,
Ravi Kumar
,
Pasin Manurangsi
,
Serena Wang
Creative Commons Attribution 4.0 International license
We study differential privacy (DP) in a multi-party setting where each party only trusts a (known) subset of the other parties with its data. Specifically, given a trust graph where vertices correspond to parties and neighbors are mutually trusting, we give a DP algorithm for aggregation with a much better privacy-utility trade-off than in the well-studied local model of DP (where each party trusts no other party). We further study a robust variant where each party trusts all but an unknown subset of at most t of its neighbors (where t is a given parameter), and give an algorithm for this setting. We complement our algorithms with lower bounds, and discuss implications of our work to other tasks in private learning and analytics.
@InProceedings{ghazi_et_al:LIPIcs.ITCS.2025.53,
author = {Ghazi, Badih and Kumar, Ravi and Manurangsi, Pasin and Wang, Serena},
title = {{Differential Privacy on Trust Graphs}},
booktitle = {16th Innovations in Theoretical Computer Science Conference (ITCS 2025)},
pages = {53:1--53:23},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-361-4},
ISSN = {1868-8969},
year = {2025},
volume = {325},
editor = {Meka, Raghu},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITCS.2025.53},
URN = {urn:nbn:de:0030-drops-226816},
doi = {10.4230/LIPIcs.ITCS.2025.53},
annote = {Keywords: Differential privacy, trust graphs, minimum dominating set, packing number}
}