165 lines
4.7 KiB
Java
165 lines
4.7 KiB
Java
/* 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);
|
|
}
|
|
}
|