1. Fujian Provincial Key Laboratory of Network Security and Cryptology, College of Computer and Cyber Security, Fujian Normal University, Fuzhou, China
2. State Key Laboratory of Public Big Data, College of Computer Science and Technology, Guizhou University, Guiyang, China
3. School of Computer Science, Nanjing University of Posts and Telecommunications, Nanjing, China
4. Department of Information Systems and Cyber Security, University of Texas at San Antonio, San Antonio, TX, USA