AbstractODFSignatureService.java

/*
 * eID Applet Project.
 * Copyright (C) 2008-2009 FedICT.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License version
 * 3.0 as published by the Free Software Foundation.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, see 
 * http://www.gnu.org/licenses/.
 */
package be.fedict.eid.applet.service.signer.odf;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
import java.util.zip.ZipOutputStream;

import javax.xml.crypto.URIDereferencer;
import javax.xml.parsers.ParserConfigurationException;

import org.apache.commons.io.IOUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.xml.security.utils.Constants;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.xml.sax.SAXException;

import be.fedict.eid.applet.service.signer.AbstractXmlSignatureService;
import be.fedict.eid.applet.service.signer.DigestAlgo;
import be.fedict.eid.applet.service.signer.facets.KeyInfoSignatureFacet;
import be.fedict.eid.applet.service.signer.facets.XAdESSignatureFacet;

/**
 * Signature Service implementation for OpenDocument format signatures.
 * 
 * The signatures created with this class are accepted as valid signature within
 * OpenOffice.org 3.x. They probably don't get accepted by older OOo versions.
 * 
 * @see http://wiki.services.openoffice.org/wiki/Security/Digital_Signatures
 * 
 * @author fcorneli
 * 
 */
abstract public class AbstractODFSignatureService extends AbstractXmlSignatureService {

	private static final Log LOG = LogFactory.getLog(AbstractODFSignatureService.class);

	private final XAdESSignatureFacet xadesSignatureFacet;

	public AbstractODFSignatureService(DigestAlgo digestAlgo) {
		super(digestAlgo);
		addSignatureFacet(new ODFSignatureFacet(this, getSignatureDigestAlgorithm()));
		addSignatureFacet(new OpenOfficeSignatureFacet(getSignatureDigestAlgorithm()));
		this.xadesSignatureFacet = new XAdESSignatureFacet(getSignatureDigestAlgorithm());
		addSignatureFacet(this.xadesSignatureFacet);
		addSignatureFacet(new KeyInfoSignatureFacet(false, true, false));
	}

	/**
	 * Gives back the used XAdES signature facet. Allows for extra configuration
	 * of the XAdES elements.
	 * 
	 * @return
	 */
	protected XAdESSignatureFacet getXAdESSignatureFacet() {
		return this.xadesSignatureFacet;
	}

	/**
	 * Returns the URL of the ODF to be signed.
	 * 
	 * @return
	 */
	abstract protected URL getOpenDocumentURL();

	@Override
	protected final URIDereferencer getURIDereferencer() {
		URL odfUrl = getOpenDocumentURL();
		return new ODFURIDereferencer(odfUrl);
	}

	@Override
	protected String getSignatureDescription() {
		return "ODF Document";
	}

	@Override
	protected final OutputStream getSignedDocumentOutputStream() {
		LOG.debug("get signed document output stream");
		/*
		 * Create each time a new object; we want an empty output stream to
		 * start with.
		 */
		OutputStream signedDocumentOutputStream = new ODFSignedDocumentOutputStream();
		return signedDocumentOutputStream;
	}

	private class ODFSignedDocumentOutputStream extends ByteArrayOutputStream {

		@Override
		public void close() throws IOException {
			LOG.debug("close ODF signed document output stream");
			super.close();
			outputSignedOpenDocument(this.toByteArray());
		}
	}

	private void outputSignedOpenDocument(byte[] signatureData) throws IOException {
		LOG.debug("output signed open document");
		OutputStream signedOdfOutputStream = getSignedOpenDocumentOutputStream();
		if (null == signedOdfOutputStream) {
			throw new NullPointerException("signedOpenDocumentOutputStream is null");
		}
		/*
		 * Copy the original ODF content to the signed ODF package.
		 */
		ZipOutputStream zipOutputStream = new ZipOutputStream(signedOdfOutputStream);
		ZipInputStream zipInputStream = new ZipInputStream(this.getOpenDocumentURL().openStream());
		ZipEntry zipEntry;
		while (null != (zipEntry = zipInputStream.getNextEntry())) {
			if (!zipEntry.getName().equals(ODFUtil.SIGNATURE_FILE)) {
				zipOutputStream.putNextEntry(zipEntry);
				IOUtils.copy(zipInputStream, zipOutputStream);
			}
		}
		zipInputStream.close();
		/*
		 * Add the ODF XML signature file to the signed ODF package.
		 */
		zipEntry = new ZipEntry(ODFUtil.SIGNATURE_FILE);
		zipOutputStream.putNextEntry(zipEntry);
		IOUtils.write(signatureData, zipOutputStream);
		zipOutputStream.close();
	}

	/**
	 * The output stream to which to write the signed ODF file.
	 * 
	 * @return
	 */
	abstract protected OutputStream getSignedOpenDocumentOutputStream();

	public final String getFilesDigestAlgorithm() {
		/*
		 * No local files to digest.
		 */
		return null;
	}

	@Override
	protected final Document getEnvelopingDocument() throws ParserConfigurationException, IOException, SAXException {
		Document document = getODFSignatureDocument();
		if (null != document) {
			return document;
		}
		document = ODFUtil.getNewDocument();
		Element rootElement = document.createElementNS(ODFUtil.SIGNATURE_NS, ODFUtil.SIGNATURE_ELEMENT);
		rootElement.setAttributeNS(Constants.NamespaceSpecNS, "xmlns", ODFUtil.SIGNATURE_NS);
		document.appendChild(rootElement);
		return document;
	}

	/**
	 * Get the XML signature file from the ODF package
	 * 
	 * @return
	 * @throws IOException
	 * @throws ParserConfigurationException
	 * @throws SAXException
	 */
	private Document getODFSignatureDocument() throws IOException, ParserConfigurationException, SAXException {
		URL odfUrl = this.getOpenDocumentURL();

		InputStream inputStream = ODFUtil.findDataInputStream(odfUrl.openStream(), ODFUtil.SIGNATURE_FILE);
		if (null != inputStream) {
			return ODFUtil.loadDocument(inputStream);
		}
		return null;
	}
}