gencbd_vector_ntt
if (!gencbd_vector_ntt(y, cbd_1, &counter, r, rank, mdctx, key))
|| !gencbd_vector_ntt(key->s, cbd_1, &counter, sigma, rank, mdctx, key)
|| !gencbd_vector_ntt(key->t, cbd_1, &counter, sigma, rank, mdctx, key))