src/org/apache/xml/security/keys/keyresolver/implementations/RSAKeyValueResolver.java

/*
 * The Apache Software License, Version 1.1
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 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights
 * reserved.
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 * modification, are permitted provided that the following conditions
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 * 1. Redistributions of source code must retain the above copyright
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 *       "This product includes software developed by the
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 *    if and wherever such third-party acknowledgments normally appear.
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 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 2001, Institute for
 * Data Communications Systems, <http://www.nue.et-inf.uni-siegen.de/>.
 * The development of this software was partly funded by the European
 * Commission in the <WebSig> project in the ISIS Programme.
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package org.apache.xml.security.keys.keyresolver.implementations;



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

import javax.xml.transform.TransformerException;

import org.apache.xml.security.exceptions.XMLSecurityException;
import org.apache.xml.security.keys.content.keyvalues.RSAKeyValue;
import org.apache.xml.security.keys.keyresolver.KeyResolverException;
import org.apache.xml.security.keys.keyresolver.KeyResolverSpi;
import org.apache.xml.security.keys.storage.StorageResolver;
import org.apache.xml.security.utils.Constants;
import org.apache.xml.security.utils.XMLUtils;
import org.apache.xpath.XPathAPI;
import org.w3c.dom.Element;


/**
 *
 * @author $Author$
 */
public class RSAKeyValueResolver extends KeyResolverSpi {

   /** {@link org.apache.commons.logging} logging facility */
    static org.apache.commons.logging.Log log = 
        org.apache.commons.logging.LogFactory.getLog(
                        RSAKeyValueResolver.class.getName());

   /** Field _rsaKeyElement */
   private Element _rsaKeyElement = null;

   /**
    * Method engineCanResolve
    *
    * @param element
    * @param BaseURI
    * @param storage
    *
    */
   public boolean engineCanResolve(Element element, String BaseURI,
                                   StorageResolver storage) {

      log.debug("Can I resolve " + element.getTagName());

      if (element == null) {
         return false;
      }

      boolean isKeyValue = XMLUtils.elementIsInSignatureSpace(element,
                              Constants._TAG_KEYVALUE);
      boolean isRSAKeyValue = XMLUtils.elementIsInSignatureSpace(element,
                                 Constants._TAG_RSAKEYVALUE);

      if (isKeyValue) {
         try {
         Element nscontext = XMLUtils.createDSctx(element.getOwnerDocument(), "ds", Constants.SignatureSpecNS);

            this._rsaKeyElement = (Element) XPathAPI.selectSingleNode(element,
                    "./ds:" + Constants._TAG_RSAKEYVALUE, nscontext);

            if (this._rsaKeyElement != null) {
               return true;
            }
         } catch (TransformerException ex) {}
      } else if (isRSAKeyValue) {

         // this trick is needed to allow the RetrievalMethodResolver to eat a
         // ds:RSAKeyValue directly (without KeyValue)
         this._rsaKeyElement = element;

         return true;
      }

      return false;
   }

   /**
    * Method engineResolvePublicKey
    *
    * @param element
    * @param BaseURI
    * @param storage
    * @return null if no {@link PublicKey} could be obtained
    * @throws KeyResolverException
    */
   public PublicKey engineResolvePublicKey(
           Element element, String BaseURI, StorageResolver storage)
              throws KeyResolverException {

      if (this._rsaKeyElement == null) {
         boolean weCanResolve = this.engineCanResolve(element, BaseURI,
                                   storage);

         if (!weCanResolve || (this._rsaKeyElement == null)) {
            return null;
         }
      }

      try {
         RSAKeyValue rsaKeyValue = new RSAKeyValue(this._rsaKeyElement,
                                                   BaseURI);

         return rsaKeyValue.getPublicKey();
      } catch (XMLSecurityException ex) {
         log.debug("XMLSecurityException", ex);
      }

      return null;
   }

   /**
    * Method engineResolveX509Certificate
    *
    * @param element
    * @param BaseURI
    * @param storage
    *
    * @throws KeyResolverException
    */
   public X509Certificate engineResolveX509Certificate(
           Element element, String BaseURI, StorageResolver storage)
              throws KeyResolverException {
      return null;
   }

   /**
    * Method engineResolveSecretKey
    *
    * @param element
    * @param BaseURI
    * @param storage
    *
    * @throws KeyResolverException
    */
   public javax.crypto.SecretKey engineResolveSecretKey(
           Element element, String BaseURI, StorageResolver storage)
              throws KeyResolverException {
      return null;
   }
}