Merge branch '1829-self-destruct-timer-introductions' into '804-self-destructing-messages'

Update introduction client to include a self-destruct timer in each message

See merge request briar/briar!1300

bramble-api/src/main/java/org/briarproject/bramble/util/ValidationUtils.java

@@ -64,4 +64,9 @@ public class ValidationUtils {
 		if (dictionary != null && dictionary.size() != size)
 			throw new FormatException();
 	}
+
+	public static void checkRange(@Nullable Long l, long min, long max)
+			throws FormatException {
+		if (l != null && (l < min || l > max)) throw new FormatException();
+	}
 }

briar-api/src/main/java/org/briarproject/briar/api/conversation/ConversationMessageHeader.java

@@ -12,18 +12,20 @@ public abstract class ConversationMessageHeader {
 
 	private final MessageId id;
 	private final GroupId groupId;
-	private final long timestamp;
+	private final long timestamp, autoDeleteTimer;
-	private final boolean local, sent, seen, read;
+	private final boolean local, read, sent, seen;
 
-	public ConversationMessageHeader(MessageId id, GroupId groupId, long timestamp,
+	public ConversationMessageHeader(MessageId id, GroupId groupId,
-			boolean local, boolean read, boolean sent, boolean seen) {
+			long timestamp, boolean local, boolean read, boolean sent,
+			boolean seen, long autoDeleteTimer) {
 		this.id = id;
 		this.groupId = groupId;
 		this.timestamp = timestamp;
 		this.local = local;
+		this.read = read;
 		this.sent = sent;
 		this.seen = seen;
-		this.read = read;
+		this.autoDeleteTimer = autoDeleteTimer;
 	}
 
 	public MessageId getId() {
@@ -55,4 +57,8 @@ public abstract class ConversationMessageHeader {
 	}
 
 	public abstract <T> T accept(ConversationMessageVisitor<T> v);
+
+	public long getAutoDeleteTimer() {
+		return autoDeleteTimer;
+	}
 }

briar-api/src/main/java/org/briarproject/briar/api/conversation/ConversationRequest.java

@@ -20,11 +20,12 @@ public abstract class ConversationRequest<N extends Nameable>
 	private final String text;
 	private final boolean answered;
 
-	public ConversationRequest(MessageId messageId, GroupId groupId, long time,
+	public ConversationRequest(MessageId messageId, GroupId groupId,
-			boolean local, boolean read, boolean sent, boolean seen,
+			long timestamp, boolean local, boolean read, boolean sent,
-			SessionId sessionId, N nameable, @Nullable String text,
+			boolean seen, SessionId sessionId, N nameable,
-			boolean answered) {
+			@Nullable String text, boolean answered, long autoDeleteTimer) {
-		super(messageId, groupId, time, local, read, sent, seen);
+		super(messageId, groupId, timestamp, local, read, sent, seen,
+				autoDeleteTimer);
 		this.sessionId = sessionId;
 		this.nameable = nameable;
 		this.text = text;

briar-api/src/main/java/org/briarproject/briar/api/conversation/ConversationResponse.java

@@ -16,8 +16,8 @@ public abstract class ConversationResponse extends ConversationMessageHeader {
 
 	public ConversationResponse(MessageId id, GroupId groupId, long time,
 			boolean local, boolean read, boolean sent, boolean seen,
-			SessionId sessionId, boolean accepted) {
+			SessionId sessionId, boolean accepted, long autoDeleteTimer) {
-		super(id, groupId, time, local, read, sent, seen);
+		super(id, groupId, time, local, read, sent, seen, autoDeleteTimer);
 		this.sessionId = sessionId;
 		this.accepted = accepted;
 	}

briar-api/src/main/java/org/briarproject/briar/api/introduction/IntroductionManager.java

@@ -31,7 +31,7 @@ public interface IntroductionManager extends ConversationClient {
 	/**
 	 * The current minor version of the introduction client.
 	 */
-	int MINOR_VERSION = 0;
+	int MINOR_VERSION = 1;
 
 	/**
 	 * Sends two initial introduction messages.

briar-api/src/main/java/org/briarproject/briar/api/introduction/IntroductionRequest.java

@@ -18,12 +18,12 @@ public class IntroductionRequest extends ConversationRequest<Author> {
 
 	private final AuthorInfo authorInfo;
 
-	public IntroductionRequest(MessageId messageId, GroupId groupId,
+	public IntroductionRequest(MessageId messageId, GroupId groupId, long time,
-			long time, boolean local, boolean read, boolean sent, boolean seen,
+			boolean local, boolean read, boolean sent, boolean seen,
 			SessionId sessionId, Author author, @Nullable String text,
-			boolean answered, AuthorInfo authorInfo) {
+			boolean answered, AuthorInfo authorInfo, long autoDeleteTimer) {
 		super(messageId, groupId, time, local, read, sent, seen, sessionId,
-				author, text, answered);
+				author, text, answered, autoDeleteTimer);
 		this.authorInfo = authorInfo;
 	}
 

briar-api/src/main/java/org/briarproject/briar/api/introduction/IntroductionResponse.java

@@ -25,9 +25,10 @@ public class IntroductionResponse extends ConversationResponse {
 	public IntroductionResponse(MessageId messageId, GroupId groupId, long time,
 			boolean local, boolean read, boolean sent, boolean seen,
 			SessionId sessionId, boolean accepted, Author author,
-			AuthorInfo introducedAuthorInfo, Role role, boolean canSucceed) {
+			AuthorInfo introducedAuthorInfo, Role role, boolean canSucceed,
+			long autoDeleteTimer) {
 		super(messageId, groupId, time, local, read, sent, seen, sessionId,
-				accepted);
+				accepted, autoDeleteTimer);
 		this.introducedAuthor = author;
 		this.introducedAuthorInfo = introducedAuthorInfo;
 		this.ourRole = role;

briar-api/src/main/java/org/briarproject/briar/api/messaging/PrivateMessageHeader.java

@@ -16,16 +16,14 @@ public class PrivateMessageHeader extends ConversationMessageHeader {
 
 	private final boolean hasText;
 	private final List<AttachmentHeader> attachmentHeaders;
-	private final long autoDeleteTimer;
 
 	public PrivateMessageHeader(MessageId id, GroupId groupId, long timestamp,
 			boolean local, boolean read, boolean sent, boolean seen,
 			boolean hasText, List<AttachmentHeader> headers,
 			long autoDeleteTimer) {
-		super(id, groupId, timestamp, local, read, sent, seen);
+		super(id, groupId, timestamp, local, read, sent, seen, autoDeleteTimer);
 		this.hasText = hasText;
 		this.attachmentHeaders = headers;
-		this.autoDeleteTimer = autoDeleteTimer;
 	}
 
 	public boolean hasText() {
@@ -36,10 +34,6 @@ public class PrivateMessageHeader extends ConversationMessageHeader {
 		return attachmentHeaders;
 	}
 
-	public long getAutoDeleteTimer() {
-		return autoDeleteTimer;
-	}
-
 	@Override
 	public <T> T accept(ConversationMessageVisitor<T> v) {
 		return v.visitPrivateMessageHeader(this);

briar-api/src/main/java/org/briarproject/briar/api/sharing/InvitationRequest.java

@@ -7,6 +7,8 @@ import org.briarproject.briar.api.conversation.ConversationRequest;
 
 import javax.annotation.Nullable;
 
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
+
 public abstract class InvitationRequest<S extends Shareable> extends
 		ConversationRequest<S> {
 
@@ -17,7 +19,7 @@ public abstract class InvitationRequest<S extends Shareable> extends
 			SessionId sessionId, S object, @Nullable String text,
 			boolean available, boolean canBeOpened) {
 		super(messageId, groupId, time, local, read, sent, seen, sessionId,
-				object, text, !available);
+				object, text, !available, NO_AUTO_DELETE_TIMER);
 		this.canBeOpened = canBeOpened;
 	}
 

briar-api/src/main/java/org/briarproject/briar/api/sharing/InvitationResponse.java

@@ -5,6 +5,8 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.api.client.SessionId;
 import org.briarproject.briar.api.conversation.ConversationResponse;
 
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
+
 public abstract class InvitationResponse extends ConversationResponse {
 
 	private final GroupId shareableId;
@@ -12,7 +14,8 @@ public abstract class InvitationResponse extends ConversationResponse {
 	public InvitationResponse(MessageId id, GroupId groupId, long time,
 			boolean local, boolean read, boolean sent, boolean seen,
 			SessionId sessionId, boolean accepted, GroupId shareableId) {
-		super(id, groupId, time, local, read, sent, seen, sessionId, accepted);
+		super(id, groupId, time, local, read, sent, seen, sessionId, accepted,
+				NO_AUTO_DELETE_TIMER);
 		this.shareableId = shareableId;
 	}
 

briar-core/src/main/java/org/briarproject/briar/introduction/AbortMessage.java

@@ -8,6 +8,8 @@ import org.briarproject.briar.api.client.SessionId;
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
+
 @Immutable
 @NotNullByDefault
 class AbortMessage extends AbstractIntroductionMessage {
@@ -16,7 +18,8 @@ class AbortMessage extends AbstractIntroductionMessage {
 
 	protected AbortMessage(MessageId messageId, GroupId groupId, long timestamp,
 			@Nullable MessageId previousMessageId, SessionId sessionId) {
-		super(messageId, groupId, timestamp, previousMessageId);
+		super(messageId, groupId, timestamp, previousMessageId,
+				NO_AUTO_DELETE_TIMER);
 		this.sessionId = sessionId;
 	}
 

briar-core/src/main/java/org/briarproject/briar/introduction/AbstractIntroductionMessage.java

@@ -16,13 +16,16 @@ abstract class AbstractIntroductionMessage {
 	private final long timestamp;
 	@Nullable
 	private final MessageId previousMessageId;
+	private final long autoDeleteTimer;
 
 	AbstractIntroductionMessage(MessageId messageId, GroupId groupId,
-			long timestamp, @Nullable MessageId previousMessageId) {
+			long timestamp, @Nullable MessageId previousMessageId,
+			long autoDeleteTimer) {
 		this.messageId = messageId;
 		this.groupId = groupId;
 		this.timestamp = timestamp;
 		this.previousMessageId = previousMessageId;
+		this.autoDeleteTimer = autoDeleteTimer;
 	}
 
 	MessageId getMessageId() {
@@ -42,4 +45,7 @@ abstract class AbstractIntroductionMessage {
 		return previousMessageId;
 	}
 
+	public long getAutoDeleteTimer() {
+		return autoDeleteTimer;
+	}
 }

briar-core/src/main/java/org/briarproject/briar/introduction/AbstractProtocolEngine.java

@@ -4,6 +4,7 @@ import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.client.ClientHelper;
 import org.briarproject.bramble.api.client.ContactGroupFactory;
 import org.briarproject.bramble.api.contact.Contact;
+import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.data.BdfDictionary;
@@ -17,9 +18,11 @@ import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.properties.TransportProperties;
+import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.api.versioning.ClientVersioningManager;
 import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.client.SessionId;
 import org.briarproject.briar.api.introduction.IntroductionResponse;
@@ -30,6 +33,10 @@ import java.util.Map;
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
+import static org.briarproject.briar.api.introduction.IntroductionManager.CLIENT_ID;
+import static org.briarproject.briar.api.introduction.IntroductionManager.MAJOR_VERSION;
+import static org.briarproject.briar.introduction.IntroductionConstants.GROUP_KEY_CONTACT_ID;
 import static org.briarproject.briar.introduction.MessageType.ABORT;
 import static org.briarproject.briar.introduction.MessageType.ACCEPT;
 import static org.briarproject.briar.introduction.MessageType.ACTIVATE;
@@ -39,7 +46,7 @@ import static org.briarproject.briar.introduction.MessageType.REQUEST;
 
