Les attaques par canaux cachés telles que les attaques par analyse de la consommation sont une menace pour la sécurité des circuits intégrés. Elles exploitent les fuites physiques émises par les circuits lors des calculs cryptographiques pour récupérer les informations secrètes qu'ils contiennent. De nombreuses contremesures, notamment matérielles, ont donc été proposées par la communauté dans le but de protéger les crypto-systèmes contre ce type d'attaques. Malgré leur efficacité, leur inconvénient majeur est leur surcoût important en surface, vitesse et consommation. Cette thèse a pour objectif de proposer des contremesures avec un faible coût au niveau matériel visant à réduire ces fuites et offrant un bon compromis entre sécurité et surcoûts. Pour cela, nous identifions tout d'abord les principales sources de fuites d'un crypto-système intégrant une architecture matérielle itérative d'un algorithme symétrique. Puis nous proposons plusieurs contremesures, à faible coût matériel, qui visent à réduire ces fuites. Enfin, nous évaluerons la robustesse de nos solutions face aux attaques par canaux cachés. / Side channel attacks such as power analysis attacks are a threat to the security of integrated circuits.They exploit the physical leakage of circuits during the cryptographic computations to retrieve the secret informations they contain. Many countermeasures, including hardware, have been proposed by the community in order to protect cryptosystems against such attacks. Despite their effectiveness, their major drawback is their significant additional cost in area, speed and consumption. This thesis aims at proposing low cost countermeasures able to reduce the leaks and offering a good compromise between security and costs. First we identify the main sources of leakage of a cryptographic system that integrates an iterative hardware architecture of a symetric algorithm. Then we propose several low cost countermeasures, which aim at reducing this leakage. Finally, we evaluate the robustness of our solutions against side channel attacks.

The Rijndael cipher was chosen as the Advanced Encryption Standard (AES) in August 1999. Its internal structure exhibits unusual properties such as a clean and simple algebraic description for the S-box. In this research, we construct a scalable family of ciphers which behave very much like the original Rijndael. This approach gives us the opportunity to use computational complexity theory. In the main result, we generate a candidate one-way function family from the scalable Rijndael family. We note that, although reduction to one-way functions is a common theme in the theory of public-key cryptography, it is rare to have such a defense of security in the private-key theatre. In this thesis a plan of attack is introduced at the circuit level whose aim is not break the cryptosystem in any practical way, but simply to break the very bold Rijndael security claim. To achieve this goal, we are led to a formal understanding of the Rijndael security claim, juxtaposing it with rigorous security treatments. Several of the questions that arise in this regard are as follows: ``Do invertible functions represented by circuits with very small numbers of gates have better than worst case implementations for their inverses?' ``How many plaintext/ciphertext pairs are needed to uniquely determine the Rijndael key?'

Submitted by Jaqueline Silva (jtas29@gmail.com) on 2014-09-04T17:02:47Z No. of bitstreams: 2 Dissertacao Elisangela Silva Dias.pdf: 846122 bytes, checksum: 357f425f14050b1601ed04cbcd4d9165 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-09-04T17:02:47Z (GMT). No. of bitstreams: 2 Dissertacao Elisangela Silva Dias.pdf: 846122 bytes, checksum: 357f425f14050b1601ed04cbcd4d9165 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2010-03-26 / A defensive alliance in graph G = (V;E) is a set of vertices S V satisfying the condition that every vertex v 2 S has at most one more neighbor in V 􀀀S than S. Due to this type of alliance, the vertices in S together defend themselves to the vertices in V 􀀀S. This dissertation introduces the basic concepts for the understanding of alliances in graphs, along with a variety of alliances and their numbers and provides some mathematical properties for these alliances, focusing mainly on defensive alliances in graphs. It shows theorems, corollaries, lemmas, propositions and observations with appropriate proofs with respect to the minimum degree of a graph G d(G), the maximum degree D(G), the algebraic connectivity μ, the total dominanting set gt(G), the eccentricity, the edge connectivity l(G), the chromatic number c(G), the (vertex) independence number b0(G), the vertex connectivity k(G), the order of the largest clique w(G) and the domination number g(G). It also shows a generalization of defensive alliances, called defensive kalliance, and the definition and properties of a security set in G. A secure set S V of graph G = (V;E) is a set whose every nonempty subset can be