eu.europa.esig.dss.cades.TimeStampTokenProductionComparator Maven / Gradle / Ivy

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/**
 * DSS - Digital Signature Services
 * Copyright (C) 2015 European Commission, provided under the CEF programme
 * 
 * This file is part of the "DSS - Digital Signature Services" project.
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library 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 library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */
package eu.europa.esig.dss.cades;

import eu.europa.esig.dss.spi.DSSASN1Utils;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.tsp.TimeStampToken;

import java.io.Serializable;
import java.util.Comparator;

/**
 * The class used to compare production time of {@code TimeStampToken}s
 * Class checks the production time of timestamps and their covered data
 * 
 * The method compare() returns 
 *     -1 if the {@code timeStampTokenOne} was created before {@code timeStampTokenTwo}
 *     0 if TimeStampTokens were created in the same
 *     1 if the {@code timeStampTokenOne} was created after {@code timeStampTokenTwo}
 *     
 */
public class TimeStampTokenProductionComparator implements Comparator, Serializable {

	private static final long serialVersionUID = 4125423970411266861L;

	/**
	 * Default constructor
	 */
	public TimeStampTokenProductionComparator() {
		// empty
	}

	@Override
	public int compare(TimeStampToken timeStampTokenOne, TimeStampToken timeStampTokenTwo) {
		int result = compareByGenerationTime(timeStampTokenOne, timeStampTokenTwo);
		if (result == 0) {			
			result = compareByHashTableSize(timeStampTokenOne, timeStampTokenTwo);
		}
		return result;
	}
	
	/**
	 * Returns TRUE if {@code timeStampTokenOne} was created after {@code timeStampTokenTwo}
	 * @param timeStampTokenOne {@link TimeStampToken}
	 * @param timeStampTokenTwo {@link TimeStampToken}
	 * @return TRUE if the first {@link TimeStampToken} has been created after the second timestamp, FALSE otherwise
	 */
	public boolean after(TimeStampToken timeStampTokenOne, TimeStampToken timeStampTokenTwo) {
		return compare(timeStampTokenOne, timeStampTokenTwo) > 0;
	}
	
	private int compareByGenerationTime(TimeStampToken tst1, TimeStampToken tst2) {
		return DSSASN1Utils.getTimeStampTokenGenerationTime(tst1).compareTo(DSSASN1Utils.getTimeStampTokenGenerationTime(tst2));
	}

	private int compareByHashTableSize(TimeStampToken tst1, TimeStampToken tst2) {
		ASN1Sequence atsHashIndexOne = CMSUtils.getAtsHashIndex(tst1.getUnsignedAttributes());
		ASN1Sequence atsHashIndexTwo = CMSUtils.getAtsHashIndex(tst2.getUnsignedAttributes());

		if (atsHashIndexOne != null && atsHashIndexTwo != null) {
			int hashTableSizeOne = getHashTableSize(atsHashIndexOne);
			int hashTableSizeTwo = getHashTableSize(atsHashIndexTwo);
			if (hashTableSizeOne < hashTableSizeTwo) {
				return -1;
			} else if (hashTableSizeOne > hashTableSizeTwo) {
				return 1;
			}
		} else if (atsHashIndexOne != null) {
			return 1;
		} else if (atsHashIndexTwo != null) {
			return -1;
		}
		return 0;
	}

	private int getHashTableSize(ASN1Sequence derSequence) {
		int recordsNumber = 0;
		for (int ii = 0; ii < derSequence.size(); ii++) {
			ASN1Sequence derEncodedSequence = (ASN1Sequence) derSequence.getObjectAt(ii);
			recordsNumber += derEncodedSequence.size();
		}
		return recordsNumber;
	}

}