 @Immutable
 @NotNullByDefault
-abstract class AbstractProtocolEngine<S extends Session>
+abstract class AbstractProtocolEngine<S extends Session<?>>
 		implements ProtocolEngine<S> {
 
 	protected final DatabaseComponent db;
@@ -50,6 +57,7 @@ abstract class AbstractProtocolEngine<S extends Session>
 	protected final IdentityManager identityManager;
 	protected final MessageParser messageParser;
 	protected final MessageEncoder messageEncoder;
+	protected final ClientVersioningManager clientVersioningManager;
 	protected final Clock clock;
 
 	AbstractProtocolEngine(
@@ -61,6 +69,7 @@ abstract class AbstractProtocolEngine<S extends Session>
 			IdentityManager identityManager,
 			MessageParser messageParser,
 			MessageEncoder messageEncoder,
+			ClientVersioningManager clientVersioningManager,
 			Clock clock) {
 		this.db = db;
 		this.clientHelper = clientHelper;
@@ -70,16 +79,26 @@ abstract class AbstractProtocolEngine<S extends Session>
 		this.identityManager = identityManager;
 		this.messageParser = messageParser;
 		this.messageEncoder = messageEncoder;
+		this.clientVersioningManager = clientVersioningManager;
 		this.clock = clock;
 	}
 
 	Message sendRequestMessage(Transaction txn, PeerSession s,
 			long timestamp, Author author, @Nullable String text)
 			throws DbException {
-		Message m = messageEncoder
+		Message m;
-				.encodeRequestMessage(s.getContactGroupId(), timestamp,
+		if (contactSupportsAutoDeletion(txn, s.getContactGroupId())) {
-						s.getLastLocalMessageId(), author, text);
+			// TODO: Look up the current auto-delete timer
-		sendMessage(txn, REQUEST, s.getSessionId(), m, true);
+			long timer = NO_AUTO_DELETE_TIMER;
+			m = messageEncoder.encodeRequestMessage(s.getContactGroupId(),
+					timestamp, s.getLastLocalMessageId(), author, text, timer);
+			sendMessage(txn, REQUEST, s.getSessionId(), m, true, timer);
+		} else {
+			m = messageEncoder.encodeRequestMessage(s.getContactGroupId(),
+					timestamp, s.getLastLocalMessageId(), author, text);
+			sendMessage(txn, REQUEST, s.getSessionId(), m, true,
+					NO_AUTO_DELETE_TIMER);
+		}
 		return m;
 	}
 
@@ -87,21 +106,41 @@ abstract class AbstractProtocolEngine<S extends Session>
 			PublicKey ephemeralPublicKey, long acceptTimestamp,
 			Map<TransportId, TransportProperties> transportProperties,
 			boolean visible) throws DbException {
-		Message m = messageEncoder
+		Message m;
-				.encodeAcceptMessage(s.getContactGroupId(), timestamp,
+		if (contactSupportsAutoDeletion(txn, s.getContactGroupId())) {
-						s.getLastLocalMessageId(), s.getSessionId(),
+			// TODO: Look up the current auto-delete timer
-						ephemeralPublicKey, acceptTimestamp,
+			long timer = NO_AUTO_DELETE_TIMER;
-						transportProperties);
+			m = messageEncoder.encodeAcceptMessage(s.getContactGroupId(),
-		sendMessage(txn, ACCEPT, s.getSessionId(), m, visible);
+					timestamp, s.getLastLocalMessageId(), s.getSessionId(),
+					ephemeralPublicKey, acceptTimestamp, transportProperties,
+					timer);
+			sendMessage(txn, ACCEPT, s.getSessionId(), m, visible, timer);
+		} else {
+			m = messageEncoder.encodeAcceptMessage(s.getContactGroupId(),
+					timestamp, s.getLastLocalMessageId(), s.getSessionId(),
+					ephemeralPublicKey, acceptTimestamp, transportProperties);
+			sendMessage(txn, ACCEPT, s.getSessionId(), m, visible,
+					NO_AUTO_DELETE_TIMER);
+		}
 		return m;
 	}
 
 	Message sendDeclineMessage(Transaction txn, PeerSession s, long timestamp,
 			boolean visible) throws DbException {
-		Message m = messageEncoder
+		Message m;
-				.encodeDeclineMessage(s.getContactGroupId(), timestamp,
+		if (contactSupportsAutoDeletion(txn, s.getContactGroupId())) {
-						s.getLastLocalMessageId(), s.getSessionId());
+			// TODO: Look up the current auto-delete timer
-		sendMessage(txn, DECLINE, s.getSessionId(), m, visible);
+			long timer = NO_AUTO_DELETE_TIMER;
+			m = messageEncoder.encodeDeclineMessage(s.getContactGroupId(),
+					timestamp, s.getLastLocalMessageId(), s.getSessionId(),
+					timer);
+			sendMessage(txn, DECLINE, s.getSessionId(), m, visible, timer);
+		} else {
+			m = messageEncoder.encodeDeclineMessage(s.getContactGroupId(),
+					timestamp, s.getLastLocalMessageId(), s.getSessionId());
+			sendMessage(txn, DECLINE, s.getSessionId(), m, visible,
+					NO_AUTO_DELETE_TIMER);
+		}
 		return m;
 	}
 
@@ -111,7 +150,8 @@ abstract class AbstractProtocolEngine<S extends Session>
 				.encodeAuthMessage(s.getContactGroupId(), timestamp,
 						s.getLastLocalMessageId(), s.getSessionId(), mac,
 						signature);
-		sendMessage(txn, AUTH, s.getSessionId(), m, false);
+		sendMessage(txn, AUTH, s.getSessionId(), m, false,
+				NO_AUTO_DELETE_TIMER);
 		return m;
 	}
 
@@ -120,7 +160,8 @@ abstract class AbstractProtocolEngine<S extends Session>
 		Message m = messageEncoder
 				.encodeActivateMessage(s.getContactGroupId(), timestamp,
 						s.getLastLocalMessageId(), s.getSessionId(), mac);
-		sendMessage(txn, ACTIVATE, s.getSessionId(), m, false);
+		sendMessage(txn, ACTIVATE, s.getSessionId(), m, false,
+				NO_AUTO_DELETE_TIMER);
 		return m;
 	}
 
@@ -129,16 +170,17 @@ abstract class AbstractProtocolEngine<S extends Session>
 		Message m = messageEncoder
 				.encodeAbortMessage(s.getContactGroupId(), timestamp,
 						s.getLastLocalMessageId(), s.getSessionId());
-		sendMessage(txn, ABORT, s.getSessionId(), m, false);
+		sendMessage(txn, ABORT, s.getSessionId(), m, false,
+				NO_AUTO_DELETE_TIMER);
 		return m;
 	}
 
 	private void sendMessage(Transaction txn, MessageType type,
-			SessionId sessionId, Message m, boolean visibleInConversation)
+			SessionId sessionId, Message m, boolean visibleInConversation,
-			throws DbException {
+			long autoDeleteTimer) throws DbException {
-		BdfDictionary meta = messageEncoder
+		BdfDictionary meta = messageEncoder.encodeMetadata(type, sessionId,
-				.encodeMetadata(type, sessionId, m.getTimestamp(), true, true,
+				m.getTimestamp(), true, true, visibleInConversation,
-						visibleInConversation);
+				autoDeleteTimer);
 		try {
 			clientHelper.addLocalMessage(txn, m, meta, true, false);
 		} catch (FormatException e) {
@@ -146,9 +188,10 @@ abstract class AbstractProtocolEngine<S extends Session>
 		}
 	}
 
-	void broadcastIntroductionResponseReceivedEvent(Transaction txn, Session s,
+	void broadcastIntroductionResponseReceivedEvent(Transaction txn,
-			AuthorId sender, Author otherAuthor, AbstractIntroductionMessage m,
+			Session<?> s, AuthorId sender, Author otherAuthor,
-			boolean canSucceed) throws DbException {
+			AbstractIntroductionMessage m, boolean canSucceed)
+			throws DbException {
 		AuthorId localAuthorId = identityManager.getLocalAuthor(txn).getId();
 		Contact c = contactManager.getContact(txn, sender, localAuthorId);
 		AuthorInfo otherAuthorInfo =
@@ -157,7 +200,8 @@ abstract class AbstractProtocolEngine<S extends Session>
 				new IntroductionResponse(m.getMessageId(), m.getGroupId(),
 						m.getTimestamp(), false, false, false, false,
 						s.getSessionId(), m instanceof AcceptMessage,
-						otherAuthor, otherAuthorInfo, s.getRole(), canSucceed);
+						otherAuthor, otherAuthorInfo, s.getRole(), canSucceed,
+						m.getAutoDeleteTimer());
 		IntroductionResponseReceivedEvent e =
 				new IntroductionResponseReceivedEvent(response, c.getId());
 		txn.attach(e);
@@ -190,4 +234,19 @@ abstract class AbstractProtocolEngine<S extends Session>
 		);
 	}
 
+	boolean contactSupportsAutoDeletion(Transaction txn, GroupId contactGroupId)
+			throws DbException {
+		try {
+			BdfDictionary meta = clientHelper
+					.getGroupMetadataAsDictionary(txn, contactGroupId);
+			int contactId = meta.getLong(GROUP_KEY_CONTACT_ID).intValue();
+			ContactId c = new ContactId(contactId);
+			int minorVersion = clientVersioningManager
+					.getClientMinorVersion(txn, c, CLIENT_ID, MAJOR_VERSION);
+			// Auto-delete was added in client version 0.1
+			return minorVersion >= 1;
+		} catch (FormatException e) {
+			throw new DbException(e);
+		}
+	}
 }

briar-core/src/main/java/org/briarproject/briar/introduction/AcceptMessage.java

@@ -26,8 +26,10 @@ class AcceptMessage extends AbstractIntroductionMessage {
 			long timestamp, @Nullable MessageId previousMessageId,
 			SessionId sessionId, PublicKey ephemeralPublicKey,
 			long acceptTimestamp,
-			Map<TransportId, TransportProperties> transportProperties) {
+			Map<TransportId, TransportProperties> transportProperties,
-		super(messageId, groupId, timestamp, previousMessageId);
+			long autoDeleteTimer) {
+		super(messageId, groupId, timestamp, previousMessageId,
+				autoDeleteTimer);
 		this.sessionId = sessionId;
 		this.ephemeralPublicKey = ephemeralPublicKey;
 		this.acceptTimestamp = acceptTimestamp;

briar-core/src/main/java/org/briarproject/briar/introduction/ActivateMessage.java

@@ -7,6 +7,8 @@ import org.briarproject.briar.api.client.SessionId;
 
 import javax.annotation.concurrent.Immutable;
 
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
+
 @Immutable
 @NotNullByDefault
 class ActivateMessage extends AbstractIntroductionMessage {
@@ -17,7 +19,8 @@ class ActivateMessage extends AbstractIntroductionMessage {
 	protected ActivateMessage(MessageId messageId, GroupId groupId,
 			long timestamp, MessageId previousMessageId, SessionId sessionId,
 			byte[] mac) {
-		super(messageId, groupId, timestamp, previousMessageId);
+		super(messageId, groupId, timestamp, previousMessageId,
+				NO_AUTO_DELETE_TIMER);
 		this.sessionId = sessionId;
 		this.mac = mac;
 	}

briar-core/src/main/java/org/briarproject/briar/introduction/AuthMessage.java

@@ -7,6 +7,8 @@ import org.briarproject.briar.api.client.SessionId;
 
 import javax.annotation.concurrent.Immutable;
 
