[snakeboy]

However in this setup, anyone can bring a smartphone in and take a picture of the screen when it displays anything that separates your id from a fake one.

Sounds like you might be on the right track if you can get over that hurdle somehow.

[kybernetikos]

The smartphone problem exists currently with paper ballots. You're not supposed to be allowed to bring a camera into the voting booth, but this is not enforced particularly well.

One approach to this problem is to make it easy to cancel a previous ballot and submit a new one, so you can get your evidence that you voted the way e.g. your employer wanted you to, but then you can cancel it and vote with your conscience.

[feborges]

In the Brazilian voting machine this is often done. You type the numbers and it loads the candidate info in the screen. Once you click [Confirm] the screen gets blank with the message of success. Therefore the only way to take a picture is before the vote is actually processed. You have a [Reset] button to re-enter the numbers.

[rjmunro]

As far as I can remember from the instructions last time I voted, in Britain you can do this, just return the ballot to the person handing them out and say that you made a mistake, and they should issue you a replacement.