C#实现AES的加解密算法

C#实现AES的加解密
    顺便提一下，有些人搞不懂为什么加密后数据会变长，这是因为对称加密算法是分组加密，也就是按照预先设定好的块大小进行加密。加密时，首先将明文进行分块，对于最后一块，如果少于块的大小，是需要进行填充的。因此有不同的填充模式。还有有的时候，解密数据时报错：数据长度不符合要求时，也多半是由于程序中加密出了错，因为加密后的密文应该是块大小的整数倍的。.NET中的密码算法可以进行很多配置，还可以进行扩展。如采用不同的链接模式，填充模式、块大小，密钥长度等。需要详细了解的话可以先看一下对称加密的基础知识，再参考下MSDN。下面是用C#实现的AES加解密算法：AES密钥默认长度是128位的。代码如下：

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01.using System;   
02.using System.Security.Cryptography;   
03.using System.Text;   
04.using System.IO;   
05.  
06.namespace GraduationDesign   
07.{       
08.    class AESEncryption    
09.    {           
10.        //默认密钥向量    
11.        private static byte[] _key1 = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF, 0x12, 0x34, 0x56,  0x78, 0x90, 0xAB, 0xCD, 0xEF };    
12.  
13.        /// <summary>   
14.        /// AES加密算法   
15.        /// </summary>   
16.        /// <param name="plainText">明文字符串</param>   
17.        /// <param name="strKey">密钥</param>   
18.        /// <returns>返回加密后的密文字节数组</returns>   
19.        public static byte[] AESEncrypt(string plainText , string strKey )   
20.        {   
21.            //分组加密算法   
22.            SymmetricAlgorithm des = Rijndael .Create () ;                 
23.            byte[] inputByteArray =Encoding .UTF8  .GetBytes (plainText ) ;//得到需要加密的字节数组       
24.                            //设置密钥及密钥向量   
25.            des.Key =Encoding.UTF8.GetBytes (strKey );   
26.            des.IV = _key1 ;               

27.            MemoryStream ms = new MemoryStream();   
28.            CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);   
29.            cs.Write(inputByteArray, 0, inputByteArray.Length);   
30.            cs.FlushFinalBlock();   
31.            byte[] cipherBytes = ms .ToArray () ;//得到加密后的字节数组   
32.            cs.Close();   
33.            ms.Close();   
34.            return cipherBytes ;               
35.        }   
36.           
37.        /// <summary>   
38.        /// AES解密   
39.        /// </summary>   
40.        /// <param name="cipherText">密文字节数组</param>   
41.        /// <param name="strKey">密钥</param>   
42.        /// <returns>返回解密后的字符串</returns>   
43.        public static byte[] AESDecrypt(byte[] cipherText , string strKey )   
44.        {              
45.            SymmetricAlgorithm des = Rijndael .Create () ;                             
46.            des.Key =Encoding.UTF8.GetBytes (strKey );   
47.            des.IV = _key1 ;   
48.            byte[] decryptBytes = new byte[cipherText .Length ] ;              
49.            MemoryStream ms = new MemoryStream(cipherText ) ;   
50.            CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor (), CryptoStreamMode.Read );   
51.            cs.Read (decryptBytes , 0, decryptBytes.Length);               
52.            cs.Close();   
53.            ms.Close();            
54.            return decryptBytes ;   
55.        }   
56.}