Andrew D. Ker
Jun 11, 2007
Journal name not available for this finding
This paper draws together two methodologies for the detection of bit replacement steganography: the principle of maximum likelihood, which is statistically well-founded but has lead to weak detectors in practice, and so-called structural detection, which is sensitive but lacks optimality and can suffer from complicated exposition. The key novelty is to extend structural analysis to include a hypothetical "pre-cover", from which the cover object is imagined to derive. Here, maximum likelihood detection is presented for three structural detectors. Although the algebraic derivation is long, and maximizing the likelihood function difficult in practice, conceptually the new detectors are reasonably simple. Experiments show that the new detectors are the best performers yet, very significantly so in the detection of replacement of multiple bit planes.