/* 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 net.sf.l2j.gameserver.network;

/**
 *
 * @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);
	}
}
