Towards Round-Optimal Secure Multiparty Computations: Multikey FHE Without a CRS
- 주제(키워드) Multikey FHE , LWE assumption , multiparty computation , lattice
- 주제(기타) Computer Science, Theory & Methods
- 설명문(일반) [Kim, Eunkyung] Samsung SDS, Secur Res Team, E Tower,Seongchongil 56, Seoul 06765, South Korea; [Lee, Hyang-Sook; Park, Jeongeun] Ewha Womans Univ, Dept Math, Ewhayeodaegil 52, Seoul 03760, South Korea
- 관리정보기술 faculty
- 등재 SCIE, SCOPUS
- 발행기관 WORLD SCIENTIFIC PUBL CO PTE LTD
- 발행년도 2020
- 총서유형 Journal
- URI http://www.dcollection.net/handler/ewha/000000168807
- 본문언어 영어
- Published As https://dx.doi.org/10.1142/S012905412050001X
초록/요약
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. We also define a new security notion "multikey-CPA security" to prove that a multikey ciphertext cannot be decrypted unless all the secret keys are gathered and our scheme is multikey-CPA secure.
more