Paper 2025/242

Rational Secret Sharing with Competition

Tiantian Gong, Yale University
Zeyu Liu, Yale University
Abstract

The rational secret sharing problem (RSS) considers incentivizing rational parties to share their received information to reconstruct a correctly shared secret. Halpern and Teague (STOC'04) demonstrate that solving the RSS problem deterministically with explicitly bounded runtime is impossible, if parties prefer learning the secret than not learning, and they prefer fewer other parties to learn. To overcome this impossibility result, we propose RSS with competition. We consider a slightly different yet sensible preference profile: Each party prefers to learn the secret early and prefers fewer parties learning before them. This preference profile changes the information-hiding dynamics among parties in prior works: First, those who have learned the secret are indifferent towards or even prefer informing others later; second, the competition to learn the secret earlier among different access groups in the access structure facilitates information sharing inside an access group. As a result, we are able to construct the first deterministic RSS algorithm that terminates in at most two rounds. Additionally, our construction does not employ any cryptographic machinery (being fully game-theoretic and using the underlying secret-sharing scheme as a black-box) nor requires the knowledge of the parties' exact utility function. Furthermore, we consider general access structures.

Note: This is the full version of the conference proceedings.

Metadata
Available format(s)
PDF
Category
Cryptographic protocols
Publication info
Published elsewhere. Minor revision. Financial Cryptography and Data Security 2025
Keywords
Rational secret sharing
Contact author(s)
tiantian gong @ yale edu
zeyu liu @ yale edu
History
2025-03-01: revised
2025-02-16: received
See all versions
Short URL
https://ia.cr/2025/242
License
Creative Commons Attribution-NonCommercial-ShareAlike
CC BY-NC-SA

BibTeX

@misc{cryptoeprint:2025/242,
      author = {Tiantian Gong and Zeyu Liu},
      title = {Rational Secret Sharing with Competition},
      howpublished = {Cryptology {ePrint} Archive, Paper 2025/242},
      year = {2025},
      url = {https://eprint.iacr.org/2025/242}
}
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