Paper 2024/740

Multi-Client Functional Encryption with Public Inputs and Strong Security

Ky Nguyen, DIENS, Ecole normale superieure, CNRS, Inria, PSL University, Paris, France
Duong Hieu Phan, LTCI, Telecom Paris, Institut Polytechnique de Paris, France
David Pointcheval, DIENS, Ecole normale superieure, CNRS, Inria, PSL University, Paris, France
Abstract

Recent years have witnessed a significant development for functional encryption (FE) in the multi-user setting, particularly with multi-client functional encryption (MCFE). The challenge becomes more important when combined with access control, such as attribute-based encryption (ABE), which was actually not covered by the FE and MCFE frameworks. On the other hand, as for complex primitives, many works have studied the admissibility of adversaries to ensure that the security model encompasses all real threats of attacks. In this paper, adding a public input to FE/MCFE, we cover many previous primitives, notably attribute-based function classes. Furthermore, with the strongest admissibility for inner-product functionality, our framework is quite versatile, as it encrypts multiple sub-vectors, allows repetitions and corruptions, and eventually also encompasses public-key FE and classical ABE, bridging the private setting of MCFE with the public setting of FE and ABE. Finally, we propose an MCFE with public inputs with the class of functions that combines inner-products (on private inputs) and attribute-based access-control (on public inputs) for LSSS policies. We achieve the first AB-MCFE for inner-products with strong admissibility and with adaptive security. This also leads to MIFE for inner products, public-key single-input inner-product FE with LSSS key-policy and KPABE for LSSS, with adaptive security while the previous AB-MCFE construction of Agrawal et al. from CRYPTO '23 considers a slightly larger functionality of average weighted sum but with selective security only.

Metadata
Available format(s)
PDF
Category
Public-key cryptography
Publication info
Preprint.
Keywords
Functional EncryptionSecurity Notions
Contact author(s)
ky nguyen @ ens fr
hieu phan @ telecom-paris fr
david pointcheval @ ens fr
History
2024-05-16: approved
2024-05-15: received
See all versions
Short URL
https://ia.cr/2024/740
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2024/740,
      author = {Ky Nguyen and Duong Hieu Phan and David Pointcheval},
      title = {Multi-Client Functional Encryption with Public Inputs and Strong Security},
      howpublished = {Cryptology {ePrint} Archive, Paper 2024/740},
      year = {2024},
      url = {https://eprint.iacr.org/2024/740}
}
Note: In order to protect the privacy of readers, eprint.iacr.org does not use cookies or embedded third party content.