On Some Incompatible Properties of Voting Schemes

Abstract

Abstract. In this paper, we study the problem of simultaneously achieving several security properties, for voting schemes, without non-standard assumptions. More specifically, we focus on the universal verifiability of the computation of the tally, on the unconditional privacy/anonymity of the votes, and on the receipt-freeness properties, for the most classical election processes. Under usual assumptions and efficiency requirements, we show that a voting system that wants to publish the final list of the voters who actually voted, and to compute the number of times each candidate has been chosen, we cannot achieve:-universal verifiability of the tally (UV) and unconditional privacy of the votes (UP) simultaneously, unless all the registered voters actually vote;

Towards Automatic Analysis of Election Verifiability Properties

“…Universal verifiability was also studied by Chevallier-Mames et al [11] with the aim of showing an incompatibility result: protocols satisfying their definition are incompatible with vote-privacy (also called ballot secrecy), and hence coercion-resistance. To see this, note that they require functions f and f such that for any bulletin board BB and list of eligible voters L the function f (BB, L) returns the list of actual voters and f (BB, L) returns the election outcome (see Definition 1 of [11]).…”

“…To see this, note that they require functions f and f such that for any bulletin board BB and list of eligible voters L the function f (BB, L) returns the list of actual voters and f (BB, L) returns the election outcome (see Definition 1 of [11]). From these functions one could consider any single bulletin board entry b and compute f ({b}, L), f ({b}, L) to reveal a voter and her vote.…”

Anonymity and Verifiability in Voting: Understanding (Un)Linkability

“…the fact that only eligible voters cast a vote (cf. [1,7]). In [20] eligibility verifiability was addressed first as a separate voting requirement.…”

“…In [7], Chevallier et al prove that unconditional privacy and universal verifiability cannot be simultaneously achieved without additional assumptions (such as private channels). Most schemes in literature make such assumptions, and under these may be able to achieve both verifiability and anonymity.…”

“…Confusion is added because, in literature, there are opposing results. For example, [7] proves incompatibility of these notions, while other works such as [6,13], do combine notions of verifiability and anonymity.…”