Cryptology ePrint Archive: Report 2022/404

Constant Latency in Sleepy Consensus

Atsuki Momose and Ling Ren

Abstract: Dynamic participation support is an important feature of Bitcoin's longest-chain protocol and its variants. But these protocols suffer from long latency as a fundamental trade-off. Specifically, the latency depends at least on the following two factors: 1) the desired security level of the protocol, and 2) the actual participation level of the network. Classic BFT protocols, on the other hand, can achieve constant latency but cannot make progress under dynamic participation. In this work, we present a protocol that simultaneously supports dynamic participation and achieves constant latency. Our core technique is to extend the classic BFT approach from static quorum size to dynamic quorum size, i.e., according to the current participation level, while preserving important properties of static quorum. We also present a recovery mechanism for rejoining nodes that is efficient in terms of both communication and storage. Our experimental evaluation shows our protocol has much lower latency than a longest-chain protocol, especially when there is a sudden decrease of participation.

Category / Keywords: cryptographic protocols / BFT Protocols, Blockchain, Dynamic Participation, Sleepy Model

Original Publication (in the same form): ACM CCS 2022

Date: received 29 Mar 2022

Contact author: atsuki momose at gmail com

Available format(s): PDF | BibTeX Citation

Version: 20220331:072548 (All versions of this report)

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