Android App Protection via Interpretation Obfuscation

To protect Android app from malicious reproduction or tampering, code obfuscation techniques are introduced to increase the difficulty of reverse engineering and program understanding. Current obfuscation schemes focus more on the protection of the meta information over the executable code which contains valuable or patented algorithms. Therefore, a more sophisticated obfuscator is needed to improve the protection on the executable code. In this paper we propose SMOG, a comprehensive executable code obfuscation system to protect Android app. SMOG is composed of two parts, an obfuscation engine and an execution environment. The obfuscation engine is at software vendor´s side to conduct the obfuscation on the app´s executable code, and then release the obfuscated app to the end-user along with an execution token. The execution environment is setup by integrating the received execution token, which endows the Android Dalvik VM the capability to execute the obfuscated app. SMOG is an easily deployed system which proves fine-grained level protection. The obfuscated app generated by SMOG could resist static and dynamic reverse engineering. Moreover, the benchmark result shows SMOG only costs about 5% more performance in dispatching the incoming bytecode to the proper interpreter.