.eclipse.persistence.jaxb.JAXBContextFactory;
+import org.eclipse.persistence.jaxb.UnmarshallerProperties;
+import org.qortal.data.account.AccountBalanceData;
+import org.qortal.repository.DataException;
+
+/**
+ * Block 212937
+ * <p>
+ * Somehow a node minted a version of block 212937 that contained one transaction:
+ * a PAYMENT transaction that attempted to spend more QORT than that account had as QORT balance.
+ * <p>
+ * This invalid transaction made block 212937 (rightly) invalid to several nodes,
+ * which refused to use that block.
+ * However, it seems there were no other nodes minting an alternative, valid block at that time
+ * and so the chain stalled for several nodes in the network.
+ * <p>
+ * Additionally, the invalid block 212937 affected all new installations, regardless of whether
+ * they synchronized from scratch (block 1) or used an 'official release' bootstrap.
+ * <p>
+ * After lengthy diagnosis, it was discovered that
+ * the invalid transaction seemed to rely on incorrect balances in a corrupted database.
+ * Copies of DB files containing the broken chain were also shared around, exacerbating the problem.
+ * <p>
+ * There were three options:
+ * <ol>
+ * <li>roll back the chain to last known valid block 212936 and re-mint empty blocks to current height</li>
+ * <li>keep existing chain, but apply database edits at block 212937 to allow current chain to be valid</li>
+ * <li>attempt to mint an alternative chain, retaining as many valid transactions as possible</li>
+ * </ol>
+ * <p>
+ * Option 1 was highly undesirable due to knock-on effects from wiping 700+ transactions, some of which
+ * might have affect cross-chain trades, although there were no cross-chain trade completed during
+ * the decision period.
+ * <p>
+ * Option 3 was essentially a slightly better version of option 1 and rejected for similar reasons.
+ * Attempts at option 3 also rapidly hit cumulative problems with every replacement block due to
+ * differing block timestamps making some transactions, and then even some blocks themselves, invalid.
+ * <p>
+ * This class is the implementation of option 2.
+ * <p>
+ * The change in account balances are relatively small, see <tt>block-212937-deltas.json</tt> resource
+ * for actual values. These values were obtained by exporting the <tt>AccountBalances</tt> table from
+ * both versions of the database with chain at block 212936, and then comparing. The values were also
+ * tested by syncing both databases up to block 225500, re-exporting and re-comparing.
+ * <p>
+ * The invalid block 212937 signature is: <tt>2J3GVJjv...qavh6KkQ</tt>.
+ * <p>
+ * The invalid transaction in block 212937 is:
+ * <p>
+ * <code><pre>
+   {
+      "amount" : "0.10788294",
+      "approvalStatus" : "NOT_REQUIRED",
+      "blockHeight" : 212937,
+      "creatorAddress" : "QLdw5uabviLJgRGkRiydAFmAtZzxHfNXSs",
+      "fee" : "0.00100000",
+      "recipient" : "QZi1mNHDbiLvsytxTgxDr9nhJe4pNZaWpw",
+      "reference" : "J6JukdTVuXZ3JYbHatfZzwxG2vSiZwVCPDzW5K7PsVQKRj8XZeDtqnkGCGGjaSQZ9bQMtV44ky88NnGM4YBQKU6",
+      "senderPublicKey" : "DBFfbD2M3uh4jPE5PaUcZVvNPfrrJzVB7seeEtBn5SPs",
+      "signature" : "qkitxdCEEnKt8w6wRfFixtErbXsxWE6zG2ESNhpqBdScikV1WxeA6WZTTMJVV4tCeZdBFXw3V1X5NVztv6LirWK",
+      "timestamp" : 1607863074904,
+      "txGroupId" : 0,
+      "type" : "PAYMENT"
+   }
+   </pre></code>
+ * <p>
+ * Account <tt>QLdw5uabviLJgRGkRiydAFmAtZzxHfNXSs</tt> attempted to spend <tt>0.10888294</tt> (including fees)
+ * when their QORT balance was really only <tt>0.10886665</tt>.
+ * <p>
+ * However, on the broken DB nodes, their balance
+ * seemed to be <tt>0.10890293</tt> which was sufficient to make the transaction valid.
+ */
+public final class Block212937 {
+
+	private static final Logger LOGGER = LogManager.getLogger(Block212937.class);
+	private static final String ACCOUNT_DELTAS_SOURCE = "block-212937-deltas.json";
+
+	private static final List<AccountBalanceData> accountDeltas = readAccountDeltas();
+
+	private Block212937() {
+		/* Do not instantiate */
+	}
+
+	@SuppressWarnings("unchecked")
+	private static List<AccountBalanceData> readAccountDeltas() {
+		Unmarshaller unmarshaller;
+
+		try {
+			// Create JAXB context aware of classes we need to unmarshal
+			JAXBContext jc = JAXBContextFactory.createContext(new Class[] {
+				AccountBalanceData.class
+			}, null);
+
+			// Create unmarshaller
+			unmarshaller = jc.createUnmarshaller();
+
+			// Set the unmarshaller media type to JSON
+			unmarshaller.setProperty(UnmarshallerProperties.MEDIA_TYPE, "application/json");
+
+			// Tell unmarshaller that there's no JSON root element in the JSON input
+			unmarshaller.setProperty(UnmarshallerProperties.JSON_INCLUDE_ROOT, false);
+		} catch (JAXBException e) {
+			String message = "Failed to setup unmarshaller to read block 212937 deltas";
+			LOGGER.error(message, e);
+			throw new RuntimeException(message, e);
+		}
+
+		ClassLoader classLoader = BlockChain.class.getClassLoader();
+		InputStream in = classLoader.getResourceAsStream(ACCOUNT_DELTAS_SOURCE);
+		StreamSource jsonSource = new StreamSource(in);
+
+		try  {
+			// Attempt to unmarshal JSON stream to BlockChain config
+			return (List<AccountBalanceData>) unmarshaller.unmarshal(jsonSource, AccountBalanceData.class).getValue();
+		} catch (UnmarshalException e) {
+			String message = "Failed to parse block 212937 deltas";
+			LOGGER.error(message, e);
+			throw new RuntimeException(message, e);
+		} catch (JAXBException e) {
+			String message = "Unexpected JAXB issue while processing block 212937 deltas";
+			LOGGER.error(message, e);
+			throw new RuntimeException(message, e);
+		}
+	}
+
+	public static void processFix(Block block) throws DataException {
+		block.repository.getAccountRepository().modifyAssetBalances(accountDeltas);
+	}
+
+	public static void orphanFix(Block block) throws DataException {
+		// Create inverse deltas
+		List<AccountBalanceData> inverseDeltas = accountDeltas.stream()
+				.map(delta -> new AccountBalanceData(delta.getAddress(), delta.getAssetId(), 0 - delta.getBalance()))
+				.collect(Collectors.toList());
+
+		block.repository.getAccountRepository().modifyAssetBalances(inverseDeltas);
+	}
+
+}

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

@@ -32,7 +32,6 @@ 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;
 import org.qortal.utils.StringLongMapXmlAdapter;
 
 /**
@@ -71,6 +70,10 @@ public class BlockChain {
 	private GenesisBlock.GenesisInfo genesisInfo;
 
 	public enum FeatureTrigger {
+		atFindNextTransactionFix,
+		newBlockSigHeight,
+		shareBinFix,
+		calcChainWeightTimestamp;
 	}
 
 	/** Map of which blockchain features are enabled when (height/timestamp) */
@@ -372,6 +375,22 @@ public class BlockChain {
 
 	// Convenience methods for specific blockchain feature triggers
 
+	public int getAtFindNextTransactionFixHeight() {
+		return this.featureTriggers.get(FeatureTrigger.atFindNextTransactionFix.name()).intValue();
+	}
+
+	public int getNewBlockSigHeight() {
+		return this.featureTriggers.get(FeatureTrigger.newBlockSigHeight.name()).intValue();
+	}
+
+	public int getShareBinFixHeight() {
+		return this.featureTriggers.get(FeatureTrigger.shareBinFix.name()).intValue();
+	}
+
+	public long getCalcChainWeightTimestamp() {
+		return this.featureTriggers.get(FeatureTrigger.calcChainWeightTimestamp.name()).longValue();
+	}
+
 	// More complex getters for aspects that change by height or timestamp
 
 	public long getRewardAtHeight(int ourHeight) {
@@ -482,7 +501,7 @@ public class BlockChain {
 	}
 
 	/**
-	 * Some sort start-up/initialization/checking method.
+	 * Some sort of start-up/initialization/checking method.
 	 * 
 	 * @throws SQLException
 	 */
@@ -492,7 +511,11 @@ public class BlockChain {
 			rebuildBlockchain();
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			BlockData detachedBlockData = repository.getBlockRepository().getDetachedBlockSignature();
+			repository.checkConsistency();
+
+			int startHeight = Math.max(repository.getBlockRepository().getBlockchainHeight() - 1440, 1);
+
+			BlockData detachedBlockData = repository.getBlockRepository().getDetachedBlockSignature(startHeight);
 
 			if (detachedBlockData != null) {
 				LOGGER.error(String.format("Block %d's reference does not match any block's signature", detachedBlockData.getHeight()));
@@ -530,7 +553,8 @@ public class BlockChain {
 
 	private static void rebuildBlockchain() throws DataException {
 		// (Re)build repository
-		RepositoryManager.rebuild();
+		if (!RepositoryManager.wasPristineAtOpen())
+			RepositoryManager.rebuild();
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			GenesisBlock genesisBlock = GenesisBlock.getInstance(repository);
@@ -552,17 +576,23 @@ public class BlockChain {
 
 		try {
 			try (final Repository repository = RepositoryManager.getRepository()) {
-				for (int height = repository.getBlockRepository().getBlockchainHeight(); height > targetHeight; --height) {
+				int height = repository.getBlockRepository().getBlockchainHeight();
+				BlockData orphanBlockData = repository.getBlockRepository().fromHeight(height);
+
+				while (height > targetHeight) {
 					LOGGER.info(String.format("Forcably orphaning block %d", height));
 
-					BlockData blockData = repository.getBlockRepository().fromHeight(height);
-					Block block = new Block(repository, blockData);
+					Block block = new Block(repository, orphanBlockData);
 					block.orphan();
-					repository.saveChanges();
-				}
 
-				BlockData lastBlockData = repository.getBlockRepository().getLastBlock();
-				Controller.getInstance().setChainTip(lastBlockData);
+					repository.saveChanges();
+
+					--height;
+					orphanBlockData = repository.getBlockRepository().fromHeight(height);
+
+					repository.discardChanges(); // clear transaction status to prevent deadlocks
+					Controller.getInstance().onOrphanedBlock(orphanBlockData);
+				}
 
 				return true;
 			}
@@ -571,33 +601,4 @@ public class BlockChain {
 		}
 	}
 
-	public static void trimOldOnlineAccountsSignatures() {
-		final Long now = NTP.getTime();
-		if (now == null)
-			return;
-
-		ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
-		if (!blockchainLock.tryLock())
-			// Too busy to trim right now, try again later
-			return;
-
-		try {
-			try (final Repository repository = RepositoryManager.tryRepository()) {
-				if (repository == null)
-					return;
-
-				int numBlocksTrimmed = repository.getBlockRepository().trimOldOnlineAccountsSignatures(now - BlockChain.getInstance().getOnlineAccountSignaturesMaxLifetime());
-
-				if (numBlocksTrimmed > 0)
-					LOGGER.debug(String.format("Trimmed old online accounts signatures from %d block%s", numBlocksTrimmed, (numBlocksTrimmed != 1 ? "s" : "")));
-
-				repository.saveChanges();
-			} catch (DataException e) {
-				LOGGER.warn(String.format("Repository issue trying to trim old online accounts signatures: %s", e.getMessage()));
-			}
-		} finally {
-			blockchainLock.unlock();
-		}
-	}
-
 }

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

@@ -0,0 +1,80 @@
+package org.qortal.controller;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.data.block.BlockData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.settings.Settings;
+import org.qortal.utils.NTP;
+
+public class AtStatesTrimmer implements Runnable {
+
+	private static final Logger LOGGER = LogManager.getLogger(AtStatesTrimmer.class);
+
+	@Override
+	public void run() {
+		Thread.currentThread().setName("AT States trimmer");
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			int trimStartHeight = repository.getATRepository().getAtTrimHeight();
+
+			repository.getATRepository().prepareForAtStateTrimming();
+			repository.saveChanges();
+
+			while (!Controller.isStopping()) {
+				repository.discardChanges();
+
+				Thread.sleep(Settings.getInstance().getAtStatesTrimInterval());
+
+				BlockData chainTip = Controller.getInstance().getChainTip();
+				if (chainTip == null || NTP.getTime() == null)
+					continue;
+
+				// Don't even attempt if we're mid-sync as our repository requests will be delayed for ages
+				if (Controller.getInstance().isSynchronizing())
+					continue;
+
+				long currentTrimmableTimestamp = NTP.getTime() - Settings.getInstance().getAtStatesMaxLifetime();
+				// We want to keep AT states near the tip of our copy of blockchain so we can process/orphan nearby blocks
+				long chainTrimmableTimestamp = chainTip.getTimestamp() - Settings.getInstance().getAtStatesMaxLifetime();
+
+				long upperTrimmableTimestamp = Math.min(currentTrimmableTimestamp, chainTrimmableTimestamp);
+				int upperTrimmableHeight = repository.getBlockRepository().getHeightFromTimestamp(upperTrimmableTimestamp);
+
+				int upperBatchHeight = trimStartHeight + Settings.getInstance().getAtStatesTrimBatchSize();
+				int upperTrimHeight = Math.min(upperBatchHeight, upperTrimmableHeight);
+
+				if (trimStartHeight >= upperTrimHeight)
+					continue;
+
+				int numAtStatesTrimmed = repository.getATRepository().trimAtStates(trimStartHeight, upperTrimHeight, Settings.getInstance().getAtStatesTrimLimit());
+				repository.saveChanges();
+
+				if (numAtStatesTrimmed > 0) {
+					final int finalTrimStartHeight = trimStartHeight;
+					LOGGER.debug(() -> String.format("Trimmed %d AT state%s between blocks %d and %d",
+							numAtStatesTrimmed, (numAtStatesTrimmed != 1 ? "s" : ""),
+							finalTrimStartHeight, upperTrimHeight));
+				} else {
+					// Can we move onto next batch?
+					if (upperTrimmableHeight > upperBatchHeight) {
+						trimStartHeight = upperBatchHeight;
+						repository.getATRepository().setAtTrimHeight(trimStartHeight);
+						repository.getATRepository().prepareForAtStateTrimming();
+						repository.saveChanges();
+
+						final int finalTrimStartHeight = trimStartHeight;
+						LOGGER.debug(() -> String.format("Bumping AT state base trim height to %d", finalTrimStartHeight));
+					}
+				}
+			}
+		} catch (DataException e) {
+			LOGGER.warn(String.format("Repository issue trying to trim AT states: %s", e.getMessage()));
+		} catch (InterruptedException e) {
+			// Time to exit
+		}
+	}
+
+}

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

@@ -214,8 +214,9 @@ public class AutoUpdate extends Thread {
 			return false; // failed - try another repo
 		}
 
-		// Give repository a chance to backup in case things go badly wrong
-		RepositoryManager.backup(true);
+		// Give repository a chance to backup in case things go badly wrong (if enabled)
+		if (Settings.getInstance().getRepositoryBackupInterval() > 0)
+			RepositoryManager.backup(true);
 
 		// Call ApplyUpdate to end this process (unlocking current JAR so it can be replaced)
 		String javaHome = System.getProperty("java.home");

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

@@ -1,4 +1,4 @@
-package org.qortal.block;
+package org.qortal.controller;
 
 import java.math.BigInteger;
 import java.util.ArrayList;
@@ -13,8 +13,9 @@ import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.account.Account;
 import org.qortal.account.PrivateKeyAccount;
+import org.qortal.block.Block;
 import org.qortal.block.Block.ValidationResult;
-import org.qortal.controller.Controller;
+import org.qortal.block.BlockChain;
 import org.qortal.data.account.MintingAccountData;
 import org.qortal.data.account.RewardShareData;
 import org.qortal.data.block.BlockData;
@@ -60,7 +61,7 @@ public class BlockMinter extends Thread {
 				List<TransactionData> unconfirmedTransactions = repository.getTransactionRepository().getUnconfirmedTransactions();
 
 				for (TransactionData transactionData : unconfirmedTransactions) {
-					LOGGER.trace(String.format("Deleting unconfirmed transaction %s", Base58.encode(transactionData.getSignature())));
+					LOGGER.trace(() -> String.format("Deleting unconfirmed transaction %s", Base58.encode(transactionData.getSignature())));
 					repository.getTransactionRepository().delete(transactionData);
 				}
 
@@ -69,7 +70,7 @@ public class BlockMinter extends Thread {
 
 			// Going to need this a lot...
 			BlockRepository blockRepository = repository.getBlockRepository();
-			Block previousBlock = null;
+			BlockData previousBlockData = null;
 
 			List<Block> newBlocks = new ArrayList<>();
 
@@ -115,7 +116,7 @@ public class BlockMinter extends Thread {
 
 					RewardShareData rewardShareData = repository.getAccountRepository().getRewardShare(mintingAccountData.getPublicKey());
 					if (rewardShareData == null) {
-						// Reward-share doesn't even exist - probably not a good sign
+						// Reward-share doesn't exist - probably cancelled but not yet removed from node's list of minting accounts
 						madi.remove();
 						continue;
 					}
@@ -134,24 +135,27 @@ public class BlockMinter extends Thread {
 				// Disregard peers that have "misbehaved" recently
 				peers.removeIf(Controller.hasMisbehaved);
 
-				// Disregard peers that don't have a recent block
-				peers.removeIf(Controller.hasNoRecentBlock);
+				// Disregard peers that don't have a recent block, but only if we're not in recovery mode.
+				// In that mode, we want to allow minting on top of older blocks, to recover stalled networks.
+				if (Controller.getInstance().getRecoveryMode() == false)
+					peers.removeIf(Controller.hasNoRecentBlock);
 
 				// Don't mint if we don't have enough up-to-date peers as where would the transactions/consensus come from?
 				if (peers.size() < Settings.getInstance().getMinBlockchainPeers())
 					continue;
 
-				// If our latest block isn't recent then we need to synchronize instead of minting.
+				// If our latest block isn't recent then we need to synchronize instead of minting, unless we're in recovery mode.
 				if (!peers.isEmpty() && lastBlockData.getTimestamp() < minLatestBlockTimestamp)
-					continue;
+					if (Controller.getInstance().getRecoveryMode() == false)
+						continue;
 
 				// There are enough peers with a recent block and our latest block is recent
 				// so go ahead and mint a block if possible.
 				isMintingPossible = true;
 
 				// Check blockchain hasn't changed
-				if (previousBlock == null || !Arrays.equals(previousBlock.getSignature(), lastBlockData.getSignature())) {
-					previousBlock = new Block(repository, lastBlockData);
+				if (previousBlockData == null || !Arrays.equals(previousBlockData.getSignature(), lastBlockData.getSignature())) {
+					previousBlockData = lastBlockData;
 					newBlocks.clear();
 
 					// Reduce log timeout
@@ -162,12 +166,20 @@ public class BlockMinter extends Thread {
 				mintingAccountsData.removeIf(mintingAccountData -> newBlocks.stream().anyMatch(newBlock -> Arrays.equals(newBlock.getBlockData().getMinterPublicKey(), mintingAccountData.getPublicKey())));
 
 				// Do we need to build any potential new blocks?
-				List<PrivateKeyAccount> mintingAccounts = mintingAccountsData.stream().map(accountData -> new PrivateKeyAccount(repository, accountData.getPrivateKey())).collect(Collectors.toList());
+				List<PrivateKeyAccount> newBlocksMintingAccounts = mintingAccountsData.stream().map(accountData -> new PrivateKeyAccount(repository, accountData.getPrivateKey())).collect(Collectors.toList());
 
-				for (PrivateKeyAccount mintingAccount : mintingAccounts) {
+				// We might need to sit the next block out, if one of our minting accounts signed the previous one
+				final byte[] previousBlockMinter = previousBlockData.getMinterPublicKey();
+				final boolean mintedLastBlock = mintingAccountsData.stream().anyMatch(mintingAccount -> Arrays.equals(mintingAccount.getPublicKey(), previousBlockMinter));
+				if (mintedLastBlock) {
+					LOGGER.trace(String.format("One of our keys signed the last block, so we won't sign the next one"));
+					continue;
+				}
+
+				for (PrivateKeyAccount mintingAccount : newBlocksMintingAccounts) {
 					// First block does the AT heavy-lifting
 					if (newBlocks.isEmpty()) {
-						Block newBlock = Block.mint(repository, previousBlock.getBlockData(), mintingAccount);
+						Block newBlock = Block.mint(repository, previousBlockData, mintingAccount);
 						if (newBlock == null) {
 							// For some reason we can't mint right now
 							moderatedLog(() -> LOGGER.error("Couldn't build a to-be-minted block"));
@@ -195,7 +207,7 @@ public class BlockMinter extends Thread {
 				// Make sure we're the only thread modifying the blockchain
 				ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
 				if (!blockchainLock.tryLock(30, TimeUnit.SECONDS)) {
-					LOGGER.warn("Couldn't acquire blockchain lock even after waiting 30 seconds");
+					LOGGER.debug("Couldn't acquire blockchain lock even after waiting 30 seconds");
 					continue;
 				}
 
@@ -233,8 +245,8 @@ public class BlockMinter extends Thread {
 						continue;
 
 					// Pick best block
-					final int parentHeight = previousBlock.getBlockData().getHeight();
-					final byte[] parentBlockSignature = previousBlock.getSignature();
+					final int parentHeight = previousBlockData.getHeight();
+					final byte[] parentBlockSignature = previousBlockData.getSignature();
 
 					BigInteger bestWeight = null;
 
@@ -274,28 +286,33 @@ public class BlockMinter extends Thread {
 					try {
 						newBlock.process();
 
-						LOGGER.info(String.format("Minted new block: %d", newBlock.getBlockData().getHeight()));
 						repository.saveChanges();
 
+						LOGGER.info(String.format("Minted new block: %d", newBlock.getBlockData().getHeight()));
+
 						RewardShareData rewardShareData = repository.getAccountRepository().getRewardShare(newBlock.getBlockData().getMinterPublicKey());
 
 						if (rewardShareData != null) {
-							LOGGER.info(String.format("Minted block %d, sig %.8s by %s on behalf of %s",
+							LOGGER.info(String.format("Minted block %d, sig %.8s, parent sig: %.8s by %s on behalf of %s",
 									newBlock.getBlockData().getHeight(),
 									Base58.encode(newBlock.getBlockData().getSignature()),
+									Base58.encode(newBlock.getParent().getSignature()),
 									rewardShareData.getMinter(),
 									rewardShareData.getRecipient()));
 						} else {
-							LOGGER.info(String.format("Minted block %d, sig %.8s by %s",
+							LOGGER.info(String.format("Minted block %d, sig %.8s, parent sig: %.8s by %s",
 									newBlock.getBlockData().getHeight(),
 									Base58.encode(newBlock.getBlockData().getSignature()),
+									Base58.encode(newBlock.getParent().getSignature()),
 									newBlock.getMinter().getAddress()));
 						}
 
-						repository.saveChanges();
-
-						// Notify controller
+						// Notify network after we're released blockchain lock
 						newBlockMinted = true;
+
+						// Notify Controller
+						repository.discardChanges(); // clear transaction status to prevent deadlocks
+						Controller.getInstance().onNewBlock(newBlock.getBlockData());
 					} catch (DataException e) {
 						// Unable to process block - report and discard
 						LOGGER.error("Unable to process newly minted block?", e);
@@ -305,8 +322,13 @@ public class BlockMinter extends Thread {
 					blockchainLock.unlock();
 				}
 
-				if (newBlockMinted)
-					Controller.getInstance().onNewBlock(newBlock.getBlockData());
+				if (newBlockMinted) {
+					// Broadcast our new chain to network
+					BlockData newBlockData = newBlock.getBlockData();
+
+					Network network = Network.getInstance();
+					network.broadcast(broadcastPeer -> network.buildHeightMessage(broadcastPeer, newBlockData));
+				}
 			}
 		} catch (DataException e) {
 			LOGGER.warn("Repository issue while running block minter", e);

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

@@ -1,43 +0,0 @@
-package org.qortal.controller;
-
-import java.util.HashMap;
-import java.util.Map;
-
-import org.eclipse.jetty.websocket.api.Session;
-import org.qortal.data.block.BlockData;
-
-public class BlockNotifier {
-
-	private static BlockNotifier instance;
-
-	@FunctionalInterface
-	public interface Listener {
-		void notify(BlockData blockData);
-	}
-
-	private Map<Session, Listener> listenersBySession = new HashMap<>();
-
-	private BlockNotifier() {
-	}
-
-	public static synchronized BlockNotifier getInstance() {
-		if (instance == null)
-			instance = new BlockNotifier();
-
-		return instance;
-	}
-
-	public synchronized void register(Session session, Listener listener) {
-		this.listenersBySession.put(session, listener);
-	}
-
-	public synchronized void deregister(Session session) {
-		this.listenersBySession.remove(session);
-	}
-
-	public synchronized void onNewBlock(BlockData blockData) {
-		for (Listener listener : this.listenersBySession.values())
-			listener.notify(blockData);
-	}
-
-}

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

@@ -1,5 +1,7 @@
 package org.qortal.controller;
 
+import java.util.ArrayList;
+import java.util.Collection;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -27,22 +29,34 @@ public class ChatNotifier {
 		return instance;
 	}
 
-	public synchronized void register(Session session, Listener listener) {
-		this.listenersBySession.put(session, listener);
+	public void register(Session session, Listener listener) {
+		synchronized (this.listenersBySession) {
+			this.listenersBySession.put(session, listener);
+		}
 	}
 
-	public synchronized void deregister(Session session) {
-		this.listenersBySession.remove(session);
+	public void deregister(Session session) {
+		synchronized (this.listenersBySession) {
+			this.listenersBySession.remove(session);
+		}
 	}
 
-	public synchronized void onNewChatTransaction(ChatTransactionData chatTransactionData) {
-		for (Listener listener : this.listenersBySession.values())
+	public void onNewChatTransaction(ChatTransactionData chatTransactionData) {
+		for (Listener listener : getAllListeners())
 			listener.notify(chatTransactionData);
 	}
 
-	public synchronized void onGroupMembershipChange() {
-		for (Listener listener : this.listenersBySession.values())
+	public void onGroupMembershipChange() {
+		for (Listener listener : getAllListeners())
 			listener.notify(null);
 	}
 
+	private Collection<Listener> getAllListeners() {
+		// Make a copy of listeners to both avoid concurrent modification
+		// and reduce synchronization time
+		synchronized (this.listenersBySession) {
+			return new ArrayList<>(this.listenersBySession.values());
+		}
+	}
+
 }

