Estimating the Information Theoretic Optimal Stego Noise
We recently developed a new benchmark for steganography, underpinned by the square root law of capacity, called Steganographic Fisher Information (SFI). It is related to the multiplicative constant for the square root capacity rate and represents a truly information theoretic measure of asymptotic evidence. Given a very large corpus of covers from which the joint histograms can be estimated, an estimator for SFI was derived in , and certain aspects of embedding and detection were compared using this benchmark.
In this paper we concentrate on the evidence presented by various spatial-domain embedding operations. We extend the technology of  in two ways, to convex combinations of arbitrary so-called independent embedding functions. We then apply the new techniques to estimate, in genuine sets of cover images, the spatial-domain stego noise shape which optimally trades evidence – in terms of asymptotic KL divergence – for capacity. The results suggest that smallest embedding changes are optimal for cover images not exhibiting much noise, and also for cover images with significant saturation, but in noisy images it is superior to embed with more stego noise in fewer locations.
Unable to display preview. Download preview PDF.
- 1.Ker, A.: Estimating Steganographic Fisher Information in real images. In: Proc. 11th Information Hiding Workshop (to appear, 2009)Google Scholar
- 3.Böhme, R.: Improved Statistical Steganalysis using Models of Heterogeneous Cover Signals. PhD thesis, Technische Universität Dresden (2008)Google Scholar
- 4.Ker, A.: The ultimate steganalysis benchmark? In: Proc. 9th ACM Workshop on Multimedia and Security, pp. 141–148 (2007)Google Scholar
- 7.Ker, A., Pevný, T., Kodovský, J., Fridrich, J.: The square root law of steganographic capacity. In: Proc. 10th ACM Workshop on Multimedia and Security, pp. 107–116 (2008)Google Scholar
- 8.Filler, T., Ker, A., Fridrich, J.: The square root law of steganographic capacity for Markov covers. In: Proc. SPIE. Media Forensics and Security XI, vol. 7254, pp. 801–811 (2009)Google Scholar
- 13.Filler, T., Fridrich, J.: Fisher Information determines capacity of ε-secure steganography. In: Proc. 11th Information Hiding Workshop (to appear, 2009)Google Scholar