On Slicing Specification Based Software Watermarking

With the extensive application of the Internet and the emergence of Virtual Machine technology, software protection encounters an unprecedented challenge. Software products can be spreaded abroad everywhere in very short time through Internet. Large scale parallel download replaces previous one-to-one infringing copy, while the single software pirate becomes thousands of individuals who are difficult to be tracked. Furthermore, in support of the Virtual Machine technology, the intermediate language programs have particular characteristic of Machine-independent makes the attack against software more effective such as reverse engineering; reverse compiling; obfuscation and so on. Software protection has become an urgent research subject to ensure the development of software industry towards a healthy and sustaining direction.Software protections technology has outstanding characteristics that include multiple research views and abundant experimental methods, much active exploration have been done by the domestic and foreign scholars. Existing methods can mainly ensure software security during its distributing and running which can satisfy the distributed requirement. But there is no obvious breakthrough in resisting pirate by now. As an important branch of digital watermarking, software watermarking resists software's pirate by hiding copyright information in software. In recent years, a lot of software watermarking algorithms have been presented, but they seldom can comprehensively satisfy practical requirement in high robustness. In a word, there is no really practical software watermarking up to now.This paper presents a novel software watermarking method based on program slicing rule against the weak robustness of existing algorithms. In view of the characteristic that aplplication programs must be splitted in mobile computing, firstly, source program is automatically sliced up by slice tool; the different slice rule X represents different watermark information. Secondly, sliced program is segmented and converted into open and hidden module. The open module is executed on an unsecured machine while the hidden module is executed on a secure one, the two modules interact each other by remote procedure calls. Neither the open module nor the hidden one contains all information of watermark; an attacker can only get the interactive behaviors between the open module and the hidden one on the condition that he can't recover the hidden module. Being lack of indispensable information, it is very difficult to reverse-compile larger program, and it not only makes the reversing engineering more difficult, but also hide the watermark information effectively. In addition, this scheme controls its effect to program's running at reasonable range by optimizing the design of split-transfering algorithm and enhance the efficiency of interaction. The extraction of watermark is a validation that indicates the mapping relation between slice's rule and watermark information. We integrate the open module and the hidden module according to split-transfering's rule firstly, and the watermark can be got by the slice's rule.In order to evaluate practical effect of this scheme, our experiment mainly focuses on the complexity of recovery of the hidden module's content, and evaluates the time cost of interaction between the open module and the hidden one. The experimental result proves that this scheme controls its effect to program's running at reasonable range on the basis of enough stealth and robustness. The software watermark method based on program slicing is a beneficial exploration for software watermarking research.