作者机构:[1]Faculty of Mathematics and Computer Science, Hubei University, Wuhan 430062, Hubei, China, [2]State Key Laboratory of Information Security/Graduate University of Chinese Academy of Sciences, Beijing 100049, China
相关基金:Supported by the National Natural Science Foundation of China (60573053 , 60603012) and the Specialized Research Fund for the Doctoral Program of Higher Education of China (200505 12002)