Restructured project prior to merging changes from Afsnit repo.

src/.gitignore

@@ -0,0 +1 @@
+/build

src/build.xml

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+<project name='api' default='depend'>
+	<import file='../build-common.xml'/>
+</project>

src/net/sf/briar/api/Bytes.java

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+package net.sf.briar.api;
+
+import java.util.Arrays;
+
+/** A wrapper around a byte array, to allow it to be stored in maps etc. */
+public class Bytes {
+
+	private final byte[] bytes;
+
+	private int hashCode = -1;
+
+	public Bytes(byte[] bytes) {
+		this.bytes = bytes;
+	}
+
+	public byte[] getBytes() {
+		return bytes;
+	}
+
+	@Override
+	public int hashCode() {
+		// Thread-safe because if two or more threads check and update the
+		// value, they'll calculate the same value
+		if(hashCode == -1) hashCode = Arrays.hashCode(bytes);
+		return hashCode;
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if(o instanceof Bytes)
+			return Arrays.equals(bytes, ((Bytes) o).bytes);
+		return false;
+	}
+}

src/net/sf/briar/api/ContactId.java

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+package net.sf.briar.api;
+
+/**
+ * Type-safe wrapper for an integer that uniquely identifies a contact within
+ * the scope of a single node.
+ */
+public class ContactId {
+
+	private final int id;
+
+	public ContactId(int id) {
+		this.id = id;
+	}
+
+	public int getInt() {
+		return id;
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if(o instanceof ContactId) return id == ((ContactId) o).id;
+		return false;
+	}
+
+	@Override
+	public int hashCode() {
+		return id;
+	}
+}

src/net/sf/briar/api/FormatException.java

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+package net.sf.briar.api;
+
+import java.io.IOException;
+
+/** An exception that indicates an unrecoverable formatting error. */
+public class FormatException extends IOException {
+
+	private static final long serialVersionUID = 2274966775687766337L;
+}

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

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+package net.sf.briar.api;
+
+/** The ratings that may be applied to an author in peer moderation. */
+public enum Rating {
+	BAD, UNRATED, GOOD
+}

src/net/sf/briar/api/TransportConfig.java

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+package net.sf.briar.api;
+
+import java.util.Hashtable;
+import java.util.Map;
+
+public class TransportConfig extends Hashtable<String, String> {
+
+	private static final long serialVersionUID = 2330384620787778596L;
+
+	public TransportConfig(Map<String, String> c) {
+		super(c);
+	}
+
+	public TransportConfig() {
+		super();
+	}
+}

src/net/sf/briar/api/TransportProperties.java

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+package net.sf.briar.api;
+
+import java.util.Hashtable;
+import java.util.Map;
+
+public class TransportProperties extends Hashtable<String, String> {
+
+	private static final long serialVersionUID = 7533739534204953625L;
+
+	public TransportProperties(Map<String, String> p) {
+		super(p);
+	}
+
+	public TransportProperties() {
+		super();
+	}
+}

src/net/sf/briar/api/clock/Clock.java

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+package net.sf.briar.api.clock;
+
+/**
+ * An interface for time-related system functions that allows them to be
+ * replaced for testing.
+ */
+public interface Clock {
+
+	/** @see {@link java.lang.System#currentTimeMillis()} */
+	long currentTimeMillis();
+}

src/net/sf/briar/api/clock/SystemClock.java

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+package net.sf.briar.api.clock;
+
+/** Default clock implementation. */
+public class SystemClock implements Clock {
+
+	public long currentTimeMillis() {
+		return System.currentTimeMillis();
+	}
+}

src/net/sf/briar/api/crypto/AuthenticatedCipher.java

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+package net.sf.briar.api.crypto;
+
+import java.security.InvalidKeyException;
+import java.security.Key;
+
+import javax.crypto.BadPaddingException;
+import javax.crypto.IllegalBlockSizeException;
+
+/**
+ * A wrapper for a provider-dependent cipher class, since javax.crypto.Cipher
+ * doesn't support additional authenticated data until Java 7.
+ */
+public interface AuthenticatedCipher {
+
+	/**
+	 * Initializes this cipher with a key, an initialisation vector (IV) and
+	 * additional authenticated data (AAD).
+	 */
+	void init(int opmode, Key key, byte[] iv, byte[] aad)
+			throws InvalidKeyException;
+
+	/** Encrypts or decrypts data in a single-part operation. */
+	int doFinal(byte[] input, int inputOff, int len, byte[] output,
+			int outputOff) throws IllegalBlockSizeException,
+			BadPaddingException;
+
+	/** Returns the length of the message authenticated code (MAC) in bytes. */
+	int getMacLength();
+}

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

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+package net.sf.briar.api.crypto;
+
+import java.security.KeyPair;
+import java.security.PrivateKey;
+import java.security.SecureRandom;
+import java.security.Signature;
+
+import javax.crypto.Cipher;
+
+public interface CryptoComponent {
+
+	/**
+	 * Derives a tag key from the given temporary secret.
+	 * @param alice Indicates whether the key is for connections initiated by
+	 * Alice or Bob.
+	 */
+	ErasableKey deriveTagKey(byte[] secret, boolean alice);
+
+	/**
+	 * Derives a frame key from the given temporary secret and connection
+	 * number.
+	 * @param alice Indicates whether the key is for a connection initiated by
+	 * Alice or Bob.
+	 * @param initiator Indicates whether the key is for the initiator's or the
+	 * responder's side of the connection.
+	 */
+	ErasableKey deriveFrameKey(byte[] secret, long connection, boolean alice,
+			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.
+	 */
+	byte[] deriveInitialSecret(byte[] ourPublicKey, byte[] theirPublicKey,
+			PrivateKey ourPrivateKey, boolean alice);
+
+	/**
+	 * 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);
+
+	/** Encodes the pseudo-random tag that is used to recognise a connection. */
+	void encodeTag(byte[] tag, Cipher tagCipher, ErasableKey tagKey,
+			long connection);
+
+	KeyPair generateAgreementKeyPair();
+
+	KeyPair generateSignatureKeyPair();
+
+	KeyParser getSignatureKeyParser();
+
+	ErasableKey generateTestKey();
+
+	MessageDigest getMessageDigest();
+
+	PseudoRandom getPseudoRandom(int seed);
+
+	SecureRandom getSecureRandom();
+
+	Cipher getTagCipher();
+
+	AuthenticatedCipher getFrameCipher();
+
+	Signature getSignature();
+}

src/net/sf/briar/api/crypto/ErasableKey.java

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+package net.sf.briar.api.crypto;
+
+import javax.crypto.SecretKey;
+
+public interface ErasableKey extends SecretKey {
+
+	/** Returns a copy of the key. */
+	ErasableKey copy();
+
+	/** Erases the key from memory. */
+	void erase();
+}

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

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+package net.sf.briar.api.crypto;
+
+import net.sf.briar.api.ContactId;
+import net.sf.briar.api.db.ContactTransport;
+import net.sf.briar.api.protocol.TransportId;
+import net.sf.briar.api.transport.ConnectionContext;
+
+public interface KeyManager {
+
+	/**
+	 * Starts the key manager and returns true if it started successfully. This
+	 * method must be called after the database has been opened.
+	 */
+	boolean start();
+
+	/** Stops the key manager. */
+	void stop();
+
+	/**
+	 * Returns a connection context for connecting to the given contact over
+	 * the given transport, or null if an error occurs or the contact does not
+	 * support the transport.
+	 */
+	ConnectionContext getConnectionContext(ContactId c, TransportId t);
+
+	/**
+	 * Called whenever a contact transport has been added. The initial secret
+	 * is erased before returning.
+	 */
+	void contactTransportAdded(ContactTransport ct, byte[] initialSecret);
+}

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

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+package net.sf.briar.api.crypto;
+
+import java.security.PublicKey;
+import java.security.spec.InvalidKeySpecException;
+
+public interface KeyParser {
+
+	PublicKey parsePublicKey(byte[] encodedKey) throws InvalidKeySpecException;
+}

src/net/sf/briar/api/crypto/MessageDigest.java

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+package net.sf.briar.api.crypto;
+
+/** An interface that allows a java.security.MessageDigest to be wrapped. */
+public interface MessageDigest {
+
+	/** @see {@link java.security.MessageDigest#digest()} */
+	byte[] digest();
+
+	/** @see {@link java.security.MessageDigest#digest(byte[])} */
+	byte[] digest(byte[] input);
+
+	/** @see {@link java.security.MessageDigest#digest(byte[], int, int)} */
+	int digest(byte[] buf, int offset, int len);
+
+	/** @see {@link java.security.MessageDigest#getDigestLength()} */
+	int getDigestLength();
+
+	/** @see {@link java.security.MessageDigest#reset()} */
+	void reset();
+
+	/** @see {@link java.security.MessageDigest#update(byte)} */
+	void update(byte input);
+
+	/** @see {@link java.security.MessageDigest#update(byte[])} */
+	void update(byte[] input);
+
+	/** @see {@link java.security.MessageDigest#update(byte[], int, int)} */
+	void update(byte[] input, int offset, int len);
+}

