Separate the sync layer from its clients. #112

briar-api/src/org/briarproject/api/UniqueId.java

@@ -1,6 +1,7 @@
 package org.briarproject.api;
 
 import java.util.Arrays;
+import java.util.Comparator;
 
 public abstract class UniqueId {
 
@@ -27,4 +28,20 @@ public abstract class UniqueId {
 		if (hashCode == -1) hashCode = Arrays.hashCode(id);
 		return hashCode;
 	}
+
+	public static class IdComparator implements Comparator<UniqueId> {
+
+		public static final IdComparator INSTANCE = new IdComparator();
+
+		@Override
+		public int compare(UniqueId a, UniqueId b) {
+			byte[] aBytes = a.getBytes(), bBytes = b.getBytes();
+			for (int i = 0; i < UniqueId.LENGTH; i++) {
+				int aUnsigned = aBytes[i] & 0xFF, bUnsigned = bBytes[i] & 0xFF;
+				if (aUnsigned < bUnsigned) return -1;
+				if (aUnsigned > bUnsigned) return 1;
+			}
+			return 0;
+		}
+	}
 }

briar-api/src/org/briarproject/api/android/AndroidExecutor.java

@@ -1,7 +1,7 @@
 package org.briarproject.api.android;
 
 import java.util.concurrent.Callable;
-import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
 
 /**
  * Enables background threads to make Android API calls that must be made from
@@ -10,10 +10,11 @@ import java.util.concurrent.ExecutionException;
 public interface AndroidExecutor {
 
 	/**
-	 * Runs the given task on a thread with a message queue and returns the
-	 * result of the task.
+	 * Runs the given task on the main UI thread and returns a Future for
+	 * getting the result.
 	 */
-	<V> V call(Callable<V> c) throws InterruptedException, ExecutionException;
+	<V> Future<V> submit(Callable<V> c);
 
-	void shutdown();
+	/** Runs the given task on the main UI thread. */
+	void execute(Runnable r);
 }

briar-api/src/org/briarproject/api/android/AndroidNotificationManager.java

@@ -1,26 +1,20 @@
 package org.briarproject.api.android;
 
-import org.briarproject.api.contact.ContactId;
 import org.briarproject.api.lifecycle.Service;
 import org.briarproject.api.sync.GroupId;
 
-/**
- * Manages notifications for private messages and group posts. All methods must
- * be called from the Android UI thread.
- */
+/** Manages notifications for private messages and forum posts. */
 public interface AndroidNotificationManager extends Service {
 
-	void showPrivateMessageNotification(ContactId c);
+	void showPrivateMessageNotification(GroupId g);
 
-	void clearPrivateMessageNotification(ContactId c);
-
-	void blockPrivateMessageNotification(ContactId c);
-
-	void unblockPrivateMessageNotification(ContactId c);
+	void clearPrivateMessageNotification(GroupId g);
 
 	void showForumPostNotification(GroupId g);
 
 	void clearForumPostNotification(GroupId g);
 
-	void clearNotifications();
+	void blockNotification(GroupId g);
+
+	void unblockNotification(GroupId g);
 }

briar-api/src/org/briarproject/api/crypto/CryptoComponent.java

@@ -57,9 +57,6 @@ public interface CryptoComponent {
 	 */
 	byte[] deriveSignatureNonce(SecretKey master, boolean alice);
 
-	/** Derives a group salt from the given master secret. */
-	byte[] deriveGroupSalt(SecretKey master);
-
 	/**
 	 * Derives initial transport keys for the given transport in the given
 	 * rotation period from the given master secret.
@@ -77,6 +74,12 @@ public interface CryptoComponent {
 	/** Encodes the pseudo-random tag that is used to recognise a stream. */
 	void encodeTag(byte[] tag, SecretKey tagKey, long streamNumber);
 
+	/**
+	 * Returns the hash of the given inputs. The inputs are unambiguously
+	 * combined by prefixing each input with its length.
+	 */
+	byte[] hash(byte[]... inputs);
+
 	/**
 	 * Encrypts and authenticates the given plaintext so it can be written to
 	 * storage. The encryption and authentication keys are derived from the

briar-api/src/org/briarproject/api/data/BdfDictionary.java

@@ -1,46 +1,90 @@
 package org.briarproject.api.data;
 
+import org.briarproject.api.FormatException;
+
 import java.util.HashMap;
 
 // This class is not thread-safe
 public class BdfDictionary extends HashMap<String, Object> {
 
+	public Boolean getBoolean(String key) throws FormatException {
+		Object o = get(key);
+		if (o instanceof Boolean) return (Boolean) o;
+		throw new FormatException();
+	}
+
 	public Boolean getBoolean(String key, Boolean defaultValue) {
 		Object o = get(key);
 		if (o instanceof Boolean) return (Boolean) o;
 		return defaultValue;
 	}
 
+	public Long getInteger(String key) throws FormatException {
+		Object o = get(key);
+		if (o instanceof Long) return (Long) o;
+		throw new FormatException();
+	}
+
 	public Long getInteger(String key, Long defaultValue) {
 		Object o = get(key);
 		if (o instanceof Long) return (Long) o;
 		return defaultValue;
 	}
 
+	public Double getFloat(String key) throws FormatException {
+		Object o = get(key);
+		if (o instanceof Double) return (Double) o;
+		throw new FormatException();
+	}
+
 	public Double getFloat(String key, Double defaultValue) {
 		Object o = get(key);
 		if (o instanceof Double) return (Double) o;
 		return defaultValue;
 	}
 
+	public String getString(String key) throws FormatException {
+		Object o = get(key);
+		if (o instanceof String) return (String) o;
+		throw new FormatException();
+	}
+
 	public String getString(String key, String defaultValue) {
 		Object o = get(key);
 		if (o instanceof String) return (String) o;
 		return defaultValue;
 	}
 
+	public byte[] getRaw(String key) throws FormatException {
+		Object o = get(key);
+		if (o instanceof byte[]) return (byte[]) o;
+		throw new FormatException();
+	}
+
 	public byte[] getRaw(String key, byte[] defaultValue) {
 		Object o = get(key);
 		if (o instanceof byte[]) return (byte[]) o;
 		return defaultValue;
 	}
 
+	public BdfList getList(String key) throws FormatException {
+		Object o = get(key);
+		if (o instanceof BdfList) return (BdfList) o;
+		throw new FormatException();
+	}
+
 	public BdfList getList(String key, BdfList defaultValue) {
 		Object o = get(key);
 		if (o instanceof BdfList) return (BdfList) o;
 		return defaultValue;
 	}
 
