static int check_bn(const char *name, const BIGNUM *bn, const char *hexbn)
{
    BIGNUM *tmp = NULL;
    int r;

    if (!TEST_true(BN_hex2bn(&tmp, hexbn)))
        return 0;

    if (BN_cmp(bn, tmp) != 0)
        TEST_error("unexpected %s value", name);
    r = TEST_BN_eq(bn, tmp);
    BN_free(tmp);
    return r;
}