[1] Fudan Univ, Sch Comp Sci, Shanghai 200438, Peoples R China
[2] Yunnan Univ, Sch Informat Sci & Engn, Kunming 650504, Peoples R China
[3] Fudan Univ, Inst Fintech, Shanghai 200438, Peoples R China
[4] Minist Educ, Engn Res Ctr Cyber Secur Auditing & Monitoring, Shanghai 200438, Peoples R China