A recent trend in MPC protocols is to have a more expensive preprocessing phase followed by a very efficient online phase, e.g., the recent so-called SPDZ protocol by Damgård et al. Applications such as voting and some auctions are perfect applications for these protocols, as the parties usually know well in advance when the computation will take place, and using those protocols allows us to use only cheap information theoretic primitives in the actual computation. Unfortunately no protocol of the SPDZ type supports an audit phase.
In this paper we formalize the concept of publicly auditable secure computation and provide an enhanced version of the SPDZ protocol where, even if all the servers are corrupted, anyone with access to the transcript of the protocol can check that the output is indeed correct. Most importantly, we do so without compromising the performance of SPDZ i.e., the cost of our online phase is the same as that of SPDZ, up to a small constant factor of about two.Category / Keywords: cryptographic protocols / Efficient Multiparty Computation, Electronic voting, Public Verifiability Date: received 3 Feb 2014, last revised 10 Feb 2014 Contact author: cbaum at cs au dk Available format(s): PDF | BibTeX Citation Version: 20140210:123550 (All versions of this report) Discussion forum: Show discussion | Start new discussion