Tuxedo: Maximizing Smart Contract Computation in PoW Blockchains

Sourav Das, Nitin Awathare, Ling Ren, Vinay J. Ribeiro, Umesh Bellur

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Proof-of-Work~(PoW) based blockchains typically allocate only a tiny fraction (e.g., less than 1% for Ethereum) of the average interarrival time~$\mathbbI $ between blocks for validating smart contracts present in transactions. In such systems, block validation and PoW mining are typically performed sequentially, the former by CPUs and the latter by ASICs. A trivial increase in validation time~$(t)$ introduces the popularly known Verifier's Dilemma, and as we demonstrate, causes more forking and hurts fairness. Large t also reduces the tolerance for safety against a Byzantine adversary. Solutions that offload validation to a set of non-chain nodes (a.k.a. off-chain approaches) suffer from trust and performance issues that are non-trivial to resolve. In this paper, we present Tuxedo, the first on-chain protocol to theoretically scale t/\mathbbI \approx 1$ in PoW blockchains. The key innovation in Tuxedo is to perform CPU-based block processing in \em parallel to ASIC mining. We achieve this by allowing miners to delay validation of transactions in a block by up to ? blocks, where ? is a system parameter. We perform security analysis of Tuxedo considering all possible adversarial strategies in a synchronous network with maximum end-to-end delay ?and demonstrate that Tuxedo achieves security equivalent to known results for longest chain PoW Nakamoto consensus. Our prototype implementation of Tuxedo atop Ethereum demonstrates that it can scale t without suffering the harmful effects of naïve scaling up of t/\mathbbI $ in existing blockchains.

Original languageEnglish (US)
Title of host publicationSIGMETRICS/PERFORMANCE 2022 - Abstract Proceedings of the 2022 ACM SIGMETRICS/IFIP PERFORMANCE Joint International Conference on Measurement and Modeling of Computer Systems
PublisherAssociation for Computing Machinery, Inc
Pages63-64
Number of pages2
ISBN (Electronic)9781450391412
DOIs
StatePublished - Jun 6 2022
Event2022 ACM SIGMETRICS/IFIP PERFORMANCE Joint International Conference on Measurement and Modeling of Computer Systems, SIGMETRICS/PERFORMANCE 2022 - Virtual, Online, India
Duration: Jun 6 2022Jun 10 2022

Publication series

NameSIGMETRICS/PERFORMANCE 2022 - Abstract Proceedings of the 2022 ACM SIGMETRICS/IFIP PERFORMANCE Joint International Conference on Measurement and Modeling of Computer Systems

Conference

Conference2022 ACM SIGMETRICS/IFIP PERFORMANCE Joint International Conference on Measurement and Modeling of Computer Systems, SIGMETRICS/PERFORMANCE 2022
Country/TerritoryIndia
CityVirtual, Online
Period6/6/226/10/22

Keywords

  • proof-of-work blockchains
  • scalability
  • smart contracts

ASJC Scopus subject areas

  • Computational Theory and Mathematics
  • Computer Networks and Communications
  • Hardware and Architecture
  • Software

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