作者机构:[1]Key Laboratory of Cryptologic Technology and Information Security of Ministry of Education, Shandong University, Ji'nan 250100, China, [2]Center for Advanced Study, Tsinghua University, Beijing 100084, China
相关基金:Supported by the National Key Basic Research and Development (973) Program of China (No. 2007CB807902) and the National Natural Science Foundation of China (Nos. 90604036 and 60525201)