Research Of Software Protection For Embedded System Based On EPPCT

With the growing popularity of embedded products, as the soul of the embedded systems, the embedded software is booming, and its industrial scale has been grown in strength. The application softwares based on embedded platforms are also increasingly diverse, and have become the most important part of embedded product value chain. However, the embedded application software piracy is becoming severe problem.Pirated use, reverse engineering, and tampering have posed a great threat to software industry. So the copyrights of embedded software has gradually get the focus of attention in recent years, a new kind of software copyright protection technology-software watermarking technology can be applied to protect the embedded software copyright as a powerful weapon. This technique is also becoming hot spot. of research,The thesis gives a summarizing introduction to software security and software protection techniques, and introduces software watermarking techinuque and its recent development deeply, and also explains its definition, classification, and methods of attacking. The static and dynamic software watermarking are compared and analysed. The dynamic graph software watermarking topology stucture, encodeing, algorithms, and protection measures were discussed emphastically. The embedded system architecture is gived an overview, according to the characteristics of the embedded environment, proposes a tamper-resistant software watermarking scheme. The accomplished researches are as follow.First of all, the thesis study the graph topology structure, data rate, coding, algorithm of dynamic graph software watermark in detail, and presents a modified EPPCT software watermarking graph topology structure, Analysis shows that, compare to PPCT, EPPCT is higher in data rate. To enhance the stealth of software watermarking, a novel approache through the Chinese Remainder Theorem, is applied to decompose watermark data into several sub-watermarks which are embedded into difference position of program.Secondly, in order to improve the tamper-proofing and enfore the difficulty of reverse engineering, a strategy which combines self-checking with code-blocks encrypting, is used to enhanced anti-attack performance of software watermarking. Considering the embedded system characteristics, a simple encryption algorithm is designed to protect the watermark, while minimizing overhead.Finally, based on environmental characteristics of embedded system, we design a software watermarking prototype system, and then conduct a series of test case on the system in terms of evaluation criteria. According to the results of experiments, respectively, from several aspects, such as validity, date rate, stealth, robustness, overload, we make an objective analysis of the software watermarking scheme.