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

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+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();
+}

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

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+package net.sf.briar.api.crypto;
+
+public interface PseudoRandom {
+
+	byte[] nextBytes(int bytes);
+}

src/net/sf/briar/api/db/ContactTransport.java

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+package net.sf.briar.api.db;
+
+import net.sf.briar.api.ContactId;
+import net.sf.briar.api.protocol.TransportId;
+
+public class ContactTransport {
+
+	private final ContactId contactId;
+	private final TransportId transportId;
+	private final long epoch, clockDiff, latency;
+	private final boolean alice;
+
+	public ContactTransport(ContactId contactId, TransportId transportId,
+			long epoch, long clockDiff, long latency, boolean alice) {
+		this.contactId = contactId;
+		this.transportId = transportId;
+		this.epoch = epoch;
+		this.clockDiff = clockDiff;
+		this.latency = latency;
+		this.alice = alice;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+
+	public TransportId getTransportId() {
+		return transportId;
+	}
+
+	public long getEpoch() {
+		return epoch;
+	}
+
+	public long getClockDifference() {
+		return clockDiff;
+	}
+
+	public long getLatency() {
+		return latency;
+	}
+
+	public boolean getAlice() {
+		return alice;
+	}
+}

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

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+package net.sf.briar.api.db;
+
+import java.io.IOException;
+import java.util.Collection;
+import java.util.Map;
+
+import net.sf.briar.api.ContactId;
+import net.sf.briar.api.Rating;
+import net.sf.briar.api.TransportConfig;
+import net.sf.briar.api.TransportProperties;
+import net.sf.briar.api.db.event.DatabaseListener;
+import net.sf.briar.api.protocol.Ack;
+import net.sf.briar.api.protocol.AuthorId;
+import net.sf.briar.api.protocol.Batch;
+import net.sf.briar.api.protocol.Group;
+import net.sf.briar.api.protocol.GroupId;
+import net.sf.briar.api.protocol.Message;
+import net.sf.briar.api.protocol.MessageId;
+import net.sf.briar.api.protocol.Offer;
+import net.sf.briar.api.protocol.RawBatch;
+import net.sf.briar.api.protocol.Request;
+import net.sf.briar.api.protocol.SubscriptionUpdate;
+import net.sf.briar.api.protocol.Transport;
+import net.sf.briar.api.protocol.TransportId;
+import net.sf.briar.api.protocol.TransportUpdate;
+
+/**
+ * Encapsulates the database implementation and exposes high-level operations
+ * to other components.
+ */
+public interface DatabaseComponent {
+
+	/**
+	 * Opens the database.
+	 * @param resume True to reopen an existing database or false to create a
+	 * new one.
+	 */
+	void open(boolean resume) throws DbException, IOException;
+
+	/** Waits for any open transactions to finish and closes the database. */
+	void close() throws DbException, IOException;
+
+	/** Adds a listener to be notified when database events occur. */
+	void addListener(DatabaseListener d);
+
+	/** Removes a listener. */
+	void removeListener(DatabaseListener d);
+
+	/**
+	 * Adds a new contact to the database and returns an ID for the contact.
+	 */
+	ContactId addContact() throws DbException;
+
+	/** Adds a contact transport to the database. */
+	void addContactTransport(ContactTransport ct) throws DbException;
+
+	/** Adds a locally generated group message to the database. */
+	void addLocalGroupMessage(Message m) throws DbException;
+
+	/** Adds a locally generated private message to the database. */
+	void addLocalPrivateMessage(Message m, ContactId c) throws DbException;
+
+	/**
+	 * Stores the given temporary secrets and deletes any secrets that have
+	 * been made obsolete.
+	 */
+	void addSecrets(Collection<TemporarySecret> secrets) throws DbException;
+
+	/**
+	 * Generates an acknowledgement for the given contact. Returns null if
+	 * there are no batches to acknowledge.
+	 */
+	Ack generateAck(ContactId c, int maxBatches) throws DbException;
+
+	/**
+	 * Generates a batch of messages for the given contact. Returns null if
+	 * there are no sendable messages that fit in the given capacity.
+	 */
+	RawBatch generateBatch(ContactId c, int capacity) throws DbException;
+
+	/**
+	 * Generates a batch of messages for the given contact from the given
+	 * collection of requested messages. Any messages that were either added to
+	 * the batch, or were considered but are no longer sendable to the contact,
+	 * are removed from the collection of requested messages before returning.
+	 * Returns null if there are no sendable messages that fit in the given
+	 * capacity.
+	 */
+	RawBatch generateBatch(ContactId c, int capacity,
+			Collection<MessageId> requested) throws DbException;
+
+	/**
+	 * Generates an offer for the given contact. Returns null if there are no
+	 * messages to offer.
+	 */
+	Offer generateOffer(ContactId c, int maxMessages) throws DbException;
+
+	/**
+	 * Generates a subscription update for the given contact. Returns null if
+	 * an update is not due.
+	 */
+	SubscriptionUpdate generateSubscriptionUpdate(ContactId c)
+			throws DbException;
+
+	/**
+	 * Generates a transport update for the given contact. Returns null if an
+	 * update is not due.
+	 */
+	TransportUpdate generateTransportUpdate(ContactId c) throws DbException;
+
+	/** Returns the configuration for the given transport. */
+	TransportConfig getConfig(TransportId t) throws DbException;
+
+	/** Returns the IDs of all contacts. */
+	Collection<ContactId> getContacts() throws DbException;
+
+	/** Returns the local transport properties for the given transport. */
+	TransportProperties getLocalProperties(TransportId t) throws DbException;
+
+	/** Returns all local transports. */
+	Collection<Transport> getLocalTransports() throws DbException;
+
+	/** Returns the headers of all messages in the given group. */
+	Collection<MessageHeader> getMessageHeaders(GroupId g) throws DbException;
+
+	/** Returns the user's rating for the given author. */
+	Rating getRating(AuthorId a) throws DbException;
+
+	/** Returns all remote transport properties for the given transport. */
+	Map<ContactId, TransportProperties> getRemoteProperties(TransportId t)
+			throws DbException;
+
+	/** Returns all temporary secrets. */
+	Collection<TemporarySecret> getSecrets() throws DbException;
+
+	/** Returns the set of groups to which the user subscribes. */
+	Collection<Group> getSubscriptions() throws DbException;
+
+	/** Returns the number of unread messages in each subscribed group. */
+	Map<GroupId, Integer> getUnreadMessageCounts() throws DbException;
+
+	/** Returns the contacts to which the given group is visible. */
+	Collection<ContactId> getVisibility(GroupId g) throws DbException;
+
+	/** Returns true if any messages are sendable to the given contact. */
+	boolean hasSendableMessages(ContactId c) throws DbException;
+
+	/**
+	 * Increments the outgoing connection counter for the given contact
+	 * transport in the given rotation period and returns the old value.
+	 */
+	long incrementConnectionCounter(ContactId c, TransportId t, long period)
+			throws DbException;
+
+	/** Processes an acknowledgement from the given contact. */
+	void receiveAck(ContactId c, Ack a) throws DbException;
+
+	/** Processes a batch of messages from the given contact. */
+	void receiveBatch(ContactId c, Batch b) throws DbException;
+
+	/**
+	 * Processes an offer from the given contact and generates a request for
+	 * any messages in the offer that the contact should send. To prevent
+	 * contacts from using offers to test for subscriptions that are not
+	 * visible to them, any messages belonging to groups that are not visible
+	 * to the contact are requested just as though they were not present in the
+	 * database.
+	 */
+	Request receiveOffer(ContactId c, Offer o) throws DbException;
+
+	/** Processes a subscription update from the given contact. */
+	void receiveSubscriptionUpdate(ContactId c, SubscriptionUpdate s)
+			throws DbException;
+
+	/** Processes a transport update from the given contact. */
+	void receiveTransportUpdate(ContactId c, TransportUpdate t)
+			throws DbException;
+
+	/** Removes a contact (and all associated state) from the database. */
+	void removeContact(ContactId c) throws DbException;
+
+	/**
+	 * Sets the configuration for the given transport, replacing any existing
+	 * configuration for that transport.
+	 */
+	void setConfig(TransportId t, TransportConfig c) throws DbException;
+
+	/**
+	 * Sets the connection reordering window for the given contact transport
+	 * in the given rotation period.
+	 */
+	void setConnectionWindow(ContactId c, TransportId t, long period,
+			long centre, byte[] bitmap) throws DbException;
+
+	/**
+	 * Sets the local transport properties for the given transport, replacing
+	 * any existing properties for that transport.
+	 */
+	void setLocalProperties(TransportId t, TransportProperties p)
+			throws DbException;
+
+	/** Records the user's rating for the given author. */
+	void setRating(AuthorId a, Rating r) throws DbException;
+
+	/** Records the given messages as having been seen by the given contact. */
+	void setSeen(ContactId c, Collection<MessageId> seen) throws DbException;
+
+	/**
+	 * Makes the given group visible to the given set of contacts and invisible
+	 * to any other contacts.
+	 */
+	void setVisibility(GroupId g, Collection<ContactId> visible)
+			throws DbException;
+
+	/** Subscribes to the given group. */
+	void subscribe(Group g) throws DbException;
+
+	/**
+	 * Unsubscribes from the given group. Any messages belonging to the group
+	 * are deleted from the database.
+	 */
+	void unsubscribe(GroupId g) throws DbException;
+}

