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Debant, Alexandre. "Symbolic verification of distance-bounding protocols : application to payment protocols." Thesis, Rennes 1, 2020. http://www.theses.fr/2020REN1S057.
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L’essor des nouvelles technologies, et en particulier la Communication en Champ Proche (NFC), a permis l’apparition de nouvelles applications. Á ce titre, nous pouvons mentionner le paiement sans contact, les clefs mains libres ou encore les carte d’abonnement dans les transports en commun. Afin de sécuriser l’ensemble de ces applications, des protocoles de sécurité, appelés protocoles délimiteurs de distance on été développés. Ces protocoles ont pour objectif d’assurer la proximité physique des appareils mis en jeu afin protocole cryptographique, protocole de paiement de limiter le risque d’attaque. Dans ce manuscrit, nous présentons diverses approches permettant une analyse formelle de ces protocoles. Dans ce but, nous proposons un modèle symbolique permettant une modélisation précise du temps ainsi que des positions dans l’espace de chaque participant. Nous proposons ensuite deux approches : la première développant une nouvelle procédure de vérification, la seconde permettant la ré-utilisation d’outils existants tels que Proverif. Tout au long de ce manuscrit, nous porterons une attention parti- culières aux protocoles de paiement sans contactThe rise of new technologies, and in particular Near Field Communication (NFC) tags, offers new applications such as contactless payments, key-less entry systems, transport ticketing... Due to their security concerns, new security protocols, called distance-bounding protocols, have been developed to ensure the physical proximity of the de- vices during a session. In order to prevent flaws and attacks, these protocols require formal verification. In this manuscript, we present several techniques that allow for an automatic verification of such protocols. To this aim, we first present a symbolic model which faithfully models time and locations. Then we develop two approaches : either ba- sed on a new verification procedure, or leveraging existing tools like Proverif. Along this manuscript, we pay a particular attention to apply our results to contactless payment protocols
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Bandyopadhyay, Amrit. "The smart stone protocol (SSP) design and protocols /." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3953.
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Thesis (M.S.) -- University of Maryland, College Park, 2006.Thesis research directed by: Dept. of Electrical and Computer Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Gerault, David. "Security analysis of contactless communication protocols." Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAC103.
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Dowling, Benjamin James. "Provable security of internet protocols." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/108960/1/Benjamin%20James_Dowling_Thesis.pdf.
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Secure communications over the Internet are typically established by first running an authenticated key exchange protocol, which computes a secret key between two users, which is then utilised in an encryption protocol. In this work we examine novel security properties of the most prominent communications protocols, including the Transport Layer Security and Secure Shell protocols. We introduce new security frameworks for analysing security properties of protocols involving negotiation, multiple ciphersuites, long-term key reuse, and time synchronisation. Our results have increased confidence in the security of real-world protocols, and our analyses of next-generation protocols have informed their development by standardisation bodies.
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Gibson-Robinson, Thomas. "Analysing layered security protocols." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:35c9e4e5-6540-4e1d-9fcc-a98f8f60c20a.
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Many security protocols are built as the composition of an application-layer protocol and a secure transport protocol, such as TLS. There are many approaches to proving the correctness of such protocols. One popular approach is verification by abstraction, in which the correctness of the application-layer protocol is proven under the assumption that the transport layer satisfies certain properties, such as confidentiality. Following this approach, we adapt the strand spaces model in order to analyse application-layer protocols that depend on an underlying secure transport layer, including unilaterally authenticating secure transport protocols, such as unilateral TLS. Further, we develop proof rules that enable us to prove the correctness of application-layer protocols that use either unilateral or bilateral secure transport protocols. We then illustrate these rules by proving the correctness of WebAuth, a single-sign-on protocol that makes extensive use of unilateral TLS. In this thesis we also present a full proof of the model's soundness. In particular, we prove that, subject to a suitable independence assumption, if there is an attack against the application-layer protocol when layered on top of a particular secure transport protocol, then there is an attack against the abstracted model of the application-layer protocol. In contrast to existing work in this area, the independence assumption consists of eight statically-checkable conditions, meaning that it can be checked statically, rather than having to consider all possible runs of the protocol. Lastly, we extend the model to allow protocols that consist of an arbitrary number of layers to be proven correct. In this case, we prove the correctness of the intermediate layers using the high-level strand spaces model, by abstracting away from the underlying transport-layers. Further, we extend the above soundness results in order to prove that the multi-layer approach is sound. We illustrate the effectiveness of our technique by proving the correctness of a couple of simple multi-layer protocols.
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Yang, Ying. "Routing protocols for wireless sensor networks: A survey." Thesis, Mittuniversitetet, Institutionen för informationsteknologi och medier, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-19700.
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Wireless sensor networks(WSNs) are different to traditional networks and are highly dependent on applications, thus traditional routing protocols cannot be applied efficiently to the networks. As the variability of both the application and the network architecture, the majority of the attention, therefore, has been given to the routing protocols. This work surveys and evaluates state-of-the-art routing protocols based on many factors including energy efficiency, delay andcomplexity, and presents several classifications for the various approaches pursued. Additionally, more attention is paid to several routing protocols and their advantages and disadvantages and, indeed, this work implements two of selected protocols, LEACH and THVRG, on the OPNET, and compares them in many aspects based on a large amount of experimental data. The survey also provides a valuable framework for comparing new and existing routing protocols. According to the evaluation for the performance of the routing protocols, this thesis provides assistance in relation to further improving the performance in relation to routing protocols. Finally, future research strategies and trends in relation to routing technology in wireless sensor networks are also provided.
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Maria, Fábio Rogério Tôrres. "Frequência dos diferentes protocolos de extrações nos tratamentos ortodônticos conduzidos na Faculdade de Odontologia de Bauru FOB-USP, nos últimos 35 anos." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/25/25134/tde-02062011-143725/.
