One-Time Delegation of Unlinkable Signing Rights and Its Application

Delegation of signing rights can be useful to promote effective resource sharing and smooth cooperation among participants in distributed systems, and in many situations, we often need restricted delegation such as one-timeness and unlinkability rather than simple full delegation. Particularly, one-timesness cannot be achieved just by deploying cryptographic measures, and one needs to resort to some form of tamper-proofness or the assistance from external cloud servers for ``key-disabling\u27\u27. In this work, we extend the latter such that a delegatee can sign a message without the delegator\u27s involvement with the assumption that there exists at least one honest cloud server with secure erasure to achieve one-timeness. In this setting, if the delegator just shares their signing key between the delegatee and cloud servers, it may be problematic. It is because in the worst case, the delegator cannot know whether or not a signing key theft occurred because the signatures generated illegally are indistinguishable from the ones generated legally. To solve this, first we propose an efficient one-time delegation scheme of Okamoto-Schnorr signing. Further we combine the basic delegation scheme with anonymous credentials such that the delegator can detect the signing key theft even if one-time delegation is broken while also achieving unlinkability for both the delegator and cloud servers. Further we show its application to an e-cash scheme, which can prevent double-spending

Mechanical damage assessment of glass fibre-reinforced polymer composites using passive infrared thermography

This study deals with characterization of the damage and thermomechanical behavior of the Glass Fiber-Reinforced Polymer composite materials (GFRP), submitted to static tensile loadings, using a passive infrared thermography technique. During mechanical testing, thermal measurements are performed by means of an IR camera. The thermal data post-processing involves the analysis of both the thermal maps and the thermomechanical behavior of the material. The thermal maps analysis allows qualitative evaluation of the created material damage at high stress levels. While the thermomechanical analysis gave us a quantitative evaluation of the material damage, for both low and high stress levels, through definition of a new thermoelastic damage variable

Introducing reconfigurability and cognitive networks concepts in the wireless world

11scopu

Détermination des contraintes résiduelles par diffractométrie X des couches biphasées. Application au cas de la cémentation

L'objectif de ce travail est de déterminer par diffraction des rayons X les contraintes résiduelles dans les deux phases présentes en surface des aciers cémentés : la martensite et l'austénite résiduelle. Une caractérisation fondée sur la diffraction des rayons X (quantification de phases, mesures de paramètres de maille, contraintes résiduelles) permet d'obtenir des résultats nécessaires à la compréhension de la genèse des contraintes résiduelles de cémentation.The aim of this work is the X-ray determination of residual stresses in the two surface phases of carburized steels : martensite and retained austenite. A characterization, based on X-ray diffraction (retained austenite fraction, cell parameters measurements, residual stresses), allows the obtention of results which are necessary for the understanding of the residual stresses growth

Evaluation of Elastic Properties of Surface Layer from Rayleigh Wave Dispersion

This paper deals with the problem of determining subsurface elastic properties in non homogeneous layers from the measured dispersion of Rayleigh surface waves. The thermochemical treatments of steels such as carburizing or nitrurizing, produce a gradient of properties in the depth which is caused by carbon or nitrogen diffusion. These treatments are usually performed in the manufacture of automotive components (gear box, c.v. joint, hooke joint).</p