successfully defended of an attack, under appropriate definitions of “attack” and “defence”. / Uma aliança defensiva no grafo G = (V;E) é um conjunto de vértices S V satisfazendo a condição de que todo vértice v 2 S tem no máximo um vizinho a mais em V 􀀀S que em S. Devido a este tipo de aliança, os vértices em S juntam para se defenderem dos vértices em V 􀀀S. Nesta dissertação, são introduzidos os conceitos básicos para o entendimentos das alianças em grafos, junto com uma variedade de tipos de alianças e seus respectivos números, bem como são fornecidas algumas propriedades matemáticas para estas alianças, focando principalmente nas alianças defensivas em grafos. Apresentamos teoremas, corolários, lemas, proposições e observações com as devidas provas com relação ao grau mínimo de um grafo G d(G), ao grau máximo D(G), à conectividade algébrica μ, ao conjunto dominante total gt(G), à excentricidade, à conectividade de arestas l(G), ao número cromático c(G), ao número de independência (de vértices) b0(G), à conectividade de vértices k(G), à ordem da maior clique w(G) e ao número de dominação g(G). Também é mostrada a generalização de alianças defensivas, chamada k-aliança defensiva, e a definição e propriedades de um conjunto seguro em G. Um conjunto seguro S V do grafo G = (V;E) é um conjunto no qual todo subconjunto não-vazio pode ser defendido com sucesso de um ataque, sob as definições apropriadas de “ataque” e “defesa”.

O presente trabalho de pesquisa modela a cadeia de suprimentos brasileira da carne bovina industrializada destinada ao mercado internacional e aspectos do conjunto normativo incidente sobre este setor. Por meio desta modelagem, são apresentados os requisitos para um sistema de controle e integração das informações em tempo real em frigoríficos exportadores que atenda as exigências do poder público e de parceiros comerciais, além das principais necessidades do próprio frigorífico. Este trabalho de pesquisa apresenta, também, a arquitetura de hardware, de software e a metodologia do sistema operacional proposto, além dos benefícios advindos de sua eventual implementação. Este sistema, ora denominado Cadeia Logística Segura para Exportação de Carne Bovina Industrializada (CLSECB) contém as informações necessárias para a gestão do frigorífico, o controle de qualidade do produto, o trâmite burocrático da mercadoria, através da aplicação de dispositivos de identificação por rádio frequência (RFID) e do sistema operacional proposto. O CLSECB, portanto, permite identificar o produto (individualmente e/ou por lotes), associar informações ao produto (tanto sobre sua qualidade quanto sobre sua procedência), coletar e transmitir essas informações de forma rápida, eficiente e segura. Deste modo, o CLSECB é um sistema que, se implementado, permitirá a rastreabilidade total dentro do processo de industrialização e, será um avanço para a rastreabilidade total ao longo de toda a cadeia de suprimentos da carne bovina industrializada. Tais realizações, por fim, aproximam a cadeia de suprimentos da carne bovina industrializada dos ideais do programa Brasil-ID, do objetivo de obter uma linha azul para a exportação deste produto e do objetivo de expandir os mercados existentes e conquistar novos mercados internacionais. / This research work models the Brazilian supply chain of industrialized beef destined to the international market and regulatory aspects regarding this sector. Through this modeling, the requirements are presented for a system that controls and integrates information in real-time around beef producer exporters that meets the demands of the Government and business partners, including the main needs of the industry itself. This research work also presents the hardware and the software architecture and the methodology of a proposed operating system, including the benefits obtained from its eventual implementation. Thus, the proposed system, called Secure Supply Chain for the Export of Processed Beef (CLSECB Cadeia Logística Segura para Exportação de Carne Bovina Industrializada), contains the necessary information to the management of the industry, the quality control of the product, the bureaucratic processes of goods through the application of Radio-Frequency Identification (RFID) devices and the proposed operation system. The CLSECB allows the identification of the product (individually and/or by sets), the association of the products information (being it by its quality or by its precedence) and the collection and transmission of this information in a fast, efficient and secure way. Summarizing, the CLSECB is a system that, if implemented, will allow full traceability through the whole Brazilian supply chain of industrialized beef to exportation. Such accomplishments, bring together the Brazilian supply chain of industrialized beef and the ideals of the Brazil-ID program, the goal to obtain a blue channel to the exportation of this product and the target to expand existing markets and conquer new international markets.

