etc/mont.c

   1 /* tests the montgomery routines */
   2 #include <tommath.h>
   3 #include <stdlib.h>
   4 #include <time.h>
   5
   6 int main(void)
   7 {
   8    mp_int modulus, R, p, pp;
   9    mp_digit mp;
  10    mp_err err;
  11    int x, y;
  12
  13    srand(time(NULL));
  14    if ((err = mp_init_multi(&modulus, &R, &p, &pp, NULL)) != MP_OKAY)                                      goto LTM_ERR;
  15
  16    /* loop through various sizes */
  17    for (x = 4; x < 256; x++) {
  18       printf("DIGITS == %3d...", x);
  19       fflush(stdout);
  20
  21       /* make up the odd modulus */
  22       if ((err = mp_rand(&modulus, x)) != MP_OKAY)                                                         goto LTM_ERR;
  23       modulus.dp[0] |= 1uL;
  24
  25       /* now find the R value */
  26       if ((err = mp_montgomery_calc_normalization(&R, &modulus)) != MP_OKAY)                               goto LTM_ERR;
  27       if ((err = mp_montgomery_setup(&modulus, &mp)) != MP_OKAY)                                           goto LTM_ERR;
  28
  29       /* now run through a bunch tests */
  30       for (y = 0; y < 1000; y++) {
  31          /* p = random */
  32          if ((err = mp_rand(&p, x/2)) != MP_OKAY)                                                          goto LTM_ERR;
  33          /* pp = R * p */
  34          if ((err = mp_mul(&p, &R, &pp)) != MP_OKAY)                                                       goto LTM_ERR;
  35          if ((err = mp_montgomery_reduce(&pp, &modulus, mp)) != MP_OKAY)                                   goto LTM_ERR;
  36
  37          /* should be equal to p */
  38          if (mp_cmp(&pp, &p) != MP_EQ) {
  39             printf("FAILURE!\n");
  40             exit(-1);
  41          }
  42       }
  43       printf("PASSED\n");
  44    }
  45
  46 LTM_ERR:
  47    return 0;
  48 }