Massive refactoring to use pseudonyms instead of nicknames for contacts.

The invitation and private messaging UIs are currently broken. Some key
rotation bugs were fixed; others may have been created (unit tests
needed). An encoding for private keys was added. Pseudonyms were moved
out of the messaging package and ratings were moved in.

briar-api/src/net/sf/briar/api/Author.java

@@ -1,6 +1,6 @@
-package net.sf.briar.api.messaging;
+package net.sf.briar.api;
 
-/** A pseudonymous author of {@link Message}s. */
+/** A pseudonym for a user. */
 public class Author {
 
 	private final AuthorId id;
@@ -23,10 +23,7 @@ public class Author {
 		return name;
 	}
 
-	/**
-	 * Returns the public key that is used to verify messages signed by the
-	 * author.
-	 */
+	/** Returns the public key used to verify the pseudonym's signatures. */
 	public byte[] getPublicKey() {
 		return publicKey;
 	}

briar-api/src/net/sf/briar/api/AuthorFactory.java

@@ -1,4 +1,4 @@
-package net.sf.briar.api.messaging;
+package net.sf.briar.api;
 
 import java.io.IOException;
 

briar-api/src/net/sf/briar/api/AuthorId.java

@@ -1,4 +1,4 @@
-package net.sf.briar.api.messaging;
+package net.sf.briar.api;
 
 import java.util.Arrays;
 

briar-api/src/net/sf/briar/api/Contact.java

@@ -3,12 +3,12 @@ package net.sf.briar.api;
 public class Contact {
 
 	private final ContactId id;
-	private final String name;
+	private final Author author;
 	private final long lastConnected;
 
-	public Contact(ContactId id, String name, long lastConnected) {
+	public Contact(ContactId id, Author author, long lastConnected) {
 		this.id = id;
-		this.name = name;
+		this.author = author;
 		this.lastConnected = lastConnected;
 	}
 
@@ -16,8 +16,8 @@ public class Contact {
 		return id;
 	}
 
-	public String getName() {
-		return name;
+	public Author getAuthor() {
+		return author;
 	}
 
 	public long getLastConnected() {

briar-api/src/net/sf/briar/api/LocalAuthor.java

@@ -1,6 +1,6 @@
-package net.sf.briar.api.messaging;
+package net.sf.briar.api;
 
-/** A pseudonym that the user can use to sign {@link Message}s. */
+/** A pseudonym for the local user. */
 public class LocalAuthor extends Author {
 
 	private final byte[] privateKey;
@@ -11,7 +11,7 @@ public class LocalAuthor extends Author {
 		this.privateKey = privateKey;
 	}
 
-	/** Returns the private key that is used to sign messages. */
+	/**  Returns the private key used to generate the pseudonym's signatures. */
 	public byte[] getPrivateKey() {
 		return privateKey;
 	}

briar-api/src/net/sf/briar/api/TransportId.java

@@ -1,4 +1,4 @@
-package net.sf.briar.api.messaging;
+package net.sf.briar.api;
 
 import java.util.Arrays;
 

briar-api/src/net/sf/briar/api/UniqueId.java

@@ -1,4 +1,4 @@
-package net.sf.briar.api.messaging;
+package net.sf.briar.api;
 
 import java.util.Arrays;
 

briar-api/src/net/sf/briar/api/crypto/CryptoComponent.java

@@ -9,6 +9,61 @@ import javax.crypto.Cipher;
 
 public interface CryptoComponent {
 
+	ErasableKey generateSecretKey();
+
+	MessageDigest getMessageDigest();
+
+	PseudoRandom getPseudoRandom(int seed1, int seed2);
+
+	SecureRandom getSecureRandom();
+
+	Signature getSignature();
+
+	KeyPair generateAgreementKeyPair();
+
+	KeyParser getAgreementKeyParser();
+
+	KeyPair generateSignatureKeyPair();
+
+	KeyParser getSignatureKeyParser();
+
+	/** Generates a random invitation code. */
+	int generateInvitationCode();
+
+	/**
+	 * Derives two confirmation codes from the given master secret. The first
+	 * code is for Alice to give to Bob; the second is for Bob to give to
+	 * Alice.
+	 */
+	int[] deriveConfirmationCodes(byte[] secret);
+
+	/**
+	 * Derives two nonces from the given master secret. The first nonce is for
+	 * Alice to sign; the second is for Bob to sign.
+	 */
+	byte[][] deriveInvitationNonces(byte[] secret);
+
+	/**
+	 * Derives a shared master secret from two public keys and one of the
+	 * corresponding private keys.
+	 * @param alice indicates whether the private key belongs to Alice or Bob.
+	 */
+	byte[] deriveMasterSecret(byte[] theirPublicKey, KeyPair ourKeyPair,
+			boolean alice) throws GeneralSecurityException;
+
+	/**
+	 * Derives an initial secret for the given transport from the given master
+	 * secret.
+	 */
+	byte[] deriveInitialSecret(byte[] secret, int transportIndex);
+
+	/**
+	 * Derives a temporary secret for the given period from the given secret,
+	 * which is either the initial shared secret or the previous period's
+	 * temporary secret.
+	 */
+	byte[] deriveNextSecret(byte[] secret, long period);
+
 	/**
 	 * Derives a tag key from the given temporary secret.
 	 * @param alice indicates whether the key is for connections initiated by
@@ -28,57 +83,18 @@ public interface CryptoComponent {
 			boolean initiator);
 
