/*

 * 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 Key Usage Extension.

 *

 * <p>This extension, if present, defines the purpose (e.g., encipherment,

 * signature, certificate signing) of the key contained in the certificate.

 * The usage restriction might be employed when a multipurpose key is to be

 * restricted (e.g., when an RSA key should be used only for signing or only

 * for key encipherment).

 *

 * @author Amit Kapoor

 * @author Hemma Prafullchandra

 * @see Extension

 * @see CertAttrSet

 */

public class KeyUsageExtension 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.KeyUsage";

    /**

     * Attribute names.

     */

    public static final String NAME = "KeyUsage";

    public static final String DIGITAL_SIGNATURE = "digital_signature";

    public static final String NON_REPUDIATION = "non_repudiation";

    public static final String KEY_ENCIPHERMENT = "key_encipherment";

    public static final String DATA_ENCIPHERMENT = "data_encipherment";

    public static final String KEY_AGREEMENT = "key_agreement";

    public static final String KEY_CERTSIGN = "key_certsign";

    public static final String CRL_SIGN = "crl_sign";

    public static final String ENCIPHER_ONLY = "encipher_only";

    public static final String DECIPHER_ONLY = "decipher_only";

    // Private data members

    private boolean[] bitString;

    // Encode this extension value

    private void encodeThis() throws IOException {

        DerOutputStream os = new DerOutputStream();

        os.putTruncatedUnalignedBitString(new BitArray(this.bitString));

        this.extensionValue = os.toByteArray();

    }

    /**

     * Check if bit is set.

     *

     * @param position the position in the bit string to check.

     */

    private boolean isSet(int position) {

        return bitString[position];

    }

    /**

     * Set the bit at the specified position.

     */

    private void set(int position, boolean val) {

        // enlarge bitString if necessary

        if (position >= bitString.length) {

            boolean[] tmp = new boolean[position+1];

            System.arraycopy(bitString, 0, tmp, 0, bitString.length);

            bitString = tmp;

        }

        bitString[position] = val;

    }

    /**

     * Create a KeyUsageExtension with the passed bit settings. The criticality

     * is set to true.

     *

     * @param bitString the bits to be set for the extension.

     */

    public KeyUsageExtension(byte[] bitString) throws IOException {

        this.bitString =

            new BitArray(bitString.length*8,bitString).toBooleanArray();

        this.extensionId = PKIXExtensions.KeyUsage_Id;

        this.critical = true;

        encodeThis();

    }

    /**

     * Create a KeyUsageExtension with the passed bit settings. The criticality

     * is set to true.

     *

     * @param bitString the bits to be set for the extension.

     */

    public KeyUsageExtension(boolean[] bitString) throws IOException {

        this.bitString = bitString;

        this.extensionId = PKIXExtensions.KeyUsage_Id;

        this.critical = true;

        encodeThis();

    }

    /**

     * Create a KeyUsageExtension with the passed bit settings. The criticality

     * is set to true.

     *

     * @param bitString the bits to be set for the extension.

     */

    public KeyUsageExtension(BitArray bitString) throws IOException {

        this.bitString = bitString.toBooleanArray();

        this.extensionId = PKIXExtensions.KeyUsage_Id;

        this.critical = true;

        encodeThis();

    }

    /**

     * Create the extension from the passed DER encoded value of the same.

     * The DER encoded value may be wrapped in an OCTET STRING.

     *

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

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

     * wrapped in an OCTET STRING).

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

     * @exception IOException on error.

     */

    public KeyUsageExtension(Boolean critical, Object value)

    throws IOException {

        this.extensionId = PKIXExtensions.KeyUsage_Id;

        this.critical = critical.booleanValue();

        /*

         * The following check should be activated again after

         * the PKIX profiling work becomes standard and the check

         * is not a barrier to interoperability !

         * if (!this.critical) {

         *   throw new IOException("KeyUsageExtension not marked critical,"

         *                         + " invalid profile.");

         * }

         */

        byte[] extValue = (byte[]) value;

        if (extValue[0] == DerValue.tag_OctetString) {

            this.extensionValue = new DerValue(extValue).getOctetString();

        } else {

            this.extensionValue = extValue;

        }

        DerValue val = new DerValue(this.extensionValue);

        this.bitString = val.getUnalignedBitString().toBooleanArray();

    }

    /**

     * Create a default key usage.

