Script updates to support add/remove dev group admins

Proof of concept: speed up QORT buying

TestNets.md

@@ -52,14 +52,13 @@
 
 ## Single-node testnet
 
-A single-node testnet is possible with code modifications, for basic testing, or to more easily start a new testnet.
-To do so, follow these steps:
-- Comment out the `if (mintedLastBlock) { }` conditional in BlockMinter.java
-- Comment out the `minBlockchainPeers` validation in Settings.validate()
-- Set `minBlockchainPeers` to 0 in settings.json
-- Set `Synchronizer.RECOVERY_MODE_TIMEOUT` to `0`
-- All other steps should remain the same. Only a single reward share key is needed.
-- Remember to put these values back after introducing other nodes
+A single-node testnet is possible with an additional settings, or to more easily start a new testnet.
+Just add this setting:
+```
+"singleNodeTestnet": true
+```
+This will automatically allow multiple consecutive blocks to be minted, as well as setting minBlockchainPeers to 0.
+Remember to put these values back after introducing other nodes
 
 ## Fixed network
 
@@ -93,3 +92,32 @@ Your options are:
 - `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
 
+## Example settings-test.json
+```
+{
+  "isTestNet": true,
+  "bitcoinNet": "TEST3",
+  "repositoryPath": "db-testnet",
+  "blockchainConfig": "testchain.json",
+  "minBlockchainPeers": 1,
+  "apiDocumentationEnabled": true,
+  "apiRestricted": false,
+  "bootstrap": false,
+  "maxPeerConnectionTime": 999999999,
+  "localAuthBypassEnabled": true,
+  "singleNodeTestnet": true,
+  "recoveryModeTimeout": 0
+}
+```
+
+## Quick start
+Here are some steps to quickly get a single node testnet up and running with a generic minting account:
+1. Start with template `settings-test.json`, and create a `testchain.json` based on mainnet's blockchain.json (or obtain one from Qortal developers). These should be in the same directory as the jar.
+2. Make sure feature triggers and other timestamp/height activations are correctly set. Generally these would be `0` so that they are enabled from the start.
+3. Set a recent genesis `timestamp` in testchain.json, and add this reward share entry:
+`{ "type": "REWARD_SHARE", "minterPublicKey": "DwcUnhxjamqppgfXCLgbYRx8H9XFPUc2qYRy3CEvQWEw", "recipient": "QbTDMss7NtRxxQaSqBZtSLSNdSYgvGaqFf", "rewardSharePublicKey": "CRvQXxFfUMfr4q3o1PcUZPA4aPCiubBsXkk47GzRo754", "sharePercent": 0 },`
+4. Start the node, passing in settings-test.json, e.g: `java -jar qortal.jar settings-test.json`
+5. Once started, add the corresponding minting key to the node:
+`curl -X POST "http://localhost:62391/admin/mintingaccounts" -d "F48mYJycFgRdqtc58kiovwbcJgVukjzRE4qRRtRsK9ix"`
+6. Alternatively you can use your own minting account instead of the generic one above.
+7. After a short while, blocks should be minted from the genesis timestamp until the current time.

WindowsInstaller/Qortal.aip

@@ -17,10 +17,10 @@
     <ROW Property="Manufacturer" Value="Qortal"/>
     <ROW Property="MsiLogging" MultiBuildValue="DefaultBuild:vp"/>
     <ROW Property="NTP_GOOD" Value="false"/>
-    <ROW Property="ProductCode" Value="1033:{E5597539-098E-4BA6-99DF-4D22018BC0D3} 1049:{2B5E55A2-142A-4BED-B3B9-5657162282B7} 2052:{6F19171F-4743-4127-B191-AAFA3FA885D2} 2057:{A1B3108D-EC5D-47A1-AEE4-DBD956E682FB} " Type="16"/>
+    <ROW Property="ProductCode" Value="1033:{ADE0C9E9-F7D9-4829-8626-8571C735C4D7} 1049:{F5230C0A-9D8C-4C70-AC72-17CECC8273B8} 2052:{D5A0760C-E5B3-4C4C-97B0-81CC445F07B9} 2057:{EF5EF0BE-0B00-4F5C-A2A0-DF2CB82FF20D} " Type="16"/>
     <ROW Property="ProductLanguage" Value="2057"/>
     <ROW Property="ProductName" Value="Qortal"/>
-    <ROW Property="ProductVersion" Value="3.4.3" Type="32"/>
+    <ROW Property="ProductVersion" Value="3.6.3" Type="32"/>
     <ROW Property="RECONFIG_NTP" Value="true"/>
     <ROW Property="REMOVE_BLOCKCHAIN" Value="YES" Type="4"/>
     <ROW Property="REPAIR_BLOCKCHAIN" Value="YES" Type="4"/>
@@ -212,7 +212,7 @@
     <ROW Component="ADDITIONAL_LICENSE_INFO_71" ComponentId="{12A3ADBE-BB7A-496C-8869-410681E6232F}" Directory_="jdk.zipfs_Dir" Attributes="0" KeyPath="ADDITIONAL_LICENSE_INFO_71" Type="0"/>
     <ROW Component="ADDITIONAL_LICENSE_INFO_8" ComponentId="{D53AD95E-CF96-4999-80FC-5812277A7456}" Directory_="java.naming_Dir" Attributes="0" KeyPath="ADDITIONAL_LICENSE_INFO_8" Type="0"/>
     <ROW Component="ADDITIONAL_LICENSE_INFO_9" ComponentId="{6B7EA9B0-5D17-47A8-B78C-FACE86D15E01}" Directory_="java.net.http_Dir" Attributes="0" KeyPath="ADDITIONAL_LICENSE_INFO_9" Type="0"/>
-    <ROW Component="AI_CustomARPName" ComponentId="{F17029E8-CCC4-456D-B4AC-1854C81C46B6}" Directory_="APPDIR" Attributes="260" KeyPath="DisplayName" Options="1"/>
+    <ROW Component="AI_CustomARPName" ComponentId="{F4F774B9-18DC-4740-9552-EA16B98801C9}" Directory_="APPDIR" Attributes="260" KeyPath="DisplayName" Options="1"/>
     <ROW Component="AI_ExePath" ComponentId="{3644948D-AE0B-41BB-9FAF-A79E70490A08}" Directory_="APPDIR" Attributes="260" KeyPath="AI_ExePath"/>
     <ROW Component="APPDIR" ComponentId="{680DFDDE-3FB4-47A5-8FF5-934F576C6F91}" Directory_="APPDIR" Attributes="0"/>
     <ROW Component="AccessBridgeCallbacks.h" ComponentId="{288055D1-1062-47A3-AA44-5601B4E38AED}" Directory_="bridge_Dir" Attributes="0" KeyPath="AccessBridgeCallbacks.h" Type="0"/>
@@ -1173,7 +1173,7 @@
     <ROW Action="AI_STORE_LOCATION" Type="51" Source="ARPINSTALLLOCATION" Target="[APPDIR]"/>
     <ROW Action="AI_SetPermissions" Type="11265" Source="userAccounts.dll" Target="OnSetPermissions" WithoutSeq="true"/>
     <ROW Action="CustomizeLog4j2PropertiesScript" Type="3109" Target="Script Text" TargetUnformatted="var actionData = Session.Property(&quot;CustomActionData&quot;);&#13;&#10;var actionDataArray = actionData.split(&quot;|&quot;);&#13;&#10;var appDir = actionDataArray[0];&#13;&#10;var dataFolder = actionDataArray[1] + actionDataArray[2] + &quot;\\&quot;;&#13;&#10;&#13;&#10;var ForReading = 1, ForWriting = 2, ForAppending = 8;&#13;&#10;var fso = new ActiveXObject(&quot;Scripting.FileSystemObject&quot;);&#13;&#10;&#13;&#10;// Make copy&#13;&#10;fso.CopyFile(appDir + &quot;log4j2.properties&quot;, appDir + &quot;log4j2-orig.properties&quot;, true); // overwrite&#13;&#10;&#13;&#10;// Rewrite %AppDir%\log4j2.properties to update logfile storage path&#13;&#10;var fin = fso.OpenTextFile(appDir + &quot;log4j2-orig.properties&quot;, ForReading, false); // no create&#13;&#10;var fout = fso.OpenTextFile(appDir + &quot;log4j2.properties&quot;, ForWriting, true); // can create&#13;&#10;&#13;&#10;// Copy lines with rewriting where necessary&#13;&#10;while( !fin.AtEndOfStream ) {&#13;&#10;&#9;var line = fin.ReadLine();&#13;&#10;&#13;&#10;&#9;var start = line.indexOf(&quot;property.dirname&quot;);&#13;&#10;&#9;if (start &gt; 0) {&#13;&#10;&#9;&#9;// line: # property.dirname = ...appdata...&#13;&#10;&#9;&#9;// uncomment/replace this line for Windows&#13;&#10;&#9;&#9;fout.WriteLine( &quot;property.dirname = &quot; + dataFolder.split(&apos;\\&apos;).join(&apos;\\\\&apos;) );&#13;&#10;&#9;} else {&#13;&#10;&#9;&#9;// not found - output verbatim&#13;&#10;&#9;&#9;fout.WriteLine( line );&#13;&#10;&#9;}&#13;&#10;}&#13;&#10;&#13;&#10;fin.Close();&#13;&#10;fout.Close();&#13;&#10;" AdditionalSeq="AI_DATA_SETTER_4"/>
-    <ROW Action="CustomizeSettingsJsonScript" Type="3109" Target="Script Text" TargetUnformatted="var actionData = Session.Property(&quot;CustomActionData&quot;);&#13;&#10;var actionDataArray = actionData.split(&quot;|&quot;);&#13;&#10;var appDir = actionDataArray[0];&#13;&#10;var dataFolder = actionDataArray[1] + actionDataArray[2] + &quot;\\&quot;;&#13;&#10;&#13;&#10;var ForReading = 1, ForWriting = 2, ForAppending = 8;&#13;&#10;var fso = new ActiveXObject(&quot;Scripting.FileSystemObject&quot;);&#13;&#10;&#13;&#10;// Create basic %APPDIR%\settings.json with path to real settings.json in dataFolder&#13;&#10;var fts = fso.OpenTextFile(appDir + &quot;settings.json&quot;, ForWriting, true);&#13;&#10;&#13;&#10;fts.WriteLine( &quot;{&quot; );&#13;&#10;// We need to escape Windows path backslashes to keep JSON valid&#13;&#10;fts.WriteLine( &quot;  \&quot;userPath\&quot;: \&quot;&quot; + dataFolder.split(&apos;\\&apos;).join(&apos;\\\\&apos;) + &quot;\&quot;&quot; );&#13;&#10;fts.WriteLine( &quot;}&quot; );&#13;&#10;&#13;&#10;fts.Close();&#13;&#10;&#13;&#10;// Make copy&#13;&#10;fso.CopyFile(dataFolder + &quot;settings.json&quot;, dataFolder + &quot;settings-orig.json&quot;, true); // overwrite&#13;&#10;&#13;&#10;// Rewrite settings.json to update repository path&#13;&#10;var fin = fso.OpenTextFile(dataFolder + &quot;settings-orig.json&quot;, ForReading, false);&#13;&#10;var fout = fso.OpenTextFile(dataFolder + &quot;settings.json&quot;, ForWriting, true);&#13;&#10;&#13;&#10;// First line should contain opening brace&#13;&#10;fout.WriteLine( fin.ReadLine() );&#13;&#10;&#13;&#10;// Append our entries&#13;&#10;fout.WriteLine( &quot;  \&quot;repositoryPath\&quot;: \&quot;&quot; + dataFolder.split(&apos;\\&apos;).join(&apos;\\\\&apos;) + &quot;db\&quot;,&quot; );&#13;&#10;fout.WriteLine( &quot;  \&quot;dataPath\&quot;: \&quot;&quot; + dataFolder.split(&apos;\\&apos;).join(&apos;\\\\&apos;) + &quot;data\&quot;,&quot; );&#13;&#10;&#13;&#10;// copy rest of settings&#13;&#10;while( !fin.AtEndOfStream ) {&#13;&#10;&#9;fout.WriteLine( fin.ReadLine() );&#13;&#10;}&#13;&#10;&#13;&#10;fin.Close();&#13;&#10;fout.Close();&#13;&#10;" AdditionalSeq="AI_DATA_SETTER_3"/>
+    <ROW Action="CustomizeSettingsJsonScript" Type="3109" Target="Script Text" TargetUnformatted="var actionData = Session.Property(&quot;CustomActionData&quot;);&#13;&#10;var actionDataArray = actionData.split(&quot;|&quot;);&#13;&#10;var appDir = actionDataArray[0];&#13;&#10;var dataFolder = actionDataArray[1] + actionDataArray[2] + &quot;\\&quot;;&#13;&#10;&#13;&#10;var ForReading = 1, ForWriting = 2, ForAppending = 8;&#13;&#10;var fso = new ActiveXObject(&quot;Scripting.FileSystemObject&quot;);&#13;&#10;&#13;&#10;// Create basic %APPDIR%\settings.json with path to real settings.json in dataFolder&#13;&#10;var fts = fso.OpenTextFile(appDir + &quot;settings.json&quot;, ForWriting, true);&#13;&#10;&#13;&#10;fts.WriteLine( &quot;{&quot; );&#13;&#10;// We need to escape Windows path backslashes to keep JSON valid&#13;&#10;fts.WriteLine( &quot;  \&quot;userPath\&quot;: \&quot;&quot; + dataFolder.split(&apos;\\&apos;).join(&apos;\\\\&apos;) + &quot;\&quot;&quot; );&#13;&#10;fts.WriteLine( &quot;}&quot; );&#13;&#10;&#13;&#10;fts.Close();&#13;&#10;&#13;&#10;// Make copy&#13;&#10;fso.CopyFile(dataFolder + &quot;settings.json&quot;, dataFolder + &quot;settings-orig.json&quot;, true); // overwrite&#13;&#10;&#13;&#10;// Rewrite settings.json to update repository path&#13;&#10;var fin = fso.OpenTextFile(dataFolder + &quot;settings-orig.json&quot;, ForReading, false);&#13;&#10;var fout = fso.OpenTextFile(dataFolder + &quot;settings.json&quot;, ForWriting, true);&#13;&#10;&#13;&#10;// First line should contain opening brace&#13;&#10;fout.WriteLine( fin.ReadLine() );&#13;&#10;&#13;&#10;// Append our entries&#13;&#10;fout.WriteLine( &quot;  \&quot;repositoryPath\&quot;: \&quot;&quot; + dataFolder.split(&apos;\\&apos;).join(&apos;\\\\&apos;) + &quot;db\&quot;,&quot; );&#13;&#10;fout.WriteLine( &quot;  \&quot;dataPath\&quot;: \&quot;&quot; + dataFolder.split(&apos;\\&apos;).join(&apos;\\\\&apos;) + &quot;data\&quot;,&quot; );&#13;&#10;fout.WriteLine( &quot;  \&quot;walletsPath\&quot;: \&quot;&quot; + dataFolder.split(&apos;\\&apos;).join(&apos;\\\\&apos;) + &quot;wallets\&quot;,&quot; );&#13;&#10;fout.WriteLine( &quot;  \&quot;listsPath\&quot;: \&quot;&quot; + dataFolder.split(&apos;\\&apos;).join(&apos;\\\\&apos;) + &quot;lists\&quot;,&quot; );&#13;&#10;&#13;&#10;// copy rest of settings&#13;&#10;while( !fin.AtEndOfStream ) {&#13;&#10;&#9;fout.WriteLine( fin.ReadLine() );&#13;&#10;}&#13;&#10;&#13;&#10;fin.Close();&#13;&#10;fout.Close();&#13;&#10;" AdditionalSeq="AI_DATA_SETTER_3"/>
     <ROW Action="DetectRunningProcess" Type="1" Source="aicustact.dll" Target="DetectProcess" Options="3" AdditionalSeq="AI_DATA_SETTER_8"/>
     <ROW Action="DetectW32Time" Type="1" Source="aicustact.dll" Target="DetectService" Options="3" AdditionalSeq="AI_DATA_SETTER_11"/>
     <ROW Action="NTP_config" Type="3090" Source="ntpcfg.bat"/>

lib/org/ciyam/AT/1.4.0/AT-1.4.0.pom

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>org.ciyam</groupId>
+  <artifactId>AT</artifactId>
+  <version>1.4.0</version>
+  <description>POM was created from install:install-file</description>
+</project>

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

@@ -3,14 +3,15 @@
   <groupId>org.ciyam</groupId>
   <artifactId>AT</artifactId>
   <versioning>
-    <release>1.3.8</release>
+    <release>1.4.0</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>
+      <version>1.4.0</version>
     </versions>
-    <lastUpdated>20200925114415</lastUpdated>
+    <lastUpdated>20221105114346</lastUpdated>
   </versioning>
 </metadata>

pom.xml

@@ -3,7 +3,7 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>org.qortal</groupId>
 	<artifactId>qortal</artifactId>
-	<version>3.6.0</version>
+	<version>3.6.4</version>
 	<packaging>jar</packaging>
 	<properties>
 		<skipTests>true</skipTests>
@@ -11,7 +11,7 @@
 		<bitcoinj.version>0.15.10</bitcoinj.version>
 		<bouncycastle.version>1.69</bouncycastle.version>
 		<build.timestamp>${maven.build.timestamp}</build.timestamp>
-		<ciyam-at.version>1.3.8</ciyam-at.version>
+		<ciyam-at.version>1.4.0</ciyam-at.version>
 		<commons-net.version>3.6</commons-net.version>
 		<commons-text.version>1.8</commons-text.version>
 		<commons-io.version>2.6</commons-io.version>

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

@@ -1,7 +1,7 @@
 package org.qortal.api.model;
 
 import io.swagger.v3.oas.annotations.media.Schema;
-import org.qortal.data.network.PeerChainTipData;
+import org.qortal.data.block.BlockSummaryData;
 import org.qortal.data.network.PeerData;
 import org.qortal.network.Handshake;
 import org.qortal.network.Peer;
@@ -63,11 +63,11 @@ public class ConnectedPeer {
             this.age = "connecting...";
         }
 
-        PeerChainTipData peerChainTipData = peer.getChainTipData();
+        BlockSummaryData peerChainTipData = peer.getChainTipData();
         if (peerChainTipData != null) {
-            this.lastHeight = peerChainTipData.getLastHeight();
-            this.lastBlockSignature = peerChainTipData.getLastBlockSignature();
-            this.lastBlockTimestamp = peerChainTipData.getLastBlockTimestamp();
+            this.lastHeight = peerChainTipData.getHeight();
+            this.lastBlockSignature = peerChainTipData.getSignature();
+            this.lastBlockTimestamp = peerChainTipData.getTimestamp();
         }
     }
 

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

@@ -205,6 +205,10 @@ public class AddressesResource {
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			List<OnlineAccountLevel> onlineAccountLevels = new ArrayList<>();
 
+			// Prepopulate all levels
+			for (int i=0; i<=10; i++)
+				onlineAccountLevels.add(new OnlineAccountLevel(i, 0));
+
 			for (OnlineAccountData onlineAccountData : onlineAccounts) {
 				try {
 					final int minterLevel = Account.getRewardShareEffectiveMintingLevelIncludingLevelZero(repository, onlineAccountData.getPublicKey());

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

@@ -69,6 +69,7 @@ public class ChatResource {
 	public List<ChatMessage> searchChat(@QueryParam("before") Long before, @QueryParam("after") Long after,
 			@QueryParam("txGroupId") Integer txGroupId,
 			@QueryParam("involving") List<String> involvingAddresses,
+			@QueryParam("reference") String reference,
 			@Parameter(ref = "limit") @QueryParam("limit") Integer limit,
 			@Parameter(ref = "offset") @QueryParam("offset") Integer offset,
 			@Parameter(ref = "reverse") @QueryParam("reverse") Boolean reverse) {
@@ -87,11 +88,16 @@ public class ChatResource {
 		if (after != null && after < 1500000000000L)
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 
+		byte[] referenceBytes = null;
+		if (reference != null)
+			referenceBytes = Base58.decode(reference);
+
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			return repository.getChatRepository().getMessagesMatchingCriteria(
 					before,
 					after,
 					txGroupId,
+					referenceBytes,
 					involvingAddresses,
 					limit, offset, reverse);
 		} catch (DataException e) {

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

@@ -46,6 +46,7 @@ public class ChatMessagesWebSocket extends ApiWebSocket {
 						null,
 						txGroupId,
 						null,
+						null,
 						null, null, null);
 
 				sendMessages(session, chatMessages);
@@ -72,6 +73,7 @@ public class ChatMessagesWebSocket extends ApiWebSocket {
 					null,
 					null,
 					null,
+					null,
 					involvingAddresses,
 					null, null, null);
 

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

@@ -1,16 +1,18 @@
 package org.qortal.arbitrary.misc;
 
+import org.apache.commons.io.FilenameUtils;
 import org.json.JSONObject;
 import org.qortal.arbitrary.ArbitraryDataRenderer;
 import org.qortal.transaction.Transaction;
 import org.qortal.utils.FilesystemUtils;
 
+import java.io.File;
 import java.io.IOException;
 import java.nio.file.Path;
 import java.nio.file.Paths;
-import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 
 import static java.util.Arrays.stream;
 import static java.util.stream.Collectors.toMap;
@@ -38,6 +40,7 @@ public enum Service {
     GIT_REPOSITORY(300, false, null, null),
     IMAGE(400, true, 10*1024*1024L, null),
     THUMBNAIL(410, true, 500*1024L, null),
+    QCHAT_IMAGE(420, true, 500*1024L, null),
     VIDEO(500, false, null, null),
     AUDIO(600, false, null, null),
     BLOG(700, false, null, null),
@@ -48,7 +51,30 @@ public enum Service {
     PLAYLIST(910, true, null, null),
     APP(1000, false, null, null),
     METADATA(1100, false, null, null),
-    QORTAL_METADATA(1111, true, 10*1024L, Arrays.asList("title", "description", "tags"));
+    GIF_REPOSITORY(1200, true, 25*1024*1024L, null) {
+        @Override
+        public ValidationResult validate(Path path) {
+            // Custom validation function to require .gif files only, and at least 1
+            int gifCount = 0;
+            File[] files = path.toFile().listFiles();
+            if (files != null) {
+                for (File file : files) {
+                    if (file.isDirectory()) {
+                        return ValidationResult.DIRECTORIES_NOT_ALLOWED;
+                    }
+                    String extension = FilenameUtils.getExtension(file.getName()).toLowerCase();
+                    if (!Objects.equals(extension, "gif")) {
+                        return ValidationResult.INVALID_FILE_EXTENSION;
+                    }
+                    gifCount++;
+                }
+            }
+            if (gifCount == 0) {
+                return ValidationResult.MISSING_DATA;
+            }
+            return ValidationResult.OK;
+        }
+    };
 
     public final int value;
     private final boolean requiresValidation;
@@ -114,7 +140,10 @@ public enum Service {
         OK(1),
         MISSING_KEYS(2),
         EXCEEDS_SIZE_LIMIT(3),
-        MISSING_INDEX_FILE(4);
+        MISSING_INDEX_FILE(4),
+        DIRECTORIES_NOT_ALLOWED(5),
+        INVALID_FILE_EXTENSION(6),
+        MISSING_DATA(7);
 
         public final int value;
 

