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Sign the message with the group's private key if the group is

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restricted, and check the signature if it should be present.
This commit is contained in:
akwizgran
2011-07-25 21:54:49 +01:00
parent 3f61d0c3df
commit a86ef2142f
4 changed files with 139 additions and 72 deletions
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78
components/net/sf/briar/protocol/MessageEncoderImpl.java
View File

@@ -34,30 +34,31 @@ class MessageEncoderImpl implements MessageEncoder {
}
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);
throws IOException, GeneralSecurityException {
return encodeMessage(parent, group, null, null, null, body);
}
public Message encodeMessage(MessageId parent, Group group,
PrivateKey groupKey, byte[] body) throws IOException,
GeneralSecurityException {
return encodeMessage(parent, group, groupKey, null, null, body);
}
public Message encodeMessage(MessageId parent, Group group, Author author,
PrivateKey privateKey, byte[] body) throws IOException,
PrivateKey authorKey, byte[] body) throws IOException,
GeneralSecurityException {
return encodeMessage(parent, group, null, author, authorKey, body);
}
public Message encodeMessage(MessageId parent, Group group,
PrivateKey groupKey, Author author, PrivateKey authorKey,
byte[] body) throws IOException, GeneralSecurityException {
if((author == null) != (authorKey == null))
throw new IllegalArgumentException();
if((group.getPublicKey() == null) != (groupKey == null))
throw new IllegalArgumentException();
long timestamp = System.currentTimeMillis();
ByteArrayOutputStream out = new ByteArrayOutputStream();
Writer w = writerFactory.createWriter(out);
@@ -65,29 +66,32 @@ class MessageEncoderImpl implements MessageEncoder {
w.writeUserDefinedTag(Tags.MESSAGE);
parent.writeTo(w);
group.writeTo(w);
author.writeTo(w);
if(author == null) w.writeNull();
else author.writeTo(w);
w.writeInt64(timestamp);
w.writeBytes(body);
// Sign the message
byte[] signable = out.toByteArray();
signature.initSign(privateKey);
signature.update(signable);
byte[] sig = signature.sign();
signable = null;
// Write the signature
w.writeBytes(sig);
// Sign the message with the author's private key, if there is one
if(authorKey == null) {
w.writeNull();
} else {
signature.initSign(authorKey);
signature.update(out.toByteArray());
w.writeBytes(signature.sign());
}
// Sign the message with the group's private key, if there is one
if(groupKey == null) {
w.writeNull();
} else {
signature.initSign(groupKey);
signature.update(out.toByteArray());
w.writeBytes(signature.sign());
}
// Hash the message, including the signatures, to get the message ID
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());
// The author ID is the hash of the author object
out.reset();
w = writerFactory.createWriter(out);
author.writeTo(w);
messageDigest.reset();
messageDigest.update(out.toByteArray());
AuthorId authorId = new AuthorId(messageDigest.digest());
AuthorId authorId = author == null ? AuthorId.NONE : author.getId();
return new MessageImpl(id, parent, group.getId(), authorId, timestamp,
raw);
}

33
components/net/sf/briar/protocol/MessageReader.java
View File

@@ -5,7 +5,6 @@ import java.security.GeneralSecurityException;
import java.security.MessageDigest;
import java.security.PublicKey;
import java.security.Signature;
import java.security.SignatureException;
import net.sf.briar.api.crypto.CryptoComponent;
import net.sf.briar.api.crypto.KeyParser;
@@ -64,12 +63,18 @@ class MessageReader implements ObjectReader<Message> {
if(timestamp < 0L) throw new FormatException();
// Skip the message body
r.readBytes();
// Record the length of the signed data
int messageLength = (int) counting.getCount();
// Record the length of the data covered by the author's signature
int signedByAuthor = (int) counting.getCount();
// Read the author's signature, if there is one
byte[] authorSig = null;
if(author == null) r.readNull();
else authorSig = r.readBytes();
// Record the length of the data covered by the group's signature
int signedByGroup = (int) counting.getCount();
// Read the group's signature, if there is one
byte[] groupSig = null;
if(group.getPublicKey() == null) r.readNull();
else groupSig = r.readBytes();
// That's all, folks
r.removeConsumer(counting);
r.removeConsumer(copying);
@@ -77,16 +82,26 @@ class MessageReader implements ObjectReader<Message> {
// 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();
PublicKey k = keyParser.parsePublicKey(author.getPublicKey());
signature.initVerify(k);
signature.update(raw, 0, signedByAuthor);
if(!signature.verify(authorSig)) throw new FormatException();
} catch(GeneralSecurityException e) {
throw new FormatException();
}
}
// Hash the message, including the signature, to get the message ID
// Verify the group's signature, if there is one
if(group.getPublicKey() != null) {
try {
PublicKey k = keyParser.parsePublicKey(group.getPublicKey());
signature.initVerify(k);
signature.update(raw, 0, signedByGroup);
if(!signature.verify(groupSig)) throw new FormatException();
} catch(GeneralSecurityException e) {
throw new FormatException();
}
}
// Hash the message, including the signatures, to get the message ID
messageDigest.reset();
messageDigest.update(raw);
MessageId id = new MessageId(messageDigest.digest());