DES加密 DES解密

 1         public static string _KEY = "HQDCKEY1";  //密钥  
 2         public static string _IV = "HQDCKEY2";   //向量  
 3 
 4         /// <summary>  
 5         /// DES加密  
 6         /// </summary>  
 7         /// <param name="data"></param>  
 8         /// <returns></returns>  
 9         public static string Encode(string data)
10         {
11 
12             byte[] byKey = System.Text.ASCIIEncoding.ASCII.GetBytes(_KEY);
13             byte[] byIV = System.Text.ASCIIEncoding.ASCII.GetBytes(_IV);
14 
15             DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();
16             int i = cryptoProvider.KeySize;
17             MemoryStream ms = new MemoryStream();
18             CryptoStream cst = new CryptoStream(ms, cryptoProvider.CreateEncryptor(byKey, byIV), CryptoStreamMode.Write);
19 
20             StreamWriter sw = new StreamWriter(cst);
21             sw.Write(data);
22             sw.Flush();
23             cst.FlushFinalBlock();
24             sw.Flush();
25 
26             string strRet = Convert.ToBase64String(ms.GetBuffer(), 0, (int)ms.Length);
27             return strRet;
28         }
29 
30         /// <summary>  
31         /// DES解密  
32         /// </summary>  
33         /// <param name="data"></param>  
34         /// <returns></returns>  
35         public static string Decode(string data)
36         {
37 
38             byte[] byKey = System.Text.ASCIIEncoding.ASCII.GetBytes(_KEY);
39             byte[] byIV = System.Text.ASCIIEncoding.ASCII.GetBytes(_IV);
40 
41             byte[] byEnc;
42 
43             try
44             {
45                 data.Replace("_%_", "/");
46                 data.Replace("-%-", "#");
47                 byEnc = Convert.FromBase64String(data);
48 
49             }
50             catch
51             {
52                 return null;
53             }
54 
55             DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();
56             MemoryStream ms = new MemoryStream(byEnc);
57             CryptoStream cst = new CryptoStream(ms, cryptoProvider.CreateDecryptor(byKey, byIV), CryptoStreamMode.Read);
58             StreamReader sr = new StreamReader(cst);
59             return sr.ReadToEnd();
60         }