Fixed bug causing initial latestATStates data to be discarded.

This should fix an edge case where AT states data was pruned/trimmed but it was then later required in consensus. The older state was deleted because it was replaced by a new "latest" state in a brand new block. But once the new "latest" state was orphaned from the block, the old "latest" state was then required again.

This works around the problem by excluding very recent blocks in the latest AT states data, so that it is unaffected by real-time sync activity.

The trade off is that we could end up retaining more AT states than needed, so a secondary cleanup process may need to run at some time in the future to remove these. But it should only be a minimal amount of data, and can be cleaned up with a single query. This would have been happening to a certain degree already.

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:{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="ProductCode" Value="1033:{6C93A96C-E3AF-42FD-BE11-7EC3734905C6} 1049:{754F5347-82E5-4251-AED0-F4141CDD11F5} 2052:{413BD7B3-A3F8-47D0-BCA4-5C7694A40936} 2057:{71450AC8-1E6F-4469-852D-0591FA693680} " Type="16"/>
     <ROW Property="ProductLanguage" Value="2057"/>
     <ROW Property="ProductName" Value="Qortal"/>
-    <ROW Property="ProductVersion" Value="3.6.3" Type="32"/>
+    <ROW Property="ProductVersion" Value="3.8.3" 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="{F4F774B9-18DC-4740-9552-EA16B98801C9}" Directory_="APPDIR" Attributes="260" KeyPath="DisplayName" Options="1"/>
+    <ROW Component="AI_CustomARPName" ComponentId="{EC7B4AD9-F2D9-48C4-A586-C4697D9C380C}" Directory_="APPDIR" Attributes="260" KeyPath="DisplayName" Options="1"/>
     <ROW Component="AI_ExePath" ComponentId="{3644948D-AE0B-41BB-9FAF-A79E70490A08}" Directory_="APPDIR" Attributes="260" KeyPath="AI_ExePath"/>
     <ROW Component="APPDIR" ComponentId="{680DFDDE-3FB4-47A5-8FF5-934F576C6F91}" Directory_="APPDIR" Attributes="0"/>
     <ROW Component="AccessBridgeCallbacks.h" ComponentId="{288055D1-1062-47A3-AA44-5601B4E38AED}" Directory_="bridge_Dir" Attributes="0" KeyPath="AccessBridgeCallbacks.h" Type="0"/>

pom.xml

@@ -3,7 +3,7 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>org.qortal</groupId>
 	<artifactId>qortal</artifactId>
-	<version>3.8.0</version>
+	<version>3.8.3</version>
 	<packaging>jar</packaging>
 	<properties>
 		<skipTests>true</skipTests>

src/main/java/org/qortal/account/SelfSponsorshipAlgoV1.java

@@ -52,6 +52,11 @@ public class SelfSponsorshipAlgoV1 {
 
 
     public void run() throws DataException {
+        if (this.accountData == null) {
+            // Nothing to do
+            return;
+        }
+
         this.fetchSponsorshipRewardShares();
         if (this.sponsorshipRewardShares.isEmpty()) {
             // Nothing to do

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

@@ -1,6 +1,7 @@
 package org.qortal.api.model;
 
 import io.swagger.v3.oas.annotations.media.Schema;
+import org.qortal.controller.Controller;
 import org.qortal.data.block.BlockSummaryData;
 import org.qortal.data.network.PeerData;
 import org.qortal.network.Handshake;
@@ -36,6 +37,7 @@ public class ConnectedPeer {
     public Long lastBlockTimestamp;
     public UUID connectionId;
     public String age;
+    public Boolean isTooDivergent;
 
     protected ConnectedPeer() {
     }
@@ -69,6 +71,11 @@ public class ConnectedPeer {
             this.lastBlockSignature = peerChainTipData.getSignature();
             this.lastBlockTimestamp = peerChainTipData.getTimestamp();
         }
+
+        // Only include isTooDivergent decision if we've had the opportunity to request block summaries this peer
+        if (peer.getLastTooDivergentTime() != null) {
+            this.isTooDivergent = Controller.wasRecentlyTooDivergent.test(peer);
+        }
     }
 
 }

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

@@ -70,6 +70,8 @@ public class ChatResource {
 			@QueryParam("txGroupId") Integer txGroupId,
 			@QueryParam("involving") List<String> involvingAddresses,
 			@QueryParam("reference") String reference,
+			@QueryParam("chatreference") String chatReference,
+			@QueryParam("haschatreference") Boolean hasChatReference,
 			@Parameter(ref = "limit") @QueryParam("limit") Integer limit,
 			@Parameter(ref = "offset") @QueryParam("offset") Integer offset,
 			@Parameter(ref = "reverse") @QueryParam("reverse") Boolean reverse) {
@@ -92,12 +94,18 @@ public class ChatResource {
 		if (reference != null)
 			referenceBytes = Base58.decode(reference);
 
+		byte[] chatReferenceBytes = null;
+		if (chatReference != null)
+			chatReferenceBytes = Base58.decode(chatReference);
+
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			return repository.getChatRepository().getMessagesMatchingCriteria(
 					before,
 					after,
 					txGroupId,
 					referenceBytes,
+					chatReferenceBytes,
+					hasChatReference,
 					involvingAddresses,
 					limit, offset, reverse);
 		} catch (DataException e) {

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

@@ -8,11 +8,10 @@ import io.swagger.v3.oas.annotations.responses.ApiResponse;
 import io.swagger.v3.oas.annotations.security.SecurityRequirement;
 import io.swagger.v3.oas.annotations.tags.Tag;
 
-import java.io.IOException;
 import java.math.BigDecimal;
 import java.util.List;
 import java.util.Objects;
-import java.util.concurrent.locks.ReentrantLock;
+import java.util.stream.Collectors;
 
 import javax.servlet.http.HttpServletRequest;
 import javax.ws.rs.*;
@@ -25,7 +24,6 @@ import org.bitcoinj.core.*;
 import org.bitcoinj.script.Script;
 import org.qortal.api.*;
 import org.qortal.api.model.CrossChainBitcoinyHTLCStatus;
-import org.qortal.controller.Controller;
 import org.qortal.crosschain.*;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.at.ATData;
@@ -586,98 +584,103 @@ public class CrossChainHtlcResource {
 			}
 
 			List<TradeBotData> allTradeBotData = repository.getCrossChainRepository().getAllTradeBotData();
-			TradeBotData tradeBotData = allTradeBotData.stream().filter(tradeBotDataItem -> tradeBotDataItem.getAtAddress().equals(atAddress)).findFirst().orElse(null);
-			if (tradeBotData == null)
+			List<TradeBotData> tradeBotDataList = allTradeBotData.stream().filter(tradeBotDataItem -> tradeBotDataItem.getAtAddress().equals(atAddress)).collect(Collectors.toList());
+			if (tradeBotDataList == null || tradeBotDataList.isEmpty())
 				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 
-			Bitcoiny bitcoiny = (Bitcoiny) acct.getBlockchain();
-			int lockTime = tradeBotData.getLockTimeA();
+			// Loop through all matching entries for this AT address, as there might be more than one
+			for (TradeBotData tradeBotData : tradeBotDataList) {
 
-			// We can't refund P2SH-A until lockTime-A has passed
-			if (NTP.getTime() <= lockTime * 1000L)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_TOO_SOON);
+				if (tradeBotData == null)
+					throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 
-			// We can't refund P2SH-A until median block time has passed lockTime-A (see BIP113)
-			int medianBlockTime = bitcoiny.getMedianBlockTime();
-			if (medianBlockTime <= lockTime)
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_TOO_SOON);
+				Bitcoiny bitcoiny = (Bitcoiny) acct.getBlockchain();
+				int lockTime = tradeBotData.getLockTimeA();
 
-			// Fee for redeem/refund is subtracted from P2SH-A balance.
-			long feeTimestamp = calcFeeTimestamp(lockTime, crossChainTradeData.tradeTimeout);
-			long p2shFee = bitcoiny.getP2shFee(feeTimestamp);
-			long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
+				// We can't refund P2SH-A until lockTime-A has passed
+				if (NTP.getTime() <= lockTime * 1000L)
+					continue;
 
-			// Create redeem script based on destination chain
-			byte[] redeemScriptA;
-			String p2shAddressA;
-			BitcoinyHTLC.Status htlcStatusA;
-			if (Objects.equals(bitcoiny.getCurrencyCode(), "ARRR")) {
-				redeemScriptA = PirateChainHTLC.buildScript(tradeBotData.getTradeForeignPublicKey(), lockTime, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
-				p2shAddressA = PirateChain.getInstance().deriveP2shAddressBPrefix(redeemScriptA);
-				htlcStatusA = PirateChainHTLC.determineHtlcStatus(bitcoiny.getBlockchainProvider(), p2shAddressA, minimumAmountA);
-			}
-			else {
-				redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTime, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
-				p2shAddressA = bitcoiny.deriveP2shAddress(redeemScriptA);
-				htlcStatusA = BitcoinyHTLC.determineHtlcStatus(bitcoiny.getBlockchainProvider(), p2shAddressA, minimumAmountA);
-			}
-			LOGGER.info(String.format("Refunding P2SH address: %s", p2shAddressA));
+				// We can't refund P2SH-A until median block time has passed lockTime-A (see BIP113)
+				int medianBlockTime = bitcoiny.getMedianBlockTime();
+				if (medianBlockTime <= lockTime)
+					continue;
 
-			switch (htlcStatusA) {
-				case UNFUNDED:
-				case FUNDING_IN_PROGRESS:
-					// Still waiting for P2SH-A to be funded...
-					throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_TOO_SOON);
+				// Fee for redeem/refund is subtracted from P2SH-A balance.
+				long feeTimestamp = calcFeeTimestamp(lockTime, crossChainTradeData.tradeTimeout);
+				long p2shFee = bitcoiny.getP2shFee(feeTimestamp);
+				long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
 
-				case REDEEM_IN_PROGRESS:
-				case REDEEMED:
-				case REFUND_IN_PROGRESS:
-				case REFUNDED:
-					// Too late!
-					return false;
+				// Create redeem script based on destination chain
+				byte[] redeemScriptA;
+				String p2shAddressA;
+				BitcoinyHTLC.Status htlcStatusA;
+				if (Objects.equals(bitcoiny.getCurrencyCode(), "ARRR")) {
+					redeemScriptA = PirateChainHTLC.buildScript(tradeBotData.getTradeForeignPublicKey(), lockTime, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+					p2shAddressA = PirateChain.getInstance().deriveP2shAddressBPrefix(redeemScriptA);
+					htlcStatusA = PirateChainHTLC.determineHtlcStatus(bitcoiny.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+				} else {
+					redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTime, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+					p2shAddressA = bitcoiny.deriveP2shAddress(redeemScriptA);
+					htlcStatusA = BitcoinyHTLC.determineHtlcStatus(bitcoiny.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+				}
+				LOGGER.info(String.format("Refunding P2SH address: %s", p2shAddressA));
 
-				case FUNDED:{
-					Coin refundAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
+				switch (htlcStatusA) {
+					case UNFUNDED:
+					case FUNDING_IN_PROGRESS:
+						// Still waiting for P2SH-A to be funded...
+						continue;
 
-					if (Objects.equals(bitcoiny.getCurrencyCode(), "ARRR")) {
-						// Pirate Chain custom integration
+					case REDEEM_IN_PROGRESS:
+					case REDEEMED:
+					case REFUND_IN_PROGRESS:
+					case REFUNDED:
+						// Too late!
+						continue;
 
-						PirateChain pirateChain = PirateChain.getInstance();
-						String p2shAddressT3 = pirateChain.deriveP2shAddress(redeemScriptA);
+					case FUNDED: {
+						Coin refundAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
 
-						// Get funding txid
-						String fundingTxidHex = PirateChainHTLC.getUnspentFundingTxid(pirateChain.getBlockchainProvider(), p2shAddressA, minimumAmountA);
-						if (fundingTxidHex == null) {
-							throw new ForeignBlockchainException("Missing funding txid when refunding P2SH");
+						if (Objects.equals(bitcoiny.getCurrencyCode(), "ARRR")) {
+							// Pirate Chain custom integration
+
+							PirateChain pirateChain = PirateChain.getInstance();
+							String p2shAddressT3 = pirateChain.deriveP2shAddress(redeemScriptA);
+
+							// Get funding txid
+							String fundingTxidHex = PirateChainHTLC.getUnspentFundingTxid(pirateChain.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+							if (fundingTxidHex == null) {
+								throw new ForeignBlockchainException("Missing funding txid when refunding P2SH");
+							}
+							String fundingTxid58 = Base58.encode(HashCode.fromString(fundingTxidHex).asBytes());
+
+							byte[] privateKey = tradeBotData.getTradePrivateKey();
+							String privateKey58 = Base58.encode(privateKey);
+							String redeemScript58 = Base58.encode(redeemScriptA);
+
+							String txid = PirateChain.getInstance().refundP2sh(p2shAddressT3,
+									receiveAddress, refundAmount.value, redeemScript58, fundingTxid58, lockTime, privateKey58);
+							LOGGER.info("Refund txid: {}", txid);
+						} else {
+							// ElectrumX coins
+
+							ECKey refundKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
+							List<TransactionOutput> fundingOutputs = bitcoiny.getUnspentOutputs(p2shAddressA);
+
+							// Validate the destination foreign blockchain address
+							Address receiving = Address.fromString(bitcoiny.getNetworkParameters(), receiveAddress);
+							if (receiving.getOutputScriptType() != Script.ScriptType.P2PKH)
+								throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+							Transaction p2shRefundTransaction = BitcoinyHTLC.buildRefundTransaction(bitcoiny.getNetworkParameters(), refundAmount, refundKey,
+									fundingOutputs, redeemScriptA, lockTime, receiving.getHash());
+
+							bitcoiny.broadcastTransaction(p2shRefundTransaction);
 						}
-						String fundingTxid58 = Base58.encode(HashCode.fromString(fundingTxidHex).asBytes());
 
-						byte[] privateKey = tradeBotData.getTradePrivateKey();
-						String privateKey58 = Base58.encode(privateKey);
-						String redeemScript58 = Base58.encode(redeemScriptA);
-
-						String txid = PirateChain.getInstance().refundP2sh(p2shAddressT3,
-								receiveAddress, refundAmount.value, redeemScript58, fundingTxid58, lockTime, privateKey58);
-						LOGGER.info("Refund txid: {}", txid);
+						return true;
 					}
-					else {
-						// ElectrumX coins
-
-						ECKey refundKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
-						List<TransactionOutput> fundingOutputs = bitcoiny.getUnspentOutputs(p2shAddressA);
-
-						// Validate the destination foreign blockchain address
-						Address receiving = Address.fromString(bitcoiny.getNetworkParameters(), receiveAddress);
-						if (receiving.getOutputScriptType() != Script.ScriptType.P2PKH)
-							throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
-
-						Transaction p2shRefundTransaction = BitcoinyHTLC.buildRefundTransaction(bitcoiny.getNetworkParameters(), refundAmount, refundKey,
-								fundingOutputs, redeemScriptA, lockTime, receiving.getHash());
-
-						bitcoiny.broadcastTransaction(p2shRefundTransaction);
-					}
-
-					return true;
 				}
 			}
 

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

@@ -47,6 +47,8 @@ public class ChatMessagesWebSocket extends ApiWebSocket {
 						txGroupId,
 						null,
 						null,
+						null,
+						null,
 						null, null, null);
 
 				sendMessages(session, chatMessages);
@@ -74,6 +76,8 @@ public class ChatMessagesWebSocket extends ApiWebSocket {
 					null,
 					null,
 					null,
+					null,
+					null,
 					involvingAddresses,
 					null, null, null);
 

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

@@ -2,6 +2,7 @@ package org.qortal.arbitrary;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.qortal.arbitrary.exception.DataNotPublishedException;
 import org.qortal.arbitrary.exception.MissingDataException;
 import org.qortal.arbitrary.metadata.ArbitraryDataMetadataCache;
 import org.qortal.arbitrary.misc.Service;
@@ -88,7 +89,7 @@ public class ArbitraryDataBuilder {
             if (latestPut == null) {
                 String message = String.format("Couldn't find PUT transaction for name %s, service %s and identifier %s",
                         this.name, this.service, this.identifierString());
-                throw new DataException(message);
+                throw new DataNotPublishedException(message);
             }
             this.latestPutTransaction = latestPut;
 

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

@@ -4,6 +4,7 @@ import org.apache.commons.io.FileUtils;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
+import org.qortal.arbitrary.exception.DataNotPublishedException;
 import org.qortal.arbitrary.exception.MissingDataException;
 import org.qortal.arbitrary.misc.Service;
 import org.qortal.controller.arbitrary.ArbitraryDataBuildManager;
@@ -169,10 +170,18 @@ public class ArbitraryDataReader {
             this.uncompress();
             this.validate();
 
+        } catch (DataNotPublishedException e) {
+            if (e.getMessage() != null) {
+                // Log the message only, to avoid spamming the logs with a full stack trace
+                LOGGER.debug("DataNotPublishedException when trying to load QDN resource: {}", e.getMessage());
+            }
+            this.deleteWorkingDirectory();
+            throw e;
+
         } catch (DataException e) {
             LOGGER.info("DataException when trying to load QDN resource", e);
             this.deleteWorkingDirectory();
-            throw new DataException(e.getMessage());
+            throw e;
 
         } finally {
             this.postExecute();

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

@@ -3,6 +3,7 @@ package org.qortal.arbitrary;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.arbitrary.ArbitraryDataFile.ResourceIdType;
+import org.qortal.arbitrary.exception.DataNotPublishedException;
 import org.qortal.arbitrary.metadata.ArbitraryDataTransactionMetadata;
 import org.qortal.arbitrary.misc.Service;
 import org.qortal.controller.arbitrary.ArbitraryDataBuildManager;
@@ -325,7 +326,7 @@ public class ArbitraryDataResource {
             if (latestPut == null) {
                 String message = String.format("Couldn't find PUT transaction for name %s, service %s and identifier %s",
                         this.resourceId, this.service, this.identifierString());
-                throw new DataException(message);
+                throw new DataNotPublishedException(message);
             }
             this.latestPutTransaction = latestPut;
 

src/main/java/org/qortal/arbitrary/exception/DataNotPublishedException.java

@@ -0,0 +1,22 @@
+package org.qortal.arbitrary.exception;
+
+import org.qortal.repository.DataException;
+
+public class DataNotPublishedException extends DataException {
+
+	public DataNotPublishedException() {
+	}
+
+	public DataNotPublishedException(String message) {
+		super(message);
+	}
+
+	public DataNotPublishedException(String message, Throwable cause) {
+		super(message, cause);
+	}
+
+	public DataNotPublishedException(Throwable cause) {
+		super(cause);
+	}
+
+}