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

@@ -0,0 +1,79 @@
+package org.qortal.controller;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.block.BlockChain;
+import org.qortal.data.block.BlockData;
+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;
+
+public class OnlineAccountsSignaturesTrimmer implements Runnable {
+
+	private static final Logger LOGGER = LogManager.getLogger(OnlineAccountsSignaturesTrimmer.class);
+
+	private static final long INITIAL_SLEEP_PERIOD = 5 * 60 * 1000L + 1234L; // ms
+
+	public void run() {
+		Thread.currentThread().setName("Online Accounts trimmer");
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			// Don't even start trimming until initial rush has ended
+			Thread.sleep(INITIAL_SLEEP_PERIOD);
+
+			int trimStartHeight = repository.getBlockRepository().getOnlineAccountsSignaturesTrimHeight();
+
+			while (!Controller.isStopping()) {
+				repository.discardChanges();
+
+				Thread.sleep(Settings.getInstance().getOnlineSignaturesTrimInterval());
+
+				BlockData chainTip = Controller.getInstance().getChainTip();
+				if (chainTip == null || NTP.getTime() == null)
+					continue;
+
+				// Don't even attempt if we're mid-sync as our repository requests will be delayed for ages
+				if (Controller.getInstance().isSynchronizing())
+					continue;
+
+				// Trim blockchain by removing 'old' online accounts signatures
+				long upperTrimmableTimestamp = NTP.getTime() - BlockChain.getInstance().getOnlineAccountSignaturesMaxLifetime();
+				int upperTrimmableHeight = repository.getBlockRepository().getHeightFromTimestamp(upperTrimmableTimestamp);
+
+				int upperBatchHeight = trimStartHeight + Settings.getInstance().getOnlineSignaturesTrimBatchSize();
+				int upperTrimHeight = Math.min(upperBatchHeight, upperTrimmableHeight);
+
+				if (trimStartHeight >= upperTrimHeight)
+					continue;
+
+				int numSigsTrimmed = repository.getBlockRepository().trimOldOnlineAccountsSignatures(trimStartHeight, upperTrimHeight);
+				repository.saveChanges();
+
+				if (numSigsTrimmed > 0) {
+					final int finalTrimStartHeight = trimStartHeight;
+					LOGGER.debug(() -> String.format("Trimmed %d online accounts signature%s between blocks %d and %d",
+							numSigsTrimmed, (numSigsTrimmed != 1 ? "s" : ""),
+							finalTrimStartHeight, upperTrimHeight));
+				} else {
+					// Can we move onto next batch?
+					if (upperTrimmableHeight > upperBatchHeight) {
+						trimStartHeight = upperBatchHeight;
+
+						repository.getBlockRepository().setOnlineAccountsSignaturesTrimHeight(trimStartHeight);
+						repository.saveChanges();
+
+						final int finalTrimStartHeight = trimStartHeight;
+						LOGGER.debug(() -> String.format("Bumping online accounts signatures base trim height to %d", finalTrimStartHeight));
+					}
+				}
+			}
+		} catch (DataException e) {
+			LOGGER.warn(String.format("Repository issue trying to trim online accounts signatures: %s", e.getMessage()));
+		} catch (InterruptedException e) {
+			// Time to exit
+		}
+	}
+
+}

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

@@ -1,42 +0,0 @@
-package org.qortal.controller;
-
-import java.util.HashMap;
-import java.util.Map;
-
-import org.eclipse.jetty.websocket.api.Session;
-
-public class StatusNotifier {
-
-	private static StatusNotifier instance;
-
-	@FunctionalInterface
-	public interface Listener {
-		void notify(long timestamp);
-	}
-
-	private Map<Session, Listener> listenersBySession = new HashMap<>();
-
-	private StatusNotifier() {
-	}
-
-	public static synchronized StatusNotifier getInstance() {
-		if (instance == null)
-			instance = new StatusNotifier();
-
-		return instance;
-	}
-
-	public synchronized void register(Session session, Listener listener) {
-		this.listenersBySession.put(session, listener);
-	}
-
-	public synchronized void deregister(Session session) {
-		this.listenersBySession.remove(session);
-	}
-
-	public synchronized void onStatusChange(long now) {
-		for (Listener listener : this.listenersBySession.values())
-			listener.notify(now);
-	}
-
-}

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

@@ -0,0 +1,30 @@
+package org.qortal.controller.tradebot;
+
+import java.util.List;
+
+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, TRADE_ALREADY_EXISTS }
+
+	/** Returns list of state names for trade-bot entries that have ended, e.g. redeemed, refunded or cancelled. */
+	public List<String> getEndStates();
+
+	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) throws DataException;
+
+	public void progress(Repository repository, TradeBotData tradeBotData) throws DataException, ForeignBlockchainException;
+
+}

src/main/java/org/qortal/controller/tradebot/LitecoinACCTv1TradeBot.java

@@ -0,0 +1,903 @@
+package org.qortal.controller.tradebot;
+
+import static java.util.Arrays.stream;
+import static java.util.stream.Collectors.toMap;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+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.ECKey;
+import org.bitcoinj.core.Transaction;
+import org.bitcoinj.core.TransactionOutput;
+import org.bitcoinj.script.Script.ScriptType;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.account.PublicKeyAccount;
+import org.qortal.api.model.crosschain.TradeBotCreateRequest;
+import org.qortal.asset.Asset;
+import org.qortal.crosschain.ACCT;
+import org.qortal.crosschain.AcctMode;
+import org.qortal.crosschain.ForeignBlockchainException;
+import org.qortal.crosschain.Litecoin;
+import org.qortal.crosschain.LitecoinACCTv1;
+import org.qortal.crosschain.SupportedBlockchain;
+import org.qortal.crosschain.BitcoinyHTLC;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.data.transaction.BaseTransactionData;
+import org.qortal.data.transaction.DeployAtTransactionData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.transaction.DeployAtTransaction;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.transaction.DeployAtTransactionTransformer;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+/**
+ * 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 LitecoinACCTv1TradeBot implements AcctTradeBot {
+
+	private static final Logger LOGGER = LogManager.getLogger(LitecoinACCTv1TradeBot.class);
+
+	public enum State implements TradeBot.StateNameAndValueSupplier {
+		BOB_WAITING_FOR_AT_CONFIRM(10, false, false),
+		BOB_WAITING_FOR_MESSAGE(15, true, true),
+		BOB_WAITING_FOR_AT_REDEEM(25, true, true),
+		BOB_DONE(30, false, false),
+		BOB_REFUNDED(35, false, false),
+
+		ALICE_WAITING_FOR_AT_LOCK(85, true, true),
+		ALICE_DONE(95, false, false),
+		ALICE_REFUNDING_A(105, true, true),
+		ALICE_REFUNDED(110, false, false);
+
+		private static final Map<Integer, State> map = stream(State.values()).collect(toMap(state -> state.value, state -> state));
+
+		public final int value;
+		public final boolean requiresAtData;
+		public final boolean requiresTradeData;
+
+		State(int value, boolean requiresAtData, boolean requiresTradeData) {
+			this.value = value;
+			this.requiresAtData = requiresAtData;
+			this.requiresTradeData = requiresTradeData;
+		}
+
+		public static State valueOf(int value) {
+			return map.get(value);
+		}
+
+		@Override
+		public String getState() {
+			return this.name();
+		}
+
+		@Override
+		public int getStateValue() {
+			return this.value;
+		}
+	}
+
+	/** Maximum time Bob waits for his AT creation transaction to be confirmed into a block. (milliseconds) */
+	private static final long MAX_AT_CONFIRMATION_PERIOD = 24 * 60 * 60 * 1000L; // ms
+
+	private static LitecoinACCTv1TradeBot instance;
+
+	private final List<String> endStates = Arrays.asList(State.BOB_DONE, State.BOB_REFUNDED, State.ALICE_DONE, State.ALICE_REFUNDING_A, State.ALICE_REFUNDED).stream()
+			.map(State::name)
+			.collect(Collectors.toUnmodifiableList());
+
+	private LitecoinACCTv1TradeBot() {
+	}
+
+	public static synchronized LitecoinACCTv1TradeBot getInstance() {
+		if (instance == null)
+			instance = new LitecoinACCTv1TradeBot();
+
+		return instance;
+	}
+
+	@Override
+	public List<String> getEndStates() {
+		return this.endStates;
+	}
+
+	/**
+	 * Creates a new trade-bot entry from the "Bob" viewpoint, i.e. OFFERing QORT in exchange for LTC.
+	 * <p>
+	 * Generates:
+	 * <ul>
+	 * 	<li>new 'trade' private key</li>
+	 * </ul>
+	 * Derives:
+	 * <ul>
+	 * 	<li>'native' (as in Qortal) public key, public key hash, address (starting with Q)</li>
+	 * 	<li>'foreign' (as in Litecoin) public key, public key hash</li>
+	 * </ul>
+	 * A Qortal AT is then constructed including the following as constants in the 'data segment':
+	 * <ul>
+	 * 	<li>'native'/Qortal 'trade' address - used as a MESSAGE contact</li>
+	 * 	<li>'foreign'/Litecoin public key hash - used by Alice's P2SH scripts to allow redeem</li>
+	 * 	<li>QORT amount on offer by Bob</li>
+	 * 	<li>LTC amount expected in return by Bob (from Alice)</li>
+	 * 	<li>trading timeout, in case things go wrong and everyone needs to refund</li>
+	 * </ul>
+	 * Returns a DEPLOY_AT transaction that needs to be signed and broadcast to the Qortal network.
+	 * <p>
+	 * Trade-bot will wait for Bob's AT to be deployed before taking next step.
+	 * <p>
+	 * @param repository
+	 * @param tradeBotCreateRequest
+	 * @return raw, unsigned DEPLOY_AT transaction
+	 * @throws DataException
+	 */
+	public byte[] createTrade(Repository repository, TradeBotCreateRequest tradeBotCreateRequest) throws DataException {
+		byte[] tradePrivateKey = TradeBot.generateTradePrivateKey();
+
+		byte[] tradeNativePublicKey = TradeBot.deriveTradeNativePublicKey(tradePrivateKey);
+		byte[] tradeNativePublicKeyHash = Crypto.hash160(tradeNativePublicKey);
+		String tradeNativeAddress = Crypto.toAddress(tradeNativePublicKey);
+
+		byte[] tradeForeignPublicKey = TradeBot.deriveTradeForeignPublicKey(tradePrivateKey);
+		byte[] tradeForeignPublicKeyHash = Crypto.hash160(tradeForeignPublicKey);
+
+		// Convert Litecoin receiving address into public key hash (we only support P2PKH at this time)
+		Address litecoinReceivingAddress;
+		try {
+			litecoinReceivingAddress = Address.fromString(Litecoin.getInstance().getNetworkParameters(), tradeBotCreateRequest.receivingAddress);
+		} catch (AddressFormatException e) {
+			throw new DataException("Unsupported Litecoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+		}
+		if (litecoinReceivingAddress.getOutputScriptType() != ScriptType.P2PKH)
+			throw new DataException("Unsupported Litecoin receiving address: " + tradeBotCreateRequest.receivingAddress);
+
+		byte[] litecoinReceivingAccountInfo = litecoinReceivingAddress.getHash();
+
+		PublicKeyAccount creator = new PublicKeyAccount(repository, tradeBotCreateRequest.creatorPublicKey);
+
+		// Deploy AT
+		long timestamp = NTP.getTime();
+		byte[] reference = creator.getLastReference();
+		long fee = 0L;
+		byte[] signature = null;
+		BaseTransactionData baseTransactionData = new BaseTransactionData(timestamp, Group.NO_GROUP, reference, creator.getPublicKey(), fee, signature);
+
+		String name = "QORT/LTC ACCT";
+		String description = "QORT/LTC cross-chain trade";
+		String aTType = "ACCT";
+		String tags = "ACCT QORT LTC";
+		byte[] creationBytes = LitecoinACCTv1.buildQortalAT(tradeNativeAddress, tradeForeignPublicKeyHash, tradeBotCreateRequest.qortAmount,
+				tradeBotCreateRequest.foreignAmount, tradeBotCreateRequest.tradeTimeout);
+		long amount = tradeBotCreateRequest.fundingQortAmount;
+
+		DeployAtTransactionData deployAtTransactionData = new DeployAtTransactionData(baseTransactionData, name, description, aTType, tags, creationBytes, amount, Asset.QORT);
+
+		DeployAtTransaction deployAtTransaction = new DeployAtTransaction(repository, deployAtTransactionData);
+		fee = deployAtTransaction.calcRecommendedFee();
+		deployAtTransactionData.setFee(fee);
+
+		DeployAtTransaction.ensureATAddress(deployAtTransactionData);
+		String atAddress = deployAtTransactionData.getAtAddress();
+
+		TradeBotData tradeBotData =  new TradeBotData(tradePrivateKey, LitecoinACCTv1.NAME,
+				State.BOB_WAITING_FOR_AT_CONFIRM.name(), State.BOB_WAITING_FOR_AT_CONFIRM.value,
+				creator.getAddress(), atAddress, timestamp, tradeBotCreateRequest.qortAmount,
+				tradeNativePublicKey, tradeNativePublicKeyHash, tradeNativeAddress,
+				null, null,
+				SupportedBlockchain.LITECOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				tradeBotCreateRequest.foreignAmount, null, null, null, litecoinReceivingAccountInfo);
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Built AT %s. Waiting for deployment", atAddress));
+
+		// Attempt to backup the trade bot data
+		TradeBot.backupTradeBotData(repository);
+
+		// Return to user for signing and broadcast as we don't have their Qortal private key
+		try {
+			return DeployAtTransactionTransformer.toBytes(deployAtTransactionData);
+		} catch (TransformationException e) {
+			throw new DataException("Failed to transform DEPLOY_AT transaction?", e);
+		}
+	}
+
+	/**
+	 * Creates a trade-bot entry from the 'Alice' viewpoint, i.e. matching LTC to an existing offer.
+	 * <p>
+	 * Requires a chosen trade offer from Bob, passed by <tt>crossChainTradeData</tt>
+	 * and access to a Litecoin wallet via <tt>xprv58</tt>.
+	 * <p>
+	 * The <tt>crossChainTradeData</tt> contains the current trade offer state
+	 * as extracted from the AT's data segment.
+	 * <p>
+	 * Access to a funded wallet is via a Litecoin BIP32 hierarchical deterministic key,
+	 * passed via <tt>xprv58</tt>.
+	 * <b>This key will be stored in your node's database</b>
+	 * to allow trade-bot to create/fund the necessary P2SH transactions!
+	 * However, due to the nature of BIP32 keys, it is possible to give the trade-bot
+	 * only a subset of wallet access (see BIP32 for more details).
+	 * <p>
+	 * As an example, the xprv58 can be extract from a <i>legacy, password-less</i>
+	 * Electrum wallet by going to the console tab and entering:<br>
+	 * <tt>wallet.keystore.xprv</tt><br>
+	 * which should result in a base58 string starting with either 'xprv' (for Litecoin main-net)
+	 * or 'tprv' for (Litecoin test-net).
+	 * <p>
+	 * It is envisaged that the value in <tt>xprv58</tt> will actually come from a Qortal-UI-managed wallet.
+	 * <p>
+	 * If sufficient funds are available, <b>this method will actually fund the P2SH-A</b>
+	 * with the Litecoin amount expected by 'Bob'.
+	 * <p>
+	 * If the Litecoin transaction is successfully broadcast to the network then
+	 * we also send a MESSAGE to Bob's trade-bot to let them know.
+	 * <p>
+	 * The trade-bot entry is saved to the repository and the cross-chain trading process commences.
+	 * <p>
+	 * @param repository
+	 * @param crossChainTradeData chosen trade OFFER that Alice wants to match
+	 * @param xprv58 funded wallet xprv in base58
+	 * @return true if P2SH-A funding transaction successfully broadcast to Litecoin network, false otherwise
+	 * @throws DataException
+	 */
+	public ResponseResult startResponse(Repository repository, ATData atData, ACCT acct, CrossChainTradeData crossChainTradeData, String xprv58, String receivingAddress) throws DataException {
+		byte[] tradePrivateKey = TradeBot.generateTradePrivateKey();
+		byte[] secretA = TradeBot.generateSecret();
+		byte[] hashOfSecretA = Crypto.hash160(secretA);
+
+		byte[] tradeNativePublicKey = TradeBot.deriveTradeNativePublicKey(tradePrivateKey);
+		byte[] tradeNativePublicKeyHash = Crypto.hash160(tradeNativePublicKey);
+		String tradeNativeAddress = Crypto.toAddress(tradeNativePublicKey);
+
+		byte[] tradeForeignPublicKey = TradeBot.deriveTradeForeignPublicKey(tradePrivateKey);
+		byte[] tradeForeignPublicKeyHash = Crypto.hash160(tradeForeignPublicKey);
+		byte[] receivingPublicKeyHash = Base58.decode(receivingAddress); // Actually the whole address, not just PKH
+
+		// We need to generate lockTime-A: add tradeTimeout to now
+		long now = NTP.getTime();
+		int lockTimeA = crossChainTradeData.tradeTimeout * 60 + (int) (now / 1000L);
+
+		TradeBotData tradeBotData =  new TradeBotData(tradePrivateKey, LitecoinACCTv1.NAME,
+				State.ALICE_WAITING_FOR_AT_LOCK.name(), State.ALICE_WAITING_FOR_AT_LOCK.value,
+				receivingAddress, crossChainTradeData.qortalAtAddress, now, crossChainTradeData.qortAmount,
+				tradeNativePublicKey, tradeNativePublicKeyHash, tradeNativeAddress,
+				secretA, hashOfSecretA,
+				SupportedBlockchain.LITECOIN.name(),
+				tradeForeignPublicKey, tradeForeignPublicKeyHash,
+				crossChainTradeData.expectedForeignAmount, xprv58, null, lockTimeA, receivingPublicKeyHash);
+
+		// Attempt to backup the trade bot data
+		TradeBot.backupTradeBotData(repository);
+
+		// Check we have enough funds via xprv58 to fund P2SH to cover expectedForeignAmount
+		long p2shFee;
+		try {
+			p2shFee = Litecoin.getInstance().getP2shFee(now);
+		} catch (ForeignBlockchainException e) {
+			LOGGER.debug("Couldn't estimate Litecoin fees?");
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		// Do not include fee for funding transaction as this is covered by buildSpend()
+		long amountA = crossChainTradeData.expectedForeignAmount + p2shFee /*redeeming/refunding P2SH-A*/;
+
+		// P2SH-A to be funded
+		byte[] redeemScriptBytes = BitcoinyHTLC.buildScript(tradeForeignPublicKeyHash, lockTimeA, crossChainTradeData.creatorForeignPKH, hashOfSecretA);
+		String p2shAddress = Litecoin.getInstance().deriveP2shAddress(redeemScriptBytes);
+
+		// Build transaction for funding P2SH-A
+		Transaction p2shFundingTransaction = Litecoin.getInstance().buildSpend(tradeBotData.getForeignKey(), p2shAddress, amountA);
+		if (p2shFundingTransaction == null) {
+			LOGGER.debug("Unable to build P2SH-A funding transaction - lack of funds?");
+			return ResponseResult.BALANCE_ISSUE;
+		}
+
+		try {
+			Litecoin.getInstance().broadcastTransaction(p2shFundingTransaction);
+		} catch (ForeignBlockchainException e) {
+			// We couldn't fund P2SH-A at this time
+			LOGGER.debug("Couldn't broadcast P2SH-A funding transaction?");
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		// Attempt to send MESSAGE to Bob's Qortal trade address
+		byte[] messageData = LitecoinACCTv1.buildOfferMessage(tradeBotData.getTradeForeignPublicKeyHash(), tradeBotData.getHashOfSecret(), tradeBotData.getLockTimeA());
+		String messageRecipient = crossChainTradeData.qortalCreatorTradeAddress;
+
+		boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, messageData);
+		if (!isMessageAlreadySent) {
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK) {
+				LOGGER.warn(() -> String.format("Unable to send MESSAGE to Bob's trade-bot %s: %s", messageRecipient, result.name()));
+				return ResponseResult.NETWORK_ISSUE;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Funding P2SH-A %s. Messaged Bob. Waiting for AT-lock", p2shAddress));
+
+		return ResponseResult.OK;
+	}
+
+	@Override
+	public boolean canDelete(Repository repository, TradeBotData tradeBotData) throws DataException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null)
+			return true;
+
+		// If the AT doesn't exist then we might as well let the user tidy up
+		if (!repository.getATRepository().exists(tradeBotData.getAtAddress()))
+			return true;
+
+		switch (tradeBotState) {
+			case BOB_WAITING_FOR_AT_CONFIRM:
+			case ALICE_DONE:
+			case BOB_DONE:
+			case ALICE_REFUNDED:
+			case BOB_REFUNDED:
+				return true;
+
+			default:
+				return false;
+		}
+	}
+
+	@Override
+	public void progress(Repository repository, TradeBotData tradeBotData) throws DataException, ForeignBlockchainException {
+		State tradeBotState = State.valueOf(tradeBotData.getStateValue());
+		if (tradeBotState == null) {
+			LOGGER.info(() -> String.format("Trade-bot entry for AT %s has invalid state?", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		ATData atData = null;
+		CrossChainTradeData tradeData = null;
+
+		if (tradeBotState.requiresAtData) {
+			// Attempt to fetch AT data
+			atData = repository.getATRepository().fromATAddress(tradeBotData.getAtAddress());
+			if (atData == null) {
+				LOGGER.debug(() -> String.format("Unable to fetch trade AT %s from repository", tradeBotData.getAtAddress()));
+
+				// If it has been over 24 hours since we last updated this trade-bot entry then assume AT is never coming back
+				// and so wipe the trade-bot entry
+				if (tradeBotData.getTimestamp() + MAX_AT_CONFIRMATION_PERIOD < NTP.getTime()) {
+					LOGGER.info(() -> String.format("AT %s has been gone for too long - deleting trade-bot entry", tradeBotData.getAtAddress()));
+					repository.getCrossChainRepository().delete(tradeBotData.getTradePrivateKey());
+					repository.saveChanges();
+				}
+
+				return;
+			}
+
+			if (tradeBotState.requiresTradeData) {
+				tradeData = LitecoinACCTv1.getInstance().populateTradeData(repository, atData);
+				if (tradeData == null) {
+					LOGGER.warn(() -> String.format("Unable to fetch ACCT trade data for AT %s from repository", tradeBotData.getAtAddress()));
+					return;
+				}
+			}
+		}
+
+		switch (tradeBotState) {
+			case BOB_WAITING_FOR_AT_CONFIRM:
+				handleBobWaitingForAtConfirm(repository, tradeBotData);
+				break;
+
+			case BOB_WAITING_FOR_MESSAGE:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleBobWaitingForMessage(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_WAITING_FOR_AT_LOCK:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleAliceWaitingForAtLock(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case BOB_WAITING_FOR_AT_REDEEM:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleBobWaitingForAtRedeem(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_DONE:
+			case BOB_DONE:
+				break;
+
+			case ALICE_REFUNDING_A:
+				TradeBot.getInstance().updatePresence(repository, tradeBotData, tradeData);
+				handleAliceRefundingP2shA(repository, tradeBotData, atData, tradeData);
+				break;
+
+			case ALICE_REFUNDED:
+			case BOB_REFUNDED:
+				break;
+		}
+	}
+
+	/**
+	 * Trade-bot is waiting for Bob's AT to deploy.
+	 * <p>
+	 * If AT is deployed, then trade-bot's next step is to wait for MESSAGE from Alice.
+	 */
+	private void handleBobWaitingForAtConfirm(Repository repository, TradeBotData tradeBotData) throws DataException {
+		if (!repository.getATRepository().exists(tradeBotData.getAtAddress())) {
+			if (NTP.getTime() - tradeBotData.getTimestamp() <= MAX_AT_CONFIRMATION_PERIOD)
+				return;
+
+			// We've waited ages for AT to be confirmed into a block but something has gone awry.
+			// After this long we assume transaction loss so give up with trade-bot entry too.
+			tradeBotData.setState(State.BOB_REFUNDED.name());
+			tradeBotData.setStateValue(State.BOB_REFUNDED.value);
+			tradeBotData.setTimestamp(NTP.getTime());
+			// We delete trade-bot entry here instead of saving, hence not using updateTradeBotState()
+			repository.getCrossChainRepository().delete(tradeBotData.getTradePrivateKey());
+			repository.saveChanges();
+
+			LOGGER.info(() -> String.format("AT %s never confirmed. Giving up on trade", tradeBotData.getAtAddress()));
+			TradeBot.notifyStateChange(tradeBotData);
+			return;
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_WAITING_FOR_MESSAGE,
+				() -> String.format("AT %s confirmed ready. Waiting for trade message", tradeBotData.getAtAddress()));
+	}
+
+	/**
+	 * Trade-bot is waiting for MESSAGE from Alice's trade-bot, containing Alice's trade info.
+	 * <p>
+	 * It's possible Bob has cancelling his trade offer, receiving an automatic QORT refund,
+	 * in which case trade-bot is done with this specific trade and finalizes on refunded state.
+	 * <p>
+	 * Assuming trade is still on offer, trade-bot checks the contents of MESSAGE from Alice's trade-bot.
+	 * <p>
+	 * Details from Alice are used to derive P2SH-A address and this is checked for funding balance.
+	 * <p>
+	 * Assuming P2SH-A has at least expected Litecoin balance,
+	 * Bob's trade-bot constructs a zero-fee, PoW MESSAGE to send to Bob's AT with more trade details.
+	 * <p>
+	 * On processing this MESSAGE, Bob's AT should switch into 'TRADE' mode and only trade with Alice.
+	 * <p>
+	 * Trade-bot's next step is to wait for Alice to redeem the AT, which will allow Bob to
+	 * extract secret-A needed to redeem Alice's P2SH.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleBobWaitingForMessage(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// If AT has finished then Bob likely cancelled his trade offer
+		if (atData.getIsFinished()) {
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_REFUNDED,
+					() -> String.format("AT %s cancelled - trading aborted", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		String address = tradeBotData.getTradeNativeAddress();
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(null, address, null, null, null);
+
+		for (MessageTransactionData messageTransactionData : messageTransactionsData) {
+			if (messageTransactionData.isText())
+				continue;
+
+			// We're expecting: HASH160(secret-A), Alice's Litecoin pubkeyhash and lockTime-A
+			byte[] messageData = messageTransactionData.getData();
+			LitecoinACCTv1.OfferMessageData offerMessageData = LitecoinACCTv1.extractOfferMessageData(messageData);
+			if (offerMessageData == null)
+				continue;
+
+			byte[] aliceForeignPublicKeyHash = offerMessageData.partnerLitecoinPKH;
+			byte[] hashOfSecretA = offerMessageData.hashOfSecretA;
+			int lockTimeA = (int) offerMessageData.lockTimeA;
+			long messageTimestamp = messageTransactionData.getTimestamp();
+			int refundTimeout = LitecoinACCTv1.calcRefundTimeout(messageTimestamp, lockTimeA);
+
+			// Determine P2SH-A address and confirm funded
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(aliceForeignPublicKeyHash, lockTimeA, tradeBotData.getTradeForeignPublicKeyHash(), hashOfSecretA);
+			String p2shAddressA = litecoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Litecoin.getInstance().getP2shFee(feeTimestamp);
+			final long minimumAmountA = tradeBotData.getForeignAmount() + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(litecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+			switch (htlcStatusA) {
+				case UNFUNDED:
+				case FUNDING_IN_PROGRESS:
+					// There might be another MESSAGE from someone else with an actually funded P2SH-A...
+					continue;
+
+				case REDEEM_IN_PROGRESS:
+				case REDEEMED:
+					// We've already redeemed this?
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_DONE,
+							() -> String.format("P2SH-A %s already spent? Assuming trade complete", p2shAddressA));
+					return;
+
+				case REFUND_IN_PROGRESS:
+				case REFUNDED:
+					// This P2SH-A is burnt, but there might be another MESSAGE from someone else with an actually funded P2SH-A...
+					continue;
+
+				case FUNDED:
+					// Fall-through out of switch...
+					break;
+			}
+
+			// Good to go - send MESSAGE to AT
+
+			String aliceNativeAddress = Crypto.toAddress(messageTransactionData.getCreatorPublicKey());
+
+			// Build outgoing message, padding each part to 32 bytes to make it easier for AT to consume
+			byte[] outgoingMessageData = LitecoinACCTv1.buildTradeMessage(aliceNativeAddress, aliceForeignPublicKeyHash, hashOfSecretA, lockTimeA, refundTimeout);
+			String messageRecipient = tradeBotData.getAtAddress();
+
+			boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, outgoingMessageData);
+			if (!isMessageAlreadySent) {
+				PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+				MessageTransaction outgoingMessageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, outgoingMessageData, false, false);
+
+				outgoingMessageTransaction.computeNonce();
+				outgoingMessageTransaction.sign(sender);
+
+				// reset repository state to prevent deadlock
+				repository.discardChanges();
+				ValidationResult result = outgoingMessageTransaction.importAsUnconfirmed();
+
+				if (result != ValidationResult.OK) {
+					LOGGER.warn(() -> String.format("Unable to send MESSAGE to AT %s: %s", messageRecipient, result.name()));
+					return;
+				}
+			}
+
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_WAITING_FOR_AT_REDEEM,
+					() -> String.format("Locked AT %s to %s. Waiting for AT redeem", tradeBotData.getAtAddress(), aliceNativeAddress));
+
+			return;
+		}
+	}
+
+	/**
+	 * Trade-bot is waiting for Bob's AT to switch to TRADE mode and lock trade to Alice only.
+	 * <p>
+	 * It's possible that Bob has cancelled his trade offer in the mean time, or that somehow
+	 * this process has taken so long that we've reached P2SH-A's locktime, or that someone else
+	 * has managed to trade with Bob. In any of these cases, trade-bot switches to begin the refunding process.
+	 * <p>
+	 * Assuming Bob's AT is locked to Alice, trade-bot checks AT's state data to make sure it is correct.
+	 * <p>
+	 * If all is well, trade-bot then redeems AT using Alice's secret-A, releasing Bob's QORT to Alice.
+	 * <p>
+	 * In revealing a valid secret-A, Bob can then redeem the LTC funds from P2SH-A.
+	 * <p>
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleAliceWaitingForAtLock(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		if (aliceUnexpectedState(repository, tradeBotData, atData, crossChainTradeData))
+			return;
+
+		Litecoin litecoin = Litecoin.getInstance();
+		int lockTimeA = tradeBotData.getLockTimeA();
+
+		// Refund P2SH-A if we've passed lockTime-A
+		if (NTP.getTime() >= lockTimeA * 1000L) {
+			byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeA, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+			String p2shAddressA = litecoin.deriveP2shAddress(redeemScriptA);
+
+			long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+			long p2shFee = Litecoin.getInstance().getP2shFee(feeTimestamp);
+			long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+
+			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(litecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+			switch (htlcStatusA) {
+				case UNFUNDED:
+				case FUNDING_IN_PROGRESS:
+				case FUNDED:
+					break;
+
+				case REDEEM_IN_PROGRESS:
+				case REDEEMED:
+					// Already redeemed?
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+							() -> String.format("P2SH-A %s already spent? Assuming trade completed", p2shAddressA));
+					return;
+
+				case REFUND_IN_PROGRESS:
+				case REFUNDED:
+					TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDED,
+							() -> String.format("P2SH-A %s already refunded. Trade aborted", p2shAddressA));
+					return;
+
+			}
+
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+					() -> atData.getIsFinished()
+					? String.format("AT %s cancelled. Refunding P2SH-A %s - aborting trade", tradeBotData.getAtAddress(), p2shAddressA)
+					: String.format("LockTime-A reached, refunding P2SH-A %s - aborting trade", p2shAddressA));
+
+			return;
+		}
+
+		// We're waiting for AT to be in TRADE mode
+		if (crossChainTradeData.mode != AcctMode.TRADING)
+			return;
+
+		// AT is in TRADE mode and locked to us as checked by aliceUnexpectedState() above
+
+		// Find our MESSAGE to AT from previous state
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(tradeBotData.getTradeNativePublicKey(),
+				crossChainTradeData.qortalCreatorTradeAddress, null, null, null);
+		if (messageTransactionsData == null || messageTransactionsData.isEmpty()) {
+			LOGGER.warn(() -> String.format("Unable to find our message to trade creator %s?", crossChainTradeData.qortalCreatorTradeAddress));
+			return;
+		}
+
+		long recipientMessageTimestamp = messageTransactionsData.get(0).getTimestamp();
+		int refundTimeout = LitecoinACCTv1.calcRefundTimeout(recipientMessageTimestamp, lockTimeA);
+
+		// Our calculated refundTimeout should match AT's refundTimeout
+		if (refundTimeout != crossChainTradeData.refundTimeout) {
+			LOGGER.debug(() -> String.format("Trade AT refundTimeout '%d' doesn't match our refundTimeout '%d'", crossChainTradeData.refundTimeout, refundTimeout));
+			// We'll eventually refund
+			return;
+		}
+
+		// We're good to redeem AT
+
+		// Send 'redeem' MESSAGE to AT using both secret
+		byte[] secretA = tradeBotData.getSecret();
+		String qortalReceivingAddress = Base58.encode(tradeBotData.getReceivingAccountInfo()); // Actually contains whole address, not just PKH
+		byte[] messageData = LitecoinACCTv1.buildRedeemMessage(secretA, qortalReceivingAddress);
+		String messageRecipient = tradeBotData.getAtAddress();
+
+		boolean isMessageAlreadySent = repository.getMessageRepository().exists(tradeBotData.getTradeNativePublicKey(), messageRecipient, messageData);
+		if (!isMessageAlreadySent) {
+			PrivateKeyAccount sender = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+			MessageTransaction messageTransaction = MessageTransaction.build(repository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
+
+			messageTransaction.computeNonce();
+			messageTransaction.sign(sender);
+
+			// Reset repository state to prevent deadlock
+			repository.discardChanges();
+			ValidationResult result = messageTransaction.importAsUnconfirmed();
+
+			if (result != ValidationResult.OK) {
+				LOGGER.warn(() -> String.format("Unable to send MESSAGE to AT %s: %s", messageRecipient, result.name()));
+				return;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+				() -> String.format("Redeeming AT %s. Funds should arrive at %s",
+						tradeBotData.getAtAddress(), qortalReceivingAddress));
+	}
+
+	/**
+	 * Trade-bot is waiting for Alice to redeem Bob's AT, thus revealing secret-A which is required to spend the LTC funds from P2SH-A.
+	 * <p>
+	 * It's possible that Bob's AT has reached its trading timeout and automatically refunded QORT back to Bob. In which case,
+	 * trade-bot is done with this specific trade and finalizes in refunded state.
+	 * <p>
+	 * Assuming trade-bot can extract a valid secret-A from Alice's MESSAGE then trade-bot uses that to redeem the LTC funds from P2SH-A
+	 * to Bob's 'foreign'/Litecoin trade legacy-format address, as derived from trade private key.
+	 * <p>
+	 * (This could potentially be 'improved' to send LTC to any address of Bob's choosing by changing the transaction output).
+	 * <p>
+	 * If trade-bot successfully broadcasts the transaction, then this specific trade is done.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleBobWaitingForAtRedeem(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// AT should be 'finished' once Alice has redeemed QORT funds
+		if (!atData.getIsFinished())
+			// Not finished yet
+			return;
+
+		// If AT is not REDEEMED then something has gone wrong
+		if (crossChainTradeData.mode != AcctMode.REDEEMED) {
+			// Not redeemed so must be refunded/cancelled
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_REFUNDED,
+					() -> String.format("AT %s has auto-refunded - trade aborted", tradeBotData.getAtAddress()));
+
+			return;
+		}
+
+		byte[] secretA = LitecoinACCTv1.findSecretA(repository, crossChainTradeData);
+		if (secretA == null) {
+			LOGGER.debug(() -> String.format("Unable to find secret-A from redeem message to AT %s?", tradeBotData.getAtAddress()));
+			return;
+		}
+
+		// Use secret-A to redeem P2SH-A
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		byte[] receivingAccountInfo = tradeBotData.getReceivingAccountInfo();
+		int lockTimeA = crossChainTradeData.lockTimeA;
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(crossChainTradeData.partnerForeignPKH, lockTimeA, crossChainTradeData.creatorForeignPKH, crossChainTradeData.hashOfSecretA);
+		String p2shAddressA = litecoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Litecoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(litecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+		switch (htlcStatusA) {
+			case UNFUNDED:
+			case FUNDING_IN_PROGRESS:
+				// P2SH-A suddenly not funded? Our best bet at this point is to hope for AT auto-refund
+				return;
+
+			case REDEEM_IN_PROGRESS:
+			case REDEEMED:
+				// Double-check that we have redeemed P2SH-A...
+				break;
+
+			case REFUND_IN_PROGRESS:
+			case REFUNDED:
+				// Wait for AT to auto-refund
+				return;
+
+			case FUNDED: {
+				Coin redeemAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
+				ECKey redeemKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
+				List<TransactionOutput> fundingOutputs = litecoin.getUnspentOutputs(p2shAddressA);
+
+				Transaction p2shRedeemTransaction = BitcoinyHTLC.buildRedeemTransaction(litecoin.getNetworkParameters(), redeemAmount, redeemKey,
+						fundingOutputs, redeemScriptA, secretA, receivingAccountInfo);
+
+				litecoin.broadcastTransaction(p2shRedeemTransaction);
+				break;
+			}
+		}
+
+		String receivingAddress = litecoin.pkhToAddress(receivingAccountInfo);
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.BOB_DONE,
+				() -> String.format("P2SH-A %s redeemed. Funds should arrive at %s", tradeBotData.getAtAddress(), receivingAddress));
+	}
+
+	/**
+	 * Trade-bot is attempting to refund P2SH-A.
+	 * @throws ForeignBlockchainException
+	 */
+	private void handleAliceRefundingP2shA(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		int lockTimeA = tradeBotData.getLockTimeA();
+
+		// We can't refund P2SH-A until lockTime-A has passed
+		if (NTP.getTime() <= lockTimeA * 1000L)
+			return;
+
+		Litecoin litecoin = Litecoin.getInstance();
+
+		// We can't refund P2SH-A until median block time has passed lockTime-A (see BIP113)
+		int medianBlockTime = litecoin.getMedianBlockTime();
+		if (medianBlockTime <= lockTimeA)
+			return;
+
+		byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTimeA, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+		String p2shAddressA = litecoin.deriveP2shAddress(redeemScriptA);
+
+		// Fee for redeem/refund is subtracted from P2SH-A balance.
+		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
+		long p2shFee = Litecoin.getInstance().getP2shFee(feeTimestamp);
+		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+		BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(litecoin.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+		switch (htlcStatusA) {
+			case UNFUNDED:
+			case FUNDING_IN_PROGRESS:
+				// Still waiting for P2SH-A to be funded...
+				return;
+
+			case REDEEM_IN_PROGRESS:
+			case REDEEMED:
+				// Too late!
+				TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+						() -> String.format("P2SH-A %s already spent!", p2shAddressA));
+				return;
+
+			case REFUND_IN_PROGRESS:
+			case REFUNDED:
+				break;
+
+			case FUNDED:{
+				Coin refundAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
+				ECKey refundKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
+				List<TransactionOutput> fundingOutputs = litecoin.getUnspentOutputs(p2shAddressA);
+
+				// Determine receive address for refund
+				String receiveAddress = litecoin.getUnusedReceiveAddress(tradeBotData.getForeignKey());
+				Address receiving = Address.fromString(litecoin.getNetworkParameters(), receiveAddress);
+
+				Transaction p2shRefundTransaction = BitcoinyHTLC.buildRefundTransaction(litecoin.getNetworkParameters(), refundAmount, refundKey,
+						fundingOutputs, redeemScriptA, lockTimeA, receiving.getHash());
+
+				litecoin.broadcastTransaction(p2shRefundTransaction);
+				break;
+			}
+		}
+
+		TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDED,
+				() -> String.format("LockTime-A reached. Refunded P2SH-A %s. Trade aborted", p2shAddressA));
+	}
+
+	/**
+	 * Returns true if Alice finds AT unexpectedly cancelled, refunded, redeemed or locked to someone else.
+	 * <p>
+	 * Will automatically update trade-bot state to <tt>ALICE_REFUNDING_A</tt> or <tt>ALICE_DONE</tt> as necessary.
+	 * 
+	 * @throws DataException
+	 * @throws ForeignBlockchainException
+	 */
+	private boolean aliceUnexpectedState(Repository repository, TradeBotData tradeBotData,
+			ATData atData, CrossChainTradeData crossChainTradeData) throws DataException, ForeignBlockchainException {
+		// This is OK
+		if (!atData.getIsFinished() && crossChainTradeData.mode == AcctMode.OFFERING)
+			return false;
+
+		boolean isAtLockedToUs = tradeBotData.getTradeNativeAddress().equals(crossChainTradeData.qortalPartnerAddress);
+
+		if (!atData.getIsFinished() && crossChainTradeData.mode == AcctMode.TRADING)
+			if (isAtLockedToUs) {
+				// AT is trading with us - OK
+				return false;
+			} else {
+				TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+						() -> String.format("AT %s trading with someone else: %s. Refunding & aborting trade", tradeBotData.getAtAddress(), crossChainTradeData.qortalPartnerAddress));
+
+				return true;
+			}
+
+		if (atData.getIsFinished() && crossChainTradeData.mode == AcctMode.REDEEMED && isAtLockedToUs) {
+			// We've redeemed already?
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_DONE,
+					() -> String.format("AT %s already redeemed by us. Trade completed", tradeBotData.getAtAddress()));
+		} else {
+			// Any other state is not good, so start defensive refund
+			TradeBot.updateTradeBotState(repository, tradeBotData, State.ALICE_REFUNDING_A,
+					() -> String.format("AT %s cancelled/refunded/redeemed by someone else/invalid state. Refunding & aborting trade", tradeBotData.getAtAddress()));
+		}
+
+		return true;
+	}
+
+	private long calcFeeTimestamp(int lockTimeA, int tradeTimeout) {
+		return (lockTimeA - tradeTimeout * 60) * 1000L;
+	}
+
+}