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
+
 @Immutable
 @NotNullByDefault
 class AuthMessage extends AbstractIntroductionMessage {
@@ -17,7 +19,8 @@ class AuthMessage extends AbstractIntroductionMessage {
 	protected AuthMessage(MessageId messageId, GroupId groupId,
 			long timestamp, MessageId previousMessageId, SessionId sessionId,
 			byte[] mac, byte[] signature) {
-		super(messageId, groupId, timestamp, previousMessageId);
+		super(messageId, groupId, timestamp, previousMessageId,
+				NO_AUTO_DELETE_TIMER);
 		this.sessionId = sessionId;
 		this.mac = mac;
 		this.signature = signature;

briar-core/src/main/java/org/briarproject/briar/introduction/DeclineMessage.java

@@ -16,8 +16,9 @@ class DeclineMessage extends AbstractIntroductionMessage {
 
 	protected DeclineMessage(MessageId messageId, GroupId groupId,
 			long timestamp, @Nullable MessageId previousMessageId,
-			SessionId sessionId) {
+			SessionId sessionId, long autoDeleteTimer) {
-		super(messageId, groupId, timestamp, previousMessageId);
+		super(messageId, groupId, timestamp, previousMessageId,
+				autoDeleteTimer);
 		this.sessionId = sessionId;
 	}
 

briar-core/src/main/java/org/briarproject/briar/introduction/IntroduceeProtocolEngine.java

@@ -26,6 +26,7 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.transport.KeyManager;
 import org.briarproject.bramble.api.transport.KeySetId;
+import org.briarproject.bramble.api.versioning.ClientVersioningManager;
 import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.client.ProtocolStateException;
 import org.briarproject.briar.api.client.SessionId;
@@ -76,10 +77,11 @@ class IntroduceeProtocolEngine
 			Clock clock,
 			IntroductionCrypto crypto,
 			KeyManager keyManager,
-			TransportPropertyManager transportPropertyManager) {
+			TransportPropertyManager transportPropertyManager,
+			ClientVersioningManager clientVersioningManager) {
 		super(db, clientHelper, contactManager, contactGroupFactory,
 				messageTracker, identityManager, messageParser, messageEncoder,
-				clock);
+				clientVersioningManager, clock);
 		this.crypto = crypto;
 		this.keyManager = keyManager;
 		this.transportPropertyManager = transportPropertyManager;
@@ -258,7 +260,7 @@ class IntroduceeProtocolEngine
 		IntroductionRequest request = new IntroductionRequest(m.getMessageId(),
 				m.getGroupId(), m.getTimestamp(), false, false, false, false,
 				s.getSessionId(), m.getAuthor(), m.getText(), false,
-				authorInfo);
+				authorInfo, m.getAutoDeleteTimer());
 		IntroductionRequestReceivedEvent e =
 				new IntroductionRequestReceivedEvent(request, c.getId());
 		txn.attach(e);

briar-core/src/main/java/org/briarproject/briar/introduction/IntroducerProtocolEngine.java

@@ -13,6 +13,7 @@ import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.api.versioning.ClientVersioningManager;
 import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.client.ProtocolStateException;
 import org.briarproject.briar.api.introduction.event.IntroductionAbortedEvent;
@@ -50,10 +51,11 @@ class IntroducerProtocolEngine
 			IdentityManager identityManager,
 			MessageParser messageParser,
 			MessageEncoder messageEncoder,
+			ClientVersioningManager clientVersioningManager,
 			Clock clock) {
 		super(db, clientHelper, contactManager, contactGroupFactory,
 				messageTracker, identityManager, messageParser, messageEncoder,
-				clock);
+				clientVersioningManager, clock);
 	}
 
 	@Override

briar-core/src/main/java/org/briarproject/briar/introduction/IntroductionConstants.java

@@ -12,6 +12,7 @@ interface IntroductionConstants {
 	String MSG_KEY_LOCAL = "local";
 	String MSG_KEY_VISIBLE_IN_UI = "visibleInUi";
 	String MSG_KEY_AVAILABLE_TO_ANSWER = "availableToAnswer";
+	String MSG_KEY_AUTO_DELETE_TIMER = "autoDeleteTimer";
 
 	// Session Keys
 	String SESSION_KEY_SESSION_ID = "sessionId";

briar-core/src/main/java/org/briarproject/briar/introduction/IntroductionManagerImpl.java

@@ -461,7 +461,7 @@ class IntroductionManagerImpl extends ConversationClientImpl
 		return new IntroductionRequest(m, contactGroupId, meta.getTimestamp(),
 				meta.isLocal(), meta.isRead(), status.isSent(), status.isSeen(),
 				sessionId, author, text, !meta.isAvailableToAnswer(),
-				authorInfo);
+				authorInfo, rm.getAutoDeleteTimer());
 	}
 
 	private IntroductionResponse parseInvitationResponse(Transaction txn,
@@ -499,7 +499,8 @@ class IntroductionManagerImpl extends ConversationClientImpl
 		}
 		return new IntroductionResponse(m, contactGroupId, meta.getTimestamp(),
 				meta.isLocal(), meta.isRead(), status.isSent(), status.isSeen(),
-				sessionId, accept, author, authorInfo, role, canSucceed);
+				sessionId, accept, author, authorInfo, role, canSucceed,
+				meta.getAutoDeleteTimer());
 	}
 
 	private void removeSessionWithIntroducer(Transaction txn,

briar-core/src/main/java/org/briarproject/briar/introduction/IntroductionValidator.java

@@ -15,13 +15,18 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.briar.api.client.SessionId;
 
+import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 
 import static java.util.Collections.singletonList;
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.MAX_AUTO_DELETE_TIMER_MS;
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.MIN_AUTO_DELETE_TIMER_MS;
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
 import static org.briarproject.bramble.api.crypto.CryptoConstants.MAC_BYTES;
 import static org.briarproject.bramble.api.crypto.CryptoConstants.MAX_SIGNATURE_BYTES;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
 import static org.briarproject.bramble.util.ValidationUtils.checkLength;
+import static org.briarproject.bramble.util.ValidationUtils.checkRange;
 import static org.briarproject.bramble.util.ValidationUtils.checkSize;
 import static org.briarproject.briar.api.introduction.IntroductionConstants.MAX_INTRODUCTION_TEXT_LENGTH;
 import static org.briarproject.briar.introduction.MessageType.ACCEPT;
@@ -52,13 +57,14 @@ class IntroductionValidator extends BdfMessageValidator {
 				return validateRequestMessage(m, body);
 			case ACCEPT:
 				return validateAcceptMessage(m, body);
+			case DECLINE:
+				return validateDeclineMessage(type, m, body);
 			case AUTH:
 				return validateAuthMessage(m, body);
 			case ACTIVATE:
 				return validateActivateMessage(m, body);
-			case DECLINE:
 			case ABORT:
-				return validateOtherMessage(type, m, body);
+				return validateAbortMessage(type, m, body);
 			default:
 				throw new FormatException();
 		}
@@ -66,7 +72,11 @@ class IntroductionValidator extends BdfMessageValidator {
 
 	private BdfMessageContext validateRequestMessage(Message m, BdfList body)
 			throws FormatException {
-		checkSize(body, 4);
+		// Client version 0.0: Message type, optional previous message ID,
+		// author, optional text.
+		// Client version 0.1: Message type, optional previous message ID,
+		// author, optional text, optional auto-delete timer.
+		checkSize(body, 4, 5);
 
 		byte[] previousMessageId = body.getOptionalRaw(1);
 		checkLength(previousMessageId, UniqueId.LENGTH);
@@ -77,8 +87,11 @@ class IntroductionValidator extends BdfMessageValidator {
 		String text = body.getOptionalString(3);
 		checkLength(text, 1, MAX_INTRODUCTION_TEXT_LENGTH);
 
+		long timer = NO_AUTO_DELETE_TIMER;
+		if (body.size() == 5) timer = validateTimer(body.getOptionalLong(4));
+
 		BdfDictionary meta =
-				messageEncoder.encodeRequestMetadata(m.getTimestamp());
+				messageEncoder.encodeRequestMetadata(m.getTimestamp(), timer);
 		if (previousMessageId == null) {
 			return new BdfMessageContext(meta);
 		} else {
@@ -89,7 +102,12 @@ class IntroductionValidator extends BdfMessageValidator {
 
 	private BdfMessageContext validateAcceptMessage(Message m, BdfList body)
 			throws FormatException {
-		checkSize(body, 6);
+		// Client version 0.0: Message type, session ID, optional previous
+		// message ID, ephemeral public key, timestamp, transport properties.
+		// Client version 0.1: Message type, session ID, optional previous
+		// message ID, ephemeral public key, timestamp, transport properties,
+		// optional auto-delete timer.
+		checkSize(body, 6, 7);
 
 		byte[] sessionIdBytes = body.getRaw(1);
 		checkLength(sessionIdBytes, UniqueId.LENGTH);
@@ -109,9 +127,40 @@ class IntroductionValidator extends BdfMessageValidator {
 		clientHelper
 				.parseAndValidateTransportPropertiesMap(transportProperties);
 
+		long timer = NO_AUTO_DELETE_TIMER;
+		if (body.size() == 7) timer = validateTimer(body.getOptionalLong(6));
+
 		SessionId sessionId = new SessionId(sessionIdBytes);
 		BdfDictionary meta = messageEncoder.encodeMetadata(ACCEPT, sessionId,
-				m.getTimestamp(), false, false, false);
+				m.getTimestamp(), false, false, false, timer);
+		if (previousMessageId == null) {
+			return new BdfMessageContext(meta);
+		} else {
+			MessageId dependency = new MessageId(previousMessageId);
+			return new BdfMessageContext(meta, singletonList(dependency));
+		}
+	}
+
+	private BdfMessageContext validateDeclineMessage(MessageType type,
+			Message m, BdfList body) throws FormatException {
+		// Client version 0.0: Message type, session ID, optional previous
+		// message ID.
+		// Client version 0.1: Message type, session ID, optional previous
+		// message ID, optional auto-delete timer.
+		checkSize(body, 3, 4);
+
+		byte[] sessionIdBytes = body.getRaw(1);
+		checkLength(sessionIdBytes, UniqueId.LENGTH);
+
+		byte[] previousMessageId = body.getOptionalRaw(2);
+		checkLength(previousMessageId, UniqueId.LENGTH);
+
+		long timer = NO_AUTO_DELETE_TIMER;
+		if (body.size() == 4) timer = validateTimer(body.getOptionalLong(3));
+
+		SessionId sessionId = new SessionId(sessionIdBytes);
+		BdfDictionary meta = messageEncoder.encodeMetadata(type, sessionId,
+				m.getTimestamp(), false, false, false, timer);
 		if (previousMessageId == null) {
 			return new BdfMessageContext(meta);
 		} else {
@@ -138,7 +187,7 @@ class IntroductionValidator extends BdfMessageValidator {
 
 		SessionId sessionId = new SessionId(sessionIdBytes);
 		BdfDictionary meta = messageEncoder.encodeMetadata(AUTH, sessionId,
-				m.getTimestamp(), false, false, false);
+				m.getTimestamp(), false, false, false, NO_AUTO_DELETE_TIMER);
 		MessageId dependency = new MessageId(previousMessageId);
 		return new BdfMessageContext(meta, singletonList(dependency));
 	}
@@ -158,7 +207,7 @@ class IntroductionValidator extends BdfMessageValidator {
 
 		SessionId sessionId = new SessionId(sessionIdBytes);
 		BdfDictionary meta = messageEncoder.encodeMetadata(ACTIVATE, sessionId,
-				m.getTimestamp(), false, false, false);
+				m.getTimestamp(), false, false, false, NO_AUTO_DELETE_TIMER);
 		if (previousMessageId == null) {
 			return new BdfMessageContext(meta);
 		} else {
@@ -167,7 +216,7 @@ class IntroductionValidator extends BdfMessageValidator {
 		}
 	}
 
-	private BdfMessageContext validateOtherMessage(MessageType type,
+	private BdfMessageContext validateAbortMessage(MessageType type,
 			Message m, BdfList body) throws FormatException {
 		checkSize(body, 3);
 
