/*

 * Copyright 1997-2006 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.security.x509;

import java.io.IOException;

import java.io.OutputStream;

import java.util.Enumeration;

import sun.security.util.*;

/**

 * Represent the Subject Key Identifier Extension.

 *

 * This extension, if present, provides a means of identifying the particular

 * public key used in an application.  This extension by default is marked

 * non-critical.

 *

 * <p>Extensions are addiitonal attributes which can be inserted in a X509

 * v3 certificate. For example a "Driving License Certificate" could have

 * the driving license number as a extension.

 *

 * <p>Extensions are represented as a sequence of the extension identifier

 * (Object Identifier), a boolean flag stating whether the extension is to

 * be treated as being critical and the extension value itself (this is again

 * a DER encoding of the extension value).

 *

 * @author Amit Kapoor

 * @author Hemma Prafullchandra

 * @see Extension

 * @see CertAttrSet

 */

public class SubjectKeyIdentifierExtension extends Extension

implements CertAttrSet<String> {

    /**

     * Identifier for this attribute, to be used with the

     * get, set, delete methods of Certificate, x509 type.

     */

    public static final String IDENT =

                         "x509.info.extensions.SubjectKeyIdentifier";

    /**

     * Attribute names.

     */

    public static final String NAME = "SubjectKeyIdentifier";

    public static final String KEY_ID = "key_id";

    // Private data member

    private KeyIdentifier id = null;

    // Encode this extension value

    private void encodeThis() throws IOException {

        if (id == null) {

            this.extensionValue = null;

            return;

        }

        DerOutputStream os = new DerOutputStream();

        id.encode(os);

        this.extensionValue = os.toByteArray();

    }

    /**

     * Create a SubjectKeyIdentifierExtension with the passed octet string.

     * The criticality is set to False.

     * @param octetString the octet string identifying the key identifier.

     */

    public SubjectKeyIdentifierExtension(byte[] octetString)

    throws IOException {

        id = new KeyIdentifier(octetString);

        this.extensionId = PKIXExtensions.SubjectKey_Id;

        this.critical = false;

        encodeThis();

    }

    /**

     * Create the extension from the passed DER encoded value.

     *

     * @param critical true if the extension is to be treated as critical.

     * @param value an array of DER encoded bytes of the actual value.

     * @exception ClassCastException if value is not an array of bytes

     * @exception IOException on error.

     */

    public SubjectKeyIdentifierExtension(Boolean critical, Object value)

    throws IOException {

        this.extensionId = PKIXExtensions.SubjectKey_Id;

        this.critical = critical.booleanValue();

        this.extensionValue = (byte[]) value;

        DerValue val = new DerValue(this.extensionValue);

        this.id = new KeyIdentifier(val);

    }

    /**

     * Returns a printable representation.

     */

    public String toString() {

        return super.toString() + "SubjectKeyIdentifier [\n"

                + String.valueOf(id) + "]\n";

    }

    /**

     * Write the extension to the OutputStream.

     *

     * @param out the OutputStream to write the extension to.

     * @exception IOException on encoding errors.

     */

    public void encode(OutputStream out) throws IOException {

        DerOutputStream tmp = new DerOutputStream();

        if (extensionValue == null) {

            extensionId = PKIXExtensions.SubjectKey_Id;

            critical = false;

            encodeThis();

        }

        super.encode(tmp);

        out.write(tmp.toByteArray());

    }

    /**

     * Set the attribute value.

     */

    public void set(String name, Object obj) throws IOException {

        if (name.equalsIgnoreCase(KEY_ID)) {

            if (!(obj instanceof KeyIdentifier)) {

              throw new IOException("Attribute value should be of" +

                                    " type KeyIdentifier.");

            }

            id = (KeyIdentifier)obj;

        } else {

          throw new IOException("Attribute name not recognized by " +

                "CertAttrSet:SubjectKeyIdentifierExtension.");

        }

        encodeThis();

    }

    /**

     * Get the attribute value.

     */

    public Object get(String name) throws IOException {

        if (name.equalsIgnoreCase(KEY_ID)) {

            return (id);

        } else {

          throw new IOException("Attribute name not recognized by " +

                "CertAttrSet:SubjectKeyIdentifierExtension.");

        }

    }

    /**

     * Delete the attribute value.

     */

    public void delete(String name) throws IOException {

        if (name.equalsIgnoreCase(KEY_ID)) {

            id = null;

        } else {

          throw new IOException("Attribute name not recognized by " +

                "CertAttrSet:SubjectKeyIdentifierExtension.");

        }

        encodeThis();

    }

    /**

     * Return an enumeration of names of attributes existing within this

     * attribute.

     */

    public Enumeration<String> getElements() {

        AttributeNameEnumeration elements = new AttributeNameEnumeration();

        elements.addElement(KEY_ID);

        return (elements.elements());

    }

    /**

     * Return the name of this attribute.

     */

    public String getName() {

        return (NAME);

    }

}