PKIXBuilderParameters


1   /*
2    * @(#)PKIXBuilderParameters.java   1.15 03/12/19
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   
8   package java.security.cert;
9   
10  import java.security.KeyStore  ;
11  import java.security.KeyStoreException  ;
12  import java.security.InvalidAlgorithmParameterException  ;
13  import java.security.InvalidParameterException  ;
14  import java.util.Set  ;
15  
16  /**
17   * Parameters used as input for the PKIX <code>CertPathBuilder</code> 
18   * algorithm.
19   * <p>
20   * A PKIX <code>CertPathBuilder</code> uses these parameters to {@link 
21   * CertPathBuilder#build build} a <code>CertPath</code> which has been 
22   * validated according to the PKIX certification path validation algorithm.
23   *
24   * <p>To instantiate a <code>PKIXBuilderParameters</code> object, an
25   * application must specify one or more <i>most-trusted CAs</i> as defined by
26   * the PKIX certification path validation algorithm. The most-trusted CA 
27   * can be specified using one of two constructors. An application 
28   * can call {@link #PKIXBuilderParameters(Set, CertSelector) 
29   * PKIXBuilderParameters(Set, CertSelector)}, specifying a 
30   * <code>Set</code> of <code>TrustAnchor</code> objects, each of which 
31   * identifies a most-trusted CA. Alternatively, an application can call 
32   * {@link #PKIXBuilderParameters(KeyStore, CertSelector)
33   * PKIXBuilderParameters(KeyStore, CertSelector)}, specifying a 
34   * <code>KeyStore</code> instance containing trusted certificate entries, each 
35   * of which will be considered as a most-trusted CA.
36   *
37   * <p>In addition, an application must specify constraints on the target 
38   * certificate that the <code>CertPathBuilder</code> will attempt 
39   * to build a path to. The constraints are specified as a 
40   * <code>CertSelector</code> object. These constraints should provide the 
41   * <code>CertPathBuilder</code> with enough search criteria to find the target 
42   * certificate. Minimal criteria for an <code>X509Certificate</code> usually 
43   * include the subject name and/or one or more subject alternative names.
44   * If enough criteria is not specified, the <code>CertPathBuilder</code> 
45   * may throw a <code>CertPathBuilderException</code>.
46   * <p>
47   * <b>Concurrent Access</b>
48   * <p>
49   * Unless otherwise specified, the methods defined in this class are not
50   * thread-safe. Multiple threads that need to access a single
51   * object concurrently should synchronize amongst themselves and
52   * provide the necessary locking. Multiple threads each manipulating
53   * separate objects need not synchronize.
54   *
55   * @see CertPathBuilder
56   * 
57   * @version     1.15 12/19/03
58   * @since   1.4
59   * @author  Sean Mullan
60   */
61  public class PKIXBuilderParameters extends PKIXParameters   {
62  
63      private int maxPathLength = 5;
64  
65      /**
66       * Creates an instance of <code>PKIXBuilderParameters</code> with
67       * the specified <code>Set</code> of most-trusted CAs. 
68       * Each element of the set is a {@link TrustAnchor TrustAnchor}.
69       *
70       * <p>Note that the <code>Set</code> is copied to protect against
71       * subsequent modifications.
72       *
73       * @param trustAnchors a <code>Set</code> of <code>TrustAnchor</code>s
74       * @param targetConstraints a <code>CertSelector</code> specifying the 
75       * constraints on the target certificate 
76       * @throws InvalidAlgorithmParameterException if <code>trustAnchors</code> 
77       * is empty <code>(trustAnchors.isEmpty() == true)</code>
78       * @throws NullPointerException if <code>trustAnchors</code> is 
79       * <code>null</code>
80       * @throws ClassCastException if any of the elements of
81       * <code>trustAnchors</code> are not of type 
82       * <code>java.security.cert.TrustAnchor</code>
83       */
84      public PKIXBuilderParameters(Set  <TrustAnchor  > trustAnchors, CertSelector   
85      targetConstraints) throws InvalidAlgorithmParameterException  
86      {
87          super(trustAnchors);
88      setTargetCertConstraints(targetConstraints);
89      }
90  
91      /**
92       * Creates an instance of <code>PKIXBuilderParameters</code> that
93       * populates the set of most-trusted CAs from the trusted
94       * certificate entries contained in the specified <code>KeyStore</code>.