@@ -179,7 +228,7 @@ class IntroductionValidator extends BdfMessageValidator {
 
 		SessionId sessionId = new SessionId(sessionIdBytes);
 		BdfDictionary meta = messageEncoder.encodeMetadata(type, sessionId,
-				m.getTimestamp(), false, false, false);
+				m.getTimestamp(), false, false, false, NO_AUTO_DELETE_TIMER);
 		if (previousMessageId == null) {
 			return new BdfMessageContext(meta);
 		} else {
@@ -188,4 +237,9 @@ class IntroductionValidator extends BdfMessageValidator {
 		}
 	}
 
+	private long validateTimer(@Nullable Long timer) throws FormatException {
+		if (timer == null) return NO_AUTO_DELETE_TIMER;
+		checkRange(timer, MIN_AUTO_DELETE_TIMER_MS, MAX_AUTO_DELETE_TIMER_MS);
+		return timer;
+	}
 }

briar-core/src/main/java/org/briarproject/briar/introduction/MessageEncoder.java

@@ -18,11 +18,12 @@ import javax.annotation.Nullable;
 @NotNullByDefault
 interface MessageEncoder {
 
-	BdfDictionary encodeRequestMetadata(long timestamp);
+	BdfDictionary encodeRequestMetadata(long timestamp,
+			long autoDeleteTimer);
 
 	BdfDictionary encodeMetadata(MessageType type,
 			@Nullable SessionId sessionId, long timestamp, boolean local,
-			boolean read, boolean visible);
+			boolean read, boolean visible, long autoDeleteTimer);
 
 	void addSessionId(BdfDictionary meta, SessionId sessionId);
 
@@ -30,18 +31,53 @@ interface MessageEncoder {
 
 	void setAvailableToAnswer(BdfDictionary meta, boolean available);
 
+	/**
+	 * Encodes a request message without an auto-delete timer.
+	 */
 	Message encodeRequestMessage(GroupId contactGroupId, long timestamp,
 			@Nullable MessageId previousMessageId, Author author,
 			@Nullable String text);
 
+	/**
+	 * Encodes a request message with an optional auto-delete timer. This
+	 * requires the contact to support client version 0.1 or higher.
+	 */
+	Message encodeRequestMessage(GroupId contactGroupId, long timestamp,
+			@Nullable MessageId previousMessageId, Author author,
+			@Nullable String text, long autoDeleteTimer);
+
+	/**
+	 * Encodes an accept message without an auto-delete timer.
+	 */
 	Message encodeAcceptMessage(GroupId contactGroupId, long timestamp,
 			@Nullable MessageId previousMessageId, SessionId sessionId,
 			PublicKey ephemeralPublicKey, long acceptTimestamp,
 			Map<TransportId, TransportProperties> transportProperties);
 
+	/**
+	 * Encodes an accept message with an optional auto-delete timer. This
+	 * requires the contact to support client version 0.1 or higher.
+	 */
+	Message encodeAcceptMessage(GroupId contactGroupId, long timestamp,
+			@Nullable MessageId previousMessageId, SessionId sessionId,
+			PublicKey ephemeralPublicKey, long acceptTimestamp,
+			Map<TransportId, TransportProperties> transportProperties,
+			long autoDeleteTimer);
+
+	/**
+	 * Encodes a decline message without an auto-delete timer.
+	 */
 	Message encodeDeclineMessage(GroupId contactGroupId, long timestamp,
 			@Nullable MessageId previousMessageId, SessionId sessionId);
 
+	/**
+	 * Encodes a decline message with an optional auto-delete timer. This
+	 * requires the contact to support client version 0.1 or higher.
+	 */
+	Message encodeDeclineMessage(GroupId contactGroupId, long timestamp,
+			@Nullable MessageId previousMessageId, SessionId sessionId,
+			long autoDeleteTimer);
+
 	Message encodeAuthMessage(GroupId contactGroupId, long timestamp,
 			@Nullable MessageId previousMessageId, SessionId sessionId,
 			byte[] mac, byte[] signature);

briar-core/src/main/java/org/briarproject/briar/introduction/MessageEncoderImpl.java

@@ -20,7 +20,9 @@ import java.util.Map;
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
 import static org.briarproject.briar.client.MessageTrackerConstants.MSG_KEY_READ;
+import static org.briarproject.briar.introduction.IntroductionConstants.MSG_KEY_AUTO_DELETE_TIMER;
 import static org.briarproject.briar.introduction.IntroductionConstants.MSG_KEY_AVAILABLE_TO_ANSWER;
 import static org.briarproject.briar.introduction.IntroductionConstants.MSG_KEY_LOCAL;
 import static org.briarproject.briar.introduction.IntroductionConstants.MSG_KEY_MESSAGE_TYPE;
@@ -48,9 +50,10 @@ class MessageEncoderImpl implements MessageEncoder {
 	}
 
 	@Override
-	public BdfDictionary encodeRequestMetadata(long timestamp) {
+	public BdfDictionary encodeRequestMetadata(long timestamp,
-		BdfDictionary meta =
+			long autoDeleteTimer) {
-				encodeMetadata(REQUEST, null, timestamp, false, false, false);
+		BdfDictionary meta = encodeMetadata(REQUEST, null, timestamp,
+				false, false, false, autoDeleteTimer);
 		meta.put(MSG_KEY_AVAILABLE_TO_ANSWER, false);
 		return meta;
 	}
@@ -58,7 +61,7 @@ class MessageEncoderImpl implements MessageEncoder {
 	@Override
 	public BdfDictionary encodeMetadata(MessageType type,
 			@Nullable SessionId sessionId, long timestamp, boolean local,
-			boolean read, boolean visible) {
+			boolean read, boolean visible, long autoDeleteTimer) {
 		BdfDictionary meta = new BdfDictionary();
 		meta.put(MSG_KEY_MESSAGE_TYPE, type.getValue());
 		if (sessionId != null)
@@ -69,6 +72,9 @@ class MessageEncoderImpl implements MessageEncoder {
 		meta.put(MSG_KEY_LOCAL, local);
 		meta.put(MSG_KEY_READ, read);
 		meta.put(MSG_KEY_VISIBLE_IN_UI, visible);
+		if (autoDeleteTimer != NO_AUTO_DELETE_TIMER) {
+			meta.put(MSG_KEY_AUTO_DELETE_TIMER, autoDeleteTimer);
+		}
 		return meta;
 	}
 
@@ -103,6 +109,23 @@ class MessageEncoderImpl implements MessageEncoder {
 		return createMessage(contactGroupId, timestamp, body);
 	}
 
+	@Override
+	public Message encodeRequestMessage(GroupId contactGroupId, long timestamp,
+			@Nullable MessageId previousMessageId, Author author,
+			@Nullable String text, long autoDeleteTimer) {
+		if (text != null && text.isEmpty()) {
+			throw new IllegalArgumentException();
+		}
+		BdfList body = BdfList.of(
+				REQUEST.getValue(),
+				previousMessageId,
+				clientHelper.toList(author),
+				text,
+				encodeTimer(autoDeleteTimer)
+		);
+		return createMessage(contactGroupId, timestamp, body);
+	}
+
 	@Override
 	public Message encodeAcceptMessage(GroupId contactGroupId, long timestamp,
 			@Nullable MessageId previousMessageId, SessionId sessionId,
@@ -119,11 +142,46 @@ class MessageEncoderImpl implements MessageEncoder {
 		return createMessage(contactGroupId, timestamp, body);
 	}
 
+	@Override
+	public Message encodeAcceptMessage(GroupId contactGroupId, long timestamp,
+			@Nullable MessageId previousMessageId, SessionId sessionId,
+			PublicKey ephemeralPublicKey, long acceptTimestamp,
+			Map<TransportId, TransportProperties> transportProperties,
+			long autoDeleteTimer) {
+		BdfList body = BdfList.of(
+				ACCEPT.getValue(),
+				sessionId,
+				previousMessageId,
+				ephemeralPublicKey.getEncoded(),
+				acceptTimestamp,
+				clientHelper.toDictionary(transportProperties),
+				encodeTimer(autoDeleteTimer)
+		);
+		return createMessage(contactGroupId, timestamp, body);
+	}
+
 	@Override
 	public Message encodeDeclineMessage(GroupId contactGroupId, long timestamp,
 			@Nullable MessageId previousMessageId, SessionId sessionId) {
-		return encodeMessage(DECLINE, contactGroupId, sessionId, timestamp,
+		BdfList body = BdfList.of(
-				previousMessageId);
+				DECLINE.getValue(),
+				sessionId,
+				previousMessageId
+		);
+		return createMessage(contactGroupId, timestamp, body);
+	}
+
+	@Override
+	public Message encodeDeclineMessage(GroupId contactGroupId, long timestamp,
+			@Nullable MessageId previousMessageId, SessionId sessionId,
+			long autoDeleteTimer) {
+		BdfList body = BdfList.of(
+				DECLINE.getValue(),
+				sessionId,
+				previousMessageId,
+				encodeTimer(autoDeleteTimer)
+		);
+		return createMessage(contactGroupId, timestamp, body);
 	}
 
 	@Override
@@ -156,15 +214,8 @@ class MessageEncoderImpl implements MessageEncoder {
 	@Override
 	public Message encodeAbortMessage(GroupId contactGroupId, long timestamp,
 			@Nullable MessageId previousMessageId, SessionId sessionId) {
-		return encodeMessage(ABORT, contactGroupId, sessionId, timestamp,
-				previousMessageId);
-	}
-
-	private Message encodeMessage(MessageType type, GroupId contactGroupId,
-			SessionId sessionId, long timestamp,
-			@Nullable MessageId previousMessageId) {
 		BdfList body = BdfList.of(
-				type.getValue(),
+				ABORT.getValue(),
 				sessionId,
 				previousMessageId
 		);
@@ -181,4 +232,8 @@ class MessageEncoderImpl implements MessageEncoder {
 		}
 	}
 
+	@Nullable
+	private Long encodeTimer(long autoDeleteTimer) {
+		return autoDeleteTimer == NO_AUTO_DELETE_TIMER ? null : autoDeleteTimer;
+	}
 }

briar-core/src/main/java/org/briarproject/briar/introduction/MessageMetadata.java

@@ -13,12 +13,12 @@ class MessageMetadata {
 	private final MessageType type;
 	@Nullable
 	private final SessionId sessionId;
-	private final long timestamp;
+	private final long timestamp, autoDeleteTimer;
 	private final boolean local, read, visible, available;
 
 	MessageMetadata(MessageType type, @Nullable SessionId sessionId,
 			long timestamp, boolean local, boolean read, boolean visible,
-			boolean available) {
+			boolean available, long autoDeleteTimer) {
 		this.type = type;
 		this.sessionId = sessionId;
 		this.timestamp = timestamp;
@@ -26,6 +26,7 @@ class MessageMetadata {
 		this.read = read;
 		this.visible = visible;
 		this.available = available;
+		this.autoDeleteTimer = autoDeleteTimer;
 	}
 
 	MessageType getMessageType() {
@@ -57,4 +58,7 @@ class MessageMetadata {
 		return available;
 	}
 
+	public long getAutoDeleteTimer() {
+		return autoDeleteTimer;
+	}
 }

briar-core/src/main/java/org/briarproject/briar/introduction/MessageParserImpl.java

@@ -19,7 +19,9 @@ import java.util.Map;
 
 import javax.inject.Inject;
 
