/// <summary>

        /// 加密

        /// </summary>

        /// <param name="str"></param>

        /// <returns></returns>

        private string Encryption(string str)

        {

            string psw;

            string key = "tracymac";

            using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())

            {

                byte[] inputByteArray = Encoding.UTF8.GetBytes(str);

                des.Key = ASCIIEncoding.ASCII.GetBytes(key);

                des.IV = ASCIIEncoding.ASCII.GetBytes(key);

                System.IO.MemoryStream ms = new System.IO.MemoryStream();

                using (CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write))

                {

                    cs.Write(inputByteArray, , inputByteArray.Length);

                    cs.FlushFinalBlock();

                    cs.Close();

                }

                psw = Convert.ToBase64String(ms.ToArray());

                ms.Close();

            }

            return psw;

        }

        /// <summary>

        /// 解密

        /// </summary>

        /// <param name="psw"></param>

        /// <returns></returns>

        private string Decode(string psw)

        {

            string str;

            string key = "tracymac";

            using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())

            {

                byte[] inputByteArray = Convert.FromBase64String(psw);

                des.Key = ASCIIEncoding.ASCII.GetBytes(key);

                des.IV = ASCIIEncoding.ASCII.GetBytes(key);

                System.IO.MemoryStream ms = new System.IO.MemoryStream();

                using (CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write))

                {

                    cs.Write(inputByteArray, , inputByteArray.Length);

                    cs.FlushFinalBlock();

                    cs.Close();

                }

                str = Encoding.UTF8.GetString(ms.ToArray());

                ms.Close();

            }

            return str;

        }