 	/**
-	 * Derives an initial shared secret from two public keys and one of the
-	 * corresponding private keys.
-	 * @param alice indicates whether the private key belongs to Alice or Bob.
+	 * Returns a cipher for generating the pseudo-random tags that are used to
+	 * recognise connections.
 	 */
-	byte[] deriveInitialSecret(byte[] theirPublicKey, KeyPair ourKeyPair,
-			boolean alice) throws GeneralSecurityException;
+	Cipher getTagCipher();
 
-	/**
-	 * Generates a random invitation code.
-	 */
-	int generateInvitationCode();
-
-	/**
-	 * Derives two confirmation codes from the given initial shared secret. The
-	 * first code is for Alice to give to Bob; the second is for Bob to give to
-	 * Alice.
-	 */
-	int[] deriveConfirmationCodes(byte[] secret);
-
-	/**
-	 * Derives a temporary secret for the given period from the previous
-	 * period's temporary secret.
-	 */
-	byte[] deriveNextSecret(byte[] secret, long period);
+	/** Returns a cipher for encrypting and authenticating connections. */
+	AuthenticatedCipher getFrameCipher();
 
 	/** Encodes the pseudo-random tag that is used to recognise a connection. */
 	void encodeTag(byte[] tag, Cipher tagCipher, ErasableKey tagKey,
 			long connection);
 
-	KeyPair generateAgreementKeyPair();
-
-	KeyParser getAgreementKeyParser();
-
-	KeyPair generateSignatureKeyPair();
-
-	KeyParser getSignatureKeyParser();
-
-	ErasableKey generateSecretKey();
-
-	MessageDigest getMessageDigest();
-
-	PseudoRandom getPseudoRandom(int seed1, int seed2);
-
-	SecureRandom getSecureRandom();
-
-	Cipher getTagCipher();
-
-	AuthenticatedCipher getFrameCipher();
-
-	Signature getSignature();
-
 	/**
 	 * Encrypts the given plaintext so it can be written to temporary storage.
 	 * The ciphertext will not be decryptable after the app restarts.

briar-api/src/net/sf/briar/api/crypto/KeyManager.java

@@ -1,7 +1,7 @@
 package net.sf.briar.api.crypto;
 
 import net.sf.briar.api.ContactId;
-import net.sf.briar.api.messaging.TransportId;
+import net.sf.briar.api.TransportId;
 import net.sf.briar.api.transport.ConnectionContext;
 import net.sf.briar.api.transport.Endpoint;
 

briar-api/src/net/sf/briar/api/crypto/KeyParser.java

@@ -1,9 +1,13 @@
 package net.sf.briar.api.crypto;
 
+import java.security.PrivateKey;
 import java.security.PublicKey;
 import java.security.spec.InvalidKeySpecException;
 
 public interface KeyParser {
 
 	PublicKey parsePublicKey(byte[] encodedKey) throws InvalidKeySpecException;
+
+	PrivateKey parsePrivateKey(byte[] encodedKey)
+			throws InvalidKeySpecException;
 }

briar-api/src/net/sf/briar/api/crypto/Password.java

@@ -1,14 +0,0 @@
-package net.sf.briar.api.crypto;
-
-/**
- * Encapsulates a password. Implementations may keep the password encrypted in
- * memory to reduce the chances of writing it to the swapfile in plaintext.
- */
-public interface Password {
-
-	/**
-	 * Returns the password as a character array, which should be filled with
-	 * zeroes as soon as it has been used.
-	 */
-	char[] getPassword();
-}

briar-api/src/net/sf/briar/api/crypto/PseudoRandom.java

@@ -1,5 +1,6 @@
 package net.sf.briar.api.crypto;
 
