对称加密的例子（DES）——针对文件进行加解密

这是是今天课堂上的例子。针对文件的加解密其实与字符串加解密没有大的差别。

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 fileName = "demo.txt";
EncryptFile(fileName, des.Key, des.IV);
DecryptFile(fileName+".des", des.Key, des.IV);

Console.Read();

}

private static void DecryptFile(string fileName, byte[] key, byte[] iv)
{
FileStream input = new FileStream(fileName, FileMode.Open);
FileStream output = new FileStream(fileName + ".txt", FileMode.Create);

DES des = DES.Create();
CryptoStream stream = new CryptoStream(input, des.CreateDecryptor(key, iv), CryptoStreamMode.Read);
byte[] buffer = new byte[input.Length];
stream.Read(buffer, 0, buffer.Length);
stream.Close();
input.Close();

output.Write(buffer, 0, buffer.Length);
output.Close();
}

private static void EncryptFile(string fileName, byte[] key, byte[] iv)
{
FileStream input = new FileStream(fileName, FileMode.Open);
FileStream output = new FileStream(fileName + ".des", FileMode.Create);

DES des = DES.Create();
CryptoStream stream = new CryptoStream(output, des.CreateEncryptor(key, iv), CryptoStreamMode.Write);

byte[] buffer = new byte[input.Length];
input.Read(buffer, 0, buffer.Length);
input.Close();
stream.Write(buffer, 0, buffer.Length);
stream.FlushFinalBlock();
stream.Close();
output.Close();

}

加密之前的文件

加密之后的文件

解密之后的文件

.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; }