33 research outputs found

    Dysphagia revealing diffuse idiopathic skeletal hyperostosis: report of two cases and literature review

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    Diffuse Idiopathic Skeletal Hyperostosis (DISH) also known as Forestier's disease, is a musculoskeletal disorder characterized by the calcification of ligaments essentially the vertebral longitudinal anterior ligament. Men are generally affected. It is often asymptomatic. The most common extra-spinal clinical manifestation of this disease presents as dysphagia followed by respiratory disturbances such as dyspnea and sleep apnea. In this paper we discuss two cases where the patients have experienced progressive dysphagia. Radiological findings were compatible with DISH. The management was based on diet modification and anti-inflammatory medication

    A Cryptanalysis of Two Cancelable Biometric Schemes based on Index-of-Max Hashing

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    Cancelable biometric schemes generate secure biometric templates by combining user specific tokens and biometric data. The main objective is to create irreversible, unlinkable, and revocable templates, with high accuracy in matching. In this paper, we cryptanalyze two recent cancelable biometric schemes based on a particular locality sensitive hashing function, index-of-max (IoM): Gaussian Random Projection-IoM (GRP-IoM) and Uniformly Random Permutation-IoM (URP-IoM). As originally proposed, these schemes were claimed to be resistant against reversibility, authentication, and linkability attacks under the stolen token scenario. We propose several attacks against GRP-IoM and URP-IoM, and argue that both schemes are severely vulnerable against authentication and linkability attacks. We also propose better, but not yet practical, reversibility attacks against GRP-IoM. The correctness and practical impact of our attacks are verified over the same dataset provided by the authors of these two schemes.Comment: Some revisions and addition of acknowledgement

    Adequate Elliptic Curve for Computing the Product of n Pairings

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    Many pairing-based protocols require the computation of the product and/or of a quotient of n pairings where n > 1 is a natural integer. Zhang et al.[1] recently showed that the Kachisa-Schafer and Scott family of elliptic curves with embedding degree 16 denoted KSS16 at the 192-bit security level is suitable for such protocols comparatively to the Baretto- Lynn and Scott family of elliptic curves of embedding degree 12 (BLS12). In this work, we provide important corrections and improvements to their work based on the computation of the optimal Ate pairing. We focus on the computation of the nal exponentiation which represent an important part of the overall computation of this pairing. Our results improve by 864 multiplications in Fp the computations of Zhang et al.[1]. We prove that for computing the product or the quotient of 2 pairings, BLS12 curves are the best solution. In other cases, specially when n > 2 as mentioned in [1], KSS16 curves are recommended for computing product of n pairings. Furthermore, we prove that the curve presented by Zhang et al.[1] is not resistant against small subgroup attacks. We provide an example of KSS16 curve protected against such attacks

    On the Computation of the Optimal Ate Pairing at the 192-bit Security Level

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    Barreto, Lynn and Scott elliptic curves of embedding degree 12 denoted BLS12 have been proven to present fastest results on the implementation of pairings at the 192-bit security level [1]. The computation of pairings in general involves the execution of the Miller algorithm and the final exponentiation. In this paper, we improve the complexity of these two steps up to 8% by searching an appropriate parameter. We compute the optimal ate pairing on BLS curves of embedding degree 12 and we also extend the same analysis to BLS curves with embedding degree 24. Furthermore, as many pairing based protocols are implemented on memory constrained devices such as SIM or smart cards, we describe an efficient algorithm for the computation of the final exponentiation less memory intensive with an improvement up to 25% with respect to the previous work

    School-based intervention to promote healthy nutrition in Sousse, Tunisia

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    Introduction: Obesity among children is a major risk factor for chronic diseases. School interventions programs can represent a mean to implement healthy nutrition attitudes at early ages. Our objective was to evaluate the effects of a school intervention program to promote healthy nutrition among adolescents, in terms of knowledge, behaviors and intention. Methods: Quasi experimental study among urban students in Sousse, Tunisia with 2 groups, intervention and control. The intervention group had an interactive program integrated with school courses that promoted healthy nutrition habits. Both groups had a pre post evaluation. Results: 2200 students aged from 12 to 16 participated to the pre post evaluation. In the intervention group, there were significant changes form pre to post test in knowledge, intentions, and behaviors. In the control group, almost no significant changes were observed. Conclusion: School intervention programs can represent an interesting approach to promote healthy nutrition habits among adolescent

