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On the Impossibility of Surviving (Iterated) Deletion of Weakly Dominated Strategies in Rational MPC

Authors:
Johannes Blömer , Paderborn University
Jan Bobolz , University of Edinburgh
Henrik Bröcher , Paderborn University
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Presentation: Slides
Conference: TCC 2023
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, stable with respect to weak domination. Furthermore, we formally prove that (under certain assumptions) it is impossible to design a secret reconstruction protocol which is a Nash equlibrium but not weakly dominated if (1) shares are authenticated or (2) half of all players may form a coalition.
BibTeX
@inproceedings{tcc-2023-33636,
  title={On the Impossibility of Surviving (Iterated) Deletion of Weakly Dominated Strategies in Rational MPC},
  publisher={Springer-Verlag},
  author={Johannes Blömer and Jan Bobolz and Henrik Bröcher},
  year=2023
}