Challenging the doctrines of JPEG steganography
Vojtěch Holub, Jessica Fridrich · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2014
The design of both steganography and steganalysis methods for digital images heavily relies on empirically justified principles. In steganography, the domain in which the embedding changes are executed is usually the preferred domain in which to measure the statistical impact of embedding (to construct the distortion function). Another principle almost exclusively used in steganalysis states that the most accurate detection is obtained when extracting the steganalysis features from the embedding domain. While a substantial body of prior art seems to support these two doctrines, this article challenges both principles when applied to the JPEG format. Through a series of targeted experiments on numerous older as well as current steganographic algorithms, we lay out arguments for why measuring the embedding distortion in the spatial domain can be highly beneficial for JPEG steganography. Moreover, as modern embedding algorithms avoid introducing easily detectable artifacts in the statistics of quantized DCT coefficients, we demonstrate that more accurate detection is obtained when constructing the steganalysis features in the spatial domain where the distortion function is minimized, challenging thus both established doctrines.