The Design And Realization Of Software Watermarking Scheme Based On Code Obfuscation

With the development of information technology, computer has become an indispensable part of the lives of the people. Computer software has become the main motive force. However, piracy is becoming increasingly serious, which caused by a number of enterprises and the attention of scholars. To solve the piracy problem,we should rely on legal means on the one hand, on the other hand, we should study and discuss how to use various technical method to the effective protection of software products, which has important practical significance for the prevention of piracy.The protection technologies of software divide into two types according to their product, one is pure software, another is based on the hardware, or the combination of the software and hardware. Because more and more software adopt similar way to distribute on line, software protection concentrates on the first mainly. And the first type concentrates on three fields mainly, such as obfuscation, encryption, and software watermark. The attack of the real world is many angles and multi-level. In order to enhance software protection, many people seek the methods which can better resist the static analysis, reverse engineering and tampering and other malicious attacks. It is an effective choice to combine a variety of software protection technologies.This paper studies the characteristics of the PE file format and the basic reverse engineering first. And then, it designs a kind of software protection scheme combined obfuscation with software watermark, utilizing the obfuscation to prevent the program from being compiled in reverse and the watermark to prove the real owner. The program which use integer factorization algorithm and list structure obfuscates the intermediate code files that are generated by the disassembly of the PE file. It can increase the degree of difficulty for attackers to reverse analysis of the intermediate code, which preventing the software is easy to decompile. In order to form a security rules for watermark information conversion, the program uses the thought of none-watermarking, which is applied to images, audio and other digital watermarking technology, and combines with the thought of program code-cuts. And the technical scheme uses junk instruction, which can strengthen the code obfuscation and ensure the robustness and invisibility of watermark to achieve the automatic watermark embedding and extraction.To test the actual effect, this paper has designed a prototype system, which consists of two parts obfuscation and watermark and reflects the program overview and basic ideas. The system of using the program of obfuscation and watermark can be running the same as before, and it is difficult to be decompiled or destroy the watermark. So it work out that the system is a practical and efficient tool, and the program is useful to explore to software protection technology.