State Key Laboratory of Networking and Switching Technology;
Beijing University of Posts and Telecommunications;
Beijing 100876;
China;
Information Security Center;
Beijing University of Posts and Telecommunications;
Beijing 100876;
China;
National Engineering Laboratory for Disaster Backup and Recovery;
Beijing 100876;
China;
Nanjing University of Information Science & Technology (NUIST);
Nanjing 210044;
China;