[Zhang, Xiao-Fei; Xu, Ting] Cent China Normal Univ, Sch Math & Stat, Wuhan 430079, Hubei, Peoples R China.
[Ou-Yang, Le] Shenzhen Univ, Coll Informat Engn, Shenzhen 518060, Peoples R China.
[Ou-Yang, Le] Shenzhen Univ, Shenzhen Key Lab Media Secur, Shenzhen 518060, Peoples R China.
[Hu, Xiaohua] Cent China Normal Univ, Sch Comp, Wuhan 430079, Hubei, Peoples R China.
[Hu, Xiaohua] Drexel Univ, Coll Comp & Informat, Philadelphia, PA 19104 USA.