Protection of Relational Databases by Means of Watermarking: Recent Advances and Challenges

Databases represent today great economical and strategic concerns for both enterprises and public institutions. In that context, where data leaks, robbery as well as innocent or even hostile data degradation represent a real danger, and watermarking appears as an interesting tool. Watermarking is based on the imperceptible embedding of a message or watermark into a database in order, for instance, to determine its origin as well as to detect if it has been modified. A major advantage of watermarking in relation to other digital content protection mechanisms is that it leaves access to the data while keeping them protected by means of a watermark, independent of the data format storage. Nevertheless, it is necessary to ensure that the introduced distortion does not perturb the exploitation of the database. In this chapter, we give a general overview of the latest database watermarking methods, focusing on those dealing with distortion control. In particular, we present a recent technique based on an ontological modeling of the database semantics that represent the relationships in between attributes—relationships that should be preserved in order to avoid the appearance of incoherent and unlikely records

Robust hashing for image authentication using quaternion discrete Fourier transform and log-polar transform

International audienceIn this work, a novel robust image hashing scheme for image authentication is proposed based on the combination of the quaternion discrete Fourier transform (QDFT) with the log-polar transform. QDFT offers a sound way to jointly deal with the three channels of color images. The key features of the present method rely on (i) the computation of a secondary image using a log-polar transform; and (ii) the extraction from this image of low frequency QDFT coefficients' magnitude. The final image hash is generated according to the correlation of these magnitude coefficients and is scrambled by a secret key to enhance the system security. Experiments were conducted in order to analyze and identify the most appropriate parameter values of the proposed method and also to compare its performance to some reference methods in terms of receiver operating characteristics curves. The results show that the proposed scheme offers a good sensitivity to image content alterations and is robust to the common content-preserving operations, and especially to large angle rotation operations

Color Image Analysis by Quaternion-Type Moments

International audienceIn this paper, by using the quaternion algebra, the conventional complex-type moments (CTMs) for gray-scale images are generalized to color images as quaternion-type moments (QTMs) in a holistic manner. We first provide a general formula of QTMs from which we derive a set of quaternion-valued QTM invariants (QTMIs) to image rotation, scale and translation transformations by eliminating the influence of transformation parameters. An efficient computation algorithm is also proposed so as to reduce computational complexity. The performance of the proposed QTMs and QTMIs are evaluated considering several application frameworks ranging from color image reconstruction, face recognition to image registration. We show they achieve better performance than CTMs and CTM invariants (CTMIs). We also discuss the choice of the unit pure quaternion influence with the help of experiments. appears to be an optimal choice

Fast Computation of Sliding Discrete Tchebichef Moments and Its Application in Duplicated Regions Detection

International audienceComputational load remains a major concern when processing signals by means of sliding transforms. In this paper, we present an efficient algorithm for the fast computation of one-dimensional and two-dimensional sliding discrete Tchebichef moments. To do so, we first establish the relationships that exist between the Tchebichef moments of two neighboring windows taking advantage of Tchebichef polynomials’ properties. We then propose an original way to fast compute the moments of one window by utilizing the moment values of its previous window. We further theoretically establish the complexity of our fast algorithm and illustrate its interest within the framework of digital forensics and more precisely the detection of duplicated regions in an audio signal or an image. Our algorithm is used to extract local features of such a signal tampering. Experimental results show that its complexity is independent of the window size, validating the theory. They also exhibit that our algorithm is suitable to digital forensics and beyond to any applications based on sliding Tchebichef moments

Medical image integrity control combining digital signature and lossless watermarking

International audienceEnforcing protection of medical content becomes a major issue of computer security. Since medical contents are more and more widely distributed, it is necessary to develop security mechanism to guarantee their confidentiality, integrity and traceability in an autonomous way. In this context, watermarking has been recently proposed as a complementary mechanism for medical data protection. In this paper, we focus on the verification of medical image integrity through the combination of digital signatures with such a technology, and especially with Reversible Watermarking (RW). RW schemes have been proposed for images of sensitive content for which any modification may aspect their interpretation. Whence, we compare several recent RW schemes and discuss their potential use in the framework of an integrity control process in application to different sets of medical images issued from three distinct modalities: Magnetic Resonance Images, Positron Emission Tomography and Ultrasound Imaging. Experimental results with respect to two aspects including data hiding capacity and image quality preservation, show different limitations which depend on the watermark approach but also on image modality specificities

New Advanced Technologies to Provide Decentralised and Secure Access to Medical Records: Case Studies in Oncology