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O presente estudo objetivou realizar um levantamento retrospectivo de todos os planejamentos ortodônticos realizados pelo Departamento de Ortodontia (FOB USP) desde 1973, para que pudessem ser avaliados os protocolos de tratamento escolhidos à época, principalmente quanto à decisão de extrações e suas freqüências. A amostra constitui-se inicialmente de 3745 documentações ortodônticas arquivadas pelo Departamento de Ortodontia, das quais 332 documentações foram descartadas seguindo alguns fatores de exclusão, tais como casos transferidos, desistências e informações e exames incompletos. A amostra total de 3413 pacientes foi avaliada de acordo com o protocolo de tratamento escolhido, classificados como: Protocolo 0 (Sem extrações); Protocolo 1 (Extrações de 4 primeiros pré-molares); Protocolo 2 (2 primeiros pré-molares superiores e 2 segundos inferiores); Protocolo 3 (2 pré-molares superiores); Protocolo 4 (4 segundos pré-molares); Protocolo 6 (Incisivos e caninos); Protocolo 7 (Primeiros e segundos molares); Protocolo 8 (extrações atípicas); Protocolo 9 (grupo de agenesias e perdas precoces). Estes protocolos aferidos, foram então divididos em 7 grupos, definidos como 7 intervalos cronológicos a cada 5 anos: Intervalo 1 (1973-1977); Intervalo 2 (1978-1982); Intervalo 3 (1983-1987); Intervalo 4 (1988-1992); Intervalo 5 (1993-1997); Intervalo 6 (1998-2002); Intervalo 7 (2003-2007). Estes intervalos foram então comparados entre si para que as freqüências dos protocolos pudessem definir possíveis tendências predominantes a cada época testada. Os resultados demonstraram diferenças estatisticamente significantes para 7 dos 10 protocolos avaliados entre os intervalos considerados, evidenciando uma grande diferença de freqüência dos principais protocolos de tratamento ao longo destes 35 anos avaliados. Portanto conclui-se que a escolha pelos protocolos de tratamento sofreram influências de filosofias e dogmas vigentes durante os intervalos avaliados.The purpose of this retrospective study was to evaluate all orthodontic treatment plannings conducted at the Orthodontic Department at Bauru Dental School, University of São Paulo, since 1973, in order to investigate extraction and nonextraction frequency protocols selected at each considered period. The sample comprised initially 3745 records of treated patients, that according to exclusion criteria, reduced the final sample to 3413 documentations. This total sample was evaluated according to the protocol choice, being divided into 10 groups: Protocol 0 (nonextraction group); Protocol 1 (4-first premolar extractions); Protocol 2 (2-maxillary first and 2-mandibular second premolar extractions); Protocol 3 (2-maxillary premolar extractions); Protocol 4 (4-second premolar extractions); Protocol 5 (asymmetric premolar extractions); Protocol 6 (incisor and canine extractions); Protocol 7 (first and second molar extractions); Protocol 8 (atypical extractions) and Protocol 9 (agenesis and previously missing teeth group). These 3413 obtained protocols were divided into seven 5-year intervals: Interval 1 (1973-1977); Interval 2 (1978-1982); Interval 3 (1983-1987); Interval 4 (1988-1992); Interval 5 (1993-1997); Interval 6 (1998-2002); Interval 7 (2003-2007). The frequency of each protocol was compared among the 7 intervals, using the Proportion Test, in order to identify some predominant trends at each tested period. The results showed that 7 frequency protocols were significantly different among the 7 considered intervals, evidencing that the protocols choice was influenced by some dominant philosophies or dogmas during the evaluated periods.
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Guedj, Michaël. "BSP algorithms for LTL & CTL model checking of security protocols." Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1081.
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Dans un monde fortement dépendant de la communication de données distribuées, la conception d’infrastructures sécurisées est une tâche cruciale. Les systèmes et réseaux distribués prennent de plus en plus d’importance, car la plupart des services et des possibilités qui caractérisent la société moderne sont basés sur ces technologies.La communication entre les agents sur les réseaux a donc suscité un grand intérêt pour la recherche. Afin de fournir des moyens de communication efficaces et fiables, de plus en plus de protocoles de communication sont inventés, et pour la plupart d’entre eux, la sécurité est un objectif importantIn a world strongly dependent on distributed data communication, the design of secure infrastructures is a crucial task. Distributed systems and networks are becoming increasingly important, as most of the services and opportunities that characterise the modern society are based on these technologies. Communication among agents over networks has therefore acquired a great deal of research interest. In order to provide effective and reliable means of communication, more and more communication protocols are invented, and for most of them, security is a significant goal
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坂部, 俊樹, 正彦 酒井, 圭一朗 草刈, and 直樹 西田. "Verifying Cryptographic Protocols." INTELLIGENT MEDIA INTEGRATION NAGOYA UNIVERSITY / COE, 2005. http://hdl.handle.net/2237/10378.
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Jaspan, Ciera N. C. "Proper Plugin Protocols." Research Showcase @ CMU, 2011. http://repository.cmu.edu/dissertations/189.
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The ability of the software engineering community to achieve high levels of reuse from software frameworks has been tempered by the difficulty in understanding how to reuse them properly. When written correctly, a plugin can take advantage of the framework’s code and architecture to provide a rich application with relatively few lines of code. Unfortunately, doing this correctly is difficult because frameworks frequently require plugin developers to be aware of complex protocols between objects, and improper use of these protocols causes exceptions and unexpected behavior at run time. This dissertation introduces collaboration constraints, rules governing how multiple objects may interact in a complex protocol. These constraints are particularly difficult to understand and analyze because they may extend across type boundaries and even programming language boundaries. This thesis improves the state of the art through two mechanisms. First, it provides a deep understanding of these collaboration constraints and the framework designs which create them. Second, it introduces Fusion, an adoptable specification language and static analysis tool, that detects broken collaboration constraints in plugin code and demonstrates how to achieve this goal in a cost-effective manner that is practical for industry use.
