Byzantine Fault Tolerance in the Age of Blockchains and Cloud Computing

Abstract

BFT is a generic technique used for ordering transactions on a distributed system even if a fraction of the processes are controlled by a malicious adversary. BFT is widely known as the model for permissioned blockchains, and is increasingly used in various permissionless blockchains. BFT has also been used in various cloud computing scenarios, such as blockchain-as-a-service, the multi-cloud scenario, and their fault-tolerant components. It is widely believed that there is no one-size-fits-all BFT protocol. We review and discuss some recent results on BFT protocols, covering both partially synchronous BFT protocols and completely asynchronous BFT protocols, and covering their building blocks (e.g., reliable broadcast, Byzantine agreement).