src/main/java/org/apache/jcp/xml/dsig/internal/dom/DOMReference.java - santuario-java - Git at Google

 /**
  * 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
  * under the License.
  */
 /*
  * Portions copyright 2005 Sun Microsystems, Inc. All rights reserved.
  */
 /*
  * ===========================================================================
  *
  * (C) Copyright IBM Corp. 2003 All Rights Reserved.
  *
  * ===========================================================================
  */
 /*
  * $Id$
  */
 package org.apache.jcp.xml.dsig.internal.dom;

 import javax.xml.crypto.*;
 import javax.xml.crypto.dsig.*;
 import javax.xml.crypto.dom.DOMCryptoContext;
 import javax.xml.crypto.dom.DOMURIReference;

 import java.io.*;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.security.*;
 import java.util.*;

 import org.w3c.dom.Attr;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 import org.w3c.dom.Node;

 import org.apache.xml.security.utils.XMLUtils;

 import org.apache.jcp.xml.dsig.internal.DigesterOutputStream;
 import org.apache.xml.security.algorithms.MessageDigestAlgorithm;
 import org.apache.xml.security.signature.XMLSignatureInput;
 import org.apache.xml.security.utils.UnsyncBufferedOutputStream;

 /**
  * DOM-based implementation of Reference.
  *
  */
 public final class DOMReference extends DOMStructure
     implements Reference, DOMURIReference {

    /**
     * The maximum number of transforms per reference, if secure validation is enabled.
     */
    public static final int MAXIMUM_TRANSFORM_COUNT = 5;

    /**
     * Look up useC14N11 system property. If true, an explicit C14N11 transform
     * will be added if necessary when generating the signature. See section
     * 3.1.1 of http://www.w3.org/2007/xmlsec/Drafts/xmldsig-core/ for more info.
     *
     * If true, overrides the same property if set in the XMLSignContext.
     */
     private static boolean useC14N11 =
         AccessController.doPrivileged((PrivilegedAction<Boolean>)
             () -> Boolean.getBoolean("com.sun.org.apache.xml.internal.security.useC14N11"));

     private static final org.slf4j.Logger LOG =
         org.slf4j.LoggerFactory.getLogger(DOMReference.class);

     private final DigestMethod digestMethod;
     private final String id;
     private final List<Transform> transforms;
     private List<Transform> allTransforms;
     private final Data appliedTransformData;
     private Attr here;
     private final String uri;
     private final String type;
     private byte[] digestValue;
     private byte[] calcDigestValue;
     private Element refElem;
     private boolean digested = false;
     private boolean validated = false;
     private boolean validationStatus;
     private Data derefData;
     private InputStream dis;
     private MessageDigest md;
     private Provider provider;

     /**
      * Creates a <code>Reference</code> from the specified parameters.
      *
      * @param uri the URI (may be null)
      * @param type the type (may be null)
      * @param dm the digest method
      * @param transforms a list of {@link Transform}s. The list
      *    is defensively copied to protect against subsequent modification.
      *    May be <code>null</code> or empty.
      * @param id the reference ID (may be <code>null</code>)
      * @throws NullPointerException if <code>dm</code> is <code>null</code>
      * @throws ClassCastException if any of the <code>transforms</code> are
      *    not of type <code>Transform</code>
      */
     public DOMReference(String uri, String type, DigestMethod dm,
                         List<? extends Transform> transforms, String id,
                         Provider provider)
     {
         this(uri, type, dm, null, null, transforms, id, null, provider);
     }

     public DOMReference(String uri, String type, DigestMethod dm,
                         List<? extends Transform> appliedTransforms,
                         Data result, List<? extends Transform> transforms,
                         String id, Provider provider)
     {
         this(uri, type, dm, appliedTransforms,
              result, transforms, id, null, provider);
     }

     public DOMReference(String uri, String type, DigestMethod dm,
                         List<? extends Transform> appliedTransforms,
                         Data result, List<? extends Transform> transforms,
                         String id, byte[] digestValue, Provider provider)
     {
         if (dm == null) {
             throw new NullPointerException("DigestMethod must be non-null");
         }
         if (appliedTransforms == null) {
             this.allTransforms = new ArrayList<>();
         } else {
             this.allTransforms = new ArrayList<>(appliedTransforms);
             for (int i = 0, size = this.allTransforms.size(); i < size; i++) {
                 if (!(this.allTransforms.get(i) instanceof Transform)) {
                     throw new ClassCastException
                         ("appliedTransforms["+i+"] is not a valid type");
                 }
             }
         }
         if (transforms == null) {
             this.transforms = Collections.emptyList();
         } else {
             this.transforms = new ArrayList<>(transforms);
             for (int i = 0, size = this.transforms.size(); i < size; i++) {
                 if (!(this.transforms.get(i) instanceof Transform)) {
                     throw new ClassCastException
                         ("transforms["+i+"] is not a valid type");
                 }
             }
             this.allTransforms.addAll(this.transforms);
         }
         this.digestMethod = dm;
         this.uri = uri;
         if (uri != null && !uri.isEmpty()) {
             try {
                 new URI(uri);
             } catch (URISyntaxException e) {
                 throw new IllegalArgumentException(e.getMessage());
             }
         }
         this.type = type;
         this.id = id;
         if (digestValue != null) {
             this.digestValue = digestValue.clone();
             this.digested = true;
         }
         this.appliedTransformData = result;
         this.provider = provider;
     }

