Full-sky CMB lensing reconstruction in presence of sky-cuts

We consider the reconstruction of the CMB lensing potential and its power spectrum of the full sphere in presence of sky-cuts due to point sources and Galactic contaminations. Those two effects are treated separately. Small regions contaminated by point sources are filled in using Gaussian constrained realizations. The Galactic plane is simply masked using an apodized mask before lensing reconstruction. This algorithm recovers the power spectrum of the lensing potential with no significant bias.Comment: Submitted to A&

Broadcast Encryption using Sum-Product decomposition of Boolean functions

The problem of Broadcast Encryption (BE) consists in broadcasting an encrypted message to a large number of users or receiving devices in such a way that the emitter of the message can control which of the users can or cannot decrypt it. Since the early 1990\u27s, the design of BE schemes has received significant interest and many different concepts were proposed. A major breakthrough was achieved by Naor, Naor and Lotspiech (CRYPTO 2001) by partitioning cleverly the set of authorized users and associating a symmetric key to each subset. Since then, while there have been many advances in public-key based BE schemes, mostly based on bilinear maps, little was made on symmetric cryptography. In this paper, we design a new symmetric-based BE scheme, named $\Sigma\Pi$BE, that relies on logic optimization and consensual security assumptions. It is competitive with the work of Naor et al. and provides a different tradeoff: the bandwidth requirement is significantly lowered at the cost of an increase in the key storage

Broadcast Encryption using Sum-Product decomposition of Boolean functions

The problem of Broadcast Encryption (BE) consists in broadcasting an encrypted message to a large number of users or receiving devices in such a way that the emitter of the message can control which of the users can or cannot decrypt it. Since the early 1990s, the design of BE schemes has received significant interest and many different concepts were proposed. A major breakthrough was achieved by Naor, Naor and Lotspiech (CRYPTO 2001) by partitioning cleverly the set of authorized users and associating a symmetric key to each subset. Since then, while there have been many advances in public-key based BE schemes, mostly based on bilinear maps, little was made on symmetric cryptography. In this paper, we design a new symmetric-based BE scheme, named $\Sigma\Pi$BE, that relies on logic optimization and consensual security assumptions. It is competitive with the work of Naor et al. and provides a different tradeoff: the bandwidth requirement is significantly lowered at the cost of an increase in the key storage. </p

Les Organisations de la Société Civile et la Lutte Contre la Pauvreté en Afrique Subsaharienne

The paper presents the role played by civil society organisations to bring down the poverty

Nanomechanical testing for crystal plasticity constitutive framework identification at high strain rates

Shot-Peening (SP) is a surface mechanical treatment that consists in propelling hard particles, called shot, onto a ductile metallic surface at high velocity to induce subsurface residual compressive stresses. It is widely used in the industry to increase fatigue life and wear resistance of treated parts. Shot-peening induced macroscopic residual stresses (e.g. Type I) predictions using finite element analysis or analytical method is today already well assessed. However, recent works [1] revealed that spherical indentation in specific crystal orientations could induce subsurface intragranular tensile stresses. In the shot-peening context, such intra-granular (e.g. Type III) residual stresses could influence structure’s High Cycle Fatigue (HCF) behavior and macroscopic residual stresses stability over the load cycles It would also favor early stage plasticity and crack initiation. Shot-peening simulations at the crystal scale would therefore provide essential quantitative inputs for treated parts fatigue life prediction. Such simulations require to select relevant constitutive frameworks representing the crystal behavior at high strain rate (up to 106 s-1) and accounting for repeated impact induced cyclic effects. Also, identification of such behavior will require mechanical tests at the crystal scale under process-representative test conditions. In the present work, a new methodology for crystal plasticity inverse identification for large strain rate ranges is developed. It relies on high-strain rate micropillar compression tests performed with a recently developed nano-indenter test apparatus [2], at strain rates up to 102 s-1. Micropercussion induced residual imprints are also experimentally generated to provide material behavior inputs at higher strain rates. Both tests are combined for inverse identification of two different crystal plasticity constitutive frameworks for copper. Unicity and stability of the given coefficients are studied using cost function plots and an identifiability indicator developed by Renner et al. [3]. Further works will focus on high strain rates Berkovich indentation tests to complete the developed methodology. Experimental data will also be generated at higher strain rates and for repeated impacts, using a currently developed impact shot gun that will propel shots at shot-peening velocity with a spatial accuracy of . [1] S. Breumier, A. Villani, C. Maurice et M. &. K. G. Lévesque, «Effect of crystal orientation on indentation-induced residual stress field: simulation and experimental validation,» Materials & Design, vol. 169, 2019. [2] G. Guillonneau, M. Mieszala, J. Wehrs, J. Schwiedrzik, S. Grop, D. Frey, L. Philippe, J.-M. Breguet, J. Michler et J. Wheeler, «Nanomechanical testing at high strain rates: New instrumentation for nanoindentation and microcompression,» Materials & Design, vol. 148, pp. 39-48, 2018. [3] E. Renner, Y. Gaillard, F. Richard, F. Amiot et P. Delobelle, «Sensitivity of the residual topography to single crystal plasticity parameters in Berkovich nanoindentation on FCC nickel,» International Journal of Plasticity, vol. 77, pp. 118 - 140, 2016

