Rational secret sharing, revisited

We consider the problem of secret sharing among n rational players. This problem was introduced by Halpern and Teague (STOC 2004), who claim that a solution is impossible for n = 2 but show a solution for the case n >= 3. Contrary to their claim, we show a protocol for rational secret sharing among n = 2 players; our protocol extends to the case n >= 3, where it is simpler than the Halpern-Teague solution and also offers a number of other advantages. We also show how to avoid the continual involvement of the dealer, in either our own protocol or that of Halpern and Teague. Our techniques extend to the case of rational players trying to securely compute an arbitrary function, under certain assumptions on the utilities of the players.