dropbear/libtommath/bn_mp_prime_rabin_miller_trials.c
Steffen Jaeckel c71258625d Prime-related bugfixes (#81)
* Merge pull request #180 from czurnieden/isprimeerror

Fixed bug in mp_prime_isprime
(cherry picked from commit f3ff7064f3301a2fc11b84d389fd67769862d437)

* do 2 MR rounds for numbers >=2048bits

* back-port modified mp_prime_next_prime()
2019-09-17 22:11:09 +08:00

56 lines
1.5 KiB
C

#include "tommath_private.h"
#ifdef BN_MP_PRIME_RABIN_MILLER_TRIALS_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis
*
* LibTomMath is a library that provides multiple-precision
* integer arithmetic as well as number theoretic functionality.
*
* The library was designed directly after the MPI library by
* Michael Fromberger but has been written from scratch with
* additional optimizations in place.
*
* 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 } /* For bigger keysizes use always at least 2 Rounds */
};
/* 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;
}
#endif
/* ref: HEAD -> master, tag: v1.1.0 */
/* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
/* commit time: 2019-01-28 20:32:32 +0100 */