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

@@ -366,18 +366,14 @@ public class Block {
 		long timestamp = calcTimestamp(parentBlockData, minter.getPublicKey(), minterLevel);
 		long onlineAccountsTimestamp = OnlineAccountsManager.getCurrentOnlineAccountTimestamp();
 
-		// Fetch our list of online accounts
+		// Fetch our list of online accounts, removing any that are missing a nonce
 		List<OnlineAccountData> onlineAccounts = OnlineAccountsManager.getInstance().getOnlineAccounts(onlineAccountsTimestamp);
+		onlineAccounts.removeIf(a -> a.getNonce() == null || a.getNonce() < 0);
 		if (onlineAccounts.isEmpty()) {
-			LOGGER.error("No online accounts - not even our own?");
+			LOGGER.debug("No online accounts - not even our own?");
 			return null;
 		}
 
-		// If mempow is active, remove any legacy accounts that are missing a nonce
-		if (timestamp >= BlockChain.getInstance().getOnlineAccountsMemoryPoWTimestamp()) {
-			onlineAccounts.removeIf(a -> a.getNonce() == null || a.getNonce() < 0);
-		}
-
 		// Load sorted list of reward share public keys into memory, so that the indexes can be obtained.
 		// This is up to 100x faster than querying each index separately. For 4150 reward share keys, it
 		// was taking around 5000ms to query individually, vs 50ms using this approach.
@@ -411,29 +407,27 @@ public class Block {
 		// Aggregated, single signature
 		byte[] onlineAccountsSignatures = Qortal25519Extras.aggregateSignatures(signaturesToAggregate);
 
-		// Add nonces to the end of the online accounts signatures if mempow is active
-		if (timestamp >= BlockChain.getInstance().getOnlineAccountsMemoryPoWTimestamp()) {
-			try {
-				// Create ordered list of nonce values
-				List<Integer> nonces = new ArrayList<>();
-				for (int i = 0; i < onlineAccountsCount; ++i) {
-					Integer accountIndex = accountIndexes.get(i);
-					OnlineAccountData onlineAccountData = indexedOnlineAccounts.get(accountIndex);
-					nonces.add(onlineAccountData.getNonce());
-				}
-
-				// Encode the nonces to a byte array
-				byte[] encodedNonces = BlockTransformer.encodeOnlineAccountNonces(nonces);
-
-				// Append the encoded nonces to the encoded online account signatures
-				ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
-				outputStream.write(onlineAccountsSignatures);
-				outputStream.write(encodedNonces);
-				onlineAccountsSignatures = outputStream.toByteArray();
-			}
-			catch (TransformationException | IOException e) {
-				return null;
+		// Add nonces to the end of the online accounts signatures
+		try {
+			// Create ordered list of nonce values
+			List<Integer> nonces = new ArrayList<>();
+			for (int i = 0; i < onlineAccountsCount; ++i) {
+				Integer accountIndex = accountIndexes.get(i);
+				OnlineAccountData onlineAccountData = indexedOnlineAccounts.get(accountIndex);
+				nonces.add(onlineAccountData.getNonce());
 			}
+
+			// Encode the nonces to a byte array
+			byte[] encodedNonces = BlockTransformer.encodeOnlineAccountNonces(nonces);
+
+			// Append the encoded nonces to the encoded online account signatures
+			ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+			outputStream.write(onlineAccountsSignatures);
+			outputStream.write(encodedNonces);
+			onlineAccountsSignatures = outputStream.toByteArray();
+		}
+		catch (TransformationException | IOException e) {
+			return null;
 		}
 
 		byte[] minterSignature = minter.sign(BlockTransformer.getBytesForMinterSignature(parentBlockData,
@@ -1046,14 +1040,9 @@ public class Block {
 		final int signaturesLength = Transformer.SIGNATURE_LENGTH;
 		final int noncesLength = onlineRewardShares.size() * Transformer.INT_LENGTH;
 
-		if (this.blockData.getTimestamp() >= BlockChain.getInstance().getOnlineAccountsMemoryPoWTimestamp()) {
-			// We expect nonces to be appended to the online accounts signatures
-			if (this.blockData.getOnlineAccountsSignatures().length != signaturesLength + noncesLength)
-				return ValidationResult.ONLINE_ACCOUNT_SIGNATURES_MALFORMED;
-		} else {
-			if (this.blockData.getOnlineAccountsSignatures().length != signaturesLength)
-				return ValidationResult.ONLINE_ACCOUNT_SIGNATURES_MALFORMED;
-		}
+		// We expect nonces to be appended to the online accounts signatures
+		if (this.blockData.getOnlineAccountsSignatures().length != signaturesLength + noncesLength)
+			return ValidationResult.ONLINE_ACCOUNT_SIGNATURES_MALFORMED;
 
 		// Check signatures
 		long onlineTimestamp = this.blockData.getOnlineAccountsTimestamp();
@@ -1062,32 +1051,33 @@ public class Block {
 		byte[] encodedOnlineAccountSignatures = this.blockData.getOnlineAccountsSignatures();
 
 		// Split online account signatures into signature(s) + nonces, then validate the nonces
-		if (this.blockData.getTimestamp() >= BlockChain.getInstance().getOnlineAccountsMemoryPoWTimestamp()) {
-			byte[] extractedSignatures = BlockTransformer.extract(encodedOnlineAccountSignatures, 0, signaturesLength);
-			byte[] extractedNonces = BlockTransformer.extract(encodedOnlineAccountSignatures, signaturesLength, onlineRewardShares.size() * Transformer.INT_LENGTH);
-			encodedOnlineAccountSignatures = extractedSignatures;
+		byte[] extractedSignatures = BlockTransformer.extract(encodedOnlineAccountSignatures, 0, signaturesLength);
+		byte[] extractedNonces = BlockTransformer.extract(encodedOnlineAccountSignatures, signaturesLength, onlineRewardShares.size() * Transformer.INT_LENGTH);
+		encodedOnlineAccountSignatures = extractedSignatures;
 
-			List<Integer> nonces = BlockTransformer.decodeOnlineAccountNonces(extractedNonces);
+		List<Integer> nonces = BlockTransformer.decodeOnlineAccountNonces(extractedNonces);
 
-			// Build block's view of online accounts (without signatures, as we don't need them here)
-			Set<OnlineAccountData> onlineAccounts = new HashSet<>();
-			for (int i = 0; i < onlineRewardShares.size(); ++i) {
-				Integer nonce = nonces.get(i);
-				byte[] publicKey = onlineRewardShares.get(i).getRewardSharePublicKey();
+		// Build block's view of online accounts (without signatures, as we don't need them here)
+		Set<OnlineAccountData> onlineAccounts = new HashSet<>();
+		for (int i = 0; i < onlineRewardShares.size(); ++i) {
+			Integer nonce = nonces.get(i);
+			byte[] publicKey = onlineRewardShares.get(i).getRewardSharePublicKey();
 
-				OnlineAccountData onlineAccountData = new OnlineAccountData(onlineTimestamp, null, publicKey, nonce);
-				onlineAccounts.add(onlineAccountData);
-			}
-
-			// Remove those already validated & cached by online accounts manager - no need to re-validate them
-			OnlineAccountsManager.getInstance().removeKnown(onlineAccounts, onlineTimestamp);
-
-			// Validate the rest
-			for (OnlineAccountData onlineAccount : onlineAccounts)
-				if (!OnlineAccountsManager.getInstance().verifyMemoryPoW(onlineAccount, this.blockData.getTimestamp()))
-					return ValidationResult.ONLINE_ACCOUNT_NONCE_INCORRECT;
+			OnlineAccountData onlineAccountData = new OnlineAccountData(onlineTimestamp, null, publicKey, nonce);
+			onlineAccounts.add(onlineAccountData);
 		}
 
+		// Remove those already validated & cached by online accounts manager - no need to re-validate them
+		OnlineAccountsManager.getInstance().removeKnown(onlineAccounts, onlineTimestamp);
+
+		// Validate the rest
+		for (OnlineAccountData onlineAccount : onlineAccounts)
+			if (!OnlineAccountsManager.getInstance().verifyMemoryPoW(onlineAccount, null))
+				return ValidationResult.ONLINE_ACCOUNT_NONCE_INCORRECT;
+
+		// Cache the valid online accounts as they will likely be needed for the next block
+		OnlineAccountsManager.getInstance().addBlocksOnlineAccounts(onlineAccounts, onlineTimestamp);
+
 		// Extract online accounts' timestamp signatures from block data. Only one signature if aggregated.
 		List<byte[]> onlineAccountsSignatures = BlockTransformer.decodeTimestampSignatures(encodedOnlineAccountSignatures);
 

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

@@ -73,7 +73,8 @@ public class BlockChain {
 		calcChainWeightTimestamp,
 		transactionV5Timestamp,
 		transactionV6Timestamp,
-		disableReferenceTimestamp;
+		disableReferenceTimestamp,
+		increaseOnlineAccountsDifficultyTimestamp;
 	}
 
 	// Custom transaction fees
@@ -195,10 +196,6 @@ public class BlockChain {
 	 * featureTriggers because unit tests need to set this value via Reflection. */
 	private long onlineAccountsModulusV2Timestamp;
 
-	/** Feature trigger timestamp for online accounts mempow verification. Can't use featureTriggers
-	 * because unit tests need to set this value via Reflection. */
-	private long onlineAccountsMemoryPoWTimestamp;
-
 	/** Max reward shares by block height */
 	public static class MaxRewardSharesByTimestamp {
 		public long timestamp;
@@ -359,10 +356,6 @@ public class BlockChain {
 		return this.onlineAccountsModulusV2Timestamp;
 	}
 
-	public long getOnlineAccountsMemoryPoWTimestamp() {
-		return this.onlineAccountsMemoryPoWTimestamp;
-	}
-
 	/** Returns true if approval-needing transaction types require a txGroupId other than NO_GROUP. */
 	public boolean getRequireGroupForApproval() {
 		return this.requireGroupForApproval;
@@ -486,6 +479,10 @@ public class BlockChain {
 		return this.featureTriggers.get(FeatureTrigger.disableReferenceTimestamp.name()).longValue();
 	}
 
+	public long getIncreaseOnlineAccountsDifficultyTimestamp() {
+		return this.featureTriggers.get(FeatureTrigger.increaseOnlineAccountsDifficultyTimestamp.name()).longValue();
+	}
+
 
 	// More complex getters for aspects that change by height or timestamp
 

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

@@ -26,6 +26,9 @@ import org.qortal.data.block.CommonBlockData;
 import org.qortal.data.transaction.TransactionData;
 import org.qortal.network.Network;
 import org.qortal.network.Peer;
+import org.qortal.network.message.BlockSummariesV2Message;
+import org.qortal.network.message.HeightV2Message;
+import org.qortal.network.message.Message;
 import org.qortal.repository.BlockRepository;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
@@ -90,6 +93,8 @@ public class BlockMinter extends Thread {
 
 		List<Block> newBlocks = new ArrayList<>();
 
+		final boolean isSingleNodeTestnet = Settings.getInstance().isSingleNodeTestnet();
+
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			// Going to need this a lot...
 			BlockRepository blockRepository = repository.getBlockRepository();
@@ -108,8 +113,9 @@ public class BlockMinter extends Thread {
 					// Free up any repository locks
 					repository.discardChanges();
 
-					// Sleep for a while
-					Thread.sleep(1000);
+					// Sleep for a while.
+					// It's faster on single node testnets, to allow lots of blocks to be minted quickly.
+					Thread.sleep(isSingleNodeTestnet ? 50 : 1000);
 
 					isMintingPossible = false;
 
@@ -220,9 +226,10 @@ public class BlockMinter extends Thread {
 					List<PrivateKeyAccount> newBlocksMintingAccounts = mintingAccountsData.stream().map(accountData -> new PrivateKeyAccount(repository, accountData.getPrivateKey())).collect(Collectors.toList());
 
 					// We might need to sit the next block out, if one of our minting accounts signed the previous one
+					// Skip this check for single node testnets, since they definitely need to mint every block
 					byte[] previousBlockMinter = previousBlockData.getMinterPublicKey();
 					boolean mintedLastBlock = mintingAccountsData.stream().anyMatch(mintingAccount -> Arrays.equals(mintingAccount.getPublicKey(), previousBlockMinter));
-					if (mintedLastBlock) {
+					if (mintedLastBlock && !isSingleNodeTestnet) {
 						LOGGER.trace(String.format("One of our keys signed the last block, so we won't sign the next one"));
 						continue;
 					}
@@ -241,7 +248,7 @@ public class BlockMinter extends Thread {
 							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"));
+								moderatedLog(() -> LOGGER.info("Couldn't build a to-be-minted block"));
 								continue;
 							}
 
@@ -433,11 +440,9 @@ public class BlockMinter extends Thread {
 
 					if (newBlockMinted) {
 						// Broadcast our new chain to network
-						BlockData newBlockData = newBlock.getBlockData();
-
-						Network network = Network.getInstance();
-						network.broadcast(broadcastPeer -> network.buildHeightMessage(broadcastPeer, newBlockData));
+						Network.getInstance().broadcastOurChain();
 					}
+
 				} catch (InterruptedException e) {
 					// We've been interrupted - time to exit
 					return;

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

@@ -45,7 +45,6 @@ import org.qortal.data.account.AccountData;
 import org.qortal.data.block.BlockData;
 import org.qortal.data.block.BlockSummaryData;
 import org.qortal.data.naming.NameData;
-import org.qortal.data.network.PeerChainTipData;
 import org.qortal.data.network.PeerData;
 import org.qortal.data.transaction.ChatTransactionData;
 import org.qortal.data.transaction.TransactionData;
@@ -317,6 +316,10 @@ public class Controller extends Thread {
 		}
 	}
 
+	public static long uptime() {
+		return System.currentTimeMillis() - Controller.startTime;
+	}
+
 	/** Returns highest block, or null if it's not available. */
 	public BlockData getChainTip() {
 		synchronized (this.latestBlocks) {
@@ -727,25 +730,25 @@ public class Controller extends Thread {
 
 	public static final Predicate<Peer> hasNoRecentBlock = peer -> {
 		final Long minLatestBlockTimestamp = getMinimumLatestBlockTimestamp();
-		final PeerChainTipData peerChainTipData = peer.getChainTipData();
-		return peerChainTipData == null || peerChainTipData.getLastBlockTimestamp() == null || peerChainTipData.getLastBlockTimestamp() < minLatestBlockTimestamp;
+		final BlockSummaryData peerChainTipData = peer.getChainTipData();
+		return peerChainTipData == null || peerChainTipData.getTimestamp() == null || peerChainTipData.getTimestamp() < minLatestBlockTimestamp;
 	};
 
 	public static final Predicate<Peer> hasNoOrSameBlock = peer -> {
 		final BlockData latestBlockData = getInstance().getChainTip();
-		final PeerChainTipData peerChainTipData = peer.getChainTipData();
-		return peerChainTipData == null || peerChainTipData.getLastBlockSignature() == null || Arrays.equals(latestBlockData.getSignature(), peerChainTipData.getLastBlockSignature());
+		final BlockSummaryData peerChainTipData = peer.getChainTipData();
+		return peerChainTipData == null || peerChainTipData.getSignature() == null || Arrays.equals(latestBlockData.getSignature(), peerChainTipData.getSignature());
 	};
 
 	public static final Predicate<Peer> hasOnlyGenesisBlock = peer -> {
-		final PeerChainTipData peerChainTipData = peer.getChainTipData();
-		return peerChainTipData == null || peerChainTipData.getLastHeight() == null || peerChainTipData.getLastHeight() == 1;
+		final BlockSummaryData peerChainTipData = peer.getChainTipData();
+		return peerChainTipData == null || peerChainTipData.getHeight() == 1;
 	};
 
 	public static final Predicate<Peer> hasInferiorChainTip = peer -> {
-		final PeerChainTipData peerChainTipData = peer.getChainTipData();
+		final BlockSummaryData peerChainTipData = peer.getChainTipData();
 		final List<ByteArray> inferiorChainTips = Synchronizer.getInstance().inferiorChainSignatures;
-		return peerChainTipData == null || peerChainTipData.getLastBlockSignature() == null || inferiorChainTips.contains(ByteArray.wrap(peerChainTipData.getLastBlockSignature()));
+		return peerChainTipData == null || peerChainTipData.getSignature() == null || inferiorChainTips.contains(ByteArray.wrap(peerChainTipData.getSignature()));
 	};
 
 	public static final Predicate<Peer> hasOldVersion = peer -> {
@@ -835,6 +838,12 @@ public class Controller extends Thread {
 		String tooltip = String.format("%s - %d %s", actionText, numberOfPeers, connectionsText);
 		if (!Settings.getInstance().isLite()) {
 			tooltip = tooltip.concat(String.format(" - %s %d", heightText, height));
+
+			final Integer blocksRemaining = Synchronizer.getInstance().getBlocksRemaining();
+			if (blocksRemaining != null && blocksRemaining > 0) {
+				String blocksRemainingText = Translator.INSTANCE.translate("SysTray", "BLOCKS_REMAINING");
+				tooltip = tooltip.concat(String.format(" - %d %s", blocksRemaining, blocksRemainingText));
+			}
 		}
 		tooltip = tooltip.concat(String.format("\n%s: %s", Translator.INSTANCE.translate("SysTray", "BUILD_VERSION"), this.buildVersion));
 		SysTray.getInstance().setToolTipText(tooltip);
@@ -1007,8 +1016,7 @@ public class Controller extends Thread {
 		network.broadcast(peer -> peer.isOutbound() ? network.buildPeersMessage(peer) : new GetPeersMessage());
 
 		// Send our current height
-		BlockData latestBlockData = getChainTip();
-		network.broadcast(peer -> network.buildHeightMessage(peer, latestBlockData));
+		network.broadcastOurChain();
 
 		// Request unconfirmed transaction signatures, but only if we're up-to-date.
 		// If we're NOT up-to-date then priority is synchronizing first
@@ -1215,6 +1223,10 @@ public class Controller extends Thread {
 				onNetworkHeightV2Message(peer, message);
 				break;
 
+			case BLOCK_SUMMARIES_V2:
+				onNetworkBlockSummariesV2Message(peer, message);
+				break;
+
 			case GET_TRANSACTION:
 				TransactionImporter.getInstance().onNetworkGetTransactionMessage(peer, message);
 				break;
@@ -1232,19 +1244,10 @@ public class Controller extends Thread {
 				break;
 
 			case GET_ONLINE_ACCOUNTS:
-				OnlineAccountsManager.getInstance().onNetworkGetOnlineAccountsMessage(peer, message);
-				break;
-
 			case ONLINE_ACCOUNTS:
-				OnlineAccountsManager.getInstance().onNetworkOnlineAccountsMessage(peer, message);
-				break;
-
 			case GET_ONLINE_ACCOUNTS_V2:
-				OnlineAccountsManager.getInstance().onNetworkGetOnlineAccountsV2Message(peer, message);
-				break;
-
 			case ONLINE_ACCOUNTS_V2:
-				OnlineAccountsManager.getInstance().onNetworkOnlineAccountsV2Message(peer, message);
+				// No longer supported - to be eventually removed
 				break;
 
 			case GET_ONLINE_ACCOUNTS_V3:
@@ -1378,8 +1381,10 @@ public class Controller extends Thread {
 				// Send valid, yet unexpected message type in response, so peer's synchronizer doesn't have to wait for timeout
 				LOGGER.debug(() -> String.format("Sending 'block unknown' response to peer %s for GET_BLOCK request for unknown block %s", peer, Base58.encode(signature)));
 
-				// We'll send empty block summaries message as it's very short
-				Message blockUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+				// Send generic 'unknown' message as it's very short
+				Message blockUnknownMessage = peer.getPeersVersion() >= GenericUnknownMessage.MINIMUM_PEER_VERSION
+						? new GenericUnknownMessage()
+						: new BlockSummariesMessage(Collections.emptyList());
 				blockUnknownMessage.setId(message.getId());
 				if (!peer.sendMessage(blockUnknownMessage))
 					peer.disconnect("failed to send block-unknown response");
@@ -1428,11 +1433,15 @@ public class Controller extends Thread {
 		this.stats.getBlockSummariesStats.requests.incrementAndGet();
 
 		// If peer's parent signature matches our latest block signature
-		// then we can short-circuit with an empty response
+		// then we have no blocks after that and can short-circuit with an empty response
 		BlockData chainTip = getChainTip();
 		if (chainTip != null && Arrays.equals(parentSignature, chainTip.getSignature())) {
-			Message blockSummariesMessage = new BlockSummariesMessage(Collections.emptyList());
+			Message blockSummariesMessage = peer.getPeersVersion() >= BlockSummariesV2Message.MINIMUM_PEER_VERSION
+					? new BlockSummariesV2Message(Collections.emptyList())
+					: new BlockSummariesMessage(Collections.emptyList());
+
 			blockSummariesMessage.setId(message.getId());
+
 			if (!peer.sendMessage(blockSummariesMessage))
 				peer.disconnect("failed to send block summaries");
 
@@ -1488,7 +1497,9 @@ public class Controller extends Thread {
 				this.stats.getBlockSummariesStats.fullyFromCache.incrementAndGet();
 		}
 
-		Message blockSummariesMessage = new BlockSummariesMessage(blockSummaries);
+		Message blockSummariesMessage = peer.getPeersVersion() >= BlockSummariesV2Message.MINIMUM_PEER_VERSION
+				? new BlockSummariesV2Message(blockSummaries)
+				: new BlockSummariesMessage(blockSummaries);
 		blockSummariesMessage.setId(message.getId());
 		if (!peer.sendMessage(blockSummariesMessage))
 			peer.disconnect("failed to send block summaries");
@@ -1563,18 +1574,59 @@ public class Controller extends Thread {
 			// If peer is inbound and we've not updated their height
 			// then this is probably their initial HEIGHT_V2 message
 			// so they need a corresponding HEIGHT_V2 message from us
-			if (!peer.isOutbound() && (peer.getChainTipData() == null || peer.getChainTipData().getLastHeight() == null))
-				peer.sendMessage(Network.getInstance().buildHeightMessage(peer, getChainTip()));
+			if (!peer.isOutbound() && peer.getChainTipData() == null) {
+				Message responseMessage = Network.getInstance().buildHeightOrChainTipInfo(peer);
+
+				if (responseMessage == null || !peer.sendMessage(responseMessage)) {
+					peer.disconnect("failed to send our chain tip info");
+					return;
+				}
+			}
 		}
 
