Cryptology ePrint Archive: Report 2016/1072

Game-Theoretic Security for Two-Party Protocols

Haruna Higo and Keisuke Tanaka and 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. Specifically, 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.

Category / Keywords: cryptographic protocols / game theory, oblivious transfer, commitment

Date: received 15 Nov 2016, last revised 17 Nov 2016

Contact author: yasunaga at se kanazawa-u ac jp

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Version: 20161117:140157 (All versions of this report)

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