C#实现DES对称加密法

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入口参数有三个:key、data、mode。 key为加密解密使用的密钥，data为加密解密的数据，mode为其工作模式。当模式为加密模式时，明文按照64位进行分组，形成明文组，key用于对数据加密，当模式为解密模式时，key用于对数据解密。实际运用中，密钥只用到了64位中的56位，这样才具有高的安全性。

1 /// <summary>
2   /// DES对称加密
3   /// </summary>
4   public sealed class DES {
5     /// <summary>
6     /// Des解密方法
7     /// </summary>
8     /// <param name="val"></param>
9     /// <param name="key"></param>
10     /// <param name="IV"></param>
11     /// <returns></returns>
12     public static string Decrypt(string val, string key, string IV) {
13       try {
14         byte[] buffer1 = Convert.FromBase64String(key);
15         byte[] buffer2 = Convert.FromBase64String(IV);
16         DESCryptoServiceProvider provider1 = new DESCryptoServiceProvider();
17         provider1.Mode = CipherMode.ECB;
18         provider1.Key = buffer1;
19         provider1.IV = buffer2;
20         ICryptoTransform transform1 = provider1.CreateDecryptor(provider1.Key, provider1.IV);
21         byte[] buffer3 = Convert.FromBase64String(val);
22         MemoryStream stream1 = new MemoryStream();
23         CryptoStream stream2 = new CryptoStream(stream1, transform1, CryptoStreamMode.Write);
24         stream2.Write(buffer3, 0, buffer3.Length);
25         stream2.FlushFinalBlock();
26         stream2.Close();
27         return Encoding.Default.GetString(stream1.ToArray());
28       }
29       catch// (System.Exception ex)
30       {
31         return "";
32       }
33     }
34
35     /// <summary>
36     /// Des加密方法
37     /// </summary>
38     /// <param name="val"></param>
39     /// <param name="key"></param>
40     /// <param name="IV"></param>
41     /// <returns></returns>
42     public static string Encrypt(string val, string key, string IV) {
43       try {
44         byte[] buffer1 = Convert.FromBase64String(key);
45         byte[] buffer2 = Convert.FromBase64String(IV);
46
47         DESCryptoServiceProvider provider1 = new DESCryptoServiceProvider();
48         provider1.Mode = CipherMode.ECB;
49         provider1.Key = buffer1;
50         provider1.IV = buffer2;
51         ICryptoTransform transform1 = provider1.CreateEncryptor(provider1.Key, provider1.IV);
52         byte[] buffer3 = Encoding.Default.GetBytes(val);
53         MemoryStream stream1 = new MemoryStream();
54         CryptoStream stream2 = new CryptoStream(stream1, transform1, CryptoStreamMode.Write);
55         stream2.Write(buffer3, 0, buffer3.Length);
56         stream2.FlushFinalBlock();
57         stream2.Close();
58         return Convert.ToBase64String(stream1.ToArray());
59       }
60       catch// (Exception ex)
61       {
62         return "";
63       }
64     }
65   }
66