Paper 2024/327

Registered Functional Encryptions from Pairings

Ziqi Zhu, East China Normal University
Jiangtao Li, Shanghai University
Kai Zhang, Shanghai University of Electric Power
Junqing Gong, East China Normal University, Shanghai Qi Zhi Institute
Haifeng Qian, East China Normal University
Abstract

This work initiates the study of concrete registered functional encryption (Reg-FE) beyond ``all-or-nothing'' functionalities: - We build the first Reg-FE for linear function or inner-product evaluation (Reg-IPFE) from pairings. The scheme achieves adaptive IND-security under $k$-Lin assumption in the prime-order bilinear group. A minor modification yields the first Registered Inner-Product Encryption (Reg-IPE) scheme from $k$-Lin assumption. Prior work achieves the same security in the generic group model. -We build the first Reg-FE for quadratic function (Reg-QFE) from pairings. The scheme achieves very selective simulation-based security (SIM-security) under bilateral $k$-Lin assumption in the prime-order bilinear group. Here, ``very selective'' means that the adversary claims challenge messages, all quadratic functions to be registered and all corrupted users at the beginning. Besides focusing on the compactness of the master public key and helper keys, we also aim for compact ciphertexts in Reg-FE. Let $L$ be the number of slots and $n$ be the input size. Our first Reg-IPFE has weakly compact ciphertexts of size $O(n\cdot\log L)$ while our second Reg-QFE has compact ciphertexts of size $O(n+\log L)$. Technically, for our first Reg-IPFE, we employ nested dual-system method within the context of Reg-IPFE; for our second Reg-QFE, we follow Wee's ``IPFE-to-QFE'' transformation [TCC' 20] but devise a set of new techniques that make our pairing-based Reg-IPFE compatible. Along the way, we introduce a new notion named Pre-Constrained Registered IPFE which generalizes slotted Reg-IPFE by constraining the form of functions that can be registered.

Metadata
Available format(s)
PDF
Category
Public-key cryptography
Publication info
A major revision of an IACR publication in EUROCRYPT 2024
Keywords
Functional EncryptionNested dual-system methodKey-escrow problemPrime-order bilinear groupSimulation-based security
Contact author(s)
52275902001 @ stu ecnu edu cn
lijiangtao @ shu edu cn
kzhang @ shiep edu cn
jqgong @ sei ecnu edu cn
hfqian @ cs ecnu edu cn
History
2024-02-27: approved
2024-02-26: received
See all versions
Short URL
https://ia.cr/2024/327
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2024/327,
      author = {Ziqi Zhu and Jiangtao Li and Kai Zhang and Junqing Gong and Haifeng Qian},
      title = {Registered Functional Encryptions from Pairings},
      howpublished = {Cryptology {ePrint} Archive, Paper 2024/327},
      year = {2024},
      url = {https://eprint.iacr.org/2024/327}
}
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