/*

 * Copyright (c) 1998, 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

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 */

package com.sun.crypto.provider;

import java.nio.ByteBuffer;

import javax.crypto.MacSpi;

import javax.crypto.SecretKey;

import java.security.*;

import java.security.spec.*;

/**

 * This is an implementation of the HMAC-MD5 algorithm.

 *

 * @author Jan Luehe

 */

public final class HmacMD5 extends MacSpi implements Cloneable {

    private HmacCore hmac;

    private static final int MD5_BLOCK_LENGTH = 64;

    /**

     * Standard constructor, creates a new HmacMD5 instance.

     */

    public HmacMD5() throws NoSuchAlgorithmException {

        hmac = new HmacCore(MessageDigest.getInstance("MD5"),

                            MD5_BLOCK_LENGTH);

    }

    /**

     * Returns the length of the HMAC in bytes.

     *

     * @return the HMAC length in bytes.

     */

    protected int engineGetMacLength() {

        return hmac.getDigestLength();

    }

    /**

     * Initializes the HMAC with the given secret key and algorithm parameters.

     *

     * @param key the secret key.

     * @param params the algorithm parameters.

     *

     * @exception InvalidKeyException if the given key is inappropriate for

     * initializing this MAC.

     * @exception InvalidAlgorithmParameterException if the given algorithm

     * parameters are inappropriate for this MAC.

     */

    protected void engineInit(Key key, AlgorithmParameterSpec params)

        throws InvalidKeyException, InvalidAlgorithmParameterException {

        hmac.init(key, params);

    }

    /**

     * Processes the given byte.

     *

     * @param input the input byte to be processed.

     */

    protected void engineUpdate(byte input) {

        hmac.update(input);

    }

    /**

     * Processes the first <code>len</code> bytes in <code>input</code>,

     * starting at <code>offset</code>.

     *

     * @param input the input buffer.

     * @param offset the offset in <code>input</code> where the input starts.

     * @param len the number of bytes to process.

     */

    protected void engineUpdate(byte input[], int offset, int len) {

        hmac.update(input, offset, len);

    }

    protected void engineUpdate(ByteBuffer input) {

        hmac.update(input);

    }

    /**

     * Completes the HMAC computation and resets the HMAC for further use,

     * maintaining the secret key that the HMAC was initialized with.

     *

     * @return the HMAC result.

     */

    protected byte[] engineDoFinal() {

        return hmac.doFinal();

    }

    /**

     * Resets the HMAC for further use, maintaining the secret key that the

     * HMAC was initialized with.

     */

    protected void engineReset() {

        hmac.reset();

    }

    /*

     * Clones this object.

     */

    public Object clone() {

        HmacMD5 that = null;

        try {

            that = (HmacMD5) super.clone();

            that.hmac = (HmacCore) this.hmac.clone();

        } catch (CloneNotSupportedException e) {

        }

        return that;

    }

}