Fast Keyword Search Using Public-Key Ciphertexts With Hidden Structures

Searchable Public-Key Ciphertexts with Hidden Structures for keyword search is as fast as possible without sacrificing semantic security of the encrypted keywords. In SPCHS, all keyword-searchable ciphertexts are structured by hidden relations, and with the search trapdoor corresponding to a keyword, the minimum information of the relations is disclosed to a search algorithm as the guidance to find all matching ciphertexts efficiently. Construct a SPCHS scheme from scratch in which the ciphertexts have a hidden star-like structure. The scheme is to be semantically secure in the Random Oracle model. The search complexity of is dependent on the actual number of the ciphertexts containing the queried keyword, rather than the number of all ciphertexts. SPCHS construct from anonymous identity-based encryption and collision-free full-identity malleable Identity-Based Key Encapsulation Mechanism with anonymity. Two collision-free full-identity malleable IBKEM instances are semantically secure and anonymous, respectively, in the RO and standard models. The latter instance enables us to construct an SPCHS scheme with semantic security in the standard model.