Multi-user certificateless public key encryption with conjunctive keyword search for cloud-based telemedicine

With the development of communication and information technologies, the telemedicine system has infiltrated many aspects of medicine field. It allows doctors to simultaneously diagnose patients in different areas, which provides great convenience to people. However, the increasing medical data brings serious challenges to people, such as data storage and processing. To reduce data management costs and enjoy convenient services, more and more individuals and medical institutions prefer to store data in the cloud. Recently, many public key encryption with keyword search (PEKS) schemes have been designed to address the security and privacy of the outsourced data. However, most of the existing schemes support only single-keyword search, and cannot suitable for multi-user environment. To resolve these issues, we construct a certificateless public key encryption with conjunctive keyword search scheme for multi-user system (mCLPECK), in which the same data only needs to be encrypted once and can be searched by multi-receiver. At the same time, the mCLPECK scheme supports multi-keyword search. Furthermore, we show the proposed scheme can resist chosen keyword attacks, and has lower storage and computation overhead compared to other related schemes.