Nous vous rappelons que, afin de garantir l'accès de tous les inscrits aux salles de réunion, l'inscription aux réunions est gratuite mais obligatoire.
Inscriptions closes à cette réunion.
14 personnes membres du GdR ISIS, et 0 personnes non membres du GdR, sont inscrits à cette réunion.
Capacité de la salle : 100 personnes.
La protection des documents numériques constitue un enjeu économique, mais aussi de société. Tout particulier, administration ou entreprise qui met ses contenus à disposition d'autres utilisateurs (e.g. sur un réseau social, un sytème télématique hospitalier ou une plate-forme de vidéos à la demande) souhaite pouvoir les protéger et s'assurer que les utilisateurs respecteront l'usage qui leur est concédé pour ces contenus. Plusieurs mécanismes de protection peuvent épauler ces fournisseurs de contenu. La cryptographie propose des solutions pour protéger la confidentialité des données (chiffrement), pour assurer leur intégrité (fonctions de hachage, signature), ou encore pour s'assurer de l'identité de la personne qui les envoie (authentification, signature). De telles primitives sont aujourd'hui intégrées dans de nombreux protocoles de communication standardisés, ainsi que dans les techniques de protection de droit d'auteur comme les DRM (Digital Rights Management).
Mais ces techniques ne peuvent, à elles seules, résoudre tous les problèmes liés à la protection de contenus. Avec l'avènement du numérique et la popularisation d'Internet est rapidement apparue la perspective de redistributions illicites massives de documents. Le contrôle d'accès et la mise en place de DRM, conçus pour limiter cette fraude, ont rapidement montré leurs limites. Car ces protections n'agissent que lors de la distribution du document. Mais une fois que celui-ci est joué en clair, sur un balladeur, un ordinateur, une télévision ou tout autre type de terminal, il ne contient plus aucune protection. C'est pourquoi des techniques de protection complémentaires, comme le tatouage robuste, ont été étudiées dès le début des années 90. Leur objectif est d'offrir une protection permanente, y compris lorsque le document est joué en clair, ou subit certaines transformations (compression, re-numérisation du signal analogique, etc).
Le tatouage appartient aux techniques dites de dissimulation d'information, qui toutes visent à cacher un message dans un signal de manière imperceptible, mais avec des objectifs différents. On parle plus spécifiquement de stéganographie lorsque l'objectif est de rendre cette communication furtive. On parle de tatouage, lorsque la robustesse des données cachées est déterminante, par exemple dans les contextes de protection de droit d'auteur, ou bien encore lorsque l'on cherche à détecter d'éventuelles modifications dans le document. On parle enfin de fingerprinting lorsque l'on cherche à personnaliser les différentes copies d'un même document, afin de tracer les utilisateurs indélicats qui les redistribueraient de manière illégitime.
La journée est dédiée aux interactions entre la cryptographie et la dissimulation d'information (stéganographie, tatouage, fingerprinting). En voici quelques exemples, non limitatifs :
Envoyer un résumé d'une page aux organisateurs de la journée Caroline Fontaine, Claude Delpha et William Puech avant le 21 Février 2012.
Caroline Fontaine, Lab-STICC et Telecom Bretagne, Brest [caroline.fontaine@telecom-bretagne.eu]
Claude Delpha, L2S, Gif-sur-Yvette [Claude.Delpha@lss.supelec.fr]
et William Puech, ICAR/LIRMM, Montpellier [william.puech@lirmm.fr]
La réunion se déroulera dans l'amphi Emeraude de Telecoms-Paristech.
9h30 - 10h : Welcome
10h00 : Invited Talk : Lattices and Homomorphic Encryption
C. Aguilar Melchor
11h00 : Invited Talk : Homomorphic encryption and information hiding
T. Bianchi
12h00 : Break
12h20 : Towards practical homomorphic encryption-based computation
S. Fau, R. Sirdey, G. Gogniat and C. Fontaine
12h45 : Hiding information in biometric systems for enhancing security and Protecting privacy
S. Kanade, D. Petrovska-Delacretaz and B. Dorizzi
13h10-14h15 : dejeuner
14h15 : Invited Talk : What is the Effective Key Length of a Watermarking Scheme?
