C++ (Cpp) constant_time_eq_size_t Exemples

Exemple #1

Fichier : gfp_p256.c Projet : ctz/ring

void GFp_nistz256_select_w7(P256_POINT_AFFINE *out,
                            const P256_POINT_AFFINE table[64], int index) {
  assert(index >= 0);
  size_t index_as_size_t = (size_t)index; /* XXX: constant time? */

  alignas(32) Elem x; memset(x, 0, sizeof(x));
  alignas(32) Elem y; memset(y, 0, sizeof(y));

  for (size_t i = 0; i < 64; ++i) {
    Limb mask = constant_time_eq_size_t(index_as_size_t, i + 1);
    for (size_t j = 0; j < P256_LIMBS; ++j) {
      x[j] |= table[i].X[j] & mask;
      y[j] |= table[i].Y[j] & mask;
    }
  }

  memcpy(out->X, x, sizeof(x));
  memcpy(out->Y, y, sizeof(y));
}

Exemple #2

Fichier : gfp_p256.c Projet : thejpster/ring

void ecp_nistz256_select_w5(P256_POINT *out, const P256_POINT table[16],
                            int index) {
  assert(index >= 0);
  size_t index_as_size_t = (size_t)index; /* XXX: constant time? */

  alignas(32) Elem x; memset(x, 0, sizeof(x));
  alignas(32) Elem y; memset(y, 0, sizeof(y));
  alignas(32) Elem z; memset(z, 0, sizeof(z));

  for (size_t i = 0; i < 16; ++i) {
    GFp_Limb mask = constant_time_eq_size_t(index_as_size_t, i + 1);
    for (size_t j = 0; j < P256_LIMBS; ++j) {
      x[j] |= table[i].X[j] & mask;
      y[j] |= table[i].Y[j] & mask;
      z[j] |= table[i].Z[j] & mask;
    }
  }

  memcpy(&out->X, x, sizeof(x));
  memcpy(&out->Y, y, sizeof(y));
  memcpy(&out->Z, z, sizeof(z));
}