Vivisecting the Dissection: On the Role of Trusted Components in BFT Protocols

TL;DR

This paper critically examines the role of trusted components in Byzantine fault-tolerant protocols, arguing they are best used to enhance resilience to crash faults rather than reduce replica count.

Contribution

It refutes recent claims against trusted components in BFT protocols and advocates for their use to improve crash fault tolerance with fewer replicas.

Findings

Trusted components can improve crash fault tolerance in BFT protocols.

Critiques of using trusted components to reduce replica count are flawed.

Using trusted components enhances resilience rather than performance in BFT protocols.

Abstract

A recent paper by Gupta et al. (EuroSys'23) challenged the usefulness of trusted component (TC) based Byzantine fault-tolerant (BFT) protocols to lower the replica group size from $3f+1$ to $2f+1$, identifying three limitations of such protocols and proposing that TCs should be used instead to improve the performance of BFT protocols. Here, we point out flaws in both arguments and advocate that the most worthwhile use of TCs in BFT protocols is indeed to make them as resilient as crash fault-tolerant (CFT) protocols, which can tolerate up to $f$ faulty replicas using $2f+1$ replicas.