## Cryptology ePrint Archive: Report 2010/029

On Achieving the "Best of Both Worlds" in Secure Multiparty Computation

Yuval Ishai and Jonathan Katz and Eyal Kushilevitz and Yehuda Lindell and Erez Petrank

Abstract: Two settings are traditionally considered for secure multiparty computation, depending on whether or not a majority of the parties are assumed to be honest. Protocols designed under this assumption provide full security'' (and, in particular, guarantee output delivery and fairness) when this assumption holds; unfortunately, these protocols are completely insecure if this assumption is violated. On the other hand, protocols tolerating an arbitrary number of corruptions do not guarantee fairness or output delivery even if only a \emph{single} party is dishonest.

It is natural to wonder whether it is possible to achieve the best of both worlds'': namely, a single protocol that simultaneously achieves the best possible security in both the above settings. Here, we rule out this possibility (at least for general functionalities) but show some positive results regarding what \emph{can} be achieved.

Category / Keywords: foundations / secure computation, guaranteed output delivery, privacy

Publication Info: This is a full version of the combination of two papers by the authors. The first paper by Ishai, Kushilevitz, Lindell and Petrank appeared at CRYPTO 2006 and the second paper by Katz appeared at STOC 2007.

Date: received 20 Jan 2010

Contact author: lindell at cs biu ac il

Available format(s): PDF | BibTeX Citation

[ Cryptology ePrint archive ]