3d256d3f4a
git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@17471 ec53bebd-3082-4978-b11e-865c3cabbd6b
111 lines
2.9 KiB
C
Executable File
111 lines
2.9 KiB
C
Executable File
/*
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Name: iprime.c
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Purpose: Pseudoprimality testing routines
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Author: M. J. Fromberger <http://www.dartmouth.edu/~sting/>
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Info: $Id$
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Copyright (C) 2002 Michael J. Fromberger, All Rights Reserved.
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Permission is hereby granted, free of charge, to any person
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obtaining a copy of this software and associated documentation files
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(the "Software"), to deal in the Software without restriction,
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including without limitation the rights to use, copy, modify, merge,
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publish, distribute, sublicense, and/or sell copies of the Software,
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and to permit persons to whom the Software is furnished to do so,
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subject to the following conditions:
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The above copyright notice and this permission notice shall be
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included in all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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#include "iprime.h"
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#include <stdlib.h>
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static int s_ptab_size = 32;
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static int s_ptab[] = {
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2, 3, 5, 7, 11, 13, 17, 19,
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23, 29, 31, 37, 41, 43, 47, 53,
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59, 61, 67, 71, 73, 79, 83, 89,
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97, 101, 103, 107, 109, 113, 127, 131
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};
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/* {{{ mp_int_is_prime(z) */
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/* Test whether z is likely to be prime:
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MP_TRUE means it is probably prime
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MP_FALSE means it is definitely composite
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*/
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mp_result mp_int_is_prime(mp_int z)
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{
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int i, rem;
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mp_result res;
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/* First check for divisibility by small primes; this eliminates a
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large number of composite candidates quickly
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*/
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for(i = 0; i < s_ptab_size; ++i) {
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if((res = mp_int_div_value(z, s_ptab[i], NULL, &rem)) != MP_OK)
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return res;
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if(rem == 0)
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return MP_FALSE;
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}
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/* Now try Fermat's test for several prime witnesses (since we now
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know from the above that z is not a multiple of any of them)
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*/
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{
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mpz_t tmp;
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if((res = mp_int_init(&tmp)) != MP_OK) return res;
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for(i = 0; i < 10 && i < s_ptab_size; ++i) {
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if((res = mp_int_exptmod_bvalue(s_ptab[i], z, z, &tmp)) != MP_OK)
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return res;
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if(mp_int_compare_value(&tmp, s_ptab[i]) != 0) {
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mp_int_clear(&tmp);
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return MP_FALSE;
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}
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}
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mp_int_clear(&tmp);
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}
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return MP_TRUE;
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}
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/* }}} */
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/* {{{ mp_int_find_prime(z) */
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/* Find the first apparent prime in ascending order from z */
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mp_result mp_int_find_prime(mp_int z)
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{
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mp_result res;
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if(mp_int_is_even(z) && ((res = mp_int_add_value(z, 1, z)) != MP_OK))
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return res;
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while((res = mp_int_is_prime(z)) == MP_FALSE) {
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if((res = mp_int_add_value(z, 2, z)) != MP_OK)
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break;
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}
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return res;
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}
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/* }}} */
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/* Here there be dragons */
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