/*
 * 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 3 of the License, 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, see <http://www.gnu.org/licenses/>.
 */
package silentium.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);
	}
}