src/net/sf/briar/api/db/DatabaseDirectory.java

@@ -0,0 +1,15 @@
+package net.sf.briar.api.db;
+
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import com.google.inject.BindingAnnotation;
+
+/** Annotation for injecting the directory where the database is stored. */
+@BindingAnnotation
+@Target({ PARAMETER })
+@Retention(RUNTIME)
+public @interface DatabaseDirectory {}

src/net/sf/briar/api/db/DatabaseExecutor.java

@@ -0,0 +1,15 @@
+package net.sf.briar.api.db;
+
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import com.google.inject.BindingAnnotation;
+
+/** Annotation for injecting the executor for database tasks. */
+@BindingAnnotation
+@Target({ PARAMETER })
+@Retention(RUNTIME)
+public @interface DatabaseExecutor {}

src/net/sf/briar/api/db/DatabaseMaxSize.java

@@ -0,0 +1,15 @@
+package net.sf.briar.api.db;
+
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import com.google.inject.BindingAnnotation;
+
+/** Annotation for injecting the maximum size in bytes of the database. */
+@BindingAnnotation
+@Target({ PARAMETER })
+@Retention(RUNTIME)
+public @interface DatabaseMaxSize {}

src/net/sf/briar/api/db/DatabasePassword.java

@@ -0,0 +1,18 @@
+package net.sf.briar.api.db;
+
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import com.google.inject.BindingAnnotation;
+
+/**
+ * Annotation for injecting the password from which the database encryption
+ * key is derived.
+ */
+@BindingAnnotation
+@Target({ PARAMETER })
+@Retention(RUNTIME)
+public @interface DatabasePassword {}

src/net/sf/briar/api/db/DbException.java

@@ -0,0 +1,14 @@
+package net.sf.briar.api.db;
+
+public class DbException extends Exception {
+
+	private static final long serialVersionUID = 3706581789209939441L;
+
+	public DbException() {
+		super();
+	}
+
+	public DbException(Throwable t) {
+		super(t);
+	}
+}

src/net/sf/briar/api/db/MessageHeader.java

@@ -0,0 +1,35 @@
+package net.sf.briar.api.db;
+
+import net.sf.briar.api.protocol.AuthorId;
+import net.sf.briar.api.protocol.GroupId;
+import net.sf.briar.api.protocol.MessageId;
+
+public interface MessageHeader {
+
+	/** Returns the message's unique identifier. */
+	MessageId getId();
+
+	/**
+	 * Returns the message's parent, or null if this is the first message in a
+	 * thread.
+	 */
+	MessageId getParent();
+
+	/** Returns the group to which the message belongs. */
+	GroupId getGroup();
+
+	/** Returns the message's author. */
+	AuthorId getAuthor();
+
+	/** Returns the message's subject line. */
+	String getSubject();
+
+	/** Returns the timestamp created by the message's author. */
+	long getTimestamp();
+
+	/** Returns true if the message has been read. */
+	boolean getRead();
+
+	/** Returns true if the message has been starred. */
+	boolean getStarred();
+}

src/net/sf/briar/api/db/NoSuchContactException.java

@@ -0,0 +1,10 @@
+package net.sf.briar.api.db;
+
+/**
+ * Thrown when a database operation is attempted for a contact that is not in
+ * the database.
+ */
+public class NoSuchContactException extends DbException {
+
+	private static final long serialVersionUID = -7048538231308207386L;
+}

src/net/sf/briar/api/db/NoSuchContactTransportException.java

@@ -0,0 +1,10 @@
+package net.sf.briar.api.db;
+
+/**
+ * Thrown when a database operation is attempted for a contact transport that
+ * is not in the database.
+ */
+public class NoSuchContactTransportException extends DbException {
+
+	private static final long serialVersionUID = -6274982612759573100L;
+}

src/net/sf/briar/api/db/Status.java

@@ -0,0 +1,11 @@
+package net.sf.briar.api.db;
+
+/** The status of a message with respect to a particular contact. */
+public enum Status {
+	/** The message has not been sent, received, or acked. */
+	NEW,
+	/** The message has been sent, but not received or acked. */
+	SENT,
+	/** The message has been received or acked. */
+	SEEN
+}

src/net/sf/briar/api/db/TemporarySecret.java

@@ -0,0 +1,59 @@
+package net.sf.briar.api.db;
+
+import static net.sf.briar.api.transport.TransportConstants.CONNECTION_WINDOW_SIZE;
+import net.sf.briar.api.ContactId;
+import net.sf.briar.api.protocol.TransportId;
+
+public class TemporarySecret extends ContactTransport {
+
+	private final long period, outgoing, centre;
+	private final byte[] secret, bitmap;
+
+	/** 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);
+		this.period = period;
+		this.secret = secret;
+		this.outgoing = outgoing;
+		this.centre = centre;
+		this.bitmap = bitmap;
+	}
+
+	/** 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, 0L, 0L, new byte[CONNECTION_WINDOW_SIZE / 8]);
+	}
+
+	/** Creates a temporary secret derived from the given contact transport. */
+	public TemporarySecret(ContactTransport ct, long period, byte[] secret) {
+		this(ct.getContactId(), ct.getTransportId(), ct.getEpoch(),
+				ct.getClockDifference(), ct.getLatency(), ct.getAlice(),
+				period, secret);
+	}
+
+	public long getPeriod() {
+		return period;
+	}
+
+	public byte[] getSecret() {
+		return secret;
+	}
+
+	public long getOutgoingConnectionCounter() {
+		return outgoing;
+	}
+
+	public long getWindowCentre() {
+		return centre;
+	}
+
+	public byte[] getWindowBitmap() {
+		return bitmap;
+	}
+}

src/net/sf/briar/api/db/event/BatchReceivedEvent.java

@@ -0,0 +1,6 @@
+package net.sf.briar.api.db.event;
+
+/** An event that is broadcast when a batch of messages is received. */
+public class BatchReceivedEvent extends DatabaseEvent {
+
+}

src/net/sf/briar/api/db/event/ContactAddedEvent.java

@@ -0,0 +1,17 @@
+package net.sf.briar.api.db.event;
+
+import net.sf.briar.api.ContactId;
+
+/** An event that is broadcast when a contact is added. */
+public class ContactAddedEvent extends DatabaseEvent {
+
+	private final ContactId contactId;
+
+	public ContactAddedEvent(ContactId contactId) {
+		this.contactId = contactId;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+}

src/net/sf/briar/api/db/event/ContactRemovedEvent.java

@@ -0,0 +1,17 @@
+package net.sf.briar.api.db.event;
+
+import net.sf.briar.api.ContactId;
+
+/** An event that is broadcast when a contact is removed. */
+public class ContactRemovedEvent extends DatabaseEvent {
+
+	private final ContactId contactId;
+
+	public ContactRemovedEvent(ContactId contactId) {
+		this.contactId = contactId;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+}

src/net/sf/briar/api/db/event/DatabaseEvent.java

@@ -0,0 +1,6 @@
+package net.sf.briar.api.db.event;
+
+/** An abstract superclass for database events. */
+public abstract class DatabaseEvent {
+
+}

src/net/sf/briar/api/db/event/DatabaseListener.java

@@ -0,0 +1,7 @@
+package net.sf.briar.api.db.event;
+
+/** An interface for receiving notifications when database events occur. */
+public interface DatabaseListener {
+
+	void eventOccurred(DatabaseEvent e);
+}

src/net/sf/briar/api/db/event/LocalTransportsUpdatedEvent.java

@@ -0,0 +1,9 @@
+package net.sf.briar.api.db.event;
+
+/**
+ * An event that is broadcast when the local transport properties are
+ * updated.
+ */
+public class LocalTransportsUpdatedEvent extends DatabaseEvent {
+
+}

src/net/sf/briar/api/db/event/MessagesAddedEvent.java

@@ -0,0 +1,9 @@
+package net.sf.briar.api.db.event;
+
+/**
+ * An event that is broadcast when one or more messages are added to the
+ * database.
+ */
+public class MessagesAddedEvent extends DatabaseEvent {
+
+}

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

@@ -0,0 +1,23 @@
+package net.sf.briar.api.db.event;
+
+import net.sf.briar.api.Rating;
+import net.sf.briar.api.protocol.AuthorId;
+
+public class RatingChangedEvent extends DatabaseEvent {
+
+	private final AuthorId author;
+	private final Rating rating;
+
+	public RatingChangedEvent(AuthorId author, Rating rating) {
+		this.author = author;
+		this.rating = rating;
+	}
+
+	public AuthorId getAuthor() {
+		return author;
+	}
+
+	public Rating getRating() {
+		return rating;
+	}
+}

