Dynamic Self-Protection and Tamperproofing for Android Apps Using Native Code

With over one billion sold devices, representing 80% market share, Android remains the most popular platform for mobile devices. Application piracy on this platform is a major concern and a cause of significant losses: about 97% of the top 100 paid apps were found to be hacked in terms of repackaging or the distribution of clones. Therefore new and stronger methods aiming to increase the burden on reverse engineering and modification of proprietary mobile software are required. In this paper, we propose an application of the Android native code component to implement strong software self-protection for apps. Within this scope, we present three dynamic obfuscation techniques, namely dynamic code loading, dynamic re-encryption, and tamper proofing. We provide a practical evaluation of this approach, assessing both the cost and efficiency of its achieved protection level. Our results indicate that with the proposed methods one can reach significant complication of the reverse-engineering process, while being affordable in terms of execution time and application size.