Election verifiability in electronic voting protocols (Preliminary version)

We present a symbolic definition of election verifiability for electronic voting protocols. Our definition is given in terms of reachability assertions in the applied pi calculus and is amenable to automated reasoning using the tool ProVerif. The definition distinguishes three aspects of verifiability, which we call individual, universal, and eligibility verifiability. It also allows us to determine precisely what aspects of the system are required to be trusted. We demonstrate our formalism by analysing the protocols due to Fujioka, Okamoto & Ohta and Juels, Catalano & Jakobsson; the latter of which has been implemented by Clarkson, Chong & Myers.