/*

 * Copyright (c) 1997, 2007, 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.KeyRep;

import java.security.InvalidKeyException;

import javax.crypto.SecretKey;

import javax.crypto.spec.DESKeySpec;

/**

 * This class represents a DES key.

 *

 * @author Jan Luehe

 *

 */

final class DESKey implements SecretKey {

    static final long serialVersionUID = 7724971015953279128L;

    private byte[] key;

    /**

     * Uses the first 8 bytes of the given key as the DES key.

     *

     * @param key the buffer with the DES key bytes.

     *

     * @exception InvalidKeyException if less than 8 bytes are available for

     * the key.

     */

    DESKey(byte[] key) throws InvalidKeyException {

        this(key, 0);

    }

    /**

     * Uses the first 8 bytes in <code>key</code>, beginning at

     * <code>offset</code>, as the DES key

     *

     * @param key the buffer with the DES key bytes.

     * @param offset the offset in <code>key</code>, where the DES key bytes

     * start.

     *

     * @exception InvalidKeyException if less than 8 bytes are available for

     * the key.

     */

    DESKey(byte[] key, int offset) throws InvalidKeyException {

        if (key == null || key.length - offset < DESKeySpec.DES_KEY_LEN) {

            throw new InvalidKeyException("Wrong key size");

        }

        this.key = new byte[DESKeySpec.DES_KEY_LEN];

        System.arraycopy(key, offset, this.key, 0, DESKeySpec.DES_KEY_LEN);

        DESKeyGenerator.setParityBit(this.key, 0);

    }

    public byte[] getEncoded() {

        // Return a copy of the key, rather than a reference,

        // so that the key data cannot be modified from outside

        return (byte[])this.key.clone();

    }

    public String getAlgorithm() {

        return "DES";

    }

    public String getFormat() {

        return "RAW";

    }

    /**

     * Calculates a hash code value for the object.

     * Objects that are equal will also have the same hashcode.

     */

    public int hashCode() {

        int retval = 0;

        for (int i = 1; i < this.key.length; i++) {

            retval += this.key[i] * i;

        }

        return(retval ^= "des".hashCode());

    }

    public boolean equals(Object obj) {

        if (this == obj)

            return true;

        if (!(obj instanceof SecretKey))

            return false;

        String thatAlg = ((SecretKey)obj).getAlgorithm();

        if (!(thatAlg.equalsIgnoreCase("DES")))

            return false;

        byte[] thatKey = ((SecretKey)obj).getEncoded();

        boolean ret = java.util.Arrays.equals(this.key, thatKey);

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

        return ret;

    }

    /**

     * readObject is called to restore the state of this key from

     * a stream.

     */

    private void readObject(java.io.ObjectInputStream s)

         throws java.io.IOException, ClassNotFoundException

    {

        s.defaultReadObject();

        key = (byte[])key.clone();

    }

    /**

     * Replace the DES key to be serialized.

     *

     * @return the standard KeyRep object to be serialized

     *

     * @throws java.io.ObjectStreamException if a new object representing

     * this DES key could not be created

     */

    private Object writeReplace() throws java.io.ObjectStreamException {

        return new KeyRep(KeyRep.Type.SECRET,

                        getAlgorithm(),

                        getFormat(),

                        getEncoded());

    }

    /**

     * Ensures that the bytes of this key are

     * set to zero when there are no more references to it.

     */

    protected void finalize() throws Throwable {

        try {

            if (this.key != null) {

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

                this.key = null;

            }

        } finally {

            super.finalize();

        }

    }

}