    Anti-tumor Activity of N4 [(E)-1-(2-hydroxyphenyl) Methylidene], N4-[(E)-2-Phenylethylidene], N4 [(E,2E)-3-Phenyl-2-propenylidene], and N4 [(E)ethylidene] Isonicotinohydrazide on K562 and Jurkat Cell Lines

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    Using the water eliminated mechanism, reactions of 4-pyridinecarboxylic acid hydrazide and salicylaldehyde, benzaldehyde, cinnamaldehyde, and formaldehyde afforded the corresponding N4[(E)-1-(2-hydroxyphenyl) methylidene] (NHPM), N4-[(E)-2-phenylethylidene] (NPI), N4[(E,2E)-3-phenyl-2-propenylidene] (NPPI), and N4[(E) ethylidene] (NEI) isonicotinohydrazide, in high yields, after several minutes, as reported. These new compounds have shown antitumor activity against two kinds of cancer cells, which are K562 (human chronic myeloid leukemia) and Jurkat (human T lymphocyte carcinoma)

    Long term effect of a school based intervention to prevent chronic diseases in Tunisia, 2009-2015

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    Background & Objectives: We aimed to evaluate the long term effect of school based intervention to prevent non- communicable disease risk factors.Methods: It was a quasi experimental study conducted during the period of 2009-2015. We involved school children aged from 11 to 16 years old. For the assessment of the program’s effectiveness, subjects in both groups were examined at baseline, at the end of the 3-year intervention period and at the follow-up, one year after program’s cessation.Results: In the intervention group, the prevalence of school children who reported to be eating 5 fruits and vegetable sdaily increased significantly from 30.0% at pre-assessment to 33.2% at post-assessment, one year after (p=0.02, p=0.41 respectively). For the control group, this prevalence had significantly decreased from 40.2% at baseline to 35.0% at post-intervention, at the follow up, this proportion increased to 44.5%(p=0.001, p<10-3 respectively). Concerning smoking habits, we observed a decreasing trend in the intervention group from 5.7% at pre-assessment, to 4.8% at post-assessment and to 3.4% at the follow-up (p=0.19 and p=0.25 respectively). There was also a significant decrease in school children who did recommended physical activity in the same group.Conclusion: The present work showed that interventions promoting healthy lifestyles should be maintained. Developing countries should be encouraged and supported to design, conduct, and evaluate robust preventive interventions.Keywords: Schools, lifestyle, intervention

    Area-Efficient Hardware Implementation of the Optimal Ate Pairing over BN curves.

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    To have an efficient asymmetric key encryption scheme such as elliptic curves, hyperelliptic curves, pairing etc., we have to go through an arithmetic optimization then a hardware one. Taking into consideration restricted environments’ compromises, we should strike a balance between efficiency and memory resources. For this reason, we studied the mathematical aspect of pairing computation and gave new development of the methods that compute the hard part of the final exponentiation in [2]. They prove that these new methods save an important number of temporary variables, and they are certainly faster than the existing one. In this paper, we will also present a new way of computing Miller loop, more precisely in the doubling algorithm. So we will use this result and the arithmetic optimization presented in [2]. Then, we will apply hardware optimization to find a satisfactory design which give the best compromise between area occupation and execution time. Our hardware implementation on a Virtex-6 FPGA(XC6VHX250T) used only 5976 Slices, 30 DSP, which is less resources used compared with state-ofthe-art hardware implementations, so we can say that our approach cope with the limited resources of restricted environmen

