public static IServerDHParams GetResponse(RequestReqDHParams reqDhParams, string privateKey, out AsymmetricCipherKeyPair serverKeyPair, out byte[] newNonce)
{
var pqInnerData = DeserializeRequest(reqDhParams, privateKey);
GeneratePandG(out var p, out var g);
KeyGenerationParameters kgp = new DHKeyGenerationParameters(new SecureRandom(), new DHParameters(p, BigInteger.ValueOf(g)));
var keyGen = GeneratorUtilities.GetKeyPairGenerator("DH");
keyGen.Init(kgp);
serverKeyPair = keyGen.GenerateKeyPair();
var publicKey = (DHPublicKeyParameters)serverKeyPair.Public;
var dhInnerData = new TServerDHInnerData
{
DhPrimeAsBinary = publicKey.Parameters.P.ToByteArray(),
Nonce = pqInnerData.Nonce,
ServerNonce = pqInnerData.ServerNonce,
G = publicKey.Parameters.G.IntValue,
GAAsBinary = publicKey.Y.ToByteArray(),
ServerTime = (int)((DateTimeOffset)DateTime.Now).ToUnixTimeSeconds()
};
newNonce = pqInnerData.NewNonce;
return(SerializeResponse(pqInnerData, dhInnerData));
}
private static TPQInnerData Decrypt(RequestReqDHParams requestReqDhParams, out byte[] checksum)
{
var decryptedResponse = RSAHelper.RsaDecryptWithPrivate(requestReqDhParams.EncryptedDataAsBinary, PrivateKey);
var decryptedResponseBuffer = PooledByteBufferAllocator.Default.Buffer();
decryptedResponseBuffer.WriteBytes(decryptedResponse);
checksum = new byte[20];
decryptedResponseBuffer.ReadBytes(checksum);
return((TPQInnerData)Serializer.Deserialize(decryptedResponseBuffer));
}
private static TPQInnerData DeserializeRequest(RequestReqDHParams reqDhParams, string privateKey)
{
var encryptedData = reqDhParams.EncryptedDataAsBinary;
var innerDataWithHash = RSAHelper.RsaDecryptWithPrivate(encryptedData, privateKey);
var shaHashsum = innerDataWithHash.Take(20).ToArray();
var innerData = innerDataWithHash.Skip(20).ToArray();
var hashsum = Sha1Helper.ComputeHashsum(innerData);
Guard.That(shaHashsum).IsItemsEquals(hashsum);
var innerDataBuffer = PooledByteBufferAllocator.Default.Buffer(innerData.Length);
innerDataBuffer.WriteBytes(innerData);
return(Serializer.Deserialize(innerDataBuffer).Is <TPQInnerData>());
}
