Authentication protocols are used for two parties to authenticate each other and build a secure channel over wired or wireless public channels. However, the present standards of authentication protocols are either insufficiently secure or inefficient for light weight devices. Therefore, we propose two authentication protocols for improving the security and user efficiency in wired and wireless environments, respectively. Traditionally, TLS/SSL is the standard of authentication and key exchange protocols in wired Internet. It is known that the security of TLS/SSL is not enough due to all sorts of client side attacks. To amend the client side security, multi-factor authentication is an effective solution. However, this solution brings about the issue of biometric privacy which raises public concern of revealing biometric data to an authentication server. Therefore, we propose a truly three factor authentication protocol, where the authentication server can verify their biometric data without the knowledge of users¡¦ templates and samples. In the major wireless technologies, extensible Authentication Protocol (EAP) is an authentication framework widely used in IEEE 802.11 WLANs. Authentication mechanisms built on EAP are called EAP methods. The requirements for EAP methods in WLANs authentication have been defined in RFC 4017. To achieve user efficiency and robust security, lightweight computation and forward secrecy, excluded in RFC 4017, are desired in WLAN authentication. However, all EAP methods and authentication protocols designed for WLANs so far do not satisfy all of the above properties. We will present a complete EAP method that utilizes stored secrets and passwords to verify users so that it can (1) meet the requirements of RFC 4017, (2) provide lightweight computation, and (3) allow for forward secrecy. In order to prove our proposed protocols completely, we apply two different models to examine their security properties: Bellare¡¦s model, a standard reduction based on computational model, that reduces the security properties to the computationally hard problems and the OFMC/AVISPA tool, a model checking approach based on formal model, that uses the concept of the search tree to systematically find the weaknesses of a protocol. Through adopting Bellare¡¦s model and OFMC/AVISPA tool, the security of our work is firmly established.

Depuis l’introduction de la mécanique quantique, plusieurs mystères de la nature ont trouvé leurs explications. De plus en plus, les concepts de la mécanique quantique se sont entremêlés avec d’autres de la théorie de la complexité du calcul. De nouvelles idées et solutions ont été découvertes et élaborées dans le but de résoudre ces problèmes informatiques. En particulier, la mécanique quantique a secoué plusieurs preuves de sécurité de protocoles classiques. Dans ce m´emoire, nous faisons un étalage de résultats récents de l’implication de la mécanique quantique sur la complexité du calcul, et cela plus précisément dans le cas de classes avec interaction. Nous présentons ces travaux de recherches avec la nomenclature des jeux à information imparfaite avec coopération. Nous exposons les différences entre les théories classiques, quantiques et non-signalantes et les démontrons par l’exemple du jeu à cycle impair. Nous centralisons notre attention autour de deux grands thèmes : l’effet sur un jeu de l’ajout de joueurs et de la répétition parallèle. Nous observons que l’effet de ces modifications a des conséquences très différentes en fonction de la théorie physique considérée. / Since the introduction of quantum mechanics, many mysteries of nature have found explanations. Many quantum-mechanical concepts have merged with the field of computational complexity theory. New ideas and solutions have been put forward to solve computational problems. In particular, quantum mechanics has struck down many security proofs of classical protocols. In this thesis, we survey recent results regarding the implication of quantum mechanics to computational complexity and more precisely to classes with interaction. We present the work done in the framework of cooperative games with imperfect information. We give some differences between classical, quantum and no-signaling theories and apply them to the specific example of Odd Cycle Games. We center our attention on two different themes: the effect on a game of adding more players and of parallel repetition. We observe that depending of the physical theory considered, the consequences of these changes is very different.

