I'm not convinced that any method will ever be 100% foolproof, but I think it can be improved immensely, and if we could limit the inaccuracies/fraud to always be less than those incurred by a traditional paper ballot[1], I think I'd approve.
In regards to your comment regarding untrusted parties handling the hardware, here are a few counterpoints:
- We already trust polling place workers with paper ballots, the possibility for fraud already exists.
- The potential for fraud from any one polling place can be limited by implementing a system which makes it impossible (or very very difficult) to spoof the location from which a vote was cast, and ensuring that the number of votes cast per polling place is within an expected range.
- Such a system could also include a paper receipt with an ID number on it. A voter could plug this "tracking number" in on a trusted website (ie. vote.gov) and confirm that their name is associated with their preferred candidates, but not allow them to change these choices. This would go a long way towards identifying fraudulent activity when/if it occurs.
[1] Though figuring out how to quantify this is anybody's guess.