Towards Round-Optimal Secure Multiparty Computations: Multikey FHE without a CRS

Eunkyung Kim, Hyang-Sook Lee, and Jeongeun Park

Abstract

Multikey fully homomorphic encryption (MFHE) allows homomorphic operations between ciphertexts encrypted under different keys. In applications for secure multiparty computation (MPC)protocols, MFHE can be more advantageous than usual fully homomorphic encryption (FHE) since users do not need to agree with a common public key before the computation when using MFHE. In EUROCRYPT 2016, Mukherjee and Wichs constructed a secure MPC protocol in only two rounds via MFHE which deals with a common random/reference string (CRS) in key generation. After then, Brakerski et al.. replaced the role of CRS with the distributed setup for CRS calculation to form a four round secure MPC protocol. Thus, recent improvements in round complexity of MPC protocols have been made using MFHE. In this paper, we go further to obtain round-efficient and secure MPC protocols. The underlying MFHE schemes in previous works still involve the common value, CRS, it seems to weaken the power of using MFHE to allow users to independently generate their own keys. Therefore, we resolve the issue by constructing an MFHE scheme without CRS based on LWE assumption, and then we obtain a secure MPC protocol against semi-malicious security in three rounds.

Available format(s)
Category
Cryptographic protocols
Publication info
Published elsewhere. MAJOR revision.ACISP2018
DOI
10.1007/978-3-319-93638-3_7
Keywords
FHEMFHE
Contact author(s)
jungeun7430 @ naver com
History
2020-12-22: last of 5 revisions
See all versions
Short URL
https://ia.cr/2018/1156

CC BY

BibTeX

@misc{cryptoeprint:2018/1156,
author = {Eunkyung Kim and Hyang-Sook Lee and Jeongeun Park},
title = {Towards Round-Optimal Secure Multiparty Computations: Multikey FHE without a CRS},
howpublished = {Cryptology ePrint Archive, Paper 2018/1156},
year = {2018},
doi = {10.1007/978-3-319-93638-3_7},
note = {\url{https://eprint.iacr.org/2018/1156}},
url = {https://eprint.iacr.org/2018/1156}
}

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