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
 import static org.briarproject.briar.client.MessageTrackerConstants.MSG_KEY_READ;
+import static org.briarproject.briar.introduction.IntroductionConstants.MSG_KEY_AUTO_DELETE_TIMER;
 import static org.briarproject.briar.introduction.IntroductionConstants.MSG_KEY_AVAILABLE_TO_ANSWER;
 import static org.briarproject.briar.introduction.IntroductionConstants.MSG_KEY_LOCAL;
 import static org.briarproject.briar.introduction.IntroductionConstants.MSG_KEY_MESSAGE_TYPE;
@@ -65,8 +67,9 @@ class MessageParserImpl implements MessageParser {
 		boolean read = d.getBoolean(MSG_KEY_READ);
 		boolean visible = d.getBoolean(MSG_KEY_VISIBLE_IN_UI);
 		boolean available = d.getBoolean(MSG_KEY_AVAILABLE_TO_ANSWER, false);
+		long timer = d.getLong(MSG_KEY_AUTO_DELETE_TIMER, NO_AUTO_DELETE_TIMER);
 		return new MessageMetadata(type, sessionId, timestamp, local, read,
-				visible, available);
+				visible, available, timer);
 	}
 
 	@Override
@@ -77,8 +80,10 @@ class MessageParserImpl implements MessageParser {
 				new MessageId(previousMsgBytes));
 		Author author = clientHelper.parseAndValidateAuthor(body.getList(2));
 		String text = body.getOptionalString(3);
+		long timer = NO_AUTO_DELETE_TIMER;
+		if (body.size() == 5) timer = body.getLong(4, NO_AUTO_DELETE_TIMER);
 		return new RequestMessage(m.getId(), m.getGroupId(),
-				m.getTimestamp(), previousMessageId, author, text);
+				m.getTimestamp(), previousMessageId, author, text, timer);
 	}
 
 	@Override
@@ -92,9 +97,11 @@ class MessageParserImpl implements MessageParser {
 		long acceptTimestamp = body.getLong(4);
 		Map<TransportId, TransportProperties> transportProperties = clientHelper
 				.parseAndValidateTransportPropertiesMap(body.getDictionary(5));
+		long timer = NO_AUTO_DELETE_TIMER;
+		if (body.size() == 7) timer = body.getLong(6, NO_AUTO_DELETE_TIMER);
 		return new AcceptMessage(m.getId(), m.getGroupId(), m.getTimestamp(),
 				previousMessageId, sessionId, ephemeralPublicKey,
-				acceptTimestamp, transportProperties);
+				acceptTimestamp, transportProperties, timer);
 	}
 
 	@Override
@@ -104,8 +111,10 @@ class MessageParserImpl implements MessageParser {
 		byte[] previousMsgBytes = body.getOptionalRaw(2);
 		MessageId previousMessageId = (previousMsgBytes == null ? null :
 				new MessageId(previousMsgBytes));
+		long timer = NO_AUTO_DELETE_TIMER;
+		if (body.size() == 4) timer = body.getLong(3, NO_AUTO_DELETE_TIMER);
 		return new DeclineMessage(m.getId(), m.getGroupId(), m.getTimestamp(),
-				previousMessageId, sessionId);
+				previousMessageId, sessionId, timer);
 	}
 
 	@Override

briar-core/src/main/java/org/briarproject/briar/introduction/RequestMessage.java

@@ -18,8 +18,9 @@ class RequestMessage extends AbstractIntroductionMessage {
 
 	RequestMessage(MessageId messageId, GroupId groupId, long timestamp,
 			@Nullable MessageId previousMessageId, Author author,
-			@Nullable String text) {
+			@Nullable String text, long autoDeleteTimer) {
-		super(messageId, groupId, timestamp, previousMessageId);
+		super(messageId, groupId, timestamp, previousMessageId,
+				autoDeleteTimer);
 		this.author = author;
 		this.text = text;
 	}

briar-core/src/main/java/org/briarproject/briar/messaging/PrivateMessageValidator.java

@@ -28,6 +28,7 @@ import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.MIN_AU
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_BODY_LENGTH;
 import static org.briarproject.bramble.api.transport.TransportConstants.MAX_CLOCK_DIFFERENCE;
 import static org.briarproject.bramble.util.ValidationUtils.checkLength;
+import static org.briarproject.bramble.util.ValidationUtils.checkRange;
 import static org.briarproject.bramble.util.ValidationUtils.checkSize;
 import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_ATTACHMENTS_PER_MESSAGE;
 import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_CONTENT_TYPE_BYTES;
@@ -136,10 +137,10 @@ class PrivateMessageValidator implements MessageValidator {
 			checkLength(contentType, 1, MAX_CONTENT_TYPE_BYTES);
 		}
 		Long timer = null;
-		if (body.size() == 4) timer = body.getOptionalLong(3);
+		if (body.size() == 4) {
-		if (timer != null && (timer < MIN_AUTO_DELETE_TIMER_MS ||
+			timer = body.getOptionalLong(3);
-				timer > MAX_AUTO_DELETE_TIMER_MS)) {
+			checkRange(timer, MIN_AUTO_DELETE_TIMER_MS,
-			throw new FormatException();
+					MAX_AUTO_DELETE_TIMER_MS);
 		}
 		// Return the metadata
 		BdfDictionary meta = new BdfDictionary();

briar-core/src/test/java/org/briarproject/briar/introduction/IntroductionIntegrationTest.java

@@ -45,6 +45,7 @@ import java.util.Map;
 import java.util.Set;
 
 import static java.util.Collections.emptySet;
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
 import static org.briarproject.bramble.test.TestPluginConfigModule.SIMPLEX_TRANSPORT_ID;
 import static org.briarproject.bramble.test.TestUtils.getAgreementPublicKey;
 import static org.briarproject.bramble.test.TestUtils.getSecretKey;
@@ -1114,7 +1115,7 @@ public class IntroductionIntegrationTest
 						m.getTimestamp(), m.getPreviousMessageId(),
 						m.getSessionId(), m.getEphemeralPublicKey(),
 						m.getAcceptTimestamp(),
-						getTransportPropertiesMap(2))
+						getTransportPropertiesMap(2), NO_AUTO_DELETE_TIMER)
 		);
 	}
 
@@ -1125,7 +1126,7 @@ public class IntroductionIntegrationTest
 						m.getTimestamp(), m.getPreviousMessageId(),
 						m.getSessionId(), m.getEphemeralPublicKey(),
 						clock.currentTimeMillis(),
-						m.getTransportProperties())
+						m.getTransportProperties(), NO_AUTO_DELETE_TIMER)
 		);
 	}
 
@@ -1135,7 +1136,8 @@ public class IntroductionIntegrationTest
 				m -> new AcceptMessage(m.getMessageId(), m.getGroupId(),
 						m.getTimestamp(), m.getPreviousMessageId(),
 						m.getSessionId(), getAgreementPublicKey(),
-						m.getAcceptTimestamp(), m.getTransportProperties())
+						m.getAcceptTimestamp(), m.getTransportProperties(),
+						NO_AUTO_DELETE_TIMER)
 		);
 	}
 
@@ -1155,10 +1157,12 @@ public class IntroductionIntegrationTest
 
 		// introducer can not yet remove messages
 		assertFalse(deleteAllMessages1From0().allDeleted());
-		assertTrue(deleteAllMessages1From0().hasIntroductionSessionInProgress());
+		assertTrue(
+				deleteAllMessages1From0().hasIntroductionSessionInProgress());
 		// introducee1 can not yet remove messages
 		assertFalse(deleteAllMessages0From1().allDeleted());
-		assertTrue(deleteAllMessages0From1().hasIntroductionSessionInProgress());
+		assertTrue(
+				deleteAllMessages0From1().hasIntroductionSessionInProgress());
 
 		// sync second REQUEST message
 		sync0To2(1, true);
@@ -1166,10 +1170,12 @@ public class IntroductionIntegrationTest
 
 		// introducer can not yet remove messages
 		assertFalse(deleteAllMessages2From0().allDeleted());
-		assertTrue(deleteAllMessages2From0().hasIntroductionSessionInProgress());
+		assertTrue(
+				deleteAllMessages2From0().hasIntroductionSessionInProgress());
 		// introducee2 can not yet remove messages
 		assertFalse(deleteAllMessages0From2().allDeleted());
-		assertTrue(deleteAllMessages0From2().hasIntroductionSessionInProgress());
+		assertTrue(
+				deleteAllMessages0From2().hasIntroductionSessionInProgress());
 
 		// sync first ACCEPT message
 		sync1To0(1, true);
@@ -1177,7 +1183,8 @@ public class IntroductionIntegrationTest
 
 		// introducer can not yet remove messages
 		assertFalse(deleteAllMessages1From0().allDeleted());
-		assertTrue(deleteAllMessages1From0().hasIntroductionSessionInProgress());
+		assertTrue(
+				deleteAllMessages1From0().hasIntroductionSessionInProgress());
 
 		// sync second ACCEPT message
 		sync2To0(1, true);
@@ -1185,7 +1192,8 @@ public class IntroductionIntegrationTest
 
 		// introducer can not yet remove messages
 		assertFalse(deleteAllMessages2From0().allDeleted());
-		assertTrue(deleteAllMessages2From0().hasIntroductionSessionInProgress());
+		assertTrue(
+				deleteAllMessages2From0().hasIntroductionSessionInProgress());
 
 		// sync forwarded ACCEPT messages to introducees
 		sync0To1(1, true);
@@ -1193,10 +1201,12 @@ public class IntroductionIntegrationTest
 
 		// introducee1 can not yet remove messages
 		assertFalse(deleteAllMessages0From1().allDeleted());
-		assertTrue(deleteAllMessages0From1().hasIntroductionSessionInProgress());
+		assertTrue(
+				deleteAllMessages0From1().hasIntroductionSessionInProgress());
 		// introducee2 can not yet remove messages
 		assertFalse(deleteAllMessages0From2().allDeleted());
-		assertTrue(deleteAllMessages0From2().hasIntroductionSessionInProgress());
+		assertTrue(
+				deleteAllMessages0From2().hasIntroductionSessionInProgress());
 
 		// sync first AUTH and its forward
 		sync1To0(1, true);
@@ -1204,12 +1214,15 @@ public class IntroductionIntegrationTest
 
 		// introducer can not yet remove messages
 		assertFalse(deleteAllMessages1From0().allDeleted());
-		assertTrue(deleteAllMessages1From0().hasIntroductionSessionInProgress());
+		assertTrue(
+				deleteAllMessages1From0().hasIntroductionSessionInProgress());
 		assertFalse(deleteAllMessages2From0().allDeleted());
-		assertTrue(deleteAllMessages2From0().hasIntroductionSessionInProgress());
+		assertTrue(
+				deleteAllMessages2From0().hasIntroductionSessionInProgress());
 		// introducee2 can not yet remove messages
 		assertFalse(deleteAllMessages0From2().allDeleted());
-		assertTrue(deleteAllMessages0From2().hasIntroductionSessionInProgress());
+		assertTrue(
+				deleteAllMessages0From2().hasIntroductionSessionInProgress());
 
 		// sync second AUTH and its forward as well as the following ACTIVATE
 		sync2To0(2, true);
@@ -1217,12 +1230,15 @@ public class IntroductionIntegrationTest
 
 		// introducer can not yet remove messages
 		assertFalse(deleteAllMessages1From0().allDeleted());
-		assertTrue(deleteAllMessages1From0().hasIntroductionSessionInProgress());
+		assertTrue(
+				deleteAllMessages1From0().hasIntroductionSessionInProgress());
 		assertFalse(deleteAllMessages2From0().allDeleted());
-		assertTrue(deleteAllMessages2From0().hasIntroductionSessionInProgress());
+		assertTrue(
+				deleteAllMessages2From0().hasIntroductionSessionInProgress());
 		// introducee1 can not yet remove messages
 		assertFalse(deleteAllMessages0From1().allDeleted());
-		assertTrue(deleteAllMessages0From1().hasIntroductionSessionInProgress());
+		assertTrue(
+				deleteAllMessages0From1().hasIntroductionSessionInProgress());
 
