Paper 2022/1047

Perfectly Secure Synchronous MPC with Asynchronous Fallback Guarantees Against General Adversaries

Ananya Appan
Anirudh Chandramouli
Ashish Choudhury, International Institute of Information Technology, Bangalore India
Abstract

In this work, we study perfectly-secure multi-party computation (MPC) against general (non-threshold) adversaries. Known protocols in a synchronous network are secure against $Q^{(3)}$ adversary structures, while in an asynchronous network, known protocols are secure against $Q^{(4)}$ adversary structures. A natural question is whether there exists a single protocol which remains secure against $Q^{(3)}$ and $Q^{(4)}$ adversary structures in a synchronous and in an asynchronous network respectively, where the parties are not aware of the network type. We design the first such best-of-both-worlds protocol against general adversaries. Our result generalizes the result of Appan, Chandramouli and Choudhury (PODC 2022), which presents a best-of-both-worlds perfectly-secure protocol against threshold adversaries. To design our protocol, we present two important building blocks which are of independent interest. The first building block is a best-of-both-worlds perfectly-secure Byzantine agreement (BA) protocol for $Q^{(3)}$ adversary structures, which remains secure both in a synchronous, as well as an asynchronous network. The second building block is a best-of-both-worlds perfectly-secure verifiable secret-sharing (VSS) protocol, which remains secure against $Q^{(3)}$ and $Q^{(4)}$ adversary structures in a synchronous network and an asynchronous network respectively.

Metadata
Available format(s)
PDF
Category
Cryptographic protocols
Publication info
Preprint.
Keywords
Byzantine faults unconditional-security Byzantine agreement secret sharing privacy Multi-Party Computation
Contact author(s)
ananya appan @ iiitb ac in
anirudh c @ iiitb ac in
ashish choudhury @ iiitb ac in
History
2022-08-17: approved
2022-08-12: received
See all versions
Short URL
https://ia.cr/2022/1047
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2022/1047,
      author = {Ananya Appan and Anirudh Chandramouli and Ashish Choudhury},
      title = {Perfectly Secure Synchronous MPC with Asynchronous Fallback Guarantees Against General Adversaries},
      howpublished = {Cryptology ePrint Archive, Paper 2022/1047},
      year = {2022},
      note = {\url{https://eprint.iacr.org/2022/1047}},
      url = {https://eprint.iacr.org/2022/1047}
}
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