/*

 * Copyright (c) 2005, 2014, 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

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/*

 * $Id: KeyInfo.java,v 1.7 2005/05/10 16:35:34 mullan Exp $

 */

package javax.xml.crypto.dsig.keyinfo;

import java.util.List;

import javax.xml.crypto.MarshalException;

import javax.xml.crypto.XMLCryptoContext;

import javax.xml.crypto.XMLStructure;

/**

 * A representation of the XML <code>KeyInfo</code> element as defined in

 * the <a href="http://www.w3.org/TR/xmldsig-core/">

 * W3C Recommendation for XML-Signature Syntax and Processing</a>.

 * A <code>KeyInfo</code> contains a list of {@link XMLStructure}s, each of

 * which contain information that enables the recipient(s) to obtain the key

 * needed to validate an XML signature. The XML Schema Definition is defined as:

 *

 * <pre>

 * <element name="KeyInfo" type="ds:KeyInfoType"/>

 * <complexType name="KeyInfoType" mixed="true">

 *   <choice maxOccurs="unbounded">

 *     <element ref="ds:KeyName"/>

 *     <element ref="ds:KeyValue"/>

 *     <element ref="ds:RetrievalMethod"/>

 *     <element ref="ds:X509Data"/>

 *     <element ref="ds:PGPData"/>

 *     <element ref="ds:SPKIData"/>

 *     <element ref="ds:MgmtData"/>

 *     <any processContents="lax" namespace="##other"/>

 *     <!-- (1,1) elements from (0,unbounded) namespaces -->

 *   </choice>

 *   <attribute name="Id" type="ID" use="optional"/>

 * </complexType>

 * </pre>

 *

 * A <code>KeyInfo</code> instance may be created by invoking one of the

 * {@link KeyInfoFactory#newKeyInfo newKeyInfo} methods of the

 * {@link KeyInfoFactory} class, and passing it a list of one or more

 * <code>XMLStructure</code>s and an optional id parameter;

 * for example:

 * <pre>

 *   KeyInfoFactory factory = KeyInfoFactory.getInstance("DOM");

 *   KeyInfo keyInfo = factory.newKeyInfo

 *      (Collections.singletonList(factory.newKeyName("Alice"), "keyinfo-1"));

 * </pre>

 *

 * <p><code>KeyInfo</code> objects can also be marshalled to XML by invoking

 * the {@link #marshal marshal} method.

 *

 * @author Sean Mullan

 * @author JSR 105 Expert Group

 * @since 1.6

 * @see KeyInfoFactory#newKeyInfo(List)

 * @see KeyInfoFactory#newKeyInfo(List, String)

 */

public interface KeyInfo extends XMLStructure {

    /**

     * Returns an {@link java.util.Collections#unmodifiableList unmodifiable

     * list} containing the key information. Each entry of the list is

     * an {@link XMLStructure}.

     *

     * <p>If there is a public subclass representing the type of

     * <code>XMLStructure</code>, it is returned as an instance of that

     * class (ex: an <code>X509Data</code> element would be returned as an

     * instance of {@link javax.xml.crypto.dsig.keyinfo.X509Data}).

     *

     * @return an unmodifiable list of one or more <code>XMLStructure</code>s

     *    in this <code>KeyInfo</code>. Never returns <code>null</code> or an

     *    empty list.

     */

    List<XMLStructure> getContent();

    /**

     * Return the optional Id attribute of this <code>KeyInfo</code>, which

     * may be useful for referencing this <code>KeyInfo</code> from other

     * XML structures.

     *

     * @return the Id attribute of this <code>KeyInfo</code> (may be

     *    <code>null</code> if not specified)

     */

    String getId();

    /**

     * Marshals the key info to XML.

     *

     * @param parent a mechanism-specific structure containing the parent node

     *    that the marshalled key info will be appended to

     * @param context the <code>XMLCryptoContext</code> containing additional

     *    context (may be null if not applicable)

     * @throws ClassCastException if the type of <code>parent</code> or

     *    <code>context</code> is not compatible with this key info

     * @throws MarshalException if the key info cannot be marshalled

     * @throws NullPointerException if <code>parent</code> is <code>null</code>

     */

    void marshal(XMLStructure parent, XMLCryptoContext context)

        throws MarshalException;

}