位与加密方式的实现

位与加密方式的速度非常快。若能保证其私有密钥的安全性,则位与加密的安全性很高，要破译几乎是不可能的。

但是位与加密的缺陷是灵活性较差,对私有密钥的管理是个头疼的问题。

在只需要简单粗暴的加密方式的环境下，这是个不错的选择。

 

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Arrays;

public class Encryptor {

    public static byte[] encrypt(byte[] content, byte[] key) {
        if (key.length == 0)
            throw new IllegalArgumentException("key can not be empty!");
        byte[] copy = Arrays.copyOf(content, content.length);
        encrypt1(copy, key, 0);
        return copy;
    }

    private static void encrypt1(byte[] content, byte[] key, int start) {
        if (start == content.length)
            return;// 递归结束条件
        int end = start + key.length;
        if (end >= content.length)
            end = content.length;
        for (int i = start; i < end; i++) {
            content[i] ^= key[i - start];
        }
        encrypt1(content, key, end);
    }

    public static byte[] decrypt(byte[] content, byte[] key) {
        // 异或的解密等于加密
        return encrypt(content, key);
    }

    public static void encryptFile(File file, File output, byte[] privateKey)
            throws IOException {
        if(output.getParentFile()!=null)
            output.getParentFile().mkdirs();
        FileInputStream fis = new FileInputStream(file);
        FileOutputStream fos = new FileOutputStream(output);
        byte[] buffer = new byte[8192];
        int realSize = -1;
        try {
            while ((realSize = fis.read(buffer)) != -1) {
                byte[] encrypted = encrypt(buffer, privateKey);
                fos.write(encrypted,0,realSize);
            }
        }
        finally {
            fos.close();
            fis.close();
        }
    }

    public static void decryptFile(File file, File output, byte[] privateKey)
            throws IOException {
        encryptFile(file, output, privateKey);
    }

    public static void main(String[] args) throws Exception {
        byte[] key = "kiss".getBytes();
        byte[] content = "dddefr12345adkfjsadfjladskfj".getBytes();
        byte[] test = encrypt(content, key);
        System.out.println(new String(test));
        test = decrypt(test, key);
        System.out.println(new String(test));
//        encryptFile(new File("test"), new File("test2"), key);
//        decryptFile(new File("test2"), new File("test3"), key);
    }
}

 

小弟潜水好久~出来透个气。呼呼