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Moving code analysis from safety to security: taking the attacker model into account

Département Ingénierie Logiciels et Systèmes (LIST)

Laboratoire pour la Sûreté du Logiciel

SL-DRT-20-0741

sebastien.bardin@cea.fr

Cyber security : hardware and sofware (.pdf)

So-called formal techniques for automated program analysis have been proven highly successful over the past decade in the field of safety critical systems. A current Grand Challenge of formal verification is to scale to the security analysis of non-regulated programs. In code analyzers, code-level attackers are implicitly restricted to sending crafted messages. Yet, realistic attackers can do much worst, typically deduce or modify information during executions ? using for example pure hardware attacks (side channel attacks, fault injection) or mixed hardware/software attacks (e.g., Rowhammer, cache attacks, speculative attacks such as Spectre). The goal of this doctoral thesis is precisely to understand how relevant attacker models can be *efficiently* added to the standard program analysis framework. This requires to identify relevant attacker models (capacities, goals), and to formalize them in a way amenable to efficient code analysis.

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Development of a mobile multimodal imager for radiological characterization of complex environments

Département Métrologie Instrumentation et Information (LIST)

Laboratoire Capteurs et Architectures Electroniques

01-10-2020

SL-DRT-20-0744

vincent.schoepff@cea.fr

Factory of the future incl. robotics and non destructive testing (.pdf)

The mitigation of accidental situations such as Chernobyl or Fukushima requires the access to a radiological characterization of environment. Gamma imaging systems provide a solution of interest to address this requirement by allowing the remote visualization of irradiating hot spots through the superimposition of a gamma image onto a visible picture. CEA List is a first rank international actor in the development of gamma cameras for nuclear industry and Homeland Security applications (CARTOGAM, GAMPIX/iPIX and Nanopix gamma cameras). However, may they be based on coded aperture techniques or Compton imaging methods, current imaging systems are required to stay still during the whole acquisition step (from several seconds to minutes), in order to gather sufficient counting statistics for hot spot reconstruction. On the other hand, this reconstruction is achieved through the projection on a two-dimensional space, which makes results uneasy to interpret in case of a complexly crowded and degraded environment. The research project hereby proposed aims at addressing those limitations by allowing the localization of hot spots with a moving imager and implementing the reconstruction of superimposed images in a three-dimensional environment. To this aim, several research paths are proposed and could be coupled into a multimodal mobile imager for the characterization of radiologically degraded areas : the transposition of Compton imaging methods to a mobile referential, allowing the reconstruction by a moving system; the adaptation of tomography reconstruction algorithms for the localization of hot spots with their depth; and the construction of three-dimensional visible images via stereoscopy methods and images structure analysis for reconstructing the environment.

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Advanced chemical analysis of organic light emitting diodes

Département des Plateformes Technologiques (LETI)

Laboratoire Analyses de Surfaces et Interfaces

01-10-2020

SL-DRT-20-0748

jean-paul.barnes@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

The nanocharacterisation platform has recently installed several advanced characterisation techniques : a new time of flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectrometer (XPS). Both instruments are equipped with a novel argon cluster ion source that allows damage free analysis of organic layers such as those found in organic light emitting diodes (OLEDs). The lifetime of OLEDs may be limited by the electrical or environmental ageing or the organic layers contained in the device. For the development of OLEDs it is important to be able to characterise the degradation of organic layers. The objective of this PhD project is to develop the advanced TOF-SIMS and XPS protocols needed to quantify and understand the degradation of the layers. The development of specific sample preparation methods will be carried out in order to be able to analyse the same area of the sample using several different techniques. The candidate will work closely with the team at the CEA-LETI making the OLED devices and materials and the instrument suppliers.

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Critical buried interfaces in imaging devices studied by novel hard X-ray photoelectron spectroscopy techniques

Département des Plateformes Technologiques (LETI)

Laboratoire Analyses de Surfaces et Interfaces

01-10-2020

SL-DRT-20-0750

orenault@cea.fr

Advanced nano characterization (.pdf)

The development of advanced generic technologies such as imagers or memories requires a fine understanding on the properties of critical interfaces. To this end, implementing cutting-edge nanocharacterisation methods and instrumentation is of utmost importance. Here, we address the implementation of a novel X-ray photoelectron spectroscopy technique employing hard X-rays (HAXPES: HArd X-ray Photoelectron Spectroscopy) delivered by a Chromium source in a new kind of photoemission spectrometer recently installed at the Minatec PlatForm For Nanocharacterization, CEA-Grenoble. With this technique, the probing depth of conventional photoelectron spectroscopy is enhanced by a factor of 3-5, enabling to get access to deeply buried interfaces localized 20-50 nm below the surface, which is a typical situation in devices. The thesis work is organized around two aspects : a first one deals with the chemical state analysis of critical buried interfaces in imager devices and other thecnologies developped at ST Microelectronics. The second aspect is focused on interface electronics and in-depth potential distribution, especially targetting the determination of valence band offsets.

