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+/* 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., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 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 gnu.java.security.util.Prime;
+
+import java.math.BigInteger;
+import java.security.AlgorithmParameterGeneratorSpi;
+import java.security.AlgorithmParameters;
+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;
+
+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;
+ }
+ }
+}