Delegated Time-Lock Puzzle

Aydin Abadi; Dan Ristea; Steven J. Murdoch

Paper 2023/1183

Delegated Time-Lock Puzzle

Aydin Abadi

, University College London

Dan Ristea

, University College London

Steven J. Murdoch

, University College London

Abstract

Time-Lock puzzles (TLP) are cryptographic protocols that enable a client to lock a message in such a way that a server can only unlock it after a specific time period. However, existing TLPs have certain limitations: (i) they assume that both the client and server always possess sufficient computational resources and (ii) they solely focus on the lower time bound for finding a solution, disregarding the upper bound that guarantees a regular server can find a solution within a certain time frame. Additionally, existing TLPs designed to handle multiple puzzles either (a) entail high verification costs or (b) lack generality, requiring identical time intervals between consecutive solutions. To address these limitations, this paper introduces, for the first time, the concept of a "Delegated Time-Lock Puzzle" and presents a protocol called "Efficient Delegated Time- Lock Puzzle" (ED-TLP) that realises this concept. ED-TLP allows the client and server to delegate their resource-demanding tasks to third-party helpers. It facilitates real-time verification of solution correctness and efficiently handles multiple puzzles with varying time intervals. ED-TLP ensures the delivery of solutions within predefined time limits by incorporating both an upper bound and a fair payment algorithm. We have implemented ED-TLP and conducted a comprehensive analysis of its overheads, demonstrating the efficiency of the construction

Metadata

Available format(s): PDF
Category: Cryptographic protocols
Publication info: Preprint.
Keywords: Time-lock puzzle Delegated Computation Blockchain Smart Contracts Verifiable Delay Function
Contact author(s): aydin abadi @ ucl ac uk
dan ristea 19 @ ucl ac uk
s murdoch @ ucl ac uk
History: 2023-08-04: approved; 2023-08-02: received; See all versions
Short URL: https://ia.cr/2023/1183
License: CC BY

BibTeX

@misc{cryptoeprint:2023/1183,
      author = {Aydin Abadi and Dan Ristea and Steven J. Murdoch},
      title = {Delegated Time-Lock Puzzle},
      howpublished = {Cryptology ePrint Archive, Paper 2023/1183},
      year = {2023},
      note = {\url{https://eprint.iacr.org/2023/1183}},
      url = {https://eprint.iacr.org/2023/1183}
}