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