Nakamoto Consensus under Bounded Processing Capacity

Lucianna Kiffer, Joachim Neu, Srivatsan Sridhar, Aviv Zohar, David Tse

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

For Nakamoto’s longest-chain consensus protocol, whose proof-of-work (PoW) and proof-of-stake (PoS) variants power major blockchains such as Bitcoin and Cardano, we revisit the classic problem of the security–performance tradeoff: Given a network of nodes with finite communication- and computation-resources, against what fraction of adversary power is Nakamoto consensus (NC) secure for a given block production rate? State-of-the-art analyses of NC fail to answer this question, because their bounded-delay model does not capture the rate limits to nodes’ processing of blocks, which cause congestion when blocks are released in quick succession. We develop a new analysis technique to prove a refined security–performance tradeoff for PoW NC in a bounded-capacity model. In this model, we show that, in contrast to the classic bounded-delay model, Nakamoto’s private attack is no longer the worst attack, and a new attack we call the teasing strategy, that exploits congestion, is strictly worse. In PoS, equivocating blocks can exacerbate congestion, making traditional PoS NC insecure except at very low block production rates. To counter such equivocation spamming, we present a variant of PoS NC we call Blanking NC (BlaNC), which achieves the same resilience as PoW NC.

Original languageEnglish
Title of host publicationCCS 2024 - Proceedings of the 2024 ACM SIGSAC Conference on Computer and Communications Security
PublisherAssociation for Computing Machinery, Inc
Pages363-377
Number of pages15
ISBN (Electronic)9798400706363
DOIs
StatePublished - 9 Dec 2024
Event31st ACM SIGSAC Conference on Computer and Communications Security, CCS 2024 - Salt Lake City, United States
Duration: 14 Oct 202418 Oct 2024

Publication series

NameCCS 2024 - Proceedings of the 2024 ACM SIGSAC Conference on Computer and Communications Security

Conference

Conference31st ACM SIGSAC Conference on Computer and Communications Security, CCS 2024
Country/TerritoryUnited States
CitySalt Lake City
Period14/10/2418/10/24

Bibliographical note

Publisher Copyright:
© 2024 Copyright held by the owner/author(s).

Keywords

  • bandwidth
  • blockchain
  • capacity
  • consensus
  • Nakamoto
  • spamming

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