加密解密帮助类（对称加密）

 1   // 对称加密帮助类
 2     public static class CryptoHelper
 3     {
 4         //详细参考http://www.cnblogs.com/JimmyZhang/archive/2008/10/02/Cryptograph.html
 5         private static ICryptoTransform encryptor;     // 加密器对象
 6         private static ICryptoTransform decryptor;     // 解密器对象
 7
 8         private static SymmetricAlgorithm provider = SymmetricAlgorithm.Create("TripleDES");
 9
10         private const int BufferSize = 1024;
11
12
13         /// <summary>
14         /// 加密算法
15         /// </summary>
16         /// <param name="key">为24或16位字符</param>
17         /// <param name="encryptText">被加密的字符串</param>
18         /// <returns></returns>
19         public static string Encrypt(string key, string encryptedText)
20         {
21             provider.IV = new byte[] { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };
22             provider.Key = Encoding.UTF8.GetBytes(key);
23
24             encryptor = provider.CreateEncryptor();
25             // 创建明文流
26             byte[] clearBuffer = Encoding.UTF8.GetBytes(encryptedText);
27             MemoryStream clearStream = new MemoryStream(clearBuffer);
28
29             // 创建空的密文流
30             MemoryStream encryptedStream = new MemoryStream();
31
32             CryptoStream cryptoStream =
33                 new CryptoStream(encryptedStream, encryptor, CryptoStreamMode.Write);
34
35             // 将明文流写入到buffer中
36             // 将buffer中的数据写入到cryptoStream中
37             int bytesRead = 0;
38             byte[] buffer = new byte[BufferSize];
39             do
40             {
41                 bytesRead = clearStream.Read(buffer, 0, BufferSize);
42                 cryptoStream.Write(buffer, 0, bytesRead);
43             } while (bytesRead > 0);
44
45             cryptoStream.FlushFinalBlock();
46
47             // 获取加密后的文本
48             buffer = encryptedStream.ToArray();
49             string str = Convert.ToBase64String(buffer);
50             return str;
51         }
52
53         // 解密算法
54         /// <summary>
55         /// </summary>
56         /// <param name="key">为24或16位字符</param>
57         /// <param name="decryptedText">被解密的字符串</param>
58         /// <returns></returns>
59         public static string Decrypt(string key, string decryptedText)
60         {
61             provider.IV = new byte[] { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };
62             provider.Key = Encoding.UTF8.GetBytes(key);
63
64             decryptor = provider.CreateDecryptor();
65             byte[] encryptedBuffer = Convert.FromBase64String(decryptedText);
66             Stream encryptedStream = new MemoryStream(encryptedBuffer);
67
68             MemoryStream clearStream = new MemoryStream();
69             CryptoStream cryptoStream =
70                 new CryptoStream(encryptedStream, decryptor, CryptoStreamMode.Read);
71
72             int bytesRead = 0;
73             byte[] buffer = new byte[BufferSize];
74
75             do
76             {
77                 bytesRead = cryptoStream.Read(buffer, 0, BufferSize);
78                 clearStream.Write(buffer, 0, bytesRead);
79             } while (bytesRead > 0);
80
81             buffer = clearStream.GetBuffer();
82             string str =
83                 Encoding.UTF8.GetString(buffer, 0, (int)clearStream.Length);
84
85             return str;
86         }
87
88     }