/* This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 *
 * http://www.gnu.org/copyleft/gpl.html
 */
package com.festina.gameserver;

/**
 *
 * @author  KenM
 */
public class GameCrypt
{
    private final byte[] _inKey = new byte[16];
    private final byte[] _outKey = new byte[16];
    private boolean _isEnabled;

    public void setKey(byte[] key)
    {
        System.arraycopy(key, 0, _inKey, 0, 16);
        System.arraycopy(key, 0, _outKey, 0, 16);
    }

    public void decrypt(byte[] raw, final int offset, final int size)
    {
        if (!_isEnabled)
            return;

            int temp = 0;
            for (int i = 0; i < size; i++)
            {
                int temp2 = raw[offset+i] & 0xFF;
                raw[offset+i] = (byte) (temp2 ^ _inKey[i&15] ^ temp);
                temp = temp2;
            }

            int old = _inKey[8] &0xff;
            old |= _inKey[9] << 8 &0xff00;
            old |= _inKey[10] << 0x10 &0xff0000;
            old |= _inKey[11] << 0x18 &0xff000000;

            old += size;

            _inKey[8] = (byte)(old &0xff);
            _inKey[9] = (byte)(old >> 0x08 &0xff);
            _inKey[10] = (byte)(old >> 0x10 &0xff);
            _inKey[11] = (byte)(old >> 0x18 &0xff);
    }

    public void encrypt(byte[] raw, final int offset, final int size)
    {
        if (!_isEnabled)
        {
            _isEnabled = true;
            return;
        }

        int temp = 0;
        for (int i = 0; i < size; i++)
        {
            int temp2 = raw[offset+i] & 0xFF;
            temp = temp2 ^ _outKey[i&15] ^ temp;
            raw[offset+i] = (byte) temp;
        }

        int old = _outKey[8] &0xff;
        old |= _outKey[9] << 8 &0xff00;
        old |= _outKey[10] << 0x10 &0xff0000;
        old |= _outKey[11] << 0x18 &0xff000000;

        old += size;

        _outKey[8] = (byte)(old &0xff);
        _outKey[9] = (byte)(old >> 0x08 &0xff);
        _outKey[10] = (byte)(old >> 0x10 &0xff);
        _outKey[11] = (byte)(old >> 0x18 &0xff);
    }

    /**
     * Marshal an integer to a byte array.
     * The bytes are in BIGENDIAN order.
     * i.e. array[offset] is the most-significant-byte
     * and  array[offset+3] is the least-significant-byte.
     *
     * @param array  The array of bytes.
     * @param offset The offset from which to start marshalling.
     */
    public static void intToBytes(int value, byte[] array, int offset)
    {
        array[offset++] = (byte) (value & 0xff);
        array[offset++] = (byte) (value >> 0x08 & 0xff);
        array[offset++] = (byte) (value >> 0x10 & 0xff);
        array[offset++] = (byte) (value >> 0x18 & 0xff);

    }
}

 