 		// Update peer chain tip data
-		PeerChainTipData newChainTipData = new PeerChainTipData(heightV2Message.getHeight(), heightV2Message.getSignature(), heightV2Message.getTimestamp(), heightV2Message.getMinterPublicKey());
+		BlockSummaryData newChainTipData = new BlockSummaryData(heightV2Message.getHeight(), heightV2Message.getSignature(), heightV2Message.getMinterPublicKey(), heightV2Message.getTimestamp());
 		peer.setChainTipData(newChainTipData);
 
 		// Potentially synchronize
 		Synchronizer.getInstance().requestSync();
 	}
 
+	private void onNetworkBlockSummariesV2Message(Peer peer, Message message) {
+		BlockSummariesV2Message blockSummariesV2Message = (BlockSummariesV2Message) message;
+
+		if (!Settings.getInstance().isLite()) {
+			// If peer is inbound and we've not updated their height
+			// then this is probably their initial BLOCK_SUMMARIES_V2 message
+			// so they need a corresponding BLOCK_SUMMARIES_V2 message from us
+			if (!peer.isOutbound() && peer.getChainTipData() == null) {
+				Message responseMessage = Network.getInstance().buildHeightOrChainTipInfo(peer);
+
+				if (responseMessage == null || !peer.sendMessage(responseMessage)) {
+					peer.disconnect("failed to send our chain tip info");
+					return;
+				}
+			}
+		}
+
+		if (message.hasId()) {
+			/*
+			 * Experimental proof-of-concept: discard messages with ID
+			 * These are 'late' reply messages received after timeout has expired,
+			 * having been passed upwards from Peer to Network to Controller.
+			 * Hence, these are NOT simple "here's my chain tip" broadcasts from other peers.
+			 */
+			LOGGER.debug("Discarding late {} message with ID {} from {}", message.getType().name(), message.getId(), peer);
+			return;
+		}
+
+		// Update peer chain tip data
+		peer.setChainTipSummaries(blockSummariesV2Message.getBlockSummaries());
+
+		// Potentially synchronize
+		Synchronizer.getInstance().requestSync();
+	}
+
 	private void onNetworkGetAccountMessage(Peer peer, Message message) {
 		GetAccountMessage getAccountMessage = (GetAccountMessage) message;
 		String address = getAccountMessage.getAddress();
@@ -1590,8 +1642,8 @@ public class Controller extends Thread {
 				// Send valid, yet unexpected message type in response, so peer doesn't have to wait for timeout
 				LOGGER.debug(() -> String.format("Sending 'account unknown' response to peer %s for GET_ACCOUNT request for unknown account %s", peer, address));
 
-				// We'll send empty block summaries message as it's very short
-				Message accountUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+				// Send generic 'unknown' message as it's very short
+				Message accountUnknownMessage = new GenericUnknownMessage();
 				accountUnknownMessage.setId(message.getId());
 				if (!peer.sendMessage(accountUnknownMessage))
 					peer.disconnect("failed to send account-unknown response");
@@ -1626,8 +1678,8 @@ public class Controller extends Thread {
 				// Send valid, yet unexpected message type in response, so peer doesn't have to wait for timeout
 				LOGGER.debug(() -> String.format("Sending 'account unknown' response to peer %s for GET_ACCOUNT_BALANCE request for unknown account %s and asset ID %d", peer, address, assetId));
 
-				// We'll send empty block summaries message as it's very short
-				Message accountUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+				// Send generic 'unknown' message as it's very short
+				Message accountUnknownMessage = new GenericUnknownMessage();
 				accountUnknownMessage.setId(message.getId());
 				if (!peer.sendMessage(accountUnknownMessage))
 					peer.disconnect("failed to send account-unknown response");
@@ -1670,8 +1722,8 @@ public class Controller extends Thread {
 				// Send valid, yet unexpected message type in response, so peer doesn't have to wait for timeout
 				LOGGER.debug(() -> String.format("Sending 'account unknown' response to peer %s for GET_ACCOUNT_TRANSACTIONS request for unknown account %s", peer, address));
 
-				// We'll send empty block summaries message as it's very short
-				Message accountUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+				// Send generic 'unknown' message as it's very short
+				Message accountUnknownMessage = new GenericUnknownMessage();
 				accountUnknownMessage.setId(message.getId());
 				if (!peer.sendMessage(accountUnknownMessage))
 					peer.disconnect("failed to send account-unknown response");
@@ -1707,8 +1759,8 @@ public class Controller extends Thread {
 				// Send valid, yet unexpected message type in response, so peer doesn't have to wait for timeout
 				LOGGER.debug(() -> String.format("Sending 'account unknown' response to peer %s for GET_ACCOUNT_NAMES request for unknown account %s", peer, address));
 
-				// We'll send empty block summaries message as it's very short
-				Message accountUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+				// Send generic 'unknown' message as it's very short
+				Message accountUnknownMessage = new GenericUnknownMessage();
 				accountUnknownMessage.setId(message.getId());
 				if (!peer.sendMessage(accountUnknownMessage))
 					peer.disconnect("failed to send account-unknown response");
@@ -1742,8 +1794,8 @@ public class Controller extends Thread {
 				// Send valid, yet unexpected message type in response, so peer doesn't have to wait for timeout
 				LOGGER.debug(() -> String.format("Sending 'name unknown' response to peer %s for GET_NAME request for unknown name %s", peer, name));
 
-				// We'll send empty block summaries message as it's very short
-				Message nameUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+				// Send generic 'unknown' message as it's very short
+				Message nameUnknownMessage = new GenericUnknownMessage();
 				nameUnknownMessage.setId(message.getId());
 				if (!peer.sendMessage(nameUnknownMessage))
 					peer.disconnect("failed to send name-unknown response");
@@ -1791,14 +1843,14 @@ public class Controller extends Thread {
 				continue;
 			}
 
-			final PeerChainTipData peerChainTipData = peer.getChainTipData();
+			BlockSummaryData peerChainTipData = peer.getChainTipData();
 			if (peerChainTipData == null) {
 				iterator.remove();
 				continue;
 			}
 
 			// Disregard peers that don't have a recent block
-			if (peerChainTipData.getLastBlockTimestamp() == null || peerChainTipData.getLastBlockTimestamp() < minLatestBlockTimestamp) {
+			if (peerChainTipData.getTimestamp() == null || peerChainTipData.getTimestamp() < minLatestBlockTimestamp) {
 				iterator.remove();
 				continue;
 			}
@@ -1826,6 +1878,10 @@ public class Controller extends Thread {
 		if (latestBlockData == null || latestBlockData.getTimestamp() < minLatestBlockTimestamp)
 			return false;
 
+		if (Settings.getInstance().isSingleNodeTestnet())
+			// Single node testnets won't have peers, so we can assume up to date from this point
+			return true;
+
 		// Needs a mutable copy of the unmodifiableList
 		List<Peer> peers = new ArrayList<>(Network.getInstance().getImmutableHandshakedPeers());
 		if (peers == null)

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

@@ -53,17 +53,30 @@ public class OnlineAccountsManager {
      */
     private static final int MAX_BLOCKS_CACHED_ONLINE_ACCOUNTS = 3;
 
-    private static final long ONLINE_ACCOUNTS_QUEUE_INTERVAL = 100L; //ms
+    private static final long ONLINE_ACCOUNTS_QUEUE_INTERVAL = 100L; // ms
     private static final long ONLINE_ACCOUNTS_TASKS_INTERVAL = 10 * 1000L; // ms
-    private static final long ONLINE_ACCOUNTS_LEGACY_BROADCAST_INTERVAL = 60 * 1000L; // ms
-    private static final long ONLINE_ACCOUNTS_BROADCAST_INTERVAL = 5 * 1000L; // ms
+    private static final long ONLINE_ACCOUNTS_COMPUTE_INTERVAL = 5 * 1000L; // ms
+    private static final long ONLINE_ACCOUNTS_BROADCAST_INTERVAL = 60 * 1000L; // ms
+    // After switching to a new online timestamp, we "burst" the online accounts requests
+    // at an increased interval for a specified amount of time
+    private static final long ONLINE_ACCOUNTS_BROADCAST_BURST_INTERVAL = 5 * 1000L; // ms
+    private static final long ONLINE_ACCOUNTS_BROADCAST_BURST_LENGTH = 5 * 60 * 1000L; // ms
 
-    private static final long ONLINE_ACCOUNTS_V2_PEER_VERSION = 0x0300020000L; // v3.2.0
-    private static final long ONLINE_ACCOUNTS_V3_PEER_VERSION = 0x0300040000L; // v3.4.0
+    private static final long ONLINE_ACCOUNTS_COMPUTE_INITIAL_SLEEP_INTERVAL = 30 * 1000L; // ms
 
-    // MemoryPoW
-    public final int POW_BUFFER_SIZE = 1 * 1024 * 1024; // bytes
-    public int POW_DIFFICULTY = 18; // leading zero bits
+    // MemoryPoW - mainnet
+    public static final int POW_BUFFER_SIZE = 1 * 1024 * 1024; // bytes
+    public static final int POW_DIFFICULTY_V1 = 18; // leading zero bits
+    public static final int POW_DIFFICULTY_V2 = 19; // leading zero bits
+
+    // MemoryPoW - testnet
+    public static final int POW_BUFFER_SIZE_TESTNET = 1 * 1024 * 1024; // bytes
+    public static final int POW_DIFFICULTY_TESTNET = 5; // leading zero bits
+
+    // IMPORTANT: if we ever need to dynamically modify the buffer size using a feature trigger, the
+    // pre-allocated buffer below will NOT work, and we should instead use a dynamically allocated
+    // one for the transition period.
+    private static long[] POW_VERIFY_WORK_BUFFER = new long[getPoWBufferSize() / 8];
 
     private final ScheduledExecutorService executor = Executors.newScheduledThreadPool(4, new NamedThreadFactory("OnlineAccounts"));
     private volatile boolean isStopping = false;
@@ -85,6 +98,8 @@ public class OnlineAccountsManager {
      */
     private final SortedMap<Long, Set<OnlineAccountData>> latestBlocksOnlineAccounts = new ConcurrentSkipListMap<>();
 
+    private long lastOnlineAccountsRequest = 0;
+
     private boolean hasOurOnlineAccounts = false;
 
     public static long getOnlineTimestampModulus() {
@@ -107,6 +122,23 @@ public class OnlineAccountsManager {
         return (timestamp / getOnlineTimestampModulus()) * getOnlineTimestampModulus();
     }
 
+    private static int getPoWBufferSize() {
+        if (Settings.getInstance().isTestNet())
+            return POW_BUFFER_SIZE_TESTNET;
+
+        return POW_BUFFER_SIZE;
+    }
+
+    private static int getPoWDifficulty(long timestamp) {
+        if (Settings.getInstance().isTestNet())
+            return POW_DIFFICULTY_TESTNET;
+
+        if (timestamp >= BlockChain.getInstance().getIncreaseOnlineAccountsDifficultyTimestamp())
+            return POW_DIFFICULTY_V2;
+
+        return POW_DIFFICULTY_V1;
+    }
+
     private OnlineAccountsManager() {
     }
 
@@ -122,16 +154,16 @@ public class OnlineAccountsManager {
         // Expire old online accounts signatures
         executor.scheduleAtFixedRate(this::expireOldOnlineAccounts, ONLINE_ACCOUNTS_TASKS_INTERVAL, ONLINE_ACCOUNTS_TASKS_INTERVAL, TimeUnit.MILLISECONDS);
 
-        // Send our online accounts
-        executor.scheduleAtFixedRate(this::sendOurOnlineAccountsInfo, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, TimeUnit.MILLISECONDS);
-
-        // Request online accounts from peers (legacy)
-        executor.scheduleAtFixedRate(this::requestLegacyRemoteOnlineAccounts, ONLINE_ACCOUNTS_LEGACY_BROADCAST_INTERVAL, ONLINE_ACCOUNTS_LEGACY_BROADCAST_INTERVAL, TimeUnit.MILLISECONDS);
-        // Request online accounts from peers (V3+)
-        executor.scheduleAtFixedRate(this::requestRemoteOnlineAccounts, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, TimeUnit.MILLISECONDS);
+        // Request online accounts from peers
+        executor.scheduleAtFixedRate(this::requestRemoteOnlineAccounts, ONLINE_ACCOUNTS_BROADCAST_BURST_INTERVAL, ONLINE_ACCOUNTS_BROADCAST_BURST_INTERVAL, TimeUnit.MILLISECONDS);
 
         // Process import queue
         executor.scheduleWithFixedDelay(this::processOnlineAccountsImportQueue, ONLINE_ACCOUNTS_QUEUE_INTERVAL, ONLINE_ACCOUNTS_QUEUE_INTERVAL, TimeUnit.MILLISECONDS);
+
+        // Send our online accounts (using increased initial delay)
+        // This allows some time for initial online account lists to be retrieved, and
+        // reduces the chances of the same nonce being computed twice
+        executor.scheduleAtFixedRate(this::sendOurOnlineAccountsInfo, ONLINE_ACCOUNTS_COMPUTE_INITIAL_SLEEP_INTERVAL, ONLINE_ACCOUNTS_COMPUTE_INTERVAL, TimeUnit.MILLISECONDS);
     }
 
     public void shutdown() {
@@ -151,7 +183,6 @@ public class OnlineAccountsManager {
             return;
 
         byte[] timestampBytes = Longs.toByteArray(onlineAccountsTimestamp);
-        final boolean mempowActive = onlineAccountsTimestamp >= BlockChain.getInstance().getOnlineAccountsMemoryPoWTimestamp();
 
         Set<OnlineAccountData> replacementAccounts = new HashSet<>();
         for (PrivateKeyAccount onlineAccount : onlineAccounts) {
@@ -160,7 +191,7 @@ public class OnlineAccountsManager {
             byte[] signature = Qortal25519Extras.signForAggregation(onlineAccount.getPrivateKey(), timestampBytes);
             byte[] publicKey = onlineAccount.getPublicKey();
 
-            Integer nonce = mempowActive ? new Random().nextInt(500000) : null;
+            Integer nonce = new Random().nextInt(500000);
 
             OnlineAccountData ourOnlineAccountData = new OnlineAccountData(onlineAccountsTimestamp, signature, publicKey, nonce);
             replacementAccounts.add(ourOnlineAccountData);
@@ -180,25 +211,37 @@ public class OnlineAccountsManager {
         LOGGER.debug("Processing online accounts import queue (size: {})", this.onlineAccountsImportQueue.size());
 
         Set<OnlineAccountData> onlineAccountsToAdd = new HashSet<>();
+        Set<OnlineAccountData> onlineAccountsToRemove = new HashSet<>();
         try (final Repository repository = RepositoryManager.getRepository()) {
             for (OnlineAccountData onlineAccountData : this.onlineAccountsImportQueue) {
                 if (isStopping)
                     return;
 
+                // Skip this account if it's already validated
+                Set<OnlineAccountData> onlineAccounts = this.currentOnlineAccounts.get(onlineAccountData.getTimestamp());
+                if (onlineAccounts != null && onlineAccounts.contains(onlineAccountData)) {
+                    // We have already validated this online account
+                    onlineAccountsImportQueue.remove(onlineAccountData);
+                    continue;
+                }
+
                 boolean isValid = this.isValidCurrentAccount(repository, onlineAccountData);
                 if (isValid)
                     onlineAccountsToAdd.add(onlineAccountData);
 
-                // Remove from queue
-                onlineAccountsImportQueue.remove(onlineAccountData);
+                // Don't remove from the queue yet - we'll do this at the end of the process
+                // This prevents duplicates being added to the queue whilst it's being processed
+                onlineAccountsToRemove.add(onlineAccountData);
             }
         } catch (DataException e) {
             LOGGER.error("Repository issue while verifying online accounts", e);
-        }
 
-        if (!onlineAccountsToAdd.isEmpty()) {
-            LOGGER.debug("Merging {} validated online accounts from import queue", onlineAccountsToAdd.size());
-            addAccounts(onlineAccountsToAdd);
+        } finally {
+            if (!onlineAccountsToAdd.isEmpty()) {
+                LOGGER.debug("Merging {} validated online accounts from import queue", onlineAccountsToAdd.size());
+                addAccounts(onlineAccountsToAdd);
+            }
+            onlineAccountsImportQueue.removeAll(onlineAccountsToRemove);
         }
     }
 
@@ -304,12 +347,10 @@ public class OnlineAccountsManager {
             return false;
         }
 
-        // Validate mempow if feature trigger is active
-        if (now >= BlockChain.getInstance().getOnlineAccountsMemoryPoWTimestamp()) {
-            if (!getInstance().verifyMemoryPoW(onlineAccountData, now)) {
-                LOGGER.trace(() -> String.format("Rejecting online reward-share for account %s due to invalid PoW nonce", mintingAccount.getAddress()));
-                return false;
-            }
+        // Validate mempow
+        if (!getInstance().verifyMemoryPoW(onlineAccountData, POW_VERIFY_WORK_BUFFER)) {
+            LOGGER.trace(() -> String.format("Rejecting online reward-share for account %s due to invalid PoW nonce", mintingAccount.getAddress()));
+            return false;
         }
 
         return true;
@@ -333,7 +374,7 @@ public class OnlineAccountsManager {
         for (var entry : hashesToRebuild.entrySet()) {
             Long timestamp = entry.getKey();
 
-            LOGGER.debug(() -> String.format("Rehashing for timestamp %d and leading bytes %s",
+            LOGGER.trace(() -> String.format("Rehashing for timestamp %d and leading bytes %s",
                             timestamp,
                             entry.getValue().stream().sorted(Byte::compareUnsigned).map(leadingByte -> String.format("%02x", leadingByte)).collect(Collectors.joining(", "))
                     )
@@ -359,7 +400,7 @@ public class OnlineAccountsManager {
             }
         }
 
-        LOGGER.debug(String.format("we have online accounts for timestamps: %s", String.join(", ", this.currentOnlineAccounts.keySet().stream().map(l -> Long.toString(l)).collect(Collectors.joining(", ")))));
+        LOGGER.trace(String.format("we have online accounts for timestamps: %s", String.join(", ", this.currentOnlineAccounts.keySet().stream().map(l -> Long.toString(l)).collect(Collectors.joining(", ")))));
 
         return true;
     }
@@ -399,30 +440,7 @@ public class OnlineAccountsManager {
     }
 
     /**
-     * Request data from other peers. (Pre-V3)
-     */
-    private void requestLegacyRemoteOnlineAccounts() {
-        final Long now = NTP.getTime();
-        if (now == null)
-            return;
-
-        // Don't bother if we're not up to date
-        if (!Controller.getInstance().isUpToDate())
-            return;
-
-        List<OnlineAccountData> mergedOnlineAccounts = Set.copyOf(this.currentOnlineAccounts.values()).stream().flatMap(Set::stream).collect(Collectors.toList());
-
-        Message messageV2 = new GetOnlineAccountsV2Message(mergedOnlineAccounts);
-
-        Network.getInstance().broadcast(peer ->
-                peer.getPeersVersion() < ONLINE_ACCOUNTS_V3_PEER_VERSION
-                        ? messageV2
-                        : null
-        );
-    }
-
-    /**
-     * Request data from other peers. V3+
+     * Request data from other peers
      */
     private void requestRemoteOnlineAccounts() {
         final Long now = NTP.getTime();
@@ -433,13 +451,25 @@ public class OnlineAccountsManager {
         if (!Controller.getInstance().isUpToDate())
             return;
 
-        Message messageV3 = new GetOnlineAccountsV3Message(currentOnlineAccountsHashes);
+        long onlineAccountsTimestamp = getCurrentOnlineAccountTimestamp();
+        if (now - onlineAccountsTimestamp >= ONLINE_ACCOUNTS_BROADCAST_BURST_LENGTH) {
+            // New online timestamp started more than 5 mins ago - we probably don't need to request so frequently
 
-        Network.getInstance().broadcast(peer ->
-                peer.getPeersVersion() >= ONLINE_ACCOUNTS_V3_PEER_VERSION
-                        ? messageV3
-                        : null
-        );
+            if (Controller.uptime() < ONLINE_ACCOUNTS_BROADCAST_BURST_LENGTH) {
+                // The node recently started up, so we should request at the burst interval
+                // This could allow accounts to move around the network more easily when an auto update is occurring
+            }
+            else if (now - lastOnlineAccountsRequest < ONLINE_ACCOUNTS_BROADCAST_INTERVAL) {
+                // We already requested online accounts in the last minute, so no need to request again
+                return;
+            }
+        }
+
+        LOGGER.debug("Requesting online accounts via broadcast...");
+
+        lastOnlineAccountsRequest = now;
+        Message messageV3 = new GetOnlineAccountsV3Message(currentOnlineAccountsHashes);
+        Network.getInstance().broadcast(peer -> messageV3);
     }
 
     /**
@@ -464,12 +494,10 @@ public class OnlineAccountsManager {
 
         // 'next' timestamp (prioritize this as it's the most important, if mempow active)
         final long nextOnlineAccountsTimestamp = toOnlineAccountTimestamp(now) + getOnlineTimestampModulus();
-        if (isMemoryPoWActive(now)) {
-            boolean success = computeOurAccountsForTimestamp(nextOnlineAccountsTimestamp);
-            if (!success) {
-                // We didn't compute the required nonce value(s), and so can't proceed until they have been retried
-                return;
-            }
+        boolean success = computeOurAccountsForTimestamp(nextOnlineAccountsTimestamp);
+        if (!success) {
+            // We didn't compute the required nonce value(s), and so can't proceed until they have been retried
+            return;
         }
 
         // 'current' timestamp
@@ -522,6 +550,8 @@ public class OnlineAccountsManager {
             Set<OnlineAccountData> onlineAccounts = this.currentOnlineAccounts.computeIfAbsent(onlineAccountsTimestamp, k -> ConcurrentHashMap.newKeySet());
             boolean alreadyExists = onlineAccounts.stream().anyMatch(a -> Arrays.equals(a.getPublicKey(), publicKey));
             if (alreadyExists) {
+                this.hasOurOnlineAccounts = true;
+
                 if (remaining > 0) {
                     // Move on to next account
                     continue;
@@ -544,21 +574,15 @@ public class OnlineAccountsManager {
 
