using System;

using System.Security.Cryptography;

using System.Text;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        var epoch = new DateTime(1970, 1, 1);

        var dateNow = DateTime.Now;

        var epochResult = dateNow - epoch;

        var message = epochResult.ToString();

        Console.WriteLine("Epoch time: " + message);

        var publicKey = "0oa70WuefiddqLjqlTls";

        var privateKey = "m2vQxqNixqrEDcQ2heVa";

        var theDigest = CalculateDigest(publicKey, privateKey, message);

        Console.WriteLine("Signature: " + theDigest);

        Console.WriteLine("JS Staging URL: https://checkout.tpay.me/script/CheckoutScript?epochTimeSpan="+ epochResult +"&signature="+ theDigest);

    }

​

    public static string CalculateDigest(string publicKey, string privateKey, string message)

    {

        var signature = "";

        var hash = new System.Security.Cryptography.HMACSHA256(System.Text.Encoding.UTF8.GetBytes(privateKey));

        var correctHash = string.Join(string.Empty, hash.ComputeHash(System.Text.Encoding.UTF8.GetBytes(message)).Select(b => b.ToString("x2")));

        signature = publicKey + ":" + correctHash;

        return signature;

    }

}