using System;

public class Program

{

    public static void Main()

    {

        var time = DateTime.UtcNow.ToString("yyyyMMddHHmmss");

        var tokenexId = "TXID";

        var clientSecretKey = "ClientSecretKey";

        Console.WriteLine("Use the output below as the authentication key in JSFiddle.");

        Console.WriteLine("Authentication Key:" +GenerateHMAC(tokenexId+"|"+time+"|INSERT_TOKEN", clientSecretKey));

        Console.WriteLine("timestamp:"+time);   

    }

    private static string GenerateHMAC(string payload,string HMACKey)

    {

        var hmac = new System.Security.Cryptography.HMACSHA256{Key = System.Text.Encoding.UTF8.GetBytes(HMACKey)};

        var hash = hmac.ComputeHash(System.Text.Encoding.UTF8.GetBytes(payload));

        return Convert.ToBase64String(hash);

    }

}