Liu Jianhua, received his M.S. degree of applied mathernatics in 2009 at China West Normal University. Now he is a Ph.D. candidate of communication and information system at Beihang University, China. His research interests include cryptography, network security, and basic theory and critical technology in electronic commerce. Email: ljh2583265@ 163.com Liu Jianwei, received his Ph.D. degree at Xidian University, China. He is currently a professor and doctoral supervisor of Electronics Infomation and Engineering College in Beihang University, China. His research interests include cryptography, net-work security and trusted computing. Email: liujianwei@ buaa edu.cn Qiu Xiufeng, received his M.S. degree of computer software theory in 2006 at Jiangxi Normal University, China. Now he is a Ph.D. candidate of communication and information system at Beihang University, China. His research interests include cryptography and network security. Email: 451272151@qq.com