Research On Software Watermarking Technique Based On Local Variables

With the development of Internet, software copyright protecting is moreimportant, and is attracting more focus. One method is based on softwarewatermarking technology, which embedding the watermark into the softwarebefore released. Watermark is the identity information of the copyright owner.When copyright issue occurs, the owner can extract the watermark from thesoftware. Nowadays, software technology can be divided into two classes, staticand dynamic technology. The theoretical base includes cryptogram, graphic, math,software engineer and so on.In this paper, a software watermarking scheme, HSVN algorithm isproposed. It embeds the watermark into the local variable, making a good stealth.Before embedding, the watermark is divided based on GCRT. In this way, if morethan half of the sub-watermarks are extracted successfully, the originalwatermark can be restored. So HSVN algorithm has a good robustness. Whenchoosing local variables, a random algorithm is used to get the embeddingposition. In this way, the sub-watermarks can be stealthier and the existence ofwatermark will not add the size of the program. Also, the performance will not beaffected. In this paper, the extended form of HSVN is analyzed. The watermarkcan be embedded into the name of the function or other code, which can increasethe confusion of the watermark and improve the data rate.Based on HSVN algorithm, software is developed. HSVN system has twofunctions, watermarking embedding and watermark extracting, and composed bycontrol module, watermark transforming module, code scan module, randomsequence produce module, sub-watermark embedding module and watermarkrestore module. Control module manages other modules’ operation.Based on HSVN software, some experiments are done to analyze theperformance of HSVN algorithm on robustness, the effect to the software and thedata rate. Theoretic analysis is made on stealth.