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

@@ -0,0 +1,27 @@
+package net.sf.briar.api.db.event;
+
+import java.util.Collection;
+
+import net.sf.briar.api.ContactId;
+import net.sf.briar.api.protocol.Transport;
+
+/** An event that is broadcast when a contact's transports are updated. */
+public class RemoteTransportsUpdatedEvent extends DatabaseEvent {
+
+	private final ContactId contactId;
+	private final Collection<Transport> transports;
+
+	public RemoteTransportsUpdatedEvent(ContactId contactId,
+			Collection<Transport> transports) {
+		this.contactId = contactId;
+		this.transports = transports;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+
+	public Collection<Transport> getTransports() {
+		return transports;
+	}
+}

src/net/sf/briar/api/db/event/SubscriptionsUpdatedEvent.java

@@ -0,0 +1,28 @@
+package net.sf.briar.api.db.event;
+
+import java.util.Collection;
+import java.util.Collections;
+
+import net.sf.briar.api.ContactId;
+
+/**
+ * An event that is broadcast when the set of subscriptions visible to one or
+ * more contacts is updated.
+ */
+public class SubscriptionsUpdatedEvent extends DatabaseEvent {
+
+	private final Collection<ContactId> affectedContacts;
+
+	public SubscriptionsUpdatedEvent() {
+		affectedContacts = Collections.emptyList();
+	}
+
+	public SubscriptionsUpdatedEvent(Collection<ContactId> affectedContacts) {
+		this.affectedContacts = affectedContacts;
+	}
+
+	/** Returns the contacts affected by the update. */
+	public Collection<ContactId> getAffectedContacts() {
+		return affectedContacts;
+	}
+}

src/net/sf/briar/api/i18n/FontManager.java

@@ -0,0 +1,23 @@
+package net.sf.briar.api.i18n;
+
+import java.awt.Font;
+import java.io.File;
+import java.util.Locale;
+
+public interface FontManager {
+
+	/**
+	 * Initializes the FontManager for the given locale. Fonts are loaded from
+	 * the given directory if they cannot be loaded from the running jar.
+	 */
+	void initialize(Locale locale, File dir);
+
+	/** Returns the appropriate font for the given language. */
+	Font getFontForLanguage(String language);
+
+	/** Returns the current user interface font. */
+	Font getUiFont();
+
+	/** Sets the user interface font appropriately for the given language. */
+	void setUiFontForLanguage(String language);
+}

src/net/sf/briar/api/i18n/I18n.java

@@ -0,0 +1,53 @@
+package net.sf.briar.api.i18n;
+
+import java.awt.ComponentOrientation;
+import java.awt.Font;
+import java.io.File;
+import java.io.IOException;
+import java.util.Locale;
+
+public interface I18n {
+
+	/** Returns the named string, translated for the current i18n locale. */
+	String tr(String name);
+
+	/** Returns the i18n locale. This may not match the system locale. */
+	Locale getLocale();
+
+	/** Sets the i18n locale. */
+	void setLocale(Locale locale);
+
+	/** Loads the i18n locale from Briar/Data/locale.cfg. */
+	void loadLocale() throws IOException;
+
+	/** Saves the i18n locale to Briar/Data/locale.cfg. */
+	void saveLocale() throws IOException;
+
+	/** Loads the i18n locale from the given file. */
+	void loadLocale(File f) throws IOException;
+
+	/** Saves the i18n locale to the given file. */
+	void saveLocale(File f) throws IOException;
+
+	/** Returns the ComponentOrientation of the current i18n locale. */
+	ComponentOrientation getComponentOrientation();
+
+	/** Registers a listener for changes to the i18n locale. */
+	void addListener(Listener l);
+
+	/** Unregisters a listener for changes to the i18n locale. */
+	void removeListener(Listener l);
+
+	/**
+	 * Implemented by classes that wish to be informed of changes to the i18n
+	 * locale.
+	 */
+	public interface Listener {
+
+		/**
+		 * Called whenever the i18n locale changes.
+		 * @param uiFont The user interface font for the new locale.
+		 */
+		void localeChanged(Font uiFont);
+	}
+}

src/net/sf/briar/api/i18n/Stri18ng.java

@@ -0,0 +1,49 @@
+package net.sf.briar.api.i18n;
+
+/** A named translatable string. */
+public class Stri18ng {
+
+	private static final String HTML_OPEN_LEFT = "<html><body align='left'>";
+	private static final String HTML_OPEN_RIGHT = "<html><body align='right'>";
+	private static final String HTML_CLOSE = "</body></html>";
+	private static final String PARAGRAPH = "<p><p>"; // Yes, two of them
+
+	private final String name;
+	private final I18n i18n;
+
+	public Stri18ng(String name, I18n i18n) {
+		this.name = name;
+		this.i18n = i18n;
+	}
+
+	/** Returns the string translated for the current i18n locale. */
+	public String tr() {
+		return i18n.tr(name);
+	}
+
+	/** Returns the string, translated for the current i18n locale, as HTML. */
+	public String html() {
+		if(i18n.getComponentOrientation().isLeftToRight())
+			return HTML_OPEN_LEFT + i18n.tr(name) + HTML_CLOSE;
+		else return HTML_OPEN_RIGHT + i18n.tr(name) + HTML_CLOSE;
+	}
+
+	/**
+	 * Returns the string, translated for the current locale, as HTML.
+	 * @param paras Additional (pre-translated) paragraphs that should be
+	 * appended to the HTML.
+	 */
+	public String html(String... paras) {
+		StringBuilder s = new StringBuilder();
+		if(i18n.getComponentOrientation().isLeftToRight())
+			s.append(HTML_OPEN_LEFT);
+		else s.append(HTML_OPEN_RIGHT);
+		s.append(tr());
+		for(String para : paras) {
+			s.append(PARAGRAPH);
+			s.append(para);
+		}
+		s.append(HTML_CLOSE);
+		return s.toString();
+	}
+}

src/net/sf/briar/api/lifecycle/ShutdownManager.java

@@ -0,0 +1,16 @@
+package net.sf.briar.api.lifecycle;
+
+public interface ShutdownManager {
+
+	/**
+	 * Registers a hook to be run when the JVM shuts down and returns a handle
+	 * that can be used to remove the hook.
+	 */
+	int addShutdownHook(Runnable hook);
+
+	/**
+	 * Removes the shutdown hook identified by the given handle and returns
+	 * true if the hook was removed.
+	 */
+	boolean removeShutdownHook(int handle);
+}

src/net/sf/briar/api/plugins/InvitationConstants.java

@@ -0,0 +1,14 @@
+package net.sf.briar.api.plugins;
+
+public interface InvitationConstants {
+
+	long INVITATION_TIMEOUT = 60 * 1000; // 1 minute
+
+	int CODE_BITS = 19; // Codes must fit into six decimal digits
+
+	int MAX_CODE = 1 << CODE_BITS - 1;
+
+	int HASH_LENGTH = 48;
+
+	int MAX_PUBLIC_KEY_LENGTH = 120;
+}

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

@@ -0,0 +1,38 @@
+package net.sf.briar.api.plugins;
+
+import java.io.IOException;
+import java.util.Collection;
+
+import net.sf.briar.api.ContactId;
+import net.sf.briar.api.protocol.TransportId;
+
+public interface Plugin {
+
+	/** Returns the plugin's transport identifier. */
+	TransportId getId();
+
+	/** Starts the plugin. */
+	void start() throws IOException;
+
+	/** Stops the plugin. */
+	void stop() throws IOException;
+
+	/**
+	 * Returns true if the plugin's poll() method should be called
+	 * periodically to attempt to establish connections.
+	 */
+	boolean shouldPoll();
+
+	/**
+	 * Returns the desired interval in milliseconds between calls to the
+	 * plugin's poll() method.
+	 */
+	long getPollingInterval();
+
+	/**
+	 * Attempts to establish connections to contacts, passing any created
+	 * connections to the callback. To avoid creating redundant connections,
+	 * the plugin may exclude the given contacts from polling.
+	 */
+	void poll(Collection<ContactId> connected);
+}

src/net/sf/briar/api/plugins/PluginCallback.java

@@ -0,0 +1,50 @@
+package net.sf.briar.api.plugins;
+
+import java.util.Map;
+
+import net.sf.briar.api.ContactId;
+import net.sf.briar.api.TransportConfig;
+import net.sf.briar.api.TransportProperties;
+
+/**
+ * An interface through which a transport plugin interacts with the rest of
+ * the application.
+ */
+public interface PluginCallback {
+
+	/** Returns the plugin's configuration. */
+	TransportConfig getConfig();
+
+	/** Returns the plugin's local transport properties. */
+	TransportProperties getLocalProperties();
+
+	/** Returns the plugin's remote transport properties. */
+	Map<ContactId, TransportProperties> getRemoteProperties();
+
+	/** Stores the plugin's configuration. */
+	void setConfig(TransportConfig c);
+
+	/** Stores the plugin's local transport properties. */
+	void setLocalProperties(TransportProperties p);
+
+	/**
+	 * Presents the user with a choice among two or more named options and
+	 * returns the user's response. The message may consist of a translatable
+	 * format string and arguments.
+	 * @return An index into the array of options indicating the user's choice,
+	 * or -1 if the user cancelled the choice.
+	 */
+	int showChoice(String[] options, String... message);
+
+	/**
+	 * Asks the user to confirm an action and returns the user's response. The
+	 * message may consist of a translatable format string and arguments.
+	 */
+	boolean showConfirmationMessage(String... message);
+
+	/**
+	 * Shows a message to the user. The message may consist of a translatable
+	 * format string and arguments.
+	 */
+	void showMessage(String... message);
+}

src/net/sf/briar/api/plugins/PluginExecutor.java

@@ -0,0 +1,15 @@
+package net.sf.briar.api.plugins;
+
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import com.google.inject.BindingAnnotation;
+
+/** Annotation for injecting the executor used by transport plugins. */
+@BindingAnnotation
+@Target({ PARAMETER })
+@Retention(RUNTIME)
+public @interface PluginExecutor {}

