Coercion-Resistant Electronic Elections

We introduce a model for electronic election schemes that involves a more powerful adversary than previous work. In particular, we allow the adversary to demand of coerced voters that they vote in a particular manner, abstain from voting, or even disclose their secret keys. We define a scheme to be

coercion-resistant

if it is infeasible for the adversary to determine whether a coerced voter complies with the demands.

A first contribution of this paper is to describe and characterize this newly strengthened adversary. In doing so, we additionally present what we believe to be the first formal security definitions for electronic elections of

any

type. A second contribution is a protocol that is provably secure against our formalized adversary. While strong attack model are of theoretical interest, we emphasize that our results lie close to practicality in two senses: We model real-life threats (such as vote-buying), and our proposed protocol combines a fair degree of efficiency with low structural complexity. While previous schemes have required an untappable channel, ours has the more practical requirement of an anonymous channel.