Changed the root package from net.sf.briar to org.briarproject.

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

@@ -0,0 +1,40 @@
+package org.briarproject.api;
+
+/** A pseudonym for a user. */
+public class Author {
+
+	private final AuthorId id;
+	private final String name;
+	private final byte[] publicKey;
+
+	public Author(AuthorId id, String name, byte[] publicKey) {
+		this.id = id;
+		this.name = name;
+		this.publicKey = publicKey;
+	}
+
+	/** Returns the author's unique identifier. */
+	public AuthorId getId() {
+		return id;
+	}
+
+	/** Returns the author's name. */
+	public String getName() {
+		return name;
+	}
+
+	/** Returns the public key used to verify the pseudonym's signatures. */
+	public byte[] getPublicKey() {
+		return publicKey;
+	}
+
+	@Override
+	public int hashCode() {
+		return id.hashCode();
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		return o instanceof Author && id.equals(((Author) o).id);
+	}
+}

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

@@ -0,0 +1,31 @@
+package org.briarproject.api;
+
+public interface AuthorConstants {
+
+	/** The maximum length of an author's name in UTF-8 bytes. */
+	int MAX_AUTHOR_NAME_LENGTH = 50;
+
+	/**
+	 * The maximum length of a public key in bytes.
+	 * <p>
+	 * Public keys use SEC1 format: 0x04 x y, where x and y are unsigned
+	 * big-endian integers.
+	 * <p>
+	 * For a 384-bit elliptic curve, the maximum length is 2 * (384/8) + 1.
+	 */
+	int MAX_PUBLIC_KEY_LENGTH = 97;
+
+	/**
+	 * The maximum length of a signature in bytes.
+	 * <p>
+	 * A signature is an ASN.1 DER sequence containing two integers, r and s.
+	 * The format is 0x30 len1 0x02 len2 r 0x02 len3 s, where len1 is
+	 * len(0x02 len2 r 0x02 len3 s) as a DER length, len2 is len(r) as a DER
+	 * length, len3 is len(s) as a DER length, and r and s are signed
+	 * big-endian integers of minimal length.
+	 * <p>
+	 * For a 384-bit elliptic curve, the lengths are one byte each, so the
+	 * maximum length is 2 * (384/8) + 8.
+	 */
+	int MAX_SIGNATURE_LENGTH = 104;
+}

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

@@ -0,0 +1,9 @@
+package org.briarproject.api;
+
+public interface AuthorFactory {
+
+	Author createAuthor(String name, byte[] publicKey);
+
+	LocalAuthor createLocalAuthor(String name, byte[] publicKey,
+			byte[] privateKey);
+}

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

@@ -0,0 +1,21 @@
+package org.briarproject.api;
+
+import java.util.Arrays;
+
+/**
+ * Type-safe wrapper for a byte array that uniquely identifies an
+ * {@link 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;
+	}
+}

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

@@ -0,0 +1,34 @@
+package org.briarproject.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;
+	}
+}

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

@@ -0,0 +1,37 @@
+package org.briarproject.api;
+
+public class Contact {
+
+	private final ContactId id;
+	private final Author author;
+	private final AuthorId localAuthorId;
+
+	public Contact(ContactId id, Author author, AuthorId localAuthorId) {
+		this.id = id;
+		this.author = author;
+		this.localAuthorId = localAuthorId;
+	}
+
+	public ContactId getId() {
+		return id;
+	}
+
+	public Author getAuthor() {
+		return author;
+	}
+
+	public AuthorId getLocalAuthorId() {
+		return localAuthorId;
+	}
+
+	@Override
+	public int hashCode() {
+		return id.hashCode();
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if(o instanceof Contact) return id.equals(((Contact) o).id);
+		return false;
+	}
+}

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

@@ -0,0 +1,29 @@
+package org.briarproject.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 int hashCode() {
+		return id;
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if(o instanceof ContactId) return id == ((ContactId) o).id;
+		return false;
+	}
+}

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

@@ -0,0 +1,9 @@
+package org.briarproject.api;
+
+import java.io.IOException;
+
+/** An exception that indicates an unrecoverable formatting error. */
+public class FormatException extends IOException {
+
+	private static final long serialVersionUID = 2274966775687766337L;
+}

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

@@ -0,0 +1,18 @@
+package org.briarproject.api;
+
+/** A pseudonym for the local user. */
+public class LocalAuthor extends Author {
+
+	private final byte[] privateKey;
+
+	public LocalAuthor(AuthorId id, String name, byte[] publicKey,
+			byte[] privateKey) {
+		super(id, name, publicKey);
+		this.privateKey = privateKey;
+	}
+
+	/**  Returns the private key used to generate the pseudonym's signatures. */
+	public byte[] getPrivateKey() {
+		return privateKey;
+	}
+}

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

@@ -0,0 +1,15 @@
+package org.briarproject.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() {}
+}

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

@@ -0,0 +1,21 @@
+package org.briarproject.api;
+
+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;
+	}
+}

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

@@ -0,0 +1,15 @@
+package org.briarproject.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() {}
+}

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

@@ -0,0 +1,10 @@
+package org.briarproject.api;
+
+public interface TransportPropertyConstants {
+
+	/** 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;
+}

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

@@ -0,0 +1,30 @@
+package org.briarproject.api;
+
+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;
+	}
+}

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

@@ -0,0 +1,19 @@
+package org.briarproject.api.android;
+
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+
+/**
+ * Enables background threads to make Android API calls that must be made from
+ * a thread with a message queue.
+ */
+public interface AndroidExecutor {
+
+	/**
+	 * Runs the given task on a thread with a message queue and returns the
+	 * result of the task.
+	 */
+	<V> V call(Callable<V> c) throws InterruptedException, ExecutionException;
+
+	void shutdown();
+}

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

@@ -0,0 +1,19 @@
+package org.briarproject.api.android;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+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 accessing the database from the UI.
+ */
+@BindingAnnotation
+@Target({ FIELD, METHOD, PARAMETER })
+@Retention(RUNTIME)
+public @interface DatabaseUiExecutor {}

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

@@ -0,0 +1,27 @@
+package org.briarproject.api.android;
+
+/**
+ * Manages mappings between object references and serialisable handles. This
+ * enables references to be passed between Android UI objects that belong to
+ * the same process but can only communicate via serialisation.
+ */
+public interface ReferenceManager {
+
+	/**
+	 * Returns the object with the given handle, or null if no mapping exists
+	 * for the handle.
+	 */
+	<T> T getReference(long handle, Class<T> c);
+
+	/**
+	 * Creates a mapping between the given reference and a handle, and returns
+	 * the handle.
+	 */
+	<T> long putReference(T reference, Class<T> c);
+
+	/**
+	 * Removes and returns the object with the given handle, or returns null
+	 * if no mapping exists for the handle.
+	 */
+	<T> T removeReference(long handle, Class<T> c);
+}

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

@@ -0,0 +1,24 @@
+package org.briarproject.api.crypto;
+
+import java.security.GeneralSecurityException;
+
+/** An authenticated cipher that support additional authenticated data. */
+public interface AuthenticatedCipher {
+
+	/**
+	 * Initializes this cipher with a key, an initialisation vector (IV) and
+	 * additional authenticated data (AAD).
+	 */
+	void init(int opmode, SecretKey key, byte[] iv, byte[] aad)
+			throws GeneralSecurityException;
+
+	/** Encrypts or decrypts data in a single-part operation. */
+	int doFinal(byte[] input, int inputOff, int len, byte[] output,
+			int outputOff) throws GeneralSecurityException;
+
+	/** Returns the length of the message authenticated code (MAC) in bytes. */
+	int getMacLength();
+
+	/** Returns the block size of the cipher in bytes. */
+	int getBlockSize();
+}

