using System;

using System.Text;

using System.Security.Cryptography;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World".ComputeMd5());

    }

}

​

public static class StringExtensions

{

    public static string ComputeMd5(this string input)

    {

        using (var md5 = MD5.Create())

        {

            var bytes = md5.ComputeHash(Encoding.UTF8.GetBytes(input));

​

            var sBuilder = new StringBuilder();

​

            foreach (var dataByte in bytes)

            {

                sBuilder.Append(dataByte.ToString("x2"));

            }

​

            return sBuilder.ToString();

        }

    }

}