Le présent travail de Doctorat porte sur l’adaptation et le déconditionnement cardiovasculaire chez l’astronaute en microgravité réelle prolongée, en microgravité simulée de courte durée (avec et sans contremesures par hypergravité), et en confinement de longue durée. Afin de répondre à cette thématique, 3 études expérimentales sur l’humain ont été réalisées, et de fait, ce présent travail de Doctorat se divise en 3 parties distinctes. La première est la mission « Mars 500 » qui comprend un confinement de 520 jours de 6 sujets-volontaires. La seconde est le projet « Vessel Imaging » qui comprend un vol spatial respectif de 6 mois à bord de la « Station Spatiale Internationale (ISS) » de 10 sujets-astronautes. La troisième est l’étude «Short Time Bed-Rest (STBR)» (12 sujets) qui comprend une courte période de microgravité simulée par alitement prolongé à -6° (5 jours) avec et sans l’utilisation de deux contremesures cardiovasculaires par hypergravité (continue ou intermittente). / This PhD work focuses on astronaut cardiovascular adaptation and deconditioning in real prolonged microgravity, short simulated microgravity (with and without countermeasures) and long-term confinement. To answer to this topic 3 humans experimental studies have been performed, and thus the present PhD work is divided into 3 distinct parts . The first one is the mission « Mars 500 » which consists in 520-days confinement with 6 subjects-volunteers mission. The second is the project « Vessel Imaging » whitch consit in a 6-months spaceflight aboard the « International Space Station » with 10 subjects-astronauts. The third is the « Short Time Bed -Rest (STBR) » study (12 subjects) which consist in a short period of bedrest (-6°, 5 days) with and without the use of two cardiovascular countermeasures by hypergravity (continuous or intermittent).

The mobility attribute of a mobile agent implies deployment thereof in untrustworthy environments, which introduces malicious host threats. The research question deals with how a security framework could be constructed to address the mentioned threats without introducing high costs or restraining the mobile agent's autonomy or performance. Available literature have been studied, analysed and discussed. The salient characteristics as well as the drawbacks of current solutions were isolated. Through this knowledge a dynamic mobile agent security framework was defined. The framework is based on the definition of multiple security levels, depending on type of deployment environment and type of application. A prototype was constructed and tested and it was found to be lightweight and efficient, giving developers insight into possible security threats as well as tools for maximum protection against malicious hosts. The framework outperformed other frameworks / models as it provides dynamic solutions without burdening a system with unnecessary security gadgets and hence paying for it in system cost and performance / Computing / D.Phil.

Cette thèse aborde la conception et les contremesures permettant d'améliorer le calcul cryptographique matériel léger. Parce que la cryptographie (et la cryptanalyse) sont de nos jours de plus en plus omniprésentes dans notre vie quotidienne, il est crucial que les nouveaux systèmes développés soient suffisamment robustes pour faire face à la quantité croissante de données de traitement sans compromettre la sécurité globale. Ce travail aborde de nombreux sujets liés aux implémentations cryptographiques légères. Les principales contributions de cette thèse sont : - Un nouveau système d'accélération matérielle cryptographique appliqué aux codes BCH ; - Réduction de la consommation des systèmes embarqués et SoCs ; - Contre-mesures légères des attaques par canal auxiliaire applicables à l'algorithme de chiffrement reconfigurable AES ;- CSAC : Un pare-feu sécurisé sur la puce cryptographique ; - Attaques par analyse fréquentielle ; - Un nouveau protocole à divulgation nulle de connaissance appliquée aux réseaux de capteurs sans fil ; - OMD : Un nouveau schéma de chiffrement authentifié. / This thesis addresses lightweight hardware design and countermeasures to improve cryptographic computation. Because cryptography (and cryptanalysis) is nowadays becoming more and more ubiquitous in our daily lives, it is crucial that newly developed systems are robust enough to deal with the increasing amount of processing data without compromising the overall security. This work addresses many different topics related to lightweight cryptographic implementations. The main contributions of this thesis are: - A new cryptographic hardware acceleration scheme applied to BCH codes; - Hardware power minimization applied to SoCs and embedded devices; - Timing and DPA lightweight countermeasures applied to the reconfigurable AES block cipher; - CSAC: A cryptographically secure on-chip firewall; - Frequency analysis attack experiments; - A new zero-knowledge zero-knowledge protocol applied to wireless sensor networks; - OMD: A new authenticated encryption scheme.

