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kc3-lang/libtommath/bn_mp_prime_rabin_miller_trials.c

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  • Author : Steffen Jaeckel
    Date : 2018-12-29 17:56:20
    Hash : 18355de6
    Message : Update file headers [skip ci]

  • bn_mp_prime_rabin_miller_trials.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 },
       {  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
    
    /* ref:         $Format:%D$ */
    /* git commit:  $Format:%H$ */
    /* commit time: $Format:%ai$ */