Pretty Good Strategies for Benaloh Challenge

TL;DR

This paper demonstrates that rational strategies exist for voters to effectively use the Benaloh challenge, supporting its viability as an auditing mechanism in voting systems.

Contribution

It challenges prior claims by showing simple rational strategies that justify the effectiveness of the Benaloh challenge in election auditing.

Findings

Rational strategies can be constructed for voters in the Benaloh challenge.

The existence of these strategies supports the practical use of the mechanism.

The analysis counters previous claims of the mechanism's ineffectiveness.

Abstract

Benaloh challenge allows the voter to audit the encryption of her vote, and in particular to check whether the vote has been represented correctly. An interesting analysis of the mechanism has been presented by Culnane and Teague. The authors propose a natural game-theoretic model of the interaction between the voter and a corrupt, malicious encryption device. Then, they claim that there is no "natural" rational strategy for the voter to play the game. In consequence, the authorities cannot provide the voter with a sensible auditing strategy, which undermines the whole idea. Here, we claim the contrary, i.e., that there exist simple rational strategies that justify the usefulness of Benaloh challenge.