using System;

using System.Linq;

using System.Text;

using System.Security.Cryptography;

public class Program

{

    public static void Main()

    {

        Console.Write(CreateToken("cardCVC=123&cardExp=2105&cardNum=5123456789012346&holderName=John Doe&mobileNumber=20100000000000","C0DF9A7B3819968807A9D4E48D0E65C6"));

    }

​

     private static string CreateToken(string message, string secret)

    {

      var encoding = new System.Text.UTF8Encoding();

      byte[] keyByte = encoding.GetBytes(secret);

      byte[] messageBytes = encoding.GetBytes(message);

      using (var hmacsha256 = new HMACSHA256(keyByte))

      {

        byte[] hashmessage = hmacsha256.ComputeHash(messageBytes);

        return BitConverter.ToString(hashmessage).Replace("-","");

      }

    }

}