/*

 * 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.security.cert.CertificateException;

import java.security.cert.CertificateParsingException;

import java.security.cert.CertificateExpiredException;

import java.security.cert.CertificateNotYetValidException;

import java.util.Date;

import java.util.Enumeration;

import sun.security.util.*;

/**

 * This class defines the Private Key Usage Extension.

 *

 * <p>The Private Key Usage Period extension allows the certificate issuer

 * to specify a different validity period for the private key than the

 * certificate. This extension is intended for use with digital

 * signature keys.  This extension consists of two optional components

 * notBefore and notAfter.  The private key associated with the

 * certificate should not be used to sign objects before or after the

 * times specified by the two components, respectively.

 *

 * <pre>

 * PrivateKeyUsagePeriod ::= SEQUENCE {

 *     notBefore  [0]  GeneralizedTime OPTIONAL,

 *     notAfter   [1]  GeneralizedTime OPTIONAL }

 * </pre>

 *

 * @author Amit Kapoor

 * @author Hemma Prafullchandra

 * @see Extension

 * @see CertAttrSet

 */

public class PrivateKeyUsageExtension 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.PrivateKeyUsage";

    /**

     * Sub attributes name for this CertAttrSet.

     */

    public static final String NAME = "PrivateKeyUsage";

    public static final String NOT_BEFORE = "not_before";

    public static final String NOT_AFTER = "not_after";

    // Private data members

    private static final byte TAG_BEFORE = 0;

    private static final byte TAG_AFTER = 1;

    private Date        notBefore = null;

    private Date        notAfter = null;

    // Encode this extension value.

    private void encodeThis() throws IOException {

        if (notBefore == null && notAfter == null) {

            this.extensionValue = null;

            return;

        }

        DerOutputStream seq = new DerOutputStream();

        DerOutputStream tagged = new DerOutputStream();

        if (notBefore != null) {

            DerOutputStream tmp = new DerOutputStream();

            tmp.putGeneralizedTime(notBefore);

            tagged.writeImplicit(DerValue.createTag(DerValue.TAG_CONTEXT,

                                 false, TAG_BEFORE), tmp);

        }

        if (notAfter != null) {

            DerOutputStream tmp = new DerOutputStream();

            tmp.putGeneralizedTime(notAfter);

            tagged.writeImplicit(DerValue.createTag(DerValue.TAG_CONTEXT,

                                 false, TAG_AFTER), tmp);

        }

        seq.write(DerValue.tag_Sequence, tagged);

        this.extensionValue = seq.toByteArray();

    }

    /**

     * The default constructor for PrivateKeyUsageExtension.

     *

     * @param notBefore the date/time before which the private key

     *         should not be used.

     * @param notAfter the date/time after which the private key

     *         should not be used.

     */

    public PrivateKeyUsageExtension(Date notBefore, Date notAfter)

    throws IOException {

        this.notBefore = notBefore;

        this.notAfter = notAfter;

        this.extensionId = PKIXExtensions.PrivateKeyUsage_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 CertificateException on certificate parsing errors.

     * @exception IOException on error.

     */

    public PrivateKeyUsageExtension(Boolean critical, Object value)

    throws CertificateException, IOException {

        this.extensionId = PKIXExtensions.PrivateKeyUsage_Id;

        this.critical = critical.booleanValue();

        this.extensionValue = (byte[]) value;

        DerInputStream str = new DerInputStream(this.extensionValue);

        DerValue[] seq = str.getSequence(2);

        // NB. this is always encoded with the IMPLICIT tag

        // The checks only make sense if we assume implicit tagging,

        // with explicit tagging the form is always constructed.

        for (int i = 0; i < seq.length; i++) {

            DerValue opt = seq[i];

            if (opt.isContextSpecific(TAG_BEFORE) &&

                !opt.isConstructed()) {

                if (notBefore != null) {

                    throw new CertificateParsingException(

                        "Duplicate notBefore in PrivateKeyUsage.");

                }

                opt.resetTag(DerValue.tag_GeneralizedTime);

                str = new DerInputStream(opt.toByteArray());

                notBefore = str.getGeneralizedTime();

            } else if (opt.isContextSpecific(TAG_AFTER) &&

                       !opt.isConstructed()) {

                if (notAfter != null) {

                    throw new CertificateParsingException(

                        "Duplicate notAfter in PrivateKeyUsage.");

                }

                opt.resetTag(DerValue.tag_GeneralizedTime);

                str = new DerInputStream(opt.toByteArray());

                notAfter = str.getGeneralizedTime();

            } else

                throw new IOException("Invalid encoding of " +

                                      "PrivateKeyUsageExtension");

        }

    }

    /**

     * Return the printable string.

