10.5281/zenodo.3952218
https://zenodo.org/records/3952218
oai:zenodo.org:3952218
Jamroga, W.
W.
Jamroga
University of Luxembourg
Roenne, P.
P.
Roenne
Polish Academy of Sciences
Ryan, P.
P.
Ryan
University of Luxembourg
Stark, P.
P.
Stark
University of California
Risk-Limiting Tallies
Zenodo
2020
End-to-end verifiability
Risk-limiting audits
Plausible deniability
Coercion resistance
2020-07-20
eng
10.5281/zenodo.3952217
https://zenodo.org/communities/futuretpm-h2020
https://zenodo.org/communities/eu
Creative Commons Attribution 4.0 International
Many voter-verifiable, coercion-resistant schemes have been proposed, but even the most carefully designed systems necessarily leak information via the announced result. In corner cases, this may be problematic. For example, if all the votes go to one candidate then all vote privacy evaporates. The mere possibility of candidates getting no or few votes could have implications for security in practice: if a coercer demands that a voter cast a vote for such an unpopular candidate, then the voter may feel obliged to obey, even if she is confident that the voting system satisfies the standard coercion resistance definitions. With complex ballots, there may also be a danger of “Italian” style (aka “signature”) attacks: the coercer demands the voter cast a ballot with a specific, identifying pattern. Here we propose an approach to tallying end-to-end verifiable schemes that avoids revealing all the votes but still achieves whatever confidence level in the announced result is desired. Now a coerced voter can claim that the required vote must be amongst those that remained shrouded. Our approach is based on the well-established notion of Risk-Limiting Audits, but here applied to the tally rather than to the audit. We show that this approach counters coercion threats arising in extreme tallies and “Italian” attacks. We illustrate our approach by applying it to the Selene scheme, and we extend the approach to Risk-Limiting Verification, where not all vote trackers are revealed, thereby enhancing the coercion mitigation properties of Selene.
European Commission
10.13039/501100000780
779391
Future Proofing the Connected World: A Quantum-Resistant Trusted Platform Module