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	/*
	* Copyright (c) 2009, 2020, 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.security.AlgorithmConstraints;
	import java.security.CryptoPrimitive;
	import java.util.Collection;
	import java.util.Collections;
	import java.util.Date;
	import java.util.Set;
	import java.util.EnumSet;
	import java.math.BigInteger;
	import java.security.PublicKey;
	import java.security.KeyFactory;
	import java.security.AlgorithmParameters;
	import java.security.GeneralSecurityException;
	import java.security.cert.Certificate;
	import java.security.cert.X509CRL;
	import java.security.cert.X509Certificate;
	import java.security.cert.PKIXCertPathChecker;
	import java.security.cert.TrustAnchor;
	import java.security.cert.CRLException;
	import java.security.cert.CertificateException;
	import java.security.cert.CertPathValidatorException;
	import java.security.cert.CertPathValidatorException.BasicReason;
	import java.security.cert.PKIXReason;
	import java.security.interfaces.DSAParams;
	import java.security.interfaces.DSAPublicKey;
	import java.security.spec.DSAPublicKeySpec;

	import sun.security.util.ConstraintsParameters;
	import sun.security.util.Debug;
	import sun.security.util.DisabledAlgorithmConstraints;
	import sun.security.validator.Validator;
	import sun.security.x509.AlgorithmId;
	import sun.security.x509.X509CertImpl;
	import sun.security.x509.X509CRLImpl;

	/**
	* A {@code PKIXCertPathChecker} implementation to check whether a
	* specified certificate contains the required algorithm constraints.
	* <p>
	* Certificate fields such as the subject public key, the signature
	* algorithm, key usage, extended key usage, etc. need to conform to
	* the specified algorithm constraints.
	*
	* @see PKIXCertPathChecker
	* @see PKIXParameters
	*/
	public final class AlgorithmChecker extends PKIXCertPathChecker {
	private static final Debug debug = Debug.getInstance("certpath");

	private final AlgorithmConstraints constraints;
	private final PublicKey trustedPubKey;
	private final Date date;
	private PublicKey prevPubKey;
	private final String variant;
	private TrustAnchor anchor;

	private static final Set<CryptoPrimitive> SIGNATURE_PRIMITIVE_SET =
	Collections.unmodifiableSet(EnumSet.of(CryptoPrimitive.SIGNATURE));

	private static final Set<CryptoPrimitive> KU_PRIMITIVE_SET =
	Collections.unmodifiableSet(EnumSet.of(
	CryptoPrimitive.SIGNATURE,
	CryptoPrimitive.KEY_ENCAPSULATION,
	CryptoPrimitive.PUBLIC_KEY_ENCRYPTION,
	CryptoPrimitive.KEY_AGREEMENT));

	private static final DisabledAlgorithmConstraints
	certPathDefaultConstraints =
	DisabledAlgorithmConstraints.certPathConstraints();

	/**
	* Create a new {@code AlgorithmChecker} with the given
	* {@code TrustAnchor} and {@code String} variant.
	*
	* @param anchor the trust anchor selected to validate the target
	* certificate
	* @param variant the Validator variant of the operation. A null value
	* passed will set it to Validator.GENERIC.
	*/
	public AlgorithmChecker(TrustAnchor anchor, String variant) {
	this(anchor, certPathDefaultConstraints, null, variant);
	}

	/**
	* Create a new {@code AlgorithmChecker} with the given
	* {@code AlgorithmConstraints} and {@code String} variant.
	*
	* Note that this constructor can initialize a variation of situations where
	* the AlgorithmConstraints or Variant maybe known.
	*
	* @param constraints the algorithm constraints (or null)
	* @param variant the Validator variant of the operation. A null value
	* passed will set it to Validator.GENERIC.
	*/
	public AlgorithmChecker(AlgorithmConstraints constraints, String variant) {
	this(null, constraints, null, variant);
	}

	/**
	* Create a new {@code AlgorithmChecker} with the
	* given {@code TrustAnchor}, {@code AlgorithmConstraints}, {@code Date},
	* and {@code String} variant.
	*
	* @param anchor the trust anchor selected to validate the target
	* certificate
	* @param constraints the algorithm constraints (or null)
	* @param date the date specified by the PKIXParameters date, or the
	* JAR timestamp if jar files are being validated and the
	* JAR is timestamped. May be null if no timestamp or
	* PKIXParameter date is set.
	* @param variant the Validator variant of the operation. A null value
	* passed will set it to Validator.GENERIC.
	*/
	public AlgorithmChecker(TrustAnchor anchor,
	AlgorithmConstraints constraints, Date date, String variant) {

	if (anchor != null) {
	if (anchor.getTrustedCert() != null) {
	this.trustedPubKey = anchor.getTrustedCert().getPublicKey();
	} else {
	this.trustedPubKey = anchor.getCAPublicKey();
	}
	this.anchor = anchor;
	} else {
	this.trustedPubKey = null;
	}

	this.prevPubKey = this.trustedPubKey;
	this.constraints = (constraints == null ? certPathDefaultConstraints :
	constraints);
	this.date = date;
	this.variant = (variant == null ? Validator.VAR_GENERIC : variant);
	}

