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Resilience to Chain-Quality Attacks in Fair Separability

In this paper, it is proposed that an implementation of fair separability where the cost of outputting transactions remains consistent for the inputs of all processes, which enhances resilience to chain-quality attacks.

Authored by:
Vincent Gramoli, University of Sydney
Zhenliang Lu, University of Sydney
Qiang Tang, University of Sydney
Pouriya Zarbafian, University of Sydney


In recent years, a new research area called order-fairness has emerged within State Machine Replication (SMR). Its goal is to prevent malicious processes from reordering transactions, ensuring that the SMR output reflects the local orderings observed by processes. One of the advanced approaches to addressing this challenge is fair separability, which is designed to mitigate cyclic dependencies present in transaction dependency graphs.

However, in the existing implementation of fair separability, a transaction input by a Byzantine process can be output with only O(1) resources, whereas outputting a transaction input by a correct process requires O(n) resources. This vulnerability exposes the protocol to chain-quality attacks.

This paper was co-authored by our CTO and Founder, Professor Vincent Gramoli.

Professor Vincent Gramoli is a full professor at the University of Sydney. He is a researcher in the field of distributed systems and algorithms, with a focus on the design and analysis of distributed systems and algorithms for shared memory and data-centric systems, including distributed hash tables, distributed shared memory and transactional memory. He has published numerous papers in top-tier conferences and journals in the field and has received several awards for his research. He is also currently serving as the Head of Concurrent Systems Research Group at the University of Sydney.

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