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

@@ -0,0 +1,105 @@
+package org.briarproject.api.crypto;
+
+import java.security.GeneralSecurityException;
+import java.security.SecureRandom;
+
+public interface CryptoComponent {
+
+	SecretKey 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 a group salt from the given master secret. */
+	byte[] deriveGroupSalt(byte[] secret);
+
+	/**
+	 * 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
+	 * Alice or Bob.
+	 */
+	SecretKey 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.
+	 */
+	SecretKey deriveFrameKey(byte[] secret, long connection, boolean alice,
+			boolean initiator);
+
+	/** 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, SecretKey tagKey, long connection);
+
+	/**
+	 * Encrypts and authenticates the given plaintext so it can be written to
+	 * storage. The encryption and authentication keys are derived from the
+	 * given password. The ciphertext will be decryptable using the same
+	 * password after the app restarts.
+	 */
+	byte[] encryptWithPassword(byte[] plaintext, char[] password);
+
+	/**
+	 * Decrypts and authenticates the given ciphertext that has been read from
+	 * storage. The encryption and authentication keys are derived from the
+	 * given password. Returns null if the ciphertext cannot be decrypted and
+	 * authenticated (for example, if the password is wrong).
+	 */
+	byte[] decryptWithPassword(byte[] ciphertext, char[] password);
+}

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

@@ -0,0 +1,17 @@
+package org.briarproject.api.crypto;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+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 long-running crypto tasks. */
+@BindingAnnotation
+@Target({ FIELD, METHOD, PARAMETER })
+@Retention(RUNTIME)
+public @interface CryptoExecutor {}

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

@@ -0,0 +1,23 @@
+package org.briarproject.api.crypto;
+
+import org.briarproject.api.ContactId;
+import org.briarproject.api.TransportId;
+import org.briarproject.api.lifecycle.Service;
+import org.briarproject.api.transport.ConnectionContext;
+import org.briarproject.api.transport.Endpoint;
+
+public interface KeyManager extends Service {
+
+	/**
+	 * 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 an endpoint has been added. The initial secret
+	 * is erased before returning.
+	 */
+	void endpointAdded(Endpoint ep, long maxLatency, byte[] initialSecret);
+}

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

@@ -0,0 +1,21 @@
+package org.briarproject.api.crypto;
+
+/** A key pair consisting of a {@link PublicKey} and a {@link PrivateKey). */
+public class KeyPair {
+
+	private final PublicKey publicKey;
+	private final PrivateKey privateKey;
+
+	public KeyPair(PublicKey publicKey, PrivateKey privateKey) {
+		this.publicKey = publicKey;
+		this.privateKey = privateKey;
+	}
+
+	public PublicKey getPublic() {
+		return publicKey;
+	}
+
+	public PrivateKey getPrivate() {
+		return privateKey;
+	}
+}

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

@@ -0,0 +1,11 @@
+package org.briarproject.api.crypto;
+
+import java.security.GeneralSecurityException;
+
+public interface KeyParser {
+
+	PublicKey parsePublicKey(byte[] encodedKey) throws GeneralSecurityException;
+
+	PrivateKey parsePrivateKey(byte[] encodedKey)
+			throws GeneralSecurityException;
+}

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

@@ -0,0 +1,28 @@
+package org.briarproject.api.crypto;
+
+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);
+}

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

@@ -0,0 +1,8 @@
+package org.briarproject.api.crypto;
+
+/** The private half of a public/private {@link KeyPair}. */
+public interface PrivateKey {
+
+	/** Returns the encoded representation of this key. */
+	byte[] getEncoded();
+}

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

@@ -0,0 +1,7 @@
+package org.briarproject.api.crypto;
+
+/** A deterministic PRNG. */
+public interface PseudoRandom {
+
+	byte[] nextBytes(int bytes);
+}

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

@@ -0,0 +1,8 @@
+package org.briarproject.api.crypto;
+
+/** The public half of a public/private {@link KeyPair}. */
+public interface PublicKey {
+
+	/** Returns the encoded representation of this key. */
+	byte[] getEncoded();
+}

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

@@ -0,0 +1,21 @@
+package org.briarproject.api.crypto;
+
+/** A secret key used for encryption and/or authentication. */
+public interface SecretKey {
+
+	/** Returns the encoded representation of this key. */
+	byte[] getEncoded();
+
+	/**
+	 * Returns a copy of this key - erasing this key will erase the copy and
+	 * vice versa.
+	 */
+	SecretKey copy();
+
+	/**
+	 * Erases this key from memory. Any copies derived from this key via the
+	 * {@link #copy()} method, and any keys from which this key was derived via
+	 * the {@link #copy()} method, are also erased.
+	 */
+	void erase();
+}

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

@@ -0,0 +1,31 @@
+package org.briarproject.api.crypto;
+
+import java.security.GeneralSecurityException;
+
+public interface Signature {
+
+	/**
+	 * @see {@link java.security.Signature#initSign(java.security.PrivateKey)}
+	 */
+	void initSign(PrivateKey k) throws GeneralSecurityException;
+
+	/**
+	 * @see {@link java.security.Signature#initVafiry(java.security.PublicKey)}
+	 */
+	void initVerify(PublicKey k) throws GeneralSecurityException;
+
+	/** @see {@link java.security.Signature#update(byte)} */
+	void update(byte b);
+
+	/** @see {@link java.security.Signature#update(byte[])} */
+	void update(byte[] b);
+
+	/** @see {@link java.security.Signature#update(byte[], int, int)} */
+	void update(byte[] b, int off, int len);
+
+	/** @see {@link java.security.Signature#sign()} */
+	byte[] sign();
+
+	/** @see {@link java.security.Signature#verify(byte[])} */
+	boolean verify(byte[] signature);
+}

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

@@ -0,0 +1,10 @@
+package org.briarproject.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/org/briarproject/api/db/DatabaseComponent.java

