C#编程之AES加密（二）

上一章我们举例了官方给出的一个AES加密例程，我们从官方的例程可以看出，这例程对文档类型的文件进行加密是比较合适的。

但有时候，我们需要对一小段数据进行加密，例如通过序列号加密生成产品加密后的序列号，用于遥控与主机间的RF通信，这就是纯粹的16进制数进行加密了。比如汽车遥控，家居遥控等等，这些产品序列号是对所有用户透明的，如果不进行加密，通信信息很容易被拦截。为解决这一问题，我们这里介绍一下aes128加密16字节序列号：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Security.Cryptography;

namespace aesDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            var keyBuf = "1111111111111111";
            var valueBuf = Encoding.UTF8.GetBytes("2222222222222222");
            using(var aes=new RijndaelManaged())
            {
                aes.IV = Encoding.UTF8.GetBytes(keyBuf);
                aes.Key = Encoding.UTF8.GetBytes(keyBuf);
                aes.Mode = CipherMode.ECB;
                aes.Padding = PaddingMode.None;
                var cryptoTransform = aes.CreateEncryptor();
                var resultBuff = cryptoTransform.TransformFinalBlock(valueBuf, 0, valueBuf.Length);
                Console.WriteLine(resultBuff.Length);
                foreach (byte i in resultBuff)
                    Console.WriteLine("{0:X2}", i);
            }
            Console.ReadLine();
        }
    }
}

编译运行：

我们校验一下我们的结果：

说明我们的算法没问题。下面我们简化一下:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Security.Cryptography;

namespace aesDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            byte[] plaintext = new byte[] { 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32 };
            using(var aes=new RijndaelManaged())
            {
                aes.IV = new byte[16];
                aes.Key = new byte[]{0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,};
                aes.Mode = CipherMode.ECB;
                aes.Padding = PaddingMode.None;
                var cryptoTransform = aes.CreateEncryptor();
                var resultBuff = cryptoTransform.TransformFinalBlock(plaintext, 0, plaintext.Length);
                foreach (byte i in resultBuff)
                    Console.WriteLine("{0:X2}", i);
            }
            Console.ReadLine();
        }
    }
}

这里有几个地方需要讲解一下的：

1.  using System.Security.Cryptography; 调用系统安全加密算法空间命名，对于这个官方给出的解释如下：namespace provides cryptographic services, including secure encoding and decoding of data, and many other operations, such as hashing, generation of random values, and authentication.
2. 创建 RijndaelManaged 类，通过这个类，我们可以配置加密参数；
3.  aes.Mode = CipherMode.ECB; 设置对称算法中填充的模式，这里因为我们填充参数设置为none（ aes.Padding = PaddingMode.None; ），所以该参数也可以不进行设置，或采用默认值CBC。
4. 填充默认是填充为32字节的，因为我们只需用到16字节，所以我们可以设置其值为不填充 aes.Padding = PaddingMode.None; 当然你不做处理也是可以的，因为只要你提取前面的16字节，而忽略后面的16字节就好了。

至此，对C# ase加密我们就讲解完了，当然C#加密方式还有很多种，这些都是包含在 System.Security.Cryptography; 中，有兴趣的，可以自行深入探讨。

 最后我们得到：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Security.Cryptography;

namespace aesDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            byte[] plaintext = new byte[] { 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32 };
            using(var aes=new RijndaelManaged())
            {
                aes.IV = new byte[16];
                aes.Key = new byte[]{0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,};
                aes.Mode = CipherMode.CBC;
                aes.Padding = PaddingMode.None;
                var cryptoTransform = aes.CreateEncryptor();
                var resultBuff = cryptoTransform.TransformFinalBlock(plaintext, 0, plaintext.Length);
                foreach (byte i in resultBuff)
                    Console.WriteLine("{0:X2}", i);
            }
            Console.ReadLine();
        }
    }
}

下面我们接着说一下如何解密：

我们知道加密需要创建加密实例 var cryptoTransform = aes.CreateEncryptor(); 同样，解密也是一样的： cryptoTransform = aes.CreateDecryptor(); 接着按部就班，直接将需要解密的密文传入解密函数运算即可：

resultBuff = cryptoTransform.TransformFinalBlock(resultBuff, 0, resultBuff.Length);

最后总结代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Security.Cryptography;

namespace aesDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            byte[] plaintext = new byte[] { 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32, 0x32 };
            using(var aes=new RijndaelManaged())
            {
                aes.IV = new byte[16];
                aes.Key = new byte[]{0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31,0x31};
                //aes.Mode = CipherMode.CBC;
                aes.Padding = PaddingMode.None;
                var cryptoTransform = aes.CreateEncryptor();
                byte[] resultBuff = cryptoTransform.TransformFinalBlock(plaintext, 0, plaintext.Length);
                foreach (byte i in resultBuff)
                    Console.Write("{0:X2}", i);
                Console.WriteLine();
                cryptoTransform = aes.CreateDecryptor();
                resultBuff = cryptoTransform.TransformFinalBlock(resultBuff, 0, resultBuff.Length);
                foreach (byte i in resultBuff)
                    Console.Write("{0:X2}", i);
            }
            Console.ReadLine();
        }
    }
}

 编译运行：

End.

谢谢.