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1: /* DSAParameterGenerator.java --- DSA Parameter Generator Implementation 2: Copyright (C) 1999 Free Software Foundation, Inc. 3: 4: This file is part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2, or (at your option) 9: any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 USA. 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: 39: package gnu.java.security.provider; 40: 41: import gnu.java.security.util.Prime; 42: 43: import java.math.BigInteger; 44: import java.security.AlgorithmParameterGeneratorSpi; 45: import java.security.AlgorithmParameters; 46: import java.security.InvalidAlgorithmParameterException; 47: import java.security.NoSuchAlgorithmException; 48: import java.security.SecureRandom; 49: import java.security.spec.AlgorithmParameterSpec; 50: import java.security.spec.DSAParameterSpec; 51: import java.security.spec.InvalidParameterSpecException; 52: import java.util.Random; 53: 54: public class DSAParameterGenerator extends AlgorithmParameterGeneratorSpi 55: { 56: private int size; 57: private SecureRandom random = null; 58: 59: public DSAParameterGenerator() 60: { 61: size = 1024; 62: } 63: 64: public void engineInit(int size, SecureRandom random) 65: { 66: if( (size < 512) || (size > 1024) || ( (size % 64) != 0) ) 67: //throw new InvalidAlgorithmParameterException("Invalid Size"); 68: return; 69: this.size = size; 70: this.random = random; 71: } 72: 73: public void engineInit(AlgorithmParameterSpec genParamSpec, SecureRandom random) 74: throws InvalidAlgorithmParameterException 75: { 76: if( !( genParamSpec instanceof DSAParameterSpec ) ) 77: throw new InvalidAlgorithmParameterException("Must be DSAParameterSpec"); 78: 79: DSAParameterSpec dsaparameterspec = (DSAParameterSpec)genParamSpec; 80: int tmp = dsaparameterspec.getP().bitLength(); 81: 82: if( (tmp < 512) || (tmp > 1024) || ( (tmp % 64) != 0) ) 83: throw new InvalidAlgorithmParameterException("Invalid Size"); 84: 85: this.random = random; 86: } 87: 88: //For more information see IEEE P1363 A.16.1 (10/05/98 Draft) 89: public AlgorithmParameters engineGenerateParameters() 90: { 91: DSAParameterSpec dsaparameterspec; 92: 93: int L = size; 94: BigInteger r, p, k, h, g; 95: 96: //q 2^159 < q < 2^160 97: r = Prime.generateRandomPrime( 159, 160, BigInteger.valueOf(1)); 98: 99: // 2^(L-1) < p < 2^L 100: p = Prime.generateRandomPrime( r, BigInteger.valueOf(1), L - 1, L, BigInteger.valueOf(1)); 101: 102: k = p.subtract( BigInteger.valueOf(1) ); 103: k = k.divide( r ); 104: 105: Random rand = new Random(); 106: h = BigInteger.valueOf(1); 107: 108: for(;;) { 109: h = h.add(BigInteger.valueOf( 1 ) ); 110: 111: g = h.modPow(k, p); 112: 113: if( g.compareTo( BigInteger.valueOf(1) ) != 1 ) 114: break; 115: } 116: 117: try { 118: dsaparameterspec = new DSAParameterSpec(p, r, g); 119: AlgorithmParameters ap = AlgorithmParameters.getInstance("DSA"); 120: ap.init( dsaparameterspec ); 121: return ap; 122: } catch ( NoSuchAlgorithmException nsae ) { 123: return null; 124: } catch ( InvalidParameterSpecException ipse) { 125: return null; 126: } 127: } 128: }