1. Department of Management, Beijing Electronic Science & Technology Institute, Beijing, People’s Republic of China
2. Information Security Center, State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, Beijing, People’s Republic of China.
3. School of Information Science and Technology, University of Science and Technology of China, Hefei, People’s Republic of China
4. Department of Cyberspace Security, Beijing Electronic Science & Technology Institute, Beijing, People’s Republic of China