Solution: Mir-BFT: Scalable and Robust BFT for Decentralized Networks

Anonymous

Keywords: blockchain, BFT, consensus

TL;DR: The first BFT total order broadcast protocol to combine parallel leaders with robustness to request duplication

Abstract:

This paper presents Mir-BFT, a robust Byzantine fault-tolerant (BFT) total order broadcast protocol
aimed at maximizing throughput on wide-area networks (WANs),
targeting deployments in decentralized networks,
such as permissioned and Proof-of-Stake permissionless blockchain systems.

Mir-BFT is the first BFT protocol that allows multiple leaders to propose request batches independently
(i.e., parallel leaders), while effectively precluding performance degradation due to request duplication
by rotating the assignment of a partitioned request hash space to leaders.
As this mechanism removes the single-leader bandwidth bottleneck
and exposes a computation bottleneck related to authenticating clients even on a WAN,
our protocol further boosts throughput using a client signature verification sharding optimization.
Our evaluation shows that Mir-BFT outperforms state-of-the-art
single-leader protocols
and orders more than 60000 signed Bitcoin-sized (500-byte) transactions per second
on a widely distributed setup (100 nodes, 1 Gbps WAN) with typical latencies of few seconds.
Moreover, our evaluation exposes the impact of duplicate requests on parallel leader protocols which Mir-BFT eliminates.
We also evaluate Mir-BFT under different crash and Byzantine faults, demonstrating its performance robustness.

Mir-BFT relies on classical BFT protocol constructs, which simplifies reasoning about its correctness.
Specifically, Mir-BFT is a generalization of the celebrated and scrutinized PBFT protocol.
In a nutshell, Mir-BFT follows PBFT ``safety-wise'', with changes needed to accommodate novel features restricted to PBFT liveness.

Area: Distributed Consensus

Type: Solution