Guo Wangmei, received the B.S. degree in information secure from Xidian University, Xi'an, China in 2006. Now she is a Master-Doctor combined program graduate student in class of 2006. Her research interests are convolutional network coding and its applications. Email: wangmeiguo@mail.xidian.edu.cn Cai Ning, received the B.S. degree in mathematics from the Normal College of Beijing, Beijing, China in 1982, the M.S. degree in mathematics from Academia Sinica, Beijing, China, in 1984, and the Ph. D. degree in mathematics from the University of Bielefeld, Bielefeld, Germany, in 1988. During 1984-1986, he worked in the Institute of Systems Sciences, Academia Sinica, Beijing, China. From 1989 to 2006, he was a Miss. Mitarbeiter in the Department of Mathematics, the University of Bielefeld, Gerrrany. Since 2006, he is a professor in the State Key Lab. of ISN, Xidian University, China. Prof. Cai is one of the initiators of network coding. He is a recipient of the 2005 IEEF. Information Theory Society Paper Award. His research interests include information theory, combinatorics, network coding and their applications. Email: caining@mail.xidian.edu.cn Wang Xiao, received the B.S. and M.S. degrees in mathematics from Xidian University, Xl'an, China in 2005 and 2008, respectively. Now he is a Doctor undergraduate student in class of spring in 2008. His research interests are secure network coding and its applications. Email:wangxiaoxiao@mail.xidian.edu.cn