Dispute Resolution in Voting
This work addresses dispute resolution for voting systems, which is crucial for ensuring trust and integrity in elections, but it is incremental as it builds on existing protocol classes and definitions.
The paper tackles the problem of resolving disputes in voting protocols where voters and authorities may make false claims, by systematically characterizing disputes and proposing a new definition that accounts for timeliness and communication topologies. It demonstrates utility by analyzing a mixnet-based voting protocol and proving it satisfies dispute resolution, verifiability, and receipt-freeness using machine-checked and traditional proofs.
In voting, disputes arise when a voter claims that the voting authority is dishonest and did not correctly process his ballot while the authority claims to have followed the protocol. A dispute can be resolved if any third party can unambiguously determine who is right. We systematically characterize all relevant disputes for a generic, practically relevant, class of voting protocols. Based on our characterization, we propose a new definition of dispute resolution for voting that accounts for the possibility that both voters and the voting authority can make false claims and that voters may abstain from voting. A central aspect of our work is timeliness: a voter should possess the evidence required to resolve disputes no later than the election's end. We characterize what assumptions are necessary and sufficient for timeliness in terms of a communication topology for our voting protocol class. We formalize the dispute resolution properties and communication topologies symbolically. This provides the basis for verification of dispute resolution for a broad class of protocols. To demonstrate the utility of our model, we analyze a mixnet-based voting protocol and prove that it satisfies dispute resolution as well as verifiability and receipt-freeness. To prove our claims, we combine machine-checked proofs with traditional pen-and-paper proofs.