private static string key = "VSQAdmin";//密文 加密解密是都需要密文且保持一致

        private static string iv = "VSQAdmin";//加密解密时key 、 iv 中传入的key、iv值一致




        /// <summary>
        /// Des解密
        /// </summary>
        /// <param name="pToDecrypt"></param>
        /// <returns></returns>
        public  static string DecryptString(string pToDecrypt)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            byte[] inputByteArray = new byte[pToDecrypt.Length / 2];
            for (int x = 0; x < pToDecrypt.Length / 2; x++)
            {
                int i = (Convert.ToInt32(pToDecrypt.Substring(x * 2, 2), 16));
                inputByteArray[x] = (byte)i;
            }

            des.Key = UTF8Encoding.UTF8.GetBytes(key);//***************key与加密时的Key保持一致
            des.IV = UTF8Encoding.UTF8.GetBytes(iv);//*****************skey与加密时的IV保持一致

            MemoryStream ms = new MemoryStream();

            CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();

            StringBuilder ret = new StringBuilder();
            return Encoding.UTF8.GetString(ms.ToArray());
        }
        /// <summary>
        /// Des加密
        /// </summary>
        /// <param name="encryptString"></param>
        /// <returns></returns>
        public static string Des(string encryptString)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();

            byte[] sor = Encoding.UTF8.GetBytes(encryptString);
            //传入key、iv
            des.Key = UTF8Encoding.UTF8.GetBytes(key);
            des.IV = UTF8Encoding.UTF8.GetBytes(iv);

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

            cs.Write(sor, 0, sor.Length);
            cs.FlushFinalBlock();

            StringBuilder sb = new StringBuilder();
            foreach (byte b in ms.ToArray())
            {
                sb.AppendFormat("{0:X2}", b);
            }
            return sb.ToString();
        }