Blacknoise: lightweight low-fi steganography in defense of free speech

Abstract

Censorship of communications is a widespread and current practice in various countries with repressive governments in order to prevent or restrict speech; political speech in particular. In many cases state-run telecommunications agencies, including those providing Internet and phone service, actively filter content or disconnect users in defense of incumbents in the face of widespread criticism by citizens. In this paper I present the results of experiments with Blacknoise, a system that uses commodity low-cost mobile telephones equipped with cameras, and takes advantage of their low-fidelity, noisy sensors in order to enable embedding of arbitrary text payloads into the images they produce. These images can then be disseminated via MMS, Bluetooth, or posting on the Internet, without requiring a separate digital camera or computer to perform processing.