             // Compute nonce
             Integer nonce;
-            if (isMemoryPoWActive(NTP.getTime())) {
-                try {
-                    nonce = this.computeMemoryPoW(mempowBytes, publicKey, onlineAccountsTimestamp);
-                    if (nonce == null) {
-                        // A nonce is required
-                        return false;
-                    }
-                } catch (TimeoutException e) {
-                    LOGGER.info(String.format("Timed out computing nonce for account %.8s", Base58.encode(publicKey)));
+            try {
+                nonce = this.computeMemoryPoW(mempowBytes, publicKey, onlineAccountsTimestamp);
+                if (nonce == null) {
+                    // A nonce is required
                     return false;
                 }
-            }
-            else {
-                // Send -1 if we haven't computed a nonce due to feature trigger timestamp
-                nonce = -1;
+            } catch (TimeoutException e) {
+                LOGGER.info(String.format("Timed out computing nonce for account %.8s", Base58.encode(publicKey)));
+                return false;
             }
 
             byte[] signature = Qortal25519Extras.signForAggregation(privateKey, timestampBytes);
@@ -567,7 +591,7 @@ public class OnlineAccountsManager {
             OnlineAccountData ourOnlineAccountData = new OnlineAccountData(onlineAccountsTimestamp, signature, publicKey, nonce);
 
             // Make sure to verify before adding
-            if (verifyMemoryPoW(ourOnlineAccountData, NTP.getTime())) {
+            if (verifyMemoryPoW(ourOnlineAccountData, null)) {
                 ourOnlineAccounts.add(ourOnlineAccountData);
             }
         }
@@ -579,17 +603,7 @@ public class OnlineAccountsManager {
         if (!hasInfoChanged)
             return false;
 
-        Message messageV1 = new OnlineAccountsMessage(ourOnlineAccounts);
-        Message messageV2 = new OnlineAccountsV2Message(ourOnlineAccounts);
-        Message messageV3 = new OnlineAccountsV3Message(ourOnlineAccounts);
-
-        Network.getInstance().broadcast(peer ->
-                peer.getPeersVersion() >= OnlineAccountsV3Message.MIN_PEER_VERSION
-                        ? messageV3
-                        : peer.getPeersVersion() >= ONLINE_ACCOUNTS_V2_PEER_VERSION
-                        ? messageV2
-                        : messageV1
-        );
+        Network.getInstance().broadcast(peer -> new OnlineAccountsV3Message(ourOnlineAccounts));
 
         LOGGER.debug("Broadcasted {} online account{} with timestamp {}", ourOnlineAccounts.size(), (ourOnlineAccounts.size() != 1 ? "s" : ""), onlineAccountsTimestamp);
 
@@ -600,12 +614,6 @@ public class OnlineAccountsManager {
 
     // MemoryPoW
 
-    private boolean isMemoryPoWActive(Long timestamp) {
-        if (timestamp >= BlockChain.getInstance().getOnlineAccountsMemoryPoWTimestamp() || Settings.getInstance().isOnlineAccountsMemPoWEnabled()) {
-            return true;
-        }
-        return false;
-    }
     private byte[] getMemoryPoWBytes(byte[] publicKey, long onlineAccountsTimestamp) throws IOException {
         byte[] timestampBytes = Longs.toByteArray(onlineAccountsTimestamp);
 
@@ -617,11 +625,6 @@ public class OnlineAccountsManager {
     }
 
     private Integer computeMemoryPoW(byte[] bytes, byte[] publicKey, long onlineAccountsTimestamp) throws TimeoutException {
-        if (!isMemoryPoWActive(NTP.getTime())) {
-            LOGGER.info("Mempow start timestamp not yet reached, and onlineAccountsMemPoWEnabled not enabled in settings");
-            return null;
-        }
-
         LOGGER.info(String.format("Computing nonce for account %.8s and timestamp %d...", Base58.encode(publicKey), onlineAccountsTimestamp));
 
         // Calculate the time until the next online timestamp and use it as a timeout when computing the nonce
@@ -629,7 +632,8 @@ public class OnlineAccountsManager {
         final long nextOnlineAccountsTimestamp = toOnlineAccountTimestamp(startTime) + getOnlineTimestampModulus();
         long timeUntilNextTimestamp = nextOnlineAccountsTimestamp - startTime;
 
-        Integer nonce = MemoryPoW.compute2(bytes, POW_BUFFER_SIZE, POW_DIFFICULTY, timeUntilNextTimestamp);
+        int difficulty = getPoWDifficulty(onlineAccountsTimestamp);
+        Integer nonce = MemoryPoW.compute2(bytes, getPoWBufferSize(), difficulty, timeUntilNextTimestamp);
 
         double totalSeconds = (NTP.getTime() - startTime) / 1000.0f;
         int minutes = (int) ((totalSeconds % 3600) / 60);
@@ -638,15 +642,15 @@ public class OnlineAccountsManager {
 
         LOGGER.info(String.format("Computed nonce for timestamp %d and account %.8s: %d. Buffer size: %d. Difficulty: %d. " +
                         "Time taken: %02d:%02d. Hashrate: %f", onlineAccountsTimestamp, Base58.encode(publicKey),
-                nonce, POW_BUFFER_SIZE, POW_DIFFICULTY, minutes, seconds, hashRate));
+                nonce, getPoWBufferSize(), difficulty, minutes, seconds, hashRate));
 
         return nonce;
     }
 
-    public boolean verifyMemoryPoW(OnlineAccountData onlineAccountData, Long timestamp) {
-        if (!isMemoryPoWActive(timestamp)) {
-            // Not active yet, so treat it as valid
-            return true;
+    public boolean verifyMemoryPoW(OnlineAccountData onlineAccountData, long[] workBuffer) {
+        // Require a valid nonce value
+        if (onlineAccountData.getNonce() == null || onlineAccountData.getNonce() < 0) {
+            return false;
         }
 
         int nonce = onlineAccountData.getNonce();
@@ -659,7 +663,7 @@ public class OnlineAccountsManager {
         }
 
         // Verify the nonce
-        return MemoryPoW.verify2(mempowBytes, POW_BUFFER_SIZE, POW_DIFFICULTY, nonce);
+        return MemoryPoW.verify2(mempowBytes, workBuffer, getPoWBufferSize(), getPoWDifficulty(onlineAccountData.getTimestamp()), nonce);
     }
 
 
@@ -697,7 +701,7 @@ public class OnlineAccountsManager {
      */
     // Block::mint() - only wants online accounts with (online) timestamp that matches block's (online) timestamp so they can be added to new block
     public List<OnlineAccountData> getOnlineAccounts(long onlineTimestamp) {
-        LOGGER.info(String.format("caller's timestamp: %d, our timestamps: %s", onlineTimestamp, String.join(", ", this.currentOnlineAccounts.keySet().stream().map(l -> Long.toString(l)).collect(Collectors.joining(", ")))));
+        LOGGER.debug(String.format("caller's timestamp: %d, our timestamps: %s", onlineTimestamp, String.join(", ", this.currentOnlineAccounts.keySet().stream().map(l -> Long.toString(l)).collect(Collectors.joining(", ")))));
 
         return new ArrayList<>(Set.copyOf(this.currentOnlineAccounts.getOrDefault(onlineTimestamp, Collections.emptySet())));
     }
@@ -743,11 +747,12 @@ public class OnlineAccountsManager {
      * Typically called by {@link Block#areOnlineAccountsValid()}
      */
     public void addBlocksOnlineAccounts(Set<OnlineAccountData> blocksOnlineAccounts, Long timestamp) {
-        // We want to add to 'current' in preference if possible
-        if (this.currentOnlineAccounts.containsKey(timestamp)) {
-            addAccounts(blocksOnlineAccounts);
+        // If these are current accounts, then there is no need to cache them, and should instead rely
+        // on the more complete entries we already have in self.currentOnlineAccounts.
+        // Note: since sig-agg, we no longer have individual signatures included in blocks, so we
+        // mustn't add anything to currentOnlineAccounts from here.
+        if (this.currentOnlineAccounts.containsKey(timestamp))
             return;
-        }
 
         // Add to block cache instead
         this.latestBlocksOnlineAccounts.computeIfAbsent(timestamp, k -> ConcurrentHashMap.newKeySet())
@@ -767,106 +772,6 @@ public class OnlineAccountsManager {
 
     // Network handlers
 
-    public void onNetworkGetOnlineAccountsMessage(Peer peer, Message message) {
-        GetOnlineAccountsMessage getOnlineAccountsMessage = (GetOnlineAccountsMessage) message;
-
-        List<OnlineAccountData> excludeAccounts = getOnlineAccountsMessage.getOnlineAccounts();
-
-        // Send online accounts info, excluding entries with matching timestamp & public key from excludeAccounts
-        List<OnlineAccountData> accountsToSend = Set.copyOf(this.currentOnlineAccounts.values()).stream().flatMap(Set::stream).collect(Collectors.toList());
-        int prefilterSize = accountsToSend.size();
-
-        Iterator<OnlineAccountData> iterator = accountsToSend.iterator();
-        while (iterator.hasNext()) {
-            OnlineAccountData onlineAccountData = iterator.next();
-
-            for (OnlineAccountData excludeAccountData : excludeAccounts) {
-                if (onlineAccountData.getTimestamp() == excludeAccountData.getTimestamp() && Arrays.equals(onlineAccountData.getPublicKey(), excludeAccountData.getPublicKey())) {
-                    iterator.remove();
-                    break;
-                }
-            }
-        }
-
-        if (accountsToSend.isEmpty())
-            return;
-
-        Message onlineAccountsMessage = new OnlineAccountsMessage(accountsToSend);
-        peer.sendMessage(onlineAccountsMessage);
-
-        LOGGER.debug("Sent {} of our {} online accounts to {}", accountsToSend.size(), prefilterSize, peer);
-    }
-
-    public void onNetworkOnlineAccountsMessage(Peer peer, Message message) {
-        OnlineAccountsMessage onlineAccountsMessage = (OnlineAccountsMessage) message;
-
-        List<OnlineAccountData> peersOnlineAccounts = onlineAccountsMessage.getOnlineAccounts();
-        LOGGER.debug("Received {} online accounts from {}", peersOnlineAccounts.size(), peer);
-
-        int importCount = 0;
-
-        // Add any online accounts to the queue that aren't already present
-        for (OnlineAccountData onlineAccountData : peersOnlineAccounts) {
-            boolean isNewEntry = onlineAccountsImportQueue.add(onlineAccountData);
-
-            if (isNewEntry)
-                importCount++;
-        }
-
-        if (importCount > 0)
-            LOGGER.debug("Added {} online accounts to queue", importCount);
-    }
-
-    public void onNetworkGetOnlineAccountsV2Message(Peer peer, Message message) {
-        GetOnlineAccountsV2Message getOnlineAccountsMessage = (GetOnlineAccountsV2Message) message;
-
-        List<OnlineAccountData> excludeAccounts = getOnlineAccountsMessage.getOnlineAccounts();
-
-        // Send online accounts info, excluding entries with matching timestamp & public key from excludeAccounts
-        List<OnlineAccountData> accountsToSend = Set.copyOf(this.currentOnlineAccounts.values()).stream().flatMap(Set::stream).collect(Collectors.toList());
-        int prefilterSize = accountsToSend.size();
-
-        Iterator<OnlineAccountData> iterator = accountsToSend.iterator();
-        while (iterator.hasNext()) {
-            OnlineAccountData onlineAccountData = iterator.next();
-
-            for (OnlineAccountData excludeAccountData : excludeAccounts) {
-                if (onlineAccountData.getTimestamp() == excludeAccountData.getTimestamp() && Arrays.equals(onlineAccountData.getPublicKey(), excludeAccountData.getPublicKey())) {
-                    iterator.remove();
-                    break;
-                }
-            }
-        }
-
-        if (accountsToSend.isEmpty())
-            return;
-
-        Message onlineAccountsMessage = new OnlineAccountsV2Message(accountsToSend);
-        peer.sendMessage(onlineAccountsMessage);
-
-        LOGGER.debug("Sent {} of our {} online accounts to {}", accountsToSend.size(), prefilterSize, peer);
-    }
-
-    public void onNetworkOnlineAccountsV2Message(Peer peer, Message message) {
-        OnlineAccountsV2Message onlineAccountsMessage = (OnlineAccountsV2Message) message;
-
-        List<OnlineAccountData> peersOnlineAccounts = onlineAccountsMessage.getOnlineAccounts();
-        LOGGER.debug("Received {} online accounts from {}", peersOnlineAccounts.size(), peer);
-
-        int importCount = 0;
-
-        // Add any online accounts to the queue that aren't already present
-        for (OnlineAccountData onlineAccountData : peersOnlineAccounts) {
-            boolean isNewEntry = onlineAccountsImportQueue.add(onlineAccountData);
-
-            if (isNewEntry)
-                importCount++;
-        }
-
-        if (importCount > 0)
-            LOGGER.debug("Added {} online accounts to queue", importCount);
-    }
-
     public void onNetworkGetOnlineAccountsV3Message(Peer peer, Message message) {
         GetOnlineAccountsV3Message getOnlineAccountsMessage = (GetOnlineAccountsV3Message) message;
 
@@ -887,7 +792,7 @@ public class OnlineAccountsManager {
                 Set<OnlineAccountData> timestampsOnlineAccounts = this.currentOnlineAccounts.getOrDefault(timestamp, Collections.emptySet());
                 outgoingOnlineAccounts.addAll(timestampsOnlineAccounts);
 
-                LOGGER.debug(() -> String.format("Going to send all %d online accounts for timestamp %d", timestampsOnlineAccounts.size(), timestamp));
+                LOGGER.trace(() -> String.format("Going to send all %d online accounts for timestamp %d", timestampsOnlineAccounts.size(), timestamp));
             } else {
                 // Quick cache of which leading bytes to send so we only have to filter once
                 Set<Byte> outgoingLeadingBytes = new HashSet<>();
@@ -911,7 +816,7 @@ public class OnlineAccountsManager {
                         .forEach(outgoingOnlineAccounts::add);
 
                 if (outgoingOnlineAccounts.size() > beforeAddSize)
-                    LOGGER.debug(String.format("Going to send %d online accounts for timestamp %d and leading bytes %s",
+                    LOGGER.trace(String.format("Going to send %d online accounts for timestamp %d and leading bytes %s",
                             outgoingOnlineAccounts.size() - beforeAddSize,
                             timestamp,
                             outgoingLeadingBytes.stream().sorted(Byte::compareUnsigned).map(leadingByte -> String.format("%02x", leadingByte)).collect(Collectors.joining(", "))
@@ -920,25 +825,27 @@ public class OnlineAccountsManager {
             }
         }
 
-        peer.sendMessage(
-                peer.getPeersVersion() >= OnlineAccountsV3Message.MIN_PEER_VERSION ?
-                        new OnlineAccountsV3Message(outgoingOnlineAccounts) :
-                        new OnlineAccountsV2Message(outgoingOnlineAccounts)
-        );
+        peer.sendMessage(new OnlineAccountsV3Message(outgoingOnlineAccounts));
 
-        LOGGER.debug("Sent {} online accounts to {}", outgoingOnlineAccounts.size(), peer);
+        LOGGER.trace("Sent {} online accounts to {}", outgoingOnlineAccounts.size(), peer);
     }
 
     public void onNetworkOnlineAccountsV3Message(Peer peer, Message message) {
         OnlineAccountsV3Message onlineAccountsMessage = (OnlineAccountsV3Message) message;
 
         List<OnlineAccountData> peersOnlineAccounts = onlineAccountsMessage.getOnlineAccounts();
-        LOGGER.debug("Received {} online accounts from {}", peersOnlineAccounts.size(), peer);
+        LOGGER.trace("Received {} online accounts from {}", peersOnlineAccounts.size(), peer);
 
         int importCount = 0;
 
         // Add any online accounts to the queue that aren't already present
         for (OnlineAccountData onlineAccountData : peersOnlineAccounts) {
+
+            Set<OnlineAccountData> onlineAccounts = this.currentOnlineAccounts.computeIfAbsent(onlineAccountData.getTimestamp(), k -> ConcurrentHashMap.newKeySet());
+            if (onlineAccounts.contains(onlineAccountData))
+                // We have already validated this online account
+                continue;
+
             boolean isNewEntry = onlineAccountsImportQueue.add(onlineAccountData);
 
             if (isNewEntry)

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

@@ -4,6 +4,7 @@ import com.rust.litewalletjni.LiteWalletJni;
 import org.apache.commons.io.FileUtils;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.json.JSONException;
 import org.json.JSONObject;
 import org.qortal.arbitrary.ArbitraryDataFile;
 import org.qortal.arbitrary.ArbitraryDataReader;
@@ -99,14 +100,19 @@ public class PirateChainWalletController extends Thread {
                 LOGGER.debug("Syncing Pirate Chain wallet...");
                 String response = LiteWalletJni.execute("sync", "");
                 LOGGER.debug("sync response: {}", response);
-                JSONObject json = new JSONObject(response);
-                if (json.has("result")) {
-                    String result = json.getString("result");
 
-                    // We may have to set wallet to ready if this is the first ever successful sync
-                    if (Objects.equals(result, "success")) {
-                        this.currentWallet.setReady(true);
+                try {
+                    JSONObject json = new JSONObject(response);
+                    if (json.has("result")) {
+                        String result = json.getString("result");
+
+                        // We may have to set wallet to ready if this is the first ever successful sync
+                        if (Objects.equals(result, "success")) {
+                            this.currentWallet.setReady(true);
+                        }
                     }
+                } catch (JSONException e) {
+                    LOGGER.info("Unable to interpret JSON", e);
                 }
 
                 // Rate limit sync attempts

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

@@ -19,7 +19,6 @@ import org.qortal.block.BlockChain;
 import org.qortal.data.block.BlockData;
 import org.qortal.data.block.BlockSummaryData;
 import org.qortal.data.block.CommonBlockData;
-import org.qortal.data.network.PeerChainTipData;
 import org.qortal.data.transaction.RewardShareTransactionData;
 import org.qortal.data.transaction.TransactionData;
 import org.qortal.event.Event;
@@ -54,7 +53,8 @@ public class Synchronizer extends Thread {
 	/** Maximum number of block signatures we ask from peer in one go */
 	private static final int MAXIMUM_REQUEST_SIZE = 200; // XXX move to Settings?
 
-	private static final long RECOVERY_MODE_TIMEOUT = 10 * 60 * 1000L; // ms
+	/** Maximum number of consecutive failed sync attempts before marking peer as misbehaved */
+	private static final int MAX_CONSECUTIVE_FAILED_SYNC_ATTEMPTS = 3;
 
 
 	private boolean running;
@@ -76,6 +76,8 @@ public class Synchronizer extends Thread {
 	private volatile boolean isSynchronizing = false;
 	/** Temporary estimate of synchronization progress for SysTray use. */
 	private volatile int syncPercent = 0;
+	/** Temporary estimate of blocks remaining for SysTray use. */
+	private volatile int blocksRemaining = 0;
 
 	private static volatile boolean requestSync = false;
 	private boolean syncRequestPending = false;
@@ -181,6 +183,18 @@ public class Synchronizer extends Thread {
 		}
 	}
 
+	public Integer getBlocksRemaining() {
+		synchronized (this.syncLock) {
+			// Report as 0 blocks remaining if the latest block is within the last 60 mins
+			final Long minLatestBlockTimestamp = NTP.getTime() - (60 * 60 * 1000L);
+			if (Controller.getInstance().isUpToDate(minLatestBlockTimestamp)) {
+				return 0;
+			}
+
+			return this.isSynchronizing ? this.blocksRemaining : null;
+		}
+	}
+
 	public void requestSync() {
 		requestSync = true;
 	}
@@ -282,7 +296,7 @@ public class Synchronizer extends Thread {
 		BlockData priorChainTip = Controller.getInstance().getChainTip();
 
 		synchronized (this.syncLock) {
-			this.syncPercent = (priorChainTip.getHeight() * 100) / peer.getChainTipData().getLastHeight();
+			this.syncPercent = (priorChainTip.getHeight() * 100) / peer.getChainTipData().getHeight();
 
 			// Only update SysTray if we're potentially changing height
 			if (this.syncPercent < 100) {
@@ -312,7 +326,7 @@ public class Synchronizer extends Thread {
 
 				case INFERIOR_CHAIN: {
 					// Update our list of inferior chain tips
-					ByteArray inferiorChainSignature = ByteArray.wrap(peer.getChainTipData().getLastBlockSignature());
+					ByteArray inferiorChainSignature = ByteArray.wrap(peer.getChainTipData().getSignature());
 					if (!inferiorChainSignatures.contains(inferiorChainSignature))
 						inferiorChainSignatures.add(inferiorChainSignature);
 
@@ -320,7 +334,8 @@ public class Synchronizer extends Thread {
 					LOGGER.debug(() -> String.format("Refused to synchronize with peer %s (%s)", peer, syncResult.name()));
 
 					// Notify peer of our superior chain
-					if (!peer.sendMessage(Network.getInstance().buildHeightMessage(peer, priorChainTip)))
+					Message message = Network.getInstance().buildHeightOrChainTipInfo(peer);
+					if (message == null || !peer.sendMessage(message))
 						peer.disconnect("failed to notify peer of our superior chain");
 					break;
 				}
@@ -341,7 +356,7 @@ public class Synchronizer extends Thread {
 					// fall-through...
 				case NOTHING_TO_DO: {
 					// Update our list of inferior chain tips
-					ByteArray inferiorChainSignature = ByteArray.wrap(peer.getChainTipData().getLastBlockSignature());
+					ByteArray inferiorChainSignature = ByteArray.wrap(peer.getChainTipData().getSignature());
 					if (!inferiorChainSignatures.contains(inferiorChainSignature))
 						inferiorChainSignatures.add(inferiorChainSignature);
 
@@ -369,8 +384,7 @@ public class Synchronizer extends Thread {
 				// Reset our cache of inferior chains
 				inferiorChainSignatures.clear();
 
-				Network network = Network.getInstance();
-				network.broadcast(broadcastPeer -> network.buildHeightMessage(broadcastPeer, newChainTip));
+				Network.getInstance().broadcastOurChain();
 
 				EventBus.INSTANCE.notify(new NewChainTipEvent(priorChainTip, newChainTip));
 			}
@@ -397,9 +411,10 @@ public class Synchronizer extends Thread {
 					timePeersLastAvailable = NTP.getTime();
 
