System.Security.Cryptography.MD5CryptoServiceProvider md5 = new System.Security.Cryptography.MD5CryptoServiceProvider(); Random ra = new Random(); var rr= ra.Next(1,100000); byte[] test = System.Text.Encoding.UTF8.GetBytes(rr.ToString()); Console.WriteLine(rr); byte[] output = md5.ComputeHash(test); Console.WriteLine("md5-1:" + BitConverter.ToString(output).Replace("-","")); Console.WriteLine("md5-2:" + FormsAuthentication.HashPasswordForStoringInConfigFile(rr.ToString(), "MD5"));