Les systèmes embarqués sont utilisés dans de nombreux systèmes critiques, depuis les automobiles jusqu'aux les systèmes de contrôle industriels. La plupart des recherches sur ces systèmes embarqués se sont concentrés sur l'amélioration de leur fiabilité face à des fautes ou erreurs de fonctionnent non intentionnelles, moins de travaux on été réalisés considérant les attaques intentionnelles. Ces systèmes embarqués sont de plus en plus connectés, souvent à Internet, via des réseaux sans fils, par exemple pour leur administration à distance. Cela augmente les risques d'attaques à distance ou d'injection de code malicieux. Les fautes de fonctionnement de ces équipements peuvent causer des dommages physiques comme par example rendre des appareils médicaux dangereux. Par conséquent, il est primordial de protéger ces systèmes embarqués contre les attaques. Dans cette thèse nous présentons des attaques et défenses contre les systèmes embarqués contraints. Nous présentons plusieurs attaques contre des techniques d'attestation logicielle utilisées dans les systèmes embarqués. Puis nous présentons la conception et l'implémentation d'une technique d'attestation logicielle qui est résistante aux attaque présentées précédemment. Finalement, nous présentons la conception d'une solution permettant de réaliser l'attestation de code ainsi que la création d'une racine de confiance dynamique (dynamic root of trust) pour les systèmes embarqués. Cette solution est prouvée sure et ne dépend pas d'assomptions fortes faites dans le cas de l'attestation logicielle. / Embedded devices are currently used in many critical systems, ranging from automotive to medical devices and industrial control systems. Most of the research on such devices has focused on improving their reliability against unintentional failures, while fewer efforts have been spent to prevent intentional and malicious attacks. These devices are increasingly being connected via wireless and connected to the Internet for remote administration, this increases the risk of remote exploits and malicious code injected in such devices. Failures in such devices might cause physical damage and health and safety risks. Therefore, protecting embedded devices from attacks is of the utmost importance. In this thesis we present novel attacks and defenses against low-end embedded devices. We present several attacks against software-based attestation techniques used in embedded devices. Furthermore we design and implement a novel software-based attestation technique that is immune to the aforementioned attacks. Finally, we design a hardware solution to attest and establish a dyna