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

@@ -0,0 +1,379 @@
+package org.qortal.controller.tradebot;
+
+import java.awt.TrayIcon.MessageType;
+import java.security.SecureRandom;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Random;
+import java.util.concurrent.locks.ReentrantLock;
+
+import 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.data.transaction.BaseTransactionData;
+import org.qortal.data.transaction.PresenceTransactionData;
+import org.qortal.event.Event;
+import org.qortal.event.EventBus;
+import org.qortal.event.Listener;
+import org.qortal.group.Group;
+import org.qortal.gui.SysTray;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.settings.Settings;
+import org.qortal.transaction.PresenceTransaction;
+import org.qortal.transaction.PresenceTransaction.PresenceType;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.transform.transaction.TransactionTransformer;
+import org.qortal.utils.NTP;
+
+import com.google.common.primitives.Longs;
+
+/**
+ * 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 final Map<String, Long> presenceTimestampsByAtAddress = Collections.synchronizedMap(new HashMap<>());
+
+	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;
+		}
+
+		// Check Alice doesn't already have an existing, on-going trade-bot entry for this AT.
+		if (repository.getCrossChainRepository().existsTradeWithAtExcludingStates(atData.getATAddress(), acctTradeBot.getEndStates()))
+			return ResponseResult.TRADE_ALREADY_EXISTS;
+
+		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);
+			repository.saveChanges();
+		}
+
+		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("Foreign blockchain 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;
+	}
+
+	/*package*/ static void backupTradeBotData(Repository repository) {
+		// Attempt to backup the trade bot data. This an optional step and doesn't impact trading, so don't throw an exception on failure
+		try {
+			LOGGER.info("About to backup trade bot data...");
+			ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
+			blockchainLock.lockInterruptibly();
+			try {
+				repository.exportNodeLocalData(true);
+			} finally {
+				blockchainLock.unlock();
+			}
+		} catch (InterruptedException | DataException e) {
+			LOGGER.info(String.format("Failed to obtain blockchain lock when exporting trade bot data: %s", e.getMessage()));
+		}
+	}
+
+	/** Updates trade-bot entry to new state, with current timestamp, logs message and notifies state-change listeners. */
+	/*package*/ static void updateTradeBotState(Repository repository, TradeBotData tradeBotData,
+			String newState, int newStateValue, Supplier<String> logMessageSupplier) throws DataException {
+		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();
+	}
+
+	// PRESENCE-related
+	/*package*/ void updatePresence(Repository repository, TradeBotData tradeBotData, CrossChainTradeData tradeData)
+			throws DataException {
+		String atAddress = tradeBotData.getAtAddress();
+
+		PrivateKeyAccount tradeNativeAccount = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+		String signerAddress = tradeNativeAccount.getAddress();
+
+		/*
+		 * There's no point in Alice trying to build a PRESENCE transaction
+		 * for an AT that isn't locked to her, as other peers won't be able
+		 * to validate the PRESENCE transaction as signing public key won't
+		 * be visible.
+		 */
+		if (!signerAddress.equals(tradeData.qortalCreatorTradeAddress) && !signerAddress.equals(tradeData.qortalPartnerAddress))
+			// Signer is neither Bob, nor Alice, or trade not yet locked to Alice
+			return;
+
+		long now = NTP.getTime();
+		long threshold = now - PresenceType.TRADE_BOT.getLifetime();
+
+		long timestamp = presenceTimestampsByAtAddress.compute(atAddress, (k, v) -> (v == null || v < threshold) ? now : v);
+
+		// If timestamp hasn't been updated then nothing to do
+		if (timestamp != now)
+			return;
+
+		int txGroupId = Group.NO_GROUP;
+		byte[] reference = new byte[TransactionTransformer.SIGNATURE_LENGTH];
+		byte[] creatorPublicKey = tradeNativeAccount.getPublicKey();
+		long fee = 0L;
+
+		BaseTransactionData baseTransactionData = new BaseTransactionData(timestamp, txGroupId, reference, creatorPublicKey, fee, null);
+
+		int nonce = 0;
+		byte[] timestampSignature = tradeNativeAccount.sign(Longs.toByteArray(timestamp));
+
+		PresenceTransactionData transactionData = new PresenceTransactionData(baseTransactionData, nonce, PresenceType.TRADE_BOT, timestampSignature);
+
+		PresenceTransaction presenceTransaction = new PresenceTransaction(repository, transactionData);
+		presenceTransaction.computeNonce();
+
+		presenceTransaction.sign(tradeNativeAccount);
+
+		ValidationResult result = presenceTransaction.importAsUnconfirmed();
+		if (result != ValidationResult.OK)
+			LOGGER.debug(() -> String.format("Unable to build trade-bot PRESENCE transaction for %s: %s", tradeBotData.getAtAddress(), result.name()));
+	}
+
+}

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

@@ -0,0 +1,23 @@
+package org.qortal.crosschain;
+
+import org.qortal.data.at.ATData;
+import org.qortal.data.at.ATStateData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+
+public interface ACCT {
+
+	public byte[] getCodeBytesHash();
+
+	public int getModeByteOffset();
+
+	public ForeignBlockchain getBlockchain();
+
+	public CrossChainTradeData populateTradeData(Repository repository, ATData atData) throws DataException;
+
+	public CrossChainTradeData populateTradeData(Repository repository, ATStateData atStateData) throws DataException;
+
+	public byte[] buildCancelMessage(String creatorQortalAddress);
+
+}

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

@@ -0,0 +1,21 @@
+package org.qortal.crosschain;
+
+import static java.util.Arrays.stream;
+import static java.util.stream.Collectors.toMap;
+
+import java.util.Map;
+
+public enum AcctMode {
+	OFFERING(0), TRADING(1), CANCELLED(2), REFUNDED(3), REDEEMED(4);
+
+	public final int value;
+	private static final Map<Integer, AcctMode> map = stream(AcctMode.values()).collect(toMap(mode -> mode.value, mode -> mode));
+
+	AcctMode(int value) {
+		this.value = value;
+	}
+
+	public static AcctMode valueOf(int value) {
+		return map.get(value);
+	}
+}

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

@@ -1,159 +0,0 @@
-package org.qortal.crosschain;
-
-import java.util.ArrayList;
-import java.util.List;
-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.Coin;
-import org.bitcoinj.core.NetworkParameters;
-import org.bitcoinj.core.Transaction;
-import org.bitcoinj.core.TransactionOutput;
-import org.bitcoinj.params.MainNetParams;
-import org.bitcoinj.params.RegTestParams;
-import org.bitcoinj.params.TestNet3Params;
-import org.bitcoinj.script.ScriptBuilder;
-import org.bitcoinj.utils.MonetaryFormat;
-import org.qortal.settings.Settings;
-import org.qortal.utils.BitTwiddling;
-import org.qortal.utils.Pair;
-
-public class BTC {
-
-	public static final MonetaryFormat FORMAT = new MonetaryFormat().minDecimals(8).postfixCode();
-	public static final long NO_LOCKTIME_NO_RBF_SEQUENCE = 0xFFFFFFFFL;
-	public static final long LOCKTIME_NO_RBF_SEQUENCE = NO_LOCKTIME_NO_RBF_SEQUENCE - 1;
-	public static final int HASH160_LENGTH = 20;
-
-	protected static final Logger LOGGER = LogManager.getLogger(BTC.class);
-
-	private static final int TIMESTAMP_OFFSET = 4 + 32 + 32;
-
-	public enum BitcoinNet {
-		MAIN {
-			@Override
-			public NetworkParameters getParams() {
-				return MainNetParams.get();
-			}
-		},
-		TEST3 {
-			@Override
-			public NetworkParameters getParams() {
-				return TestNet3Params.get();
-			}
-		},
-		REGTEST {
-			@Override
-			public NetworkParameters getParams() {
-				return RegTestParams.get();
-			}
-		};
-
-		public abstract NetworkParameters getParams();
-	}
-
-	private static BTC instance;
-	private final NetworkParameters params;
-	private final ElectrumX electrumX;
-
-	// Constructors and instance
-
-	private BTC() {
-		BitcoinNet bitcoinNet = Settings.getInstance().getBitcoinNet();
-		this.params = bitcoinNet.getParams();
-
-		LOGGER.info(() -> String.format("Starting Bitcoin support using %s", bitcoinNet.name()));
-
-		this.electrumX = ElectrumX.getInstance(bitcoinNet.name());
-	}
-
-	public static synchronized BTC getInstance() {
-		if (instance == null)
-			instance = new BTC();
-
-		return instance;
-	}
-
-	// Getters & setters
-
-	public NetworkParameters getNetworkParameters() {
-		return this.params;
-	}
-
-	public static synchronized void resetForTesting() {
-		instance = null;
-	}
-
-	// Actual useful methods for use by other classes
-
-	/** Returns median timestamp from latest 11 blocks, in seconds. */
-	public Integer getMedianBlockTime() {
-		Integer height = this.electrumX.getCurrentHeight();
-		if (height == null)
-			return null;
-
-		// Grab latest 11 blocks
-		List<byte[]> blockHeaders = this.electrumX.getBlockHeaders(height - 11, 11);
-		if (blockHeaders == null || blockHeaders.size() < 11)
-			return null;
-
-		List<Integer> blockTimestamps = blockHeaders.stream().map(blockHeader -> BitTwiddling.fromLEBytes(blockHeader, TIMESTAMP_OFFSET)).collect(Collectors.toList());
-
-		// Descending, but order shouldn't matter as we're picking median...
-		blockTimestamps.sort((a, b) -> Integer.compare(b, a));
-
-		return blockTimestamps.get(5);
-	}
-
-	public Coin getBalance(String base58Address) {
-		Long balance = this.electrumX.getBalance(addressToScript(base58Address));
-		if (balance == null)
-			return null;
-
-		return Coin.valueOf(balance);
-	}
-
-	public List<TransactionOutput> getUnspentOutputs(String base58Address) {
-		List<Pair<byte[], Integer>> unspentOutputs = this.electrumX.getUnspentOutputs(addressToScript(base58Address));
-		if (unspentOutputs == null)
-			return null;
-
-		List<TransactionOutput> unspentTransactionOutputs = new ArrayList<>();
-		for (Pair<byte[], Integer> unspentOutput : unspentOutputs) {
-			List<TransactionOutput> transactionOutputs = getOutputs(unspentOutput.getA());
-			if (transactionOutputs == null)
-				return null;
-
-			unspentTransactionOutputs.add(transactionOutputs.get(unspentOutput.getB()));
-		}
-
-		return unspentTransactionOutputs;
-	}
-
-	public List<TransactionOutput> getOutputs(byte[] txHash) {
-		byte[] rawTransactionBytes = this.electrumX.getRawTransaction(txHash);
-		if (rawTransactionBytes == null)
-			return null;
-
-		Transaction transaction = new Transaction(this.params, rawTransactionBytes);
-		return transaction.getOutputs();
-	}
-
-	public List<byte[]> getAddressTransactions(String base58Address) {
-		return this.electrumX.getAddressTransactions(addressToScript(base58Address));
-	}
-
-	public boolean broadcastTransaction(Transaction transaction) {
-		return this.electrumX.broadcastTransaction(transaction.bitcoinSerialize());
-	}
-
-	// Utility methods for us
-
-	private byte[] addressToScript(String base58Address) {
-		Address address = Address.fromString(this.params, base58Address);
-		return ScriptBuilder.createOutputScript(address).getProgram();
-	}
-
-}