+	public BdfDictionary getDictionary(String key) throws FormatException {
+		Object o = get(key);
+		if (o instanceof BdfDictionary) return (BdfDictionary) o;
+		throw new FormatException();
+	}
+
 	public BdfDictionary getDictionary(String key, BdfDictionary defaultValue) {
 		Object o = get(key);
 		if (o instanceof BdfDictionary) return (BdfDictionary) o;

briar-api/src/org/briarproject/api/data/BdfList.java

@@ -1,46 +1,90 @@
 package org.briarproject.api.data;
 
+import org.briarproject.api.FormatException;
+
 import java.util.ArrayList;
 
 // This class is not thread-safe
 public class BdfList extends ArrayList<Object> {
 
+	public Boolean getBoolean(int index) throws FormatException {
+		Object o = get(index);
+		if (o instanceof Boolean) return (Boolean) o;
+		throw new FormatException();
+	}
+
 	public Boolean getBoolean(int index, Boolean defaultValue) {
 		Object o = get(index);
 		if (o instanceof Boolean) return (Boolean) o;
 		return defaultValue;
 	}
 
+	public Long getInteger(int index) throws FormatException {
+		Object o = get(index);
+		if (o instanceof Long) return (Long) o;
+		throw new FormatException();
+	}
+
 	public Long getInteger(int index, Long defaultValue) {
 		Object o = get(index);
 		if (o instanceof Long) return (Long) o;
 		return defaultValue;
 	}
 
+	public Double getFloat(int index) throws FormatException {
+		Object o = get(index);
+		if (o instanceof Double) return (Double) o;
+		throw new FormatException();
+	}
+
 	public Double getFloat(int index, Double defaultValue) {
 		Object o = get(index);
 		if (o instanceof Double) return (Double) o;
 		return defaultValue;
 	}
 
+	public String getString(int index) throws FormatException {
+		Object o = get(index);
+		if (o instanceof String) return (String) o;
+		throw new FormatException();
+	}
+
 	public String getString(int index, String defaultValue) {
 		Object o = get(index);
 		if (o instanceof String) return (String) o;
 		return defaultValue;
 	}
 
+	public byte[] getRaw(int index) throws FormatException {
+		Object o = get(index);
+		if (o instanceof byte[]) return (byte[]) o;
+		throw new FormatException();
+	}
+
 	public byte[] getRaw(int index, byte[] defaultValue) {
 		Object o = get(index);
 		if (o instanceof byte[]) return (byte[]) o;
 		return defaultValue;
 	}
 
+	public BdfList getList(int index) throws FormatException {
+		Object o = get(index);
+		if (o instanceof BdfList) return (BdfList) o;
+		throw new FormatException();
+	}
+
 	public BdfList getList(int index, BdfList defaultValue) {
 		Object o = get(index);
 		if (o instanceof BdfList) return (BdfList) o;
 		return defaultValue;
 	}
 
+	public BdfDictionary getDictionary(int index) throws FormatException {
+		Object o = get(index);
+		if (o instanceof BdfDictionary) return (BdfDictionary) o;
+		throw new FormatException();
+	}
+
 	public BdfDictionary getDictionary(int index, BdfDictionary defaultValue) {
 		Object o = get(index);
 		if (o instanceof BdfDictionary) return (BdfDictionary) o;

briar-api/src/org/briarproject/api/data/BdfReader.java

@@ -7,9 +7,6 @@ public interface BdfReader {
 	boolean eof() throws IOException;
 	void close() throws IOException;
 
-	void addConsumer(Consumer c);
-	void removeConsumer(Consumer c);
-
 	boolean hasNull() throws IOException;
 	void readNull() throws IOException;
 	void skipNull() throws IOException;

briar-api/src/org/briarproject/api/data/DataConstants.java

@@ -1,12 +0,0 @@
-package org.briarproject.api.data;
-
-import org.briarproject.api.UniqueId;
-
-public interface DataConstants {
-
-	int LIST_START_LENGTH = 1;
-
-	int LIST_END_LENGTH = 1;
-
-	int UNIQUE_ID_LENGTH = 2 + UniqueId.LENGTH;
-}

briar-api/src/org/briarproject/api/db/DatabaseComponent.java

@@ -9,11 +9,12 @@ import org.briarproject.api.identity.Author;
 import org.briarproject.api.identity.AuthorId;
 import org.briarproject.api.identity.LocalAuthor;
 import org.briarproject.api.sync.Ack;
+import org.briarproject.api.sync.ClientId;
 import org.briarproject.api.sync.Group;
 import org.briarproject.api.sync.GroupId;
 import org.briarproject.api.sync.Message;
-import org.briarproject.api.sync.MessageHeader;
 import org.briarproject.api.sync.MessageId;
+import org.briarproject.api.sync.MessageStatus;
 import org.briarproject.api.sync.Offer;
 import org.briarproject.api.sync.Request;
 import org.briarproject.api.sync.SubscriptionAck;
@@ -44,9 +45,12 @@ public interface DatabaseComponent {
 	 */
 	ContactId addContact(Author remote, AuthorId local) throws DbException;
 
+	/** Adds a group to the given contact's subscriptions. */
+	void addGroup(ContactId c, Group g) throws DbException;
+
 	/**
 	 * Subscribes to a group, or returns false if the user already has the
-	 * maximum number of public subscriptions.
+	 * maximum number of subscriptions.
 	 */
 	boolean addGroup(Group g) throws DbException;
 
@@ -54,7 +58,8 @@ public interface DatabaseComponent {
 	void addLocalAuthor(LocalAuthor a) throws DbException;
 
 	/** Stores a local message. */
-	void addLocalMessage(Message m) throws DbException;
+	void addLocalMessage(Message m, ClientId c, Metadata meta)
+			throws DbException;
 
 	/**
 	 * Stores a transport and returns true if the transport was not previously
@@ -147,22 +152,9 @@ public interface DatabaseComponent {
 	/** Returns the group with the given ID, if the user subscribes to it. */
 	Group getGroup(GroupId g) throws DbException;
 
-	/** Returns all groups to which the user subscribes, excluding inboxes. */
+	/** Returns all groups to which the user subscribes. */
 	Collection<Group> getGroups() throws DbException;
 
-	/**
-	 * Returns the ID of the inbox group for the given contact, or null if no
-	 * inbox group has been set.
-	 */
-	GroupId getInboxGroupId(ContactId c) throws DbException;
-
-	/**
-	 * Returns the headers of all messages in the inbox group for the given
-	 * contact, or null if no inbox group has been set.
-	 */
-	Collection<MessageHeader> getInboxMessageHeaders(ContactId c)
-			throws DbException;
-
 	/** Returns the local pseudonym with the given ID. */
 	LocalAuthor getLocalAuthor(AuthorId a) throws DbException;
 
