using System;

​

public class Program

{

    public static void Main()

    {

        //enter the client secret from the portal here. 

        var clientSecret = "oShzaTm89ktDKW4vrCHy2BPW04LyUcNrKWJr5VIq"; //client secret key

​

        //generate the test HMAC value

        Console.WriteLine("Test Authentication Key:" +GenerateHMAC("6619237621900826|20180109161437|sixTOKENfour", clientSecret)); //client provided string

    }

​

​

    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);

    }

}