     /**
      * Creates a <code>DOMReference</code> from an element.
      *
      * @param refElem a Reference element
      */
     public DOMReference(Element refElem, XMLCryptoContext context,
                         Provider provider)
         throws MarshalException
     {
         boolean secVal = Utils.secureValidation(context);

         // unmarshal Transforms, if specified
         Element nextSibling = DOMUtils.getFirstChildElement(refElem);
         List<Transform> newTransforms = new ArrayList<>(MAXIMUM_TRANSFORM_COUNT);
         if ("Transforms".equals(nextSibling.getLocalName())
             && XMLSignature.XMLNS.equals(nextSibling.getNamespaceURI())) {
             Element transformElem = DOMUtils.getFirstChildElement(nextSibling,
                                                                   "Transform",
                                                                   XMLSignature.XMLNS);
             newTransforms.add(new DOMTransform(transformElem, context, provider));
             transformElem = DOMUtils.getNextSiblingElement(transformElem);
             while (transformElem != null) {
                 String localName = transformElem.getLocalName();
                 String namespace = transformElem.getNamespaceURI();
                 if (!"Transform".equals(localName) || !XMLSignature.XMLNS.equals(namespace)) {
                     throw new MarshalException(
                         "Invalid element name: " + localName +
                         ", expected Transform");
                 }
                 newTransforms.add
                     (new DOMTransform(transformElem, context, provider));
                 if (secVal && newTransforms.size() > MAXIMUM_TRANSFORM_COUNT) {
                     String error = "A maxiumum of " + MAXIMUM_TRANSFORM_COUNT + " "
                         + "transforms per Reference are allowed with secure validation";
                     throw new MarshalException(error);
                 }
                 transformElem = DOMUtils.getNextSiblingElement(transformElem);
             }
             nextSibling = DOMUtils.getNextSiblingElement(nextSibling);
         }
         if (!"DigestMethod".equals(nextSibling.getLocalName())
             && XMLSignature.XMLNS.equals(nextSibling.getNamespaceURI())) {
             throw new MarshalException("Invalid element name: " +
                                        nextSibling.getLocalName() +
                                        ", expected DigestMethod");
         }

         // unmarshal DigestMethod
         Element dmElem = nextSibling;
         this.digestMethod = DOMDigestMethod.unmarshal(dmElem);
         String digestMethodAlgorithm = this.digestMethod.getAlgorithm();
         if (secVal
             && MessageDigestAlgorithm.ALGO_ID_DIGEST_NOT_RECOMMENDED_MD5.equals(digestMethodAlgorithm)) {
             throw new MarshalException(
                 "It is forbidden to use algorithm " + digestMethod + " when secure validation is enabled"
             );
         }

         // unmarshal DigestValue
         Element dvElem = DOMUtils.getNextSiblingElement(dmElem, "DigestValue", XMLSignature.XMLNS);
         String content = XMLUtils.getFullTextChildrenFromNode(dvElem);
         this.digestValue = XMLUtils.decode(content);

         // check for extra elements
         if (DOMUtils.getNextSiblingElement(dvElem) != null) {
             throw new MarshalException(
                 "Unexpected element after DigestValue element");
         }

         // unmarshal attributes
         this.uri = DOMUtils.getAttributeValue(refElem, "URI");

         Attr attr = refElem.getAttributeNodeNS(null, "Id");
         if (attr != null) {
             this.id = attr.getValue();
             refElem.setIdAttributeNode(attr, true);
         } else {
             this.id = null;
         }

         this.type = DOMUtils.getAttributeValue(refElem, "Type");
         this.here = refElem.getAttributeNodeNS(null, "URI");
         this.refElem = refElem;
         this.transforms = newTransforms;
         this.allTransforms = transforms;
         this.appliedTransformData = null;
         this.provider = provider;
     }

     public DigestMethod getDigestMethod() {
         return digestMethod;
     }

     public String getId() {
         return id;
     }

     public String getURI() {
         return uri;
     }

     public String getType() {
         return type;
     }

     public List<Transform> getTransforms() {
         return Collections.unmodifiableList(allTransforms);
     }

     public byte[] getDigestValue() {
         return digestValue == null ? null : digestValue.clone();
     }

     public byte[] getCalculatedDigestValue() {
         return calcDigestValue == null ? null
                                         : calcDigestValue.clone();
     }

     @Override
     public void marshal(Node parent, String dsPrefix, DOMCryptoContext context)
         throws MarshalException
     {
         LOG.debug("Marshalling Reference");
         Document ownerDoc = DOMUtils.getOwnerDocument(parent);

         refElem = DOMUtils.createElement(ownerDoc, "Reference",
                                          XMLSignature.XMLNS, dsPrefix);

         // set attributes
         DOMUtils.setAttributeID(refElem, "Id", id);
         DOMUtils.setAttribute(refElem, "URI", uri);
         DOMUtils.setAttribute(refElem, "Type", type);

         // create and append Transforms element
         if (!allTransforms.isEmpty()) {
             Element transformsElem = DOMUtils.createElement(ownerDoc,
                                                             "Transforms",
                                                             XMLSignature.XMLNS,
                                                             dsPrefix);
             refElem.appendChild(transformsElem);
             for (Transform transform : allTransforms) {
                 ((DOMStructure)transform).marshal(transformsElem,
                                                   dsPrefix, context);
             }
         }

