We develop new definitions of security for this server-aided setting, that generalize the standard simulation-based definitions for MPC, and allow us to formally capture the existence of dishonest but non-colluding participants. This requires us to introduce a formal characterization of non-colluding adversaries that may be of independent interest.
We then design general and special-purpose server-aided MPC protocols that are more efficient (in terms of computation and communication) for the parties than the alternative of running a standard MPC protocol (i.e., without the server). Our main general-purpose protocol provides security when there is at least one honest party with input. We also construct a new and efficient server-aided protocol for private set intersection and give a general transformation from any secure delegated computation scheme to a server-aided two-party protocol.Category / Keywords: cryptographic protocols / multi-party computation, non-collusion, delegated computation, cloud computing Date: received 27 May 2011, last revised 25 Oct 2011 Contact author: senyk at microsoft com Available format(s): PDF | BibTeX Citation Version: 20111025:173858 (All versions of this report) Short URL: ia.cr/2011/272 Discussion forum: Show discussion | Start new discussion