University of Luton
Asymmetric searchable encryption allows searches to be carried over cipher-texts, 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 cipher-texts 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.