+/** A deterministic PRNG. */
 public interface PseudoRandom {
 
 	byte[] nextBytes(int bytes);

briar-api/src/net/sf/briar/api/db/ContactExistsException.java

@@ -0,0 +1,10 @@
+package net.sf.briar.api.db;
+
+/**
+ * Thrown when a duplicate contact is added to the database. This exception may
+ * occur due to concurrent updates and does not indicate a database error.
+ */
+public class ContactExistsException extends DbException {
+
+	private static final long serialVersionUID = -6658762011691502411L;
+}

briar-api/src/net/sf/briar/api/db/DatabaseComponent.java

@@ -4,28 +4,29 @@ import java.io.IOException;
 import java.util.Collection;
 import java.util.Map;
 
+import net.sf.briar.api.Author;
+import net.sf.briar.api.AuthorId;
 import net.sf.briar.api.Contact;
 import net.sf.briar.api.ContactId;
-import net.sf.briar.api.Rating;
+import net.sf.briar.api.LocalAuthor;
 import net.sf.briar.api.TransportConfig;
+import net.sf.briar.api.TransportId;
 import net.sf.briar.api.TransportProperties;
 import net.sf.briar.api.db.event.DatabaseListener;
 import net.sf.briar.api.messaging.Ack;
-import net.sf.briar.api.messaging.AuthorId;
 import net.sf.briar.api.messaging.Group;
 import net.sf.briar.api.messaging.GroupId;
-import net.sf.briar.api.messaging.LocalAuthor;
 import net.sf.briar.api.messaging.LocalGroup;
 import net.sf.briar.api.messaging.Message;
 import net.sf.briar.api.messaging.MessageId;
 import net.sf.briar.api.messaging.Offer;
+import net.sf.briar.api.messaging.Rating;
 import net.sf.briar.api.messaging.Request;
 import net.sf.briar.api.messaging.RetentionAck;
 import net.sf.briar.api.messaging.RetentionUpdate;
 import net.sf.briar.api.messaging.SubscriptionAck;
 import net.sf.briar.api.messaging.SubscriptionUpdate;
 import net.sf.briar.api.messaging.TransportAck;
-import net.sf.briar.api.messaging.TransportId;
 import net.sf.briar.api.messaging.TransportUpdate;
 import net.sf.briar.api.transport.Endpoint;
 import net.sf.briar.api.transport.TemporarySecret;
@@ -53,9 +54,10 @@ public interface DatabaseComponent {
 	void removeListener(DatabaseListener d);
 
 	/**
-	 * Stores a contact with the given name and returns an ID for the contact.
+	 * Stores a contact with the given pseudonym, associated with the given
+	 * local pseudonym, and returns an ID for the contact.
 	 */
-	ContactId addContact(String name) throws DbException;
+	ContactId addContact(Author remote, AuthorId local) throws DbException;
 
 	/** Stores an endpoint. */
 	void addEndpoint(Endpoint ep) throws DbException;
@@ -85,7 +87,7 @@ public interface DatabaseComponent {
 	 * Stores a transport and returns true if the transport was not previously
 	 * in the database.
 	 */
-	boolean addTransport(TransportId t) throws DbException;
+	boolean addTransport(TransportId t, long maxLatency) throws DbException;
 
 	/**
 	 * Generates an acknowledgement for the given contact, or returns null if
@@ -176,12 +178,19 @@ public interface DatabaseComponent {
 	/** Returns the group with the given ID, if the user subscribes to it. */
 	Group getGroup(GroupId g) throws DbException;
 
+	/** Returns the pseudonym with the given ID. */
+	LocalAuthor getLocalAuthor(AuthorId a) throws DbException;
+
 	/** Returns all pseudonyms that the user can use to sign messages. */
 	Collection<LocalAuthor> getLocalAuthors() throws DbException;
 
 	/** Returns all restricted groups to which the user can post messages. */
 	Collection<LocalGroup> getLocalGroups() throws DbException;
 
+	/** Returns the local transport properties for all transports. */
+	Map<TransportId, TransportProperties> getLocalProperties()
+			throws DbException;
+
 	/** Returns the local transport properties for the given transport. */
 	TransportProperties getLocalProperties(TransportId t) throws DbException;
 
@@ -222,6 +231,9 @@ public interface DatabaseComponent {
 	/** Returns the set of groups to which the user subscribes. */
 	Collection<Group> getSubscriptions() throws DbException;
 
