1. Key Laboratory for Ubiquitous Network and Service Software of Liaoning Province, School of Software, Dalian University of Technology, Dalian, Liaoning, China
2. Department of Computer Science, City University of Hong Kong, Hong Kong
3. Physical Sciences and Engineering College, Cardiff University, Cardiff, U.K.
4. Hubei Key Laboratory of Distributed System Security, Hubei Engineering Research Center on Big Data Security, School of Cyber Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, China
5. Department of Computer Science, Sichuan University, Chengdu, Sichuan, China
6. Ningxia Research Institute, China Coal Research Institute, Beijing, China
7. Key Laboratory for Ubiquitous Network and Service Software of Liaoning Province, the International School of Information Science & Engineering, Dalian University of Technology, Dalian, Liaoning, China