Changed the message format to store the author and group inline - this

doesn't take a huge amount of space and allows every message to be
self-certifying.

components/net/sf/briar/protocol/AuthorFactoryImpl.java

@@ -0,0 +1,42 @@
+package net.sf.briar.protocol;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.security.MessageDigest;
+
+import net.sf.briar.api.crypto.CryptoComponent;
+import net.sf.briar.api.protocol.Author;
+import net.sf.briar.api.protocol.AuthorFactory;
+import net.sf.briar.api.protocol.AuthorId;
+import net.sf.briar.api.serial.Writer;
+import net.sf.briar.api.serial.WriterFactory;
+
+import com.google.inject.Inject;
+
+class AuthorFactoryImpl implements AuthorFactory {
+
+	private final CryptoComponent crypto;
+	private final WriterFactory writerFactory;
+
+	@Inject
+	AuthorFactoryImpl(CryptoComponent crypto, WriterFactory writerFactory) {
+		this.crypto = crypto;
+		this.writerFactory = writerFactory;
+	}
+
+	public Author createAuthor(String name, byte[] publicKey)
+	throws IOException {
+		ByteArrayOutputStream out = new ByteArrayOutputStream();
+		Writer w = writerFactory.createWriter(out);
+		new AuthorImpl(null, name, publicKey).writeTo(w);
+		MessageDigest messageDigest = crypto.getMessageDigest();
+		messageDigest.reset();
+		messageDigest.update(out.toByteArray());
+		AuthorId id = new AuthorId(messageDigest.digest());
+		return new AuthorImpl(id, name, publicKey);
+	}
+
+	public Author createAuthor(AuthorId id, String name, byte[] publicKey) {
+		return new AuthorImpl(id, name, publicKey);
+	}
+}

components/net/sf/briar/protocol/AuthorImpl.java

@@ -0,0 +1,39 @@
+package net.sf.briar.protocol;
+
+import java.io.IOException;
+
+import net.sf.briar.api.protocol.Author;
+import net.sf.briar.api.protocol.AuthorId;
+import net.sf.briar.api.protocol.Tags;
+import net.sf.briar.api.serial.Writer;
+
+class AuthorImpl implements Author {
+
+	private final AuthorId id;
+	private final String name;
+	private final byte[] publicKey;
+
+	AuthorImpl(AuthorId id, String name, byte[] publicKey) {
+		this.id = id;
+		this.name = name;
+		this.publicKey = publicKey;
+	}
+
+	public AuthorId getId() {
+		return id;
+	}
+
+	public String getName() {
+		return name;
+	}
+
+	public byte[] getPublicKey() {
+		return publicKey;
+	}
+
+	public void writeTo(Writer w) throws IOException {
+		w.writeUserDefinedTag(Tags.AUTHOR);
+		w.writeString(name);
+		w.writeBytes(publicKey);
+	}
+}

components/net/sf/briar/protocol/AuthorReader.java

@@ -0,0 +1,38 @@
+package net.sf.briar.protocol;
+
+import java.io.IOException;
+import java.security.MessageDigest;
+
+import net.sf.briar.api.crypto.CryptoComponent;
+import net.sf.briar.api.protocol.Author;
+import net.sf.briar.api.protocol.AuthorFactory;
+import net.sf.briar.api.protocol.AuthorId;
+import net.sf.briar.api.protocol.Tags;
+import net.sf.briar.api.serial.ObjectReader;
+import net.sf.briar.api.serial.Reader;
+
+class AuthorReader implements ObjectReader<Author> {
+
+	private final MessageDigest messageDigest;
+	private final AuthorFactory authorFactory;
+
+	AuthorReader(CryptoComponent crypto, AuthorFactory authorFactory) {
+		messageDigest = crypto.getMessageDigest();
+		this.authorFactory = authorFactory;
+	}
+
+	public Author readObject(Reader r) throws IOException {
+		// Initialise the consumer
+		DigestingConsumer digesting = new DigestingConsumer(messageDigest);
+		messageDigest.reset();
+		// Read and digest the data
+		r.addConsumer(digesting);
+		r.readUserDefinedTag(Tags.AUTHOR);
+		String name = r.readString();
+		byte[] publicKey = r.readBytes();
+		r.removeConsumer(digesting);
+		// Build and return the author
+		AuthorId id = new AuthorId(messageDigest.digest());
+		return authorFactory.createAuthor(id, name, publicKey);
+	}
+}

components/net/sf/briar/protocol/BatchReader.java

@@ -4,6 +4,7 @@ import java.io.IOException;
 import java.security.MessageDigest;
 import java.util.List;
 
