Multi-user search on the encrypted multimedia database: lattice-based searchable encryption scheme with time-controlled proxy re-encryption

Multimedia cloud storage which saves the huge storage overhead of local devices has attracted considerable attention. However, due to the lack of physical control of data, the privacy protection of data on the multimedia cloud has become one of the main concerns of users. Public-key encryption with keywords search (PEKS) is a technique that can keep the privacy and searchability of data in the cloud. In this paper, we present a PEKS with time-controlled proxy re-encryption model which allows the data owner to delegate the access right of the encrypted multimedia database to other users, to achieve the time-controlled multi-user search. Furthermore, it is designed to resist keywords guessing attack and support conjunctive keywords search. Compared with previous works which require a time server to generate a time seal for the generation of the search token, this model embeds the time information of accessing the encrypted database into public and secret key pairs of data users, which saves the managing overhead and reduces the security risks resulting from an extra server. In addition, most existing PEKS schemes were constructed based on the hardness of classical mathematical problems which can be broken by quantum computers. To address this issue, a lattice-based PEKS scheme based on the above model is proposed, which can be considered as the candidate for protecting multimedia data security in the quantum era.