+	/** Returns the maximum latencies of all local transports. */
+	Map<TransportId, Long> getTransportLatencies() throws DbException;
+
 	/** Returns the number of unread messages in each subscribed group. */
 	Map<GroupId, Integer> getUnreadMessageCounts() throws DbException;
 
@@ -317,6 +329,13 @@ public interface DatabaseComponent {
 	 */
 	boolean setReadFlag(MessageId m, boolean read) throws DbException;
 
+	/**
+	 * Sets the remote transport properties for the given contact, replacing
+	 * any existing properties.
+	 */
+	void setRemoteProperties(ContactId c,
+			Map<TransportId, TransportProperties> p) throws DbException;
+
 	/** Records the given messages as having been seen by the given contact. */
 	void setSeen(ContactId c, Collection<MessageId> seen) throws DbException;
 

briar-api/src/net/sf/briar/api/db/DatabaseConfig.java

@@ -2,13 +2,11 @@ package net.sf.briar.api.db;
 
 import java.io.File;
 
-import net.sf.briar.api.crypto.Password;
-
 public interface DatabaseConfig {
 
 	File getDataDirectory();
 
-	Password getPassword();
+	char[] getPassword();
 
 	long getMaxSize();
 }

briar-api/src/net/sf/briar/api/db/GroupMessageHeader.java

@@ -1,9 +1,9 @@
 package net.sf.briar.api.db;
 
-import net.sf.briar.api.Rating;
-import net.sf.briar.api.messaging.Author;
+import net.sf.briar.api.Author;
 import net.sf.briar.api.messaging.GroupId;
 import net.sf.briar.api.messaging.MessageId;
+import net.sf.briar.api.messaging.Rating;
 
 public class GroupMessageHeader extends MessageHeader {
 

briar-api/src/net/sf/briar/api/db/event/RatingChangedEvent.java

@@ -1,7 +1,7 @@
 package net.sf.briar.api.db.event;
 
-import net.sf.briar.api.Rating;
-import net.sf.briar.api.messaging.AuthorId;
+import net.sf.briar.api.AuthorId;
+import net.sf.briar.api.messaging.Rating;
 
 public class RatingChangedEvent extends DatabaseEvent {
 

briar-api/src/net/sf/briar/api/db/event/RemoteTransportsUpdatedEvent.java

@@ -1,7 +1,7 @@
 package net.sf.briar.api.db.event;
 
 import net.sf.briar.api.ContactId;
-import net.sf.briar.api.messaging.TransportId;
+import net.sf.briar.api.TransportId;
 
 /**
  * An event that is broadcast when a contact's remote transport properties

briar-api/src/net/sf/briar/api/db/event/TransportAddedEvent.java

@@ -1,17 +1,23 @@
 package net.sf.briar.api.db.event;
 
-import net.sf.briar.api.messaging.TransportId;
+import net.sf.briar.api.TransportId;
 
-/** An event that is broadcast when a transport is added. */
+/** An event that is broadcast when a transport is added to the database. */
 public class TransportAddedEvent extends DatabaseEvent {
 
 	private final TransportId transportId;
+	private final long maxLatency;
 
-	public TransportAddedEvent(TransportId transportId) {
+	public TransportAddedEvent(TransportId transportId, long maxLatency) {
 		this.transportId = transportId;
+		this.maxLatency = maxLatency;
 	}
 
 	public TransportId getTransportId() {
 		return transportId;
 	}
+
+	public long getMaxLatency() {
+		return maxLatency;
+	}
 }

briar-api/src/net/sf/briar/api/db/event/TransportRemovedEvent.java

@@ -1,6 +1,6 @@
 package net.sf.briar.api.db.event;
 
-import net.sf.briar.api.messaging.TransportId;
+import net.sf.briar.api.TransportId;
 
 /** An event that is broadcast when a transport is removed. */
 public class TransportRemovedEvent extends DatabaseEvent {

briar-api/src/net/sf/briar/api/invitation/InvitationListener.java

@@ -9,7 +9,10 @@ public interface InvitationListener {
 	/** Called if a connection is established and key agreement succeeds. */
 	void connectionSucceeded(int localCode, int remoteCode);
 
-	/** Called if a connection cannot be established. */
+	/**
+	 * Called if a connection cannot be established. This indicates that the
+	 * protocol has ended unsuccessfully.
+	 */
 	void connectionFailed();
 
