1. Institute for Network Sciences and Cyberspace and Beijing National Research Center for Information Science and Technology, Tsinghua University, Beijing, China
2. Institute of Software, Chinese Academy of Sciences, Beijing, China
3. Center for Secure Information Systems, George Mason University, Fairfax, VA, USA
4. Institute of Cyber Security Research, Zhejiang University, Hangzhou, China
5. Department of Computer Science, Florida State University, Tallahassee, FL, USA