 				// If enough time has passed, enter recovery mode, which lifts some restrictions on who we can sync with and when we can mint
-				if (NTP.getTime() - timePeersLastAvailable > RECOVERY_MODE_TIMEOUT) {
+				long recoveryModeTimeout = Settings.getInstance().getRecoveryModeTimeout();
+				if (NTP.getTime() - timePeersLastAvailable > recoveryModeTimeout) {
 					if (recoveryMode == false) {
-						LOGGER.info(String.format("Peers have been unavailable for %d minutes. Entering recovery mode...", RECOVERY_MODE_TIMEOUT/60/1000));
+						LOGGER.info(String.format("Peers have been unavailable for %d minutes. Entering recovery mode...", recoveryModeTimeout/60/1000));
 						recoveryMode = true;
 					}
 				}
@@ -513,13 +528,13 @@ public class Synchronizer extends Thread {
 			final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
 			final int ourInitialHeight = ourLatestBlockData.getHeight();
 
-			PeerChainTipData peerChainTipData = peer.getChainTipData();
-			int peerHeight = peerChainTipData.getLastHeight();
-			byte[] peersLastBlockSignature = peerChainTipData.getLastBlockSignature();
+			BlockSummaryData peerChainTipData = peer.getChainTipData();
+			int peerHeight = peerChainTipData.getHeight();
+			byte[] peersLastBlockSignature = peerChainTipData.getSignature();
 
 			byte[] ourLastBlockSignature = ourLatestBlockData.getSignature();
 			LOGGER.debug(String.format("Fetching summaries from peer %s at height %d, sig %.8s, ts %d; our height %d, sig %.8s, ts %d", peer,
-					peerHeight, Base58.encode(peersLastBlockSignature), peer.getChainTipData().getLastBlockTimestamp(),
+					peerHeight, Base58.encode(peersLastBlockSignature), peerChainTipData.getTimestamp(),
 					ourInitialHeight, Base58.encode(ourLastBlockSignature), ourLatestBlockData.getTimestamp()));
 
 			List<BlockSummaryData> peerBlockSummaries = new ArrayList<>();
@@ -637,9 +652,9 @@ public class Synchronizer extends Thread {
 							return peers;
 
 						// Count the number of blocks this peer has beyond our common block
-						final PeerChainTipData peerChainTipData = peer.getChainTipData();
-						final int peerHeight = peerChainTipData.getLastHeight();
-						final byte[] peerLastBlockSignature = peerChainTipData.getLastBlockSignature();
+						final BlockSummaryData peerChainTipData = peer.getChainTipData();
+						final int peerHeight = peerChainTipData.getHeight();
+						final byte[] peerLastBlockSignature = peerChainTipData.getSignature();
 						final int peerAdditionalBlocksAfterCommonBlock = peerHeight - commonBlockSummary.getHeight();
 						// Limit the number of blocks we are comparing. FUTURE: we could request more in batches, but there may not be a case when this is needed
 						int summariesRequired = Math.min(peerAdditionalBlocksAfterCommonBlock, MAXIMUM_REQUEST_SIZE);
@@ -727,8 +742,9 @@ public class Synchronizer extends Thread {
 
 					LOGGER.debug(String.format("Listing peers with common block %.8s...", Base58.encode(commonBlockSummary.getSignature())));
 					for (Peer peer : peersSharingCommonBlock) {
-						final int peerHeight = peer.getChainTipData().getLastHeight();
-						final Long peerLastBlockTimestamp = peer.getChainTipData().getLastBlockTimestamp();
+						BlockSummaryData peerChainTipData = peer.getChainTipData();
+						final int peerHeight = peerChainTipData.getHeight();
+						final Long peerLastBlockTimestamp = peerChainTipData.getTimestamp();
 						final int peerAdditionalBlocksAfterCommonBlock = peerHeight - commonBlockSummary.getHeight();
 						final CommonBlockData peerCommonBlockData = peer.getCommonBlockData();
 
@@ -825,7 +841,7 @@ public class Synchronizer extends Thread {
 		// Calculate the length of the shortest peer chain sharing this common block
 		int minChainLength = 0;
 		for (Peer peer : peersSharingCommonBlock) {
-			final int peerHeight = peer.getChainTipData().getLastHeight();
+			final int peerHeight = peer.getChainTipData().getHeight();
 			final int peerAdditionalBlocksAfterCommonBlock = peerHeight - commonBlockSummary.getHeight();
 
 			if (peerAdditionalBlocksAfterCommonBlock < minChainLength || minChainLength == 0)
@@ -933,13 +949,13 @@ public class Synchronizer extends Thread {
 					final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
 					final int ourInitialHeight = ourLatestBlockData.getHeight();
 
-					PeerChainTipData peerChainTipData = peer.getChainTipData();
-					int peerHeight = peerChainTipData.getLastHeight();
-					byte[] peersLastBlockSignature = peerChainTipData.getLastBlockSignature();
+					BlockSummaryData peerChainTipData = peer.getChainTipData();
+					int peerHeight = peerChainTipData.getHeight();
+					byte[] peersLastBlockSignature = peerChainTipData.getSignature();
 
 					byte[] ourLastBlockSignature = ourLatestBlockData.getSignature();
 					String syncString = String.format("Synchronizing with peer %s at height %d, sig %.8s, ts %d; our height %d, sig %.8s, ts %d", peer,
-							peerHeight, Base58.encode(peersLastBlockSignature), peer.getChainTipData().getLastBlockTimestamp(),
+							peerHeight, Base58.encode(peersLastBlockSignature), peerChainTipData.getTimestamp(),
 							ourInitialHeight, Base58.encode(ourLastBlockSignature), ourLatestBlockData.getTimestamp());
 					LOGGER.info(syncString);
 
@@ -1246,7 +1262,14 @@ public class Synchronizer extends Thread {
 		int numberSignaturesRequired = additionalPeerBlocksAfterCommonBlock - peerBlockSignatures.size();
 
 		int retryCount = 0;
-		while (height < peerHeight) {
+
+		// Keep fetching blocks from peer until we reach their tip, or reach a count of MAXIMUM_COMMON_DELTA blocks.
+		// We need to limit the total number, otherwise too much can be loaded into memory, causing an
+		// OutOfMemoryException. This is common when syncing from 1000+ blocks behind the chain tip, after starting
+		// from a small fork that didn't become part of the main chain. This causes the entire sync process to
+		// use syncToPeerChain(), resulting in potentially thousands of blocks being held in memory if the limit
+		// below isn't applied.
+		while (height < peerHeight && peerBlocks.size() <= MAXIMUM_COMMON_DELTA) {
 			if (Controller.isStopping())
 				return SynchronizationResult.SHUTTING_DOWN;
 
@@ -1313,7 +1336,7 @@ public class Synchronizer extends Thread {
 			// Final check to make sure the peer isn't out of date (except for when we're in recovery mode)
 			if (!recoveryMode && peer.getChainTipData() != null) {
 				final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
-				final Long peerLastBlockTimestamp = peer.getChainTipData().getLastBlockTimestamp();
+				final Long peerLastBlockTimestamp = peer.getChainTipData().getTimestamp();
 				if (peerLastBlockTimestamp == null || peerLastBlockTimestamp < minLatestBlockTimestamp) {
 					LOGGER.info(String.format("Peer %s is out of date, so abandoning sync attempt", peer));
 					return SynchronizationResult.CHAIN_TIP_TOO_OLD;
@@ -1448,6 +1471,12 @@ public class Synchronizer extends Thread {
 
 			repository.saveChanges();
 
+			synchronized (this.syncLock) {
+				if (peer.getChainTipData() != null) {
+					this.blocksRemaining = peer.getChainTipData().getHeight() - newBlock.getBlockData().getHeight();
+				}
+			}
+
 			Controller.getInstance().onNewBlock(newBlock.getBlockData());
 		}
 
@@ -1543,6 +1572,12 @@ public class Synchronizer extends Thread {
 
 			repository.saveChanges();
 
+			synchronized (this.syncLock) {
+				if (peer.getChainTipData() != null) {
+					this.blocksRemaining = peer.getChainTipData().getHeight() - newBlock.getBlockData().getHeight();
+				}
+			}
+
 			Controller.getInstance().onNewBlock(newBlock.getBlockData());
 		}
 
@@ -1553,12 +1588,19 @@ public class Synchronizer extends Thread {
 		Message getBlockSummariesMessage = new GetBlockSummariesMessage(parentSignature, numberRequested);
 
 		Message message = peer.getResponse(getBlockSummariesMessage);
-		if (message == null || message.getType() != MessageType.BLOCK_SUMMARIES)
+		if (message == null)
 			return null;
 
-		BlockSummariesMessage blockSummariesMessage = (BlockSummariesMessage) message;
+		if (message.getType() == MessageType.BLOCK_SUMMARIES) {
+			BlockSummariesMessage blockSummariesMessage = (BlockSummariesMessage) message;
+			return blockSummariesMessage.getBlockSummaries();
+		}
+		else if (message.getType() == MessageType.BLOCK_SUMMARIES_V2) {
+			BlockSummariesV2Message blockSummariesMessage = (BlockSummariesV2Message) message;
+			return blockSummariesMessage.getBlockSummaries();
+		}
 
-		return blockSummariesMessage.getBlockSummaries();
+		return null;
 	}
 
 	private List<byte[]> getBlockSignatures(Peer peer, byte[] parentSignature, int numberRequested) throws InterruptedException {
@@ -1577,8 +1619,20 @@ public class Synchronizer extends Thread {
 		Message getBlockMessage = new GetBlockMessage(signature);
 
 		Message message = peer.getResponse(getBlockMessage);
-		if (message == null)
+		if (message == null) {
+			peer.getPeerData().incrementFailedSyncCount();
+			if (peer.getPeerData().getFailedSyncCount() >= MAX_CONSECUTIVE_FAILED_SYNC_ATTEMPTS) {
+				// Several failed attempts, so mark peer as misbehaved
+				LOGGER.info("Marking peer {} as misbehaved due to {} failed sync attempts", peer, peer.getPeerData().getFailedSyncCount());
+				Network.getInstance().peerMisbehaved(peer);
+			}
 			return null;
+		}
+
+		// Reset failed sync count now that we have a block response
+		// FUTURE: we could move this to the end of the sync process, but to reduce risk this can be done
+		// at a later stage. For now we are only defending against serialization errors or no responses.
+		peer.getPeerData().setFailedSyncCount(0);
 
 		switch (message.getType()) {
 			case BLOCK: {

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

@@ -595,9 +595,10 @@ public class ArbitraryDataFileManager extends Thread {
                 // Send valid, yet unexpected message type in response, so peer's synchronizer doesn't have to wait for timeout
                 LOGGER.debug(String.format("Sending 'file unknown' response to peer %s for GET_FILE request for unknown file %s", peer, arbitraryDataFile));
 
-                // We'll send empty block summaries message as it's very short
-                // TODO: use a different message type here
-                Message fileUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+                // Send generic 'unknown' message as it's very short
+                Message fileUnknownMessage = peer.getPeersVersion() >= GenericUnknownMessage.MINIMUM_PEER_VERSION
+                        ? new GenericUnknownMessage()
+                        : new BlockSummariesMessage(Collections.emptyList());
                 fileUnknownMessage.setId(message.getId());
                 if (!peer.sendMessage(fileUnknownMessage)) {
                     LOGGER.debug("Couldn't sent file-unknown response");

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

@@ -16,7 +16,7 @@ public class BlockArchiver implements Runnable {
 
 	private static final Logger LOGGER = LogManager.getLogger(BlockArchiver.class);
 
-	private static final long INITIAL_SLEEP_PERIOD = 0L; // TODO: 5 * 60 * 1000L + 1234L; // ms
+	private static final long INITIAL_SLEEP_PERIOD = 5 * 60 * 1000L + 1234L; // ms
 
 	public void run() {
 		Thread.currentThread().setName("Block archiver");

src/main/java/org/qortal/controller/tradebot/LitecoinACCTv3TradeBot.java

@@ -19,6 +19,7 @@ import org.qortal.data.transaction.MessageTransactionData;
 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.ValidationResult;
@@ -317,20 +318,27 @@ public class LitecoinACCTv3TradeBot implements AcctTradeBot {
 
 		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);
+			// Do this in a new thread so caller doesn't have to wait for computeNonce()
+			// In the unlikely event that the transaction doesn't validate then the buy won't happen and eventually Alice's AT will be refunded
+			new Thread(() -> {
+				try (final Repository threadsRepository = RepositoryManager.getRepository()) {
+					PrivateKeyAccount sender = new PrivateKeyAccount(threadsRepository, tradeBotData.getTradePrivateKey());
+					MessageTransaction messageTransaction = MessageTransaction.build(threadsRepository, sender, Group.NO_GROUP, messageRecipient, messageData, false, false);
 
-			messageTransaction.computeNonce();
-			messageTransaction.sign(sender);
+					messageTransaction.computeNonce();
+					messageTransaction.sign(sender);
 
-			// reset repository state to prevent deadlock
-			repository.discardChanges();
-			ValidationResult result = messageTransaction.importAsUnconfirmed();
+					// reset repository state to prevent deadlock
+					threadsRepository.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;
-			}
+					if (result != ValidationResult.OK) {
+						LOGGER.warn(() -> String.format("Unable to send MESSAGE to Bob's trade-bot %s: %s", messageRecipient, result.name()));
+					}
+				} catch (DataException e) {
+					LOGGER.warn(() -> String.format("Unable to send MESSAGE to Bob's trade-bot %s: %s", messageRecipient, e.getMessage()));
+				}
+			}, "TradeBot response").start();
 		}
 
 		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Funding P2SH-A %s. Messaged Bob. Waiting for AT-lock", p2shAddress));

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

@@ -468,9 +468,6 @@ public class TradeBot implements Listener {
 
 		List<TradePresenceData> safeTradePresences = List.copyOf(this.safeAllTradePresencesByPubkey.values());
 
-		if (safeTradePresences.isEmpty())
-			return;
-
 		LOGGER.debug("Broadcasting all {} known trade presences. Next broadcast timestamp: {}",
 				safeTradePresences.size(), nextTradePresenceBroadcastTimestamp
 		);
@@ -637,7 +634,7 @@ public class TradeBot implements Listener {
 		}
 
 		if (newCount > 0) {
-			LOGGER.debug("New trade presences: {}", newCount);
+			LOGGER.debug("New trade presences: {}, all trade presences: {}", newCount, allTradePresencesByPubkey.size());
 			rebuildSafeAllTradePresences();
 		}
 	}

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

@@ -99,6 +99,10 @@ public class MemoryPoW {
 	}
 
 	public static boolean verify2(byte[] data, int workBufferLength, long difficulty, int nonce) {
+		return verify2(data, null, workBufferLength, difficulty, nonce);
+	}
+
+	public static boolean verify2(byte[] data, long[] workBuffer, int workBufferLength, long difficulty, int nonce) {
 		// Hash data with SHA256
 		byte[] hash = Crypto.digest(data);
 
@@ -111,7 +115,10 @@ public class MemoryPoW {
 		byteBuffer = null;
 
 		int longBufferLength = workBufferLength / 8;
-		long[] workBuffer = new long[longBufferLength];
+
+		if (workBuffer == null)
+			workBuffer = new long[longBufferLength];
+
 		long[] state = new long[4];
 
 		long seed = 8682522807148012L;

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

@@ -24,7 +24,10 @@ public class ArbitraryResourceMetadata {
         this.description = description;
         this.tags = tags;
         this.category = category;
-        this.categoryName = category.getName();
+
+        if (category != null) {
+            this.categoryName = category.getName();
+        }
     }
 
     public static ArbitraryResourceMetadata fromTransactionMetadata(ArbitraryDataTransactionMetadata transactionMetadata) {

src/main/java/org/qortal/data/block/BlockSummaryData.java

@@ -11,11 +11,12 @@ public class BlockSummaryData {
 	private int height;
 	private byte[] signature;
 	private byte[] minterPublicKey;
-	private int onlineAccountsCount;
 
 	// Optional, set during construction
+	private Integer onlineAccountsCount;
 	private Long timestamp;
 	private Integer transactionCount;
+	private byte[] reference;
 
 	// Optional, set after construction
 	private Integer minterLevel;
@@ -25,6 +26,15 @@ public class BlockSummaryData {
 	protected BlockSummaryData() {
 	}
 
+	/** Constructor typically populated with fields from HeightV2Message */
+	public BlockSummaryData(int height, byte[] signature, byte[] minterPublicKey, long timestamp) {
+		this.height = height;
+		this.signature = signature;
+		this.minterPublicKey = minterPublicKey;
+		this.timestamp = timestamp;
+	}
+
+	/** Constructor typically populated with fields from BlockSummariesMessage */
 	public BlockSummaryData(int height, byte[] signature, byte[] minterPublicKey, int onlineAccountsCount) {
 		this.height = height;
 		this.signature = signature;
@@ -32,13 +42,16 @@ public class BlockSummaryData {
 		this.onlineAccountsCount = onlineAccountsCount;
 	}
 
-	public BlockSummaryData(int height, byte[] signature, byte[] minterPublicKey, int onlineAccountsCount, long timestamp, int transactionCount) {
+	/** Constructor typically populated with fields from BlockSummariesV2Message */
+	public BlockSummaryData(int height, byte[] signature, byte[] minterPublicKey, Integer onlineAccountsCount,
+							Long timestamp, Integer transactionCount, byte[] reference) {
 		this.height = height;
 		this.signature = signature;
 		this.minterPublicKey = minterPublicKey;
 		this.onlineAccountsCount = onlineAccountsCount;
 		this.timestamp = timestamp;
 		this.transactionCount = transactionCount;
+		this.reference = reference;
 	}
 
 	public BlockSummaryData(BlockData blockData) {
@@ -49,6 +62,7 @@ public class BlockSummaryData {
 
 		this.timestamp = blockData.getTimestamp();
 		this.transactionCount = blockData.getTransactionCount();
+		this.reference = blockData.getReference();
 	}
 
 	// Getters / setters
@@ -65,7 +79,7 @@ public class BlockSummaryData {
 		return this.minterPublicKey;
 	}
 
-	public int getOnlineAccountsCount() {
+	public Integer getOnlineAccountsCount() {
 		return this.onlineAccountsCount;
 	}
 
@@ -77,6 +91,10 @@ public class BlockSummaryData {
 		return this.transactionCount;
 	}
 
+	public byte[] getReference() {
+		return this.reference;
+	}
+
 	public Integer getMinterLevel() {
 		return this.minterLevel;
 	}

src/main/java/org/qortal/data/block/CommonBlockData.java

@@ -1,7 +1,5 @@
 package org.qortal.data.block;
 
-import org.qortal.data.network.PeerChainTipData;
-
 import javax.xml.bind.annotation.XmlAccessType;
 import javax.xml.bind.annotation.XmlAccessorType;
 import java.math.BigInteger;
@@ -14,14 +12,14 @@ public class CommonBlockData {
 	private BlockSummaryData commonBlockSummary = null;
 	private List<BlockSummaryData> blockSummariesAfterCommonBlock = null;
 	private BigInteger chainWeight = null;
-	private PeerChainTipData chainTipData = null;
+	private BlockSummaryData chainTipData = null;
 
 	// Constructors
 
 	protected CommonBlockData() {
 	}
 
-	public CommonBlockData(BlockSummaryData commonBlockSummary, PeerChainTipData chainTipData) {
+	public CommonBlockData(BlockSummaryData commonBlockSummary, BlockSummaryData chainTipData) {
 		this.commonBlockSummary = commonBlockSummary;
 		this.chainTipData = chainTipData;
 	}
@@ -49,7 +47,7 @@ public class CommonBlockData {
 		this.chainWeight = chainWeight;
 	}
 
-	public PeerChainTipData getChainTipData() {
+	public BlockSummaryData getChainTipData() {
 		return this.chainTipData;
 	}
 

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

@@ -1,37 +0,0 @@
-package org.qortal.data.network;
-
-public class PeerChainTipData {
-
-	/** Latest block height as reported by peer. */
-	private Integer lastHeight;
-	/** Latest block signature as reported by peer. */
-	private byte[] lastBlockSignature;
-	/** Latest block timestamp as reported by peer. */
-	private Long lastBlockTimestamp;
-	/** Latest block minter public key as reported by peer. */
-	private byte[] lastBlockMinter;
-
-	public PeerChainTipData(Integer lastHeight, byte[] lastBlockSignature, Long lastBlockTimestamp, byte[] lastBlockMinter) {
-		this.lastHeight = lastHeight;
-		this.lastBlockSignature = lastBlockSignature;
-		this.lastBlockTimestamp = lastBlockTimestamp;
-		this.lastBlockMinter = lastBlockMinter;
-	}
-
-	public Integer getLastHeight() {
-		return this.lastHeight;
-	}
-
-	public byte[] getLastBlockSignature() {
-		return this.lastBlockSignature;
-	}
-
-	public Long getLastBlockTimestamp() {
-		return this.lastBlockTimestamp;
-	}
-
-	public byte[] getLastBlockMinter() {
-		return this.lastBlockMinter;
-	}
-
-}

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

@@ -28,6 +28,9 @@ public class PeerData {
 	private Long addedWhen;
 	private String addedBy;
 
+	/** The number of consecutive times we failed to sync with this peer */
+	private int failedSyncCount = 0;
+
 	// Constructors
 
 	// necessary for JAXB serialization
@@ -92,6 +95,18 @@ public class PeerData {
 		return this.addedBy;
 	}
 
+	public int getFailedSyncCount() {
+		return this.failedSyncCount;
+	}
+
+	public void setFailedSyncCount(int failedSyncCount) {
+		this.failedSyncCount = failedSyncCount;
+	}
+
+	public void incrementFailedSyncCount() {
+		this.failedSyncCount++;
+	}
+
 	// Pretty peerAddress getter for JAXB
 	@XmlElement(name = "address")
 	protected String getPrettyAddress() {

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

@@ -128,6 +128,10 @@ public abstract class TransactionData {
 		return this.txGroupId;
 	}
 
+	public void setTxGroupId(int txGroupId) {
+		this.txGroupId = txGroupId;
+	}
+
 	public byte[] getReference() {
 		return this.reference;
 	}

src/main/java/org/qortal/group/Group.java

@@ -80,6 +80,9 @@ public class Group {
 	// Useful constants
 	public static final int NO_GROUP = 0;
 
+	// Null owner address corresponds with public key "11111111111111111111111111111111"
+	public static String NULL_OWNER_ADDRESS = "QdSnUy6sUiEnaN87dWmE92g1uQjrvPgrWG";
+
 	public static final int MIN_NAME_SIZE = 3;
 	public static final int MAX_NAME_SIZE = 32;
 	public static final int MAX_DESCRIPTION_SIZE = 128;