         // create and append DigestMethod element
         ((DOMDigestMethod)digestMethod).marshal(refElem, dsPrefix, context);

         // create and append DigestValue element
         LOG.debug("Adding digestValueElem");
         Element digestValueElem = DOMUtils.createElement(ownerDoc,
                                                          "DigestValue",
                                                          XMLSignature.XMLNS,
                                                          dsPrefix);
         if (digestValue != null) {
             digestValueElem.appendChild
                 (ownerDoc.createTextNode(XMLUtils.encodeToString(digestValue)));
         }
         refElem.appendChild(digestValueElem);

         parent.appendChild(refElem);
         here = refElem.getAttributeNodeNS(null, "URI");
     }

     public void digest(XMLSignContext signContext)
         throws XMLSignatureException
     {
         Data data = null;
         if (appliedTransformData == null) {
             data = dereference(signContext);
         } else {
             data = appliedTransformData;
         }
         digestValue = transform(data, signContext);

         // insert digestValue into DigestValue element
         String encodedDV = XMLUtils.encodeToString(digestValue);
         LOG.debug("Reference object uri = {}", uri);
         Element digestElem = DOMUtils.getLastChildElement(refElem);
         if (digestElem == null) {
             throw new XMLSignatureException("DigestValue element expected");
         }
         DOMUtils.removeAllChildren(digestElem);
         digestElem.appendChild
             (refElem.getOwnerDocument().createTextNode(encodedDV));

         digested = true;
         LOG.debug("Reference digesting completed");
     }

     public boolean validate(XMLValidateContext validateContext)
         throws XMLSignatureException
     {
         if (validateContext == null) {
             throw new NullPointerException("validateContext cannot be null");
         }
         if (validated) {
             return validationStatus;
         }
         Data data = dereference(validateContext);
         calcDigestValue = transform(data, validateContext);

         if (LOG.isDebugEnabled()) {
             LOG.debug("Expected digest: " + XMLUtils.encodeToString(digestValue));
             LOG.debug("Actual digest: " + XMLUtils.encodeToString(calcDigestValue));
         }

         validationStatus = Arrays.equals(digestValue, calcDigestValue);
         validated = true;
         return validationStatus;
     }

     public Data getDereferencedData() {
         return derefData;
     }

     public InputStream getDigestInputStream() {
         return dis;
     }

     private Data dereference(XMLCryptoContext context)
         throws XMLSignatureException
     {
         Data data = null;

         // use user-specified URIDereferencer if specified; otherwise use deflt
         URIDereferencer deref = context.getURIDereferencer();
         if (deref == null) {
             deref = DOMURIDereferencer.INSTANCE;
         }
         try {
             data = deref.dereference(this, context);
             LOG.debug("URIDereferencer class name: {}", deref.getClass().getName());
             LOG.debug("Data class name: {}", data.getClass().getName());
         } catch (URIReferenceException ure) {
             throw new XMLSignatureException(ure);
         }

         return data;
     }

     private byte[] transform(Data dereferencedData,
                              XMLCryptoContext context)
         throws XMLSignatureException
     {
         if (md == null) {
             try {
                 md = MessageDigest.getInstance
                     (((DOMDigestMethod)digestMethod).getMessageDigestAlgorithm());
             } catch (NoSuchAlgorithmException nsae) {
                 throw new XMLSignatureException(nsae);
             }
         }
         md.reset();
         DigesterOutputStream dos;
         Boolean cache = (Boolean)
             context.getProperty("javax.xml.crypto.dsig.cacheReference");
         if (cache != null && cache) {
             this.derefData = copyDerefData(dereferencedData);
             dos = new DigesterOutputStream(md, true);
         } else {
             dos = new DigesterOutputStream(md);
         }
         Data data = dereferencedData;
         try (OutputStream os = new UnsyncBufferedOutputStream(dos)) {
             for (int i = 0, size = transforms.size(); i < size; i++) {
                 DOMTransform transform = (DOMTransform)transforms.get(i);
                 if (i < size - 1) {
                     data = transform.transform(data, context);
                 } else {
                     data = transform.transform(data, context, os);
                 }
             }

             if (data != null) {
                 XMLSignatureInput xi;
                 // explicitly use C14N 1.1 when generating signature
                 // first check system property, then context property
                 boolean c14n11 = useC14N11;
                 String c14nalg = CanonicalizationMethod.INCLUSIVE;
                 if (context instanceof XMLSignContext) {
                     if (!c14n11) {
                         Boolean prop = (Boolean)context.getProperty
                             ("org.apache.xml.security.useC14N11");
                         c14n11 = prop != null && prop;
                         if (c14n11) {
                             c14nalg = "http://www.w3.org/2006/12/xml-c14n11";
                         }
                     } else {
                         c14nalg = "http://www.w3.org/2006/12/xml-c14n11";
                     }
                 }
                 if (data instanceof ApacheData) {
                     xi = ((ApacheData)data).getXMLSignatureInput();
                 } else if (data instanceof OctetStreamData) {
                     xi = new XMLSignatureInput
                         (((OctetStreamData)data).getOctetStream());
                 } else if (data instanceof NodeSetData) {
                     TransformService spi = null;
                     if (provider == null) {
                         spi = TransformService.getInstance(c14nalg, "DOM");
                     } else {
                         try {
                             spi = TransformService.getInstance(c14nalg, "DOM", provider);
                         } catch (NoSuchAlgorithmException nsae) {
                             spi = TransformService.getInstance(c14nalg, "DOM");
                         }
                     }
                     data = spi.transform(data, context);
                     xi = new XMLSignatureInput
                         (((OctetStreamData)data).getOctetStream());
                 } else {
                     throw new XMLSignatureException("unrecognized Data type");
                 }

