MD5加密

       public static string MD5ToString(String argString)
        {
            MD5 md5 = new MD5CryptoServiceProvider();
            byte[] data = System.Text.Encoding.Default.GetBytes(argString);
            byte[] result = md5.ComputeHash(data);
            String strReturn = String.Empty;
            for (int i = 0; i < result.Length; i++)
                strReturn += result[i].ToString("x").PadLeft(2, '0');
            return strReturn;
        }