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	/*
	* Copyright (c) 2011, 2015, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code 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 General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package sun.security.provider.certpath;

	import java.io.IOException;
	import java.math.BigInteger;
	import java.security.cert.Certificate;
	import java.security.cert.X509Certificate;
	import java.security.cert.X509CertSelector;
	import java.security.cert.CertificateException;
	import java.util.Arrays;
	import java.util.Date;

	import sun.security.util.Debug;
	import sun.security.util.DerInputStream;
	import sun.security.x509.SerialNumber;
	import sun.security.x509.AuthorityKeyIdentifierExtension;

	/**
	* An adaptable X509 certificate selector for forward certification path
	* building. This selector overrides the default X509CertSelector matching
	* rules for the subjectKeyIdentifier and serialNumber criteria, and adds
	* additional rules for certificate validity.
	*
	* @since 1.7
	*/
	class AdaptableX509CertSelector extends X509CertSelector {

	private static final Debug debug = Debug.getInstance("certpath");

	// The start date of a validity period.
	private Date startDate;

	// The end date of a validity period.
	private Date endDate;

	// The subject key identifier
	private byte[] ski;

	// The serial number
	private BigInteger serial;

	/**
	* Sets the criterion of the X509Certificate validity period.
	*
	* Normally, we may not have to check that a certificate validity period
	* must fall within its issuer's certificate validity period. However,
	* when we face root CA key updates for version 1 certificates, according
	* to scheme of RFC 4210 or 2510, the validity periods should be checked
	* to determine the right issuer's certificate.
	*
	* Conservatively, we will only check the validity periods for version
	* 1 and version 2 certificates. For version 3 certificates, we can
	* determine the right issuer by authority and subject key identifier
	* extensions.
	*
	* @param startDate the start date of a validity period that must fall
	* within the certificate validity period for the X509Certificate
	* @param endDate the end date of a validity period that must fall
	* within the certificate validity period for the X509Certificate
	*/
	void setValidityPeriod(Date startDate, Date endDate) {
	this.startDate = startDate;
	this.endDate = endDate;
	}

	/**
	* This selector overrides the subjectKeyIdentifier matching rules of
	* X509CertSelector, so it throws IllegalArgumentException if this method
	* is ever called.
	*/
	@Override
	public void setSubjectKeyIdentifier(byte[] subjectKeyID) {
	throw new IllegalArgumentException();
	}

	/**
	* This selector overrides the serialNumber matching rules of
	* X509CertSelector, so it throws IllegalArgumentException if this method
	* is ever called.
	*/
	@Override
	public void setSerialNumber(BigInteger serial) {
	throw new IllegalArgumentException();
	}

	/**
	* Sets the subjectKeyIdentifier and serialNumber criteria from the
	* authority key identifier extension.
	*
	* The subjectKeyIdentifier criterion is set to the keyIdentifier field
	* of the extension, or null if it is empty. The serialNumber criterion
	* is set to the authorityCertSerialNumber field, or null if it is empty.
	*
	* Note that we do not set the subject criterion to the
	* authorityCertIssuer field of the extension. The caller MUST set
	* the subject criterion before calling match().
	*
	* @param ext the authorityKeyIdentifier extension
	* @throws IOException if there is an error parsing the extension
	*/
	void setSkiAndSerialNumber(AuthorityKeyIdentifierExtension ext)
	throws IOException {

	ski = null;
	serial = null;

	if (ext != null) {
	ski = ext.getEncodedKeyIdentifier();
	SerialNumber asn = (SerialNumber)ext.get(
	AuthorityKeyIdentifierExtension.SERIAL_NUMBER);
	if (asn != null) {
	serial = asn.getNumber();
	}
	// the subject criterion should be set by the caller
	}
	}

	/**
	* Decides whether a <code>Certificate</code> should be selected.
	*
	* This method overrides the matching rules for the subjectKeyIdentifier
	* and serialNumber criteria and adds additional rules for certificate
	* validity.
	*
	* For the purpose of compatibility, when a certificate is of
	* version 1 and version 2, or the certificate does not include
	* a subject key identifier extension, the selection criterion
	* of subjectKeyIdentifier will be disabled.
	*/
	@Override
	public boolean match(Certificate cert) {
	X509Certificate xcert = (X509Certificate)cert;

	// match subject key identifier
	if (!matchSubjectKeyID(xcert)) {
	return false;
	}

	// In practice, a CA may replace its root certificate and require that
	// the existing certificate is still valid, even if the AKID extension
	// does not match the replacement root certificate fields.
	//
	// Conservatively, we only support the replacement for version 1 and
	// version 2 certificate. As for version 3, the certificate extension
	// may contain sensitive information (for example, policies), the
	// AKID need to be respected to seek the exact certificate in case
	// of key or certificate abuse.
	int version = xcert.getVersion();
	if (serial != null && version > 2) {
	if (!serial.equals(xcert.getSerialNumber())) {
	return false;
	}
	}

	// Check the validity period for version 1 and 2 certificate.
	if (version < 3) {
	if (startDate != null) {
	try {
	xcert.checkValidity(startDate);
	} catch (CertificateException ce) {
	return false;
	}
	}
	if (endDate != null) {
	try {
	xcert.checkValidity(endDate);
	} catch (CertificateException ce) {
	return false;
	}
	}
	}


	if (!super.match(cert)) {
	return false;
	}

	return true;
	}

	/*
	* Match on subject key identifier extension value. These matching rules
	* are identical to X509CertSelector except that if the certificate does
	* not have a subject key identifier extension, it returns true.
	*/
	private boolean matchSubjectKeyID(X509Certificate xcert) {
	if (ski == null) {
	return true;
	}
	try {
	byte[] extVal = xcert.getExtensionValue("2.5.29.14");
	if (extVal == null) {
	if (debug != null) {
	debug.println("AdaptableX509CertSelector.match: "
	+ "no subject key ID extension. Subject: "
	+ xcert.getSubjectX500Principal());
	}
	return true;
	}
	DerInputStream in = new DerInputStream(extVal);
	byte[] certSubjectKeyID = in.getOctetString();
	if (certSubjectKeyID == null \|\|
	!Arrays.equals(ski, certSubjectKeyID)) {
	if (debug != null) {
	debug.println("AdaptableX509CertSelector.match: "
	+ "subject key IDs don't match. "
	+ "Expected: " + Arrays.toString(ski) + " "
	+ "Cert's: " + Arrays.toString(certSubjectKeyID));
	}
	return false;
	}
	} catch (IOException ex) {
	if (debug != null) {
	debug.println("AdaptableX509CertSelector.match: "
	+ "exception in subject key ID check");
	}
	return false;
	}
	return true;
	}

	@Override
	public Object clone() {
	AdaptableX509CertSelector copy =
	(AdaptableX509CertSelector)super.clone();
	if (startDate != null) {
	copy.startDate = (Date)startDate.clone();
	}

	if (endDate != null) {
	copy.endDate = (Date)endDate.clone();
	}

	if (ski != null) {
	copy.ski = ski.clone();
	}
	return copy;
	}
	}

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