public override Message ProcessIncoming(MessageHeader header, byte[] chiper, ref byte[] plaintext)
{
var messageDirection = Message.GetMessageDirection(header.ID);
// Message instance that we will return to the caller.
var message = MessageFactory.Create(header.ID);
// Unencrypted byte array.
plaintext = null;
lock (_lock)
{
// Handshaking.
if (_state <= 1)
{
// Handshakes are sent unencrypted.
// First message by both ends is always sent unencrypted.
plaintext = (byte[])chiper.Clone();
// Use the first message direction to configure the processor.
if (_state == 0)
{
_clientCrypto = new Crypto8(GetOppositeDirection(messageDirection), _keyPair);
}
if (_state == 1)
{
_serverCrypto = new Crypto8(GetOppositeDirection(messageDirection), Crypto8.GenerateKeyPair());
}
}
if (_state == 4)
{
_clientCrypto.UpdateNonce((byte[])_serverNonce.Clone(), UpdateNonceType.Encrypt);
_clientCrypto.UpdateNonce((byte[])_clientNonce.Clone(), UpdateNonceType.Decrypt);
_clientCrypto.UpdateSharedKey(_serverCrypto.SharedKey);
}
// _state == 1 means we are the server.
// Usually processing 10101 - LoginRequestMessage.
if (_state == 2)
{
_serverCrypto.UpdateSharedKey(Crypto8.SupercellPublicKey);
// -> Pre-Encryption.
// Copies the public key appended to the beginning of the message.
var publicKey = new byte[CoCKeyPair.KeyLength];
Buffer.BlockCopy(chiper, 0, publicKey, 0, CoCKeyPair.KeyLength);
Debug.WriteLine($"Public-Key from {header.ID}: {ToHexString(publicKey)}");
// Copies the remaining bytes into the plaintext buffer
var plaintextLen = header.Length - CoCKeyPair.KeyLength;
plaintext = new byte[plaintextLen];
Buffer.BlockCopy(chiper, CoCKeyPair.KeyLength, plaintext, 0, plaintextLen);
// Crypto8 will take publicKey & _keyPair.PublicKey and generate a blake2b nonce
_clientCrypto.UpdateSharedKey(publicKey);
// Then use _keyPair.PrivateKey, publicKey and nonce to decrypt.
_clientCrypto.Decrypt(ref plaintext);
// -> Post-Encryption.
_sessionKey = new byte[CoCKeyPair.NonceLength];
_clientNonce = new byte[CoCKeyPair.NonceLength];
// Copy the SessionKey and the ClientNonce.
Buffer.BlockCopy(plaintext, 0, _sessionKey, 0, CoCKeyPair.NonceLength);
Buffer.BlockCopy(plaintext, CoCKeyPair.NonceLength, _clientNonce, 0, CoCKeyPair.NonceLength);
Debug.WriteLine($"Session-key from {header.ID}: {ToHexString(_sessionKey)}");
Debug.WriteLine($"Client-nonce from {header.ID}: {ToHexString(_clientNonce)}");
var actualMessage = new byte[plaintext.Length - (CoCKeyPair.NonceLength * 2)];
Buffer.BlockCopy(plaintext, CoCKeyPair.NonceLength * 2, actualMessage, 0, actualMessage.Length);
plaintext = actualMessage;
}
else if (_state == 3)
{
_clientCrypto.UpdateNonce(_clientNonce, UpdateNonceType.Blake);
_serverCrypto.UpdateNonce(_clientNonce, UpdateNonceType.Blake);
_serverCrypto.Decrypt(ref chiper);
// Post-Encryption
// Copies the public key appended to the beginning of the message.
_serverNonce = new byte[CoCKeyPair.NonceLength];
Buffer.BlockCopy(chiper, 0, _serverNonce, 0, CoCKeyPair.NonceLength);
var publicKey = new byte[CoCKeyPair.KeyLength];
Buffer.BlockCopy(chiper, CoCKeyPair.NonceLength, publicKey, 0, CoCKeyPair.KeyLength);
_serverCrypto.UpdateNonce((byte[])_serverNonce.Clone(), UpdateNonceType.Decrypt);
_serverCrypto.UpdateNonce((byte[])_clientNonce.Clone(), UpdateNonceType.Encrypt);
_serverCrypto.UpdateSharedKey(publicKey);
Debug.WriteLine($"Server-Nonce from {header.ID}: {ToHexString(_serverNonce)}");
Debug.WriteLine($"New Public-Key from {header.ID}: {ToHexString(publicKey)}");
// Copies the remaining bytes into the plaintext buffer.
var plaintextLen = chiper.Length - CoCKeyPair.KeyLength - CoCKeyPair.NonceLength;
plaintext = new byte[plaintextLen];
Buffer.BlockCopy(chiper, CoCKeyPair.KeyLength + CoCKeyPair.NonceLength, plaintext, 0, plaintextLen);
}
else if (_state > 3)
{
if (messageDirection == MessageDirection.Client)
{
_serverCrypto.Decrypt(ref chiper);
}
if (messageDirection == MessageDirection.Server)
{
_clientCrypto.Decrypt(ref chiper);
}
plaintext = chiper;
}
_state++;
}
try
{
using (var reader = new MessageReader(new MemoryStream(plaintext)))
message.ReadMessage(reader);
}
catch (Exception ex)
{
Console.WriteLine("Ex: " + ex);
}
return(message);
}
private byte[] ProcessIncomingData(MessageDirection direction, MessageHeader header, BufferStream stream)
{
var plaintext = (byte[])null;
var chiper = new byte[header.Length];
stream.Read(chiper, 0, header.Length);
// Handshaking.
if (_incommingState == 0)
{
// Handshakes are sent unencrypted.
