Research On Software Watermarking And Interrelated Technique

As far as software watermarking interrelated technology is concerned, a chaos-based robust software watermarking is proposed firstly. And then a new software zero-watermarking based on software birthmark is presented by introducing image zero-watermarking into software watermarking. At last, a dynamic opcode n-gram set is introduced to extend the research on software birthmark employed in zero-watermarking. The main research conents and originality of this thesis can be summarized from three aspects in detail as follows:(1) To settle the existing limitations of software watermark algorithm from four aspects—"attack model supposed", "style of embedding", "position of embedding" and "utility of watermarking", a chaos-based software watermarking framework is proposed in this thesis, in which the anti-reverse engineering technique and chaotic system are combined with the idea of Easter Egg software watermarking. With the chaotic system, global protection for the program is provided by dispersing watermark over the whole code of the program; with the anti-reverse engineering technique, the resistance against reverse engineering is improved. The framework can be implemented under various software and hardware platforms. In this thesis, the implementation of the watermarking framework is performed under the Intel i386 architecture and the Windows operating system, which is then taken as an example to analyze the robustness of the watermark framework and the performance degradation of the watermarked program. It is form the experiments and analysis that the watermarking can resist various semantics-preserving transformation attacks and possess good tolerance for reverse engineering attacks. The robustness of the algorithm is at a high quality.(2) Embedding watermark by existing software watermark algorithm results in the performance degradation of watermarked program inevitably, and furthermore, the watermark is embedded in the redundancy of the program, so it is likely to be removed. To settle these problems, the conception of software zero-watermark based on birthmark is proposed by introducing image zero-watermarking into the software watermarking in this thesis. And then as Myles' birthmark is improved, feature n-gram set is presented to be birthmark of the software. Then the software zero-watermark algorithm based on the feature n-gram set is introduced incorporating the idea of Shamir's secret sharing. Comparative analysis between our birthmark and Myles' is provided theoretically and experimentally. Analyses and experiments show that the scheme provides both high credibility and resilience.(3) Aiming at solving the problem that static feature n-gram set is not robust to code compression, encryption, packing when it is presented to be the birthmark of software, the software birthmark of dynamic opcode n-gram set is introduced by extending that of static feature n-gram set to dynamic state. And the new birthmark can not only keep the advantages of feature n-gram set based on static opcode, but also be robust to code compression, encryption, packing. Furthermore, the algorithm based on dynamic opcode n-gram is improved by employing the theory of Probability and Statistic, which is to evaluate the similarity of two programs. As a result, the complexity of the improved algorithm decreases to O(n) which is O(n~2) as for the original one.Finally, the research work of this thesis is summarized, and the future developing direction of the software watermarking technologies is indicated.