alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (AlgIdDSA.java)

This example Java source code file (AlgIdDSA.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

algiddsa, algorithm, algorithmid, biginteger, construct, deprecated, deroutputstream, dervalue, dsa, dsa_oid, dss\/dsa, ioexception, math, providerexception, security, string

The AlgIdDSA.java Java example source code

/*
 * 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
 * questions.
 */

package sun.security.x509;

import java.io.IOException;
import java.math.BigInteger;
import java.security.*;
import java.security.interfaces.DSAParams;

import sun.security.util.*;


/**
 * This class identifies DSS/DSA Algorithm variants, which are distinguished
 * by using different algorithm parameters <em>P, Q, G.  It uses the
 * NIST/IETF standard DER encoding.  These are used to implement the Digital
 * Signature Standard (DSS), FIPS 186.
 *
 * <P>NOTE:  DSS/DSA Algorithm IDs may be created without these
 * parameters.  Use of DSS/DSA in modes where parameters are
 * either implicit (e.g. a default applicable to a site or a larger scope),
 * or are derived from some Certificate Authority's DSS certificate, is
 * not supported directly.  The application is responsible for creating a key
 * containing the required parameters prior to using the key in cryptographic
 * operations.  The follwoing is an example of how this may be done assuming
 * that we have a certificate called <code>currentCert which doesn't
 * contain DSS/DSA parameters and we need to derive DSS/DSA parameters
 * from a CA's certificate called <code>caCert.
 * <p>
 * <code>
 * // key containing parameters to use
 * DSAPublicKey cAKey = (DSAPublicKey)(caCert.getPublicKey());
 * // key without parameters
 * DSAPublicKey nullParamsKey = (DSAPublicKey)(currentCert.getPublicKey());
 *
 * DSAParams cAKeyParams = cAKey.getParams();
 * KeyFactory kf = KeyFactory.getInstance("DSA");
 * DSAPublicKeySpec ks = new DSAPublicKeySpec(nullParamsKey.getY(),
 *                                            cAKeyParams.getP(),
 *                                            cAKeyParams.getQ(),
 *                                            cAKeyParams.getG());
 * DSAPublicKey usableKey = kf.generatePublic(ks);
 * </pre>
 *
 * @see java.security.interfaces.DSAParams
 * @see java.security.interfaces.DSAPublicKey
 * @see java.security.KeyFactory
 * @see java.security.spec.DSAPublicKeySpec
 *
 * @author David Brownell
 */
public final
class AlgIdDSA extends AlgorithmId implements DSAParams
{

    private static final long serialVersionUID = 3437177836797504046L;

    /*
     * The three unsigned integer parameters.
     */
    private BigInteger  p , q, g;

    /** Returns the DSS/DSA parameter "P" */
    public BigInteger   getP () { return p; }

    /** Returns the DSS/DSA parameter "Q" */
    public BigInteger   getQ () { return q; }

    /** Returns the DSS/DSA parameter "G" */
    public BigInteger   getG () { return g; }

    /**
     * Default constructor.  The OID and parameters must be
     * deserialized before this algorithm ID is used.
     */
    @Deprecated
    public AlgIdDSA () {}

    AlgIdDSA (DerValue val) throws IOException
        { super(val.getOID()); }

    /**
     * Construct an AlgIdDSA from an X.509 encoded byte array.
     */
    public AlgIdDSA (byte[] encodedAlg) throws IOException
        { super (new DerValue(encodedAlg).getOID()); }

    /**
     * Constructs a DSS/DSA Algorithm ID from unsigned integers that
     * define the algorithm parameters.  Those integers are encoded
     * as big-endian byte arrays.
     *
     * @param p the DSS/DSA parameter "P"
     * @param q the DSS/DSA parameter "Q"
     * @param g the DSS/DSA parameter "G"
     */
    public AlgIdDSA (byte p [], byte q [], byte g [])
    throws IOException
    {
        this (new BigInteger (1, p),
            new BigInteger (1, q),
            new BigInteger (1, g));
    }

    /**
     * Constructs a DSS/DSA Algorithm ID from numeric parameters.
     * If all three are null, then the parameters portion of the algorithm id
     * is set to null.  See note in header regarding use.
     *
     * @param p the DSS/DSA parameter "P"
     * @param q the DSS/DSA parameter "Q"
     * @param g the DSS/DSA parameter "G"
     */
    public AlgIdDSA (BigInteger p, BigInteger q, BigInteger g)
    {
        super (DSA_oid);

        if (p != null || q != null || g != null) {
            if (p == null || q == null || g == null)
                throw new ProviderException("Invalid parameters for DSS/DSA" +
                                            " Algorithm ID");
            try {
                this.p = p;
                this.q = q;
                this.g = g;
                initializeParams ();

            } catch (IOException e) {
                /* this should not happen */
                throw new ProviderException ("Construct DSS/DSA Algorithm ID");
            }
        }
    }

    /**
     * Returns "DSA", indicating the Digital Signature Algorithm (DSA) as
     * defined by the Digital Signature Standard (DSS), FIPS 186.
     */
    public String getName ()
        { return "DSA"; }


    /*
     * For algorithm IDs which haven't been created from a DER encoded
     * value, "params" must be created.
     */
    private void initializeParams ()
    throws IOException
    {
        DerOutputStream out = new DerOutputStream ();

        out.putInteger(p);
        out.putInteger(q);
        out.putInteger(g);
        params = new DerValue (DerValue.tag_Sequence,out.toByteArray ());
    }

    /**
     * Parses algorithm parameters P, Q, and G.  They're found
     * in the "params" member, which never needs to be changed.
     */
    protected void decodeParams ()
    throws IOException
    {
        if (params == null)
            throw new IOException("DSA alg params are null");
        if (params.tag != DerValue.tag_Sequence)
            throw new  IOException("DSA alg parsing error");

        params.data.reset ();

        this.p = params.data.getBigInteger();
        this.q = params.data.getBigInteger();
        this.g = params.data.getBigInteger();

        if (params.data.available () != 0)
            throw new IOException ("AlgIdDSA params, extra="+
                                   params.data.available ());
    }


    /*
     * Returns a formatted string describing the parameters.
     */
    public String toString ()
        { return paramsToString (); }

    /*
     * Returns a string describing the parameters.
     */
    protected String paramsToString ()
    {
        if (params == null)
            return " null\n";
        else
            return
                "\n    p:\n" + Debug.toHexString(p) +
                "\n    q:\n" + Debug.toHexString(q) +
                "\n    g:\n" + Debug.toHexString(g) +
                "\n";
    }
}

Other Java examples (source code examples)

Here is a short list of links related to this Java AlgIdDSA.java source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2024 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.