Phonecams and the Secret Ballot

Secrecy of the ballot is one of the most important security requirements for elections. Voters must be able to keep their votes secret. But that is only half of the secret ballot requirement. The other half, which is sometimes overlooked, is that a voter should not be able to prove to a third party how he voted, even if the voter wants to do so.

Allowing voters to prove how they voted opens the door to vote-buying and coercion. It’s much harder to buy a vote if the buyer can’t be sure that he is really getting what he paid for; and it’s harder to strongarm someone into voting your way if you they can undetectably vote for their own candidate. For example, if you can prove how you voted, then the boss or the union chief can tell you not to bother showing up for work the next day without proof that you voted for a certain candidate.

Most voting systems are designed to prevent voters from proving how they voted. But new recording technology allows voters to record their votes on video, using cellphone cameras or similar small devices. Alex Halderman decided to demonstrate this by recording his own vote yesterday. Alex writes:

[Yesterday] I voted for John Kerry–and I can prove it, thanks to my Nokia 6230 camera phone:

http://www.cs.princeton.edu/~jhalderm/vote04.avi

You see, my phone can record short video clips as well as still photos. Inside the election booth, I shot a clip showing my choice of candidate, my face (so you know it’s me voting), and the final lever pull that locked in the vote (so you know I didn’t change it after turning off the camera).

[I posted this at Alex’s request.]