Code Voting: when Simplicity Meets Security

The Swiss Chancellery has developed highly demanding requirements in terms of security for electronic voting. A few protocols have been proposed that meet the requirements. We propose a very simple protocol that satisfies the Swiss requirements while achieving an additional property: secrecy against a dishonest voting device, thanks to code voting. One key feature of our protocol is to use very short codes (typically one or two digits), so that it can be easily used by voters. Moreover, it only relies on standard primitives. Using the tool ProVerif, we formally prove vote privacy and end-to-end verifiability under the trust model of the Swiss Chancellery, assuming a dishonest voting device.