    On Computing the Multidimensional Scalar Multiplication on Elliptic Curves

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    A multidimensional scalar multiplication (d-mul) consists of computing [a1]P1+⋯+[ad]Pd[a_1]P_1+\cdots+[a_d]P_d, where dd is an integer (d≥2)d\geq 2), α1,⋯ ,αd\alpha_1, \cdots, \alpha_d are scalars of size l∈N∗l\in \mathbb{N}^* bits, P1,P2,⋯ ,PdP_1, P_2, \cdots, P_d are points on an elliptic curve EE. This operation (d-mul) is widely used in cryptography, especially in elliptic curve cryptographic algorithms. In fact, it is utilized in the digital signature verification algorithm (ECDSA), proving and verification algorithms such as the Succinct Non interactive Argument of Knowledge (zkSNARK) protocol, and in isogeny based post-quantum cryptosystems. Several methods in the literature allow to compute the d-mul efficiently (e.g., the bucket method, the Karabina et al. method). This paper aims to present and compare the most recent and efficient methods in the literature for computing the d-mul operation in terms of with, complexity, memory consumption, and proprieties. We will also present our work on the progress of the optimisation of d-mul in two methods. The first method is useful if 2d−12^d-1 points of EE can be stored. It is based on a simple precomputation function. The second method works efficiently when dd is large and 2d−12^d-1 points of EE can not be stored. It performs the calculation on the fly without any precomputation. We show that our first method is 100(1−1d)%100(1-\frac{1}{d})\% more efficient, while our second exhibits a 50%50\% improvement in efficiency. These improvements will be substantiated by assessing the number of operations and practical implementation

    The use of pairings in asymetric cryptography for micro-electronics

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    Les couplages sont des outils mathématiques introduits par André Weil en 1948. Ils sont un sujet très en vogue depuis une dizaine d'années en cryptographie asymétrique. Ils permettent en effet de réaliser des opérations cryptographiques impossible à réaliser simplement autrement tel que la signature courte et la cryptographie basée sur l'identité. Ces dernières années, le calcul des couplages est devenu plus facile grâce à l'introduction de nouvelles méthodes de calculs mathématiques particulièrement efficaces sur les courbes elliptiques dites les courbes bien adaptées aux couplages. Aujourd'hui, nous sommes au stade de transfert de cette technologie, de la théorie vers la mise en œuvre pratique, sur des composants électroniques. Ce transfert soulève de nombreuses problématiques qui s'avèrent difficile à surmonter à cause de la différence de culture scientifique entre mathématiciens et micro-électroniciens. Dans le présent document, en premier lieu, nous avons étudié le problème de l'implémentation du couplage dans des environnements restreints. En effet, le calcul du couplage de Tate, ou aussi de l'une de ses variantes, nécessite plusieurs variables pour être implémenté, par conséquent, il nécessite une bonne partie de la mémoire du composant électronique sur lequel nous souhaitons implémenter un tel couplage.Dans ce contexte, en faisant des optimisations mathématiques, nous avons pu implémenté ces couplages dans des environnements retreints. Le deuxième problème que nous avons traité dans cette thèse est celui de la sécurité des protocoles cryptographiques basés sur les couplages. Dans ce contexte, puisque les couplages sur les courbes elliptiques sont censés d'être matériellement attaqués, nous devons le protéger contre ces attaques. Nous avons étudié les attaques sur les couplages et nous avons proposé une contre-mesure.Les couplages sont des outils mathématiques introduits par André Weil en 1948. Ils sont un sujet très en vogue depuis une dizaine d'années en cryptographie asymétrique. Ils permettent en effet de réaliser des opérations cryptographiques impossible à réaliser simplement autrement tel que la signature courte et la cryptographie basée sur l'identité. Ces dernières années, le calcul des couplages est devenu plus facile grâce à l'introduction de nouvelles méthodes de calculs mathématiques particulièrement efficaces sur les courbes elliptiques dites les courbes bien adaptées aux couplages. Aujourd'hui, nous sommes au stade de transfert de cette technologie, de la théorie vers la mise en œuvre pratique, sur des composants électroniques. Ce transfert soulève de nombreuses problématiques qui s'avèrent difficile à surmonter à cause de la différence de culture scientifique entre mathématiciens et micro-électroniciens. Dans le présent document, en premier lieu, nous avons étudié le problème de l'implémentation du couplage dans des environnements restreints. En effet, le calcul du couplage de Tate, ou aussi de l'une de ses variantes, nécessite plusieurs variables pour être implémenté, par conséquent, il nécessite une bonne partie de la mémoire du composant électronique sur lequel nous souhaitons implémenter un tel couplage.Dans ce contexte, en faisant des optimisations mathématiques, nous avons pu implémenté ces couplages dans des environnements retreints. Le deuxième problème que nous avons traité dans cette thèse est celui de la sécurité des protocoles cryptographiques basés sur les couplages. Dans ce contexte, puisque les couplages sur les courbes elliptiques sont censés d'être matériellement attaqués, nous devons le protéger contre ces attaques. Nous avons étudié les attaques sur les couplages et nous avons proposé une contre-mesure
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