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	/*
	* Copyright (c) 2002, 2019, 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.validator;

	import java.util.*;

	import java.security.cert.*;

	import sun.security.x509.NetscapeCertTypeExtension;

	/**
	* Class to check if an end entity cert is suitable for use in some
	* context.<p>
	*
	* This class is used internally by the validator. Currently, seven variants
	* are supported defined as VAR_XXX constants in the Validator class:
	* <ul>
	* <li>Generic. No additional requirements, all certificates are ok.
	*
	* <li>TLS server. Requires that a String parameter is passed to
	* validate that specifies the name of the TLS key exchange algorithm
	* in use. See the JSSE X509TrustManager spec for details.
	*
	* <li>TLS client.
	*
	* <li>Code signing.
	*
	* <li>JCE code signing. Some early JCE code signing certs issued to
	* providers had incorrect extensions. In this mode the checks
	* are relaxed compared to standard code signing checks in order to
	* allow these certificates to pass.
	*
	* <li>Plugin code signing. WebStart and Plugin require their own variant
	* which is equivalent to VAR_CODE_SIGNING with additional checks for
	* compatibility/special cases. See also PKIXValidator.
	*
	* <li>TSA Server (see RFC 3161, section 2.3).
	*
	* </ul>
	*
	* @author Andreas Sterbenz
	*/
	class EndEntityChecker {

	// extended key usage OIDs for TLS server, TLS client, code signing
	// and any usage

	private final static String OID_EXTENDED_KEY_USAGE =
	SimpleValidator.OID_EXTENDED_KEY_USAGE;

	private final static String OID_EKU_TLS_SERVER = "1.3.6.1.5.5.7.3.1";

	private final static String OID_EKU_TLS_CLIENT = "1.3.6.1.5.5.7.3.2";

	private final static String OID_EKU_CODE_SIGNING = "1.3.6.1.5.5.7.3.3";

	private final static String OID_EKU_TIME_STAMPING = "1.3.6.1.5.5.7.3.8";

	private final static String OID_EKU_ANY_USAGE = "2.5.29.37.0";

	// the Netscape Server-Gated-Cryptography EKU extension OID
	private final static String OID_EKU_NS_SGC = "2.16.840.1.113730.4.1";

	// the Microsoft Server-Gated-Cryptography EKU extension OID
	private final static String OID_EKU_MS_SGC = "1.3.6.1.4.1.311.10.3.3";

	// the recognized extension OIDs
	private final static String OID_SUBJECT_ALT_NAME = "2.5.29.17";

	private final static String NSCT_SSL_CLIENT =
	NetscapeCertTypeExtension.SSL_CLIENT;

	private final static String NSCT_SSL_SERVER =
	NetscapeCertTypeExtension.SSL_SERVER;

	private final static String NSCT_CODE_SIGNING =
	NetscapeCertTypeExtension.OBJECT_SIGNING;

	// bit numbers in the key usage extension
	private final static int KU_SIGNATURE = 0;
	private final static int KU_KEY_ENCIPHERMENT = 2;
	private final static int KU_KEY_AGREEMENT = 4;

	// TLS key exchange algorithms requiring digitalSignature key usage
	private final static Collection<String> KU_SERVER_SIGNATURE =
	Arrays.asList("DHE_DSS", "DHE_RSA", "ECDHE_ECDSA", "ECDHE_RSA",
	"RSA_EXPORT", "UNKNOWN");

	// TLS key exchange algorithms requiring keyEncipherment key usage
	private final static Collection<String> KU_SERVER_ENCRYPTION =
	Arrays.asList("RSA");

	// TLS key exchange algorithms requiring keyAgreement key usage
	private final static Collection<String> KU_SERVER_KEY_AGREEMENT =
	Arrays.asList("DH_DSS", "DH_RSA", "ECDH_ECDSA", "ECDH_RSA");

	// variant of this end entity cert checker
	private final String variant;

	// type of the validator this checker belongs to
	private final String type;

	private EndEntityChecker(String type, String variant) {
	this.type = type;
	this.variant = variant;
	}

	static EndEntityChecker getInstance(String type, String variant) {
	return new EndEntityChecker(type, variant);
	}

	void check(X509Certificate[] chain, Object parameter,
	boolean checkUnresolvedCritExts)
	throws CertificateException {
	if (variant.equals(Validator.VAR_GENERIC)) {
	return; // no checks
	}