This diploma thesis deals with implementation of the information security management system in company. The theoretical part of thesis summarizes the theoretical knowledge in the field of information security and describes a set of standards ISO/IEC 27000. In the following section the specific company is analysed, and to this company there are then applied theoretical knowledge during the implementation of information security management system.

Bone loss and muscle atrophy are two main physiological conditions affecting astronauts while being in space. In order to counteract the effects, at least two hours of aerobic and resistant countermeasure exercise is scheduled into their working day, seven days a week. Yoyo Technology AB has developed a resistance exercise device based on the flywheel principle, providing a load independent of gravity. However, there is no biomechanical research done on the efficiency of the device in microgravity, from a human movement point of view using simulation software. The aim of this thesis was to evaluate the effects of performing a leg press on the flywheel exercise device in a microgravity environment. Simulations of performing a flywheel leg press in earth gravity, microgravity and performing a conventional squat were done. The evaluated parameters were reaction forces, joint angles, joint moments, joint powers and muscle recruitment in the lower extremities. The simulations were done using a biomechanical simulation software based on a motion capture data collection. From the results two conclusions were proposed. Performing a flywheel leg press in microgravity environment or on earth provides at least as much peak moment as a body weighted squat performed on earth. Furthermore, performing a flywheel leg press in microgravity will induce a higher activity level among hip extensors and knee flexors compared to performing a flywheel leg press on earth.

