view libtommath/bn_mp_prime_is_prime.c @ 1629:258b57b208ae

Fix for issue successfull login of disabled user (#78) This commit introduces fix for scenario: 1. Root login disabled on dropbear 2. PAM authentication model enabled While login as root user, after prompt for password user is being notified about login failrue, but after second attempt of prompt for password within same session, login becames succesfull. Signed-off-by: Pawel Rapkiewicz <[email protected]>
author vincentto13 <33652988+vincentto13@users.noreply.github.com>
date Wed, 20 Mar 2019 15:03:40 +0100
parents 8bba51a55704
children f52919ffd3b1
line wrap: on
line source

#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, [email protected], 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

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