+import net.sf.briar.api.crypto.CryptoComponent;
 import net.sf.briar.api.protocol.Batch;
 import net.sf.briar.api.protocol.BatchId;
 import net.sf.briar.api.protocol.Message;
@@ -17,9 +18,9 @@ class BatchReader implements ObjectReader<Batch> {
 	private final ObjectReader<Message> messageReader;
 	private final BatchFactory batchFactory;
 
-	BatchReader(MessageDigest messageDigest,
-			ObjectReader<Message> messageReader, BatchFactory batchFactory) {
-		this.messageDigest = messageDigest;
+	BatchReader(CryptoComponent crypto, ObjectReader<Message> messageReader,
+			BatchFactory batchFactory) {
+		messageDigest = crypto.getMessageDigest();
 		this.messageReader = messageReader;
 		this.batchFactory = batchFactory;
 	}

components/net/sf/briar/protocol/GroupFactoryImpl.java

@@ -1,11 +1,40 @@
 package net.sf.briar.protocol;
 
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.security.MessageDigest;
+
+import net.sf.briar.api.crypto.CryptoComponent;
 import net.sf.briar.api.protocol.Group;
 import net.sf.briar.api.protocol.GroupFactory;
 import net.sf.briar.api.protocol.GroupId;
+import net.sf.briar.api.serial.Writer;
+import net.sf.briar.api.serial.WriterFactory;
+
+import com.google.inject.Inject;
 
 class GroupFactoryImpl implements GroupFactory {
 
+	private final CryptoComponent crypto;
+	private final WriterFactory writerFactory;
+
+	@Inject
+	GroupFactoryImpl(CryptoComponent crypto, WriterFactory writerFactory) {
+		this.crypto = crypto;
+		this.writerFactory = writerFactory;
+	}
+
+	public Group createGroup(String name, byte[] publicKey) throws IOException {
+		ByteArrayOutputStream out = new ByteArrayOutputStream();
+		Writer w = writerFactory.createWriter(out);
+		new GroupImpl(null, name, publicKey).writeTo(w);
+		MessageDigest messageDigest = crypto.getMessageDigest();
+		messageDigest.reset();
+		messageDigest.update(out.toByteArray());
+		GroupId id = new GroupId(messageDigest.digest());
+		return new GroupImpl(id, name, publicKey);
+	}
+
 	public Group createGroup(GroupId id, String name, byte[] publicKey) {
 		return new GroupImpl(id, name, publicKey);
 	}

components/net/sf/briar/protocol/GroupReader.java

@@ -3,6 +3,7 @@ package net.sf.briar.protocol;
 import java.io.IOException;
 import java.security.MessageDigest;
 
+import net.sf.briar.api.crypto.CryptoComponent;
 import net.sf.briar.api.protocol.Group;
 import net.sf.briar.api.protocol.GroupFactory;
 import net.sf.briar.api.protocol.GroupId;
@@ -15,8 +16,8 @@ class GroupReader implements ObjectReader<Group> {
 	private final MessageDigest messageDigest;
 	private final GroupFactory groupFactory;
 
-	GroupReader(MessageDigest messageDigest, GroupFactory groupFactory) {
-		this.messageDigest = messageDigest;
+	GroupReader(CryptoComponent crypto, GroupFactory groupFactory) {
+		messageDigest = crypto.getMessageDigest();
 		this.groupFactory = groupFactory;
 	}
 

components/net/sf/briar/protocol/MessageEncoderImpl.java

@@ -3,13 +3,14 @@ package net.sf.briar.protocol;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.security.GeneralSecurityException;
-import java.security.KeyPair;
 import java.security.MessageDigest;
+import java.security.PrivateKey;
 import java.security.Signature;
 
 import net.sf.briar.api.crypto.CryptoComponent;
+import net.sf.briar.api.protocol.Author;
 import net.sf.briar.api.protocol.AuthorId;
-import net.sf.briar.api.protocol.GroupId;
+import net.sf.briar.api.protocol.Group;
 import net.sf.briar.api.protocol.Message;
 import net.sf.briar.api.protocol.MessageEncoder;
 import net.sf.briar.api.protocol.MessageId;
@@ -32,8 +33,30 @@ class MessageEncoderImpl implements MessageEncoder {
 		this.writerFactory = writerFactory;
 	}
 
