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Diffstat (limited to 'libjava/gnu/java/security/util/Prime.java')
| -rw-r--r-- | libjava/gnu/java/security/util/Prime.java | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/libjava/gnu/java/security/util/Prime.java b/libjava/gnu/java/security/util/Prime.java new file mode 100644 index 00000000000..06d059e1eeb --- /dev/null +++ b/libjava/gnu/java/security/util/Prime.java @@ -0,0 +1,164 @@ +/* Prime.java --- Prime number generation utilities + 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.util; +import java.math.BigInteger; +import java.util.Random; +//import java.security.SecureRandom; + +public final class Prime +{ + + /* + See IEEE P1363 A.15.4 (10/05/98 Draft) + */ + public static BigInteger generateRandomPrime( int pmin, int pmax, BigInteger f ) + { + BigInteger d; + + //Step 1 - generate prime + BigInteger p = new BigInteger( (pmax + pmin)/2, new Random() ); + if( p.compareTo( BigInteger.valueOf( 1 ).shiftLeft( pmin ) ) <= 0 ) + { + p.add( BigInteger.valueOf( 1 ).shiftLeft( pmin ).subtract( p ) ); + } + + //Step 2 - test for even + if( p.mod( BigInteger.valueOf(2) ).compareTo( BigInteger.valueOf( 0 )) == 0) + p.add( BigInteger.valueOf( 1 ) ); + + for(;;) + { + //Step 3 + if( p.compareTo( BigInteger.valueOf( 1 ).shiftLeft( pmax)) > 0) + { + //Step 3.1 + p = p.subtract( BigInteger.valueOf( 1 ).shiftLeft( pmax) ); + p = p.add( BigInteger.valueOf( 1 ).shiftLeft( pmin) ); + p = p.subtract( BigInteger.valueOf( 1 ) ); + + //Step 3.2 + // put step 2 code here so looping code is cleaner + //Step 2 - test for even + if( p.mod( BigInteger.valueOf(2) ).compareTo( BigInteger.valueOf( 0 )) == 0) + p.add( BigInteger.valueOf( 1 ) ); + continue; + } + + //Step 4 - compute GCD + d = p.subtract( BigInteger.valueOf(1) ); + d = d.gcd( f ); + + //Step 5 - test d + if( d.compareTo( BigInteger.valueOf( 1 ) ) == 0) + { + //Step 5.1 - test primality + if( p.isProbablePrime( 1 ) == true ) + { + //Step 5.2; + return p; + } + } + //Step 6 + p = p.add( BigInteger.valueOf( 2 ) ); + + //Step 7 + } + } + + + /* + See IEEE P1363 A.15.5 (10/05/98 Draft) + */ + public static BigInteger generateRandomPrime( BigInteger r, BigInteger a, int pmin, int pmax, BigInteger f ) + { + BigInteger d, w; + + //Step 1 - generate prime + BigInteger p = new BigInteger( (pmax + pmin)/2, new Random() ); + + steptwo:{ //Step 2 + w = p.mod( r.multiply( BigInteger.valueOf(2) )); + + //Step 3 + p = p.add( r.multiply( BigInteger.valueOf(2) ) ); + p = p.subtract( w ); + p = p.add(a); + + //Step 4 - test for even + if( p.mod( BigInteger.valueOf(2) ).compareTo( BigInteger.valueOf( 0 )) == 0) + p.add( r ); + + for(;;) + { + //Step 5 + if( p.compareTo( BigInteger.valueOf( 1 ).shiftLeft( pmax)) > 0) + { + //Step 5.1 + p = p.subtract( BigInteger.valueOf( 1 ).shiftLeft( pmax) ); + p = p.add( BigInteger.valueOf( 1 ).shiftLeft( pmin) ); + p = p.subtract( BigInteger.valueOf( 1 ) ); + + //Step 5.2 - goto to Step 2 + break steptwo; + } + + //Step 6 + d = p.subtract( BigInteger.valueOf(1) ); + d = d.gcd( f ); + + //Step 7 - test d + if( d.compareTo( BigInteger.valueOf( 1 ) ) == 0) + { + //Step 7.1 - test primality + if( p.isProbablePrime( 1 ) == true ) + { + //Step 7.2; + return p; + } + } + //Step 8 + p = p.add( r.multiply( BigInteger.valueOf(2) ) ); + + //Step 9 + } + } + //Should never reach here but makes the compiler happy + return BigInteger.valueOf(0); + } +} |