Plugin available to require "access code" to show certain post categories?

Hi, I have a site that I hope to use to allow my clients to view pictures and videos of an event they used my company for. I had the idea in my head that I could give them an “access code” at the end of their event, so when they visited my site later that day/week, they could enter that code on a specific page, and depending on what code they entered, they would see a gallery page listing all the photos and videos from their event.

I suppose the easiest way to go about this in WP would be to make each event’s media (pics and vids) have their own specific post category, so when the code was entered, it returns a gallery of posts in that category and no others. The idea is that I would like clients to have some privacy with their pictures, rather than having an open gallery section with all the events’ pictures viewable to the public.

An alternative idea is to simply ask them to enter the date of the event (it is unlikely I would do more than one event on any given day) and the result would show all pics/vids from that date. Either one of these systems would work but I would prefer the additional privacy of the first method.

Does a plugin exist that is capable of achieving this? If not, how would I make this happen otherwise? I assume if there is no easy to use plugin for this, it will take significant php and server-side scripting to accomplish.

Thank you!

P.S. I realize the “password protected page” function exists, but the way I would like this to work is that the client goes to one page (i.e. mywebsite.com/member-area) and the content could be rendered dynamically on that page, or at least originate from that page (in the event I would need to place the specific content on inner pages, i.e. mywebsite.com/member-area/jane-doe-wedding). Therefore I don’t think the use of password protected page access is appropriate for my needs, but if I am incorrect about that, please explain how it could be used ??