Protect Software Using Watermarking Techniques

While piracy and compromise are exploding with the rapid development of software industry, an intractable matter that how to protect copyright and core of programs has arisen. In this paper, the crucial problems about software protection, especially copyright safeguards are solved by using technology of watermarking, tamper proofing, reverse engineering, dynamic analysis, together with the idea of information hiding. The research fields of concern include software security, digital watermark, cryptography, graph theory, algorithm design, software engineering and so on. the accomplished researches are as follows:Firstly, software protection technology is studied, including technology of information hiding, reverse engineering, tamper proofing, encryption& decryption, code obfuscation, software diversity and Java security.Secondly, a systematic research about the technology of static software watermark as well as dynamic graph software watermark is carried out, including watermark encoding, watermark embedding, watermark retrieval and watermark protection. Watermark topology of Radix-K circular linklist, PPCT (Planted Plane Cubic Tree) and improved PPCT are implemented. Theoretical research and experimental analysis are made in details about their usability, stealth and anti-attack capacity.Thirdly, a novel approach of tamperproof dynamic graph software watermark with multiple constant encoding is proposed. In this scheme, an idea of fake watermark is introduced to enhance the stealth and anti-attack capacity of dynamic graph watermark and secure software from sabotage. Meanwhile, a detailed analysis in theory is made concerning the principle, feasibility and merits of this approach.Fourthly, a prototype of watermark system JMark1.0 based on Java bytecode files is realized. The comprehensive system consists of static data software watermarking sub-system and dynamic graph software watermark sub-system,leaving some extensible interfaces to be perfected.Finally, a series of tests are made on the basis of the prototype system, analyzing the two sub-systems separately about their validity, robustness and performance overload caused by watermark embedding. Moreover, data rate of the three graph watermark structures in the system is analyzed in theory.