Design New Framework For Obfuscated Interpretation Which Can Embed Watermarks

In recent years, with the remarkable development of internet, the influence of environment of living and methods of pirate is changed. Large range application of P2P (Peer To Peer) network, the pirate of the software is rampant day by day, software protection issue become outstanding. Bootleggers are no longer a few specialized pirate personages but hundreds and thousands of individuals, how to carry on effective protection to the software become more urgent. Law and technology is effective in practice. In 1991, first law which protecting software was published, more details were added in its second edition in 2002. Although these law strongly punish the behavior of pirate, but pirate still exist everywhere. Because these punish only focuses on the thing happened, how to defend pirate become more important than ever. The protection technologies of software divide into two types according to their product, one is pure software, another is based on the hardware, or the combination of the software and hardware. Because more and more software adopt similar way to distribute on line, software protection concentrates on the first mainly. And the first type concentrates on three fields mainly, such as obfuscation, encryption, and software watermark. The attack of the real world is many angles and multi-level, it is very difficult for single technology to reply all the attacks. This paper designs a kind of software protection scheme combined obfuscation with software watermark, utilizing the obfuscation to prevent the program from being compiled in reverse and the watermark to prove the real owner. The whole framework includes the translator and FSM-based interpreter, and the translator is used for obfuscating source code, FSM-based unit embed in the compiler to be used in interpretation. The obfuscation technology adopted in this scheme is a kind of dynamic map, the program after obfuscation does not include all program information. Because of the information of lacking, the degree of difficulty of compiling the procedure is relatively great. Changing and resuming following the same specification, this specification is different as information of the watermark is different, one state corresponding to one bit of watermark information, utilizing the value of this bit which the change rule of this statement be represented in the state. The watermark information includes the digital signature of the original program etc., and the purpose is to prevent the additive attack. In order to test the actual operation result, this paper designs and realizes a prototype system. The system integrates the translator and FSM unit in the same interface. The functions mentioned in this paper are all realized in the system, this system is a mini-system of real one, using this system we can confirm the goal requirement and the exploitation scheme of the system. Finally, according to the test result of JAVA, it is difficult to compile in reverse or attempt to destroy the watermark for the large-scale program adopting this scheme.