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kc3-lang/libtommath/bn_mp_prime_rabin_miller_trials.c

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  • 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 */
    /* SPDX-License-Identifier: Unlicense */
    
    static const struct {
       int k, t;
    } sizes[] = {
       {    80, -1 }, /* Use deterministic algorithm for size <= 80 bits */
       {    81, 37 }, /* max. error = 2^(-96)*/
       {    96, 32 }, /* max. error = 2^(-96)*/
       {   128, 40 }, /* max. error = 2^(-112)*/
       {   160, 35 }, /* max. error = 2^(-112)*/
       {   256, 27 }, /* max. error = 2^(-128)*/
       {   384, 16 }, /* max. error = 2^(-128)*/
       {   512, 18 }, /* max. error = 2^(-160)*/
       {   768, 11 }, /* max. error = 2^(-160)*/
       {   896, 10 }, /* max. error = 2^(-160)*/
       {  1024, 12 }, /* max. error = 2^(-192)*/
       {  1536, 8  }, /* max. error = 2^(-192)*/
       {  2048, 6  }, /* max. error = 2^(-192)*/
       {  3072, 4  }, /* max. error = 2^(-192)*/
       {  4096, 5  }, /* max. error = 2^(-256)*/
       {  5120, 4  }, /* max. error = 2^(-256)*/
       {  6144, 4  }, /* max. error = 2^(-256)*/
       {  8192, 3  }, /* max. error = 2^(-256)*/
       {  9216, 3  }, /* max. error = 2^(-256)*/
       { 10240, 2  }  /* For bigger keysizes use always at least 2 Rounds */
    };
    
    /* returns # of RM trials required for a given bit size */
    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