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

@@ -10,9 +10,7 @@ import java.io.File;
 import java.io.IOException;
 import java.nio.file.Path;
 import java.nio.file.Paths;
-import java.util.List;
-import java.util.Map;
-import java.util.Objects;
+import java.util.*;
 
 import static java.util.Arrays.stream;
 import static java.util.stream.Collectors.toMap;
@@ -20,6 +18,31 @@ import static java.util.stream.Collectors.toMap;
 public enum Service {
     AUTO_UPDATE(1, false, null, null),
     ARBITRARY_DATA(100, false, null, null),
+    QCHAT_ATTACHMENT(120, true, 1024*1024L, null) {
+        @Override
+        public ValidationResult validate(Path path) {
+            // Custom validation function to require a single file, with a whitelisted extension
+            int fileCount = 0;
+            File[] files = path.toFile().listFiles();
+            if (files != null) {
+                for (File file : files) {
+                    if (file.isDirectory()) {
+                        return ValidationResult.DIRECTORIES_NOT_ALLOWED;
+                    }
+                    final String extension = FilenameUtils.getExtension(file.getName()).toLowerCase();
+                    final List<String> allowedExtensions = Arrays.asList("zip", "pdf", "txt", "odt", "ods", "doc", "docx", "xls", "xlsx", "ppt", "pptx");
+                    if (extension == null || !allowedExtensions.contains(extension)) {
+                        return ValidationResult.INVALID_FILE_EXTENSION;
+                    }
+                    fileCount++;
+                }
+            }
+            if (fileCount != 1) {
+                return ValidationResult.INVALID_FILE_COUNT;
+            }
+            return ValidationResult.OK;
+        }
+    },
     WEBSITE(200, true, null, null) {
         @Override
         public ValidationResult validate(Path path) {
@@ -143,7 +166,8 @@ public enum Service {
         MISSING_INDEX_FILE(4),
         DIRECTORIES_NOT_ALLOWED(5),
         INVALID_FILE_EXTENSION(6),
-        MISSING_DATA(7);
+        MISSING_DATA(7),
+        INVALID_FILE_COUNT(8);
 
         public final int value;
 

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

@@ -1522,6 +1522,9 @@ public class Block {
 		// Batch update in repository
 		repository.getAccountRepository().modifyMintedBlockCounts(allUniqueExpandedAccounts.stream().map(AccountData::getAddress).collect(Collectors.toList()), +1);
 
+		// Keep track of level bumps in case we need to apply to other entries
+		Map<String, Integer> bumpedAccounts = new HashMap<>();
+
 		// Local changes and also checks for level bump
 		for (AccountData accountData : allUniqueExpandedAccounts) {
 			// Adjust count locally (in Java)
@@ -1535,6 +1538,7 @@ public class Block {
 					if (newLevel > accountData.getLevel()) {
 						// Account has increased in level!
 						accountData.setLevel(newLevel);
+						bumpedAccounts.put(accountData.getAddress(), newLevel);
 						repository.getAccountRepository().setLevel(accountData);
 						LOGGER.trace(() -> String.format("Block minter %s bumped to level %d", accountData.getAddress(), accountData.getLevel()));
 					}
@@ -1542,6 +1546,25 @@ public class Block {
 					break;
 				}
 		}
+
+		// Also bump other entries if need be
+		if (!bumpedAccounts.isEmpty()) {
+			for (ExpandedAccount expandedAccount : expandedAccounts) {
+				Integer newLevel = bumpedAccounts.get(expandedAccount.mintingAccountData.getAddress());
+				if (newLevel != null && expandedAccount.mintingAccountData.getLevel() != newLevel) {
+					expandedAccount.mintingAccountData.setLevel(newLevel);
+					LOGGER.trace("Also bumped {} to level {}", expandedAccount.mintingAccountData.getAddress(), newLevel);
+				}
+
+				if (!expandedAccount.isRecipientAlsoMinter) {
+					newLevel = bumpedAccounts.get(expandedAccount.recipientAccountData.getAddress());
+					if (newLevel != null && expandedAccount.recipientAccountData.getLevel() != newLevel) {
+						expandedAccount.recipientAccountData.setLevel(newLevel);
+						LOGGER.trace("Also bumped {} to level {}", expandedAccount.recipientAccountData.getAddress(), newLevel);
+					}
+				}
+			}
+		}
 	}
 
 	protected void processBlockRewards() throws DataException {

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

@@ -76,7 +76,9 @@ public class BlockChain {
 		disableReferenceTimestamp,
 		increaseOnlineAccountsDifficultyTimestamp,
 		onlineAccountMinterLevelValidationHeight,
-		selfSponsorshipAlgoV1Height;
+		selfSponsorshipAlgoV1Height,
+		feeValidationFixTimestamp,
+		chatReferenceTimestamp;
 	}
 
 	// Custom transaction fees
@@ -98,6 +100,13 @@ public class BlockChain {
 	/** Whether only one registered name is allowed per account. */
 	private boolean oneNamePerAccount = false;
 
+	/** Checkpoints */
+	public static class Checkpoint {
+		public int height;
+		public String signature;
+	}
+	private List<Checkpoint> checkpoints;
+
 	/** Block rewards by block height */
 	public static class RewardByHeight {
 		public int height;
@@ -379,6 +388,10 @@ public class BlockChain {
 		return this.oneNamePerAccount;
 	}
 
+	public List<Checkpoint> getCheckpoints() {
+		return this.checkpoints;
+	}
+
 	public List<RewardByHeight> getBlockRewardsByHeight() {
 		return this.rewardsByHeight;
 	}
@@ -501,6 +514,14 @@ public class BlockChain {
 		return this.featureTriggers.get(FeatureTrigger.onlineAccountMinterLevelValidationHeight.name()).intValue();
 	}
 
+	public long getFeeValidationFixTimestamp() {
+		return this.featureTriggers.get(FeatureTrigger.feeValidationFixTimestamp.name()).longValue();
+	}
+
+	public long getChatReferenceTimestamp() {
+		return this.featureTriggers.get(FeatureTrigger.chatReferenceTimestamp.name()).longValue();
+	}
+
 
 	// More complex getters for aspects that change by height or timestamp
 
@@ -669,6 +690,7 @@ public class BlockChain {
 
 		boolean isTopOnly = Settings.getInstance().isTopOnly();
 		boolean archiveEnabled = Settings.getInstance().isArchiveEnabled();
+		boolean isLite = Settings.getInstance().isLite();
 		boolean canBootstrap = Settings.getInstance().getBootstrap();
 		boolean needsArchiveRebuild = false;
 		BlockData chainTip;
@@ -689,22 +711,44 @@ public class BlockChain {
 					}
 				}
 			}
+
+			// Validate checkpoints
+			// Limited to topOnly nodes for now, in order to reduce risk, and to solve a real-world problem with divergent topOnly nodes
+			// TODO: remove the isTopOnly conditional below once this feature has had more testing time
+			if (isTopOnly && !isLite) {
+				List<Checkpoint> checkpoints = BlockChain.getInstance().getCheckpoints();
+				for (Checkpoint checkpoint : checkpoints) {
+					BlockData blockData = repository.getBlockRepository().fromHeight(checkpoint.height);
+					if (blockData == null) {
+						// Try the archive
+						blockData = repository.getBlockArchiveRepository().fromHeight(checkpoint.height);
+					}
+					if (blockData == null) {
+						LOGGER.trace("Couldn't find block for height {}", checkpoint.height);
+						// This is likely due to the block being pruned, so is safe to ignore.
+						// Continue, as there might be other blocks we can check more definitively.
+						continue;
+					}
+
+					byte[] signature = Base58.decode(checkpoint.signature);
+					if (!Arrays.equals(signature, blockData.getSignature())) {
+						LOGGER.info("Error: block at height {} with signature {} doesn't match checkpoint sig: {}. Bootstrapping...", checkpoint.height, Base58.encode(blockData.getSignature()), checkpoint.signature);
+						needsArchiveRebuild = true;
+						break;
+					}
+					LOGGER.info("Block at height {} matches checkpoint signature", blockData.getHeight());
+				}
+			}
+
 		}
 
-		boolean hasBlocks = (chainTip != null && chainTip.getHeight() > 1);
+		// Check first block is Genesis Block
+		if (!isGenesisBlockValid() || needsArchiveRebuild) {
+			try {
+				rebuildBlockchain();
 
-		if (isTopOnly && hasBlocks) {
-			// Top-only mode is enabled and we have blocks, so it's possible that the genesis block has been pruned
-			// It's best not to validate it, and there's no real need to
-		} else {
-			// Check first block is Genesis Block
-			if (!isGenesisBlockValid() || needsArchiveRebuild) {
-				try {
-					rebuildBlockchain();
-
-				} catch (InterruptedException e) {
-					throw new DataException(String.format("Interrupted when trying to rebuild blockchain: %s", e.getMessage()));
-				}
+			} catch (InterruptedException e) {
+				throw new DataException(String.format("Interrupted when trying to rebuild blockchain: %s", e.getMessage()));
 			}
 		}
 
@@ -713,9 +757,7 @@ public class BlockChain {
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			repository.checkConsistency();
 
-			// Set the number of blocks to validate based on the pruned state of the chain
-			// If pruned, subtract an extra 10 to allow room for error
-			int blocksToValidate = (isTopOnly || archiveEnabled) ? Settings.getInstance().getPruneBlockLimit() - 10 : 1440;
+			int blocksToValidate = Math.min(Settings.getInstance().getPruneBlockLimit() - 10, 1440);
 
 			int startHeight = Math.max(repository.getBlockRepository().getBlockchainHeight() - blocksToValidate, 1);
 			BlockData detachedBlockData = repository.getBlockRepository().getDetachedBlockSignature(startHeight);

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

@@ -769,6 +769,16 @@ public class Controller extends Thread {
 		}
 	};
 
+	public static final Predicate<Peer> wasRecentlyTooDivergent = peer -> {
+		Long now = NTP.getTime();
+		Long peerLastTooDivergentTime = peer.getLastTooDivergentTime();
+		if (now == null || peerLastTooDivergentTime == null)
+			return false;
+
+		// Exclude any peers that were TOO_DIVERGENT in the last 5 mins
+		return (now - peerLastTooDivergentTime < 5 * 60 * 1000L);
+	};
+
 	private long getRandomRepositoryMaintenanceInterval() {
 		final long minInterval = Settings.getInstance().getRepositoryMaintenanceMinInterval();
 		final long maxInterval = Settings.getInstance().getRepositoryMaintenanceMaxInterval();

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

@@ -1121,6 +1121,7 @@ public class Synchronizer extends Thread {
 			// If common block is too far behind us then we're on massively different forks so give up.
 			if (!force && testHeight < ourHeight - MAXIMUM_COMMON_DELTA) {
 				LOGGER.info(String.format("Blockchain too divergent with peer %s", peer));
+				peer.setLastTooDivergentTime(NTP.getTime());
 				return SynchronizationResult.TOO_DIVERGENT;
 			}
 
@@ -1130,6 +1131,9 @@ public class Synchronizer extends Thread {
 			testHeight = Math.max(testHeight - step, 1);
 		}
 
+		// Peer not considered too divergent
+		peer.setLastTooDivergentTime(0L);
+
 		// Prepend test block's summary as first block summary, as summaries returned are *after* test block
 		BlockSummaryData testBlockSummary = new BlockSummaryData(testBlockData);
 		blockSummariesFromCommon.add(0, testBlockSummary);

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

@@ -82,7 +82,7 @@ public class ArbitraryDataFileManager extends Thread {
 
         try {
             // Use a fixed thread pool to execute the arbitrary data file requests
-            int threadCount = 10;
+            int threadCount = 5;
             ExecutorService arbitraryDataFileRequestExecutor = Executors.newFixedThreadPool(threadCount);
             for (int i = 0; i < threadCount; i++) {
                 arbitraryDataFileRequestExecutor.execute(new ArbitraryDataFileRequestThread());
@@ -288,7 +288,7 @@ public class ArbitraryDataFileManager extends Thread {
         // The ID needs to match that of the original request
         message.setId(originalMessage.getId());
 
-        if (!requestingPeer.sendMessage(message)) {
+        if (!requestingPeer.sendMessageWithTimeout(message, (int) ArbitraryDataManager.ARBITRARY_REQUEST_TIMEOUT)) {
             LOGGER.debug("Failed to forward arbitrary data file to peer {}", requestingPeer);
             requestingPeer.disconnect("failed to forward arbitrary data file");
         }
@@ -564,13 +564,16 @@ public class ArbitraryDataFileManager extends Thread {
                 LOGGER.trace("Hash {} exists", hash58);
 
                 // We can serve the file directly as we already have it
+                LOGGER.debug("Sending file {}...", arbitraryDataFile);
                 ArbitraryDataFileMessage arbitraryDataFileMessage = new ArbitraryDataFileMessage(signature, arbitraryDataFile);
                 arbitraryDataFileMessage.setId(message.getId());
-                if (!peer.sendMessage(arbitraryDataFileMessage)) {
-                    LOGGER.debug("Couldn't sent file");
+                if (!peer.sendMessageWithTimeout(arbitraryDataFileMessage, (int) ArbitraryDataManager.ARBITRARY_REQUEST_TIMEOUT)) {
+                    LOGGER.debug("Couldn't send file {}", arbitraryDataFile);
                     peer.disconnect("failed to send file");
                 }
-                LOGGER.debug("Sent file {}", arbitraryDataFile);
+                else {
+                    LOGGER.debug("Sent file {}", arbitraryDataFile);
+                }
             }
             else if (relayInfo != null) {
                 LOGGER.debug("We have relay info for hash {}", Base58.encode(hash));

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

@@ -39,9 +39,11 @@ public class AtStatesPruner implements Runnable {
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			int pruneStartHeight = repository.getATRepository().getAtPruneHeight();
+			int maxLatestAtStatesHeight = PruneManager.getMaxHeightForLatestAtStates(repository);
 
 			repository.discardChanges();
-			repository.getATRepository().rebuildLatestAtStates();
+			repository.getATRepository().rebuildLatestAtStates(maxLatestAtStatesHeight);
+			repository.saveChanges();
 
 			while (!Controller.isStopping()) {
 				repository.discardChanges();
@@ -91,7 +93,8 @@ public class AtStatesPruner implements Runnable {
 					if (upperPrunableHeight > upperBatchHeight) {
 						pruneStartHeight = upperBatchHeight;
 						repository.getATRepository().setAtPruneHeight(pruneStartHeight);
-						repository.getATRepository().rebuildLatestAtStates();
+						maxLatestAtStatesHeight = PruneManager.getMaxHeightForLatestAtStates(repository);
+						repository.getATRepository().rebuildLatestAtStates(maxLatestAtStatesHeight);
 						repository.saveChanges();
 
 						final int finalPruneStartHeight = pruneStartHeight;

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

@@ -26,9 +26,11 @@ public class AtStatesTrimmer implements Runnable {
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			int trimStartHeight = repository.getATRepository().getAtTrimHeight();
+			int maxLatestAtStatesHeight = PruneManager.getMaxHeightForLatestAtStates(repository);
 
 			repository.discardChanges();
-			repository.getATRepository().rebuildLatestAtStates();
+			repository.getATRepository().rebuildLatestAtStates(maxLatestAtStatesHeight);
+			repository.saveChanges();
 
 			while (!Controller.isStopping()) {
 				repository.discardChanges();
@@ -69,7 +71,8 @@ public class AtStatesTrimmer implements Runnable {
 					if (upperTrimmableHeight > upperBatchHeight) {
 						trimStartHeight = upperBatchHeight;
 						repository.getATRepository().setAtTrimHeight(trimStartHeight);
-						repository.getATRepository().rebuildLatestAtStates();
+						maxLatestAtStatesHeight = PruneManager.getMaxHeightForLatestAtStates(repository);
+						repository.getATRepository().rebuildLatestAtStates(maxLatestAtStatesHeight);
 						repository.saveChanges();
 
 						final int finalTrimStartHeight = trimStartHeight;

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

@@ -157,4 +157,18 @@ public class PruneManager {
         return (height < latestUnprunedHeight);
     }
 
+    /**
+     * When rebuilding the latest AT states, we need to specify a maxHeight, so that we aren't tracking
+     * very recent AT states that could potentially be orphaned. This method ensures that AT states
+     * are given a sufficient number of blocks to confirm before being tracked as a latest AT state.
+     */
+    public static int getMaxHeightForLatestAtStates(Repository repository) throws DataException {
+        // Get current chain height, and subtract a certain number of "confirmation" blocks
+        // This is to ensure we are basing our latest AT states data on confirmed blocks -
+        // ones that won't be orphaned in any normal circumstances
+        final int confirmationBlocks = 250;
+        final int chainHeight = repository.getBlockRepository().getBlockchainHeight();
+        return chainHeight - confirmationBlocks;
+    }
+
 }

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

@@ -134,6 +134,8 @@ public class Digibyte extends Bitcoiny {
 			Context bitcoinjContext = new Context(digibyteNet.getParams());
 
 			instance = new Digibyte(digibyteNet, electrumX, bitcoinjContext, CURRENCY_CODE);
+
+			electrumX.setBlockchain(instance);
 		}
 
 		return instance;

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

@@ -40,7 +40,7 @@ public class ElectrumX extends BitcoinyBlockchainProvider {
 	private static final String VERBOSE_TRANSACTIONS_UNSUPPORTED_MESSAGE = "verbose transactions are currently unsupported";
 
 	private static final int RESPONSE_TIME_READINGS = 5;
-	private static final long MAX_AVG_RESPONSE_TIME = 500L; // ms
+	private static final long MAX_AVG_RESPONSE_TIME = 1000L; // ms
 
 	public static class Server {
 		String hostname;

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

@@ -117,7 +117,7 @@ public class PirateWallet {
                 // Restore existing wallet
                 String response = LiteWalletJni.initfromb64(serverUri, params, wallet, saplingOutput64, saplingSpend64);
                 if (response != null && !response.contains("\"initalized\":true")) {
-                    LOGGER.info("Unable to initialize Pirate Chain wallet: {}", response);
+                    LOGGER.info("Unable to initialize Pirate Chain wallet at {}: {}", serverUri, response);
                     return false;
                 }
                 this.seedPhrase = inputSeedPhrase;

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

@@ -138,6 +138,8 @@ public class Ravencoin extends Bitcoiny {
 			Context bitcoinjContext = new Context(ravencoinNet.getParams());
 
 			instance = new Ravencoin(ravencoinNet, electrumX, bitcoinjContext, CURRENCY_CODE);
+
+			electrumX.setBlockchain(instance);
 		}
 
 		return instance;

src/main/java/org/qortal/data/chat/ChatMessage.java

@@ -27,6 +27,8 @@ public class ChatMessage {
 
 	private String recipientName;
 