@@ -0,0 +1,357 @@
+package org.briarproject.api.db;
+
+import java.io.IOException;
+import java.util.Collection;
+import java.util.Map;
+
+import org.briarproject.api.Author;
+import org.briarproject.api.AuthorId;
+import org.briarproject.api.Contact;
+import org.briarproject.api.ContactId;
+import org.briarproject.api.LocalAuthor;
+import org.briarproject.api.TransportConfig;
+import org.briarproject.api.TransportId;
+import org.briarproject.api.TransportProperties;
+import org.briarproject.api.event.EventListener;
+import org.briarproject.api.messaging.Ack;
+import org.briarproject.api.messaging.Group;
+import org.briarproject.api.messaging.GroupId;
+import org.briarproject.api.messaging.GroupStatus;
+import org.briarproject.api.messaging.Message;
+import org.briarproject.api.messaging.MessageId;
+import org.briarproject.api.messaging.Offer;
+import org.briarproject.api.messaging.Request;
+import org.briarproject.api.messaging.RetentionAck;
+import org.briarproject.api.messaging.RetentionUpdate;
+import org.briarproject.api.messaging.SubscriptionAck;
+import org.briarproject.api.messaging.SubscriptionUpdate;
+import org.briarproject.api.messaging.TransportAck;
+import org.briarproject.api.messaging.TransportUpdate;
+import org.briarproject.api.transport.Endpoint;
+import org.briarproject.api.transport.TemporarySecret;
+
+/**
+ * Encapsulates the database implementation and exposes high-level operations
+ * to other components.
+ */
+public interface DatabaseComponent {
+
+	/** Opens the database and returns true if the database already existed. */
+	boolean open() 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(EventListener d);
+
+	/** Removes a listener. */
+	void removeListener(EventListener d);
+
+	/**
+	 * Stores a contact associated with the given local and remote pseudonyms,
+	 * and returns an ID for the contact.
+	 */
+	ContactId addContact(Author remote, AuthorId local) throws DbException;
+
+	/** Stores an endpoint. */
+	void addEndpoint(Endpoint ep) throws DbException;
+
+	/**
+	 * Subscribes to a group, or returns false if the user already has the
+	 * maximum number of public subscriptions.
+	 */
+	boolean addGroup(Group g) throws DbException;
+
+	/** Stores a local pseudonym. */
+	void addLocalAuthor(LocalAuthor a) throws DbException;
+
+	/** Stores a local message. */
+	void addLocalMessage(Message m) throws DbException;
+
+	/**
+	 * Stores the given temporary secrets and deletes any secrets that have
+	 * been made obsolete.
+	 */
+	void addSecrets(Collection<TemporarySecret> secrets) throws DbException;
+
+	/**
+	 * Stores a transport and returns true if the transport was not previously
+	 * in the database.
+	 */
+	boolean addTransport(TransportId t, long maxLatency) throws DbException;
+
+	/**
+	 * Returns an acknowledgement for the given contact, or null if there are
+	 * no messages to acknowledge.
+	 */
+	Ack generateAck(ContactId c, int maxMessages) throws DbException;
+
+	/**
+	 * Returns a batch of raw messages for the given contact, with a total
+	 * length less than or equal to the given length, for transmission over a
+	 * transport with the given maximum latency. Returns null if there are no
+	 * sendable messages that fit in the given length.
+	 */
+	Collection<byte[]> generateBatch(ContactId c, int maxLength,
+			long maxLatency) throws DbException;
+
+	/**
+	 * Returns an offer for the given contact for transmission over a
+	 * transport with the given maximum latency, or null if there are no
+	 * messages to offer.
+	 */
+	Offer generateOffer(ContactId c, int maxMessages, long maxLatency)
+			throws DbException;
+
+	/**
+	 * Returns a request for the given contact, or null if there are no
+	 * messages to request.
+	 */
+	Request generateRequest(ContactId c, int maxMessages) throws DbException;
+
+	/**
+	 * Returns a batch of raw messages for the given contact, with a total
+	 * length less than or equal to the given length, for transmission over a
+	 * transport with the given maximum latency. Only messages that have been
+	 * requested by the contact are returned. Returns null if there are no
+	 * sendable messages that fit in the given length.
+	 */
+	Collection<byte[]> generateRequestedBatch(ContactId c, int maxLength,
+			long maxLatency) throws DbException;
+
+	/**
+	 * Returns a retention ack for the given contact, or null if no retention
+	 * ack is due.
+	 */
+	RetentionAck generateRetentionAck(ContactId c) throws DbException;
+
+	/**
+	 * Returns a retention update for the given contact, for transmission
+	 * over a transport with the given latency. Returns null if no update is
+	 * due.
+	 */
+	RetentionUpdate generateRetentionUpdate(ContactId c, long maxLatency)
+			throws DbException;
+
+	/**
+	 * Returns a subscription ack for the given contact, or null if no
+	 * subscription ack is due.
+	 */
+	SubscriptionAck generateSubscriptionAck(ContactId c) throws DbException;
+
+	/**
+	 * Returns a subscription update for the given contact, for transmission
+	 * over a transport with the given latency. Returns null if no update is
+	 * due.
+	 */
+	SubscriptionUpdate generateSubscriptionUpdate(ContactId c, long maxLatency)
+			throws DbException;
+
+	/**
+	 * Returns a batch of transport acks for the given contact, or null if no
+	 * transport acks are due.
+	 */
+	Collection<TransportAck> generateTransportAcks(ContactId c)
+			throws DbException;
+
+	/**
+	 * Returns a batch of transport updates for the given contact, for
+	 * transmission over a transport with the given latency. Returns null if no
+	 * updates are due.
+	 */
+	Collection<TransportUpdate> generateTransportUpdates(ContactId c,
+			long maxLatency) throws DbException;
+
+	/**
+	 * Returns the status of all groups to which the user subscribes or can
+	 * subscribe, excluding inbox groups.
+	 */
+	Collection<GroupStatus> getAvailableGroups() throws DbException;
+
+	/** Returns the configuration for the given transport. */
+	TransportConfig getConfig(TransportId t) throws DbException;
+
+	/** Returns the contact with the given ID. */
+	Contact getContact(ContactId c) throws DbException;
+
+	/** Returns all contacts. */
+	Collection<Contact> getContacts() throws DbException;
+
+	/** Returns the group with the given ID, if the user subscribes to it. */
+	Group getGroup(GroupId g) throws DbException;
+
+	/** Returns all groups to which the user subscribes. */
+	Collection<Group> getGroups() throws DbException;
+
+	/**
+	 * Returns the ID of the inbox group for the given contact, or null if no
+	 * inbox group has been set.
+	 */
+	GroupId getInboxGroupId(ContactId c) throws DbException;
+
+	/**
+	 * Returns the headers of all messages in the inbox group for the given
+	 * contact, or null if no inbox group has been set.
+	 */
+	Collection<MessageHeader> getInboxMessageHeaders(ContactId c)
+			throws DbException;
+
+	/**
+	 * Returns the time at which a connection to each contact was last opened
+	 * or closed.
+	 */
+	Map<ContactId, Long> getLastConnected() throws DbException;
+
+	/** Returns the local pseudonym with the given ID. */
+	LocalAuthor getLocalAuthor(AuthorId a) throws DbException;
+
+	/** Returns all local pseudonyms. */
+	Collection<LocalAuthor> getLocalAuthors() 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;
+
+	/** Returns the body of the message with the given ID. */
+	byte[] getMessageBody(MessageId m) throws DbException;
+
+	/** Returns the headers of all messages in the given group. */
+	Collection<MessageHeader> getMessageHeaders(GroupId g)
+			throws DbException;
+
+	/** Returns true if the given message is marked as read. */
+	boolean getReadFlag(MessageId m) 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 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;
+
+	/** Returns the IDs of all contacts to which the given group is visible. */
+	Collection<ContactId> getVisibility(GroupId g) throws DbException;
+
+	/**
+	 * Increments the outgoing connection counter for the given endpoint
+	 * in the given rotation period and returns the old value, or -1 if the
+	 * counter does not exist.
+	 */
+	long incrementConnectionCounter(ContactId c, TransportId t, long period)
+			throws DbException;
+
+	/**
+	 * Merges the given configuration with existing configuration for the
+	 * given transport.
+	 */
+	void mergeConfig(TransportId t, TransportConfig c) throws DbException;
+
+	/**
+	 * Merges the given properties with the existing local properties for the
+	 * given transport.
+	 */
+	void mergeLocalProperties(TransportId t, TransportProperties p)
+			throws DbException;
+
+	/** Processes an ack from the given contact. */
+	void receiveAck(ContactId c, Ack a) throws DbException;
+
+	/** Processes a message from the given contact. */
+	void receiveMessage(ContactId c, Message m) throws DbException;
+
+	/** Processes an offer from the given contact. */
+	void receiveOffer(ContactId c, Offer o) throws DbException;
+
+	/** Processes a request from the given contact. */
+	void receiveRequest(ContactId c, Request r) throws DbException;
+
+	/** Processes a retention ack from the given contact. */
+	void receiveRetentionAck(ContactId c, RetentionAck a) throws DbException;
+
+	/** Processes a retention update from the given contact. */
+	void receiveRetentionUpdate(ContactId c, RetentionUpdate u)
+			throws DbException;
+
+	/** Processes a subscription ack from the given contact. */
+	void receiveSubscriptionAck(ContactId c, SubscriptionAck a)
+			throws DbException;
+
+	/** Processes a subscription update from the given contact. */
+	void receiveSubscriptionUpdate(ContactId c, SubscriptionUpdate u)
+			throws DbException;
+
+	/** Processes a transport ack from the given contact. */
+	void receiveTransportAck(ContactId c, TransportAck a) throws DbException;
+
+	/** Processes a transport update from the given contact. */
+	void receiveTransportUpdate(ContactId c, TransportUpdate u)
+			throws DbException;
+
+	/** Removes a contact (and all associated state) from the database. */
+	void removeContact(ContactId c) throws DbException;
+
+	/**
+	 * Unsubscribes from a group. Any messages belonging to the group
+	 * are deleted from the database.
+	 */
+	void removeGroup(Group g) throws DbException;
+
+	/**
+	 * Removes a local pseudonym (and all associated state) from the database.
+	 */
+	void removeLocalAuthor(AuthorId a) throws DbException;
+
+	/**
+	 * Removes a transport (and any associated configuration and local
+	 * properties) from the database.
+	 */
+	void removeTransport(TransportId t) throws DbException;
+
+	/**
+	 * Sets the connection reordering window for the given endpoint in the
+	 * given rotation period.
+	 */
+	void setConnectionWindow(ContactId c, TransportId t, long period,
+			long centre, byte[] bitmap) throws DbException;
+
+	/**
+	 * Makes a group visible to the given contact, adds it to the contact's
+	 * subscriptions, and sets it as the inbox group for the contact.
+	 */
+	public void setInboxGroup(ContactId c, Group g) throws DbException;
+
+	/**
+	 * Marks a message as read or unread.
+	 */
+	void 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;
+
+	/**
+	 * Makes a group visible to the given set of contacts and invisible to any
+	 * other current or future contacts.
+	 */
+	void setVisibility(GroupId g, Collection<ContactId> visible)
+			throws DbException;
+
+	/**
+	 * Makes a group visible to all current and future contacts, or invisible
+	 * to future contacts.
+	 */
+	void setVisibleToAll(GroupId g, boolean all) throws DbException;
+}

