67b4e4ccd0
git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@23519 ec53bebd-3082-4978-b11e-865c3cabbd6b
120 lines
3.7 KiB
C
120 lines
3.7 KiB
C
/*
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Name: iprime.c
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Purpose: Pseudoprimality testing routines
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Author: M. J. Fromberger <http://spinning-yarns.org/michael/>
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Info: $Id: iprime.c 635 2008-01-08 18:19:40Z sting $
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Copyright (C) 2002-2008 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 = 168;
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static int s_ptab[] = {
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2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43,
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47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107,
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109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181,
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191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263,
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269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349,
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353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433,
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439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509, 521,
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523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601, 607, 613,
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617, 619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691, 701,
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709, 719, 727, 733, 739, 743, 751, 757, 761, 769, 773, 787, 797, 809,
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811, 821, 823, 827, 829, 839, 853, 857, 859, 863, 877, 881, 883, 887,
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907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977, 983, 991, 997
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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;
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mp_small 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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