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

@@ -11,6 +11,7 @@ import org.qortal.controller.arbitrary.ArbitraryDataFileListManager;
 import org.qortal.controller.arbitrary.ArbitraryDataManager;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.block.BlockData;
+import org.qortal.data.block.BlockSummaryData;
 import org.qortal.data.network.PeerData;
 import org.qortal.data.transaction.TransactionData;
 import org.qortal.network.message.*;
@@ -90,6 +91,8 @@ public class Network {
 
     private static final long DISCONNECTION_CHECK_INTERVAL = 10 * 1000L; // milliseconds
 
+    private static final int BROADCAST_CHAIN_TIP_DEPTH = 7; // Just enough to fill a SINGLE TCP packet (~1440 bytes)
+
     // Generate our node keys / ID
     private final Ed25519PrivateKeyParameters edPrivateKeyParams = new Ed25519PrivateKeyParameters(new SecureRandom());
     private final Ed25519PublicKeyParameters edPublicKeyParams = edPrivateKeyParams.generatePublicKey();
@@ -1087,10 +1090,16 @@ public class Network {
 
         if (peer.isOutbound()) {
             if (!Settings.getInstance().isLite()) {
-                // Send our height
-                Message heightMessage = buildHeightMessage(peer, Controller.getInstance().getChainTip());
-                if (!peer.sendMessage(heightMessage)) {
-                    peer.disconnect("failed to send height/info");
+                // Send our height / chain tip info
+                Message message = this.buildHeightOrChainTipInfo(peer);
+
+                if (message == null) {
+                    peer.disconnect("Couldn't build our chain tip info");
+                    return;
+                }
+
+                if (!peer.sendMessage(message)) {
+                    peer.disconnect("failed to send height / chain tip info");
                     return;
                 }
             }
@@ -1164,10 +1173,47 @@ public class Network {
         return new PeersV2Message(peerAddresses);
     }
 
-    public Message buildHeightMessage(Peer peer, BlockData blockData) {
-        // HEIGHT_V2 contains way more useful info
-        return new HeightV2Message(blockData.getHeight(), blockData.getSignature(),
-                blockData.getTimestamp(), blockData.getMinterPublicKey());
+    /** Builds either (legacy) HeightV2Message or (newer) BlockSummariesV2Message, depending on peer version.
+     *
+     *  @return Message, or null if DataException was thrown.
+     */
+    public Message buildHeightOrChainTipInfo(Peer peer) {
+        if (peer.getPeersVersion() >= BlockSummariesV2Message.MINIMUM_PEER_VERSION) {
+            int latestHeight = Controller.getInstance().getChainHeight();
+
+            try (final Repository repository = RepositoryManager.getRepository()) {
+                List<BlockSummaryData> latestBlockSummaries = repository.getBlockRepository().getBlockSummaries(latestHeight - BROADCAST_CHAIN_TIP_DEPTH, latestHeight);
+                return new BlockSummariesV2Message(latestBlockSummaries);
+            } catch (DataException e) {
+                return null;
+            }
+        } else {
+            // For older peers
+            BlockData latestBlockData = Controller.getInstance().getChainTip();
+            return new HeightV2Message(latestBlockData.getHeight(), latestBlockData.getSignature(),
+                    latestBlockData.getTimestamp(), latestBlockData.getMinterPublicKey());
+        }
+    }
+
+    public void broadcastOurChain() {
+        BlockData latestBlockData = Controller.getInstance().getChainTip();
+        int latestHeight = latestBlockData.getHeight();
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            List<BlockSummaryData> latestBlockSummaries = repository.getBlockRepository().getBlockSummaries(latestHeight - BROADCAST_CHAIN_TIP_DEPTH, latestHeight);
+            Message latestBlockSummariesMessage = new BlockSummariesV2Message(latestBlockSummaries);
+
+            // For older peers
+            Message heightMessage = new HeightV2Message(latestBlockData.getHeight(), latestBlockData.getSignature(),
+                    latestBlockData.getTimestamp(), latestBlockData.getMinterPublicKey());
+
+            Network.getInstance().broadcast(broadcastPeer -> broadcastPeer.getPeersVersion() >= BlockSummariesV2Message.MINIMUM_PEER_VERSION
+                    ? latestBlockSummariesMessage
+                    : heightMessage
+            );
+        } catch (DataException e) {
+            LOGGER.warn("Couldn't broadcast our chain tip info", e);
+        }
     }
 
     public Message buildNewTransactionMessage(Peer peer, TransactionData transactionData) {

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

@@ -6,8 +6,8 @@ import com.google.common.net.InetAddresses;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.controller.Controller;
+import org.qortal.data.block.BlockSummaryData;
 import org.qortal.data.block.CommonBlockData;
-import org.qortal.data.network.PeerChainTipData;
 import org.qortal.data.network.PeerData;
 import org.qortal.network.message.ChallengeMessage;
 import org.qortal.network.message.Message;
@@ -148,7 +148,7 @@ public class Peer {
     /**
      * Latest block info as reported by peer.
      */
-    private PeerChainTipData peersChainTipData;
+    private List<BlockSummaryData> peersChainTipData = Collections.emptyList();
 
     /**
      * Our common block with this peer
@@ -353,28 +353,34 @@ public class Peer {
         }
     }
 
-    public PeerChainTipData getChainTipData() {
-        synchronized (this.peerInfoLock) {
-            return this.peersChainTipData;
-        }
+    public BlockSummaryData getChainTipData() {
+        List<BlockSummaryData> chainTipSummaries = this.peersChainTipData;
+
+        if (chainTipSummaries.isEmpty())
+            return null;
+
+        // Return last entry, which should have greatest height
+        return chainTipSummaries.get(chainTipSummaries.size() - 1);
     }
 
-    public void setChainTipData(PeerChainTipData chainTipData) {
-        synchronized (this.peerInfoLock) {
-            this.peersChainTipData = chainTipData;
-        }
+    public void setChainTipData(BlockSummaryData chainTipData) {
+        this.peersChainTipData = Collections.singletonList(chainTipData);
+    }
+
+    public List<BlockSummaryData> getChainTipSummaries() {
+        return this.peersChainTipData;
+    }
+
+    public void setChainTipSummaries(List<BlockSummaryData> chainTipSummaries) {
+        this.peersChainTipData = List.copyOf(chainTipSummaries);
     }
 
     public CommonBlockData getCommonBlockData() {
-        synchronized (this.peerInfoLock) {
-            return this.commonBlockData;
-        }
+        return this.commonBlockData;
     }
 
     public void setCommonBlockData(CommonBlockData commonBlockData) {
-        synchronized (this.peerInfoLock) {
-            this.commonBlockData = commonBlockData;
-        }
+        this.commonBlockData = commonBlockData;
     }
 
     public boolean isSyncInProgress() {
@@ -904,20 +910,22 @@ public class Peer {
     // Common block data
 
     public boolean canUseCachedCommonBlockData() {
-        PeerChainTipData peerChainTipData = this.getChainTipData();
-        CommonBlockData commonBlockData = this.getCommonBlockData();
+        BlockSummaryData peerChainTipData = this.getChainTipData();
+        if (peerChainTipData == null || peerChainTipData.getSignature() == null)
+            return false;
 
-        if (peerChainTipData != null && commonBlockData != null) {
-            PeerChainTipData commonBlockChainTipData = commonBlockData.getChainTipData();
-            if (peerChainTipData.getLastBlockSignature() != null && commonBlockChainTipData != null
-                    && commonBlockChainTipData.getLastBlockSignature() != null) {
-                if (Arrays.equals(peerChainTipData.getLastBlockSignature(),
-                        commonBlockChainTipData.getLastBlockSignature())) {
-                    return true;
-                }
-            }
-        }
-        return false;
+        CommonBlockData commonBlockData = this.getCommonBlockData();
+        if (commonBlockData == null)
+            return false;
+
+        BlockSummaryData commonBlockChainTipData = commonBlockData.getChainTipData();
+        if (commonBlockChainTipData == null || commonBlockChainTipData.getSignature() == null)
+            return false;
+
+        if (!Arrays.equals(peerChainTipData.getSignature(), commonBlockChainTipData.getSignature()))
+            return false;
+
+        return true;
     }
 
 

src/main/java/org/qortal/network/message/BlockSummariesV2Message.java

@@ -0,0 +1,109 @@
+package org.qortal.network.message;
+
+import com.google.common.primitives.Ints;
+import com.google.common.primitives.Longs;
+import org.qortal.data.block.BlockSummaryData;
+import org.qortal.transform.Transformer;
+import org.qortal.transform.block.BlockTransformer;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.BufferUnderflowException;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.List;
+
+public class BlockSummariesV2Message extends Message {
+
+	public static final long MINIMUM_PEER_VERSION = 0x0300060001L;
+
+	private static final int BLOCK_SUMMARY_V2_LENGTH = BlockTransformer.BLOCK_SIGNATURE_LENGTH /* block signature */
+			+ Transformer.PUBLIC_KEY_LENGTH /* minter public key */
+			+ Transformer.INT_LENGTH /* online accounts count */
+			+ Transformer.LONG_LENGTH /* block timestamp */
+			+ Transformer.INT_LENGTH /* transactions count */
+			+ BlockTransformer.BLOCK_SIGNATURE_LENGTH; /* block reference */
+
+	private List<BlockSummaryData> blockSummaries;
+
+	public BlockSummariesV2Message(List<BlockSummaryData> blockSummaries) {
+		super(MessageType.BLOCK_SUMMARIES_V2);
+
+		// Shortcut for when there are no summaries
+		if (blockSummaries.isEmpty()) {
+			this.dataBytes = Message.EMPTY_DATA_BYTES;
+			return;
+		}
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			// First summary's height
+			bytes.write(Ints.toByteArray(blockSummaries.get(0).getHeight()));
+
+			for (BlockSummaryData blockSummary : blockSummaries) {
+				bytes.write(blockSummary.getSignature());
+				bytes.write(blockSummary.getMinterPublicKey());
+				bytes.write(Ints.toByteArray(blockSummary.getOnlineAccountsCount()));
+				bytes.write(Longs.toByteArray(blockSummary.getTimestamp()));
+				bytes.write(Ints.toByteArray(blockSummary.getTransactionCount()));
+				bytes.write(blockSummary.getReference());
+			}
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
+
+	private BlockSummariesV2Message(int id, List<BlockSummaryData> blockSummaries) {
+		super(id, MessageType.BLOCK_SUMMARIES_V2);
+
+		this.blockSummaries = blockSummaries;
+	}
+
+	public List<BlockSummaryData> getBlockSummaries() {
+		return this.blockSummaries;
+	}
+
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
+		List<BlockSummaryData> blockSummaries = new ArrayList<>();
+
+		// If there are no bytes remaining then we can treat this as an empty array of summaries
+		if (bytes.remaining() == 0)
+			return new BlockSummariesV2Message(id, blockSummaries);
+
+		int height = bytes.getInt();
+
+		// Expecting bytes remaining to be exact multiples of BLOCK_SUMMARY_V2_LENGTH
+		if (bytes.remaining() % BLOCK_SUMMARY_V2_LENGTH != 0)
+			throw new BufferUnderflowException();
+
+		while (bytes.hasRemaining()) {
+			byte[] signature = new byte[BlockTransformer.BLOCK_SIGNATURE_LENGTH];
+			bytes.get(signature);
+
+			byte[] minterPublicKey = new byte[Transformer.PUBLIC_KEY_LENGTH];
+			bytes.get(minterPublicKey);
+
+			int onlineAccountsCount = bytes.getInt();
+
+			long timestamp = bytes.getLong();
+
+			int transactionsCount = bytes.getInt();
+
+			byte[] reference = new byte[BlockTransformer.BLOCK_SIGNATURE_LENGTH];
+			bytes.get(reference);
+
+			BlockSummaryData blockSummary = new BlockSummaryData(height, signature, minterPublicKey,
+					onlineAccountsCount, timestamp, transactionsCount, reference);
+			blockSummaries.add(blockSummary);
+
+			height++;
+		}
+
+		return new BlockSummariesV2Message(id, blockSummaries);
+	}
+
+}

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

@@ -0,0 +1,23 @@
+package org.qortal.network.message;
+
+import java.nio.ByteBuffer;
+
+public class GenericUnknownMessage extends Message {
+
+    public static final long MINIMUM_PEER_VERSION = 0x0300060001L;
+
+    public GenericUnknownMessage() {
+        super(MessageType.GENERIC_UNKNOWN);
+
+        this.dataBytes = EMPTY_DATA_BYTES;
+    }
+
+    private GenericUnknownMessage(int id) {
+        super(id, MessageType.GENERIC_UNKNOWN);
+    }
+
+    public static Message fromByteBuffer(int id, ByteBuffer bytes) {
+        return new GenericUnknownMessage(id);
+    }
+
+}

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

@@ -21,6 +21,7 @@ public enum MessageType {
     HEIGHT_V2(10, HeightV2Message::fromByteBuffer),
     PING(11, PingMessage::fromByteBuffer),
     PONG(12, PongMessage::fromByteBuffer),
+    GENERIC_UNKNOWN(13, GenericUnknownMessage::fromByteBuffer),
 
     // Requesting data
     PEERS_V2(20, PeersV2Message::fromByteBuffer),
@@ -41,6 +42,7 @@ public enum MessageType {
 
     BLOCK_SUMMARIES(70, BlockSummariesMessage::fromByteBuffer),
     GET_BLOCK_SUMMARIES(71, GetBlockSummariesMessage::fromByteBuffer),
+    BLOCK_SUMMARIES_V2(72, BlockSummariesV2Message::fromByteBuffer),
 
     ONLINE_ACCOUNTS(80, OnlineAccountsMessage::fromByteBuffer),
     GET_ONLINE_ACCOUNTS(81, GetOnlineAccountsMessage::fromByteBuffer),

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

@@ -14,7 +14,7 @@ public interface ChatRepository {
 	 * Expects EITHER non-null txGroupID OR non-null sender and recipient addresses.
 	 */
 	public List<ChatMessage> getMessagesMatchingCriteria(Long before, Long after,
-			Integer txGroupId, List<String> involving,
+			Integer txGroupId, byte[] reference, List<String> involving,
 			Integer limit, Integer offset, Boolean reverse) throws DataException;
 
 	public ChatMessage toChatMessage(ChatTransactionData chatTransactionData) throws DataException;

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

@@ -143,13 +143,17 @@ public class HSQLDBBlockArchiveRepository implements BlockArchiveRepository {
                 byte[] blockMinterPublicKey = resultSet.getBytes(3);
 
                 // Fetch additional info from the archive itself
-                int onlineAccountsCount = 0;
+                Integer onlineAccountsCount = null;
+                Long timestamp = null;
+                Integer transactionCount = null;
+                byte[] reference = null;
+
                 BlockData blockData = this.fromSignature(signature);
                 if (blockData != null) {
                     onlineAccountsCount = blockData.getOnlineAccountsCount();
                 }
 
-                BlockSummaryData blockSummary = new BlockSummaryData(height, signature, blockMinterPublicKey, onlineAccountsCount);
+                BlockSummaryData blockSummary = new BlockSummaryData(height, signature, blockMinterPublicKey, onlineAccountsCount, timestamp, transactionCount, reference);
                 blockSummaries.add(blockSummary);
             } while (resultSet.next());
 

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

@@ -297,7 +297,7 @@ public class HSQLDBBlockRepository implements BlockRepository {
 	@Override
 	public List<BlockSummaryData> getBlockSummariesBySigner(byte[] signerPublicKey, Integer limit, Integer offset, Boolean reverse) throws DataException {
 		StringBuilder sql = new StringBuilder(512);
-		sql.append("SELECT signature, height, Blocks.minter, online_accounts_count FROM ");
+		sql.append("SELECT signature, height, Blocks.minter, online_accounts_count, minted_when, transaction_count, Blocks.reference FROM ");
 
 		// List of minter account's public key and reward-share public keys with minter's public key
 		sql.append("(SELECT * FROM (VALUES (CAST(? AS QortalPublicKey))) UNION (SELECT reward_share_public_key FROM RewardShares WHERE minter_public_key = ?)) AS PublicKeys (public_key) ");
@@ -322,8 +322,12 @@ public class HSQLDBBlockRepository implements BlockRepository {
 				int height = resultSet.getInt(2);
 				byte[] blockMinterPublicKey = resultSet.getBytes(3);
 				int onlineAccountsCount = resultSet.getInt(4);
+				long timestamp = resultSet.getLong(5);
+				int transactionCount = resultSet.getInt(6);
+				byte[] reference = resultSet.getBytes(7);
 
-				BlockSummaryData blockSummary = new BlockSummaryData(height, signature, blockMinterPublicKey, onlineAccountsCount);
+				BlockSummaryData blockSummary = new BlockSummaryData(height, signature, blockMinterPublicKey, onlineAccountsCount,
+						timestamp, transactionCount, reference);
 				blockSummaries.add(blockSummary);
 			} while (resultSet.next());
 
@@ -355,7 +359,7 @@ public class HSQLDBBlockRepository implements BlockRepository {
 
 	@Override
 	public List<BlockSummaryData> getBlockSummaries(int firstBlockHeight, int lastBlockHeight) throws DataException {
-		String sql = "SELECT signature, height, minter, online_accounts_count, minted_when, transaction_count "
+		String sql = "SELECT signature, height, minter, online_accounts_count, minted_when, transaction_count, reference "
 				+ "FROM Blocks WHERE height BETWEEN ? AND ?";
 
 		List<BlockSummaryData> blockSummaries = new ArrayList<>();
@@ -371,9 +375,10 @@ public class HSQLDBBlockRepository implements BlockRepository {
 				int onlineAccountsCount = resultSet.getInt(4);
 				long timestamp = resultSet.getLong(5);
 				int transactionCount = resultSet.getInt(6);
+				byte[] reference = resultSet.getBytes(7);
 
 				BlockSummaryData blockSummary = new BlockSummaryData(height, signature, minterPublicKey, onlineAccountsCount,
-						timestamp, transactionCount);
+						timestamp, transactionCount, reference);
 				blockSummaries.add(blockSummary);
 			} while (resultSet.next());
 

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

@@ -23,7 +23,7 @@ public class HSQLDBChatRepository implements ChatRepository {
 	}
 
 	@Override
-	public List<ChatMessage> getMessagesMatchingCriteria(Long before, Long after, Integer txGroupId,
+	public List<ChatMessage> getMessagesMatchingCriteria(Long before, Long after, Integer txGroupId, byte[] referenceBytes,
 			List<String> involving, Integer limit, Integer offset, Boolean reverse)
 			throws DataException {
 		// Check args meet expectations
@@ -57,6 +57,11 @@ public class HSQLDBChatRepository implements ChatRepository {
 			bindParams.add(after);
 		}
 
+		if (referenceBytes != null) {
+			whereClauses.add("reference = ?");
+			bindParams.add(referenceBytes);
+		}
+
 		if (txGroupId != null) {
 			whereClauses.add("tx_group_id = " + txGroupId); // int safe to use literally
 			whereClauses.add("recipient IS NULL");

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

@@ -184,6 +184,8 @@ public class Settings {
 
 	// Peer-to-peer related
 	private boolean isTestNet = false;
+	/** Single node testnet mode */
+	private boolean singleNodeTestnet = false;
 	/** Port number for inbound peer-to-peer connections. */
 	private Integer listenPort;
 	/** Whether to attempt to open the listen port via UPnP */
@@ -203,8 +205,11 @@ public class Settings {
 	/** Maximum number of retry attempts if a peer fails to respond with the requested data */
 	private int maxRetries = 2;
 
+	/** The number of seconds of no activity before recovery mode begins */
+	public long recoveryModeTimeout = 10 * 60 * 1000L;
+
 	/** Minimum peer version number required in order to sync with them */
-	private String minPeerVersion = "3.3.7";
+	private String minPeerVersion = "3.6.3";
 	/** 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
 	 * If false, sync will be blocked both ways, and they will not appear in the peers list */
@@ -290,10 +295,6 @@ public class Settings {
 	/** Additional offset added to values returned by NTP.getTime() */
 	private Long testNtpOffset = null;
 
-	// Online accounts
-
-	/** Whether to opt-in to mempow computations for online accounts, ahead of general release */
-	private boolean onlineAccountsMemPoWEnabled = false;
 
 
 	/* Foreign chains */
@@ -490,7 +491,7 @@ public class Settings {
 
 	private void validate() {
 		// Validation goes here
-		if (this.minBlockchainPeers < 1)
+		if (this.minBlockchainPeers < 1 && !singleNodeTestnet)
 			throwValidationError("minBlockchainPeers must be at least 1");
 
 		if (this.apiKey != null && this.apiKey.trim().length() < 8)
@@ -647,6 +648,10 @@ public class Settings {
 		return this.isTestNet;
 	}
 
+	public boolean isSingleNodeTestnet() {
+		return this.singleNodeTestnet;
+	}
+
 	public int getListenPort() {
 		if (this.listenPort != null)
 			return this.listenPort;
@@ -667,6 +672,9 @@ public class Settings {
 	}
 
 	public int getMinBlockchainPeers() {
+		if (singleNodeTestnet)
+			return 0;
+
 		return this.minBlockchainPeers;
 	}
 
@@ -692,6 +700,10 @@ public class Settings {
 
 	public int getMaxRetries() { return this.maxRetries; }
 
+	public long getRecoveryModeTimeout() {
+		return recoveryModeTimeout;
+	}
+
 	public String getMinPeerVersion() { return this.minPeerVersion; }
 
 	public boolean getAllowConnectionsWithOlderPeerVersions() { return this.allowConnectionsWithOlderPeerVersions; }
@@ -800,10 +812,6 @@ public class Settings {
 		return this.testNtpOffset;
 	}
 
-	public boolean isOnlineAccountsMemPoWEnabled() {
-		return this.onlineAccountsMemPoWEnabled;
-	}
-
 	public long getRepositoryBackupInterval() {
 		return this.repositoryBackupInterval;
 	}

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

@@ -2,6 +2,7 @@ package org.qortal.transaction;
 
 import java.util.Collections;
 import java.util.List;
+import java.util.Objects;
 
 import org.qortal.account.Account;
 import org.qortal.asset.Asset;
@@ -64,15 +65,24 @@ public class AddGroupAdminTransaction extends Transaction {
 
 		Account owner = getOwner();
 		String groupOwner = this.repository.getGroupRepository().getOwner(groupId);
+		boolean groupOwnedByNullAccount = Objects.equals(groupOwner, Group.NULL_OWNER_ADDRESS);
 
