1. Institute of Computing Science and Technology, Guangzhou University, Guangzhou, China
2. School of Information Science and Engineering, Chengdu University, Chengdu, China
3. School of Information Science and Engineering, Lanzhou University, Lanzhou, China
4. College of Mathematics and Informatics, Fujian Normal University, Fujian Provincial Key Laboratory of Network Security and Cryptology, Fujian Network & Information Security Industry Technology Development Base, Fuzhou, China
5. Center for Cyber Security, University of Electronic Science and Technology of China, Chengdu, China