1. Department of Computer Science, City University of Hong Kong, Hong Kong, Hong Kong
2. Xi'an Jiaotong University, Xi'an, Shaanxi, China
3. Department of Computer Science, George Mason University, Fairfax, Virginia, USA
4. Department of Computer Science and Engineering, The Ohio State University, Columbus, Ohio, USA
5. DBAPPSecurity Co., Ltd, Hangzhou, Zhejiang, China
6. Department of Computing, The Hong Kong Polytechnic University, Hong Kong, Hong Kong