Games for exchanging information

Gillat Kol, Moni Naor
2008 Proceedings of the fourtieth annual ACM symposium on Theory of computing - STOC 08  
We consider the rational versions of two of the classical problems in foundations of cryptography: secret sharing and multiparty computation, suggested by Halpern and Teague (STOC 2004). Our goal is to design games and fair strategies that encourage rational participants to exchange information about their inputs for their mutual benet, when the only mean of communication is a broadcast channel. We show that protocols for the above information exchanging tasks, where players' values come from a
more » ... bounded domain, cannot satisfy some of the most desirable properties. In contrast, we provide a rational secret sharing scheme with simultaneous broadcast channel in which shares are taken from an unbounded domain, but have nite (and polynomial sized) expectation. Previous schemes (mostly cryptographic) have required computational assumptions, making them inexact and susceptible to backward induction, or used stronger communication channels. Our scheme is non-cryptographic, immune to backward induction, and satises a stronger rationality concept (strict Nash equilibrium). We show that our solution can also be used to construct an ε-Nash equilibrium secret sharing scheme for the case of a non-simultaneous broadcast channel.
doi:10.1145/1374376.1374437 dblp:conf/stoc/KolN08 fatcat:f7sers4jr5d7jfmlcwarcqf76u