caching security

Hi, I want to enable caching on some sites that are behind my nginx reverse proxy such as owncloud and gitlab, both of these are log in based with separate users, but I dont want a situation the same as steam recently encountered where they were caching a particular users page for all other users and other people could see other peoples profiles, see the link: http://store.steampowered.com/news/19852/

So are there any special config options that I can include to make sure that this does not happen to my sites.

Thanks for any responses, Ben