| With the increasing popularity of computer and the Internet, in e-government's networks and intranets, many documents are distributed and saved in the way of electronic documents. PDF has the following two advantages as a preferred electronic document format: First, this format is platform-independent; Second, it uses the industrial standard compression algorithms. However, electronic documents are easy to copy without any traces, which are likely to cause leakage of information and give a serious threat to information security. The methods of creating a convenient, efficient and safe strategy of protection, which are an urgently needed by a great many of enterprises, are the contents of this paper. Main thesis is as follows:(1)The physical structure of the PDF document as well as its principle and logical structure are analyzed. In order to protect the security of PDF document, the following two PDF encryption styles are discussed in detail: overall encryption and content-level encryption.(2)We analyze and research the Acrobat software and its plug-in technology, describe the characteristics and applications of plug-ins, a detail discussion of Acrobat PDF documents on the encryption and decryption process is involved as well as the encryption and decryption algorithms.(3)A deep study and the methods, procedures and the tasks of creating Acrobat plug-in in windows'environment are gave in the thesis.(4)Based on the needs of the PDF Digital Rights Management System, in which the decryption plug-in is designed. The functions of this system, including efficient process of the encryption of information, management of certification and authority, generation of the encryption keys are implemented by the plug-ins.PDF decryption plug-in designed in this thesis has been successfully applied the copyright protection management system of Anhui Electric Power Research Institute. The System is proved to be effective and reliable after six months of the trial run. |
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