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 * 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

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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.util.DerOutputStream;

import sun.security.x509.SerialNumber;

import sun.security.x509.KeyIdentifier;

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) {

            KeyIdentifier akid = (KeyIdentifier)ext.get(

                AuthorityKeyIdentifierExtension.KEY_ID);

            if (akid != null) {

                DerOutputStream derout = new DerOutputStream();

                derout.putOctetString(akid.getIdentifier());

                ski = derout.toByteArray();

            }

            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: "

                }

                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: "

                }

                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;

    }

}