Payload Scaling for Adaptive Steganography: An Empirical Study
Résumé
Payload-scaling laws of imperfect steganography inform the steganographer about how the size of secret payload should grow with cover size for constant statistical detectability. In this letter, we carry out an empirical study for the case when the steganographer and the steganalyst operate at a game-theoretic equilibrium. We first explore the possibility to leverage a generalization of the square root law to content-adaptive steganography due to Ker. Since this result does not appear to be tight enough for realistic cover sizes, we instead work with a detectability limited sender in image sources with a forced model as well as real images in both spatial and JPEG domain. The scaling is observed in practice when the images are carefully cropped to preserve the distribution of costs across scales.