 		// sync second ACTIVATE and its forward
 		sync1To0(1, true);
@@ -1458,14 +1474,16 @@ public class IntroductionIntegrationTest
 		sendAcks(c1, c0, contactId0From1, 1);
 		assertTrue(deleteAllMessages1From0().allDeleted());
 		assertEquals(0, getMessages1From0().size());
-		assertTrue(deleteAllMessages1From0().allDeleted());  // a second time nothing happens
+		assertTrue(deleteAllMessages1From0()
+				.allDeleted());  // a second time nothing happens
 
 		// introducer can remove messages after getting ACK from introducee2
 		// if this succeeds, we still had the session object after delete above
 		sendAcks(c2, c0, contactId0From2, 1);
 		assertTrue(deleteAllMessages2From0().allDeleted());
 		assertEquals(0, getMessages2From0().size());
-		assertTrue(deleteAllMessages2From0().allDeleted());  // a second time nothing happens
+		assertTrue(deleteAllMessages2From0()
+				.allDeleted());  // a second time nothing happens
 
 		// no one should have aborted
 		assertFalse(listener0.aborted);
@@ -1489,7 +1507,8 @@ public class IntroductionIntegrationTest
 		Set<MessageId> toDelete1 = new HashSet<>();
 		toDelete1.add(messageId1);
 		assertFalse(deleteMessages1From0(toDelete1).allDeleted());
-		assertTrue(deleteMessages1From0(toDelete1).hasIntroductionSessionInProgress());
+		assertTrue(deleteMessages1From0(toDelete1)
+				.hasIntroductionSessionInProgress());
 
 		// deleting the introduction for introducee2 will fail as well
 		Collection<ConversationMessageHeader> m2From0 = getMessages2From0();
@@ -1498,7 +1517,8 @@ public class IntroductionIntegrationTest
 		Set<MessageId> toDelete2 = new HashSet<>();
 		toDelete2.add(messageId2);
 		assertFalse(deleteMessages2From0(toDelete2).allDeleted());
-		assertTrue(deleteMessages2From0(toDelete2).hasIntroductionSessionInProgress());
+		assertTrue(deleteMessages2From0(toDelete2)
+				.hasIntroductionSessionInProgress());
 
 		// sync REQUEST messages
 		sync0To1(1, true);
@@ -1508,9 +1528,11 @@ public class IntroductionIntegrationTest
 
 		// deleting introduction fails, because responses did not arrive
 		assertFalse(deleteMessages0From1(toDelete1).allDeleted());
-		assertTrue(deleteMessages0From1(toDelete1).hasIntroductionSessionInProgress());
+		assertTrue(deleteMessages0From1(toDelete1)
+				.hasIntroductionSessionInProgress());
 		assertFalse(deleteMessages0From2(toDelete2).allDeleted());
-		assertTrue(deleteMessages0From2(toDelete2).hasIntroductionSessionInProgress());
+		assertTrue(deleteMessages0From2(toDelete2)
+				.hasIntroductionSessionInProgress());
 
 		// remember response of introducee1 for future deletion
 		Collection<ConversationMessageHeader> m0From1 = getMessages0From1();
@@ -1570,7 +1592,8 @@ public class IntroductionIntegrationTest
 		// deleting introduction fails for introducee 2,
 		// because response is not yet selected for deletion
 		assertFalse(deleteMessages0From2(toDelete2).allDeleted());
-		assertTrue(deleteMessages0From2(toDelete2).hasNotAllIntroductionSelected());
+		assertTrue(deleteMessages0From2(toDelete2)
+				.hasNotAllIntroductionSelected());
 
 		// add response to be deleted as well
 		toDelete2.add(response2);
@@ -1588,7 +1611,8 @@ public class IntroductionIntegrationTest
 		// deleting introduction fails for introducee 1,
 		// because response is not yet selected for deletion
 		assertFalse(deleteMessages0From1(toDelete1).allDeleted());
-		assertTrue(deleteMessages0From1(toDelete1).hasNotAllIntroductionSelected());
+		assertTrue(deleteMessages0From1(toDelete1)
+				.hasNotAllIntroductionSelected());
 
 		// add response to be deleted as well
 		toDelete1.add(response1);
@@ -1730,7 +1754,8 @@ public class IntroductionIntegrationTest
 
 	@MethodsNotNullByDefault
 	@ParametersNotNullByDefault
-	private abstract class IntroductionListener implements EventListener {
+	private abstract static class IntroductionListener
+			implements EventListener {
 
 		volatile boolean aborted = false;
 		volatile Event latestEvent;

briar-core/src/test/java/org/briarproject/briar/introduction/IntroductionValidatorTest.java

@@ -6,20 +6,29 @@ import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.data.BdfDictionary;
 import org.briarproject.bramble.api.data.BdfEntry;
 import org.briarproject.bramble.api.data.BdfList;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.test.ValidatorTestCase;
 import org.briarproject.briar.api.client.SessionId;
 import org.jmock.Expectations;
 import org.junit.Test;
 
+import java.util.Map;
+
 import javax.annotation.Nullable;
 
+import static java.util.Collections.singletonMap;
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.MAX_AUTO_DELETE_TIMER_MS;
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.MIN_AUTO_DELETE_TIMER_MS;
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
 import static org.briarproject.bramble.api.crypto.CryptoConstants.MAC_BYTES;
 import static org.briarproject.bramble.api.crypto.CryptoConstants.MAX_AGREEMENT_PUBLIC_KEY_BYTES;
 import static org.briarproject.bramble.api.crypto.CryptoConstants.MAX_SIGNATURE_BYTES;
 import static org.briarproject.bramble.test.TestUtils.getAgreementPublicKey;
 import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
 import static org.briarproject.bramble.test.TestUtils.getRandomId;
+import static org.briarproject.bramble.test.TestUtils.getTransportId;
 import static org.briarproject.bramble.util.StringUtils.getRandomString;
 import static org.briarproject.briar.api.introduction.IntroductionConstants.MAX_INTRODUCTION_TEXT_LENGTH;
 import static org.briarproject.briar.introduction.MessageType.ABORT;
@@ -44,9 +53,12 @@ public class IntroductionValidatorTest extends ValidatorTestCase {
 	private final BdfDictionary meta = new BdfDictionary();
 	private final PublicKey ephemeralPublicKey = getAgreementPublicKey();
 	private final long acceptTimestamp = 42;
+	private final TransportId transportId = getTransportId();
 	private final BdfDictionary transportProperties = BdfDictionary.of(
-			new BdfEntry("transportId",  new BdfDictionary())
+			new BdfEntry(transportId.getString(), new BdfDictionary())
 	);
+	private final Map<TransportId, TransportProperties> transportPropertiesMap =
+			singletonMap(transportId, new TransportProperties());
 	private final byte[] mac = getRandomBytes(MAC_BYTES);
 	private final byte[] signature = getRandomBytes(MAX_SIGNATURE_BYTES);
 
@@ -60,7 +72,7 @@ public class IntroductionValidatorTest extends ValidatorTestCase {
 				authorList, text);
 
 		expectParseAuthor(authorList, author);
-		expectEncodeRequestMetadata();
+		expectEncodeRequestMetadata(NO_AUTO_DELETE_TIMER);
 		BdfMessageContext messageContext =
 				validator.validateMessage(message, group, body);
 
@@ -72,7 +84,7 @@ public class IntroductionValidatorTest extends ValidatorTestCase {
 		BdfList body = BdfList.of(REQUEST.getValue(), null, authorList, text);
 
 		expectParseAuthor(authorList, author);
-		expectEncodeRequestMetadata();
+		expectEncodeRequestMetadata(NO_AUTO_DELETE_TIMER);
 		BdfMessageContext messageContext =
 				validator.validateMessage(message, group, body);
 
@@ -84,13 +96,42 @@ public class IntroductionValidatorTest extends ValidatorTestCase {
 		BdfList body = BdfList.of(REQUEST.getValue(), null, authorList, null);
 
 		expectParseAuthor(authorList, author);
-		expectEncodeRequestMetadata();
+		expectEncodeRequestMetadata(NO_AUTO_DELETE_TIMER);
 		BdfMessageContext messageContext =
 				validator.validateMessage(message, group, body);
 
 		assertExpectedContext(messageContext, null);
 	}
 
+	@Test
+	public void testAcceptsRequestWithNullAutoDeleteTimer() throws Exception {
+		testAcceptsRequestWithAutoDeleteTimer(null);
+	}
+
+	@Test
+	public void testAcceptsRequestWithMinAutoDeleteTimer() throws Exception {
+		testAcceptsRequestWithAutoDeleteTimer(MIN_AUTO_DELETE_TIMER_MS);
+	}
+
+	@Test
+	public void testAcceptsRequestWithMaxAutoDeleteTimer() throws Exception {
+		testAcceptsRequestWithAutoDeleteTimer(MAX_AUTO_DELETE_TIMER_MS);
+	}
+
+	private void testAcceptsRequestWithAutoDeleteTimer(@Nullable Long timer)
+			throws Exception {
+		BdfList body = BdfList.of(REQUEST.getValue(), previousMsgId.getBytes(),
+				authorList, text, timer);
+
+		expectParseAuthor(authorList, author);
+		long autoDeleteTimer = timer == null ? NO_AUTO_DELETE_TIMER : timer;
+		expectEncodeRequestMetadata(autoDeleteTimer);
+		BdfMessageContext messageContext =
+				validator.validateMessage(message, group, body);
+
+		assertExpectedContext(messageContext, previousMsgId);
+	}
+
 	@Test(expected = FormatException.class)
 	public void testRejectsTooShortBodyForRequest() throws Exception {
 		BdfList body = BdfList.of(REQUEST.getValue(), null, authorList);
@@ -99,8 +140,8 @@ public class IntroductionValidatorTest extends ValidatorTestCase {
 
 	@Test(expected = FormatException.class)
 	public void testRejectsTooLongBodyForRequest() throws Exception {
-		BdfList body =
+		BdfList body = BdfList.of(REQUEST.getValue(), null, authorList, text,
-				BdfList.of(REQUEST.getValue(), null, authorList, text, null);
+				null, null);
 		validator.validateMessage(message, group, body);
 	}
 
@@ -119,6 +160,32 @@ public class IntroductionValidatorTest extends ValidatorTestCase {
 		validator.validateMessage(message, group, body);
 	}
 
