Paper 2020/1154

Functional Encryption for Set Intersection in the Multi-Client Setting

Kwangsu Lee and Minhye Seo

Abstract

Functional encryption for set intersection (FE-SI) in the multi-client environment is that each client $i$ encrypts a set $X_i$ associated with time $T$ by using its own encryption key and uploads it to a cloud server, and then the cloud server which receives a function key of the client indexes $i, j$ from a trusted center can compute the intersection $X_i \cap X_j$ of the two client ciphertexts. In this paper, we first newly define the concept of FE-SI suitable for the multi-client setting. Then, we propose an efficient FE-SI scheme in asymmetric bilinear groups and prove the static security of our scheme under newly introduced assumptions. In our FE-SI scheme, a ciphertext consists of $O(\ell)$ group elements, a function key consists of a single group element, and the decryption algorithm has $O(\ell^2)$ complexity where $\ell$ is the size of a set in the ciphertext. Next, we propose another FE-SI scheme with time-constrained keys that limits the ability of function keys to be valid only for a specified time period $T$, and proves the static security of our scheme. Finally, we prove that the two assumptions hold in the general group model to provide confidence in the two newly introduced assumptions.

Metadata
Available format(s)
PDF
Category
Public-key cryptography
Publication info
Published elsewhere. Designs, Codes and Cryptography
DOI
10.1007/s10623-021-00961-w
Keywords
Functional encryptionPrivate set intersectionMulti-client settingBilinear maps
Contact author(s)
kwangsu @ sejong ac kr
History
2021-11-02: revised
2020-09-25: received
See all versions
Short URL
https://ia.cr/2020/1154
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2020/1154,
      author = {Kwangsu Lee and Minhye Seo},
      title = {Functional Encryption for Set Intersection in the Multi-Client Setting},
      howpublished = {Cryptology ePrint Archive, Paper 2020/1154},
      year = {2020},
      doi = {10.1007/s10623-021-00961-w},
      note = {\url{https://eprint.iacr.org/2020/1154}},
      url = {https://eprint.iacr.org/2020/1154}
}
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