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package sun.security.provider.certpath;

import java.security.AlgorithmConstraints;
import java.security.CryptoPrimitive;
import java.security.Timestamp;
import java.security.cert.CertPathValidator;
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.AnchorCertificates;
import sun.security.util.ConstraintsParameters;
import sun.security.util.Debug;
import sun.security.util.DisabledAlgorithmConstraints;
import sun.security.validator.Validator;
import sun.security.x509.X509CertImpl;
import sun.security.x509.X509CRLImpl;
import sun.security.x509.AlgorithmId;

A PKIXCertPathChecker implementation to check whether a specified certificate contains the required algorithm constraints. 

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 Also:
PKIXCertPathChecker
PKIXParameters/**
 * 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 pkixdate;
    private PublicKey prevPubKey;
    private final Timestamp jarTimestamp;
    private final String variant;

    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 = new DisabledAlgorithmConstraints(
            DisabledAlgorithmConstraints.PROPERTY_CERTPATH_DISABLED_ALGS);

    // If there is no "cacerts" keyword, then disable anchor checking
    private static final boolean publicCALimits =
            certPathDefaultConstraints.checkProperty("jdkCA");

    // If anchor checking enabled, this will be true if the trust anchor
    // has a match in the cacerts file
    private boolean trustedMatch = false;

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

    
Create a new AlgorithmChecker with the given AlgorithmConstraints, Timestamp, and String variant. Note that this constructor can initialize a variation of situations where the AlgorithmConstraints, Timestamp, or Variant maybe known. 
Params:
constraints – the algorithm constraints (or null)
jarTimestamp – Timestamp passed for JAR timestamp constraint
                    checking. Set to null if not applicable.
variant – is the Validator variants of the operation. A null value
               passed will set it to Validator.GENERIC./**
     * Create a new {@code AlgorithmChecker} with the given
     * {@code AlgorithmConstraints}, {@code Timestamp}, and {@code String}
     * variant.
     *
     * Note that this constructor can initialize a variation of situations where
     * the AlgorithmConstraints, Timestamp, or Variant maybe known.
     *
     * @param constraints the algorithm constraints (or null)
     * @param jarTimestamp Timestamp passed for JAR timestamp constraint
     *                     checking. Set to null if not applicable.
     * @param variant is the Validator variants of the operation. A null value
     *                passed will set it to Validator.GENERIC.
     */
    public AlgorithmChecker(AlgorithmConstraints constraints,
            Timestamp jarTimestamp, String variant) {
        this(null, constraints, null, jarTimestamp, variant);
    }

    
Create a new AlgorithmChecker with the given TrustAnchor, AlgorithmConstraints, Timestamp, and String variant. 
Params:
anchor – the trust anchor selected to validate the target
    certificate
constraints – the algorithm constraints (or null)
pkixdate – The date specified by the PKIXParameters date.  If the
                PKIXParameters is null, the current date is used.  This
                should be null when jar files are being checked.
jarTimestamp – Timestamp passed for JAR timestamp constraint
                    checking. Set to null if not applicable.
variant – is the Validator variants of the operation. A null value
               passed will set it to Validator.GENERIC./**
     * Create a new {@code AlgorithmChecker} with the
     * given {@code TrustAnchor}, {@code AlgorithmConstraints},
     * {@code Timestamp}, and {@code String} variant.
     *
     * @param anchor the trust anchor selected to validate the target
     *     certificate
     * @param constraints the algorithm constraints (or null)
     * @param pkixdate The date specified by the PKIXParameters date.  If the
     *                 PKIXParameters is null, the current date is used.  This
     *                 should be null when jar files are being checked.
     * @param jarTimestamp Timestamp passed for JAR timestamp constraint
     *                     checking. Set to null if not applicable.
     * @param variant is the Validator variants of the operation. A null value
     *                passed will set it to Validator.GENERIC.
     */
    public AlgorithmChecker(TrustAnchor anchor,
            AlgorithmConstraints constraints, Date pkixdate,
            Timestamp jarTimestamp, String variant) {

