private MessageKeys GetOrCreateMessageKeys(SessionState sessionState,
IEcPublicKey theirEphemeral,
ChainKey chainKey, uint counter)
{
if (chainKey.GetIndex() > counter)
{
if (sessionState.HasMessageKeys(theirEphemeral, counter))
{
return(sessionState.RemoveMessageKeys(theirEphemeral, counter));
}
else
{
throw new DuplicateMessageException($"Received message with old counter: {chainKey.GetIndex()} , {counter}");
}
}
//Avoiding a uint overflow
uint chainKeyIndex = chainKey.GetIndex();
if ((counter > chainKeyIndex) && (counter - chainKeyIndex > 2000))
{
throw new InvalidMessageException("Over 2000 messages into the future!");
}
while (chainKey.GetIndex() < counter)
{
MessageKeys messageKeys = chainKey.GetMessageKeys();
sessionState.SetMessageKeys(theirEphemeral, messageKeys);
chainKey = chainKey.GetNextChainKey();
}
sessionState.SetReceiverChainKey(theirEphemeral, chainKey.GetNextChainKey());
return(chainKey.GetMessageKeys());
}
public void TestChainKeyDerivationV3()
{
byte[] seed =
{
0x8a, 0xb7, 0x2d, 0x6f, 0x4c,
0xc5, 0xac, 0x0d, 0x38, 0x7e,
0xaf, 0x46, 0x33, 0x78, 0xdd,
0xb2, 0x8e, 0xdd, 0x07, 0x38,
0x5b, 0x1c, 0xb0, 0x12, 0x50,
0xc7, 0x15, 0x98, 0x2e, 0x7a,
0xd4, 0x8f
};
byte[] messageKey =
{
/* 0x02*/
0xbf, 0x51, 0xe9, 0xd7,
0x5e, 0x0e, 0x31, 0x03, 0x10,
0x51, 0xf8, 0x2a, 0x24, 0x91,
0xff, 0xc0, 0x84, 0xfa, 0x29,
0x8b, 0x77, 0x93, 0xbd, 0x9d,
0xb6, 0x20, 0x05, 0x6f, 0xeb,
0xf4, 0x52, 0x17
};
byte[] macKey =
{
0xc6, 0xc7, 0x7d, 0x6a, 0x73,
0xa3, 0x54, 0x33, 0x7a, 0x56,
0x43, 0x5e, 0x34, 0x60, 0x7d,
0xfe, 0x48, 0xe3, 0xac, 0xe1,
0x4e, 0x77, 0x31, 0x4d, 0xc6,
0xab, 0xc1, 0x72, 0xe7, 0xa7,
0x03, 0x0b
};
byte[] nextChainKey =
{
0x28, 0xe8, 0xf8, 0xfe, 0xe5,
0x4b, 0x80, 0x1e, 0xef, 0x7c,
0x5c, 0xfb, 0x2f, 0x17, 0xf3,
0x2c, 0x7b, 0x33, 0x44, 0x85,
0xbb, 0xb7, 0x0f, 0xac, 0x6e,
0xc1, 0x03, 0x42, 0xa2, 0x46,
0xd1, 0x5d
};
ChainKey chainKey = new ChainKey(Hkdf.CreateFor(3), seed, 0);
CollectionAssert.AreEqual(seed, chainKey.GetKey());
CollectionAssert.AreEqual(messageKey, chainKey.GetMessageKeys().GetCipherKey());
CollectionAssert.AreEqual(macKey, chainKey.GetMessageKeys().GetMacKey());
CollectionAssert.AreEqual(nextChainKey, chainKey.GetNextChainKey().GetKey());
Assert.AreEqual <uint>(0, chainKey.GetIndex());
Assert.AreEqual <uint>(0, chainKey.GetMessageKeys().GetCounter());
Assert.AreEqual <uint>(1, chainKey.GetNextChainKey().GetIndex());
Assert.AreEqual <uint>(1, chainKey.GetNextChainKey().GetMessageKeys().GetCounter());
}
public void TestChainKeyDerivationV2()
{
byte[] seed =
{
0x8a, 0xb7, 0x2d, 0x6f, 0x4c,
0xc5, 0xac, 0x0d, 0x38, 0x7e,
0xaf, 0x46, 0x33, 0x78, 0xdd,
0xb2, 0x8e, 0xdd, 0x07, 0x38,
0x5b, 0x1c, 0xb0, 0x12, 0x50,
0xc7, 0x15, 0x98, 0x2e, 0x7a,
0xd4, 0x8f
};
byte[] messageKey =
{
0x02, 0xa9, 0xaa, 0x6c, 0x7d,
0xbd, 0x64, 0xf9, 0xd3, 0xaa,
