Study of cover source mismatch in steganalysis and ways to mitigate its impact

Jan Kodovský; Vahid Sedighi; Jessica Fridrich

doi:10.1117/12.2039693

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19 February 2014 Study of cover source mismatch in steganalysis and ways to mitigate its impact

Jan Kodovský, Vahid Sedighi, Jessica Fridrich

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Proceedings Volume 9028, Media Watermarking, Security, and Forensics 2014; 90280J (2014) https://doi.org/10.1117/12.2039693
Event: IS&T/SPIE Electronic Imaging, 2014, San Francisco, California, United States

Abstract

When a steganalysis detector trained on one cover source is applied to images from a different source, generally the detection error increases due to the mismatch between both sources. In steganography, this situation is recognized as the so-called cover source mismatch (CSM). The drop in detection accuracy depends on many factors, including the properties of both sources, the detector construction, the feature space used to represent the covers, and the steganographic algorithm. Although well recognized as the single most important factor negatively affecting the performance of steganalyzers in practice, the CSM received surprisingly little attention from researchers. One of the reasons for this is the diversity with which the CSM can manifest. On a series of experiments in the spatial and JPEG domains, we refute some of the common misconceptions that the severity of the CSM is tied to the feature dimensionality or their “fragility.” The CSM impact on detection appears too difficult to predict due to the effect of complex dependencies among the features. We also investigate ways to mitigate the negative effect of the CSM using simple measures, such as by enlarging the diversity of the training set (training on a mixture of sources) and by employing a bank of detectors trained on multiple different sources and testing on a detector trained on the closest source.

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Jan Kodovský, Vahid Sedighi, and Jessica Fridrich "Study of cover source mismatch in steganalysis and ways to mitigate its impact", Proc. SPIE 9028, Media Watermarking, Security, and Forensics 2014, 90280J (19 February 2014); https://doi.org/10.1117/12.2039693

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