/*

 * Copyright (c) 1997, 2011, 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 javax.crypto.spec;

import java.security.InvalidKeyException;

/**

 * This class specifies a DES-EDE ("triple-DES") key.

 *

 * @author Jan Luehe

 *

 * @since 1.4

 */

public class DESedeKeySpec implements java.security.spec.KeySpec {

    /**

     * The constant which defines the length of a DESede key in bytes.

     */

    public static final int DES_EDE_KEY_LEN = 24;

    private byte[] key;

    /**

     * Creates a DESedeKeySpec object using the first 24 bytes in

     * <code>key</code> as the key material for the DES-EDE key.

     *

     * <p> The bytes that constitute the DES-EDE key are those between

     * <code>key[0]</code> and <code>key[23]</code> inclusive

     *

     * @param key the buffer with the DES-EDE key material. The first

     * 24 bytes of the buffer are copied to protect against subsequent

     * modification.

     *

     * @exception NullPointerException if <code>key</code> is null.

     * @exception InvalidKeyException if the given key material is shorter

     * than 24 bytes.

     */

    public DESedeKeySpec(byte[] key) throws InvalidKeyException {

        this(key, 0);

    }

    /**

     * Creates a DESedeKeySpec object using the first 24 bytes in

     * <code>key</code>, beginning at <code>offset</code> inclusive,

     * as the key material for the DES-EDE key.

     *

     * <p> The bytes that constitute the DES-EDE key are those between

     * <code>key[offset]</code> and <code>key[offset+23]</code> inclusive.

     *

     * @param key the buffer with the DES-EDE key material. The first

     * 24 bytes of the buffer beginning at <code>offset</code> inclusive

     * are copied to protect against subsequent modification.

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

     * material starts.

     *

     * @exception NullPointerException if <code>key</code> is null.

     * @exception InvalidKeyException if the given key material, starting at

     * <code>offset</code> inclusive, is shorter than 24 bytes

     */

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

        if (key.length - offset < 24) {

            throw new InvalidKeyException("Wrong key size");

        }

        this.key = new byte[24];

        System.arraycopy(key, offset, this.key, 0, 24);

    }

    /**

     * Returns the DES-EDE key.

     *

     * @return the DES-EDE key. Returns a new array

     * each time this method is called.

     */

    public byte[] getKey() {

        return this.key.clone();

    }

    /**

     * Checks if the given DES-EDE key, starting at <code>offset</code>

     * inclusive, is parity-adjusted.

     *

     * @param key    a byte array which holds the key value

     * @param offset the offset into the byte array

     * @return true if the given DES-EDE key is parity-adjusted, false

     * otherwise

     *

     * @exception NullPointerException if <code>key</code> is null.

     * @exception InvalidKeyException if the given key material, starting at

     * <code>offset</code> inclusive, is shorter than 24 bytes

     */

    public static boolean isParityAdjusted(byte[] key, int offset)

        throws InvalidKeyException {

            if (key.length - offset < 24) {

                throw new InvalidKeyException("Wrong key size");

            }

            if (DESKeySpec.isParityAdjusted(key, offset) == false

                || DESKeySpec.isParityAdjusted(key, offset + 8) == false

                || DESKeySpec.isParityAdjusted(key, offset + 16) == false) {

                return false;

            }

            return true;

    }

}