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

@@ -0,0 +1,23 @@
+package net.sf.briar.api.plugins;
+
+import java.util.Collection;
+
+import net.sf.briar.api.plugins.duplex.DuplexPlugin;
+
+public interface PluginManager {
+
+	/**
+	 * Starts the plugins and returns the number of plugins successfully
+	 * started. This method must not be called until the database has been
+	 * opened.
+	 */
+	int start();
+
+	/**
+	 * Stops the plugins and returns the number of plugins successfully stopped.
+	 */
+	int stop();
+
+	/** Returns any duplex plugins that support invitations. */
+	Collection<DuplexPlugin> getInvitationPlugins();
+}

src/net/sf/briar/api/plugins/duplex/DuplexPlugin.java

@@ -0,0 +1,31 @@
+package net.sf.briar.api.plugins.duplex;
+
+import net.sf.briar.api.ContactId;
+import net.sf.briar.api.crypto.PseudoRandom;
+import net.sf.briar.api.plugins.Plugin;
+
+/** An interface for transport plugins that support duplex communication. */
+public interface DuplexPlugin extends Plugin {
+
+	/**
+	 * Attempts to create and return a connection to the given contact using
+	 * the current transport and configuration properties. Returns null if a
+	 * connection could not be created.
+	 */
+	DuplexTransportConnection createConnection(ContactId c);
+
+	/** Returns true if the plugin supports exchanging invitations. */
+	boolean supportsInvitations();
+
+	/**
+	 * Starts the invitation process from the inviter's side. Returns null if
+	 * no connection can be established within the given timeout.
+	 */
+	DuplexTransportConnection sendInvitation(PseudoRandom r, long timeout);
+
+	/**
+	 * Starts the invitation process from the invitee's side. Returns null if
+	 * no connection can be established within the given timeout.
+	 */
+	DuplexTransportConnection acceptInvitation(PseudoRandom r, long timeout);
+}

src/net/sf/briar/api/plugins/duplex/DuplexPluginCallback.java

@@ -0,0 +1,14 @@
+package net.sf.briar.api.plugins.duplex;
+
+import net.sf.briar.api.ContactId;
+import net.sf.briar.api.plugins.PluginCallback;
+
+/**
+ * An interface for handling connections created by a duplex transport plugin.
+ */
+public interface DuplexPluginCallback extends PluginCallback {
+
+	void incomingConnectionCreated(DuplexTransportConnection d);
+
+	void outgoingConnectionCreated(ContactId c, DuplexTransportConnection d);
+}

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

@@ -0,0 +1,9 @@
+package net.sf.briar.api.plugins.duplex;
+
+import java.util.concurrent.Executor;
+
+public interface DuplexPluginFactory {
+
+	DuplexPlugin createPlugin(Executor pluginExecutor,
+			DuplexPluginCallback callback);
+}

src/net/sf/briar/api/plugins/duplex/DuplexTransportConnection.java

@@ -0,0 +1,32 @@
+package net.sf.briar.api.plugins.duplex;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+/**
+ * An interface for reading and writing data over a duplex transport. The
+ * connection is not responsible for encrypting/decrypting or authenticating
+ * the data.
+ */
+public interface DuplexTransportConnection {
+
+	/** Returns an input stream for reading from the connection. */
+	InputStream getInputStream() throws IOException;
+
+	/** Returns an output stream for writing to the connection. */
+	OutputStream getOutputStream() throws IOException;
+
+	/**
+	 * Returns true if the output stream should be flushed after each packet.
+	 */
+	boolean shouldFlush();
+
+	/**
+	 * Closes the connection and disposes of any associated resources. The
+	 * first argument indicates whether the connection is being closed because
+	 * of an exception and the second argument indicates whether the connection
+	 * was recognised, which may affect how resources are disposed of.
+	 */
+	void dispose(boolean exception, boolean recognised) throws IOException;
+}

src/net/sf/briar/api/plugins/simplex/SimplexPlugin.java

@@ -0,0 +1,22 @@
+package net.sf.briar.api.plugins.simplex;
+
+import net.sf.briar.api.ContactId;
+import net.sf.briar.api.plugins.Plugin;
+
+/** An interface for transport plugins that support simplex communication. */
+public interface SimplexPlugin extends Plugin {
+
+	/**
+	 * Attempts to create and return a reader for the given contact using the
+	 * current transport and configuration properties. Returns null if a reader
+	 * could not be created.
+	 */
+	SimplexTransportReader createReader(ContactId c);
+
+	/**
+	 * Attempts to create and return a writer for the given contact using the
+	 * current transport and configuration properties. Returns null if a writer
+	 * could not be created.
+	 */
+	SimplexTransportWriter createWriter(ContactId c);
+}

src/net/sf/briar/api/plugins/simplex/SimplexPluginCallback.java

@@ -0,0 +1,15 @@
+package net.sf.briar.api.plugins.simplex;
+
+import net.sf.briar.api.ContactId;
+import net.sf.briar.api.plugins.PluginCallback;
+
+/**
+ * An interface for handling readers and writers created by a simplex transport
+ * plugin.
+ */
+public interface SimplexPluginCallback extends PluginCallback {
+
+	void readerCreated(SimplexTransportReader r);
+
+	void writerCreated(ContactId c, SimplexTransportWriter w);
+}

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

@@ -0,0 +1,9 @@
+package net.sf.briar.api.plugins.simplex;
+
+import java.util.concurrent.Executor;
+
+public interface SimplexPluginFactory {
+
+	SimplexPlugin createPlugin(Executor pluginExecutor,
+			SimplexPluginCallback callback);
+}

src/net/sf/briar/api/plugins/simplex/SimplexTransportReader.java

@@ -0,0 +1,23 @@
+package net.sf.briar.api.plugins.simplex;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * An interface for reading data from a simplex transport. The reader is not
+ * responsible for decrypting or authenticating the data before returning it.
+ */
+public interface SimplexTransportReader {
+
+	/** Returns an input stream for reading from the transport. 
+	 * @throws IOException */
+	InputStream getInputStream() throws IOException;
+
+	/**
+	 * Closes the reader and disposes of any associated resources. The first
+	 * argument indicates whether the reader is being closed because of an
+	 * exception and the second argument indicates whether the connection was
+	 * recognised, which may affect how resources are disposed of.
+	 */
+	void dispose(boolean exception, boolean recognised) throws IOException;
+}

src/net/sf/briar/api/plugins/simplex/SimplexTransportWriter.java

@@ -0,0 +1,30 @@
+package net.sf.briar.api.plugins.simplex;
+
+import java.io.IOException;
+import java.io.OutputStream;
+
+/**
+ * An interface for writing data to a simplex transport. The writer is not
+ * responsible for authenticating or encrypting the data before writing it.
+ */
+public interface SimplexTransportWriter {
+
+	/** Returns the capacity of the transport in bytes. */
+	long getCapacity();
+
+	/** Returns an output stream for writing to the transport. 
+	 * @throws IOException */
+	OutputStream getOutputStream() throws IOException;
+
+	/**
+	 * Returns true if the output stream should be flushed after each packet.
+	 */
+	boolean shouldFlush();
+
+	/**
+	 * Closes the writer and disposes of any associated resources. The
+	 * argument indicates whether the writer is being closed because of an
+	 * exception, which may affect how resources are disposed of.
+	 */
+	void dispose(boolean exception) throws IOException;
+}

src/net/sf/briar/api/protocol/Ack.java

@@ -0,0 +1,10 @@
+package net.sf.briar.api.protocol;
+
+import java.util.Collection;
+
+/** A packet acknowledging receipt of one or more batches. */
+public interface Ack {
+
+	/** Returns the IDs of the acknowledged batches. */
+	Collection<BatchId> getBatchIds();
+}

