Cryptology ePrint Archive: Report 2011/272

Outsourcing Multi-Party Computation

Seny Kamara and Payman Mohassel and Mariana Raykova

Abstract: We initiate the study of secure multi-party computation (MPC) in a server-aided setting, where the parties have access to a single server that (1) does not have any input to the computation; (2) does not receive any output from the computation; but (3) has a vast (but bounded) amount of computational resources. In this setting, we are concerned with designing protocols that minimize the computation of the parties at the expense of the server.

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)

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