Banana-Coding.com - Java Knuddels Emulator

Java-Quelltext

package eu.knuddelz.net.Security;

import java.io.IOException;
import java.io.InputStream;


public class Protocol {
	public static byte[] decode(InputStream in, byte[] decodeKey) throws IOException {
    	byte first = (byte) in.read();

    	if (first == -1) {
        	throw new IOException("End of stream");
    	}
    	byte second = (byte)in.read();
    	byte third = (byte)in.read();
    	byte fourth = (byte)in.read();
    	int length=(first<<24)|(second<<16)|(third << 8)|fourth;
    	byte[] buffer = new byte[length];
    	
    	
        	for (int i = 0; i < length; i++) {
            	byte byter = (byte) in.read();
            	if(decodeKey!=null) {
                	byter = (byte)(byter^(decodeKey[(i%(decodeKey.length))]));
            	}
            	buffer[i] = byter;
        	}
    	return buffer;
	}

	public static byte[] encode(byte[] message, byte[] encodeKey) {
    	int length = message.length;
    	byte first = (byte)(length>>24);
    	byte second = (byte)(length>>16);
    	byte third = (byte)(length>>8);
    	byte fourth = (byte)(length>>0);
    	byte[] len = { first, second, third, fourth };
    	
    	for(int i = 0; i < message.length; i++) {
        	if(encodeKey!=null) {
            	message[i] = (byte)(message[i] ^ (encodeKey[(i%(encodeKey.length))]));
        	}
    	}
    	

    	byte[] buffer = new byte[len.length + message.length];
    	System.arraycopy(len, 0, buffer, 0, len.length);
    	System.arraycopy(message, 0, buffer, len.length, message.length);
    	return buffer;
	}
}