In this dissertation, I have done an empirical study of framework help forums which showed that collaboration constraints are burdensome for developers, as they take hours or even days to resolve. From this empirical study, I have identified several common properties of collaboration constraints. This motivated a new specification language, called Fusion, that is tailored for specifying collaboration constraints in a practical way. The specification language uses relationships to describe the abstract associations between objects and allows developers to specify collaboration constraints as logical predicates of relationships. Since a relationship is an abstraction above the code, this allows developers to easily specify constraints that cross type and language boundaries. There are three variants of the analysis: a sound variant that has false positives but no false negatives, a complete variant that has false negatives but no false positives, and a pragmatic variant that attempts to balance this tradeoff. In this dissertation, I successfully used Fusion to specify and analyze constraints from examples found in the help forums of the ASP.NET and Spring frameworks. Additionally, I ran Fusion on DaCapo, a 1.5 MLOC DaCapo benchmark for program analysis, to show that Fusion is scalable and provides precise enough results for industry with low specification cost.
This dissertation examines many tradeoffs: the tradeoffs of framework designs, the tradeoffs of specification precision, and the tradeoffs of program analysis results are all featured. A central theme of this work is that there is no single right solution to collaboration constraints; there are only solutions that work better for a particular instance of the problem.
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Attamah, M. K. "Epistemic gossip protocols." Thesis, University of Liverpool, 2015. http://livrepository.liverpool.ac.uk/3001317/.
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In this thesis we study epistemic protocols for gossip. Each agent in the gossip scenario knows a unique piece of information which is called a secret. Agents communicate with each other by means of pairwise telephone calls, and in each call the calling pair of agents exchange all the secrets they currently know. In an epistemic gossip protocol, an agent 'a' can call another agent 'b', not because it is so instructed, but because agent 'a' knows that it satisfies some knowledge-based condition defined by the protocol. The goal of gossiping is typically epistemic, for example, that after a sequence of calls, every agent knows the secret of every other agent. The question then arises as to which knowledge conditions bring about the goal of gossiping, and what properties the resulting protocols have. In this thesis we describe a theoretical framework for the study of epistemic gossip protocols based on dynamic epistemic logic. We describe a number of epistemic gossip protocols and formalise these protocols using our theoretical framework. We study and prove the dynamic properties of these protocols in various types of underlying network topologies such as the line topology network, circle topology network, tree topology network, and the complete topology network. Based on our theoretical framework, we implement a software framework for describing, modelling and checking the dynamic properties of epistemic gossip protocols. We call this software framework the Epistemic Gossip Protocol (EGP) tool. The EGP tool automates the checking of dynamic properties of a given epistemic gossip protocol, such as, whether the given protocol achieves the goal of gossiping for every execution sequence of the protocol, whether the given protocol can produce execution sequences that lead to a deadlock, or whether the given protocol can produce an infinite execution sequence due to a loop. We describe the details of the implementation of the EGP tool, and use the tool to model, and check the dynamic properties of our example protocols. We present and discuss the results obtained from our experiments with the EGP tool.
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Bedrax-Weiss, Tania. "Optimal search protocols /." view abstract or download file of text, 1999. http://wwwlib.umi.com/cr/uoregon/fullcit?p9948016.
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Thesis (Ph. D.)--University of Oregon, 1999.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 206-211). Also available for download via the World Wide Web; free to University of Oregon users. Address: http://wwwlib.umi.com/cr/uoregon/fullcit?p9948016.
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Njoya, Nadine Katia. "Contraction-Expansion Protocols." Digital Commons @ East Tennessee State University, 2008. https://dc.etsu.edu/etd/1971.
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An approach to a new class of compounds known as bridgehead dienone is described. The route is based on a tandem contraction-expansion event in which the contraction triggers the expansion. The two steps involved are a palladium-catalyzed Favorskii contraction and a cis-divinyl cyclopropanone rearrangement. Progress towards these goals is reported.
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Shah, Munam Ali. "A novel MAC protocol for cognitive radio networks." Thesis, University of Bedfordshire, 2013. http://hdl.handle.net/10547/301090.