0x92, 0xf9, 0x2a, 0x27, 0x7b,
0xf5, 0x46, 0x09, 0xda, 0xdf,
0x0b, 0x00, 0x82, 0x8a, 0xcf,
0xc6, 0x1e, 0x3c, 0x72, 0x4b,
0x84, 0xa7
};
byte[] macKey =
{
0xbf, 0xbe, 0x5e, 0xfb, 0x60,
0x30, 0x30, 0x52, 0x67, 0x42,
0xe3, 0xee, 0x89, 0xc7, 0x02,
0x4e, 0x88, 0x4e, 0x44, 0x0f,
0x1f, 0xf3, 0x76, 0xbb, 0x23,
0x17, 0xb2, 0xd6, 0x4d, 0xeb,
0x7c, 0x83
};
byte[] nextChainKey =
{
0x28, 0xe8, 0xf8, 0xfe, 0xe5,
0x4b, 0x80, 0x1e, 0xef, 0x7c,
0x5c, 0xfb, 0x2f, 0x17, 0xf3,
0x2c, 0x7b, 0x33, 0x44, 0x85,
0xbb, 0xb7, 0x0f, 0xac, 0x6e,
0xc1, 0x03, 0x42, 0xa2, 0x46,
0xd1, 0x5d
};
ChainKey chainKey = new ChainKey(Hkdf.CreateFor(2), seed, 0);
Assert.AreEqual(seed, chainKey.GetKey());
CollectionAssert.AreEqual(messageKey, chainKey.GetMessageKeys().GetCipherKey());
CollectionAssert.AreEqual(macKey, chainKey.GetMessageKeys().GetMacKey());
CollectionAssert.AreEqual(nextChainKey, chainKey.GetNextChainKey().GetKey());
Assert.AreEqual <uint>(0, chainKey.GetIndex());
Assert.AreEqual <uint>(0, chainKey.GetMessageKeys().GetCounter());
Assert.AreEqual <uint>(1, chainKey.GetNextChainKey().GetIndex());
Assert.AreEqual <uint>(1, chainKey.GetNextChainKey().GetMessageKeys().GetCounter());
}
/**
* Encrypt a message.
*
* @param paddedMessage The plaintext message bytes, optionally padded to a constant multiple.
* @return A ciphertext message encrypted to the recipient+device tuple.
*/
public CiphertextMessage Encrypt(byte[] paddedMessage)
{
lock (SessionLock)
{
SessionRecord sessionRecord = _sessionStore.LoadSession(_remoteAddress);
SessionState sessionState = sessionRecord.GetSessionState();
ChainKey chainKey = sessionState.GetSenderChainKey();
MessageKeys messageKeys = chainKey.GetMessageKeys();
IEcPublicKey senderEphemeral = sessionState.GetSenderRatchetKey();
uint previousCounter = sessionState.GetPreviousCounter();
uint sessionVersion = sessionState.GetSessionVersion();
byte[] ciphertextBody = GetCiphertext(sessionVersion, messageKeys, paddedMessage);
CiphertextMessage ciphertextMessage = new SignalMessage(sessionVersion, messageKeys.GetMacKey(),
senderEphemeral, chainKey.GetIndex(),
previousCounter, ciphertextBody,
sessionState.GetLocalIdentityKey(),
sessionState.GetRemoteIdentityKey());
if (sessionState.HasUnacknowledgedPreKeyMessage())
{
SessionState.UnacknowledgedPreKeyMessageItems items = sessionState.GetUnacknowledgedPreKeyMessageItems();
uint localRegistrationId = sessionState.GetLocalRegistrationId();
ciphertextMessage = new PreKeySignalMessage(sessionVersion, localRegistrationId, items.GetPreKeyId(),
items.GetSignedPreKeyId(), items.GetBaseKey(),
sessionState.GetLocalIdentityKey(),
(SignalMessage)ciphertextMessage);
}
sessionState.SetSenderChainKey(chainKey.GetNextChainKey());
_sessionStore.StoreSession(_remoteAddress, sessionRecord);
return(ciphertextMessage);
}
}