In this work, we initiate the study of contracts in cryptographic protocol design. We show how to design, use and analyze contracts between parties for the purpose of incentivizing honest behavior from rational adversaries. We refer to such contracts as adversarial level agreements (ALA). The framework we propose can result in more efficient protocols and can enforce deterrence in covert protocols; meaning that one can guarantee that a given deterrence factor will deter the adversary instead of assuming it.
We show how to apply our framework to two-party protocols, including secure two-party computation (2PC) and proofs of storage (PoS). In the 2PC case, we integrate ALAs to publicly-verifiable covert protocols and show, through a game-theoretic analysis, how to set the parameters of the ALA to guarantee honest behavior. We do the same in the setting of PoS which are two-party protocols that allow a client to efficiently verify the integrity of a file stored in the cloud.
Category / Keywords: cryptographic protocols / Adversarial Level Agreements, 2PC, Covert Security, Game Theory, Rational Cryptography, Proofs of Storage Date: received 8 Oct 2020 Contact author: marilyn_george at brown edu Available format(s): PDF | BibTeX Citation Version: 20201009:113830 (All versions of this report) Short URL: ia.cr/2020/1249