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

@@ -1,669 +0,0 @@
-package org.qortal.crosschain;
-
-import static org.ciyam.at.OpCode.calcOffset;
-
-import java.nio.ByteBuffer;
-import java.util.Arrays;
-import java.util.List;
-import java.util.function.Function;
-
-import org.bitcoinj.core.Address;
-import org.bitcoinj.core.Coin;
-import org.bitcoinj.core.ECKey;
-import org.bitcoinj.core.LegacyAddress;
-import org.bitcoinj.core.NetworkParameters;
-import org.bitcoinj.core.Transaction;
-import org.bitcoinj.core.Transaction.SigHash;
-import org.bitcoinj.core.TransactionInput;
-import org.bitcoinj.core.TransactionOutput;
-import org.bitcoinj.crypto.TransactionSignature;
-import org.bitcoinj.script.Script;
-import org.bitcoinj.script.ScriptBuilder;
-import org.bitcoinj.script.ScriptChunk;
-import org.bitcoinj.script.ScriptOpCodes;
-import org.ciyam.at.API;
-import org.ciyam.at.CompilationException;
-import org.ciyam.at.FunctionCode;
-import org.ciyam.at.MachineState;
-import org.ciyam.at.OpCode;
-import org.ciyam.at.Timestamp;
-import org.qortal.account.Account;
-import org.qortal.asset.Asset;
-import org.qortal.at.QortalAtLoggerFactory;
-import org.qortal.block.BlockChain;
-import org.qortal.block.BlockChain.CiyamAtSettings;
-import org.qortal.crypto.Crypto;
-import org.qortal.data.at.ATData;
-import org.qortal.data.at.ATStateData;
-import org.qortal.data.block.BlockData;
-import org.qortal.data.crosschain.CrossChainTradeData;
-import org.qortal.repository.DataException;
-import org.qortal.repository.Repository;
-import org.qortal.utils.Base58;
-import org.qortal.utils.BitTwiddling;
-
-import com.google.common.hash.HashCode;
-import com.google.common.primitives.Bytes;
-
-/*
- * Bob generates Bitcoin private key
- * 		private key required to sign P2SH redeem tx
- * 		private key can be used to create 'secret' (e.g. double-SHA256)
- * 		encrypted private key could be stored in Qortal AT for access by Bob from any node
- * Bob creates Qortal AT
- * Alice finds Qortal AT and wants to trade
- * 		Alice generates Bitcoin private key
- * 		Alice will need to send Bob her Qortal address and Bitcoin refund address
- * Bob sends Alice's Qortal address to Qortal AT
- * Qortal AT sends initial QORT payment to Alice (so she has QORT to send message to AT and claim funds)
- * Alice receives funds and checks Qortal AT to confirm it's locked to her
- * Alice creates/funds Bitcoin P2SH
- * 		Alice requires: Bob's redeem Bitcoin address, Alice's refund Bitcoin address, derived locktime
- * Bob checks P2SH is funded
- * 		Bob requires: Bob's redeem Bitcoin address, Alice's refund Bitcoin address, derived locktime
- * Bob uses secret to redeem P2SH
- * 		Qortal core/UI will need to create, and sign, this transaction
- * Alice scans P2SH redeem tx and uses secret to redeem Qortal AT
- */
-
-public class BTCACCT {
-
-	public static final int SECRET_LENGTH = 32;
-	public static final int MIN_LOCKTIME = 1500000000;
-	public static final byte[] CODE_BYTES_HASH = HashCode.fromString("edcdb1feb36e079c5f956faff2f24219b12e5fbaaa05654335e615e33218282f").asBytes(); // SHA256 of AT code bytes
-
-	/*
-	 * OP_TUCK (to copy public key to before signature)
-	 * OP_CHECKSIGVERIFY (sig & pubkey must verify or script fails)
-	 * OP_HASH160 (convert public key to PKH)
-	 * OP_DUP (duplicate PKH)
-	 * <push 20 bytes> <refund PKH> OP_EQUAL (does PKH match refund PKH?)
-	 * OP_IF
-	 * 	OP_DROP (no need for duplicate PKH)
-	 * 	<push 4 bytes> <locktime>
-	 * 	OP_CHECKLOCKTIMEVERIFY (if this passes, leftover stack is <locktime> so script passes)
-	 * OP_ELSE
-	 * 	<push 20 bytes> <redeem PKH> OP_EQUALVERIFY (duplicate PKH must match redeem PKH or script fails)
-	 * 	OP_HASH160 (hash secret)
-	 * 	<push 20 bytes> <hash of secret> OP_EQUAL (do hashes of secrets match? if true, script passes else script fails)
-	 * OP_ENDIF
-	 */
-
-	private static final byte[] redeemScript1 = HashCode.fromString("7dada97614").asBytes(); // OP_TUCK OP_CHECKSIGVERIFY OP_HASH160 OP_DUP push(0x14 bytes)
-	private static final byte[] redeemScript2 = HashCode.fromString("87637504").asBytes(); // OP_EQUAL OP_IF OP_DROP push(0x4 bytes)
-	private static final byte[] redeemScript3 = HashCode.fromString("b16714").asBytes(); // OP_CHECKLOCKTIMEVERIFY OP_ELSE push(0x14 bytes)
-	private static final byte[] redeemScript4 = HashCode.fromString("88a914").asBytes(); // OP_EQUALVERIFY OP_HASH160 push(0x14 bytes)
-	private static final byte[] redeemScript5 = HashCode.fromString("8768").asBytes(); // OP_EQUAL OP_ENDIF
-
-	/**
-	 * Returns Bitcoin redeemScript used for cross-chain trading.
-	 * <p>
-	 * See comments in {@link BTCACCT} for more details.
-	 * 
-	 * @param refunderPubKeyHash 20-byte HASH160 of P2SH funder's public key, for refunding purposes
-	 * @param lockTime seconds-since-epoch threshold, after which P2SH funder can claim refund
-	 * @param redeemerPubKeyHash 20-byte HASH160 of P2SH redeemer's public key
-	 * @param secretHash 20-byte HASH160 of secret, used by P2SH redeemer to claim funds
-	 * @return
-	 */
-	public static byte[] buildScript(byte[] refunderPubKeyHash, int lockTime, byte[] redeemerPubKeyHash, byte[] secretHash) {
-		return Bytes.concat(redeemScript1, refunderPubKeyHash, redeemScript2, BitTwiddling.toLEByteArray((int) (lockTime & 0xffffffffL)),
-				redeemScript3, redeemerPubKeyHash, redeemScript4, secretHash, redeemScript5);
-	}
-
-	/**
-	 * Builds a custom transaction to spend P2SH.
-	 * 
-	 * @param amount output amount, should be total of input amounts, less miner fees
-	 * @param spendKey key for signing transaction, and also where funds are 'sent' (output)
-	 * @param fundingOutput output from transaction that funded P2SH address
-	 * @param redeemScriptBytes the redeemScript itself, in byte[] form
-	 * @param lockTime (optional) transaction nLockTime, used in refund scenario
-	 * @param scriptSigBuilder function for building scriptSig using transaction input signature
-	 * @return Signed Bitcoin transaction for spending P2SH
-	 */
-	public static Transaction buildP2shTransaction(Coin amount, ECKey spendKey, List<TransactionOutput> fundingOutputs, byte[] redeemScriptBytes, Long lockTime, Function<byte[], Script> scriptSigBuilder) {
-		NetworkParameters params = BTC.getInstance().getNetworkParameters();
-
-		Transaction transaction = new Transaction(params);
-		transaction.setVersion(2);
-
-		// Output is back to P2SH funder
-		transaction.addOutput(amount, ScriptBuilder.createP2PKHOutputScript(spendKey.getPubKeyHash()));
-
-		for (int inputIndex = 0; inputIndex < fundingOutputs.size(); ++inputIndex) {
-			TransactionOutput fundingOutput = fundingOutputs.get(inputIndex);
-
-			// Input (without scriptSig prior to signing)
-			TransactionInput input = new TransactionInput(params, null, redeemScriptBytes, fundingOutput.getOutPointFor());
-			if (lockTime != null)
-				input.setSequenceNumber(BTC.LOCKTIME_NO_RBF_SEQUENCE); // Use max-value, so no lockTime and no RBF
-			else
-				input.setSequenceNumber(BTC.NO_LOCKTIME_NO_RBF_SEQUENCE); // Use max-value - 1, so lockTime can be used but not RBF
-			transaction.addInput(input);
-		}
-
-		// Set locktime after inputs added but before input signatures are generated
-		if (lockTime != null)
-			transaction.setLockTime(lockTime);
-
-		for (int inputIndex = 0; inputIndex < fundingOutputs.size(); ++inputIndex) {
-			// Generate transaction signature for input
-			final boolean anyoneCanPay = false;
-			TransactionSignature txSig = transaction.calculateSignature(inputIndex, spendKey, redeemScriptBytes, SigHash.ALL, anyoneCanPay);
-
-			// Calculate transaction signature
-			byte[] txSigBytes = txSig.encodeToBitcoin();
-
-			// Build scriptSig using lambda and tx signature
-			Script scriptSig = scriptSigBuilder.apply(txSigBytes);
-
-			// Set input scriptSig
-			transaction.getInput(inputIndex).setScriptSig(scriptSig);
-		}
-
-		return transaction;
-	}
-
-	/**
-	 * Returns signed Bitcoin transaction claiming refund from P2SH address.
-	 * 
-	 * @param refundAmount refund amount, should be total of input amounts, less miner fees
-	 * @param refundKey key for signing transaction, and also where refund is 'sent' (output)
-	 * @param fundingOutput output from transaction that funded P2SH address
-	 * @param redeemScriptBytes the redeemScript itself, in byte[] form
-	 * @param lockTime transaction nLockTime - must be at least locktime used in redeemScript
-	 * @return Signed Bitcoin transaction for refunding P2SH
-	 */
-	public static Transaction buildRefundTransaction(Coin refundAmount, ECKey refundKey, List<TransactionOutput> fundingOutputs, byte[] redeemScriptBytes, long lockTime) {
-		Function<byte[], Script> refundSigScriptBuilder = (txSigBytes) -> {
-			// Build scriptSig with...
-			ScriptBuilder scriptBuilder = new ScriptBuilder();
-
-			// transaction signature
-			scriptBuilder.addChunk(new ScriptChunk(txSigBytes.length, txSigBytes));
-
-			// redeem public key
-			byte[] refundPubKey = refundKey.getPubKey();
-			scriptBuilder.addChunk(new ScriptChunk(refundPubKey.length, refundPubKey));
-
-			// redeem script
-			scriptBuilder.addChunk(new ScriptChunk(ScriptOpCodes.OP_PUSHDATA1, redeemScriptBytes));
-
-			return scriptBuilder.build();
-		};
-
-		return buildP2shTransaction(refundAmount, refundKey, fundingOutputs, redeemScriptBytes, lockTime, refundSigScriptBuilder);
-	}
-
-	/**
-	 * Returns signed Bitcoin transaction redeeming funds from P2SH address.
-	 * 
-	 * @param redeemAmount redeem amount, should be total of input amounts, less miner fees
-	 * @param redeemKey key for signing transaction, and also where funds are 'sent' (output)
-	 * @param fundingOutput output from transaction that funded P2SH address
-	 * @param redeemScriptBytes the redeemScript itself, in byte[] form
-	 * @param secret actual 32-byte secret used when building redeemScript
-	 * @return Signed Bitcoin transaction for redeeming P2SH
-	 */
-	public static Transaction buildRedeemTransaction(Coin redeemAmount, ECKey redeemKey, List<TransactionOutput> fundingOutputs, byte[] redeemScriptBytes, byte[] secret) {
-		Function<byte[], Script> redeemSigScriptBuilder = (txSigBytes) -> {
-			// Build scriptSig with...
-			ScriptBuilder scriptBuilder = new ScriptBuilder();
-
-			// secret
-			scriptBuilder.addChunk(new ScriptChunk(secret.length, secret));
-
-			// transaction signature
-			scriptBuilder.addChunk(new ScriptChunk(txSigBytes.length, txSigBytes));
-
-			// redeem public key
-			byte[] redeemPubKey = redeemKey.getPubKey();
-			scriptBuilder.addChunk(new ScriptChunk(redeemPubKey.length, redeemPubKey));
-
-			// redeem script
-			scriptBuilder.addChunk(new ScriptChunk(ScriptOpCodes.OP_PUSHDATA1, redeemScriptBytes));
-
-			return scriptBuilder.build();
-		};
-
-		return buildP2shTransaction(redeemAmount, redeemKey, fundingOutputs, redeemScriptBytes, null, redeemSigScriptBuilder);
-	}
-
-	/**
-	 * Returns Qortal AT creation bytes for cross-chain trading AT.
-	 * <p>
-	 * <tt>tradeTimeout</tt> (minutes) is the time window for the recipient to send the
-	 * 32-byte secret to the AT, before the AT automatically refunds the AT's creator.
-	 * 
-	 * @param qortalCreator Qortal address for AT creator, also used for refunds
-	 * @param secretHash 20-byte HASH160 of 32-byte secret
-	 * @param tradeTimeout how many minutes, from start of 'trade mode' until AT auto-refunds AT creator
-	 * @param initialPayout how much QORT to pay trade partner upon switch to 'trade mode'
-	 * @param redeemPayout how much QORT to pay trade partner if they send correct 32-byte secret to AT
-	 * @param bitcoinAmount how much BTC the AT creator is expecting to trade
-	 * @return
-	 */
-	public static byte[] buildQortalAT(String qortalCreator, byte[] secretHash, int tradeTimeout, long initialPayout, long redeemPayout, long bitcoinAmount) {
-		// Labels for data segment addresses
-		int addrCounter = 0;
-
-		// Constants (with corresponding dataByteBuffer.put*() calls below)
-
-		final int addrQortalCreator1 = addrCounter++;
-		final int addrQortalCreator2 = addrCounter++;
-		final int addrQortalCreator3 = addrCounter++;
-		final int addrQortalCreator4 = addrCounter++;
-
-		final int addrSecretHash = addrCounter;
-		addrCounter += 4;
-
-		final int addrTradeTimeout = addrCounter++;
-		final int addrInitialPayoutAmount = addrCounter++;
-		final int addrRedeemPayoutAmount = addrCounter++;
-		final int addrBitcoinAmount = addrCounter++;
-
-		final int addrMessageTxType = addrCounter++;
-
-		final int addrSecretHashPointer = addrCounter++;
-		final int addrQortalRecipientPointer = addrCounter++;
-		final int addrMessageSenderPointer = addrCounter++;
-
-		final int addrMessageDataPointer = addrCounter++;
-		final int addrMessageDataLength = addrCounter++;
-
-		final int addrEndOfConstants = addrCounter;
-
-		// Variables
-
-		final int addrQortalRecipient1 = addrCounter++;
-		final int addrQortalRecipient2 = addrCounter++;
-		final int addrQortalRecipient3 = addrCounter++;
-		final int addrQortalRecipient4 = addrCounter++;
-
-		final int addrTradeRefundTimestamp = addrCounter++;
-		final int addrLastTxTimestamp = addrCounter++;
-		final int addrBlockTimestamp = addrCounter++;
-		final int addrTxType = addrCounter++;
-		final int addrResult = addrCounter++;
-
-		final int addrMessageSender1 = addrCounter++;
-		final int addrMessageSender2 = addrCounter++;
-		final int addrMessageSender3 = addrCounter++;
-		final int addrMessageSender4 = addrCounter++;
-
-		final int addrMessageData = addrCounter;
-		addrCounter += 4;
-
-		// Data segment
-		ByteBuffer dataByteBuffer = ByteBuffer.allocate(addrCounter * MachineState.VALUE_SIZE);
-
-		// AT creator's Qortal address, decoded from Base58
-		assert dataByteBuffer.position() == addrQortalCreator1 * MachineState.VALUE_SIZE : "addrQortalCreator1 incorrect";
-		byte[] qortalCreatorBytes = Base58.decode(qortalCreator);
-		dataByteBuffer.put(Bytes.ensureCapacity(qortalCreatorBytes, 32, 0));
-
-		// Hash of secret
-		assert dataByteBuffer.position() == addrSecretHash * MachineState.VALUE_SIZE : "addrSecretHash incorrect";
-		dataByteBuffer.put(Bytes.ensureCapacity(secretHash, 32, 0));
-
-		// Trade timeout in minutes
-		assert dataByteBuffer.position() == addrTradeTimeout * MachineState.VALUE_SIZE : "addrTradeTimeout incorrect";
-		dataByteBuffer.putLong(tradeTimeout);
-
-		// Initial payout amount
-		assert dataByteBuffer.position() == addrInitialPayoutAmount * MachineState.VALUE_SIZE : "addrInitialPayoutAmount incorrect";
-		dataByteBuffer.putLong(initialPayout);
-
-		// Redeem payout amount
-		assert dataByteBuffer.position() == addrRedeemPayoutAmount * MachineState.VALUE_SIZE : "addrRedeemPayoutAmount incorrect";
-		dataByteBuffer.putLong(redeemPayout);
-
-		// Expected Bitcoin amount
-		assert dataByteBuffer.position() == addrBitcoinAmount * MachineState.VALUE_SIZE : "addrBitcoinAmount incorrect";
-		dataByteBuffer.putLong(bitcoinAmount);
-
-		// We're only interested in MESSAGE transactions
-		assert dataByteBuffer.position() == addrMessageTxType * MachineState.VALUE_SIZE : "addrMessageTxType incorrect";
-		dataByteBuffer.putLong(API.ATTransactionType.MESSAGE.value);
-
-		// Index into data segment of hash, used by GET_B_IND
-		assert dataByteBuffer.position() == addrSecretHashPointer * MachineState.VALUE_SIZE : "addrSecretHashPointer incorrect";
-		dataByteBuffer.putLong(addrSecretHash);
-
-		// Index into data segment of recipient address, used by SET_B_IND
-		assert dataByteBuffer.position() == addrQortalRecipientPointer * MachineState.VALUE_SIZE : "addrQortalRecipientPointer incorrect";
-		dataByteBuffer.putLong(addrQortalRecipient1);
-
-		// Index into data segment of (temporary) transaction's sender's address, used by GET_B_IND
-		assert dataByteBuffer.position() == addrMessageSenderPointer * MachineState.VALUE_SIZE : "addrMessageSenderPointer incorrect";
-		dataByteBuffer.putLong(addrMessageSender1);
-
-		// Source location and length for hashing any passed secret
-		assert dataByteBuffer.position() == addrMessageDataPointer * MachineState.VALUE_SIZE : "addrMessageDataPointer incorrect";
-		dataByteBuffer.putLong(addrMessageData);
-		assert dataByteBuffer.position() == addrMessageDataLength * MachineState.VALUE_SIZE : "addrMessageDataLength incorrect";
-		dataByteBuffer.putLong(32L);
-
-		assert dataByteBuffer.position() == addrEndOfConstants * MachineState.VALUE_SIZE : "dataByteBuffer position not at end of constants";
-
-		// Code labels
-		Integer labelRefund = null;
-
-		Integer labelOfferTxLoop = null;
-		Integer labelCheckOfferTx = null;
-
-		Integer labelTradeMode = null;
-		Integer labelTradeTxLoop = null;
-		Integer labelCheckTradeTx = null;
-
-		ByteBuffer codeByteBuffer = ByteBuffer.allocate(512);
-
-		// Two-pass version
-		for (int pass = 0; pass < 2; ++pass) {
-			codeByteBuffer.clear();
-
-			try {
-				/* Initialization */
-
-				// Use AT creation 'timestamp' as starting point for finding transactions sent to AT
-				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_CREATION_TIMESTAMP, addrLastTxTimestamp));
-
-				// Set restart position to after this opcode
-				codeByteBuffer.put(OpCode.SET_PCS.compile());
-
-				/* Loop, waiting for message from AT owner containing trade partner details, or AT owner's address to cancel offer */
-
-				/* Transaction processing loop */
-				labelOfferTxLoop = codeByteBuffer.position();
-
-				// Find next transaction to this AT since the last one (if any)
-				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PUT_TX_AFTER_TIMESTAMP_INTO_A, addrLastTxTimestamp));
-				// If no transaction found, A will be zero. If A is zero, set addrComparator to 1, otherwise 0.
-				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.CHECK_A_IS_ZERO, addrResult));
-				// If addrResult is zero (i.e. A is non-zero, transaction was found) then go check transaction
-				codeByteBuffer.put(OpCode.BZR_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelCheckOfferTx)));
-				// Stop and wait for next block
-				codeByteBuffer.put(OpCode.STP_IMD.compile());
-
-				/* Check transaction */
-				labelCheckOfferTx = codeByteBuffer.position();
-
-				// Update our 'last found transaction's timestamp' using 'timestamp' from transaction
-				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TIMESTAMP_FROM_TX_IN_A, addrLastTxTimestamp));
-				// Extract transaction type (message/payment) from transaction and save type in addrTxType
-				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TYPE_FROM_TX_IN_A, addrTxType));
-				// If transaction type is not MESSAGE type then go look for another transaction
-				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrTxType, addrMessageTxType, calcOffset(codeByteBuffer, labelOfferTxLoop)));
-
-				/* Check transaction's sender */
-
-				// Extract sender address from transaction into B register
-				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_ADDRESS_FROM_TX_IN_A_INTO_B));
-				// Save B register into data segment starting at addrMessageSender1 (as pointed to by addrMessageSenderPointer)
-				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageSenderPointer));
-				// Compare each part of transaction's sender's address with expected address. If they don't match, look for another transaction.
-				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrQortalCreator1, calcOffset(codeByteBuffer, labelOfferTxLoop)));
-				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrQortalCreator2, calcOffset(codeByteBuffer, labelOfferTxLoop)));
-				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrQortalCreator3, calcOffset(codeByteBuffer, labelOfferTxLoop)));
-				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrQortalCreator4, calcOffset(codeByteBuffer, labelOfferTxLoop)));
-
-				/* Extract trade partner info from message */
-
-				// Extract message from transaction into B register
-				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_MESSAGE_FROM_TX_IN_A_INTO_B));
-				// Save B register into data segment starting at addrQortalRecipient1 (as pointed to by addrQortalRecipientPointer)
-				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrQortalRecipientPointer));
-				// Compare each of recipient address with creator's address (for offer-cancel scenario). If they don't match, assume recipient is trade partner.
-				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrQortalRecipient1, addrQortalCreator1, calcOffset(codeByteBuffer, labelTradeMode)));
-				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrQortalRecipient2, addrQortalCreator2, calcOffset(codeByteBuffer, labelTradeMode)));
-				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrQortalRecipient3, addrQortalCreator3, calcOffset(codeByteBuffer, labelTradeMode)));
-				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrQortalRecipient4, addrQortalCreator4, calcOffset(codeByteBuffer, labelTradeMode)));
-				// Recipient address is AT creator's address, so cancel offer and finish.
-				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelRefund == null ? 0 : labelRefund));
-
-				/* Switch to 'trade mode' */
-				labelTradeMode = codeByteBuffer.position();
-
-				// Send initial payment to recipient so they have enough funds to message AT if all goes well
-				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PAY_TO_ADDRESS_IN_B, addrInitialPayoutAmount));
-
-				// Calculate trade timeout refund 'timestamp' by adding addrTradeTimeout minutes to above message's 'timestamp', then save into addrTradeRefundTimestamp
-				codeByteBuffer.put(OpCode.EXT_FUN_RET_DAT_2.compile(FunctionCode.ADD_MINUTES_TO_TIMESTAMP, addrTradeRefundTimestamp, addrLastTxTimestamp, addrTradeTimeout));
-
-				// Set restart position to after this opcode
-				codeByteBuffer.put(OpCode.SET_PCS.compile());
-
-				/* Loop, waiting for trade timeout or message from Qortal trade recipient containing secret */
-
-				// Fetch current block 'timestamp'
-				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_BLOCK_TIMESTAMP, addrBlockTimestamp));
-				// If we're not past refund 'timestamp' then look for next transaction
-				codeByteBuffer.put(OpCode.BLT_DAT.compile(addrBlockTimestamp, addrTradeRefundTimestamp, calcOffset(codeByteBuffer, labelTradeTxLoop)));
-				// We're past refund 'timestamp' so go refund everything back to AT creator
-				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelRefund == null ? 0 : labelRefund));
-
-				/* Transaction processing loop */
-				labelTradeTxLoop = codeByteBuffer.position();
-
-				// Find next transaction to this AT since the last one (if any)
-				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PUT_TX_AFTER_TIMESTAMP_INTO_A, addrLastTxTimestamp));
-				// If no transaction found, A will be zero. If A is zero, set addrComparator to 1, otherwise 0.
-				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.CHECK_A_IS_ZERO, addrResult));
-				// If addrResult is zero (i.e. A is non-zero, transaction was found) then go check transaction
-				codeByteBuffer.put(OpCode.BZR_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelCheckTradeTx)));
-				// Stop and wait for next block
-				codeByteBuffer.put(OpCode.STP_IMD.compile());
-
-				/* Check transaction */
-				labelCheckTradeTx = codeByteBuffer.position();
-
-				// Update our 'last found transaction's timestamp' using 'timestamp' from transaction
-				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TIMESTAMP_FROM_TX_IN_A, addrLastTxTimestamp));
-				// Extract transaction type (message/payment) from transaction and save type in addrTxType
-				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TYPE_FROM_TX_IN_A, addrTxType));
-				// If transaction type is not MESSAGE type then go look for another transaction
-				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrTxType, addrMessageTxType, calcOffset(codeByteBuffer, labelTradeTxLoop)));
-
-				/* Check transaction's sender */
-
-				// Extract sender address from transaction into B register
-				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_ADDRESS_FROM_TX_IN_A_INTO_B));
-				// Save B register into data segment starting at addrMessageSender1 (as pointed to by addrMessageSenderPointer)
-				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageSenderPointer));
-				// Compare each part of transaction's sender's address with expected address. If they don't match, look for another transaction.
-				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrQortalRecipient1, calcOffset(codeByteBuffer, labelTradeTxLoop)));
-				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrQortalRecipient2, calcOffset(codeByteBuffer, labelTradeTxLoop)));
-				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrQortalRecipient3, calcOffset(codeByteBuffer, labelTradeTxLoop)));
-				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrQortalRecipient4, calcOffset(codeByteBuffer, labelTradeTxLoop)));
-
-				/* Check 'secret' in transaction's message */
-
-				// Extract message from transaction into B register
-				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_MESSAGE_FROM_TX_IN_A_INTO_B));
-				// Save B register into data segment starting at addrMessageData (as pointed to by addrMessageDataPointer)
-				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageDataPointer));
-				// Load B register with expected hash result (as pointed to by addrSecretHashPointer)
-				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.SET_B_IND, addrSecretHashPointer));
-				// Perform HASH160 using source data at addrMessageData. (Location and length specified via addrMessageDataPointer and addrMessageDataLength).
-				// Save the equality result (1 if they match, 0 otherwise) into addrResult.
-				codeByteBuffer.put(OpCode.EXT_FUN_RET_DAT_2.compile(FunctionCode.CHECK_HASH160_WITH_B, addrResult, addrMessageDataPointer, addrMessageDataLength));
-				// If hashes don't match, addrResult will be zero so go find another transaction
-				codeByteBuffer.put(OpCode.BZR_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelTradeTxLoop)));
-
-				/* Success! Pay arranged amount to intended recipient */
-
-				// Load B register with intended recipient address (as pointed to by addrQortalRecipientPointer)
-				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.SET_B_IND, addrQortalRecipientPointer));
-				// Pay AT's balance to recipient
-				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PAY_TO_ADDRESS_IN_B, addrRedeemPayoutAmount));
-				// Fall-through to refunding any remaining balance back to AT creator
-
-				/* Refund balance back to AT creator */
-				labelRefund = codeByteBuffer.position();
-
-				// Load B register with AT creator's address.
-				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_CREATOR_INTO_B));
-				// Pay AT's balance back to AT's creator.
-				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PAY_ALL_TO_ADDRESS_IN_B));
-				// We're finished forever
-				codeByteBuffer.put(OpCode.FIN_IMD.compile());
-			} catch (CompilationException e) {
-				throw new IllegalStateException("Unable to compile BTC-QORT ACCT?", e);
-			}
-		}
-
-		codeByteBuffer.flip();
-
-		byte[] codeBytes = new byte[codeByteBuffer.limit()];
-		codeByteBuffer.get(codeBytes);
-
-		assert Arrays.equals(Crypto.digest(codeBytes), BTCACCT.CODE_BYTES_HASH)
-			: String.format("BTCACCT.CODE_BYTES_HASH mismatch: expected %s, actual %s", HashCode.fromBytes(CODE_BYTES_HASH), HashCode.fromBytes(Crypto.digest(codeBytes)));
-
-		final short ciyamAtVersion = 2;
-		final short numCallStackPages = 0;
-		final short numUserStackPages = 0;
-		final long minActivationAmount = 0L;
-
-		return MachineState.toCreationBytes(ciyamAtVersion, codeBytes, dataByteBuffer.array(), numCallStackPages, numUserStackPages, minActivationAmount);
-	}
-
-	/**
-	 * Returns CrossChainTradeData with useful info extracted from AT.
-	 * 
-	 * @param repository
-	 * @param atAddress
-	 * @throws DataException
-	 */
-	public static CrossChainTradeData populateTradeData(Repository repository, ATData atData) throws DataException {
-		String atAddress = atData.getATAddress();
-
-		ATStateData atStateData = repository.getATRepository().getLatestATState(atAddress);
-		byte[] stateData = atStateData.getStateData();
-
-		QortalAtLoggerFactory loggerFactory = QortalAtLoggerFactory.getInstance();
-		byte[] dataBytes = MachineState.extractDataBytes(loggerFactory, stateData);
-
-		CrossChainTradeData tradeData = new CrossChainTradeData();
-		tradeData.qortalAtAddress = atAddress;
-		tradeData.qortalCreator = Crypto.toAddress(atData.getCreatorPublicKey());
-		tradeData.creationTimestamp = atData.getCreation();
-
-		Account atAccount = new Account(repository, atAddress);
-		tradeData.qortBalance = atAccount.getConfirmedBalance(Asset.QORT);
-
-		ByteBuffer dataByteBuffer = ByteBuffer.wrap(dataBytes);
-		byte[] addressBytes = new byte[32];
-
-		// Skip AT creator address
-		dataByteBuffer.position(dataByteBuffer.position() + 32);
-
-		// Hash of secret
-		tradeData.secretHash = new byte[20];
-		dataByteBuffer.get(tradeData.secretHash);
-		dataByteBuffer.position(dataByteBuffer.position() + 32 - 20); // skip to 32 bytes
-
-		// Trade timeout
-		tradeData.tradeRefundTimeout = dataByteBuffer.getLong();
-
-		// Initial payout
-		tradeData.initialPayout = dataByteBuffer.getLong();
-
-		// Redeem payout
-		tradeData.redeemPayout = dataByteBuffer.getLong();
-
-		// Expected BTC amount
-		tradeData.expectedBitcoin = dataByteBuffer.getLong();
-
-		// Skip MESSAGE transaction type
-		dataByteBuffer.position(dataByteBuffer.position() + 8);
-
-		// Skip pointer to secretHash
-		dataByteBuffer.position(dataByteBuffer.position() + 8);
-
-		// Skip pointer to Qortal recipient
-		dataByteBuffer.position(dataByteBuffer.position() + 8);
-
-		// Skip pointer to message sender
-		dataByteBuffer.position(dataByteBuffer.position() + 8);
-
-		// Skip pointer to message data
-		dataByteBuffer.position(dataByteBuffer.position() + 8);
-
-		// Skip message data length
-		dataByteBuffer.position(dataByteBuffer.position() + 8);
-
-		// Qortal recipient (if any)
-		dataByteBuffer.get(addressBytes);
-
-		// Trade offer timeout (AT 'timestamp' converted to Qortal block height)
-		long tradeRefundTimestamp = dataByteBuffer.getLong();
-
-		if (tradeRefundTimestamp != 0) {
-			tradeData.mode = CrossChainTradeData.Mode.TRADE;
-			tradeData.tradeRefundHeight = new Timestamp(tradeRefundTimestamp).blockHeight;
-
-			if (addressBytes[0] != 0)
-				tradeData.qortalRecipient = Base58.encode(Arrays.copyOf(addressBytes, Account.ADDRESS_LENGTH));
-
-			// We'll suggest half of trade timeout
-			CiyamAtSettings ciyamAtSettings = BlockChain.getInstance().getCiyamAtSettings();
-
-			int tradeModeSwitchHeight = (int) (tradeData.tradeRefundHeight - tradeData.tradeRefundTimeout / ciyamAtSettings.minutesPerBlock);
-
-			BlockData blockData = repository.getBlockRepository().fromHeight(tradeModeSwitchHeight);
-			if (blockData != null) {
-				tradeData.tradeModeTimestamp = blockData.getTimestamp(); // NOTE: milliseconds from epoch
-				tradeData.lockTime = (int) (tradeData.tradeModeTimestamp / 1000L + tradeData.tradeRefundTimeout / 2 * 60);
-			}
-		} else {
-			tradeData.mode = CrossChainTradeData.Mode.OFFER;
-		}
-
-		return tradeData;
-	}
-
-	public static byte[] findP2shSecret(String p2shAddress, List<byte[]> rawTransactions) {
-		NetworkParameters params = BTC.getInstance().getNetworkParameters();
-
-		for (byte[] rawTransaction : rawTransactions) {
-			Transaction transaction = new Transaction(params, rawTransaction);
-
-			// Cycle through inputs, looking for one that spends our P2SH
-			for (TransactionInput input : transaction.getInputs()) {
-				Script scriptSig = input.getScriptSig();
-				List<ScriptChunk> scriptChunks = scriptSig.getChunks();
-
-				// Expected number of script chunks for redeem. Refund might not have the same number.
-				int expectedChunkCount = 1 /*secret*/ + 1 /*sig*/ + 1 /*pubkey*/ + 1 /*redeemScript*/;
-				if (scriptChunks.size() != expectedChunkCount)
-					continue;
-
-				// We're expecting last chunk to contain the actual redeemScript
-				ScriptChunk lastChunk = scriptChunks.get(scriptChunks.size() - 1);
-				byte[] redeemScriptBytes = lastChunk.data;
-
-				// If non-push scripts, redeemScript will be null
-				if (redeemScriptBytes == null)
-					continue;
-
-				byte[] redeemScriptHash = Crypto.hash160(redeemScriptBytes);
-				Address inputAddress = LegacyAddress.fromScriptHash(params, redeemScriptHash);
-
-				if (!inputAddress.toString().equals(p2shAddress))
-					// Input isn't spending our P2SH
-					continue;
-
-				byte[] secret = scriptChunks.get(0).data;
-				if (secret.length != BTCACCT.SECRET_LENGTH)
-					continue;
-
-				return secret;
-			}
-		}
-
-		return null;
-	}
-
-}

