Protecting WordPress Media Library

Our teacher candidates in education need to create a WP site portfolio which needs to include confidential pdf uploads (evaluation forms, etc). Any ideas how I can prevent direct access to those media files vial URL?

We are running a WP multi-site on Reclaim Cloud.

Thanks,
Colin

Level of prevention becomes important to clarify. A lot of the options obscure the url rather than preventing access to it. I think something like this will do it. If you’ve got more specific needs, let me know.

I was just in message conversation with Ken Bauer who offered this approach of an edit of .htaccess

Ken thinks this is something Reclaim might want to build into their WP installs (if possible)