[1] Xian Univ Posts & Telecommun, Natl Engn Lab Wireless Secur, Xian 710121, Shaanxi, Peoples R China
[2] Westone Cryptol Res Ctr, Beijing 100070, Peoples R China
[3] Xian Univ Posts & Telecommun, Sch Comp Sci & Technol, Xian 710121, Shaanxi, Peoples R China
[4] City Univ Hong Kong, Dept Comp Sci, Kowloon Tong, Hong Kong, Peoples R China