Ordinos: A Verifiable Tally-Hiding E-Voting System

Abstract

Modern electronic voting systems (e-voting systems) are designed to provide not only vote privacy but also (end-to-end) verifiability. Several verifiable e-voting systems have been proposed in the literature, with Helios being one of the most prominent ones.Almost all such systems, however, reveal not just the voting result but also the full tally, consisting of the exact number of votes per candidate or even all single votes. There are several situations where this is undesirable. For example, in elections with only a few voters (e.g., boardroom or jury votings), revealing the complete tally leads to a low privacy level, possibly deterring voters from voting for their actual preference. In other cases, revealing the complete tally might unnecessarily embarrass some candidates. Often, the voting result merely consists of a single winner or a ranking of candidates, so revealing only this information but not the complete tally is sufficient. This property is called tallyhiding and it offers completely new options for e-voting.In this paper, we propose the first provably secure endto-end verifiable tally-hiding e-voting system, called Ordinos. We instantiated our system with suitable cryptographic primitives, including an MPC protocol for greater-than tests, implemented the system, and evaluated its performance, demonstrating its practicality. Moreover, our work provides a deeper understanding of tally-hiding in general, in particular in how far tally-hiding affects the levels of privacy and verifiability of e-voting systems.

Revisiting Practical and Usable Coercion-Resistant Remote E-Voting

“…For the Paillier-based system that we have presented it would be natural to add the tally system from Ordinos [12] since this is also based on Paillier encryption. Ordinos will only reveal the winner or the ranking of the candidates in the election, and will thus help for coercion-resistance in the case where there are candidates which expected to only get few or no votes.…”

“…This algorithm is linear in the bit length, i.e. logarithmic in the security parameter, and can be made public verifiable [12]. Using this technique allows us to do the weeding process secure and efficient, but at the cost of all ballots being submitted with a voter identifier.…”

Epoque: Practical End-to-End Verifiable Post-Quantum-Secure E-Voting

“…In this section, we carry out a rigorous analysis of the vote privacy of Epoque and show that the privacy level of Epoque is ideal. For this purpose, we use the privacy definition for e-voting protocols proposed in [51] which has already been used to analyze a number of further voting protocols and mix nets [47]- [49], [51], [52].…”

An Improved Coercion-Resistant E-Voting Scheme

“…erefore, in practical application, the secure e-voting scheme needs to satisfy some necessary security requirements to protect the privacy of ballot, such as freedom (no one can be forced to cast a certain vote); fairness (no one can use more than his own votes to influence the tallying result); confidentiality (no one can know other voter's content except himself ); coercion resistance [7][8][9][10] (the voter proves nothing about the content of his ballot to others); verifiability [11,12] (every voter can verify if his ballot is correctly tallied, and any participant can verify the correctness of tallying result).…”