O presente trabalho de pesquisa modela a cadeia de suprimentos brasileira da carne bovina industrializada destinada ao mercado internacional e aspectos do conjunto normativo incidente sobre este setor. Por meio desta modelagem, são apresentados os requisitos para um sistema de controle e integração das informações em tempo real em frigoríficos exportadores que atenda as exigências do poder público e de parceiros comerciais, além das principais necessidades do próprio frigorífico. Este trabalho de pesquisa apresenta, também, a arquitetura de hardware, de software e a metodologia do sistema operacional proposto, além dos benefícios advindos de sua eventual implementação. Este sistema, ora denominado Cadeia Logística Segura para Exportação de Carne Bovina Industrializada (CLSECB) contém as informações necessárias para a gestão do frigorífico, o controle de qualidade do produto, o trâmite burocrático da mercadoria, através da aplicação de dispositivos de identificação por rádio frequência (RFID) e do sistema operacional proposto. O CLSECB, portanto, permite identificar o produto (individualmente e/ou por lotes), associar informações ao produto (tanto sobre sua qualidade quanto sobre sua procedência), coletar e transmitir essas informações de forma rápida, eficiente e segura. Deste modo, o CLSECB é um sistema que, se implementado, permitirá a rastreabilidade total dentro do processo de industrialização e, será um avanço para a rastreabilidade total ao longo de toda a cadeia de suprimentos da carne bovina industrializada. Tais realizações, por fim, aproximam a cadeia de suprimentos da carne bovina industrializada dos ideais do programa Brasil-ID, do objetivo de obter uma linha azul para a exportação deste produto e do objetivo de expandir os mercados existentes e conquistar novos mercados internacionais. / This research work models the Brazilian supply chain of industrialized beef destined to the international market and regulatory aspects regarding this sector. Through this modeling, the requirements are presented for a system that controls and integrates information in real-time around beef producer exporters that meets the demands of the Government and business partners, including the main needs of the industry itself. This research work also presents the hardware and the software architecture and the methodology of a proposed operating system, including the benefits obtained from its eventual implementation. Thus, the proposed system, called Secure Supply Chain for the Export of Processed Beef (CLSECB Cadeia Logística Segura para Exportação de Carne Bovina Industrializada), contains the necessary information to the management of the industry, the quality control of the product, the bureaucratic processes of goods through the application of Radio-Frequency Identification (RFID) devices and the proposed operation system. The CLSECB allows the identification of the product (individually and/or by sets), the association of the products information (being it by its quality or by its precedence) and the collection and transmission of this information in a fast, efficient and secure way. Summarizing, the CLSECB is a system that, if implemented, will allow full traceability through the whole Brazilian supply chain of industrialized beef to exportation. Such accomplishments, bring together the Brazilian supply chain of industrialized beef and the ideals of the Brazil-ID program, the goal to obtain a blue channel to the exportation of this product and the target to expand existing markets and conquer new international markets.

