The processing power of smartphones supports steganographic algorithms that were considered to be too computationally intensive for handheld devices. Several steganography apps are now available on mobile phones to support covert communications using digital photographs.

This chapter focuses on two key questions: How effectively can a steganography app be reverse engineered? How can this knowledge help improve the detection of steganographic images and other related files? Two Android steganography apps, PixelKnot and Da Vinci Secret Image, are analyzed. Experiments demonstrate that they are constructed in very different ways and provide different levels of security for hiding messages. The results of detecting steganography files, including images generated by the apps, using three software packages are presented. The results point to an urgent need for further research on reverse engineering steganography apps and detecting images produced by these apps.