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Scaling Mobile Private Contact Discovery to Billions of Users

Hetz, Laura ; Schneider, Thomas ; Weinert, Christian (2023)
Scaling Mobile Private Contact Discovery to Billions of Users.
28th European Symposium on Research in Computer Security (ESORICS'23). The Hague, The Netherlands (25.09.2023 – 29.09.2023)
doi: 10.1007/978-3-031-50594-2_23
Konferenzveröffentlichung, Bibliographie

Kurzbeschreibung (Abstract)

Mobile contact discovery is a convenience feature of messengers such as WhatsApp or Telegram that helps users to identify which of their existing contacts are registered with the service. Unfortunately, the contact discovery implementation of many popular messengers massively violates the users' privacy as demonstrated by Hagen et al. (NDSS'21, ACM TOPS'23). Unbalanced private set intersection (PSI) protocols are a promising cryptographic solution to realize mobile private contact discovery, however, state-of-the-art protocols do not scale to real-world database sizes with billions of registered users in terms of communication and/or computation overhead. In our work, we make significant steps towards truly practical large-scale mobile private contact discovery. For this, we combine and substantially optimize the unbalanced PSI protocol of Kales et al. (USENIX Security'19) and the private information retrieval (PIR) protocol of Kogan and Corrigan-Gibbs (USENIX Security'21). Our resulting protocol has a total communication overhead that is sublinear in the size of the servers user database and also has sublinear online runtimes. We optimize our protocol by introducing database partitioning and efficient scheduling of user queries. To handle realistic change rates of databases and contact lists, we propose and evaluate different possibilities for efficient updates. We implement our protocol on smartphones and measure online runtimes of less than 2 s to query up to 1024 contacts from a database with more than two billion entries. Furthermore, we achieve a reduction in setup communication up to factor 32 × compared to state-of-the-art mobile private contact discovery protocols.

Typ des Eintrags: Konferenzveröffentlichung
Erschienen: 2023
Autor(en): Hetz, Laura ; Schneider, Thomas ; Weinert, Christian
Art des Eintrags: Bibliographie
Titel: Scaling Mobile Private Contact Discovery to Billions of Users
Sprache: Englisch
Publikationsjahr: September 2023
Ort: Cham
Verlag: Springer
Buchtitel: Computer Security - ESORICS 2023
Reihe: Lecture Notes in Computer Science
Band einer Reihe: 14344
Veranstaltungstitel: 28th European Symposium on Research in Computer Security (ESORICS'23)
Veranstaltungsort: The Hague, The Netherlands
Veranstaltungsdatum: 25.09.2023 – 29.09.2023
Auflage: 1. Edt.
DOI: 10.1007/978-3-031-50594-2_23
URL / URN: https://doi.org/10.1007/978-3-031-50594-2_23
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Kurzbeschreibung (Abstract):

Mobile contact discovery is a convenience feature of messengers such as WhatsApp or Telegram that helps users to identify which of their existing contacts are registered with the service. Unfortunately, the contact discovery implementation of many popular messengers massively violates the users' privacy as demonstrated by Hagen et al. (NDSS'21, ACM TOPS'23). Unbalanced private set intersection (PSI) protocols are a promising cryptographic solution to realize mobile private contact discovery, however, state-of-the-art protocols do not scale to real-world database sizes with billions of registered users in terms of communication and/or computation overhead. In our work, we make significant steps towards truly practical large-scale mobile private contact discovery. For this, we combine and substantially optimize the unbalanced PSI protocol of Kales et al. (USENIX Security'19) and the private information retrieval (PIR) protocol of Kogan and Corrigan-Gibbs (USENIX Security'21). Our resulting protocol has a total communication overhead that is sublinear in the size of the servers user database and also has sublinear online runtimes. We optimize our protocol by introducing database partitioning and efficient scheduling of user queries. To handle realistic change rates of databases and contact lists, we propose and evaluate different possibilities for efficient updates. We implement our protocol on smartphones and measure online runtimes of less than 2 s to query up to 1024 contacts from a database with more than two billion entries. Furthermore, we achieve a reduction in setup communication up to factor 32 × compared to state-of-the-art mobile private contact discovery protocols.

Fachbereich(e)/-gebiet(e): 20 Fachbereich Informatik
20 Fachbereich Informatik > Praktische Kryptographie und Privatheit
DFG-Sonderforschungsbereiche (inkl. Transregio)
DFG-Sonderforschungsbereiche (inkl. Transregio) > Sonderforschungsbereiche
DFG-Graduiertenkollegs
DFG-Graduiertenkollegs > Graduiertenkolleg 2050 Privacy and Trust for Mobile Users
DFG-Sonderforschungsbereiche (inkl. Transregio) > Sonderforschungsbereiche > SFB 1119: CROSSING – Kryptographiebasierte Sicherheitslösungen als Grundlage für Vertrauen in heutigen und zukünftigen IT-Systemen
Hinterlegungsdatum: 25 Jul 2024 07:56
Letzte Änderung: 07 Nov 2024 08:28
PPN: 523288557
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