The Research Of Vector CAD Electronic Drawing Protection System

With rapid development of internet and communication technology, electronic commerce and electronic government affairs have become very important aspects in our daily life. CAD electronic drawing is a technique revolution in the software industry. It has brought engineering drawing into the era of personal computers. CAD has become an especially important technology, with benefits such as lower product development costs and a greatly shortened design cycle. CAD enables designers to develop work on screen, print it out and save it for future editing, saving time on their drawings.The existence of CAD electronic drawings also brings security concerns. As a critical part of electronic documents, electronic drawing is playing more and more important role in the field of information security. The context in the electronic drawing normally contains detailed information of a product. It is also used throughout the engineering process from conceptual design and layout of products. Once the information in the electronic drawing reveals to other competitors, it can lead to serious economy losses. Recent years, the unauthorized distribution of top-secret electronic documents has turned from attackers to the inside-job. How to prevent this has become a significant issue for companies and government departments. After investigated previous study of the protection of electronic drawings, this thesis has done several extensive researches on the protection of AutoCAD electronic drawings.In the first part of this thesis, we introduce the technique foundation that can be used to develop CAD electronic drawing protection system. According to the great demand of protection for electronic drawings, this thesis focuses on the development and customization of AutoCAD, one of the mainstream CAD software with billions of customers. Then, we analyze two major AutoCAD document types: DWG and DXF. After comparing several customization and development tools for AutoCAD, we choose ObjectARX as the major development environment. Afterwards, we introduce key techniques of integration and customization under AutoCAD.Then, this thesis proposed a design scheme of CAD electronic drawing protection system. According to the demands of electronic drawing protection system, we present different functional elements this scheme. In this thesis, we elaborate the detailed implementation of the system. We also give a short introduction about security techniques that used in this system. Two important elements of this scheme, disorder and recovery, and electronic seals, can at certain extent solve the problem of inside disclosure. It also can be integrated into AutoCAD as plug-in software. Electronic seals module can effectively solve the problem that is unique to China.In the end, this thesis presents several information hiding methods that can be used in the electronic protection system. We studied the features of CAD vector drawings and proposed three different kinds of time-space domain information hiding methods, which can be used for vector CAD drawings. After conduct Discrete Walsh Transform, one of the integer transform, this thesis further introduces a transform domain information hiding method that can also be used for vector CAD drawings. These methods can be effectively applied to the protection of vector CAD images. These methods also have practical applications in the electronic seal module.