Bingo Voting: Secure and Coercion-Free Voting Using a Trusted Random Number Generator

Abstract

Abstract. It is debatable if current direct-recording electronic voting machines can sufficiently be trusted for a use in elections. Reports about malfunctions and possible ways of manipulation abound. Voting schemes have to fulfill seemingly contradictory requirements: On one hand the election process should be verifiable to prevent electoral fraud and on the other hand each vote should be deniable to avoid coercion and vote buying. This work presents a new verifiable and coercion-free voting scheme Bingo Voting, which is based on a trusted random number generator. As a motivation for the new scheme two coercion/vote buying attacks on voting schemes are presented which show that it can be dangerous to let the voter contribute randomness to the voting scheme. A proof-of-concept implementation of the scheme shows the practicality of the scheme: all costly computations can be moved to a non time critical pre-voting phase.

Vote-Independence: A Powerful Privacy Notion for Voting Protocols

“…The cited protocols [4,10,15,18] illustrate the hierarchy and show that the inverse implications are not true, as discussed below.…”

“…Bingo Voting was developed by Bohli et al [4] to achieve coercion-resistance as well as individual and universal verifiability by using a trusted random number generator (RNG). We use Bingo Voting to illustrate the existence of protocols that respect Vote-Independence with active Collaboration (V I − AC).…”

“…with passive collaboration of the voter) and "Vote-Independence with active Collaboration (VI-AC)" (which corresponds to Coercion Resistance). We prove the hierarchy of the definitions and illustrate each level with a real world example: the protocol by Fujioka et al [10] provides Vote-Independence (VI), the protocol due to Okamoto [18] ensures VI-PC, and the protocol by Bohli et al [4] guarantees VI-AC. We also show that even Coercion-Resistant protocols may not ensure Vote-Independence (i.e.…”

Defining Privacy for Weighted Votes, Single and Multi-voter Coercion

“…Note that the assumptions (Mod), (EQ) are satisfied by many well-known protocols (e.g. [25,16,26]), we illustrate this on an example.…”

“…Bingo Voting was developed by Bohli et al [25] to achieve coercion-resistance as well as individual and universal verifiability by using a trusted random number generator (RNG) and a voting booth.…”