Voting is a fundamental decision making instrument in any consensus-based society. It is employed in various applications from student body elections, reality television shows, shareholder meetings, to national elections. With the motivation of better eciency, scalability, speed, and lower cost, voting is currently shifting from paper-based to the use of electronic medium. This is while aiming to achieve better security, such that voting result reflects true opinions of the voters. Our research focuses on the study of cryptographic voting protocols accommodating a flexible ballot structure as a foundation for building a secure electronic voting system with acceptable voting results. In particular, we search for a solution suitable for the preferential voting system employed in the Australian Federal Election. The outcomes of the research include: improvements and applications of batch proof and verication theorems and techniques, a proposed alternative homomorphic encryption based voting scheme, a proposed Extended Binary Mixing Gate (EBMG) mix-network scheme, a new threshold randomisation technique to achieve receipt-freeness property in voting, and the application of cryptographic voting protocol for preferential voting. The threats and corresponding requirements for a secure secret-ballot voting scheme are rst discussed. There are significant security concerns about the conduct of electronic voting, and it is essential that the voting results re ect the true opinions of the voters - especially in political elections. We examine and extend batch processing proofs and verifications theorems and proposed applications of the theorems useful for voting. Many instances of similar operations can be processed in a single instance using a batch technique based on one of the batch theorems. As the proofs and verications provide formal assurances that the voting process is secure, batch processing offers great efficiency improvements while retaining the security required in a real-world implementation of the protocol. The two main approaches in cryptographic voting protocols, homomorphic encryption based voting and mix-network based voting, are both studied in this research. An alternative homomorphic voting scheme using multiplicative homomorphism property, and a number of novel mix-network schemes are proposed. It is shown that compared to the mix-network approach, homomorphic encryption schemes are not scalable for straight-forward adaptation of preferential systems. One important requirement of secret-ballot voting is receipt-freeness. A randomisation technique to achieve receipt-freeness in voting is examined and applied in an ecient and practical voting scheme employing an optimistic mix-network. A more general technique using threshold randomisation is also proposed. Combination of the primitives, both the homomorphic encryption and mixnetwork approach, yields a hybrid approach producing a secure and ecient secret-ballot voting scheme accommodating a exible ballot structure. The resulting solution oers a promising foundation for secure and practical secret-ballot electronic voting accommodating any type of counting system.

Esta Tese aborda, de modo original e pioneiro, importantes aspectos da Engenharia de Fundações do Sul de Minas: a) sistematização de conhecimentos sobre a Geologia regional; b) identificação e caracterização da prática de fundações; c) definição (com a formação de um banco de dados) dos perfis mais representativos do subsolo de suas principais cidades; d) estudo dos parâmetros físicos, químicos e geomecânicos de um solo típico; e) implantação de campo experimental de fundações da Universidade Federal de Lavras, com a realização de provas de carga. Grande ênfase foi dada aos itens (a), (c) e (e). Priorizou-se o estudo das fundações de baixa capacidade de carga, no estudo do comportamento carga-recalque de ensaios de placa, de provas de carga a compressão em estacas-broca isoladas e de tubulões curtos instrumentados. Destacam-se as análises sobre os efeitos de forma, profundidade, melhoramento do terreno de fundação e de inundação nas fundações rasas e da variação L/d na resistência lateral unitária das estacas, sendo valorizadas as fórmulas empíricas com base no SPT. São apresentadas fórmulas de previsão de carga, em função do SPT, para sapatas, estacas de pequeno diâmetro e tubulões curtos e um estudo de custos, onde se mostra que a opção indiscriminada por tubulões é inadequada para certas faixas de carga de trabalho. Adicionalmente, são feitas recomendações para intensificar o uso de sondagens tendo em vista a grande variabilidade das propriedades dos solos regionais e para aumentar os fatores de segurança nestas fórmulas onde houver possibilidade de ocorrência de colapso no solo. / This work presents, at time, important aspects of Foundation Engineering at Southern Region of Minas Gerais State: a) systematization of the knowledge about regional geology; b) identification and characterization of practice in foundations; c) definition (though establishment of a data base) of most representative sub-soil profiles at main cities at the region; d) study of physical, chemical and geomechanical parameters of a typical soil; e) implementation of a experimental field for foundation studies at Federal University of Lavras, by execution of load tests. A large emphasis was given to items a, c and e. The study of foundations of low load capacity was prioritized when testing plates, isolated piles under compression and short drilled piers with sensors. Analysis such as form effects, depth, soil improvement and flooding on shallow foundations and variation of L/d on the lateral unity resistance by emphasizing the empiral equations based on SPT were all pointed out. Mathematical equations are presented for load estimation as function of SPT for small diameter piles and short drilled piers as well as a cost study where it can bem shown that the undistinguished alternative for piers is inadequate for some load values. In addition, due to soil spatial variability and safety factor increment on soils subject for colapse, recommendations on intensive use of SPT test are given.