Inorganic fillers influence on the radiation-induced ageing of a space-used silicone elastomer

A space-used filled silicone rubber (silica and iron oxide fillers) and its polysiloxane isolated matrix were exposed to high energy electrons in order to determine their ageing mechanisms from a structural point of view. Physicochemical analysis evidenced that both filled and unfilled materials predominantly crosslink under such irradiation. Solid-state 29Si NMR spectroscopy allowed the identification of T-type SiO3 units as the main new crosslinks formed in the polymer network. It also revealed an increase in Qtype SiO4 units in the irradiated filled sample. Thanks to the combination of NMR spectroscopy and ammonia-modified swelling tests, these Q-type units were associated with new crosslinks formed at the silica fillers-matrix interface. While the main interaction between the polysiloxane network and the fillers was shown to proceed mainly through hydrogen bonding in the pristine filled samples, it was suggested that the hydrogen bonds were progressively replaced with SiO4 chemical bonds. These additional chemical crosslinks induced evolutions of the shear modulus on the rubber plateau and crosslink density that were significantly more pronounced in the filled material than in the neat one

A Thermo‐ and mechanoresponsive cyano‐substituted oligo(p‐phenylene vinylene) derivative with five emissive states

Multiresponsive materials that display predefined photoluminescence color changes upon exposure to different stimuli are attractive candidates for advanced sensing schemes. Herein, we report a cyano-substituted oligo(p-phenylene vinylene) (cyano-OPV) derivative that forms five different solvent-free solid-state molecular assemblies, luminescence properties of which change upon thermal and mechanical stimulation. Single-crystal X-ray structural analysis suggested that tolyl groups introduced at the termini of solubilizing side-chains of the cyano-OPV play a pivotal role in its solid-state arrangement. Viewed more broadly, this report shows that the introduction of competing intermolecular interactions into excimer-forming chromophores is a promising design strategy for multicolored thermo- and mechanoresponsive luminescent materials

DolphinAtack: Inaudible Voice Commands

Speech recognition (SR) systems such as Siri or Google Now have become an increasingly popular human-computer interaction method, and have turned various systems into voice controllable systems(VCS). Prior work on attacking VCS shows that the hidden voice commands that are incomprehensible to people can control the systems. Hidden voice commands, though hidden, are nonetheless audible. In this work, we design a completely inaudible attack, DolphinAttack, that modulates voice commands on ultrasonic carriers (e.g., f > 20 kHz) to achieve inaudibility. By leveraging the nonlinearity of the microphone circuits, the modulated low frequency audio commands can be successfully demodulated, recovered, and more importantly interpreted by the speech recognition systems. We validate DolphinAttack on popular speech recognition systems, including Siri, Google Now, Samsung S Voice, Huawei HiVoice, Cortana and Alexa. By injecting a sequence of inaudible voice commands, we show a few proof-of-concept attacks, which include activating Siri to initiate a FaceTime call on iPhone, activating Google Now to switch the phone to the airplane mode, and even manipulating the navigation system in an Audi automobile. We propose hardware and software defense solutions. We validate that it is feasible to detect DolphinAttack by classifying the audios using supported vector machine (SVM), and suggest to re-design voice controllable systems to be resilient to inaudible voice command attacks.Comment: 15 pages, 17 figure

Modular Polynomial Multiplication Using RSA/ECC coprocessor

Modular polynomial multiplication is a core and costly operation of ideal lattice-based schemes. In the context of embedded devices, previous works transform the polynomial multiplication to an integer one using Kronecker substitution. Then thanks to this transformation, existing coprocessors which handle large-integer operations can be re-purposed to speed-up lattice-based cryptography. In a nutshell, the Kronecker substitution transforms by evaluation the polynomials to integers, multiplies it with an integer multiplication and gets back to a polynomial result using a radix conversion. The previous work focused on optimization of the integer multiplication using coprocessor instructions. In this work, we pursue the seminal research by optimizing the evaluation, radix conversion and the modular reductions modulo q with today\u27s RSA/ECC coprocessor. In particular we show that with a RSA/ECC coprocessor that can compute addition/subtraction, (modular) multiplication, shift and logical AND on integers, we can compute the whole modular polynomial multiplication using coprocessor instructions. The efficiency of our modular polynomial multiplication depends on the component specification and on the cryptosystem parameters set. Hence, we assess our algorithm on a chip for several lattice-based schemes, which are finalists of the NIST standardization. Moreover, we compare our modular polynomial multiplication with other polynomial multiplication techniques