public static string Key        {            get            {                return key;            }            set            {                key = value;            }        }

        /// <summary>                /// DES Encrypt            /// </summary>        /// <param name="encryptString">要加密的字符串</param>        /// <returns>加密后的字符串</returns>        public static string DesEncrypt(string encryptString)        {            byte[] keyBytes = System.Text.Encoding.UTF8.GetBytes(key.Substring(0, 8));            byte[] keyIV = keyBytes;            byte[] inputByteArray = Encoding.UTF8.GetBytes(encryptString);            System.Security.Cryptography.DESCryptoServiceProvider provider = new System.Security.Cryptography.DESCryptoServiceProvider();            System.IO.MemoryStream mStream = new System.IO.MemoryStream();            System.Security.Cryptography.CryptoStream cStream = new System.Security.Cryptography.CryptoStream(mStream, provider.CreateEncryptor(keyBytes, keyIV), System.Security.Cryptography.CryptoStreamMode.Write);            cStream.Write(inputByteArray, 0, inputByteArray.Length);            cStream.FlushFinalBlock();            return Convert.ToBase64String(mStream.ToArray());        }    

         /// <summary>                /// Function : DES Decrypt        /// </summary>        /// <param name="decryptString">要解密的字符串</param>        /// <returns>解密后的字符串</returns>        public static string DesDecrypt(string decryptString)        {            byte[] keyBytes = Encoding.UTF8.GetBytes(key.Substring(0, 8));            byte[] keyIV = keyBytes;            byte[] inputByteArray = Convert.FromBase64String(decryptString);            System.Security.Cryptography.DESCryptoServiceProvider provider = new System.Security.Cryptography.DESCryptoServiceProvider();            System.IO.MemoryStream mStream = new System.IO.MemoryStream();            System.Security.Cryptography.CryptoStream cStream = new System.Security.Cryptography.CryptoStream(mStream, provider.CreateDecryptor(keyBytes, keyIV), System.Security.Cryptography.CryptoStreamMode.Write);            cStream.Write(inputByteArray, 0, inputByteArray.Length);            cStream.FlushFinalBlock();            return Encoding.UTF8.GetString(mStream.ToArray());        }