A família sofreu, no século passado, séc. XX diversas mudanças. As próprias relações mudaram: industrialização e urbanização aceleradas, emancipação da mulher, duas Guerras Mundiais que alavancaram o tema dos direitos humanos, com evidente repercussão nos direitos da personalidade. Tudo isso alterou o perfil da família e das relações que ocorrem em seu seio. Na verdade, estabeleceu-se uma perspectiva limitadora do poder em geral, da ascendência sobre outrem, inclusive no âmbito do pátrio poder, hoje poder familiar. Sem embargo disso, passada a euforia inicial, é hora de buscar caminhos para a plena efetivação desses direitos. Isso dependerá, em grande medida, da própria interpretação judicial, já que na decisão jurisdicional o ordenamento convertido numa fórmula específica para a solução daquela lide atinge o seu ápice. Se a afetividade e a grita por justiça e ética nas relações familiares é inafastável, mais do que isso, é louvável, porque consagra a dignidade da pessoa humana, por outro lado, a ideologia e a patrulha moral em temas existenciais devem ser evitadas. Ativismo judicial não se confunde com invasividade. A intrujice do Estado na família pela função legislativa, executiva ou judiciária deve incentivar um repensar das próprias expectativas que os operadores do Direito, sobretudo do Direito de Família, possuem a respeito do potencial transformativo de seus saberes. Assim, sempre buscando o justo termo, a dissertação examina as hipóteses de intervenção judicial no exercício abusivo do poder familiar, tanto na dimensão patrimonial quanto na dimensão existencial. Na primeira, analisa-se a administração dos bens dos filhos, o usufruto que, por lei, lhe é correlato e sua interpretação à luz do princípio do melhor interesse da criança e do adolescente. Na segunda, o objeto da investigação é o ponto ótimo de equilíbrio entre a intervenção que concretiza os direitos e a intervenção invasiva, errônea. Surgem ponderações sobre a ideologia e sua influência na exegese judicial, em temas como alienação parental e abandono afetivo que habitam o novo léxico deste Direito de Família sequioso de substância o qual, entretanto, não pode abdicar de uma postura autocrítica sob pena de manietar as próprias possibilidades de realização pessoal que alega defender. / Family underwent several changes in the last century, the twentieth century. The very relationships did change: accelerated (rapid) industrialization and urbanization, women´s emancipation, two World Wars, levered the human rights subject, with obvious repercussion on the rights of personality. All of that has modified family profile and the relationships that occur within its core. Actually, in general, a limiting perspective of power was established on the ascendancy over the other, inclusively in the extent of parental power, currently said family, or parental authority. With no embargo of this, after leaving behind the initial euphoria, now is the moment to look for ways towards the thorough accomplishment of these rights. This will depend, largely, on the judicial interpretation, for in the jurisdictional decision converted into a specific formula aimed at the solution of that dispute, it reaches its climax. If, on one hand, affectivity and the outcry for justice and ethics within family relationships cannot be set apart, and, more than that, they are praiseworthy - for they consecrate dignity of the individual - on the other hand, when it comes to existential matters, ideology and moral patrolling ought to be avoided. Judicial activism does not confound with invasiveness. State intrusion on family through legislative, or executive, or judiciary activity, should encourage a review of the very expectations that Law operating professionals have particularly those in the Family Law field regarding the transformational potential of their knowledge. Therefore, looking always for the right boundary, the dissertation investigates the hypotheses for judicial intervening in abusive family authority, considering not only property dimension, but also the existential. On the first we analyze the administration of assets of sons, the usufruct that by force of law correlates to it, and its interpretation in the light of best interest for child and adolescent. On the second, the object of our investigation is the optimal balance point between intervention that makes rights concrete, and the invasive, erroneous interference. We ponder over ideology and its influence on the judicial exegesis, in subjects such as parental alienation and affective abandonment, which dwell in this Family Law new lexicon, avid for substance, but which, however, cannot waive from a self-criticism posture, under penalty of handcuffing the very own possibilities of personal fulfillment it alleges to defend.