Java tutorial
/* * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.security.cert; import java.util.Set; /** * Interface for an X.509 extension. * * <p>The extensions defined for X.509 v3 * {@link X509Certificate Certificates} and v2 * {@link X509CRL CRLs} (Certificate Revocation * Lists) provide methods * for associating additional attributes with users or public keys, * for managing the certification hierarchy, and for managing CRL * distribution. The X.509 extensions format also allows communities * to define private extensions to carry information unique to those * communities. * * <p>Each extension in a certificate/CRL may be designated as * critical or non-critical. A certificate/CRL-using system (an application * validating a certificate/CRL) must reject the certificate/CRL if it * encounters a critical extension it does not recognize. A non-critical * extension may be ignored if it is not recognized. * <p> * The ASN.1 definition for this is: * <pre> * Extensions ::= SEQUENCE SIZE (1..MAX) OF Extension * * Extension ::= SEQUENCE { * extnId OBJECT IDENTIFIER, * critical BOOLEAN DEFAULT FALSE, * extnValue OCTET STRING * -- contains a DER encoding of a value * -- of the type registered for use with * -- the extnId object identifier value * } * </pre> * Since not all extensions are known, the {@code getExtensionValue} * method returns the DER-encoded OCTET STRING of the * extension value (i.e., the {@code extnValue}). This can then * be handled by a <em>Class</em> that understands the extension. * * @author Hemma Prafullchandra * @since 1.2 */ public interface X509Extension { /** * Check if there is a critical extension that is not supported. * * @return {@code true} if a critical extension is found that is * not supported, otherwise {@code false}. */ public boolean hasUnsupportedCriticalExtension(); /** * Gets a Set of the OID strings for the extension(s) marked * CRITICAL in the certificate/CRL managed by the object * implementing this interface. * * Here is sample code to get a Set of critical extensions from an * X509Certificate and print the OIDs: * <pre>{@code * X509Certificate cert = null; * try (InputStream inStrm = new FileInputStream("DER-encoded-Cert")) { * CertificateFactory cf = CertificateFactory.getInstance("X.509"); * cert = (X509Certificate)cf.generateCertificate(inStrm); * } * * Set<String> critSet = cert.getCriticalExtensionOIDs(); * if (critSet != null && !critSet.isEmpty()) { * System.out.println("Set of critical extensions:"); * for (String oid : critSet) { * System.out.println(oid); * } * } * }</pre> * @return a Set (or an empty Set if none are marked critical) of * the extension OID strings for extensions that are marked critical. * If there are no extensions present at all, then this method returns * null. */ public Set<String> getCriticalExtensionOIDs(); /** * Gets a Set of the OID strings for the extension(s) marked * NON-CRITICAL in the certificate/CRL managed by the object * implementing this interface. * * Here is sample code to get a Set of non-critical extensions from an * X509CRL revoked certificate entry and print the OIDs: * <pre>{@code * CertificateFactory cf = null; * X509CRL crl = null; * try (InputStream inStrm = new FileInputStream("DER-encoded-CRL")) { * cf = CertificateFactory.getInstance("X.509"); * crl = (X509CRL)cf.generateCRL(inStrm); * } * * byte[] certData = <DER-encoded certificate data> * ByteArrayInputStream bais = new ByteArrayInputStream(certData); * X509Certificate cert = (X509Certificate)cf.generateCertificate(bais); * X509CRLEntry badCert = * crl.getRevokedCertificate(cert.getSerialNumber()); * * if (badCert != null) { * Set<String> nonCritSet = badCert.getNonCriticalExtensionOIDs(); * if (nonCritSet != null) * for (String oid : nonCritSet) { * System.out.println(oid); * } * } * }</pre> * * @return a Set (or an empty Set if none are marked non-critical) of * the extension OID strings for extensions that are marked non-critical. * If there are no extensions present at all, then this method returns * null. */ public Set<String> getNonCriticalExtensionOIDs(); /** * Gets the DER-encoded OCTET string for the extension value * (<em>extnValue</em>) identified by the passed-in {@code oid} * String. * The {@code oid} string is * represented by a set of nonnegative whole numbers separated * by periods. * * <p>For example:<br> * <table class="striped"> * <caption style="display:none">Examples of OIDs and extension names</caption> * <thead> * <tr> * <th scope="col">OID <em>(Object Identifier)</em></th> * <th scope="col">Extension Name</th></tr> * </thead> * <tbody style="text-align:left"> * <tr><th scope="row">2.5.29.14</th> * <td>SubjectKeyIdentifier</td></tr> * <tr><th scope="row">2.5.29.15</th> * <td>KeyUsage</td></tr> * <tr><th scope="row">2.5.29.16</th> * <td>PrivateKeyUsage</td></tr> * <tr><th scope="row">2.5.29.17</th> * <td>SubjectAlternativeName</td></tr> * <tr><th scope="row">2.5.29.18</th> * <td>IssuerAlternativeName</td></tr> * <tr><th scope="row">2.5.29.19</th> * <td>BasicConstraints</td></tr> * <tr><th scope="row">2.5.29.30</th> * <td>NameConstraints</td></tr> * <tr><th scope="row">2.5.29.33</th> * <td>PolicyMappings</td></tr> * <tr><th scope="row">2.5.29.35</th> * <td>AuthorityKeyIdentifier</td></tr> * <tr><th scope="row">2.5.29.36</th> * <td>PolicyConstraints</td></tr> * </tbody> * </table> * * @param oid the Object Identifier value for the extension. * @return the DER-encoded octet string of the extension value or * null if it is not present. */ public byte[] getExtensionValue(String oid); }