1. Department of Computer Science, Faculty of Computer Science and Information Technology; Universiti Putra Malaysia; Serdang Selangor 43400 Malaysia
2. The School of Computing, Science & Engineering, Newton Building; University of Salford; Salford, Greater Manchester M5 4WT UK
3. Department of Information Systems and Cyber Security; University of Texas at San Antonio; San Antonio TX 78249-0631 USA