Adding authentication to certain web pages

My site currently runs with a CMS I wrote myself. The data entry pages are protected by HTTP authentication. I'd like to move to a more sophisticated authentication system that will handle the creation and access for users, tie into two-factor authentication and decide who can do what to each data entry page. I'm looking for any pointers to established frameworks I can drop into the pages that need protecting, suggestions for tutorials, etc. Many, many thanks in advance.