An Improved Scheme Of Tamper-proof Watermarking Based On Hybrid Encoding

With the rapid development of computer network technology, information exchange and delivery have becoming more and more efficient, which benefits the sharing of knowledge and technology, but it has great tremendous risk for the software protection which encounters an unprecedented challenge and threat. Software watermarking is just the technology to deal with the problem, it embeds a secret message into the program to protect the intellectual property from stealing and prove the ownership after the stealing occurred.Software watermarking verifies the copyright without the limit on program execution, which is adapted to the policy of software manufacturers that the protection of intellectual property and the occupancy of market, so the technology has attracted much attention of software manufacturers and academia. Up to now, there are many algorithms of Software watermarking, and dynamic graph watermarking (DGW) is one of the more typical watermarking. DGW is a watermark that is represented in a graph topology, which is created only at the runtime of a program, triggered by a special sequence of input. Currently, DGW has some restrictions among the integrated performance criteria of watermarking, and tamper-resistant capabilities are weak. This thesis focuses on the above issues of applying watermarking and tamper-proofing to software protection, improved the graph topology and scheme of tamper-proof watermarking to increase the data-rate/stealth and the ability of resisting attack, at the same time, enhance the robustness and tamper-resistant capabilities. The accomplished researches are as follows:(1) Systematic researching about the technology of software watermarking especially DGW, including encoding, embedding, attack and protection and so on.(2) The core issue of DGW is the graph codec issue.This article improved a graph topology which is called I-IPPCT by Hybrid Encoding; it inherited the stability of IPPCT and added extra points to improve the date-rate and the ability of resisting attack. By comparing the topology of Radix-K and IPPCT, we have improved the high date-rate of I-IPPCT. At the same time, we evaluated the date rate, robustness, as well as the hidden watermark to load brought about by the overload performance of hybrid encoding I-IPPCT, the experimental results show that the scheme of Hybrid Encoding has strong robustness and high data rate. (3) In order to improve the robustness and stealth, enhance tamper-resistant capabilities, using GCRT splitting and tamper proofing technology to improve a DGW scheme with tamper proofing, this scheme changed the thinking of the previous graph partitioning which can break through the limitation of the dilemma between watermark sub-graphs, using GCRT splitting to split the large numbers which represent the watermark copyright information so as to improve the the stealth and hidden information; while increasing the redundancy of data, adding anti-tampering function,to enhance the robustness and tamper-resistant capabilities effectively.