95       * Only keystore entries that contain trusted <code>X509Certificate</code>s
96       * are considered; all other certificate types are ignored.
97       *
98       * @param keystore a <code>KeyStore</code> from which the set of 
99       * most-trusted CAs will be populated
100      * @param targetConstraints a <code>CertSelector</code> specifying the 
101      * constraints on the target certificate 
102      * @throws KeyStoreException if <code>keystore</code> has not been 
103      * initialized
104      * @throws InvalidAlgorithmParameterException if <code>keystore</code> does
105      * not contain at least one trusted certificate entry
106      * @throws NullPointerException if <code>keystore</code> is 
107      * <code>null</code>
108      */
109     public PKIXBuilderParameters(KeyStore   keystore, 
110         CertSelector   targetConstraints) 
111         throws KeyStoreException  , InvalidAlgorithmParameterException   
112     {
113     super(keystore);
114     setTargetCertConstraints(targetConstraints);
115     }
116 
117     /**
118      * Sets the value of the maximum number of non-self-issued intermediate
119      * certificates that may exist in a certification path. A certificate
120      * is self-issued if the DNs that appear in the subject and issuer
121      * fields are identical and are not empty. Note that the last certificate
122      * in a certification path is not an intermediate certificate, and is not
123      * included in this limit. Usually the last certificate is an end entity
124      * certificate, but it can be a CA certificate. A PKIX 
125      * <code>CertPathBuilder</code> instance must not build 
126      * paths longer than the length specified.
127      *
128      * <p> A value of 0 implies that the path can only contain
129      * a single certificate. A value of -1 implies that the
130      * path length is unconstrained (i.e. there is no maximum).
131      * The default maximum path length, if not specified, is 5.
132      * Setting a value less than -1 will cause an exception to be thrown.
133      *
134      * <p> If any of the CA certificates contain the 
135      * <code>BasicConstraintsExtension</code>, the value of the
136      * <code>pathLenConstraint</code> field of the extension overrides
137      * the maximum path length parameter whenever the result is a
138      * certification path of smaller length.
139      *
140      * @param maxPathLength the maximum number of non-self-issued intermediate
141      *  certificates that may exist in a certification path
142      * @throws InvalidParameterException if <code>maxPathLength</code> is set 
143      *  to a value less than -1
144      *
145      * @see #getMaxPathLength
146      */
147     public void setMaxPathLength(int maxPathLength) {
148     if (maxPathLength < -1) {
149         throw new InvalidParameterException  ("the maximum path "
150         + "length parameter can not be less than -1");
151     }
152     this.maxPathLength = maxPathLength;
153     }
154 
155     /**
156      * Returns the value of the maximum number of intermediate non-self-issued
157      * certificates that may exist in a certification path. See
158      * the {@link #setMaxPathLength} method for more details.
159      *
160      * @return the maximum number of non-self-issued intermediate certificates 
161      *  that may exist in a certification path, or -1 if there is no limit
162      *
163      * @see #setMaxPathLength
164      */
165     public int getMaxPathLength() {
166         return maxPathLength;
167     }
168 
169     /**
170      * Returns a formatted string describing the parameters.
171      *
172      * @return a formatted string describing the parameters
173      */
174     public String   toString() {
175         StringBuffer   sb = new StringBuffer  ();
176         sb.append("[\n");
177     sb.append(super.toString());
178     sb.append("  Maximum Path Length: " + maxPathLength + "\n");
179     sb.append("]\n");
180     return sb.toString();
181     }
182 }
183
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