Fedora Security :: Sshd With Both Certificate AND Password After Each Other?

I want to enable sshd from Internet, but I want to secure it as much as possible.Therefore, despite the fact that the service will run on a tcp port above 2000 to prevent most scans, I would like to :- First, force the use of a client certificate, to avoid brute force attack on my users/passwords- second force the use of a username/password to avoid someone having access to my system just by stealing my key..When I look at the configuration, it's possible to enable both, but one of them is sufficient to login, but I can't find how to make them both mandatory...