%0 Conference Paper
%B Proceedings of the 27th annual international cryptology conference on Advances in cryptology
%D 2007
%T Universally-composable two-party computation in two rounds
%A Horvitz,Omer
%A Katz, Jonathan
%X Round complexity is a central measure of efficiency, and characterizing the round complexity of various cryptographic tasks is of both theoretical and practical importance. We show here a universally-composable (UC) protocol (in the common reference string model) for two-party computation of any functionality, where both parties receive output, using only two rounds. (This assumes honest parties are allowed to transmit messages simultaneously in any given round; we obtain a three-round protocol when parties are required to alternate messages.) Our results match the obvious lower bounds for the round complexity of secure two-party computation under any reasonable definition of security, regardless of what setup is used. Thus, our results establish that secure two-party computation can be obtained under a commonly-used setup assumption with maximal security (i.e., security under general composition) in a minimal number of rounds. To give but one example of the power of our general result, we observe that as an almost immediate corollary we obtain a two-round UC blind signature scheme, matching a result by Fischlin at Crypto 2006 (though, in contrast to Fischlin, we use specific number-theoretic assumptions).
%B Proceedings of the 27th annual international cryptology conference on Advances in cryptology
%S CRYPTO'07
%I Springer-Verlag
%C Berlin, Heidelberg
%P 111 - 129
%8 2007///
%@ 3-540-74142-9, 978-3-540-74142-8
%G eng
%U http://dl.acm.org/citation.cfm?id=1777777.1777788