+	private byte[] chatReference;
+
 	private byte[] data;
 
 	private boolean isText;
@@ -42,8 +44,8 @@ public class ChatMessage {
 
 	// For repository use
 	public ChatMessage(long timestamp, int txGroupId, byte[] reference, byte[] senderPublicKey, String sender,
-			String senderName, String recipient, String recipientName, byte[] data, boolean isText,
-			boolean isEncrypted, byte[] signature) {
+			String senderName, String recipient, String recipientName, byte[] chatReference, byte[] data,
+			boolean isText, boolean isEncrypted, byte[] signature) {
 		this.timestamp = timestamp;
 		this.txGroupId = txGroupId;
 		this.reference = reference;
@@ -52,6 +54,7 @@ public class ChatMessage {
 		this.senderName = senderName;
 		this.recipient = recipient;
 		this.recipientName = recipientName;
+		this.chatReference = chatReference;
 		this.data = data;
 		this.isText = isText;
 		this.isEncrypted = isEncrypted;
@@ -90,6 +93,10 @@ public class ChatMessage {
 		return this.recipientName;
 	}
 
+	public byte[] getChatReference() {
+		return this.chatReference;
+	}
+
 	public byte[] getData() {
 		return this.data;
 	}

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

@@ -26,6 +26,8 @@ public class ChatTransactionData extends TransactionData {
 
 	private String recipient; // can be null
 
+	private byte[] chatReference; // can be null
+
 	@Schema(description = "raw message data, possibly UTF8 text", example = "2yGEbwRFyhPZZckKA")
 	private byte[] data;
 
@@ -44,13 +46,14 @@ public class ChatTransactionData extends TransactionData {
 	}
 
 	public ChatTransactionData(BaseTransactionData baseTransactionData,
-			String sender, int nonce, String recipient, byte[] data, boolean isText, boolean isEncrypted) {
+			String sender, int nonce, String recipient, byte[] chatReference, byte[] data, boolean isText, boolean isEncrypted) {
 		super(TransactionType.CHAT, baseTransactionData);
 
 		this.senderPublicKey = baseTransactionData.creatorPublicKey;
 		this.sender = sender;
 		this.nonce = nonce;
 		this.recipient = recipient;
+		this.chatReference = chatReference;
 		this.data = data;
 		this.isText = isText;
 		this.isEncrypted = isEncrypted;
@@ -78,6 +81,14 @@ public class ChatTransactionData extends TransactionData {
 		return this.recipient;
 	}
 
+	public byte[] getChatReference() {
+		return this.chatReference;
+	}
+
+	public void setChatReference(byte[] chatReference) {
+		this.chatReference = chatReference;
+	}
+
 	public byte[] getData() {
 		return this.data;
 	}

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

@@ -2,6 +2,7 @@ package org.qortal.data.transaction;
 
 import javax.xml.bind.annotation.XmlAccessType;
 import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.XmlElement;
 import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
 
 import org.qortal.transaction.Transaction.TransactionType;
@@ -90,4 +91,17 @@ public class DeployAtTransactionData extends TransactionData {
 		this.aTAddress = AtAddress;
 	}
 
+	// Re-expose creatorPublicKey for this transaction type for JAXB
+	@XmlElement(name = "creatorPublicKey")
+	@Schema(name = "creatorPublicKey", description = "AT creator's public key", example = "2tiMr5LTpaWCgbRvkPK8TFd7k63DyHJMMFFsz9uBf1ZP")
+	public byte[] getAtCreatorPublicKey() {
+		return this.creatorPublicKey;
+	}
+
+	@XmlElement(name = "creatorPublicKey")
+	@Schema(name = "creatorPublicKey", description = "AT creator's public key", example = "2tiMr5LTpaWCgbRvkPK8TFd7k63DyHJMMFFsz9uBf1ZP")
+	public void setAtCreatorPublicKey(byte[] creatorPublicKey) {
+		this.creatorPublicKey = creatorPublicKey;
+	}
+
 }

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

@@ -265,7 +265,7 @@ public enum Handshake {
 	private static final long PEER_VERSION_131 = 0x0100030001L;
 
 	/** Minimum peer version that we are allowed to communicate with */
-	private static final String MIN_PEER_VERSION = "3.7.0";
+	private static final String MIN_PEER_VERSION = "3.8.2";
 
 	private static final int POW_BUFFER_SIZE_PRE_131 = 8 * 1024 * 1024; // bytes
 	private static final int POW_DIFFICULTY_PRE_131 = 8; // leading zero bits

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

@@ -155,6 +155,11 @@ public class Peer {
      */
     private CommonBlockData commonBlockData;
 
+    /**
+     * Last time we detected this peer as TOO_DIVERGENT
+     */
+    private Long lastTooDivergentTime;
+
     // Message stats
 
     private static class MessageStats {
@@ -383,6 +388,14 @@ public class Peer {
         this.commonBlockData = commonBlockData;
     }
 
+    public Long getLastTooDivergentTime() {
+        return this.lastTooDivergentTime;
+    }
+
+    public void setLastTooDivergentTime(Long lastTooDivergentTime) {
+        this.lastTooDivergentTime = lastTooDivergentTime;
+    }
+
     public boolean isSyncInProgress() {
         return this.syncInProgress;
     }

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

@@ -119,7 +119,7 @@ public interface ATRepository {
 	 * <p>
 	 * NOTE: performs implicit <tt>repository.saveChanges()</tt>.
 	 */
-	public void rebuildLatestAtStates() throws DataException;
+	public void rebuildLatestAtStates(int maxHeight) throws DataException;
 
 
 	/** Returns height of first trimmable AT state. */

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

@@ -14,8 +14,8 @@ 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, byte[] reference, List<String> involving,
-			Integer limit, Integer offset, Boolean reverse) throws DataException;
+			Integer txGroupId, byte[] reference, byte[] chatReferenceBytes, Boolean hasChatReference,
+			List<String> involving, Integer limit, Integer offset, Boolean reverse) throws DataException;
 
 	public ChatMessage toChatMessage(ChatTransactionData chatTransactionData) throws DataException;
 

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

@@ -131,7 +131,14 @@ public interface GroupRepository {
 
 	public GroupBanData getBan(int groupId, String member) throws DataException;
 
-	public boolean banExists(int groupId, String offender) throws DataException;
+	/**
+	 * IMPORTANT: when using banExists() as part of validation, the timestamp must be that of the transaction that
+	 * is calling banExists() as part of its validation. It must NOT be the current time, unless this is being
+	 * called outside of validation, as part of an on demand check for a ban existing (such as via an API call).
+	 * This is because we need to evaluate a ban's status based on the time of the subsequent transaction, as
+	 * validation will not occur at a fixed time for every node. For some, it could be months into the future.
+	 */
+	public boolean banExists(int groupId, String offender, long timestamp) throws DataException;
 
 	public List<GroupBanData> getGroupBans(int groupId, Integer limit, Integer offset, Boolean reverse) throws DataException;
 

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

@@ -603,7 +603,7 @@ public class HSQLDBATRepository implements ATRepository {
 
 
 	@Override
-	public void rebuildLatestAtStates() throws DataException {
+	public void rebuildLatestAtStates(int maxHeight) throws DataException {
 		// latestATStatesLock is to prevent concurrent updates on LatestATStates
 		// that could result in one process using a partial or empty dataset
 		// because it was in the process of being rebuilt by another thread
@@ -624,11 +624,12 @@ public class HSQLDBATRepository implements ATRepository {
 					+ "CROSS JOIN LATERAL("
 					+ "SELECT height FROM ATStates "
 					+ "WHERE ATStates.AT_address = ATs.AT_address "
+					+ "AND height <= ?"
 					+ "ORDER BY AT_address DESC, height DESC LIMIT 1"
 					+ ") "
 					+ ")";
 			try {
-				this.repository.executeCheckedUpdate(insertSql);
+				this.repository.executeCheckedUpdate(insertSql, maxHeight);
 			} catch (SQLException e) {
 				repository.examineException(e);
 				throw new DataException("Unable to populate temporary latest AT states cache in repository", e);

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

@@ -24,8 +24,8 @@ public class HSQLDBChatRepository implements ChatRepository {
 
 	@Override
 	public List<ChatMessage> getMessagesMatchingCriteria(Long before, Long after, Integer txGroupId, byte[] referenceBytes,
-			List<String> involving, Integer limit, Integer offset, Boolean reverse)
-			throws DataException {
+			byte[] chatReferenceBytes, Boolean hasChatReference, List<String> involving,
+			Integer limit, Integer offset, Boolean reverse) throws DataException {
 		// Check args meet expectations
 		if ((txGroupId != null && involving != null && !involving.isEmpty())
 				|| (txGroupId == null && (involving == null || involving.size() != 2)))
@@ -35,7 +35,7 @@ public class HSQLDBChatRepository implements ChatRepository {
 
 		sql.append("SELECT created_when, tx_group_id, Transactions.reference, creator, "
 				+ "sender, SenderNames.name, recipient, RecipientNames.name, "
-				+ "data, is_text, is_encrypted, signature "
+				+ "chat_reference, data, is_text, is_encrypted, signature "
 				+ "FROM ChatTransactions "
 				+ "JOIN Transactions USING (signature) "
 				+ "LEFT OUTER JOIN Names AS SenderNames ON SenderNames.owner = sender "
@@ -62,6 +62,18 @@ public class HSQLDBChatRepository implements ChatRepository {
 			bindParams.add(referenceBytes);
 		}
 
+		if (chatReferenceBytes != null) {
+			whereClauses.add("chat_reference = ?");
+			bindParams.add(chatReferenceBytes);
+		}
+
+		if (hasChatReference != null && hasChatReference == true) {
+			whereClauses.add("chat_reference IS NOT NULL");
+		}
+		else if (hasChatReference != null && hasChatReference == false) {
+			whereClauses.add("chat_reference IS NULL");
+		}
+
 		if (txGroupId != null) {
 			whereClauses.add("tx_group_id = " + txGroupId); // int safe to use literally
 			whereClauses.add("recipient IS NULL");
@@ -103,13 +115,14 @@ public class HSQLDBChatRepository implements ChatRepository {
 				String senderName = resultSet.getString(6);
 				String recipient = resultSet.getString(7);
 				String recipientName = resultSet.getString(8);
-				byte[] data = resultSet.getBytes(9);
-				boolean isText = resultSet.getBoolean(10);
-				boolean isEncrypted = resultSet.getBoolean(11);
-				byte[] signature = resultSet.getBytes(12);
+				byte[] chatReference = resultSet.getBytes(9);
+				byte[] data = resultSet.getBytes(10);
+				boolean isText = resultSet.getBoolean(11);
+				boolean isEncrypted = resultSet.getBoolean(12);
+				byte[] signature = resultSet.getBytes(13);
 
 				ChatMessage chatMessage = new ChatMessage(timestamp, groupId, reference, senderPublicKey, sender,
-						senderName, recipient, recipientName, data, isText, isEncrypted, signature);
+						senderName, recipient, recipientName, chatReference, data, isText, isEncrypted, signature);
 
 				chatMessages.add(chatMessage);
 			} while (resultSet.next());
@@ -141,13 +154,14 @@ public class HSQLDBChatRepository implements ChatRepository {
 			byte[] senderPublicKey = chatTransactionData.getSenderPublicKey();
 			String sender = chatTransactionData.getSender();
 			String recipient = chatTransactionData.getRecipient();
+			byte[] chatReference = chatTransactionData.getChatReference();
 			byte[] data = chatTransactionData.getData();
 			boolean isText = chatTransactionData.getIsText();
 			boolean isEncrypted = chatTransactionData.getIsEncrypted();
 			byte[] signature = chatTransactionData.getSignature();
 
 			return new ChatMessage(timestamp, groupId, reference, senderPublicKey, sender,
-					senderName, recipient, recipientName, data, isText, isEncrypted, signature);
+					senderName, recipient, recipientName, chatReference, data, isText, isEncrypted, signature);
 		} catch (SQLException e) {
 			throw new DataException("Unable to fetch convert chat transaction from repository", e);
 		}

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

@@ -99,7 +99,7 @@ public class HSQLDBDatabasePruning {
 
         // It's essential that we rebuild the latest AT states here, as we are using this data in the next query.
         // Failing to do this will result in important AT states being deleted, rendering the database unusable.
-        repository.getATRepository().rebuildLatestAtStates();
+        repository.getATRepository().rebuildLatestAtStates(endHeight);
 
 
         // Loop through all the LatestATStates and copy them to the new table

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

@@ -980,6 +980,14 @@ public class HSQLDBDatabaseUpdates {
 					stmt.execute("ALTER TABLE Accounts ADD blocks_minted_penalty INTEGER NOT NULL DEFAULT 0");
 					break;
 
+				case 45:
+					// Add a chat reference, to allow one message to reference another, and for this to be easily
+					// searchable. Null values are allowed as most transactions won't have a reference.
+					stmt.execute("ALTER TABLE ChatTransactions ADD chat_reference Signature");
+					// For finding chat messages by reference
+					stmt.execute("CREATE INDEX ChatTransactionsChatReferenceIndex ON ChatTransactions (chat_reference)");
+					break;
+
 				default:
 					// nothing to do
 					return false;

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

@@ -777,9 +777,9 @@ public class HSQLDBGroupRepository implements GroupRepository {
 	}
 
 	@Override
-	public boolean banExists(int groupId, String offender) throws DataException {
+	public boolean banExists(int groupId, String offender, long timestamp) throws DataException {
 		try {
-			return this.repository.exists("GroupBans", "group_id = ? AND offender = ?", groupId, offender);
+			return this.repository.exists("GroupBans", "group_id = ? AND offender = ? AND (expires_when IS NULL OR expires_when > ?)", groupId, offender, timestamp);
 		} catch (SQLException e) {
 			throw new DataException("Unable to check for group ban in repository", e);
 		}

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

@@ -17,7 +17,7 @@ public class HSQLDBChatTransactionRepository extends HSQLDBTransactionRepository
 	}
 
 	TransactionData fromBase(BaseTransactionData baseTransactionData) throws DataException {
-		String sql = "SELECT sender, nonce, recipient, is_text, is_encrypted, data FROM ChatTransactions WHERE signature = ?";
+		String sql = "SELECT sender, nonce, recipient, is_text, is_encrypted, data, chat_reference FROM ChatTransactions WHERE signature = ?";
 
 		try (ResultSet resultSet = this.repository.checkedExecute(sql, baseTransactionData.getSignature())) {
 			if (resultSet == null)
@@ -29,8 +29,9 @@ public class HSQLDBChatTransactionRepository extends HSQLDBTransactionRepository
 			boolean isText = resultSet.getBoolean(4);
 			boolean isEncrypted = resultSet.getBoolean(5);
 			byte[] data = resultSet.getBytes(6);
+			byte[] chatReference = resultSet.getBytes(7);
 
-			return new ChatTransactionData(baseTransactionData, sender, nonce, recipient, data, isText, isEncrypted);
+			return new ChatTransactionData(baseTransactionData, sender, nonce, recipient, chatReference, data, isText, isEncrypted);
 		} catch (SQLException e) {
 			throw new DataException("Unable to fetch chat transaction from repository", e);
 		}
@@ -45,7 +46,7 @@ public class HSQLDBChatTransactionRepository extends HSQLDBTransactionRepository
 		saveHelper.bind("signature", chatTransactionData.getSignature()).bind("nonce", chatTransactionData.getNonce())
 				.bind("sender", chatTransactionData.getSender()).bind("recipient", chatTransactionData.getRecipient())
 				.bind("is_text", chatTransactionData.getIsText()).bind("is_encrypted", chatTransactionData.getIsEncrypted())
-				.bind("data", chatTransactionData.getData());
+				.bind("data", chatTransactionData.getData()).bind("chat_reference", chatTransactionData.getChatReference());
 
 		try {
 			saveHelper.execute(this.repository);

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

@@ -110,7 +110,13 @@ public class Settings {
 	/** Maximum number of unconfirmed transactions allowed per account */
 	private int maxUnconfirmedPerAccount = 25;
 	/** Max milliseconds into future for accepting new, unconfirmed transactions */
-	private int maxTransactionTimestampFuture = 24 * 60 * 60 * 1000; // milliseconds
+	private int maxTransactionTimestampFuture = 30 * 60 * 1000; // milliseconds
+
+	/** Maximum number of CHAT transactions allowed per account in recent timeframe */
+	private int maxRecentChatMessagesPerAccount = 250;
+	/** Maximum age of a CHAT transaction to be considered 'recent' */
+	private long recentChatMessagesMaxAge = 60 * 60 * 1000L; // milliseconds
+
 	/** Whether we check, fetch and install auto-updates */
 	private boolean autoUpdateEnabled = true;
 	/** How long between repository backups (ms), or 0 if disabled. */
@@ -153,7 +159,7 @@ public class Settings {
 	 * This prevents the node from being able to serve older blocks */
 	private boolean topOnly = false;
 	/** The amount of recent blocks we should keep when pruning */
-	private int pruneBlockLimit = 1450;
+	private int pruneBlockLimit = 6000;
 
 	/** How often to attempt AT state pruning (ms). */
 	private long atStatesPruneInterval = 3219L; // milliseconds
@@ -209,7 +215,7 @@ public class Settings {
 	public long recoveryModeTimeout = 10 * 60 * 1000L;
 
 	/** Minimum peer version number required in order to sync with them */
-	private String minPeerVersion = "3.7.0";
+	private String minPeerVersion = "3.8.2";
 	/** 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 */
@@ -267,7 +273,7 @@ public class Settings {
 	private String[] bootstrapHosts = new String[] {
 			"http://bootstrap.qortal.org",
 			"http://bootstrap2.qortal.org",
-			"http://62.171.190.193"
+			"http://bootstrap.qortal.online"
 	};
 
 	// Auto-update sources
@@ -640,6 +646,14 @@ public class Settings {
 		return this.maxTransactionTimestampFuture;
 	}
 
+	public int getMaxRecentChatMessagesPerAccount() {
+		return this.maxRecentChatMessagesPerAccount;
+	}
+
+	public long getRecentChatMessagesMaxAge() {
+		return recentChatMessagesMaxAge;
+	}
+
 	public int getBlockCacheSize() {
 		return this.blockCacheSize;
 	}

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

@@ -24,6 +24,7 @@ import org.qortal.transform.Transformer;
 import org.qortal.transform.transaction.ArbitraryTransactionTransformer;
 import org.qortal.transform.transaction.TransactionTransformer;
 import org.qortal.utils.ArbitraryTransactionUtils;
+import org.qortal.utils.NTP;
 
 public class ArbitraryTransaction extends Transaction {
 
@@ -34,9 +35,13 @@ public class ArbitraryTransaction extends Transaction {
 	public static final int MAX_DATA_SIZE = 4000;
 	public static final int MAX_METADATA_LENGTH = 32;
 	public static final int HASH_LENGTH = TransactionTransformer.SHA256_LENGTH;
-	public static final int POW_BUFFER_SIZE = 8 * 1024 * 1024; // bytes
 	public static final int MAX_IDENTIFIER_LENGTH = 64;
 