-	public Message encodeMessage(MessageId parent, GroupId group, String nick,
-			KeyPair keyPair, byte[] body) throws IOException,
+	public Message encodeMessage(MessageId parent, Group group, byte[] body)
+	throws IOException {
+		long timestamp = System.currentTimeMillis();
+		ByteArrayOutputStream out = new ByteArrayOutputStream();
+		Writer w = writerFactory.createWriter(out);
+		// Write the message
+		w.writeUserDefinedTag(Tags.MESSAGE);
+		parent.writeTo(w);
+		group.writeTo(w);
+		w.writeNull(); // No author
+		w.writeInt64(timestamp);
+		w.writeBytes(body);
+		w.writeNull(); // No author's signature
+		byte[] raw = out.toByteArray();
+		// The message ID is the hash of the entire message
+		messageDigest.reset();
+		messageDigest.update(raw);
+		MessageId id = new MessageId(messageDigest.digest());
+		return new MessageImpl(id, parent, group.getId(), AuthorId.NONE,
+				timestamp, raw);
+	}
+
+	public Message encodeMessage(MessageId parent, Group group, Author author,
+			PrivateKey privateKey, byte[] body) throws IOException,
 			GeneralSecurityException {
 		long timestamp = System.currentTimeMillis();
 		ByteArrayOutputStream out = new ByteArrayOutputStream();
@@ -42,13 +65,12 @@ class MessageEncoderImpl implements MessageEncoder {
 		w.writeUserDefinedTag(Tags.MESSAGE);
 		parent.writeTo(w);
 		group.writeTo(w);
+		author.writeTo(w);
 		w.writeInt64(timestamp);
-		w.writeString(nick);
-		w.writeBytes(keyPair.getPublic().getEncoded());
 		w.writeBytes(body);
 		// Sign the message
 		byte[] signable = out.toByteArray();
-		signature.initSign(keyPair.getPrivate());
+		signature.initSign(privateKey);
 		signature.update(signable);
 		byte[] sig = signature.sign();
 		signable = null;
@@ -59,14 +81,14 @@ class MessageEncoderImpl implements MessageEncoder {
 		messageDigest.reset();
 		messageDigest.update(raw);
 		MessageId id = new MessageId(messageDigest.digest());
-		// The author ID is the hash of the author's nick and public key
+		// The author ID is the hash of the author object
 		out.reset();
 		w = writerFactory.createWriter(out);
-		w.writeString(nick);
-		w.writeBytes(keyPair.getPublic().getEncoded());
+		author.writeTo(w);
 		messageDigest.reset();
 		messageDigest.update(out.toByteArray());
 		AuthorId authorId = new AuthorId(messageDigest.digest());
-		return new MessageImpl(id, parent, group, authorId, timestamp, raw);
+		return new MessageImpl(id, parent, group.getId(), authorId, timestamp,
+				raw);
 	}
 }

components/net/sf/briar/protocol/MessageReader.java

@@ -6,11 +6,12 @@ import java.security.MessageDigest;
 import java.security.PublicKey;
 import java.security.Signature;
 import java.security.SignatureException;
-import java.security.spec.InvalidKeySpecException;
 
+import net.sf.briar.api.crypto.CryptoComponent;
 import net.sf.briar.api.crypto.KeyParser;
+import net.sf.briar.api.protocol.Author;
 import net.sf.briar.api.protocol.AuthorId;
-import net.sf.briar.api.protocol.GroupId;
+import net.sf.briar.api.protocol.Group;
 import net.sf.briar.api.protocol.Message;
 import net.sf.briar.api.protocol.MessageId;
 import net.sf.briar.api.protocol.Tags;
@@ -21,15 +22,19 @@ import net.sf.briar.api.serial.Reader;
 
 class MessageReader implements ObjectReader<Message> {
 
+	private final ObjectReader<Group> groupReader;
+	private final ObjectReader<Author> authorReader;
 	private final KeyParser keyParser;
 	private final Signature signature;
 	private final MessageDigest messageDigest;
 
