1. Department of Computer and Network Engineering, The University of Electro-Communications (UEC), 1-5-1 Chofugaoka, Tokyo 182-8585, Japan
2. Faculty of Computer Science and Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet St., Dist. 10, Ho Chi Minh City 740050, Vietnam
3. Advanced Original Technologies Co., Ltd., Academy of Cryptography Techniques, Chiba 277-0827, Japan