Les Réseaux de Capteurs Sans Fils (RCSFs) et les réseaux véhiculaires sont de plus en plus répandus, et déployés dans des domaines d’applications variés tels que la santé, la surveillance environnementale, les applications d’alerte d’accident, et les applications militaires. Cependant, ces réseaux peuvent être sujets à des attaques, ce qui empêche leur utilisation à grande échelle. Cette thèse étudie la sécurité des communications pour les réseaux de capteurs sans fils, et les communications inter-véhiculaires. Dans ce but, nous abordons quatre aspects importants. La première étude porte sur l’authentification des messages diffusés dans les réseaux de capteurs. Nous nous concentrons sur les principaux schémas à base de divulgation de clés d’authentification. Nous démontrons que le délai de divulgation de clé induit un délai d’authentification, ce qui pourrait conduire à une attaque de mémoire de déni de service. Nous proposons ensuite deux protocoles d’authentification de la source dans les RCSFs, pour surmonter la vulnérabilité des solutions existantes. Les schémas proposés garantissent la gestion efficace de la mémoire tampon du récepteur, en utilisant un mécanisme d’authentification par niveau, et une structure de Filtre de Bloom afin de réduire le coût de communication. Ensuite, nous validons nos protocoles en utilisant l’outil de vérification AVISPA, et nous les évaluons avec des expérimentations dans l’environment TinyOS. Nous confirmons que ces protocoles fournissent un service d’authentification de la source tout en respectant les contraintes de RCSFs. La seconde étude porte sur le problème de stockage au niveau des capteurs. Nous considérons en particulier l’attaque d’authentification différée “Delayed Authentication Compromise” (DAC) dans les RCSFs, qui permet à un attaquant d’utiliser une clé déjà divulguée pour signer d’autres messages. Nous montrons d’abord que les systèmes récemment proposés qui sont résistants également à l’attaque DAC sont vulnérables aussi à deux types d’attaques: attaque de permutation de commandes (où un adversaire prétend “permuter” deux messages au fil du temps), et l’attaque de rejet de commandes (où un adversaire semble “cacher” un message envoyé par la station de base). Nous proposons ensuite une nouvelle solution d’authentification. Notre analyse montre que notre solution est efficace pour détecter à la fois l’attaque de permutation de commandes et l’attaque de rejet de commandes, — et en même temps — est plus efficace (en termes de communication et de calcul) que les solutions existantes. xxiDans la troisième étude, nous considérons le problème de la sécurité de la gestion des clés dans les réseaux de capteurs. Nous présentons de nouveaux schémas d’authentification à base de clés symétriques qui présentent un faible coût d’authentification et de communication. Nos systèmes sont construits en intégrant un mécanisme de réputation, un filtre de Bloom, et un arbre binaire de clés pour la distribution et la mise à jour des clés d’authentification. Nos schémas d’authentification sont efficaces en matière de communication et de consommation de l’énergie. La quatrième étude porte sur la sécurité des communications véhiculaires. Nous nous concentrons sur les applications d’alerte d’accident. Nous analysons les menaces pour un ensemble d’algorithmes. Nous démontrons que ces systèmes sont vulnérables à l’attaque d’injection d’une fausse position, à l’attaque de rejeu de message d’alerte, et à l’attaque d’interruption de message d’alerte. Ensuite, nous proposons des contre-mesures à ces menaces. Nous avons donc proposé une solution qui est à la fois rapide et sécurisée pour les applications d’alerte d’accident : Un algorithme rapide et sécurisé pour la diffusion des messages en multi-saut (FS-MBA). Enfin, nous confirmons l’efficacité et la faisabilité des différents protocoles en effectuant un ensemble de simulations sous le simulateur NS-2. / Wireless sensor and vehicular networks play an important role in critical military and civil applications, and pervade our daily life. However, security concerns constitute a potential stumbling block to the impeding wide deployment of sensor networks and vehicular communications. This dissertation studies communication security for Wireless Sensor Networks (WSNs), and vehicular communication. To this aim, we address four important aspects. The first study addresses broadcast authentication in WSNs. We focus on key disclosure based schemes. We demonstrate that key disclosure delay induces an authentication delay, which could lead to a memory DoS attack. We then propose two broadcastauthentication protocols for WSNs, which overcome the security vulnerability of existingsolutions. The proposed schemes guarantee the efficient management of receiver’s buffer, by employing a staggered authentication mechanism, and a Bloom filter data structure to reduce the communication overhead. We also validate our protocols under the AVISPA model checking tool, and we evaluate them with experiments under TinyOS. Our findings are that these protocols provide source authentication service while respecting the WSN constraints.The second study addresses the storage issue in WSNs, in particular