libtommath/bn_mp_prime_rabin_miller_trials.c
2019-04-07 17:26:31 +02:00

43 lines
1016 B
C

#include "tommath_private.h"
#ifdef BN_MP_PRIME_RABIN_MILLER_TRIALS_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */
static const struct {
int k, t;
} sizes[] = {
{ 80, -1 }, /* Use deterministic algorithm for size <= 80 bits */
{ 81, 39 },
{ 96, 37 },
{ 128, 32 },
{ 160, 27 },
{ 192, 21 },
{ 256, 16 },
{ 384, 10 },
{ 512, 7 },
{ 640, 6 },
{ 768, 5 },
{ 896, 4 },
{ 1024, 4 },
{ 2048, 2 },
{ 4096, 1 },
};
/* returns # of RM trials required for a given bit size and max. error of 2^(-96)*/
int mp_prime_rabin_miller_trials(int size)
{
int x;
for (x = 0; x < (int)(sizeof(sizes)/(sizeof(sizes[0]))); x++) {
if (sizes[x].k == size) {
return sizes[x].t;
} else if (sizes[x].k > size) {
return (x == 0) ? sizes[0].t : sizes[x - 1].t;
}
}
return sizes[x-1].t + 1;
}
#endif