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|All Authors / Contributors:||
Ilaria Venturini; Pierre Duhamel; Ecole nationale supérieure des télécommunications (Paris).
|Description:||1 vol. (XIII-203 p.) ; 30 cm.|
|Series Title:||ENST. E, 2006E047; ENST. E, 2006E047.|
|Responsibility:||Ilaria Venturini ; sous la direction de Pierre Duhamel.|
The subject matter of this work is exploitation of digital watermarking for integrity verification on digital media that are published on networks (wired as well as wireless). The approach here followed takes into account network cost and basic security. Network cost requires proposals to be modest under aspects including computation, communication and local storage. Basic security consists of making unreachable secret informations. A digital watermarking scenario which is adequate to the outlined context is proposed and a watermarking scheme for checking whether any substitution of a signal part has been performed, is detailed. For the proposed scheme, fractionary transforms are constructed which possess desirables properties that are important in digital signal processing. Their fractional parameter allows to control the autocorrelation of transformed signals. Two methods for building up fractional transforms which preserve the reality of the input signals are defined. The first method, starting from cosine and sine non-fractional transforms, obtains three classes of cosine and sine fractional transforms. The second method fractionalizes matrices which in general complexify their inputs, as the DFT. Both methods are examined under their decorrelation power on transformed signals. Basic security is discussed under vulnerability towards oracle attacks. Three methods having a wide application area are proposed to modify detection algorithms. The first method randomizes the decision answers by the detector on suitable inputs. The second method delays the decision answers on suitable inputs. The third method is a combination of the two.