001/*
002 * jPOS Project [http://jpos.org]
003 * Copyright (C) 2000-2026 jPOS Software SRL
004 *
005 * This program is free software: you can redistribute it and/or modify
006 * it under the terms of the GNU Affero General Public License as
007 * published by the Free Software Foundation, either version 3 of the
008 * License, or (at your option) any later version.
009 *
010 * This program is distributed in the hope that it will be useful,
011 * but WITHOUT ANY WARRANTY; without even the implied warranty of
012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
013 * GNU Affero General Public License for more details.
014 *
015 * You should have received a copy of the GNU Affero General Public License
016 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
017 */
018
019package  org.jpos.security;
020
021import java.util.Arrays;
022
023
024/**
025 * Util class contains some useful methods.
026 * @author Hani S. Kirollos
027 * @version $Revision$ $Date$
028 */
029public class Util {
030    /** Default constructor; no instance state to initialise. */
031    public Util() {}
032
033    /**
034     * DES Keys use the LSB as the odd parity bit.  This method can
035     * be used enforce correct parity.
036     *
037     * @param bytes the byte array to set the odd parity on.
038     */
039    public static void adjustDESParity (byte[] bytes) {
040        for (int i = 0; i < bytes.length; i++) {
041            int b = bytes[i];
042            bytes[i] = (byte)(b & 0xfe | (b >> 1 ^ b >> 2 ^ b >> 3 ^ b >> 4 ^ b >> 5 ^ b >> 6 ^ b >> 7 ^ 0x01) & 0x01);
043        }
044    }
045
046    /**
047     * DES Keys use the LSB as the odd parity bit.  This method checks
048     * whether the parity is adjusted or not
049     *
050     * @param bytes the byte[] to be checked
051     * @return true if parity is adjusted else returns false
052     */
053    public static boolean isDESParityAdjusted (byte[] bytes) {
054        byte[] correct = bytes.clone();
055        adjustDESParity(correct);
056        return  Arrays.equals(bytes, correct);
057    }
058}
059
060
061