	/**
	* Create a new {@code AlgorithmChecker} with the given {@code TrustAnchor},
	* {@code PKIXParameter} date, and {@code varient}
	*
	* @param anchor the trust anchor selected to validate the target
	* certificate
	* @param pkixdate Date the constraints are checked against. The value is
	* either the PKIXParameters date or null for the current date.
	* @param variant the Validator variant of the operation. A null value
	* passed will set it to Validator.GENERIC.
	*/
	public AlgorithmChecker(TrustAnchor anchor, Date pkixdate, String variant) {
	this(anchor, certPathDefaultConstraints, pkixdate, variant);
	}

	@Override
	public void init(boolean forward) throws CertPathValidatorException {
	// Note that this class does not support forward mode.
	if (!forward) {
	if (trustedPubKey != null) {
	prevPubKey = trustedPubKey;
	} else {
	prevPubKey = null;
	}
	} else {
	throw new
	CertPathValidatorException("forward checking not supported");
	}
	}

	@Override
	public boolean isForwardCheckingSupported() {
	// Note that as this class does not support forward mode, the method
	// will always returns false.
	return false;
	}

	@Override
	public Set<String> getSupportedExtensions() {
	return null;
	}

	@Override
	public void check(Certificate cert,
	Collection<String> unresolvedCritExts)
	throws CertPathValidatorException {

	if (!(cert instanceof X509Certificate) \|\| constraints == null) {
	// ignore the check for non-x.509 certificate or null constraints
	return;
	}

	// check the key usage and key size
	boolean[] keyUsage = ((X509Certificate) cert).getKeyUsage();
	if (keyUsage != null && keyUsage.length < 9) {
	throw new CertPathValidatorException(
	"incorrect KeyUsage extension",
	null, null, -1, PKIXReason.INVALID_KEY_USAGE);
	}

	X509CertImpl x509Cert;
	AlgorithmId algorithmId;
	try {
	x509Cert = X509CertImpl.toImpl((X509Certificate)cert);
	algorithmId = (AlgorithmId)x509Cert.get(X509CertImpl.SIG_ALG);
	} catch (CertificateException ce) {
	throw new CertPathValidatorException(ce);
	}

	AlgorithmParameters currSigAlgParams = algorithmId.getParameters();
	PublicKey currPubKey = cert.getPublicKey();
	String currSigAlg = x509Cert.getSigAlgName();

	// Check the signature algorithm and parameters against constraints.
	if (!constraints.permits(SIGNATURE_PRIMITIVE_SET, currSigAlg,
	currSigAlgParams)) {
	throw new CertPathValidatorException(
	"Algorithm constraints check failed on signature " +
	"algorithm: " + currSigAlg, null, null, -1,
	BasicReason.ALGORITHM_CONSTRAINED);
	}

	// Assume all key usage bits are set if key usage is not present
	Set<CryptoPrimitive> primitives = KU_PRIMITIVE_SET;

	if (keyUsage != null) {
	primitives = EnumSet.noneOf(CryptoPrimitive.class);

	if (keyUsage[0] \|\| keyUsage[1] \|\| keyUsage[5] \|\| keyUsage[6]) {
	// keyUsage[0]: KeyUsage.digitalSignature
	// keyUsage[1]: KeyUsage.nonRepudiation
	// keyUsage[5]: KeyUsage.keyCertSign
	// keyUsage[6]: KeyUsage.cRLSign
	primitives.add(CryptoPrimitive.SIGNATURE);
	}

	if (keyUsage[2]) { // KeyUsage.keyEncipherment
	primitives.add(CryptoPrimitive.KEY_ENCAPSULATION);
	}

	if (keyUsage[3]) { // KeyUsage.dataEncipherment
	primitives.add(CryptoPrimitive.PUBLIC_KEY_ENCRYPTION);
	}

	if (keyUsage[4]) { // KeyUsage.keyAgreement
	primitives.add(CryptoPrimitive.KEY_AGREEMENT);
	}

	// KeyUsage.encipherOnly and KeyUsage.decipherOnly are
	// undefined in the absence of the keyAgreement bit.

	if (primitives.isEmpty()) {
	throw new CertPathValidatorException(
	"incorrect KeyUsage extension bits",
	null, null, -1, PKIXReason.INVALID_KEY_USAGE);
	}
	}

	ConstraintsParameters cp =
	new CertPathConstraintsParameters(x509Cert, variant,
	anchor, date);

	// Check against local constraints if it is DisabledAlgorithmConstraints
	if (constraints instanceof DisabledAlgorithmConstraints) {
	((DisabledAlgorithmConstraints)constraints).permits(currSigAlg,
	currSigAlgParams, cp);
	// DisabledAlgorithmsConstraints does not check primitives, so key
	// additional key check.

