1. Group of Analysis, Security and Systems (GASS) and Department of Software Engineering and Artificial Intelligence (DISIA), School of Computer Science, Office 431 Complutense University of Madrid (UCM), 28040 Madrid, Spain
2. Electrical Engineering Department, University of Brasilia, 70910-900 Brasilia, DF, Brazil
3. Department of Convergence Security, Sungshin Women's University, 249-1 Dongseon-dong 3-ga, Seoul 136-742, Republic of Korea