1. Shaanxi Key Laboratory of Network and System Security, School of Computer Science and Technology, Xidian University, Xi’an, China
2. College of Mathematics and Computer Science/College of Software, Fuzhou University, Fuzhou, China
3. Department of Information Systems and Cyber Security, The University of Texas at San Antonio, San Antonio, TX, USA
4. Department of Electrical and Computer Engineering, The University of Texas at San Antonio, San Antonio, TX, USA