Java Key Public getPublicKey(String algo)

Description

get Public Key

License

Apache License

Declaration

public static PublicKey getPublicKey(String algo) throws InvalidKeySpecException, NoSuchAlgorithmException 

Method Source Code

//package com.java2s;
/**//from  ww w .  j ava 2s .  c  om
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import java.math.BigInteger;
import java.security.KeyFactory;

import java.security.NoSuchAlgorithmException;

import java.security.PublicKey;

import java.security.spec.DSAPublicKeySpec;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;

import java.security.spec.RSAPublicKeySpec;

public class Main {
    private static final String DSA_Y = "07066284216756577193658833512863439617178933165631848358445549382240081120085333137303066923542492834619027404463194956043802393462371310375123430985057160";
    private static final String DSA_P = "013232376895198612407547930718267435757728527029623408872245156039757713029036368719146452186041204237350521785240337048752071462798273003935646236777459223";
    private static final String DSA_Q = "0857393771208094202104259627990318636601332086981";
    private static final String DSA_G = "05421644057436475141609648488325705128047428394380474376834667300766108262613900542681289080713724597310673074119355136085795982097390670890367185141189796";
    private static final String DSA_2048_Y = "15119007057343785981993995134621348945077524760182795513668325877793414638620983617627033248732235626178802906346261435991040697338468329634416089753032362617771631199351767336660070462291411472735835843440140283101463231807789628656218830720378705090795271104661936237385140354825159080766174663596286149653433914842868551355716015585570827642835307073681358328172009941968323702291677280809277843998510864653406122348712345584706761165794179850728091522094227603562280855104749858249588234915206290448353957550635709520273178475097150818955098638774564910092913714625772708285992586894795017709678223469405896699928";
    private static final String DSA_2048_P = "18111848663142005571178770624881214696591339256823507023544605891411707081617152319519180201250440615163700426054396403795303435564101919053459832890139496933938670005799610981765220283775567361483662648340339405220348871308593627647076689407931875483406244310337925809427432681864623551598136302441690546585427193224254314088256212718983105131138772434658820375111735710449331518776858786793875865418124429269409118756812841019074631004956409706877081612616347900606555802111224022921017725537417047242635829949739109274666495826205002104010355456981211025738812433088757102520562459649777989718122219159982614304359";
    private static final String DSA_2048_Q = "19689526866605154788513693571065914024068069442724893395618704484701";
    private static final String DSA_2048_G = "2859278237642201956931085611015389087970918161297522023542900348087718063098423976428252369340967506010054236052095950169272612831491902295835660747775572934757474194739347115870723217560530672532404847508798651915566434553729839971841903983916294692452760249019857108409189016993380919900231322610083060784269299257074905043636029708121288037909739559605347853174853410208334242027740275688698461842637641566056165699733710043802697192696426360843173620679214131951400148855611740858610821913573088059404459364892373027492936037789337011875710759208498486908611261954026964574111219599568903257472567764789616958430";
    private static final String RSA_MOD = "010800185049102889923150759252557522305032794699952150943573164381936603255999071981574575044810461362008102247767482738822150129277490998033971789476107463";
    private static final String RSA_PUB = "065537";

    public static PublicKey getPublicKey(String algo) throws InvalidKeySpecException, NoSuchAlgorithmException {
        if (algo.equalsIgnoreCase("DSA")) {
            return getPublicKey("DSA", 1024);
        } else if (algo.equalsIgnoreCase("RSA")) {
            return getPublicKey("RSA", 512);
        } else {
            throw new RuntimeException("Unsupported key algorithm " + algo);
        }
    }

    public static PublicKey getPublicKey(String algo, int keysize)
            throws InvalidKeySpecException, NoSuchAlgorithmException {
        KeyFactory kf = KeyFactory.getInstance(algo);
        KeySpec kspec;
        if (algo.equalsIgnoreCase("DSA")) {
            if (keysize == 1024) {
                kspec = new DSAPublicKeySpec(new BigInteger(DSA_Y), new BigInteger(DSA_P), new BigInteger(DSA_Q),
                        new BigInteger(DSA_G));
            } else if (keysize == 2048) {
                kspec = new DSAPublicKeySpec(new BigInteger(DSA_2048_Y), new BigInteger(DSA_2048_P),
                        new BigInteger(DSA_2048_Q), new BigInteger(DSA_2048_G));
            } else {
                throw new RuntimeException("Unsupported keysize:" + keysize);
            }
        } else if (algo.equalsIgnoreCase("RSA")) {
            if (keysize == 512) {
                kspec = new RSAPublicKeySpec(new BigInteger(RSA_MOD), new BigInteger(RSA_PUB));
            } else {
                throw new RuntimeException("Unsupported keysize:" + keysize);
            }
        } else {
            throw new RuntimeException("Unsupported key algorithm " + algo);
        }
        return kf.generatePublic(kspec);
    }
}

Related

1. getPublicKey(KeyPair kp)
2. getPublicKey(KeyStore keyStore, String alias)
3. getPublicKey(KeyStore keyStore, String alias)
4. getPublicKey(KeyStore keyStore, String alias, char[] password)
5. getPublicKey(KeyStore ks, String alias, char[] password)
6. getPublicKey(String alias)
7. getPublicKey(String certificatePath)
8. getPublicKey(String certPath)
9. getPublicKey(String filename)