Breaching the privacy of Israel’s paper ballot voting system

Abstract

An election is a process through which citizens in liberal democracies select their governing bodies, usually through voting. For elections to be truly honest, people must be able to vote freely without being subject to coercion; that is why voting is usually done in a private manner. In this paper we analyze the security offered by a paper-ballot voting system that is used in Israel, as well as several other countries around the world. We provide an algorithm which, based on publicly-available information, breaks the privacy of the voters participating in such elections. Simulations based on real data collected in Israel show that our algorithm performs well, and can correctly recover the vote of up to 96% of the voters.