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Theses

Analyse de canaux de communication dans un contexte non coopératif.

Abstract : In this thesis, we study communication channels in a non cooperative context and more particularly, error correcting codes reconstruction on one hand, and steganalysis on the other hand. We play an unauthorized observer who wants to have access to the information exchanged between two legal users. Our researches on algorithms to reconstruct error correcting codes lead us to propose a generic approach for linear block codes, convolutional and turbo codes. We analyze the Sicot-Houcke algorithm and use it as a base to design an entirely automatic technique to reconstruct convolutional codes. Moreover, this technique has a better complexity than existing ones. Finally, we adapt theses results to retrieve the parameters of turbo code encoders. In the context of steganographic analysis, we first propose two new models of security which play with a real-life adversary. Then, we adapt the RS analysis int! o a detection scheme for the Multi Bit Plane Image Steganography for the spatial domain. This algorithm was proposed by Nguyen et al. at IWDW'06. Finally, we develop a new approach to analyze JPEG files. We study statistics of compressed DCT coefficients and point out new detectors with high performances which are independent, in practice, of the amount of hidden information. We illustrate these results with an universal steganalysis scheme and a specific one to detect Outguess, F5 and JPHide and JPSeek.
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Submitted on : Thursday, July 22, 2010 - 11:41:08 AM
Last modification on : Wednesday, March 27, 2019 - 4:41:26 PM
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Johann Barbier. Analyse de canaux de communication dans un contexte non coopératif.. Informatique [cs]. Ecole Polytechnique X, 2007. Français. ⟨pastel-00003711⟩

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