Altran

About: Altran is a company organization based out in Neuilly-sur-Seine, France. It is known for research contribution in the topics: Software development & Formal verification. The organization has 488 authors who have published 512 publications receiving 6395 citations.

Vulnerability Analysis of GPS Receiver Software

Abstract: Satellite navigation systems such as the Global Positioning System (GPS)makes it possible for users to find their relative or absolute position. Thanks to its mobility and reliability, the GPS is used in many civil and military applications. However, the GPS does not provide an advanced level of security. Therefore, it could be potentially a target of attacks. With the development of new GPS attacks, the security knowledge has to grow at the same rate, so existing attacks can be detected by updated versions of receiver software or hardware. In this paper, a comparative analysis of GPS receiver resilience to software attacks is performed with the help of GNSS simulator from Spirent. The main objective of this work is to perform a sensitivity analysis of variables involved in calculation of position of the GPS receivers from different price bands that might be targeted by existing or future GPS attack. Variables making the biggest impact on calculated position are determined using the model. Experimentation validation of their influence is performed using selected receivers and corrupted signals generated by GNSS simulator. The testing is based on tuning the selected variables in order to simulate the theoretical error obtained from the sensitivity analysis. The results obtained from testing are discussed in order to analyse the behaviour of the considered GNSS receivers (including the premium class ones)and establish whether they provide a protection from existing or potential GPS attacks.

Auditing User-Provided Axioms in Software Verification Conditions

Abstract: A common approach to formally checking assertions inserted into a program is to first generate verification conditions, logical sentences that, if then proven, ensure the assertions are correct. Sometimes users provide axioms that get incorporated into verification conditions. Such axioms can capture aspects of the program's specification or can be hints to help automatic provers. There is always the danger of mistakes in these axioms. In the worst case these mistakes introduce inconsistencies and verification conditions become erroneously provable. We discuss here our use of an SMT solver to investigate the quality of user-provided axioms, to check for inconsistencies in axioms and to verify expected relationships between axioms, for example.

Design of a moderated multidetector neutron spectrometer for optimal specificity

Abstract: Neutron spectrometry can play an important role in the detection and identification of neutron-emitting sources in various security applications. In the present work, a portable filtered array neutron spectrometer, consisting of twelve 6LiF-based thermal neutron detectors embedded within a single heterogeneous volume was designed and its expected performance compared to that of a commercially available 12-sphere Bonner spheres spectrometer. Each detector within the volume was designed to optimally respond to a unique portion of the neutron spectrum by varying the type and thickness of materials used to filter the spectrum as well as the thickness of the moderator in front of the detector. The available design space was permuted and performance metrics developed to identify the optimal geometries. The top performing detector geometries were then combinatorially explored to identify the best array of geometries that yielded the most information about a neutron spectrum. The best performing filtered array was found to provide as much spectral information as, or more than, the commercially available 12-sphere Bonner spheres spectrometer to which it was compared.

ISAR image segmentation by non linear diffusion equation

Abstract: This paper describes a non linear spatial filtering for the target radar segmentation of ISAR/SAR images. Since such images are usually corrupted by speckle noise and clutters, image processing technique are required in order to obtain a more clear image. We have implemented a spatial technique based on the non linear diffusion equation, also known as the Perona-Malik equation. Our model is based on an calculation of the spatial gradient on a 5/spl times/5 stencil in order to increase the merging of target corresponding regions. By suitably estimating a diffusion coefficient related parameter, the gradient threshold, target segmentation is done into few integration steps of the equivalent explicit scheme. The resulting images maintain most of the original details also visible in converting the filtered image in a binary format. The proposed method can be the first step of target classification by matching correlation of more advanced techniques.