Affiliation: | 1. Information Security Center, State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, P.O. Box 145, Beijing 100876, China;2. National Engineering Laboratory for Disaster Backup and Recovery, Beijing University of Posts and Telecommunications, Beijing 100876, China;3. Shandong Provincial Key Laboratory of Computer Network, Shandong Computer Science Center, Jinan 250014, China |