Access control for uploaded files based on custom field

In a current project, users will be creating media content that is uploaded to their profile. Through their profile page, they might chose to share some or all content on Facebook. However, we have to adhere to strict privacy laws, so the user has to mark a specific file as shared before it should be publicly available.

Is there some way to connect a SafeCracker File fieldtype to some kind of access control/middle man, so the public URL is a authentication mechanism of some sort - Which in turn checks a custom field?

Moved to Development and Programming by Moderator