Modeling Content-Adaptive Steganography with Detection Costs as a Quasi-Zero-Sum Game

Recently, content-adaptive steganography was modeled by Johnson et al. as a stochastic, two-player, zero-sum game between a steganographer and a steganalyst. To model economically rational steganalysts, we generalize this model by introducing a non-uniform cost of steganalysis. We characterize the Nash equilibria of our game based on the theory of blocking games, a class of quasi-zero-sum games, which were previously used to study the attack-resilience of systems and networks. Finally, we provide efficiently computable linear programs for finding an equilibrium. To the best of our knowledge, our paper is not only the first one to solve our generalized model, but it is also the first one to solve the original model for every possible combination of the parameter values.