@@ -176,15 +168,35 @@ public interface DatabaseComponent {
 	/** Returns the local transport properties for the given transport. */
 	TransportProperties getLocalProperties(TransportId t) throws DbException;
 
-	/** Returns the body of the message with the given ID. */
-	byte[] getMessageBody(MessageId m) throws DbException;
+	/**
+	 * Returns the IDs of any messages that need to be validated by the given
+	 * client.
+	 */
+	Collection<MessageId> getMessagesToValidate(ClientId c) throws DbException;
 
-	/** Returns the headers of all messages in the given group. */
-	Collection<MessageHeader> getMessageHeaders(GroupId g)
+	/** Returns the message with the given ID, in serialised form. */
+	byte[] getRawMessage(MessageId m) throws DbException;
+
+	/** Returns the metadata for all messages in the given group. */
+	Map<MessageId, Metadata> getMessageMetadata(GroupId g)
 			throws DbException;
 
-	/** Returns true if the given message is marked as read. */
-	boolean getReadFlag(MessageId m) throws DbException;
+	/** Returns the metadata for the given message. */
+	Metadata getMessageMetadata(MessageId m) throws DbException;
+
+	/**
+	 * Returns the status of all messages in the given group with respect to
+	 * the given contact.
+	 */
+	Collection<MessageStatus> getMessageStatus(ContactId c, GroupId g)
+			throws DbException;
+
+	/**
+	 * Returns the status of the given message with respect to the given
+	 * contact.
+	 */
+	MessageStatus getMessageStatus(ContactId c, MessageId m)
+			throws DbException;
 
 	/** Returns all remote transport properties for the given transport. */
 	Map<ContactId, TransportProperties> getRemoteProperties(TransportId t)
@@ -203,9 +215,6 @@ public interface DatabaseComponent {
 	/** Returns the maximum latencies in milliseconds of all transports. */
 	Map<TransportId, Integer> getTransportLatencies() throws DbException;
 
-	/** Returns the number of unread messages in each subscribed group. */
-	Map<GroupId, Integer> getUnreadMessageCounts() throws DbException;
-
 	/** Returns the IDs of all contacts to which the given group is visible. */
 	Collection<ContactId> getVisibility(GroupId g) throws DbException;
 
@@ -223,6 +232,12 @@ public interface DatabaseComponent {
 	void mergeLocalProperties(TransportId t, TransportProperties p)
 			throws DbException;
 
+	/**
+	 * Merges the given metadata with the existing metadata for the given
+	 * message.
+	 */
+	void mergeMessageMetadata(MessageId m, Metadata meta) throws DbException;
+
 	/**
 	 * Merges the given settings with the existing settings in the given
 	 * namespace.
@@ -276,16 +291,9 @@ public interface DatabaseComponent {
 	 */
 	void removeTransport(TransportId t) throws DbException;
 
-	/**
-	 * Makes a group visible to the given contact, adds it to the contact's
-	 * subscriptions, and sets it as the inbox group for the contact.
-	 */
-	void setInboxGroup(ContactId c, Group g) throws DbException;
-
-	/**
-	 * Marks a message as read or unread.
-	 */
-	void setReadFlag(MessageId m, boolean read) throws DbException;
+	/** Marks the given message as valid or invalid. */
+	void setMessageValidity(Message m, ClientId c, boolean valid)
+			throws DbException;
 
 	/**
 	 * Sets the remote transport properties for the given contact, replacing

briar-api/src/org/briarproject/api/event/MessageAddedEvent.java

@@ -22,7 +22,7 @@ public class MessageAddedEvent extends Event {
 
 	/** Returns the ID of the group to which the message belongs. */
 	public GroupId getGroupId() {
-		return message.getGroup().getId();
+		return message.getGroupId();
 	}
 
 	/**

briar-api/src/org/briarproject/api/event/MessageValidatedEvent.java

@@ -0,0 +1,38 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.sync.ClientId;
+import org.briarproject.api.sync.Message;
+
+/**
+ * An event that is broadcast when a message has passed or failed validation.
+ */
+public class MessageValidatedEvent extends Event {
+
+	private final Message message;
+	private final ClientId clientId;
+	private final boolean local, valid;
+
+	public MessageValidatedEvent(Message message, ClientId clientId,
+			boolean local, boolean valid) {
+		this.message = message;
+		this.clientId = clientId;
+		this.local = local;
+		this.valid = valid;
+	}
+
+	public Message getMessage() {
+		return message;
+	}
+
+	public ClientId getClientId() {
+		return clientId;
+	}
+
+	public boolean isLocal() {
+		return local;
+	}
+
+	public boolean isValid() {
+		return valid;
+	}
+}

briar-api/src/org/briarproject/api/forum/Forum.java

@@ -1,10 +1,37 @@
 package org.briarproject.api.forum;
 
+import org.briarproject.api.sync.Group;
 import org.briarproject.api.sync.GroupId;
 
-public interface Forum {
+public class Forum {
 
-	GroupId getId();
+	private final Group group;
+	private final String name;
 
-	String getName();
+	public Forum(Group group, String name) {
+		this.group = group;
+		this.name = name;
+	}
+
+	public GroupId getId() {
+		return group.getId();
+	}
+
+	public Group getGroup() {
+		return group;
+	}
+
+	public String getName() {
+		return name;
+	}
+
+	@Override
+	public int hashCode() {
+		return group.hashCode();
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		return o instanceof Forum && group.equals(((Forum) o).group);
+	}
 }

briar-api/src/org/briarproject/api/forum/ForumConstants.java

@@ -0,0 +1,19 @@
+package org.briarproject.api.forum;
+
+import static org.briarproject.api.sync.SyncConstants.MAX_GROUP_DESCRIPTOR_LENGTH;
+import static org.briarproject.api.sync.SyncConstants.MAX_MESSAGE_BODY_LENGTH;
+
+public interface ForumConstants {
+
+	/** The maximum length of a forum's name in bytes. */
+	int MAX_FORUM_NAME_LENGTH = MAX_GROUP_DESCRIPTOR_LENGTH - 10;
+
+	/** The length of a forum's random salt in bytes. */
+	int FORUM_SALT_LENGTH = 32;
+
+	/** The maximum length of a forum post's content type in bytes. */
+	int MAX_CONTENT_TYPE_LENGTH = 50;
+
+	/** The maximum length of a forum post's body in bytes. */
+	int MAX_FORUM_POST_BODY_LENGTH = MAX_MESSAGE_BODY_LENGTH - 1024;
+}

briar-api/src/org/briarproject/api/forum/ForumFactory.java

@@ -1,7 +0,0 @@
-package org.briarproject.api.forum;
-
-public interface ForumFactory {
-
-	/** Creates a forum with the given name and a random salt. */
-	Forum createForum(String name);
-}

briar-api/src/org/briarproject/api/forum/ForumManager.java

@@ -3,14 +3,20 @@ package org.briarproject.api.forum;
 import org.briarproject.api.contact.Contact;
 import org.briarproject.api.contact.ContactId;
 import org.briarproject.api.db.DbException;
+import org.briarproject.api.sync.ClientId;
 import org.briarproject.api.sync.GroupId;
-import org.briarproject.api.sync.Message;
 import org.briarproject.api.sync.MessageId;
 
 import java.util.Collection;
 
 public interface ForumManager {
 
+	/** Returns the unique ID of the forum client. */
+	ClientId getClientId();
+
+	/** Creates a forum with the given name. */
+	Forum createForum(String name);
+
 	/**
 	 * Subscribes to a forum, or returns false if the user already has the
 	 * maximum number of forum subscriptions.
@@ -18,7 +24,7 @@ public interface ForumManager {
 	boolean addForum(Forum f) throws DbException;
 
