The Design And Implementation Of Digital Document Privilege Management System Based On Usbkey

The pace of networked office is enhanced by the rapid development and widely being used of the Internet. In the recent years, the situation of people handling digital sensitive docoument in the enterprise by using computers is becoming more and more frequently. Therefore, protecting the information and data of the enterprise during the business development is becoming one of the most important missions.On such a background, the thesis introduces the current research situation of the technique of digital document protection, finding the shortage of each protecting method by comparation. And then, on the base of this beginning point, the thesis analyzes, designs and implements an advanced digital document privilege management system.Encryption must be used for document protection. On the consequence of this, the thesis firstly does research on encryption technique, public key infrastructure and CryptoAPI. Moreover, considering the insecurity of the key management method of the current digital document protection, this thesis designs a public key encryption method based on USBKey, and a method of managing keys and privileges by using local database. At last, thread synchronization technique will be discussed which will be used to make keys and privileges synchronized via the server. With all of the techniques talked above, the disadvantage of key management and not supporting offline in other similar document protecting methods will be diminished.On the base of this, the thesis uses the the thoughts of software engineering in order to implement a digital document privilege management system, and focuses on the upper application of the client of the whole system, includes:1. Analyze the system that to be implemented. First, user demands will be analyzed and separated into different modules for the sake of getting the skelinton of the system. And then, the thesis enhances the demands of handling error, proformance, start and exit method. Futhermore, the techniques which will be used during the implementation will be analyzed and compared one by one in order to help choosing the most suitable method to build the whole system.2. Design the system on the base of system analyzing, including designing the skelinton of the whole system, the physical storage of the local database, and also the digital design of the upper application modules of the client.3. Implement the user interface, the local database accessing module, the synchronization module and crypting and decrypting module of the client.4. Do recovery testing, security testing, stress testing and proformance testing on the client of the whole system.The advantage of this system is that encryption and decryption are all depended on USBKey which can complete encryption and decryption inside. It is much safer compared with usual public encryption method. On apart of this, encrypted files can be used without depending on any other specific reading software. Furthermore, offline using is supported by the system implemented by this thesis, making up the disadvantage of other usual document protecting systems which can not support offline using. This system can work well even the network shutdowns unexpectively.In practical applications, this system can effectively reinforce the security of digital document inside the enterprise, protect the security of the process of transporing and using, and control the privilege of the digital doument.