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/**

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements. See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership. The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License. You may obtain a copy of the License at

 *

 * http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing,

 * software distributed under the License is distributed on an

 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

 * KIND, either express or implied. See the License for the

 * specific language governing permissions and limitations

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package com.sun.org.apache.xml.internal.security.keys.keyresolver.implementations;

import java.security.PublicKey;

import java.security.cert.Certificate;

import java.security.cert.X509Certificate;

import java.util.Arrays;

import java.util.Iterator;

import javax.crypto.SecretKey;

import com.sun.org.apache.xml.internal.security.exceptions.XMLSecurityException;

import com.sun.org.apache.xml.internal.security.keys.content.X509Data;

import com.sun.org.apache.xml.internal.security.keys.content.x509.XMLX509Digest;

import com.sun.org.apache.xml.internal.security.keys.keyresolver.KeyResolverException;

import com.sun.org.apache.xml.internal.security.keys.keyresolver.KeyResolverSpi;

import com.sun.org.apache.xml.internal.security.keys.storage.StorageResolver;

import com.sun.org.apache.xml.internal.security.utils.Constants;

import com.sun.org.apache.xml.internal.security.utils.XMLUtils;

import org.w3c.dom.Element;

/**

 * KeyResolverSpi implementation which resolves public keys and X.509 certificates from a

 * {@code dsig11:X509Digest} element.

 *

 */

public class X509DigestResolver extends KeyResolverSpi {

    private static final com.sun.org.slf4j.internal.Logger LOG =

        com.sun.org.slf4j.internal.LoggerFactory.getLogger(X509DigestResolver.class);

    /** {{@inheritDoc}}. */

    public boolean engineCanResolve(Element element, String baseURI, StorageResolver storage) {

        if (XMLUtils.elementIsInSignatureSpace(element, Constants._TAG_X509DATA)) {

            try {

                X509Data x509Data = new X509Data(element, baseURI);

                return x509Data.containsDigest();

            } catch (XMLSecurityException e) {

                return false;

            }

        } else {

            return false;

        }

    }

    /** {{@inheritDoc}}. */

    public PublicKey engineLookupAndResolvePublicKey(Element element, String baseURI, StorageResolver storage)

        throws KeyResolverException {

        X509Certificate cert = this.engineLookupResolveX509Certificate(element, baseURI, storage);

        if (cert != null) {

            return cert.getPublicKey();

        }

        return null;

    }

    /** {{@inheritDoc}}. */

    public X509Certificate engineLookupResolveX509Certificate(Element element, String baseURI, StorageResolver storage)

        throws KeyResolverException {

        LOG.debug("Can I resolve {}", element.getTagName());

        if (!engineCanResolve(element, baseURI, storage)) {

            return null;

        }

        try {

            return resolveCertificate(element, baseURI, storage);

        } catch (XMLSecurityException e) {

            LOG.debug("XMLSecurityException", e);

        }

        return null;

    }

    /** {{@inheritDoc}}. */

    public SecretKey engineLookupAndResolveSecretKey(Element element, String baseURI, StorageResolver storage)

        throws KeyResolverException {

        return null;

    }

    /**

     * Resolves from the storage resolver the actual certificate represented by the digest.

     *

     * @param element

     * @param baseURI

     * @param storage

     * @return the certificate represented by the digest.

     * @throws XMLSecurityException

     */

    private X509Certificate resolveCertificate(Element element, String baseURI, StorageResolver storage)

        throws XMLSecurityException {

        XMLX509Digest x509Digests[] = null;

        Element x509childNodes[] = XMLUtils.selectDs11Nodes(element.getFirstChild(), Constants._TAG_X509DIGEST);

        if (x509childNodes == null || x509childNodes.length <= 0) {

            return null;

        }

        try {

            checkStorage(storage);

            x509Digests = new XMLX509Digest[x509childNodes.length];

            for (int i = 0; i < x509childNodes.length; i++) {

                x509Digests[i] = new XMLX509Digest(x509childNodes[i], baseURI);

            }

            Iterator<Certificate> storageIterator = storage.getIterator();

            while (storageIterator.hasNext()) {

                X509Certificate cert = (X509Certificate) storageIterator.next();

                for (int i = 0; i < x509Digests.length; i++) {

                    XMLX509Digest keyInfoDigest = x509Digests[i];

                    byte[] certDigestBytes = XMLX509Digest.getDigestBytesFromCert(cert, keyInfoDigest.getAlgorithm());

                    if (Arrays.equals(keyInfoDigest.getDigestBytes(), certDigestBytes)) {

                        LOG.debug("Found certificate with: {}", cert.getSubjectX500Principal().getName());

                        return cert;

                    }

                }

            }

        } catch (XMLSecurityException ex) {

            throw new KeyResolverException(ex);

        }

        return null;

    }

    /**

     * Method checkSrorage

     *

     * @param storage

     * @throws KeyResolverException

     */

    private void checkStorage(StorageResolver storage) throws KeyResolverException {

        if (storage == null) {

            Object exArgs[] = { Constants._TAG_X509DIGEST };

            KeyResolverException ex = new KeyResolverException("KeyResolver.needStorageResolver", exArgs);

            LOG.debug("", ex);

            throw ex;

        }

    }

}