Paper 2016/1072

Game-Theoretic Security for Two-Party Protocols

Haruna Higo, Keisuke Tanaka, Akihiro Yamada, and Kenji Yasunaga

Abstract

Asharov, Canetti, and Hazay (Eurocrypt 2011) studied how game-theoretic concepts can be used to capture the cryptographic properties of correctness, privacy, and fairness in two-party protocols for fail- stop adversaries. In this work, we further study the characterization of the cryptographic properties of specific two-party protocols, oblivious transfer (OT) and commitment, in terms of game theory. Specif- ically, for each protocol, OT and commitment, we define a two-party game between rational sender and receiver together with their utility functions. Then, we prove that a given protocol satisfies cryptographic properties if and only if the strategy of following the protocol is in a Nash equilibrium. Compared to the previous work of Asharov et al., our characterization has several advantages: The game is played by multiple rational parties; All the cryptographic properties of OT/commitment are characterized by a single game; Security for malicious adversaries is considered; Utility functions are specified in general forms based on the preferences of the parties; A solution concept employed is a plain Nash equilibrium. Based on the above equivalence between game-theoretic and cryptographic security, we introduce a new game-theoretic security by considering several unsatisfactory points in the utility functions of the game-theoretic framework. Then, we show that it is equivalent to the cryptographic security against risk- averse adversaries, who behave maliciously, but does not act in a way that can cause the other party’s successful attacks. Our results indicate that the security against risk-averse adversaries may be more natural from the perspective of game theory.

Metadata
Available format(s)
PDF
Category
Cryptographic protocols
Publication info
Preprint. MINOR revision.
Keywords
game theoryoblivious transfercommitment
Contact author(s)
yasunaga @ se kanazawa-u ac jp
History
2017-11-22: last of 2 revisions
2016-11-17: received
See all versions
Short URL
https://ia.cr/2016/1072
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2016/1072,
      author = {Haruna Higo and Keisuke Tanaka and Akihiro Yamada and Kenji Yasunaga},
      title = {Game-Theoretic Security for Two-Party Protocols},
      howpublished = {Cryptology ePrint Archive, Paper 2016/1072},
      year = {2016},
      note = {\url{https://eprint.iacr.org/2016/1072}},
      url = {https://eprint.iacr.org/2016/1072}
}
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