Use FormsAuthentication

   

using System;
using System.Web.Security;

//MD5Test

class Class1 {

    static void Main(string[] args) {
        string Brian = FormsAuthentication.HashPasswordForStoringInConfigFile("MyPassword", "MD5");
        Console.WriteLine(Brian);
        Brian = FormsAuthentication.HashPasswordForStoringInConfigFile("MyPassword", "sha1");
        Console.WriteLine(Brian);

    }
}