any example for use it with NodeJs ?  #1

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1. bag7dad commented on Oct 5, 2020

   

   bag7dad

   on Oct 5, 2020

   Last edited by bag7dad

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   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
2. mandelmonkey commented on Nov 26, 2022

   

   mandelmonkey

   on Nov 26, 2022

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   @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?
3. gonsodany commented on Jul 16, 2024

   

   gonsodany

   on Jul 16, 2024

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