                 boolean secVal = Utils.secureValidation(context);
                 xi.setSecureValidation(secVal);
                 if (context instanceof XMLSignContext && c14n11
                     && !xi.isOctetStream() && !xi.isOutputStreamSet()) {
                     TransformService spi = null;
                     if (provider == null) {
                         spi = TransformService.getInstance(c14nalg, "DOM");
                     } else {
                         try {
                             spi = TransformService.getInstance(c14nalg, "DOM", provider);
                         } catch (NoSuchAlgorithmException nsae) {
                             spi = TransformService.getInstance(c14nalg, "DOM");
                         }
                     }

                     DOMTransform t = new DOMTransform(spi);
                     Element transformsElem = null;
                     String dsPrefix = DOMUtils.getSignaturePrefix(context);
                     if (allTransforms.isEmpty()) {
                         transformsElem = DOMUtils.createElement(
                             refElem.getOwnerDocument(),
                             "Transforms", XMLSignature.XMLNS, dsPrefix);
                         refElem.insertBefore(transformsElem,
                             DOMUtils.getFirstChildElement(refElem));
                     } else {
                         transformsElem = DOMUtils.getFirstChildElement(refElem);
                     }
                     t.marshal(transformsElem, dsPrefix,
                               (DOMCryptoContext)context);
                     allTransforms.add(t);
                     xi.updateOutputStream(os, true);
                 } else {
                     xi.updateOutputStream(os);
                 }
             }
             os.flush();
             if (cache != null && cache) {
                 this.dis = dos.getInputStream();
             }
             return dos.getDigestValue();
         } catch (NoSuchAlgorithmException e) {
             throw new XMLSignatureException(e);
         } catch (TransformException e) {
             throw new XMLSignatureException(e);
         } catch (MarshalException e) {
             throw new XMLSignatureException(e);
         } catch (IOException e) {
             throw new XMLSignatureException(e);
         } catch (org.apache.xml.security.c14n.CanonicalizationException e) {
             throw new XMLSignatureException(e);
         } finally { //NOPMD
             if (dos != null) {
                 try {
                     dos.close();
                 } catch (IOException e) {
                     throw new XMLSignatureException(e);
                 }
             }
         }
     }

     public Node getHere() {
         return here;
     }

     @Override
     public boolean equals(Object o) {
         if (this == o) {
             return true;
         }

         if (!(o instanceof Reference)) {
             return false;
         }
         Reference oref = (Reference)o;

         boolean idsEqual = id == null ? oref.getId() == null
                                        : id.equals(oref.getId());
         boolean urisEqual = uri == null ? oref.getURI() == null
                                          : uri.equals(oref.getURI());
         boolean typesEqual = type == null ? oref.getType() == null
                                            : type.equals(oref.getType());
         boolean digestValuesEqual =
             Arrays.equals(digestValue, oref.getDigestValue());

         return digestMethod.equals(oref.getDigestMethod()) && idsEqual &&
             urisEqual && typesEqual &&
             allTransforms.equals(oref.getTransforms()) && digestValuesEqual;
     }

     @Override
     public int hashCode() {
         int result = 17;
         if (id != null) {
             result = 31 * result + id.hashCode();
         }
         if (uri != null) {
             result = 31 * result + uri.hashCode();
         }
         if (type != null) {
             result = 31 * result + type.hashCode();
         }
         if (digestValue != null) {
             result = 31 * result + Arrays.hashCode(digestValue);
         }
         result = 31 * result + digestMethod.hashCode();
         result = 31 * result + allTransforms.hashCode();

         return result;
     }

     boolean isDigested() {
         return digested;
     }

     private static Data copyDerefData(Data dereferencedData) {
         if (dereferencedData instanceof ApacheData) {
             // need to make a copy of the Data
             ApacheData ad = (ApacheData)dereferencedData;
             XMLSignatureInput xsi = ad.getXMLSignatureInput();
             if (xsi.isNodeSet()) {
                 try {
                     final Set<Node> s = xsi.getNodeSet();
                     return new NodeSetData() {
                         public Iterator<Node> iterator() { return s.iterator(); }
                     };
                 } catch (Exception e) {
                     // LOG a warning
                     LOG.warn("cannot cache dereferenced data: " + e);
                     return null;
                 }
             } else if (xsi.isElement()) {
                 return new DOMSubTreeData
                     (xsi.getSubNode(), xsi.isExcludeComments());
             } else if (xsi.isOctetStream() || xsi.isByteArray()) {
                 try {
                     return new OctetStreamData
                         (xsi.getOctetStream(), xsi.getSourceURI(),
                          xsi.getMIMEType());
                 } catch (IOException ioe) {
                     // LOG a warning
                     LOG.warn("cannot cache dereferenced data: " + ioe);
                     return null;
                 }
             }
         }
         return dereferencedData;
     }
 }
	/**
	* 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
	* under the License.
	*/
	/*
	* Portions copyright 2005 Sun Microsystems, Inc. All rights reserved.
	*/
	/*
	* ===========================================================================
	*
	* (C) Copyright IBM Corp. 2003 All Rights Reserved.
	*
	* ===========================================================================
	*/
	/*
	* $Id$
	*/
	package org.apache.jcp.xml.dsig.internal.dom;

