Practical Algebraic Attacks on the Hitag2 Stream Cipher in RFID Transponders

Talk given at eSmart 2010. How to attack the Hitag2 cipher in RFID trannsponders

On the absence of Shapiro-like steps in certain mesoscopic S-N-S junctions

In DC transport through mesoscopic S-N-S junctions, it is known that the Josephson coupling decreases exponentially with increasing temperature, but the phase dependence of the conductance persists to much higher temperatures and decreases only as 1/T. It is pointed out here that, despite the fact that such a phase-dependent conductance does bring about an AC current for a pure DC voltage, it cannot, by itself, lead to the formation of Shapiro steps.Comment: 1 page, to be published in PRL (as Comment

Calorimetric readout of a superconducting proximity-effect thermometer

A proximity-effect thermometer measures the temperature dependent critical supercurrent in a long superconductor - normal metal - superconductor (SNS) Josephson junction. Typically, the transition from the superconducting to the normal state is detected by monitoring the appearance of a voltage across the junction. We describe a new approach to detect the transition based on the temperature increase in the resistive state due to Joule heating. Our method increases the sensitivity and is especially applicable for temperatures below about 300 mK.Comment: 10 pages, 5 figures. To appear in the proceedings of the Conference on Micro- and Nanocryogenics (LT25 satellite) organized in Espoo, Finland (2008

Long-term change in nutritional status after severe traumatic brain injury

IntroductionIn the acute phase, patients who sustained a severe Traumatic Brain injury (TBI) (Glasgow Coma Scale under 8) frequently present malnutrition during critical care. Long-term nutritional outcome after a severe TBI has been less studied. Cognitive impairments and behavioural disorders together with hormonal disorders can lead to persisting malnutrition or over-eating and obesity. The purpose of this study was to follow the weight, the body mass index (BMI), albuminemia and hormonal dosage after a severe TBI.MethodsThis study relied on a research protocol designed to follow concurrently and prospectively endocrine disorders and cognitive disorders in a cohort of patients with severe TBI (Inspire-TC protocol). In the present work, we focused specifically on the evolution in weight, height, body mass index, albuminemia and endocrine abnormalities. These parameters were collected upon admission to the rehabilitation department, at 4 months, 12 months and 18 months when feasible for the severe TBI patients included in the Inspire-TC protocol. Albuminaemia was measured late after the TBI when patients agreed.Results10 patients were included. Initially 60% of the patients had biological malnutrition, 10% were overweight, 80% presented a normal BMI and 10% had an insufficient BMI. All patients gained weight during the monitoring with an overweight at 18 months for three patients. Along the overall monitoring, 44% of the patients had hormonal disruptions. The 3 patients with long-term overweight had frontal-temporal brain lesions. All three recovered walking. Only one had hormonal disruptions. Albuminaemia was normal for all patients who accepted to make this bioessay control.ConclusionThere is a tendency to gain weight after a severe TBI. Favorable factors include fronto-temporal injuries, and the presence of executive disorders. Endocrine perturbation and immobility can also contribute to overweight but were less frequently observed in this cohort

Competition between electronic cooling and Andreev dissipation in a superconducting micro-cooler

We discuss very low temperature experiments on superconducting micro-coolers made of a double Normal metal - Insulator - Superconductor junction. We investigate with a high resolution the differential conductance of the micro-cooler as well as of additional probe junctions. There is an explicit crossover between the single quasi-particle current and the phase-coherent Andreev current. We establish a thermal model by considering the thermal contribution due to the Andreev current. The related increase of the electron temperature is discussed, including the influence of several parameters like the phase-coherence length or the tunnel junction transparency

First DENIS I-band extragalactic catalog

This paper presents the first I-band photometric catalog of the brightest galaxies extracted from the Deep Near Infrared Survey of the Southern Sky (DENIS) An automatic galaxy recognition program has been developed to build this provisional catalog. The method is based on a discriminating analysis. The most discriminant parameter to separate galaxies from stars is proved to be the peak intensity of an object divided by its array. Its efficiency is better than 99%. The nominal accuracy for galaxy coordinates calculated with the Guide Star Catalog is about 6 arcseconds. The cross-identification with galaxies available in the Lyon-Meudon Extragalactic DAtabase (LEDA) allows a calibraton of the I-band photometry with the sample of Mathewson et Al. Thus, the catalog contains total I-band magnitude, isophotal diameter, axis ratio, position angle and a rough estimate of the morphological type code for 20260 galaxies. The internal completeness of this catalog reaches magnitude $I_{lim}=14.5$, with a photometric accuracy of $\sim 0.18m$. 25% of the Southern sky has been processed in this study. This quick look analysis allows us to start a radio and spectrographic follow-up long before the end of the survey.Comment: 13 pages, 17 figures, to appear A&A Supl.

Generic Attacks and the Security of Quartz

Abstract. The signature scheme Quartz is based on a trapdoor function G that be-longs to a family called HFEv-. This function has the advantage to have two indepen-dent security parameters, and we claim that if d is big enough, no better method to compute an inverse of G than the exhaustive search is known. This paper looks at the security of Quartz under this (quite a strong) assumption. It allows a generic approach to the security of Quartz. We view it as a special case of a general construction called generalized Feistel-Patarin scheme, that transforms a trapdoor function into a short signature scheme. The main object of this paper is the concrete security of this general construction. On one hand, we present generic attacks on such schemes. On the other hand, we study the possibility to prove or justify the security with some well chosen assumptions. Unfortunately for Quartz, our lower and upper security bounds do not coincide. Still the best attack known for Quartz is our generic attack using O(280) computations with O(280) of memory. We will also propose an alternative way of doing short signatures, less general than the Feistel-Patarin scheme, but for which both bounds do coincide

Improved resolution in the position of drought-related QTLs in a single mapping population of rice by meta-analysis

Peer reviewedPublisher PD