de.tsenger.animamea.asn1.AmDHPublicKey.java Source code

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Here is the source code for de.tsenger.animamea.asn1.AmDHPublicKey.java

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/**
 *  Copyright 2011, Tobias Senger
 *  
 *  This file is part of animamea.
 *
 *  Animamea is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  Animamea 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 for more details.
 *
 *  You should have received a copy of the GNU General Public License   
 *  along with animamea.  If not, see <http://www.gnu.org/licenses/>.
 */
package de.tsenger.animamea.asn1;

import java.io.IOException;
import java.math.BigInteger;

import javax.crypto.interfaces.DHPublicKey;
import javax.crypto.spec.DHParameterSpec;

import org.bouncycastle.asn1.ASN1Encoding;
import org.bouncycastle.asn1.ASN1Integer;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.BERTags;
import org.bouncycastle.asn1.DERTaggedObject;

/**
 * @author Tobias Senger (tobias@t-senger.de)
 *
 */
public class AmDHPublicKey extends AmPublicKey implements DHPublicKey {

    private static final long serialVersionUID = 5691151250780854614L;

    private final String algorithm = "DH";
    private final String format = "CVC";

    private DERTaggedObject p = null;
    private DERTaggedObject g = null;
    private DERTaggedObject q = null;
    private DERTaggedObject y = null;

    /**
     * @param seq
     */
    public AmDHPublicKey(ASN1Sequence seq) {
        super(seq);
        decode(seq);
    }

    public AmDHPublicKey(String oidString, BigInteger p, BigInteger q, BigInteger g, BigInteger y) {
        super(oidString);
        this.p = new DERTaggedObject(false, 1, new ASN1Integer(p));
        this.q = new DERTaggedObject(false, 2, new ASN1Integer(q));
        this.g = new DERTaggedObject(false, 3, new ASN1Integer(g));
        this.y = new DERTaggedObject(false, 4, new ASN1Integer(y));
        vec.add(this.p);
        vec.add(this.q);
        vec.add(this.g);
        vec.add(this.y);
    }

    /**
     * Konstruktor fr Ephemeral Public Key (TR-03110 V2.05 D.3.4)
     * @param oidString OID
     * @param y public value
     */
    public AmDHPublicKey(String oidString, BigInteger y) {
        super(oidString);
        this.y = new DERTaggedObject(false, 4, new ASN1Integer(y));
        vec.add(this.y);
    }

    /* (non-Javadoc)
     * @see java.security.Key#getAlgorithm()
     */
    @Override
    public String getAlgorithm() {
        return algorithm;
    }

    /* (non-Javadoc)
     * @see java.security.Key#getFormat()
     */
    @Override
    public String getFormat() {
        return format;
    }

    /* (non-Javadoc)
     * @see java.security.Key#getEncoded()
     */
    @Override
    public byte[] getEncoded() {
        try {
            return super.getEncoded(ASN1Encoding.DER);
        } catch (IOException e) {
            return null;
        }
    }

    /* (non-Javadoc)
     * @see de.tsenger.animamea.asn1.AmPublicKey#decode(org.bouncycastle.asn1.DERSequence)
     */
    @Override
    protected void decode(ASN1Sequence seq) {
        for (int i = 1; i < seq.size(); i++) {
            DERTaggedObject to = (DERTaggedObject) seq.getObjectAt(i);
            switch (to.getTagNo()) {
            case 1:
                p = to;
                break;
            case 2:
                q = to;
                break;
            case 3:
                g = to;
                break;
            case 4:
                y = to;
                break;
            }
        }

    }

    /** Returns prime modulus p
     * @return
     */
    public BigInteger getP() {
        if (p == null)
            return null;
        ASN1Integer derInt = (ASN1Integer) p.getObjectParser(BERTags.INTEGER, false);
        return derInt.getPositiveValue();
    }

    /** Returns generator g
     * @return
     */
    public BigInteger getG() {
        if (g == null)
            return null;
        ASN1Integer derInt = (ASN1Integer) g.getObjectParser(BERTags.INTEGER, false);
        return derInt.getPositiveValue();
    }

    /** Returns oder of the subgroup q
     * @return
     */
    public BigInteger getQ() {
        if (q == null)
            return null;
        ASN1Integer derInt = (ASN1Integer) q.getObjectParser(BERTags.INTEGER, false);
        return derInt.getPositiveValue();
    }

    /* (non-Javadoc)
     * @see javax.crypto.interfaces.DHPublicKey#getY()
     */
    @Override
    public BigInteger getY() {
        if (y == null)
            return null;
        ASN1Integer derInt = (ASN1Integer) y.getObjectParser(BERTags.INTEGER, false);
        return derInt.getPositiveValue();
    }

    /* (non-Javadoc)
     * @see javax.crypto.interfaces.DHKey#getParams()
     */
    @Override
    public DHParameterSpec getParams() {
        DHParameterSpec dhSpec = new DHParameterSpec(getP(), getG());
        return dhSpec;
    }

}