Profile Privacy "who can see the file"

In our business company we have a little study .

We produce text files, movies, drawings for our clients.

We want use Dolphin to delivery these files for us customers.

We are concerned about privacy matters:

the files we create for someone, need to be personal and protected.

The problem we need to solve is that we do not want all users to be able to see each other's files.

In brief, we want user John's files only to be seen by user John and no one else.

We want the setting "who can see this file" to be only controlled by the administrator and there should be no chance the user could change it, not even accidentally.

We are looking for alternative solutions, if you could please advice us.

- is it possible to create these privacy settings with Dolphin's basic modules?

- if not, do we need some special extension or module?

- or, is it possible to get there by creating sub-domains; each sub-domain for only one client and their

collaborator?

- any other suggestion?

I use this site to transfer Real Estate files and I only set permissions for the people in the transaction to be able to the see whatever it is they are suppose to see.  I am testing the site and you sparked some good questions.  I never thought of the user having the ability to change the permissions which they cannot as I just tested but if a person wants to share the information of course it is very easy for them to do that inside or outside of Dolphin.  Once a document becomes digital it is kind if like a packet that is at the wisdom of the person who has it in their hands at that moment.  I see no way around this  as a discussion was recently had about screen capture and yada, yada from there.  All I know is that I assign who has the right to view something but beyond that is up to the person that I gave that right to.....