/*

 * Copyright 1997-1999 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.security.PublicKey;

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;

import sun.misc.HexDumpEncoder;

import sun.security.util.*;

/**

 * Represent the Key Identifier ASN.1 object.

 *

 * @author Amit Kapoor

 * @author Hemma Prafullchandra

 */

public class KeyIdentifier {

    private byte[] octetString;

    /**

     * Create a KeyIdentifier with the passed bit settings.

     *

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

     */

    public KeyIdentifier(byte[] octetString) {

        this.octetString = octetString.clone();

    }

    /**

     * Create a KeyIdentifier from the DER encoded value.

     *

     * @param val the DerValue

     */

    public KeyIdentifier(DerValue val) throws IOException {

        octetString = val.getOctetString();

    }

    /**

     * Creates a KeyIdentifier from a public-key value.

     *

     * <p>From RFC2459: Two common methods for generating key identifiers from

     * the public key are:

     * <ol>

     * <li>The keyIdentifier is composed of the 160-bit SHA-1 hash of the

     * value of the BIT STRING subjectPublicKey (excluding the tag,

     * length, and number of unused bits).

     * <p>

     * <li>The keyIdentifier is composed of a four bit type field with

     * the value 0100 followed by the least significant 60 bits of the

     * SHA-1 hash of the value of the BIT STRING subjectPublicKey.

     * </ol>

     * <p>This method supports method 1.

     *

     * @param pubKey the public key from which to construct this KeyIdentifier

     * @throws IOException on parsing errors

     */

    public KeyIdentifier(PublicKey pubKey)

        throws IOException

    {

        DerValue algAndKey = new DerValue(pubKey.getEncoded());

        if (algAndKey.tag != DerValue.tag_Sequence)

            throw new IOException("PublicKey value is not a valid "

                                  + "X.509 public key");

        AlgorithmId algid = AlgorithmId.parse(algAndKey.data.getDerValue());

        byte[] key = algAndKey.data.getUnalignedBitString().toByteArray();

        MessageDigest md = null;

        try {

            md = MessageDigest.getInstance("SHA1");

        } catch (NoSuchAlgorithmException e3) {

            throw new IOException("SHA1 not supported");

        }

        md.update(key);

        this.octetString = md.digest();

    }

    /**

     * Return the value of the KeyIdentifier as byte array.

     */

    public byte[] getIdentifier() {

        return octetString.clone();

    }

    /**

     * Returns a printable representation of the KeyUsage.

     */

    public String toString() {

        String s = "KeyIdentifier [\n";

        HexDumpEncoder encoder = new HexDumpEncoder();

        s += encoder.encodeBuffer(octetString);

        s += "]\n";

        return (s);

    }

    /**

     * Write the KeyIdentifier to the DerOutputStream.

     *

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

     * @exception IOException

     */

    void encode(DerOutputStream out) throws IOException {

        out.putOctetString(octetString);

    }

    /**

     * Returns a hash code value for this object.

     * Objects that are equal will also have the same hashcode.

     */

    public int hashCode () {

        int retval = 0;

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

            retval += octetString[i] * i;

        return retval;

    }

    /**

     * Indicates whether some other object is "equal to" this one.

     */

    public boolean equals(Object other) {

        if (this == other)

            return true;

        if (!(other instanceof KeyIdentifier))

            return false;

        return java.util.Arrays.equals(octetString,

                                       ((KeyIdentifier)other).getIdentifier());

    }

}