Software Watermarking And Tamper-resistant Technology Research And Practice

Software watermark embeds some special secret messages in software program, and these messages are extractive when it is necessary to improve authority ownership.Software watermark can be divided into static software watermark and dynamic software watermark. Dynamic graphic watermark is a relatively new dynamic software watermark technique .It uses a graphic topology produced in executive time as the watermark number. Dynamic data analyses are difficult, so this kind of watermark is more robust to watermark attacks.This paper gives a new tamper-proofing dynamic graphic watermark scheme base on existing software watermark theories, and realizes a prototype system named D-JSM. D-JSM uses the result of two big primes as watermark. It encodes the result in a planted plane cubic tree structure. Then it transforms the constant in the candidate program into small integers, whose PPCT substructures can be found in the watermark tree, and gives the reference information of these substructures in order to locate them. Then we modify the candidate program source code, replacing the constants in candidate program with constant decoding functions, which are base on the reference information. The recognizing phase of this scheme can use debugging software. It can watch the execution statement of software program and detect the appearance of planted plane cubic tree structures, so the owner of software can retrieve the software watermark number.The innovation of this scheme is that it can tamper-proof software watermark. Once an attacker modifies the watermark tree, the reference information to retrieve key constants will become invalid, and the program will fail to run.According to experience result, this scheme is feasible. But it still needs lots of improvement before it can be used for practice.