the Delayed AuthenticationCompromise attack (DAC). We first demonstrate that recently proposed schemes, which also address the DAC issue are vulnerable to two kinds of attacks: switch command attack (where an adversary pretends to “switch” two messages over time), and drop command attack (where an adversary just pretends to “hide” a message sent from the broadcaster). As a countermeasure against these attacks, we propose a new solution for broadcast authentication. Our analysis shows that our solution is effective in detecting both switch command and drop command attack, and—at the same time—is more efficient (in terms of both communication and computation) than the state of the art solutions.In the third study, we address key management security in WSNs. We present novel symmetric-key-based authentication schemes which exhibit low computation and communication authentication overhead. Our schemes are built upon the integration of a reputation mechanism, a Bloom filter, and a key binary tree for the distribution and updating of the auxviii thentication keys. Our schemes are lightweight and efficient with respect to communication and energy overhead. The fourth study addresses security in vehicular communications. We focus on fast multi hop broadcast applications. We analyze the security threats of state of the art vehicular based safety applications. We demonstrate that these schemes are vulnerable to the position cheating attack, the replay broadcast message attack, and the interrupting forwarding attack. Then, we propose countermeasures for these threats. We hence propose a complete solution which is both fast and secure in broadcasting safety related messages: Fast and Secure Multi-hop Broadcast Algorithm (FS-MBA). Finally, we confirm the efficiency and feasibility of our proposals using an extensive set of simulations under NS-2 Simulator.

L'authentification homme-machine est une problématique largement développée pour les télécommunications. Une authentification dans le sens "machine-homme" permettra d'assurer l'utilisateur humain assermenté du fonctionnement intègre d'une machine lors, par exemple, d'une session de vote électronique ou d'une vérification d'objet en traçabilité sécurisée. Cette thèse se focalise sur la traçabilité sécurisée sans accès (systématique) à un canal de communication. Nous décrivons différentes techniques d'authentification de produits manufacturés en nous concentrant sur une méthode de caractérisation de motifs imprimés. Pour effectivement authentifier un objet, nous montrons qu'un agent vérifieur doit s'assurer de l'intégrité du tiers et du système électronique utilisée pour la vérification. Cependant l'authenticité du système électronique lui-même reste à vérifier. La question que nous adressons alors est la suivante : comment un être humain peut-il se convaincre de l'intégrité et de l'authenticité d'un système embarqué dans un mode hors ligne ? Nous définissons deux familles de solutions. Dans la première, l'utilisateur fait appel, pour les calculs, à un dispositif auxiliaire tandis que dans la seconde l'utilisateur ne fait usage que d'un papier et d'un crayon. Pour chacune des deux familles, nous proposons un protocole d'authentification d'un système embarqué dont la puce, typiquement un FPGA ou un microcontrôleur, dépend de la configuration ou de la programmation d'une mémoire RAM / "Human-to-Machine" authentication is widely developed for modern telecommunications. A "Machine-to-Human" authentication will ensure the trusted human user about the integrity of the machine, for example during an electronic voting session or object verification in secure traceability. This work is focused on secure traceability without any systematic access to a communication network. We depict different technics for goods authentication and we focus on a method based on the characterization of printed patterns. To completely authenticate an object, we show that a human verifier has to be confident in the integrity of the third party and the electronic system involved in the verification phase. However, the authenticity of the electronic system itself has also to be verified. We address here the following question : how a human being can convince himself about the integrity and the authenticity of an embedded system in an off-line environment ? We propose two groups of solutions. In the first one, an auxiliary electronic device is used to perform computing operations. In the second one, the human capability (memory and computational abilities) is exploited. In each group, we propose a protocol to authenticate embedded systems for which the chip (typically an FPGA (Field Programmable Gate Array) or a microcontroller) is initialized according to the configuration or programming of its RAM memory

