Privacy-Preserving Decision-Making Over Blockchain

Many blockchain applications require democratic on-chain decision-making. In this work, we propose a communityinclusive decentralised collaborative decision-making system with privacy assurance. Its key component is a two-stage voting scheme
inspired by choice architecture. Our decision-making system is compatible with most existing blockchain infrastructures. In addition,
it supports liquid democracy/delegative voting for better collaborative intelligence. Namely, stake holders can either vote directly on
proposals or delegate their voting power to experts. When majority of voting committee members are honest, no one can derive voters’
voting preferences or delegations with non-negligible probability. To support concurrent multiple voting events, we design a distributed
batch key generation protocol that can generate multiple keys simultaneously by voting committee members with amortised
communication cost of OðnÞ per key, where n is the number of participants. Besides, our system supports “evolving committee”, i.e.,
voting committee members can be changed during the voting period. We implemented a pilot system in Scala, benchmark results
indicate that our system can support large number of participants with high efficiency.