对称加密的例子（DES）——直接加密和解密字符串

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;

}

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }