Paper 2022/1693

More Efficient Adaptively Secure Lattice-based IBE with Equality Test in the Standard Model

Kyoichi Asano
Keita Emura
Atsushi Takayasu

Identity-based encryption with equality test (IBEET) is a variant of identity-based encryption (IBE), where any users who have trapdoors can check whether two ciphertexts are encryption of the same plaintext. Although several lattice-based IBEET schemes have been proposed, they have drawbacks in either security or efficiency. Specifically, most schemes satisfy only selective security, while adaptively secure schemes in the standard model suffer from large master public keys that consist of linear numbers of matrices. In other words, known lattice-based IBEET schemes perform poorly compared to the state-of-the-art lattice-based IBE schemes (without equality test). In this paper, we propose a semi-generic construction of CCA-secure lattice-based IBEET from a certain class of lattice-based IBE schemes. As a result, we obtain the first lattice-based IBEET schemes with adaptive security and CCA security in the standard model. Furthermore, our semi-generic construction can use several state-of-the-art lattice-based IBE schemes as underlying schemes. Then, we have adaptively secure lattice-based IBEET schemes whose public keys have only poly-log matrices.

Available format(s)
Public-key cryptography
Publication info
Published elsewhere. ISC 2022
identity-based encryption equality test adaptive security chosen-ciphertext security
Contact author(s)
k asano @ uec ac jp
k-emura @ nict go jp
takayasu-a @ g ecc u-tokyo ac jp
2022-12-10: approved
2022-12-07: received
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      author = {Kyoichi Asano and Keita Emura and Atsushi Takayasu},
      title = {More Efficient Adaptively Secure Lattice-based IBE with Equality Test in the Standard Model},
      howpublished = {Cryptology ePrint Archive, Paper 2022/1693},
      year = {2022},
      note = {\url{}},
      url = {}
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