/**
* Build a new session from a {@link org.whispersystems.libaxolotl.state.PreKeyBundle} retrieved from
* a server.
*
* @param preKey A PreKey for the destination recipient, retrieved from a server.
* @throws InvalidKeyException when the {@link org.whispersystems.libaxolotl.state.PreKeyBundle} is
* badly formatted.
* @throws org.whispersystems.libaxolotl.UntrustedIdentityException when the sender's
* {@link IdentityKey} is not
* trusted.
*/
public void process(PreKeyBundle preKey)
{
lock (SessionCipher.SESSION_LOCK)
{
if (!identityKeyStore.IsTrustedIdentity(remoteAddress.getName(), preKey.getIdentityKey()))
{
throw new UntrustedIdentityException(remoteAddress.getName(), preKey.getIdentityKey());
}
if (preKey.getSignedPreKey() != null &&
!Curve.verifySignature(preKey.getIdentityKey().getPublicKey(),
preKey.getSignedPreKey().serialize(),
preKey.getSignedPreKeySignature()))
{
throw new InvalidKeyException("Invalid signature on device key!");
}
if (preKey.getSignedPreKey() == null && preKey.getPreKey() == null)
{
throw new InvalidKeyException("Both signed and unsigned prekeys are absent!");
}
bool supportsV3 = preKey.getSignedPreKey() != null;
SessionRecord sessionRecord = sessionStore.LoadSession(remoteAddress);
ECKeyPair ourBaseKey = Curve.generateKeyPair();
ECPublicKey theirSignedPreKey = supportsV3 ? preKey.getSignedPreKey() : preKey.getPreKey();
ECPublicKey test = preKey.getPreKey(); // TODO: cleanup
May <ECPublicKey> theirOneTimePreKey = (test == null) ? May <ECPublicKey> .NoValue : new May <ECPublicKey>(test);
May <uint> theirOneTimePreKeyId = theirOneTimePreKey.HasValue ? new May <uint>(preKey.getPreKeyId()) :
May <uint> .NoValue;
AliceAxolotlParameters.Builder parameters = AliceAxolotlParameters.newBuilder();
parameters.setOurBaseKey(ourBaseKey)
.setOurIdentityKey(identityKeyStore.GetIdentityKeyPair())
.setTheirIdentityKey(preKey.getIdentityKey())
.setTheirSignedPreKey(theirSignedPreKey)
.setTheirRatchetKey(theirSignedPreKey)
.setTheirOneTimePreKey(supportsV3 ? theirOneTimePreKey : May <ECPublicKey> .NoValue);
if (!sessionRecord.isFresh())
{
sessionRecord.archiveCurrentState();
}
RatchetingSession.initializeSession(sessionRecord.getSessionState(),
supportsV3 ? (uint)3 : 2,
parameters.create());
sessionRecord.getSessionState().setUnacknowledgedPreKeyMessage(theirOneTimePreKeyId, preKey.getSignedPreKeyId(), ourBaseKey.getPublicKey());
sessionRecord.getSessionState().setLocalRegistrationId(identityKeyStore.GetLocalRegistrationId());
sessionRecord.getSessionState().setRemoteRegistrationId(preKey.getRegistrationId());
sessionRecord.getSessionState().setAliceBaseKey(ourBaseKey.getPublicKey().serialize());
sessionStore.StoreSession(remoteAddress, sessionRecord);
identityKeyStore.SaveIdentity(remoteAddress.getName(), preKey.getIdentityKey());
}
}
private KeyExchangeMessage processInitiate(KeyExchangeMessage message)
{
uint flags = KeyExchangeMessage.RESPONSE_FLAG;
SessionRecord sessionRecord = sessionStore.LoadSession(remoteAddress);
if (message.getVersion() >= 3 &&
!Curve.verifySignature(message.getIdentityKey().getPublicKey(),
message.getBaseKey().serialize(),
message.getBaseKeySignature()))
{
throw new InvalidKeyException("Bad signature!");
}
SymmetricAxolotlParameters.Builder builder = SymmetricAxolotlParameters.newBuilder();
if (!sessionRecord.getSessionState().hasPendingKeyExchange())
{
builder.setOurIdentityKey(identityKeyStore.GetIdentityKeyPair())
.setOurBaseKey(Curve.generateKeyPair())
.setOurRatchetKey(Curve.generateKeyPair());
}
else
{