P. Bas, joint work with T. Furon and F. Cayre
15h15 : Relative-entropy based beamforming for secret key transmission
R. Boyer and C. Delpha
15h40 : Message tracing with optimal ciphertext rate
D. H. Phan, D. Pointcheval and M. Strefler
16h05 : Encryption-Maps Data Hiding for Reduced Selective Encryption of H.264/AVC Video
L. Dubois and W. Puech
16h30 : End
Carlos Aguilar Melchor, (Mathematics and Computer Science department, Xlim, Limoges)
Carlos Aguilar Melchor, former student of the École Polytechnique de Paris, obtained his PhD in 2006 at the LAAS-CNRS (Toulouse) under the supervision of Yves Deswarte. His research domains are security, privacy and cryptography. In security and privacy he has worked mainly on anonymous communications and on trust and replication issues on new generation networks. In cryptography he has worked on various privacy primitives such as private information retrieval, homomorphic encryption and ring signatures. He is currently Assistant Professor (Maître de Conférences) at the University of Limoges.
Title : Lattices and Homomorphic Encryption
Summary : Homomorphic encryption schemes allow to compute directly over encrypted data without the decryption keys. Obtaining homormophic encryption schemes allowing to compute anything else than a very restricted set of functions over encrypted data has been an open issue for thirty years, until very recently a few groundbreaking results opened the path to theoretical and probably practical systems.
In this presentation, oriented for the non-specialist, we will present first these unique tools as well as their basic properties. Then we will show how these properties are extremely important for many applications. Finally, we will present the results obtained by the community since 2008 as well as their theoretical and practical consequences.
Tiziano Bianchi, (Dipartimento di Elettronica e Telecomunicazioni, Università di Firenze, Italy)
Tiziano Bianchi received the M.Sc. degree (Laurea) in electronic engineering and the Ph.D. degree in information and telecommunication engineering from the University of Florence, Italy, in 2001 and 2005, respectively. Since March 2005, he is with the Department of Electronics and Telecommunications, University of Florence as a Research Assistant. His research interests have involved processing of SAR images, signal processing in communications, multicarrier modulation techniques, and ultra-wideband systems. Current research topics include multimedia security technologies and signal processing in the encrypted domain. He is now working in the Image Analysis Processing and Protection Group as a Research Assistant with Alessandro Piva.
Title : Homomorphic encryption and information hiding
Summary : Homomorphic cryptosystems have the property that some elementary algebraic operations in the plain domain are mapped into elementary operations in the encrypted domain, so that some simple operations can be directly performed on the encrypted messages without the need of the decryption key. Although homomorphic encryption is a long standing topic in the crypto community, it has attracted the interest of signal processing experts only quite recently.
In this talk, we will explore the potential applications of homomorphic encryption in information hiding. Firstly, we will review how homomorphic encryption allows us to perform simple signal manipulations in a secure way, and the problems and limitations inherent with this approach. Then, we will see how homomorphic encryption can improve traditional information hiding techniques, enabling secure algorithms for watermarking embedding and detection on untrusted devices, and providing interesting solutions for privacy preserving applications.
Patrick Bas, (Signal and Images Group, LAGIS, Lille)
Dr Patrick Bas received the Electrical Engineering degree from the Institut National Polytechnique de Grenoble, France, in 1997 and the Ph.D. degree in Signal and Image processing from Institut National Polytechnique de Grenoble, France, in 2000. From 1997 to 2000, he was a member of the Laboratoire des Images et des Signaux de Grenoble (LIS), France where he worked on still image watermarking. During his post-doctoral activities, he was a Member of the Communications and Remote Sensing Laboratory of the Faculty of Engineering at the Université Catholique de Louvain, Belgium. His research interests include synchronisation and security evaluation in watermarking, and steganalysis. From 2001 to 2009, Patrick Bas worked as a CNRS researcher at Gipsa-Lab, and since 2010 he works at LAGIS, Lille, France.
Title : "What is the Effective Key Length of a Watermarking Scheme?", joint work with Teddy Furon and François Cayre
Summary : Whereas the embedding distortion, the payload and the robustness of digital watermarking schemes are well understood, the notion of security is still not completely well defined. The approach proposed in the last five years is too theoretical and solely considers the embedding process, which is half of the watermarking scheme. This paper proposes a new measurement of watermarking security, called the effective key length, which captures the difficulty for the adversary to get access to the watermarking channel. This new methodology is applied to additive spread spectrum schemes and DC-QIM, where theoretical and practical computations of the effective key length are proposed. It shows that these schemes are not secure as soon as the adversary gets observations in the Known Message Attack context.
Date : 2012-03-21
Lieu : Telecom-Paristech (Amphi Emeraude),
Thèmes scientifiques :
D - Télécommunications : compression, protection, transmission
Inscriptions closes à cette réunion.
Accéder au compte-rendu de cette réunion.
(c) GdR IASIS - CNRS - 2024.