中文摘要：

Wei Du received her B.S. degree in 2000 and M.S. degree in 2003, both in computer science from Faculty of Mathematics and Computer Science, Hubei University. She is currently a Ph.D. candidate in computer science in School of Computer Science and Technology, Huazhong University of Science and Technology and a lecture of computer science in College of Computer Science and Technology, Wuhan University of Technology. Her major research interests include distributed computing and information security. Guo-Hua Cui is currently a professor in School of Computer Science and Technology, Huazhong University of Science and Technology. He also led the Information Security and Confidence Research Laboratory, Huazhong University of Science and Technology. He has pub- lished more than 40 publications in journals and conferences on informa-tion security. His research interest is information security. Wei Liu received his B.S. degree in 1999 and M.S. degree in 2002, both in computer science from Faculty of Mathematics and Computer Science, Hubei University. He subsequently received his Ph.D. degree from School of Computer Science, Fudan University, in 2005. He is currently an associate professor of Cornmiter Science in College of Computer Science and Technology, Wuhan University of Technology. His research interests include parallel and distributed com- puting and information security. He is a member of China Computer Federation.