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

@@ -0,0 +1,17 @@
+package net.sf.briar.api.protocol;
+
+/** A pseudonymous author of messages. */
+public interface Author {
+
+	/** Returns the author's unique identifier. */
+	AuthorId getId();
+
+	/** Returns the author's name. */
+	String getName();
+
+	/**
+	 * Returns the public key that is used to verify messages signed by the
+	 * author.
+	 */
+	byte[] getPublicKey();
+}

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

@@ -0,0 +1,10 @@
+package net.sf.briar.api.protocol;
+
+import java.io.IOException;
+
+public interface AuthorFactory {
+
+	Author createAuthor(String name, byte[] publicKey) throws IOException;
+
+	Author createAuthor(AuthorId id, String name, byte[] publicKey);
+}

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

@@ -0,0 +1,18 @@
+package net.sf.briar.api.protocol;
+
+import java.util.Arrays;
+
+/** Type-safe wrapper for a byte array that uniquely identifies an author. */
+public class AuthorId extends UniqueId {
+
+	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;
+	}
+}

src/net/sf/briar/api/protocol/Batch.java

@@ -0,0 +1,13 @@
+package net.sf.briar.api.protocol;
+
+import java.util.Collection;
+
+/** An incoming packet containing messages. */
+public interface Batch {
+
+	/** Returns the batch's unique identifier. */
+	BatchId getId();
+
+	/** Returns the messages contained in the batch. */
+	Collection<Message> getMessages();
+}

src/net/sf/briar/api/protocol/BatchId.java

@@ -0,0 +1,21 @@
+package net.sf.briar.api.protocol;
+
+import java.util.Arrays;
+
+/**
+ * Type-safe wrapper for a byte array that uniquely identifies a batch of
+ * messages.
+ */
+public class BatchId extends UniqueId {
+
+	public BatchId(byte[] id) {
+		super(id);
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if(o instanceof BatchId)
+			return Arrays.equals(id, ((BatchId) o).id);
+		return false;
+	}
+}

src/net/sf/briar/api/protocol/Group.java

@@ -0,0 +1,17 @@
+package net.sf.briar.api.protocol;
+
+/** A group to which users may subscribe. */
+public interface Group {
+
+	/** Returns the group's unique identifier. */
+	GroupId getId();
+
+	/** Returns the group's name. */
+	String getName();
+
+	/**
+	 * If the group is restricted, returns the public key that is used to
+	 * authorise all messages sent to the group. Otherwise returns null.
+	 */
+	byte[] getPublicKey();
+}

src/net/sf/briar/api/protocol/GroupFactory.java

@@ -0,0 +1,10 @@
+package net.sf.briar.api.protocol;
+
+import java.io.IOException;
+
+public interface GroupFactory {
+
+	Group createGroup(String name, byte[] publicKey) throws IOException;
+
+	Group createGroup(GroupId id, String name, byte[] publicKey);
+}

src/net/sf/briar/api/protocol/GroupId.java

@@ -0,0 +1,21 @@
+package net.sf.briar.api.protocol;
+
+import java.util.Arrays;
+
+/**
+ * Type-safe wrapper for a byte array that uniquely identifies a group to which
+ * users may subscribe.
+ */
+public class GroupId extends UniqueId {
+
+	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;
+	}
+}

src/net/sf/briar/api/protocol/Message.java

@@ -0,0 +1,34 @@
+package net.sf.briar.api.protocol;
+
+public interface Message {
+
+	/** Returns the message's unique identifier. */
+	MessageId getId();
+
+	/**
+	 * Returns the message's parent, or null if this is the first message in a
+	 * thread.
+	 */
+	MessageId getParent();
+
+	/** Returns the group to which the message belongs. */
+	GroupId getGroup();
+
+	/** Returns the message's author. */
+	AuthorId getAuthor();
+
+	/** Returns the message's subject line. */
+	String getSubject();
+
+	/** Returns the timestamp created by the message's author. */
+	long getTimestamp();
+
+	/** Returns the serialised message. */
+	byte[] getSerialised();
+
+	/** Returns the offset of the message body within the serialised message. */
+	int getBodyStart();
+
+	/** Returns the length of the message body in bytes. */
+	int getBodyLength();
+}

src/net/sf/briar/api/protocol/MessageFactory.java

@@ -0,0 +1,31 @@
+package net.sf.briar.api.protocol;
+
+import java.io.IOException;
+import java.security.GeneralSecurityException;
+import java.security.PrivateKey;
+
+public interface MessageFactory {
+
+	/** Creates a private message. */
+	Message createMessage(MessageId parent, String subject, byte[] body)
+	throws IOException, GeneralSecurityException;
+
+	/** Creates an anonymous message to an unrestricted group. */
+	Message createMessage(MessageId parent, Group group, String subject,
+			byte[] body) throws IOException, GeneralSecurityException;
+
+	/** Creates an anonymous message to a restricted group. */
+	Message createMessage(MessageId parent, Group group, PrivateKey groupKey,
+			String subject, byte[] body) throws IOException,
+			GeneralSecurityException;
+
+	/** Creates a pseudonymous message to an unrestricted group. */
+	Message createMessage(MessageId parent, Group group, Author author,
+			PrivateKey authorKey, String subject, byte[] body)
+	throws IOException, GeneralSecurityException;
+
+	/** Creates a pseudonymous message to a restricted group. */
+	Message createMessage(MessageId parent, Group group, PrivateKey groupKey,
+			Author author, PrivateKey authorKey, String subject, byte[] body)
+	throws IOException, GeneralSecurityException;
+}

src/net/sf/briar/api/protocol/MessageId.java

@@ -0,0 +1,18 @@
+package net.sf.briar.api.protocol;
+
+import java.util.Arrays;
+
+/** Type-safe wrapper for a byte array that uniquely identifies a message. */
+public class MessageId extends UniqueId {
+
+	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;
+	}
+}

src/net/sf/briar/api/protocol/Offer.java

@@ -0,0 +1,10 @@
+package net.sf.briar.api.protocol;
+
+import java.util.Collection;
+
+/** A packet offering the recipient some messages. */
+public interface Offer {
+
+	/** Returns the message IDs contained in the offer. */
+	Collection<MessageId> getMessageIds();
+}

src/net/sf/briar/api/protocol/PacketFactory.java

@@ -0,0 +1,22 @@
+package net.sf.briar.api.protocol;
+
+import java.util.BitSet;
+import java.util.Collection;
+import java.util.Map;
+
+public interface PacketFactory {
+
+	Ack createAck(Collection<BatchId> acked);
+
+	RawBatch createBatch(Collection<byte[]> messages);
+
+	Offer createOffer(Collection<MessageId> offered);
+
+	Request createRequest(BitSet requested, int length);
+
+	SubscriptionUpdate createSubscriptionUpdate(Map<GroupId, GroupId> holes,
+			Map<Group, Long> subs, long expiry, long timestamp);
+
+	TransportUpdate createTransportUpdate(Collection<Transport> transports,
+			long timestamp);
+}

src/net/sf/briar/api/protocol/ProtocolConstants.java

@@ -0,0 +1,47 @@
+package net.sf.briar.api.protocol;
+
+import static net.sf.briar.api.transport.TransportConstants.MIN_CONNECTION_LENGTH;
+
+public interface ProtocolConstants {
+
+	/**
+	 * The maximum length of a serialised packet in bytes. To allow for future
+	 * changes in the protocol, this is smaller than the minimum connection
+	 * length minus the maximum encryption and authentication overhead.
+	 */
+	int MAX_PACKET_LENGTH = MIN_CONNECTION_LENGTH / 2;
+
+	/** The maximum number of transports a node may support. */
+	int MAX_TRANSPORTS = 25;
+
+	/** The maximum number of properties per transport. */
+	int MAX_PROPERTIES_PER_TRANSPORT = 100;
+
+	/** The maximum length of a property's key or value in UTF-8 bytes. */
+	int MAX_PROPERTY_LENGTH = 100;
+
+	/** The maximum length of a group's name in UTF-8 bytes. */
+	int MAX_GROUP_NAME_LENGTH = 50;
+
+	/** The maximum length of a public key in bytes. */
+	int MAX_PUBLIC_KEY_LENGTH = 120;
+
+	/** The maximum length of an author's name in UTF-8 bytes. */
+	int MAX_AUTHOR_NAME_LENGTH = 50;
+
+	/**
+	 * The maximum length of a message body in bytes. To allow for future
+	 * changes in the protocol, this is smaller than the maximum packet length
+	 * even when all the message's other fields have their maximum lengths.
+	 */
+	int MAX_BODY_LENGTH = MAX_PACKET_LENGTH - 1024;
+
+	/** The maximum length of a message's subject line in UTF-8 bytes. */
+	int MAX_SUBJECT_LENGTH = 100;
+
+	/** The maximum length of a signature in bytes. */
+	int MAX_SIGNATURE_LENGTH = 120;
+
+	/** The length of a message's random salt in bytes. */
+	int SALT_LENGTH = 8;
+}

