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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</code>
* method returns the DER-encoded OCTET STRING of the
* extension value (i.e., the <code>extnValue</code>). This can then
* be handled by a <em>Class</em> that understands the extension.
*
* @author Hemma Prafullchandra
*/
public interface X509Extension {
/**
* Check if there is a critical extension that is not supported.
*
* @return <tt>true</tt> if a critical extension is found that is
* not supported, otherwise <tt>false</tt>.
*/
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>
* InputStream inStrm = null;
* X509Certificate cert = null;
* try {
* inStrm = new FileInputStream("DER-encoded-Cert");
* CertificateFactory cf = CertificateFactory.getInstance("X.509");
* cert = (X509Certificate)cf.generateCertificate(inStrm);
* } finally {
* if (inStrm != null) {
* inStrm.close();
* }
* }<p>
*
* 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);
* }
* }
* </code></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>
* InputStream inStrm = null;
* CertificateFactory cf = null;
* X509CRL crl = null;
* try {
* inStrm = new FileInputStream("DER-encoded-CRL");
* cf = CertificateFactory.getInstance("X.509");
* crl = (X509CRL)cf.generateCRL(inStrm);
* } finally {
* if (inStrm != null) {
* inStrm.close();
* }
* }<p>
*
* byte[] certData = <DER-encoded certificate data>
* ByteArrayInputStream bais = new ByteArrayInputStream(certData);
* X509Certificate cert = (X509Certificate)cf.generateCertificate(bais);
* bais.close();
* X509CRLEntry badCert =
* crl.getRevokedCertificate(cert.getSerialNumber());<p>
*
* if (badCert != null) {
* Set<String> nonCritSet = badCert.getNonCriticalExtensionOIDs();<p>
* if (nonCritSet != null)
* for (String oid : nonCritSet) {
* System.out.println(oid);
* }
* }
* </code></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</code>
* String.
* The <code>oid</code> string is
* represented by a set of nonnegative whole numbers separated
* by periods.
*
* <p>For example:<br>
* <table border=groove summary="Examples of OIDs and extension names">
* <tr>
* <th>OID <em>(Object Identifier)</em></th>
* <th>Extension Name</th></tr>
* <tr><td>2.5.29.14</td>
* <td>SubjectKeyIdentifier</td></tr>
* <tr><td>2.5.29.15</td>
* <td>KeyUsage</td></tr>
* <tr><td>2.5.29.16</td>
* <td>PrivateKeyUsage</td></tr>
* <tr><td>2.5.29.17</td>
* <td>SubjectAlternativeName</td></tr>
* <tr><td>2.5.29.18</td>
* <td>IssuerAlternativeName</td></tr>
* <tr><td>2.5.29.19</td>
* <td>BasicConstraints</td></tr>
* <tr><td>2.5.29.30</td>
* <td>NameConstraints</td></tr>
* <tr><td>2.5.29.33</td>
* <td>PolicyMappings</td></tr>
* <tr><td>2.5.29.35</td>
* <td>AuthorityKeyIdentifier</td></tr>
* <tr><td>2.5.29.36</td>
* <td>PolicyConstraints</td></tr>
* </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);
}