PREStO: A Systematic Framework for Blockchain Consensus Protocols

The rapid evolution of blockchain technology has brought together stakeholders from fundamentally different backgrounds. The result is a diverse ecosystem, as exemplified by the development of a wide range of different blockchain protocols. This raises questions for decision and policy makers: How do different protocols compare? What are their trade-offs? Existing efforts to survey the area reveal a fragmented terminology and the lack of a unified framework to reason about the properties of blockchain protocols. In this paper, we work towards bridging this gap. We present a five-dimensional design space with a modular structure in which protocols can be compared and understood. Based on these five axes -- Optimality, Stability, Efficiency, Robustness and Persistence -- we organize the properties of existing protocols in subcategories of increasing granularity. The result is a dynamic scheme -- termed the PREStO framework -- which aids the interaction between stakeholders of different backgrounds, including managers and investors, and which enables systematic reasoning about blockchain protocols. We illustrate its value by comparing existing protocols and identifying research challenges, hence making a first step towards understanding the blockchain ecosystem through a more comprehensive lens.