Paper 2013/330

Trapdoor Privacy in Asymmetric Searchable Encryption Schemes

Afonso Arriaga, Qiang Tang, and Peter Ryan


Asymmetric searchable encryption allows searches to be carried over ciphertexts, through delegation, and by means of trapdoors issued by the owner of the data. Public Key Encryption with Keyword Search (PEKS) is a primitive with such functionality that provides delegation of exact-match searches. As it is important that ciphertexts preserve data privacy, it is also important that trapdoors do not expose the user's search criteria. The difficulty of formalizing a security model for trapdoor privacy lies in the verification functionality, which gives the adversary the power of verifying if a trapdoor encodes a particular keyword. In this paper, we provide a broader view on what can be achieved regarding trapdoor privacy in asymmetric searchable encryption schemes, and bridge the gap between previous definitions, which give limited privacy guarantees in practice against search patterns. We propose the notion of Strong Search Pattern Privacy for PEKS and construct a scheme that achieves this security notion.

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Publication info
Published elsewhere. Minor revision. AFRICACRYPT '14. This is the full version.
Asymmetric Searchable EncryptionPEKSTrapdoor PrivacyAnonymous IBEFunction PrivacyPredicate PrivacySearch Pattern PrivacyKey Unlinkability.
Contact author(s)
afonso delerue @ uni lu
2014-03-24: last of 2 revisions
2013-06-02: received
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      author = {Afonso Arriaga and Qiang Tang and Peter Ryan},
      title = {Trapdoor Privacy in Asymmetric Searchable Encryption Schemes},
      howpublished = {Cryptology ePrint Archive, Paper 2013/330},
      year = {2013},
      note = {\url{}},
      url = {}
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