/*

 * Copyright (c) 2018, 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 sun.security.ssl;

import java.io.IOException;

import java.nio.ByteBuffer;

import java.security.GeneralSecurityException;

import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.SecretKey;

import javax.net.ssl.SSLHandshakeException;

final class SSLBasicKeyDerivation implements SSLKeyDerivation {

    private final String hashAlg;

    private final SecretKey secret;

    private final byte[] hkdfInfo;

    SSLBasicKeyDerivation(SecretKey secret, String hashAlg,

            byte[] label, byte[] context, int length) {

        this.hashAlg = hashAlg.replace("-", "");

        this.secret = secret;

        this.hkdfInfo = createHkdfInfo(label, context, length);

    }

    @Override

    public SecretKey deriveKey(String algorithm,

            AlgorithmParameterSpec keySpec) throws IOException {

        try {

            HKDF hkdf = new HKDF(hashAlg);

            return hkdf.expand(secret, hkdfInfo,

                    ((SecretSizeSpec)keySpec).length, algorithm);

        } catch (GeneralSecurityException gse) {

            throw (SSLHandshakeException) new SSLHandshakeException(

                "Could not generate secret").initCause(gse);

        }

    }

    private static byte[] createHkdfInfo(

            byte[] label, byte[] context, int length) {

        byte[] info = new byte[4 + label.length + context.length];

        ByteBuffer m = ByteBuffer.wrap(info);

        try {

            Record.putInt16(m, length);

            Record.putBytes8(m, label);

            Record.putBytes8(m, context);

        } catch (IOException ioe) {

            // unlikely

        }

        return info;

    }

    static class SecretSizeSpec implements AlgorithmParameterSpec {

        final int length;

        SecretSizeSpec(int length) {

            this.length = length;

        }

    }

}