+	@Test(expected = FormatException.class)
+	public void testRejectsRequestWithNonLongAutoDeleteTimer()
+			throws Exception {
+		BdfList body = BdfList.of(REQUEST.getValue(), previousMsgId.getBytes(),
+				authorList, text, "foo");
+		expectParseAuthor(authorList, author);
+		validator.validateMessage(message, group, body);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsRequestWithTooSmallAutoDeleteTimer()
+			throws Exception {
+		BdfList body = BdfList.of(REQUEST.getValue(), previousMsgId.getBytes(),
+				authorList, text, MIN_AUTO_DELETE_TIMER_MS - 1);
+		expectParseAuthor(authorList, author);
+		validator.validateMessage(message, group, body);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsRequestWithTooBigAutoDeleteTimer() throws Exception {
+		BdfList body = BdfList.of(REQUEST.getValue(), previousMsgId.getBytes(),
+				authorList, text, MAX_AUTO_DELETE_TIMER_MS + 1);
+		expectParseAuthor(authorList, author);
+		validator.validateMessage(message, group, body);
+	}
+
 	//
 	// Introduction ACCEPT
 	//
@@ -129,11 +196,38 @@ public class IntroductionValidatorTest extends ValidatorTestCase {
 				previousMsgId.getBytes(), ephemeralPublicKey.getEncoded(),
 				acceptTimestamp, transportProperties);
 		expectParsePublicKey();
-		context.checking(new Expectations() {{
+		expectParseTransportProperties();
-			oneOf(clientHelper).parseAndValidateTransportPropertiesMap(
+		expectEncodeMetadata(ACCEPT, NO_AUTO_DELETE_TIMER);
-					transportProperties);
+		BdfMessageContext messageContext =
-		}});
+				validator.validateMessage(message, group, body);
-		expectEncodeMetadata(ACCEPT);
+
+		assertExpectedContext(messageContext, previousMsgId);
+	}
+
+	@Test
+	public void testAcceptsAcceptWithNullAutoDeleteTimer() throws Exception {
+		testAcceptsAcceptWithAutoDeleteTimer(null);
+	}
+
+	@Test
+	public void testAcceptsAcceptWithMinAutoDeleteTimer() throws Exception {
+		testAcceptsAcceptWithAutoDeleteTimer(MIN_AUTO_DELETE_TIMER_MS);
+	}
+
+	@Test
+	public void testAcceptsAcceptWithMaxAutoDeleteTimer() throws Exception {
+		testAcceptsAcceptWithAutoDeleteTimer(MAX_AUTO_DELETE_TIMER_MS);
+	}
+
+	private void testAcceptsAcceptWithAutoDeleteTimer(@Nullable Long timer)
+			throws Exception {
+		BdfList body = BdfList.of(ACCEPT.getValue(), sessionId.getBytes(),
+				previousMsgId.getBytes(), ephemeralPublicKey.getEncoded(),
+				acceptTimestamp, transportProperties, timer);
+		expectParsePublicKey();
+		expectParseTransportProperties();
+		long autoDeleteTimer = timer == null ? NO_AUTO_DELETE_TIMER : timer;
+		expectEncodeMetadata(ACCEPT, autoDeleteTimer);
 		BdfMessageContext messageContext =
 				validator.validateMessage(message, group, body);
 
@@ -152,7 +246,7 @@ public class IntroductionValidatorTest extends ValidatorTestCase {
 	public void testRejectsTooLongBodyForAccept() throws Exception {
 		BdfList body = BdfList.of(ACCEPT.getValue(), sessionId.getBytes(),
 				previousMsgId.getBytes(), ephemeralPublicKey.getEncoded(),
-				acceptTimestamp, transportProperties, null);
+				acceptTimestamp, transportProperties, null, null);
 		validator.validateMessage(message, group, body);
 	}
 
@@ -200,6 +294,40 @@ public class IntroductionValidatorTest extends ValidatorTestCase {
 		validator.validateMessage(message, group, body);
 	}
 
+	@Test(expected = FormatException.class)
+	public void testRejectsAcceptWithNonLongAutoDeleteTimer()
+			throws Exception {
+		BdfList body = BdfList.of(ACCEPT.getValue(), sessionId.getBytes(),
+				previousMsgId.getBytes(), ephemeralPublicKey.getEncoded(),
+				acceptTimestamp, transportProperties, "foo");
+		expectParsePublicKey();
+		expectParseTransportProperties();
+		validator.validateMessage(message, group, body);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsAcceptWithTooSmallAutoDeleteTimer()
+			throws Exception {
+		BdfList body = BdfList.of(ACCEPT.getValue(), sessionId.getBytes(),
+				previousMsgId.getBytes(), ephemeralPublicKey.getEncoded(),
+				acceptTimestamp, transportProperties,
+				MIN_AUTO_DELETE_TIMER_MS - 1);
+		expectParsePublicKey();
+		expectParseTransportProperties();
+		validator.validateMessage(message, group, body);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsAcceptWithTooBigAutoDeleteTimer() throws Exception {
+		BdfList body = BdfList.of(ACCEPT.getValue(), sessionId.getBytes(),
+				previousMsgId.getBytes(), ephemeralPublicKey.getEncoded(),
+				acceptTimestamp, transportProperties,
+				MAX_AUTO_DELETE_TIMER_MS + 1);
+		expectParsePublicKey();
+		expectParseTransportProperties();
+		validator.validateMessage(message, group, body);
+	}
+
 	//
 	// Introduction DECLINE
 	//
@@ -209,7 +337,35 @@ public class IntroductionValidatorTest extends ValidatorTestCase {
 		BdfList body = BdfList.of(DECLINE.getValue(), sessionId.getBytes(),
 				previousMsgId.getBytes());
 
-		expectEncodeMetadata(DECLINE);
+		expectEncodeMetadata(DECLINE, NO_AUTO_DELETE_TIMER);
+		BdfMessageContext messageContext =
+				validator.validateMessage(message, group, body);
+
+		assertExpectedContext(messageContext, previousMsgId);
+	}
+
+	@Test
+	public void testAcceptsDeclineWithNullAutoDeleteTimer() throws Exception {
+		testAcceptsDeclineWithAutoDeleteTimer(null);
+	}
+
+	@Test
+	public void testAcceptsDeclineWithMinAutoDeleteTimer() throws Exception {
+		testAcceptsDeclineWithAutoDeleteTimer(MIN_AUTO_DELETE_TIMER_MS);
+	}
+
+	@Test
+	public void testAcceptsDeclineWithMaxAutoDeleteTimer() throws Exception {
+		testAcceptsDeclineWithAutoDeleteTimer(MAX_AUTO_DELETE_TIMER_MS);
+	}
+
+	private void testAcceptsDeclineWithAutoDeleteTimer(@Nullable Long timer)
+			throws Exception {
+		BdfList body = BdfList.of(DECLINE.getValue(), sessionId.getBytes(),
+				previousMsgId.getBytes(), timer);
+
+		long autoDeleteTimer = timer == null ? NO_AUTO_DELETE_TIMER : timer;
+		expectEncodeMetadata(DECLINE, autoDeleteTimer);
 		BdfMessageContext messageContext =
 				validator.validateMessage(message, group, body);
 
@@ -225,7 +381,7 @@ public class IntroductionValidatorTest extends ValidatorTestCase {
 	@Test(expected = FormatException.class)
 	public void testRejectsTooLongBodyForDecline() throws Exception {
 		BdfList body = BdfList.of(DECLINE.getValue(), sessionId.getBytes(),
-				previousMsgId.getBytes(), null);
+				previousMsgId.getBytes(), null, null);
 		validator.validateMessage(message, group, body);
 	}
 
@@ -242,6 +398,28 @@ public class IntroductionValidatorTest extends ValidatorTestCase {
 		validator.validateMessage(message, group, body);
 	}
 
+	@Test(expected = FormatException.class)
+	public void testRejectsNonLongAutoDeleteTimerForDecline() throws Exception {
+		BdfList body = BdfList.of(DECLINE.getValue(), sessionId.getBytes(),
+				previousMsgId.getBytes(), "foo");
+		validator.validateMessage(message, group, body);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsTooSmallAutoDeleteTimerForDecline()
+			throws Exception {
+		BdfList body = BdfList.of(DECLINE.getValue(), sessionId.getBytes(),
+				previousMsgId.getBytes(), MIN_AUTO_DELETE_TIMER_MS - 1);
+		validator.validateMessage(message, group, body);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsTooBigAutoDeleteTimerForDecline() throws Exception {
+		BdfList body = BdfList.of(DECLINE.getValue(), sessionId.getBytes(),
+				previousMsgId.getBytes(), MAX_AUTO_DELETE_TIMER_MS + 1);
+		validator.validateMessage(message, group, body);
+	}
+
 	//
 	// Introduction AUTH
 	//
@@ -251,7 +429,7 @@ public class IntroductionValidatorTest extends ValidatorTestCase {
 		BdfList body = BdfList.of(AUTH.getValue(), sessionId.getBytes(),
 				previousMsgId.getBytes(), mac, signature);
 
-		expectEncodeMetadata(AUTH);
+		expectEncodeMetadata(AUTH, NO_AUTO_DELETE_TIMER);
 		BdfMessageContext messageContext =
 				validator.validateMessage(message, group, body);
 
@@ -340,7 +518,7 @@ public class IntroductionValidatorTest extends ValidatorTestCase {
 		BdfList body = BdfList.of(ACTIVATE.getValue(), sessionId.getBytes(),
 				previousMsgId.getBytes(), mac);
 
-		expectEncodeMetadata(ACTIVATE);
+		expectEncodeMetadata(ACTIVATE, NO_AUTO_DELETE_TIMER);
 		BdfMessageContext messageContext =
 				validator.validateMessage(message, group, body);
 
@@ -398,7 +576,7 @@ public class IntroductionValidatorTest extends ValidatorTestCase {
 		BdfList body = BdfList.of(ABORT.getValue(), sessionId.getBytes(),
 				previousMsgId.getBytes());
 
-		expectEncodeMetadata(ABORT);
+		expectEncodeMetadata(ABORT, NO_AUTO_DELETE_TIMER);
 		BdfMessageContext messageContext =
 				validator.validateMessage(message, group, body);
 
@@ -442,17 +620,28 @@ public class IntroductionValidatorTest extends ValidatorTestCase {
 			will(returnValue(ephemeralPublicKey));
 		}});
 	}
-	private void expectEncodeRequestMetadata() {
+
+	private void expectParseTransportProperties() throws Exception {
 		context.checking(new Expectations() {{
-			oneOf(messageEncoder).encodeRequestMetadata(message.getTimestamp());
+			oneOf(clientHelper).parseAndValidateTransportPropertiesMap(
+					transportProperties);
+			will(returnValue(transportPropertiesMap));
+		}});
+	}
+
+	private void expectEncodeRequestMetadata(long autoDeleteTimer) {
+		context.checking(new Expectations() {{
+			oneOf(messageEncoder).encodeRequestMetadata(message.getTimestamp(),
+					autoDeleteTimer);
 			will(returnValue(meta));
 		}});
 	}
 
-	private void expectEncodeMetadata(MessageType type) {
+	private void expectEncodeMetadata(MessageType type, long autoDeleteTimer) {
 		context.checking(new Expectations() {{
 			oneOf(messageEncoder).encodeMetadata(type, sessionId,
-					message.getTimestamp(), false, false, false);
+					message.getTimestamp(), false, false, false,
+					autoDeleteTimer);
 			will(returnValue(meta));
 		}});
 	}

briar-core/src/test/java/org/briarproject/briar/introduction/MessageEncoderParserIntegrationTest.java

@@ -23,6 +23,9 @@ import java.util.Map;
 
 import javax.inject.Inject;
 
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.MAX_AUTO_DELETE_TIMER_MS;
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.MIN_AUTO_DELETE_TIMER_MS;
+import static org.briarproject.bramble.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
 import static org.briarproject.bramble.api.crypto.CryptoConstants.MAC_BYTES;
 import static org.briarproject.bramble.api.crypto.CryptoConstants.MAX_SIGNATURE_BYTES;
 import static org.briarproject.bramble.test.TestUtils.getAgreementPublicKey;
@@ -87,8 +90,8 @@ public class MessageEncoderParserIntegrationTest extends BrambleTestCase {
 
 	@Test
 	public void testRequestMessageMetadata() throws FormatException {
-		BdfDictionary d = messageEncoder
+		BdfDictionary d = messageEncoder.encodeRequestMetadata(timestamp,
-				.encodeRequestMetadata(timestamp);
+				MIN_AUTO_DELETE_TIMER_MS);
 		MessageMetadata meta = messageParser.parseMetadata(d);
 
 		assertEquals(REQUEST, meta.getMessageType());
@@ -98,13 +101,13 @@ public class MessageEncoderParserIntegrationTest extends BrambleTestCase {
 		assertFalse(meta.isRead());
 		assertFalse(meta.isVisibleInConversation());
 		assertFalse(meta.isAvailableToAnswer());
+		assertEquals(MIN_AUTO_DELETE_TIMER_MS, meta.getAutoDeleteTimer());
 	}
 
