private byte[] decrypt(SessionRecord sessionRecord, WhisperMessage ciphertext)
{
lock (SESSION_LOCK)
{
IEnumerator<SessionState> previousStates = sessionRecord.getPreviousSessionStates().GetEnumerator(); //iterator
LinkedList<Exception> exceptions = new LinkedList<Exception>();
try
{
SessionState sessionState = new SessionState(sessionRecord.getSessionState());
byte[] plaintext = decrypt(sessionState, ciphertext);
sessionRecord.setState(sessionState);
return plaintext;
}
catch (InvalidMessageException e)
{
exceptions.AddLast(e); // add (java default behavioir addlast)
}
while (previousStates.MoveNext()) //hasNext();
{
try
{
SessionState promotedState = new SessionState(previousStates.Current); //.next()
byte[] plaintext = decrypt(promotedState, ciphertext);
sessionRecord.getPreviousSessionStates().Remove(previousStates.Current); // previousStates.remove()
sessionRecord.promoteState(promotedState);
return plaintext;
}
catch (InvalidMessageException e)
{
exceptions.AddLast(e);
}
}
throw new InvalidMessageException("No valid sessions.", exceptions);
}
}
public void StoreSession(AxolotlAddress address, SessionRecord record)
{
sessionStore.StoreSession(address, record);
}
public void StoreSession(AxolotlAddress address, SessionRecord record)
{
sessions[address] = record.serialize();
}
private May<uint> processV2(SessionRecord sessionRecord, PreKeyWhisperMessage message)
{
if (!message.getPreKeyId().HasValue)
{
throw new InvalidKeyIdException("V2 message requires one time prekey id!");
}
if (!preKeyStore.ContainsPreKey(message.getPreKeyId().ForceGetValue()) &&
sessionStore.ContainsSession(remoteAddress))
{
//Log.w(TAG, "We've already processed the prekey part of this V2 session, letting bundled message fall through...");
return May<uint>.NoValue; //May.absent();
}
ECKeyPair ourPreKey = preKeyStore.LoadPreKey(message.getPreKeyId().ForceGetValue()).getKeyPair();
BobAxolotlParameters.Builder parameters = BobAxolotlParameters.newBuilder();
parameters.setOurIdentityKey(identityKeyStore.GetIdentityKeyPair())
.setOurSignedPreKey(ourPreKey)
.setOurRatchetKey(ourPreKey)
.setOurOneTimePreKey(May<ECKeyPair>.NoValue) //absent
.setTheirIdentityKey(message.getIdentityKey())
.setTheirBaseKey(message.getBaseKey());
if (!sessionRecord.isFresh()) sessionRecord.archiveCurrentState();
RatchetingSession.initializeSession(sessionRecord.getSessionState(), message.getMessageVersion(), parameters.create());
sessionRecord.getSessionState().setLocalRegistrationId(identityKeyStore.GetLocalRegistrationId());
sessionRecord.getSessionState().setRemoteRegistrationId(message.getRegistrationId());
sessionRecord.getSessionState().setAliceBaseKey(message.getBaseKey().serialize());
if (message.getPreKeyId().ForceGetValue() != Medium.MAX_VALUE)
{
return message.getPreKeyId();
}
else
{
return May<uint>.NoValue; // May.absent();
}
}
private May<uint> processV3(SessionRecord sessionRecord, PreKeyWhisperMessage message)
{
if (sessionRecord.hasSessionState(message.getMessageVersion(), message.getBaseKey().serialize()))
{
//Log.w(TAG, "We've already setup a session for this V3 message, letting bundled message fall through...");
return May<uint>.NoValue;
}
ECKeyPair ourSignedPreKey = signedPreKeyStore.LoadSignedPreKey(message.getSignedPreKeyId()).getKeyPair();
BobAxolotlParameters.Builder parameters = BobAxolotlParameters.newBuilder();
parameters.setTheirBaseKey(message.getBaseKey())
.setTheirIdentityKey(message.getIdentityKey())
.setOurIdentityKey(identityKeyStore.GetIdentityKeyPair())
.setOurSignedPreKey(ourSignedPreKey)
.setOurRatchetKey(ourSignedPreKey);
if (message.getPreKeyId().HasValue)
{
parameters.setOurOneTimePreKey(new May<ECKeyPair>(preKeyStore.LoadPreKey(message.getPreKeyId().ForceGetValue()).getKeyPair()));
}
else
{
parameters.setOurOneTimePreKey(May<ECKeyPair>.NoValue);
}
if (!sessionRecord.isFresh()) sessionRecord.archiveCurrentState();
RatchetingSession.initializeSession(sessionRecord.getSessionState(), message.getMessageVersion(), parameters.create());
sessionRecord.getSessionState().setLocalRegistrationId(identityKeyStore.GetLocalRegistrationId());
sessionRecord.getSessionState().setRemoteRegistrationId(message.getRegistrationId());
sessionRecord.getSessionState().setAliceBaseKey(message.getBaseKey().serialize());
if (message.getPreKeyId().HasValue && message.getPreKeyId().ForceGetValue() != Medium.MAX_VALUE)
{
return message.getPreKeyId();
}
else
{
return May<uint>.NoValue;
}
}
/**
* Build a new session from a received {@link org.whispersystems.libaxolotl.protocol.PreKeyWhisperMessage}.
*
* After a session is constructed in this way, the embedded {@link org.whispersystems.libaxolotl.protocol.WhisperMessage}
* can be decrypted.
*
* @param message The received {@link org.whispersystems.libaxolotl.protocol.PreKeyWhisperMessage}.
* @throws org.whispersystems.libaxolotl.InvalidKeyIdException when there is no local
* {@link org.whispersystems.libaxolotl.state.PreKeyRecord}
* that corresponds to the PreKey ID in
* the message.
* @throws org.whispersystems.libaxolotl.InvalidKeyException when the message is formatted incorrectly.
* @throws org.whispersystems.libaxolotl.UntrustedIdentityException when the {@link IdentityKey} of the sender is untrusted.
*/
/*package*/
internal May<uint> process(SessionRecord sessionRecord, PreKeyWhisperMessage message)
{
uint messageVersion = message.getMessageVersion();
IdentityKey theirIdentityKey = message.getIdentityKey();
May<uint> unsignedPreKeyId;
if (!identityKeyStore.IsTrustedIdentity(remoteAddress.getName(), theirIdentityKey))
{
throw new UntrustedIdentityException(remoteAddress.getName(), theirIdentityKey);
}
switch (messageVersion)
{
case 2: unsignedPreKeyId = processV2(sessionRecord, message); break;
case 3: unsignedPreKeyId = processV3(sessionRecord, message); break;
default: throw new Exception("Unknown version: " + messageVersion);
}
identityKeyStore.SaveIdentity(remoteAddress.getName(), theirIdentityKey);
return unsignedPreKeyId;
}
public void StoreSession(AxolotlAddress address, SessionRecord record)
{
DeleteSession(address); // TODO: sqlite-net combined private keys for insertOrReplace
var session = new Session() { DeviceId = address.DeviceId, Name = address.Name, Record = record.serialize() };
conn.InsertOrReplace(session);
return;
}
public void storeSession(AxolotlAddress address, SessionRecord record)
{
if (sessions.ContainsKey(address)) //mimic HashMap update behaviour
{
sessions.Remove(address);
}
sessions.Add(address, record.serialize()); // put
}