1. College of Communication Engineering, Chengdu University of Information Technology, Chengdu, China
2. Network and Data Security Key Lab. of Sichuan Pro., University of Electronic Science and Technology of China, Chengdu, China
3. School of Software, Chengdu Polytechnic, Chengdu, China
4. Educational Informationization and Big Data Center, Education Department of Sichuan Province, Chengdu, China