The Research And Application Of Opaque Predicates Based On Chaos Theory

Along with the rapid development of the java programming language, many applications developed by using java programming language. But the release of the java program make it easy to get the java byte code, according to the reverse analysis it is very easy to get the algorithm even java source code from the java bytecode. So there is an urgent need of method to protect the java bytecode. Code obfuscation was proposed as a preventive reverse analysis method. Opaque predicate is a relatively new code obfuscation method. It can obfuscate the code by change the control flow of the program, but also keep the running results unchanged, and make it more difficult to reverse analysis at the same time. So it is considered to be a better means of code obfuscation. Initially it often uses the number theoretical true mathematical expressions as predicates and inserts it into source code to obfuscate it. The shortcoming of this opaque predicate is its simplicity and insecurity. Reverse analysis can easy to filter out the opaque predicates which disrupt the control flow of the program.In order to overcome the initial disadvantage of using a simple method to construct opaque predicates. In this paper, we will present a new method to construct opaque predicate based on the combination of a variety of other construct methods, the new method will combine chaos theory into it. The new construct methods not only improved the ability of obfuscation, but also significantly improved the ability in security and resistance to reverse engineer. The specific work of this paper is as follows:1. Made some analysis on opaque predicate and code obfuscation technology, summarizes the construction method of opaque predicate and how to use it in code obfuscation. With the development of reverse analysis technique, many kinds of reverse analysis method come out. This paper summarizes and generalizes the reverse analysis method.2. Propose a new method to construct opaque predicate with the combination of chaos theory. And in accordance with the characteristics of the opaque predicate cluster constructed by the new method, we designed to use N-queens problem to determine the output of the chaotic opaque predicate. In order to facilitate the use of new methods to conver the code, we develop a dedicated obfuscation transformation tool. This tool not only prossess the capability of using chaotic opaque predicates to obfuscate the code, but also integrated compilation and packaging of Java program.3. Use the third-party tools SandMark to evaluate the performance of chaotic opaque predicate in code obfuscation. And then give some advices about how to obfuscate the code based on the results of the evaluation.