 	/** Stores a local forum post. */
-	void addLocalPost(Message m) throws DbException;
+	void addLocalPost(ForumPost p) throws DbException;
 
 	/** Returns all forums to which the user could subscribe. */
 	Collection<Forum> getAvailableForums() throws DbException;

briar-api/src/org/briarproject/api/forum/ForumPost.java

@@ -0,0 +1,37 @@
+package org.briarproject.api.forum;
+
+import org.briarproject.api.identity.Author;
+import org.briarproject.api.sync.Message;
+import org.briarproject.api.sync.MessageId;
+
+public class ForumPost {
+
+	private final Message message;
+	private final MessageId parent;
+	private final Author author;
+	private final String contentType;
+
+	public ForumPost(Message message, MessageId parent, Author author,
+			String contentType) {
+		this.message = message;
+		this.parent = parent;
+		this.author = author;
+		this.contentType = contentType;
+	}
+
+	public Message getMessage() {
+		return message;
+	}
+
+	public MessageId getParent() {
+		return parent;
+	}
+
+	public Author getAuthor() {
+		return author;
+	}
+
+	public String getContentType() {
+		return contentType;
+	}
+}

briar-api/src/org/briarproject/api/forum/ForumPostFactory.java

@@ -2,7 +2,7 @@ package org.briarproject.api.forum;
 
 import org.briarproject.api.crypto.PrivateKey;
 import org.briarproject.api.identity.Author;
-import org.briarproject.api.sync.Message;
+import org.briarproject.api.sync.GroupId;
 import org.briarproject.api.sync.MessageId;
 
 import java.io.IOException;
@@ -10,12 +10,12 @@ import java.security.GeneralSecurityException;
 
 public interface ForumPostFactory {
 
-	Message createAnonymousPost(MessageId parent, Forum forum,
-			String contentType, long timestamp, byte[] body) throws IOException,
-			GeneralSecurityException;
+	ForumPost createAnonymousPost(GroupId groupId, long timestamp,
+			MessageId parent, String contentType, byte[] body)
+			throws IOException, GeneralSecurityException;
 
-	Message createPseudonymousPost(MessageId parent, Forum forum,
-			Author author, PrivateKey privateKey, String contentType,
-			long timestamp, byte[] body) throws IOException,
+	ForumPost createPseudonymousPost(GroupId groupId, long timestamp,
+			MessageId parent, Author author, String contentType, byte[] body,
+			PrivateKey privateKey) throws IOException,
 			GeneralSecurityException;
 }

briar-api/src/org/briarproject/api/forum/ForumPostHeader.java

@@ -3,17 +3,46 @@ package org.briarproject.api.forum;
 import org.briarproject.api.identity.Author;
 import org.briarproject.api.sync.MessageId;
 
-public interface ForumPostHeader {
+public class ForumPostHeader {
 
-	MessageId getId();
+	private final MessageId id;
+	private final long timestamp;
+	private final Author author;
+	private final Author.Status authorStatus;
+	private final String contentType;
+	private final boolean read;
 
-	Author getAuthor();
+	public ForumPostHeader(MessageId id, long timestamp, Author author,
+			Author.Status authorStatus, String contentType, boolean read) {
+		this.id = id;
+		this.timestamp = timestamp;
+		this.author = author;
+		this.authorStatus = authorStatus;
+		this.contentType = contentType;
+		this.read = read;
+	}
 
-	Author.Status getAuthorStatus();
+	public MessageId getId() {
+		return id;
+	}
 
-	String getContentType();
+	public Author getAuthor() {
+		return author;
+	}
 
-	long getTimestamp();
+	public Author.Status getAuthorStatus() {
+		return authorStatus;
+	}
 
-	boolean isRead();
+	public String getContentType() {
+		return contentType;
+	}
+
+	public long getTimestamp() {
+		return timestamp;
+	}
+
+	public boolean isRead() {
+		return read;
+	}
 }

briar-api/src/org/briarproject/api/identity/AuthorId.java

@@ -2,22 +2,25 @@ package org.briarproject.api.identity;
 
 import org.briarproject.api.UniqueId;
 
+import java.nio.charset.Charset;
 import java.util.Arrays;
 
 /**
  * Type-safe wrapper for a byte array that uniquely identifies an
- * {@link Author}.
+ * {@link org.briarproject.api.identity.Author Author}.
  */
 public class AuthorId extends UniqueId {
 
+	/** Label for hashing authors to calculate their identities. */
+	public static final byte[] LABEL =
+			"AUTHOR_ID".getBytes(Charset.forName("US-ASCII"));
+
 	public AuthorId(byte[] id) {
 		super(id);
 	}
 
 	@Override
 	public boolean equals(Object o) {
-		if (o instanceof AuthorId)
-			return Arrays.equals(id, ((AuthorId) o).id);
-		return false;
+		return o instanceof AuthorId && Arrays.equals(id, ((AuthorId) o).id);
 	}
 }

briar-api/src/org/briarproject/api/messaging/MessagingConstants.java

@@ -0,0 +1,12 @@
+package org.briarproject.api.messaging;
+
+import static org.briarproject.api.sync.SyncConstants.MAX_MESSAGE_BODY_LENGTH;
+
+public interface MessagingConstants {
+
+	/** The maximum length of a private message's content type in bytes. */
+	int MAX_CONTENT_TYPE_LENGTH = 50;
+
+	/** The maximum length of a private message's body in bytes. */
+	int MAX_PRIVATE_MESSAGE_BODY_LENGTH = MAX_MESSAGE_BODY_LENGTH - 1024;
+}

briar-api/src/org/briarproject/api/messaging/MessagingManager.java

@@ -1,37 +1,35 @@
 package org.briarproject.api.messaging;
 
 import org.briarproject.api.contact.ContactId;
-import org.briarproject.api.crypto.SecretKey;
 import org.briarproject.api.db.DbException;
+import org.briarproject.api.sync.ClientId;
 import org.briarproject.api.sync.GroupId;
-import org.briarproject.api.sync.Message;
 import org.briarproject.api.sync.MessageId;
 
 import java.util.Collection;
 
 public interface MessagingManager {
 
+	/** Returns the unique ID of the messaging client. */
+	ClientId getClientId();
+
 	/**
 	 * Informs the messaging manager that a new contact has been added.
 	 * Creates a private conversation with the contact.
 	 */
-	void addContact(ContactId c, SecretKey master) throws DbException;
+	void addContact(ContactId c) throws DbException;
 