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

@@ -0,0 +1,190 @@
+package org.qortal.crosschain;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.EnumMap;
+import java.util.Map;
+
+import org.bitcoinj.core.Context;
+import org.bitcoinj.core.NetworkParameters;
+import org.bitcoinj.params.MainNetParams;
+import org.bitcoinj.params.RegTestParams;
+import org.bitcoinj.params.TestNet3Params;
+import org.qortal.crosschain.ElectrumX.Server;
+import org.qortal.crosschain.ElectrumX.Server.ConnectionType;
+import org.qortal.settings.Settings;
+
+public class Bitcoin extends Bitcoiny {
+
+	public static final String CURRENCY_CODE = "BTC";
+
+	// Temporary values until a dynamic fee system is written.
+	private static final long OLD_FEE_AMOUNT = 4_000L; // Not 5000 so that existing P2SH-B can output 1000, avoiding dust issue, leaving 4000 for fees.
+	private static final long NEW_FEE_TIMESTAMP = 1598280000000L; // milliseconds since epoch
+	private static final long NEW_FEE_AMOUNT = 10_000L;
+
+	private static final long NON_MAINNET_FEE = 1000L; // enough for TESTNET3 and should be OK for REGTEST
+
+	private static final Map<ElectrumX.Server.ConnectionType, Integer> DEFAULT_ELECTRUMX_PORTS = new EnumMap<>(ElectrumX.Server.ConnectionType.class);
+	static {
+		DEFAULT_ELECTRUMX_PORTS.put(ConnectionType.TCP, 50001);
+		DEFAULT_ELECTRUMX_PORTS.put(ConnectionType.SSL, 50002);
+	}
+
+	public enum BitcoinNet {
+		MAIN {
+			@Override
+			public NetworkParameters getParams() {
+				return MainNetParams.get();
+			}
+
+			@Override
+			public Collection<ElectrumX.Server> getServers() {
+				return Arrays.asList(
+						// Servers chosen on NO BASIS WHATSOEVER from various sources!
+						new Server("128.0.190.26", Server.ConnectionType.SSL, 50002),
+						new Server("hodlers.beer", Server.ConnectionType.SSL, 50002),
+						new Server("electrumx.erbium.eu", Server.ConnectionType.TCP, 50001),
+						new Server("electrumx.erbium.eu", Server.ConnectionType.SSL, 50002),
+						new Server("btc.lastingcoin.net", Server.ConnectionType.SSL, 50002),
+						new Server("electrum.bitaroo.net", Server.ConnectionType.SSL, 50002),
+						new Server("bitcoin.grey.pw", Server.ConnectionType.SSL, 50002),
+						new Server("2electrumx.hopto.me", Server.ConnectionType.SSL, 56022),
+						new Server("185.64.116.15", Server.ConnectionType.SSL, 50002),
+						new Server("kirsche.emzy.de", Server.ConnectionType.SSL, 50002),
+						new Server("alviss.coinjoined.com", Server.ConnectionType.SSL, 50002),
+						new Server("electrum.emzy.de", Server.ConnectionType.SSL, 50002),
+						new Server("electrum.emzy.de", Server.ConnectionType.TCP, 50001),
+						new Server("vmd71287.contaboserver.net", Server.ConnectionType.SSL, 50002),
+						new Server("btc.litepay.ch", Server.ConnectionType.SSL, 50002),
+						new Server("electrum.stippy.com", Server.ConnectionType.SSL, 50002),
+						new Server("xtrum.com", Server.ConnectionType.SSL, 50002),
+						new Server("electrum.acinq.co", Server.ConnectionType.SSL, 50002),
+						new Server("electrum2.taborsky.cz", Server.ConnectionType.SSL, 50002),
+						new Server("vmd63185.contaboserver.net", Server.ConnectionType.SSL, 50002),
+						new Server("electrum2.privateservers.network", Server.ConnectionType.SSL, 50002),
+						new Server("electrumx.alexridevski.net", Server.ConnectionType.SSL, 50002),
+						new Server("192.166.219.200", Server.ConnectionType.SSL, 50002),
+						new Server("2ex.digitaleveryware.com", Server.ConnectionType.SSL, 50002),
+						new Server("dxm.no-ip.biz", Server.ConnectionType.SSL, 50002),
+						new Server("caleb.vegas", Server.ConnectionType.SSL, 50002));
+			}
+
+			@Override
+			public String getGenesisHash() {
+				return "000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f";
+			}
+
+			@Override
+			public long getP2shFee(Long timestamp) {
+				// TODO: This will need to be replaced with something better in the near future!
+				if (timestamp != null && timestamp < NEW_FEE_TIMESTAMP)
+					return OLD_FEE_AMOUNT;
+
+				return NEW_FEE_AMOUNT;
+			}
+		},
+		TEST3 {
+			@Override
+			public NetworkParameters getParams() {
+				return TestNet3Params.get();
+			}
+
+			@Override
+			public Collection<ElectrumX.Server> getServers() {
+				return Arrays.asList(
+						new Server("tn.not.fyi", Server.ConnectionType.SSL, 55002),
+						new Server("electrumx-test.1209k.com", Server.ConnectionType.SSL, 50002),
+						new Server("testnet.qtornado.com", Server.ConnectionType.SSL, 51002),
+						new Server("testnet.aranguren.org", Server.ConnectionType.TCP, 51001),
+						new Server("testnet.aranguren.org", Server.ConnectionType.SSL, 51002),
+						new Server("testnet.hsmiths.com", Server.ConnectionType.SSL, 53012));
+			}
+
+			@Override
+			public String getGenesisHash() {
+				return "000000000933ea01ad0ee984209779baaec3ced90fa3f408719526f8d77f4943";
+			}
+
+			@Override
+			public long getP2shFee(Long timestamp) {
+				return NON_MAINNET_FEE;
+			}
+		},
+		REGTEST {
+			@Override
+			public NetworkParameters getParams() {
+				return RegTestParams.get();
+			}
+
+			@Override
+			public Collection<ElectrumX.Server> getServers() {
+				return Arrays.asList(
+						new Server("localhost", Server.ConnectionType.TCP, 50001),
+						new Server("localhost", Server.ConnectionType.SSL, 50002));
+			}
+
+			@Override
+			public String getGenesisHash() {
+				// This is unique to each regtest instance
+				return null;
+			}
+
+			@Override
+			public long getP2shFee(Long timestamp) {
+				return NON_MAINNET_FEE;
+			}
+		};
+
+		public abstract NetworkParameters getParams();
+		public abstract Collection<ElectrumX.Server> getServers();
+		public abstract String getGenesisHash();
+		public abstract long getP2shFee(Long timestamp) throws ForeignBlockchainException;
+	}
+
+	private static Bitcoin instance;
+
+	private final BitcoinNet bitcoinNet;
+
+	// Constructors and instance
+
+	private Bitcoin(BitcoinNet bitcoinNet, BitcoinyBlockchainProvider blockchain, Context bitcoinjContext, String currencyCode) {
+		super(blockchain, bitcoinjContext, currencyCode);
+		this.bitcoinNet = bitcoinNet;
+
+		LOGGER.info(() -> String.format("Starting Bitcoin support using %s", this.bitcoinNet.name()));
+	}
+
+	public static synchronized Bitcoin getInstance() {
+		if (instance == null) {
+			BitcoinNet bitcoinNet = Settings.getInstance().getBitcoinNet();
+
+			BitcoinyBlockchainProvider electrumX = new ElectrumX("Bitcoin-" + bitcoinNet.name(), bitcoinNet.getGenesisHash(), bitcoinNet.getServers(), DEFAULT_ELECTRUMX_PORTS);
+			Context bitcoinjContext = new Context(bitcoinNet.getParams());
+
+			instance = new Bitcoin(bitcoinNet, electrumX, bitcoinjContext, CURRENCY_CODE);
+		}
+
+		return instance;
+	}
+
+	// Getters & setters
+
+	public static synchronized void resetForTesting() {
+		instance = null;
+	}
+
+	// Actual useful methods for use by other classes
+
+	/**
+	 * Returns estimated BTC fee, in sats per 1000bytes, optionally for historic timestamp.
+	 * 
+	 * @param timestamp optional milliseconds since epoch, or null for 'now'
+	 * @return sats per 1000bytes, or throws ForeignBlockchainException if something went wrong
+	 */
+	@Override
+	public long getP2shFee(Long timestamp) throws ForeignBlockchainException {
+		return this.bitcoinNet.getP2shFee(timestamp);
+	}
+
+}

