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/* * @(#)PKIXCertPathChecker.java 1.8 05/11/17 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package java.security.cert; import java.util.Collection; import java.util.Set; /** * An abstract class that performs one or more checks on an * <code>X509Certificate</code>. * * <p>A concrete implementation of the <code>PKIXCertPathChecker</code> class * can be created to extend the PKIX certification path validation algorithm. * For example, an implementation may check for and process a critical private * extension of each certificate in a certification path. * * <p>Instances of <code>PKIXCertPathChecker</code> are passed as parameters * using the {@link PKIXParameters#setCertPathCheckers setCertPathCheckers} * or {@link PKIXParameters#addCertPathChecker addCertPathChecker} methods * of the <code>PKIXParameters</code> and <code>PKIXBuilderParameters</code> * class. Each of the <code>PKIXCertPathChecker</code>s {@link #check check} * methods will be called, in turn, for each certificate processed by a PKIX * <code>CertPathValidator</code> or <code>CertPathBuilder</code> * implementation. * * <p>A <code>PKIXCertPathChecker</code> may be called multiple times on * successive certificates in a certification path. Concrete subclasses * are expected to maintain any internal state that may be necessary to * check successive certificates. The {@link #init init} method is used * to initialize the internal state of the checker so that the certificates * of a new certification path may be checked. A stateful implementation * <b>must</b> override the {@link #clone clone} method if necessary in * order to allow a PKIX <code>CertPathBuilder</code> to efficiently * backtrack and try other paths. In these situations, the * <code>CertPathBuilder</code> is able to restore prior path validation * states by restoring the cloned <code>PKIXCertPathChecker</code>s. * * <p>The order in which the certificates are presented to the * <code>PKIXCertPathChecker</code> may be either in the forward direction * (from target to most-trusted CA) or in the reverse direction (from * most-trusted CA to target). A <code>PKIXCertPathChecker</code> implementation * <b>must</b> support reverse checking (the ability to perform its checks when * it is presented with certificates in the reverse direction) and <b>may</b> * support forward checking (the ability to perform its checks when it is * presented with certificates in the forward direction). The * {@link #isForwardCheckingSupported isForwardCheckingSupported} method * indicates whether forward checking is supported. * <p> * Additional input parameters required for executing the check may be * specified through constructors of concrete implementations of this class. * <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 PKIXParameters * @see PKIXBuilderParameters * * @version 1.8 11/17/05 * @since 1.4 * @author Yassir Elley * @author Sean Mullan */ public abstract class PKIXCertPathChecker implements Cloneable { /** * Default constructor. */ protected PKIXCertPathChecker() {} /** * Initializes the internal state of this <code>PKIXCertPathChecker</code>. * <p> * The <code>forward</code> flag specifies the order that * certificates will be passed to the {@link #check check} method * (forward or reverse). A <code>PKIXCertPathChecker</code> <b>must</b> * support reverse checking and <b>may</b> support forward checking. * * @param forward the order that certificates are presented to * the <code>check</code> method. If <code>true</code>, certificates * are presented from target to most-trusted CA (forward); if * <code>false</code>, from most-trusted CA to target (reverse). * @throws CertPathValidatorException if this * <code>PKIXCertPathChecker</code> is unable to check certificates in * the specified order; it should never be thrown if the forward flag * is false since reverse checking must be supported */ public abstract void init(boolean forward) throws CertPathValidatorException; /** * Indicates if forward checking is supported. Forward checking refers * to the ability of the <code>PKIXCertPathChecker</code> to perform * its checks when certificates are presented to the <code>check</code> * method in the forward direction (from target to most-trusted CA). * * @return <code>true</code> if forward checking is supported, * <code>false</code> otherwise */ public abstract boolean isForwardCheckingSupported(); /** * Returns an immutable <code>Set</code> of X.509 certificate extensions * that this <code>PKIXCertPathChecker</code> supports (i.e. recognizes, is * able to process), or <code>null</code> if no extensions are supported. * <p> * Each element of the set is a <code>String</code> representing the * Object Identifier (OID) of the X.509 extension that is supported. * The OID is represented by a set of nonnegative integers separated by * periods. * <p> * All X.509 certificate extensions that a <code>PKIXCertPathChecker</code> * might possibly be able to process should be included in the set. * * @return an immutable <code>Set</code> of X.509 extension OIDs (in * <code>String</code> format) supported by this * <code>PKIXCertPathChecker</code>, or <code>null</code> if no * extensions are supported */ public abstract Set<String> getSupportedExtensions(); /** * Performs the check(s) on the specified certificate using its internal * state and removes any critical extensions that it processes from the * specified collection of OID strings that represent the unresolved * critical extensions. The certificates are presented in the order * specified by the <code>init</code> method. * * @param cert the <code>Certificate</code> to be checked * @param unresolvedCritExts a <code>Collection</code> of OID strings * representing the current set of unresolved critical extensions * @exception CertPathValidatorException if the specified certificate does * not pass the check */ public abstract void check(Certificate cert, Collection<String> unresolvedCritExts) throws CertPathValidatorException; /** * Returns a clone of this object. Calls the <code>Object.clone()</code> * method. * All subclasses which maintain state must support and * override this method, if necessary. * * @return a copy of this <code>PKIXCertPathChecker</code> */ public Object clone() { try { return super.clone(); } catch (CloneNotSupportedException e) { /* Cannot happen */ throw new InternalError(e.toString()); } } }