int uECC_sign(const uint8_t *private_key,
              const uint8_t *message_hash,
              unsigned hash_size,
              uint8_t *signature,
              uECC_Curve curve) {
    uECC_word_t k[uECC_MAX_WORDS];
    uECC_word_t tries;

    for (tries = 0; tries < uECC_RNG_MAX_TRIES; ++tries) {
        if (!uECC_generate_random_int(k, curve->n, BITS_TO_WORDS(curve->num_n_bits))) {
            return 0;
        }

        if (uECC_sign_with_k(private_key, message_hash, hash_size, k, signature, curve)) {
            return 1;
        }
    }
    return 0;
}