Our society is heavily dependent on commodities, as water and electricity, supplied to final users by engineered systems, which are known as critical infrastructures. In such context, the understanding of how such systems handle damaging events is an important aspect and is a current concern of researchers, public agents, and society. How much of performance a system loses due to damages is related to its vulnerability, and the ability to absorb and recover successfully from damages is its resilience. In this study, approaches to assess the vulnerability and resilience of power distribution systems by evaluating dynamic features, as the processes of failure and repair, and system reconfiguration for vulnerability, and the effects of extreme weather scenarios for resilience together with the processes of failure of repair are presented. Such approaches were applied on systems previously presented in the literature, and also on a Brazilian power distribution system. A Monte Carlo simulation was applied to evaluate this systems, models for time-to-failure and time-to-repair under different circumstances were obtained from historical data, and a method to use the models of time-to-failure during the vulnerability analysis was introduced. In addition, an assessment of the impact of reconfiguration capability on vulnerability is also carried out, and a resilience assessment under different climate scenarios has been developed. The time-to-failure and repair models highlighted how external factors modifies the Brazilian system failure and repair dynamics, the use of time-to-failure models during vulnerability analysis showed that the consideration of the failure dynamic of the types of elements give different results, and the time domain allows new analysis\' perspectives. The investigation indicated that the vulnerability reduction due to reconfiguration is affected by the number of switches and also the maximum load capacity of the distribution system feeders. The resilience assessment showed that for structural connectivity, larger distribution networks are less resilient, while for electricity delivery, a set of features, related with the topological and electrical organization of such networks, seems to be associated with the network service resilience, such information is useful for system planning and management. The dynamics evaluated in this study are relevant to vulnerability and resilience of such systems, and also to other critical infrastructures. Moreover, the developed approaches can be applied to other systems, as transportation and water distribution. In future studies, other power distribution systems features, as distributed generation and energy storage, will be considered in both, vulnerability and resilience analysis. / Nossa sociedade é altamente dependente de commodities, como água e eletricidade, fornecidas para os usuários por sistemas de engenharia, conhecidos como infraestruturas críticas. A compreensão de como tais sistemas lidam com eventos prejudiciais é uma preocupação atual de pesquisadores, agentes públicos e sociedade. A perda de desempenho de um sistema devido a danos é relacionada à sua vulnerabilidade, e a capacidade de absorver e se recuperar dos danos é a resiliência. Neste estudo, são apresentadas abordagens para avaliar a vulnerabilidade e resiliência de sistemas de distribuição de energia considerando características dinâmicas, como os processos de falha e reconfiguração do sistema, para a vulnerabilidade, e os efeitos de climas extremos na resiliência com os processos de falha e reparo. Tais abordagens foram aplicadas em sistemas previamente apresentados na literatura, e também em um sistema brasileiro. Simulação de Monte Carlo foi utilizada para avaliar as dinâmicas de falha e reparo do sistema utilizando de modelos obtidos a partir de dados históricos, e um método para usar os modelos de tempo-até-falha durante a análise de vulnerabilidade também foi apresentado. Além disso, uma avaliação do impacto da dinâmica de reconfiguração na vulnerabilidade foi realizada e uma avaliação de resiliência sob diferentes cenários climáticos foi desenvolvida. Os modelos tempo-para-falha e reparo destacaram como fatores externos modificam as dinâmicas de falha e reparo do sistema brasileiro, o uso de modelos de confiabilidade na análise de vulnerabilidades mostrou que a consideração dos diferentes tipos de elementos geram resultados diferentes e o domínio de tempo permite novas perspectivas de análise. A investigação da reconfiguração indicou que a redução da vulnerabilidade devido à reconfiguração é afetada pelo número de chaves e também pela máxima capacidade de carga dos alimentadores do sistema de distribuição. A avaliação de resiliência mostrou que, para conectividade estrutural, redes de distribuição maiores são menos resilientes, enquanto que para fornecimento de energia, um conjunto de características, relacionados com a organização topológica e elétrica dessas redes parece ser associado à resiliência do serviço, informação útil para o planejamento. As dinâmicas avaliadas neste estudo são relevantes para a vulnerabilidade e resiliência de tais sistemas, e também para outras infraestruturas críticas. Além disso, essas abordagens podem ser aplicadas a outros sistemas, como transporte e distribuição de água. Em estudos futuros, outras características de sistemas de distribuição de energia, como geração distribuída e armazenamento de energia, serão consideradas nas análises de vulnerabilidade e resiliência.