builder.setOurIdentityKey(sessionRecord.getSessionState().getPendingKeyExchangeIdentityKey())
.setOurBaseKey(sessionRecord.getSessionState().getPendingKeyExchangeBaseKey())
.setOurRatchetKey(sessionRecord.getSessionState().getPendingKeyExchangeRatchetKey());
flags |= KeyExchangeMessage.SIMULTAENOUS_INITIATE_FLAG;
}
builder.setTheirBaseKey(message.getBaseKey())
.setTheirRatchetKey(message.getRatchetKey())
.setTheirIdentityKey(message.getIdentityKey());
SymmetricAxolotlParameters parameters = builder.create();
if (!sessionRecord.isFresh())
{
sessionRecord.archiveCurrentState();
}
RatchetingSession.initializeSession(sessionRecord.getSessionState(),
Math.Min(message.getMaxVersion(), CiphertextMessage.CURRENT_VERSION),
parameters);
sessionStore.StoreSession(remoteAddress, sessionRecord);
identityKeyStore.SaveIdentity(remoteAddress.getName(), message.getIdentityKey());
byte[] baseKeySignature = Curve.calculateSignature(parameters.getOurIdentityKey().getPrivateKey(),
parameters.getOurBaseKey().getPublicKey().serialize());
return(new KeyExchangeMessage(sessionRecord.getSessionState().getSessionVersion(),
message.getSequence(), flags,
parameters.getOurBaseKey().getPublicKey(),
baseKeySignature, parameters.getOurRatchetKey().getPublicKey(),
parameters.getOurIdentityKey().getPublicKey()));
}
private void processResponse(KeyExchangeMessage message)
{
SessionRecord sessionRecord = sessionStore.LoadSession(remoteAddress);
SessionState sessionState = sessionRecord.getSessionState();
bool hasPendingKeyExchange = sessionState.hasPendingKeyExchange();
bool isSimultaneousInitiateResponse = message.isResponseForSimultaneousInitiate();
if (!hasPendingKeyExchange || sessionState.getPendingKeyExchangeSequence() != message.getSequence())
{
//Log.w(TAG, "No matching sequence for response. Is simultaneous initiate response: " + isSimultaneousInitiateResponse);
if (!isSimultaneousInitiateResponse)
{
throw new StaleKeyExchangeException();
}
else
{
return;
}
}
SymmetricAxolotlParameters.Builder parameters = SymmetricAxolotlParameters.newBuilder();
parameters.setOurBaseKey(sessionRecord.getSessionState().getPendingKeyExchangeBaseKey())
.setOurRatchetKey(sessionRecord.getSessionState().getPendingKeyExchangeRatchetKey())
.setOurIdentityKey(sessionRecord.getSessionState().getPendingKeyExchangeIdentityKey())
.setTheirBaseKey(message.getBaseKey())
.setTheirRatchetKey(message.getRatchetKey())
.setTheirIdentityKey(message.getIdentityKey());
if (!sessionRecord.isFresh())
{
sessionRecord.archiveCurrentState();
}
RatchetingSession.initializeSession(sessionRecord.getSessionState(),
Math.Min(message.getMaxVersion(), CiphertextMessage.CURRENT_VERSION),
parameters.create());
if (sessionRecord.getSessionState().getSessionVersion() >= 3 &&
!Curve.verifySignature(message.getIdentityKey().getPublicKey(),
message.getBaseKey().serialize(),
message.getBaseKeySignature()))
{
throw new InvalidKeyException("Base key signature doesn't match!");
}
sessionStore.StoreSession(remoteAddress, sessionRecord);
identityKeyStore.SaveIdentity(remoteAddress.getName(), message.getIdentityKey());
}
private May <uint> processV3(SessionRecord sessionRecord, PreKeySignalMessage message)
{
if (sessionRecord.hasSessionState(message.getMessageVersion(), message.getBaseKey().serialize()))
{
Debug.WriteLine("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();
BobSignalProtocolParameters.Builder parameters = BobSignalProtocolParameters.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(), 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);
}
}
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();
}
}