Cryptology ePrint Archive: Report 2019/1460

Byzantine Fault Tolerance in Partially Synchronous Networks

Yongge Wang

Abstract: The problem of Byzantine Fault Tolerance (BFT) in partial synchronous networks has received a lot of attention in the last 30 years. There are two types of widely accepted definitions for partial synchronous networks. This paper shows that several widely deployed BFT protocols would reach deadlocks in both of these partial synchronous networks (that is, they will not achieve liveness property). To make things worse, it is shown that, for most of the attacks, the adversary only needs to control one participant to carry out the attack instead of controlling (n-1)/3 participants. Based on the analysis of BFT security requirements for partial synchronous networks, this paper proposes a BFT protocol BDLS and proves its security in partial synchronous networks. It is shown that BDLS is one of the most efficient BFT protocols in partial synchronous networks. Specifically, during synchrony with threshold digital signature schemes, BDLS participants could reach agreement in 3 steps with linear communication/authenticator complexity. It is noted that best existing linear communication/authenticator complexity protocols require at least 7 steps to achieve agreement. The BDLS protocol could be used in several application scenarios such as state machine replication or as blockchain finality gadgets.

Category / Keywords: cryptographic protocols / Byzantine Agreement, Blockchain, fault tolerance, asynchronous networks

Date: received 17 Dec 2019, last revised 6 May 2020

Contact author: yonwang at uncc edu

Available format(s): PDF | BibTeX Citation

Version: 20200507:002227 (All versions of this report)

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