XUE Qingshui was born in Shandong Province, China, in 1971. He received his BS degree in computer science and technology in Shandong Normal University and Master degree in computer application from Shandong University, China in 1995 and 2000, respectively. His research interests include network security and cryptography, l-le is now a doctoral candidate in the Department of Computer Science and Engineering, Shanghai Jiaotong University and associate professor in Shandong P.E. Institute. Email: xue-qsh@cs.sjtu.edu.cn. Tel: 86-21-62932951. CAO Zhenfu was born in Jiangsu Province, China, in 1962. He received his BS in computer science and technology from the Harbin Institute of Technology, China in 1983, Ph.D. in mathematics from the same university. Since 1987 and 1991, he has been associatc professor and professor respectively. Main research areas are number theory and modern cryptography, theory and technology of information security, etc. Since 2000, he has been granted to become the doctoral supervisor. In 2002, he came to Shanghai and worked at Shanghai Jiaotong University, Email: zfcao@cs.sjtu.edu .cn.