LIU Xuchong, WANG Jianxin1, LUO Yong
(1. School of Information Science and Engineering, Central South Univ, Changsha, Hunan410083, China; 2Network Security and Technical Surveillance Corps, Hunan Provincial Public Security Office, Changsha, Hunan410001,China;3. College of Science, National Univ of Defense Technology, Changsha, Hunan410073, China)