[This article belongs to Volume - 55, Issue - 09]
Gongcheng Kexue Yu Jishu/Advanced Engineering Science
Journal ID : AES-02-09-2023-615

Sherif Tawfik Amin,

Abstract : The paper investigates the Byzantine Reliable Broadcast Channel (BRBC) in the context of Mobile Byzantine Failures (MBF). BRBC, a pivotal communication primitive in fault-tolerant distributed systems, ensures that all legitimate processes deliver an identical set of messages irrespective of the sender's correctness. The study extends the BRBC to a dynamic model where participants may switch between correct and Byzantine behaviors multiple times in a single execution. This new specification, termed BRBCM, is designed to handle this dynamic and challenging environment. We operate within a fixed set of processes, with each possessing a unique identifier, in a synchronous system where time is marked by sequential rounds divided into sending, receiving, and computation phases. The paper then elucidates on the Mobile Byzantine Failures model, where an external attacker can dynamically control a subset of system processes. Moreover, these processes are capable of identifying when they've been influenced by a mobile Byzantine agent through failure detectors called BFAO and CFAO. The heart of the study introduces the Mobile Byzantine Reliable Broadcast Channel Problem (BRBCM), a redesigned primitive to accommodate mobile Byzantine failures. This involves stringent conditions to maintain the integrity and validity of the broadcast in a dynamic environment. Through rigorous examination, we establish the impossibility of solving the CDFBM problem under standard conditions. However, with the introduction of the OCCD oracle, a solution becomes feasible. This research provides the protocol PCDFBM-RB, an extended model of Bracha's solution, tailored to address the unique challenges of mobile Byzantine reliable broadcast channels.