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Transparent piezoelectric actuators for haptic

Département Composants Silicium (LETI)

Labo Composants Micro-actuateurs

01-10-2020

SL-DRT-20-0756

gwenael.le-rhun@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

The haptic technology (science of touch) is in full rise and attracts more and more interest from industrials in the fields of telephony or automotive. Piezoelectric actuators are used to generate vibrations on a tactile surface to produce a haptic feedback, thus facilitating (or augmenting!) interactions between the user and his environment. Some tactile surfaces, such as screen, dashboard or window, would ideally require the use of transparent actuators. However, thin film piezoelectric actuators are deposited on a silicon substrate and incorporate non-transparent layers (electrodes, etc.). Strong technological constraints, such as the crystallization temperature of the piezoelectric material (around 700 °C for the PZT), make the thin film deposition of transparent piezoelectric stacks on glass particularly complex, or impossible. LETI has recently developed an innovative technology for transferring one or more layers, for example PZT, from a silicon growth substrate to a host substrate such as glass (several patents). The objective of this thesis will be to design and realize transparent piezoelectric actuators on glass substrate for a haptic application. A state of the art on the subject will make it possible to establish the targeted specifications for the chosen device. Based on the knowledge and expertise available at LETI, the PhD student will work on the integration of materials (piezoelectric, electrodes, etc ...) allowing in particular obtaining a functional stack with the required transparency, as well as on the design and the realization of the actuators and their characterizations.

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Microstructure control of additive manufacturing parts by generation and detection of ultrasound by laser

Département Imagerie Simulation pour le Contrôle (LIST)

Laboratoire Instrumentation et Capteurs

01-01-2020

SL-DRT-20-0757

jerome.laurent2@cea.fr

Additive manufacturing, new routes for saving materials (.pdf)

The metal additive manufacturing (AM) processes show a great potential still growing, and those in very varied applications fields. However, existing systems have limitations, in particular on the ability to adapt the microstructures and to detect online the melting defects [1]. To overcome these limitations, it is necessary to develop new manufacturing strategies that could make it possible to adapt the solidification conditions as well as online non-destructive testing (NDT) inspection methods. Direct energy deposition (DED) or selective laser melting (SLM) processes use metallic powder and a locally concentrated energy source, which generates strong thermal gradients, which most often lead to highly oriented microstructures and relatively rough surfaces, both making NDT inspection and physical interpretations more tricky. The microstructures produced are out of thermodynamic equilibrium and possess coarse grains structure; they are characterized by the entanglement of columnar and equiaxed grains. This type of microstructure influences significantly the mechanical behavior and elastic waves propagation; the size distribution of heterogeneities are close to the acoustic wavelengths, having for effect the attenuation and scattering of elastic waves. One of the major challenges in AM is to reduce/prevent the formation of columnar grains during manufacturing, as their presence within the microstructure is the most unfavorable for the use properties. By controlling the thermal conditions during the solidification/crystallization (cooling rate, temperature gradients), it is a priori possible to favorably induce the formation of equiaxed grains. It is also known that, by insonification of the molten metal with high intensity ultrasound, it is possible to perform a ?grain refinement-like?, or also to generate other effects (cavitation, flow, mixing, spraying, dislocation, scattering and phase transformation [2]). Indeed, when an elastic vibration is applied directly to molten metal, it would be possible to control-like the solidified grain structure, i.e. to change locally the direction of growth and morphology of the microstructure during the solidification phase. Therby perturbating the solidification conditions, then, it is conceivable to cause the formation of equiaxial grains, and, potentially, the number of flaws (microporosities, cracks). This observation sets the objective of this thesis, which aims to shape more optimally the AM microstructures by vibrating the melting pool and to conduct either offline or online monitoring by ultrasonic-laser (LU) technique. On the one hand, the work, in the CEA-DEN-LISL Lab. [3], will consist of controlling the microstructural evolution of AM parts by contactless vibration of the melting pool. Thus, it will seek to modify the dynamics of the melt, for example, by destabilizing the dendritic growth in the solidification front due to elastic waves generation with a continuous-wave modulated or pulsed laser source. The control parameters will be assessed in laboratory conditions using an existing experimental prototype, which will be improve by adding several other instruments (fast/thermal/Schlieren cameras, pyrometer) to generate ?enhanced microstructures? and by improving the coaxial manufacturing nozzle. On the other hand, the work in the CEA-DRT-LIST Lab., will consist to inspect online AM samples by employing a LU method. Thus, it will seek to generate and detect ultrasound by laser in the melt, to monitored, for example, the evolution of solidification front, keyhole outbreak, optical penetration evolution, and so on, by measuring acoustic precursors [4]. Ultrasonic characterization measurements, under laboratory conditions, will also be carried out in order to determine the elastic properties by LU [5], whether using surface waves (Rayleigh) or zero-group velocity modes (local Poisson's ratio, anisotropy, thickness), and other NDT methods available from the LIST lab., which can then be compared to EBSD (homogenization method) and metallurgical cuts. FDTD or Finite Elements simulations of ultrasound in these rough and heterogeneous media will also be considered. References: [1] Zhao et al, Phys. Rev. X, 9, 02052, (2019), Wolff et al, Sci. Rep., 9, 962, (2019), Martin et al., Nat. Com., 10, 1987, (2019), Wei, Mazumder & DebRoy, Sci. Rep., 5, 16446, (2015). [2] G. I. Eskin & D. G. Eskin, ?Ultrasonic melt treatment of light alloy melts', 2nd edn, Boca Raton, FL, CRC Press, (2014), M. C. Flemings, ?Solidification processing', McGraw-HilI press, (1974), T.T. Roehling et al., Acta Materialia 128, 197, (2017), M.J. Matthews et al., Optics Express 25, 11788, (2017). [3] P. Aubry et al., J. Laser Appl., 29(2), (2017) [4] Walter & Telschow, QNDE, 15, (1996), Walter, Telschow & Haun, Proc COM, (1999), Carlson and Johnson, WJ, (1998), He, Wu, Li & Hao, Appl. Phys. Lett., 89, (2006). [5] Clorennec, Prada & Royer, Murray, Appl. Phys. Lett., 89, (2006), Laurent, Royer & Prada, Wave Motion 51(6), (2014) Laurent, Royer, Hussain, Ahmad & Prada, J. Acoust. Soc. Am. 137(6), (2015).

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