 	/**
@@ -20,7 +23,21 @@ public interface InvitationListener {
 
 	/**
 	 * Informs the local peer that the remote peer's confirmation check did
-	 * not succeed, or the connection was lost during confirmation.
+	 * not succeed, or the connection was lost during confirmation. This
+	 * indicates that the protocol has ended unsuccessfully.
 	 */
 	void remoteConfirmationFailed();
+
+	/**
+	 * Informs the local peer of the name used by the remote peer. Called if
+	 * the exchange of pseudonyms succeeds. This indicates that the protocol
+	 * has ended successfully.
+	 */
+	void pseudonymExchangeSucceeded(String remoteName);
+
+	/**
+	 * Called if the exchange of pseudonyms fails. This indicates that the
+	 * protocol has ended unsuccessfully.
+	 */
+	void pseudonymExchangeFailed();
 }

briar-api/src/net/sf/briar/api/invitation/InvitationState.java

@@ -7,12 +7,13 @@ public class InvitationState {
 	private final boolean connectionFailed;
 	private final boolean localCompared, remoteCompared;
 	private final boolean localMatched, remoteMatched;
+	private final String contactName;
 
 	public InvitationState(int localInvitationCode, int remoteInvitationCode,
 			int localConfirmationCode, int remoteConfirmationCode,
 			boolean connectionFailed, boolean localCompared,
 			boolean remoteCompared, boolean localMatched,
-			boolean remoteMatched) {
+			boolean remoteMatched, String contactName) {
 		this.localInvitationCode = localInvitationCode;
 		this.remoteInvitationCode = remoteInvitationCode;
 		this.localConfirmationCode = localConfirmationCode;
@@ -22,6 +23,7 @@ public class InvitationState {
 		this.remoteCompared = remoteCompared;
 		this.localMatched = localMatched;
 		this.remoteMatched = remoteMatched;
+		this.contactName = contactName;
 	}
 
 	public int getLocalInvitationCode() {
@@ -59,4 +61,8 @@ public class InvitationState {
 	public boolean getRemoteMatched() {
 		return remoteMatched;
 	}
+
+	public String getContactName() {
+		return contactName;
+	}
 }

briar-api/src/net/sf/briar/api/invitation/InvitationTaskFactory.java

@@ -1,8 +1,11 @@
 package net.sf.briar.api.invitation;
 
+import net.sf.briar.api.AuthorId;
+
 /** Creates tasks for exchanging invitations with remote peers. */
 public interface InvitationTaskFactory {
 
-	/** Creates a task using the given invitation codes. */
-	InvitationTask createTask(int localCode, int remoteCode);
+	/** Creates a task using the given pseudonym and invitation codes. */
+	InvitationTask createTask(AuthorId localAuthorId, int localCode,
+			int remoteCode);
 }

briar-api/src/net/sf/briar/api/messaging/Group.java

@@ -29,8 +29,9 @@ public class Group {
 	}
 
 	/**
-	 * If the group is restricted, returns the public key that is used to
-	 * authorise all messages sent to the group. Otherwise returns null.
+	 * If the group is restricted, returns the public key used to verify the
+	 * signatures on all messages sent to the group. If the group is
+	 * unrestricted, returns null.
 	 */
 	public byte[] getPublicKey() {
 		return publicKey;

briar-api/src/net/sf/briar/api/messaging/GroupId.java

@@ -2,6 +2,8 @@ package net.sf.briar.api.messaging;
 
 import java.util.Arrays;
 
+import net.sf.briar.api.UniqueId;
+
 /**
  * Type-safe wrapper for a byte array that uniquely identifies a {@link Group}.
  */

briar-api/src/net/sf/briar/api/messaging/LocalGroup.java

@@ -1,6 +1,6 @@
 package net.sf.briar.api.messaging;
 
-/** A restricted group to which the user can post messages. */
+/** A restricted group to which the local user can post messages. */
 public class LocalGroup extends Group {
 
 	private final byte[] privateKey;
@@ -11,7 +11,7 @@ public class LocalGroup extends Group {
 		this.privateKey = privateKey;
 	}
 
-	/** Returns the private key that is used to sign messages. */
+	/** Returns the private key used to sign all messages sent to the group. */
 	public byte[] getPrivateKey() {
 		return privateKey;
 	}

briar-api/src/net/sf/briar/api/messaging/Message.java

@@ -1,5 +1,7 @@
 package net.sf.briar.api.messaging;
 
+import net.sf.briar.api.Author;
+
 public interface Message {
 
 	/** Returns the message's unique identifier. */
@@ -18,8 +20,8 @@ public interface Message {
 	Group getGroup();
 
 	/**
-	 * Returns the message's {@link Author}, or null if this is an anonymous
-	 * message.
+	 * Returns the message's {@link net.sf.briar.api.Author Author}, or null
+	 * if this is an anonymous message.
 	 */
 	Author getAuthor();
 