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

@@ -0,0 +1,16 @@
+package org.briarproject.api.db;
+
+import java.io.File;
+
+public interface DatabaseConfig {
+
+	boolean databaseExists();
+
+	File getDatabaseDirectory();
+
+	void setEncryptionKey(byte[] key);
+
+	byte[] getEncryptionKey();
+
+	long getMaxSize();
+}

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

@@ -0,0 +1,17 @@
+package org.briarproject.api.db;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+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({ FIELD, METHOD, PARAMETER })
+@Retention(RUNTIME)
+public @interface DatabaseExecutor {}

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

@@ -0,0 +1,7 @@
+package org.briarproject.api.db;
+
+/** Thrown when a database operation is attempted and the database is closed. */
+public class DbClosedException extends DbException {
+
+	private static final long serialVersionUID = -3679248177625310653L;
+}

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

@@ -0,0 +1,12 @@
+package org.briarproject.api.db;
+
+public class DbException extends Exception {
+
+	private static final long serialVersionUID = 3706581789209939441L;
+
+	public DbException() {}
+
+	public DbException(Throwable t) {
+		super(t);
+	}
+}

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

@@ -0,0 +1,10 @@
+package org.briarproject.api.db;
+
+/**
+ * Thrown when a duplicate pseudonym is added to the database. This exception
+ * may occur due to concurrent updates and does not indicate a database error.
+ */
+public class LocalAuthorExistsException extends DbException {
+
+	private static final long serialVersionUID = -1483877298070151673L;
+}

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

@@ -0,0 +1,68 @@
+package org.briarproject.api.db;
+
+import org.briarproject.api.Author;
+import org.briarproject.api.messaging.GroupId;
+import org.briarproject.api.messaging.MessageId;
+
+public class MessageHeader {
+
+	private final MessageId id, parent;
+	private final GroupId groupId;
+	private final Author author;
+	private final String contentType;
+	private final long timestamp;
+	private final boolean read;
+
+	public MessageHeader(MessageId id, MessageId parent, GroupId groupId,
+			Author author, String contentType, long timestamp, boolean read) {
+		this.id = id;
+		this.parent = parent;
+		this.groupId = groupId;
+		this.author = author;
+		this.contentType = contentType;
+		this.timestamp = timestamp;
+		this.read = read;
+	}
+
+	/** Returns the message's unique identifier. */
+	public MessageId getId() {
+		return id;
+	}
+
+	/**
+	 * Returns the message's parent, or null if this is the first message in a
+	 * thread.
+	 */
+	public MessageId getParent() {
+		return parent;
+	}
+
+	/**
+	 * Returns the unique identifier of the group to which the message belongs.
+	 */
+	public GroupId getGroupId() {
+		return groupId;
+	}
+
+	/**
+	 * Returns the message's author, or null if this is an  anonymous message.
+	 */
+	public Author getAuthor() {
+		return author;
+	}
+
+	/** Returns the message's content type. */
+	public String getContentType() {
+		return contentType;
+	}
+
+	/** Returns the timestamp created by the message's author. */
+	public long getTimestamp() {
+		return timestamp;
+	}
+
+	/** Returns true if the message has been read. */
+	public boolean isRead() {
+		return read;
+	}
+}

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

@@ -0,0 +1,11 @@
+package org.briarproject.api.db;
+
+/**
+ * Thrown when a database operation is attempted for a contact that is not in
+ * the database. This exception may occur due to concurrent updates and does
+ * not indicate a database error.
+ */
+public class NoSuchContactException extends DbException {
+
+	private static final long serialVersionUID = -7048538231308207386L;
+}

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

@@ -0,0 +1,11 @@
+package org.briarproject.api.db;
+
+/**
+ * Thrown when a database operation is attempted for a pseudonym that is not in
+ * the database. This exception may occur due to concurrent updates and does
+ * not indicate a database error.
+ */
+public class NoSuchLocalAuthorException extends DbException {
+
+	private static final long serialVersionUID = 494398665376703860L;
+}

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

@@ -0,0 +1,11 @@
+package org.briarproject.api.db;
+
+/**
+ * Thrown when a database operation is attempted for a message that is not in
+ * the database. This exception may occur due to concurrent updates and does
+ * not indicate a database error.
+ */
+public class NoSuchMessageException extends DbException {
+
+	private static final long serialVersionUID = 9191508339698803848L;
+}

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

@@ -0,0 +1,12 @@
+package org.briarproject.api.db;
+
+/**
+ * Thrown when a database operation is attempted for a group to which the user
+ * does not subscribe. This exception may occur due to concurrent updates and
+ * does not indicate a database error.
+ */
+public class NoSuchSubscriptionException extends DbException {
+
+	private static final long serialVersionUID = -5494178507342571697L;
+
+}

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

@@ -0,0 +1,11 @@
+package org.briarproject.api.db;
+
+/**
+ * Thrown when a database operation is attempted for a transport that is not in
+ * the database. This exception may occur due to concurrent updates and does
+ * not indicate a database error.
+ */
+public class NoSuchTransportException extends DbException {
+
+	private static final long serialVersionUID = -6274982612759573100L;
+}

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

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

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

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

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

@@ -0,0 +1,6 @@
+package org.briarproject.api.event;
+
+/** An abstract superclass for events. */
+public abstract class Event {
+
+}

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

@@ -0,0 +1,7 @@
+package org.briarproject.api.event;
+
+/** An interface for receiving notifications when events occur. */
+public interface EventListener {
+
+	void eventOccurred(Event e);
+}

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

@@ -0,0 +1,17 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.AuthorId;
+
+/** An event that is broadcast when a local pseudonym is added. */
+public class LocalAuthorAddedEvent extends Event {
+
+	private final AuthorId authorId;
+
+	public LocalAuthorAddedEvent(AuthorId authorId) {
+		this.authorId = authorId;
+	}
+
+	public AuthorId getAuthorId() {
+		return authorId;
+	}
+}

