Didier Stevens

Monday 11 June 2007

Some e-voting observations

Filed under: Vulnerabilities — Didier Stevens @ 16:52

Last Sunday, we had federal elections here in Belgium. I’m glad to see that the electronic voting system I used is designed to minimize voter coercion.

The secret ballot prevents coercion (being forced to vote for a certain person or party): if the voter can’t produce evidence of how he voted, he can lie to the coercer about his vote without risk. Some political parties want to change the process of the secret electronic ballot and include a paper trail. This is not a good idea, it will make coercion much more effective, as the voter will have an official paper with his vote.

The ubiquitousness of mobile phones equiped with a camera gives coercers a new opportunity to require proof from the persons they are coercing. The coercer just has to instruct his victim to take a picture of his ballot. The Belgian electronic ballot is designed to prevent this. When you’ve casted your vote, you’ll see a screen like this one:

The 2 buttons at the bottom of the screen allow you to:

  • left button: go back a screen and change your vote
  • right button: confirm your vote

Once you have confirmed your vote, the next screen doesn’t display how you voted. So if one is coerced and has to deliver proof, one just has to take a picture of the vote one was coerced into, and then back out from the screen and change ones vote. The only workaround I see is for the coercer to demand a video of the complete voting process, in stead of a picture of the ballot.

I’ve made a video of my voting last Sunday, and it turned out to be rather difficult to do. First of all, I was standing very close to the screen and I clumsily managed to film only the bottom of the screen. Secondly, the brightness of the CRT screen (black letters on a white background) makes it very hard to read my ballot on the video. This could also be an anti-coercion mechanism, taking legible pictures of a white screen is very hard.

This is an advantage that our electronic ballot has over our paper ballot, it is more effective against voter coercion.

You can find a simulation of the Belgian electronic ballot here:

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