protecting products? is there a way?

Is there a way of making viewers register or login to view products for sale instead of just prices?
I would like a generic front page with log in the n show all product once viewers have registered or logged in if they are already registered.
I apologise if this is a stupid question but I am blind and struggle with the backend of opencart.

Not easy to understand what you really want.

As far as I understand, you want to display NO products and NO prices.
Instead something like a landing page and products and prices shall be visible AFTER your visitors have been logged in or registered?
Or display products only and NO prices - that would be a catalog mode (see extensions).