	import javax.xml.crypto.*;
	import javax.xml.crypto.dsig.*;
	import javax.xml.crypto.dom.DOMCryptoContext;
	import javax.xml.crypto.dom.DOMURIReference;

	import java.io.*;
	import java.net.URI;
	import java.net.URISyntaxException;
	import java.security.*;
	import java.util.*;

	import org.w3c.dom.Attr;
	import org.w3c.dom.Document;
	import org.w3c.dom.Element;
	import org.w3c.dom.Node;

	import org.apache.xml.security.utils.XMLUtils;

	import org.apache.jcp.xml.dsig.internal.DigesterOutputStream;
	import org.apache.xml.security.algorithms.MessageDigestAlgorithm;
	import org.apache.xml.security.signature.XMLSignatureInput;
	import org.apache.xml.security.utils.UnsyncBufferedOutputStream;

	/**
	* DOM-based implementation of Reference.
	*
	*/
	public final class DOMReference extends DOMStructure
	implements Reference, DOMURIReference {

	/**
	* The maximum number of transforms per reference, if secure validation is enabled.
	*/
	public static final int MAXIMUM_TRANSFORM_COUNT = 5;

	/**
	* Look up useC14N11 system property. If true, an explicit C14N11 transform
	* will be added if necessary when generating the signature. See section
	* 3.1.1 of http://www.w3.org/2007/xmlsec/Drafts/xmldsig-core/ for more info.
	*
	* If true, overrides the same property if set in the XMLSignContext.
	*/
	private static boolean useC14N11 =
	AccessController.doPrivileged((PrivilegedAction<Boolean>)
	() -> Boolean.getBoolean("com.sun.org.apache.xml.internal.security.useC14N11"));

	private static final org.slf4j.Logger LOG =
	org.slf4j.LoggerFactory.getLogger(DOMReference.class);

	private final DigestMethod digestMethod;
	private final String id;
	private final List<Transform> transforms;
	private List<Transform> allTransforms;
	private final Data appliedTransformData;
	private Attr here;
	private final String uri;
	private final String type;
	private byte[] digestValue;
	private byte[] calcDigestValue;
	private Element refElem;
	private boolean digested = false;
	private boolean validated = false;
	private boolean validationStatus;
	private Data derefData;
	private InputStream dis;
	private MessageDigest md;
	private Provider provider;

	/**
	* Creates a <code>Reference</code> from the specified parameters.
	*
	* @param uri the URI (may be null)
	* @param type the type (may be null)
	* @param dm the digest method
	* @param transforms a list of {@link Transform}s. The list
	* is defensively copied to protect against subsequent modification.
	* May be <code>null</code> or empty.
	* @param id the reference ID (may be <code>null</code>)
	* @throws NullPointerException if <code>dm</code> is <code>null</code>
	* @throws ClassCastException if any of the <code>transforms</code> are
	* not of type <code>Transform</code>
	*/
	public DOMReference(String uri, String type, DigestMethod dm,
	List<? extends Transform> transforms, String id,
	Provider provider)
	{
	this(uri, type, dm, null, null, transforms, id, null, provider);
	}

	public DOMReference(String uri, String type, DigestMethod dm,
	List<? extends Transform> appliedTransforms,
	Data result, List<? extends Transform> transforms,
	String id, Provider provider)
	{
	this(uri, type, dm, appliedTransforms,
	result, transforms, id, null, provider);
	}

	public DOMReference(String uri, String type, DigestMethod dm,
	List<? extends Transform> appliedTransforms,
	Data result, List<? extends Transform> transforms,
	String id, byte[] digestValue, Provider provider)
	{
	if (dm == null) {
	throw new NullPointerException("DigestMethod must be non-null");
	}
	if (appliedTransforms == null) {
	this.allTransforms = new ArrayList<>();
	} else {
	this.allTransforms = new ArrayList<>(appliedTransforms);
	for (int i = 0, size = this.allTransforms.size(); i < size; i++) {
	if (!(this.allTransforms.get(i) instanceof Transform)) {
	throw new ClassCastException
	("appliedTransforms["+i+"] is not a valid type");
	}
	}
	}
	if (transforms == null) {
	this.transforms = Collections.emptyList();
	} else {
	this.transforms = new ArrayList<>(transforms);
	for (int i = 0, size = this.transforms.size(); i < size; i++) {
	if (!(this.transforms.get(i) instanceof Transform)) {
	throw new ClassCastException
	("transforms["+i+"] is not a valid type");
	}
	}
	this.allTransforms.addAll(this.transforms);
	}
	this.digestMethod = dm;
	this.uri = uri;
	if (uri != null && !uri.isEmpty()) {
	try {
	new URI(uri);
	} catch (URISyntaxException e) {
	throw new IllegalArgumentException(e.getMessage());
	}
	}
	this.type = type;
	this.id = id;
	if (digestValue != null) {
	this.digestValue = digestValue.clone();
	this.digested = true;
	}
	this.appliedTransformData = result;
	this.provider = provider;
	}

