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Daniel Esteban Escudero Ospina

An Efficient Passive-to-Active Compiler for Honest-Majority MPC over Rings

Research output: Contribution to book/anthology/report/proceedingArticle in proceedingsResearchpeer-review

Multiparty computation (MPC) over rings such as $\mathbb{Z}_{2^{32}}$ or
$\mathbb{Z}_{2^{64}}$ has received a great deal of attention recently due to
its ease of implementation and attractive performance. Several actively secure
protocols over these rings have been implemented, for both the dishonest
majority setting and the setting of three parties with one corruption.
However, in the honest majority setting, no \emph{concretely} efficient
protocol for arithmetic computation over rings has yet been proposed that
allows for an \emph{arbitrary} number of parties.

We present a novel compiler for MPC over the ring $\mathbb{Z}_{2^{k}}$ in the
honest majority setting that turns a semi-honest protocol into an
actively secure protocol with very little overhead. The communication cost per
multiplication is only twice that of the semi-honest protocol, making
the resultant actively secure protocol almost as fast.

To demonstrate the efficiency of our compiler, we implement both an optimized
3-party variant (based on replicated secret-sharing), as well as a protocol
for $n$ parties (based on a recent protocol from TCC 2019). For the 3-party
variant, we obtain a protocol which outperforms the previous state of the art
that we can experimentally compare against. Our $n$-party variant
is the first implementation for this particular setting, and we show
that it performs comparably to the current state of the art over fields.
Original languageEnglish
Title of host publicationACNS'21
Publication year2021
Publication statusPublished - 2021

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