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The scarcity of bandwidth in the radio spectrum has become more vital since the demand for wireless applications has increased. Most of the spectrum bands have been allocated although many studies have shown that these bands are significantly underutilized most of the time. The problem of unavailability of spectrum bands and the inefficiency in their utilization have been smartly addressed by the cognitive radio (CR) technology which is an opportunistic network that senses the environment, observes the network changes, and then uses knowledge gained from the prior interaction with the network to make intelligent decisions by dynamically adapting transmission characteristics. In this thesis, recent research and survey about the advances in theory and applications of cognitive radio technology has been reviewed. The thesis starts with the essential background on cognitive radio techniques and systems and discusses those characteristics of CR technology, such as standards, applications and challenges that all can help make software radio more personal. It then presents advanced level material by extensively reviewing the work done so far in the area of cognitive radio networks and more specifically in medium access control (MAC) protocol of CR. The list of references will be useful to both researchers and practitioners in this area. Also, it can be adopted as a graduate-level textbook for an advanced course on wireless communication networks. The development of new technologies such as Wi-Fi, cellular phones, Bluetooth, TV broadcasts and satellite has created immense demand for radio spectrum which is a limited natural resource ranging from 30KHz to 300GHz. For every wireless application, some portion of the radio spectrum needs to be purchased, and the Federal Communication Commission (FCC) allocates the spectrum for some fee for such services. This static allocation of the radio spectrum has led to various problems such as saturation in some bands, scarcity, and lack of radio resources to new wireless applications. Most of the frequencies in the radio spectrum have been allocated although many studies have shown that the allocated bands are not being used efficiently. The CR technology is one of the effective solutions to the shortage of spectrum and the inefficiency of its utilization. In this thesis, a detailed investigation on issues related to the protocol design for cognitive radio networks with particular emphasis on the MAC layer is presented. A novel Dynamic and Decentralized and Hybrid MAC (DDH-MAC) protocol that lies between the CR MAC protocol families of globally available common control channel (GCCC) and local control channel (non-GCCC). First, a multi-access channel MAC protocol, which integrates the best features of both GCCC and non-GCCC, is proposed. Second, an enhancement to the protocol is proposed by enabling it to access more than one control channel at the same time. The cognitive users/secondary users (SUs) always have access to one control channel and they can identify and exploit the vacant channels by dynamically switching across the different control channels. Third, rapid and efficient exchange of CR control information has been proposed to reduce delays due to the opportunistic nature of CR. We have calculated the pre-transmission time for CR and investigate how this time can have a significant effect on nodes holding a delay sensitive data. Fourth, an analytical model, including a Markov chain model, has been proposed. This analytical model will rigorously analyse the performance of our proposed DDH-MAC protocol in terms of aggregate throughput, access delay, and spectrum opportunities in both the saturated and non-saturated networks. Fifth, we develop a simulation model for the DDH-MAC protocol using OPNET Modeler and investigate its performance for queuing delays, bit error rates, backoff slots and throughput. It could be observed from both the numerical and simulation results that when compared with existing CR MAC protocols our proposed MAC protocol can significantly improve the spectrum utilization efficiency of wireless networks. Finally, we optimize the performance of our proposed MAC protocol by incorporating multi-level security and making it energy efficient.
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Kou, Tian. "Conformance testing of OSI protocols : the class O transport protocol as an example." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26427.
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This thesis addresses the problem of conformance testing of communication
protocol implementations. Test sequence generation techniques for finite state machines (FSM) have been developed to solve the problem of high costs of an exhaustive test. These techniques also guarantee a complete
coverage of an implementation in terms of state transitions and output functions, and therefore provide a sound test of the implementation under test. In this thesis, we have modified and applied three test sequence generation
techniques on the class 0 transport protocol. A local tester and executable test sequences for the ISO class 0 transport protocol have been developed on a portable protocol tester to demonstrate the practicality of the test methods and test methodologies. The local test is achieved by an upper tester residing on top of the implementation under test (IUT) and a lower tester residing at the bottom of the IUT. Tests are designed based on the state diagram of an IUT. Some methodologies of parameter variations have also been used to test primitive parameters of the implementation. Some problems encountered during the implementation of the testers and how they are resolved are also discussed in the thesis.Science, Faculty of
Computer Science, Department of
Graduate
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Muhammad, Shahabuddin. "EXTENDING DISTRIBUTED TEMPORAL PROTOCOL LOGIC TO A PROOF BASED FRAMEWORK FOR AUTHENTICATION PROTOCOLS." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3086.
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Running critical applications, such as e-commerce, in a distributed environment requires assurance of the identities of the participants communicating with each other. Providing such assurance in a distributed environment is a difficult task. The goal of a security protocol is to overcome the vulnerabilities of a distributed environment by providing a secure way to disseminate critical information into the network. However, designing a security protocol is itself an error-prone process. In addition to employing an authentication protocol, one also needs to make sure that the protocol successfully achieves its authentication goals. The Distributed Temporal Protocol Logic (DTPL) provides a language for formalizing both local and global properties of distributed communicating processes. The DTPL can be effectively applied to security protocol analysis as a model checker. Although, a model checker can determine flaws in a security protocol, it can not provide proof of the security properties of a protocol. In this research, we extend the DTPL language and construct a set of axioms by transforming the unified framework of SVO logic into DTPL. This results into a deductive style proof-based framework for the verification of authentication protocols. The proposed framework represents authentication protocols and concisely proves their security properties. We formalize various features essential for achieving authentication, such as message freshness, key association, and source association in our framework. Since analyzing security protocols greatly depends upon associating a received message to its source, we separately analyze the source association axioms, translate them into our framework, and extend the idea for public-key protocols. Developing a proof-based framework in temporal logic gives us another verification tool in addition to the existing model checker. A security property of a protocol can either be verified using our approach, or a design flaw can be identified using the model checker. In this way, we can analyze a security protocol from both perspectives while benefiting from the representation of distributed temporal protocol logic. A challenge-response strategy provides a higher level of abstraction for authentication protocols. Here, we also develop a set of formulae using the challenge-response strategy to analyze a protocol at an abstract level. This abstraction has been adapted from the authentication tests of the graph-theoretic approach of strand space method. First, we represent a protocol in logic and then use the challenge-response strategy to develop authentication tests. These tests help us find the possibility of attacks on authentication protocols by investigating the originator of its received messages. Identifying the unintended originator of a received message indicates the existence of possible flaws in a protocol. We have applied our strategy on several well-known protocols and have successfully identified the attacks.Ph.D.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Computer Science PhD
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Scerri, Guillaume. "Proof of security protocols revisited." Thesis, Cachan, Ecole normale supérieure, 2015. http://www.theses.fr/2015DENS0002/document.