// First message by both ends is always sent unencrypted.
plaintext = new byte[header.Length];
Buffer.BlockCopy(chiper, 0, plaintext, 0, header.Length);
// Use the first message direction to configure the processor.
// If message is coming in, then the going out is opposite direction.
_direction = GetOppositeDirection(direction);
// If we're the client then we must have a serverkey.
if (_direction == MessageDirection.Server && _serverKey == null)
{
throw new InvalidOperationException("Public key of server was not specified.");
}
if (_crypto == null)
{
_crypto = new Crypto8(_direction, _keyPair);
}
Debug.WriteLine($"Initialized Crypto8 {_direction} with private-key: {ToHexString(_keyPair.PrivateKey)}, public-key {_keyPair.PublicKey}");
}
// If somehow the incoming message to process comes from the same direction.
// The MessageProcessor can only process message going in One Direction. ;]
if (GetOppositeDirection(direction) != _direction)
{
throw new InvalidOperationException("Tried to process an incoming data from a message coming from the same direction."); // -> Protocol Exception?
}
// _incomingState == 2 means we are the server.
// Usually processing 10101 - LoginRequestMessage.
if (_incommingState == 2)
{
// -> Post-Encryption.
// Copies the public key appended to the beginning of the message
// sent of message 20100.
var publicKey = new byte[KeyPair.KeyLength];
Buffer.BlockCopy(chiper, 0, publicKey, 0, KeyPair.KeyLength);
Debug.WriteLine($"Public-Key from {header.Id}: {ToHexString(publicKey)}");
// Copies the remaining bytes into the postChiper buffer which
// will be decrypted by _crypto.
var tmpPlaintextLen = header.Length - KeyPair.KeyLength;
var tmpPlaintext = new byte[tmpPlaintextLen];
Buffer.BlockCopy(chiper, KeyPair.KeyLength, tmpPlaintext, 0, tmpPlaintextLen);
// Crypto8 will take the client's publicKey & _keyPair.PublicKey and generate a blake2b nonce
_crypto.UpdateSharedKey(publicKey);
// Then use _keyPair.PrivateKey, publicKey and nonce to decrypt.
_crypto.Decrypt(ref tmpPlaintext);
// -> Pre-Encryption.
var sessionKey = new byte[KeyPair.NonceLength];
var remoteNonce = new byte[KeyPair.NonceLength];
// Copy the SessionKey and the ClientNonce.
Buffer.BlockCopy(tmpPlaintext, 0, sessionKey, 0, KeyPair.NonceLength);
Buffer.BlockCopy(tmpPlaintext, KeyPair.NonceLength, remoteNonce, 0, KeyPair.NonceLength);
Debug.WriteLine($"Session-key from {header.Id}: {ToHexString(sessionKey)}");
Debug.WriteLine($"Client-nonce from {header.Id}: {ToHexString(remoteNonce)}");
// Copies the plaintext without the session key and the remote/client nonce.
var plaintextLen = tmpPlaintext.Length - (KeyPair.NonceLength * 2);
plaintext = new byte[plaintextLen];
Buffer.BlockCopy(tmpPlaintext, KeyPair.NonceLength * 2, plaintext, 0, plaintextLen);
_crypto.UpdateNonce(remoteNonce, UpdateNonceType.Decrypt);
_crypto.UpdateNonce(remoteNonce, UpdateNonceType.Blake);
_sessionKey = sessionKey;
_remoteNonce = remoteNonce;
_nstate = States.Authentifying;
}
// _incomingState == 3 means we are the client.
// Usually processing 20104 - LoginSuccessMessage.
else if (_incommingState == 3)
{
// -> Might want to generate random nonce here for the
// client nonce.
Debug.Assert(_localNonce != null);
var tmpPlaintext = (byte[])chiper.Clone();
// _crypto will use this nonce after the second key is passed to it
// using _crypto.UpdateSharedKey.
var localNonce = _localNonce;
_crypto.UpdateNonce(localNonce, UpdateNonceType.Encrypt);
_crypto.UpdateNonce(localNonce, UpdateNonceType.Blake);
_crypto.Decrypt(ref tmpPlaintext);
// -> Post-Encryption
var remoteNonce = new byte[KeyPair.NonceLength];
var key = new byte[KeyPair.KeyLength];
// Copies the ServerNonce and the new second secret key.
Buffer.BlockCopy(tmpPlaintext, 0, remoteNonce, 0, KeyPair.NonceLength);
Buffer.BlockCopy(tmpPlaintext, KeyPair.NonceLength, key, 0, KeyPair.KeyLength);
Debug.WriteLine($"Shared-key from {header.Id}: {ToHexString(key)}");
Debug.WriteLine($"Server-nonce from {header.Id}: {ToHexString(remoteNonce)}");
// Copies the plaintext without the server nonce and the new second secret key.
var plaintextLen = tmpPlaintext.Length - KeyPair.NonceLength - KeyPair.KeyLength;
plaintext = new byte[plaintextLen];
Buffer.BlockCopy(tmpPlaintext, KeyPair.NonceLength + KeyPair.KeyLength, plaintext, 0, plaintextLen);
_crypto.UpdateNonce(remoteNonce, UpdateNonceType.Decrypt);
_crypto.UpdateSharedKey(key);
_remoteNonce = remoteNonce;
_key = key;
_nstate = States.Authentified;
}
// Messages after the previous states are processed the same way.
else if (_incommingState > (int)_direction)
{
_nstate = States.Completed;
plaintext = (byte[])chiper.Clone();
_crypto.Decrypt(ref plaintext);
}
return(plaintext);
}
