Cross-Chain State Machine Replication

TL;DR

This paper introduces a new cross-chain state machine replication protocol that uses path signatures to ensure consistency among Byzantine participants, separating application logic from fault-tolerance.

Contribution

It presents a novel SMR protocol tailored for cross-chain exchanges, achieving $O(n)$ message delays and systematically replacing ad-hoc cross-chain solutions.

Findings

Protocol achieves $O(n)$ message delays.

Uses path signatures for consistency.

Separates application logic from fault-tolerance.

Abstract

This paper considers the classical state machine replication (SMR) problem in a distributed system model inspired by cross-chain exchanges. We propose a novel SMR protocol adapted for this model. Each state machine transition takes $O(n)$ message delays, where $n$ is the number of active participants, of which any number may be Byzantine. This protocol makes novel use of path signatures to keep replicas consistent. This protocol design cleanly separates application logic from fault-tolerance, providing a systematic way to replace complex ad-hoc cross-chain protocols with a more principled approach.