A Software Watermarking Method

Softwarewatermarkingisanewmethodusedtoprotectthecopyrightofsoftware.Unlike traditional software protection techniques dependent only on encryptiontechnology, software watermarking embeds certain secret information into hostsoftware codes and the embedded secret information can be extracted from thesoftware embedded watermarking when needed. Recent years, software watermarkingtechnology has been actively explored and researched at home and abroad. Manysoftware watermarking algorithms have been proposed, but most of what can not beintegrated to meet the actual needs in the data rates, stealth, and robustness and so on.At present, no systems of software watermarking can be really applied to practicalwork, so we need to constantlyimprove and perfect it. This dissertation focuses on theresearch and exploration of improving stealth and data rate of the softwarewatermarking,themainworkofwhichisasfollows:1. The current copyright protection technologies of software, especially softwarewatermarking technology are introduced, including the concept and classification ofsoftware. Attacks of software watermark, advantages and disadvantages of existingsoftwarewatermarkingalgorithmarediscussed.2. Cryptographic technique is studied. In this paper, the copyright information ofownership could be re-encoded bycryptographyalgorithm to hide the information andensure that unauthorized users can not get the real content, so that the security of thesystemcanbestrengthened. Itisdifficultforattackerstorecovertheoriginalcopyrightinformation, when they do not know the private key. So the watermark can beprotectedandthesecurityofthewatermarkcanbeimproved.3. Dynamic Graph Software Watermark technique is analyzed primary. A newsoftware watermarking method based on public-key cryptography and PPCT dynamicgraph encoding is proposed in this paper. Firstly, the copyright information ofownership should be encrypted for software by RSA public-key cryptographyalgorithm. Secondly, the size of each sub-watermark number (binary bits) isdetermined,accordingto thesizeofthewatermark(binarybits)andthesub-watermarkblocksneededtosplit.Thirdly,thevaluesofallsub-watermarksareproducedbasedonChinese Remaining Theorem. Finally, these sub-watermarks are encoded into plantedplane cubic tree structures which are embedded into the software codes as software watermarktoimprovethesafetyofwatermarkinformation.4.Thesystem basedonthis schemeis designedandrealized.Throughanalyses ofdata rate, stealth and load and experiments of confusion attacks and anti - compileattacks, it has proved that the system has a good anti-attack capabilityand a high levelofstealthandsecurity.