1. Fujian Provincial Key Laboratory of Network Security and Cryptology, College of Computer and Cyber Security, Fujian Normal University, Fuzhou, China
2. Department of Computer Science, Virginia Commonwealth University, Richmond, VA, USA
3. College of Computer and Data Science, Fuzhou University, Fuzhou, China
4. State Key Laboratory of Public Big Data, College of Big Data and Information Engineering, Guizhou University, Guiyang, China
5. Department of Informatics, University of Oslo, Oslo, Norway