/*

 * Copyright (c) 1997, 2013, 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 javax.crypto.KeyGeneratorSpi;

import javax.crypto.SecretKey;

import javax.crypto.spec.DESedeKeySpec;

import java.security.SecureRandom;

import java.security.InvalidParameterException;

import java.security.InvalidAlgorithmParameterException;

import java.security.InvalidKeyException;

import java.security.spec.AlgorithmParameterSpec;

/**

 * This class generates a Triple DES key.

 *

 * @author Jan Luehe

 *

 */

public final class DESedeKeyGenerator extends KeyGeneratorSpi {

    private SecureRandom random = null;

    private int keysize = 168;

    /**

     * Empty constructor

     */

    public DESedeKeyGenerator() {

    }

    /**

     * 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

                ("Triple 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. A keysize with 112 bits of entropy

     * corresponds to a Triple DES key with 2 intermediate keys, and a keysize

     * with 168 bits of entropy corresponds to a Triple DES key with 3

     * intermediate keys.

     * @param random the source of randomness for this key generator

     */

    protected void engineInit(int keysize, SecureRandom random) {

        if ((keysize != 112) && (keysize != 168)) {

            throw new InvalidParameterException("Wrong keysize: must be "

                                                + "equal to 112 or 168");

        }

        this.keysize = keysize;

        this.engineInit(random);

    }

    /**

     * Generates the Triple DES key.

     *

     * @return the new Triple DES key

     */

    protected SecretKey engineGenerateKey() {

        if (this.random == null) {

            this.random = SunJCE.getRandom();

        }

        byte[] rawkey = new byte[DESedeKeySpec.DES_EDE_KEY_LEN];

        if (keysize == 168) {

            // 3 intermediate keys

            this.random.nextBytes(rawkey);

            // Do parity adjustment for each intermediate key

            DESKeyGenerator.setParityBit(rawkey, 0);

            DESKeyGenerator.setParityBit(rawkey, 8);

            DESKeyGenerator.setParityBit(rawkey, 16);

        } else {

            // 2 intermediate keys

            byte[] tmpkey = new byte[16];

            this.random.nextBytes(tmpkey);

            DESKeyGenerator.setParityBit(tmpkey, 0);

            DESKeyGenerator.setParityBit(tmpkey, 8);

            System.arraycopy(tmpkey, 0, rawkey, 0, tmpkey.length);

            // Copy the first 8 bytes into the last

            System.arraycopy(tmpkey, 0, rawkey, 16, 8);

            java.util.Arrays.fill(tmpkey, (byte)0x00);

        }

        DESedeKey desEdeKey = null;

        try {

            desEdeKey = new DESedeKey(rawkey);

        } catch (InvalidKeyException ike) {

            // this never happens

            throw new RuntimeException(ike.getMessage());

        }

        java.util.Arrays.fill(rawkey, (byte)0x00);

        return desEdeKey;

    }

}