Sophisticated Attacks on Decoy Ballots: A Devil's Menu
CER-ETH Working Paper No. 17/283, December 2017
15 Pages Posted: 20 Dec 2017 Last revised: 29 Sep 2019
Date Written: September 27, 2019
Abstract
Voting systems based on decoy ballots aim at preventing real ballots from being bought. Decoy ballots do not count in election outcomes, but are indistinguishable from real ballots. We introduce a “Devil’s Menu” consisting of several price offers and allocation rules, which can be used by a malevolent third party—called the adversary—to curb the protection offered by decoy ballots. In equilibrium, the adversary can buy the real ballots of any strict subset of voting districts at a price corresponding to the willingness to sell them. By contrast, the voters holding decoy ballots are trapped into selling them at a low or negligible price. Decoy ballots may thus be ineffective against vote-buying even if the adversary’s budget is limited.
Keywords: voting, decoy votes, adversary, electronic voting, attacks, lemons market
JEL Classification: C72, D4, D82, D86
Suggested Citation: Suggested Citation