Tc-PEDCKS: Towards time controlled public key encryption with delegatable conjunctive keyword search for Internet of Things

With the widespread adoption of Internet of Things (IoT) and cloud computing, more and more individuals and organizations are outsourcing their IoT data in the cloud server. Under these circumstances, how to protect the privacy and security of the outsourced data becomes a key challenge. Public key encryption with keyword search (PEKS) is a promising technology to solve the problem. In this paper, we present a new kind of PEKS named time controlled public key encryption with delegated conjunctive keyword search (tc-PEDCKS) for IoT deployment. A basic tc-PEDCKS is firstly presented which supports conjunctive keyword search and enables a data user to delegate access right over the data to others in a limited time period. To resist against the keyword guessing attacks, a more secure tc-PEDCKS with designated server construction is also presented. The two constructions are proved secure in the random oracle model. The performance evaluation and experimental results demonstrate that our constructions are practical and feasible for real world IoT scenarios.