using System;

using System.Security.Cryptography;

using System.Text;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        var testData = Encoding.UTF8.GetBytes("Testing");

        using (var hasher = new HMACSHA256()) {

            var hash1 = hasher.ComputeHash(testData);

            Console.WriteLine(BitConverter.ToString(hash1).Replace("-",""));

        }       

        using (var hasher2 = new HMACSHA256()) {

            var hash2 = hasher2.ComputeHash(testData);

            //Console.WriteLine(string.Join("", hash2.Select(b => b.ToString("x2")).ToArray()));

            Console.WriteLine(BitConverter.ToString(hash2).Replace("-",""));

        }

        var secretKey = Encoding.UTF8.GetBytes("Secret Raygun Key!!");             

        using (var hasher3 = new HMACSHA256(secretKey)) {

            var hash3 = hasher3.ComputeHash(testData);

            Console.WriteLine("\n" + BitConverter.ToString(hash3).Replace("-",""));

        }

        using (var hasher4 = new HMACSHA256(secretKey)) {

            var hash4 = hasher4.ComputeHash(testData);

            Console.WriteLine(BitConverter.ToString(hash4).Replace("-",""));

        }

    }

}