On Byzantine Broadcast in Loosely Connected Networks

TL;DR

This paper introduces a new protocol for reliable message broadcasting in loosely connected, multihop asynchronous networks that tolerates Byzantine failures without requiring global knowledge, supported by theoretical conditions and experimental validation.

Contribution

It presents a protocol that guarantees reliable broadcast in loosely connected networks without global knowledge, unlike prior solutions requiring such initialization.

Findings

Protocol tolerates a higher number of Byzantine failures.

Provides conditions for perfect reliable broadcast in torus networks.

Experimental results show effectiveness in probabilistic guarantees.

Abstract

We consider the problem of reliably broadcasting information in a multihop asynchronous network that is subject to Byzantine failures. Most existing approaches give conditions for perfect reliable broadcast (all correct nodes deliver the authentic message and nothing else), but they require a highly connected network. An approach giving only probabilistic guarantees (correct nodes deliver the authentic message with high probability) was recently proposed for loosely connected networks, such as grids and tori. Yet, the proposed solution requires a specific initialization (that includes global knowledge) of each node, which may be difficult or impossible to guarantee in self-organizing networks - for instance, a wireless sensor network, especially if they are prone to Byzantine failures. In this paper, we propose a new protocol offering guarantees for loosely connected networks that does not require such global knowledge dependent initialization. In more details, we give a methodology to determine whether a set of nodes will always deliver the authentic message, in any execution. Then, we give conditions for perfect reliable broadcast in a torus network. Finally, we provide experimental evaluation for our solution, and determine the number of randomly distributed Byzantine failures than can be tolerated, for a given correct broadcast probability.