Cryptology ePrint Archive: Report 2018/1156

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

Eunkyung Kim and 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-ecient 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.

Category / Keywords: cryptographic protocols / FHE, MFHE

Original Publication (with major differences): ACISP2018

Date: received 27 Nov 2018

Contact author: jungeun7430 at naver com

Available format(s): PDF | BibTeX Citation

Version: 20181203:023832 (All versions of this report)

Short URL:

[ Cryptology ePrint archive ]