4Yu Xin,Wang Nan,Zhang Heyin.Design and developmentof PDF document protection system based on DRMtechnology. Proc of the 2nd Int Symp on KnowledgeAcquisition and Modeling (KAM 2009) . 2009
5Li Changxin,Wu Hongwei,Chen Shifeng,et al.Efficientimplementation for MD5-RC4encryption using GPU withCUDA. Proc of the 3rd Int Conf on Anti-Counterfeiting,Security,and Identification in Communication (2009ASID) . 2009
6Kanso,Ali A.Encryption System with Variable Number of Register-s. COMPUTERS & ELECTRICAL ENGINEERING . 2010
7Document management-Portable document format—Part1:PDF1.7. ISO 32000-1:2008 . 2008
