using System;

using System.Collections.Generic;

using System.Linq;

using System.Security.Cryptography;

using System.Text;

using System.Threading.Tasks;

using System.Numerics;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

var apiKey = BigInteger.Parse(

    "2de51c4fd0f04b9fabeb95225e87da70",

    NumberStyles.HexNumber

);

var connectionId = BigInteger.Parse(

    "5fecbc200f0e4a7cbf41040e11047e56",

    NumberStyles.HexNumber

);

​

         HMACSHA1 hmac = new HMACSHA1(UTF8Encoding.UTF8.GetBytes(apiKey.ToString("N").ToLower()));

         string authentication = Convert.ToBase64String(hmac.ComputeHash(UTF8Encoding.UTF8.GetBytes(connectionId.ToString("N").ToLower())));

        Console.WriteLine(authentication);

    }

}