static void Main(string[] args)
        {
            string s = GetMd5("123");
            Console.WriteLine(s);
            Console.ReadKey();
        }

        static string GetMd5(string str)
        {
            byte[] result = Encoding.Default.GetBytes(str.Trim());    //tbPass为输入密码的文本框
            MD5 md5 = new MD5CryptoServiceProvider();
            byte[] output = md5.ComputeHash(result);
            return  BitConverter.ToString(output).Replace("-", "");
        }