 	@Test
 	public void testMessageMetadata() throws FormatException {
-		BdfDictionary d = messageEncoder
+		BdfDictionary d = messageEncoder.encodeMetadata(ABORT, sessionId,
-				.encodeMetadata(ABORT, sessionId, timestamp, false, true,
+				timestamp, false, true, false, MAX_AUTO_DELETE_TIMER_MS);
-						false);
 		MessageMetadata meta = messageParser.parseMetadata(d);
 
 		assertEquals(ABORT, meta.getMessageType());
@@ -114,6 +117,7 @@ public class MessageEncoderParserIntegrationTest extends BrambleTestCase {
 		assertTrue(meta.isRead());
 		assertFalse(meta.isVisibleInConversation());
 		assertFalse(meta.isAvailableToAnswer());
+		assertEquals(MAX_AUTO_DELETE_TIMER_MS, meta.getAutoDeleteTimer());
 	}
 
 	@Test
@@ -131,6 +135,42 @@ public class MessageEncoderParserIntegrationTest extends BrambleTestCase {
 		assertEquals(previousMsgId, rm.getPreviousMessageId());
 		assertEquals(author, rm.getAuthor());
 		assertEquals(text, rm.getText());
+		assertEquals(NO_AUTO_DELETE_TIMER, rm.getAutoDeleteTimer());
+	}
+
+	@Test
+	public void testRequestMessageWithAutoDeleteTimer() throws FormatException {
+		Message m = messageEncoder.encodeRequestMessage(groupId, timestamp,
+				previousMsgId, author, text, MIN_AUTO_DELETE_TIMER_MS);
+		validator.validateMessage(m, group, clientHelper.toList(m));
+		RequestMessage rm =
+				messageParser.parseRequestMessage(m, clientHelper.toList(m));
+
+		assertEquals(m.getId(), rm.getMessageId());
+		assertEquals(m.getGroupId(), rm.getGroupId());
+		assertEquals(m.getTimestamp(), rm.getTimestamp());
+		assertEquals(previousMsgId, rm.getPreviousMessageId());
+		assertEquals(author, rm.getAuthor());
+		assertEquals(text, rm.getText());
+		assertEquals(MIN_AUTO_DELETE_TIMER_MS, rm.getAutoDeleteTimer());
+	}
+
+	@Test
+	public void testRequestMessageWithoutAutoDeleteTimer()
+			throws FormatException {
+		Message m = messageEncoder.encodeRequestMessage(groupId, timestamp,
+				previousMsgId, author, text, NO_AUTO_DELETE_TIMER);
+		validator.validateMessage(m, group, clientHelper.toList(m));
+		RequestMessage rm =
+				messageParser.parseRequestMessage(m, clientHelper.toList(m));
+
+		assertEquals(m.getId(), rm.getMessageId());
+		assertEquals(m.getGroupId(), rm.getGroupId());
+		assertEquals(m.getTimestamp(), rm.getTimestamp());
+		assertEquals(previousMsgId, rm.getPreviousMessageId());
+		assertEquals(author, rm.getAuthor());
+		assertEquals(text, rm.getText());
+		assertEquals(NO_AUTO_DELETE_TIMER, rm.getAutoDeleteTimer());
 	}
 
 	@Test
@@ -142,6 +182,7 @@ public class MessageEncoderParserIntegrationTest extends BrambleTestCase {
 				messageParser.parseRequestMessage(m, clientHelper.toList(m));
 
 		assertNull(rm.getPreviousMessageId());
+		assertEquals(NO_AUTO_DELETE_TIMER, rm.getAutoDeleteTimer());
 	}
 
 	@Test
@@ -154,6 +195,7 @@ public class MessageEncoderParserIntegrationTest extends BrambleTestCase {
 				messageParser.parseRequestMessage(m, clientHelper.toList(m));
 
 		assertNull(rm.getText());
+		assertEquals(NO_AUTO_DELETE_TIMER, rm.getAutoDeleteTimer());
 	}
 
 	@Test
@@ -179,6 +221,57 @@ public class MessageEncoderParserIntegrationTest extends BrambleTestCase {
 				am.getEphemeralPublicKey().getEncoded());
 		assertEquals(acceptTimestamp, am.getAcceptTimestamp());
 		assertEquals(transportProperties, am.getTransportProperties());
+		assertEquals(NO_AUTO_DELETE_TIMER, am.getAutoDeleteTimer());
+	}
+
+	@Test
+	public void testAcceptMessageWithAutoDeleteTimer() throws Exception {
+		Map<TransportId, TransportProperties> transportProperties =
+				getTransportPropertiesMap(2);
+
+		long acceptTimestamp = 1337L;
+		Message m = messageEncoder.encodeAcceptMessage(groupId, timestamp,
+				previousMsgId, sessionId, ephemeralPublicKey,
+				acceptTimestamp, transportProperties, MAX_AUTO_DELETE_TIMER_MS);
+		validator.validateMessage(m, group, clientHelper.toList(m));
+		AcceptMessage am =
+				messageParser.parseAcceptMessage(m, clientHelper.toList(m));
+
+		assertEquals(m.getId(), am.getMessageId());
+		assertEquals(m.getGroupId(), am.getGroupId());
+		assertEquals(m.getTimestamp(), am.getTimestamp());
+		assertEquals(previousMsgId, am.getPreviousMessageId());
+		assertEquals(sessionId, am.getSessionId());
+		assertArrayEquals(ephemeralPublicKey.getEncoded(),
+				am.getEphemeralPublicKey().getEncoded());
+		assertEquals(acceptTimestamp, am.getAcceptTimestamp());
+		assertEquals(transportProperties, am.getTransportProperties());
+		assertEquals(MAX_AUTO_DELETE_TIMER_MS, am.getAutoDeleteTimer());
+	}
+
+	@Test
+	public void testAcceptMessageWithoutAutoDeleteTimer() throws Exception {
+		Map<TransportId, TransportProperties> transportProperties =
+				getTransportPropertiesMap(2);
+
+		long acceptTimestamp = 1337L;
+		Message m = messageEncoder.encodeAcceptMessage(groupId, timestamp,
+				previousMsgId, sessionId, ephemeralPublicKey,
+				acceptTimestamp, transportProperties, NO_AUTO_DELETE_TIMER);
+		validator.validateMessage(m, group, clientHelper.toList(m));
+		AcceptMessage am =
+				messageParser.parseAcceptMessage(m, clientHelper.toList(m));
+
+		assertEquals(m.getId(), am.getMessageId());
+		assertEquals(m.getGroupId(), am.getGroupId());
+		assertEquals(m.getTimestamp(), am.getTimestamp());
+		assertEquals(previousMsgId, am.getPreviousMessageId());
+		assertEquals(sessionId, am.getSessionId());
+		assertArrayEquals(ephemeralPublicKey.getEncoded(),
+				am.getEphemeralPublicKey().getEncoded());
+		assertEquals(acceptTimestamp, am.getAcceptTimestamp());
+		assertEquals(transportProperties, am.getTransportProperties());
+		assertEquals(NO_AUTO_DELETE_TIMER, am.getAutoDeleteTimer());
 	}
 
 	@Test
@@ -195,6 +288,39 @@ public class MessageEncoderParserIntegrationTest extends BrambleTestCase {
 		assertEquals(m.getTimestamp(), dm.getTimestamp());
 		assertEquals(previousMsgId, dm.getPreviousMessageId());
 		assertEquals(sessionId, dm.getSessionId());
+		assertEquals(NO_AUTO_DELETE_TIMER, dm.getAutoDeleteTimer());
+	}
+
+	@Test
+	public void testDeclineMessageWithAutoDeleteTimer() throws Exception {
+		Message m = messageEncoder.encodeDeclineMessage(groupId, timestamp,
+				previousMsgId, sessionId, MIN_AUTO_DELETE_TIMER_MS);
+		validator.validateMessage(m, group, clientHelper.toList(m));
+		DeclineMessage dm =
+				messageParser.parseDeclineMessage(m, clientHelper.toList(m));
+
+		assertEquals(m.getId(), dm.getMessageId());
+		assertEquals(m.getGroupId(), dm.getGroupId());
+		assertEquals(m.getTimestamp(), dm.getTimestamp());
+		assertEquals(previousMsgId, dm.getPreviousMessageId());
+		assertEquals(sessionId, dm.getSessionId());
+		assertEquals(MIN_AUTO_DELETE_TIMER_MS, dm.getAutoDeleteTimer());
+	}
+
+	@Test
+	public void testDeclineMessageWithoutAutoDeleteTimer() throws Exception {
+		Message m = messageEncoder.encodeDeclineMessage(groupId, timestamp,
+				previousMsgId, sessionId, NO_AUTO_DELETE_TIMER);
+		validator.validateMessage(m, group, clientHelper.toList(m));
+		DeclineMessage dm =
+				messageParser.parseDeclineMessage(m, clientHelper.toList(m));
+
+		assertEquals(m.getId(), dm.getMessageId());
+		assertEquals(m.getGroupId(), dm.getGroupId());
+		assertEquals(m.getTimestamp(), dm.getTimestamp());
+		assertEquals(previousMsgId, dm.getPreviousMessageId());
+		assertEquals(sessionId, dm.getSessionId());
+		assertEquals(NO_AUTO_DELETE_TIMER, dm.getAutoDeleteTimer());
 	}
 
 	@Test
@@ -213,6 +339,7 @@ public class MessageEncoderParserIntegrationTest extends BrambleTestCase {
 		assertEquals(sessionId, am.getSessionId());
 		assertArrayEquals(mac, am.getMac());
 		assertArrayEquals(signature, am.getSignature());
+		assertEquals(NO_AUTO_DELETE_TIMER, am.getAutoDeleteTimer());
 	}
 
 	@Test
@@ -230,6 +357,7 @@ public class MessageEncoderParserIntegrationTest extends BrambleTestCase {
 		assertEquals(previousMsgId, am.getPreviousMessageId());
 		assertEquals(sessionId, am.getSessionId());
 		assertArrayEquals(mac, am.getMac());
+		assertEquals(NO_AUTO_DELETE_TIMER, am.getAutoDeleteTimer());
 	}
 
 	@Test
@@ -246,5 +374,6 @@ public class MessageEncoderParserIntegrationTest extends BrambleTestCase {
 		assertEquals(m.getTimestamp(), am.getTimestamp());
 		assertEquals(previousMsgId, am.getPreviousMessageId());
 		assertEquals(sessionId, am.getSessionId());
+		assertEquals(NO_AUTO_DELETE_TIMER, am.getAutoDeleteTimer());
 	}
 }

briar-headless/src/test/java/org/briarproject/briar/headless/event/WebSocketControllerTest.kt

@@ -97,7 +97,8 @@ internal class WebSocketControllerTest : ControllerTest() {
             author,
             text,
             false,
-            AuthorInfo(VERIFIED)
+            AuthorInfo(VERIFIED),
+            NO_AUTO_DELETE_TIMER
         )
         val introductionRequestEvent =
             IntroductionRequestReceivedEvent(introductionRequest, contact.id)

briar-headless/src/test/java/org/briarproject/briar/headless/messaging/MessagingControllerImplTest.kt

@@ -89,7 +89,7 @@ internal class MessagingControllerImplTest : ControllerTest() {
     fun listIntroductionRequest() {
         val request = IntroductionRequest(
             message.id, group.id, timestamp, true, true, true, false, sessionId, author, text,
-            false, AuthorInfo(UNVERIFIED)
+            false, AuthorInfo(UNVERIFIED), NO_AUTO_DELETE_TIMER
         )
 
         expectGetContact()
@@ -330,7 +330,7 @@ internal class MessagingControllerImplTest : ControllerTest() {
     fun testIntroductionRequestWithNullText() {
         val request = IntroductionRequest(
             message.id, group.id, timestamp, true, true, true, false, sessionId, author, null,
-            false, AuthorInfo(VERIFIED)
+            false, AuthorInfo(VERIFIED), NO_AUTO_DELETE_TIMER
         )
         val json = """
             {