	} else {
	// Perform the default constraints checking anyway.
	certPathDefaultConstraints.permits(currSigAlg, currSigAlgParams, cp);
	// Call locally set constraints to check key with primitives.
	if (!constraints.permits(primitives, currPubKey)) {
	throw new CertPathValidatorException(
	"Algorithm constraints check failed on key " +
	currPubKey.getAlgorithm() + " with size of " +
	sun.security.util.KeyUtil.getKeySize(currPubKey) +
	"bits",
	null, null, -1, BasicReason.ALGORITHM_CONSTRAINED);
	}
	}

	// If there is no previous key, set one and exit
	if (prevPubKey == null) {
	prevPubKey = currPubKey;
	return;
	}

	// Check with previous cert for signature algorithm and public key
	if (!constraints.permits(
	SIGNATURE_PRIMITIVE_SET,
	currSigAlg, prevPubKey, currSigAlgParams)) {
	throw new CertPathValidatorException(
	"Algorithm constraints check failed on " +
	"signature algorithm: " + currSigAlg,
	null, null, -1, BasicReason.ALGORITHM_CONSTRAINED);
	}

	// Inherit key parameters from previous key
	if (PKIX.isDSAPublicKeyWithoutParams(currPubKey)) {
	// Inherit DSA parameters from previous key
	if (!(prevPubKey instanceof DSAPublicKey)) {
	throw new CertPathValidatorException("Input key is not " +
	"of a appropriate type for inheriting parameters");
	}

	DSAParams params = ((DSAPublicKey)prevPubKey).getParams();
	if (params == null) {
	throw new CertPathValidatorException(
	"Key parameters missing from public key.");
	}

	try {
	BigInteger y = ((DSAPublicKey)currPubKey).getY();
	KeyFactory kf = KeyFactory.getInstance("DSA");
	DSAPublicKeySpec ks = new DSAPublicKeySpec(y, params.getP(),
	params.getQ(), params.getG());
	currPubKey = kf.generatePublic(ks);
	} catch (GeneralSecurityException e) {
	throw new CertPathValidatorException("Unable to generate " +
	"key with inherited parameters: " + e.getMessage(), e);
	}
	}

	// reset the previous public key
	prevPubKey = currPubKey;
	}

	/**
	* Try to set the trust anchor of the checker.
	* <p>
	* If there is no trust anchor specified and the checker has not started,
	* set the trust anchor.
	*
	* @param anchor the trust anchor selected to validate the target
	* certificate
	*/
	void trySetTrustAnchor(TrustAnchor anchor) {
	// Don't bother if the check has started or trust anchor has already
	// specified.
	if (prevPubKey == null) {
	if (anchor == null) {
	throw new IllegalArgumentException(
	"The trust anchor cannot be null");
	}

	// Don't bother to change the trustedPubKey.
	if (anchor.getTrustedCert() != null) {
	prevPubKey = anchor.getTrustedCert().getPublicKey();
	} else {
	prevPubKey = anchor.getCAPublicKey();
	}
	this.anchor = anchor;
	}
	}

	/**
	* Check the signature algorithm with the specified public key.
	*
	* @param key the public key to verify the CRL signature
	* @param crl the target CRL
	* @param variant the Validator variant of the operation. A null value
	* passed will set it to Validator.GENERIC.
	* @param anchor the trust anchor selected to validate the CRL issuer
	*/
	static void check(PublicKey key, X509CRL crl, String variant,
	TrustAnchor anchor) throws CertPathValidatorException {

	X509CRLImpl x509CRLImpl = null;
	try {
	x509CRLImpl = X509CRLImpl.toImpl(crl);
	} catch (CRLException ce) {
	throw new CertPathValidatorException(ce);
	}

	AlgorithmId algorithmId = x509CRLImpl.getSigAlgId();
	check(key, algorithmId, variant, anchor);
	}

	/**
	* Check the signature algorithm with the specified public key.
	*
	* @param key the public key to verify the CRL signature
	* @param algorithmId signature algorithm Algorithm ID
	* @param variant the Validator variant of the operation. A null
	* value passed will set it to Validator.GENERIC.
	* @param anchor the trust anchor selected to validate the public key
	*/
	static void check(PublicKey key, AlgorithmId algorithmId, String variant,
	TrustAnchor anchor) throws CertPathValidatorException {

	certPathDefaultConstraints.permits(algorithmId.getName(),
	algorithmId.getParameters(),
	new CertPathConstraintsParameters(key, variant, anchor));
	}
	}

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