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

@@ -0,0 +1,921 @@
+package org.qortal.crosschain;
+
+import static org.ciyam.at.OpCode.calcOffset;
+
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.List;
+
+import org.ciyam.at.API;
+import org.ciyam.at.CompilationException;
+import org.ciyam.at.FunctionCode;
+import org.ciyam.at.MachineState;
+import org.ciyam.at.OpCode;
+import org.ciyam.at.Timestamp;
+import org.qortal.account.Account;
+import org.qortal.asset.Asset;
+import org.qortal.at.QortalFunctionCode;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.at.ATStateData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.utils.Base58;
+import org.qortal.utils.BitTwiddling;
+
+import com.google.common.hash.HashCode;
+import com.google.common.primitives.Bytes;
+
+/**
+ * Cross-chain trade AT
+ * 
+ * <p>
+ * <ul>
+ * <li>Bob generates Bitcoin & Qortal 'trade' keys, and secret-b
+ * 		<ul>
+ * 			<li>private key required to sign P2SH redeem tx</li>
+ * 			<li>private key could be used to create 'secret' (e.g. double-SHA256)</li>
+ * 			<li>encrypted private key could be stored in Qortal AT for access by Bob from any node</li>
+ * 		</ul>
+ * </li>
+ * <li>Bob deploys Qortal AT
+ * 		<ul>
+ * 		</ul>
+ * </li>
+ * <li>Alice finds Qortal AT and wants to trade
+ * 		<ul>
+ * 			<li>Alice generates Bitcoin & Qortal 'trade' keys</li>
+ * 			<li>Alice funds Bitcoin P2SH-A</li>
+ * 			<li>Alice sends 'offer' MESSAGE to Bob from her Qortal trade address, containing:
+ * 				<ul>
+ * 					<li>hash-of-secret-A</li>
+ * 					<li>her 'trade' Bitcoin PKH</li>
+ * 				</ul>
+ * 			</li>
+ * 		</ul>
+ * </li>
+ * <li>Bob receives "offer" MESSAGE
+ * 		<ul>
+ * 			<li>Checks Alice's P2SH-A</li>
+ * 			<li>Sends 'trade' MESSAGE to Qortal AT from his trade address, containing:
+ * 				<ul>
+ * 					<li>Alice's trade Qortal address</li>
+ * 					<li>Alice's trade Bitcoin PKH</li>
+ * 					<li>hash-of-secret-A</li>
+ * 				</ul>
+ * 			</li>
+ * 		</ul>
+ * </li>
+ * <li>Alice checks Qortal AT to confirm it's locked to her
+ * 		<ul>
+ * 			<li>Alice creates/funds Bitcoin P2SH-B</li>
+ * 		</ul>
+ * </li>
+ * <li>Bob checks P2SH-B is funded
+ * 		<ul>
+ * 			<li>Bob redeems P2SH-B using his Bitcoin trade key and secret-B</li>
+ * 		</ul>
+ * </li>
+ * <li>Alice scans P2SH-B redeem transaction to extract secret-B
+ * 		<ul>
+ * 			<li>Alice sends 'redeem' MESSAGE to Qortal AT from her trade address, containing:
+ * 				<ul>
+ * 					<li>secret-A</li>
+ * 					<li>secret-B</li>
+ * 					<li>Qortal receiving address of her chosing</li>
+ * 				</ul>
+ * 			</li>
+ * 			<li>AT's QORT funds are sent to Qortal receiving address</li>
+ * 		</ul>
+ * </li>
+ * <li>Bob checks AT, extracts secret-A
+ * 		<ul>
+ * 			<li>Bob redeems P2SH-A using his Bitcoin trade key and secret-A</li>
+ * 			<li>P2SH-A BTC funds end up at Bitcoin address determined by redeem transaction output(s)</li>
+ * 		</ul>
+ * </li>
+ * </ul>
+ */
+public class BitcoinACCTv1 implements ACCT {
+
+	public static final String NAME = BitcoinACCTv1.class.getSimpleName();
+	public static final byte[] CODE_BYTES_HASH = HashCode.fromString("f7f419522a9aaa3c671149878f8c1374dfc59d4fd86ca43ff2a4d913cfbc9e89").asBytes(); // SHA256 of AT code bytes
+
+	public static final int SECRET_LENGTH = 32;
+
+	/** <b>Value</b> offset into AT segment where 'mode' variable (long) is stored. (Multiply by MachineState.VALUE_SIZE for byte offset). */
+	private static final int MODE_VALUE_OFFSET = 68;
+	/** <b>Byte</b> offset into AT state data where 'mode' variable (long) is stored. */
+	public static final int MODE_BYTE_OFFSET = MachineState.HEADER_LENGTH + (MODE_VALUE_OFFSET * MachineState.VALUE_SIZE);
+
+	public static class OfferMessageData {
+		public byte[] partnerBitcoinPKH;
+		public byte[] hashOfSecretA;
+		public long lockTimeA;
+	}
+	public static final int OFFER_MESSAGE_LENGTH = 20 /*partnerBitcoinPKH*/ + 20 /*hashOfSecretA*/ + 8 /*lockTimeA*/;
+	public static final int TRADE_MESSAGE_LENGTH = 32 /*partner's Qortal trade address (padded from 25 to 32)*/
+			+ 24 /*partner's Bitcoin PKH (padded from 20 to 24)*/
+			+ 8 /*lockTimeB*/
+			+ 24 /*hash of secret-A (padded from 20 to 24)*/
+			+ 8 /*lockTimeA*/;
+	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;
+	}
+
+	@Override
+	public byte[] getCodeBytesHash() {
+		return CODE_BYTES_HASH;
+	}
+
+	@Override
+	public int getModeByteOffset() {
+		return MODE_BYTE_OFFSET;
+	}
+
+	@Override
+	public ForeignBlockchain getBlockchain() {
+		return Bitcoin.getInstance();
+	}
+
+	/**
+	 * Returns Qortal AT creation bytes for cross-chain trading AT.
+	 * <p>
+	 * <tt>tradeTimeout</tt> (minutes) is the time window for the trade partner to send the
+	 * 32-byte secret to the AT, before the AT automatically refunds the AT's creator.
+	 * 
+	 * @param creatorTradeAddress AT creator's trade Qortal address, also used for refunds
+	 * @param bitcoinPublicKeyHash 20-byte HASH160 of creator's trade Bitcoin public key
+	 * @param hashOfSecretB 20-byte HASH160 of 32-byte secret-B
+	 * @param qortAmount how much QORT to pay trade partner if they send correct 32-byte secrets to AT
+	 * @param bitcoinAmount how much BTC the AT creator is expecting to trade
+	 * @param tradeTimeout suggested timeout for entire trade
+	 */
+	public static byte[] buildQortalAT(String creatorTradeAddress, byte[] bitcoinPublicKeyHash, byte[] hashOfSecretB, long qortAmount, long bitcoinAmount, int tradeTimeout) {
+		// Labels for data segment addresses
+		int addrCounter = 0;
+
+		// Constants (with corresponding dataByteBuffer.put*() calls below)
+
+		final int addrCreatorTradeAddress1 = addrCounter++;
+		final int addrCreatorTradeAddress2 = addrCounter++;
+		final int addrCreatorTradeAddress3 = addrCounter++;
+		final int addrCreatorTradeAddress4 = addrCounter++;
+
+		final int addrBitcoinPublicKeyHash = addrCounter;
+		addrCounter += 4;
+
+		final int addrHashOfSecretB = addrCounter;
+		addrCounter += 4;
+
+		final int addrQortAmount = addrCounter++;
+		final int addrBitcoinAmount = addrCounter++;
+		final int addrTradeTimeout = addrCounter++;
+
+		final int addrMessageTxnType = addrCounter++;
+		final int addrExpectedTradeMessageLength = addrCounter++;
+		final int addrExpectedRedeemMessageLength = addrCounter++;
+
+		final int addrCreatorAddressPointer = addrCounter++;
+		final int addrHashOfSecretBPointer = addrCounter++;
+		final int addrQortalPartnerAddressPointer = addrCounter++;
+		final int addrMessageSenderPointer = addrCounter++;
+
+		final int addrTradeMessagePartnerBitcoinPKHOffset = addrCounter++;
+		final int addrPartnerBitcoinPKHPointer = addrCounter++;
+		final int addrTradeMessageHashOfSecretAOffset = addrCounter++;
+		final int addrHashOfSecretAPointer = addrCounter++;
+
+		final int addrRedeemMessageSecretBOffset = addrCounter++;
+		final int addrRedeemMessageReceivingAddressOffset = addrCounter++;
+
+		final int addrMessageDataPointer = addrCounter++;
+		final int addrMessageDataLength = addrCounter++;
+
+		final int addrPartnerReceivingAddressPointer = addrCounter++;
+
+		final int addrEndOfConstants = addrCounter;
+
+		// Variables
+
+		final int addrCreatorAddress1 = addrCounter++;
+		final int addrCreatorAddress2 = addrCounter++;
+		final int addrCreatorAddress3 = addrCounter++;
+		final int addrCreatorAddress4 = addrCounter++;
+
+		final int addrQortalPartnerAddress1 = addrCounter++;
+		final int addrQortalPartnerAddress2 = addrCounter++;
+		final int addrQortalPartnerAddress3 = addrCounter++;
+		final int addrQortalPartnerAddress4 = addrCounter++;
+
+		final int addrLockTimeA = addrCounter++;
+		final int addrLockTimeB = addrCounter++;
+		final int addrRefundTimeout = addrCounter++;
+		final int addrRefundTimestamp = addrCounter++;
+		final int addrLastTxnTimestamp = addrCounter++;
+		final int addrBlockTimestamp = addrCounter++;
+		final int addrTxnType = addrCounter++;
+		final int addrResult = addrCounter++;
+
+		final int addrMessageSender1 = addrCounter++;
+		final int addrMessageSender2 = addrCounter++;
+		final int addrMessageSender3 = addrCounter++;
+		final int addrMessageSender4 = addrCounter++;
+
+		final int addrMessageLength = addrCounter++;
+
+		final int addrMessageData = addrCounter;
+		addrCounter += 4;
+
+		final int addrHashOfSecretA = addrCounter;
+		addrCounter += 4;
+
+		final int addrPartnerBitcoinPKH = addrCounter;
+		addrCounter += 4;
+
+		final int addrPartnerReceivingAddress = addrCounter;
+		addrCounter += 4;
+
+		final int addrMode = addrCounter++;
+		assert addrMode == MODE_VALUE_OFFSET : "MODE_VALUE_OFFSET does not match addrMode";
+
+		// Data segment
+		ByteBuffer dataByteBuffer = ByteBuffer.allocate(addrCounter * MachineState.VALUE_SIZE);
+
+		// AT creator's trade Qortal address, decoded from Base58
+		assert dataByteBuffer.position() == addrCreatorTradeAddress1 * MachineState.VALUE_SIZE : "addrCreatorTradeAddress1 incorrect";
+		byte[] creatorTradeAddressBytes = Base58.decode(creatorTradeAddress);
+		dataByteBuffer.put(Bytes.ensureCapacity(creatorTradeAddressBytes, 32, 0));
+
+		// Bitcoin public key hash
+		assert dataByteBuffer.position() == addrBitcoinPublicKeyHash * MachineState.VALUE_SIZE : "addrBitcoinPublicKeyHash incorrect";
+		dataByteBuffer.put(Bytes.ensureCapacity(bitcoinPublicKeyHash, 32, 0));
+
+		// Hash of secret-B
+		assert dataByteBuffer.position() == addrHashOfSecretB * MachineState.VALUE_SIZE : "addrHashOfSecretB incorrect";
+		dataByteBuffer.put(Bytes.ensureCapacity(hashOfSecretB, 32, 0));
+
+		// Redeem Qort amount
+		assert dataByteBuffer.position() == addrQortAmount * MachineState.VALUE_SIZE : "addrQortAmount incorrect";
+		dataByteBuffer.putLong(qortAmount);
+
+		// Expected Bitcoin amount
+		assert dataByteBuffer.position() == addrBitcoinAmount * MachineState.VALUE_SIZE : "addrBitcoinAmount incorrect";
+		dataByteBuffer.putLong(bitcoinAmount);
+
+		// Suggested trade timeout (minutes)
+		assert dataByteBuffer.position() == addrTradeTimeout * MachineState.VALUE_SIZE : "addrTradeTimeout incorrect";
+		dataByteBuffer.putLong(tradeTimeout);
+
+		// We're only interested in MESSAGE transactions
+		assert dataByteBuffer.position() == addrMessageTxnType * MachineState.VALUE_SIZE : "addrMessageTxnType incorrect";
+		dataByteBuffer.putLong(API.ATTransactionType.MESSAGE.value);
+
+		// Expected length of 'trade' MESSAGE data from AT creator
+		assert dataByteBuffer.position() == addrExpectedTradeMessageLength * MachineState.VALUE_SIZE : "addrExpectedTradeMessageLength incorrect";
+		dataByteBuffer.putLong(TRADE_MESSAGE_LENGTH);
+
+		// Expected length of 'redeem' MESSAGE data from trade partner
+		assert dataByteBuffer.position() == addrExpectedRedeemMessageLength * MachineState.VALUE_SIZE : "addrExpectedRedeemMessageLength incorrect";
+		dataByteBuffer.putLong(REDEEM_MESSAGE_LENGTH);
+
+		// Index into data segment of AT creator's address, used by GET_B_IND
+		assert dataByteBuffer.position() == addrCreatorAddressPointer * MachineState.VALUE_SIZE : "addrCreatorAddressPointer incorrect";
+		dataByteBuffer.putLong(addrCreatorAddress1);
+
+		// Index into data segment of hash of secret B, used by GET_B_IND
+		assert dataByteBuffer.position() == addrHashOfSecretBPointer * MachineState.VALUE_SIZE : "addrHashOfSecretBPointer incorrect";
+		dataByteBuffer.putLong(addrHashOfSecretB);
+
+		// Index into data segment of partner's Qortal address, used by SET_B_IND
+		assert dataByteBuffer.position() == addrQortalPartnerAddressPointer * MachineState.VALUE_SIZE : "addrQortalPartnerAddressPointer incorrect";
+		dataByteBuffer.putLong(addrQortalPartnerAddress1);
+
+		// Index into data segment of (temporary) transaction's sender's address, used by GET_B_IND
+		assert dataByteBuffer.position() == addrMessageSenderPointer * MachineState.VALUE_SIZE : "addrMessageSenderPointer incorrect";
+		dataByteBuffer.putLong(addrMessageSender1);
+
+		// Offset into 'trade' MESSAGE data payload for extracting partner's Bitcoin PKH
+		assert dataByteBuffer.position() == addrTradeMessagePartnerBitcoinPKHOffset * MachineState.VALUE_SIZE : "addrTradeMessagePartnerBitcoinPKHOffset incorrect";
+		dataByteBuffer.putLong(32L);
+
+		// Index into data segment of partner's Bitcoin PKH, used by GET_B_IND
+		assert dataByteBuffer.position() == addrPartnerBitcoinPKHPointer * MachineState.VALUE_SIZE : "addrPartnerBitcoinPKHPointer incorrect";
+		dataByteBuffer.putLong(addrPartnerBitcoinPKH);
+
+		// Offset into 'trade' MESSAGE data payload for extracting hash-of-secret-A
+		assert dataByteBuffer.position() == addrTradeMessageHashOfSecretAOffset * MachineState.VALUE_SIZE : "addrTradeMessageHashOfSecretAOffset incorrect";
+		dataByteBuffer.putLong(64L);
+
+		// Index into data segment to hash of secret A, used by GET_B_IND
+		assert dataByteBuffer.position() == addrHashOfSecretAPointer * MachineState.VALUE_SIZE : "addrHashOfSecretAPointer incorrect";
+		dataByteBuffer.putLong(addrHashOfSecretA);
+
+		// Offset into 'redeem' MESSAGE data payload for extracting secret-B
+		assert dataByteBuffer.position() == addrRedeemMessageSecretBOffset * MachineState.VALUE_SIZE : "addrRedeemMessageSecretBOffset incorrect";
+		dataByteBuffer.putLong(32L);
+
+		// Offset into 'redeem' MESSAGE data payload for extracting Qortal receiving address
+		assert dataByteBuffer.position() == addrRedeemMessageReceivingAddressOffset * MachineState.VALUE_SIZE : "addrRedeemMessageReceivingAddressOffset incorrect";
+		dataByteBuffer.putLong(64L);
+
+		// Source location and length for hashing any passed secret
+		assert dataByteBuffer.position() == addrMessageDataPointer * MachineState.VALUE_SIZE : "addrMessageDataPointer incorrect";
+		dataByteBuffer.putLong(addrMessageData);
+		assert dataByteBuffer.position() == addrMessageDataLength * MachineState.VALUE_SIZE : "addrMessageDataLength incorrect";
+		dataByteBuffer.putLong(32L);
+
+		// Pointer into data segment of where to save partner's receiving Qortal address, used by GET_B_IND
+		assert dataByteBuffer.position() == addrPartnerReceivingAddressPointer * MachineState.VALUE_SIZE : "addrPartnerReceivingAddressPointer incorrect";
+		dataByteBuffer.putLong(addrPartnerReceivingAddress);
+
+		assert dataByteBuffer.position() == addrEndOfConstants * MachineState.VALUE_SIZE : "dataByteBuffer position not at end of constants";
+
+		// Code labels
+		Integer labelRefund = null;
+
+		Integer labelTradeTxnLoop = null;
+		Integer labelCheckTradeTxn = null;
+		Integer labelCheckCancelTxn = null;
+		Integer labelNotTradeNorCancelTxn = null;
+		Integer labelCheckNonRefundTradeTxn = null;
+		Integer labelTradeTxnExtract = null;
+		Integer labelRedeemTxnLoop = null;
+		Integer labelCheckRedeemTxn = null;
+		Integer labelCheckRedeemTxnSender = null;
+		Integer labelCheckSecretB = null;
+		Integer labelPayout = null;
+
+		ByteBuffer codeByteBuffer = ByteBuffer.allocate(768);
+
+		// Two-pass version
+		for (int pass = 0; pass < 2; ++pass) {
+			codeByteBuffer.clear();
+
+			try {
+				/* Initialization */
+
+				// Use AT creation 'timestamp' as starting point for finding transactions sent to AT
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_CREATION_TIMESTAMP, addrLastTxnTimestamp));
+
+				// Load B register with AT creator's address so we can save it into addrCreatorAddress1-4
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_CREATOR_INTO_B));
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrCreatorAddressPointer));
+
+				// Set restart position to after this opcode
+				codeByteBuffer.put(OpCode.SET_PCS.compile());
+
+				/* Loop, waiting for message from AT creator's trade address containing trade partner details, or AT owner's address to cancel offer */
+
+				/* Transaction processing loop */
+				labelTradeTxnLoop = codeByteBuffer.position();
+
+				// Find next transaction (if any) to this AT since the last one (referenced by addrLastTxnTimestamp)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PUT_TX_AFTER_TIMESTAMP_INTO_A, addrLastTxnTimestamp));
+				// If no transaction found, A will be zero. If A is zero, set addrResult to 1, otherwise 0.
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.CHECK_A_IS_ZERO, addrResult));
+				// If addrResult is zero (i.e. A is non-zero, transaction was found) then go check transaction
+				codeByteBuffer.put(OpCode.BZR_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelCheckTradeTxn)));
+				// Stop and wait for next block
+				codeByteBuffer.put(OpCode.STP_IMD.compile());
+
+				/* Check transaction */
+				labelCheckTradeTxn = codeByteBuffer.position();
+
+				// Update our 'last found transaction's timestamp' using 'timestamp' from transaction
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TIMESTAMP_FROM_TX_IN_A, addrLastTxnTimestamp));
+				// Extract transaction type (message/payment) from transaction and save type in addrTxnType
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TYPE_FROM_TX_IN_A, addrTxnType));
+				// If transaction type is not MESSAGE type then go look for another transaction
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrTxnType, addrMessageTxnType, calcOffset(codeByteBuffer, labelTradeTxnLoop)));
+
+				/* Check transaction's sender. We're expecting AT creator's trade address for 'trade' message, or AT creator's own address for 'cancel' message. */
+
+				// Extract sender address from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_ADDRESS_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrMessageSender1 (as pointed to by addrMessageSenderPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageSenderPointer));
+				// Compare each part of message sender's address with AT creator's trade address. If they don't match, check for cancel situation.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrCreatorTradeAddress1, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrCreatorTradeAddress2, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrCreatorTradeAddress3, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrCreatorTradeAddress4, calcOffset(codeByteBuffer, labelCheckCancelTxn)));
+				// Message sender's address matches AT creator's trade address so go process 'trade' message
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelCheckNonRefundTradeTxn == null ? 0 : labelCheckNonRefundTradeTxn));
+
+				/* Checking message sender for possible cancel message */
+				labelCheckCancelTxn = codeByteBuffer.position();
+
+				// Compare each part of message sender's address with AT creator's address. If they don't match, look for another transaction.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrCreatorAddress1, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrCreatorAddress2, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrCreatorAddress3, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrCreatorAddress4, calcOffset(codeByteBuffer, labelNotTradeNorCancelTxn)));
+				// Partner address is AT creator's address, so cancel offer and finish.
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.CANCELLED.value));
+				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
+				codeByteBuffer.put(OpCode.FIN_IMD.compile());
+
+				/* Not trade nor cancel message */
+				labelNotTradeNorCancelTxn = codeByteBuffer.position();
+
+				// Loop to find another transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelTradeTxnLoop == null ? 0 : labelTradeTxnLoop));
+
+				/* Possible switch-to-trade-mode message */
+				labelCheckNonRefundTradeTxn = codeByteBuffer.position();
+
+				// Check 'trade' message we received has expected number of message bytes
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(QortalFunctionCode.GET_MESSAGE_LENGTH_FROM_TX_IN_A.value, addrMessageLength));
+				// If message length matches, branch to info extraction code
+				codeByteBuffer.put(OpCode.BEQ_DAT.compile(addrMessageLength, addrExpectedTradeMessageLength, calcOffset(codeByteBuffer, labelTradeTxnExtract)));
+				// Message length didn't match - go back to finding another 'trade' MESSAGE transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelTradeTxnLoop == null ? 0 : labelTradeTxnLoop));
+
+				/* Extracting info from 'trade' MESSAGE transaction */
+				labelTradeTxnExtract = codeByteBuffer.position();
+
+				// Extract message from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_MESSAGE_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrQortalPartnerAddress1 (as pointed to by addrQortalPartnerAddressPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrQortalPartnerAddressPointer));
+
+				// Extract trade partner's Bitcoin public key hash (PKH)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.PUT_PARTIAL_MESSAGE_FROM_TX_IN_A_INTO_B.value, addrTradeMessagePartnerBitcoinPKHOffset));
+				// Extract partner's Bitcoin PKH (we only really use values from B1-B3)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrPartnerBitcoinPKHPointer));
+				// Also extract lockTimeB
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_B4, addrLockTimeB));
+
+				// Grab next 32 bytes
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.PUT_PARTIAL_MESSAGE_FROM_TX_IN_A_INTO_B.value, addrTradeMessageHashOfSecretAOffset));
+
+				// Extract hash-of-secret-a (we only really use values from B1-B3)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrHashOfSecretAPointer));
+				// Extract lockTimeA (from B4)
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_B4, addrLockTimeA));
+
+				// Calculate trade refund timeout: (lockTimeA - lockTimeB) / 2 / 60
+				codeByteBuffer.put(OpCode.SET_DAT.compile(addrRefundTimeout, addrLockTimeA)); // refundTimeout = lockTimeA
+				codeByteBuffer.put(OpCode.SUB_DAT.compile(addrRefundTimeout, addrLockTimeB)); // refundTimeout -= lockTimeB
+				codeByteBuffer.put(OpCode.DIV_VAL.compile(addrRefundTimeout, 2L * 60L)); // refundTimeout /= 2 * 60
+				// Calculate trade timeout refund 'timestamp' by adding addrRefundTimeout minutes to this transaction's 'timestamp', then save into addrRefundTimestamp
+				codeByteBuffer.put(OpCode.EXT_FUN_RET_DAT_2.compile(FunctionCode.ADD_MINUTES_TO_TIMESTAMP, addrRefundTimestamp, addrLastTxnTimestamp, addrRefundTimeout));
+
+				/* We are in 'trade mode' */
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.TRADING.value));
+
+				// Set restart position to after this opcode
+				codeByteBuffer.put(OpCode.SET_PCS.compile());
+
+				/* Loop, waiting for trade timeout or 'redeem' MESSAGE from Qortal trade partner */
+
+				// Fetch current block 'timestamp'
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_BLOCK_TIMESTAMP, addrBlockTimestamp));
+				// If we're not past refund 'timestamp' then look for next transaction
+				codeByteBuffer.put(OpCode.BLT_DAT.compile(addrBlockTimestamp, addrRefundTimestamp, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+				// We're past refund 'timestamp' so go refund everything back to AT creator
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelRefund == null ? 0 : labelRefund));
+
+				/* Transaction processing loop */
+				labelRedeemTxnLoop = codeByteBuffer.position();
+
+				// Find next transaction to this AT since the last one (if any)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PUT_TX_AFTER_TIMESTAMP_INTO_A, addrLastTxnTimestamp));
+				// If no transaction found, A will be zero. If A is zero, set addrComparator to 1, otherwise 0.
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.CHECK_A_IS_ZERO, addrResult));
+				// If addrResult is zero (i.e. A is non-zero, transaction was found) then go check transaction
+				codeByteBuffer.put(OpCode.BZR_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelCheckRedeemTxn)));
+				// Stop and wait for next block
+				codeByteBuffer.put(OpCode.STP_IMD.compile());
+
+				/* Check transaction */
+				labelCheckRedeemTxn = codeByteBuffer.position();
+
+				// Update our 'last found transaction's timestamp' using 'timestamp' from transaction
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TIMESTAMP_FROM_TX_IN_A, addrLastTxnTimestamp));
+				// Extract transaction type (message/payment) from transaction and save type in addrTxnType
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TYPE_FROM_TX_IN_A, addrTxnType));
+				// If transaction type is not MESSAGE type then go look for another transaction
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrTxnType, addrMessageTxnType, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+
+				/* Check message payload length */
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(QortalFunctionCode.GET_MESSAGE_LENGTH_FROM_TX_IN_A.value, addrMessageLength));
+				// If message length matches, branch to sender checking code
+				codeByteBuffer.put(OpCode.BEQ_DAT.compile(addrMessageLength, addrExpectedRedeemMessageLength, calcOffset(codeByteBuffer, labelCheckRedeemTxnSender)));
+				// Message length didn't match - go back to finding another 'redeem' MESSAGE transaction
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelRedeemTxnLoop == null ? 0 : labelRedeemTxnLoop));
+
+				/* Check transaction's sender */
+				labelCheckRedeemTxnSender = codeByteBuffer.position();
+
+				// Extract sender address from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_ADDRESS_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrMessageSender1 (as pointed to by addrMessageSenderPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageSenderPointer));
+				// Compare each part of transaction's sender's address with expected address. If they don't match, look for another transaction.
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender1, addrQortalPartnerAddress1, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender2, addrQortalPartnerAddress2, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender3, addrQortalPartnerAddress3, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+				codeByteBuffer.put(OpCode.BNE_DAT.compile(addrMessageSender4, addrQortalPartnerAddress4, calcOffset(codeByteBuffer, labelRedeemTxnLoop)));
+
+				/* Check 'secret-A' in transaction's message */
+
+				// Extract secret-A from first 32 bytes of message from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN.compile(FunctionCode.PUT_MESSAGE_FROM_TX_IN_A_INTO_B));
+				// Save B register into data segment starting at addrMessageData (as pointed to by addrMessageDataPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageDataPointer));
+				// Load B register with expected hash result (as pointed to by addrHashOfSecretAPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.SET_B_IND, addrHashOfSecretAPointer));
+				// Perform HASH160 using source data at addrMessageData. (Location and length specified via addrMessageDataPointer and addrMessageDataLength).
+				// Save the equality result (1 if they match, 0 otherwise) into addrResult.
+				codeByteBuffer.put(OpCode.EXT_FUN_RET_DAT_2.compile(FunctionCode.CHECK_HASH160_WITH_B, addrResult, addrMessageDataPointer, addrMessageDataLength));
+				// If hashes don't match, addrResult will be zero so go find another transaction
+				codeByteBuffer.put(OpCode.BNZ_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelCheckSecretB)));
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelRedeemTxnLoop == null ? 0 : labelRedeemTxnLoop));
+
+				/* Check 'secret-B' in transaction's message */
+
+				labelCheckSecretB = codeByteBuffer.position();
+
+				// Extract secret-B from next 32 bytes of message from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.PUT_PARTIAL_MESSAGE_FROM_TX_IN_A_INTO_B.value, addrRedeemMessageSecretBOffset));
+				// Save B register into data segment starting at addrMessageData (as pointed to by addrMessageDataPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrMessageDataPointer));
+				// Load B register with expected hash result (as pointed to by addrHashOfSecretBPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.SET_B_IND, addrHashOfSecretBPointer));
+				// Perform HASH160 using source data at addrMessageData. (Location and length specified via addrMessageDataPointer and addrMessageDataLength).
+				// Save the equality result (1 if they match, 0 otherwise) into addrResult.
+				codeByteBuffer.put(OpCode.EXT_FUN_RET_DAT_2.compile(FunctionCode.CHECK_HASH160_WITH_B, addrResult, addrMessageDataPointer, addrMessageDataLength));
+				// If hashes don't match, addrResult will be zero so go find another transaction
+				codeByteBuffer.put(OpCode.BNZ_DAT.compile(addrResult, calcOffset(codeByteBuffer, labelPayout)));
+				codeByteBuffer.put(OpCode.JMP_ADR.compile(labelRedeemTxnLoop == null ? 0 : labelRedeemTxnLoop));
+
+				/* Success! Pay arranged amount to receiving address */
+				labelPayout = codeByteBuffer.position();
+
+				// Extract Qortal receiving address from next 32 bytes of message from transaction into B register
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.PUT_PARTIAL_MESSAGE_FROM_TX_IN_A_INTO_B.value, addrRedeemMessageReceivingAddressOffset));
+				// Save B register into data segment starting at addrPartnerReceivingAddress (as pointed to by addrPartnerReceivingAddressPointer)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_B_IND, addrPartnerReceivingAddressPointer));
+				// Pay AT's balance to receiving address
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PAY_TO_ADDRESS_IN_B, addrQortAmount));
+				// Set redeemed mode
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.REDEEMED.value));
+				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
+				codeByteBuffer.put(OpCode.FIN_IMD.compile());
+
+				// Fall-through to refunding any remaining balance back to AT creator
+
+				/* Refund balance back to AT creator */
+				labelRefund = codeByteBuffer.position();
+
+				// Set refunded mode
+				codeByteBuffer.put(OpCode.SET_VAL.compile(addrMode, AcctMode.REFUNDED.value));
+				// We're finished forever (finishing auto-refunds remaining balance to AT creator)
+				codeByteBuffer.put(OpCode.FIN_IMD.compile());
+			} catch (CompilationException e) {
+				throw new IllegalStateException("Unable to compile BTC-QORT ACCT?", e);
+			}
+		}
+
+		codeByteBuffer.flip();
+
+		byte[] codeBytes = new byte[codeByteBuffer.limit()];
+		codeByteBuffer.get(codeBytes);
+
+		assert Arrays.equals(Crypto.digest(codeBytes), BitcoinACCTv1.CODE_BYTES_HASH)
+			: String.format("BTCACCT.CODE_BYTES_HASH mismatch: expected %s, actual %s", HashCode.fromBytes(CODE_BYTES_HASH), HashCode.fromBytes(Crypto.digest(codeBytes)));
+
+		final short ciyamAtVersion = 2;
+		final short numCallStackPages = 0;
+		final short numUserStackPages = 0;
+		final long minActivationAmount = 0L;
+
+		return MachineState.toCreationBytes(ciyamAtVersion, codeBytes, dataByteBuffer.array(), numCallStackPages, numUserStackPages, minActivationAmount);
+	}
+
+	/**
+	 * Returns CrossChainTradeData with useful info extracted from AT.
+	 */
+	@Override
+	public CrossChainTradeData populateTradeData(Repository repository, ATData atData) throws DataException {
+		ATStateData atStateData = repository.getATRepository().getLatestATState(atData.getATAddress());
+		return populateTradeData(repository, atData.getCreatorPublicKey(), atData.getCreation(), atStateData);
+	}
+
+	/**
+	 * Returns CrossChainTradeData with useful info extracted from AT.
+	 */
+	@Override
+	public CrossChainTradeData populateTradeData(Repository repository, ATStateData atStateData) throws DataException {
+		ATData atData = repository.getATRepository().fromATAddress(atStateData.getATAddress());
+		return populateTradeData(repository, atData.getCreatorPublicKey(), atData.getCreation(), atStateData);
+	}
+
+	/**
+	 * Returns CrossChainTradeData with useful info extracted from AT.
+	 */
+	public CrossChainTradeData populateTradeData(Repository repository, byte[] creatorPublicKey, long creationTimestamp, ATStateData atStateData) throws DataException {
+		byte[] addressBytes = new byte[25]; // for general use
+		String atAddress = atStateData.getATAddress();
+
+		CrossChainTradeData tradeData = new CrossChainTradeData();
+
+		tradeData.foreignBlockchain = SupportedBlockchain.BITCOIN.name();
+		tradeData.acctName = NAME;
+
+		tradeData.qortalAtAddress = atAddress;
+		tradeData.qortalCreator = Crypto.toAddress(creatorPublicKey);
+		tradeData.creationTimestamp = creationTimestamp;
+
+		Account atAccount = new Account(repository, atAddress);
+		tradeData.qortBalance = atAccount.getConfirmedBalance(Asset.QORT);
+
+		byte[] stateData = atStateData.getStateData();
+		ByteBuffer dataByteBuffer = ByteBuffer.wrap(stateData);
+		dataByteBuffer.position(MachineState.HEADER_LENGTH);
+
+		/* Constants */
+
+		// Skip creator's trade address
+		dataByteBuffer.get(addressBytes);
+		tradeData.qortalCreatorTradeAddress = Base58.encode(addressBytes);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - addressBytes.length);
+
+		// Creator's Bitcoin/foreign public key hash
+		tradeData.creatorForeignPKH = new byte[20];
+		dataByteBuffer.get(tradeData.creatorForeignPKH);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - tradeData.creatorForeignPKH.length); // skip to 32 bytes
+
+		// Hash of secret B
+		tradeData.hashOfSecretB = new byte[20];
+		dataByteBuffer.get(tradeData.hashOfSecretB);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - tradeData.hashOfSecretB.length); // skip to 32 bytes
+
+		// Redeem payout
+		tradeData.qortAmount = dataByteBuffer.getLong();
+
+		// Expected BTC amount
+		tradeData.expectedForeignAmount = dataByteBuffer.getLong();
+
+		// Trade timeout
+		tradeData.tradeTimeout = (int) dataByteBuffer.getLong();
+
+		// Skip MESSAGE transaction type
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip expected 'trade' message length
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip expected 'redeem' message length
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to creator's address
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to hash-of-secret-B
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to partner's Qortal trade address
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to message sender
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip 'trade' message data offset for partner's bitcoin PKH
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to partner's bitcoin PKH
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip 'trade' message data offset for hash-of-secret-A
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to hash-of-secret-A
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip 'redeem' message data offset for secret-B
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip 'redeem' message data offset for partner's Qortal receiving address
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to message data
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip message data length
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip pointer to partner's receiving address
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		/* End of constants / begin variables */
+
+		// Skip AT creator's address
+		dataByteBuffer.position(dataByteBuffer.position() + 8 * 4);
+
+		// Partner's trade address (if present)
+		dataByteBuffer.get(addressBytes);
+		String qortalRecipient = Base58.encode(addressBytes);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - addressBytes.length);
+
+		// Potential lockTimeA (if in trade mode)
+		int lockTimeA = (int) dataByteBuffer.getLong();
+
+		// Potential lockTimeB (if in trade mode)
+		int lockTimeB = (int) dataByteBuffer.getLong();
+
+		// AT refund timeout (probably only useful for debugging)
+		int refundTimeout = (int) dataByteBuffer.getLong();
+
+		// Trade-mode refund timestamp (AT 'timestamp' converted to Qortal block height)
+		long tradeRefundTimestamp = dataByteBuffer.getLong();
+
+		// Skip last transaction timestamp
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip block timestamp
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip transaction type
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip temporary result
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip temporary message sender
+		dataByteBuffer.position(dataByteBuffer.position() + 8 * 4);
+
+		// Skip message length
+		dataByteBuffer.position(dataByteBuffer.position() + 8);
+
+		// Skip temporary message data
+		dataByteBuffer.position(dataByteBuffer.position() + 8 * 4);
+
+		// Potential hash160 of secret A
+		byte[] hashOfSecretA = new byte[20];
+		dataByteBuffer.get(hashOfSecretA);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - hashOfSecretA.length); // skip to 32 bytes
+
+		// Potential partner's Bitcoin PKH
+		byte[] partnerBitcoinPKH = new byte[20];
+		dataByteBuffer.get(partnerBitcoinPKH);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - partnerBitcoinPKH.length); // skip to 32 bytes
+
+		// Partner's receiving address (if present)
+		byte[] partnerReceivingAddress = new byte[25];
+		dataByteBuffer.get(partnerReceivingAddress);
+		dataByteBuffer.position(dataByteBuffer.position() + 32 - partnerReceivingAddress.length); // skip to 32 bytes
+
+		// Trade AT's 'mode'
+		long modeValue = dataByteBuffer.getLong();
+		AcctMode acctMode = AcctMode.valueOf((int) (modeValue & 0xffL));
+
+		/* End of variables */
+
+		if (acctMode != null && acctMode != AcctMode.OFFERING) {
+			tradeData.mode = acctMode;
+			tradeData.refundTimeout = refundTimeout;
+			tradeData.tradeRefundHeight = new Timestamp(tradeRefundTimestamp).blockHeight;
+			tradeData.qortalPartnerAddress = qortalRecipient;
+			tradeData.hashOfSecretA = hashOfSecretA;
+			tradeData.partnerForeignPKH = partnerBitcoinPKH;
+			tradeData.lockTimeA = lockTimeA;
+			tradeData.lockTimeB = lockTimeB;
+
+			if (acctMode == AcctMode.REDEEMED)
+				tradeData.qortalPartnerReceivingAddress = Base58.encode(partnerReceivingAddress);
+		} else {
+			tradeData.mode = AcctMode.OFFERING;
+		}
+
+		tradeData.duplicateDeprecated();
+
+		return tradeData;
+	}
+
+	/** Returns 'offer' MESSAGE payload for trade partner to send to AT creator's trade address. */
+	public static byte[] buildOfferMessage(byte[] partnerBitcoinPKH, byte[] hashOfSecretA, int lockTimeA) {
+		byte[] lockTimeABytes = BitTwiddling.toBEByteArray((long) lockTimeA);
+		return Bytes.concat(partnerBitcoinPKH, hashOfSecretA, lockTimeABytes);
+	}
+
+	/** Returns info extracted from 'offer' MESSAGE payload sent by trade partner to AT creator's trade address, or null if not valid. */
+	public static OfferMessageData extractOfferMessageData(byte[] messageData) {
+		if (messageData == null || messageData.length != OFFER_MESSAGE_LENGTH)
+			return null;
+
+		OfferMessageData offerMessageData = new OfferMessageData();
+		offerMessageData.partnerBitcoinPKH = Arrays.copyOfRange(messageData, 0, 20);
+		offerMessageData.hashOfSecretA = Arrays.copyOfRange(messageData, 20, 40);
+		offerMessageData.lockTimeA = BitTwiddling.longFromBEBytes(messageData, 40);
+
+		return offerMessageData;
+	}
+
+	/** Returns 'trade' MESSAGE payload for AT creator to send to AT. */
+	public static byte[] buildTradeMessage(String partnerQortalTradeAddress, byte[] partnerBitcoinPKH, byte[] hashOfSecretA, int lockTimeA, int lockTimeB) {
+		byte[] data = new byte[TRADE_MESSAGE_LENGTH];
+		byte[] partnerQortalAddressBytes = Base58.decode(partnerQortalTradeAddress);
+		byte[] lockTimeABytes = BitTwiddling.toBEByteArray((long) lockTimeA);
+		byte[] lockTimeBBytes = BitTwiddling.toBEByteArray((long) lockTimeB);
+
+		System.arraycopy(partnerQortalAddressBytes, 0, data, 0, partnerQortalAddressBytes.length);
+		System.arraycopy(partnerBitcoinPKH, 0, data, 32, partnerBitcoinPKH.length);
+		System.arraycopy(lockTimeBBytes, 0, data, 56, lockTimeBBytes.length);
+		System.arraycopy(hashOfSecretA, 0, data, 64, hashOfSecretA.length);
+		System.arraycopy(lockTimeABytes, 0, data, 88, lockTimeABytes.length);
+
+		return data;
+	}
+
+	/** Returns 'cancel' MESSAGE payload for AT creator to cancel trade AT. */
+	@Override
+	public byte[] buildCancelMessage(String creatorQortalAddress) {
+		byte[] data = new byte[CANCEL_MESSAGE_LENGTH];
+		byte[] creatorQortalAddressBytes = Base58.decode(creatorQortalAddress);
+
+		System.arraycopy(creatorQortalAddressBytes, 0, data, 0, creatorQortalAddressBytes.length);
+
+		return data;
+	}
+
+	/** Returns 'redeem' MESSAGE payload for trade partner/ to send to AT. */
+	public static byte[] buildRedeemMessage(byte[] secretA, byte[] secretB, String qortalReceivingAddress) {
+		byte[] data = new byte[REDEEM_MESSAGE_LENGTH];
+		byte[] qortalReceivingAddressBytes = Base58.decode(qortalReceivingAddress);
+
+		System.arraycopy(secretA, 0, data, 0, secretA.length);
+		System.arraycopy(secretB, 0, data, 32, secretB.length);
+		System.arraycopy(qortalReceivingAddressBytes, 0, data, 64, qortalReceivingAddressBytes.length);
+
+		return data;
+	}
+
+	/** Returns P2SH-B lockTime (epoch seconds) based on trade partner's 'offer' MESSAGE timestamp and P2SH-A locktime. */
+	public static int calcLockTimeB(long offerMessageTimestamp, int lockTimeA) {
+		// lockTimeB is halfway between offerMessageTimestamp and lockTimeA
+		return (int) ((lockTimeA + (offerMessageTimestamp / 1000L)) / 2L);
+	}
+
+	public static byte[] findSecretA(Repository repository, CrossChainTradeData crossChainTradeData) throws DataException {
+		String atAddress = crossChainTradeData.qortalAtAddress;
+		String redeemerAddress = crossChainTradeData.qortalPartnerAddress;
+
+		// We don't have partner's public key so we check every message to AT
+		List<MessageTransactionData> messageTransactionsData = repository.getMessageRepository().getMessagesByParticipants(null, atAddress, null, null, null);
+		if (messageTransactionsData == null)
+			return null;
+
+		// Find 'redeem' message
+		for (MessageTransactionData messageTransactionData : messageTransactionsData) {
+			// Check message payload type/encryption
+			if (messageTransactionData.isText() || messageTransactionData.isEncrypted())
+				continue;
+
+			// Check message payload size
+			byte[] messageData = messageTransactionData.getData();
+			if (messageData.length != REDEEM_MESSAGE_LENGTH)
+				// Wrong payload length
+				continue;
+
+			// Check sender
+			if (!Crypto.toAddress(messageTransactionData.getSenderPublicKey()).equals(redeemerAddress))
+				// Wrong sender;
+				continue;
+
+			// Extract both secretA & secretB
+			byte[] secretA = new byte[32];
+			System.arraycopy(messageData, 0, secretA, 0, secretA.length);
+			byte[] secretB = new byte[32];
+			System.arraycopy(messageData, 32, secretB, 0, secretB.length);
+
+			byte[] hashOfSecretA = Crypto.hash160(secretA);
+			if (!Arrays.equals(hashOfSecretA, crossChainTradeData.hashOfSecretA))
+				continue;
+
+			byte[] hashOfSecretB = Crypto.hash160(secretB);
+			if (!Arrays.equals(hashOfSecretB, crossChainTradeData.hashOfSecretB))
+				continue;
+
+			return secretA;
+		}
+
+		return null;
+	}
+
+}