src/net/sf/briar/api/protocol/ProtocolReader.java

@@ -0,0 +1,26 @@
+package net.sf.briar.api.protocol;
+
+import java.io.IOException;
+
+public interface ProtocolReader {
+
+	boolean eof() throws IOException;
+
+	boolean hasAck() throws IOException;
+	Ack readAck() throws IOException;
+
+	boolean hasBatch() throws IOException;
+	UnverifiedBatch readBatch() throws IOException;
+
+	boolean hasOffer() throws IOException;
+	Offer readOffer() throws IOException;
+
+	boolean hasRequest() throws IOException;
+	Request readRequest() throws IOException;
+
+	boolean hasSubscriptionUpdate() throws IOException;
+	SubscriptionUpdate readSubscriptionUpdate() throws IOException;
+
+	boolean hasTransportUpdate() throws IOException;
+	TransportUpdate readTransportUpdate() throws IOException;
+}

src/net/sf/briar/api/protocol/ProtocolReaderFactory.java

@@ -0,0 +1,8 @@
+package net.sf.briar.api.protocol;
+
+import java.io.InputStream;
+
+public interface ProtocolReaderFactory {
+
+	ProtocolReader createProtocolReader(InputStream in);
+}

src/net/sf/briar/api/protocol/ProtocolWriter.java

@@ -0,0 +1,28 @@
+package net.sf.briar.api.protocol;
+
+import java.io.IOException;
+
+public interface ProtocolWriter {
+
+	int getMaxBatchesForAck(long capacity);
+
+	int getMaxMessagesForOffer(long capacity);
+
+	int getMessageCapacityForBatch(long capacity);
+
+	void writeAck(Ack a) throws IOException;
+
+	void writeBatch(RawBatch b) throws IOException;
+
+	void writeOffer(Offer o) throws IOException;
+
+	void writeRequest(Request r) throws IOException;
+
+	void writeSubscriptionUpdate(SubscriptionUpdate s) throws IOException;
+
+	void writeTransportUpdate(TransportUpdate t) throws IOException;
+
+	void flush() throws IOException;
+
+	void close() throws IOException;
+}

src/net/sf/briar/api/protocol/ProtocolWriterFactory.java

@@ -0,0 +1,8 @@
+package net.sf.briar.api.protocol;
+
+import java.io.OutputStream;
+
+public interface ProtocolWriterFactory {
+
+	ProtocolWriter createProtocolWriter(OutputStream out, boolean flush);
+}

src/net/sf/briar/api/protocol/RawBatch.java

@@ -0,0 +1,13 @@
+package net.sf.briar.api.protocol;
+
+import java.util.Collection;
+
+/** An outgoing packet containing messages. */
+public interface RawBatch {
+
+	/** Returns the batch's unique identifier. */
+	BatchId getId();
+
+	/** Returns the serialised messages contained in the batch. */
+	Collection<byte[]> getMessages();
+}

src/net/sf/briar/api/protocol/Request.java

@@ -0,0 +1,16 @@
+package net.sf.briar.api.protocol;
+
+import java.util.BitSet;
+
+/** A packet requesting some or all of the messages from an offer. */
+public interface Request {
+
+	/**
+	 * Returns a sequence of bits corresponding to the sequence of messages in
+	 * the offer, where the i^th bit is set if the i^th message should be sent.
+	 */
+	BitSet getBitmap();
+
+	/** Returns the length of the bitmap in bits. */
+	int getLength();
+}

src/net/sf/briar/api/protocol/SubscriptionUpdate.java

@@ -0,0 +1,25 @@
+package net.sf.briar.api.protocol;
+
+import java.util.Map;
+
+/** A packet updating the sender's subscriptions. */
+public interface SubscriptionUpdate {
+
+	/** Returns the holes contained in the update. */
+	Map<GroupId, GroupId> getHoles();
+
+	/** Returns the subscriptions contained in the update. */
+	Map<Group, Long> getSubscriptions();
+
+	/**
+	 * Returns the expiry time of the contact's database. Messages that are
+	 * older than the expiry time must not be sent to the contact.
+	 */
+	long getExpiryTime();
+
+	/**
+	 * Returns the update's timestamp. Updates that are older than the newest
+	 * update received from the same contact must be ignored.
+	 */
+	long getTimestamp();
+}

src/net/sf/briar/api/protocol/Transport.java

@@ -0,0 +1,39 @@
+package net.sf.briar.api.protocol;
+
+import java.util.Map;
+import java.util.TreeMap;
+
+public class Transport extends TreeMap<String, String> {
+
+	private static final long serialVersionUID = 4900420175715429560L;
+
+	private final TransportId id;
+
+	public Transport(TransportId id, Map<String, String> p) {
+		super(p);
+		this.id = id;
+	}
+
+	public Transport(TransportId id) {
+		super();
+		this.id = id;
+	}
+
+	public TransportId getId() {
+		return id;
+	}
+
+	@Override
+	public int hashCode() {
+		return id.hashCode();
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if(o instanceof Transport) {
+			Transport t = (Transport) o;
+			return id.equals(t.id) && super.equals(o);
+		}
+		return false;
+	}
+}

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

@@ -0,0 +1,21 @@
+package net.sf.briar.api.protocol;
+
+import java.util.Arrays;
+
+/**
+ * Type-safe wrapper for a byte array that uniquely identifies a transport
+ * plugin.
+ */
+public class TransportId extends UniqueId {
+
+	public TransportId(byte[] id) {
+		super(id);
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if(o instanceof TransportId)
+			return Arrays.equals(id, ((TransportId) o).id);
+		return false;
+	}
+}

src/net/sf/briar/api/protocol/TransportUpdate.java

@@ -0,0 +1,16 @@
+package net.sf.briar.api.protocol;
+
+import java.util.Collection;
+
+/** A packet updating the sender's transport properties. */
+public interface TransportUpdate {
+
+	/** Returns the transports contained in the update. */
+	Collection<Transport> getTransports();
+
+	/**
+	 * Returns the update's timestamp. Updates that are older than the newest
+	 * update received from the same contact must be ignored.
+	 */
+	long getTimestamp();
+}

src/net/sf/briar/api/protocol/Types.java

@@ -0,0 +1,16 @@
+package net.sf.briar.api.protocol;
+
+/** Struct identifiers for encoding and decoding protocol objects. */
+public interface Types {
+
+	int ACK = 0;
+	int AUTHOR = 1;
+	int BATCH = 2;
+	int GROUP = 3;
+	int MESSAGE = 4;
+	int OFFER = 5;
+	int REQUEST = 6;
+	int SUBSCRIPTION_UPDATE = 7;
+	int TRANSPORT = 8;
+	int TRANSPORT_UPDATE = 9;
+}

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

@@ -0,0 +1,30 @@
+package net.sf.briar.api.protocol;
+
+import java.util.Arrays;
+
+public abstract class UniqueId {
+
+	/** The length of a unique identifier in bytes. */
+	public static final int LENGTH = 48;
+
+	protected final byte[] id;
+
+	private int hashCode = -1;
+
+	protected UniqueId(byte[] id) {
+		if(id.length != LENGTH) throw new IllegalArgumentException();
+		this.id = id;
+	}
+
+	public byte[] getBytes() {
+		return id;
+	}
+
+	@Override
+	public int hashCode() {
+		// Thread-safe because if two or more threads check and update the
+		// value, they'll calculate the same value
+		if(hashCode == -1) hashCode = Arrays.hashCode(id);
+		return hashCode;
+	}
+}

src/net/sf/briar/api/protocol/UnverifiedBatch.java

@@ -0,0 +1,8 @@
+package net.sf.briar.api.protocol;
+
+import java.security.GeneralSecurityException;
+
+public interface UnverifiedBatch {
+
+	Batch verify() throws GeneralSecurityException;
+}

src/net/sf/briar/api/protocol/VerificationExecutor.java

@@ -0,0 +1,15 @@
+package net.sf.briar.api.protocol;
+
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import com.google.inject.BindingAnnotation;
+
+/** Annotation for injecting the executor for message verification tasks. */
+@BindingAnnotation
+@Target({ PARAMETER })
+@Retention(RUNTIME)
+public @interface VerificationExecutor {}

src/net/sf/briar/api/protocol/duplex/DuplexConnectionFactory.java

@@ -0,0 +1,14 @@
+package net.sf.briar.api.protocol.duplex;
+
+import net.sf.briar.api.ContactId;
+import net.sf.briar.api.plugins.duplex.DuplexTransportConnection;
+import net.sf.briar.api.protocol.TransportId;
+import net.sf.briar.api.transport.ConnectionContext;
+
+public interface DuplexConnectionFactory {
+
+	void createIncomingConnection(ConnectionContext ctx, DuplexTransportConnection d);
+
+	void createOutgoingConnection(ContactId c, TransportId t,
+			DuplexTransportConnection d);
+}

