package nu.fw.jeti.applet;

import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

/* 
 *	@author Serge Rehem
 *	Jeti, a Java Jabber client, Copyright (C) 2003 E.S. de Boer  
 *
 *  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 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, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *	For questions, comments etc, 
 *	use the website at http://jeti.jabberstudio.org
 *  or jabber/mail me at jeti@jabber.org
 *
 *	Created on 14-nov-2003
 */

/*
 *  This code is based on AES Interop Between PHP and Java (Part 1) post at  
 *  http://propaso.com/blog/?cat=6                                           
 */
public class Crypto {

	public static String decrypt(String cryptedPasswd, String secretKey) {
		Cipher cipher;
		try {
			cipher = Cipher.getInstance("AES/CBC/NoPadding");
			SecretKeySpec keySpec = new SecretKeySpec(secretKey.getBytes(), "AES");

			IvParameterSpec ivSpec = new IvParameterSpec("@4321avaJtluafeD".getBytes());
			
			cipher.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);
			byte[] outText = cipher.doFinal(hexToBytes(cryptedPasswd));
			return new String(outText).trim();
		} catch (Exception e) {
			e.printStackTrace();
			return null;
		}
	}

	private static byte[] hexToBytes(String str) {
		if (str == null) {
			return null;
		} else if (str.length() < 2) {
			return null;
		} else {
			int len = str.length() / 2;
			byte[] buffer = new byte[len];
			for (int i = 0; i < len; i++) {
				buffer[i] = (byte) Integer.parseInt(str.substring(i * 2,
						i * 2 + 2), 16);
			}
			return buffer;
		}
	}
}