import java.io.FilterOutputStream;

import java.io.IOException;

import java.io.OutputStream;

import java.io.FileOutputStream;

import java.io.FileInputStream;

import java.util.Random;

class ScrambledOutputStream extends FilterOutputStream{

private int[] map;

public ScrambledOutputStream(OutputStream out, int[] map){

super(out);

if(map==null || map.length!=256){

throw new IllegalArgumentException("map need contain 256 elements exactly.");

}

this.map = map;

}

@Override

public void write(int b) throws IOException{

// implementing trivial encryption, true value used as index. The map's role is key, so we need store it or retrive the identical one.

// The result looks having no relation with the source, haha.

out.write(map[b]);

// filed out is protected, so you can access it here.

}

}

public class Scramble{

public static final int RANDOM_SEED = 0;

public static void main(String[] args){

if(args.length != 2){

System.err.println("usage: java Scramble srcpath destpath");

return;

}

FileInputStream fis = null;

ScrambledOutputStream sos = null;

try{

fis = new FileInputStream(args[0]);

FileOutputStream fos = new FileOutputStream(args[1]);

sos = new ScrambledOutputStream(fos, makeMap());

int b;

while((b=fis.read())!=-1){

sos.write(b);

}

}catch(IOException ioe){

ioe.printStackTrace();

}finally{

if(fis!=null){

try{

fis.close();

}catch(IOException ioe){

ioe.printStackTrace();

}

}

if(sos!=null){

try{

sos.close();

}catch(IOException ioe){

ioe.printStackTrace();

}

}

}

}

static int[] makeMap(){

int[] map = new int[256];

for(int i=0;i<map.length;i++){

map[i] = i;

}

// shuffle the map

Random random = new Random(RANDOM_SEED);

// Specified seed intentionally to retrive the identical map when operating decryption.

for(int i=0;i<map.length;i++){

int index = random.nextInt(map.length);

if(index!=i){

int temp = map[index];

map[index] = map[i];

map[i] = temp;

}

}

return map;

}

}