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

@@ -0,0 +1,17 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.AuthorId;
+
+/** An event that is broadcast when a local pseudonym is removed. */
+public class LocalAuthorRemovedEvent extends Event {
+
+	private final AuthorId authorId;
+
+	public LocalAuthorRemovedEvent(AuthorId authorId) {
+		this.authorId = authorId;
+	}
+
+	public AuthorId getAuthorId() {
+		return authorId;
+	}
+}

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

@@ -0,0 +1,23 @@
+package org.briarproject.api.event;
+
+import java.util.Collection;
+
+import org.briarproject.api.ContactId;
+
+/**
+ * An event that is broadcast when the set of subscriptions visible to one or
+ * more contacts is updated.
+ */
+public class LocalSubscriptionsUpdatedEvent extends Event {
+
+	private final Collection<ContactId> affected;
+
+	public LocalSubscriptionsUpdatedEvent(Collection<ContactId> affected) {
+		this.affected = affected;
+	}
+
+	/** Returns the contacts affected by the update. */
+	public Collection<ContactId> getAffectedContacts() {
+		return affected;
+	}
+}

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

@@ -0,0 +1,9 @@
+package org.briarproject.api.event;
+
+/**
+ * An event that is broadcast when the local transport properties are
+ * updated.
+ */
+public class LocalTransportsUpdatedEvent extends Event {
+
+}

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

@@ -0,0 +1,29 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.ContactId;
+import org.briarproject.api.messaging.Group;
+
+/** An event that is broadcast when a message is added to the database. */
+public class MessageAddedEvent extends Event {
+
+	private final Group group;
+	private final ContactId contactId;
+
+	public MessageAddedEvent(Group group, ContactId contactId) {
+		this.group = group;
+		this.contactId = contactId;
+	}
+
+	/** Returns the group to which the message belongs. */
+	public Group getGroup() {
+		return group;
+	}
+
+	/**
+	 * Returns the ID of the contact from which the message was received, or
+	 * null if the message was locally generated.
+	 */
+	public ContactId getContactId() {
+		return contactId;
+	}
+}

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

@@ -0,0 +1,9 @@
+package org.briarproject.api.event;
+
+/**
+ * An event that is broadcast when one or messages expire from the database,
+ * potentially changing the database's retention time.
+ */
+public class MessageExpiredEvent extends Event {
+
+}

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

@@ -0,0 +1,17 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.ContactId;
+
+/** An event that is broadcast when a message is requested by a contact. */
+public class MessageRequestedEvent extends Event {
+
+	private final ContactId contactId;
+
+	public MessageRequestedEvent(ContactId contactId) {
+		this.contactId = contactId;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+}

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

@@ -0,0 +1,20 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.ContactId;
+
+/**
+ * An event that is broadcast when a message is received from or offered by a
+ * contact and needs to be acknowledged.
+ */
+public class MessageToAckEvent extends Event {
+
+	private final ContactId contactId;
+
+	public MessageToAckEvent(ContactId contactId) {
+		this.contactId = contactId;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+}

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

@@ -0,0 +1,20 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.ContactId;
+
+/**
+ * An event that is broadcast when a message is offered by a contact and needs
+ * to be requested.
+ */
+public class MessageToRequestEvent extends Event {
+
+	private final ContactId contactId;
+
+	public MessageToRequestEvent(ContactId contactId) {
+		this.contactId = contactId;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+}

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

@@ -0,0 +1,20 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.ContactId;
+
+/**
+ * An event that is broadcast when the retention time of a contact's database
+ * changes.
+ */
+public class RemoteRetentionTimeUpdatedEvent extends Event {
+
+	private final ContactId contactId;
+
+	public RemoteRetentionTimeUpdatedEvent(ContactId contactId) {
+		this.contactId = contactId;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+}

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

@@ -0,0 +1,17 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.ContactId;
+
+/**  An event that is broadcast when a contact's subscriptions are updated. */
+public class RemoteSubscriptionsUpdatedEvent extends Event {
+
+	private final ContactId contactId;
+
+	public RemoteSubscriptionsUpdatedEvent(ContactId contactId) {
+		this.contactId = contactId;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+}

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

@@ -0,0 +1,28 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.ContactId;
+import org.briarproject.api.TransportId;
+
+/**
+ * An event that is broadcast when a contact's remote transport properties
+ * are updated.
+ */
+public class RemoteTransportsUpdatedEvent extends Event {
+
+	private final ContactId contactId;
+	private final TransportId transportId;
+
+	public RemoteTransportsUpdatedEvent(ContactId contactId,
+			TransportId transportId) {
+		this.contactId = contactId;
+		this.transportId = transportId;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+
+	public TransportId getTransportId() {
+		return transportId;
+	}
+}

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

@@ -0,0 +1,17 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.messaging.Group;
+
+/** An event that is broadcast when the user subscribes to a group. */
+public class SubscriptionAddedEvent extends Event {
+
+	private final Group group;
+
+	public SubscriptionAddedEvent(Group group) {
+		this.group = group;
+	}
+
+	public Group getGroup() {
+		return group;
+	}
+}

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

@@ -0,0 +1,17 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.messaging.Group;
+
+/** An event that is broadcast when the user unsubscribes from a group. */
+public class SubscriptionRemovedEvent extends Event {
+
+	private final Group group;
+
+	public SubscriptionRemovedEvent(Group group) {
+		this.group = group;
+	}
+
+	public Group getGroup() {
+		return group;
+	}
+}

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

@@ -0,0 +1,23 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.TransportId;
+
+/** An event that is broadcast when a transport is added. */
+public class TransportAddedEvent extends Event {
+
+	private final TransportId transportId;
+	private final long maxLatency;
+
+	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/org/briarproject/api/event/TransportRemovedEvent.java

@@ -0,0 +1,17 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.TransportId;
+
+/** An event that is broadcast when a transport is removed. */
+public class TransportRemovedEvent extends Event {
+
+	private final TransportId transportId;
+
+	public TransportRemovedEvent(TransportId transportId) {
+		this.transportId = transportId;
+	}
+
+	public TransportId getTransportId() {
+		return transportId;
+	}
+}

briar-api/src/org/briarproject/api/invitation/InvitationConstants.java

@@ -0,0 +1,14 @@
+package org.briarproject.api.invitation;
+
+public interface InvitationConstants {
+
+	long CONNECTION_TIMEOUT = 30 * 1000; // Milliseconds
+
+	long CONFIRMATION_TIMEOUT = 60 * 1000; // Milliseconds
+
+	int CODE_BITS = 19; // Codes must fit into six decimal digits
+
+	int HASH_LENGTH = 48; // Bytes
+
+	int MAX_PUBLIC_KEY_LENGTH = 97; // Bytes
+}

briar-api/src/org/briarproject/api/invitation/InvitationListener.java

@@ -0,0 +1,47 @@
+package org.briarproject.api.invitation;
+
+/**
+ * An interface for receiving updates about the state of an
+ * {@link InvitationTask}.
+ */
+public interface InvitationListener {
+
+	/** Called if a connection to the remote peer is established. */
+	void connectionSucceeded();
+
+	/**
+	 * Called if a connection to the remote peer cannot be established. This
+	 * indicates that the protocol has ended unsuccessfully.
+	 */
+	void connectionFailed();
+
+	/** Called if key agreement with the remote peer succeeds. */
+	void keyAgreementSucceeded(int localCode, int remoteCode);
+
+	/**
+	 * Called if key agreement with the remote peer fails or the connection is
+	 * lost. This indicates that the protocol has ended unsuccessfully.
+	 */
+	void keyAgreementFailed();
+
+	/** Called if the remote peer's confirmation check succeeds. */
+	void remoteConfirmationSucceeded();
+
+	/**
+	 * Called if remote peer's confirmation check fails or the connection is
+	 * lost. This indicates that the protocol has ended unsuccessfully.
+	 */
+	void remoteConfirmationFailed();
+
+	/**
+	 * 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 or the connection is lost.
+	 * This indicates that the protocol has ended unsuccessfully.
+	 */
+	void pseudonymExchangeFailed();
+}

