1. School of Computer Science, Shaanxi Normal University, Xi'an, China
2. School of Computer Science, State Key Laboratory of Cryptology, Shaanxi Normal University, Xi'an, China
3. Xi'an Aeronautics Computing Technique Research Institute, Aviation Industry Corporation of China, Xi'an, China
4. School of Computer Science and Technology, Wuhan University of Technology, Wuhan, China
5. School of Computer Science, Hubei University Of Technology, Wuhan, China