using System;

using System.Text;

using System.Security.Cryptography;

public class Program

{

    public static void Main()

    {

        string value = @"Hello World!";

        string secret = "2HAPYKRxHrg9bq2T";

​

        Console.WriteLine("HEX hash");

        var signature1 = HexHash(value, secret);

        Console.WriteLine("Signature: " + signature1);

        Console.WriteLine();

        Console.WriteLine("Base64 hash");

        var signature2 = Base64Hash(value, secret);

        Console.WriteLine("Signature: " + signature2);

        Console.WriteLine();

        Console.WriteLine("Secret key: " + secret);

        Console.WriteLine("Message:");

        Console.WriteLine(value);

    }

    private static string Base64Hash(string value, string secret)

    {

        Encoding encoding = Encoding.UTF8;

        var hmac = new HMACSHA256(encoding.GetBytes(secret));

        return Convert.ToBase64String(hmac.ComputeHash(encoding.GetBytes(value)));

    }

    private static string HexHash(string value, string secret)

    {

        using (var hmacSha256 = new HMACSHA256(Encoding.UTF8.GetBytes(secret)))

        {

            byte[] bytes = Encoding.UTF8.GetBytes(value);

            byte[] hash = hmacSha256.ComputeHash(bytes);

​

            //Console.WriteLine("ToBase64String: " + Convert.ToBase64String(hash));

            //Console.WriteLine("BitConverter (HEX): " + BitConverter.ToString(hash));

            return BitConverter.ToString(hash)

                .Replace("-", string.Empty);

        }

    }

}