An Improved PPCT Based Dynamic Graph Software Watermarking Scheme

Dynamic graph software watermarking has become the focus of attention both in the academia and industries. In this paper we improve the IPPCT structure (Improved Planted Plane Cubic Trees) which is based on the Radix-k circular linked list structure and PPCT structure. This further improvement takes advantage of all nodes in PPCT tree to encode so as to enhance the data rate at the same time. In order to build the watermark graph structure easily, the watermark number is divided into smaller sub-data on the basis of the Chinese Remainder Theorem before it is mapped into the watermark graph. Furthermore, for the purpose of enhancing the watermarking resistance against the attacks, each sub-divided is transformed into several equivalent data, then the latter will be embedded into the software. This kind of redundantly embedding aims to make sure that the watermark data can be recovered from the subset of equivalent watermark graphs extracted from the software. Experiments and analysis results show that this improved dynamic graph software watermarking scheme can make a good balance effect between the data rate, stealth and robustness of them.