这是在课堂上讲解的一个例子，最简单的对称算法，DES
关于该算法的一些说明，有兴趣的朋友可以参考下面的链接
http://baike.baidu.com/view/7510.htm
static void Main(string[] args)
{
DES des = DES.Create();
des.Key = Convert.FromBase64String("12345678910=");
des.IV = Convert.FromBase64String("12345678910=");
//DES的算法密钥和向量必须是12位，而且最后一位必须的=
//而且必须用FromBase64String的方式获取
string original = "Hello,world";
byte[] data = EncryptText(original, des.Key, des.IV);//加密
string result = DecryptText(data, des.Key, des.IV);//解密
Console.WriteLine(result);
Console.Read();
}
private static string DecryptText(byte[] data, byte[] key, byte[] iv)
{
MemoryStream ms = new MemoryStream(data);
DES des = DES.Create();
CryptoStream stream = new CryptoStream(ms, des.CreateDecryptor(key, iv), CryptoStreamMode.Read);
byte[] from = new byte[data.Length];
stream.Read(from, 0, from.Length);
return Encoding.ASCII.GetString(from);
}
private static byte[] EncryptText(string original, byte[] key, byte[] iv)
{
MemoryStream ms = new MemoryStream();//用来接收密文的内存流
DES des = DES.Create();
CryptoStream stream = new CryptoStream(ms, des.CreateEncryptor(key, iv), CryptoStreamMode.Write);
//创建加密流
byte[] to = Encoding.ASCII.GetBytes(original);//获取输入的字符串的字节
stream.Write(to, 0, to.Length);//写入加密流
stream.FlushFinalBlock();//写入内存流，并清空缓冲区
byte[] ret = ms.ToArray();
stream.Close();
ms.Close();
return ret;
}