     */

    public KeyUsageExtension() {

        extensionId = PKIXExtensions.KeyUsage_Id;

        critical = true;

        bitString = new boolean[0];

    }

    /**

     * Set the attribute value.

     */

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

        if (!(obj instanceof Boolean)) {

            throw new IOException("Attribute must be of type Boolean.");

        }

        boolean val = ((Boolean)obj).booleanValue();

        if (name.equalsIgnoreCase(DIGITAL_SIGNATURE)) {

            set(0,val);

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

            set(1,val);

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

            set(2,val);

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

            set(3,val);

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

            set(4,val);

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

            set(5,val);

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

            set(6,val);

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

            set(7,val);

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

            set(8,val);

        } else {

          throw new IOException("Attribute name not recognized by"

                                + " CertAttrSet:KeyUsage.");

        }

        encodeThis();

    }

    /**

     * Get the attribute value.

     */

    public Object get(String name) throws IOException {

        if (name.equalsIgnoreCase(DIGITAL_SIGNATURE)) {

            return Boolean.valueOf(isSet(0));

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

            return Boolean.valueOf(isSet(1));

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

            return Boolean.valueOf(isSet(2));

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

            return Boolean.valueOf(isSet(3));

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

            return Boolean.valueOf(isSet(4));

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

            return Boolean.valueOf(isSet(5));

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

            return Boolean.valueOf(isSet(6));

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

            return Boolean.valueOf(isSet(7));

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

            return Boolean.valueOf(isSet(8));

        } else {

          throw new IOException("Attribute name not recognized by"

                                + " CertAttrSet:KeyUsage.");

        }

    }

    /**

     * Delete the attribute value.

     */

    public void delete(String name) throws IOException {

        if (name.equalsIgnoreCase(DIGITAL_SIGNATURE)) {

            set(0,false);

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

            set(1,false);

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

            set(2,false);

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

            set(3,false);

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

            set(4,false);

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

            set(5,false);

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

            set(6,false);

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

            set(7,false);

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

            set(8,false);

        } else {

          throw new IOException("Attribute name not recognized by"

                                + " CertAttrSet:KeyUsage.");

        }

        encodeThis();

    }

    /**

     * Returns a printable representation of the KeyUsage.

     */

    public String toString() {

        String s = super.toString() + "KeyUsage [\n";

        try {

            if (isSet(0)) {

                s += "  DigitalSignature\n";

            }

            if (isSet(1)) {

                s += "  Non_repudiation\n";

            }

            if (isSet(2)) {

                s += "  Key_Encipherment\n";

            }

            if (isSet(3)) {

                s += "  Data_Encipherment\n";

            }

            if (isSet(4)) {

                s += "  Key_Agreement\n";

            }

            if (isSet(5)) {

                s += "  Key_CertSign\n";

            }

            if (isSet(6)) {

                s += "  Crl_Sign\n";

            }

            if (isSet(7)) {

                s += "  Encipher_Only\n";

            }

            if (isSet(8)) {

                s += "  Decipher_Only\n";

            }

        } catch (ArrayIndexOutOfBoundsException ex) {}

        s += "]\n";

        return (s);

    }

    /**

     * Write the extension to the DerOutputStream.

     *

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

     * @exception IOException on encoding errors.

     */

    public void encode(OutputStream out) throws IOException {

       DerOutputStream  tmp = new DerOutputStream();

       if (this.extensionValue == null) {

           this.extensionId = PKIXExtensions.KeyUsage_Id;

           this.critical = true;

           encodeThis();

       }

       super.encode(tmp);

       out.write(tmp.toByteArray());

    }

    /**

     * Return an enumeration of names of attributes existing within this

     * attribute.

     */

    public Enumeration<String> getElements() {

        AttributeNameEnumeration elements = new AttributeNameEnumeration();

        elements.addElement(DIGITAL_SIGNATURE);

        elements.addElement(NON_REPUDIATION);

        elements.addElement(KEY_ENCIPHERMENT);

        elements.addElement(DATA_ENCIPHERMENT);

        elements.addElement(KEY_AGREEMENT);

        elements.addElement(KEY_CERTSIGN);

        elements.addElement(CRL_SIGN);

        elements.addElement(ENCIPHER_ONLY);

        elements.addElement(DECIPHER_ONLY);

        return (elements.elements());

    }

    public boolean[] getBits() {

        return bitString.clone();

    }

    /**

     * Return the name of this attribute.

     */

    public String getName() {

        return (NAME);

    }

}