### On the impossibility of surviving (iterated) deletion of weakly dominated strategies in rational MPC

##### Abstract

Rational multiparty computation (rational MPC) provides a framework for analyzing MPC protocols through the lens of game theory. One way to judge whether an MPC protocol is rational is through weak domination: Rational players would not adhere to an MPC protocol if deviating never decreases their utility, but sometimes increases it. Secret reconstruction protocols are of particular importance in this setting because they represent the last phase of most (rational) MPC protocols. We show that most secret reconstruction protocols from the literature are not, in fact, rationally sound with respect to weak domination. Furthermore, we formally prove that (under certain assumptions) it is impossible to design a rationally sound secret reconstruction protocol if (1) shares are authenticated or (2) half of all players may form a coalition.

Available format(s)
Category
Foundations
Publication info
Preprint.
Keywords
Game TheoryRational Secret SharingMultiparty ComputationRational CryptographyWeakly Dominated Strategies
Contact author(s)
History
2022-12-27: approved
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Short URL
https://ia.cr/2022/1762

CC BY

BibTeX

@misc{cryptoeprint:2022/1762,
author = {Johannes Blömer and Jan Bobolz and Henrik Bröcher},
title = {On the impossibility of surviving (iterated) deletion of weakly dominated strategies in rational MPC},
howpublished = {Cryptology ePrint Archive, Paper 2022/1762},
year = {2022},
note = {\url{https://eprint.iacr.org/2022/1762}},
url = {https://eprint.iacr.org/2022/1762}
}

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