A Brief Study on Byzantine Fault Tolerance, Consensus, and Blockchain

Distributed systems solve large scale complex problems and consensus is at its core, coordinating every single subsystem towards the same goal. Among consensuses, byzantine fault tolerating consensus is a particularly useful kind of consensus which we will extensively discuss. In this paper, we will review the general approaches to solve the consensus problem – deterministic consensus and probabilistic consensus, PBFT and HotStuff's frameworks and properties, impact that HotStuff has on consensus’ framework in the future, and how federated learning uses principle of distributed system to leverage privacy.