-		// Check transaction's public key matches group's current owner
-		if (!owner.getAddress().equals(groupOwner))
+		// Require approval if transaction relates to a group owned by the null account
+		if (groupOwnedByNullAccount && !this.needsGroupApproval())
+			return ValidationResult.GROUP_APPROVAL_REQUIRED;
+
+		// Check transaction's public key matches group's current owner (except for groups owned by the null account)
+		if (!groupOwnedByNullAccount && !owner.getAddress().equals(groupOwner))
 			return ValidationResult.INVALID_GROUP_OWNER;
 
 		// Check address is a group member
 		if (!this.repository.getGroupRepository().memberExists(groupId, memberAddress))
 			return ValidationResult.NOT_GROUP_MEMBER;
 
+		// Check transaction creator is a group member
+		if (!this.repository.getGroupRepository().memberExists(groupId, this.getCreator().getAddress()))
+			return ValidationResult.NOT_GROUP_MEMBER;
+
 		// Check group member is not already an admin
 		if (this.repository.getGroupRepository().adminExists(groupId, memberAddress))
 			return ValidationResult.ALREADY_GROUP_ADMIN;

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

@@ -2,6 +2,7 @@ package org.qortal.transaction;
 
 import java.util.Collections;
 import java.util.List;
+import java.util.Objects;
 
 import org.qortal.account.Account;
 import org.qortal.asset.Asset;
@@ -65,11 +66,21 @@ public class RemoveGroupAdminTransaction extends Transaction {
 			return ValidationResult.GROUP_DOES_NOT_EXIST;
 
 		Account owner = getOwner();
+		String groupOwner = this.repository.getGroupRepository().getOwner(groupId);
+		boolean groupOwnedByNullAccount = Objects.equals(groupOwner, Group.NULL_OWNER_ADDRESS);
 
-		// Check transaction's public key matches group's current owner
-		if (!owner.getAddress().equals(groupData.getOwner()))
+		// Require approval if transaction relates to a group owned by the null account
+		if (groupOwnedByNullAccount && !this.needsGroupApproval())
+			return ValidationResult.GROUP_APPROVAL_REQUIRED;
+
+		// Check transaction's public key matches group's current owner (except for groups owned by the null account)
+		if (!groupOwnedByNullAccount && !owner.getAddress().equals(groupOwner))
 			return ValidationResult.INVALID_GROUP_OWNER;
 
+		// Check transaction creator is a group member
+		if (!this.repository.getGroupRepository().memberExists(groupId, this.getCreator().getAddress()))
+			return ValidationResult.NOT_GROUP_MEMBER;
+
 		Account admin = getAdmin();
 
 		// Check member is an admin

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

@@ -1,13 +1,7 @@
 package org.qortal.transaction;
 
 import java.math.BigInteger;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Comparator;
-import java.util.EnumSet;
-import java.util.Iterator;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Predicate;
 
@@ -69,8 +63,8 @@ public abstract class Transaction {
 		AT(21, false),
 		CREATE_GROUP(22, true),
 		UPDATE_GROUP(23, true),
-		ADD_GROUP_ADMIN(24, false),
-		REMOVE_GROUP_ADMIN(25, false),
+		ADD_GROUP_ADMIN(24, true),
+		REMOVE_GROUP_ADMIN(25, true),
 		GROUP_BAN(26, false),
 		CANCEL_GROUP_BAN(27, false),
 		GROUP_KICK(28, false),
@@ -250,6 +244,7 @@ public abstract class Transaction {
 		INVALID_TIMESTAMP_SIGNATURE(95),
 		ADDRESS_BLOCKED(96),
 		NAME_BLOCKED(97),
+		GROUP_APPROVAL_REQUIRED(98),
 		INVALID_BUT_OK(999),
 		NOT_YET_RELEASED(1000);
 
@@ -760,9 +755,13 @@ public abstract class Transaction {
 			// Group no longer exists? Possibly due to blockchain orphaning undoing group creation?
 			return true; // stops tx being included in block but it will eventually expire
 
+		String groupOwner = this.repository.getGroupRepository().getOwner(txGroupId);
+		boolean groupOwnedByNullAccount = Objects.equals(groupOwner, Group.NULL_OWNER_ADDRESS);
+
 		// If transaction's creator is group admin (of group with ID txGroupId) then auto-approve
+		// This is disabled for null-owned groups, since these require approval from other admins
 		PublicKeyAccount creator = this.getCreator();
-		if (groupRepository.adminExists(txGroupId, creator.getAddress()))
+		if (!groupOwnedByNullAccount && groupRepository.adminExists(txGroupId, creator.getAddress()))
 			return false;
 
 		return true;

src/main/java/org/qortal/transform/block/BlockTransformer.java

@@ -235,7 +235,7 @@ public class BlockTransformer extends Transformer {
 			// Online accounts timestamp is only present if there are also signatures
 			onlineAccountsTimestamp = byteBuffer.getLong();
 
-			final int signaturesByteLength = getOnlineAccountSignaturesLength(onlineAccountsSignaturesCount, onlineAccountsCount, timestamp);
+			final int signaturesByteLength = (onlineAccountsSignaturesCount * Transformer.SIGNATURE_LENGTH) + (onlineAccountsCount * INT_LENGTH);
 			if (signaturesByteLength > BlockChain.getInstance().getMaxBlockSize())
 				throw new TransformationException("Byte data too long for online accounts signatures");
 
@@ -511,16 +511,6 @@ public class BlockTransformer extends Transformer {
 
 		return nonces;
 	}
-	public static int getOnlineAccountSignaturesLength(int onlineAccountsSignaturesCount, int onlineAccountCount, long blockTimestamp) {
-		if (blockTimestamp >= BlockChain.getInstance().getOnlineAccountsMemoryPoWTimestamp()) {
-			// Once mempow is active, we expect the online account signatures to be appended with the nonce values
-			return (onlineAccountsSignaturesCount * Transformer.SIGNATURE_LENGTH) + (onlineAccountCount * INT_LENGTH);
-		}
-		else {
-			// Before mempow, only the online account signatures were included (which will likely be a single signature)
-			return onlineAccountsSignaturesCount * Transformer.SIGNATURE_LENGTH;
-		}
-	}
 
 	public static byte[] extract(byte[] input, int pos, int length) {
 		byte[] output = new byte[length];

src/main/resources/blockchain.json

@@ -24,7 +24,6 @@
 	"onlineAccountSignaturesMinLifetime": 43200000,
 	"onlineAccountSignaturesMaxLifetime": 86400000,
 	"onlineAccountsModulusV2Timestamp": 1659801600000,
-	"onlineAccountsMemoryPoWTimestamp": 9999999999999,
 	"rewardsByHeight": [
 		{ "height": 1, "reward": 5.00 },
 		{ "height": 259201, "reward": 4.75 },
@@ -80,7 +79,8 @@
 		"calcChainWeightTimestamp": 1620579600000,
 		"transactionV5Timestamp": 1642176000000,
 		"transactionV6Timestamp": 9999999999999,
-		"disableReferenceTimestamp": 1655222400000
+		"disableReferenceTimestamp": 1655222400000,
+		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999
 	},
 	"genesisInfo": {
 		"version": 4,

src/main/resources/i18n/SysTray_de.properties

@@ -7,6 +7,8 @@ AUTO_UPDATE = Automatisches Update
 
 BLOCK_HEIGHT = height
 
+BLOCKS_REMAINING = blocks remaining
+
 BUILD_VERSION = Build-Version
 
 CHECK_TIME_ACCURACY = Prüfe Zeitgenauigkeit

src/main/resources/i18n/SysTray_en.properties

@@ -7,6 +7,8 @@ AUTO_UPDATE = Auto Update
 
 BLOCK_HEIGHT = height
 
+BLOCKS_REMAINING = blocks remaining
+
 BUILD_VERSION = Build version
 
 CHECK_TIME_ACCURACY = Check time accuracy

src/main/resources/i18n/SysTray_es.properties

@@ -7,6 +7,8 @@ AUTO_UPDATE = Actualización automática
 
 BLOCK_HEIGHT = altura
 
+BLOCKS_REMAINING = blocks remaining
+
 BUILD_VERSION = Versión de compilación
 
 CHECK_TIME_ACCURACY = Comprobar la precisión del tiempo

src/main/resources/i18n/SysTray_fi.properties

@@ -7,6 +7,8 @@ AUTO_UPDATE = Automaattinen päivitys
 
 BLOCK_HEIGHT = korkeus
 
+BLOCKS_REMAINING = blocks remaining
+
 BUILD_VERSION = Versio
 
 CHECK_TIME_ACCURACY = Tarkista ajan tarkkuus

src/main/resources/i18n/SysTray_fr.properties

@@ -7,6 +7,8 @@ AUTO_UPDATE = Mise à jour automatique
 
 BLOCK_HEIGHT = hauteur
 
+BLOCKS_REMAINING = blocks remaining
+
 BUILD_VERSION = Numéro de version
 
 CHECK_TIME_ACCURACY = Vérifier l'heure

src/main/resources/i18n/SysTray_hu.properties

@@ -7,6 +7,8 @@ AUTO_UPDATE = Automatikus Frissítés
 
 BLOCK_HEIGHT = blokkmagasság
 
+BLOCKS_REMAINING = blocks remaining
+
 BUILD_VERSION = Verzió
 
 CHECK_TIME_ACCURACY = Óra pontosságának ellenőrzése

src/main/resources/i18n/SysTray_it.properties

@@ -7,6 +7,8 @@ AUTO_UPDATE = Aggiornamento automatico
 
 BLOCK_HEIGHT = altezza
 
+BLOCKS_REMAINING = blocks remaining
+
 BUILD_VERSION = Versione
 
 CHECK_TIME_ACCURACY = Controlla la precisione dell'ora

src/main/resources/i18n/SysTray_ko.properties

@@ -7,6 +7,8 @@ AUTO_UPDATE = 자동 업데이트
 
 BLOCK_HEIGHT = 높이
 
+BLOCKS_REMAINING = blocks remaining
+
 BUILD_VERSION = 빌드 버전
 
 CHECK_TIME_ACCURACY = 시간 정확도 점검

src/main/resources/i18n/SysTray_nl.properties

@@ -7,6 +7,8 @@ AUTO_UPDATE = Automatische Update
 
 BLOCK_HEIGHT = Block hoogte
 
+BLOCKS_REMAINING = blocks remaining
+
 BUILD_VERSION = Versie nummer
 
 CHECK_TIME_ACCURACY = Controleer accuraatheid van de tijd

src/main/resources/i18n/SysTray_ro.properties

@@ -7,6 +7,8 @@ AUTO_UPDATE = Actualizare automata
 
 BLOCK_HEIGHT = dimensiune
 
+BLOCKS_REMAINING = blocks remaining
+
 BUILD_VERSION = versiunea compilatiei
 
 CHECK_TIME_ACCURACY = verificare exactitate ora

src/main/resources/i18n/SysTray_ru.properties

@@ -7,6 +7,8 @@ AUTO_UPDATE = Автоматическое обновление
 
 BLOCK_HEIGHT = Высота блока
 
+BLOCKS_REMAINING = blocks remaining
+
 BUILD_VERSION = Версия сборки
 
 CHECK_TIME_ACCURACY = Проверка точного времени

src/main/resources/i18n/SysTray_sv.properties

@@ -7,6 +7,8 @@ AUTO_UPDATE = Automatisk uppdatering
 
 BLOCK_HEIGHT = höjd
 
+BLOCKS_REMAINING = blocks remaining
+
 BUILD_VERSION = Byggversion
 
 CHECK_TIME_ACCURACY = Kontrollera tidens noggrannhet

src/main/resources/i18n/SysTray_zh_CN.properties

@@ -7,6 +7,8 @@ AUTO_UPDATE = 自动更新
 
 BLOCK_HEIGHT = 区块高度
 
+BLOCKS_REMAINING = blocks remaining
+
 BUILD_VERSION = 版本
 
 CHECK_TIME_ACCURACY = 检查时间准确性

src/main/resources/i18n/SysTray_zh_TW.properties

@@ -7,6 +7,8 @@ AUTO_UPDATE = 自動更新
 
 BLOCK_HEIGHT = 區塊高度
 
+BLOCKS_REMAINING = blocks remaining
+
 BUILD_VERSION = 版本
 
 CHECK_TIME_ACCURACY = 檢查時間準確性

src/test/java/org/qortal/test/arbitrary/ArbitraryServiceTests.java

@@ -102,77 +102,77 @@ public class ArbitraryServiceTests extends Common {
     }
 
     @Test
-    public void testValidQortalMetadata() throws IOException {
-        // Metadata is to describe an arbitrary resource (title, description, tags, etc)
-        String dataString = "{\"title\":\"Test Title\", \"description\":\"Test description\", \"tags\":[\"test\"]}";
+    public void testValidateGifRepository() throws IOException {
+        // Generate some random data
+        byte[] data = new byte[1024];
+        new Random().nextBytes(data);
 
-        // Write to temp path
-        Path path = Files.createTempFile("testValidQortalMetadata", null);
+        // Write the data to several files in a temp path
+        Path path = Files.createTempDirectory("testValidateGifRepository");
         path.toFile().deleteOnExit();
-        Files.write(path, dataString.getBytes(), StandardOpenOption.CREATE);
+        Files.write(Paths.get(path.toString(), "image1.gif"), data, StandardOpenOption.CREATE);
+        Files.write(Paths.get(path.toString(), "image2.gif"), data, StandardOpenOption.CREATE);
+        Files.write(Paths.get(path.toString(), "image3.gif"), data, StandardOpenOption.CREATE);
 
-        Service service = Service.QORTAL_METADATA;
+        Service service = Service.GIF_REPOSITORY;
         assertTrue(service.isValidationRequired());
+
+        // There is an index file in the root
         assertEquals(ValidationResult.OK, service.validate(path));
     }
 
     @Test
-    public void testQortalMetadataMissingKeys() throws IOException {
-        // Metadata is to describe an arbitrary resource (title, description, tags, etc)
-        String dataString = "{\"description\":\"Test description\", \"tags\":[\"test\"]}";
+    public void testValidateMultiLayerGifRepository() throws IOException {
+        // Generate some random data
+        byte[] data = new byte[1024];
+        new Random().nextBytes(data);
 
-        // Write to temp path
-        Path path = Files.createTempFile("testQortalMetadataMissingKeys", null);
+        // Write the data to several files in a temp path
+        Path path = Files.createTempDirectory("testValidateMultiLayerGifRepository");
         path.toFile().deleteOnExit();
-        Files.write(path, dataString.getBytes(), StandardOpenOption.CREATE);
+        Files.write(Paths.get(path.toString(), "image1.gif"), data, StandardOpenOption.CREATE);
 
-        Service service = Service.QORTAL_METADATA;
+        Path subdirectory = Paths.get(path.toString(), "subdirectory");
+        Files.createDirectories(subdirectory);
+        Files.write(Paths.get(subdirectory.toString(), "image2.gif"), data, StandardOpenOption.CREATE);
+        Files.write(Paths.get(subdirectory.toString(), "image3.gif"), data, StandardOpenOption.CREATE);
+
+        Service service = Service.GIF_REPOSITORY;
         assertTrue(service.isValidationRequired());
-        assertEquals(ValidationResult.MISSING_KEYS, service.validate(path));
+
+        // There is an index file in the root
+        assertEquals(ValidationResult.DIRECTORIES_NOT_ALLOWED, service.validate(path));
     }
 
     @Test
-    public void testQortalMetadataTooLarge() throws IOException {
-        // Metadata is to describe an arbitrary resource (title, description, tags, etc)
-        String dataString = "{\"title\":\"Test Title\", \"description\":\"Test description\", \"tags\":[\"test\"]}";
+    public void testValidateEmptyGifRepository() throws IOException {
+        Path path = Files.createTempDirectory("testValidateEmptyGifRepository");
 
-        // Generate some large data to go along with it
-        int largeDataSize = 11*1024; // Larger than allowed 10kiB
-        byte[] largeData = new byte[largeDataSize];
-        new Random().nextBytes(largeData);
-
-        // Write to temp path
-        Path path = Files.createTempDirectory("testQortalMetadataTooLarge");
-        path.toFile().deleteOnExit();
-        Files.write(Paths.get(path.toString(), "data"), dataString.getBytes(), StandardOpenOption.CREATE);
-        Files.write(Paths.get(path.toString(), "large_data"), largeData, StandardOpenOption.CREATE);
-
-        Service service = Service.QORTAL_METADATA;
+        Service service = Service.GIF_REPOSITORY;
         assertTrue(service.isValidationRequired());
-        assertEquals(ValidationResult.EXCEEDS_SIZE_LIMIT, service.validate(path));
+
+        // There is an index file in the root
+        assertEquals(ValidationResult.MISSING_DATA, service.validate(path));
     }
 
     @Test
-    public void testMultipleFileMetadata() throws IOException {
-        // Metadata is to describe an arbitrary resource (title, description, tags, etc)
-        String dataString = "{\"title\":\"Test Title\", \"description\":\"Test description\", \"tags\":[\"test\"]}";
+    public void testValidateInvalidGifRepository() throws IOException {
+        // Generate some random data
+        byte[] data = new byte[1024];
+        new Random().nextBytes(data);
 
-        // Generate some large data to go along with it
-        int otherDataSize = 1024; // Smaller than 10kiB limit
-        byte[] otherData = new byte[otherDataSize];
-        new Random().nextBytes(otherData);
-
-        // Write to temp path
-        Path path = Files.createTempDirectory("testMultipleFileMetadata");
+        // Write the data to several files in a temp path
+        Path path = Files.createTempDirectory("testValidateInvalidGifRepository");
         path.toFile().deleteOnExit();
-        Files.write(Paths.get(path.toString(), "data"), dataString.getBytes(), StandardOpenOption.CREATE);
-        Files.write(Paths.get(path.toString(), "other_data"), otherData, StandardOpenOption.CREATE);
+        Files.write(Paths.get(path.toString(), "image1.gif"), data, StandardOpenOption.CREATE);
+        Files.write(Paths.get(path.toString(), "image2.gif"), data, StandardOpenOption.CREATE);
+        Files.write(Paths.get(path.toString(), "image3.jpg"), data, StandardOpenOption.CREATE); // Invalid extension
 
-        Service service = Service.QORTAL_METADATA;
+        Service service = Service.GIF_REPOSITORY;
         assertTrue(service.isValidationRequired());
 
-        // There are multiple files, so we don't know which one to parse as JSON
-        assertEquals(ValidationResult.MISSING_KEYS, service.validate(path));
+        // There is an index file in the root
+        assertEquals(ValidationResult.INVALID_FILE_EXTENSION, service.validate(path));
     }
 
 }

src/test/java/org/qortal/test/common/AccountUtils.java

@@ -124,8 +124,6 @@ public class AccountUtils {
 		long timestamp = System.currentTimeMillis();
 		byte[] timestampBytes = Longs.toByteArray(timestamp);
 
-		final boolean mempowActive = timestamp >= BlockChain.getInstance().getOnlineAccountsMemoryPoWTimestamp();
-
 		for (int a = 0; a < numAccounts; ++a) {
 			byte[] privateKey = new byte[Transformer.PUBLIC_KEY_LENGTH];
 			SECURE_RANDOM.nextBytes(privateKey);
@@ -135,7 +133,7 @@ public class AccountUtils {
 
 			byte[] signature = signForAggregation(privateKey, timestampBytes);
 
-			Integer nonce = mempowActive ? new Random().nextInt(500000) : null;
+			Integer nonce = new Random().nextInt(500000);
 
 			onlineAccounts.add(new OnlineAccountData(timestamp, signature, publicKey, nonce));
 		}