The increasing number of mobile devices challenges the current radio frequency (RF) networks. The conventional RF spectrum for wireless communications is saturating, motivating to develop other unexplored frequency bands. Light Fidelity (LiFi) which uses more than 300 THz of the visible light spectrum for high-speed wireless communications, is considered a promising complementary technology to its RF counterpart. LiFi enables daily lighting infrastructures, i.e. light emitting diode (LED) lamps to realise data transmission, and maintains the lighting functionality at the same time. Since LiFi mainly relies on line-of-sight (LoS) transmission, users in indoor environments may experience blockages which significantly affects users' quality of service (QoS). Therefore, hybrid LiFi and RF networks (HLRNs) where LiFi supports high data rate transmission and RF offers reliable connectivity, can provide a potential solution to future indoor wireless communications. In HLRNs, efficient load balancing (LB) schemes are critical in improving the traffic performance and network utilisation. In this thesis, the optimisation-based scheme (OBS) and the evolutionary game theory (EGT) based scheme (EGTBS) are proposed for load balancing in HLRNs. Specifically, in OBS, two algorithms, the joint optimisation algorithm (JOA) and the separate optimisation algorithm (SOA) are proposed. Analysis and simulation results show that JOA can achieve the optimal performance in terms of user data rate while requiring high computational complexity. SOA reduces the computational complexity but achieves low user data rates. EGTBS is able to achieve a better performance/complexity trade-off than OBS and other conventional load balancing schemes. In addition, the effects of handover, blockages, orientation of LiFi receivers, and user data rate requirement on the throughput of HLRNs are investigated. Moreover, the packet latency in HLRNs is also studied in this thesis. The notion of LiFi service ratio is introduced, defined as the proportion of users served by LiFi in HLRNs. The optimal LiFi service ratio to minimise system delay is mathematically derived and a low-complexity packet flow assignment scheme based on this optimum ratio is proposed. Simulation results show that the theoretical optimum of the LiFi service ratio is very close to the practical solution. Also, the proposed packet flow assignment scheme can reduce at most 90% of packet delay compared to the conventional load balancing schemes at reduced computational complexity.

L'un des éléments qui caractérisent le processus de mondialisation de l'économie est le développement de la logistique du fret comme secteur stratégique pour déterminer les avantages concurrentiels des régions urbaines. Cette étude analyse le lien entre l'évolution du marché, la réorganisation de l'Etat et le développement des infrastructures logistiques urbaines. Le point d'entrée de cette analyse est l'étude des politiques qui ont produit et gouverné au fil du temps deux marchés alimentaires de gros européens : le MIN Rungis et les Marchés Généraux de Milan. Leur comparaison explique comment les changements structurels ont influencé leur évolution et pourquoi aujourd'hui deux marchés de gros qui étaient initialement très similaires d'un point de vue analytique différent, ont deux policy outcome très différents. En utilisant une approche théorique et méthodologique basée sur les contributions du néo-institutionnalisme historique et de l'économie politique urbaine, le rôle des groupes d'intérêts, des acteurs politiques, des règles politiques et du marché est éclairé. Ces facteurs sont liés entre eux pour expliquer la policy conversion observée pour le MIN Rungis et la policy drift dans le cas de Milan. Enfin, les processus politiques qui ont mené à ces résultats sont expliqués en termes de mécanismes causaux. L'analyse met en évidence le rôle central des règles de politique locale et du contexte politique dans la détermination de la capacité des groupes d'intérêt locaux à influencer les processus décisionnels, et l'effet de leur mobilisation sur le développement de ces infrastructures urbaines. / One of the elements that characterize the process of economic globalization is the development of freight logistics as a strategic sector to determine the competitive advantages of urban regions. This study analyses the link between market changes, state reorganisation and the development of urban logistics infrastructures. The entry point for this analysis is the study of the policies that have produced and governed over time two European wholesale food markets: the MIN Rungis and the General Markets of Milan. Their comparison explains how structural changes have influenced their evolution and why today two wholesale markets, which were initially very similar from an analytical point of view, have nowadays two very different policy outcomes. Using a theoretical and methodological approach based on the contributions of historical neo-institutionalism and urban political economy, the role of interest groups, political actors, political rules and the market is clarified. These factors are interrelated to explain the policy conversion observed for MIN Rungis and the policy drift in the case of Milan. Finally, the policy processes that led to these results are explained in terms of causal mechanisms. The analysis highlights the central role of local policy rules and political context in determining the ability of local interest groups to influence decision-making processes, and the effect of their mobilization on the development of these urban infrastructures.