 	/** Stores a local private message. */
-	void addLocalMessage(Message m) throws DbException;
+	void addLocalMessage(PrivateMessage m) throws DbException;
 
-	/** Returns the private conversation with the given ID. */
-	PrivateConversation getConversation(GroupId g) throws DbException;
+	/** Returns the ID of the contact with the given private conversation. */
+	ContactId getContactId(GroupId g) throws DbException;
 
-	/**
-	 * Returns the ID of the private conversation with the given contact, or
-	 * null if no private conversation ID has been set.
-	 */
+	/** Returns the ID of the private conversation with the given contact. */
 	GroupId getConversationId(ContactId c) throws DbException;
 
 	/**
-	 * Returns the headers of all messages in the private conversation with the
-	 * given contact, or null if no private conversation ID has been set.
+	 * Returns the headers of all messages in the given private conversation.
 	 */
 	Collection<PrivateMessageHeader> getMessageHeaders(ContactId c)
 			throws DbException;
@@ -39,13 +37,6 @@ public interface MessagingManager {
 	/** Returns the body of the private message with the given ID. */
 	byte[] getMessageBody(MessageId m) throws DbException;
 
-	/**
-	 * Makes a private conversation visible to the given contact, adds it to
-	 * the contact's subscriptions, and sets it as the private conversation for
-	 * the contact.
-	 */
-	void setConversation(ContactId c, PrivateConversation p) throws DbException;
-
 	/** Marks a private message as read or unread. */
 	void setReadFlag(MessageId m, boolean read) throws DbException;
 }

briar-api/src/org/briarproject/api/messaging/PrivateConversation.java

@@ -1,8 +1,33 @@
 package org.briarproject.api.messaging;
 
+import org.briarproject.api.sync.Group;
 import org.briarproject.api.sync.GroupId;
 
-public interface PrivateConversation {
+// TODO: Remove if no longer needed
+public class PrivateConversation {
 
-	GroupId getId();
+	private final Group group;
+
+	public PrivateConversation(Group group) {
+		this.group = group;
+	}
+
+	public GroupId getId() {
+		return group.getId();
+	}
+
+	public Group getGroup() {
+		return group;
+	}
+
+	@Override
+	public int hashCode() {
+		return group.hashCode();
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		return o instanceof PrivateConversation
+				&& group.equals(((PrivateConversation) o).group);
+	}
 }

briar-api/src/org/briarproject/api/messaging/PrivateMessage.java

@@ -0,0 +1,30 @@
+package org.briarproject.api.messaging;
+
+import org.briarproject.api.sync.Message;
+import org.briarproject.api.sync.MessageId;
+
+public class PrivateMessage {
+
+	private final Message message;
+	private final MessageId parent;
+	private final String contentType;
+
+	public PrivateMessage(Message message, MessageId parent,
+			String contentType) {
+		this.message = message;
+		this.parent = parent;
+		this.contentType = contentType;
+	}
+
+	public Message getMessage() {
+		return message;
+	}
+
+	public MessageId getParent() {
+		return parent;
+	}
+
+	public String getContentType() {
+		return contentType;
+	}
+}

briar-api/src/org/briarproject/api/messaging/PrivateMessageFactory.java

@@ -1,6 +1,6 @@
 package org.briarproject.api.messaging;
 
-import org.briarproject.api.sync.Message;
+import org.briarproject.api.sync.GroupId;
 import org.briarproject.api.sync.MessageId;
 
 import java.io.IOException;
@@ -8,8 +8,7 @@ import java.security.GeneralSecurityException;
 
 public interface PrivateMessageFactory {
 
-	Message createPrivateMessage(MessageId parent,
-			PrivateConversation conversation, String contentType,
-			long timestamp, byte[] body) throws IOException,
-			GeneralSecurityException;
+	PrivateMessage createPrivateMessage(GroupId groupId, long timestamp,
+			MessageId parent, String contentType, byte[] body)
+			throws IOException, GeneralSecurityException;
 }

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

@@ -1,23 +1,51 @@
 package org.briarproject.api.messaging;
 
-import org.briarproject.api.identity.Author;
 import org.briarproject.api.sync.MessageId;
 
-public interface PrivateMessageHeader {
+public class PrivateMessageHeader {
 
-	enum Status { STORED, SENT, DELIVERED }
+	private final MessageId id;
+	private final long timestamp;
+	private final String contentType;
+	private final boolean local, read, sent, seen;
 
-	MessageId getId();
+	public PrivateMessageHeader(MessageId id, long timestamp,
+			String contentType, boolean local, boolean read, boolean sent,
+			boolean seen) {
+		this.id = id;
+		this.timestamp = timestamp;
+		this.contentType = contentType;
+		this.local = local;
+		this.read = read;
+		this.sent = sent;
+		this.seen = seen;
+	}
 
-	Author getAuthor();
+	public MessageId getId() {
+		return id;
+	}
 
-	String getContentType();
+	public String getContentType() {
+		return contentType;
+	}
 
-	long getTimestamp();
+	public long getTimestamp() {
+		return timestamp;
+	}
 
-	boolean isLocal();
+	public boolean isLocal() {
+		return local;
+	}
 
-	boolean isRead();
+	public boolean isRead() {
+		return read;
+	}
 
-	Status getStatus();
+	public boolean isSent() {
+		return sent;
+	}
+
+	public boolean isSeen() {
+		return seen;
+	}
 }

briar-api/src/org/briarproject/api/sync/ClientId.java

@@ -0,0 +1,20 @@
+package org.briarproject.api.sync;
+
+import org.briarproject.api.UniqueId;
+
+import java.util.Arrays;
+
+/**
+ * Type-safe wrapper for a byte array that uniquely identifies a sync client.
+ */
+public class ClientId extends UniqueId {
+
+	public ClientId(byte[] id) {
+		super(id);
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		return o instanceof ClientId && Arrays.equals(id, ((ClientId) o).id);
+	}
+}

briar-api/src/org/briarproject/api/sync/Group.java

@@ -1,28 +1,20 @@
 package org.briarproject.api.sync;
 
