I think you could accomplish this in a Document Library using permission levels...
For example, you can create a new Permission Level and only give it 'Add Items' and 'View Items' permissions for lists. This means that a user can add items to lists and view items in a list but not open the items. So he can basically see the items in the list but not their content (someone pls correct me if I am wrong here). Then you could assign this permission level to all users that can 'dump' their documents and give the supervisor higher permissions so he can edit the documents (probably contribute permissions is ok).
I'm not sure if this is the preferred approach but its just an idea and I have not tested this out, but I think permissions are the way to go. In my current site, I have Restricted Read permissions on certain department libraries for all users except those that belong to that department, that way everyone can see/open the files but only those from the department can upload and edit documents.
Here are some of the documents I've been reading for permissions:
http://www.sharepointblues.com/2010/09/01/sharepoint-security-and-permission-system-overview/ (this article helps A LOT with understanding how permisions work)
Anyway, I hope that helps!