Spread Spectrum Watermarking Based On Software Copyright Protection

Software is a ubiquitous digital product in digital society. Software security is therefore becoming a research forefront which attracts great attention from academia and practitioners. Secure software engineering is a multi-disciplinary research field across software engineering, information security and high performance computation. Traditional ways to protect software are sometimes ineffective when they try to deal with some problems such as software code misusing, code belonging and so on. So people migrated watermark applied in multimedia document protection to software protection. And this kind of watermark has caught people's eyes increasingly. And become a talent showing itself among those software protection technologies.In this thesis, the concepts, purposes, properties of ideal watermark, attacks against watermark and the sorts of watermark are introduced. Then the thesis writes on the status of software watermark and describes some typical software watermark, and analyses them from the point of security and practicability. After that, the frame of spread spectrum software watermarking was proposed. Spread spectrum watermarking technique embed watermark in frequency domain of the host data, and then robustness and security can be obtained due to small watermark signal energy and difficulty to detect. A dynamic spread spectrum software watermarking scheme was put forward by modifying times of stack operations to embed watermark and computing correlation to detect watermark. Finally, a software watermark tool used for the java application program is designed and implemented using Java programming language in order to validate the feasibility and practicability of the algorithm. The experimental results show that the software was designed to achieve the desired results.