Les SIEMs (systèmes pour la Sécurité de l'Information et la Gestion des Evénements) sont le cœur des centres opérationnels de sécurité actuels. Les SIEMs corrèlent les événements en provenance de différents capteurs (anti-virus, pare-feux, systèmes de détection d'intrusion, etc), et offrent des vues synthétiques pour la gestion des menaces ainsi que des rapports de sécurité. La recherche dans les technologies SIEM a toujours mis l'accent sur la fourniture d'une interprétation complète des menaces, en particulier pour évaluer leur importance et hiérarchiser les réponses. Toutefois, dans de nombreux cas, la réponse des menaces a encore besoin de l'homme pour mener l'analyse et aboutir à la prise de décisions, p.ex. compréhension des menaces, définition des contremesures appropriées ainsi que leur déploiement. Il s'agit d'un processus lent et coûteux, nécessitant un haut niveau d'expertise, qui reste néanmoins sujet à erreurs. Ainsi, des recherches récentes sur les SIEMs ont mis l'accent sur l'importance et la capacité d'automatiser le processus de sélection et le déploiement des contremesures. Certains auteurs ont proposé des mécanismes automatiques de réponse, comme l'adaptation des politiques de sécurité pour dépasser les limites de réponses statiques ou manuelles. Bien que ces approches améliorent le processus de réaction (en le rendant plus rapide et/ou plus efficace), ils restent limités car ces solutions n'analysent pas l'impact des contremesures choisies pour atténuer les attaques. Dans cette thèse, nous proposons une nouvelle approche systématique qui sélectionne la contremesure optimale au travers d'un ensemble de candidats, classés sur la base d'une comparaison entre leur efficacité à arrêter l'attaque et leur capacité à préserver, simultanément, le meilleur service aux utilisateurs légitimes. Nous proposons également un modèle pour représenter graphiquement les attaques et les contre-mesures, afin de déterminer le volume de chaque élément dans un scénario de multiples attaques. Les coordonnées de chaque élément sont dérivés d'un URI . Ce dernier est composé principalement de trois axes : l’utilisateur, le canal et le ressource. Nous utilisons la méthodologie CARVER pour donner un poids approprié à chaque élément composant les axes de notre système de coordonnées. Cette approche nous permet de connecter les volumes avec les risques (p.ex. des grands volumes sont équivalents à des risques élevés, tandis que des petits volumes sont équivalents à des risques faibles). Deux concepts sont considérés en comparant deux ou plusieurs volumes de risques: le risque résiduel, qui résulte lorsque le volume du risque est plus élevé que le volume de la contre-mesure, et le dommage collatéral, qui en résulte lorsque le volume de la contre-mesure est supérieur au volume du risque. En conséquence, nous sommes en mesure d'évaluer les contre-mesures pour des scénarios d'attaques individuelles et multiples, ce qui permet de sélectionner la contre-mesure ou groupe de contre-mesures qui fournit le plus grand bénéfice à l'organisation / Current Security Information and Event Management systems (SIEMs) constitute the central platform of modern security operating centers. They gather events from various sensors (intrusion detection systems, anti-virus, firewalls, etc.), correlate these events, and deliver synthetic views for threat handling and security reporting. Research in SIEM technologies has traditionally focused on providing a comprehensive interpretation of threats, in particular to evaluate their importance and prioritize responses accordingly. However, in many cases, threat responses still require humans to carry out the analysis and decision tasks e.g., understanding the threats, defining the appropriate countermeasures and deploying them. This is a slow and costly process, requiring a high level of expertise, and remaining error-prone nonetheless. Thus, recent research in SIEM technology has focused on the ability to automate the process of selecting and deploying countermeasures. Several authors have proposed automatic response mechanisms, such as the adaptation of security policies, to overcome the limitations of static or manual response. Although these approaches improve the reaction process (making it faster and/or more efficient), they remain limited since these solutions do not analyze the impact of the countermeasures selected to mitigate the attacks. In this thesis, we propose a novel and systematic process to select the optimal countermeasure from a pool of candidates, by ranking them based on a trade-off between their efficiency in stopping the attack and their ability to preserve, at the same time, the best service to normal users. In addition, we propose a model to represent graphically attacks and countermeasures, so as to determine the volume of each element in a scenario of multiple attacks. The coordinates of each element are derived from a URI. This latter is mainly composed of three axes: user, channel, and resource. We use the CARVER methodology to give an appropriate weight to each element composing the axes in our coordinate system. This approach allows us to connect the volumes with the risks (i.e. big volumes are equivalent to high risk, whereas small volumes are equivalent to low risk). Two concepts are considered while comparing two or more risk volumes: Residual risk, which results when the risk volume is higher than the countermeasure volume; and Collateral damage, which results when the countermeasure volume is higher than the risk volume. As a result, we are able to evaluate countermeasures for single and multiple attack scenarios, making it possible to select the countermeasure or group of countermeasures that provides the highest benefit to the organization

