SCALES: MPC with Small Clients and Larger Ephemeral Servers

Anasuya Acharya; Carmit Hazay; Vladimir Kolesnikov; Manoj Prabhakaran

Paper 2022/751

SCALES: MPC with Small Clients and Larger Ephemeral Servers

Anasuya Acharya

, Bar-Ilan University

Carmit Hazay

, Bar-Ilan University

Vladimir Kolesnikov

, Georgia Institute of Technology

Manoj Prabhakaran, Indian Institute of Technology Bombay

Abstract

The recently proposed YOSO model is a groundbreaking approach to MPC, executable on a public blockchain, circumventing adaptive player corruption by hiding the corruption targets until they are worthless. Players are selected unpredictably from a large pool to perform MPC subtasks, in which each selected player sends a single message (and reveals their identity). While YOSO MPC has attractive asymptotic complexity, unfortunately, it is concretely prohibitively expensive due to the cost of its building blocks. We propose a modification to the YOSO model that preserves resilience to adaptive server corruption, but allows for much more efficient protocols. In SCALES (Small Clients And Larger Ephemeral Servers) only the servers facilitating the MPC computation are ephemeral (unpredictably selected and ``speak once''). Input providers (clients) publish problem instances and collect the output, but do not otherwise participate in computation. SCALES offers attractive features, and improves over YOSO protocols in outsourcing MPC to a large pool of servers under adaptive corruption. We build SCALES from rerandomizable garbling schemes, which is a contribution of independent interest, with additional applications.

Note: Fixed a gap in the definition of sharable KMHE and the construction of sharable KMHE from the BHHO08 encryption scheme. This was required to fix the existing RGC construction.

Metadata

Available format(s): PDF
Category: Cryptographic protocols
Publication info: A major revision of an IACR publication in TCC 2022
Keywords: SCALES Ephemeral Servers YOSO Rerandomizable Garbling Schemes Garbled Circuits Homomorphic Encryption iDRE
Contact author(s): acharya @ biu ac il
carmit hazay @ biu ac il
kolesnikov @ gatech edu
mp @ cse iitb ac in
History: 2023-04-05: last of 3 revisions; 2022-06-12: received; See all versions
Short URL: https://ia.cr/2022/751
License: CC BY

BibTeX

@misc{cryptoeprint:2022/751,
      author = {Anasuya Acharya and Carmit Hazay and Vladimir Kolesnikov and Manoj Prabhakaran},
      title = {SCALES: MPC with Small Clients and Larger Ephemeral Servers},
      howpublished = {Cryptology ePrint Archive, Paper 2022/751},
      year = {2022},
      note = {\url{https://eprint.iacr.org/2022/751}},
      url = {https://eprint.iacr.org/2022/751}
}