FingerKey, un cryptosystème biométrique pour l'authentification

9 pagesNational audienceNous nous intéressons dans cet article à l'authentification des utilisateurs par le biais de leurs données biométriques (empreinte digitale, forme de la main, . . . ). Traditionnellement, l'authentification biométrique d'un utilisateur consiste à vérifier que sa donnée biométrique courante est suffisamment proche d'une donnée de référence. Malheureusement, la sécurité de ce schéma souffre du fait que les données biométriques sont des données personnelles non révocables. Lorsqu'une donnée biométrique est compromise, contrairement à un mot de passe, elle ne peut pas ˆetre changée. Nous pensons que le point faible des approches traditionnelles réside dans le stockage des données biométriques de référence. Si les données biométriques n'étaient pas stockées, elles seraient plus difficiles à voler. Il serait aussi plus difficile d'en compromettre un grand nombre simultanément. Pour pallier ce probl`eme, nous proposons un schéma d'authentification biométrique ne nécessitant pas la comparaison à une valeur biométriqu de référence. Notre méthode améliore la sécurité de l'authentification biométrique puisqu'elle ne nécessite pas de stockage

Serca1 Truncated Proteins Unable to Pump Calcium Reduce the Endoplasmic Reticulum Calcium Concentration and Induce Apoptosis

By pumping calcium from the cytosol to the ER, sarco/endoplasmic reticulum calcium ATPases (SERCAs) play a major role in the control of calcium signaling. We describe two SERCA1 splice variants (S1Ts) characterized by exon 4 and/or exon 11 splicing, encoding COOH terminally truncated proteins, having only one of the seven calcium-binding residues, and thus unable to pump calcium. As shown by semiquantitative RT-PCR, S1T transcripts are differentially expressed in several adult and fetal human tissues, but not in skeletal muscle and heart. S1T proteins expression was detected by Western blot in nontransfected cell lines. In transiently transfected cells, S1T homodimers were revealed by Western blot using mildly denaturing conditions. S1T proteins were shown, by confocal scanning microscopy, to colocalize with endogenous SERCA2b into the ER membrane. Using ER-targeted aequorin (erAEQ), we have found that S1T proteins reduce ER calcium and reverse elevation of ER calcium loading induced by SERCA1 and SERCA2b. Our results also show that SERCA1 variants increase ER calcium leakage and are consistent with the hypothesis of a cation channel formed by S1T homodimers. Finally, when overexpressed in liver-derived cells, S1T proteins significantly induce apoptosis. These data reveal a further mechanism modulating Ca2+ accumulation into the ER of nonmuscle cells and highlight the relevance of S1T proteins to the control of apoptosis

Optimization of Topical Therapy for Leishmania major Localized Cutaneous Leishmaniasis Using a Reliable C57BL/6 Model

When initiating the cutaneous disease named cutaneous leishmaniasis (CL), Leishmania parasites develop within the parasitophorous vacuoles of phagocytes residing in and/or recruited to the dermis, a process leading to more or less chronic dermis and epidermis-damaging inflammatory processes. Topical treatment of CL could be a mainstay in its management. Any improvements of topicals, such as new vehicles and shorter optimal contact regimes, could facilitate their use as an ambulatory treatment. Recently, WR279396, a third-generation aminoglycoside ointment, was designed with the aim to provide stability and optimal bioavailability for the molecules expected to target intracellular Leishmania. Two endpoints were expected to be reached: i) accelerated clearance of the maximal number of parasites, and ii) accelerated and stable repair processes without scars. A mouse model of CL was designed: it relies on the intradermal inoculation of luciferase-expressing Leishmania, allowing for in vivo bioluminescence imaging of the parasite load fluctuation, which can then be quantified simultaneously with the onset and resolution of clinical signs. These quantitative readout assays, deployed in real time, provide robust methods to rapidly assess efficacy of drugs/compounds i) to screen treatment modalities and ii) allow standardized comparison of different therapeutic agents

Biometric fuzzy extractors made practical: a proposal based on FingerCodes

International audienceRecent techniques based on error-correction enable the derivation of a secret key for the (varying) measured biometric data. Such techniques are opening the way towards broader uses of biometrics for security, beyond identification. In this paper, we propose a method based on fingerprints to associate, and further retrieve, a committed value which can be used as a secret for security applications. Unlike previous work, this method uses a stable and ordered representation of biometric data, which makes it of practical use

