Non-malleable Time-Lock Puzzles and Applications

Cody Freitag, Ilan Komargodski, Rafael Pass, Naomi Sirkin

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

Abstract

Time-lock puzzles are a mechanism for sending messages “to the future”, by allowing a sender to quickly generate a puzzle with an underlying message that remains hidden until a receiver spends a moderately large amount of time solving it. We introduce and construct a variant of a time-lock puzzle which is non-malleable, which roughly guarantees that it is impossible to “maul” a puzzle into one for a related message without solving it. Using non-malleable time-lock puzzles, we achieve the following applications: The first fair non-interactive multi-party protocols for coin flipping and auctions in the plain model without setup.Practically efficient fair multi-party protocols for coin flipping and auctions proven secure in the (auxiliary-input) random oracle model. As a key step towards proving the security of our protocols, we introduce the notion of functional non-malleability, which protects against tampering attacks that affect a specific function of the related messages. To support an unbounded number of participants in our protocols, our time-lock puzzles satisfy functional non-malleability in the fully concurrent setting. We additionally show that standard (non-functional) non-malleability is impossible to achieve in the concurrent setting (even in the random oracle model).

Original languageEnglish
Title of host publicationTheory of Cryptography - 19th International Conference, TCC 2021, Proceedings
EditorsKobbi Nissim, Brent Waters
PublisherSpringer Science and Business Media Deutschland GmbH
Pages447-479
Number of pages33
ISBN (Print)9783030904555
DOIs
StatePublished - 2021
Event19th International Conference on Theory of Cryptography, TCC 2021 - Raleigh, United States
Duration: 8 Nov 202111 Nov 2021

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume13044 LNCS

Conference

Conference19th International Conference on Theory of Cryptography, TCC 2021
Country/TerritoryUnited States
CityRaleigh
Period8/11/2111/11/21

All Science Journal Classification (ASJC) codes

  • Theoretical Computer Science
  • General Computer Science

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