Android-Stego: A Novel Service Provider Imperceptible MMS Steganography Technique Robust to Message Loss.

Information hiding techniques, specifically steganography, have been extensively researched for over two decades. However, steganography on smartphones over cellular carrier networks is yet to be fully explored. Today, smartphones which are at the epitome of ubiquitous and pervasive computing, make steganography an easily accessible covert communication channel. In this paper, we propose Android-Stego -- a framework for steganography employing smartphones. Android-Stego has been evaluated and confirmed to achieve covert communication over real world cellular service providers' communication networks such as Verizon and Sprint. A key contribution of our research presented in this paper is the benchmark results we have provided by analyzing real world cellular carriers' network restrictions on MMS message size. We have also analyzed the actions the carriers take -- such as compression and/or format conversion -- on MMS messages that fall outside the established MMS communication norm, which varies for each service provider. Finally, we have used these benchmark results in implementing Android-Stego such that it is sensitive to carrier restrictions and robust to message loss.