<p>The present thesis deals with Åland, i.e. the Åland Islands, as a language environment. Its main focus is on the language attitudes of adolescents. The status, role and use of Swedish, Finnish and English are topical. Its main part consists of an empirical study, which is based on an extensive questionnaire answered by students in grade 9 of primary school and in the second grade of the (theoretical) secondary school in Åland.</p><p>The thesis includes a description of Åland as a language environment. The legal framework making Åland an autonomous region in Finland with Swedish as the only official language is presented. Language policies in Åland are compared with those of Sweden and Finland (outside of Åland). Special treatment is given to the school as a linguistic environment and recent language related debate in Åland.</p><p>The central questions in the questionnaire relate to language choice, media habits, subjective estimations of the respondents’ own language competence and language attitudes in a broad sense.</p><p>Six hypotheses based on a model of secure and insecure majorities and minorities as well as the Interactive Acculturation Model are postulated and treated.</p><p>The results of the empirical study reveal very strong feelings of affinity towards Åland. Attitudes towards English and English-speakers are in general positive. The results reveal somewhat ambivalent attitudes towards Finnish and Finland. Many variables show a tendency among the respondents to favour Sweden ahead of Finland and negative attitudes towards Finnish but there are also other conflicting results. The respondents who have parents who speak Finnish to them display more positive attitudes towards Finnish and Finland. These differences between the groups are statistically significant. However, the group with a Finnish language background also displays its strongest feelings of affinity towards Åland.</p>

A high proportion of urban residents in Tanzanian cities are tenants who rent rooms in privately owned houses in unplanned settlements. However, in housing policy and in urban planning rental tenure gets very little attention. This study focuses on the reasons for and consequences of this discrepancy between policy and practice. Perspectives and actions of different actors involved in the housing provision process in Mwanza City, Tanzania, have been central to the research. The examined actors are residents in various housing tenure forms as well as government officials and representatives at different levels, from the neighbourhood level to UN-Habitat. The main methods have been interviews and discussions with actors as well as studies of policy documents, laws and plans. Among government actors, private rental tenure is largely seen as an issue between landlords and tenants. Tanzanian housing policy focuses more on land for housing than on shelter. This means that house-owners who control land have a more important role in urban planning and policies than tenants have. In Tanzania in general and in Mwanza in particular, housing policy focuses on residents’ involvement in upgrading unplanned areas by organising in Community Based Organisations. This means that owners who live for a longer period in an area benefit more from settlement improvements than tenants. Tenants are relatively mobile and do not take for granted that they will stay in the same house for long. This raises the question of tenants’ possibilities to influence as well as their rights as citizens as compared to that of owners. The question of citizens’ rights for dwellers in informal settlements has received increased attention during the last years in international housing policy discussions. There is an evident need to intensify and diversify this discussion.

The present thesis deals with Åland, i.e. the Åland Islands, as a language environment. Its main focus is on the language attitudes of adolescents. The status, role and use of Swedish, Finnish and English are topical. Its main part consists of an empirical study, which is based on an extensive questionnaire answered by students in grade 9 of primary school and in the second grade of the (theoretical) secondary school in Åland. The thesis includes a description of Åland as a language environment. The legal framework making Åland an autonomous region in Finland with Swedish as the only official language is presented. Language policies in Åland are compared with those of Sweden and Finland (outside of Åland). Special treatment is given to the school as a linguistic environment and recent language related debate in Åland. The central questions in the questionnaire relate to language choice, media habits, subjective estimations of the respondents’ own language competence and language attitudes in a broad sense. Six hypotheses based on a model of secure and insecure majorities and minorities as well as the Interactive Acculturation Model are postulated and treated. The results of the empirical study reveal very strong feelings of affinity towards Åland. Attitudes towards English and English-speakers are in general positive. The results reveal somewhat ambivalent attitudes towards Finnish and Finland. Many variables show a tendency among the respondents to favour Sweden ahead of Finland and negative attitudes towards Finnish but there are also other conflicting results. The respondents who have parents who speak Finnish to them display more positive attitudes towards Finnish and Finland. These differences between the groups are statistically significant. However, the group with a Finnish language background also displays its strongest feelings of affinity towards Åland.