	/**
	* Creates a <code>DOMReference</code> from an element.
	*
	* @param refElem a Reference element
	*/
	public DOMReference(Element refElem, XMLCryptoContext context,
	Provider provider)
	throws MarshalException
	{
	boolean secVal = Utils.secureValidation(context);

	// unmarshal Transforms, if specified
	Element nextSibling = DOMUtils.getFirstChildElement(refElem);
	List<Transform> newTransforms = new ArrayList<>(MAXIMUM_TRANSFORM_COUNT);
	if ("Transforms".equals(nextSibling.getLocalName())
	&& XMLSignature.XMLNS.equals(nextSibling.getNamespaceURI())) {
	Element transformElem = DOMUtils.getFirstChildElement(nextSibling,
	"Transform",
	XMLSignature.XMLNS);
	newTransforms.add(new DOMTransform(transformElem, context, provider));
	transformElem = DOMUtils.getNextSiblingElement(transformElem);
	while (transformElem != null) {
	String localName = transformElem.getLocalName();
	String namespace = transformElem.getNamespaceURI();
	if (!"Transform".equals(localName) \|\| !XMLSignature.XMLNS.equals(namespace)) {
	throw new MarshalException(
	"Invalid element name: " + localName +
	", expected Transform");
	}
	newTransforms.add
	(new DOMTransform(transformElem, context, provider));
	if (secVal && newTransforms.size() > MAXIMUM_TRANSFORM_COUNT) {
	String error = "A maxiumum of " + MAXIMUM_TRANSFORM_COUNT + " "
	+ "transforms per Reference are allowed with secure validation";
	throw new MarshalException(error);
	}
	transformElem = DOMUtils.getNextSiblingElement(transformElem);
	}
	nextSibling = DOMUtils.getNextSiblingElement(nextSibling);
	}
	if (!"DigestMethod".equals(nextSibling.getLocalName())
	&& XMLSignature.XMLNS.equals(nextSibling.getNamespaceURI())) {
	throw new MarshalException("Invalid element name: " +
	nextSibling.getLocalName() +
	", expected DigestMethod");
	}

	// unmarshal DigestMethod
	Element dmElem = nextSibling;
	this.digestMethod = DOMDigestMethod.unmarshal(dmElem);
	String digestMethodAlgorithm = this.digestMethod.getAlgorithm();
	if (secVal
	&& MessageDigestAlgorithm.ALGO_ID_DIGEST_NOT_RECOMMENDED_MD5.equals(digestMethodAlgorithm)) {
	throw new MarshalException(
	"It is forbidden to use algorithm " + digestMethod + " when secure validation is enabled"
	);
	}

	// unmarshal DigestValue
	Element dvElem = DOMUtils.getNextSiblingElement(dmElem, "DigestValue", XMLSignature.XMLNS);
	String content = XMLUtils.getFullTextChildrenFromNode(dvElem);
	this.digestValue = XMLUtils.decode(content);

	// check for extra elements
	if (DOMUtils.getNextSiblingElement(dvElem) != null) {
	throw new MarshalException(
	"Unexpected element after DigestValue element");
	}

	// unmarshal attributes
	this.uri = DOMUtils.getAttributeValue(refElem, "URI");

	Attr attr = refElem.getAttributeNodeNS(null, "Id");
	if (attr != null) {
	this.id = attr.getValue();
	refElem.setIdAttributeNode(attr, true);
	} else {
	this.id = null;
	}

	this.type = DOMUtils.getAttributeValue(refElem, "Type");
	this.here = refElem.getAttributeNodeNS(null, "URI");
	this.refElem = refElem;
	this.transforms = newTransforms;
	this.allTransforms = transforms;
	this.appliedTransformData = null;
	this.provider = provider;
	}

	public DigestMethod getDigestMethod() {
	return digestMethod;
	}

	public String getId() {
	return id;
	}

	public String getURI() {
	return uri;
	}

	public String getType() {
	return type;
	}

	public List<Transform> getTransforms() {
	return Collections.unmodifiableList(allTransforms);
	}

	public byte[] getDigestValue() {
	return digestValue == null ? null : digestValue.clone();
	}

	public byte[] getCalculatedDigestValue() {
	return calcDigestValue == null ? null
	: calcDigestValue.clone();
	}

	@Override
	public void marshal(Node parent, String dsPrefix, DOMCryptoContext context)
	throws MarshalException
	{
	LOG.debug("Marshalling Reference");
	Document ownerDoc = DOMUtils.getOwnerDocument(parent);

	refElem = DOMUtils.createElement(ownerDoc, "Reference",
	XMLSignature.XMLNS, dsPrefix);

	// set attributes
	DOMUtils.setAttributeID(refElem, "Id", id);
	DOMUtils.setAttribute(refElem, "URI", uri);
	DOMUtils.setAttribute(refElem, "Type", type);