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Avec la généralisation d'Internet, l'usage des protocoles cryptographiques est devenu omniprésent. Étant donné leur complexité et leur l'aspect critique, une vérification formelle des protocoles cryptographiques est nécessaire.Deux principaux modèles existent pour prouver les protocoles. Le modèle symbolique définit les capacités de l'attaquant comme un ensemble fixe de règles, tandis que le modèle calculatoire interdit seulement a l'attaquant derésoudre certain problèmes difficiles. Le modèle symbolique est très abstrait et permet généralement d'automatiser les preuves, tandis que le modèle calculatoire fournit des garanties plus fortes.Le fossé entre les garanties offertes par ces deux modèles est dû au fait que le modèle symbolique décrit les capacités de l'adversaire alors que le modèle calculatoire décrit ses limitations. En 2012 Bana et Comon ont proposé unnouveau modèle symbolique dans lequel les limitations de l'attaquant sont axiomatisées. De plus, si la sémantique calculatoire des axiomes découle des hypothèses cryptographiques, la sécurité dans ce modèle symbolique fournit desgaranties calculatoires.L'automatisation des preuves dans ce nouveau modèle (et l'élaboration d'axiomes suffisamment généraux pour prouver un grand nombre de protocoles) est une question laissée ouverte par l'article de Bana et Comon. Dans cette thèse nous proposons une procédure de décision efficace pour une large classe d'axiomes. De plus nous avons implémenté cette procédure dans un outil (SCARY). Nos résultats expérimentaux montrent que nos axiomes modélisant la sécurité du chiffrement sont suffisamment généraux pour prouver une large classe de protocolesWith the rise of the Internet the use of cryptographic protocols became ubiquitous. Considering the criticality and complexity of these protocols, there is an important need of formal verification.In order to obtain formal proofs of cryptographic protocols, two main attacker models exist: the symbolic model and the computational model. The symbolic model defines the attacker capabilities as a fixed set of rules. On the other hand, the computational model describes only the attacker's limitations by stating that it may break some hard problems. While the former is quiteabstract and convenient for automating proofs the later offers much stronger guarantees.There is a gap between the guarantees offered by these two models due to the fact the symbolic model defines what the adversary may do while the computational model describes what it may not do. In 2012 Bana and Comon devised a new symbolic model in which the attacker's limitations are axiomatised. In addition provided that the (computational semantics) of the axioms follows from the cryptographic hypotheses, proving security in this symbolic model yields security in the computational model.The possibility of automating proofs in this model (and finding axioms general enough to prove a large class of protocols) was left open in the original paper. In this thesis we provide with an efficient decision procedure for a general class of axioms. In addition we propose a tool (SCARY) implementing this decision procedure. Experimental results of our tool shows that the axioms we designed for modelling security of encryption are general enough to prove a large class of protocols
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Kobeissi, Nadim. "Formal verification for real-world cryptographic protocols and implementations." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEE065.
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Les particuliers et les organisations comptent de plus en plus sur le Web et sur les applications destinées aux utilisateurs pour des cas d'utilisation comme les services bancaires en ligne, la messagerie sécurisée, le partage de documents et le vote électronique. Pour protéger la confidentialité et l'intégrité de ces communications, ces systèmes dépendent de protocoles d'authentification et d'autorisation, de constructions cryptographiques au niveau de l'application et de protocoles cryptographiques au niveau du transport. Cependant, la combinaison de ces divers mécanismes pour atteindre des objectifs de sécurité de haut niveau est sujette à l'erreur et a conduit à de nombreuses attaques, même contre des applications sophistiquées et bien étudiées. Cette thèse vise à développer des méthodes et des techniques de raisonnement, de conception et de mise en œuvre de protocoles cryptographiques et de composants d'application sécurisés pertinents pour certains des protocoles et applications cryptographiques les plus fréquemment utilisés. Nous étudions et formalisons diverses notions de garanties attendues et évaluons si certains des protocoles de canaux sécurisés les plus populaires, tels que les protocoles de messagerie sécurisée et les protocoles de transport fonctionnant souvent à l'échelle du milliard d'utilisateurs, sont capables d'atteindre ces objectifs. Dans cette thèse, nous posons la question suivante : les principaux paradigmes existants pour la vérification formelle des protocoles peuvent-ils servir de lignes directrices pour l'évaluation des protocoles existants, le prototypage des protocoles en cours de conception et la conception de protocoles entièrement nouveaux, d'une manière qui soit significative et qui reflète leurs propriétés réelles prévues ? Et pouvons-nous développer de nouveaux cadres pour une vérification formelle et une mise en œuvre plus sûre sur la base de ces fondements ? Nous proposons de nouveaux modèles formels dans des cadres de vérification formelle à la fois symboliques et calculatoires pour ces protocoles et applications. Dans certains des travaux présentés, nous obtenons une méthodologie de vérification qui part du protocole et se termine au code d'implémentation. Dans d'autres parties de notre travail, nous développons un cadre dynamique pour générer des modèles de vérification formels pour tout protocole de canal sécurisé décrit dans une syntaxe légère. En fin de compte, cette thèse présente des approches de vérification formelle pour les protocoles existants en vue de leur mise en œuvre, ainsi que des méthodes de prototypage et de vérification formelle de nouveaux protocoles en cours de rédaction et de conceptionIndividuals and organizations are increasingly relying on the Web and on user-facing applications for use cases such as online banking, secure messaging, document sharing and electronic voting. To protect the confidentiality and integrity of these communications, these systems depend on authentication and authorization protocols, on application-level cryptographic constructions and on transport-layer cryptographic protocols. However, combining these varied mechanisms to achieve high-level security goals is error-prone and has led to many attacks even on sophisticated and well-studied applications. This thesis aims to develop methods and techniques for reasoning about, designing and implementing cryptographic protocols and secure application components relevant to some of the most frequently used cryptographic protocols and applications. We investigate and formalize various notions of expected guarantees and evaluate whether some of the most popular secure channel protocols, such as secure messaging protocols and transport protocols often operating at the billion-user scale, are capable of meeting these goals. In this thesis, we ask: can existing major paradigms for formal protocol verification serve as guidelines for the assessment of existing protocols, the prototyping of protocols being designed, and the conception of entirely new protocols, in a way that is meaningful and reflective of their expected real-world properties? And can we develop novel frameworks for formal verification and more secure implementation based on these foundations? We propose new formal models in both symbolic and computational formal verification frameworks for these protocols and applications. In some of the presented work, we obtain a verification methodology that starts from the protocol and ends at the implementation code. In other parts of our work, we develop a dynamic framework for generating formal verification models for any secure channel protocol described in a lightweight syntax. Ultimately, this thesis presents formal verification approaches for existing protocols reaching towards their implementation as well as methods for prototyping and formally verifying new protocols as they are being drafted and designed
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Sadrin, Stéphane. "Evaluation du bénéfice chez l'homme des probiotiques dans la prise en charge du syndrome de l'intestin irritable : méthodologie de l'essai contrôlé randomisé et allégations nutritionnelles et de santé." Thesis, Toulon, 2017. http://www.theses.fr/2017TOUL0007/document.
