A Comparison of Message Exchange Patterns in BFT Protocols

Abstract

The performance and scalability of byzantine fault-tolerant (BFT) protocols for state machine replication (SMR) have recently come under scrutiny due to their application in the consensus mechanism of blockchain implementations. This led to a proliferation of proposals that provide different trade-offs that are not easily compared as, even if these are all based on message passing, multiple design and implementation factors besides the message exchange pattern differ between each of them.In this paper we focus on the impact of different combinations of cryptographic primitives and the message exchange pattern used to collect and disseminate votes, a key aspect for performance and scalability. By measuring this aspect in isolation and in a common framework, we characterise the design space and point out research directions for adaptive protocols that provide the best trade-off for each environment and workload combination.

The Security Reference Architecture for Blockchains: Toward a Standardized Model for Studying Vulnerabilities, Threats, and Defenses

“…These issues can be resolved by combining a BFT voting protocol with lottery-based protocols that reduce the size of the actively communicating nodes to a small committee (e.g., [31], [32], [33], [34], [29]). The scalability of BFT protocols can be also improved by using threshold-based signature aggregation with a gossip-based communication pattern (e.g., [71], [72]).…”