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-09-29T13:41:58Z No. of bitstreams: 1 monalisamarialauro.pdf: 510424 bytes, checksum: 31284a9c9c1e1159695542b7f038ffe8 (MD5) / Approved for entry into archive by Diamantino Mayra (mayra.diamantino@ufjf.edu.br) on 2016-09-30T13:52:54Z (GMT) No. of bitstreams: 1 monalisamarialauro.pdf: 510424 bytes, checksum: 31284a9c9c1e1159695542b7f038ffe8 (MD5) / Made available in DSpace on 2016-09-30T13:52:54Z (GMT). No. of bitstreams: 1 monalisamarialauro.pdf: 510424 bytes, checksum: 31284a9c9c1e1159695542b7f038ffe8 (MD5) Previous issue date: 2010-08-18 / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Na presente dissertação, analisa-se o modo peculiar com que Kant apreende o problema da imortalidade da alma em sua filosofia crítica. Neste intuito, prioriza-se um confronto com as provas racional-teóricas presentes no célebre Fédon mendelssohniano, visto que este é uma notável referência na defesa da imortalidade da alma na Aufklärung. Este confronto permite constatar que o argumento da simplicidade da alma de Mendelssohn constitui-se em um paralogismo transcendental, e que sua defesa da incorruptibilidade da alma não se sustenta quando se respeita a condição crítica de uso esquematizado dos conceitos puros do entendimento. Finalmente, a advertência kantiana contra o uso especulativo da razão para além dos limites da experiência possível revela-se como parte de seu empreendimento de fundamentação de uma moralidade autônoma e plenamente ativa na vida humana. Na perspectiva aberta pela lei moral, a permanência da alma resolve-se como um necessário e sólido postulado da razão prática pura. / This thesis analyzes the particular way in which Kant conceives the issue of the soul’s immortality in his critical philosophy. In order to do that, the focus is set on a confrontation with the rational-theoretical proofs present in Mendelssohn’s Phaedon, since this work is a remarkable reference in the defense of the soul’s immortality during the German Aufklärung. This confrontation allows us to verify that Mendelssohn’s argument of the simplicity of the soul constitutes a transcendental paralogism, and his defense of the incorruptibility of the soul fails when measured by the critical condition of a schematized use of the pure concepts of the understanding. Finally, Kant’s caution against the speculative use of reason beyond the limits of possible experience appears as a part of his undertaking of philosophically grounding a morality which is both autonomous and completely active in human life. Following the perspective opened by the moral law, the duration of the soul is explained as a necessary and firm postulate of pure practical reason.

Cette recherche vise à établir les propriétés fondamentales d'un système formel aux preuves circulaires introduit par Santocanale, auquel on a rajouté la règle de coupure. On démontre, dans un premier temps, qu'il y a une pleine correspondance entre les preuves circulaires et les flèches issues des catégories dites µ-bicomplètes. Ces flèches sont celles que l'on peut définir purement à partir des outils suivants: les produits et coproduits finis, les algèbres initiales et les coalgèbres finales. Dans la catégorie des ensembles, les preuves circulaires dénotent donc les fonctions qu'on peut définir en utilisant les produits cartésiens finis, les unions disjointes finies, l'induction et la coinduction. On décrit également une procédure d'élimination des coupures qui produit, à partir d'une preuve circulaire finie, une preuve sans cycles et sans coupures, mais possiblement infinie. On démontre que l'élimination des coupures fournit une sémantique opérationnelle aux preuves circulaires, c'est-à-dire qu'elle permet de calculer les fonctions dénotées par celles-ci, par le moyen d'une sorte d'automate avec mémoire. Enfin, on s'intéresse au problème de la puissance expressive de cet éliminateur de coupures, c'est-à-dire à la question de caractériser la classe des expressions qu'il peut calculer. On démontre, par une simulation, que l'éliminateur des coupures est strictement plus expressif que les automates à pile d'ordre supérieur. / This research aims at establishing the fundamental properties of a formal system with circular proofs introduced by Santocanale, to which we added the cut rule. We first show that there is a full correspondence between circular proofs and arrows from the so-called µ-bicomplete categories. These arrows are those that can be defined purely from the following tools: finite products and coproducts, initial algebras and final coalgebras. In the category of sets, circular proofs denote functions that one can define by using finite cartesian products, finite disjoint unions, induction and coinduction. We also describe a cut-elimination procedure that produces, from a given finite circular proof, a proof without cycles and cuts, but which may be infinite. We prove that cut-elimination gives an operational semantics to circular proofs, which is to say that they allow to compute the functions denoted by them, by using a sort of automaton with memory. Finally, we are interested in finding the expressive power of that cut-eliminating automaton. In other words, we want to characterize the class of functions that it can compute. We show, through a simulation, that the cut-eliminating automaton is strictly more expressive than higher-order pushdown automata.

