1/*	$NetBSD: bn_mp_prime_is_prime.c,v 1.2 2017/01/28 21:31:47 christos Exp $	*/
2
3#include <tommath.h>
4#ifdef BN_MP_PRIME_IS_PRIME_C
5/* LibTomMath, multiple-precision integer library -- Tom St Denis
6 *
7 * LibTomMath is a library that provides multiple-precision
8 * integer arithmetic as well as number theoretic functionality.
9 *
10 * The library was designed directly after the MPI library by
11 * Michael Fromberger but has been written from scratch with
12 * additional optimizations in place.
13 *
14 * The library is free for all purposes without any express
15 * guarantee it works.
16 *
17 * Tom St Denis, tomstdenis@gmail.com, http://libtom.org
18 */
19
20/* performs a variable number of rounds of Miller-Rabin
21 *
22 * Probability of error after t rounds is no more than
23
24 *
25 * Sets result to 1 if probably prime, 0 otherwise
26 */
27int mp_prime_is_prime (mp_int * a, int t, int *result)
28{
29  mp_int  b;
30  int     ix, err, res;
31
32  /* default to no */
33  *result = MP_NO;
34
35  /* valid value of t? */
36  if (t <= 0 || t > PRIME_SIZE) {
37    return MP_VAL;
38  }
39
40  /* is the input equal to one of the primes in the table? */
41  for (ix = 0; ix < PRIME_SIZE; ix++) {
42      if (mp_cmp_d(a, ltm_prime_tab[ix]) == MP_EQ) {
43         *result = 1;
44         return MP_OKAY;
45      }
46  }
47
48  /* first perform trial division */
49  if ((err = mp_prime_is_divisible (a, &res)) != MP_OKAY) {
50    return err;
51  }
52
53  /* return if it was trivially divisible */
54  if (res == MP_YES) {
55    return MP_OKAY;
56  }
57
58  /* now perform the miller-rabin rounds */
59  if ((err = mp_init (&b)) != MP_OKAY) {
60    return err;
61  }
62
63  for (ix = 0; ix < t; ix++) {
64    /* set the prime */
65    mp_set (&b, ltm_prime_tab[ix]);
66
67    if ((err = mp_prime_miller_rabin (a, &b, &res)) != MP_OKAY) {
68      goto LBL_B;
69    }
70
71    if (res == MP_NO) {
72      goto LBL_B;
73    }
74  }
75
76  /* passed the test */
77  *result = MP_YES;
78LBL_B:mp_clear (&b);
79  return err;
80}
81#endif
82
83/* Source: /cvs/libtom/libtommath/bn_mp_prime_is_prime.c,v  */
84/* Revision: 1.4  */
85/* Date: 2006/12/28 01:25:13  */
86