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Diffstat (limited to 'libjava/classpath/gnu/java/security/provider/DSAParameterGenerator.java')
-rw-r--r-- | libjava/classpath/gnu/java/security/provider/DSAParameterGenerator.java | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/libjava/classpath/gnu/java/security/provider/DSAParameterGenerator.java b/libjava/classpath/gnu/java/security/provider/DSAParameterGenerator.java new file mode 100644 index 00000000000..ccec1136cd3 --- /dev/null +++ b/libjava/classpath/gnu/java/security/provider/DSAParameterGenerator.java @@ -0,0 +1,128 @@ +/* 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; + } + } +} |