1. School of Information Systems, Singapore Management University, Singapore. E-mails: ygtian@smu.edu.sg, yjli@smu.edu.sg, yinghuizhang@smu.edu.sg
2. School of Computing and Information Technology, University of Wollongong, NSW, Australia. E-mails: gyang@uow.edu.au, wsusilo@uow.edu.au
3. Fujian Provincial Key Laboratory of Network Security and Cryptology, College of Mathematics and Informatics, Fujian Normal University, Fuzhou, China. E-mail: ymu.ieee@gmail.com
4. Computer Science and Software Engineering, RMIT University, Victoria, Australia. E-mail: hui.cui@rmit.edu.au