@@ -33,7 +35,7 @@ public interface Message {
 	 */
 	String getSubject();
 
-	/** Returns the timestamp created by the message's {@link Author}. */
+	/** Returns the message's timestamp. */
 	long getTimestamp();
 
 	/** Returns the serialised message. */

briar-api/src/net/sf/briar/api/messaging/MessageFactory.java

@@ -4,6 +4,8 @@ import java.io.IOException;
 import java.security.GeneralSecurityException;
 import java.security.PrivateKey;
 
+import net.sf.briar.api.Author;
+
 public interface MessageFactory {
 
 	/** Creates a private message. */

briar-api/src/net/sf/briar/api/messaging/MessageId.java

@@ -2,6 +2,8 @@ package net.sf.briar.api.messaging;
 
 import java.util.Arrays;
 
+import net.sf.briar.api.UniqueId;
+
 /**
  * Type-safe wrapper for a byte array that uniquely identifies a
  * {@link Message}.

briar-api/src/net/sf/briar/api/messaging/MessagingConstants.java

@@ -52,5 +52,5 @@ public interface MessagingConstants {
 	 * The timestamp of the oldest message in the database is rounded using
 	 * this modulus to avoid revealing the presence of any particular message.
 	 */
-	long RETENTION_MODULUS = 60 * 60 * 1000; // 1 hour
+	int RETENTION_MODULUS = 60 * 60 * 1000; // 1 hour
 }

briar-api/src/net/sf/briar/api/messaging/Rating.java

@@ -1,4 +1,4 @@
-package net.sf.briar.api;
+package net.sf.briar.api.messaging;
 
 /** The ratings that may be applied to an author in peer moderation. */
 public enum Rating {

briar-api/src/net/sf/briar/api/messaging/TransportAck.java

@@ -1,5 +1,7 @@
 package net.sf.briar.api.messaging;
 
+import net.sf.briar.api.TransportId;
+
 /** A packet acknowledging a {@link TransportUpdate}. */
 public class TransportAck {
 

briar-api/src/net/sf/briar/api/messaging/TransportUpdate.java

@@ -1,5 +1,6 @@
 package net.sf.briar.api.messaging;
 
+import net.sf.briar.api.TransportId;
 import net.sf.briar.api.TransportProperties;
 
 /**

briar-api/src/net/sf/briar/api/messaging/UnverifiedMessage.java

@@ -1,6 +1,8 @@
 package net.sf.briar.api.messaging;
 
-/** A {@link Message} that has not yet had its signatures verified. */
+import net.sf.briar.api.Author;
+
+/** A {@link Message} that has not yet had its signatures (if any) verified. */
 public class UnverifiedMessage {
 
 	private final MessageId parent;
@@ -47,8 +49,8 @@ public class UnverifiedMessage {
 	}
 
 	/**
-	 * Returns the message's {@link Author}, or null if this is an anonymous
-	 * message.
+	 * Returns the message's {@link net.sf.briar.api.Author Author}, or null
+	 * if this is an anonymous message.
 	 */
 	public Author getAuthor() {
 		return author;
@@ -68,7 +70,7 @@ public class UnverifiedMessage {
 		return subject;
 	}
 
-	/** Returns the timestamp created by the message's {@link Author}. */
+	/** Returns the message's timestamp. */
 	public long getTimestamp() {
 		return timestamp;
 	}

briar-api/src/net/sf/briar/api/messaging/duplex/DuplexConnectionFactory.java

@@ -1,13 +1,14 @@
 package net.sf.briar.api.messaging.duplex;
 
 import net.sf.briar.api.ContactId;
-import net.sf.briar.api.messaging.TransportId;
+import net.sf.briar.api.TransportId;
 import net.sf.briar.api.plugins.duplex.DuplexTransportConnection;
 import net.sf.briar.api.transport.ConnectionContext;
 
 public interface DuplexConnectionFactory {
 
-	void createIncomingConnection(ConnectionContext ctx, DuplexTransportConnection d);
+	void createIncomingConnection(ConnectionContext ctx,
+			DuplexTransportConnection d);
 
 	void createOutgoingConnection(ContactId c, TransportId t,
 			DuplexTransportConnection d);

briar-api/src/net/sf/briar/api/messaging/simplex/SimplexConnectionFactory.java

@@ -1,14 +1,15 @@
 package net.sf.briar.api.messaging.simplex;
 
