An Information-Theoretic Model for Steganography

An information-theoretic model for steganography with passive adversaries is proposed. The adversary’s task of distinguishing between an innocent cover message C and a modified message S containing a secret part is interpreted as a hypothesis testing problem. The security of a steganographic system is quantified in terms of the relative entropy (or discrimination) between P_C and P_S. Several secure steganographic schemes are presented in this model; one of them is a universal information hiding scheme based on universal data compression techniques that requires no knowledge of the covertext statistics.