	// create and append Transforms element
	if (!allTransforms.isEmpty()) {
	Element transformsElem = DOMUtils.createElement(ownerDoc,
	"Transforms",
	XMLSignature.XMLNS,
	dsPrefix);
	refElem.appendChild(transformsElem);
	for (Transform transform : allTransforms) {
	((DOMStructure)transform).marshal(transformsElem,
	dsPrefix, context);
	}
	}

	// create and append DigestMethod element
	((DOMDigestMethod)digestMethod).marshal(refElem, dsPrefix, context);

	// create and append DigestValue element
	LOG.debug("Adding digestValueElem");
	Element digestValueElem = DOMUtils.createElement(ownerDoc,
	"DigestValue",
	XMLSignature.XMLNS,
	dsPrefix);
	if (digestValue != null) {
	digestValueElem.appendChild
	(ownerDoc.createTextNode(XMLUtils.encodeToString(digestValue)));
	}
	refElem.appendChild(digestValueElem);

	parent.appendChild(refElem);
	here = refElem.getAttributeNodeNS(null, "URI");
	}

	public void digest(XMLSignContext signContext)
	throws XMLSignatureException
	{
	Data data = null;
	if (appliedTransformData == null) {
	data = dereference(signContext);
	} else {
	data = appliedTransformData;
	}
	digestValue = transform(data, signContext);

	// insert digestValue into DigestValue element
	String encodedDV = XMLUtils.encodeToString(digestValue);
	LOG.debug("Reference object uri = {}", uri);
	Element digestElem = DOMUtils.getLastChildElement(refElem);
	if (digestElem == null) {
	throw new XMLSignatureException("DigestValue element expected");
	}
	DOMUtils.removeAllChildren(digestElem);
	digestElem.appendChild
	(refElem.getOwnerDocument().createTextNode(encodedDV));

	digested = true;
	LOG.debug("Reference digesting completed");
	}

	public boolean validate(XMLValidateContext validateContext)
	throws XMLSignatureException
	{
	if (validateContext == null) {
	throw new NullPointerException("validateContext cannot be null");
	}
	if (validated) {
	return validationStatus;
	}
	Data data = dereference(validateContext);
	calcDigestValue = transform(data, validateContext);

	if (LOG.isDebugEnabled()) {
	LOG.debug("Expected digest: " + XMLUtils.encodeToString(digestValue));
	LOG.debug("Actual digest: " + XMLUtils.encodeToString(calcDigestValue));
	}

	validationStatus = Arrays.equals(digestValue, calcDigestValue);
	validated = true;
	return validationStatus;
	}

	public Data getDereferencedData() {
	return derefData;
	}

	public InputStream getDigestInputStream() {
	return dis;
	}

	private Data dereference(XMLCryptoContext context)
	throws XMLSignatureException
	{
	Data data = null;

	// use user-specified URIDereferencer if specified; otherwise use deflt
	URIDereferencer deref = context.getURIDereferencer();
	if (deref == null) {
	deref = DOMURIDereferencer.INSTANCE;
	}
	try {
	data = deref.dereference(this, context);
	LOG.debug("URIDereferencer class name: {}", deref.getClass().getName());
	LOG.debug("Data class name: {}", data.getClass().getName());
	} catch (URIReferenceException ure) {
	throw new XMLSignatureException(ure);
	}

	return data;
	}

	private byte[] transform(Data dereferencedData,
	XMLCryptoContext context)
	throws XMLSignatureException
	{
	if (md == null) {
	try {
	md = MessageDigest.getInstance
	(((DOMDigestMethod)digestMethod).getMessageDigestAlgorithm());
	} catch (NoSuchAlgorithmException nsae) {
	throw new XMLSignatureException(nsae);
	}
	}
	md.reset();
	DigesterOutputStream dos;
	Boolean cache = (Boolean)
	context.getProperty("javax.xml.crypto.dsig.cacheReference");
	if (cache != null && cache) {
	this.derefData = copyDerefData(dereferencedData);
	dos = new DigesterOutputStream(md, true);
	} else {
	dos = new DigesterOutputStream(md);
	}
	Data data = dereferencedData;
	try (OutputStream os = new UnsyncBufferedOutputStream(dos)) {
	for (int i = 0, size = transforms.size(); i < size; i++) {
	DOMTransform transform = (DOMTransform)transforms.get(i);
	if (i < size - 1) {
	data = transform.transform(data, context);
	} else {
	data = transform.transform(data, context, os);
	}
	}

	if (data != null) {
	XMLSignatureInput xi;
	// explicitly use C14N 1.1 when generating signature
	// first check system property, then context property
	boolean c14n11 = useC14N11;
	String c14nalg = CanonicalizationMethod.INCLUSIVE;
	if (context instanceof XMLSignContext) {
	if (!c14n11) {
	Boolean prop = (Boolean)context.getProperty
	("org.apache.xml.security.useC14N11");
	c14n11 = prop != null && prop;
	if (c14n11) {
	c14nalg = "http://www.w3.org/2006/12/xml-c14n11";
	}
	} else {
	c14nalg = "http://www.w3.org/2006/12/xml-c14n11";
	}
	}
	if (data instanceof ApacheData) {
	xi = ((ApacheData)data).getXMLSignatureInput();
	} else if (data instanceof OctetStreamData) {
	xi = new XMLSignatureInput
	(((OctetStreamData)data).getOctetStream());
	} else if (data instanceof NodeSetData) {
	TransformService spi = null;
	if (provider == null) {
	spi = TransformService.getInstance(c14nalg, "DOM");
	} else {
	try {
	spi = TransformService.getInstance(c14nalg, "DOM", provider);
	} catch (NoSuchAlgorithmException nsae) {
	spi = TransformService.getInstance(c14nalg, "DOM");
	}
	}
	data = spi.transform(data, context);
	xi = new XMLSignatureInput
	(((OctetStreamData)data).getOctetStream());
	} else {
	throw new XMLSignatureException("unrecognized Data type");
	}

