/// <summary>
/// Initializes a new instance of the <see cref="Session"/> class.
/// </summary>
protected Session()
{
_id = Crypto8.GenerateNonce();
#if DEBUG
_ident = InternalUtils.BytesToString(_id);
#endif
}
private byte[] ProcessOutgoingData(MessageDirection direction, byte[] plaintext)
{
var chiper = (byte[])null;
// Handshaking
if (_outgoingState == 0)
{
chiper = (byte[])plaintext.Clone();
_direction = direction;
if (_crypto == null)
{
_crypto = new Crypto8(direction, _keyPair);
}
}
if (direction != _direction)
{
throw new InvalidOperationException("Tried to process an outgoing message coming from a different direction."); // -> Protocol Exception?
}
// _outgoingState == 2 means we're the server.
// Usually processing 20104 - LoginSuccessMessage.
if (_outgoingState == 2)
{
Debug.Assert(_remoteNonce != null);
Debug.Assert(_localNonce == null);
var key = Crypto8.GenerateKeyPair();
var localNonce = Crypto8.GenerateNonce();
var remoteNonce = _remoteNonce;
var tmpChiper = new byte[plaintext.Length + KeyPair.NonceLength + KeyPair.KeyLength];
Buffer.BlockCopy(localNonce, 0, tmpChiper, 0, KeyPair.NonceLength);
Buffer.BlockCopy(key.PublicKey, 0, tmpChiper, KeyPair.NonceLength, KeyPair.KeyLength);
Buffer.BlockCopy(plaintext, 0, tmpChiper, KeyPair.NonceLength + KeyPair.KeyLength, plaintext.Length);
_crypto.Encrypt(ref tmpChiper);
Debug.WriteLine($"Server-nonce: {ToHexString(localNonce)}");
Debug.WriteLine($"Shared-key: {ToHexString(key.PublicKey)}");
_crypto.UpdateNonce(localNonce, UpdateNonceType.Encrypt);
_crypto.UpdateSharedKey(key.PublicKey);
_localNonce = localNonce;
chiper = tmpChiper;
//_key = key;
}
// _outgoingState == 3 means we're the client.
// Usually processing 10101 - LoginRequestMessage.
else if (_outgoingState == 3)
{
var serverKey = _serverKey;
var sessionKey = _sessionKey;
Debug.Assert(serverKey != null, "Server key was null.");
Debug.Assert(sessionKey != null, "Session key was null.");
// Generate a ClientNonce.
var localNonce = Crypto8.GenerateNonce();
Debug.WriteLine($"Generated ClientNonce: {ToHexString(localNonce)}");
// Craft the new packet which is
// tmpChiper = sessionKey + localNonce + plaintext.
var tmpChiper = new byte[plaintext.Length + KeyPair.NonceLength * 2];
Buffer.BlockCopy(sessionKey, 0, tmpChiper, 0, KeyPair.NonceLength);
Buffer.BlockCopy(localNonce, 0, tmpChiper, KeyPair.NonceLength, KeyPair.NonceLength);
Buffer.BlockCopy(plaintext, 0, tmpChiper, KeyPair.NonceLength * 2, plaintext.Length);
// Use our specified from the constructor _keyPair.PublicKey and specified _serverKey from the constructor
// to generate the blake2b nonce and encrypt using _keyPair.PrivateKey and the generated blake2b nonce.
_crypto.UpdateSharedKey(serverKey);
_crypto.Encrypt(ref tmpChiper);
// Craft another new packet which is
// chiper = _keyPair.PublicKey + tmpChiper.
chiper = new byte[tmpChiper.Length + KeyPair.KeyLength];
Buffer.BlockCopy(_crypto.KeyPair.PublicKey, 0, chiper, 0, KeyPair.KeyLength);
Buffer.BlockCopy(tmpChiper, 0, chiper, KeyPair.KeyLength, tmpChiper.Length);
_localNonce = localNonce;
}
// Messages after the previous states are processed the same way.
else if (_outgoingState > (int)_direction)
{
var tmpChiper = (byte[])plaintext.Clone();
_crypto.Encrypt(ref tmpChiper);
chiper = tmpChiper;
}
return(chiper);
}
