Public record, but restricted file?

Hi - Is there a way to have item records publicly viewable, but then only Researchers would be able to download the associated file attached to the item?

I want my records (metadata) be be public, but only authorized people could actually download the attached document.

(I checked a few years ago, but was hoping maybe there has been a plugin or change that might allow this?)

This sounds like it quite similar to the work on an Embargo plugin discussed at this thread http://omeka.org/forums/topic/filter-files-in-items

So, doesn't quite exist yet, but others are working on things quite similar.