Secure display PDF in web page

I would like to share some "sensible" PDFs into a web application that I own. Logged users should only be able to browse that PDFs online, therefore they shouldn't be able to download the source PDF file and it should be as complicated as possible to reverse engine the viewer in order to obtain the file.

What would you do from scratch in a quick and dirty perspective?

Note: I know that this is not a good idea but I am required to do so and I need to do the best I can to protect the files.