/*

 * Copyright (c) 2005, 2021, 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.*;

import java.security.spec.AlgorithmParameterSpec;

import java.util.Arrays;

import javax.crypto.*;

import javax.crypto.spec.SecretKeySpec;

import sun.security.internal.spec.TlsRsaPremasterSecretParameterSpec;

/**

 * KeyGenerator implementation for the SSL/TLS RSA premaster secret.

 *

 * @author  Andreas Sterbenz

 * @since   1.6

 */

public final class TlsRsaPremasterSecretGenerator extends KeyGeneratorSpi {

    private static final String MSG = "TlsRsaPremasterSecretGenerator must be "

        + "initialized using a TlsRsaPremasterSecretParameterSpec";

    @SuppressWarnings("deprecation")

    private TlsRsaPremasterSecretParameterSpec spec;

    private SecureRandom random;

    public TlsRsaPremasterSecretGenerator() {

    }

    protected void engineInit(SecureRandom random) {

        throw new InvalidParameterException(MSG);

    }

    @SuppressWarnings("deprecation")

    protected void engineInit(AlgorithmParameterSpec params,

            SecureRandom random) throws InvalidAlgorithmParameterException {

        if (!(params instanceof TlsRsaPremasterSecretParameterSpec)) {

            throw new InvalidAlgorithmParameterException(MSG);

        }

        this.spec = (TlsRsaPremasterSecretParameterSpec)params;

        this.random = random;

    }

    protected void engineInit(int keysize, SecureRandom random) {

        throw new InvalidParameterException(MSG);

    }

    // Only can be used in client side to generate TLS RSA premaster secret.

    protected SecretKey engineGenerateKey() {

        if (spec == null) {

            throw new IllegalStateException(

                "TlsRsaPremasterSecretGenerator must be initialized");

        }

        byte[] b = spec.getEncodedSecret();

        if (b == null) {

            if (random == null) {

                random = new SecureRandom();

            }

            b = new byte[48];

            random.nextBytes(b);

        }

        b[0] = (byte)spec.getMajorVersion();

        b[1] = (byte)spec.getMinorVersion();

        try {

            return new SecretKeySpec(b, "TlsRsaPremasterSecret");

        } finally {

            Arrays.fill(b, (byte)0);

        }

    }

}