src/test/java/org/qortal/test/group/DevGroupAdminTests.java

@@ -0,0 +1,388 @@
+package org.qortal.test.group;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.data.transaction.*;
+import org.qortal.group.Group;
+import org.qortal.group.Group.ApprovalThreshold;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.test.common.BlockUtils;
+import org.qortal.test.common.Common;
+import org.qortal.test.common.GroupUtils;
+import org.qortal.test.common.TransactionUtils;
+import org.qortal.test.common.transaction.TestTransaction;
+import org.qortal.transaction.Transaction;
+import org.qortal.transaction.Transaction.ValidationResult;
+import org.qortal.utils.Base58;
+
+import static org.junit.Assert.*;
+
+/**
+ * Dev group admin tests
+ *
+ * The dev group (ID 1) is owned by the null account with public key 11111111111111111111111111111111
+ * To regain access to otherwise blocked owner-based rules, it has different validation logic
+ * which applies to groups with this same null owner.
+ *
+ * The main difference is that approval is required for certain transaction types relating to
+ * null-owned groups. This allows existing admins to approve updates to the group (using group's
+ * approval threshold) instead of these actions being performed by the owner.
+ *
+ * Since these apply to all null-owned groups, this allows anyone to update their group to
+ * the null owner if they want to take advantage of this decentralized approval system.
+ *
+ * Currently, the affected transaction types are:
+ * - AddGroupAdminTransaction
+ * - RemoveGroupAdminTransaction
+ *
+ * This same approach could ultimately be applied to other group transactions too.
+ */
+public class DevGroupAdminTests extends Common {
+
+	private static final int DEV_GROUP_ID = 1;
+
+	@Before
+	public void beforeTest() throws DataException {
+		Common.useDefaultSettings();
+	}
+
+	@After
+	public void afterTest() throws DataException {
+		Common.orphanCheck();
+	}
+
+	@Test
+	public void testGroupKickMember() throws DataException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PrivateKeyAccount alice = Common.getTestAccount(repository, "alice");
+			PrivateKeyAccount bob = Common.getTestAccount(repository, "bob");
+
+			// Dev group
+			int groupId = DEV_GROUP_ID;
+
+			// Confirm Bob is not a member
+			assertFalse(isMember(repository, bob.getAddress(), groupId));
+
+			// Attempt to kick Bob
+			ValidationResult result = groupKick(repository, alice, groupId, bob.getAddress());
+			// Should NOT be OK
+			assertNotSame(ValidationResult.OK, result);
+
+			// Alice to invite Bob, as it's a closed group
+			groupInvite(repository, alice, groupId, bob.getAddress(), 3600);
+
+			// Bob to join
+			joinGroup(repository, bob, groupId);
+
+			// Confirm Bob now a member
+			assertTrue(isMember(repository, bob.getAddress(), groupId));
+
+			// Attempt to kick Bob
+			result = groupKick(repository, alice, groupId, bob.getAddress());
+			// Should be OK
+			assertEquals(ValidationResult.OK, result);
+
+			// Confirm Bob no longer a member
+			assertFalse(isMember(repository, bob.getAddress(), groupId));
+
+			// Orphan last block
+			BlockUtils.orphanLastBlock(repository);
+
+			// Confirm Bob now a member
+			assertTrue(isMember(repository, bob.getAddress(), groupId));
+		}
+	}
+
+	@Test
+	public void testGroupKickAdmin() throws DataException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PrivateKeyAccount alice = Common.getTestAccount(repository, "alice");
+			PrivateKeyAccount bob = Common.getTestAccount(repository, "bob");
+
+			// Dev group
+			int groupId = DEV_GROUP_ID;
+
+			// Confirm Bob is not a member
+			assertFalse(isMember(repository, bob.getAddress(), groupId));
+
+			// Alice to invite Bob, as it's a closed group
+			groupInvite(repository, alice, groupId, bob.getAddress(), 3600);
+
+			// Bob to join
+			joinGroup(repository, bob, groupId);
+
+			// Confirm Bob now a member
+			assertTrue(isMember(repository, bob.getAddress(), groupId));
+
+			// Promote Bob to admin
+			TransactionData addGroupAdminTransactionData = addGroupAdmin(repository, alice, groupId, bob.getAddress());
+
+			// Confirm transaction needs approval, and hasn't been approved
+			Transaction.ApprovalStatus approvalStatus = GroupUtils.getApprovalStatus(repository, addGroupAdminTransactionData.getSignature());
+			assertEquals("incorrect transaction approval status", Transaction.ApprovalStatus.PENDING, approvalStatus);
+
+			// Have Alice approve Bob's approval-needed transaction
+			GroupUtils.approveTransaction(repository, "alice", addGroupAdminTransactionData.getSignature(), true);
+
+			// Mint a block so that the transaction becomes approved
+			BlockUtils.mintBlock(repository);
+
+			// Confirm transaction is approved
+			approvalStatus = GroupUtils.getApprovalStatus(repository, addGroupAdminTransactionData.getSignature());
+			assertEquals("incorrect transaction approval status", Transaction.ApprovalStatus.APPROVED, approvalStatus);
+
+			// Confirm Bob is now admin
+			assertTrue(isAdmin(repository, bob.getAddress(), groupId));
+
+			// Attempt to kick Bob
+			ValidationResult result = groupKick(repository, alice, groupId, bob.getAddress());
+			// Shouldn't be allowed
+			assertEquals(ValidationResult.INVALID_GROUP_OWNER, result);
+
+			// Confirm Bob is still a member
+			assertTrue(isMember(repository, bob.getAddress(), groupId));
+
+			// Confirm Bob still an admin
+			assertTrue(isAdmin(repository, bob.getAddress(), groupId));
+
+			// Orphan last block
+			BlockUtils.orphanLastBlock(repository);
+
+			// Confirm Bob no longer an admin (ADD_GROUP_ADMIN no longer approved)
+			assertFalse(isAdmin(repository, bob.getAddress(), groupId));
+
+			// Have Alice try to kick herself!
+			result = groupKick(repository, alice, groupId, alice.getAddress());
+			// Should NOT be OK
+			assertNotSame(ValidationResult.OK, result);
+
+			// Have Bob try to kick Alice
+			result = groupKick(repository, bob, groupId, alice.getAddress());
+			// Should NOT be OK
+			assertNotSame(ValidationResult.OK, result);
+		}
+	}
+
+	@Test
+	public void testGroupBanMember() throws DataException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PrivateKeyAccount alice = Common.getTestAccount(repository, "alice");
+			PrivateKeyAccount bob = Common.getTestAccount(repository, "bob");
+
+			// Dev group
+			int groupId = DEV_GROUP_ID;
+
+			// Confirm Bob is not a member
+			assertFalse(isMember(repository, bob.getAddress(), groupId));
+
+			// Attempt to cancel non-existent Bob ban
+			ValidationResult result = cancelGroupBan(repository, alice, groupId, bob.getAddress());
+			// Should NOT be OK
+			assertNotSame(ValidationResult.OK, result);
+
+			// Attempt to ban Bob
+			result = groupBan(repository, alice, groupId, bob.getAddress());
+			// Should be OK
+			assertEquals(ValidationResult.OK, result);
+
+			// Bob attempts to rejoin
+			result = joinGroup(repository, bob, groupId);
+			// Should NOT be OK
+			assertNotSame(ValidationResult.OK, result);
+
+			// Orphan last block (Bob ban)
+			BlockUtils.orphanLastBlock(repository);
+			// Delete unconfirmed group-ban transaction
+			TransactionUtils.deleteUnconfirmedTransactions(repository);
+
+			// Confirm Bob is not a member
+			assertFalse(isMember(repository, bob.getAddress(), groupId));
+
+			// Alice to invite Bob, as it's a closed group
+			groupInvite(repository, alice, groupId, bob.getAddress(), 3600);
+
+			// Bob to join
+			result = joinGroup(repository, bob, groupId);
+			// Should be OK
+			assertEquals(ValidationResult.OK, result);
+
+			// Confirm Bob now a member
+			assertTrue(isMember(repository, bob.getAddress(), groupId));
+
+			// Attempt to ban Bob
+			result = groupBan(repository, alice, groupId, bob.getAddress());
+			// Should be OK
+			assertEquals(ValidationResult.OK, result);
+
+			// Confirm Bob no longer a member
+			assertFalse(isMember(repository, bob.getAddress(), groupId));
+
+			// Bob attempts to rejoin
+			result = joinGroup(repository, bob, groupId);
+			// Should NOT be OK
+			assertNotSame(ValidationResult.OK, result);
+
+			// Cancel Bob's ban
+			result = cancelGroupBan(repository, alice, groupId, bob.getAddress());
+			// Should be OK
+			assertEquals(ValidationResult.OK, result);
+
+			// Bob attempts to rejoin
+			result = joinGroup(repository, bob, groupId);
+			// Should be OK
+			assertEquals(ValidationResult.OK, result);
+
+			// Orphan last block (Bob join)
+			BlockUtils.orphanLastBlock(repository);
+			// Delete unconfirmed join-group transaction
+			TransactionUtils.deleteUnconfirmedTransactions(repository);
+
+			// Orphan last block (Cancel Bob ban)
+			BlockUtils.orphanLastBlock(repository);
+			// Delete unconfirmed cancel-ban transaction
+			TransactionUtils.deleteUnconfirmedTransactions(repository);
+
+			// Bob attempts to rejoin
+			result = joinGroup(repository, bob, groupId);
+			// Should NOT be OK
+			assertNotSame(ValidationResult.OK, result);
+
+			// Orphan last block (Bob ban)
+			BlockUtils.orphanLastBlock(repository);
+			// Delete unconfirmed group-ban transaction
+			TransactionUtils.deleteUnconfirmedTransactions(repository);
+
+			// Confirm Bob now a member
+			assertTrue(isMember(repository, bob.getAddress(), groupId));
+		}
+	}
+
+	@Test
+	public void testGroupBanAdmin() throws DataException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PrivateKeyAccount alice = Common.getTestAccount(repository, "alice");
+			PrivateKeyAccount bob = Common.getTestAccount(repository, "bob");
+
+			// Dev group
+			int groupId = DEV_GROUP_ID;
+
+			// Confirm Bob is not a member
+			assertFalse(isMember(repository, bob.getAddress(), groupId));
+
+			// Alice to invite Bob, as it's a closed group
+			groupInvite(repository, alice, groupId, bob.getAddress(), 3600);
+
+			// Bob to join
+			ValidationResult result = joinGroup(repository, bob, groupId);
+			// Should be OK
+			assertEquals(ValidationResult.OK, result);
+
+			// Promote Bob to admin
+			TransactionData addGroupAdminTransactionData = addGroupAdmin(repository, alice, groupId, bob.getAddress());
+
+			// Confirm transaction needs approval, and hasn't been approved
+			Transaction.ApprovalStatus approvalStatus = GroupUtils.getApprovalStatus(repository, addGroupAdminTransactionData.getSignature());
+			assertEquals("incorrect transaction approval status", Transaction.ApprovalStatus.PENDING, approvalStatus);
+
+			// Have Alice approve Bob's approval-needed transaction
+			GroupUtils.approveTransaction(repository, "alice", addGroupAdminTransactionData.getSignature(), true);
+
+			// Mint a block so that the transaction becomes approved
+			BlockUtils.mintBlock(repository);
+
+			// Confirm transaction is approved
+			approvalStatus = GroupUtils.getApprovalStatus(repository, addGroupAdminTransactionData.getSignature());
+			assertEquals("incorrect transaction approval status", Transaction.ApprovalStatus.APPROVED, approvalStatus);
+
+			// Confirm Bob is now admin
+			assertTrue(isAdmin(repository, bob.getAddress(), groupId));
+
+			// Attempt to ban Bob
+			result = groupBan(repository, alice, groupId, bob.getAddress());
+			// .. but we can't, because Bob is an admin and the group has no owner
+			assertEquals(ValidationResult.INVALID_GROUP_OWNER, result);
+
+			// Confirm Bob still a member
+			assertTrue(isMember(repository, bob.getAddress(), groupId));
+
+			// ... and still an admin
+			assertTrue(isAdmin(repository, bob.getAddress(), groupId));
+
+			// Have Alice try to ban herself!
+			result = groupBan(repository, alice, groupId, alice.getAddress());
+			// Should NOT be OK
+			assertNotSame(ValidationResult.OK, result);
+
+			// Have Bob try to ban Alice
+			result = groupBan(repository, bob, groupId, alice.getAddress());
+			// Should NOT be OK
+			assertNotSame(ValidationResult.OK, result);
+		}
+	}
+
+
+	private ValidationResult joinGroup(Repository repository, PrivateKeyAccount joiner, int groupId) throws DataException {
+		JoinGroupTransactionData transactionData = new JoinGroupTransactionData(TestTransaction.generateBase(joiner), groupId);
+		ValidationResult result = TransactionUtils.signAndImport(repository, transactionData, joiner);
+
+		if (result == ValidationResult.OK)
+			BlockUtils.mintBlock(repository);
+
+		return result;
+	}
+
+	private void groupInvite(Repository repository, PrivateKeyAccount admin, int groupId, String invitee, int timeToLive) throws DataException {
+		GroupInviteTransactionData transactionData = new GroupInviteTransactionData(TestTransaction.generateBase(admin), groupId, invitee, timeToLive);
+		TransactionUtils.signAndMint(repository, transactionData, admin);
+	}
+
+	private ValidationResult groupKick(Repository repository, PrivateKeyAccount admin, int groupId, String member) throws DataException {
+		GroupKickTransactionData transactionData = new GroupKickTransactionData(TestTransaction.generateBase(admin), groupId, member, "testing");
+		ValidationResult result = TransactionUtils.signAndImport(repository, transactionData, admin);
+
+		if (result == ValidationResult.OK)
+			BlockUtils.mintBlock(repository);
+
+		return result;
+	}
+
+	private ValidationResult groupBan(Repository repository, PrivateKeyAccount admin, int groupId, String member) throws DataException {
+		GroupBanTransactionData transactionData = new GroupBanTransactionData(TestTransaction.generateBase(admin), groupId, member, "testing", 0);
+		ValidationResult result = TransactionUtils.signAndImport(repository, transactionData, admin);
+
+		if (result == ValidationResult.OK)
+			BlockUtils.mintBlock(repository);
+
+		return result;
+	}
+
+	private ValidationResult cancelGroupBan(Repository repository, PrivateKeyAccount admin, int groupId, String member) throws DataException {
+		CancelGroupBanTransactionData transactionData = new CancelGroupBanTransactionData(TestTransaction.generateBase(admin), groupId, member);
+		ValidationResult result = TransactionUtils.signAndImport(repository, transactionData, admin);
+
+		if (result == ValidationResult.OK)
+			BlockUtils.mintBlock(repository);
+
+		return result;
+	}
+
+	private TransactionData addGroupAdmin(Repository repository, PrivateKeyAccount owner, int groupId, String member) throws DataException {
+		AddGroupAdminTransactionData transactionData = new AddGroupAdminTransactionData(TestTransaction.generateBase(owner), groupId, member);
+		transactionData.setTxGroupId(groupId);
+		TransactionUtils.signAndMint(repository, transactionData, owner);
+		return transactionData;
+	}
+
+	private boolean isMember(Repository repository, String address, int groupId) throws DataException {
+		return repository.getGroupRepository().memberExists(groupId, address);
+	}
+
+	private boolean isAdmin(Repository repository, String address, int groupId) throws DataException {
+		return repository.getGroupRepository().adminExists(groupId, address);
+	}
+
+}

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

@@ -69,7 +69,8 @@
 		"calcChainWeightTimestamp": 0,
 		"transactionV5Timestamp": 0,
 		"transactionV6Timestamp": 9999999999999,
-		"disableReferenceTimestamp": 9999999999999
+		"disableReferenceTimestamp": 9999999999999,
+		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -72,7 +72,8 @@
 		"calcChainWeightTimestamp": 0,
 		"transactionV5Timestamp": 0,
 		"transactionV6Timestamp": 0,
-		"disableReferenceTimestamp": 0
+		"disableReferenceTimestamp": 0,
+		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -73,7 +73,8 @@
 		"calcChainWeightTimestamp": 0,
 		"transactionV5Timestamp": 0,
 		"transactionV6Timestamp": 0,
-		"disableReferenceTimestamp": 9999999999999
+		"disableReferenceTimestamp": 9999999999999,
+		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -73,7 +73,8 @@
 		"calcChainWeightTimestamp": 0,
 		"transactionV5Timestamp": 0,
 		"transactionV6Timestamp": 0,
-		"disableReferenceTimestamp": 9999999999999
+		"disableReferenceTimestamp": 9999999999999,
+		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -73,7 +73,8 @@
 		"calcChainWeightTimestamp": 0,
 		"transactionV5Timestamp": 0,
 		"transactionV6Timestamp": 0,
-		"disableReferenceTimestamp": 9999999999999
+		"disableReferenceTimestamp": 9999999999999,
+		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -73,7 +73,8 @@
 		"calcChainWeightTimestamp": 0,
 		"transactionV5Timestamp": 0,
 		"transactionV6Timestamp": 0,
-		"disableReferenceTimestamp": 9999999999999
+		"disableReferenceTimestamp": 9999999999999,
+		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -74,7 +74,8 @@
 		"transactionV5Timestamp": 0,
 		"transactionV6Timestamp": 0,
 		"disableReferenceTimestamp": 9999999999999,
-		"aggregateSignatureTimestamp": 0
+		"aggregateSignatureTimestamp": 0,
+		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -73,7 +73,8 @@
 		"calcChainWeightTimestamp": 0,
 		"transactionV5Timestamp": 0,
 		"transactionV6Timestamp": 0,
-		"disableReferenceTimestamp": 9999999999999
+		"disableReferenceTimestamp": 9999999999999,
+		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -73,7 +73,8 @@
 		"calcChainWeightTimestamp": 0,
 		"transactionV5Timestamp": 0,
 		"transactionV6Timestamp": 0,
-		"disableReferenceTimestamp": 9999999999999
+		"disableReferenceTimestamp": 9999999999999,
+		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -73,7 +73,8 @@
 		"calcChainWeightTimestamp": 0,
 		"transactionV5Timestamp": 0,
 		"transactionV6Timestamp": 0,
-		"disableReferenceTimestamp": 9999999999999
+		"disableReferenceTimestamp": 9999999999999,
+		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -73,7 +73,8 @@
 		"newConsensusTimestamp": 0,
 		"transactionV5Timestamp": 0,
 		"transactionV6Timestamp": 0,
-		"disableReferenceTimestamp": 9999999999999
+		"disableReferenceTimestamp": 9999999999999,
+		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -73,7 +73,8 @@
 		"calcChainWeightTimestamp": 0,
 		"transactionV5Timestamp": 0,
 		"transactionV6Timestamp": 0,
-		"disableReferenceTimestamp": 9999999999999
+		"disableReferenceTimestamp": 9999999999999,
+		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999
 	},
 	"genesisInfo": {
 		"version": 4,
@@ -90,6 +91,8 @@
 
 			{ "type": "CREATE_GROUP", "creatorPublicKey": "2tiMr5LTpaWCgbRvkPK8TFd7k63DyHJMMFFsz9uBf1ZP", "groupName": "dev-group", "description": "developer group", "isOpen": false, "approvalThreshold": "PCT100", "minimumBlockDelay": 0, "maximumBlockDelay": 1440 },
 
+			{ "type": "UPDATE_GROUP", "ownerPublicKey": "2tiMr5LTpaWCgbRvkPK8TFd7k63DyHJMMFFsz9uBf1ZP", "groupId": 1, "newOwner": "QdSnUy6sUiEnaN87dWmE92g1uQjrvPgrWG", "newDescription": "developer group", "newIsOpen": false, "newApprovalThreshold": "PCT40", "minimumBlockDelay": 10, "maximumBlockDelay": 1440 },
+
 			{ "type": "ISSUE_ASSET", "issuerPublicKey": "2tiMr5LTpaWCgbRvkPK8TFd7k63DyHJMMFFsz9uBf1ZP", "assetName": "TEST", "description": "test asset", "data": "", "quantity": "1000000", "isDivisible": true, "fee": 0 },
 			{ "type": "ISSUE_ASSET", "issuerPublicKey": "C6wuddsBV3HzRrXUtezE7P5MoRXp5m3mEDokRDGZB6ry", "assetName": "OTHER", "description": "other test asset", "data": "", "quantity": "1000000", "isDivisible": true, "fee": 0 },
 			{ "type": "ISSUE_ASSET", "issuerPublicKey": "2tiMr5LTpaWCgbRvkPK8TFd7k63DyHJMMFFsz9uBf1ZP", "assetName": "GOLD", "description": "gold test asset", "data": "", "quantity": "1000000", "isDivisible": true, "fee": 0 },

tools/approve-dev-transaction.sh

@@ -0,0 +1,97 @@
+#!/usr/bin/env bash
+
+port=12391
+if [ $# -gt 0 -a "$1" = "-t" ]; then
+	port=62391
+fi
+
+printf "Searching for auto-update transactions to approve...\n";
+
+tx=$( curl --silent --url "http://localhost:${port}/transactions/search?txGroupId=1&txType=ADD_GROUP_ADMIN&txType=REMOVE_GROUP_ADMIN&confirmationStatus=CONFIRMED&limit=1&reverse=true" );
+if fgrep --silent '"approvalStatus":"PENDING"' <<< "${tx}"; then
+	true
+else
+	echo "Can't find any pending transactions"
+	exit
+fi
+
+sig=$( perl -n -e 'print $1 if m/"signature":"(\w+)"/' <<< "${tx}" )
+if [ -z "${sig}" ]; then
+	printf "Can't find transaction signature in JSON:\n%s\n" "${tx}"
+	exit
+fi
+
+printf "Found transaction %s\n" $sig;
+
+printf "\nPaste your dev account private key:\n";
+IFS=
+read -s privkey
+printf "\n"
+
+# Convert to public key
+pubkey=$( curl --silent --url "http://localhost:${port}/utils/publickey" --data @- <<< "${privkey}" );
+if egrep -v --silent '^\w{44,46}$' <<< "${pubkey}"; then
+	printf "Invalid response from API - was your private key correct?\n%s\n" "${pubkey}"
+	exit
+fi
+printf "Your public key: %s\n" ${pubkey}
+
+# Convert to address
+address=$( curl --silent --url "http://localhost:${port}/addresses/convert/${pubkey}" );
+printf "Your address: %s\n" ${address}
+
+# Grab last reference
+lastref=$( curl --silent --url "http://localhost:${port}/addresses/lastreference/{$address}" );
+printf "Your last reference: %s\n" ${lastref}
+
+# Build GROUP_APPROVAL transaction
+timestamp=$( date +%s )000
+tx_json=$( cat <<TX_END
+{
+  "timestamp": ${timestamp},
+  "reference": "${lastref}",
+  "fee": 0.001,
+  "txGroupId": 0,
+  "adminPublicKey": "${pubkey}",
+  "pendingSignature": "${sig}",
+  "approval": true
+}
+TX_END
+)
+
+raw_tx=$( curl --silent --header "Content-Type: application/json" --url "http://localhost:${port}/groups/approval" --data @- <<< "${tx_json}" )
+if egrep -v --silent '^\w{100,}' <<< "${raw_tx}"; then
+	printf "Building GROUP_APPROVAL transaction failed:\n%s\n" "${raw_tx}"
+	exit
+fi
+printf "\nRaw approval tx:\n%s\n" ${raw_tx}
+
+# sign
+sign_json=$( cat <<SIGN_END
+{
+  "privateKey": "${privkey}",
+  "transactionBytes": "${raw_tx}"
+}
+SIGN_END
+)
+signed_tx=$( curl --silent --header "Content-Type: application/json" --url "http://localhost:${port}/transactions/sign" --data @- <<< "${sign_json}" )
+printf "\nSigned tx:\n%s\n" ${signed_tx}
+if egrep -v --silent '^\w{100,}' <<< "${signed_tx}"; then
+	printf "Signing GROUP_APPROVAL transaction failed:\n%s\n" "${signed_tx}"
+	exit
+fi
+
+# ready to publish?
+plural="s"
+printf "\n"
+for ((seconds = 5; seconds > 0; seconds--)); do
+	if [ "${seconds}" = "1" ]; then
+		plural=""
+	fi
+	printf "\rBroadcasting in %d second%s...(CTRL-C) to abort " $seconds $plural
+	sleep 1
+done
+
+printf "\rBroadcasting signed GROUP_APPROVAL transaction...      \n"
+result=$( curl --silent --url "http://localhost:${port}/transactions/process" --data @- <<< "${signed_tx}" )
+printf "API response:\n%s\n" "${result}"

tools/build-zip.sh

@@ -58,6 +58,9 @@ git show HEAD:log4j2.properties > ${build_dir}/log4j2.properties
 git show HEAD:start.sh > ${build_dir}/start.sh
 git show HEAD:stop.sh > ${build_dir}/stop.sh
 
+chmod +x ${build_dir}/start.sh
+chmod +x ${build_dir}/stop.sh
+
 printf "{\n}\n" > ${build_dir}/settings.json
 
 gtouch -d ${commit_ts%%+??:??} ${build_dir} ${build_dir}/*

tools/tx.pl

@@ -71,9 +71,14 @@ our %TRANSACTION_TYPES = (
 	},
 	add_group_admin => {
 		url => 'groups/addadmin',
-		required => [qw(groupId member)],
+		required => [qw(groupId txGroupId member)],
 		key_name => 'ownerPublicKey',
 	},
+	remove_group_admin => {
+        url => 'groups/removeadmin',
+        required => [qw(groupId txGroupId admin)],
+        key_name => 'ownerPublicKey',
+    },
 	group_approval => {
 		url => 'groups/approval',
 		required => [qw(pendingSignature approval)],