/*

 * Copyright (c) 1996, 2013, 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

 * or visit www.oracle.com if you need additional information or have any

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 */

package sun.security.provider;

import java.util.*;

import java.io.*;

import java.math.BigInteger;

import java.security.InvalidKeyException;

import java.security.ProviderException;

import java.security.AlgorithmParameters;

import java.security.spec.DSAParameterSpec;

import java.security.spec.InvalidParameterSpecException;

import java.security.interfaces.DSAParams;

import sun.security.x509.X509Key;

import sun.security.x509.AlgIdDSA;

import sun.security.util.BitArray;

import sun.security.util.Debug;

import sun.security.util.DerValue;

import sun.security.util.DerInputStream;

import sun.security.util.DerOutputStream;

/**

 * An X.509 public key for the Digital Signature Algorithm.

 *

 * @author Benjamin Renaud

 *

 *

 * @see DSAPrivateKey

 * @see AlgIdDSA

 * @see DSA

 */

public class DSAPublicKey extends X509Key

implements java.security.interfaces.DSAPublicKey, Serializable {

    /** use serialVersionUID from JDK 1.1. for interoperability */

    private static final long serialVersionUID = -2994193307391104133L;

    /* the public key */

    private BigInteger y;

    /*

     * Keep this constructor for backwards compatibility with JDK1.1.

     */

    public DSAPublicKey() {

    }

    /**

     * Make a DSA public key out of a public key and three parameters.

     * The p, q, and g parameters may be null, but if so, parameters will need

     * to be supplied from some other source before this key can be used in

     * cryptographic operations.  PKIX RFC2459bis explicitly allows DSA public

     * keys without parameters, where the parameters are provided in the

     * issuer's DSA public key.

     *

     * @param y the actual key bits

     * @param p DSA parameter p, may be null if all of p, q, and g are null.

     * @param q DSA parameter q, may be null if all of p, q, and g are null.

     * @param g DSA parameter g, may be null if all of p, q, and g are null.

     */

    public DSAPublicKey(BigInteger y, BigInteger p, BigInteger q,

                        BigInteger g)

    throws InvalidKeyException {

        this.y = y;

        algid = new AlgIdDSA(p, q, g);

        try {

            byte[] keyArray = new DerValue(DerValue.tag_Integer,

                               y.toByteArray()).toByteArray();

            setKey(new BitArray(keyArray.length*8, keyArray));

            encode();

        } catch (IOException e) {

            throw new InvalidKeyException("could not DER encode y: " +

                                          e.getMessage());

        }

    }

    /**

     * Make a DSA public key from its DER encoding (X.509).

     */

    public DSAPublicKey(byte[] encoded) throws InvalidKeyException {

        decode(encoded);

    }

    /**

     * Returns the DSA parameters associated with this key, or null if the

     * parameters could not be parsed.

     */

    public DSAParams getParams() {

        try {

            if (algid instanceof DSAParams) {

                return (DSAParams)algid;

            } else {

                DSAParameterSpec paramSpec;

                AlgorithmParameters algParams = algid.getParameters();

                if (algParams == null) {

                    return null;

                }

                paramSpec = algParams.getParameterSpec(DSAParameterSpec.class);

                return (DSAParams)paramSpec;

            }

        } catch (InvalidParameterSpecException e) {

            return null;

        }

    }

    /**

     * Get the raw public value, y, without the parameters.

     *

     * @see getParameters

     */

    public BigInteger getY() {

        return y;

    }

    public String toString() {

        return "Sun DSA Public Key\n    Parameters:" + algid

            + "\n  y:\n" + Debug.toHexString(y) + "\n";

    }

    protected void parseKeyBits() throws InvalidKeyException {

        try {

            DerInputStream in = new DerInputStream(getKey().toByteArray());

            y = in.getBigInteger();

        } catch (IOException e) {

            throw new InvalidKeyException("Invalid key: y value\n" +

                                          e.getMessage());

        }

    }

}