kc3-lang/libtommath/bn_mp_prime_is_prime.c

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• Hash : 4e3f1344
  Author :
  Date : 2015-11-12T01:49:07
  

  provide tommath_private.h tommath.h contains declarations for the public part of the library. tommath_private.h contains the functions which are private to ltm and should not be exposed to the public.

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• bn_mp_prime_is_prime.c

• #include <tommath_private.h>
  #ifdef BN_MP_PRIME_IS_PRIME_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.
   *
   * The library is free for all purposes without any express
   * guarantee it works.
   *
   * Tom St Denis, tstdenis82@gmail.com, http://libtom.org
   */
  
  /* performs a variable number of rounds of Miller-Rabin
   *
   * Probability of error after t rounds is no more than
  
   *
   * Sets result to 1 if probably prime, 0 otherwise
   */
  int mp_prime_is_prime (mp_int * a, int t, int *result)
  {
    mp_int  b;
    int     ix, err, res;
  
    /* default to no */
    *result = MP_NO;
  
    /* valid value of t? */
    if (t <= 0 || t > PRIME_SIZE) {
      return MP_VAL;
    }
  
    /* is the input equal to one of the primes in the table? */
    for (ix = 0; ix < PRIME_SIZE; ix++) {
        if (mp_cmp_d(a, ltm_prime_tab[ix]) == MP_EQ) {
           *result = 1;
           return MP_OKAY;
        }
    }
  
    /* first perform trial division */
    if ((err = mp_prime_is_divisible (a, &res)) != MP_OKAY) {
      return err;
    }
  
    /* return if it was trivially divisible */
    if (res == MP_YES) {
      return MP_OKAY;
    }
  
    /* now perform the miller-rabin rounds */
    if ((err = mp_init (&b)) != MP_OKAY) {
      return err;
    }
  
    for (ix = 0; ix < t; ix++) {
      /* set the prime */
      mp_set (&b, ltm_prime_tab[ix]);
  
      if ((err = mp_prime_miller_rabin (a, &b, &res)) != MP_OKAY) {
        goto LBL_B;
      }
  
      if (res == MP_NO) {
        goto LBL_B;
      }
    }
  
    /* passed the test */
    *result = MP_YES;
  LBL_B:mp_clear (&b);
    return err;
  }
  #endif
  
  /* $Source$ */
  /* $Revision$ */
  /* $Date$ */
  

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