1/*
2 * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
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24 */
25
26package java.security.cert;
27
28import java.security.KeyStore;
29import java.security.KeyStoreException;
30import java.security.InvalidAlgorithmParameterException;
31import java.security.InvalidParameterException;
32import java.util.Set;
33
34/**
35 * Parameters used as input for the PKIX {@code CertPathBuilder}
36 * algorithm.
37 * <p>
38 * A PKIX {@code CertPathBuilder} uses these parameters to {@link
39 * CertPathBuilder#build build} a {@code CertPath} which has been
40 * validated according to the PKIX certification path validation algorithm.
41 *
42 * <p>To instantiate a {@code PKIXBuilderParameters} object, an
43 * application must specify one or more <i>most-trusted CAs</i> as defined by
44 * the PKIX certification path validation algorithm. The most-trusted CA
45 * can be specified using one of two constructors. An application
46 * can call {@link #PKIXBuilderParameters(Set, CertSelector)
47 * PKIXBuilderParameters(Set, CertSelector)}, specifying a
48 * {@code Set} of {@code TrustAnchor} objects, each of which
49 * identifies a most-trusted CA. Alternatively, an application can call
50 * {@link #PKIXBuilderParameters(KeyStore, CertSelector)
51 * PKIXBuilderParameters(KeyStore, CertSelector)}, specifying a
52 * {@code KeyStore} instance containing trusted certificate entries, each
53 * of which will be considered as a most-trusted CA.
54 *
55 * <p>In addition, an application must specify constraints on the target
56 * certificate that the {@code CertPathBuilder} will attempt
57 * to build a path to. The constraints are specified as a
58 * {@code CertSelector} object. These constraints should provide the
59 * {@code CertPathBuilder} with enough search criteria to find the target
60 * certificate. Minimal criteria for an {@code X509Certificate} usually
61 * include the subject name and/or one or more subject alternative names.
62 * If enough criteria is not specified, the {@code CertPathBuilder}
63 * may throw a {@code CertPathBuilderException}.
64 * <p>
65 * <b>Concurrent Access</b>
66 * <p>
67 * Unless otherwise specified, the methods defined in this class are not
68 * thread-safe. Multiple threads that need to access a single
69 * object concurrently should synchronize amongst themselves and
70 * provide the necessary locking. Multiple threads each manipulating
71 * separate objects need not synchronize.
72 *
73 * @see CertPathBuilder
74 *
75 * @since       1.4
76 * @author      Sean Mullan
77 */
78public class PKIXBuilderParameters extends PKIXParameters {
79
80    private int maxPathLength = 5;
81
82    /**
83     * Creates an instance of {@code PKIXBuilderParameters} with
84     * the specified {@code Set} of most-trusted CAs.
85     * Each element of the set is a {@link TrustAnchor TrustAnchor}.
86     *
87     * <p>Note that the {@code Set} is copied to protect against
88     * subsequent modifications.
89     *
90     * @param trustAnchors a {@code Set} of {@code TrustAnchor}s
91     * @param targetConstraints a {@code CertSelector} specifying the
92     * constraints on the target certificate
93     * @throws InvalidAlgorithmParameterException if {@code trustAnchors}
94     * is empty {@code (trustAnchors.isEmpty() == true)}
95     * @throws NullPointerException if {@code trustAnchors} is
96     * {@code null}
97     * @throws ClassCastException if any of the elements of
98     * {@code trustAnchors} are not of type
99     * {@code java.security.cert.TrustAnchor}
100     */
101    public PKIXBuilderParameters(Set<TrustAnchor> trustAnchors, CertSelector
102        targetConstraints) throws InvalidAlgorithmParameterException
103    {
104        super(trustAnchors);
105        setTargetCertConstraints(targetConstraints);
106    }
107
108    /**
109     * Creates an instance of {@code PKIXBuilderParameters} that
110     * populates the set of most-trusted CAs from the trusted
111     * certificate entries contained in the specified {@code KeyStore}.
112     * Only keystore entries that contain trusted {@code X509Certificate}s
113     * are considered; all other certificate types are ignored.
114     *
115     * @param keystore a {@code KeyStore} from which the set of
116     * most-trusted CAs will be populated
117     * @param targetConstraints a {@code CertSelector} specifying the
118     * constraints on the target certificate
119     * @throws KeyStoreException if {@code keystore} has not been
120     * initialized
121     * @throws InvalidAlgorithmParameterException if {@code keystore} does
122     * not contain at least one trusted certificate entry
123     * @throws NullPointerException if {@code keystore} is
124     * {@code null}
125     */
126    public PKIXBuilderParameters(KeyStore keystore,
127        CertSelector targetConstraints)
128        throws KeyStoreException, InvalidAlgorithmParameterException
129    {
130        super(keystore);
131        setTargetCertConstraints(targetConstraints);
132    }
133
134    /**
135     * Sets the value of the maximum number of non-self-issued intermediate
136     * certificates that may exist in a certification path. A certificate
137     * is self-issued if the DNs that appear in the subject and issuer
138     * fields are identical and are not empty. Note that the last certificate
139     * in a certification path is not an intermediate certificate, and is not
140     * included in this limit. Usually the last certificate is an end entity
141     * certificate, but it can be a CA certificate. A PKIX
142     * {@code CertPathBuilder} instance must not build
143     * paths longer than the length specified.
144     *
145     * <p> A value of 0 implies that the path can only contain
146     * a single certificate. A value of -1 implies that the
147     * path length is unconstrained (i.e. there is no maximum).
148     * The default maximum path length, if not specified, is 5.
149     * Setting a value less than -1 will cause an exception to be thrown.
150     *
151     * <p> If any of the CA certificates contain the
152     * {@code BasicConstraintsExtension}, the value of the
153     * {@code pathLenConstraint} field of the extension overrides
154     * the maximum path length parameter whenever the result is a
155     * certification path of smaller length.
156     *
157     * @param maxPathLength the maximum number of non-self-issued intermediate
158     *  certificates that may exist in a certification path
159     * @throws InvalidParameterException if {@code maxPathLength} is set
160     *  to a value less than -1
161     *
162     * @see #getMaxPathLength
163     */
164    public void setMaxPathLength(int maxPathLength) {
165        if (maxPathLength < -1) {
166            throw new InvalidParameterException("the maximum path "
167                + "length parameter can not be less than -1");
168        }
169        this.maxPathLength = maxPathLength;
170    }
171
172    /**
173     * Returns the value of the maximum number of intermediate non-self-issued
174     * certificates that may exist in a certification path. See
175     * the {@link #setMaxPathLength} method for more details.
176     *
177     * @return the maximum number of non-self-issued intermediate certificates
178     *  that may exist in a certification path, or -1 if there is no limit
179     *
180     * @see #setMaxPathLength
181     */
182    public int getMaxPathLength() {
183        return maxPathLength;
184    }
185
186    /**
187     * Returns a formatted string describing the parameters.
188     *
189     * @return a formatted string describing the parameters
190     */
191    public String toString() {
192        StringBuilder sb = new StringBuilder();
193        sb.append("[\n");
194        sb.append(super.toString());
195        sb.append("  Maximum Path Length: " + maxPathLength + "\n");
196        sb.append("]\n");
197        return sb.toString();
198    }
199}
200