static int srp_Verify_N_and_g(const BIGNUM *N, const BIGNUM *g)
{
    BN_CTX *bn_ctx = BN_CTX_new();
    BIGNUM *p = BN_new();
    BIGNUM *r = BN_new();
    int ret =
        g != NULL && N != NULL && bn_ctx != NULL && BN_is_odd(N) &&
        BN_is_prime_ex(N, SRP_NUMBER_ITERATIONS_FOR_PRIME, bn_ctx, NULL) == 1 &&
        p != NULL && BN_rshift1(p, N) &&
        /* p = (N-1)/2 */
        BN_is_prime_ex(p, SRP_NUMBER_ITERATIONS_FOR_PRIME, bn_ctx, NULL) == 1 &&
        r != NULL &&
        /* verify g^((N-1)/2) == -1 (mod N) */
        BN_mod_exp(r, g, p, N, bn_ctx) &&
        BN_add_word(r, 1) && BN_cmp(r, N) == 0;

    BN_free(r);
    BN_free(p);
    BN_CTX_free(bn_ctx);
    return ret;
}