/*

 * Copyright (c) 2005, 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.AlgorithmParameterSpec;

import static com.sun.crypto.provider.TlsPrfGenerator.genPad;

/**

 * This file contains the code for the SslMacMD5 and SslMacSHA1 implementations.

 * The SSL 3.0 MAC is a variation of the HMAC algorithm.

 *

 * Note that we don't implement Cloneable as that is not needed for SSL.

 *

 * @author  Andreas Sterbenz

 * @since   1.6

 */

final class SslMacCore {

    private final MessageDigest md;

    private final byte[] pad1, pad2;

    private boolean first;       // Is this the first data to be processed?

    private byte[] secret;

    /**

     * Standard constructor, creates a new SslMacCore instance instantiating

     * a MessageDigest of the specified name.

     */

    SslMacCore(String digestAlgorithm, byte[] pad1, byte[] pad2)

            throws NoSuchAlgorithmException {

        md = MessageDigest.getInstance(digestAlgorithm);

        this.pad1 = pad1;

        this.pad2 = pad2;

        first = true;

    }

    /**

     * Returns the length of the Mac in bytes.

     *

     * @return the Mac length in bytes.

     */

    int getDigestLength() {

        return md.getDigestLength();

    }

    /**

     * Initializes the Mac 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.

     */

    void init(Key key, AlgorithmParameterSpec params)

            throws InvalidKeyException, InvalidAlgorithmParameterException {

        if (params != null) {

            throw new InvalidAlgorithmParameterException

                ("SslMac does not use parameters");

        }

        if (!(key instanceof SecretKey)) {

            throw new InvalidKeyException("Secret key expected");

        }

        secret = key.getEncoded();

        if (secret == null || secret.length == 0) {

            throw new InvalidKeyException("Missing key data");

        }

        reset();

    }

    /**

     * Processes the given byte.

     *

     * @param input the input byte to be processed.

     */

    void update(byte input) {

        if (first == true) {

            // compute digest for 1st pass; start with inner pad

            md.update(secret);

            md.update(pad1);

            first = false;

        }

        // add the passed byte to the inner digest

        md.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.

     */

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

        if (first == true) {

            // compute digest for 1st pass; start with inner pad

            md.update(secret);

            md.update(pad1);

            first = false;

        }

        // add the selected part of an array of bytes to the inner digest

        md.update(input, offset, len);

    }

    void update(ByteBuffer input) {

        if (first == true) {

            // compute digest for 1st pass; start with inner pad

            md.update(secret);

            md.update(pad1);

            first = false;

        }

        md.update(input);

    }

    /**

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

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

     *

     * @return the Mac result.

     */

    byte[] doFinal() {

        if (first == true) {

            // compute digest for 1st pass; start with inner pad

            md.update(secret);

            md.update(pad1);

        } else {

            first = true;

        }

        try {

            // finish the inner digest

            byte[] tmp = md.digest();

            // compute digest for 2nd pass; start with outer pad

            md.update(secret);

            md.update(pad2);

            // add result of 1st hash

            md.update(tmp);

            md.digest(tmp, 0, tmp.length);

            return tmp;

        } catch (DigestException e) {

            // should never occur

            throw new ProviderException(e);

        }

    }

    /**

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

     * Mac was initialized with.

     */

    void reset() {

        if (first == false) {

            md.reset();

            first = true;

        }

    }

    // nested static class for the SslMacMD5 implementation

    public static final class SslMacMD5 extends MacSpi {

        private final SslMacCore core;

        public SslMacMD5() throws NoSuchAlgorithmException {

            core = new SslMacCore("MD5", md5Pad1, md5Pad2);

        }

        protected int engineGetMacLength() {

            return core.getDigestLength();

        }

        protected void engineInit(Key key, AlgorithmParameterSpec params)

                throws InvalidKeyException, InvalidAlgorithmParameterException {

            core.init(key, params);

        }

        protected void engineUpdate(byte input) {

            core.update(input);

        }

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

            core.update(input, offset, len);

        }

        protected void engineUpdate(ByteBuffer input) {

            core.update(input);

        }

        protected byte[] engineDoFinal() {

            return core.doFinal();

        }

        protected void engineReset() {

            core.reset();

        }

        static final byte[] md5Pad1 = genPad((byte)0x36, 48);

        static final byte[] md5Pad2 = genPad((byte)0x5c, 48);

    }

    // nested static class for the SslMacMD5 implementation

    public static final class SslMacSHA1 extends MacSpi {

        private final SslMacCore core;

        public SslMacSHA1() throws NoSuchAlgorithmException {

            core = new SslMacCore("SHA", shaPad1, shaPad2);

        }

        protected int engineGetMacLength() {

            return core.getDigestLength();

        }

        protected void engineInit(Key key, AlgorithmParameterSpec params)

                throws InvalidKeyException, InvalidAlgorithmParameterException {

            core.init(key, params);

        }

        protected void engineUpdate(byte input) {

            core.update(input);

        }

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

            core.update(input, offset, len);

        }

        protected void engineUpdate(ByteBuffer input) {

            core.update(input);

        }

        protected byte[] engineDoFinal() {

            return core.doFinal();

        }

        protected void engineReset() {

            core.reset();

        }

        static final byte[] shaPad1 = genPad((byte)0x36, 40);

        static final byte[] shaPad2 = genPad((byte)0x5c, 40);

    }

}