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Une allégation de santé dans l’UE nécessite des preuves cliniques de l’efficacité et de la sécuritéd’une supplémentation nutrititionnelle. Les probiotiques, en particulier les bactéries lactiques,rentrent dans ce cadre règlementaire dans lequel l’EFSA indique que les preuves obtenues chez despatients avec des troubles fonctionnels intestinaux sont transposables chez une population de sujetssains. Le protocole LAPIBSS est un essai clinique de haute qualité méthodologique évaluantl’efficacité de 2 souches de Lactobacillus acidophilus à diminuer la sévérité des symptômes dusyndrome de l’intestin irritable. Les résultats confirment la sécurité d’emploi des souches utiliséesmais ne montrent pas une diminution significative des symptômes comparée au placebo après 8semaines. L’effet global du traitement est statistiquement significatif sur le score de flatulence. Uneffet placebo et l’hétérogénéité importante de la sévérité des symptômes à l’inclusion pourraientexpliquer nos résultats. Une meilleure compréhension des effets physiologiques des probiotiqueschez l’homme pourrait améliorer le rationnel de leur utilisation en recherche cliniqueA health claim across the EU requires clinical evidence about the efficacy and safety of a nutritionalsupplementation. Probiotics, especially lactic acid bacteria, fall within this regulatory framework inwhich EFSA indicates that the evidence from patients with functional gastrointestinal disorder aretransferable in a population of healthy subjects. The LAPIBSS protocol is a high-quality clinicaltrial assessing the efficacy of 2 strains of Lactobacillus acidophilus to reduce the irritable bowelsyndrome symptoms severity. Results confirm the safety of strains used but do not show asignificant decrease of symptoms compared with placebo after 8 weeks. The overall treatment effectis statistically significant on the flatus score. A placebo effect and the considerable heterogeneity ofsymptoms severity at baseline would explain our results. A better understanding of physiologicaleffects of probiotics in human would be needed to upgrade the rationale for their use in clinicalresearch
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Wibling, Oskar. "Creating Correct Network Protocols." Doctoral thesis, Uppsala universitet, Avdelningen för datorteknik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9361.
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Network protocol construction is a complex and error prone task. The challenges originate both from the inherent complexity of developing correct program code and from the distributed nature of networked systems. Protocol errors can have devastating consequences. Even so, methods for ensuring protocol correctness are currently only used to a limited extent. A central reason for this is that they are often complex and expensive to employ. In this thesis, we develop methods to perform network protocol testing and verification, with the goal to make the techniques more accessible and readily adoptable. We examine how to formulate correctness requirements for ad hoc routing protocols used to set up forwarding paths in wireless networks. Model checking is a way to verify such requirements automatically. We investigate scalability of finite-state model checking, in terms of network size and topological complexity, and devise a manual abstraction technique to improve scalability. A methodology combining simulations, emulations, and real world experiments is developed for analyzing the performance of wireless protocol implementations. The technique is applied in a comparison of the ad hoc routing protocols AODV, DSR, and OLSR. Discrepancies between simulations and real world behavior are identified; these are due to absence of realistic radio propagation and mobility models in simulation. The issues are mainly related to how the protocols sense their network surroundings and we identify improvements to these capabilities. Finally, we develop a methodology and a tool for automatic verification of safety properties of infinite-state network protocols, modeled as graph transformation systems extended with negative application conditions. The verification uses symbolic backward reachability analysis. By introducing abstractions in the form of summary nodes, the method is extended to protocols with recursive data structures. Our tool automatically verifies correct routing of the DYMO ad hoc routing protocol and several nontrivial heap manipulating programs.
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Steine, Asgeir. "Privacy-Preserving Cryptographic Protocols." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for matematiske fag, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-17284.
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Williams, Douglas E. "Fault-tolerant authentication protocols." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0020/NQ58112.pdf.
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Clayton, Richard Vincent. "Structuring and destructuring protocols." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/8492.
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Papanikolaou, Nikolaos K. "Model checking quantum protocols." Thesis, University of Warwick, 2009. http://wrap.warwick.ac.uk/2236/.
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This thesis describes model checking techniques for protocols arising in quantum information theory and quantum cryptography. We discuss the theory and implementation of a practical model checker, QMC, for quantum protocols. In our framework, we assume that the quantum operations performed in a protocol are restricted to those within the stabilizer formalism; while this particular set of operations is not universal for quantum computation, it allows us to develop models of several useful protocols as well as of systems involving both classical and quantum information processing. We detail the syntax, semantics and type system of QMC’s modelling language, the logic QCTL which is used for verification, and the verification algorithms that have been implemented in the tool. We demonstrate our techniques with applications to a number of case studies.
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Chang, Che-Hao Albert. "Reasoning about security protocols." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621505.