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<p dir="ltr">The proliferation of internet-connected embedded devices in contemporary computing environments has raised significant concerns regarding data security and confidentiality. Most embedded devices rely on computationally secure cryptographic algorithms to address these imperatives. However, despite the mathematical assurances, the physical implementation of these algorithms introduces vulnerabilities. Specifically, side-channel analysis (SCA) attacks exploit information leakage through various channels, including power consumption, electromagnetic (EM) radiation, timing, cache hits and misses, and other observable characteristics. </p><p dir="ltr">Previous research has introduced the concept of attenuating information-sensitive signatures using an analog cascoded current source for power delivery, coupled with an analog biased PMOS-based local negative feedback mechanism to stabilize the internal node. While this approach achieves robust signature suppression, resulting in higher minimum traces to disclosure (MTD) and enhanced security, it remains limited by its analog nature, making it less adaptable across different technology nodes. This thesis proposes a digital-friendly signature suppression technique that employs a digital cascoded current source and leverages a Ring-oscillator-based bleed path. These digital countermeasures can be further enhanced through time-domain obfuscation techniques. Our work demonstrates a state-of-the-art MTD of 1.25 billion traces for an AES-256 implementation. However, these countermeasures lack provable security guarantees, so continuous stress testing is essential for widespread deployment. Different intelligent attacks can be exploited on these physical countermeasures. Notably, this thesis also presents an intelligent attack on signature attenuation-based physical countermeasures and introduces an attack detector. Developing an intelligent attack detector is an integral part of the commercial adoption of physical countermeasures. </p><p dir="ltr">Next, generic physical countermeasures are often deployed in the $V_{DD}$ port as power side channel analysis is carried out through the $V_{DD}$ port. However, any digital circuit has two standard ports, namely $V_{DD}$ and clock port, and countermeasure through the clock port is mainly unexplored except for the system-level clock randomization technique. Even the clock-randomization technique is rendered ineffective in the presence of post-processing techniques. This thesis introduces a side channel resilience technique by introducing a larger slew at the clock, thereby improving MTD by $100\times$.</p><p dir="ltr">Next, these physical countermeasures do not come with any provable security guarantee. Hence, it is important to stress-test the countermeasures. This thesis does so and finds an exploitable point to reduce MTD by 1000$\times$. An attack detector of such an attack is also proposed.</p><p dir="ltr">Further, an attack detection strategy against side-channel analysis (SCA) or fault injection attacks (FIA) is also required. A detection and mitigation approach often gives us the option of duty-cycled countermeasures, hence reducing the energy overhead. This thesis proposes and analyzes a self-aware inductive loop-based attack detection strategy to detect SCA and FIA and enhance the signature attenuation countermeasures. </p><p dir="ltr">Finally, we explore opportunities for integrating these lightweight generic techniques into recently standardized Post-Quantum Cryptographic (PQC) cores. Specifically, we present an optimized implementation of the Saber PQC core, a NIST standardization finalist, achieving the lowest area and energy consumption. Future work could involve deploying lightweight PQC cores with synthesizable physical countermeasures to enhance security against quantum algorithms and physical side-channel attacks.</p>

Le premier protocole cryptographique basé sur les codes correcteurs d'erreurs a été proposé en 1978 par Robert McEliece. La cryptographie basée sur les codes est dite post-quantique car il n'existe pas à l'heure actuelle d'algorithme capable d'attaquer ce type de protocoles en temps polynomial, même en utilisant un ordinateur quantique, contrairement aux protocoles basés sur des problèmes de théorie des nombres. Toutefois, la sécurité du cryptosystème de McEliece ne repose pas uniquement sur des problèmes mathématiques. L'implantation, logicielle ou matérielle, a également un rôle très important pour sa sécurité et l'étude de celle-ci face aux attaques par canaux auxiliaires/cachés n'a débuté qu'en 2008. Des améliorations sont encore possibles. Dans cette thèse, nous proposons de nouvelles attaques sur le déchiffrement du cryptosystème de McEliece, utilisé avec les codes de Goppa classiques, ainsi que des contre-mesures correspondantes. Les attaques proposées sont des analyses de temps d'exécution ou de consommation d'énergie. Les contre-mesures associées reposent sur des propriétés mathématiques et algorithmiques. Nous montrons qu'il est essentiel de sécuriser l'algorithme de déchiffrement en le considérant dans son ensemble et non pas seulement étape par étape / The first cryptographic protocol based on error-correcting codes was proposed in 1978 by Robert McEliece. Cryptography based on codes is called post-quantum because until now, no algorithm able to attack this kind of protocols in polynomial time, even using a quantum computer, has been proposed. This is in contrast with protocols based on number theory problems like factorization of large numbers, for which efficient Shor's algorithm can be used on quantum computers. Nevertheless, the McEliece cryptosystem security is based not only on mathematical problems. Implementation (in software or hardware) is also very important for its security. Study of side-channel attacks against the McEliece cryptosystem have begun in 2008. Improvements can still be done. In this thesis, we propose new attacks against decryption in the McEliece cryptosystem, used with classical Goppa codes, including corresponding countermeasures. Proposed attacks are based on evaluation of execution time of the algorithm or its power consumption analysis. Associate countermeasures are based on mathematical and algorithmic properties of the underlying algorithm. We show that it is necessary to secure the decryption algorithm by considering it as a whole and not only step by step