pkey加密使用的秘钥
         bIV加密使用的偏移向量
 
         using System.Security.Cryptography;
 
  
      
        static string pkey = "WELCOMEGUY";  
        static byte[] bIV = { 0x00, 0x00, 0x00, 0x00, (byte)0x00, (byte)0xXX, (byte)0xOO, (byte)0xXO };
 
 
        /// <summary>
        /// DES加密
        /// </summary>
        /// <param name="str">需要加密的</param>
        /// <returns></returns>
        private static string Encrypt(string str)
        {            
            byte[] inputByteArray = Encoding.UTF8.GetBytes(str);
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            MemoryStream ms = new MemoryStream();
            CryptoStream cs=new CryptoStream(
                                                ms,
                                                des.CreateEncryptor(Encoding.UTF8.GetBytes(pkey), bIV),
                                                CryptoStreamMode.Write
                                             );
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            return Convert.ToBase64String(ms.ToArray());
            
        }
        /// <summary>
        /// DES解密
        /// </summary>
        /// <param name="pToDecrypt">需要解密的</param>
        /// <returns></returns>
        private static string Decrypt(string pToDecrypt)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            byte[] inputByteArray = Convert.FromBase64String(pToDecrypt);            
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(
                                                ms,
                                                des.CreateDecryptor(Encoding.UTF8.GetBytes(pkey), bIV),
                                                CryptoStreamMode.Write
                                                );
            cs.Write(inputByteArray, 0, inputByteArray.Length);            
            cs.FlushFinalBlock();
            return Encoding.UTF8.GetString(ms.ToArray());
        }