Privacy Preserving Decision-Making over Blockchain
Creators: name: Zhang, Jiajie
Publisher: name: Lancaster University
Year: 2024

description: Decentralised decision-making systems are now a crucial building block of
 various applications. These systems allow participants to collectively
 decide the direction and outcomes of their projects, reaching decision
 agreements in a democratic and inclusive manner. In this thesis, we
 present our work on a comprehensive and inclusive decentralised
 collaborative decision-making system while ensuring privacy. The system
 core foundation is a 2-stage voting scheme based on choice architecture
 principles. Crucially, this decisionmaking system is built to be
 compatible with existing blockchains and their infrastructure so
 
 it is adaptable and easy to deploy. Furthermore, this system implements
 liquid democracy and delegative voting, allowing the stakeholders to vote
 directly on proposals or delegate their voting powers to experts. The
 combination of wisdom of the crowd and expert knowledge enhances
 collaborative intelligence, resulting in more informed, and therefore
 improved decision-making.
 
 
 To ensure the privacy of voters, our system ensures that even when a
 minority of the voting committee members are dishonest, it is
 computationally impossible for any participant to reveal the voting
 preferences or delegations of voters with a significant probability. These
 privacy assurances are crucial to preserve the integrity of the
 decision-making process and protect participants.
 
 
 Concurrent multiple voting events is an important feature, therefore in
 this thesis we introduce a distributed batch key generation protocol. This
 protocol allows participants to generate multiple keys simultaneously,
 thereby minimizing communication costs with an amortised complexity of
 O(n) per key, where n represents the number of participants. Additionally,
 the system is built to support an evolving committee feature, which allows
 voting committee members to be changed during the voting process. This
 ensures that the decision-making process remains adaptable and aligned
 with the evolving interests and
 
 expertise within the blockchain community through flexibility.
 
 
 We thoroughly analyse the security of our system and demonstrate its
 resilience under the universally composable (UC) framework. By conducting
 a deep investigation of previous systems, we identify gaps such as
 non-private ballots and insecure and/or inefficient voting methods which
 we address in our proposed system successfully. We validate the efficiency
 of our proposed system and implement a demonstration written using the
 programming language Scala. The system is then benchmarked, and the
 results indicate that our system can effectively handle large numbers of
 participants, while maintaining high efficiency throughout the
 decision-making process.
 
 
 We believe that this community-inclusive decentralized collaborative
 decision-making system with privacy assurance contributes to the
 advancement of blockchain governance. This system also ensures that the
 principles of decentralization and democratic decisionmaking are upheld.
 Our proposed system provides incentives for the participants while also
 ensuring their active engagement in the decision-making process by using a
 novel reputation
 
 management scheme. Our research provides a practical and efficient
 solution for blockchain applications requiring transparent and secure
 decision-making processes.