Permissionless Clock Synchronization with Public Setup

Juan Garay, Aggelos Kiayias, Yu Shen

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

Abstract / Description of output

The permissionless clock synchronization problem asks how it is possible for a population of parties to maintain a system-wide synchronized clock, while their participation rate fluctuates —possibly very widely— over time. The underlying assumption is that parties experience the passage of time with roughly the same speed, but however they may disengage and engage with the protocol following arbitrary (and even chosen adversarially) participation patterns. This (classical) problem has received renewed attention due to the advent of blockchain protocols, and recently it has been solved in the setting of proof of stake, i.e., when parties are assumed to have access to a trusted PKI setup [Badertscher et al., Eurocrypt ’21]. In this work, we present the first proof-of-work (PoW)-based permissionless clock synchronization protocol. Our construction assumes a public setup (e.g., a CRS) and relies on an honest majority of computational power that, for the first time, is described in a fine-grain timing model that does not utilize a global clock that exports the current time to all parties. As a secondary result of independent interest, our protocol gives rise to the first PoW-based ledger consensus protocol that does not rely on an external clock for the time-stamping of transactions and adjustment of the PoW difficulty.
Original languageEnglish
Title of host publicationTheory of Cryptography: 20th International Conference, TCC 2022, Chicago, IL, USA, November 7–10, 2022, Proceedings, Part III
EditorsEike Kiltz, Vinod Vaikuntanathan
PublisherSpringer, Cham
Number of pages31
ISBN (Electronic)978-3-031-22368-6
ISBN (Print)978-3-031-22367-9
Publication statusPublished - 1 Jan 2023
EventThe 20th Theory of Cryptography Conference, 2022 - Chicago, United States
Duration: 7 Nov 202210 Nov 2022
Conference number: 20

Publication series

NameLecture Notes in Computer Science
PublisherSpringer Cham
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


ConferenceThe 20th Theory of Cryptography Conference, 2022
Abbreviated titleTCC 2022
Country/TerritoryUnited States
Internet address


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