1 /* 2 * Copyright (c) 1997, 2017, 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). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.security.cert; 27 28 import java.util.Set; 29 30 /** 31 * Interface for an X.509 extension. 32 * 33 * <p>The extensions defined for X.509 v3 34 * {@link X509Certificate Certificates} and v2 35 * {@link X509CRL CRLs} (Certificate Revocation 36 * Lists) provide methods 37 * for associating additional attributes with users or public keys, 38 * for managing the certification hierarchy, and for managing CRL 39 * distribution. The X.509 extensions format also allows communities 40 * to define private extensions to carry information unique to those 41 * communities. 42 * 43 * <p>Each extension in a certificate/CRL may be designated as 44 * critical or non-critical. A certificate/CRL-using system (an application 45 * validating a certificate/CRL) must reject the certificate/CRL if it 46 * encounters a critical extension it does not recognize. A non-critical 47 * extension may be ignored if it is not recognized. 48 * <p> 49 * The ASN.1 definition for this is: 50 * <pre> 51 * Extensions ::= SEQUENCE SIZE (1..MAX) OF Extension 52 * 53 * Extension ::= SEQUENCE { 54 * extnId OBJECT IDENTIFIER, 55 * critical BOOLEAN DEFAULT FALSE, 56 * extnValue OCTET STRING 57 * -- contains a DER encoding of a value 58 * -- of the type registered for use with 59 * -- the extnId object identifier value 60 * } 61 * </pre> 62 * Since not all extensions are known, the {@code getExtensionValue} 63 * method returns the DER-encoded OCTET STRING of the 64 * extension value (i.e., the {@code extnValue}). This can then 65 * be handled by a <em>Class</em> that understands the extension. 66 * 67 * @author Hemma Prafullchandra 68 * @since 1.2 69 */ 70 71 public interface X509Extension { 72 73 /** 74 * Check if there is a critical extension that is not supported. 75 * 76 * @return {@code true} if a critical extension is found that is 77 * not supported, otherwise {@code false}. 78 */ hasUnsupportedCriticalExtension()79 public boolean hasUnsupportedCriticalExtension(); 80 81 /** 82 * Gets a Set of the OID strings for the extension(s) marked 83 * CRITICAL in the certificate/CRL managed by the object 84 * implementing this interface. 85 * 86 * Here is sample code to get a Set of critical extensions from an 87 * X509Certificate and print the OIDs: 88 * <pre>{@code 89 * X509Certificate cert = null; 90 * try (InputStream inStrm = new FileInputStream("DER-encoded-Cert")) { 91 * CertificateFactory cf = CertificateFactory.getInstance("X.509"); 92 * cert = (X509Certificate)cf.generateCertificate(inStrm); 93 * } 94 * 95 * Set<String> critSet = cert.getCriticalExtensionOIDs(); 96 * if (critSet != null && !critSet.isEmpty()) { 97 * System.out.println("Set of critical extensions:"); 98 * for (String oid : critSet) { 99 * System.out.println(oid); 100 * } 101 * } 102 * }</pre> 103 * @return a Set (or an empty Set if none are marked critical) of 104 * the extension OID strings for extensions that are marked critical. 105 * If there are no extensions present at all, then this method returns 106 * null. 107 */ getCriticalExtensionOIDs()108 public Set<String> getCriticalExtensionOIDs(); 109 110 /** 111 * Gets a Set of the OID strings for the extension(s) marked 112 * NON-CRITICAL in the certificate/CRL managed by the object 113 * implementing this interface. 114 * 115 * Here is sample code to get a Set of non-critical extensions from an 116 * X509CRL revoked certificate entry and print the OIDs: 117 * <pre>{@code 118 * CertificateFactory cf = null; 119 * X509CRL crl = null; 120 * try (InputStream inStrm = new FileInputStream("DER-encoded-CRL")) { 121 * cf = CertificateFactory.getInstance("X.509"); 122 * crl = (X509CRL)cf.generateCRL(inStrm); 123 * } 124 * 125 * byte[] certData = <DER-encoded certificate data> 126 * ByteArrayInputStream bais = new ByteArrayInputStream(certData); 127 * X509Certificate cert = (X509Certificate)cf.generateCertificate(bais); 128 * X509CRLEntry badCert = 129 * crl.getRevokedCertificate(cert.getSerialNumber()); 130 * 131 * if (badCert != null) { 132 * Set<String> nonCritSet = badCert.getNonCriticalExtensionOIDs(); 133 * if (nonCritSet != null) 134 * for (String oid : nonCritSet) { 135 * System.out.println(oid); 136 * } 137 * } 138 * }</pre> 139 * 140 * @return a Set (or an empty Set if none are marked non-critical) of 141 * the extension OID strings for extensions that are marked non-critical. 142 * If there are no extensions present at all, then this method returns 143 * null. 144 */ getNonCriticalExtensionOIDs()145 public Set<String> getNonCriticalExtensionOIDs(); 146 147 /** 148 * Gets the DER-encoded OCTET string for the extension value 149 * (<em>extnValue</em>) identified by the passed-in {@code oid} 150 * String. 151 * The {@code oid} string is 152 * represented by a set of nonnegative whole numbers separated 153 * by periods. 154 * 155 * <p>For example:<br> 156 * <table class="striped"> 157 * <caption style="display:none">Examples of OIDs and extension names</caption> 158 * <thead> 159 * <tr> 160 * <th scope="col">OID <em>(Object Identifier)</em></th> 161 * <th scope="col">Extension Name</th></tr> 162 * </thead> 163 * <tbody style="text-align:left"> 164 * <tr><th scope="row">2.5.29.14</th> 165 * <td>SubjectKeyIdentifier</td></tr> 166 * <tr><th scope="row">2.5.29.15</th> 167 * <td>KeyUsage</td></tr> 168 * <tr><th scope="row">2.5.29.16</th> 169 * <td>PrivateKeyUsage</td></tr> 170 * <tr><th scope="row">2.5.29.17</th> 171 * <td>SubjectAlternativeName</td></tr> 172 * <tr><th scope="row">2.5.29.18</th> 173 * <td>IssuerAlternativeName</td></tr> 174 * <tr><th scope="row">2.5.29.19</th> 175 * <td>BasicConstraints</td></tr> 176 * <tr><th scope="row">2.5.29.30</th> 177 * <td>NameConstraints</td></tr> 178 * <tr><th scope="row">2.5.29.33</th> 179 * <td>PolicyMappings</td></tr> 180 * <tr><th scope="row">2.5.29.35</th> 181 * <td>AuthorityKeyIdentifier</td></tr> 182 * <tr><th scope="row">2.5.29.36</th> 183 * <td>PolicyConstraints</td></tr> 184 * </tbody> 185 * </table> 186 * 187 * @param oid the Object Identifier value for the extension. 188 * @return the DER-encoded octet string of the extension value or 189 * null if it is not present. 190 */ getExtensionValue(String oid)191 public byte[] getExtensionValue(String oid); 192 } 193