International Association for Cryptologic Research

International Association
for Cryptologic Research


Paper: An Information-Theoretic Model for Steganography

Christian Cachin
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Abstract: An information-theoretic model for steganography with a passive adversary is proposed. The adversary's task of distinguishing between an innocent cover message $C$ and a modified message $S$ containing hidden information is interpreted as a hypothesis testing problem. The security of a steganographic system is quantified in terms of the relative entropy (or discrimination) between the distributions of $C$ and $S$, which yields bounds on the detection capability of any adversary. It is shown that secure steganographic schemes exist in this model provided the covertext distribution satisfies certain conditions. A universal stegosystem is presented in this model that needs no knowledge of the covertext distribution, except that it is generated from independently repeated experiments.
  title={An Information-Theoretic Model for Steganography},
  booktitle={IACR Eprint archive},
  keywords={foundations / information hiding, covert channels, steganography},
  note={To appear in Information and Computation. 12481 received 11 Jun 2000, last revised 4 Mar 2004},
  author={Christian Cachin},