Paper 2023/435
Optimal Security Notion for Decentralized Multi-Client Functional Encryption
Abstract
Research on (Decentralized) Multi-Client Functional Encryption (or (D)MCFE) is very active, with interesting constructions, especially for the class of inner products. However, the security notions have been evolving over the time. While the target of the adversary in distinguishing ciphertexts is clear, legitimate scenarios that do not consist of trivial attacks on the functionality are less obvious. In this paper, we wonder whether only trivial attacks are excluded from previous security games. And, unfortunately, this was not the case. We then propose a stronger security notion, with a large definition of admissible attacks, and prove it is optimal: any extension of the set of admissible attacks is actually a trivial attack on the functionality, and not against the specific scheme. In addition, we show that all the previous constructions are insecure w.r.t. this new security notion. Eventually, we propose new DMCFE schemes for the class of inner products that provide the new features and achieve this stronger security notion.
Metadata
- Available format(s)
-
PDF
- Category
- Cryptographic protocols
- Publication info
- Published elsewhere. ACNS 2023
- Keywords
- Functional EncryptionCorruptionsSecurity Notions
- Contact author(s)
-
ky nguyen @ ens fr
hieu phan @ telecom-paris fr
david pointcheval @ ens fr - History
- 2023-03-27: approved
- 2023-03-24: received
- See all versions
- Short URL
- https://ia.cr/2023/435
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2023/435,
author = {Ky Nguyen and Duong Hieu Phan and David Pointcheval},
title = {Optimal Security Notion for Decentralized Multi-Client Functional Encryption},
howpublished = {Cryptology {ePrint} Archive, Paper 2023/435},
year = {2023},
url = {https://eprint.iacr.org/2023/435}
}
