Steganography on Mobile Apps

Steganography is an ancient communication technique that hides a message inside a common object so that the message escapes scrutiny - today, we use digital files like photos and videos to hide and pass messages. Code to execute the message hiding inside digital photos was developed (on computers) in the 1990s. However, code to execute message hiding inside photos on an app for a smartphone was developed only in the last ten years. These mobile stego apps expanded steganography's reach from computer experts to the general public, where few technological skills are necessary.

How much of a presence does mobile stego have in our day-to-day lives? Beyond collecting download statistics, it is hard to say, as there are no known software tools capable of reliable detection of mobile stego images. Why not? A simple observation is that there exist no training pairs of cover-stego images to develop software solutions. Of course, the answer is more complex. In response to this lack of data, our research team designed and created a steganography database populated with mobile phone images, including stego images created from mobile phone apps. The story of creating StegoAppDB is remarkably involved and far more complex than simply acquiring smartphones, taking pictures, and creating stego images from apps. In this talk, I present our adventure of creating a steganography app database with a diverse team of people, skills, and ideas. This has led to various discoveries connecting steganography with mobile apps, identifying several interesting and difficult open problems.