/**
* Copyright 2009 Google Inc.
*
* 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
* limitations under the License.
*
*/
package com.google.step2.xmlsimplesign;
import java.security.GeneralSecurityException;
import java.security.cert.CertPath;
import java.security.cert.CertPathValidator;
import java.security.cert.CertificateFactory;
import java.security.cert.PKIXParameters;
import java.security.cert.TrustAnchor;
import java.security.cert.X509Certificate;
import java.util.Collection;
import java.util.List;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import com.google.inject.Inject;
import com.google.step2.util.ExpiringLruCache;
import com.google.step2.util.TimeSource;
/**
* Verifies X.509 certificates.
*
* This makes heavy use of the JRE CertPath libraries. Documentation may be found at
* http://java.sun.com/j2se/1.5.0/docs/guide/security/certpath/CertPathProgGuide.html
*
* TODO: look for sane PKIXParameter certificate policy configuration.
*/
public class CachedCertPathValidator {
private static final Logger log = Logger.getLogger(CachedCertPathValidator.class.getName());
private static final String VALIDATOR_TYPE = "PKIX";
private static final String CERTIFICATE_TYPE = "X.509";
private static final int VALIDATION_CACHE_SIZE = 1024;
private static final long VALIDATION_CACHE_AGE_SECONDS = 10 * 60;
private final Set<TrustAnchor> trustRoots;
private final ExpiringLruCache<List<X509Certificate>, Boolean> validationCache;
private TimeSource timeSource = new TimeSource();
@Inject
public CachedCertPathValidator(TrustRootsProvider trustRoots) {
this(trustRoots.getTrustRoots());
}
/* visible for testing */
public CachedCertPathValidator(Collection<X509Certificate> trustRoots) {
this.trustRoots = createTrustRoots(trustRoots);
this.validationCache = new ExpiringLruCache<List<X509Certificate>, Boolean>(
VALIDATION_CACHE_SIZE);
}
private ImmutableSet<TrustAnchor> createTrustRoots(Collection<X509Certificate> trustRoots) {
List<TrustAnchor> anchors = Lists.newArrayList();
for (X509Certificate c : trustRoots) {
anchors.add(new TrustAnchor(c, null));
}
return ImmutableSet.copyOf(anchors);
}
public void setTimeSource(TimeSource timeSource) {
this.timeSource = timeSource;
validationCache.setTimeSource(timeSource);
}
public void validate(List<X509Certificate> certs) throws CertValidatorException {
// If a cert chain validates successfully, we cache it for several minutes. This improves
// performance dramatically (anywhere from 10x to 50x decrease in CPU usage when repeatedly
// verifying the same certificate chain.
if (validationCache.get(certs) != null) {
return;
}
validateNoCache(certs);
validationCache.put(certs, Boolean.TRUE, VALIDATION_CACHE_AGE_SECONDS);
}
private void validateNoCache(List<X509Certificate> certs) throws CertValidatorException {
try {
CertPathValidator validator = CertPathValidator.getInstance(VALIDATOR_TYPE);
PKIXParameters params = new PKIXParameters(trustRoots);
params.setDate(timeSource.now());
params.setRevocationEnabled(false);
CertificateFactory certFactory = CertificateFactory.getInstance(CERTIFICATE_TYPE);
CertPath certPath = certFactory.generateCertPath(certs);
validator.validate(certPath, params);
} catch (GeneralSecurityException e) {
log.log(Level.WARNING, "Certificate validation failed, certs were: " + certs, e);
throw new CertValidatorException("Certificate validation failure", e);
}
}
}