Decryptor.java

// Near Infinity - An Infinity Engine Browser and Editor
// Copyright (C) 2001 - 2005 Jon Olav Hauglid
// See LICENSE.txt for license information

package org.infinity.util;

import java.nio.ByteBuffer;

import org.infinity.util.io.StreamUtils;

public final class Decryptor
{
  private static final char[] key = {
    0x88, 0xa8, 0x8f, 0xba, 0x8a, 0xd3, 0xb9, 0xf5, 0xed, 0xb1, 0xcf, 0xea, 0xaa,
    0xe4, 0xb5, 0xfb, 0xeb, 0x82, 0xf9, 0x90, 0xca, 0xc9, 0xb5, 0xe7, 0xdc, 0x8e,
    0xb7, 0xac, 0xee, 0xf7, 0xe0, 0xca, 0x8e, 0xea, 0xca, 0x80, 0xce, 0xc5, 0xad,
    0xb7, 0xc4, 0xd0, 0x84, 0x93, 0xd5, 0xf0, 0xeb, 0xc8, 0xb4, 0x9d, 0xcc, 0xaf,
    0xa5, 0x95, 0xba, 0x99, 0x87, 0xd2, 0x9d, 0xe3, 0x91, 0xba, 0x90, 0xca
  };

  public static ByteBuffer decrypt(ByteBuffer buffer, int offset)
  {
    int decOff = 0;
    int size = buffer.limit() - buffer.position();
    ByteBuffer outBuffer = StreamUtils.getByteBuffer(size);
    for (int i = offset, len = buffer.limit(); i < len; i++) {
      outBuffer.put((byte)(256 + buffer.get(i) ^ key[decOff]));
      decOff = (decOff + 1) % key.length;
    }
    outBuffer.position(0);
    return outBuffer;
  }

  private Decryptor(){}
}