CAREER: Scalable Consensus Protocol Design with Accountability and Privacy under Practical Failure Models

在许多领域，如商业和金融，少数组织被信任来维护数据和交易的完整性。如果这些组织失败，核心完整性属性就会丢失。区块链系统构成了将信任分散给多方的关键基础设施和技术，即使其中一些是恶意的，也能保持完整性。由于存储信息的价值，这些系统需要能够容忍很大一部分恶意方，确保这些方没有不当行为的动机，并在攻击发生时追究各方的责任和恢复。此外，为了实现可伸缩性，这些系统需要具有较低的通信复杂性、良好的延迟，并支持私有事务。不幸的是，现有的区块链系统不能满足所有这些需求。该项目通过考虑问责制、实际失败模型和隐私等几个属性，弥合了区块链共识的理论基础和实际方面之间的差距，取得了新的科学进展。该项目更广泛的意义和重要性包括：(i)改进公共区块链（如Ethereum和Zcash）、基于行业的许可区块链（如VMware Concord）以及去中心化金融和中央银行数字货币等应用程序的设计，（ii）全面的教育、传播和推广计划，导致(a)使用开源材料的新研究生和本科课程，(b)研究生、本科生的指导，高中生——尤其是来自计算机领域代表性不足的少数族裔的学生，以及(c)组织促进区块链跨学科合作的活动。该项目利用并揭示了分布式计算、理论、隐私、博弈论和计算机系统之间的协同作用。它回答了以下基本研究问题：1)定义和研究故障检测和恢复机制，以及它们如何作为系统安全性和效率的反馈回路；2)设计安全高效的自稳定同步协议，允许少数人腐败；3)在理性各方存在的情况下分析共识；4)理解保护隐私的权益证明协议的限制和设计随机隐私机制。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In many fields, such as commerce and finance, a small number of organizations are trusted to maintain the integrity of data and transactions. If these organizations fail, the core integrity property is lost. Blockchains systems form the critical infrastructure and technology for decentralizing trust to multiple parties such that integrity is maintained even if some of them are malicious. Due to the value of the information stored, these systems need the ability to tolerate a significant fraction of malicious parties, ensure these parties do not have an incentive to misbehave, and hold parties accountable and recover in case of an attack. Moreover, for scalability, these systems need to have low communication complexity, good latency, and support private transactions. Unfortunately, existing blockchain systems do not meet all of these requirements. This project makes novel scientific advances by bridging the gap between theoretical foundations and the practical aspects of blockchain consensus by considering several properties such as accountability, practical failure models, and privacy. The project's broader significance and importance include: (i) improved designs for public blockchains such as Ethereum and Zcash, industry-based permissioned blockchains such as VMware Concord, and applications such as decentralized finance and Central Banking Digital Currencies, (ii) a comprehensive education, dissemination, and outreach plan resulting in (a) new graduate and undergraduate courses with open-source materials, (b) the mentoring of graduate, undergraduate, and high school students – especially from underrepresented minorities in computing, and (c) organizing events that facilitate interdisciplinary collaboration on blockchains.The project exploits and reveals synergies between distributed computing, theory, privacy, game theory, and computer systems. It answers fundamental research questions on 1) defining and studying mechanisms for fault detection and recovery and how they act as a feedback loop to the security and efficiency of the system, 2) designing secure and efficient self-stabilizing synchronous protocols tolerating minority corruption, 3) analyzing consensus in the presence of rational parties, and 4) understanding the limits of and designing randomized privacy mechanisms for privacy-preserving proof-of-stake protocols.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.