+	/** If time difference between transaction and now is greater than this then we don't verify proof-of-work. */
+	public static final long HISTORIC_THRESHOLD = 2 * 7 * 24 * 60 * 60 * 1000L;
+	public static final int POW_BUFFER_SIZE = 8 * 1024 * 1024; // bytes
+
+
 	// Constructors
 
 	public ArbitraryTransaction(Repository repository, TransactionData transactionData) {
@@ -202,9 +207,11 @@ public class ArbitraryTransaction extends Transaction {
 			// Clear nonce from transactionBytes
 			ArbitraryTransactionTransformer.clearNonce(transactionBytes);
 
-			// Check nonce
-			int difficulty = ArbitraryDataManager.getInstance().getPowDifficulty();
-			return MemoryPoW.verify2(transactionBytes, POW_BUFFER_SIZE, difficulty, nonce);
+			// We only need to check nonce for recent transactions due to PoW verification overhead
+			if (NTP.getTime() - this.arbitraryTransactionData.getTimestamp() < HISTORIC_THRESHOLD) {
+				int difficulty = ArbitraryDataManager.getInstance().getPowDifficulty();
+				return MemoryPoW.verify2(transactionBytes, POW_BUFFER_SIZE, difficulty, nonce);
+			}
 		}
 
 		return true;

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

@@ -73,7 +73,7 @@ public class CancelGroupBanTransaction extends Transaction {
 		Account member = getMember();
 
 		// Check ban actually exists
-		if (!this.repository.getGroupRepository().banExists(groupId, member.getAddress()))
+		if (!this.repository.getGroupRepository().banExists(groupId, member.getAddress(), this.groupUnbanTransactionData.getTimestamp()))
 			return ValidationResult.BAN_UNKNOWN;
 
 		// Check admin has enough funds

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

@@ -1,7 +1,9 @@
 package org.qortal.transaction;
 
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import java.util.function.Predicate;
 
 import org.qortal.account.Account;
 import org.qortal.account.PublicKeyAccount;
@@ -16,9 +18,11 @@ import org.qortal.list.ResourceListManager;
 import org.qortal.repository.DataException;
 import org.qortal.repository.GroupRepository;
 import org.qortal.repository.Repository;
+import org.qortal.settings.Settings;
 import org.qortal.transform.TransformationException;
 import org.qortal.transform.transaction.ChatTransactionTransformer;
 import org.qortal.transform.transaction.TransactionTransformer;
+import org.qortal.utils.NTP;
 
 public class ChatTransaction extends Transaction {
 
@@ -26,10 +30,11 @@ public class ChatTransaction extends Transaction {
 	private ChatTransactionData chatTransactionData;
 
 	// Other useful constants
-	public static final int MAX_DATA_SIZE = 1024;
+	public static final int MAX_DATA_SIZE = 4000;
 	public static final int POW_BUFFER_SIZE = 8 * 1024 * 1024; // bytes
-	public static final int POW_DIFFICULTY_WITH_QORT = 8; // leading zero bits
-	public static final int POW_DIFFICULTY_NO_QORT = 12; // leading zero bits
+	public static final int POW_DIFFICULTY_ABOVE_QORT_THRESHOLD = 8; // leading zero bits
+	public static final int POW_DIFFICULTY_BELOW_QORT_THRESHOLD = 18; // leading zero bits
+	public static final long POW_QORT_THRESHOLD = 400000000L;
 
 	// Constructors
 
@@ -78,7 +83,7 @@ public class ChatTransaction extends Transaction {
 		// Clear nonce from transactionBytes
 		ChatTransactionTransformer.clearNonce(transactionBytes);
 
-		int difficulty = this.getSender().getConfirmedBalance(Asset.QORT) > 0 ? POW_DIFFICULTY_WITH_QORT : POW_DIFFICULTY_NO_QORT;
+		int difficulty = this.getSender().getConfirmedBalance(Asset.QORT) >= POW_QORT_THRESHOLD ? POW_DIFFICULTY_ABOVE_QORT_THRESHOLD : POW_DIFFICULTY_BELOW_QORT_THRESHOLD;
 
 		// Calculate nonce
 		this.chatTransactionData.setNonce(MemoryPoW.compute2(transactionBytes, POW_BUFFER_SIZE, difficulty));
@@ -145,6 +150,11 @@ public class ChatTransaction extends Transaction {
 	public ValidationResult isValid() throws DataException {
 		// Nonce checking is done via isSignatureValid() as that method is only called once per import
 
+		// Disregard messages with timestamp too far in the future (we have stricter limits for CHAT transactions)
+		if (this.chatTransactionData.getTimestamp() > NTP.getTime() + (5 * 60 * 1000L)) {
+			return ValidationResult.TIMESTAMP_TOO_NEW;
+		}
+
 		// Check for blocked author by address
 		ResourceListManager listManager = ResourceListManager.getInstance();
 		if (listManager.listContains("blockedAddresses", this.chatTransactionData.getSender(), true)) {
@@ -163,6 +173,14 @@ public class ChatTransaction extends Transaction {
 			}
 		}
 
+		PublicKeyAccount creator = this.getCreator();
+		if (creator == null)
+			return ValidationResult.MISSING_CREATOR;
+
+		// Reject if unconfirmed pile already has X recent CHAT transactions from same creator
+		if (countRecentChatTransactionsByCreator(creator) >= Settings.getInstance().getMaxRecentChatMessagesPerAccount())
+			return ValidationResult.TOO_MANY_UNCONFIRMED;
+
 		// If we exist in the repository then we've been imported as unconfirmed,
 		// but we don't want to make it into a block, so return fake non-OK result.
 		if (this.repository.getTransactionRepository().exists(this.chatTransactionData.getSignature()))
@@ -204,7 +222,7 @@ public class ChatTransaction extends Transaction {
 
 		int difficulty;
 		try {
-			difficulty = this.getSender().getConfirmedBalance(Asset.QORT) > 0 ? POW_DIFFICULTY_WITH_QORT : POW_DIFFICULTY_NO_QORT;
+			difficulty = this.getSender().getConfirmedBalance(Asset.QORT) >= POW_QORT_THRESHOLD ? POW_DIFFICULTY_ABOVE_QORT_THRESHOLD : POW_DIFFICULTY_BELOW_QORT_THRESHOLD;
 		} catch (DataException e) {
 			return false;
 		}
@@ -213,6 +231,26 @@ public class ChatTransaction extends Transaction {
 		return MemoryPoW.verify2(transactionBytes, POW_BUFFER_SIZE, difficulty, nonce);
 	}
 
+	private int countRecentChatTransactionsByCreator(PublicKeyAccount creator) throws DataException {
+		List<TransactionData> unconfirmedTransactions = repository.getTransactionRepository().getUnconfirmedTransactions();
+		final Long now = NTP.getTime();
+		long recentThreshold = Settings.getInstance().getRecentChatMessagesMaxAge();
+
+		// We only care about chat transactions, and only those that are considered 'recent'
+		Predicate<TransactionData> hasSameCreatorAndIsRecentChat = transactionData -> {
+			if (transactionData.getType() != TransactionType.CHAT)
+				return false;
+
+			if (transactionData.getTimestamp() < now - recentThreshold)
+				return false;
+
+			return Arrays.equals(creator.getPublicKey(), transactionData.getCreatorPublicKey());
+		};
+
+		return (int) unconfirmedTransactions.stream().filter(hasSameCreatorAndIsRecentChat).count();
+	}
+
+
 	/**
 	 * Ensure there's at least a skeleton account so people
 	 * can retrieve sender's public key using address, even if all their messages

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

@@ -78,7 +78,7 @@ public class GroupInviteTransaction extends Transaction {
 			return ValidationResult.ALREADY_GROUP_MEMBER;
 
 		// Check invitee is not banned
-		if (this.repository.getGroupRepository().banExists(groupId, invitee.getAddress()))
+		if (this.repository.getGroupRepository().banExists(groupId, invitee.getAddress(), this.groupInviteTransactionData.getTimestamp()))
 			return ValidationResult.BANNED_FROM_GROUP;
 
 		// Check creator has enough funds

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

@@ -53,7 +53,7 @@ public class JoinGroupTransaction extends Transaction {
 			return ValidationResult.ALREADY_GROUP_MEMBER;
 
 		// Check member is not banned
-		if (this.repository.getGroupRepository().banExists(groupId, joiner.getAddress()))
+		if (this.repository.getGroupRepository().banExists(groupId, joiner.getAddress(), this.joinGroupTransactionData.getTimestamp()))
 			return ValidationResult.BANNED_FROM_GROUP;
 
 		// Check join request doesn't already exist

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

@@ -4,7 +4,9 @@ import java.util.Collections;
 import java.util.List;
 
 import org.qortal.account.Account;
+import org.qortal.account.PublicKeyAccount;
 import org.qortal.api.resource.TransactionsResource.ConfirmationStatus;
+import org.qortal.asset.Asset;
 import org.qortal.crypto.MemoryPoW;
 import org.qortal.data.transaction.PublicizeTransactionData;
 import org.qortal.data.transaction.TransactionData;
@@ -26,7 +28,7 @@ public class PublicizeTransaction extends Transaction {
 	/** If time difference between transaction and now is greater than this then we don't verify proof-of-work. */
 	public static final long HISTORIC_THRESHOLD = 2 * 7 * 24 * 60 * 60 * 1000L;
 	public static final int POW_BUFFER_SIZE = 8 * 1024 * 1024; // bytes
-	public static final int POW_DIFFICULTY = 15; // leading zero bits
+	public static final int POW_DIFFICULTY = 14; // leading zero bits
 
 	// Constructors
 
@@ -102,6 +104,12 @@ public class PublicizeTransaction extends Transaction {
 			if (!verifyNonce())
 				return ValidationResult.INCORRECT_NONCE;
 
+		// Validate fee if one has been included
+		PublicKeyAccount creator = this.getCreator();
+		if (this.transactionData.getFee() > 0)
+			if (creator.getConfirmedBalance(Asset.QORT) < this.transactionData.getFee())
+				return ValidationResult.NO_BALANCE;
+
 		return ValidationResult.OK;
 	}
 

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

@@ -163,9 +163,12 @@ public class RewardShareTransaction extends Transaction {
 				return ValidationResult.SELF_SHARE_EXISTS;
 		}
 
-		// Fee checking needed if not setting up new self-share
-		if (!(isRecipientAlsoMinter && existingRewardShareData == null))
-			// Check creator has enough funds
+		// Check creator has enough funds
+		if (this.rewardShareTransactionData.getTimestamp() >= BlockChain.getInstance().getFeeValidationFixTimestamp())
+			if (creator.getConfirmedBalance(Asset.QORT) < this.rewardShareTransactionData.getFee())
+				return ValidationResult.NO_BALANCE;
+
+		else if (!(isRecipientAlsoMinter && existingRewardShareData == null))
 			if (creator.getConfirmedBalance(Asset.QORT) < this.rewardShareTransactionData.getFee())
 				return ValidationResult.NO_BALANCE;
 

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

@@ -103,7 +103,7 @@ public class UpdateGroupTransaction extends Transaction {
 		Account newOwner = getNewOwner();
 
 		// Check new owner is not banned
-		if (this.repository.getGroupRepository().banExists(this.updateGroupTransactionData.getGroupId(), newOwner.getAddress()))
+		if (this.repository.getGroupRepository().banExists(this.updateGroupTransactionData.getGroupId(), newOwner.getAddress(), this.updateGroupTransactionData.getTimestamp()))
 			return ValidationResult.BANNED_FROM_GROUP;
 
 		return ValidationResult.OK;

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

@@ -4,6 +4,7 @@ import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.nio.ByteBuffer;
 
+import org.qortal.block.BlockChain;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.transaction.BaseTransactionData;
 import org.qortal.data.transaction.ChatTransactionData;
@@ -22,11 +23,13 @@ public class ChatTransactionTransformer extends TransactionTransformer {
 	private static final int NONCE_LENGTH = INT_LENGTH;
 	private static final int HAS_RECIPIENT_LENGTH = BOOLEAN_LENGTH;
 	private static final int RECIPIENT_LENGTH = ADDRESS_LENGTH;
+	private static final int HAS_CHAT_REFERENCE_LENGTH = BOOLEAN_LENGTH;
+	private static final int CHAT_REFERENCE_LENGTH = SIGNATURE_LENGTH;
 	private static final int DATA_SIZE_LENGTH = INT_LENGTH;
 	private static final int IS_TEXT_LENGTH = BOOLEAN_LENGTH;
 	private static final int IS_ENCRYPTED_LENGTH = BOOLEAN_LENGTH;
 
-	private static final int EXTRAS_LENGTH = NONCE_LENGTH + HAS_RECIPIENT_LENGTH + DATA_SIZE_LENGTH + IS_ENCRYPTED_LENGTH + IS_TEXT_LENGTH;
+	private static final int EXTRAS_LENGTH = NONCE_LENGTH + HAS_RECIPIENT_LENGTH + DATA_SIZE_LENGTH + IS_ENCRYPTED_LENGTH + IS_TEXT_LENGTH + HAS_CHAT_REFERENCE_LENGTH;
 
 	protected static final TransactionLayout layout;
 
@@ -77,13 +80,24 @@ public class ChatTransactionTransformer extends TransactionTransformer {
 
 		long fee = byteBuffer.getLong();
 
+		byte[] chatReference = null;
+
+		if (timestamp >= BlockChain.getInstance().getChatReferenceTimestamp()) {
+			boolean hasChatReference = byteBuffer.get() != 0;
+
+			if (hasChatReference) {
+				chatReference = new byte[CHAT_REFERENCE_LENGTH];
+				byteBuffer.get(chatReference);
+			}
+		}
+
 		byte[] signature = new byte[SIGNATURE_LENGTH];
 		byteBuffer.get(signature);
 
 		BaseTransactionData baseTransactionData = new BaseTransactionData(timestamp, txGroupId, reference, senderPublicKey, fee, signature);
 
 		String sender = Crypto.toAddress(senderPublicKey);
-		return new ChatTransactionData(baseTransactionData, sender, nonce, recipient, data, isText, isEncrypted);
+		return new ChatTransactionData(baseTransactionData, sender, nonce, recipient, chatReference, data, isText, isEncrypted);
 	}
 
 	public static int getDataLength(TransactionData transactionData) {
@@ -94,6 +108,9 @@ public class ChatTransactionTransformer extends TransactionTransformer {
 		if (chatTransactionData.getRecipient() != null)
 			dataLength += RECIPIENT_LENGTH;
 
+		if (chatTransactionData.getChatReference() != null)
+			dataLength += CHAT_REFERENCE_LENGTH;
+
 		return dataLength;
 	}
 
@@ -124,6 +141,16 @@ public class ChatTransactionTransformer extends TransactionTransformer {
 
 			bytes.write(Longs.toByteArray(chatTransactionData.getFee()));
 
+			if (transactionData.getTimestamp() >= BlockChain.getInstance().getChatReferenceTimestamp()) {
+				// Include chat reference if it's not null
+				if (chatTransactionData.getChatReference() != null) {
+					bytes.write((byte) 1);
+					bytes.write(chatTransactionData.getChatReference());
+				} else {
+					bytes.write((byte) 0);
+				}
+			}
+
 			if (chatTransactionData.getSignature() != null)
 				bytes.write(chatTransactionData.getSignature());
 

src/main/resources/blockchain.json

@@ -82,9 +82,14 @@
 		"transactionV6Timestamp": 9999999999999,
 		"disableReferenceTimestamp": 1655222400000,
 		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999,
-		"onlineAccountMinterLevelValidationHeight": 1093400,
-		"selfSponsorshipAlgoV1Height": 1092400
+		"onlineAccountMinterLevelValidationHeight": 1092000,
+		"selfSponsorshipAlgoV1Height": 1092400,
+		"feeValidationFixTimestamp": 1671918000000,
+		"chatReferenceTimestamp": 1674316800000
 	},
+	"checkpoints": [
+		{ "height": 1131800, "signature": "EpRam4PLdKzULMp7xNU7XG964AKfioG3g1k7cxwxWXnXspPwnjfF6UncEz4feuSA9mr1vW5d3YQPGruXYjj4vciSh4SPj5iWRxkHRWFeRpQnmVUyaVumuBTwM8nnLKJTdtkZnd6d8Mc5mVFdHs6EwLBTY4HECoRcbo4e4FwkfqVon4M" }
+	],
 	"genesisInfo": {
 		"version": 4,
 		"timestamp": "1593450000000",

src/test/java/org/qortal/test/BlockArchiveTests.java

@@ -23,7 +23,6 @@ import org.qortal.transform.TransformationException;
 import org.qortal.transform.block.BlockTransformation;
 import org.qortal.utils.BlockArchiveUtils;
 import org.qortal.utils.NTP;
-import org.qortal.utils.Triple;
 
 import java.io.File;
 import java.io.IOException;
@@ -314,9 +313,10 @@ public class BlockArchiveTests extends Common {
 			repository.getBlockRepository().setBlockPruneHeight(901);
 
 			// Prune the AT states for the archived blocks
-			repository.getATRepository().rebuildLatestAtStates();
+			repository.getATRepository().rebuildLatestAtStates(900);
+			repository.saveChanges();
 			int numATStatesPruned = repository.getATRepository().pruneAtStates(0, 900);
-			assertEquals(900-1, numATStatesPruned);
+			assertEquals(900-2, numATStatesPruned); // Minus 1 for genesis block, and another for the latest AT state
 			repository.getATRepository().setAtPruneHeight(901);
 
 			// Now ensure the SQL repository is missing blocks 2 and 900...
@@ -563,16 +563,23 @@ public class BlockArchiveTests extends Common {
 			// Trim the first 500 blocks
 			repository.getBlockRepository().trimOldOnlineAccountsSignatures(0, 500);
 			repository.getBlockRepository().setOnlineAccountsSignaturesTrimHeight(501);
+			repository.getATRepository().rebuildLatestAtStates(500);
 			repository.getATRepository().trimAtStates(0, 500, 1000);
 			repository.getATRepository().setAtTrimHeight(501);
 
