/* * Copyright (c) 1997, 2009, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package com.sun.crypto.provider; import java.security.SecureRandom;import java.security.InvalidParameterException;import java.security.InvalidAlgorithmParameterException;import java.security.InvalidKeyException;import java.security.spec.AlgorithmParameterSpec;import javax.crypto.KeyGeneratorSpi;import javax.crypto.SecretKey;import javax.crypto.spec.DESKeySpec; /** * This class generates a DES key. * * @author Jan Luehe * */ public final class DESKeyGenerator extends KeyGeneratorSpi {     private SecureRandom random = null;     /**     * Empty constructor     */    public DESKeyGenerator() {    }     /**     * Initializes this key generator.     *     * @param random the source of randomness for this generator     */    protected void engineInit(SecureRandom random) {        this.random = random;    }     /**     * Initializes this key generator with the specified parameter     * set and a user-provided source of randomness.     *     * @param params the key generation parameters     * @param random the source of randomness for this key generator     *     * @exception InvalidAlgorithmParameterException if <code>params</code> is     * inappropriate for this key generator     */    protected void engineInit(AlgorithmParameterSpec params,                              SecureRandom random)        throws InvalidAlgorithmParameterException {            throw new InvalidAlgorithmParameterException                ("DES key generation does not take any parameters");    }     /**     * Initializes this key generator for a certain keysize, using the given     * source of randomness.     *     * @param keysize the keysize. This is an algorithm-specific     * metric specified in number of bits.     * @param random the source of randomness for this key generator     */    protected void engineInit(int keysize, SecureRandom random) {        if (keysize != 56) {            throw new InvalidParameterException("Wrong keysize: must "                                                + "be equal to 56");        }        this.engineInit(random);    }     /**     * Generates the DES key.     *     * @return the new DES key     */    protected SecretKey engineGenerateKey() {        DESKey desKey = null;         if (this.random == null) {            this.random = SunJCE.RANDOM;        }         try {            byte[] key = new byte[DESKeySpec.DES_KEY_LEN];            do {                this.random.nextBytes(key);                setParityBit(key, 0);            } while (DESKeySpec.isWeak(key, 0));            desKey = new DESKey(key);        } catch (InvalidKeyException e) {            // this is never thrown        }         return desKey;    }     /*     * Does parity adjustment, using bit in position 8 as the parity bit,     * for 8 key bytes, starting at <code>offset</code>.     *     * The 8 parity bits of a DES key are only used for sanity-checking     * of the key, to see if the key could actually be a key. If you check     * the parity of the quantity, and it winds up not having the correct     * parity, then you'll know something went wrong.     *     * A key that is not parity adjusted (e.g. e4e4e4e4e4e4e4e4) produces the     * same output as a key that is parity adjusted (e.g. e5e5e5e5e5e5e5e5),     * because it is the 56 bits of the DES key that are cryptographically     * significant/"effective" -- the other 8 bits are just used for parity     * checking.     */    static void setParityBit(byte[] key, int offset) {        if (key == null)            return;         for (int i = 0; i < DESKeySpec.DES_KEY_LEN; i++) {            int b = key[offset] & 0xfe;            b |= (Integer.bitCount(b) & 1) ^ 1;            key[offset++] = (byte)b;        }    }}