-import java.io.UnsupportedEncodingException;
+import static org.briarproject.api.sync.SyncConstants.MAX_GROUP_DESCRIPTOR_LENGTH;
 
 /** A group to which users may subscribe. */
 public class Group {
 
 	private final GroupId id;
-	private final String name;
-	private final byte[] salt;
+	private final ClientId clientId;
+	private final byte[] descriptor;
 
-	public Group(GroupId id, String name, byte[] salt) {
-		int length;
-		try {
-			length = name.getBytes("UTF-8").length;
-		} catch (UnsupportedEncodingException e) {
-			throw new RuntimeException(e);
-		}
-		if (length == 0 || length > MessagingConstants.MAX_GROUP_NAME_LENGTH)
-			throw new IllegalArgumentException();
-		if (salt.length != MessagingConstants.GROUP_SALT_LENGTH)
+	public Group(GroupId id, ClientId clientId, byte[] descriptor) {
+		if (descriptor.length > MAX_GROUP_DESCRIPTOR_LENGTH)
 			throw new IllegalArgumentException();
 		this.id = id;
-		this.name = name;
-		this.salt = salt;
+		this.clientId = clientId;
+		this.descriptor = descriptor;
 	}
 
 	/** Returns the group's unique identifier. */
@@ -30,17 +22,14 @@ public class Group {
 		return id;
 	}
 
-	/** Returns the group's name. */
-	public String getName() {
-		return name;
+	/** Returns the ID of the client to which the group belongs. */
+	public ClientId getClientId() {
+		return clientId;
 	}
 
-	/**
-	 * Returns the salt used to distinguish the group from other groups with
-	 * the same name.
-	 */
-	public byte[] getSalt() {
-		return salt;
+	/** Returns the group's descriptor. */
+	public byte[] getDescriptor() {
+		return descriptor;
 	}
 
 	@Override

briar-api/src/org/briarproject/api/sync/GroupFactory.java

@@ -2,9 +2,6 @@ package org.briarproject.api.sync;
 
 public interface GroupFactory {
 
-	/** Creates a group with the given name and a random salt. */
-	Group createGroup(String name);
-
-	/** Creates a group with the given name and salt. */
-	Group createGroup(String name, byte[] salt);
+	/** Creates a group with the given client ID and descriptor. */
+	Group createGroup(ClientId c, byte[] descriptor);
 }

briar-api/src/org/briarproject/api/sync/GroupId.java

@@ -2,6 +2,7 @@ package org.briarproject.api.sync;
 
 import org.briarproject.api.UniqueId;
 
+import java.nio.charset.Charset;
 import java.util.Arrays;
 
 /**
@@ -9,14 +10,16 @@ import java.util.Arrays;
  */
 public class GroupId extends UniqueId {
 
+	/** Label for hashing groups to calculate their identifiers. */
+	public static final byte[] LABEL =
+			"GROUP_ID".getBytes(Charset.forName("US-ASCII"));
+
 	public GroupId(byte[] id) {
 		super(id);
 	}
 
 	@Override
 	public boolean equals(Object o) {
-		if (o instanceof GroupId)
-			return Arrays.equals(id, ((GroupId) o).id);
-		return false;
+		return o instanceof GroupId && Arrays.equals(id, ((GroupId) o).id);
 	}
 }

briar-api/src/org/briarproject/api/sync/Message.java

@@ -1,42 +1,58 @@
 package org.briarproject.api.sync;
 
-import org.briarproject.api.identity.Author;
+import static org.briarproject.api.sync.SyncConstants.MAX_MESSAGE_LENGTH;
+import static org.briarproject.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
 
-public interface Message {
+public class Message {
+
+	private final MessageId id;
+	private final GroupId groupId;
+	private final long timestamp;
+	private final byte[] raw;
+
+	public Message(MessageId id, GroupId groupId, long timestamp, byte[] raw) {
+		if (raw.length <= MESSAGE_HEADER_LENGTH)
+			throw new IllegalArgumentException();
+		if (raw.length > MAX_MESSAGE_LENGTH)
+			throw new IllegalArgumentException();
+		this.id = id;
+		this.groupId = groupId;
+		this.timestamp = timestamp;
+		this.raw = raw;
+	}
 
 	/** Returns the message's unique identifier. */
-	MessageId getId();
+	public MessageId getId() {
+		return id;
+	}
 
-	/**
-	 * Returns the identifier of the message's parent, or null if this is the
-	 * first message in a thread.
-	 */
-	MessageId getParent();
-
-	/**
-	 * Returns the {@link Group} to which the message belongs, or null if this
-	 * is a private message.
-	 */
-	Group getGroup();
-
-	/**
-	 * Returns the message's {@link Author Author}, or null
-	 * if this is an anonymous message.
-	 */
-	Author getAuthor();
-
-	/** Returns the message's content type. */
-	String getContentType();
+	/** Returns the ID of the {@link Group} to which the message belongs. */
+	public GroupId getGroupId() {
+		return groupId;
+	}
 
 	/** Returns the message's timestamp in milliseconds since the Unix epoch. */
-	long getTimestamp();
+	public long getTimestamp() {
+		return timestamp;
+	}
 
-	/** Returns the serialised message. */
-	byte[] getSerialised();
+	/** Returns the length of the raw message in bytes. */
+	public int getLength() {
+		return raw.length;
+	}
 
-	/** Returns the offset of the message body within the serialised message. */
-	int getBodyStart();
+	/** Returns the raw message. */
+	public byte[] getRaw() {
+		return raw;
+	}
 
-	/** Returns the length of the message body in bytes. */
-	int getBodyLength();
+	@Override
+	public int hashCode() {
+		return id.hashCode();
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		return o instanceof Message && id.equals(((Message) o).getId());
+	}
 }

briar-api/src/org/briarproject/api/sync/MessageFactory.java

@@ -1,19 +1,9 @@
 package org.briarproject.api.sync;
 
