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/*
This file is part of the iText (R) project.
Copyright (c) 1998-2017 iText Group NV
Authors: Bruno Lowagie, Paulo Soares, et al.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License version 3
as published by the Free Software Foundation with the addition of the
following permission added to Section 15 as permitted in Section 7(a):
FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
OF THIRD PARTY RIGHTS
This program 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 Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program; if not, see http://www.gnu.org/licenses or write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA, 02110-1301 USA, or download the license from the following URL:
http://itextpdf.com/terms-of-use/
The interactive user interfaces in modified source and object code versions
of this program must display Appropriate Legal Notices, as required under
Section 5 of the GNU Affero General Public License.
In accordance with Section 7(b) of the GNU Affero General Public License,
a covered work must retain the producer line in every PDF that is created
or manipulated using iText.
You can be released from the requirements of the license by purchasing
a commercial license. Buying such a license is mandatory as soon as you
develop commercial activities involving the iText software without
disclosing the source code of your own applications.
These activities include: offering paid services to customers as an ASP,
serving PDFs on the fly in a web application, shipping iText with a closed
source product.
For more information, please contact iText Software Corp. at this
address: [email protected]
*/
package com.itextpdf.signatures;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.net.URL;
import java.security.GeneralSecurityException;
import java.security.cert.X509CRL;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
/**
* Class that allows you to verify a certificate against
* one or more Certificate Revocation Lists.
*/
public class CRLVerifier extends RootStoreVerifier {
/** The Logger instance */
protected static final Logger LOGGER = LoggerFactory.getLogger(CRLVerifier.class);
/** The list of CRLs to check for revocation date. */
List crls;
/**
* Creates a CRLVerifier instance.
* @param verifier the next verifier in the chain
* @param crls a list of CRLs
*/
public CRLVerifier(CertificateVerifier verifier, List crls) {
super(verifier);
this.crls = crls;
}
/**
* Verifies if a a valid CRL is found for the certificate.
* If this method returns false, it doesn't mean the certificate isn't valid.
* It means we couldn't verify it against any CRL that was available.
* @param signCert the certificate that needs to be checked
* @param issuerCert its issuer
* @return a list of VerificationOK objects.
* The list will be empty if the certificate couldn't be verified.
* @see com.itextpdf.signatures.RootStoreVerifier#verify(java.security.cert.X509Certificate, java.security.cert.X509Certificate, java.util.Date)
*/
public List verify(X509Certificate signCert, X509Certificate issuerCert, Date signDate)
throws GeneralSecurityException, IOException {
List result = new ArrayList<>();
int validCrlsFound = 0;
// first check the list of CRLs that is provided
if (crls != null) {
for (X509CRL crl : crls) {
if (verify(crl, signCert, issuerCert, signDate))
validCrlsFound++;
}
}
// then check online if allowed
boolean online = false;
if (onlineCheckingAllowed && validCrlsFound == 0) {
if (verify(getCRL(signCert, issuerCert), signCert, issuerCert, signDate)) {
validCrlsFound++;
online = true;
}
}
// show how many valid CRLs were found
LOGGER.info("Valid CRLs found: " + validCrlsFound);
if (validCrlsFound > 0) {
result.add(new VerificationOK(signCert, this.getClass(), "Valid CRLs found: " + validCrlsFound + (online ? " (online)" : "")));
}
if (verifier != null)
result.addAll(verifier.verify(signCert, issuerCert, signDate));
// verify using the previous verifier in the chain (if any)
return result;
}
/**
* Verifies a certificate against a single CRL.
* @param crl the Certificate Revocation List
* @param signCert a certificate that needs to be verified
* @param issuerCert its issuer
* @param signDate the sign date
* @return true if the verification succeeded
* @throws GeneralSecurityException
*/
public boolean verify(X509CRL crl, X509Certificate signCert, X509Certificate issuerCert, Date signDate) throws GeneralSecurityException {
if (crl == null || signDate == SignUtils.UNDEFINED_TIMESTAMP_DATE)
return false;
// We only check CRLs valid on the signing date for which the issuer matches
if (crl.getIssuerX500Principal().equals(signCert.getIssuerX500Principal())
&& signDate.after(crl.getThisUpdate()) && signDate.before(crl.getNextUpdate())) {
// the signing certificate may not be revoked
if (isSignatureValid(crl, issuerCert) && crl.isRevoked(signCert)) {
throw new VerificationException(signCert, "The certificate has been revoked.");
}
return true;
}
return false;
}
/**
* Fetches a CRL for a specific certificate online (without further checking).
* @param signCert the certificate
* @param issuerCert its issuer
* @return an X509CRL object
*/
public X509CRL getCRL(X509Certificate signCert, X509Certificate issuerCert) {
if (issuerCert == null)
issuerCert = signCert;
try {
// gets the URL from the certificate
String crlurl = CertificateUtil.getCRLURL(signCert);
if (crlurl == null)
return null;
LOGGER.info("Getting CRL from " + crlurl);
return (X509CRL) SignUtils.parseCrlFromStream(new URL(crlurl).openStream());
}
catch(IOException e) {
return null;
}
catch(GeneralSecurityException e) {
return null;
}
}
/**
* Checks if a CRL verifies against the issuer certificate or a trusted anchor.
* @param crl the CRL
* @param crlIssuer the trusted anchor
* @return true if the CRL can be trusted
*/
public boolean isSignatureValid(X509CRL crl, X509Certificate crlIssuer) {
// check if the CRL was issued by the issuer
if (crlIssuer != null) {
try {
crl.verify(crlIssuer.getPublicKey());
return true;
} catch (GeneralSecurityException e) {
LOGGER.warn("CRL not issued by the same authority as the certificate that is being checked");
}
}
// check the CRL against trusted anchors
if (rootStore == null)
return false;
try {
// loop over the certificate in the key store
for (X509Certificate anchor : SignUtils.getCertificates(rootStore)) {
try {
// check if the crl was signed by a trusted party (indirect CRLs)
crl.verify(anchor.getPublicKey());
return true;
} catch (GeneralSecurityException e) {
continue;
}
}
}
catch (GeneralSecurityException e) {
return false;
}
return false;
}
}
