tommath/bn_mp_prime_rabin_miller_trials.c

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#include "tommath_private.h"
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#ifdef BN_MP_PRIME_RABIN_MILLER_TRIALS_C
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/* 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.
*
* The library is free for all purposes without any express
* guarantee it works.
*/
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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 },
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{ 256, 16 },
{ 384, 10 },
{ 512, 7 },
{ 640, 6 },
{ 768, 5 },
{ 896, 4 },
{ 1024, 4 },
{ 2048, 2 },
{ 4096, 1 },
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};
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/* returns # of RM trials required for a given bit size and max. error of 2^(-96)*/
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int mp_prime_rabin_miller_trials(int size)
{
int x;
for (x = 0; x < (int)(sizeof(sizes)/(sizeof(sizes[0]))); x++) {
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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;
}
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}
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return sizes[x-1].t + 1;
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}
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#endif
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/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */