C# DES加密解密用法

主要用到C#提供的以下三个类：
MemoryStream 内存流
DESCryptoServiceProvider 加密服务提供者类
CryptoStream 讲数据流连接到加密转换的流

下面是简易代码，已经过测试：

     public static string strKey = "abcdefgh";
     public static string strIV = "ijklmnop";
     private XmlDocument XmlDoc = null;
     private XmlElement XmlRoot = null;

     // 字符串加密
     public static string Encrypt(string _strQ)
     {
         byte[] buffer = Encoding.UTF8.GetBytes(_strQ);
         MemoryStream ms = new MemoryStream();
         DESCryptoServiceProvider tdes = new DESCryptoServiceProvider();
         CryptoStream encStream = new CryptoStream(ms, tdes.CreateEncryptor(Encoding.UTF8.GetBytes(strKey), Encoding.UTF8.GetBytes(strIV)), CryptoStreamMode.Write);
         encStream.Write(buffer, , buffer.Length);
         encStream.FlushFinalBlock();
         return Convert.ToBase64String(ms.ToArray()).Replace("+", "%");
     }

     // 字符串解密
     public static string Decrypt(string _strQ)
     {
         _strQ = _strQ.Replace("%", "+");
         byte[] buffer = Convert.FromBase64String(_strQ);
         MemoryStream ms = new MemoryStream();
         DESCryptoServiceProvider tdes = new DESCryptoServiceProvider();
         CryptoStream encStream = new CryptoStream(ms, tdes.CreateDecryptor(Encoding.UTF8.GetBytes(strKey), Encoding.UTF8.GetBytes(strIV)), CryptoStreamMode.Write);
         encStream.Write(buffer, , buffer.Length);
         encStream.FlushFinalBlock();
         return Encoding.UTF8.GetString(ms.ToArray());
     }

     // 解密加载
     public void XmlLoadDecrypt(XmlDocument xmlDoc, string fileName)
     {
         FileStream fileStream = new FileStream(fileName, FileMode.Open);
         byte[] bsXml = new byte[fileStream.Length];
         fileStream.Read(bsXml, , bsXml.Length);
         fileStream.Close();

         MemoryStream ms = new MemoryStream();
         DESCryptoServiceProvider tdes = new DESCryptoServiceProvider();
         CryptoStream encStream = new CryptoStream(ms, tdes.CreateDecryptor(Encoding.UTF8.GetBytes(strKey), Encoding.UTF8.GetBytes(strIV)), CryptoStreamMode.Write);
         encStream.Write(bsXml, , bsXml.Length);
         encStream.FlushFinalBlock();

         xmlDoc.Load(new MemoryStream(ms.ToArray()));
     }

     // 加密存储
     public void XmlSaveEncrypt(XmlDocument xmlDoc, string fileName)
     {
         if (!File.Exists(fileName))
             File.Create(fileName).Close();

         FileStream fileStream = new FileStream(fileName, FileMode.Truncate);
         MemoryStream msXml = new MemoryStream();
         xmlDoc.Save(msXml);

         DESCryptoServiceProvider tdes = new DESCryptoServiceProvider();
         CryptoStream cs = new CryptoStream(fileStream, tdes.CreateEncryptor(Encoding.UTF8.GetBytes(strKey), Encoding.UTF8.GetBytes(strIV)), CryptoStreamMode.Write);
         cs.Write(msXml.ToArray(), , msXml.ToArray().Length);
         cs.FlushFinalBlock();

         msXml.Close();
         fileStream.Close();
     }

     // 测试代码
     string str1 = "abcdefghijklmnopqrstuvwxyz";
     if (GUI.Button(new Rect(, , , ), "Encrypt"))
     {
         Debug.Log(Encrypt(str1));
     }
     if (GUI.Button(new Rect(, , , ), "Decrypt"))
     {
         Debug.Log(Decrypt(Encrypt(str1)));
     }
     if (GUI.Button(new Rect(, , , ), "Load Decrypt Xml"))
     {
         XmlDoc = new XmlDocument();
         XmlLoadDecrypt(XmlDoc, "Assets/123.xml");
         XmlRoot = XmlDoc.DocumentElement;
         Debug.Log(XmlRoot.GetAttribute("Test"));
     }
     if (GUI.Button(new Rect(, , , ), "Save Encrypt Xml"))
     {
         XmlDoc = new XmlDocument();
         XmlRoot = XmlDoc.CreateElement("RegisterRecords");
         XmlDoc.AppendChild(XmlRoot);
         XmlRoot.SetAttribute("Test", "something");
         XmlSaveEncrypt(XmlDoc, "Assets/123.xml");
     }