-import org.briarproject.api.crypto.PrivateKey;
-import org.briarproject.api.identity.Author;
-
 import java.io.IOException;
-import java.security.GeneralSecurityException;
 
 public interface MessageFactory {
 
-	Message createAnonymousMessage(MessageId parent, Group group,
-			String contentType, long timestamp, byte[] body) throws IOException,
-			GeneralSecurityException;
-
-	Message createPseudonymousMessage(MessageId parent, Group group,
-			Author author, PrivateKey privateKey, String contentType,
-			long timestamp, byte[] body) throws IOException,
-			GeneralSecurityException;
+	Message createMessage(GroupId groupId, long timestamp, byte[] body)
+			throws IOException;
 }

briar-api/src/org/briarproject/api/sync/MessageHeader.java

@@ -1,92 +0,0 @@
-package org.briarproject.api.sync;
-
-import org.briarproject.api.identity.Author;
-
-public class MessageHeader {
-
-	public enum State { STORED, SENT, DELIVERED }
-
-	private final MessageId id, parent;
-	private final GroupId groupId;
-	private final Author author;
-	private final Author.Status authorStatus;
-	private final String contentType;
-	private final long timestamp;
-	private final boolean local, read;
-	private final State status;
-
-	public MessageHeader(MessageId id, MessageId parent, GroupId groupId,
-			Author author, Author.Status authorStatus, String contentType,
-			long timestamp, boolean local, boolean read, State status) {
-		this.id = id;
-		this.parent = parent;
-		this.groupId = groupId;
-		this.author = author;
-		this.authorStatus = authorStatus;
-		this.contentType = contentType;
-		this.timestamp = timestamp;
-		this.local = local;
-		this.read = read;
-		this.status = status;
-	}
-
-	/** Returns the message's unique identifier. */
-	public MessageId getId() {
-		return id;
-	}
-
-	/**
-	 * Returns the message's parent, or null if this is the first message in a
-	 * thread.
-	 */
-	public MessageId getParent() {
-		return parent;
-	}
-
-	/**
-	 * Returns the unique identifier of the group to which the message belongs.
-	 */
-	public GroupId getGroupId() {
-		return groupId;
-	}
-
-	/**
-	 * Returns the message's author, or null if this is an  anonymous message.
-	 */
-	public Author getAuthor() {
-		return author;
-	}
-
-	/**  Returns the status of the message's author. */
-	public Author.Status getAuthorStatus() {
-		return authorStatus;
-	}
-
-	/** Returns the message's content type. */
-	public String getContentType() {
-		return contentType;
-	}
-
-	/** Returns the timestamp created by the message's author. */
-	public long getTimestamp() {
-		return timestamp;
-	}
-
-	/** Returns true if the message was locally generated. */
-	public boolean isLocal() {
-		return local;
-	}
-
-	/** Returns true if the message has been read. */
-	public boolean isRead() {
-		return read;
-	}
-
-	/**
-	 * Returns message status. (This only applies to locally generated private
-	 * messages.)
-	 */
-	public State getStatus() {
-		return status;
-	}
-}

briar-api/src/org/briarproject/api/sync/MessageId.java

@@ -2,6 +2,7 @@ package org.briarproject.api.sync;
 
 import org.briarproject.api.UniqueId;
 
+import java.nio.charset.Charset;
 import java.util.Arrays;
 
 /**
@@ -10,14 +11,16 @@ import java.util.Arrays;
  */
 public class MessageId extends UniqueId {
 
+	/** Label for hashing messages to calculate their identifiers. */
+	public static final byte[] LABEL =
+			"MESSAGE_ID".getBytes(Charset.forName("US-ASCII"));
+
 	public MessageId(byte[] id) {
 		super(id);
 	}
 
 	@Override
 	public boolean equals(Object o) {
-		if (o instanceof MessageId)
-			return Arrays.equals(id, ((MessageId) o).id);
-		return false;
+		return o instanceof MessageId && Arrays.equals(id, ((MessageId) o).id);
 	}
 }

briar-api/src/org/briarproject/api/sync/MessageStatus.java

@@ -0,0 +1,38 @@
+package org.briarproject.api.sync;
+
+import org.briarproject.api.contact.ContactId;
+
+public class MessageStatus {
+
+	private final MessageId messageId;
+	private final ContactId contactId;
+	private final boolean sent, seen;
+
+	public MessageStatus(MessageId messageId, ContactId contactId,
+			boolean sent, boolean seen) {
+		this.messageId = messageId;
+		this.contactId = contactId;
+		this.sent = sent;
+		this.seen = seen;
+	}
+
+	/** Returns the ID of the message. */
+	public MessageId getMessageId() {
+		return messageId;
+	}
+
+	/** Returns the ID of the contact. */
+	public ContactId getContactId() {
+		return contactId;
+	}
+
+	/** Returns true if the message has been sent to the contact. */
+	public boolean isSent() {
+		return sent;
+	}
+
+	/** Returns true if the message has been seen by the contact. */
+	public boolean isSeen() {
+		return seen;
+	}
+}

briar-api/src/org/briarproject/api/sync/MessageValidator.java

@@ -0,0 +1,13 @@
+package org.briarproject.api.sync;
+
+import org.briarproject.api.db.Metadata;
+import org.briarproject.api.lifecycle.Service;
+
+public interface MessageValidator extends Service {
+
+	/**
+	 * Validates the given message and returns its metadata if the message
+	 * is valid, or null if the message is invalid.
+	 */
+	Metadata validateMessage(Message m);
+}

briar-api/src/org/briarproject/api/sync/MessageVerifier.java

@@ -1,9 +0,0 @@
-package org.briarproject.api.sync;
-
-import java.security.GeneralSecurityException;
-
-/** Verifies the signatures on an {@link UnverifiedMessage}. */
-public interface MessageVerifier {
-
-	Message verifyMessage(UnverifiedMessage m) throws GeneralSecurityException;
-}

briar-api/src/org/briarproject/api/sync/MessagingConstants.java

@@ -1,46 +0,0 @@
-package org.briarproject.api.sync;
-
-
-public interface MessagingConstants {
-
-	/** The current version of the messaging protocol. */
-	byte PROTOCOL_VERSION = 0;
-
-	/** The length of the packet header in bytes. */
-	int HEADER_LENGTH = 4;
-
-	/** The maximum length of the packet payload in bytes. */
-	int MAX_PAYLOAD_LENGTH = 32 * 1024; // 32 KiB
-
-	/** The maximum number of public groups a user may subscribe to. */
-	int MAX_SUBSCRIPTIONS = 300;
-
-	/** The maximum length of a group's name in UTF-8 bytes. */
-	int MAX_GROUP_NAME_LENGTH = 50;
-
-	/** The length of a group's random salt in bytes. */
-	int GROUP_SALT_LENGTH = 32;
-
-	/**
-	 * The maximum length of a message body in bytes. To allow for future
-	 * changes in the protocol, this is smaller than the maximum payload length
-	 * even when all the message's other fields have their maximum lengths.
-	 */
-	int MAX_BODY_LENGTH = MAX_PAYLOAD_LENGTH - 1024;
-
-	/** The maximum length of a message's content type in UTF-8 bytes. */
-	int MAX_CONTENT_TYPE_LENGTH = 50;
-
-	/** The maximum length of a message's subject line in UTF-8 bytes. */
-	int MAX_SUBJECT_LENGTH = 100;
-
-	/** The length of a message's random salt in bytes. */
-	int MESSAGE_SALT_LENGTH = 32;
-
-	/**
-	 * When calculating the retention time of the database, the timestamp of
-	 * the oldest message in the database is rounded down to a multiple of
-	 * this value to avoid revealing the presence of any particular message.
-	 */
-	int RETENTION_GRANULARITY = 60 * 1000; // 1 minute
-}

briar-api/src/org/briarproject/api/sync/PacketReader.java

@@ -10,7 +10,7 @@ public interface PacketReader {
 	Ack readAck() throws IOException;
 
 	boolean hasMessage() throws IOException;
-	UnverifiedMessage readMessage() throws IOException;
+	Message readMessage() throws IOException;
 
 	boolean hasOffer() throws IOException;
 	Offer readOffer() throws IOException;

briar-api/src/org/briarproject/api/sync/PacketTypes.java

@@ -1,6 +1,6 @@
 package org.briarproject.api.sync;
 
