DDH-based schemes for multi-party Function Secret Sharing

Computer Science > Cryptography and Security [Submitted on 18 Mar 2026] DDH-based schemes for multi-party Function Secret Sharing Marc Damie, Florian Hahn, Andreas Peter, Jan Ramon 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. Comments: Published in NordSec 2025 Subjects: Cryptography and Security (cs.CR) Cite as: arXiv:2603.17453 [cs.CR]   (or arXiv:2603.17453v1 [cs.CR] for this version)   https://doi.org/10.48550/arXiv.2603.17453 Focus to learn more Submission history From: Marc Damie [view email] [v1] Wed, 18 Mar 2026 07:48:19 UTC (456 KB) Access Paper: HTML (experimental) view license Current browse context: cs.CR < prev   |   next > new | recent | 2026-03 Change to browse by: cs References & Citations NASA ADS Google Scholar Semantic Scholar Export BibTeX Citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Demos Related Papers About arXivLabs Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)