How to prevent code from leaking outside work? [duplicate]

Question

Possible Duplicate:
How to manage a Closed Source High-Risk Project?

I'm working on an institution that has a really strong sense of "possession" - each line of software we write should be only ours. Ironically, I'm the only programmer (ATM), but we're planning in hiring others.

Since my bosses wouldn't count the new programmers as people they can trust, they have an issue with the copies of the source code. We use Git, so they would have a entire copy of each of the projects they work on, when they clone the repository.

We can restrict access to them to a single key with Gitolite and bind that to their PC's, but they can copy those keys to another computer and they would have the repository access in another PC. Also (and the most obvious method) they could just upload the files somewhere else, add another remote, or just copy the files to an USB drive.

Is there any (perhaps clever) way to prevent events like these?

EDIT: I would like to thank everyone for their insights in this question, since it has been not only more eye opening, but also a firm support of my arguments (since you basically think like me, and I've been trying to make them understand that) against my bosses in the near future.

I am in a difficult situation work-wise, with my coworkers and bosses (since I'm basically in the middle) being like two gangs, so all this input is greatly, greatly appreciated.

It is true that I was looking for a technical solution to a people problem - both the management and the employees are the problem, so it can't be solved that way (I was thinking about some code obfuscation, perhaps working with separate modules, etc., but that wouldn't work from my developer POV). The main problem is the culture inside and outside the company - development is not taken seriously in my country (Venezuela) so naivity and paranoia are in fact a real issue in here.

The real answer here is an NDA (something that here in Venezuela doesn't completely work), because that's the people solution, because no sane developer would work in those conditions. Things will get ugly, but I think I will be able to handle that because of your help. Thank you all a lot! <3