If you're running secure site, you should use your certificate & signature. Even then NSA could well be capable of creating fake certificate, but it would be ex

If you're running secure site, you should use your certificate & signature. Even then NSA could well be capable of creating fake certificate, but it would be expensive. But that would stop others without huge computing capacity. Of course this requires that you're able to deliver your own CA information securely to your site users. Also end users should disable trust for any browser/OS build-in CAs.