Paper 2020/1599

Function Secret Sharing for PSI-CA: With Applications to Private Contact Tracing

Samuel Dittmer, Yuval Ishai, Steve Lu, Rafail Ostrovsky, Mohamed Elsabagh, Nikolaos Kiourtis, Brian Schulte, and Angelos Stavrou


In this work we describe a token-based solution to Contact Tracing via Distributed Point Functions (DPF) and, more generally, Function Secret Sharing (FSS). The key idea behind the solution is that FSS natively supports secure keyword search on raw sets of keywords without a need for processing the keyword sets via a data structure for set membership. Furthermore, the FSS functionality enables adding up numerical payloads associated with multiple matches without additional interaction. These features make FSS an attractive tool for lightweight privacy-preserving searching on a database of tokens belonging to infected individuals.

Available format(s)
Cryptographic protocols
Publication info
Preprint. MINOR revision.
Private Set IntersectionContact TracingFunction Secret SharingPrivate Aggregation
Contact author(s)
steve @ stealthsoftwareinc com
2020-12-24: received
Short URL
Creative Commons Attribution


      author = {Samuel Dittmer and Yuval Ishai and Steve Lu and Rafail Ostrovsky and Mohamed Elsabagh and Nikolaos Kiourtis and Brian Schulte and Angelos Stavrou},
      title = {Function Secret Sharing for PSI-CA: With Applications to Private Contact Tracing},
      howpublished = {Cryptology ePrint Archive, Paper 2020/1599},
      year = {2020},
      note = {\url{}},
      url = {}
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