 import net.sf.briar.api.ContactId;
-import net.sf.briar.api.messaging.TransportId;
+import net.sf.briar.api.TransportId;
 import net.sf.briar.api.plugins.simplex.SimplexTransportReader;
 import net.sf.briar.api.plugins.simplex.SimplexTransportWriter;
 import net.sf.briar.api.transport.ConnectionContext;
 
 public interface SimplexConnectionFactory {
 
-	void createIncomingConnection(ConnectionContext ctx, SimplexTransportReader r);
+	void createIncomingConnection(ConnectionContext ctx,
+			SimplexTransportReader r);
 
 	void createOutgoingConnection(ContactId c, TransportId t,
 			SimplexTransportWriter w);

briar-api/src/net/sf/briar/api/plugins/Plugin.java

@@ -4,7 +4,7 @@ import java.io.IOException;
 import java.util.Collection;
 
 import net.sf.briar.api.ContactId;
-import net.sf.briar.api.messaging.TransportId;
+import net.sf.briar.api.TransportId;
 
 public interface Plugin {
 

briar-api/src/net/sf/briar/api/plugins/PluginManager.java

@@ -23,6 +23,6 @@ public interface PluginManager {
 	 */
 	int stop();
 
-	/** Returns any duplex plugins that support invitations. */
+	/** Returns any running duplex plugins that support invitations. */
 	Collection<DuplexPlugin> getInvitationPlugins();
 }

briar-api/src/net/sf/briar/api/plugins/duplex/DuplexPluginFactory.java

@@ -1,6 +1,6 @@
 package net.sf.briar.api.plugins.duplex;
 
-import net.sf.briar.api.messaging.TransportId;
+import net.sf.briar.api.TransportId;
 
 public interface DuplexPluginFactory {
 

briar-api/src/net/sf/briar/api/plugins/simplex/SimplexPluginFactory.java

@@ -1,6 +1,6 @@
 package net.sf.briar.api.plugins.simplex;
 
-import net.sf.briar.api.messaging.TransportId;
+import net.sf.briar.api.TransportId;
 
 public interface SimplexPluginFactory {
 

briar-api/src/net/sf/briar/api/transport/ConnectionContext.java

@@ -1,7 +1,7 @@
 package net.sf.briar.api.transport;
 
 import net.sf.briar.api.ContactId;
-import net.sf.briar.api.messaging.TransportId;
+import net.sf.briar.api.TransportId;
 
 public class ConnectionContext {
 

briar-api/src/net/sf/briar/api/transport/ConnectionDispatcher.java

@@ -1,7 +1,7 @@
 package net.sf.briar.api.transport;
 
 import net.sf.briar.api.ContactId;
-import net.sf.briar.api.messaging.TransportId;
+import net.sf.briar.api.TransportId;
 import net.sf.briar.api.plugins.duplex.DuplexTransportConnection;
 import net.sf.briar.api.plugins.simplex.SimplexTransportReader;
 import net.sf.briar.api.plugins.simplex.SimplexTransportWriter;

briar-api/src/net/sf/briar/api/transport/ConnectionReaderFactory.java

@@ -4,9 +4,11 @@ import java.io.InputStream;
 
 public interface ConnectionReaderFactory {
 
-	/**
-	 * Creates a connection reader for one side of a connection.
-	 */
+	/** Creates a connection reader for one side of a connection. */
 	ConnectionReader createConnectionReader(InputStream in,
 			ConnectionContext ctx, boolean incoming, boolean initiator);
+
+	/** Creates a connection reader for one side of an invitation connection. */
+	ConnectionReader createInvitationConnectionReader(InputStream in,
+			byte[] secret, boolean alice);
 }

briar-api/src/net/sf/briar/api/transport/ConnectionRecogniser.java

@@ -1,8 +1,8 @@
 package net.sf.briar.api.transport;
 
 import net.sf.briar.api.ContactId;
+import net.sf.briar.api.TransportId;
 import net.sf.briar.api.db.DbException;
-import net.sf.briar.api.messaging.TransportId;
 
 /**
  * Maintains the connection reordering windows and decides whether incoming

briar-api/src/net/sf/briar/api/transport/ConnectionRegistry.java

@@ -3,7 +3,7 @@ package net.sf.briar.api.transport;
 import java.util.Collection;
 
 import net.sf.briar.api.ContactId;
-import net.sf.briar.api.messaging.TransportId;
+import net.sf.briar.api.TransportId;
 
 /**
  * Keeps track of which contacts are currently connected by which transports.

