C++ (Cpp) MP_ALLOC Examples

Example #1

/* Elliptic curve scalar-point multiplication. Computes R(x, y) = k * P(x,
 * y).  If x, y = NULL, then P is assumed to be the generator (base point)
 * of the group of points on the elliptic curve. Input and output values
 * are assumed to be NOT field-encoded. */
mp_err
ECPoint_mul(const ECGroup *group, const mp_int *k, const mp_int *px,
                        const mp_int *py, mp_int *rx, mp_int *ry)
{
        mp_err res = MP_OKAY;
        mp_int kt;

        ARGCHK((k != NULL) && (group != NULL), MP_BADARG);
        MP_DIGITS(&kt) = 0;

        /* want scalar to be less than or equal to group order */
        if (mp_cmp(k, &group->order) > 0) {
                MP_CHECKOK(mp_init(&kt, FLAG(k)));
                MP_CHECKOK(mp_mod(k, &group->order, &kt));
        } else {
                MP_SIGN(&kt) = MP_ZPOS;
                MP_USED(&kt) = MP_USED(k);
                MP_ALLOC(&kt) = MP_ALLOC(k);
                MP_DIGITS(&kt) = MP_DIGITS(k);
        }

        if ((px == NULL) || (py == NULL)) {
                if (group->base_point_mul) {
                        MP_CHECKOK(group->base_point_mul(&kt, rx, ry, group));
                } else {
                        MP_CHECKOK(group->
                                           point_mul(&kt, &group->genx, &group->geny, rx, ry,
                                                                 group));
                }
        } else {
                if (group->meth->field_enc) {
                        MP_CHECKOK(group->meth->field_enc(px, rx, group->meth));
                        MP_CHECKOK(group->meth->field_enc(py, ry, group->meth));
                        MP_CHECKOK(group->point_mul(&kt, rx, ry, rx, ry, group));
                } else {
                        MP_CHECKOK(group->point_mul(&kt, px, py, rx, ry, group));
                }
        }
        if (group->meth->field_dec) {
                MP_CHECKOK(group->meth->field_dec(rx, rx, group->meth));
                MP_CHECKOK(group->meth->field_dec(ry, ry, group->meth));
        }

  CLEANUP:
        if (MP_DIGITS(&kt) != MP_DIGITS(k)) {
                mp_clear(&kt);
        }
        return res;
}

Example #2

File: imtimer.c Project: admobitec/IP2Location-C-Library

void   mp_int_random(mp_int z, int prec)
{
  int i;

  if(prec > MP_ALLOC(z))
    prec = MP_ALLOC(z);

  for(i = 0; i < prec; ++i) {
    mp_digit d = 0;
    int j;
    
    for(j = 0; j < sizeof(d); ++j)
      d = (d << CHAR_BIT) | (rand() & UCHAR_MAX);
    
    z->digits[i] = d;
  }
  MP_USED(z) = prec;
}