/*

 * 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.ec;

import java.math.BigInteger;

import java.security.KeyPairGeneratorSpi;

import java.security.InvalidKeyException;

import java.security.InvalidParameterException;

import java.security.InvalidAlgorithmParameterException;

import java.security.KeyPair;

import java.security.ProviderException;

import java.security.SecureRandom;

import java.security.spec.AlgorithmParameterSpec;

import java.security.spec.NamedParameterSpec;

import sun.security.jca.JCAUtil;

/**

 * Key pair generator for the XDH key agreement algorithm.

 */

public class XDHKeyPairGenerator extends KeyPairGeneratorSpi {

    private static final NamedParameterSpec DEFAULT_PARAM_SPEC

        = NamedParameterSpec.X25519;

    private SecureRandom random = null;

    private XECOperations ops = null;

    private XECParameters lockedParams = null;

    XDHKeyPairGenerator() {

        tryInitialize(DEFAULT_PARAM_SPEC);

    }

    private XDHKeyPairGenerator(NamedParameterSpec paramSpec) {

        tryInitialize(paramSpec);

        lockedParams = ops.getParameters();

    }

    private void tryInitialize(NamedParameterSpec paramSpec) {

        try {

            initialize(paramSpec, null);

        } catch (InvalidAlgorithmParameterException ex) {

            String name = paramSpec.getName();

            throw new ProviderException(name + " not supported");

        }

    }

    @Override

    public void initialize(int keySize, SecureRandom random) {

        XECParameters params = XECParameters.getBySize(

            InvalidParameterException::new, keySize);

        initializeImpl(params, random);

    }

    @Override

    public void initialize(AlgorithmParameterSpec params, SecureRandom random)

            throws InvalidAlgorithmParameterException {

        XECParameters xecParams = XECParameters.get(

            InvalidAlgorithmParameterException::new, params);

        initializeImpl(xecParams, random);

    }

    private void initializeImpl(XECParameters params, SecureRandom random) {

        if (lockedParams != null && lockedParams != params) {

            throw new InvalidParameterException("Parameters must be " +

                lockedParams.getName());

        }

        this.ops = new XECOperations(params);

        this.random = random == null ? JCAUtil.getSecureRandom() : random;

    }

    @Override

    public KeyPair generateKeyPair() {

        byte[] privateKey = ops.generatePrivate(random);

        // computePublic may modify the private key, so clone it first

        BigInteger publicKey = ops.computePublic(privateKey.clone());

        try {

            return new KeyPair(

                new XDHPublicKeyImpl(ops.getParameters(), publicKey),

                new XDHPrivateKeyImpl(ops.getParameters(), privateKey)

            );

        } catch (InvalidKeyException ex) {

            throw new ProviderException(ex);

        }

    }

    static class X25519 extends XDHKeyPairGenerator {

        public X25519() {

            super(NamedParameterSpec.X25519);

        }

    }

    static class X448 extends XDHKeyPairGenerator {

        public X448() {

            super(NamedParameterSpec.X448);

        }

    }

}