Estimation of the amount of light intercepted by a plant in natural and artificial environments: Contribution of 3D virtual plants in sunflower and Arabidopsis thaliana

International audienceLight interception is a major contributor to biomass accumulation of crops. Beer's law has been extensively used to estimate the amount of light intercepted by a plant at canopy level. This method, based on the use of the leaf area index (LAI), is designed for well-developed crops where the canopy is assumed to be a turbid medium (Jones, 1992). However this assumption is seldom verified and in most situations canopies are strongly heterogeneous, as for example in perennial crops such as vineyards and orchards (e.g. Louarn et al., 2007) or in row crops during the first developmental stages or when leaf senescence occurs. We propose here to test a method based on 3D modelling to quantify the local light environment of plants in different situations, including artificial conditions. 3D virtual plants built from architectural measurements (Barczi JF et al., 1997) were used with a radiative balance model (Dauzat and Eroy, 1997) to characterise plant-environment interactions. A multi-directional approach was chosen to take into account direct and diffuse photosynthetically active radiations (PAR) which have a major influence on the plant radiative balance. Under natural conditions, when there was no obstacle to light, the direct-diffuse PAR ratio was derived from a single measurement of solar radiation above the canopy. In artificial conditions such as growth chambers or greenhouses, because of the presence of various occulting and reflecting materials and artificial light supplies, this ratio is more difficult to estimate. PAR sensors were specifically designed to measure the directional radiations received by plants in such environments. The effective radiation climate was mimicked by different virtual light sources whose characteristics were estimated from the directional measurements. The method was tested in sunflower and in the rosette of Arabidopsis thaliana, in canopy or isolated plants, from plant germination to the end of the vegetative period (Fig. 1). Experiments were carried out in natural (field), semi-controlled (greenhouse) and totally artificial (growth chamber) light environments. Various light levels were imposed and different genotypes were used to test the model relevance to environmental and genetic variations in the plant architecture. This approach was evaluated using measurements on light interception efficiency (Fig. 2) and it was compared to classical approaches (Beer's law for sunflower; leaf area x incident PAR for Arabidopsis) in the different situations. The model was particularly relevant to quantify light interception for crops in early growth stages, isolated plants or artificial environments. It was also able to characterise the local environment of different genotypes and to quantify the impact of architectural modifications on light interception. This 3D virtual plant approach is proposed as a tool to analyse the genotype-environment interactions and identify new selection criteria to improve light interception which is directly related to biomass production and yield

Early Curative Applications of the Aminoglycoside WR279396 on an Experimental Leishmania major-Loaded Cutaneous Site Do Not Impair the Acquisition of Immunity▿

Topical therapy is an attractive approach for the treatment of Leishmania major cutaneous leishmaniasis (CL). WR279396, an expanded-spectrum aminoglycoside ointment, is now in phase 3 trials. Because the application of a cream is easier than the injection of pentavalent antimony, many patients with CL will likely be treated with WR279396 soon after the onset of a lesion. However, this new therapeutic approach may impair the acquisition of immunity. We evaluated the impact of early topical therapy on acquired immunity in an optimized mouse model of L. major-induced CL. The efficacy of the WR279396 ointment in this model has been established previously. Acquired immunity was defined as the absence of lesions upon reinoculation of the same parasite isolate at a different skin site. Bioluminescence-based follow-up of luciferase-expressing L. major loads was also performed. In this model, the control of L. major loads at the initial inoculation site and the acquisition of immunity are simultaneous (day 22 postinoculation). The clinical and parasitological efficacies of WR279396 applied as early as day 11 postinoculation, i.e., during the L. major multiplication phase, did not impair the acquisition of immunity to a second L. major challenge. This is reassuring from the perspective of the wide deployment of WR279396-based therapy in foci where L. major is endemic

Biometric Fuzzy Extractors Made Practical: A Proposal Based on FingerCodes

Abstract. Recent techniques based on error-correction enable the derivation of a secret key for the (varying) measured biometric data. Such techniques are opening the way towards broader uses of biometrics for security, beyond identification. In this paper, we propose a method based on fingerprints to associate, and further retrieve, a committed value which can be used as a secret for security applications. Unlike previous work, this method uses a stable and ordered representation of biometric data, which makes it of practical use