Reputation-Based Leader Election under Partial Synchrony: Towards a Protocol-Independent Abstraction with Enhanced Guarantees

TL;DR

This paper introduces a protocol-independent leader election abstraction for partially synchronous BFT systems, along with the SWLE mechanism that improves performance and robustness with minimal overhead.

Contribution

It formalizes a generic correctness framework for leader election under partial synchrony and proposes SWLE, a reputation-based mechanism that enhances efficiency and fault tolerance.

Findings

SWLE achieves up to 4.2x higher throughput.

SWLE reduces latency by 75%.

SWLE lowers Byzantine leader frequency by 27%.

Abstract

Leader election serves a well-defined role in leader-based Byzantine Fault Tolerant (BFT) protocols. Existing reputation-based leader election frameworks for partially synchronous BFTs suffer from either protocol-specific proofs, narrow applicability, or unbounded recovery after network stabilization, leaving an open problem. This paper presents a novel protocol-independent abstraction formalizing generic correctness properties and effectiveness guarantees for leader election under partial synchrony, enabling protocol-independent analysis and design. Building on this, we design the Sliding Window Leader Election (SWLE) mechanism. SWLE dynamically adjusts leader nominations via consensus-behavior-based reputation scores, enforcing Byzantine-cost amplification. We demonstrate SWLE introduces minimal extra overhead to the base protocol and prove it satisfies all abstraction properties and provides superior effectiveness. We show, with a 16-server deployment across 4 different regions in northern China, SWLE achieves up to 4.2x higher throughput, 75% lower latency and 27% Byzantine leader frequency compared to the state-of-the-art solution under common Byzantine faults, while maintaining efficiency in fault-free scenarios.