internal static byte[] Send(DHHandshakeContext context)
{
var clear = new byte[304];
var writer = new BufRefLen(clear);
var keys = I2PPrivateKey.GetNewKeyPair();
context.PrivateKey = keys.PrivateKey;
context.Y = keys.PublicKey;
context.YBuf = new BufLen(context.Y.Key);
var sharedkey = BufUtils.DHI2PToByteArray(context.X.ToBigInteger().ModPow(context.PrivateKey.ToBigInteger(), I2PConstants.ElGamalP));
context.SessionKey = new I2PSessionKey(sharedkey);
writer.Write(context.YBuf);
context.TimestampB = (uint)(DateTime.UtcNow - I2PDate.RefDate).TotalSeconds;
writer.Write(I2PHashSHA256.GetHash(context.XBuf, context.YBuf));
writer.WriteFlip32(context.TimestampB);
writer.Write(BufUtils.Random(12));
var key = new KeyParameter(context.SessionKey.Key.ToByteArray());
var iv = context.YBuf.PeekB(context.YBuf.Length - 16, 16);
context.Encryptor = new CbcBlockCipher(new AesEngine());
context.Encryptor.Init(true, new ParametersWithIV(key, iv, 0, 16));
iv = context.HXxorHI.PeekB(context.HXxorHI.Length - 16, 16);
context.Dectryptor = new CbcBlockCipher(new AesEngine());
context.Dectryptor.Init(false, new ParametersWithIV(key, iv, 0, 16));
context.Encryptor.ProcessBytes(new BufLen(clear, 256, 48));
return(clear);
}
internal static void Receive(DHHandshakeContext context, BufLen data)
{
var reader = new BufRefLen(data);
context.Y = new I2PPublicKey(reader, context.RemoteRI.Certificate);
context.YBuf = context.Y.Key;
var sharedkey = BufUtils.DHI2PToByteArray(context.Y.ToBigInteger().ModPow(context.PrivateKey.ToBigInteger(), I2PConstants.ElGamalP));
context.SessionKey = new I2PSessionKey(sharedkey);
var key = new KeyParameter(context.SessionKey.Key.ToByteArray());
var enciv = new BufLen(context.HXxorHI.BaseArray, context.HXxorHI.Length - 16, 16);
var deciv = new BufLen(context.YBuf, context.YBuf.Length - 16, 16);
context.Encryptor = new CbcBlockCipher(new AesEngine());
context.Encryptor.Init(true, new ParametersWithIV(key, enciv.BaseArray, enciv.BaseArrayOffset, enciv.Length));
context.Dectryptor = new CbcBlockCipher(new AesEngine());
context.Dectryptor.Init(false, new ParametersWithIV(key, deciv.BaseArray, deciv.BaseArrayOffset, deciv.Length));
var encrbuf = new BufLen(reader, 0, 32 + 4 + 12);
context.Dectryptor.ProcessBytes(encrbuf);
context.HXY = reader.ReadBufLen(32);
context.TimestampB = reader.ReadFlip32();
var checkhash = I2PHashSHA256.GetHash(context.XBuf, context.YBuf);
if (!context.HXY.Equals(checkhash))
{
throw new ChecksumFailureException("NTCP SessionCreated received HXY check failed!");
}
}