1. School of Computer Science and Technology, Zhejiang Gongshang University, Hangzhou, China
2. Department of New Networks, Peng Cheng Laboratory, Shenzhen, China
3. School of Mathematics and Statistics and the Fujian Provincial Key Laboratory of Network Security and Cryptology, Fujian Normal University, Fuzhou, China
4. School of Computer Science, South China Normal University, Guangzhou, China