Les infrastructures et réseaux critiques commencent à s'ouvrir vers des architectures, protocoles et applications vulnérables. Ainsi, non seulement il est question de sécuriser ces applications (e.g., contre les attaques potentielles), mais il faut également justifier notre confiance dans les mécanismes de sécurité déployés. Pour cela, nous présentons PolyOrBAC, un cadriciel basé sur le modèle de contrôle d'accès OrBAC, les mécanismes de services Web ainsi que les contrats électroniques. Ensuite, nous préconisons l'utilisation de la Programmation Logique par Contraintes (PLC) pour détecter et résoudre les conflits éventuels dans la politique de sécurité. Au niveau de la mise en œuvre, nous proposons le protocole Q-ESP, notre amélioration d'IPSec qui assure à la fois des besoins de sécurité et de QoS. Enfin, nous présentons nos modèles et résultats de test et d'évaluation d'outils de sécurité notamment les Systèmes de Détection d'Intrusions (IDS).

Les réseaux techniques sont des infrastructures critiques qui peuvent être vulnérables aux inondations. Leur bon fonctionnement représente donc un enjeu majeur pour la gestion des risques et des territoires. Cette recherche postule que l'analyse de la résilience des réseaux techniques constitue un préalable nécessaire, mais non suffisant, à la mise en place de politiques d'amélioration de la résilience urbaine face aux inondations. Une méthodologie d'analyse de la résilience des réseaux techniques est proposée. Elle requiert l'analyse des capacités de résistance, d'absorption et de récupération de ces réseaux. Dans ce cadre, des développements ont été réalisés afin d'analyser les propriétés structurelles des réseaux techniques, les interdépendances entre les réseaux techniques et la remise en service de ces réseaux. Ces développements reposent principalement sur la théorie des graphes, les méthodes issues de la Sûreté de Fonctionnement, l'optimisation linéaire et l'analyse spatiale. Enfin, un prototype web-SIG a été développé puis appliqué à la ville de Dublin.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

Various literature suggest that securing access to land and guaranteeing land tenure security is essential for diverse land-based livelihoods and remains a prerequisite for sustainable agriculture, economic growth and poverty reduction. Secure land tenure is recognized as a key element to meeting the MDG target 11 to achieve significant improvement in the lives of 100 million slums dwellers by 2020. In the case of Rwanda, land tenure reform involves changes in land tenure systems from traditional and customary arrangements to more simple, modern and streamlined land tenure mechanisms guided by a core land registration system which is affordable, efficient and participatory. This development towards change in land registration patterns requires strong instruments for monitoring and evaluation and impact assessment of land registration implementation. The main purpose of this research is to develop key indicators to be used as baseline monitoring and evaluation instruments for land registration implementation in Rwanda, the shortage of time having limited the case study to one, but important District of Rwanda: Gasabo. The conceptual argument follows the logic of thinking that, when land tenure, symbolized by different values is supported by formal or legal land registration procedures, it gives it a dimension of power, insurance, guarantee and security that can be symbolized by different indicators measurable as variables. Seven key indicators were identified. To test the defined baseline indicators for validity, data was obtained from a sample of 150 respondents using a cluster sampling technique and structured interviews. The findings demonstrate the defined indicators could be measured and the quality of measurement (validity) established from statistical behavior of the variables. The results have shown that none of sampled households has a land title, this effect being recognized as a major hindrance to tenure security and to fruitful investment in land. Only those few who had other kinds of documents confirming rights to land, although of lesser weight, were eligible to a loan from a bank. The results have shown that the beneficiaries of bank loans have improved their income by being involved in land transactions and by acquiring a new land as well as buying domestic animals. The results also show that these interactions have brought a significant improvement in land productivity and consequently, raised income. Although household date showed low rate of land disputes, secondary data at district level showed significantly higher rates of occurrence and very low rates of dispute resolution. It is generally observed that land disputes could be avoided or solved if sufficient operational, legal and institutional instruments for disputes resolution and land registration are in place. / Thesis (M.Env.Dev.) - University of KwaZulu-Natal, Pietermaritzburg, 2007.

Thesis (M.L.A.) -- Mississippi State University. Department of Landscape Architecture. / Title from title screen. Includes bibliographical references.

No description available.