	Set<String> exts = getCriticalExtensions(chain[0]);
	if (variant.equals(Validator.VAR_TLS_SERVER)) {
	checkTLSServer(chain[0], (String)parameter, exts);
	} else if (variant.equals(Validator.VAR_TLS_CLIENT)) {
	checkTLSClient(chain[0], exts);
	} else if (variant.equals(Validator.VAR_CODE_SIGNING)) {
	checkCodeSigning(chain[0], exts);
	} else if (variant.equals(Validator.VAR_JCE_SIGNING)) {
	checkCodeSigning(chain[0], exts);
	} else if (variant.equals(Validator.VAR_PLUGIN_CODE_SIGNING)) {
	checkCodeSigning(chain[0], exts);
	} else if (variant.equals(Validator.VAR_TSA_SERVER)) {
	checkTSAServer(chain[0], exts);
	} else {
	throw new CertificateException("Unknown variant: " + variant);
	}

	// if neither VAR_GENERIC variant nor unknown variant
	if (checkUnresolvedCritExts) {
	checkRemainingExtensions(exts);
	}

	// check if certificate should be distrusted according to policies
	// set in the jdk.security.caDistrustPolicies security property
	for (CADistrustPolicy policy : CADistrustPolicy.POLICIES) {
	policy.checkDistrust(variant, chain);
	}
	}

	/**
	* Utility method returning the Set of critical extensions for
	* certificate cert (never null).
	*/
	private Set<String> getCriticalExtensions(X509Certificate cert) {
	Set<String> exts = cert.getCriticalExtensionOIDs();
	if (exts == null) {
	exts = Collections.emptySet();
	}
	return exts;
	}

	/**
	* Utility method checking if there are any unresolved critical extensions.
	* @throws CertificateException if so.
	*/
	private void checkRemainingExtensions(Set<String> exts)
	throws CertificateException {
	// basic constraints irrelevant in EE certs
	exts.remove(SimpleValidator.OID_BASIC_CONSTRAINTS);

	// If the subject field contains an empty sequence, the subjectAltName
	// extension MUST be marked critical.
	// We do not check the validity of the critical extension, just mark
	// it recognizable here.
	exts.remove(OID_SUBJECT_ALT_NAME);

	if (!exts.isEmpty()) {
	throw new CertificateException("Certificate contains unsupported "
	+ "critical extensions: " + exts);
	}
	}

	/**
	* Utility method checking if the extended key usage extension in
	* certificate cert allows use for expectedEKU.
	*/
	private boolean checkEKU(X509Certificate cert, Set<String> exts,
	String expectedEKU) throws CertificateException {
	List<String> eku = cert.getExtendedKeyUsage();
	if (eku == null) {
	return true;
	}
	return eku.contains(expectedEKU) \|\| eku.contains(OID_EKU_ANY_USAGE);
	}

	/**
	* Utility method checking if bit 'bit' is set in this certificates
	* key usage extension.
	* @throws CertificateException if not
	*/
	private boolean checkKeyUsage(X509Certificate cert, int bit)
	throws CertificateException {
	boolean[] keyUsage = cert.getKeyUsage();
	if (keyUsage == null) {
	return true;
	}
	return (keyUsage.length > bit) && keyUsage[bit];
	}

	/**
	* Check whether this certificate can be used for TLS client
	* authentication.
	* @throws CertificateException if not.
	*/
	private void checkTLSClient(X509Certificate cert, Set<String> exts)
	throws CertificateException {
	if (checkKeyUsage(cert, KU_SIGNATURE) == false) {
	throw new ValidatorException
	("KeyUsage does not allow digital signatures",
	ValidatorException.T_EE_EXTENSIONS, cert);
	}

	if (checkEKU(cert, exts, OID_EKU_TLS_CLIENT) == false) {
	throw new ValidatorException("Extended key usage does not "
	+ "permit use for TLS client authentication",
	ValidatorException.T_EE_EXTENSIONS, cert);
	}

	if (!SimpleValidator.getNetscapeCertTypeBit(cert, NSCT_SSL_CLIENT)) {
	throw new ValidatorException
	("Netscape cert type does not permit use for SSL client",
	ValidatorException.T_EE_EXTENSIONS, cert);
	}

	// remove extensions we checked
	exts.remove(SimpleValidator.OID_KEY_USAGE);
	exts.remove(SimpleValidator.OID_EXTENDED_KEY_USAGE);
	exts.remove(SimpleValidator.OID_NETSCAPE_CERT_TYPE);
	}