src/net/sf/briar/api/protocol/simplex/SimplexConnectionFactory.java

@@ -0,0 +1,15 @@
+package net.sf.briar.api.protocol.simplex;
+
+import net.sf.briar.api.ContactId;
+import net.sf.briar.api.plugins.simplex.SimplexTransportReader;
+import net.sf.briar.api.plugins.simplex.SimplexTransportWriter;
+import net.sf.briar.api.protocol.TransportId;
+import net.sf.briar.api.transport.ConnectionContext;
+
+public interface SimplexConnectionFactory {
+
+	void createIncomingConnection(ConnectionContext ctx, SimplexTransportReader r);
+
+	void createOutgoingConnection(ContactId c, TransportId t,
+			SimplexTransportWriter w);
+}

src/net/sf/briar/api/serial/Consumer.java

@@ -0,0 +1,10 @@
+package net.sf.briar.api.serial;
+
+import java.io.IOException;
+
+public interface Consumer {
+
+	void write(byte b) throws IOException;
+
+	void write(byte[] b, int off, int len) throws IOException;
+}

src/net/sf/briar/api/serial/CopyingConsumer.java

@@ -0,0 +1,22 @@
+package net.sf.briar.api.serial;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+
+/** A consumer that makes a copy of the bytes consumed. */
+public class CopyingConsumer implements Consumer {
+
+	private final ByteArrayOutputStream out = new ByteArrayOutputStream();
+
+	public byte[] getCopy() {
+		return out.toByteArray();
+	}
+
+	public void write(byte b) throws IOException {
+		out.write(b);
+	}
+
+	public void write(byte[] b, int off, int len) throws IOException {
+		out.write(b, off, len);
+	}
+}

src/net/sf/briar/api/serial/CountingConsumer.java

@@ -0,0 +1,33 @@
+package net.sf.briar.api.serial;
+
+import java.io.IOException;
+
+import net.sf.briar.api.FormatException;
+
+/**
+ * A consumer that counts the number of bytes consumed and throws a
+ * FormatException if the count exceeds a given limit.
+ */
+public class CountingConsumer implements Consumer {
+
+	private final long limit;
+	private long count = 0L;
+
+	public CountingConsumer(long limit) {
+		this.limit = limit;
+	}
+
+	public long getCount() {
+		return count;
+	}
+
+	public void write(byte b) throws IOException {
+		count++;
+		if(count > limit) throw new FormatException();
+	}
+
+	public void write(byte[] b, int off, int len) throws IOException {
+		count += len;
+		if(count > limit) throw new FormatException();
+	}
+}

src/net/sf/briar/api/serial/DigestingConsumer.java

@@ -0,0 +1,21 @@
+package net.sf.briar.api.serial;
+
+import net.sf.briar.api.crypto.MessageDigest;
+
+/** A consumer that passes its input through a message digest. */
+public class DigestingConsumer implements Consumer {
+
+	private final MessageDigest messageDigest;
+
+	public DigestingConsumer(MessageDigest messageDigest) {
+		this.messageDigest = messageDigest;
+	}
+
+	public void write(byte b) {
+		messageDigest.update(b);
+	}
+
+	public void write(byte[] b, int off, int len) {
+		messageDigest.update(b, off, len);
+	}
+}

src/net/sf/briar/api/serial/Reader.java

@@ -0,0 +1,73 @@
+package net.sf.briar.api.serial;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+
+public interface Reader {
+
+	boolean eof() throws IOException;
+	void close() throws IOException;
+
+	void setMaxStringLength(int length);
+	void resetMaxStringLength();
+
+	void setMaxBytesLength(int length);
+	void resetMaxBytesLength();
+
+	void addConsumer(Consumer c);
+	void removeConsumer(Consumer c);
+
+	void addStructReader(int id, StructReader<?> o);
+	void removeStructReader(int id);
+
+	boolean hasBoolean() throws IOException;
+	boolean readBoolean() throws IOException;
+
+	boolean hasUint7() throws IOException;
+	byte readUint7() throws IOException;
+	boolean hasInt8() throws IOException;
+	byte readInt8() throws IOException;
+	boolean hasInt16() throws IOException;
+	short readInt16() throws IOException;
+	boolean hasInt32() throws IOException;
+	int readInt32() throws IOException;
+	boolean hasInt64() throws IOException;
+	long readInt64() throws IOException;
+	boolean hasIntAny() throws IOException;
+	long readIntAny() throws IOException;
+
+	boolean hasFloat32() throws IOException;
+	float readFloat32() throws IOException;
+	boolean hasFloat64() throws IOException;
+	double readFloat64() throws IOException;
+
+	boolean hasString() throws IOException;
+	String readString() throws IOException;
+	String readString(int maxLength) throws IOException;
+
+	boolean hasBytes() throws IOException;
+	byte[] readBytes() throws IOException;
+	byte[] readBytes(int maxLength) throws IOException;
+
+	boolean hasList() throws IOException;
+	<E> List<E> readList(Class<E> e) throws IOException;
+	boolean hasListStart() throws IOException;
+	void readListStart() throws IOException;
+	boolean hasListEnd() throws IOException;
+	void readListEnd() throws IOException;
+
+	boolean hasMap() throws IOException;
+	<K, V> Map<K, V> readMap(Class<K> k, Class<V> v) throws IOException;
+	boolean hasMapStart() throws IOException;
+	void readMapStart() throws IOException;
+	boolean hasMapEnd() throws IOException;
+	void readMapEnd() throws IOException;
+
+	boolean hasNull() throws IOException;
+	void readNull() throws IOException;
+
+	boolean hasStruct(int id) throws IOException;
+	<T> T readStruct(int id, Class<T> t) throws IOException;
+	void readStructId(int id) throws IOException;
+}

src/net/sf/briar/api/serial/ReaderFactory.java

@@ -0,0 +1,8 @@
+package net.sf.briar.api.serial;
+
+import java.io.InputStream;
+
+public interface ReaderFactory {
+
+	Reader createReader(InputStream in);
+}

src/net/sf/briar/api/serial/SerialComponent.java

@@ -0,0 +1,12 @@
+package net.sf.briar.api.serial;
+
+public interface SerialComponent {
+
+	int getSerialisedListEndLength();
+
+	int getSerialisedListStartLength();
+
+	int getSerialisedStructIdLength(int id);
+
+	int getSerialisedUniqueIdLength();
+}

src/net/sf/briar/api/serial/SigningConsumer.java

@@ -0,0 +1,31 @@
+package net.sf.briar.api.serial;
+
+import java.io.IOException;
+import java.security.Signature;
+import java.security.SignatureException;
+
+/** A consumer that passes its input through a signature. */
+public class SigningConsumer implements Consumer {
+
+	private final Signature signature;
+
+	public SigningConsumer(Signature signature) {
+		this.signature = signature;
+	}
+
+	public void write(byte b) throws IOException {
+		try {
+			signature.update(b);
+		} catch(SignatureException e) {
+			throw new IOException(e.toString());
+		}
+	}
+
+	public void write(byte[] b, int off, int len) throws IOException {
+		try {
+			signature.update(b, off, len);
+		} catch(SignatureException e) {
+			throw new IOException(e.toString());
+		}
+	}
+}

src/net/sf/briar/api/serial/StructReader.java

@@ -0,0 +1,8 @@
+package net.sf.briar.api.serial;
+
+import java.io.IOException;
+
+public interface StructReader<T> {
+
+	T readStruct(Reader r) throws IOException;
+}

src/net/sf/briar/api/serial/Writer.java

@@ -0,0 +1,38 @@
+package net.sf.briar.api.serial;
+
+import java.io.IOException;
+import java.util.Collection;
+import java.util.Map;
+
+public interface Writer {
+
+	void addConsumer(Consumer c);
+	void removeConsumer(Consumer c);
+
+	void writeBoolean(boolean b) throws IOException;
+
+	void writeUint7(byte b) throws IOException;
+	void writeInt8(byte b) throws IOException;
+	void writeInt16(short s) throws IOException;
+	void writeInt32(int i) throws IOException;
+	void writeInt64(long l) throws IOException;
+	void writeIntAny(long l) throws IOException;
+
+	void writeFloat32(float f) throws IOException;
+	void writeFloat64(double d) throws IOException;
+
+	void writeString(String s) throws IOException;
+	void writeBytes(byte[] b) throws IOException;
+
+	void writeList(Collection<?> c) throws IOException;
+	void writeListStart() throws IOException;
+	void writeListEnd() throws IOException;
+
+	void writeMap(Map<?, ?> m) throws IOException;
+	void writeMapStart() throws IOException;
+	void writeMapEnd() throws IOException;
+
+	void writeNull() throws IOException;
+
+	void writeStructId(int id) throws IOException;
+}

src/net/sf/briar/api/serial/WriterFactory.java

@@ -0,0 +1,8 @@
+package net.sf.briar.api.serial;
+
+import java.io.OutputStream;
+
+public interface WriterFactory {
+
+	Writer createWriter(OutputStream out);
+}