Paper 2025/1805
DDH-based schemes for multi-party Function Secret Sharing
, University of Twente, French Institute for Research in Computer Science and Automation, University of Twente, Carl von Ossietzky Universität OldenburgAbstract
Function Secret Sharing (FSS) schemes enable sharing efficiently secret functions. Schemes dedicated to point functions, referred to as Distributed Point Functions (DPFs), are the center of FSS literature thanks to their numerous applications including private information retrieval, anonymous communications, and machine learning. While two-party DPFs benefit from schemes with logarithmic key sizes, multi-party DPFs have seen limited advancements: $O(\sqrt{N})$ key sizes (with $N$, the function domain size) and/or exponential factors in the key size. We propose a DDH-based technique reducing the key size of existing multi-party schemes. In particular, we build an honest-majority DPF with $O(\sqrt[3]{N})$ key size. Our benchmark highlights key sizes up to $10\times$ smaller (on realistic problem sizes) than state-of-the-art schemes. Finally, we extend our technique to schemes supporting comparison functions.
Metadata
- Available format(s)
-
PDF
- Category
- Cryptographic protocols
- Publication info
- Published elsewhere. NordSec 2025
- Keywords
- Function Secret SharingFSSDistributed Point FunctionDPFDDHMulti-Party Computations
- Contact author(s)
- m f d damie @ utwente nl
- History
- 2025-10-08: approved
- 2025-10-02: received
- See all versions
- Short URL
- https://ia.cr/2025/1805
- License
-
CC BY-NC-SA
BibTeX
@misc{cryptoeprint:2025/1805,
author = {Marc Damie and Florian Hahn and Andreas Peter and Jan Ramon},
title = {{DDH}-based schemes for multi-party Function Secret Sharing},
howpublished = {Cryptology {ePrint} Archive, Paper 2025/1805},
year = {2025},
url = {https://eprint.iacr.org/2025/1805}
}
