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/*
 * Copyright  1999-2004 The Apache Software Foundation.
 *
 *  Licensed 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
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package com.sun.org.apache.xml.internal.security.keys.keyresolver.implementations;



import java.security.PublicKey;
import java.security.cert.X509Certificate;


import com.sun.org.apache.xml.internal.security.exceptions.XMLSecurityException;
import com.sun.org.apache.xml.internal.security.keys.content.keyvalues.DSAKeyValue;
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;


Author:
$Author: mullan $/**
 *
 * @author $Author: mullan $
 */
public class DSAKeyValueResolver extends KeyResolverSpi {

   
Method engineResolvePublicKey
Params:
element – 
BaseURI – 
storage – 
Returns:
null if no PublicKey could be obtained/**
    * Method engineResolvePublicKey
    *
    * @param element
    * @param BaseURI
    * @param storage
    * @return null if no {@link PublicKey} could be obtained
    */
   public PublicKey engineLookupAndResolvePublicKey(
           Element element, String BaseURI, StorageResolver storage) {
            if (element == null) {
                 return null;
            }
            Element dsaKeyElement=null;
            boolean isKeyValue = XMLUtils.elementIsInSignatureSpace(element,
                                      Constants._TAG_KEYVALUE);
            if (isKeyValue) {
                dsaKeyElement =
                        XMLUtils.selectDsNode(element.getFirstChild(),Constants._TAG_DSAKEYVALUE,0);
       } else if (XMLUtils.elementIsInSignatureSpace(element,
               Constants._TAG_DSAKEYVALUE)) {
                 // this trick is needed to allow the RetrievalMethodResolver to eat a
                 // ds:DSAKeyValue directly (without KeyValue)
                 dsaKeyElement = element;
            }

      if (dsaKeyElement == null) {
                    return null;
      }

      try {
         DSAKeyValue dsaKeyValue = new DSAKeyValue(dsaKeyElement,
                                                   BaseURI);
         PublicKey pk = dsaKeyValue.getPublicKey();

         return pk;
      } catch (XMLSecurityException ex) {
                //do nothing
      }

      return null;
   }


   
@inheritDoc
/** @inheritDoc */
   public X509Certificate engineLookupResolveX509Certificate(
           Element element, String BaseURI, StorageResolver storage) {
      return null;
   }

   
@inheritDoc
/** @inheritDoc */
   public javax.crypto.SecretKey engineLookupAndResolveSecretKey(
           Element element, String BaseURI, StorageResolver storage){
      return null;
   }
}