briar-api/src/org/briarproject/api/invitation/InvitationState.java

@@ -0,0 +1,73 @@
+package org.briarproject.api.invitation;
+
+public class InvitationState {
+
+	private final int localInvitationCode, remoteInvitationCode;
+	private final int localConfirmationCode, remoteConfirmationCode;
+	private final boolean connected, 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 connected, boolean connectionFailed, boolean localCompared,
+			boolean remoteCompared, boolean localMatched,
+			boolean remoteMatched, String contactName) {
+		this.localInvitationCode = localInvitationCode;
+		this.remoteInvitationCode = remoteInvitationCode;
+		this.localConfirmationCode = localConfirmationCode;
+		this.remoteConfirmationCode = remoteConfirmationCode;
+		this.connected = connected;
+		this.connectionFailed = connectionFailed;
+		this.localCompared = localCompared;
+		this.remoteCompared = remoteCompared;
+		this.localMatched = localMatched;
+		this.remoteMatched = remoteMatched;
+		this.contactName = contactName;
+	}
+
+	public int getLocalInvitationCode() {
+		return localInvitationCode;
+	}
+
+	public int getRemoteInvitationCode() {
+		return remoteInvitationCode;
+	}
+
+	public int getLocalConfirmationCode() {
+		return localConfirmationCode;
+	}
+
+	public int getRemoteConfirmationCode() {
+		return remoteConfirmationCode;
+	}
+
+	public boolean getConnected() {
+		return connected;
+	}
+
+	public boolean getConnectionFailed() {
+		return connectionFailed;
+	}
+
+	public boolean getLocalCompared() {
+		return localCompared;
+	}
+
+	public boolean getRemoteCompared() {
+		return remoteCompared;
+	}
+
+	public boolean getLocalMatched() {
+		return localMatched;
+	}
+
+	public boolean getRemoteMatched() {
+		return remoteMatched;
+	}
+
+	public String getContactName() {
+		return contactName;
+	}
+}

briar-api/src/org/briarproject/api/invitation/InvitationTask.java

@@ -0,0 +1,29 @@
+package org.briarproject.api.invitation;
+
+/** A task for exchanging invitations with a remote peer. */
+public interface InvitationTask {
+
+	/**
+	 * Adds a listener to be informed of state changes and returns the
+	 * task's current state.
+	 */
+	InvitationState addListener(InvitationListener l);
+
+	/** Removes the given listener. */
+	void removeListener(InvitationListener l);
+
+	/** Asynchronously starts the connection process. */
+	void connect();
+
+	/**
+	 * Asynchronously informs the remote peer that the local peer's
+	 * confirmation codes matched.
+	 */
+	void localConfirmationSucceeded();
+
+	/**
+	 * Asynchronously informs the remote peer that the local peer's
+	 * confirmation codes did not match.
+	 */
+	void localConfirmationFailed();
+}

briar-api/src/org/briarproject/api/invitation/InvitationTaskFactory.java

@@ -0,0 +1,11 @@
+package org.briarproject.api.invitation;
+
+import org.briarproject.api.AuthorId;
+
+/** Creates tasks for exchanging invitations with remote peers. */
+public interface InvitationTaskFactory {
+
+	/** Creates a task using the given pseudonym and invitation codes. */
+	InvitationTask createTask(AuthorId localAuthorId, int localCode,
+			int remoteCode);
+}

briar-api/src/org/briarproject/api/lifecycle/LifecycleManager.java

@@ -0,0 +1,37 @@
+package org.briarproject.api.lifecycle;
+
+import java.util.concurrent.ExecutorService;
+
+public interface LifecycleManager {
+
+	/** Registers a {@link Service} to be started and stopped. */
+	public void register(Service s);
+
+	/**
+	 * Registers an {@link java.util.concurrent.ExecutorService ExecutorService}
+	 * to be shut down.
+	 */
+	public void registerForShutdown(ExecutorService e);
+
+	/**  Starts any registered {@link Service}s. */
+	public void startServices();
+
+	/**
+	 * Stops any registered {@link Service}s and shuts down any registered
+	 * {@link java.util.concurrent.ExecutorService ExecutorService}s.
+	 */
+	public void stopServices();
+
+	/** Waits for the database to be opened before returning. */
+	public void waitForDatabase() throws InterruptedException;
+
+	/** Waits for all registered {@link Service}s to start before returning. */
+	public void waitForStartup() throws InterruptedException;
+
+	/**
+	 * Waits for all registered {@link Service}s to stop and all registered
+	 * {@link java.util.concurrent.ExecutorService ExecutorService}s to shut
+	 * down before returning.
+	 */
+	public void waitForShutdown() throws InterruptedException;
+}

briar-api/src/org/briarproject/api/lifecycle/Service.java

@@ -0,0 +1,10 @@
+package org.briarproject.api.lifecycle;
+
+public interface Service {
+
+	/** Starts the service and returns true if it started successfully. */
+	public boolean start();
+
+	/** Stops the service and returns true if it stopped successfully. */
+	public boolean stop();
+}

briar-api/src/org/briarproject/api/lifecycle/ShutdownManager.java

@@ -0,0 +1,16 @@
+package org.briarproject.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);
+}

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

@@ -0,0 +1,18 @@
+package org.briarproject.api.messaging;
+
+import java.util.Collection;
+
+/** A packet acknowledging receipt of one or more {@link Message}s. */
+public class Ack {
+
+	private final Collection<MessageId> acked;
+
+	public Ack(Collection<MessageId> acked) {
+		this.acked = acked;
+	}
+
+	/** Returns the identifiers of the acknowledged messages. */
+	public Collection<MessageId> getMessageIds() {
+		return acked;
+	}
+}

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

@@ -0,0 +1,43 @@
+package org.briarproject.api.messaging;
+
+/** A group to which users may subscribe. */
+public class Group {
+
+	private final GroupId id;
+	private final String name;
+	private final byte[] salt;
+
+	public Group(GroupId id, String name, byte[] salt) {
+		this.id = id;
+		this.name = name;
+		this.salt = salt;
+	}
+
+	/** Returns the group's unique identifier. */
+	public GroupId getId() {
+		return id;
+	}
+
+	/** Returns the group's name. */
+	public String getName() {
+		return name;
+	}
+
+	/**
+	 * Returns the salt used to distinguish the group from other groups with
+	 * the same name.
+	 */
+	public byte[] getSalt() {
+		return salt;
+	}
+
+	@Override
+	public int hashCode() {
+		return id.hashCode();
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		return o instanceof Group && id.equals(((Group) o).id);
+	}
+}

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

@@ -0,0 +1,10 @@
+package org.briarproject.api.messaging;
+
+public interface GroupFactory {
+
+	/** Creates a group with the given name and a random salt. */
+	Group createGroup(String name);
+
+	/** Creates a group with the given name and salt. */
+	Group createGroup(String name, byte[] salt);
+}

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

@@ -0,0 +1,22 @@
+package org.briarproject.api.messaging;
+
+import java.util.Arrays;
+
+import org.briarproject.api.UniqueId;
+
+/**
+ * Type-safe wrapper for a byte array that uniquely identifies a {@link Group}.
+ */
+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;
+	}
+}

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

@@ -0,0 +1,25 @@
+package org.briarproject.api.messaging;
+
+public class GroupStatus {
+
+	private final Group group;
+	private final boolean subscribed, visibleToAll;
+
+	public GroupStatus(Group group, boolean subscribed, boolean visibleToAll) {
+		this.group = group;
+		this.subscribed = subscribed;
+		this.visibleToAll = visibleToAll;
+	}
+
+	public Group getGroup() {
+		return group;
+	}
+
+	public boolean isSubscribed() {
+		return subscribed;
+	}
+
+	public boolean isVisibleToAll() {
+		return visibleToAll;
+	}
+}

