Abstract
To support offline, privacy-preserving, contact-based discovery (that does not reveal the user’s contacts to nearby devices), a cryptographic protocol is needed that allows sending and receiving devices to share their encrypted identifiers and/or address books without revealing private information. This sharing needs to be implemented in a manner that avoids various types of attacks. Sharing the identifiers in a specific order is critical to avoiding certain types of attacks that may compromise user privacy. This disclosure describes a cryptographic protocol developed using signatures and private set intersection (PSI) that enables privacy-preserving, contact-based discovery. The cryptographic techniques utilize a federated identity model by the use of a probabilistic identity filter behind attested secure channels. The techniques utilize private set intersection (PSI) for mutual identification. The techniques are implemented using certificates provided by trusted identity providers that can be trusted by sender and receiver devices participating in contact-based discovery.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Yeo, Kevin; Krahn, Darren; Seo, Joon Young; and McCloskey, Dave, "Private Set Intersection for Offline, Privacy-Preserving, Contact-Based Nearby Device Discovery", Technical Disclosure Commons, (October 23, 2025)
https://www.tdcommons.org/dpubs_series/8773