private static TDhGenOk SerializeResponse(RequestSetClientDHParams setClientDhParams, byte[] newNonce, BigInteger agreement)
{
var newNonceHash = Sha1Helper.ComputeHashsum(newNonce).Skip(4).ToArray();
var authKeyAuxHash = Sha1Helper.ComputeHashsum(agreement.ToByteArrayUnsigned()).Take(8).ToArray();
return(new TDhGenOk
{
Nonce = setClientDhParams.Nonce,
ServerNonce = setClientDhParams.ServerNonce,
NewNonceHash1 = newNonceHash.Concat((byte)1).Concat(authKeyAuxHash).ToArray()
});
}
private static TClientDHInnerData DeserializeRequest(RequestSetClientDHParams serverDhParams, AesKeyData aesKeyData)
{
var encryptedAnswer = serverDhParams.EncryptedDataAsBinary;
var answerWithHash = AES.DecryptAes(aesKeyData, encryptedAnswer);
var serverHashsum = answerWithHash.Take(20).ToArray();
var answer = answerWithHash.Skip(20).ToArray();
var answerBuffer = PooledByteBufferAllocator.Default.Buffer();
try
{
answerBuffer.WriteBytes(answer);
var clientDhInnerData = Serializer.Deserialize(answerBuffer).Is <TClientDHInnerData>();
return(clientDhInnerData);
}
finally
{
answerBuffer.Release();
}
}
public static ISetClientDHParamsAnswer GetResponse(RequestSetClientDHParams setClientDhParams, byte[] newNonce, AsymmetricCipherKeyPair serverKeyPair, out BigInteger serverAgree, out byte[] serverSalt)
{
AesHelper.ComputeAesParameters(newNonce, setClientDhParams.ServerNonce, out var aesKeyData);
var dhInnerData = DeserializeRequest(setClientDhParams, aesKeyData);
var dhParameters = ((DHPrivateKeyParameters)serverKeyPair.Private).Parameters;
var y = new BigInteger(dhInnerData.GBAsBinary);
Guard.That(y).IsValidDhPublicKey(dhParameters.P);
var clientPublicKey = new DHPublicKeyParameters(y, dhParameters);
var serverKeyAgree = AgreementUtilities.GetBasicAgreement("DH");
serverKeyAgree.Init(serverKeyPair.Private);
serverAgree = serverKeyAgree.CalculateAgreement(clientPublicKey);
serverSalt = SaltHelper.ComputeSalt(newNonce, setClientDhParams.ServerNonce);
return(SerializeResponse(setClientDhParams, newNonce, serverAgree));
}