International Association for Cryptologic Research

International Association
for Cryptologic Research


Network Agnostic MPC with Statistical Security

Ananya Appan , UIUC
Ashish Choudhury , IIIT Bangalore
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Presentation: Slides
Conference: TCC 2023
Abstract: In this work, we initiate the study of network agnostic MPC protocols with statistical security. Network agnostic MPC protocols give the best possible security guarantees, irrespective of the behaviour of the underlying network. While network agnostic MPC protocols have been designed earlier with perfect and computational security, nothing is known in the literature regarding their possibility with statistical security. We consider the general-adversary model, where the adversary is characterized by an adversary structure which enumerates all possible candidate subsets of corrupt parties. Known statistically-secure synchronous MPC (SMPC) and asynchronous MPC (AMPC) protocols are secure against adversary structures satisfying the Q^{(2)} and Q^{(3)} conditions respectively, meaning that the union of no two and three subsets from the adversary structure cover the entire set of parties. Fix adversary structures Z_s and Z_a, satisfying the Q^{(2)} and Q^{(3)} conditions respectively, where Z_a \subset Z_s. Then given an unconditionally-secure PKI, we ask whether it is possible to design a statistically-secure MPC protocol, which is resilient against Z_s and Z_a in a synchronous and an asynchronous network respectively, even if the parties are unaware of the network type. We show that this is possible iff Z_s and Z_a satisfy the Q^{(2, 1)} condition, meaning that the union of any two subsets from Z_s and any one subset from Z_a is a proper subset of the set of parties. The complexity of our protocol is polynomial in |Z_s|.
  title={Network Agnostic MPC with Statistical Security},
  author={Ananya Appan and Ashish Choudhury},