La sécurité de l’information repose sur la bonne interaction entre différents niveaux d’abstraction : les composants matériels, systèmes d’exploitation, algorithmes, et réseaux de communication. Cependant, protéger ces éléments a un coût ; ainsi de nombreux appareils sont laissés sans bonne couverture. Cette thèse s’intéresse à ces différents aspects, du point de vue de la sécurité et de la cryptographie. Nous décrivons ainsi de nouveaux algorithmes cryptographiques (tels que des raffinements du chiffrement de Naccache–Stern), de nouveaux protocoles (dont un algorithme d’identification distribuée à divulgation nulle de connaissance), des algorithmes améliorés (dont un nouveau code correcteur et un algorithme efficace de multiplication d’entiers),ainsi que plusieurs contributions à visée systémique relevant de la sécurité de l’information et à l’intrusion. En outre, plusieurs de ces contributions s’attachent à l’amélioration des performances des constructions existantes ou introduites dans cette thèse. / Information security relies on the correct interaction of several abstraction layers: hardware, operating systems, algorithms, and networks. However, protecting each component of the technological stack has a cost; for this reason, many devices are left unprotected or under-protected. This thesis addresses several of these aspects, from a security and cryptography viewpoint. To that effect we introduce new cryptographic algorithms (such as extensions of the Naccache–Stern encryption scheme), new protocols (including a distributed zero-knowledge identification protocol), improved algorithms (including a new error-correcting code, and an efficient integer multiplication algorithm), as well as several contributions relevant to information security and network intrusion. Furthermore, several of these contributions address the performance of existing and newly-introduced constructions.

No description available.

Les algorithmes de chiffrement par blocs paramétrables constituent une généralisation des algorithmes de chiffrement par blocs classiques qui, en plus d'une clé et d'un message à chiffrer ou déchiffrer, admettent un paramètre additionnel, nommé tweak en anglais. Le rôle de ce paramètre additionnel est d'apporter une variabilité à l'algorithme de chiffrement, sans qu'il soit nécessaire de changer la clé ou de garder le tweak secret. Ce dernier doit également pouvoir être contrôlé par l'adversaire sans dégradation de la sécurité. Dans cette thèse nous nous intéressons à une classe particulière d'algorithmes de chiffrement par blocs, les algorithmes de chiffrement par blocs à clé alternée. Plusprécisément, nous étudions la sécurité du schéma d'Even-Mansour, qui constitue une abstraction de la structure de ces algorithmes dans le modèle de la permutation aléatoire, et cherchons à rendre ce schéma paramétrable tout en conservant de fortes garanties de sécurité. À cette fin, nous introduisons une nouvelle construction générique, baptiséeTEM, qui remplace les clés de tours de la construction d'Even-Mansour par une valeur qui dépend de la clé et du tweak, et en étudions la sécurité dans deux cas : lorsque le mixage de la clé et du tweak est linéaire ou lorsqu'il est très non-linéaire. Nos preuves de sécurité utilisent la technique des coefficients H, introduite par Jacques Patarin danssa thèse de doctorat, qui permet de transformer des problèmes cryptographiques en problèmes combinatoires sur des groupes finis. / Tweakable block ciphers are a generalization of classical block ciphers which, in addition to a key and a plaintext or a ciphertext, take an additionnal parameter called a tweak. The goal of this new parameter is to bring variability to the block cipher without needing to change the key or to keep the tweak secret. The tweak should also be adversariallycontrollable without sacrificing security. In this thesis we study a particular class of block ciphers, namely key-alternating ciphers. More precisely, we study the security of the Even-Mansour scheme, which is an abstraction of these ciphers in the random permutation model, and seek to bring tweakability to this scheme while keeping strong security guarantees. To this end, we introduce a new generic construction, dubbed TEM, which replaces the round keys from the Even-Mansour construction by a value depending on both the key and the tweak, and study its security in two cases: when the tweak and key mixing is linear or highly non-linear. Our security proofs rely on the H-coefficients technique, a technique introduced by Jacques Patarin in his PhD thesis which transforms cryptographic problems into combinatorial problems in finite groups.