Paper 2026/2387

Quantum Time-Lock Puzzles in the Quantum Random Oracle Model

Prabhanjan Ananth, University of California, Santa Barbara
Yao-Ting Lin, Columbia University
Abstract

A time-lock puzzle allows a sender to hide a message in a puzzle such that recovering the message requires substantially more sequential computation than the time required to generate the puzzle, even when parallel computation is allowed. Applications of time-lock puzzles include timed-release encryption, sealed-bid auctions, electronic voting, fair contract signing, coin flipping, and Byzantine consensus. However, time-lock puzzles are known to be impossible in the classical random oracle model. To overcome the classical barrier, in this work we consider quantum time-lock puzzles, in which the puzzle itself is a quantum state. Our construction in the quantum random oracle model achieves generation in one oracle round, solving in at most $T$ oracle rounds, and security against polynomial-width quantum adversaries of depth $o(T)$ for every polynomially bounded delay $T$, resolving an open problem posed by Mahmoody, Moran, and Vadhan (2011).

Metadata
Available format(s)
PDF
Category
Foundations
Publication info
Preprint.
Keywords
Quantum Cryptography
Contact author(s)
prabhanjan @ cs ucsb edu
yl6463 @ columbia edu
History
2026-10-08: approved
2026-10-06: received
See all versions
Short URL
https://ia.cr/2026/2387
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2026/2387,
      author = {Prabhanjan Ananth and Yao-Ting Lin},
      title = {Quantum Time-Lock Puzzles in the Quantum Random Oracle Model},
      howpublished = {Cryptology {ePrint} Archive, Paper 2026/2387},
      year = {2026},
      url = {https://eprint.iacr.org/2026/2387}
}
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