-/** Packet types for the messaging protocol. */
+/** Packet types for the sync protocol. */
 public interface PacketTypes {
 
 	byte ACK = 0;

briar-api/src/org/briarproject/api/sync/SyncConstants.java

@@ -0,0 +1,30 @@
+package org.briarproject.api.sync;
+
+import org.briarproject.api.UniqueId;
+
+public interface SyncConstants {
+
+	/** The current version of the sync protocol. */
+	byte PROTOCOL_VERSION = 0;
+
+	/** The length of the packet header in bytes. */
+	int PACKET_HEADER_LENGTH = 4;
+
+	/** The maximum length of the packet payload in bytes. */
+	int MAX_PACKET_PAYLOAD_LENGTH = 32 * 1024; // 32 KiB
+
+	/** The maximum number of groups a user may subscribe to. */
+	int MAX_SUBSCRIPTIONS = 200;
+
+	/** The maximum length of a group descriptor in bytes. */
+	int MAX_GROUP_DESCRIPTOR_LENGTH = 100;
+
+	/** The maximum length of a message in bytes. */
+	int MAX_MESSAGE_LENGTH = MAX_PACKET_PAYLOAD_LENGTH - PACKET_HEADER_LENGTH;
+
+	/** The length of the message header in bytes. */
+	int MESSAGE_HEADER_LENGTH = UniqueId.LENGTH + 8;
+
+	/** The maximum length of a message body in bytes. */
+	int MAX_MESSAGE_BODY_LENGTH = MAX_MESSAGE_LENGTH - MESSAGE_HEADER_LENGTH;
+}

briar-api/src/org/briarproject/api/sync/SyncSession.java

@@ -2,7 +2,7 @@ package org.briarproject.api.sync;
 
 import java.io.IOException;
 
-public interface MessagingSession {
+public interface SyncSession {
 
 	/**
 	 * Runs the session. This method returns when there are no more packets to

briar-api/src/org/briarproject/api/sync/SyncSessionFactory.java

@@ -6,14 +6,14 @@ import org.briarproject.api.contact.ContactId;
 import java.io.InputStream;
 import java.io.OutputStream;
 
-public interface MessagingSessionFactory {
+public interface SyncSessionFactory {
 
-	MessagingSession createIncomingSession(ContactId c, TransportId t,
+	SyncSession createIncomingSession(ContactId c, TransportId t,
 			InputStream in);
 
-	MessagingSession createSimplexOutgoingSession(ContactId c, TransportId t,
+	SyncSession createSimplexOutgoingSession(ContactId c, TransportId t,
 			int maxLatency, OutputStream out);
 
-	MessagingSession createDuplexOutgoingSession(ContactId c, TransportId t,
+	SyncSession createDuplexOutgoingSession(ContactId c, TransportId t,
 			int maxLatency, int maxIdleTime, OutputStream out);
 }

briar-api/src/org/briarproject/api/sync/UnverifiedMessage.java

@@ -1,94 +0,0 @@
-package org.briarproject.api.sync;
-
-import org.briarproject.api.identity.Author;
-
-/** A {@link Message} that has not yet had its signatures (if any) verified. */
-public class UnverifiedMessage {
-
-	private final MessageId parent;
-	private final Group group;
-	private final Author author;
-	private final String contentType;
-	private final long timestamp;
-	private final byte[] raw, signature;
-	private final int bodyStart, bodyLength, signedLength;
-
-	public UnverifiedMessage(MessageId parent, Group group, Author author,
-			String contentType, long timestamp, byte[] raw, byte[] signature,
-			int bodyStart, int bodyLength, int signedLength) {
-		this.parent = parent;
-		this.group = group;
-		this.author = author;
-		this.contentType = contentType;
-		this.timestamp = timestamp;
-		this.raw = raw;
-		this.signature = signature;
-		this.bodyStart = bodyStart;
-		this.bodyLength = bodyLength;
-		this.signedLength = signedLength;
-	}
-
-	/**
-	 * Returns the identifier of the message's parent, or null if this is the
-	 * first message in a thread.
-	 */
-	public MessageId getParent() {
-		return parent;
-	}
-
-	/**
-	 * Returns the {@link Group} to which the message belongs, or null if this
-	 * is a private message.
-	 */
-	public Group getGroup() {
-		return group;
-	}
-
-	/**
-	 * Returns the message's {@link Author Author}, or null
-	 * if this is an anonymous message.
-	 */
-	public Author getAuthor() {
-		return author;
-	}
-
-	/** Returns the message's content type. */
-	public String getContentType() {
-		return contentType;
-	}
-
-	/** Returns the message's timestamp. */
-	public long getTimestamp() {
-		return timestamp;
-	}
-
-	/** Returns the serialised message. */
-	public byte[] getSerialised() {
-		return raw;
-	}
-
-	/**
-	 * Returns the author's signature, or null if this is an anonymous message.
-	 */
-	public byte[] getSignature() {
-		return signature;
-	}
-
-	/** Returns the offset of the message body within the serialised message. */
-	public int getBodyStart() {
-		return bodyStart;
-	}
-
-	/** Returns the length of the message body in bytes. */
-	public int getBodyLength() {
-		return bodyLength;
-	}
-
-	/**
-	 * Returns the length in bytes of the data covered by the author's
-	 * signature.
-	 */
-	public int getSignedLength() {
-		return signedLength;
-	}
-}

briar-api/src/org/briarproject/api/sync/ValidationManager.java

@@ -0,0 +1,13 @@
+package org.briarproject.api.sync;
+
+import org.briarproject.api.lifecycle.Service;
+
+/**
+ * Responsible for managing message validators and passing them messages to
+ * validate.
+ */
+public interface ValidationManager extends Service {
+
+	/** Sets the message validator for the given client. */
+	void setMessageValidator(ClientId c, MessageValidator v);
+}