-			// Now block 500 should only have the AT state data hash
-			block500AtStatesData = repository.getATRepository().getBlockATStatesAtHeight(500);
-			atStatesData = repository.getATRepository().getATStateAtHeight(block500AtStatesData.get(0).getATAddress(), 500);
+			// Now block 499 should only have the AT state data hash
+			List<ATStateData> block499AtStatesData = repository.getATRepository().getBlockATStatesAtHeight(499);
+			atStatesData = repository.getATRepository().getATStateAtHeight(block499AtStatesData.get(0).getATAddress(), 499);
 			assertNotNull(atStatesData.getStateHash());
 			assertNull(atStatesData.getStateData());
 
-			// ... but block 501 should have the full data
+			// ... but block 500 should have the full data (due to being retained as the "latest" AT state in the trimmed range
+			block500AtStatesData = repository.getATRepository().getBlockATStatesAtHeight(500);
+			atStatesData = repository.getATRepository().getATStateAtHeight(block500AtStatesData.get(0).getATAddress(), 500);
+			assertNotNull(atStatesData.getStateHash());
+			assertNotNull(atStatesData.getStateData());
+
+			// ... and block 501 should also have the full data
 			List<ATStateData> block501AtStatesData = repository.getATRepository().getBlockATStatesAtHeight(501);
 			atStatesData = repository.getATRepository().getATStateAtHeight(block501AtStatesData.get(0).getATAddress(), 501);
 			assertNotNull(atStatesData.getStateHash());
@@ -612,9 +619,10 @@ public class BlockArchiveTests extends Common {
 			repository.getBlockRepository().setBlockPruneHeight(501);
 
 			// Prune the AT states for the archived blocks
-			repository.getATRepository().rebuildLatestAtStates();
+			repository.getATRepository().rebuildLatestAtStates(500);
+			repository.saveChanges();
 			int numATStatesPruned = repository.getATRepository().pruneAtStates(2, 500);
-			assertEquals(499, numATStatesPruned);
+			assertEquals(498, numATStatesPruned); // Minus 1 for genesis block, and another for the latest AT state
 			repository.getATRepository().setAtPruneHeight(501);
 
 			// Now ensure the SQL repository is missing blocks 2 and 500...

src/test/java/org/qortal/test/BootstrapTests.java

@@ -176,7 +176,8 @@ public class BootstrapTests extends Common {
         repository.getBlockRepository().setBlockPruneHeight(901);
 
         // Prune the AT states for the archived blocks
-        repository.getATRepository().rebuildLatestAtStates();
+        repository.getATRepository().rebuildLatestAtStates(900);
+        repository.saveChanges();
         repository.getATRepository().pruneAtStates(0, 900);
         repository.getATRepository().setAtPruneHeight(901);
 

src/test/java/org/qortal/test/PruneTests.java

@@ -1,16 +1,33 @@
 package org.qortal.test;
 
+import com.google.common.hash.HashCode;
 import org.junit.Before;
 import org.junit.Test;
+import org.qortal.account.Account;
 import org.qortal.account.PrivateKeyAccount;
+import org.qortal.asset.Asset;
+import org.qortal.block.Block;
 import org.qortal.controller.BlockMinter;
+import org.qortal.crosschain.AcctMode;
+import org.qortal.crosschain.LitecoinACCTv3;
+import org.qortal.data.at.ATData;
 import org.qortal.data.at.ATStateData;
 import org.qortal.data.block.BlockData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.transaction.BaseTransactionData;
+import org.qortal.data.transaction.DeployAtTransactionData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.group.Group;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryManager;
 import org.qortal.test.common.AtUtils;
+import org.qortal.test.common.BlockUtils;
 import org.qortal.test.common.Common;
+import org.qortal.test.common.TransactionUtils;
+import org.qortal.transaction.DeployAtTransaction;
+import org.qortal.transaction.MessageTransaction;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -19,6 +36,13 @@ import static org.junit.Assert.*;
 
 public class PruneTests extends Common {
 
+    // Constants for test AT (an LTC ACCT)
+    public static final byte[] litecoinPublicKeyHash = HashCode.fromString("bb00bb11bb22bb33bb44bb55bb66bb77bb88bb99").asBytes();
+    public static final int tradeTimeout = 20; // blocks
+    public static final long redeemAmount = 80_40200000L;
+    public static final long fundingAmount = 123_45600000L;
+    public static final long litecoinAmount = 864200L; // 0.00864200 LTC
+
     @Before
     public void beforeTest() throws DataException {
         Common.useDefaultSettings();
@@ -62,23 +86,32 @@ public class PruneTests extends Common {
             repository.getBlockRepository().setBlockPruneHeight(6);
 
             // Prune AT states for blocks 2-5
+            repository.getATRepository().rebuildLatestAtStates(5);
+            repository.saveChanges();
             int numATStatesPruned = repository.getATRepository().pruneAtStates(0, 5);
-            assertEquals(4, numATStatesPruned);
+            assertEquals(3, numATStatesPruned);
             repository.getATRepository().setAtPruneHeight(6);
 
-            // Make sure that blocks 2-5 are now missing block data and AT states data
-            for (Integer i=2; i <= 5; i++) {
+            // Make sure that blocks 2-4 are now missing block data and AT states data
+            for (Integer i=2; i <= 4; i++) {
                 BlockData blockData = repository.getBlockRepository().fromHeight(i);
                 assertNull(blockData);
                 List<ATStateData> atStatesDataList = repository.getATRepository().getBlockATStatesAtHeight(i);
                 assertTrue(atStatesDataList.isEmpty());
             }
 
-            // ... but blocks 6-10 have block data and full AT states data
+            // Block 5 should have full AT states data even though it was pruned.
+            // This is because we identified that as the "latest" AT state in that block range
+            BlockData blockData = repository.getBlockRepository().fromHeight(5);
+            assertNull(blockData);
+            List<ATStateData> atStatesDataList = repository.getATRepository().getBlockATStatesAtHeight(5);
+            assertEquals(1, atStatesDataList.size());
+
+            // Blocks 6-10 have block data and full AT states data
             for (Integer i=6; i <= 10; i++) {
-                BlockData blockData = repository.getBlockRepository().fromHeight(i);
+                blockData = repository.getBlockRepository().fromHeight(i);
                 assertNotNull(blockData.getSignature());
-                List<ATStateData> atStatesDataList = repository.getATRepository().getBlockATStatesAtHeight(i);
+                atStatesDataList = repository.getATRepository().getBlockATStatesAtHeight(i);
                 assertNotNull(atStatesDataList);
                 assertFalse(atStatesDataList.isEmpty());
                 ATStateData atStatesData = repository.getATRepository().getATStateAtHeight(atStatesDataList.get(0).getATAddress(), i);
@@ -88,4 +121,102 @@ public class PruneTests extends Common {
         }
     }
 
+    @Test
+    public void testPruneSleepingAt() throws DataException {
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            PrivateKeyAccount deployer = Common.getTestAccount(repository, "chloe");
+            PrivateKeyAccount tradeAccount = Common.getTestAccount(repository, "alice");
+
+            DeployAtTransaction deployAtTransaction = doDeploy(repository, deployer, tradeAccount.getAddress());
+            Account at = deployAtTransaction.getATAccount();
+            String atAddress = at.getAddress();
+
+            // Mint enough blocks to take the original DEPLOY_AT past the prune threshold (in this case 20)
+            Block block = BlockUtils.mintBlocks(repository, 25);
+
+            // Send creator's address to AT, instead of typical partner's address
+            byte[] messageData = LitecoinACCTv3.getInstance().buildCancelMessage(deployer.getAddress());
+            long txTimestamp = block.getBlockData().getTimestamp();
+            MessageTransaction messageTransaction = sendMessage(repository, deployer, messageData, atAddress, txTimestamp);
+
+            // AT should process 'cancel' message in next block
+            BlockUtils.mintBlock(repository);
+
+            // Prune AT states up to block 20
+            repository.getATRepository().rebuildLatestAtStates(20);
+            repository.saveChanges();
+            int numATStatesPruned = repository.getATRepository().pruneAtStates(0, 20);
+            assertEquals(1, numATStatesPruned); // deleted state at heights 2, but state at height 3 remains
+
+            // Check AT is finished
+            ATData atData = repository.getATRepository().fromATAddress(atAddress);
+            assertTrue(atData.getIsFinished());
+
+            // AT should be in CANCELLED mode
+            CrossChainTradeData tradeData = LitecoinACCTv3.getInstance().populateTradeData(repository, atData);
+            assertEquals(AcctMode.CANCELLED, tradeData.mode);
+
+            // Test orphaning - should be possible because the previous AT state at height 3 is still available
+            BlockUtils.orphanLastBlock(repository);
+        }
+    }
+
+
+    // Helper methods for AT testing
+    private DeployAtTransaction doDeploy(Repository repository, PrivateKeyAccount deployer, String tradeAddress) throws DataException {
+        byte[] creationBytes = LitecoinACCTv3.buildQortalAT(tradeAddress, litecoinPublicKeyHash, redeemAmount, litecoinAmount, tradeTimeout);
+
+        long txTimestamp = System.currentTimeMillis();
+        byte[] lastReference = deployer.getLastReference();
+
+        if (lastReference == null) {
+            System.err.println(String.format("Qortal account %s has no last reference", deployer.getAddress()));
+            System.exit(2);
+        }
+
+        Long fee = null;
+        String name = "QORT-LTC cross-chain trade";
+        String description = String.format("Qortal-Litecoin cross-chain trade");
+        String atType = "ACCT";
+        String tags = "QORT-LTC ACCT";
+
+        BaseTransactionData baseTransactionData = new BaseTransactionData(txTimestamp, Group.NO_GROUP, lastReference, deployer.getPublicKey(), fee, null);
+        TransactionData deployAtTransactionData = new DeployAtTransactionData(baseTransactionData, name, description, atType, tags, creationBytes, fundingAmount, Asset.QORT);
+
+        DeployAtTransaction deployAtTransaction = new DeployAtTransaction(repository, deployAtTransactionData);
+
+        fee = deployAtTransaction.calcRecommendedFee();
+        deployAtTransactionData.setFee(fee);
+
+        TransactionUtils.signAndMint(repository, deployAtTransactionData, deployer);
+
+        return deployAtTransaction;
+    }
+
+    private MessageTransaction sendMessage(Repository repository, PrivateKeyAccount sender, byte[] data, String recipient, long txTimestamp) throws DataException {
+        byte[] lastReference = sender.getLastReference();
+
+        if (lastReference == null) {
+            System.err.println(String.format("Qortal account %s has no last reference", sender.getAddress()));
+            System.exit(2);
+        }
+
+        Long fee = null;
+        int version = 4;
+        int nonce = 0;
+        long amount = 0;
+        Long assetId = null; // because amount is zero
+
+        BaseTransactionData baseTransactionData = new BaseTransactionData(txTimestamp, Group.NO_GROUP, lastReference, sender.getPublicKey(), fee, null);
+        TransactionData messageTransactionData = new MessageTransactionData(baseTransactionData, version, nonce, recipient, amount, assetId, data, false, false);
+
+        MessageTransaction messageTransaction = new MessageTransaction(repository, messageTransactionData);
+
+        fee = messageTransaction.calcRecommendedFee();
+        messageTransactionData.setFee(fee);
+
+        TransactionUtils.signAndMint(repository, messageTransactionData, sender);
+
+        return messageTransaction;
+    }
 }

src/test/java/org/qortal/test/SelfSponsorshipAlgoV1Tests.java

@@ -50,8 +50,8 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			PrivateKeyAccount bobAccount = Common.getTestAccount(repository, "bob");
 
 			// Bob self sponsors 10 accounts
-			List<PrivateKeyAccount> bobSponsees = generateSponsorshipRewardShares(repository, bobAccount, 10);
-			List<PrivateKeyAccount> bobSponseesOnlineAccounts = toRewardShares(repository, bobAccount, bobSponsees);
+			List<PrivateKeyAccount> bobSponsees = AccountUtils.generateSponsorshipRewardShares(repository, bobAccount, 10);
+			List<PrivateKeyAccount> bobSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, bobAccount, bobSponsees);
 			onlineAccounts.addAll(bobSponseesOnlineAccounts);
 
 			// Mint blocks
@@ -73,7 +73,7 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 				assertTrue(new Account(repository, bobSponsee.getAddress()).getLevel() > 0);
 
 			// Generate self shares so the sponsees can start minting
-			List<PrivateKeyAccount> bobSponseeSelfShares = generateSelfShares(repository, bobSponsees);
+			List<PrivateKeyAccount> bobSponseeSelfShares = AccountUtils.generateSelfShares(repository, bobSponsees);
 			onlineAccounts.addAll(bobSponseeSelfShares);
 
 			// Mint blocks
@@ -139,18 +139,18 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			PrivateKeyAccount dilbertAccount = Common.getTestAccount(repository, "dilbert");
 
 			// Bob sponsors 10 accounts
-			List<PrivateKeyAccount> bobSponsees = generateSponsorshipRewardShares(repository, bobAccount, 10);
-			List<PrivateKeyAccount> bobSponseesOnlineAccounts = toRewardShares(repository, bobAccount, bobSponsees);
+			List<PrivateKeyAccount> bobSponsees = AccountUtils.generateSponsorshipRewardShares(repository, bobAccount, 10);
+			List<PrivateKeyAccount> bobSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, bobAccount, bobSponsees);
 			onlineAccounts.addAll(bobSponseesOnlineAccounts);
 
 			// Chloe sponsors 10 accounts
-			List<PrivateKeyAccount> chloeSponsees = generateSponsorshipRewardShares(repository, chloeAccount, 10);
-			List<PrivateKeyAccount> chloeSponseesOnlineAccounts = toRewardShares(repository, chloeAccount, chloeSponsees);
+			List<PrivateKeyAccount> chloeSponsees = AccountUtils.generateSponsorshipRewardShares(repository, chloeAccount, 10);
+			List<PrivateKeyAccount> chloeSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, chloeAccount, chloeSponsees);
 			onlineAccounts.addAll(chloeSponseesOnlineAccounts);
 
 			// Dilbert sponsors 5 accounts
-			List<PrivateKeyAccount> dilbertSponsees = generateSponsorshipRewardShares(repository, dilbertAccount, 5);
-			List<PrivateKeyAccount> dilbertSponseesOnlineAccounts = toRewardShares(repository, dilbertAccount, dilbertSponsees);
+			List<PrivateKeyAccount> dilbertSponsees = AccountUtils.generateSponsorshipRewardShares(repository, dilbertAccount, 5);
+			List<PrivateKeyAccount> dilbertSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, dilbertAccount, dilbertSponsees);
 			onlineAccounts.addAll(dilbertSponseesOnlineAccounts);
 
 			// Mint blocks
@@ -172,7 +172,7 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 				assertTrue(new Account(repository, bobSponsee.getAddress()).getLevel() > 0);
 
 			// Generate self shares so the sponsees can start minting
-			List<PrivateKeyAccount> bobSponseeSelfShares = generateSelfShares(repository, bobSponsees);
+			List<PrivateKeyAccount> bobSponseeSelfShares = AccountUtils.generateSelfShares(repository, bobSponsees);
 			onlineAccounts.addAll(bobSponseeSelfShares);
 
 			// Mint blocks
@@ -270,20 +270,20 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			PrivateKeyAccount dilbertAccount = Common.getTestAccount(repository, "dilbert");
 
 			// Bob sponsors 10 accounts
-			List<PrivateKeyAccount> bobSponsees = generateSponsorshipRewardShares(repository, bobAccount, 10);
-			List<PrivateKeyAccount> bobSponseesOnlineAccounts = toRewardShares(repository, bobAccount, bobSponsees);
+			List<PrivateKeyAccount> bobSponsees = AccountUtils.generateSponsorshipRewardShares(repository, bobAccount, 10);
+			List<PrivateKeyAccount> bobSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, bobAccount, bobSponsees);
 			onlineAccountsAliceSigner.addAll(bobSponseesOnlineAccounts);
 			onlineAccountsBobSigner.addAll(bobSponseesOnlineAccounts);
 
 			// Chloe sponsors 10 accounts
-			List<PrivateKeyAccount> chloeSponsees = generateSponsorshipRewardShares(repository, chloeAccount, 10);
-			List<PrivateKeyAccount> chloeSponseesOnlineAccounts = toRewardShares(repository, chloeAccount, chloeSponsees);
+			List<PrivateKeyAccount> chloeSponsees = AccountUtils.generateSponsorshipRewardShares(repository, chloeAccount, 10);
+			List<PrivateKeyAccount> chloeSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, chloeAccount, chloeSponsees);
 			onlineAccountsAliceSigner.addAll(chloeSponseesOnlineAccounts);
 			onlineAccountsBobSigner.addAll(chloeSponseesOnlineAccounts);
 
 			// Dilbert sponsors 5 accounts
-			List<PrivateKeyAccount> dilbertSponsees = generateSponsorshipRewardShares(repository, dilbertAccount, 5);
-			List<PrivateKeyAccount> dilbertSponseesOnlineAccounts = toRewardShares(repository, dilbertAccount, dilbertSponsees);
+			List<PrivateKeyAccount> dilbertSponsees = AccountUtils.generateSponsorshipRewardShares(repository, dilbertAccount, 5);
+			List<PrivateKeyAccount> dilbertSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, dilbertAccount, dilbertSponsees);
 			onlineAccountsAliceSigner.addAll(dilbertSponseesOnlineAccounts);
 			onlineAccountsBobSigner.addAll(dilbertSponseesOnlineAccounts);
 
@@ -306,7 +306,7 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 				assertTrue(new Account(repository, bobSponsee.getAddress()).getLevel() > 0);
 
 			// Generate self shares so the sponsees can start minting
-			List<PrivateKeyAccount> bobSponseeSelfShares = generateSelfShares(repository, bobSponsees);
+			List<PrivateKeyAccount> bobSponseeSelfShares = AccountUtils.generateSelfShares(repository, bobSponsees);
 			onlineAccountsAliceSigner.addAll(bobSponseeSelfShares);
 			onlineAccountsBobSigner.addAll(bobSponseeSelfShares);
 
@@ -382,14 +382,14 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			PrivateKeyAccount bobAccount = Common.getTestAccount(repository, "bob");
 
 			// Alice sponsors 10 accounts
-			List<PrivateKeyAccount> aliceSponsees = generateSponsorshipRewardShares(repository, aliceAccount, 10);
-			List<PrivateKeyAccount> aliceSponseesOnlineAccounts = toRewardShares(repository, aliceAccount, aliceSponsees);
+			List<PrivateKeyAccount> aliceSponsees = AccountUtils.generateSponsorshipRewardShares(repository, aliceAccount, 10);
+			List<PrivateKeyAccount> aliceSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, aliceAccount, aliceSponsees);
 			onlineAccountsAliceSigner.addAll(aliceSponseesOnlineAccounts);
 			onlineAccountsBobSigner.addAll(aliceSponseesOnlineAccounts);
 
