1. College of Computer and Communication, Lanzhou University of Technology, Lanzhou, China
2. Fujian Provincial Key Laboratory of Network Security and Cryptology, College of Computer and Cyber Security, Fujian Normal University, Fuzhou, China
3. School of Computer Science, Nanjing University of Posts and Telecommunications, Nanjing, China
4. State Key Laboratory of Public Big Data, College of Computer Science and Technology, Guizhou University, Guiyang, China