-	MessageReader(KeyParser keyParser, Signature signature,
-			MessageDigest messageDigest) {
-		this.keyParser = keyParser;
-		this.signature = signature;
-		this.messageDigest = messageDigest;
+	MessageReader(CryptoComponent crypto, ObjectReader<Group> groupReader,
+			ObjectReader<Author> authorReader) {
+		this.groupReader = groupReader;
+		this.authorReader = authorReader;
+		keyParser = crypto.getKeyParser();
+		signature = crypto.getSignature();
+		messageDigest = crypto.getMessageDigest();
 	}
 
 	public Message readObject(Reader r) throws IOException {
@@ -44,49 +49,49 @@ class MessageReader implements ObjectReader<Message> {
 		byte[] b = r.readBytes();
 		if(b.length != UniqueId.LENGTH) throw new FormatException();
 		MessageId parent = new MessageId(b);
-		// Read the group ID
-		r.readUserDefinedTag(Tags.GROUP_ID);
-		b = r.readBytes();
-		if(b.length != UniqueId.LENGTH) throw new FormatException();
-		GroupId group = new GroupId(b);
+		// Read the group
+		r.addObjectReader(Tags.GROUP, groupReader);
+		Group group = r.readUserDefined(Tags.GROUP, Group.class);
+		r.removeObjectReader(Tags.GROUP);
+		// Read the author, if there is one
+		r.addObjectReader(Tags.AUTHOR, authorReader);
+		Author author = null;
+		if(r.hasNull()) r.readNull();
+		else author = r.readUserDefined(Tags.AUTHOR, Author.class);
+		r.removeObjectReader(Tags.AUTHOR);
 		// Read the timestamp
 		long timestamp = r.readInt64();
 		if(timestamp < 0L) throw new FormatException();
-		// Hash the author's nick and public key to get the author ID
-		DigestingConsumer digesting = new DigestingConsumer(messageDigest);
-		messageDigest.reset();
-		r.addConsumer(digesting);
-		r.readString();
-		byte[] encodedKey = r.readBytes();
-		r.removeConsumer(digesting);
-		AuthorId author = new AuthorId(messageDigest.digest());
 		// Skip the message body
 		r.readBytes();
 		// Record the length of the signed data
 		int messageLength = (int) counting.getCount();
-		// Read the signature
-		byte[] sig = r.readBytes();
+		// Read the author's signature, if there is one
+		byte[] authorSig = null;
+		if(author == null) r.readNull();
+		else authorSig = r.readBytes();
+		// That's all, folks
 		r.removeConsumer(counting);
 		r.removeConsumer(copying);
-		// Verify the signature
-		PublicKey publicKey;
-		try {
-			publicKey = keyParser.parsePublicKey(encodedKey);
-		} catch(InvalidKeySpecException e) {
-			throw new FormatException();
-		}
 		byte[] raw = copying.getCopy();
-		try {
-			signature.initVerify(publicKey);
-			signature.update(raw, 0, messageLength);
-			if(!signature.verify(sig)) throw new SignatureException();
-		} catch(GeneralSecurityException e) {
-			throw new FormatException();
+		// Verify the author's signature, if there is one
+		if(author != null) {
+			try {
+				PublicKey publicKey =
+					keyParser.parsePublicKey(author.getPublicKey());
+				signature.initVerify(publicKey);
+				signature.update(raw, 0, messageLength);
+				if(!signature.verify(authorSig)) throw new SignatureException();
+			} catch(GeneralSecurityException e) {
+				throw new FormatException();
+			}
 		}
 		// Hash the message, including the signature, to get the message ID
 		messageDigest.reset();
 		messageDigest.update(raw);
 		MessageId id = new MessageId(messageDigest.digest());
-		return new MessageImpl(id, parent, group, author, timestamp, raw);
+		AuthorId authorId = author == null ? AuthorId.NONE : author.getId();
+		return new MessageImpl(id, parent, group.getId(), authorId, timestamp,
+				raw);
 	}
 }

components/net/sf/briar/protocol/ProtocolModule.java

@@ -1,5 +1,6 @@
 package net.sf.briar.protocol;
 
+import net.sf.briar.api.protocol.AuthorFactory;
 import net.sf.briar.api.protocol.GroupFactory;
 import net.sf.briar.api.protocol.MessageEncoder;
 
@@ -10,6 +11,7 @@ public class ProtocolModule extends AbstractModule {
 	@Override
 	protected void configure() {
 		bind(AckFactory.class).to(AckFactoryImpl.class);
+		bind(AuthorFactory.class).to(AuthorFactoryImpl.class);
 		bind(BatchFactory.class).to(BatchFactoryImpl.class);
 		bind(GroupFactory.class).to(GroupFactoryImpl.class);
 		bind(MessageEncoder.class).to(MessageEncoderImpl.class);