any example for use it with NodeJs ?

[bag7dad]

c# with nodeJS key exchange

[bag7dad]

i use this example in c#

class Program
{
  static void Main(string[] args)
  {
      using (ECDiffieHellman alice = ECDiffieHellman.Create(ECCurve.NamedCurves.brainpoolP256r1))
      {
          var alicePublicKey = Convert.ToBase64String(alice.PublicKey.ToByteArray());
          //send alicePublicKey
          var nodejsKey = ""; //NODEJS brainpoolP256r1 publickey  base64
          byte[] nodejsKeyBytes= Convert.FromBase64String(nodejsKey);

          var aliceKey = Convert.ToBase64String(getDeriveKey(nodejsKeyBytes,alice));
          byte[] encryptedMessage = null;
          byte[] iv = null;
          // Send(aliceKey, "Secret message", out encryptedMessage, out iv);
      }
  }
  static byte[] getDeriveKey(byte[] key1, ECDiffieHellman alice)
  {
      byte[] keyX = new byte[key1.Length / 2];
      byte[] keyY = new byte[keyX.Length];
      Buffer.BlockCopy(key1, 1, keyX, 0, keyX.Length);
      Buffer.BlockCopy(key1, 1 + keyX.Length, keyY, 0, keyY.Length);
      ECParameters parameters = new ECParameters
      {
          Curve = ECCurve.NamedCurves.brainpoolP256r1,
          Q =
          {
              X = keyX,
              Y = keyY,
          },
      };
      byte[] derivedKey;
      using (ECDiffieHellman bob = ECDiffieHellman.Create(parameters))
      using (ECDiffieHellmanPublicKey bobPublic = bob.PublicKey)
      {
          return derivedKey = alice.DeriveKeyFromHash(bobPublic, HashAlgorithmName.SHA256);
      }
  }
}

and the nodeJs

`const crypto = require("crypto");
const bob = crypto.createECDH('brainpoolP256r1')
bob.generateKeys();
const bobKey = bob.getPublicKey('base64');
var bobLength = Buffer.from(bobKey, 'base64').length;
//send bobkey to c#
//recive alicekey

var alicePublicKey = "RUNLUCAAAAB/xP7JhSIhYIYAijyC2zHu7obB5CwfK/ynQPxcRAIhBI6OLRRcHyPo61AhfSZN3qA2vGDfWO2mrdWWvqqhVaDf";
var aliceKeyBuffer = Buffer.from(alicePublicKey, 'base64');
var aliceKey = Buffer.alloc(bobLength)
aliceKeyBuffer.copy(aliceKey, 1, 8);
aliceKey[0] = 4;
const hash = crypto.createHash('sha256');
var tt = bob.computeSecret(aliceKey);
var bobSecretKey = hash.update(tt).digest('base64');`

but the c# code not work in Unity so i want to use your library for that can you provide an example

[mandelmonkey]

@medozeus did you ever figure this out? I guess the curve type needs to change to use what ever which seems to be some 25519 montgomery thing which nodejs doesnt support?

[gonsodany]

Did you ever figure out, im trying to use DiffieHellman for a unity - Python flask api scenario