Research On Mixed Software Watermarking Based On Quadratic Residue

As the impetuous development of computer software industry and Internet, the software piracy and cracking which is aiming at software are running rampantly. So how to protect the copyright and kernel content of the software is becoming a intractable problem in software security field. At present, there are two kinds of technologies in software protection: encryption and information hiding. In information hiding field, there are three kinds of technologies for software protection: code obfuscating, software watermarking and tamper proofing. This paper studies software watermarking detailedly and for the shortcoming of weak robustness of software watermark, this dissertation put forward a new scheme which bases on Quadratic Residue Theory.Software watermarking is divided into static watermark and dynamic watermark via embedding and extracting mode o Static watermark has the feature of easy to embed and extract, but it's anti-attacking ability is bad and can't be use in the situation whose demand is higher. In opposition to static watermark, dynamic watermark has the feature of anti-attacking. It is one of the best software watermarks. Its kernel idea is transform watermark information into topology structure, then make semantics-preserving attacking unsuccessfully. The extracting procedure is after user input secret key, the topology graph is created in heap, and at last it is recovered to watermark data via decode algorithm. Its robustness and hiding performance are stronger.The core of dynamic watermark is the encoding and decoding of graphs. At present, the PPCT enumeration encodes is the best one for it has advantage in structure and robustness. But its shortcoming is low data rate. This paper brings out a Quadratic Residue-based watermarking scheme. At first, hash value is got from electronic license. then quadratic residue C is calculated by Rabin cipher scheme. At last, C is translated into binary tree-based radix-K data structure, when the watermark is tampered the program will terminate executing. At the same time, in order to enhance the robustness of watermark, the combination of radix-k and PPCT encoding scheme is adopted in this paper. The resolutions which are conversely deduced via Rabin scheme are translated intothis compound structure. This scheme fully makes use of the advantage of PPCT in structure and feature of Radix-K in high data rate. If attacker destroys one of these structures, another resolution M can be recovered via the rest structure and verify its validity by Rabin cipher system.