Paper 2025/290

Dynamic Decentralized Functional Encryption: Generic Constructions with Strong Security

Ky Nguyen, DIENS, École normale supérieure, CNRS, Inria, PSL University
David Pointcheval, DIENS, École normale supérieure, CNRS, Inria, PSL University, Cosmian
Robert Schädlich, DIENS, École normale supérieure, CNRS, Inria, PSL University
Abstract

Dynamic Decentralized Functional Encryption (DDFE) is a generalization of Functional Encryption which allows multiple users to join the system dynamically without interaction and without relying on a trusted third party. Users can independently encrypt their inputs for a joint evaluation under functions embedded in functional decryption keys; and they keep control on these functions as they all have to contribute to the generation of the functional keys. In this work, we present new generic compilers which, when instantiated with existing schemes from the literature, improve over the state-of-the-art in terms of security, computational assumptions and functionality. Specifically, we obtain the first adaptively secure DDFE schemes for inner products in both the standard and the stronger function-hiding setting which guarantees privacy not only for messages but also for the evaluated functions. Furthermore, we present the first DDFE for inner products whose security can be proven under the LWE assumption in the standard model. Finally, we give the first construction of a DDFE for the attribute-weighted sums functionality with attribute-based access control (with some limitations). All prior constructions guarantee only selective security, rely on group-based assumptions on pairings, and cannot provide access control.

Metadata
Available format(s)
PDF
Category
Public-key cryptography
Publication info
A major revision of an IACR publication in PKC 2025
Keywords
Functional EncryptionAdaptive SecurityFunction-HidingInner ProductAttribute-Weighted Sum
Contact author(s)
ky nguyen @ ens psl eu
david pointcheval @ ens fr
robert schaedlich @ ens fr
History
2025-02-20: approved
2025-02-19: received
See all versions
Short URL
https://ia.cr/2025/290
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2025/290,
      author = {Ky Nguyen and David Pointcheval and Robert Schädlich},
      title = {Dynamic Decentralized Functional Encryption: Generic Constructions with Strong Security},
      howpublished = {Cryptology {ePrint} Archive, Paper 2025/290},
      year = {2025},
      url = {https://eprint.iacr.org/2025/290}
}
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