Coercion Resistant End-to-end Voting

Abstract

Abstract. End-to-end voting schemes have shown considerable promise for allowing voters to verify that tallies are accurate. At the same time, the threat of coercion has generally been considered only when voting devices are honest, and in many schemes, voters can be forced or incentivized to cast votes of an adversary's choice. In this paper, we examine the issue of voter coercion and identify one example method for coercing voters in a scheme by Benaloh. To address such attacks, we present a formal definition of coercion resistance for end-to-end voting. We then present a new scheme, extended from Benaloh's, that is provably coercion resistant. In addition to providing accuracy and coercion resistance, our scheme emphasizes ease-of-use for the voter.

A game-based definition of coercion resistance and its applications1

“…A recent definition of coercion-resistance by Gardner et al [11] is specifically tailored to the protocol considered by the authors. It also considers only a very restricted part of an election process, denying, for example, the coercer access to information in the tallying phase.…”

“…Intuitively, a voting protocol is coercion-resistant if it prevents vote buying and voter coercion. Several definitions of coercion-resistance have been proposed in the literature (see, e.g., [15,18,7,23,11,14,10,1,17]), both based on cryptographic and symbolic models, where symbolic models take an idealized view on cryptography. However, in the cryptographic setting, only very few voting protocols have been analyzed rigorously w.r.t.…”

Practical Internet voting system

“…Polling station voting systems, such as Adida (2006), Araú jo et al (2010b), Benaloh (2006Benaloh ( , 2007, Chaum (2004, Chaum et al (2008aChaum et al ( ,b, 2005, Gardner et al (2009), Moran and Naor (2006, 2007, Neff (2004), Riva and Shma (2007), Rivest and Smith (2007), and Teague et al (2008), build their security on an untappable channel implemented as a private voting booth at a polling place, where a voter can cast her ballot in private. Thus, risk of voter coercion and vote buying can be greatly mitigated.…”

“…Although almost all voting systems achieve privacy on the basis of the assumption that only a minority of tallying authorities may corrupt, we believe that voter verification and universal verification should only build on hard mathematical assumptions instead of any social assumptions. The corruption of all tallying authorities in a voting system may reveal privacy, but must not compromise verifiability (i.e., the election result can be still trusted), like Gardner et al (2009).…”

Distributed ElGamal à la Pedersen

“…Several privacy definitions for voting schemes have been proposed, from ballot privacy [30,34,7,8,9,11] to coercion-resistance [31,23,33] and applied to voting schemes: Civitas has been shown to be coercionresistant [14], while Helios has been shown to ensure ballot and vote privacy [15,7,9,8].…”