Informed stego-systems in active warden context: statistical undetectability and capacity

TL;DR

This paper compares three informed stego-systems in active warden scenarios, analyzing their statistical undetectability and capacity through theoretical and experimental methods.

Contribution

It provides a comprehensive theoretical and experimental comparison of scalar Costa, trellis-coded quantization, and spread transform Costa schemes in active warden contexts.

Findings

Trellis-coded quantization offers higher capacity.

Spread transform Costa scheme shows better undetectability.

All schemes have trade-offs between capacity and detectability.

Abstract

Several authors have studied stego-systems based on Costa scheme, but just a few ones gave both theoretical and experimental justifications of these schemes performance in an active warden context. We provide in this paper a steganographic and comparative study of three informed stego-systems in active warden context: scalar Costa scheme, trellis-coded quantization and spread transform scalar Costa scheme. By leading on analytical formulations and on experimental evaluations, we show the advantages and limits of each scheme in term of statistical undetectability and capacity in the case of active warden. Such as the undetectability is given by the distance between the stego-signal and the cover distance. It is measured by the Kullback-Leibler distance.