 			// Bob sponsors 9 accounts
-			List<PrivateKeyAccount> bobSponsees = generateSponsorshipRewardShares(repository, bobAccount, 9);
-			List<PrivateKeyAccount> bobSponseesOnlineAccounts = toRewardShares(repository, bobAccount, bobSponsees);
+			List<PrivateKeyAccount> bobSponsees = AccountUtils.generateSponsorshipRewardShares(repository, bobAccount, 9);
+			List<PrivateKeyAccount> bobSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, bobAccount, bobSponsees);
 			onlineAccountsAliceSigner.addAll(bobSponseesOnlineAccounts);
 			onlineAccountsBobSigner.addAll(bobSponseesOnlineAccounts);
 
@@ -412,7 +412,7 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 				assertTrue(new Account(repository, aliceSponsee.getAddress()).getLevel() > 0);
 
 			// Generate self shares so the sponsees can start minting
-			List<PrivateKeyAccount> aliceSponseeSelfShares = generateSelfShares(repository, aliceSponsees);
+			List<PrivateKeyAccount> aliceSponseeSelfShares = AccountUtils.generateSelfShares(repository, aliceSponsees);
 			onlineAccountsAliceSigner.addAll(aliceSponseeSelfShares);
 			onlineAccountsBobSigner.addAll(aliceSponseeSelfShares);
 
@@ -483,18 +483,18 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			PrivateKeyAccount dilbertAccount = Common.getTestAccount(repository, "dilbert");
 
 			// Bob sponsors 10 accounts
-			List<PrivateKeyAccount> bobSponsees = generateSponsorshipRewardShares(repository, bobAccount, 10);
-			List<PrivateKeyAccount> bobSponseesOnlineAccounts = toRewardShares(repository, bobAccount, bobSponsees);
+			List<PrivateKeyAccount> bobSponsees = AccountUtils.generateSponsorshipRewardShares(repository, bobAccount, 10);
+			List<PrivateKeyAccount> bobSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, bobAccount, bobSponsees);
 			onlineAccounts.addAll(bobSponseesOnlineAccounts);
 
 			// Chloe sponsors 10 accounts
-			List<PrivateKeyAccount> chloeSponsees = generateSponsorshipRewardShares(repository, chloeAccount, 10);
-			List<PrivateKeyAccount> chloeSponseesOnlineAccounts = toRewardShares(repository, chloeAccount, chloeSponsees);
+			List<PrivateKeyAccount> chloeSponsees = AccountUtils.generateSponsorshipRewardShares(repository, chloeAccount, 10);
+			List<PrivateKeyAccount> chloeSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, chloeAccount, chloeSponsees);
 			onlineAccounts.addAll(chloeSponseesOnlineAccounts);
 
 			// Dilbert sponsors 5 accounts
-			List<PrivateKeyAccount> dilbertSponsees = generateSponsorshipRewardShares(repository, dilbertAccount, 5);
-			List<PrivateKeyAccount> dilbertSponseesOnlineAccounts = toRewardShares(repository, dilbertAccount, dilbertSponsees);
+			List<PrivateKeyAccount> dilbertSponsees = AccountUtils.generateSponsorshipRewardShares(repository, dilbertAccount, 5);
+			List<PrivateKeyAccount> dilbertSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, dilbertAccount, dilbertSponsees);
 			onlineAccounts.addAll(dilbertSponseesOnlineAccounts);
 
 			// Mint blocks
@@ -516,7 +516,7 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 				assertTrue(new Account(repository, bobSponsee.getAddress()).getLevel() > 0);
 
 			// Generate self shares so the sponsees can start minting
-			List<PrivateKeyAccount> bobSponseeSelfShares = generateSelfShares(repository, bobSponsees);
+			List<PrivateKeyAccount> bobSponseeSelfShares = AccountUtils.generateSelfShares(repository, bobSponsees);
 			onlineAccounts.addAll(bobSponseeSelfShares);
 
 			// Mint blocks
@@ -597,14 +597,14 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			PrivateKeyAccount bobAccount = Common.getTestAccount(repository, "bob");
 
 			// Alice sponsors 10 accounts
-			List<PrivateKeyAccount> aliceSponsees = generateSponsorshipRewardShares(repository, aliceAccount, 10);
-			List<PrivateKeyAccount> aliceSponseesOnlineAccounts = toRewardShares(repository, aliceAccount, aliceSponsees);
+			List<PrivateKeyAccount> aliceSponsees = AccountUtils.generateSponsorshipRewardShares(repository, aliceAccount, 10);
+			List<PrivateKeyAccount> aliceSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, aliceAccount, aliceSponsees);
 			onlineAccounts.addAll(aliceSponseesOnlineAccounts);
 			onlineAccounts.addAll(aliceSponseesOnlineAccounts);
 
 			// Bob sponsors 9 accounts
-			List<PrivateKeyAccount> bobSponsees = generateSponsorshipRewardShares(repository, bobAccount, 9);
-			List<PrivateKeyAccount> bobSponseesOnlineAccounts = toRewardShares(repository, bobAccount, bobSponsees);
+			List<PrivateKeyAccount> bobSponsees = AccountUtils.generateSponsorshipRewardShares(repository, bobAccount, 9);
+			List<PrivateKeyAccount> bobSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, bobAccount, bobSponsees);
 			onlineAccounts.addAll(bobSponseesOnlineAccounts);
 			onlineAccounts.addAll(bobSponseesOnlineAccounts);
 
@@ -627,7 +627,7 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 				assertTrue(new Account(repository, aliceSponsee.getAddress()).getLevel() > 0);
 
 			// Generate self shares so the sponsees can start minting
-			List<PrivateKeyAccount> aliceSponseeSelfShares = generateSelfShares(repository, aliceSponsees);
+			List<PrivateKeyAccount> aliceSponseeSelfShares = AccountUtils.generateSelfShares(repository, aliceSponsees);
 			onlineAccounts.addAll(aliceSponseeSelfShares);
 
 			// Mint blocks (Bob is the signer)
@@ -706,13 +706,13 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			PrivateKeyAccount chloeAccount = Common.getTestAccount(repository, "chloe");
 
 			// Bob sponsors 10 accounts
-			List<PrivateKeyAccount> bobSponsees = generateSponsorshipRewardShares(repository, bobAccount, 10);
-			List<PrivateKeyAccount> bobSponseesOnlineAccounts = toRewardShares(repository, bobAccount, bobSponsees);
+			List<PrivateKeyAccount> bobSponsees = AccountUtils.generateSponsorshipRewardShares(repository, bobAccount, 10);
+			List<PrivateKeyAccount> bobSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, bobAccount, bobSponsees);
 			onlineAccounts.addAll(bobSponseesOnlineAccounts);
 
 			// Chloe sponsors 10 accounts
-			List<PrivateKeyAccount> chloeSponsees = generateSponsorshipRewardShares(repository, chloeAccount, 10);
-			List<PrivateKeyAccount> chloeSponseesOnlineAccounts = toRewardShares(repository, chloeAccount, chloeSponsees);
+			List<PrivateKeyAccount> chloeSponsees = AccountUtils.generateSponsorshipRewardShares(repository, chloeAccount, 10);
+			List<PrivateKeyAccount> chloeSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, chloeAccount, chloeSponsees);
 			onlineAccounts.addAll(chloeSponseesOnlineAccounts);
 
 			// Mint blocks
@@ -728,7 +728,7 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 				block = BlockMinter.mintTestingBlock(repository, onlineAccounts.toArray(new PrivateKeyAccount[0]));
 
 			// Generate self shares so the sponsees can start minting
-			List<PrivateKeyAccount> bobSponseeSelfShares = generateSelfShares(repository, bobSponsees);
+			List<PrivateKeyAccount> bobSponseeSelfShares = AccountUtils.generateSelfShares(repository, bobSponsees);
 			onlineAccounts.addAll(bobSponseeSelfShares);
 
 			// Mint blocks
@@ -744,22 +744,22 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			assertEquals(19, (int) block.getBlockData().getHeight());
 
 			// Bob creates a valid reward share transaction
-			assertEquals(Transaction.ValidationResult.OK, createRandomRewardShare(repository, bobAccount));
+			assertEquals(Transaction.ValidationResult.OK, AccountUtils.createRandomRewardShare(repository, bobAccount));
 
 			// Mint a block, so the algo runs
 			block = BlockMinter.mintTestingBlock(repository, onlineAccounts.toArray(new PrivateKeyAccount[0]));
 
 			// Bob can no longer create a reward share transaction
-			assertEquals(Transaction.ValidationResult.ACCOUNT_CANNOT_REWARD_SHARE, createRandomRewardShare(repository, bobAccount));
+			assertEquals(Transaction.ValidationResult.ACCOUNT_CANNOT_REWARD_SHARE, AccountUtils.createRandomRewardShare(repository, bobAccount));
 
 			// ... but Chloe still can
-			assertEquals(Transaction.ValidationResult.OK, createRandomRewardShare(repository, chloeAccount));
+			assertEquals(Transaction.ValidationResult.OK, AccountUtils.createRandomRewardShare(repository, chloeAccount));
 
 			// Orphan last block
 			BlockUtils.orphanLastBlock(repository);
 
 			// Bob creates another valid reward share transaction
-			assertEquals(Transaction.ValidationResult.OK, createRandomRewardShare(repository, bobAccount));
+			assertEquals(Transaction.ValidationResult.OK, AccountUtils.createRandomRewardShare(repository, bobAccount));
 
 			// Run orphan check - this can't be in afterTest() because some tests access the live db
 			Common.orphanCheck();
@@ -780,13 +780,13 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			PrivateKeyAccount bobAccount = Common.getTestAccount(repository, "bob");
 
 			// Alice sponsors 10 accounts
-			List<PrivateKeyAccount> aliceSponsees = generateSponsorshipRewardShares(repository, aliceAccount, 10);
-			List<PrivateKeyAccount> aliceSponseesOnlineAccounts = toRewardShares(repository, aliceAccount, aliceSponsees);
+			List<PrivateKeyAccount> aliceSponsees = AccountUtils.generateSponsorshipRewardShares(repository, aliceAccount, 10);
+			List<PrivateKeyAccount> aliceSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, aliceAccount, aliceSponsees);
 			onlineAccounts.addAll(aliceSponseesOnlineAccounts);
 
 			// Bob sponsors 10 accounts
-			List<PrivateKeyAccount> bobSponsees = generateSponsorshipRewardShares(repository, bobAccount, 10);
-			List<PrivateKeyAccount> bobSponseesOnlineAccounts = toRewardShares(repository, bobAccount, bobSponsees);
+			List<PrivateKeyAccount> bobSponsees = AccountUtils.generateSponsorshipRewardShares(repository, bobAccount, 10);
+			List<PrivateKeyAccount> bobSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, bobAccount, bobSponsees);
 			onlineAccounts.addAll(bobSponseesOnlineAccounts);
 
 			// Mint blocks
@@ -802,7 +802,7 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 				block = BlockMinter.mintTestingBlock(repository, onlineAccounts.toArray(new PrivateKeyAccount[0]));
 
 			// Generate self shares so the sponsees can start minting
-			List<PrivateKeyAccount> aliceSponseeSelfShares = generateSelfShares(repository, aliceSponsees);
+			List<PrivateKeyAccount> aliceSponseeSelfShares = AccountUtils.generateSelfShares(repository, aliceSponsees);
 			onlineAccounts.addAll(aliceSponseeSelfShares);
 
 			// Mint blocks
@@ -818,7 +818,7 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			assertEquals(19, (int) block.getBlockData().getHeight());
 
 			// Alice creates a valid reward share transaction
-			assertEquals(Transaction.ValidationResult.OK, createRandomRewardShare(repository, aliceAccount));
+			assertEquals(Transaction.ValidationResult.OK, AccountUtils.createRandomRewardShare(repository, aliceAccount));
 
 			// Mint a block, so the algo runs
 			block = BlockMinter.mintTestingBlock(repository, onlineAccounts.toArray(new PrivateKeyAccount[0]));
@@ -830,16 +830,16 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			assertEquals(0, (int) new Account(repository, aliceAccount.getAddress()).getLevel());
 
 			// Alice can no longer create a reward share transaction
-			assertEquals(Transaction.ValidationResult.ACCOUNT_CANNOT_REWARD_SHARE, createRandomRewardShare(repository, aliceAccount));
+			assertEquals(Transaction.ValidationResult.ACCOUNT_CANNOT_REWARD_SHARE, AccountUtils.createRandomRewardShare(repository, aliceAccount));
 
 			// ... but Bob still can
-			assertEquals(Transaction.ValidationResult.OK, createRandomRewardShare(repository, bobAccount));
+			assertEquals(Transaction.ValidationResult.OK, AccountUtils.createRandomRewardShare(repository, bobAccount));
 
 			// Orphan last block
 			BlockUtils.orphanLastBlock(repository);
 
 			// Alice creates another valid reward share transaction
-			assertEquals(Transaction.ValidationResult.OK, createRandomRewardShare(repository, aliceAccount));
+			assertEquals(Transaction.ValidationResult.OK, AccountUtils.createRandomRewardShare(repository, aliceAccount));
 
 			// Run orphan check - this can't be in afterTest() because some tests access the live db
 			Common.orphanCheck();
@@ -867,8 +867,8 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			PrivateKeyAccount dilbertAccount = Common.getTestAccount(repository, "dilbert");
 
 			// Dilbert sponsors 10 accounts
-			List<PrivateKeyAccount> dilbertSponsees = generateSponsorshipRewardShares(repository, dilbertAccount, 10);
-			List<PrivateKeyAccount> dilbertSponseesOnlineAccounts = toRewardShares(repository, dilbertAccount, dilbertSponsees);
+			List<PrivateKeyAccount> dilbertSponsees = AccountUtils.generateSponsorshipRewardShares(repository, dilbertAccount, 10);
+			List<PrivateKeyAccount> dilbertSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, dilbertAccount, dilbertSponsees);
 			onlineAccounts.addAll(dilbertSponseesOnlineAccounts);
 
 			// Mint blocks
@@ -921,8 +921,8 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			PrivateKeyAccount dilbertAccount = Common.getTestAccount(repository, "dilbert");
 
 			// Dilbert sponsors 10 accounts
-			List<PrivateKeyAccount> dilbertSponsees = generateSponsorshipRewardShares(repository, dilbertAccount, 10);
-			List<PrivateKeyAccount> dilbertSponseesOnlineAccounts = toRewardShares(repository, dilbertAccount, dilbertSponsees);
+			List<PrivateKeyAccount> dilbertSponsees = AccountUtils.generateSponsorshipRewardShares(repository, dilbertAccount, 10);
+			List<PrivateKeyAccount> dilbertSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, dilbertAccount, dilbertSponsees);
 			onlineAccounts.addAll(dilbertSponseesOnlineAccounts);
 
 			// Mint blocks
@@ -935,7 +935,7 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 				block = BlockMinter.mintTestingBlock(repository, onlineAccounts.toArray(new PrivateKeyAccount[0]));
 
 			// Generate self shares so the sponsees can start minting
-			List<PrivateKeyAccount> dilbertSponseeSelfShares = generateSelfShares(repository, dilbertSponsees);
+			List<PrivateKeyAccount> dilbertSponseeSelfShares = AccountUtils.generateSelfShares(repository, dilbertSponsees);
 			onlineAccounts.addAll(dilbertSponseeSelfShares);
 
 			// Mint blocks
@@ -985,8 +985,8 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			PrivateKeyAccount dilbertAccount = Common.getTestAccount(repository, "dilbert");
 
 			// Bob sponsors 10 accounts
-			List<PrivateKeyAccount> bobSponsees = generateSponsorshipRewardShares(repository, bobAccount, 10);
-			List<PrivateKeyAccount> bobSponseesOnlineAccounts = toRewardShares(repository, bobAccount, bobSponsees);
+			List<PrivateKeyAccount> bobSponsees = AccountUtils.generateSponsorshipRewardShares(repository, bobAccount, 10);
+			List<PrivateKeyAccount> bobSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, bobAccount, bobSponsees);
 			onlineAccounts.addAll(bobSponseesOnlineAccounts);
 
 			// Chloe sponsors THE SAME 10 accounts
@@ -996,12 +996,12 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 				TransactionUtils.signAndImportValid(repository, transactionData, chloeAccount);
 			}
 			List<PrivateKeyAccount> chloeSponsees = new ArrayList<>(bobSponsees);
-			List<PrivateKeyAccount> chloeSponseesOnlineAccounts = toRewardShares(repository, chloeAccount, chloeSponsees);
+			List<PrivateKeyAccount> chloeSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, chloeAccount, chloeSponsees);
 			onlineAccounts.addAll(chloeSponseesOnlineAccounts);
 
 			// Dilbert sponsors 5 accounts
-			List<PrivateKeyAccount> dilbertSponsees = generateSponsorshipRewardShares(repository, dilbertAccount, 5);
-			List<PrivateKeyAccount> dilbertSponseesOnlineAccounts = toRewardShares(repository, dilbertAccount, dilbertSponsees);
+			List<PrivateKeyAccount> dilbertSponsees = AccountUtils.generateSponsorshipRewardShares(repository, dilbertAccount, 5);
+			List<PrivateKeyAccount> dilbertSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, dilbertAccount, dilbertSponsees);
 			onlineAccounts.addAll(dilbertSponseesOnlineAccounts);
 
 			// Mint blocks
@@ -1023,7 +1023,7 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 				assertTrue(new Account(repository, bobSponsee.getAddress()).getLevel() > 0);
 
 			// Generate self shares so the sponsees can start minting
-			List<PrivateKeyAccount> bobSponseeSelfShares = generateSelfShares(repository, bobSponsees);
+			List<PrivateKeyAccount> bobSponseeSelfShares = AccountUtils.generateSelfShares(repository, bobSponsees);
 			onlineAccounts.addAll(bobSponseeSelfShares);
 
 			// Mint blocks
@@ -1108,8 +1108,8 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			PrivateKeyAccount bobAccount = Common.getTestAccount(repository, "bob");
 
 			// Bob sponsors 10 accounts
-			List<PrivateKeyAccount> bobSponsees = generateSponsorshipRewardShares(repository, bobAccount, 10);
-			List<PrivateKeyAccount> bobSponseesOnlineAccounts = toRewardShares(repository, bobAccount, bobSponsees);
+			List<PrivateKeyAccount> bobSponsees = AccountUtils.generateSponsorshipRewardShares(repository, bobAccount, 10);
+			List<PrivateKeyAccount> bobSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, bobAccount, bobSponsees);
 			onlineAccounts.addAll(bobSponseesOnlineAccounts);
 
 			// Mint blocks
@@ -1128,7 +1128,7 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 				assertTrue(new Account(repository, bobSponsee.getAddress()).getLevel() > 0);
 
