OpenSSL::X509::Certificate#not_before

static VALUE
ossl_x509_get_not_before(VALUE self)
{
    X509 *x509;
    const ASN1_TIME *asn1time;

    GetX509(self, x509);
    if (!(asn1time = X509_get0_notBefore(x509))) {
        ossl_raise(eX509CertError, NULL);
    }

    return asn1time_to_time(asn1time);
}