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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * accompanied this code).

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package java.security.cert;

import java.security.KeyStore;

import java.security.KeyStoreException;

import java.security.InvalidAlgorithmParameterException;

import java.security.InvalidParameterException;

import java.util.Set;

/**

 * Parameters used as input for the PKIX {@code CertPathBuilder}

 * algorithm.

 * <p>

 * A PKIX {@code CertPathBuilder} uses these parameters to {@link

 * CertPathBuilder#build build} a {@code CertPath} which has been

 * validated according to the PKIX certification path validation algorithm.

 *

 * <p>To instantiate a {@code PKIXBuilderParameters} object, an

 * application must specify one or more <i>most-trusted CAs</i> as defined by

 * the PKIX certification path validation algorithm. The most-trusted CA

 * can be specified using one of two constructors. An application

 * can call {@link #PKIXBuilderParameters(Set, CertSelector)

 * PKIXBuilderParameters(Set, CertSelector)}, specifying a

 * {@code Set} of {@code TrustAnchor} objects, each of which

 * identifies a most-trusted CA. Alternatively, an application can call

 * {@link #PKIXBuilderParameters(KeyStore, CertSelector)

 * PKIXBuilderParameters(KeyStore, CertSelector)}, specifying a

 * {@code KeyStore} instance containing trusted certificate entries, each

 * of which will be considered as a most-trusted CA.

 *

 * <p>In addition, an application must specify constraints on the target

 * certificate that the {@code CertPathBuilder} will attempt

 * to build a path to. The constraints are specified as a

 * {@code CertSelector} object. These constraints should provide the

 * {@code CertPathBuilder} with enough search criteria to find the target

 * certificate. Minimal criteria for an {@code X509Certificate} usually

 * include the subject name and/or one or more subject alternative names.

 * If enough criteria is not specified, the {@code CertPathBuilder}

 * may throw a {@code CertPathBuilderException}.

 * <p>

 * <b>Concurrent Access</b>

 * <p>

 * Unless otherwise specified, the methods defined in this class are not

 * thread-safe. Multiple threads that need to access a single

 * object concurrently should synchronize amongst themselves and

 * provide the necessary locking. Multiple threads each manipulating

 * separate objects need not synchronize.

 *

 * @see CertPathBuilder

 *

 * @since       1.4

 * @author      Sean Mullan

 */

public class PKIXBuilderParameters extends PKIXParameters {

    private int maxPathLength = 5;

    /**

     * Creates an instance of {@code PKIXBuilderParameters} with

     * the specified {@code Set} of most-trusted CAs.

     * Each element of the set is a {@link TrustAnchor TrustAnchor}.

     *

     * <p>Note that the {@code Set} is copied to protect against

     * subsequent modifications.

     *

     * @param trustAnchors a {@code Set} of {@code TrustAnchor}s

     * @param targetConstraints a {@code CertSelector} specifying the

     * constraints on the target certificate

     * @throws InvalidAlgorithmParameterException if {@code trustAnchors}

     * is empty {@code (trustAnchors.isEmpty() == true)}

     * @throws NullPointerException if {@code trustAnchors} is

     * {@code null}

     * @throws ClassCastException if any of the elements of

     * {@code trustAnchors} are not of type

     * {@code java.security.cert.TrustAnchor}

     */

    public PKIXBuilderParameters(Set<TrustAnchor> trustAnchors, CertSelector

        targetConstraints) throws InvalidAlgorithmParameterException

    {

        super(trustAnchors);

        setTargetCertConstraints(targetConstraints);

    }

    /**

     * Creates an instance of {@code PKIXBuilderParameters} that

     * populates the set of most-trusted CAs from the trusted

     * certificate entries contained in the specified {@code KeyStore}.

     * Only keystore entries that contain trusted {@code X509Certificate}s

     * are considered; all other certificate types are ignored.

     *

     * @param keystore a {@code KeyStore} from which the set of

     * most-trusted CAs will be populated

     * @param targetConstraints a {@code CertSelector} specifying the

     * constraints on the target certificate

     * @throws KeyStoreException if {@code keystore} has not been

     * initialized

     * @throws InvalidAlgorithmParameterException if {@code keystore} does

     * not contain at least one trusted certificate entry

     * @throws NullPointerException if {@code keystore} is

     * {@code null}

     */

    public PKIXBuilderParameters(KeyStore keystore,

        CertSelector targetConstraints)

        throws KeyStoreException, InvalidAlgorithmParameterException

    {

        super(keystore);

        setTargetCertConstraints(targetConstraints);

    }

    /**

     * Sets the value of the maximum number of non-self-issued intermediate

     * certificates that may exist in a certification path. A certificate

     * is self-issued if the DNs that appear in the subject and issuer

     * fields are identical and are not empty. Note that the last certificate

     * in a certification path is not an intermediate certificate, and is not

     * included in this limit. Usually the last certificate is an end entity

     * certificate, but it can be a CA certificate. A PKIX

     * {@code CertPathBuilder} instance must not build

     * paths longer than the length specified.

     *

     * <p> A value of 0 implies that the path can only contain

     * a single certificate. A value of -1 implies that the

     * path length is unconstrained (i.e. there is no maximum).

     * The default maximum path length, if not specified, is 5.

     * Setting a value less than -1 will cause an exception to be thrown.

     *

     * <p> If any of the CA certificates contain the

     * {@code BasicConstraintsExtension}, the value of the

     * {@code pathLenConstraint} field of the extension overrides

     * the maximum path length parameter whenever the result is a

     * certification path of smaller length.

     *

     * @param maxPathLength the maximum number of non-self-issued intermediate

     *  certificates that may exist in a certification path

     * @throws InvalidParameterException if {@code maxPathLength} is set

     *  to a value less than -1

     *

     * @see #getMaxPathLength

     */

    public void setMaxPathLength(int maxPathLength) {

        if (maxPathLength < -1) {

            throw new InvalidParameterException("the maximum path "

                + "length parameter can not be less than -1");

        }

        this.maxPathLength = maxPathLength;

    }

    /**

     * Returns the value of the maximum number of intermediate non-self-issued

     * certificates that may exist in a certification path. See

     * the {@link #setMaxPathLength} method for more details.

     *

     * @return the maximum number of non-self-issued intermediate certificates

     *  that may exist in a certification path, or -1 if there is no limit

     *

     * @see #setMaxPathLength

     */

    public int getMaxPathLength() {

        return maxPathLength;

    }

    /**

     * Returns a formatted string describing the parameters.

     *

     * @return a formatted string describing the parameters

     */

    public String toString() {

        StringBuffer sb = new StringBuffer();

        sb.append("[\n");

        sb.append(super.toString());

        sb.append("  Maximum Path Length: " + maxPathLength + "\n");

        sb.append("]\n");

        return sb.toString();

    }

}