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Luo, Yi. "Spatio-temporal negotiation protocols." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4972.
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Canonical problems are simplified representations of a class of real world problems. They allow researchers to compare algorithms in a standard setting which captures the most important challenges of the real world problems being modeled. In this dissertation, we focus on negotiating a collaboration in space and time, a problem with many important real world applications. Although technically a multi-issue negotiation, we show that the problem can not be represented in a satisfactory manner by previous models. We propose the "Children in the Rectangular Forest" (CRF) model as a possible canonical problem for negotiating spatio-temporal collaboration. In the CRF problem, two embodied agents are negotiating the synchronization of their movement for a portion of the path from their respective sources to destinations. The negotiation setting is zero initial knowledge and it happens in physical time. As equilibrium strategies are not practically possible, we are interested in strategies with bounded rationality, which achieve good performance in a wide range of practical negotiation scenarios. We design a number of negotiation protocols to allow agents to exchange their offers. The simple negotiation protocol can be enhanced by schemes in which the agents add additional information of the negotiation flow to aid the negotiation partner in offer formation. Naturally, the performance of a strategy is dependent on the strategy of the opponent and the characteristics of the scenario. Thus we develop a set of metrics for the negotiation scenario which formalizes our intuition of collaborative scenarios (where the agents' interests are closely aligned) versus competitive scenarios (where the gain of the utility for one agent is paid off with a loss of utility for the other agent). Finally, we further investigate the sophisticated strategies which allow agents to learn the opponents while negotiating.; We find strategies can be augmented by collaborativeness analysis: the approximate collaborativeness metric can be used to cut short the negotiation. Then, we discover an approach to model the opponent through Bayesian learning. We assume the agents do not disclose their information voluntarily: the learning needs to rely on the study of the offers exchanged during normal negotiation. At last, we explore a setting where the agents are able to perform physical action (movement) while the negotiation is ongoing. We formalize a method to represent and update the beliefs about the valuation function, the current state of negotiation and strategy of the opponent agent using a particle filter. By exploring a number of different negotiation protocols and several peer-to-peer negotiation based strategies, we claim that the CRF problem captures the main challenges of the real world problems while allows us to simplify away some of the computationally demanding but semantically marginal features of real world problems.ID: 029808814; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 128-131).
Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
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Wei, K.-K. "Modelling of communication protocols." Thesis, University of York, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373307.
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Powell, Dave, and Paul Cook. "Community of Programming Protocols." International Foundation for Telemetering, 2009. http://hdl.handle.net/10150/606110.
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ITC/USA 2009 Conference Proceedings / The Forty-Fifth Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2009 / Riviera Hotel & Convention Center, Las Vegas, NevadaAs new products are developed for the telemetry market, network interfaces are being used for set-up and control. This paper describes the programmability of various telemetry components that are now available and discusses the internal status functions that can be returned to the user or telemetry system via the same interface that are good indicators of system health. Possible control interfaces are discussed that could be used to interface many different components. Also discussed is the need for the Range Commanders Council to address the total programmability protocol issues related to connecting multiple components into a common setup and control bus.
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Oberdan, Thomas. "Protocols, truth and convention." Amsterdam ; Atlanta, GA : Rodopi, 1993. http://catalogue.bnf.fr/ark:/12148/cb35609110v.
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Nuggehalli, Pavan S. "Energy conscious communication protocols /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2003. http://wwwlib.umi.com/cr/ucsd/fullcit?p3091328.
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Williams, James Pate. "A quantitative study of musical instrument digital interface (MIDI) over Internet Protocol (IP) protocols." Auburn, Ala., 2005. http://repo.lib.auburn.edu/2005%20Fall/Dissertation/WILLIAMS_JAMES_14.pdf.
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Iyengar, Janardhan R. "End-to-end concurrent multipath transfer using transport layer multihoming." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 1.67 Mb., p. 123, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3220807.
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Li, Kang. "Modeling the bandwidth sharing behavior of congestion controlled flows /." Full text open access at:, 2002. http://content.ohsu.edu/u?/etd,632.
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Barros, Gavilanes Juan Gabriel. "Réseaux de capteurs pour applications de suivi médical." Phd thesis, Toulouse, INPT, 2013. http://oatao.univ-toulouse.fr/10664/1/barros.pdf.
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Le maintien des personnes à domicile est une perspective sérieusement envisagée dans le contexte actuel de vieillissement de la population. Selon les statistiques, près d'un habitant sur trois aurait plus de 60 ans en 2050, contre un sur cinq en 2005. Cependant, les solutions actuelles de téléassistance (bouton alarme sur un collier par exemple) ont montré leurs limites. La thèse consiste à étudier des applications du futur permettant de fournir à une personne maintenue à domicile ou à l’hôpital une meilleure solution alternative fondée sur les réseaux de capteurs, capable de mesurer certains de ses paramètres physiologiques et de transmettre des données importantes aux infirmières ou médecins. Ces applications doivent s’adapter aux besoins médicaux et avoir un coût économique faible. Nous nous sommes focalisés sur des solutions de type réseaux de capteurs qui ont un coût de développement et de mise en œuvre faibles. Ce type de réseaux de capteurs offre de nouveaux services tels que la surveillance médicale et l'amélioration de la sécurité par la propagation d'alertes d'urgence. Cependant, la forte mobilité et le changement rapide de la topologie du réseau présentent un verrou scientifique et social. En outre, l'interférence de différents capteurs augmente la difficulté d'implantation de ce genre de réseaux IEEE 802.15.4. Depuis ces dernières années, plusieurs solutions ont été étudiées, comme nous le verrons dans cette thèse. Nous nous intéressons à la fiabilité de transmission dans cette thèse, car un réseau de capteurs est très limité par la capacité de calcul, de stockage et de transfert. Nous nous interrogeons dans un premier temps sur la meilleure méthode pour la livraison des données. Nous avons sélectionné les protocoles unicast et multicast issus du domaine MANET dans le but de comparer leurs avantages et inconvénients dans le contexte des applications de surveillance médicale. Nous nous sommes intéressés aux mécanismes de mise en place et au renforcement de la route dans chacun des protocoles. Les résultats de cette première étude montrent que les protocoles multicast s’adaptent mieux aux applications, car ils permettent de réduire le nombre de paquets transmis dans le réseau. Même si certains protocoles pourraient amener une meilleure performance (en ce qui concerne le débit utile) que d’autres, aucun protocole ne satisfait une application réelle. Nous travaillons sur l’exploitation d'un réseau hétérogène en distinguant les nœuds forts et les nœuds faibles. Dans ce cadre, nous avons proposé une nouvelle approche, HMR, qui permet de mieux assurer la performance du réseau par rapport aux solutions existantes. Une dernière problématique à étudier dans cette thèse est l’agrégation de données, car les données à transmettre dans le réseau sont souvent périodiquement générées avec des tailles très restreintes (quelques octets, par exemple). Nos études montrent que l’agrégation de données est une bonne solution. Cette thèse a donné lieu à deux publications en conférences internationales avec comité de lecture.
