Des加密与解密

        /// <summary>
        /// 文件加密
        /// </summary>
        /// <param name="sInputFilename">未加密文件路径</param>
        /// <param name="sOutputFilename">加密以后文件保存路径</param>
        /// <param name="sKey">密钥</param>
        public void EncryptFile(string sInputFilename,string sOutputFilename)
        {
            FileStream fsInput = new FileStream(sInputFilename,FileMode.Open,FileAccess.Read);
            FileStream fsEncrypted = new FileStream(sOutputFilename, FileMode.Create,FileAccess.Write);
            DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
            DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
            DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
            ICryptoTransform desencrypt = DES.CreateEncryptor();
            CryptoStream cryptostream = new CryptoStream(fsEncrypted,desencrypt,CryptoStreamMode.Write);
            byte[] bytearrayinput = new byte[fsInput.Length];
            fsInput.Read(bytearrayinput, 0, bytearrayinput.Length);
            cryptostream.Write(bytearrayinput, 0, bytearrayinput.Length);
            cryptostream.Close();
            fsInput.Close();
            fsEncrypted.Close();
        }
        /// <summary>
        /// 解密文件
        /// </summary>
        /// <param name="sInputFilename">被加密过的文件路径</param>
        /// <param name="sOutputFilename">被解密以后的文件路径</param>
        /// <param name="sKey">密钥</param>
        public void DecryptFile(string sInputFilename, string sOutputFilename,string sKey)
        {
            DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
            DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
            DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
            FileStream fsread = new FileStream(sInputFilename,FileMode.Open,FileAccess.Read);
            ICryptoTransform desdecrypt = DES.CreateDecryptor();
            CryptoStream cryptostreamDecr = new CryptoStream(fsread,desdecrypt,CryptoStreamMode.Read);
            StreamWriter fsDecrypted = new StreamWriter(sOutputFilename);
            fsDecrypted.Write(new StreamReader(cryptostreamDecr).ReadToEnd());
            fsDecrypted.Flush();
            fsDecrypted.Close();
        }
          // <summary>  
        /// 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 string DESEncrypt(string strToEnCrypt,string key)   
        {  
            //创建DES  
            using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())  
            {  
                //将明文转换成8位的整数  
                byte[] clearText = Encoding.UTF8.GetBytes(strToEnCrypt);  
                //设置密钥  
                des.Key = ASCIIEncoding.ASCII.GetBytes(key);  
                //设置初始化向量  
                des.IV = ASCIIEncoding.ASCII.GetBytes(key);  
                //创建内存流  
                System.IO.MemoryStream ms = new System.IO.MemoryStream();  
                //将内存流转连接到加密的流  
                using (CryptoStream cs = new CryptoStream(ms,des.CreateEncryptor(),CryptoStreamMode.Write))  
                {  
                    cs.Write(clearText,0,clearText.Length);  
                    cs.FlushFinalBlock();  
                    cs.Close();  
                }  
                string str = Convert.ToBase64String(ms.ToArray());  
                ms.Close();  
                return str;  
            }  
        }  
        /// <summary>  
        /// DES解密  
        /// </summary>  
        /// <param name="strToDeCrypt">要解密的以Base64</param>  
        /// <param name="key">密钥，且必须为8位。</param>  
        /// <returns>已解密的字符串。</returns>  
        public string DESDecrypt(string strToDeCrypt,string key)   
        {  
            //将密文转换成8位整数数组  
            byte[] cryptText = Convert.FromBase64String(strToDeCrypt);  
            //创建DES  
            using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())  
            {  
                //设置密钥  
                des.Key = ASCIIEncoding.ASCII.GetBytes(key);  
                //设置初始化向量  
                des.IV = ASCIIEncoding.ASCII.GetBytes(key);  
                //创建内存流  
                System.IO.MemoryStream ms = new System.IO.MemoryStream();  
                //将内存流连接到加密的流  
                using (CryptoStream cs = new CryptoStream(ms,des.CreateDecryptor(),CryptoStreamMode.Write))  
                {  
                    cs.Write(cryptText,0,cryptText.Length);  
                    cs.FlushFinalBlock();  
                    cs.Close();  
                }  
                string str = Encoding.UTF8.GetString(ms.ToArray());  
                ms.Close();  
                return str;  
            }  
        }