MultiReg-FE: Registered FE for Unbounded Inner-Product and Attribute-Weighted Sums

Qiuyan Du; Qiaohan Chu; Jie Chen; Man Ho Au; Debiao He

Paper 2024/1956

MultiReg-FE: Registered FE for Unbounded Inner-Product and Attribute-Weighted Sums

Qiuyan Du, Shanghai Key Laboratory of Trustworthy Computing, Software Engineering Institute, East China Normal University, Shanghai 200062, China

Qiaohan Chu, Shanghai Key Laboratory of Trustworthy Computing, Software Engineering Institute, East China Normal University, Shanghai 200062, China

Jie Chen, Shanghai Key Laboratory of Trustworthy Computing, Software Engineering Institute, East China Normal University, Shanghai 200062, China

Man Ho Au, Department of Computing, The Hong Kong Polytechnic University

Debiao He, School of Cyber Science and Engineering, Wuhan University, Wuhan 430072, China

Abstract

Recently, Francati et al. (Asiacrypt 2023) provided the first registered functional encryption (Reg-FE) beyond predicates. Reg-FE addresses the key escrow problem in functional encryption by allowing users to generate their own key pairs, effectively replacing the traditional private-key generator with a key curator. The key curator holds no secret information and runs deterministic algorithms to generate master public key for encryption and helper keys for decryption. However, existing Reg-FE schemes under standard assumptions require fixed data sizes, which limits their practicality in real-world applications. In this work, we introduce Multi-Function Registered Functional Encryption for Inner-Product (MultiReg-FE for IP), a novel extension of Reg-FE. It enables users to register multiple functions under a single public key. With MultiReg-FE, we achieve both Reg-FE for Unbounded Inner-Product (Unbounded IP), which removes the need to predetermine vector lengths, and Reg-FE for Attribute-Weighted Sums with Inner-Product (AWSw/IP), allowing computations over arbitrary numbers of attribute-value pairs. All our schemes achieve adaptive-IND-security. Specifically, we present: -MultiReg-FE for Inner-Product, which supports unbounded number of function vectors from each user. - Reg-FE for Unbounded Inner-Product, removing the need for preset vector lengths. - The first Reg-FE for AWSw/IP in public-key settings.

Metadata

Available format(s): PDF
Category: Public-key cryptography
Publication info: Preprint.
Keywords: Registered Functional Encryption Attribute-Weighted Sums Unbounded Inner-Product
Contact author(s): 52285902003 @ stu ecnu edu cn
52205902004 @ stu ecnu edu cn
s080001 @ e ntu edu sg
mhaau @ polyu edu hk
hedebiao @ whu edu cn
History: 2024-12-06: approved; 2024-12-03: received; See all versions
Short URL: https://ia.cr/2024/1956
License: CC BY-NC

BibTeX

@misc{cryptoeprint:2024/1956,
      author = {Qiuyan Du and Qiaohan Chu and Jie Chen and Man Ho Au and Debiao He},
      title = {{MultiReg}-{FE}: Registered {FE} for Unbounded Inner-Product and Attribute-Weighted Sums},
      howpublished = {Cryptology {ePrint} Archive, Paper 2024/1956},
      year = {2024},
      url = {https://eprint.iacr.org/2024/1956}
}