        if (anchor != null) {
            if (anchor.getTrustedCert() != null) {
                this.trustedPubKey = anchor.getTrustedCert().getPublicKey();
                // Check for anchor certificate restrictions
                trustedMatch = checkFingerprint(anchor.getTrustedCert());
                if (trustedMatch && debug != null) {
                    debug.println("trustedMatch = true");
                }
            } else {
                this.trustedPubKey = anchor.getCAPublicKey();
            }
        } else {
            this.trustedPubKey = null;
            if (debug != null) {
                debug.println("TrustAnchor is null, trustedMatch is false.");
            }
        }

        this.prevPubKey = this.trustedPubKey;
        this.constraints = (constraints == null ? certPathDefaultConstraints :
                constraints);
        // If we are checking jar files, set pkixdate the same as the timestamp
        // for certificate checking
        this.pkixdate = (jarTimestamp != null ? jarTimestamp.getTimestamp() :
                pkixdate);
        this.jarTimestamp = jarTimestamp;
        this.variant = (variant == null ? Validator.VAR_GENERIC : variant);
    }

    
Create a new AlgorithmChecker with the given TrustAnchor, PKIXParameter date, and varient 
Params:
anchor – the trust anchor selected to validate the target
    certificate
pkixdate – Date the constraints are checked against. The value is
            either the PKIXParameters date or null for the current date.
variant – is the Validator variants of the operation. A null value
               passed will set it to Validator.GENERIC./**
     * 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 is the Validator variants 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, null, variant);
    }

    // Check this 'cert' for restrictions in the AnchorCertificates
    // trusted certificates list
    private static boolean checkFingerprint(X509Certificate cert) {
        if (!publicCALimits) {
            return false;
        }

        if (debug != null) {
            debug.println("AlgorithmChecker.contains: " + cert.getSigAlgName());
        }
        return AnchorCertificates.contains(cert);
    }

    @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 ConstraintsParameters((X509Certificate)cert,
                        trustedMatch, pkixdate, jarTimestamp, variant);

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

        } else {
            // Perform the default constraints checking anyway.
            certPathDefaultConstraints.permits(currSigAlg, 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.

If there is no trust anchor specified and the checker has not started,
set the trust anchor.
Params:
anchor – the trust anchor selected to validate the target
    certificate/**
     * 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();
                // Check for anchor certificate restrictions
                trustedMatch = checkFingerprint(anchor.getTrustedCert());
                if (trustedMatch && debug != null) {
                    debug.println("trustedMatch = true");
                }
            } else {
                prevPubKey = anchor.getCAPublicKey();
            }
        }
    }

    
Check the signature algorithm with the specified public key.
Params:
key – the public key to verify the CRL signature
crl – the target CRL
variant – is the Validator variants of the operation. A null value
               passed will set it to Validator.GENERIC./**
     * 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 is the Validator variants of the operation. A null value
     *                passed will set it to Validator.GENERIC.
     */
    static void check(PublicKey key, X509CRL crl, String variant)
                        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);
    }

    
Check the signature algorithm with the specified public key.
Params:
key – the public key to verify the CRL signature
algorithmId – signature algorithm Algorithm ID
variant – is the Validator variants of the operation. A null value
               passed will set it to Validator.GENERIC./**
     * 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 is the Validator variants of the operation. A null value
     *                passed will set it to Validator.GENERIC.
     */
    static void check(PublicKey key, AlgorithmId algorithmId, String variant)
                        throws CertPathValidatorException {
        String sigAlgName = algorithmId.getName();
        AlgorithmParameters sigAlgParams = algorithmId.getParameters();

        certPathDefaultConstraints.permits(new ConstraintsParameters(
                sigAlgName, sigAlgParams, key, variant));
    }
}