The main problem for health professionals and patients in accessing information is that this information is very often distributed over many medical records and locations. This problem is particularly acute in cancerology because patients may be treated for many years and undergo a variety of examinations. Recent advances in technology make it feasible to gain access to medical records anywhere and anytime, allowing the physician or the patient to gather information from an “ephemeral electronic patient record”. However, this easy access to data is accompanied by the requirement for improved security (confidentiality, traceability, integrity, ...) and this issue needs to be addressed. In this paper we propose and discuss a decentralised approach based on recent advances in information sharing and protection: Grid technologies and watermarking methodologies. The potential impact of these technologies for oncology is illustrated by the examples of two experimental cases: a cancer surveillance network and a radiotherapy treatment plan. It is expected that the proposed approach will constitute the basis of a future secure “google-like” access to medical records

Medical record: systematic centralization versus secure on demand aggregation

<p>Abstract</p> <p>Background</p> <p>As patients often see the data of their medical histories scattered among various medical records hosted in several health-care establishments, the purpose of our multidisciplinary study was to define a pragmatic and secure on-demand based system able to gather this information, with no risk of breaching confidentiality, and to relay it to a medical professional who asked for the information via a specific search engine.</p> <p>Methods</p> <p>Scattered data are often heterogeneous, which makes the task of gathering information very hard. Two methods can be compared: trying to solve the problem by standardizing and centralizing all the information about every patient in a single Medical Record system or trying to use the data "as is" and find a way to obtain the most complete and the most accurate information. Given the failure of the first approach, due to the lack of standardization or privacy and security problems, for example, we propose an alternative that relies on the current state of affairs: an on-demand system, using a specific search engine that is able to retrieve information from the different medical records of a single patient.</p> <p>Results</p> <p>We describe the function of Medical Record Search Engines (MRSE), which are able to retrieve all the available information regarding a patient who has been hospitalized in different hospitals and to provide this information to health professionals upon request. MRSEs use pseudonymized patient identities and thus never have access to the patient's identity. However, though the system would be easy to implement as it by-passes many of the difficulties associated with a centralized architecture, the health professional would have to validate the information, i.e. read all of the information and create his own synthesis and possibly reject extra data, which could be a drawback. We thus propose various feasible improvements, based on the implementation of several tools in our on-demand based system.</p> <p>Conclusions</p> <p>A system that gathers all of the currently available information regarding a patient on the request of health-care professionals could be of great interest. This low-cost pragmatic alternative to centralized medical records could be developed quickly and easily. It could also be designed to include extra features and should thus be considered by health authorities.</p

Codage hybride cryptage-marquage-compression pour la sécurisation de l'information médicale

National audienceNous montrons dans ce chapitre comment des algorithmes de cryptage et de marquage permettent la sécurisation des images médicales. De nos jours, de plus en plus d'images numériques sont transférées sur les réseaux informatiques. Aucun système particulier n'a été développé pour le transfert sécurisé d'images. Les travaux présentés dans ce chapitre reposent sur l'idée d'adapter les algorithmes de cryptage et de marquage à l'information image qui est un signal particulier de par sa redondance et de par sa nature bidimensionnelle. Nous proposons de crypter des images au niveau des codages source afin de faire remonter cette fonctionnalité au niveau des couches hautes. De cette manière, les fonctionnalités cryptage et marquage d'images peuvent être insérées au niveau d'un logiciel. De plus, la protection doit être assurée pendant la transmission des images médicales mais aussi pour l'archivage de ces données numériques. Le problème consiste ensuite à faire résister ces chiffrements à des traitements avals comme la compression. En effet, la quantité d'information (entropie) à transmettre augmente fortement entre l'image originale et l'image cryptée. Dans le cas particulier de certains types d'images médicales, des grandes zones homogènes apparaissent. Ces zones perturbent l'efficacité des algorithmes de chiffrement. Paradoxalement ces zones homogènes, peu utilisées pour les diagnostics, peuvent être utilisées en toute sécurité pour le marquage d'images médicales. Aujourd'hui lorsqu'un médecin reçoit un patient il a souvent besoin de l'avis d'un spécialiste avant de prononcer son diagnostic. La solution serait de transmettre les images qu'il a obtenues par liaison informatique. Mais les réseaux informatiques sont complexes et les écoutes illégales nombreuses. Il se pose donc un réel problème quant à la sécurité lors de la transmission de données. Un domaine aussi important et secret que la médecine ne peut donc se permettre de prendre un tel risque sans se protéger. La protection la plus adaptée pour ce type de communication résiderait dans la cryptographie. Beaucoup de techniques de cryptage de texte ont été développées. Depuis l'antiquité, les hommes ont toujours essayé de coder des messages secrets pour se prévenir des oreilles malveillantes. Dans les premières esquisses de cette science du secret, la sécurité résidait dans la confidentialité de l'algorithme qui permettait le chiffrement et le déchiffrement. C'est au fil du temps qu'est apparue progressivement la notion de clef. Aujourd'hui, les systèmes de cryptage reposent sur des algorithmes mis à disposition de tous et c'est la clef, code secret particulier, qui est confidentielle et qui permet de crypter ou de décrypter le message \cite{Kerckhoffs:83}