 			// Generate self shares so the sponsees can start minting
-			List<PrivateKeyAccount> bobSponseeSelfShares = generateSelfShares(repository, bobSponsees);
+			List<PrivateKeyAccount> bobSponseeSelfShares = AccountUtils.generateSelfShares(repository, bobSponsees);
 			onlineAccounts.addAll(bobSponseeSelfShares);
 
 			// Mint blocks
@@ -1220,8 +1220,8 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			PrivateKeyAccount bobAccount = Common.getTestAccount(repository, "bob");
 
 			// Bob sponsors 10 accounts
-			List<PrivateKeyAccount> bobSponsees = generateSponsorshipRewardShares(repository, bobAccount, 10);
-			List<PrivateKeyAccount> bobSponseesOnlineAccounts = toRewardShares(repository, bobAccount, bobSponsees);
+			List<PrivateKeyAccount> bobSponsees = AccountUtils.generateSponsorshipRewardShares(repository, bobAccount, 10);
+			List<PrivateKeyAccount> bobSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, bobAccount, bobSponsees);
 			onlineAccounts.addAll(bobSponseesOnlineAccounts);
 
 			// Mint blocks
@@ -1240,7 +1240,7 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 				assertTrue(new Account(repository, bobSponsee.getAddress()).getLevel() > 0);
 
 			// Generate self shares so the sponsees can start minting
-			List<PrivateKeyAccount> bobSponseeSelfShares = generateSelfShares(repository, bobSponsees);
+			List<PrivateKeyAccount> bobSponseeSelfShares = AccountUtils.generateSelfShares(repository, bobSponsees);
 			onlineAccounts.addAll(bobSponseeSelfShares);
 
 			// Mint blocks
@@ -1316,8 +1316,8 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			PrivateKeyAccount bobAccount = Common.getTestAccount(repository, "bob");
 
 			// Bob sponsors 10 accounts
-			List<PrivateKeyAccount> bobSponsees = generateSponsorshipRewardShares(repository, bobAccount, 10);
-			List<PrivateKeyAccount> bobSponseesOnlineAccounts = toRewardShares(repository, bobAccount, bobSponsees);
+			List<PrivateKeyAccount> bobSponsees = AccountUtils.generateSponsorshipRewardShares(repository, bobAccount, 10);
+			List<PrivateKeyAccount> bobSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, bobAccount, bobSponsees);
 			onlineAccounts.addAll(bobSponseesOnlineAccounts);
 
 			// Mint blocks
@@ -1336,7 +1336,7 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 				assertTrue(new Account(repository, bobSponsee.getAddress()).getLevel() > 0);
 
 			// Generate self shares so the sponsees can start minting
-			List<PrivateKeyAccount> bobSponseeSelfShares = generateSelfShares(repository, bobSponsees);
+			List<PrivateKeyAccount> bobSponseeSelfShares = AccountUtils.generateSelfShares(repository, bobSponsees);
 			onlineAccounts.addAll(bobSponseeSelfShares);
 
 			// Mint blocks
@@ -1392,8 +1392,8 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 			PrivateKeyAccount bobAccount = Common.getTestAccount(repository, "bob");
 
 			// Bob sponsors 10 accounts
-			List<PrivateKeyAccount> bobSponsees = generateSponsorshipRewardShares(repository, bobAccount, 10);
-			List<PrivateKeyAccount> bobSponseesOnlineAccounts = toRewardShares(repository, bobAccount, bobSponsees);
+			List<PrivateKeyAccount> bobSponsees = AccountUtils.generateSponsorshipRewardShares(repository, bobAccount, 10);
+			List<PrivateKeyAccount> bobSponseesOnlineAccounts = AccountUtils.toRewardShares(repository, bobAccount, bobSponsees);
 			onlineAccounts.addAll(bobSponseesOnlineAccounts);
 
 			// Mint blocks
@@ -1412,7 +1412,7 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 				assertTrue(new Account(repository, bobSponsee.getAddress()).getLevel() > 0);
 
 			// Generate self shares so the sponsees can start minting
-			List<PrivateKeyAccount> bobSponseeSelfShares = generateSelfShares(repository, bobSponsees);
+			List<PrivateKeyAccount> bobSponseeSelfShares = AccountUtils.generateSelfShares(repository, bobSponsees);
 			onlineAccounts.addAll(bobSponseeSelfShares);
 
 			// Mint blocks
@@ -1543,61 +1543,6 @@ public class SelfSponsorshipAlgoV1Tests extends Common {
 		return new TransferPrivsTransaction(repository, transactionData);
 	}
 
-	private static List<PrivateKeyAccount> generateSponsorshipRewardShares(Repository repository, PrivateKeyAccount sponsorAccount, int accountsCount) throws DataException {
-		final int sharePercent = 0;
-		Random random = new Random();
-
-		List<PrivateKeyAccount> sponsees = new ArrayList<>();
-		for (int i = 0; i < accountsCount; i++) {
-
-			// Generate random sponsee account
-			byte[] randomPrivateKey = new byte[32];
-			random.nextBytes(randomPrivateKey);
-			PrivateKeyAccount sponseeAccount = new PrivateKeyAccount(repository, randomPrivateKey);
-			sponsees.add(sponseeAccount);
-
-			// Create reward-share
-			TransactionData transactionData = AccountUtils.createRewardShare(repository, sponsorAccount, sponseeAccount, sharePercent, fee);
-			TransactionUtils.signAndImportValid(repository, transactionData, sponsorAccount);
-		}
-
-		return sponsees;
-	}
-
-	private static Transaction.ValidationResult createRandomRewardShare(Repository repository, PrivateKeyAccount account) throws DataException {
-		// Bob attempts to create a reward share transaction
-		byte[] randomPrivateKey = new byte[32];
-		new Random().nextBytes(randomPrivateKey);
-		PrivateKeyAccount sponseeAccount = new PrivateKeyAccount(repository, randomPrivateKey);
-		TransactionData transactionData = AccountUtils.createRewardShare(repository, account, sponseeAccount, 0, fee);
-		return TransactionUtils.signAndImport(repository, transactionData, account);
-	}
-
-	private static List<PrivateKeyAccount> generateSelfShares(Repository repository, List<PrivateKeyAccount> accounts) throws DataException {
-		final int sharePercent = 0;
-
-		for (PrivateKeyAccount account : accounts) {
-			// Create reward-share
-			TransactionData transactionData = AccountUtils.createRewardShare(repository, account, account, sharePercent, 0L);
-			TransactionUtils.signAndImportValid(repository, transactionData, account);
-		}
-
-		return toRewardShares(repository, null, accounts);
-	}
-
-	private static List<PrivateKeyAccount> toRewardShares(Repository repository, PrivateKeyAccount parentAccount, List<PrivateKeyAccount> accounts) {
-		List<PrivateKeyAccount> rewardShares = new ArrayList<>();
-
-		for (PrivateKeyAccount account : accounts) {
-			PrivateKeyAccount sponsor = (parentAccount != null) ? parentAccount : account;
-			byte[] rewardSharePrivateKey = sponsor.getRewardSharePrivateKey(account.getPublicKey());
-			PrivateKeyAccount rewardShareAccount = new PrivateKeyAccount(repository, rewardSharePrivateKey);
-			rewardShares.add(rewardShareAccount);
-		}
-
-		return rewardShares;
-	}
-
 	private boolean areAllAccountsPresentInBlock(List<PrivateKeyAccount> accounts, Block block) throws DataException {
 		for (PrivateKeyAccount bobSponsee : accounts) {
 			boolean foundOnlineAccountInBlock = false;

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

@@ -175,4 +175,93 @@ public class ArbitraryServiceTests extends Common {
         assertEquals(ValidationResult.INVALID_FILE_EXTENSION, service.validate(path));
     }
 
-}
+    @Test
+    public void testValidateQChatAttachment() throws IOException {
+        // Generate some random data
+        byte[] data = new byte[1024];
+        new Random().nextBytes(data);
+
+        // Write the data to several files in a temp path
+        Path path = Files.createTempDirectory("testValidateQChatAttachment");
+        path.toFile().deleteOnExit();
+        Files.write(Paths.get(path.toString(), "document.pdf"), data, StandardOpenOption.CREATE);
+
+        Service service = Service.QCHAT_ATTACHMENT;
+        assertTrue(service.isValidationRequired());
+
+        // There is an index file in the root
+        assertEquals(ValidationResult.OK, service.validate(path));
+    }
+
+    @Test
+    public void testValidateInvalidQChatAttachmentFileExtension() throws IOException {
+        // Generate some random data
+        byte[] data = new byte[1024];
+        new Random().nextBytes(data);
+
+        // Write the data to several files in a temp path
+        Path path = Files.createTempDirectory("testValidateInvalidQChatAttachmentFileExtension");
+        path.toFile().deleteOnExit();
+        Files.write(Paths.get(path.toString(), "application.exe"), data, StandardOpenOption.CREATE);
+
+        Service service = Service.QCHAT_ATTACHMENT;
+        assertTrue(service.isValidationRequired());
+
+        // There is an index file in the root
+        assertEquals(ValidationResult.INVALID_FILE_EXTENSION, service.validate(path));
+    }
+
+    @Test
+    public void testValidateEmptyQChatAttachment() throws IOException {
+        Path path = Files.createTempDirectory("testValidateEmptyQChatAttachment");
+
+        Service service = Service.QCHAT_ATTACHMENT;
+        assertTrue(service.isValidationRequired());
+
+        // There is an index file in the root
+        assertEquals(ValidationResult.INVALID_FILE_COUNT, service.validate(path));
+    }
+
+    @Test
+    public void testValidateMultiLayerQChatAttachment() throws IOException {
+        // Generate some random data
+        byte[] data = new byte[1024];
+        new Random().nextBytes(data);
+
+        // Write the data to several files in a temp path
+        Path path = Files.createTempDirectory("testValidateMultiLayerQChatAttachment");
+        path.toFile().deleteOnExit();
+        Files.write(Paths.get(path.toString(), "file1.txt"), data, StandardOpenOption.CREATE);
+
+        Path subdirectory = Paths.get(path.toString(), "subdirectory");
+        Files.createDirectories(subdirectory);
+        Files.write(Paths.get(subdirectory.toString(), "file2.txt"), data, StandardOpenOption.CREATE);
+        Files.write(Paths.get(subdirectory.toString(), "file3.txt"), data, StandardOpenOption.CREATE);
+
+        Service service = Service.QCHAT_ATTACHMENT;
+        assertTrue(service.isValidationRequired());
+
+        // There is an index file in the root
+        assertEquals(ValidationResult.DIRECTORIES_NOT_ALLOWED, service.validate(path));
+    }
+
+    @Test
+    public void testValidateMultiFileQChatAttachment() throws IOException {
+        // Generate some random data
+        byte[] data = new byte[1024];
+        new Random().nextBytes(data);
+
+        // Write the data to several files in a temp path
+        Path path = Files.createTempDirectory("testValidateMultiFileQChatAttachment");
+        path.toFile().deleteOnExit();
+        Files.write(Paths.get(path.toString(), "file1.txt"), data, StandardOpenOption.CREATE);
+        Files.write(Paths.get(path.toString(), "file2.txt"), data, StandardOpenOption.CREATE);
+
+        Service service = Service.QCHAT_ATTACHMENT;
+        assertTrue(service.isValidationRequired());
+
+        // There is an index file in the root
+        assertEquals(ValidationResult.INVALID_FILE_COUNT, service.validate(path));
+    }
+
+}

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

@@ -2,29 +2,20 @@ package org.qortal.test.at;
 
 import static org.junit.Assert.*;
 
-import java.nio.ByteBuffer;
 import java.util.List;
 
-import org.ciyam.at.CompilationException;
 import org.ciyam.at.MachineState;
-import org.ciyam.at.OpCode;
 import org.junit.Before;
 import org.junit.Test;
 import org.qortal.account.PrivateKeyAccount;
-import org.qortal.asset.Asset;
 import org.qortal.data.at.ATData;
 import org.qortal.data.at.ATStateData;
-import org.qortal.data.transaction.BaseTransactionData;
-import org.qortal.data.transaction.DeployAtTransactionData;
-import org.qortal.data.transaction.TransactionData;
-import org.qortal.group.Group;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryManager;
 import org.qortal.test.common.AtUtils;
 import org.qortal.test.common.BlockUtils;
 import org.qortal.test.common.Common;
-import org.qortal.test.common.TransactionUtils;
 import org.qortal.transaction.DeployAtTransaction;
 
 public class AtRepositoryTests extends Common {
@@ -76,7 +67,7 @@ public class AtRepositoryTests extends Common {
 			Integer testHeight = maxHeight - 2;
 
 			// Trim AT state data
-			repository.getATRepository().rebuildLatestAtStates();
+			repository.getATRepository().rebuildLatestAtStates(maxHeight);
 			repository.getATRepository().trimAtStates(2, maxHeight, 1000);
 
 			ATStateData atStateData = repository.getATRepository().getATStateAtHeight(atAddress, testHeight);
@@ -130,7 +121,7 @@ public class AtRepositoryTests extends Common {
 			Integer testHeight = blockchainHeight;
 
 			// Trim AT state data
-			repository.getATRepository().rebuildLatestAtStates();
+			repository.getATRepository().rebuildLatestAtStates(maxHeight);
 			// COMMIT to check latest AT states persist / TEMPORARY table interaction
 			repository.saveChanges();
 
@@ -163,8 +154,8 @@ public class AtRepositoryTests extends Common {
 			int maxTrimHeight = blockchainHeight - 4;
 			Integer testHeight = maxTrimHeight + 1;
 
-			// Trim AT state data
-			repository.getATRepository().rebuildLatestAtStates();
+			// Trim AT state data (using a max height of maxTrimHeight + 1, so it is beyond the trimmed range)
+			repository.getATRepository().rebuildLatestAtStates(maxTrimHeight + 1);
 			repository.saveChanges();
 			repository.getATRepository().trimAtStates(2, maxTrimHeight, 1000);
 
@@ -333,7 +324,7 @@ public class AtRepositoryTests extends Common {
 			Integer testHeight = maxHeight - 2;
 
 			// Trim AT state data
-			repository.getATRepository().rebuildLatestAtStates();
+			repository.getATRepository().rebuildLatestAtStates(maxHeight);
 			repository.getATRepository().trimAtStates(2, maxHeight, 1000);
 
 			List<ATStateData> atStates = repository.getATRepository().getBlockATStatesAtHeight(testHeight);

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

@@ -8,7 +8,6 @@ import java.util.*;
 
 import com.google.common.primitives.Longs;
 import org.qortal.account.PrivateKeyAccount;
-import org.qortal.block.BlockChain;
 import org.qortal.crypto.Crypto;
 import org.qortal.crypto.Qortal25519Extras;
 import org.qortal.data.network.OnlineAccountData;
@@ -19,6 +18,7 @@ import org.qortal.data.transaction.TransactionData;
 import org.qortal.group.Group;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
+import org.qortal.transaction.Transaction;
 import org.qortal.transform.Transformer;
 import org.qortal.utils.Amounts;
 
@@ -86,6 +86,61 @@ public class AccountUtils {
 		return rewardSharePrivateKey;
 	}
 
+	public static List<PrivateKeyAccount> generateSponsorshipRewardShares(Repository repository, PrivateKeyAccount sponsorAccount, int accountsCount) throws DataException {
+		final int sharePercent = 0;
+		Random random = new Random();
+
+		List<PrivateKeyAccount> sponsees = new ArrayList<>();
+		for (int i = 0; i < accountsCount; i++) {
+
+			// Generate random sponsee account
+			byte[] randomPrivateKey = new byte[32];
+			random.nextBytes(randomPrivateKey);
+			PrivateKeyAccount sponseeAccount = new PrivateKeyAccount(repository, randomPrivateKey);
+			sponsees.add(sponseeAccount);
+
+			// Create reward-share
+			TransactionData transactionData = AccountUtils.createRewardShare(repository, sponsorAccount, sponseeAccount, sharePercent, fee);
+			TransactionUtils.signAndImportValid(repository, transactionData, sponsorAccount);
+		}
+
+		return sponsees;
+	}
+
+	public static Transaction.ValidationResult createRandomRewardShare(Repository repository, PrivateKeyAccount account) throws DataException {
+		// Bob attempts to create a reward share transaction
+		byte[] randomPrivateKey = new byte[32];
+		new Random().nextBytes(randomPrivateKey);
+		PrivateKeyAccount sponseeAccount = new PrivateKeyAccount(repository, randomPrivateKey);
+		TransactionData transactionData = createRewardShare(repository, account, sponseeAccount, 0, fee);
+		return TransactionUtils.signAndImport(repository, transactionData, account);
+	}
+
+	public static List<PrivateKeyAccount> generateSelfShares(Repository repository, List<PrivateKeyAccount> accounts) throws DataException {
+		final int sharePercent = 0;
+
+		for (PrivateKeyAccount account : accounts) {
+			// Create reward-share
+			TransactionData transactionData = createRewardShare(repository, account, account, sharePercent, 0L);
+			TransactionUtils.signAndImportValid(repository, transactionData, account);
+		}
+
+		return toRewardShares(repository, null, accounts);
+	}
+
+	public static List<PrivateKeyAccount> toRewardShares(Repository repository, PrivateKeyAccount parentAccount, List<PrivateKeyAccount> accounts) {
+		List<PrivateKeyAccount> rewardShares = new ArrayList<>();
+
+		for (PrivateKeyAccount account : accounts) {
+			PrivateKeyAccount sponsor = (parentAccount != null) ? parentAccount : account;
+			byte[] rewardSharePrivateKey = sponsor.getRewardSharePrivateKey(account.getPublicKey());
+			PrivateKeyAccount rewardShareAccount = new PrivateKeyAccount(repository, rewardSharePrivateKey);
+			rewardShares.add(rewardShareAccount);
+		}
+
+		return rewardShares;
+	}
+
 	public static Map<String, Map<Long, Long>> getBalances(Repository repository, long... assetIds) throws DataException {
 		Map<String, Map<Long, Long>> balances = new HashMap<>();
 

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

@@ -20,6 +20,15 @@ public class BlockUtils {
 		return BlockMinter.mintTestingBlock(repository, mintingAccount);
 	}
 
+	/** Mints multiple blocks using "alice-reward-share" test account, and returns the final block. */
+	public static Block mintBlocks(Repository repository, int count) throws DataException {
+		Block block = null;
+		for (int i=0; i<count; i++) {
+			block = BlockUtils.mintBlock(repository);
+		}
+		return block;
+	}
+
 	public static Long getNextBlockReward(Repository repository) throws DataException {
 		int currentHeight = repository.getBlockRepository().getBlockchainHeight();
 

