字符串加密解密

        //加密算法  
        /// <summary>  
        /// 进行DES加密。  
        /// </summary>  
        /// <param name="pToEncrypt">要加密的字符串。</param>  
        /// <param name="sKey">密钥，且必须为8位。</param>  
        /// <returns>以Base64格式返回的加密字符串。</returns>  
        public static string Encrypt(string pToEncrypt, string sKey)
        {
            using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())
            {
                byte[] inputByteArray = Encoding.UTF8.GetBytes(pToEncrypt);
                des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
                des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
                System.IO.MemoryStream ms = new System.IO.MemoryStream();
                using (CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write))
                {
                    cs.Write(inputByteArray, 0, inputByteArray.Length);
                    cs.FlushFinalBlock();
                    cs.Close();
                }
                string str = Convert.ToBase64String(ms.ToArray());
                ms.Close();
                return str;
            }
        }
        /**/
        /// <summary>  
        /// 进行DES解密。  
        /// </summary>  
        /// <param name="pToDecrypt">要解密的以Base64</param>  
        /// <param name="sKey">密钥，且必须为8位。</param>  
        /// <returns>已解密的字符串。</returns>  
        public static string Decrypt(string pToDecrypt, string sKey)
        {
            byte[] inputByteArray = Convert.FromBase64String(pToDecrypt);
            using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())
            {
                des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
                des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
                System.IO.MemoryStream ms = new System.IO.MemoryStream();
                using (CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write))
                {
                    cs.Write(inputByteArray, 0, inputByteArray.Length);
                    cs.FlushFinalBlock();
                    cs.Close();
                }
                string str = Encoding.UTF8.GetString(ms.ToArray());
                ms.Close();
                return str;
            }
        }