	/**
	* Check whether this certificate can be used for TLS server authentication
	* using the specified authentication type parameter. See X509TrustManager
	* specification for details.
	* @throws CertificateException if not.
	*/
	private void checkTLSServer(X509Certificate cert, String parameter,
	Set<String> exts) throws CertificateException {
	if (KU_SERVER_ENCRYPTION.contains(parameter)) {
	if (checkKeyUsage(cert, KU_KEY_ENCIPHERMENT) == false) {
	throw new ValidatorException
	("KeyUsage does not allow key encipherment",
	ValidatorException.T_EE_EXTENSIONS, cert);
	}
	} else if (KU_SERVER_SIGNATURE.contains(parameter)) {
	if (checkKeyUsage(cert, KU_SIGNATURE) == false) {
	throw new ValidatorException
	("KeyUsage does not allow digital signatures",
	ValidatorException.T_EE_EXTENSIONS, cert);
	}
	} else if (KU_SERVER_KEY_AGREEMENT.contains(parameter)) {
	if (checkKeyUsage(cert, KU_KEY_AGREEMENT) == false) {
	throw new ValidatorException
	("KeyUsage does not allow key agreement",
	ValidatorException.T_EE_EXTENSIONS, cert);
	}
	} else {
	throw new CertificateException("Unknown authType: " + parameter);
	}

	if (checkEKU(cert, exts, OID_EKU_TLS_SERVER) == false) {
	// check for equivalent but now obsolete Server-Gated-Cryptography
	// (aka Step-Up, 128 bit) EKU OIDs
	if ((checkEKU(cert, exts, OID_EKU_MS_SGC) == false) &&
	(checkEKU(cert, exts, OID_EKU_NS_SGC) == false)) {
	throw new ValidatorException
	("Extended key usage does not permit use for TLS "
	+ "server authentication",
	ValidatorException.T_EE_EXTENSIONS, cert);
	}
	}

	if (!SimpleValidator.getNetscapeCertTypeBit(cert, NSCT_SSL_SERVER)) {
	throw new ValidatorException
	("Netscape cert type does not permit use for SSL server",
	ValidatorException.T_EE_EXTENSIONS, cert);
	}

	// remove extensions we checked
	exts.remove(SimpleValidator.OID_KEY_USAGE);
	exts.remove(SimpleValidator.OID_EXTENDED_KEY_USAGE);
	exts.remove(SimpleValidator.OID_NETSCAPE_CERT_TYPE);
	}

	/**
	* Check whether this certificate can be used for code signing.
	* @throws CertificateException if not.
	*/
	private void checkCodeSigning(X509Certificate cert, Set<String> exts)
	throws CertificateException {
	if (checkKeyUsage(cert, KU_SIGNATURE) == false) {
	throw new ValidatorException
	("KeyUsage does not allow digital signatures",
	ValidatorException.T_EE_EXTENSIONS, cert);
	}

	if (checkEKU(cert, exts, OID_EKU_CODE_SIGNING) == false) {
	throw new ValidatorException
	("Extended key usage does not permit use for code signing",
	ValidatorException.T_EE_EXTENSIONS, cert);
	}

	// do not check Netscape cert type for JCE code signing checks
	// (some certs were issued with incorrect extensions)
	if (variant.equals(Validator.VAR_JCE_SIGNING) == false) {
	if (!SimpleValidator.getNetscapeCertTypeBit(cert, NSCT_CODE_SIGNING)) {
	throw new ValidatorException
	("Netscape cert type does not permit use for code signing",
	ValidatorException.T_EE_EXTENSIONS, cert);
	}
	exts.remove(SimpleValidator.OID_NETSCAPE_CERT_TYPE);
	}

	// remove extensions we checked
	exts.remove(SimpleValidator.OID_KEY_USAGE);
	exts.remove(SimpleValidator.OID_EXTENDED_KEY_USAGE);
	}

	/**
	* Check whether this certificate can be used by a time stamping authority
	* server (see RFC 3161, section 2.3).
	* @throws CertificateException if not.
	*/
	private void checkTSAServer(X509Certificate cert, Set<String> exts)
	throws CertificateException {
	if (checkKeyUsage(cert, KU_SIGNATURE) == false) {
	throw new ValidatorException
	("KeyUsage does not allow digital signatures",
	ValidatorException.T_EE_EXTENSIONS, cert);
	}

	if (cert.getExtendedKeyUsage() == null) {
	throw new ValidatorException
	("Certificate does not contain an extended key usage " +
	"extension required for a TSA server",
	ValidatorException.T_EE_EXTENSIONS, cert);
	}

	if (checkEKU(cert, exts, OID_EKU_TIME_STAMPING) == false) {
	throw new ValidatorException
	("Extended key usage does not permit use for TSA server",
	ValidatorException.T_EE_EXTENSIONS, cert);
	}

	// remove extensions we checked
	exts.remove(SimpleValidator.OID_KEY_USAGE);
	exts.remove(SimpleValidator.OID_EXTENDED_KEY_USAGE);
	}
	}

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