SoK: Essentials of BFT Consensus for Blockchains
Gang Wang, Mark S. Nixon · 2023
Blockchain technology has emerged as a transformative force within the contemporary Internet infrastructure, introducing distinctive attributes that have revolutionized existing distributed systems. The principles of decentralization, immutability, and transparency inherent to blockchain have prompted numerous applications to embrace its design philosophy and tailor diverse replicated solutions. Central to the blockchain framework, consensus protocols play a pivotal role in achieving distributed replication systems. The distributed systems research community has devoted considerable effort to dissecting the technical in-tricacies of consensus mechanisms, aimed at facilitating consensus among a cluster of nodes. However, persistent trust concerns make crafting resilient systems for practical scenarios challenging, given the array of potential faults. Byzantine fault-tolerant (BFT) state machine replication (SMR) emerges as an optimal contender capable of withstanding arbitrary faulty behaviors. Yet, the inherent intricacies of BFT consensus protocols, coupled with their rapid evolution, pose practical adaptation challenges across various application domains. Several noteworthy Byzantine-based replicated solutions and innovative concepts have contributed substan-tially to enhancing performance, availability, and resource efficiency. This paper undertakes a comprehensive and systematic exploration of BFT consensus protocols, with a distinct focus on the blockchain era. We delve into the core facets of BFT consensus protocols tailored for Byzantine settings within the realm of blockchain. Further, we deconstruct state-of-the-art solutions to gain a detailed understanding of BFT consensus. For each constituent, we engage in an in-depth discourse concerning its pivotal architectural foundations and key techniques. Our objective is to provide system researchers and developers with a tangible perspective of the present design landscape, thereby aiding them in formulating solutions to specific challenges.