Steganography via cover-source switching

This paper proposes a new steganographic scheme relying on the principle of “cover-source switching”, the key idea being that the embedding should switch from one cover-source to another. The proposed implementation, called Natural Steganography considers the sensor noise naturally present in the raw images and uses the principle that, by the addition of a specific noise the steganographic embedding tries to mimic a change of ISO sensitivity. The embedding methodology consists in 1) designing the stego-signal that enable to switch from one source to another the raw domain, 2) computing the statistical distribution of the stego-signal in the processed domain, 3) embedding the payload in the processed domain. We show that this methodology is easily tractable whenever the processes are known and enables to embed large and undetectable payloads.