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

@@ -0,0 +1,706 @@
+package org.qortal.crosschain;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+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;
+import org.bitcoinj.core.InsufficientMoneyException;
+import org.bitcoinj.core.LegacyAddress;
+import org.bitcoinj.core.NetworkParameters;
+import org.bitcoinj.core.Sha256Hash;
+import org.bitcoinj.core.Transaction;
+import org.bitcoinj.core.TransactionOutput;
+import org.bitcoinj.core.UTXO;
+import org.bitcoinj.core.UTXOProvider;
+import org.bitcoinj.core.UTXOProviderException;
+import org.bitcoinj.crypto.ChildNumber;
+import org.bitcoinj.crypto.DeterministicHierarchy;
+import org.bitcoinj.crypto.DeterministicKey;
+import org.bitcoinj.script.Script.ScriptType;
+import org.bitcoinj.script.ScriptBuilder;
+import org.bitcoinj.wallet.DeterministicKeyChain;
+import org.bitcoinj.wallet.SendRequest;
+import org.bitcoinj.wallet.Wallet;
+import org.qortal.api.model.SimpleForeignTransaction;
+import org.qortal.crypto.Crypto;
+import org.qortal.utils.Amounts;
+import org.qortal.utils.BitTwiddling;
+
+import com.google.common.hash.HashCode;
+
+/** Bitcoin-like (Bitcoin, Litecoin, etc.) support */
+public abstract class Bitcoiny implements ForeignBlockchain {
+
+	protected static final Logger LOGGER = LogManager.getLogger(Bitcoiny.class);
+
+	public static final int HASH160_LENGTH = 20;
+
+	protected final BitcoinyBlockchainProvider blockchain;
+	protected final Context bitcoinjContext;
+	protected final String currencyCode;
+
+	protected final NetworkParameters params;
+
+	/** Keys that have been previously marked as fully spent,<br>
+	 * i.e. keys with transactions but with no unspent outputs. */
+	protected final Set<ECKey> spentKeys = Collections.synchronizedSet(new HashSet<>());
+
+	/** How many bitcoinj wallet keys to generate in each batch. */
+	private static final int WALLET_KEY_LOOKAHEAD_INCREMENT = 3;
+
+	/** Byte offset into raw block headers to block timestamp. */
+	private static final int TIMESTAMP_OFFSET = 4 + 32 + 32;
+
+	// Constructors and instance
+
+	protected Bitcoiny(BitcoinyBlockchainProvider blockchain, Context bitcoinjContext, String currencyCode) {
+		this.blockchain = blockchain;
+		this.bitcoinjContext = bitcoinjContext;
+		this.currencyCode = currencyCode;
+
+		this.params = this.bitcoinjContext.getParams();
+	}
+
+	// Getters & setters
+
+	public BitcoinyBlockchainProvider getBlockchainProvider() {
+		return this.blockchain;
+	}
+
+	public Context getBitcoinjContext() {
+		return this.bitcoinjContext;
+	}
+
+	public String getCurrencyCode() {
+		return this.currencyCode;
+	}
+
+	public NetworkParameters getNetworkParameters() {
+		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.isValidDeterministicKey(walletKey);
+	}
+
+	// Actual useful methods for use by other classes
+
+	public String format(Coin amount) {
+		return this.format(amount.value);
+	}
+
+	public String format(long amount) {
+		return Amounts.prettyAmount(amount) + " " + this.currencyCode;
+	}
+
+	public boolean isValidDeterministicKey(String key58) {
+		try {
+			Context.propagate(this.bitcoinjContext);
+			DeterministicKey.deserializeB58(null, key58, this.params);
+			return true;
+		} catch (IllegalArgumentException e) {
+			return false;
+		}
+	}
+
+	/** Returns P2PKH address using passed public key hash. */
+	public String pkhToAddress(byte[] publicKeyHash) {
+		Context.propagate(this.bitcoinjContext);
+		return LegacyAddress.fromPubKeyHash(this.params, publicKeyHash).toString();
+	}
+
+	/** Returns P2SH address using passed redeem script. */
+	public String deriveP2shAddress(byte[] redeemScriptBytes) {
+		Context.propagate(bitcoinjContext);
+		byte[] redeemScriptHash = Crypto.hash160(redeemScriptBytes);
+		return LegacyAddress.fromScriptHash(this.params, redeemScriptHash).toString();
+	}
+
+	/**
+	 * Returns median timestamp from latest 11 blocks, in seconds.
+	 * <p>
+	 * @throws ForeignBlockchainException if error occurs
+	 */
+	public int getMedianBlockTime() throws ForeignBlockchainException {
+		int height = this.blockchain.getCurrentHeight();
+
+		// Grab latest 11 blocks
+		List<byte[]> blockHeaders = this.blockchain.getRawBlockHeaders(height - 11, 11);
+		if (blockHeaders.size() < 11)
+			throw new ForeignBlockchainException("Not enough blocks to determine median block time");
+
+		List<Integer> blockTimestamps = blockHeaders.stream().map(blockHeader -> BitTwiddling.intFromLEBytes(blockHeader, TIMESTAMP_OFFSET)).collect(Collectors.toList());
+
+		// Descending order
+		blockTimestamps.sort((a, b) -> Integer.compare(b, a));
+
+		// Pick median
+		return blockTimestamps.get(5);
+	}
+
+	/** Returns fee per transaction KB. To be overridden for testnet/regtest. */
+	public Coin getFeePerKb() {
+		return this.bitcoinjContext.getFeePerKb();
+	}
+
+	/**
+	 * Returns fixed P2SH spending fee, in sats per 1000bytes, optionally for historic timestamp.
+	 * 
+	 * @param timestamp optional milliseconds since epoch, or null for 'now'
+	 * @return sats per 1000bytes
+	 * @throws ForeignBlockchainException if something went wrong
+	 */
+	public abstract long getP2shFee(Long timestamp) throws ForeignBlockchainException;
+
+	/**
+	 * Returns confirmed balance, based on passed payment script.
+	 * <p>
+	 * @return confirmed balance, or zero if script unknown
+	 * @throws ForeignBlockchainException if there was an error
+	 */
+	public long getConfirmedBalance(String base58Address) throws ForeignBlockchainException {
+		return this.blockchain.getConfirmedBalance(addressToScriptPubKey(base58Address));
+	}
+
+	/**
+	 * Returns list of unspent outputs pertaining to passed address.
+	 * <p>
+	 * @return list of unspent outputs, or empty list if address unknown
+	 * @throws ForeignBlockchainException if there was an error.
+	 */
+	// TODO: don't return bitcoinj-based objects like TransactionOutput, use BitcoinyTransaction.Output instead
+	public List<TransactionOutput> getUnspentOutputs(String base58Address) throws ForeignBlockchainException {
+		List<UnspentOutput> unspentOutputs = this.blockchain.getUnspentOutputs(addressToScriptPubKey(base58Address), false);
+
+		List<TransactionOutput> unspentTransactionOutputs = new ArrayList<>();
+		for (UnspentOutput unspentOutput : unspentOutputs) {
+			List<TransactionOutput> transactionOutputs = this.getOutputs(unspentOutput.hash);
+
+			unspentTransactionOutputs.add(transactionOutputs.get(unspentOutput.index));
+		}
+
+		return unspentTransactionOutputs;
+	}
+
+	/**
+	 * Returns list of outputs pertaining to passed transaction hash.
+	 * <p>
+	 * @return list of outputs, or empty list if transaction unknown
+	 * @throws ForeignBlockchainException if there was an error.
+	 */
+	// TODO: don't return bitcoinj-based objects like TransactionOutput, use BitcoinyTransaction.Output instead
+	public List<TransactionOutput> getOutputs(byte[] txHash) throws ForeignBlockchainException {
+		byte[] rawTransactionBytes = this.blockchain.getRawTransaction(txHash);
+
+		Context.propagate(bitcoinjContext);
+		Transaction transaction = new Transaction(this.params, rawTransactionBytes);
+		return transaction.getOutputs();
+	}
+
+	/**
+	 * Returns list of transaction hashes pertaining to passed address.
+	 * <p>
+	 * @return list of unspent outputs, or empty list if script unknown
+	 * @throws ForeignBlockchainException if there was an error.
+	 */
+	public List<TransactionHash> getAddressTransactions(String base58Address, boolean includeUnconfirmed) throws ForeignBlockchainException {
+		return this.blockchain.getAddressTransactions(addressToScriptPubKey(base58Address), includeUnconfirmed);
+	}
+
+	/**
+	 * Returns list of raw, confirmed transactions involving given address.
+	 * <p>
+	 * @throws ForeignBlockchainException if there was an error
+	 */
+	public List<byte[]> getAddressTransactions(String base58Address) throws ForeignBlockchainException {
+		List<TransactionHash> transactionHashes = this.blockchain.getAddressTransactions(addressToScriptPubKey(base58Address), false);
+
+		List<byte[]> rawTransactions = new ArrayList<>();
+		for (TransactionHash transactionInfo : transactionHashes) {
+			byte[] rawTransaction = this.blockchain.getRawTransaction(HashCode.fromString(transactionInfo.txHash).asBytes());
+			rawTransactions.add(rawTransaction);
+		}
+
+		return rawTransactions;
+	}
+
+	/**
+	 * Returns transaction info for passed transaction hash.
+	 * <p>
+	 * @throws ForeignBlockchainException.NotFoundException if transaction unknown
+	 * @throws ForeignBlockchainException if error occurs
+	 */
+	public BitcoinyTransaction getTransaction(String txHash) throws ForeignBlockchainException {
+		return this.blockchain.getTransaction(txHash);
+	}
+
+	/**
+	 * Broadcasts raw transaction to network.
+	 * <p>
+	 * @throws ForeignBlockchainException if error occurs
+	 */
+	public void broadcastTransaction(Transaction transaction) throws ForeignBlockchainException {
+		this.blockchain.broadcastTransaction(transaction.bitcoinSerialize());
+	}
+
+	/**
+	 * Returns bitcoinj transaction sending <tt>amount</tt> to <tt>recipient</tt>.
+	 * 
+	 * @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, Long feePerByte) {
+		Context.propagate(bitcoinjContext);
+
+		Wallet wallet = Wallet.fromSpendingKeyB58(this.params, xprv58, DeterministicHierarchy.BIP32_STANDARDISATION_TIME_SECS);
+		wallet.setUTXOProvider(new WalletAwareUTXOProvider(this, wallet));
+
+		Address destination = Address.fromString(this.params, recipient);
+		SendRequest sendRequest = SendRequest.to(destination, Coin.valueOf(amount));
+
+		if (feePerByte != null)
+			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);
+			return sendRequest.tx;
+		} catch (InsufficientMoneyException e) {
+			return null;
+		}
+	}
+
+	/**
+	 * 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.
+	 *
+	 * @param key58 BIP32/HD extended Bitcoin private/public key
+	 * @return unspent BTC balance, or null if unable to determine balance
+	 */
+	public Long getWalletBalance(String key58) {
+		Context.propagate(bitcoinjContext);
+
+		Wallet wallet = walletFromDeterministicKey58(key58);
+		wallet.setUTXOProvider(new WalletAwareUTXOProvider(this, wallet));
+
+		Coin balance = wallet.getBalance();
+		if (balance == null)
+			return null;
+
+		return balance.value;
+	}
+
+	public List<BitcoinyTransaction> getWalletTransactions(String key58) throws ForeignBlockchainException {
+		Context.propagate(bitcoinjContext);
+
+		Wallet wallet = walletFromDeterministicKey58(key58);
+		DeterministicKeyChain keyChain = wallet.getActiveKeyChain();
+
+		keyChain.setLookaheadSize(Bitcoiny.WALLET_KEY_LOOKAHEAD_INCREMENT);
+		keyChain.maybeLookAhead();
+
+		List<DeterministicKey> keys = new ArrayList<>(keyChain.getLeafKeys());
+
+		Set<BitcoinyTransaction> walletTransactions = new HashSet<>();
+
+		int ki = 0;
+		do {
+			boolean areAllKeysUnused = true;
+
+			for (; ki < keys.size(); ++ki) {
+				DeterministicKey dKey = keys.get(ki);
+
+				// Check for transactions
+				Address address = Address.fromKey(this.params, dKey, ScriptType.P2PKH);
+				byte[] script = ScriptBuilder.createOutputScript(address).getProgram();
+
+				// Ask for transaction history - if it's empty then key has never been used
+				List<TransactionHash> historicTransactionHashes = this.blockchain.getAddressTransactions(script, false);
+
+				if (!historicTransactionHashes.isEmpty()) {
+					areAllKeysUnused = false;
+
+					for (TransactionHash transactionHash : historicTransactionHashes)
+						walletTransactions.add(this.getTransaction(transactionHash.txHash));
+				}
+			}
+
+			if (areAllKeysUnused)
+				// No transactions for this batch of keys so assume we're done searching.
+				break;
+
+			// Generate some more keys
+			keys.addAll(generateMoreKeys(keyChain));
+
+			// Process new keys
+		} while (true);
+
+		Comparator<BitcoinyTransaction> newestTimestampFirstComparator = Comparator.comparingInt((BitcoinyTransaction txn) -> txn.timestamp).reversed();
+
+		return walletTransactions.stream().sorted(newestTimestampFirstComparator).collect(Collectors.toList());
+	}
+
+	/**
+	 * Returns first unused receive address given 'm' BIP32 key.
+	 *
+	 * @param key58 BIP32/HD extended Bitcoin private/public key
+	 * @return P2PKH address
+	 * @throws ForeignBlockchainException if something went wrong
+	 */
+	public String getUnusedReceiveAddress(String key58) throws ForeignBlockchainException {
+		Context.propagate(bitcoinjContext);
+
+		Wallet wallet = walletFromDeterministicKey58(key58);
+		DeterministicKeyChain keyChain = wallet.getActiveKeyChain();
+
+		keyChain.setLookaheadSize(Bitcoiny.WALLET_KEY_LOOKAHEAD_INCREMENT);
+		keyChain.maybeLookAhead();
+
+		final int keyChainPathSize = keyChain.getAccountPath().size();
+		List<DeterministicKey> keys = new ArrayList<>(keyChain.getLeafKeys());
+
+		int ki = 0;
+		do {
+			for (; ki < keys.size(); ++ki) {
+				DeterministicKey dKey = keys.get(ki);
+				List<ChildNumber> dKeyPath = dKey.getPath();
+
+				// If keyChain is based on 'm', then make sure dKey is m/0/ki - i.e. a 'receive' address, not 'change' (m/1/ki)
+				if (dKeyPath.size() != keyChainPathSize + 2 || dKeyPath.get(dKeyPath.size() - 2) != ChildNumber.ZERO)
+					continue;
+
+				// Check unspent
+				Address address = Address.fromKey(this.params, dKey, ScriptType.P2PKH);
+				byte[] script = ScriptBuilder.createOutputScript(address).getProgram();
+
+				List<UnspentOutput> unspentOutputs = this.blockchain.getUnspentOutputs(script, false);
+
+				/*
+				 * If there are no unspent outputs then either:
+				 * a) all the outputs have been spent
+				 * b) address has never been used
+				 * 
+				 * For case (a) we want to remember not to check this address (key) again.
+				 */
+
+				if (unspentOutputs.isEmpty()) {
+					// If this is a known key that has been spent before, then we can skip asking for transaction history
+					if (this.spentKeys.contains(dKey)) {
+						wallet.getActiveKeyChain().markKeyAsUsed(dKey);
+						continue;
+					}
+
+					// Ask for transaction history - if it's empty then key has never been used
+					List<TransactionHash> historicTransactionHashes = this.blockchain.getAddressTransactions(script, false);
+
+					if (!historicTransactionHashes.isEmpty()) {
+						// Fully spent key - case (a)
+						this.spentKeys.add(dKey);
+						wallet.getActiveKeyChain().markKeyAsUsed(dKey);
+						continue;
+					}
+
+					// Key never been used - case (b)
+					return address.toString();
+				}
+
+				// Key has unspent outputs, hence used, so no good to us
+				this.spentKeys.remove(dKey);
+			}
+
+			// Generate some more keys
+			keys.addAll(generateMoreKeys(keyChain));
+
+			// Process new keys
+		} while (true);
+	}
+
+	// UTXOProvider support
+
+	static class WalletAwareUTXOProvider implements UTXOProvider {
+		private final Bitcoiny bitcoiny;
+		private final Wallet wallet;
+
+		private final DeterministicKeyChain keyChain;
+
+		public WalletAwareUTXOProvider(Bitcoiny bitcoiny, Wallet wallet) {
+			this.bitcoiny = bitcoiny;
+			this.wallet = wallet;
+			this.keyChain = this.wallet.getActiveKeyChain();
+
+			// Set up wallet's key chain
+			this.keyChain.setLookaheadSize(Bitcoiny.WALLET_KEY_LOOKAHEAD_INCREMENT);
+			this.keyChain.maybeLookAhead();
+		}
+
+		@Override
+		public List<UTXO> getOpenTransactionOutputs(List<ECKey> keys) throws UTXOProviderException {
+			List<UTXO> allUnspentOutputs = new ArrayList<>();
+			final boolean coinbase = false;
+
+			int ki = 0;
+			do {
+				boolean areAllKeysUnspent = true;
+
+				for (; ki < keys.size(); ++ki) {
+					ECKey key = keys.get(ki);
+
+					Address address = Address.fromKey(this.bitcoiny.params, key, ScriptType.P2PKH);
+					byte[] script = ScriptBuilder.createOutputScript(address).getProgram();
+
+					List<UnspentOutput> unspentOutputs;
+					try {
+						unspentOutputs = this.bitcoiny.blockchain.getUnspentOutputs(script, false);
+					} catch (ForeignBlockchainException e) {
+						throw new UTXOProviderException(String.format("Unable to fetch unspent outputs for %s", address));
+					}
+
+					/*
+					 * If there are no unspent outputs then either:
+					 * a) all the outputs have been spent
+					 * b) address has never been used
+					 * 
+					 * For case (a) we want to remember not to check this address (key) again.
+					 */
+
+					if (unspentOutputs.isEmpty()) {
+						// If this is a known key that has been spent before, then we can skip asking for transaction history
+						if (this.bitcoiny.spentKeys.contains(key)) {
+							this.wallet.getActiveKeyChain().markKeyAsUsed((DeterministicKey) key);
+							areAllKeysUnspent = false;
+							continue;
+						}
+
+						// Ask for transaction history - if it's empty then key has never been used
+						List<TransactionHash> historicTransactionHashes;
+						try {
+							historicTransactionHashes = this.bitcoiny.blockchain.getAddressTransactions(script, false);
+						} catch (ForeignBlockchainException e) {
+							throw new UTXOProviderException(String.format("Unable to fetch transaction history for %s", address));
+						}
+
+						if (!historicTransactionHashes.isEmpty()) {
+							// Fully spent key - case (a)
+							this.bitcoiny.spentKeys.add(key);
+							this.wallet.getActiveKeyChain().markKeyAsUsed((DeterministicKey) key);
+							areAllKeysUnspent = false;
+						} else {
+							// Key never been used - case (b)
+						}
+
+						continue;
+					}
+
+					// If we reach here, then there's definitely at least one unspent key
+					this.bitcoiny.spentKeys.remove(key);
+
+					for (UnspentOutput unspentOutput : unspentOutputs) {
+						List<TransactionOutput> transactionOutputs;
+						try {
+							transactionOutputs = this.bitcoiny.getOutputs(unspentOutput.hash);
+						} catch (ForeignBlockchainException e) {
+							throw new UTXOProviderException(String.format("Unable to fetch outputs for TX %s",
+									HashCode.fromBytes(unspentOutput.hash)));
+						}
+
+						TransactionOutput transactionOutput = transactionOutputs.get(unspentOutput.index);
+
+						UTXO utxo = new UTXO(Sha256Hash.wrap(unspentOutput.hash), unspentOutput.index,
+								Coin.valueOf(unspentOutput.value), unspentOutput.height, coinbase,
+								transactionOutput.getScriptPubKey());
+
+						allUnspentOutputs.add(utxo);
+					}
+				}
+
+				if (areAllKeysUnspent)
+					// No transactions for this batch of keys so assume we're done searching.
+					return allUnspentOutputs;
+
+				// Generate some more keys
+				keys.addAll(Bitcoiny.generateMoreKeys(this.keyChain));
+
+				// Process new keys
+			} while (true);
+		}
+
+		@Override
+		public int getChainHeadHeight() throws UTXOProviderException {
+			try {
+				return this.bitcoiny.blockchain.getCurrentHeight();
+			} catch (ForeignBlockchainException e) {
+				throw new UTXOProviderException("Unable to determine Bitcoiny chain height");
+			}
+		}
+
+		@Override
+		public NetworkParameters getParams() {
+			return this.bitcoiny.params;
+		}
+	}
+
+	// Utility methods for others
+
+	public static List<SimpleForeignTransaction> simplifyWalletTransactions(List<BitcoinyTransaction> transactions) {
+		// Sort by oldest timestamp first
+		transactions.sort(Comparator.comparingInt(t -> t.timestamp));
+
+		// Manual 2nd-level sort same-timestamp transactions so that a transaction's input comes first
+		int fromIndex = 0;
+		do {
+			int timestamp = transactions.get(fromIndex).timestamp;
+
+			int toIndex;
+			for (toIndex = fromIndex + 1; toIndex < transactions.size(); ++toIndex)
+				if (transactions.get(toIndex).timestamp != timestamp)
+					break;
+
+			// Process same-timestamp sub-list
+			List<BitcoinyTransaction> subList = transactions.subList(fromIndex, toIndex);
+
+			// Only if necessary
+			if (subList.size() > 1) {
+				// Quick index lookup
+				Map<String, Integer> indexByTxHash = subList.stream().collect(Collectors.toMap(t -> t.txHash, t -> t.timestamp));
+
+				int restartIndex = 0;
+				boolean isSorted;
+				do {
+					isSorted = true;
+
+					for (int ourIndex = restartIndex; ourIndex < subList.size(); ++ourIndex) {
+						BitcoinyTransaction ourTx = subList.get(ourIndex);
+
+						for (BitcoinyTransaction.Input input : ourTx.inputs) {
+							Integer inputIndex = indexByTxHash.get(input.outputTxHash);
+
+							if (inputIndex != null && inputIndex > ourIndex) {
+								// Input tx is currently after current tx, so swap
+								BitcoinyTransaction tmpTx = subList.get(inputIndex);
+								subList.set(inputIndex, ourTx);
+								subList.set(ourIndex, tmpTx);
+
+								// Update index lookup too
+								indexByTxHash.put(ourTx.txHash, inputIndex);
+								indexByTxHash.put(tmpTx.txHash, ourIndex);
+
+								if (isSorted)
+									restartIndex = Math.max(restartIndex, ourIndex);
+
+								isSorted = false;
+								break;
+							}
+						}
+					}
+				} while (!isSorted);
+			}
+
+			fromIndex = toIndex;
+		} while (fromIndex < transactions.size());
+
+		// Simplify
+		List<SimpleForeignTransaction> simpleTransactions = new ArrayList<>();
+
+		// Quick lookup of txs in our wallet
+		Set<String> walletTxHashes = transactions.stream().map(t -> t.txHash).collect(Collectors.toSet());
+
+		for (BitcoinyTransaction transaction : transactions) {
+			SimpleForeignTransaction.Builder builder = new SimpleForeignTransaction.Builder();
+			builder.txHash(transaction.txHash);
+			builder.timestamp(transaction.timestamp);
+
+			builder.isSentNotReceived(false);
+
+			for (BitcoinyTransaction.Input input : transaction.inputs) {
+				// TODO: add input via builder
+
+				if (walletTxHashes.contains(input.outputTxHash))
+					builder.isSentNotReceived(true);
+			}
+
+			for (BitcoinyTransaction.Output output : transaction.outputs)
+				builder.output(output.addresses, output.value);
+
+			simpleTransactions.add(builder.build());
+		}
+
+		return simpleTransactions;
+	}
+
+	// Utility methods for us
+
+	protected static List<DeterministicKey> generateMoreKeys(DeterministicKeyChain keyChain) {
+		int existingLeafKeyCount = keyChain.getLeafKeys().size();
+
+		// Increase lookahead size...
+		keyChain.setLookaheadSize(keyChain.getLookaheadSize() + Bitcoiny.WALLET_KEY_LOOKAHEAD_INCREMENT);
+		// ...and lookahead threshold (minimum number of keys to generate)...
+		keyChain.setLookaheadThreshold(0);
+		// ...so that this call will generate more keys
+		keyChain.maybeLookAhead();
+
+		// This returns *all* keys
+		List<DeterministicKey> allLeafKeys = keyChain.getLeafKeys();
+
+		// Only return newly generated keys
+		return allLeafKeys.subList(existingLeafKeyCount, allLeafKeys.size());
+	}
+
+	protected byte[] addressToScriptPubKey(String base58Address) {
+		Context.propagate(this.bitcoinjContext);
+		Address address = Address.fromString(this.params, base58Address);
+		return ScriptBuilder.createOutputScript(address).getProgram();
+	}
+
+	protected Wallet walletFromDeterministicKey58(String key58) {
+		DeterministicKey dKey = DeterministicKey.deserializeB58(null, key58, this.params);
+
+		if (dKey.hasPrivKey())
+			return Wallet.fromSpendingKeyB58(this.params, key58, DeterministicHierarchy.BIP32_STANDARDISATION_TIME_SECS);
+		else
+			return Wallet.fromWatchingKeyB58(this.params, key58, DeterministicHierarchy.BIP32_STANDARDISATION_TIME_SECS);
+	}
+
+}