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

@@ -0,0 +1,42 @@
+package org.briarproject.api.messaging;
+
+import org.briarproject.api.Author;
+
+public interface Message {
+
+	/** Returns the message's unique identifier. */
+	MessageId getId();
+
+	/**
+	 * Returns the identifier of the message's parent, or null if this is the
+	 * first message in a thread.
+	 */
+	MessageId getParent();
+
+	/**
+	 * Returns the {@link Group} to which the message belongs, or null if this
+	 * is a private message.
+	 */
+	Group getGroup();
+
+	/**
+	 * Returns the message's {@link org.briarproject.api.Author Author}, or null
+	 * if this is an anonymous message.
+	 */
+	Author getAuthor();
+
+	/** Returns the message's content type. */
+	String getContentType();
+
+	/** Returns the message's timestamp. */
+	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();
+}

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

@@ -0,0 +1,19 @@
+package org.briarproject.api.messaging;
+
+import java.io.IOException;
+import java.security.GeneralSecurityException;
+
+import org.briarproject.api.Author;
+import org.briarproject.api.crypto.PrivateKey;
+
+public interface MessageFactory {
+
+	Message createAnonymousMessage(MessageId parent, Group group,
+			String contentType, long timestamp, byte[] body) throws IOException,
+			GeneralSecurityException;
+
+	Message createPseudonymousMessage(MessageId parent, Group group,
+			Author author, PrivateKey privateKey, String contentType,
+			long timestamp, byte[] body) throws IOException,
+			GeneralSecurityException;
+}

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

@@ -0,0 +1,23 @@
+package org.briarproject.api.messaging;
+
+import java.util.Arrays;
+
+import org.briarproject.api.UniqueId;
+
+/**
+ * Type-safe wrapper for a byte array that uniquely identifies a
+ * {@link 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;
+	}
+}

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

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

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

@@ -0,0 +1,45 @@
+package org.briarproject.api.messaging;
+
+import static org.briarproject.api.transport.TransportConstants.MIN_CONNECTION_LENGTH;
+
+public interface MessagingConstants {
+
+	/**
+	 * 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 public groups a user may subscribe to. */
+	int MAX_SUBSCRIPTIONS = 3000;
+
+	/** The maximum length of a group's name in UTF-8 bytes. */
+	int MAX_GROUP_NAME_LENGTH = 50;
+
+	/** The length of a group's random salt in bytes. */
+	int GROUP_SALT_LENGTH = 32;
+
+	/**
+	 * The maximum length of a message body in bytes. To allow for future
+	 * changes in the protocol, this is smaller than the maximum 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 content type in UTF-8 bytes. */
+	int MAX_CONTENT_TYPE_LENGTH = 50;
+
+	/** The maximum length of a message's subject line in UTF-8 bytes. */
+	int MAX_SUBJECT_LENGTH = 100;
+
+	/** The length of a message's random salt in bytes. */
+	int MESSAGE_SALT_LENGTH = 32;
+
+	/**
+	 * When calculating the retention time of the database, the timestamp of
+	 * the oldest message in the database is rounded down to a multiple of
+	 * this value to avoid revealing the presence of any particular message.
+	 */
+	int RETENTION_GRANULARITY = 60 * 1000; // 1 minute
+}

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

@@ -0,0 +1,18 @@
+package org.briarproject.api.messaging;
+
+import java.util.Collection;
+
+/** A packet offering the recipient one or more {@link Messages}. */
+public class Offer {
+
+	private final Collection<MessageId> offered;
+
+	public Offer(Collection<MessageId> offered) {
+		this.offered = offered;
+	}
+
+	/** Returns the identifiers of the offered messages. */
+	public Collection<MessageId> getMessageIds() {
+		return offered;
+	}
+}

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

@@ -0,0 +1,38 @@
+package org.briarproject.api.messaging;
+
+import java.io.IOException;
+
+public interface PacketReader {
+
+	boolean eof() throws IOException;
+
+	boolean hasAck() throws IOException;
+	Ack readAck() throws IOException;
+
+	boolean hasMessage() throws IOException;
+	UnverifiedMessage readMessage() throws IOException;
+
+	boolean hasOffer() throws IOException;
+	Offer readOffer() throws IOException;
+
+	boolean hasRequest() throws IOException;
+	Request readRequest() throws IOException;
+
+	boolean hasRetentionAck() throws IOException;
+	RetentionAck readRetentionAck() throws IOException;
+
+	boolean hasRetentionUpdate() throws IOException;
+	RetentionUpdate readRetentionUpdate() throws IOException;
+
+	boolean hasSubscriptionAck() throws IOException;
+	SubscriptionAck readSubscriptionAck() throws IOException;
+
+	boolean hasSubscriptionUpdate() throws IOException;
+	SubscriptionUpdate readSubscriptionUpdate() throws IOException;
+
+	boolean hasTransportAck() throws IOException;
+	TransportAck readTransportAck() throws IOException;
+
+	boolean hasTransportUpdate() throws IOException;
+	TransportUpdate readTransportUpdate() throws IOException;
+}

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

@@ -0,0 +1,8 @@
+package org.briarproject.api.messaging;
+
+import java.io.InputStream;
+
+public interface PacketReaderFactory {
+
+	PacketReader createPacketReader(InputStream in);
+}

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

@@ -0,0 +1,34 @@
+package org.briarproject.api.messaging;
+
+import java.io.IOException;
+
+public interface PacketWriter {
+
+	int getMaxMessagesForRequest(long capacity);
+
+	int getMaxMessagesForOffer(long capacity);
+
+	void writeAck(Ack a) throws IOException;
+
+	void writeMessage(byte[] raw) throws IOException;
+
+	void writeOffer(Offer o) throws IOException;
+
+	void writeRequest(Request r) throws IOException;
+
+	void writeRetentionAck(RetentionAck a) throws IOException;
+
+	void writeRetentionUpdate(RetentionUpdate u) throws IOException;
+
+	void writeSubscriptionAck(SubscriptionAck a) throws IOException;
+
+	void writeSubscriptionUpdate(SubscriptionUpdate u) throws IOException;
+
+	void writeTransportAck(TransportAck a) throws IOException;
+
+	void writeTransportUpdate(TransportUpdate u) throws IOException;
+
+	void flush() throws IOException;
+
+	void close() throws IOException;
+}

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

@@ -0,0 +1,8 @@
+package org.briarproject.api.messaging;
+
+import java.io.OutputStream;
+
+public interface PacketWriterFactory {
+
+	PacketWriter createPacketWriter(OutputStream out, boolean flush);
+}

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

@@ -0,0 +1,18 @@
+package org.briarproject.api.messaging;
+
+import java.util.Collection;
+
+/** A packet requesting one or more {@link Message}s from the recipient. */
+public class Request {
+
+	private final Collection<MessageId> requested;
+
+	public Request(Collection<MessageId> requested) {
+		this.requested = requested;
+	}
+
+	/** Returns the identifiers of the requested messages. */
+	public Collection<MessageId> getMessageIds() {
+		return requested;
+	}
+}

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

@@ -0,0 +1,16 @@
+package org.briarproject.api.messaging;
+
+/** A packet acknowledging a (@link RetentionUpdate} */
+public class RetentionAck {
+
+	private final long version;
+
+	public RetentionAck(long version) {
+		this.version = version;
+	}
+
+	/** Returns the version number of the acknowledged update. */
+	public long getVersion() {
+		return version;
+	}
+}

