International Association for Cryptologic Research

International Association
for Cryptologic Research


MPC With Delayed Parties Over Star-Like Networks

Mariana Gama , COSIC, KULeuven
Emad Heydari Beni , COSIC, KULeuven and Nokia Bell Labs
Emmanuela Orsini , Bocconi University, Italy
Nigel Smart , COSIC, KULeuven and Zama
Oliver Zajonc , COSIC, KULeuven
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Presentation: Slides
Conference: ASIACRYPT 2023
Abstract: This paper examines multi-party computation protocols in the presence of two major constraints present in deployed systems. Firstly, we consider the situation where the parties are connected not by direct point-to-point connections, but by a star-like topology with a few central post-office style relays. Secondly, we consider MPC protocols with a strong honest majority ($t \gg n/2$) in which we have stragglers (some parties are progressing slower than others). We model stragglers by allowing the adversary to delay messages to and from some parties for a given length of time. We first show that having only a single honest relay is enough to ensure consensus of the messages sent within a protocol; secondly, we show that special care must be taken to describe multiplication protocols in the case of relays and stragglers; thirdly, we present an efficient honest-majority MPC protocol which can be run ontop of the relays and which provides active-security with abort in the case of a strong honest majority, even when run with stragglers. We back up our protocol presentation with both experimental evaluations and simulations of the effect of the relays and delays on our protocol.
  title={MPC With Delayed Parties Over Star-Like Networks},
  author={Mariana Gama and Emad Heydari Beni and Emmanuela Orsini and Nigel Smart and Oliver Zajonc},