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

@@ -0,0 +1,40 @@
+package org.qortal.crosschain;
+
+import java.util.List;
+
+public abstract class BitcoinyBlockchainProvider {
+
+	public static final boolean INCLUDE_UNCONFIRMED = true;
+	public static final boolean EXCLUDE_UNCONFIRMED = false;
+
+	/** Returns ID unique to bitcoiny network (e.g. "Litecoin-TEST3") */
+	public abstract String getNetId();
+
+	/** Returns current blockchain height. */
+	public abstract int getCurrentHeight() throws ForeignBlockchainException;
+
+	/** Returns a list of raw block headers, starting at <tt>startHeight</tt> (inclusive), up to <tt>count</tt> max. */
+	public abstract List<byte[]> getRawBlockHeaders(int startHeight, int count) throws ForeignBlockchainException;
+
+	/** Returns balance of address represented by <tt>scriptPubKey</tt>. */
+	public abstract long getConfirmedBalance(byte[] scriptPubKey) throws ForeignBlockchainException;
+
+	/** Returns raw, serialized, transaction bytes given <tt>txHash</tt>. */
+	public abstract byte[] getRawTransaction(String txHash) throws ForeignBlockchainException;
+
+	/** Returns raw, serialized, transaction bytes given <tt>txHash</tt>. */
+	public abstract byte[] getRawTransaction(byte[] txHash) throws ForeignBlockchainException;
+
+	/** Returns unpacked transaction given <tt>txHash</tt>. */
+	public abstract BitcoinyTransaction getTransaction(String txHash) throws ForeignBlockchainException;
+
+	/** Returns list of transaction hashes (and heights) for address represented by <tt>scriptPubKey</tt>, optionally including unconfirmed transactions. */
+	public abstract List<TransactionHash> getAddressTransactions(byte[] scriptPubKey, boolean includeUnconfirmed) throws ForeignBlockchainException;
+
+	/** Returns list of unspent transaction outputs for address represented by <tt>scriptPubKey</tt>, optionally including unconfirmed transactions. */
+	public abstract List<UnspentOutput> getUnspentOutputs(byte[] scriptPubKey, boolean includeUnconfirmed) throws ForeignBlockchainException;
+
+	/** Broadcasts raw, serialized, transaction bytes to network, returning success/failure. */
+	public abstract void broadcastTransaction(byte[] rawTransaction) throws ForeignBlockchainException;
+
+}

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

@@ -0,0 +1,438 @@
+package org.qortal.crosschain;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Function;
+
+import org.bitcoinj.core.Address;
+import org.bitcoinj.core.Base58;
+import org.bitcoinj.core.Coin;
+import org.bitcoinj.core.ECKey;
+import org.bitcoinj.core.LegacyAddress;
+import org.bitcoinj.core.NetworkParameters;
+import org.bitcoinj.core.Transaction;
+import org.bitcoinj.core.Transaction.SigHash;
+import org.bitcoinj.core.TransactionInput;
+import org.bitcoinj.core.TransactionOutput;
+import org.bitcoinj.crypto.TransactionSignature;
+import org.bitcoinj.script.Script;
+import org.bitcoinj.script.ScriptBuilder;
+import org.bitcoinj.script.ScriptChunk;
+import org.bitcoinj.script.ScriptOpCodes;
+import org.qortal.crypto.Crypto;
+import org.qortal.utils.BitTwiddling;
+
+import com.google.common.hash.HashCode;
+import com.google.common.primitives.Bytes;
+
+public class BitcoinyHTLC {
+
+	public enum Status {
+		UNFUNDED, FUNDING_IN_PROGRESS, FUNDED, REDEEM_IN_PROGRESS, REDEEMED, REFUND_IN_PROGRESS, REFUNDED
+	}
+
+	public static final int SECRET_LENGTH = 32;
+	public static final int MIN_LOCKTIME = 1500000000;
+
+	public static final long NO_LOCKTIME_NO_RBF_SEQUENCE = 0xFFFFFFFFL;
+	public static final long LOCKTIME_NO_RBF_SEQUENCE = NO_LOCKTIME_NO_RBF_SEQUENCE - 1;
+
+	// Assuming node's trade-bot has no more than 100 entries?
+	private static final int MAX_CACHE_ENTRIES = 100;
+
+	// Max time-to-live for cache entries (milliseconds)
+	private static final long CACHE_TIMEOUT = 30_000L;
+
+	@SuppressWarnings("serial")
+	private static final Map<String, byte[]> SECRET_CACHE = new LinkedHashMap<>(MAX_CACHE_ENTRIES + 1, 0.75F, true) {
+		// This method is called just after a new entry has been added
+		@Override
+		public boolean removeEldestEntry(Map.Entry<String, byte[]> eldest) {
+			return size() > MAX_CACHE_ENTRIES;
+		}
+	};
+	private static final byte[] NO_SECRET_CACHE_ENTRY = new byte[0];
+
+	@SuppressWarnings("serial")
+	private static final Map<String, Status> STATUS_CACHE = new LinkedHashMap<>(MAX_CACHE_ENTRIES + 1, 0.75F, true) {
+		// This method is called just after a new entry has been added
+		@Override
+		public boolean removeEldestEntry(Map.Entry<String, Status> eldest) {
+			return size() > MAX_CACHE_ENTRIES;
+		}
+	};
+
+	/*
+	 * OP_TUCK (to copy public key to before signature)
+	 * OP_CHECKSIGVERIFY (sig & pubkey must verify or script fails)
+	 * OP_HASH160 (convert public key to PKH)
+	 * OP_DUP (duplicate PKH)
+	 * <push 20 bytes> <refund PKH> OP_EQUAL (does PKH match refund PKH?)
+	 * OP_IF
+	 * 	OP_DROP (no need for duplicate PKH)
+	 * 	<push 4 bytes> <locktime>
+	 * 	OP_CHECKLOCKTIMEVERIFY (if this passes, leftover stack is <locktime> so script passes)
+	 * OP_ELSE
+	 * 	<push 20 bytes> <redeem PKH> OP_EQUALVERIFY (duplicate PKH must match redeem PKH or script fails)
+	 * 	OP_HASH160 (hash secret)
+	 * 	<push 20 bytes> <hash of secret> OP_EQUAL (do hashes of secrets match? if true, script passes else script fails)
+	 * OP_ENDIF
+	 */
+
+	private static final byte[] redeemScript1 = HashCode.fromString("7dada97614").asBytes(); // OP_TUCK OP_CHECKSIGVERIFY OP_HASH160 OP_DUP push(0x14 bytes)
+	private static final byte[] redeemScript2 = HashCode.fromString("87637504").asBytes(); // OP_EQUAL OP_IF OP_DROP push(0x4 bytes)
+	private static final byte[] redeemScript3 = HashCode.fromString("b16714").asBytes(); // OP_CHECKLOCKTIMEVERIFY OP_ELSE push(0x14 bytes)
+	private static final byte[] redeemScript4 = HashCode.fromString("88a914").asBytes(); // OP_EQUALVERIFY OP_HASH160 push(0x14 bytes)
+	private static final byte[] redeemScript5 = HashCode.fromString("8768").asBytes(); // OP_EQUAL OP_ENDIF
+
+	/**
+	 * Returns redeemScript used for cross-chain trading.
+	 * <p>
+	 * See comments in {@link BitcoinyHTLC} for more details.
+	 * 
+	 * @param refunderPubKeyHash 20-byte HASH160 of P2SH funder's public key, for refunding purposes
+	 * @param lockTime seconds-since-epoch threshold, after which P2SH funder can claim refund
+	 * @param redeemerPubKeyHash 20-byte HASH160 of P2SH redeemer's public key
+	 * @param hashOfSecret 20-byte HASH160 of secret, used by P2SH redeemer to claim funds
+	 */
+	public static byte[] buildScript(byte[] refunderPubKeyHash, int lockTime, byte[] redeemerPubKeyHash, byte[] hashOfSecret) {
+		return Bytes.concat(redeemScript1, refunderPubKeyHash, redeemScript2, BitTwiddling.toLEByteArray((int) (lockTime & 0xffffffffL)),
+				redeemScript3, redeemerPubKeyHash, redeemScript4, hashOfSecret, redeemScript5);
+	}
+
+	/**
+	 * Builds a custom transaction to spend HTLC P2SH.
+	 * 
+	 * @param params blockchain network parameters
+	 * @param amount output amount, should be total of input amounts, less miner fees
+	 * @param spendKey key for signing transaction, and also where funds are 'sent' (output)
+	 * @param fundingOutput output from transaction that funded P2SH address
+	 * @param redeemScriptBytes the redeemScript itself, in byte[] form
+	 * @param lockTime (optional) transaction nLockTime, used in refund scenario
+	 * @param scriptSigBuilder function for building scriptSig using transaction input signature
+	 * @param outputPublicKeyHash PKH used to create P2PKH output
+	 * @return Signed transaction for spending P2SH
+	 */
+	public static Transaction buildP2shTransaction(NetworkParameters params, Coin amount, ECKey spendKey,
+			List<TransactionOutput> fundingOutputs, byte[] redeemScriptBytes,
+			Long lockTime, Function<byte[], Script> scriptSigBuilder, byte[] outputPublicKeyHash) {
+		Transaction transaction = new Transaction(params);
+		transaction.setVersion(2);
+
+		// Output is back to P2SH funder
+		transaction.addOutput(amount, ScriptBuilder.createP2PKHOutputScript(outputPublicKeyHash));
+
+		for (int inputIndex = 0; inputIndex < fundingOutputs.size(); ++inputIndex) {
+			TransactionOutput fundingOutput = fundingOutputs.get(inputIndex);
+
+			// Input (without scriptSig prior to signing)
+			TransactionInput input = new TransactionInput(params, null, redeemScriptBytes, fundingOutput.getOutPointFor());
+			if (lockTime != null)
+				input.setSequenceNumber(LOCKTIME_NO_RBF_SEQUENCE); // Use max-value - 1, so lockTime can be used but not RBF
+			else
+				input.setSequenceNumber(NO_LOCKTIME_NO_RBF_SEQUENCE); // Use max-value, so no lockTime and no RBF
+			transaction.addInput(input);
+		}
+
+		// Set locktime after inputs added but before input signatures are generated
+		if (lockTime != null)
+			transaction.setLockTime(lockTime);
+
+		for (int inputIndex = 0; inputIndex < fundingOutputs.size(); ++inputIndex) {
+			// Generate transaction signature for input
+			final boolean anyoneCanPay = false;
+			TransactionSignature txSig = transaction.calculateSignature(inputIndex, spendKey, redeemScriptBytes, SigHash.ALL, anyoneCanPay);
+
+			// Calculate transaction signature
+			byte[] txSigBytes = txSig.encodeToBitcoin();
+
+			// Build scriptSig using lambda and tx signature
+			Script scriptSig = scriptSigBuilder.apply(txSigBytes);
+
+			// Set input scriptSig
+			transaction.getInput(inputIndex).setScriptSig(scriptSig);
+		}
+
+		return transaction;
+	}
+
+	/**
+	 * Returns signed transaction claiming refund from HTLC P2SH.
+	 * 
+	 * @param params blockchain network parameters
+	 * @param refundAmount refund amount, should be total of input amounts, less miner fees
+	 * @param refundKey key for signing transaction
+	 * @param fundingOutputs outputs from transaction that funded P2SH address
+	 * @param redeemScriptBytes the redeemScript itself, in byte[] form
+	 * @param lockTime transaction nLockTime - must be at least locktime used in redeemScript
+	 * @param receivingAccountInfo public-key-hash used for P2PKH output
+	 * @return Signed transaction for refunding P2SH
+	 */
+	public static Transaction buildRefundTransaction(NetworkParameters params, Coin refundAmount, ECKey refundKey,
+			List<TransactionOutput> fundingOutputs, byte[] redeemScriptBytes, long lockTime, byte[] receivingAccountInfo) {
+		Function<byte[], Script> refundSigScriptBuilder = (txSigBytes) -> {
+			// Build scriptSig with...
+			ScriptBuilder scriptBuilder = new ScriptBuilder();
+
+			// transaction signature
+			scriptBuilder.addChunk(new ScriptChunk(txSigBytes.length, txSigBytes));
+
+			// redeem public key
+			byte[] refundPubKey = refundKey.getPubKey();
+			scriptBuilder.addChunk(new ScriptChunk(refundPubKey.length, refundPubKey));
+
+			// redeem script
+			scriptBuilder.addChunk(new ScriptChunk(ScriptOpCodes.OP_PUSHDATA1, redeemScriptBytes));
+
+			return scriptBuilder.build();
+		};
+
+		// Send funds back to funding address
+		return buildP2shTransaction(params, refundAmount, refundKey, fundingOutputs, redeemScriptBytes, lockTime, refundSigScriptBuilder, receivingAccountInfo);
+	}
+
+	/**
+	 * Returns signed transaction redeeming funds from P2SH address.
+	 * 
+	 * @param params blockchain network parameters
+	 * @param redeemAmount redeem amount, should be total of input amounts, less miner fees
+	 * @param redeemKey key for signing transaction
+	 * @param fundingOutputs outputs from transaction that funded P2SH address
+	 * @param redeemScriptBytes the redeemScript itself, in byte[] form
+	 * @param secret actual 32-byte secret used when building redeemScript
+	 * @param receivingAccountInfo Bitcoin PKH used for output
+	 * @return Signed transaction for redeeming P2SH
+	 */
+	public static Transaction buildRedeemTransaction(NetworkParameters params, Coin redeemAmount, ECKey redeemKey,
+			List<TransactionOutput> fundingOutputs, byte[] redeemScriptBytes, byte[] secret, byte[] receivingAccountInfo) {
+		Function<byte[], Script> redeemSigScriptBuilder = (txSigBytes) -> {
+			// Build scriptSig with...
+			ScriptBuilder scriptBuilder = new ScriptBuilder();
+
+			// secret
+			scriptBuilder.addChunk(new ScriptChunk(secret.length, secret));
+
+			// transaction signature
+			scriptBuilder.addChunk(new ScriptChunk(txSigBytes.length, txSigBytes));
+
+			// redeem public key
+			byte[] redeemPubKey = redeemKey.getPubKey();
+			scriptBuilder.addChunk(new ScriptChunk(redeemPubKey.length, redeemPubKey));
+
+			// redeem script
+			scriptBuilder.addChunk(new ScriptChunk(ScriptOpCodes.OP_PUSHDATA1, redeemScriptBytes));
+
+			return scriptBuilder.build();
+		};
+
+		return buildP2shTransaction(params, redeemAmount, redeemKey, fundingOutputs, redeemScriptBytes, null, redeemSigScriptBuilder, receivingAccountInfo);
+	}
+
+	/**
+	 * Returns 'secret', if any, given HTLC's P2SH address.
+	 * <p>
+	 * @throws ForeignBlockchainException
+	 */
+	public static byte[] findHtlcSecret(Bitcoiny bitcoiny, String p2shAddress) throws ForeignBlockchainException {
+		NetworkParameters params = bitcoiny.getNetworkParameters();
+		String compoundKey = String.format("%s-%s-%d", params.getId(), p2shAddress, System.currentTimeMillis() / CACHE_TIMEOUT);
+
+		byte[] secret = SECRET_CACHE.getOrDefault(compoundKey, NO_SECRET_CACHE_ENTRY);
+		if (secret != NO_SECRET_CACHE_ENTRY)
+			return secret;
+
+		List<byte[]> rawTransactions = bitcoiny.getAddressTransactions(p2shAddress);
+
+		for (byte[] rawTransaction : rawTransactions) {
+			Transaction transaction = new Transaction(params, rawTransaction);
+
+			// Cycle through inputs, looking for one that spends our HTLC
+			for (TransactionInput input : transaction.getInputs()) {
+				Script scriptSig = input.getScriptSig();
+				List<ScriptChunk> scriptChunks = scriptSig.getChunks();
+
+				// Expected number of script chunks for redeem. Refund might not have the same number.
+				int expectedChunkCount = 1 /*secret*/ + 1 /*sig*/ + 1 /*pubkey*/ + 1 /*redeemScript*/;
+				if (scriptChunks.size() != expectedChunkCount)
+					continue;
+
+				// We're expecting last chunk to contain the actual redeemScript
+				ScriptChunk lastChunk = scriptChunks.get(scriptChunks.size() - 1);
+				byte[] redeemScriptBytes = lastChunk.data;
+
+				// If non-push scripts, redeemScript will be null
+				if (redeemScriptBytes == null)
+					continue;
+
+				byte[] redeemScriptHash = Crypto.hash160(redeemScriptBytes);
+				Address inputAddress = LegacyAddress.fromScriptHash(params, redeemScriptHash);
+
+				if (!inputAddress.toString().equals(p2shAddress))
+					// Input isn't spending our HTLC
+					continue;
+
+				secret = scriptChunks.get(0).data;
+				if (secret.length != BitcoinyHTLC.SECRET_LENGTH)
+					continue;
+
+				// Cache secret for a while
+				SECRET_CACHE.put(compoundKey, secret);
+
+				return secret;
+			}
+		}
+
+		// Cache negative result
+		SECRET_CACHE.put(compoundKey, null);
+
+		return null;
+	}
+
+	/**
+	 * Returns HTLC status, given P2SH address and expected redeem/refund amount
+	 * <p>
+	 * @throws ForeignBlockchainException if error occurs
+	 */
+	public static Status determineHtlcStatus(BitcoinyBlockchainProvider blockchain, String p2shAddress, long minimumAmount) throws ForeignBlockchainException {
+		String compoundKey = String.format("%s-%s-%d", blockchain.getNetId(), p2shAddress, System.currentTimeMillis() / CACHE_TIMEOUT);
+
+		Status cachedStatus = STATUS_CACHE.getOrDefault(compoundKey, null);
+		if (cachedStatus != null)
+			return cachedStatus;
+
+		byte[] ourScriptPubKey = addressToScriptPubKey(p2shAddress);
+		List<TransactionHash> transactionHashes = blockchain.getAddressTransactions(ourScriptPubKey, BitcoinyBlockchainProvider.INCLUDE_UNCONFIRMED);
+
+		// Sort by confirmed first, followed by ascending height
+		transactionHashes.sort(TransactionHash.CONFIRMED_FIRST.thenComparing(TransactionHash::getHeight));
+
+		// Transaction cache
+		Map<String, BitcoinyTransaction> transactionsByHash = new HashMap<>();
+		// HASH160(redeem script) for this p2shAddress
+		byte[] ourRedeemScriptHash = addressToRedeemScriptHash(p2shAddress);
+
+		// Check for spends first, caching full transaction info as we progress just in case we don't return in this loop
+		for (TransactionHash transactionInfo : transactionHashes) {
+			BitcoinyTransaction bitcoinyTransaction = blockchain.getTransaction(transactionInfo.txHash);
+
+			// Cache for possible later reuse
+			transactionsByHash.put(transactionInfo.txHash, bitcoinyTransaction);
+
+			// Acceptable funding is one transaction output, so we're expecting only one input
+			if (bitcoinyTransaction.inputs.size() != 1)
+				// Wrong number of inputs
+				continue;
+
+			String scriptSig = bitcoinyTransaction.inputs.get(0).scriptSig;
+
+			List<byte[]> scriptSigChunks = extractScriptSigChunks(HashCode.fromString(scriptSig).asBytes());
+			if (scriptSigChunks.size() < 3 || scriptSigChunks.size() > 4)
+				// Not valid chunks for our form of HTLC
+				continue;
+
+			// Last chunk is redeem script
+			byte[] redeemScriptBytes = scriptSigChunks.get(scriptSigChunks.size() - 1);
+			byte[] redeemScriptHash = Crypto.hash160(redeemScriptBytes);
+			if (!Arrays.equals(redeemScriptHash, ourRedeemScriptHash))
+				// Not spending our specific HTLC redeem script
+				continue;
+
+			if (scriptSigChunks.size() == 4)
+				// If we have 4 chunks, then secret is present, hence redeem
+				cachedStatus = transactionInfo.height == 0 ? Status.REDEEM_IN_PROGRESS : Status.REDEEMED;
+			else
+				cachedStatus = transactionInfo.height == 0 ? Status.REFUND_IN_PROGRESS : Status.REFUNDED;
+
+			STATUS_CACHE.put(compoundKey, cachedStatus);
+			return cachedStatus;
+		}
+
+		String ourScriptPubKeyHex = HashCode.fromBytes(ourScriptPubKey).toString();
+
+		// Check for funding
+		for (TransactionHash transactionInfo : transactionHashes) {
+			BitcoinyTransaction bitcoinyTransaction = transactionsByHash.get(transactionInfo.txHash);
+			if (bitcoinyTransaction == null)
+				// Should be present in map!
+				throw new ForeignBlockchainException("Cached Bitcoin transaction now missing?");
+
+			// Check outputs for our specific P2SH
+			for (BitcoinyTransaction.Output output : bitcoinyTransaction.outputs) {
+				// Check amount
+				if (output.value < minimumAmount)
+					// Output amount too small (not taking fees into account)
+					continue;
+
+				String scriptPubKeyHex = output.scriptPubKey;
+				if (!scriptPubKeyHex.equals(ourScriptPubKeyHex))
+					// Not funding our specific P2SH
+					continue;
+
+				cachedStatus = transactionInfo.height == 0 ? Status.FUNDING_IN_PROGRESS : Status.FUNDED;
+				STATUS_CACHE.put(compoundKey, cachedStatus);
+				return cachedStatus;
+			}
+		}
+
+		cachedStatus = Status.UNFUNDED;
+		STATUS_CACHE.put(compoundKey, cachedStatus);
+		return cachedStatus;
+	}
+
+	private static List<byte[]> extractScriptSigChunks(byte[] scriptSigBytes) {
+		List<byte[]> chunks = new ArrayList<>();
+
+		int offset = 0;
+		int previousOffset = 0;
+		while (offset < scriptSigBytes.length) {
+			byte pushOp = scriptSigBytes[offset++];
+
+			if (pushOp < 0 || pushOp > 0x4c)
+				// Unacceptable OP
+				return Collections.emptyList();
+
+			// Special treatment for OP_PUSHDATA1
+			if (pushOp == 0x4c) {
+				if (offset >= scriptSigBytes.length)
+					// Run out of scriptSig bytes?
+					return Collections.emptyList();
+
+				pushOp = scriptSigBytes[offset++];
+			}
+
+			previousOffset = offset;
+			offset += Byte.toUnsignedInt(pushOp);
+
+			byte[] chunk = Arrays.copyOfRange(scriptSigBytes, previousOffset, offset);
+			chunks.add(chunk);
+		}
+
+		return chunks;
+	}
+
+	private static byte[] addressToScriptPubKey(String p2shAddress) {
+		// We want the HASH160 part of the P2SH address
+		byte[] p2shAddressBytes = Base58.decode(p2shAddress);
+
+		byte[] scriptPubKey = new byte[1 + 1 + 20 + 1];
+		scriptPubKey[0x00] = (byte) 0xa9; /* OP_HASH160 */
+		scriptPubKey[0x01] = (byte) 0x14; /* PUSH 0x14 bytes */
+		System.arraycopy(p2shAddressBytes, 1, scriptPubKey, 2, 0x14);
+		scriptPubKey[0x16] = (byte) 0x87; /* OP_EQUAL */
+
+		return scriptPubKey;
+	}
+
+	private static byte[] addressToRedeemScriptHash(String p2shAddress) {
+		// We want the HASH160 part of the P2SH address
+		byte[] p2shAddressBytes = Base58.decode(p2shAddress);
+
+		return Arrays.copyOfRange(p2shAddressBytes, 1, 1 + 20);
+	}
+
+}