/*
 * Copyright 2005-2007 Sun Microsystems, Inc.  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.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package com.sun.crypto.provider;

import java.security.*;
import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.*;

import sun.security.internal.interfaces.TlsMasterSecret;
import sun.security.internal.spec.TlsMasterSecretParameterSpec;

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

/**
 * KeyGenerator implementation for the SSL/TLS master secret derivation.
 *
 * @author  Andreas Sterbenz
 * @since   1.6
 */
public final class TlsMasterSecretGenerator extends KeyGeneratorSpi {

    private final static String MSG = "TlsMasterSecretGenerator must be "
        + "initialized using a TlsMasterSecretParameterSpec";

    private TlsMasterSecretParameterSpec spec;

    private int protocolVersion;

    public TlsMasterSecretGenerator() {
        SunJCE.ensureIntegrity(getClass());
    }

    protected void engineInit(SecureRandom random) {
        throw new InvalidParameterException(MSG);
    }

    protected void engineInit(AlgorithmParameterSpec params,
            SecureRandom random) throws InvalidAlgorithmParameterException {
        if (params instanceof TlsMasterSecretParameterSpec == false) {
            throw new InvalidAlgorithmParameterException(MSG);
        }
        this.spec = (TlsMasterSecretParameterSpec)params;
        if ("RAW".equals(spec.getPremasterSecret().getFormat()) == false) {
            throw new InvalidAlgorithmParameterException("Key format must be RAW");
        }
        protocolVersion = (spec.getMajorVersion() << 8) | spec.getMinorVersion();
        if ((protocolVersion < 0x0300) || (protocolVersion > 0x0302)) {
            throw new InvalidAlgorithmParameterException
                ("Only SSL 3.0, TLS 1.0, and TLS 1.1 supported");
        }
    }

    protected void engineInit(int keysize, SecureRandom random) {
        throw new InvalidParameterException(MSG);
    }

    protected SecretKey engineGenerateKey() {
        if (spec == null) {
            throw new IllegalStateException
                ("TlsMasterSecretGenerator must be initialized");
        }
        SecretKey premasterKey = spec.getPremasterSecret();
        byte[] premaster = premasterKey.getEncoded();

        int premasterMajor, premasterMinor;
        if (premasterKey.getAlgorithm().equals("TlsRsaPremasterSecret")) {
            // RSA
            premasterMajor = premaster[0] & 0xff;
            premasterMinor = premaster[1] & 0xff;
        } else {
            // DH, KRB5, others
            premasterMajor = -1;
            premasterMinor = -1;
        }

        try {
            byte[] master;
            byte[] clientRandom = spec.getClientRandom();
            byte[] serverRandom = spec.getServerRandom();

            if (protocolVersion >= 0x0301) {
                byte[] seed = concat(clientRandom, serverRandom);
                master = doPRF(premaster, LABEL_MASTER_SECRET, seed, 48);
            } else {
                master = new byte[48];
                MessageDigest md5 = MessageDigest.getInstance("MD5");
                MessageDigest sha = MessageDigest.getInstance("SHA");

                byte[] tmp = new byte[20];
                for (int i = 0; i < 3; i++) {
                    sha.update(SSL3_CONST[i]);
                    sha.update(premaster);
                    sha.update(clientRandom);
                    sha.update(serverRandom);
                    sha.digest(tmp, 0, 20);

                    md5.update(premaster);
                    md5.update(tmp);
                    md5.digest(master, i << 4, 16);
                }

            }

            return new TlsMasterSecretKey(master, premasterMajor, premasterMinor);
        } catch (NoSuchAlgorithmException e) {
            throw new ProviderException(e);
        } catch (DigestException e) {
            throw new ProviderException(e);
        }
    }

    private static final class TlsMasterSecretKey implements TlsMasterSecret {

        private byte[] key;
        private final int majorVersion, minorVersion;

        TlsMasterSecretKey(byte[] key, int majorVersion, int minorVersion) {
            this.key = key;
            this.majorVersion = majorVersion;
            this.minorVersion = minorVersion;
        }

        public int getMajorVersion() {
            return majorVersion;
        }

        public int getMinorVersion() {
            return minorVersion;
        }

        public String getAlgorithm() {
            return "TlsMasterSecret";
        }

        public String getFormat() {
            return "RAW";
        }

        public byte[] getEncoded() {
            return key.clone();
        }

    }

}