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

@@ -120,7 +120,9 @@ public class Common {
 	}
 
 	public static void useSettingsAndDb(String settingsFilename, boolean dbInMemory) throws DataException {
-		closeRepository();
+		if (RepositoryManager.getRepositoryFactory() != null) {
+			closeRepository();
+		}
 
 		// Load/check settings, which potentially sets up blockchain config, etc.
 		LOGGER.debug(String.format("Using setting file: %s", settingsFilename));

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

@@ -0,0 +1,40 @@
+package org.qortal.test.common.transaction;
+
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.transaction.ChatTransactionData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+
+import java.util.Random;
+
+public class ChatTestTransaction extends TestTransaction {
+
+	public static TransactionData randomTransaction(Repository repository, PrivateKeyAccount account, boolean wantValid) throws DataException {
+		Random random = new Random();
+		byte[] orderId = new byte[64];
+		random.nextBytes(orderId);
+
+		String sender = Crypto.toAddress(account.getPublicKey());
+		int nonce = 1234567;
+
+		// Generate random recipient
+		byte[] randomPrivateKey = new byte[32];
+		random.nextBytes(randomPrivateKey);
+		PrivateKeyAccount recipientAccount = new PrivateKeyAccount(repository, randomPrivateKey);
+		String recipient = Crypto.toAddress(recipientAccount.getPublicKey());
+
+		byte[] chatReference = new byte[64];
+		random.nextBytes(chatReference);
+
+		byte[] data = new byte[4000];
+		random.nextBytes(data);
+
+		boolean isText = true;
+		boolean isEncrypted = true;
+
+		return new ChatTransactionData(generateBase(account), sender, nonce, recipient, chatReference, data, isText, isEncrypted);
+	}
+
+}

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

@@ -135,7 +135,8 @@ public class AdminTests extends Common {
 			assertNotSame(ValidationResult.OK, result);
 
 			// Attempt to ban Bob
-			result = groupBan(repository, alice, groupId, bob.getAddress());
+			int timeToLive = 0;
+			result = groupBan(repository, alice, groupId, bob.getAddress(), timeToLive);
 			// Should be OK
 			assertEquals(ValidationResult.OK, result);
 
@@ -158,7 +159,7 @@ public class AdminTests extends Common {
 			assertTrue(isMember(repository, bob.getAddress(), groupId));
 
 			// Attempt to ban Bob
-			result = groupBan(repository, alice, groupId, bob.getAddress());
+			result = groupBan(repository, alice, groupId, bob.getAddress(), timeToLive);
 			// Should be OK
 			assertEquals(ValidationResult.OK, result);
 
@@ -205,6 +206,144 @@ public class AdminTests extends Common {
 		}
 	}
 
+	@Test
+	public void testGroupBanMemberWithExpiry() throws DataException, InterruptedException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			PrivateKeyAccount alice = Common.getTestAccount(repository, "alice");
+			PrivateKeyAccount bob = Common.getTestAccount(repository, "bob");
+
+			// Create group
+			int groupId = createGroup(repository, alice, "open-group", true);
+
+			// 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 for 2 seconds
+			int timeToLive = 2;
+			result = groupBan(repository, alice, groupId, bob.getAddress(), timeToLive);
+			// 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);
+
+			// Wait for 2 seconds to pass
+			Thread.sleep(2000L);
+
+			// Bob attempts to rejoin again
+			result = joinGroup(repository, bob, groupId);
+			// Should be OK, as the ban has expired
+			assertSame(ValidationResult.OK, result);
+
+			// Confirm Bob is now a member
+			assertTrue(isMember(repository, bob.getAddress(), groupId));
+
+			// Orphan last block (Bob join)
+			BlockUtils.orphanLastBlock(repository);
+
+			// Confirm Bob is not a member
+			assertFalse(isMember(repository, bob.getAddress(), groupId));
+
+			// Orphan last block (Bob ban)
+			BlockUtils.orphanLastBlock(repository);
+			// Delete unconfirmed group-ban transaction
+			TransactionUtils.deleteUnconfirmedTransactions(repository);
+
+			// 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 for 2 seconds
+			result = groupBan(repository, alice, groupId, bob.getAddress(), 2);
+			// Should be OK
+			assertEquals(ValidationResult.OK, result);
+
+			// Confirm Bob no longer a member
+			assertFalse(isMember(repository, bob.getAddress(), groupId));
+
+			// Wait for 2 seconds to pass
+			Thread.sleep(2000L);
+
+			// Cancel Bob's ban
+			result = cancelGroupBan(repository, alice, groupId, bob.getAddress());
+			// Should NOT be OK, as ban has already expired
+			assertNotSame(ValidationResult.OK, result);
+
+			// Confirm Bob still not a member
+			assertFalse(isMember(repository, bob.getAddress(), groupId));
+
+			// Bob attempts to rejoin
+			result = joinGroup(repository, bob, groupId);
+			// Should be OK, as no longer banned
+			assertSame(ValidationResult.OK, result);
+
+			// Confirm Bob is now a member
+			assertTrue(isMember(repository, bob.getAddress(), groupId));
+
+
+			// Attempt to ban Bob for 10 seconds
+			result = groupBan(repository, alice, groupId, bob.getAddress(), 10);
+			// 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, as ban still exists
+			assertNotSame(ValidationResult.OK, result);
+
+			// Cancel Bob's ban
+			result = cancelGroupBan(repository, alice, groupId, bob.getAddress());
+			// Should be OK, as ban still exists
+			assertEquals(ValidationResult.OK, result);
+
+			// Bob attempts to rejoin
+			result = joinGroup(repository, bob, groupId);
+			// Should be OK, as no longer banned
+			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()) {
@@ -226,7 +365,8 @@ public class AdminTests extends Common {
 			assertTrue(isAdmin(repository, bob.getAddress(), groupId));
 
 			// Attempt to ban Bob
-			result = groupBan(repository, alice, groupId, bob.getAddress());
+			int timeToLive = 0;
+			result = groupBan(repository, alice, groupId, bob.getAddress(), timeToLive);
 			// Should be OK
 			assertEquals(ValidationResult.OK, result);
 
@@ -272,12 +412,12 @@ public class AdminTests extends Common {
 			assertTrue(isAdmin(repository, bob.getAddress(), groupId));
 
 			// Have Alice (owner) try to ban herself!
-			result = groupBan(repository, alice, groupId, alice.getAddress());
+			result = groupBan(repository, alice, groupId, alice.getAddress(), timeToLive);
 			// Should NOT be OK
 			assertNotSame(ValidationResult.OK, result);
 
 			// Have Bob try to ban Alice (owner)
-			result = groupBan(repository, bob, groupId, alice.getAddress());
+			result = groupBan(repository, bob, groupId, alice.getAddress(), timeToLive);
 			// Should NOT be OK
 			assertNotSame(ValidationResult.OK, result);
 		}
@@ -316,8 +456,8 @@ public class AdminTests extends Common {
 		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);
+	private ValidationResult groupBan(Repository repository, PrivateKeyAccount admin, int groupId, String member, int timeToLive) throws DataException {
+		GroupBanTransactionData transactionData = new GroupBanTransactionData(TestTransaction.generateBase(admin), groupId, member, "testing", timeToLive);
 		ValidationResult result = TransactionUtils.signAndImport(repository, transactionData, admin);
 
 		if (result == ValidationResult.OK)

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

@@ -1,4 +1,4 @@
-package org.qortal.test.at;
+package org.qortal.test.serialization;
 
 import com.google.common.hash.HashCode;
 import org.junit.After;

src/test/java/org/qortal/test/serialization/ChatSerializationTests.java

@@ -0,0 +1,102 @@
+package org.qortal.test.serialization;
+
+import com.google.common.hash.HashCode;
+import org.junit.Before;
+import org.junit.Test;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.data.transaction.ChatTransactionData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.test.common.Common;
+import org.qortal.test.common.transaction.ChatTestTransaction;
+import org.qortal.transaction.Transaction;
+import org.qortal.transform.TransformationException;
+import org.qortal.transform.transaction.TransactionTransformer;
+import org.qortal.utils.Base58;
+
+import static org.junit.Assert.*;
+
+public class ChatSerializationTests {
+
+    @Before
+    public void beforeTest() throws DataException {
+        Common.useDefaultSettings();
+    }
+
+
+    @Test
+    public void testChatSerializationWithChatReference() throws DataException, TransformationException {
+        try (final Repository repository = RepositoryManager.getRepository()) {
+
+            // Build MESSAGE-type AT transaction with chatReference
+            PrivateKeyAccount signingAccount = Common.getTestAccount(repository, "alice");
+            ChatTransactionData transactionData = (ChatTransactionData) ChatTestTransaction.randomTransaction(repository, signingAccount, true);
+            Transaction transaction = Transaction.fromData(repository, transactionData);
+            transaction.sign(signingAccount);
+
+            assertNotNull(transactionData.getChatReference());
+
+            final int claimedLength = TransactionTransformer.getDataLength(transactionData);
+            byte[] serializedTransaction = TransactionTransformer.toBytes(transactionData);
+            assertEquals("Serialized CHAT transaction length differs from declared length", claimedLength, serializedTransaction.length);
+
+            TransactionData deserializedTransactionData = TransactionTransformer.fromBytes(serializedTransaction);
+            // Re-sign
+            Transaction deserializedTransaction = Transaction.fromData(repository, deserializedTransactionData);
+            deserializedTransaction.sign(signingAccount);
+            assertEquals("Deserialized CHAT transaction signature differs", Base58.encode(transactionData.getSignature()), Base58.encode(deserializedTransactionData.getSignature()));
+
+            // Re-serialize to check new length and bytes
+            final int reclaimedLength = TransactionTransformer.getDataLength(deserializedTransactionData);
+            assertEquals("Reserialized CHAT transaction declared length differs", claimedLength, reclaimedLength);
+
+            byte[] reserializedTransaction = TransactionTransformer.toBytes(deserializedTransactionData);
+            assertEquals("Reserialized CHAT transaction bytes differ", HashCode.fromBytes(serializedTransaction).toString(), HashCode.fromBytes(reserializedTransaction).toString());
+
+            // Deserialized chat reference must match initial chat reference
+            ChatTransactionData deserializedChatTransactionData = (ChatTransactionData) deserializedTransactionData;
+            assertNotNull(deserializedChatTransactionData.getChatReference());
+            assertArrayEquals(deserializedChatTransactionData.getChatReference(), transactionData.getChatReference());
+        }
+    }
+
+    @Test
+    public void testChatSerializationWithoutChatReference() throws DataException, TransformationException {
+        try (final Repository repository = RepositoryManager.getRepository()) {
+
+            // Build MESSAGE-type AT transaction without chatReference
+            PrivateKeyAccount signingAccount = Common.getTestAccount(repository, "alice");
+            ChatTransactionData transactionData = (ChatTransactionData) ChatTestTransaction.randomTransaction(repository, signingAccount, true);
+            transactionData.setChatReference(null);
+            Transaction transaction = Transaction.fromData(repository, transactionData);
+            transaction.sign(signingAccount);
+
+            assertNull(transactionData.getChatReference());
+
+            final int claimedLength = TransactionTransformer.getDataLength(transactionData);
+            byte[] serializedTransaction = TransactionTransformer.toBytes(transactionData);
+            assertEquals("Serialized CHAT transaction length differs from declared length", claimedLength, serializedTransaction.length);
+
+            TransactionData deserializedTransactionData = TransactionTransformer.fromBytes(serializedTransaction);
+            // Re-sign
+            Transaction deserializedTransaction = Transaction.fromData(repository, deserializedTransactionData);
+            deserializedTransaction.sign(signingAccount);
+            assertEquals("Deserialized CHAT transaction signature differs", Base58.encode(transactionData.getSignature()), Base58.encode(deserializedTransactionData.getSignature()));
+
+            // Re-serialize to check new length and bytes
+            final int reclaimedLength = TransactionTransformer.getDataLength(deserializedTransactionData);
+            assertEquals("Reserialized CHAT transaction declared length differs", claimedLength, reclaimedLength);
+
+            byte[] reserializedTransaction = TransactionTransformer.toBytes(deserializedTransactionData);
+            assertEquals("Reserialized CHAT transaction bytes differ", HashCode.fromBytes(serializedTransaction).toString(), HashCode.fromBytes(reserializedTransaction).toString());
+
+            // Deserialized chat reference must match initial chat reference
+            ChatTransactionData deserializedChatTransactionData = (ChatTransactionData) deserializedTransactionData;
+            assertNull(deserializedChatTransactionData.getChatReference());
+            assertArrayEquals(deserializedChatTransactionData.getChatReference(), transactionData.getChatReference());
+        }
+    }
+
+}

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

@@ -1,4 +1,4 @@
-package org.qortal.test;
+package org.qortal.test.serialization;
 
 import org.junit.Ignore;
 import org.junit.Test;
@@ -47,7 +47,6 @@ public class SerializationTests extends Common {
 				switch (txType) {
 					case GENESIS:
 					case ACCOUNT_FLAGS:
-					case CHAT:
 					case PUBLICIZE:
 					case AIRDROP:
 					case ENABLE_FORGING:
@@ -60,6 +59,7 @@ public class SerializationTests extends Common {
 				TransactionData transactionData = TransactionUtils.randomTransaction(repository, signingAccount, txType, true);
 				Transaction transaction = Transaction.fromData(repository, transactionData);
 				transaction.sign(signingAccount);
+				transaction.importAsUnconfirmed();
 
 				final int claimedLength = TransactionTransformer.getDataLength(transactionData);
 				byte[] serializedTransaction = TransactionTransformer.toBytes(transactionData);

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

@@ -73,7 +73,9 @@
 		"disableReferenceTimestamp": 9999999999999,
 		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999,
 		"onlineAccountMinterLevelValidationHeight": 0,
-		"selfSponsorshipAlgoV1Height": 999999999
+		"selfSponsorshipAlgoV1Height": 999999999,
+		"feeValidationFixTimestamp": 0,
+		"chatReferenceTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -76,7 +76,9 @@
 		"disableReferenceTimestamp": 0,
 		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999,
 		"onlineAccountMinterLevelValidationHeight": 0,
-		"selfSponsorshipAlgoV1Height": 999999999
+		"selfSponsorshipAlgoV1Height": 999999999,
+		"feeValidationFixTimestamp": 0,
+		"chatReferenceTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -77,7 +77,9 @@
 		"disableReferenceTimestamp": 9999999999999,
 		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999,
 		"onlineAccountMinterLevelValidationHeight": 0,
-		"selfSponsorshipAlgoV1Height": 999999999
+		"selfSponsorshipAlgoV1Height": 999999999,
+		"feeValidationFixTimestamp": 0,
+		"chatReferenceTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -77,7 +77,9 @@
 		"disableReferenceTimestamp": 9999999999999,
 		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999,
 		"onlineAccountMinterLevelValidationHeight": 0,
-		"selfSponsorshipAlgoV1Height": 999999999
+		"selfSponsorshipAlgoV1Height": 999999999,
+		"feeValidationFixTimestamp": 0,
+		"chatReferenceTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -77,7 +77,9 @@
 		"disableReferenceTimestamp": 9999999999999,
 		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999,
 		"onlineAccountMinterLevelValidationHeight": 0,
-		"selfSponsorshipAlgoV1Height": 999999999
+		"selfSponsorshipAlgoV1Height": 999999999,
+		"feeValidationFixTimestamp": 0,
+		"chatReferenceTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -77,7 +77,9 @@
 		"disableReferenceTimestamp": 9999999999999,
 		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999,
 		"onlineAccountMinterLevelValidationHeight": 0,
-		"selfSponsorshipAlgoV1Height": 999999999
+		"selfSponsorshipAlgoV1Height": 999999999,
+		"feeValidationFixTimestamp": 0,
+		"chatReferenceTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -78,7 +78,9 @@
 		"aggregateSignatureTimestamp": 0,
 		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999,
 		"onlineAccountMinterLevelValidationHeight": 0,
-		"selfSponsorshipAlgoV1Height": 999999999
+		"selfSponsorshipAlgoV1Height": 999999999,
+		"feeValidationFixTimestamp": 0,
+		"chatReferenceTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -77,7 +77,9 @@
 		"disableReferenceTimestamp": 9999999999999,
 		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999,
 		"onlineAccountMinterLevelValidationHeight": 0,
-		"selfSponsorshipAlgoV1Height": 999999999
+		"selfSponsorshipAlgoV1Height": 999999999,
+		"feeValidationFixTimestamp": 0,
+		"chatReferenceTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -77,7 +77,9 @@
 		"disableReferenceTimestamp": 9999999999999,
 		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999,
 		"onlineAccountMinterLevelValidationHeight": 0,
-		"selfSponsorshipAlgoV1Height": 999999999
+		"selfSponsorshipAlgoV1Height": 999999999,
+		"feeValidationFixTimestamp": 0,
+		"chatReferenceTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -77,7 +77,9 @@
 		"disableReferenceTimestamp": 9999999999999,
 		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999,
 		"onlineAccountMinterLevelValidationHeight": 0,
-		"selfSponsorshipAlgoV1Height": 999999999
+		"selfSponsorshipAlgoV1Height": 999999999,
+		"feeValidationFixTimestamp": 0,
+		"chatReferenceTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -77,7 +77,9 @@
 		"disableReferenceTimestamp": 9999999999999,
 		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999,
 		"onlineAccountMinterLevelValidationHeight": 0,
-		"selfSponsorshipAlgoV1Height": 999999999
+		"selfSponsorshipAlgoV1Height": 999999999,
+		"feeValidationFixTimestamp": 0,
+		"chatReferenceTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2-self-sponsorship-algo.json

@@ -44,7 +44,7 @@
 		{ "height": 1000000, "share": 0.01 }
 	],
 	"qoraPerQortReward": 250,
-	"minAccountsToActivateShareBin": 30,
+	"minAccountsToActivateShareBin": 0,
 	"shareBinActivationMinLevel": 7,
 	"blocksNeededByLevel": [ 5, 20, 30, 40, 50, 60, 18, 80, 90, 100 ],
 	"blockTimingsByHeight": [
@@ -77,7 +77,9 @@
 		"disableReferenceTimestamp": 9999999999999,
 		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999,
 		"onlineAccountMinterLevelValidationHeight": 0,
-		"selfSponsorshipAlgoV1Height": 20
+		"selfSponsorshipAlgoV1Height": 20,
+		"feeValidationFixTimestamp": 0,
+		"chatReferenceTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

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

@@ -77,7 +77,9 @@
 		"disableReferenceTimestamp": 9999999999999,
 		"increaseOnlineAccountsDifficultyTimestamp": 9999999999999,
 		"onlineAccountMinterLevelValidationHeight": 0,
-		"selfSponsorshipAlgoV1Height": 999999999
+		"selfSponsorshipAlgoV1Height": 999999999,
+		"feeValidationFixTimestamp": 0,
+		"chatReferenceTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,