With the increasing adoption of decentralized information systems based on a variety of permissionless blockchain networks, the choice of consensus mechanism is at the core of many controversial discussions. Ethereum's recent transition from (PoW) to proof-of-stake (PoS)-based consensus has further fueled the debate on which mechanism is more favorable. While the aspects of energy consumption and degree of (de-)centralization are often emphasized in the public discourse, seminal research has also shed light on the formal security aspects of both approaches individually. However, related work has not yet comprehensively structured the knowledge about the security properties of PoW and PoS. Rather, it has focused on in-depth analyses of specific protocols or high-level comparative reviews covering a broad range of consensus mechanisms. To fill this gap and unravel the commonalities and discrepancies between the formal security properties of PoW- and PoS-based consensus, we conduct a systematic literature review over 26 research articles. Our findings indicate that PoW-based consensus with the longest chain rule provides the strongest formal security guarantees. Nonetheless, PoS can achieve similar guarantees when addressing its more pronounced tradeoff between safety and liveness through hybrid approaches.

翻译：随着基于各类无许可区块链网络的去中心化信息系统日益普及，共识机制的选择成为众多争议性讨论的核心。以太坊近期从工作量证明（PoW）向权益证明（PoS）共识的转型，进一步加剧了关于何种机制更具优势的争论。尽管公众讨论中常强调能耗与（去）中心化程度等层面，但开创性研究也已从形式化安全角度分别对两种方法进行了深入分析。然而，现有研究尚未系统性地梳理PoW与PoS安全属性的相关知识，而是侧重于针对特定协议的深度分析，或涵盖广泛共识机制的高层次比较性综述。为填补这一空白，揭示基于PoW和PoS共识在形式化安全属性上的共性与差异，我们对26篇研究论文进行了系统性文献综述。研究结果表明，采用最长链规则的PoW共识能提供最强的形式化安全保障。尽管如此，PoS通过混合方法应对其安全性-活性间更显著的权衡时，也能达到类似的安全保障水平。