briar-api/src/net/sf/briar/api/transport/ConnectionWriterFactory.java

@@ -4,9 +4,11 @@ import java.io.OutputStream;
 
 public interface ConnectionWriterFactory {
 
-	/**
-	 * Creates a connection writer for one side of a connection.
-	 */
+	/** Creates a connection writer for one side of a connection. */
 	ConnectionWriter createConnectionWriter(OutputStream out, long capacity,
 			ConnectionContext ctx, boolean incoming, boolean initiator);
+
+	/** Creates a connection writer for one side of an invitation connection. */
+	ConnectionWriter createInvitationConnectionWriter(OutputStream out,
+			byte[] secret, boolean alice);
 }

briar-api/src/net/sf/briar/api/transport/Endpoint.java

@@ -1,22 +1,20 @@
 package net.sf.briar.api.transport;
 
 import net.sf.briar.api.ContactId;
-import net.sf.briar.api.messaging.TransportId;
+import net.sf.briar.api.TransportId;
 
 public class Endpoint {
 
 	private final ContactId contactId;
 	private final TransportId transportId;
-	private final long epoch, clockDiff, latency;
+	private final long epoch;
 	private final boolean alice;
 
-	public Endpoint(ContactId contactId, TransportId transportId,
-			long epoch, long clockDiff, long latency, boolean alice) {
+	public Endpoint(ContactId contactId, TransportId transportId, long epoch,
+			boolean alice) {
 		this.contactId = contactId;
 		this.transportId = transportId;
 		this.epoch = epoch;
-		this.clockDiff = clockDiff;
-		this.latency = latency;
 		this.alice = alice;
 	}
 
@@ -32,14 +30,6 @@ public class Endpoint {
 		return epoch;
 	}
 
-	public long getClockDifference() {
-		return clockDiff;
-	}
-
-	public long getLatency() {
-		return latency;
-	}
-
 	public boolean getAlice() {
 		return alice;
 	}

briar-api/src/net/sf/briar/api/transport/TemporarySecret.java

@@ -2,7 +2,7 @@ package net.sf.briar.api.transport;
 
 import static net.sf.briar.api.transport.TransportConstants.CONNECTION_WINDOW_SIZE;
 import net.sf.briar.api.ContactId;
-import net.sf.briar.api.messaging.TransportId;
+import net.sf.briar.api.TransportId;
 
 public class TemporarySecret extends Endpoint {
 
@@ -11,10 +11,9 @@ public class TemporarySecret extends Endpoint {
 
 	/** Creates a temporary secret with the given connection window. */
 	public TemporarySecret(ContactId contactId, TransportId transportId,
-			long epoch, long clockDiff, long latency, boolean alice,
-			long period, byte[] secret, long outgoing, long centre,
-			byte[] bitmap) {
-		super(contactId, transportId, epoch, clockDiff, latency, alice);
+			long epoch, boolean alice, long period, byte[] secret,
+			long outgoing, long centre, byte[] bitmap) {
+		super(contactId, transportId, epoch, alice);
 		this.period = period;
 		this.secret = secret;
 		this.outgoing = outgoing;
@@ -24,17 +23,15 @@ public class TemporarySecret extends Endpoint {
 
 	/** Creates a temporary secret with a new connection window. */
 	public TemporarySecret(ContactId contactId, TransportId transportId,
-			long epoch, long clockDiff, long latency, boolean alice,
-			long period, byte[] secret) {
-		this(contactId, transportId, epoch, clockDiff, latency, alice, period,
-				secret, 0, 0, new byte[CONNECTION_WINDOW_SIZE / 8]);
+			long epoch, boolean alice, long period, byte[] secret) {
+		this(contactId, transportId, epoch, alice, period, secret, 0, 0,
+				new byte[CONNECTION_WINDOW_SIZE / 8]);
 	}
 
 	/** Creates a temporary secret derived from the given endpoint. */
 	public TemporarySecret(Endpoint ep, long period, byte[] secret) {
 		this(ep.getContactId(), ep.getTransportId(), ep.getEpoch(),
-				ep.getClockDifference(), ep.getLatency(), ep.getAlice(),
-				period, secret);
+				ep.getAlice(), period, secret);
 	}
 
 	public long getPeriod() {

briar-api/src/net/sf/briar/api/transport/TransportConstants.java

@@ -27,6 +27,9 @@ public interface TransportConstants {
 	 */
 	int MIN_CONNECTION_LENGTH = 1024 * 1024; // 2^20, 1 MiB
 
+	/** The maximum difference between two communicating devices' clocks. */
+	int MAX_CLOCK_DIFFERENCE = 60 * 60 * 1000; // 1 hour
+
 	/** The size of the connection reordering window. */
 	int CONNECTION_WINDOW_SIZE = 32;
 }