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

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.

Available format(s)
Public-key cryptography
Publication info
Functional EncryptionSecurity Notions
Contact author(s)
ky nguyen @ ens fr
hieu phan @ telecom-paris fr
david pointcheval @ ens fr
2024-05-16: approved
2024-05-15: received
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Creative Commons Attribution


      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},
      note = {\url{}},
      url = {}
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