Partial Synchrony for Free? New Upper Bounds for Byzantine Agreement

Fuente: arXiv
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Auteurs principaux: Civit, Pierre, Dzulfikar, Muhammad Ayaz, Gilbert, Seth, Guerraoui, Rachid, Komatovic, Jovan, Vidigueira, Manuel, Zablotchi, Igor
Format: Preprint
Publié: 2024
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author Civit, Pierre
Dzulfikar, Muhammad Ayaz
Gilbert, Seth
Guerraoui, Rachid
Komatovic, Jovan
Vidigueira, Manuel
Zablotchi, Igor
author_facet Civit, Pierre
Dzulfikar, Muhammad Ayaz
Gilbert, Seth
Guerraoui, Rachid
Komatovic, Jovan
Vidigueira, Manuel
Zablotchi, Igor
contents Byzantine agreement allows n processes to decide on a common value, in spite of arbitrary failures. The seminal Dolev-Reischuk bound states that any deterministic solution to Byzantine agreement exchanges Omega(n^2) bits. In synchronous networks, solutions with optimal O(n^2) bit complexity, optimal fault tolerance, and no cryptography have been established for over three decades. However, these solutions lack robustness under adverse network conditions. Therefore, research has increasingly focused on Byzantine agreement for partially synchronous networks. Numerous solutions have been proposed for the partially synchronous setting. However, these solutions are notoriously hard to prove correct, and the most efficient cryptography-free algorithms still require O(n^3) exchanged bits in the worst case. In this paper, we introduce Oper, the first generic transformation of deterministic Byzantine agreement algorithms from synchrony to partial synchrony. Oper requires no cryptography, is optimally resilient (n >= 3t+1, where t is the maximum number of failures), and preserves the worst-case per-process bit complexity of the transformed synchronous algorithm. Leveraging Oper, we present the first partially synchronous Byzantine agreement algorithm that (1) achieves optimal O(n^2) bit complexity, (2) requires no cryptography, and (3) is optimally resilient (n >= 3t+1), thus showing that the Dolev-Reischuk bound is tight even in partial synchrony. Moreover, we adapt Oper for long values and obtain several new partially synchronous algorithms with improved complexity and weaker (or completely absent) cryptographic assumptions.
format Preprint
id arxiv_https___arxiv_org_abs_2402_10059
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Partial Synchrony for Free? New Upper Bounds for Byzantine Agreement
Civit, Pierre
Dzulfikar, Muhammad Ayaz
Gilbert, Seth
Guerraoui, Rachid
Komatovic, Jovan
Vidigueira, Manuel
Zablotchi, Igor
Distributed, Parallel, and Cluster Computing
Byzantine agreement allows n processes to decide on a common value, in spite of arbitrary failures. The seminal Dolev-Reischuk bound states that any deterministic solution to Byzantine agreement exchanges Omega(n^2) bits. In synchronous networks, solutions with optimal O(n^2) bit complexity, optimal fault tolerance, and no cryptography have been established for over three decades. However, these solutions lack robustness under adverse network conditions. Therefore, research has increasingly focused on Byzantine agreement for partially synchronous networks. Numerous solutions have been proposed for the partially synchronous setting. However, these solutions are notoriously hard to prove correct, and the most efficient cryptography-free algorithms still require O(n^3) exchanged bits in the worst case. In this paper, we introduce Oper, the first generic transformation of deterministic Byzantine agreement algorithms from synchrony to partial synchrony. Oper requires no cryptography, is optimally resilient (n >= 3t+1, where t is the maximum number of failures), and preserves the worst-case per-process bit complexity of the transformed synchronous algorithm. Leveraging Oper, we present the first partially synchronous Byzantine agreement algorithm that (1) achieves optimal O(n^2) bit complexity, (2) requires no cryptography, and (3) is optimally resilient (n >= 3t+1), thus showing that the Dolev-Reischuk bound is tight even in partial synchrony. Moreover, we adapt Oper for long values and obtain several new partially synchronous algorithms with improved complexity and weaker (or completely absent) cryptographic assumptions.
title Partial Synchrony for Free? New Upper Bounds for Byzantine Agreement
topic Distributed, Parallel, and Cluster Computing
url https://arxiv.org/abs/2402.10059