/*

 * Copyright (c) 1997, 2011, 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.Key;

import java.security.PublicKey;

import java.security.PrivateKey;

import java.security.KeyFactorySpi;

import java.security.InvalidKeyException;

import java.security.spec.KeySpec;

import java.security.spec.InvalidKeySpecException;

import java.security.spec.X509EncodedKeySpec;

import java.security.spec.PKCS8EncodedKeySpec;

import javax.crypto.spec.DHPublicKeySpec;

import javax.crypto.spec.DHPrivateKeySpec;

import javax.crypto.spec.DHParameterSpec;

/**

 * This class implements the Diffie-Hellman key factory of the Sun provider.

 *

 * @author Jan Luehe

 *

 */

public final class DHKeyFactory extends KeyFactorySpi {

    /**

     * Empty constructor

     */

    public DHKeyFactory() {

    }

    /**

     * Generates a public key object from the provided key specification

     * (key material).

     *

     * @param keySpec the specification (key material) of the public key

     *

     * @return the public key

     *

     * @exception InvalidKeySpecException if the given key specification

     * is inappropriate for this key factory to produce a public key.

     */

    protected PublicKey engineGeneratePublic(KeySpec keySpec)

        throws InvalidKeySpecException

    {

        try {

            if (keySpec instanceof DHPublicKeySpec) {

                DHPublicKeySpec dhPubKeySpec = (DHPublicKeySpec)keySpec;

                return new DHPublicKey(dhPubKeySpec.getY(),

                                       dhPubKeySpec.getP(),

                                       dhPubKeySpec.getG());

            } else if (keySpec instanceof X509EncodedKeySpec) {

                return new DHPublicKey

                    (((X509EncodedKeySpec)keySpec).getEncoded());

            } else {

                throw new InvalidKeySpecException

                    ("Inappropriate key specification");

            }

        } catch (InvalidKeyException e) {

            throw new InvalidKeySpecException

                ("Inappropriate key specification");

        }

    }

    /**

     * Generates a private key object from the provided key specification

     * (key material).

     *

     * @param keySpec the specification (key material) of the private key

     *

     * @return the private key

     *

     * @exception InvalidKeySpecException if the given key specification

     * is inappropriate for this key factory to produce a private key.

     */

    protected PrivateKey engineGeneratePrivate(KeySpec keySpec)

        throws InvalidKeySpecException

    {

        try {

            if (keySpec instanceof DHPrivateKeySpec) {

                DHPrivateKeySpec dhPrivKeySpec = (DHPrivateKeySpec)keySpec;

                return new DHPrivateKey(dhPrivKeySpec.getX(),

                                        dhPrivKeySpec.getP(),

                                        dhPrivKeySpec.getG());

            } else if (keySpec instanceof PKCS8EncodedKeySpec) {

                return new DHPrivateKey

                    (((PKCS8EncodedKeySpec)keySpec).getEncoded());

            } else {

                throw new InvalidKeySpecException

                    ("Inappropriate key specification");

            }

        } catch (InvalidKeyException e) {

            throw new InvalidKeySpecException

                ("Inappropriate key specification");

        }

    }

    /**

     * Returns a specification (key material) of the given key object

     * in the requested format.

     *

     * @param key the key

     *

     * @param keySpec the requested format in which the key material shall be

     * returned

     *

     * @return the underlying key specification (key material) in the

     * requested format

     *

     * @exception InvalidKeySpecException if the requested key specification is

     * inappropriate for the given key, or the given key cannot be processed

     * (e.g., the given key has an unrecognized algorithm or format).

     */

    protected <T extends KeySpec>

        T engineGetKeySpec(Key key, Class<T> keySpec)

        throws InvalidKeySpecException {

        DHParameterSpec params;

        if (key instanceof javax.crypto.interfaces.DHPublicKey) {

            if (DHPublicKeySpec.class.isAssignableFrom(keySpec)) {

                javax.crypto.interfaces.DHPublicKey dhPubKey

                    = (javax.crypto.interfaces.DHPublicKey) key;

                params = dhPubKey.getParams();

                return keySpec.cast(new DHPublicKeySpec(dhPubKey.getY(),

                                                        params.getP(),

                                                        params.getG()));

            } else if (X509EncodedKeySpec.class.isAssignableFrom(keySpec)) {

                return keySpec.cast(new X509EncodedKeySpec(key.getEncoded()));

            } else {

                throw new InvalidKeySpecException

                    ("Inappropriate key specification");

            }

        } else if (key instanceof javax.crypto.interfaces.DHPrivateKey) {

            if (DHPrivateKeySpec.class.isAssignableFrom(keySpec)) {

                javax.crypto.interfaces.DHPrivateKey dhPrivKey

                    = (javax.crypto.interfaces.DHPrivateKey)key;

                params = dhPrivKey.getParams();

                return keySpec.cast(new DHPrivateKeySpec(dhPrivKey.getX(),

                                                         params.getP(),

                                                         params.getG()));

            } else if (PKCS8EncodedKeySpec.class.isAssignableFrom(keySpec)) {

                return keySpec.cast(new PKCS8EncodedKeySpec(key.getEncoded()));

            } else {

                throw new InvalidKeySpecException

                    ("Inappropriate key specification");

            }

        } else {

            throw new InvalidKeySpecException("Inappropriate key type");

        }

    }

    /**

     * Translates a key object, whose provider may be unknown or potentially

     * untrusted, into a corresponding key object of this key factory.

     *

     * @param key the key whose provider is unknown or untrusted

     *

     * @return the translated key

     *

     * @exception InvalidKeyException if the given key cannot be processed by

     * this key factory.

     */

    protected Key engineTranslateKey(Key key)

        throws InvalidKeyException

    {

        try {

            if (key instanceof javax.crypto.interfaces.DHPublicKey) {

                // Check if key originates from this factory

                if (key instanceof com.sun.crypto.provider.DHPublicKey) {

                    return key;

                }

                // Convert key to spec

                DHPublicKeySpec dhPubKeySpec

                    = engineGetKeySpec(key, DHPublicKeySpec.class);

                // Create key from spec, and return it

                return engineGeneratePublic(dhPubKeySpec);

            } else if (key instanceof javax.crypto.interfaces.DHPrivateKey) {

                // Check if key originates from this factory

                if (key instanceof com.sun.crypto.provider.DHPrivateKey) {

                    return key;

                }

                // Convert key to spec

                DHPrivateKeySpec dhPrivKeySpec

                    = engineGetKeySpec(key, DHPrivateKeySpec.class);

                // Create key from spec, and return it

                return engineGeneratePrivate(dhPrivKeySpec);

            } else {

                throw new InvalidKeyException("Wrong algorithm type");

            }

        } catch (InvalidKeySpecException e) {

            throw new InvalidKeyException("Cannot translate key");

        }

    }

}