1. Information Security Center, State Key Laboratory of Networking and Switching Technology, and National Engineering Laboratory for Disaster Backup and Recovery, Beijing University of Posts and Telecommunications, Beijing, China
2. Computer Science and Engineering Department, Santa Clara University, Santa Clara, CA, USA
3. Shandong Provincial Key Laboratory of Computer Networks, Shandong Computer Science Center (National Supercomputer Center in Jinan), Qilu University of Technology (Shandong Academy of Sciences), Jinan, China