     */

    public String toString() {

        return(super.toString() +

                "PrivateKeyUsage: [\n" +

                ((notBefore == null) ? "" : "From: " + notBefore.toString() + ", ")

                + ((notAfter == null) ? "" : "To: " + notAfter.toString())

                + "]\n");

    }

    /**

     * Verify that that the current time is within the validity period.

     *

     * @exception CertificateExpiredException if the certificate has expired.

     * @exception CertificateNotYetValidException if the certificate is not

     * yet valid.

     */

    public void valid()

    throws CertificateNotYetValidException, CertificateExpiredException {

        Date now = new Date();

        valid(now);

    }

    /**

     * Verify that that the passed time is within the validity period.

     *

     * @exception CertificateExpiredException if the certificate has expired

     * with respect to the <code>Date</code> supplied.

     * @exception CertificateNotYetValidException if the certificate is not

     * yet valid with respect to the <code>Date</code> supplied.

     *

     */

    public void valid(Date now)

    throws CertificateNotYetValidException, CertificateExpiredException {

        /*

         * we use the internal Dates rather than the passed in Date

         * because someone could override the Date methods after()

         * and before() to do something entirely different.

         */

        if (notBefore.after(now)) {

            throw new CertificateNotYetValidException("NotBefore: " +

                                                      notBefore.toString());

        }

        if (notAfter.before(now)) {

            throw new CertificateExpiredException("NotAfter: " +

                                                  notAfter.toString());

        }

    }

    /**

     * 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.PrivateKeyUsage_Id;

            critical = false;

            encodeThis();

        }

        super.encode(tmp);

        out.write(tmp.toByteArray());

    }

    /**

     * Set the attribute value.

     * @exception CertificateException on attribute handling errors.

     */

    public void set(String name, Object obj)

    throws CertificateException, IOException {

        if (!(obj instanceof Date)) {

            throw new CertificateException("Attribute must be of type Date.");

        }

        if (name.equalsIgnoreCase(NOT_BEFORE)) {

            notBefore = (Date)obj;

        } else if (name.equalsIgnoreCase(NOT_AFTER)) {

            notAfter = (Date)obj;

        } else {

          throw new CertificateException("Attribute name not recognized by"

                           + " CertAttrSet:PrivateKeyUsage.");

        }

        encodeThis();

    }

    /**

     * Get the attribute value.

     * @exception CertificateException on attribute handling errors.

     */

    public Object get(String name) throws CertificateException {

      if (name.equalsIgnoreCase(NOT_BEFORE)) {

          return (new Date(notBefore.getTime()));

      } else if (name.equalsIgnoreCase(NOT_AFTER)) {

          return (new Date(notAfter.getTime()));

      } else {

          throw new CertificateException("Attribute name not recognized by"

                           + " CertAttrSet:PrivateKeyUsage.");

      }

  }

    /**

     * Delete the attribute value.

     * @exception CertificateException on attribute handling errors.

     */

    public void delete(String name) throws CertificateException, IOException {

        if (name.equalsIgnoreCase(NOT_BEFORE)) {

            notBefore = null;

        } else if (name.equalsIgnoreCase(NOT_AFTER)) {

            notAfter = null;

        } else {

          throw new CertificateException("Attribute name not recognized by"

                           + " CertAttrSet:PrivateKeyUsage.");

        }

        encodeThis();

    }

    /**

     * Return an enumeration of names of attributes existing within this

     * attribute.

     */

    public Enumeration<String> getElements() {

        AttributeNameEnumeration elements = new AttributeNameEnumeration();

        elements.addElement(NOT_BEFORE);

        elements.addElement(NOT_AFTER);

        return(elements.elements());

    }

    /**

     * Return the name of this attribute.

     */

    public String getName() {

      return(NAME);

    }

}