The Research Of Fragile Watermarking For Tamper Detection Of Software

With the advent of the information age, information becomes an important strategic resource. Information technology changes people's lifestyles and work. Information science has become one of the most active fields in subject, and information industry has become a new economic growth point. As a typical digital product, the software is ushering in a huge development opportunity, meanwhile it faces many challenges. Downloading, copying, propagating and upgrading software has become very convenient, however, the software transmitted over the network can easily be used by malicious individuals or groups, which will pose a grave threat for information security and cause huge losses. Therefore, how to make full use of the Internet's convenience, how to protect software intellectual property and data integrity effectively have become a serious problem to be solved, which become a main information security problem nowadays. Relative to the multimedia watermarking, software watermarking is more realistic significance and will also bring tremendous economic benefits to information construction in china.Software watermarking is, in essence, a technique for embedding a secret message into a piece of software in order to encode some identifying information about it. When an unauthorized use of this software occurs, the secret message may be identified the ownership of the software or its authenticity and integrity. Software has deterministic behavior, self-evident behavior and the dependent nature of the execution environment, so software watermarking cannot be as multi-media watermarking that relies on the existence of redundant multimedia information to encode watermark, it has to rely on the features of software itself to embed watermark.Investigating how to use the change of program code to implement software tampering detection of fragile watermarking scheme is the point of this paper. The main findings of this paper can be summarized as follows:(1)A fragile software watermarking scheme against the demand for integrity verification of software is proposed in this paper. The algorithm uses the idea of semantic preserving code substitution for embedding the watermark. With the system, the generated watermark relates closely to the content of software, and the scheme has highly sensitive to different types of attack. Furthermore, both watermark generating and embedding position controlled by the private key enhance the security of watermarking scheme. The scheme not only can effectively detect tamper, but also has the ability to judge the types of tamper clearly.(2)A spread spectrum-based fragile software watermarking scheme is proposed in this paper. The algorithm extracts respectively a vector of instruction-group frequencies from all basic blocks of original program and constructs a vector matrix, then uses the PCA to generate watermark and modifies the vector of matrix to embed the watermark. With the system, spreading the watermark over the code provides not only a high level of stealth but also a global protection for the original program.