中文摘要：

E-mail： sysutianhb@gmail.com Haibo Tian got his PhD （2006） in Cryptography from Xidian University, China. Currently, he works at Sun Yat- Sen University as a lecture. His research interests include cryptographic protocols and schemes. He has published over 30 research papers in refereed international conferences and journals. Jin Li received his BS （2002） in Mathematics from Southwest University, China. He got his PhD in information security from Sun Yat-sen University in 2007. Currently, he works at Guangzhou University as a professor. He has been selected as one of science and technology new star in Guangdong province. His research interests include applied cryptography and security in cloud computing. He has published over 50 research papers in refereed international conferences and journals and has served as the program chair or program committee member in many international conferences.