Paper 2024/769

Time-Based Cryptography From Weaker Assumptions: Randomness Beacons, Delay Functions and More

Damiano Abram, Aarhus University
Lawrence Roy, Aarhus University
Mark Simkin, Ethereum Foundation
Abstract

The assumption that certain computations inherently require some sequential time has established itself as a powerful tool for cryptography. It allows for security and liveness guarantees in distributed protocols that are impossible to achieve with classical hardness assumptions. Unfortunately, many constructions from the realm of time-based cryptography are based on new and poorly understood hardness assumptions, which tend not to stand the test of time (cf. Leurent et al. 2023, Peikert & Tang 2023). In this work, we make progress on several fronts. We formally define the concept of a delay function and present a construction thereof from minimal assumptions. We show that these functions, in combination with classical cryptographic objects that satisfy certain efficiency criteria, would allow for constructing delay encryption, which is otherwise only known to exist based on a new hardness assumption about isogenies. We formally define randomness beacons as they are used in the context of blockchains, and we show that (linearly homomorphic) time-lock puzzles allow for efficiently constructing them. Our work puts time-based cryptography on a firmer theoretical footing, provides new constructions from simpler assumptions, and opens new avenues for constructing delay encryption.

Metadata
Available format(s)
PDF
Category
Foundations
Publication info
Preprint.
Keywords
Time-Lock PuzzlesDelay EncryptionRandomness BeaconsDelay Functions
Contact author(s)
damiano abram @ cs au dk
ldr709 @ gmail com
mark simkin @ ethereum org
History
2024-05-23: revised
2024-05-20: received
See all versions
Short URL
https://ia.cr/2024/769
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2024/769,
      author = {Damiano Abram and Lawrence Roy and Mark Simkin},
      title = {Time-Based Cryptography From Weaker Assumptions: Randomness Beacons, Delay Functions and More},
      howpublished = {Cryptology {ePrint} Archive, Paper 2024/769},
      year = {2024},
      url = {https://eprint.iacr.org/2024/769}
}
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