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

@@ -0,0 +1,23 @@
+package org.briarproject.api.messaging;
+
+/**
+ * A packet updating the recipient's view of the retention time of the sender's
+ * database.
+ */
+public class RetentionUpdate {
+
+	private final long retention, version;
+
+	public RetentionUpdate(long retention, long version) {
+		this.retention = retention;
+		this.version = version;
+	}
+
+	public long getRetentionTime() {
+		return retention;
+	}
+
+	public long getVersion() {
+		return version;
+	}
+}

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

@@ -0,0 +1,16 @@
+package org.briarproject.api.messaging;
+
+/** A packet acknowledging a {@link SubscriptionUpdate}. */
+public class SubscriptionAck {
+
+	private final long version;
+
+	public SubscriptionAck(long version) {
+		this.version = version;
+	}
+
+	/** Returns the version number of the acknowledged update. */
+	public long getVersion() {
+		return version;
+	}
+}

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

@@ -0,0 +1,28 @@
+package org.briarproject.api.messaging;
+
+import java.util.Collection;
+
+/** A packet updating the recipient's view of the sender's subscriptions. */
+public class SubscriptionUpdate {
+
+	private final Collection<Group> groups;
+	private final long version;
+
+	public SubscriptionUpdate(Collection<Group> groups, long version) {
+		this.groups = groups;
+		this.version = version;
+	}
+
+	/**
+	 * Returns the groups to which the sender subscribes, and which the sender
+	 * has made visible to the recipient.
+	 */
+	public Collection<Group> getGroups() {
+		return groups;
+	}
+
+	/** Returns the update's version number. */
+	public long getVersion() {
+		return version;
+	}
+}

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

@@ -0,0 +1,25 @@
+package org.briarproject.api.messaging;
+
+import org.briarproject.api.TransportId;
+
+/** A packet acknowledging a {@link TransportUpdate}. */
+public class TransportAck {
+
+	private final TransportId id;
+	private final long version;
+
+	public TransportAck(TransportId id, long version) {
+		this.id = id;
+		this.version = version;
+	}
+
+	/** Returns the identifier of the updated transport. */
+	public TransportId getId() {
+		return id;
+	}
+
+	/** Returns the version number of the acknowledged update. */
+	public long getVersion() {
+		return version;
+	}
+}

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

@@ -0,0 +1,36 @@
+package org.briarproject.api.messaging;
+
+import org.briarproject.api.TransportId;
+import org.briarproject.api.TransportProperties;
+
+/**
+ * A packet updating the recipient's view of the sender's transport properties.
+ */
+public class TransportUpdate {
+
+	private final TransportId id;
+	private final TransportProperties properties;
+	private final long version;
+
+	public TransportUpdate(TransportId id, TransportProperties properties,
+			long version) {
+		this.id = id;
+		this.properties = properties;
+		this.version = version;
+	}
+
+	/** Returns the identifier of the updated transport. */
+	public TransportId getId() {
+		return id;
+	}
+
+	/** Returns the transport's updated properties. */
+	public TransportProperties getProperties() {
+		return properties;
+	}
+
+	/** Returns the update's version number. */
+	public long getVersion() {
+		return version;
+	}
+}

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

@@ -0,0 +1,18 @@
+package org.briarproject.api.messaging;
+
+/** Struct identifiers for encoding and decoding protocol objects. */
+public interface Types {
+
+	int AUTHOR = 0;
+	int GROUP = 1;
+	int ACK = 2;
+	int MESSAGE = 3;
+	int OFFER = 4;
+	int REQUEST = 5;
+	int RETENTION_ACK = 6;
+	int RETENTION_UPDATE = 7;
+	int SUBSCRIPTION_ACK = 8;
+	int SUBSCRIPTION_UPDATE = 9;
+	int TRANSPORT_ACK = 10;
+	int TRANSPORT_UPDATE = 11;
+}

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

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

briar-api/src/org/briarproject/api/messaging/duplex/DuplexConnectionFactory.java

@@ -0,0 +1,15 @@
+package org.briarproject.api.messaging.duplex;
+
+import org.briarproject.api.ContactId;
+import org.briarproject.api.TransportId;
+import org.briarproject.api.plugins.duplex.DuplexTransportConnection;
+import org.briarproject.api.transport.ConnectionContext;
+
+public interface DuplexConnectionFactory {
+
+	void createIncomingConnection(ConnectionContext ctx,
+			DuplexTransportConnection d);
+
+	void createOutgoingConnection(ContactId c, TransportId t,
+			DuplexTransportConnection d);
+}

briar-api/src/org/briarproject/api/messaging/simplex/SimplexConnectionFactory.java

@@ -0,0 +1,16 @@
+package org.briarproject.api.messaging.simplex;
+
+import org.briarproject.api.ContactId;
+import org.briarproject.api.TransportId;
+import org.briarproject.api.plugins.simplex.SimplexTransportReader;
+import org.briarproject.api.plugins.simplex.SimplexTransportWriter;
+import org.briarproject.api.transport.ConnectionContext;
+
+public interface SimplexConnectionFactory {
+
+	void createIncomingConnection(ConnectionContext ctx,
+			SimplexTransportReader r);
+
+	void createOutgoingConnection(ContactId c, TransportId t,
+			SimplexTransportWriter w);
+}

briar-api/src/org/briarproject/api/plugins/Plugin.java

@@ -0,0 +1,47 @@
+package org.briarproject.api.plugins;
+
+import java.io.IOException;
+import java.util.Collection;
+
+import org.briarproject.api.ContactId;
+import org.briarproject.api.TransportId;
+
+public interface Plugin {
+
+	/** Returns the plugin's transport identifier. */
+	TransportId getId();
+
+	/** Returns a label for looking up the plugin's translated name. */
+	String getName();
+
+	/** Returns the transport's maximum frame length in bytes. */
+	int getMaxFrameLength();
+
+	/** Returns the transport's maximum latency in milliseconds. */
+	long getMaxLatency();
+
+	/** Starts the plugin and returns true if it started successfully. */
+	boolean start() throws IOException;
+
+	/** Stops the plugin. */
+	void stop() throws IOException;
+
+	/**
+	 * Returns true if the plugin's {@link #poll(Collection)} method should be
+	 * called periodically to attempt to establish connections.
+	 */
+	boolean shouldPoll();
+
+	/**
+	 * Returns the desired interval in milliseconds between calls to the
+	 * plugin's {@link #poll(Collection)} 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);
+}

briar-api/src/org/briarproject/api/plugins/PluginCallback.java

@@ -0,0 +1,52 @@
+package org.briarproject.api.plugins;
+
+import java.util.Map;
+
+import org.briarproject.api.ContactId;
+import org.briarproject.api.TransportConfig;
+import org.briarproject.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();
+
+	/** Merges the given configuration with the plugin's configuration. */
+	void mergeConfig(TransportConfig c);
+
+	/**
+	 * Merges the given properties with the plugin's local transport properties.
+	 */
+	void mergeLocalProperties(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);
+}

briar-api/src/org/briarproject/api/plugins/PluginExecutor.java

@@ -0,0 +1,17 @@
+package org.briarproject.api.plugins;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+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({ FIELD, METHOD, PARAMETER })
+@Retention(RUNTIME)
+public @interface PluginExecutor {}

briar-api/src/org/briarproject/api/plugins/PluginManager.java

@@ -0,0 +1,16 @@
+package org.briarproject.api.plugins;
+
+import java.util.Collection;
+
+import org.briarproject.api.lifecycle.Service;
+import org.briarproject.api.plugins.duplex.DuplexPlugin;
+
+/**
+ * Responsible for starting transport plugins at startup, stopping them at
+ * shutdown, and providing access to plugins for exchanging invitations.
+ */
+public interface PluginManager extends Service {
+
+	/** Returns any running duplex plugins that support invitations. */
+	Collection<DuplexPlugin> getInvitationPlugins();
+}