| /* DSAParameterGenerator.java --- DSA Parameter Generator Implementation |
| Copyright (C) 1999 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath 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 2, or (at your option) |
| any later version. |
| |
| GNU Classpath 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 GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package gnu.java.security.provider; |
| |
| import java.math.BigInteger; |
| import java.security.AlgorithmParameters; |
| import java.security.AlgorithmParameterGeneratorSpi; |
| import java.security.InvalidAlgorithmParameterException; |
| import java.security.NoSuchAlgorithmException; |
| import java.security.SecureRandom; |
| import java.security.spec.AlgorithmParameterSpec; |
| import java.security.spec.DSAParameterSpec; |
| import java.security.spec.InvalidParameterSpecException; |
| import java.util.Random; |
| |
| import gnu.java.security.util.Prime; |
| |
| public class DSAParameterGenerator extends AlgorithmParameterGeneratorSpi |
| { |
| private int size; |
| private SecureRandom random = null; |
| |
| public DSAParameterGenerator() |
| { |
| size = 1024; |
| } |
| |
| public void engineInit(int size, SecureRandom random) |
| { |
| if( (size < 512) || (size > 1024) || ( (size % 64) != 0) ) |
| //throw new InvalidAlgorithmParameterException("Invalid Size"); |
| return; |
| this.size = size; |
| this.random = random; |
| } |
| |
| public void engineInit(AlgorithmParameterSpec genParamSpec, SecureRandom random) |
| throws InvalidAlgorithmParameterException |
| { |
| if( !( genParamSpec instanceof DSAParameterSpec ) ) |
| throw new InvalidAlgorithmParameterException("Must be DSAParameterSpec"); |
| |
| DSAParameterSpec dsaparameterspec = (DSAParameterSpec)genParamSpec; |
| int tmp = dsaparameterspec.getP().bitLength(); |
| |
| if( (tmp < 512) || (tmp > 1024) || ( (tmp % 64) != 0) ) |
| throw new InvalidAlgorithmParameterException("Invalid Size"); |
| |
| this.random = random; |
| } |
| |
| //For more information see IEEE P1363 A.16.1 (10/05/98 Draft) |
| public AlgorithmParameters engineGenerateParameters() |
| { |
| DSAParameterSpec dsaparameterspec; |
| |
| int L = size; |
| BigInteger r, p, k, h, g; |
| |
| //q 2^159 < q < 2^160 |
| r = Prime.generateRandomPrime( 159, 160, BigInteger.valueOf(1)); |
| |
| // 2^(L-1) < p < 2^L |
| p = Prime.generateRandomPrime( r, BigInteger.valueOf(1), L - 1, L, BigInteger.valueOf(1)); |
| |
| k = p.subtract( BigInteger.valueOf(1) ); |
| k = k.divide( r ); |
| |
| Random rand = new Random(); |
| h = BigInteger.valueOf(1); |
| |
| for(;;) { |
| h = h.add(BigInteger.valueOf( 1 ) ); |
| |
| g = h.modPow(k, p); |
| |
| if( g.compareTo( BigInteger.valueOf(1) ) != 1 ) |
| break; |
| } |
| |
| try { |
| dsaparameterspec = new DSAParameterSpec(p, r, g); |
| AlgorithmParameters ap = AlgorithmParameters.getInstance("DSA"); |
| ap.init( dsaparameterspec ); |
| return ap; |
| } catch ( NoSuchAlgorithmException nsae ) { |
| return null; |
| } catch ( InvalidParameterSpecException ipse) { |
| return null; |
| } |
| } |
| } |