BBB-Voting: 1-out-of-k Blockchain-Based Boardroom Voting. (arXiv:2010.09112v3 [cs.CR] UPDATED)

Voting is a means to agree on a collective decision based on available
choices (e.g., candidates), where participants (voters) agree to abide by their
outcome. To improve some features of e-voting, decentralized solutions based on
a blockchain can be employed, where the blockchain represents a public bulletin
board that in contrast to a centralized bulletin board provides $100%$
availability and censorship resistance. A blockchain ensures that all entities
in the voting system have the same view of the actions made by others due to
its immutable and append-only log. The existing blockchain-based boardroom
voting solution called Open Voting Network (OVN) provides the privacy of votes
and perfect ballot secrecy, but it supports only two candidates. We present
BBB-Voting, an equivalent blockchain-based approach for decentralized voting
than OVN, but in contrast to it, BBB-Voting supports 1-out-of-$k$ choices and
provides a fault tolerance mechanism that enables recovery from stalling
participants. We provide a cost-optimized implementation using Ethereum, which
we compare with OVN and show that our work decreases the costs for voters by
$13.5%$ in terms of gas consumption. Next, we outline the extension of our
implementation scaling to magnitudes higher number of participants than in a
boardroom voting, while preserving the costs paid by the authority and
participants — we made proof-of-concept experiments with up to 1000
participants.