Code Obfuscation For Software Protection

Recently, mobile code technology has a great deal of development and promises well.However the security problem with mobile code technology obstructs its wide application in real business. Among these security problems, how to protect mobile code from malicious host is a new issue that cannot be dealt by traditional technologies. In malicious host surroundings ,a software can be reverse engineered and also can be tampered with. The confidentiality, integrality and availability of software are threatened, so convenient and effective methods are needed to protect the intellectual property contained in software. Code obfuscation transformation emerges as a defense technique to protect software form reverse engineering. The advent and widely use of Java language brings the widely research on code obfuscation because the class file is easy to be decompiled. So code obfuscation for software protection in malicious host attract much attention and there are very important theoretical and practical significance.This paper treated protecting software and using more costly forms of reverse engineering as target, deeply researched reverse engineering and code obfuscation about defense and attack. A prototype of Code obfuscation system (JOT) based on Java byte code is realized, the comprehensive system is an important manifestation for our research.Main contributions in the paper are:(1) Analysis the concept, classification and research methods of reverse engineering, and research the application of formal methods in reverse engineering.(2) Researches all kind of mainstream technologies of code obfuscation, including layout obfuscation, control obfuscation, data obfuscation, class obfuscation and preventive obfuscation. We demonstrated some properties of obfuscating transformation.(3) Design of a model for general protecting software with confidentiality, integrality, availability, reliability and authentication of software. The model has a strategy guide for software protection.(4) Design of a model with the object-oriented programming for obfuscating transformation. The model has some reference value for obfuscating transformation.(5) Designed and implemented of a prototype system for both parse and obfuscatio of Java byte code (JOT), JOT not only achieve the layout obfuscation, but also achieve the class obfuscation. Leaving some extensible interfaces to be perfected.