	boolean secVal = Utils.secureValidation(context);
	xi.setSecureValidation(secVal);
	if (context instanceof XMLSignContext && c14n11
	&& !xi.isOctetStream() && !xi.isOutputStreamSet()) {
	TransformService spi = null;
	if (provider == null) {
	spi = TransformService.getInstance(c14nalg, "DOM");
	} else {
	try {
	spi = TransformService.getInstance(c14nalg, "DOM", provider);
	} catch (NoSuchAlgorithmException nsae) {
	spi = TransformService.getInstance(c14nalg, "DOM");
	}
	}

	DOMTransform t = new DOMTransform(spi);
	Element transformsElem = null;
	String dsPrefix = DOMUtils.getSignaturePrefix(context);
	if (allTransforms.isEmpty()) {
	transformsElem = DOMUtils.createElement(
	refElem.getOwnerDocument(),
	"Transforms", XMLSignature.XMLNS, dsPrefix);
	refElem.insertBefore(transformsElem,
	DOMUtils.getFirstChildElement(refElem));
	} else {
	transformsElem = DOMUtils.getFirstChildElement(refElem);
	}
	t.marshal(transformsElem, dsPrefix,
	(DOMCryptoContext)context);
	allTransforms.add(t);
	xi.updateOutputStream(os, true);
	} else {
	xi.updateOutputStream(os);
	}
	}
	os.flush();
	if (cache != null && cache) {
	this.dis = dos.getInputStream();
	}
	return dos.getDigestValue();
	} catch (NoSuchAlgorithmException e) {
	throw new XMLSignatureException(e);
	} catch (TransformException e) {
	throw new XMLSignatureException(e);
	} catch (MarshalException e) {
	throw new XMLSignatureException(e);
	} catch (IOException e) {
	throw new XMLSignatureException(e);
	} catch (org.apache.xml.security.c14n.CanonicalizationException e) {
	throw new XMLSignatureException(e);
	} finally { //NOPMD
	if (dos != null) {
	try {
	dos.close();
	} catch (IOException e) {
	throw new XMLSignatureException(e);
	}
	}
	}
	}

	public Node getHere() {
	return here;
	}

	@Override
	public boolean equals(Object o) {
	if (this == o) {
	return true;
	}

	if (!(o instanceof Reference)) {
	return false;
	}
	Reference oref = (Reference)o;

	boolean idsEqual = id == null ? oref.getId() == null
	: id.equals(oref.getId());
	boolean urisEqual = uri == null ? oref.getURI() == null
	: uri.equals(oref.getURI());
	boolean typesEqual = type == null ? oref.getType() == null
	: type.equals(oref.getType());
	boolean digestValuesEqual =
	Arrays.equals(digestValue, oref.getDigestValue());

	return digestMethod.equals(oref.getDigestMethod()) && idsEqual &&
	urisEqual && typesEqual &&
	allTransforms.equals(oref.getTransforms()) && digestValuesEqual;
	}

	@Override
	public int hashCode() {
	int result = 17;
	if (id != null) {
	result = 31 * result + id.hashCode();
	}
	if (uri != null) {
	result = 31 * result + uri.hashCode();
	}
	if (type != null) {
	result = 31 * result + type.hashCode();
	}
	if (digestValue != null) {
	result = 31 * result + Arrays.hashCode(digestValue);
	}
	result = 31 * result + digestMethod.hashCode();
	result = 31 * result + allTransforms.hashCode();

	return result;
	}

	boolean isDigested() {
	return digested;
	}

	private static Data copyDerefData(Data dereferencedData) {
	if (dereferencedData instanceof ApacheData) {
	// need to make a copy of the Data
	ApacheData ad = (ApacheData)dereferencedData;
	XMLSignatureInput xsi = ad.getXMLSignatureInput();
	if (xsi.isNodeSet()) {
	try {
	final Set<Node> s = xsi.getNodeSet();
	return new NodeSetData() {
	public Iterator<Node> iterator() { return s.iterator(); }
	};
	} catch (Exception e) {
	// LOG a warning
	LOG.warn("cannot cache dereferenced data: " + e);
	return null;
	}
	} else if (xsi.isElement()) {
	return new DOMSubTreeData
	(xsi.getSubNode(), xsi.isExcludeComments());
	} else if (xsi.isOctetStream() \|\| xsi.isByteArray()) {
	try {
	return new OctetStreamData
	(xsi.getOctetStream(), xsi.getSourceURI(),
	xsi.getMIMEType());
	} catch (IOException ioe) {
	// LOG a warning
	LOG.warn("cannot cache dereferenced data: " + ioe);
	return null;
	}
	}
	}
	return dereferencedData;
	}
	}