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Lu, Jing. "Semi-automatic protocol implementation using an Estelle-C compiler, LAPB and RTS protocols as examples." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29419.
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Formal Description Techniques allow for the use of automated tools during the specification
and development of communication protocols. Estelle is a standardized formal description technique developed by ISO to remove ambiguities in the specification of communication protocols and services. The UBC Estelle-C compiler automates the implementation
of protocols by producing an executable C implementation directly from its Estelle specification. In this thesis, we investigate the automated protocol implementation
methodology using the Estelle-C compiler. First, we describe the improvements made to the compiler to support the latest version of Estelle. Then, we present and discuss the semiautomated implementations of the LAPB protocol in the CCITT X.25 Recommendation and the RTS protocol in the CCITT X.400 MHS series using this compiler.
Finally, we compare the automatic and manual protocol implementations of LAPB and RTS protocols in terms of functional coverage, development time, code size, and performance measure. The results strongly indicate the overall advantages of automatic protocol implementation method over the manual approach.Science, Faculty of
Computer Science, Department of
Graduate
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Maciel, Luciana França Smith. "Expressão dos receptores endometriais de estrógeno e progesterona em éguas acíclicas após administração de progesterona." Botucatu, 2017. http://hdl.handle.net/11449/151275.
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Orientador: Cezinande de MeiraResumo: Progesterone (P4) is frequently used after the administration of estradiol, to prepare seasonal non-cyclic mares as embryo recipients, however previous studies have reported gestation of seasonal non-cyclic mares treated only with P4. The objective of the present study was to evaluate the gene and protein expression of estrogen receptor alpha (ERα), estrogen beta (ERβ) and progesterone (PR) in the endometrium of seasonal non-cyclic mares treated with long acting progesterone (LAP4). Eight mares were used during the seasonal anoestrus phase, uterine biopsies were performed immediately before and five days after administration of 1,5 g of LA P4. Blood samples were taken daily for the determination of plasma P4 concentration. The protein expression of the receptors was evaluated by the immunohistochemistry and the immunostaining area percentage was determined by the ImageJ software. Transcripts abundance for ERα (ESR1), ERβ (ESR2) and PR (PGR) were determined by RT-qPCR. ERα showed higher protein expression (p <0.05) after administration of P4LA, but there was no change in mRNA abundance encoding this gene (p> 0,05). Tendency to lower protein expression was observed (p=0,07) and gene expression inhibition (p <0,05) for ERβ, PR did not changes (p>0,05). The plasma concentration of P4 presented a higher concentration 24 hours after the application of LA P4 (D1), with subsequent decline in these values (p<0,05). The 1.5 g dose of LA P4 reached the minimum concentrations of P4 requi... (Resumo completo, clicar acesso eletrônico abaixo)
Mestre
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Rudolph, Carsten. "A model for secure protocols and its application to systematic design of cryptographic protocols." Thesis, Queensland University of Technology, 2001.
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Koegler, Xavier. "Population protocols, games and large populations." Paris 7, 2012. http://www.theses.fr/2012PA077132.
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Le modèle des populations protocols a été proposé pour capturer les spécificités de réseaux opportunistes constitués d'une population d'agents mobiles à la mémoire limitée capables de communications sans fil par paires. L'objet de cette thèse est d'étendre la compréhension et l'analyse des population protocols ainsi que leurs liens avec d'autres modèles de dynamiques de populations. La première contribution de cette thèse est l'étude de la traduction en terme de protocoles de population de la dynamique d'une population d'agents jouant à un jeu de manière répétée les uns contre les autres et adaptant leur stratégie selon le comportement de PAVLOV. Nous montrons que les protocoles issus de tels jeux sont aussi puissants que les protocoles de population généraux. La deuxième contribution consiste à étudier des hypothèse de symétrie dans les jeux et dans les transitions d'un protocole de population, pour montrer que, si les protocoles de population symétriques sont équivalents aux protocoles généraux, les jeux symétriques sont, eux, significativement moins puissants. La troisième contribution est de montrer comment étudier le comportement d'une protocole de population lorsque la taille de la population tend vers l'infini en approchant la dynamique résultante à l'aide d'une équation différentielle ordinaire et de définir un calcul par grande population comme la convergence de cette équation différentielle vers un équilibre stable. La quatrième et dernière contribution de la thèse est la caractérisation des nombres calculables en ce sens comme étant très exactement les réels algébriques des [0,1]Population protocols were introduced to capture the specifies of opportunistic networks of tny mobile agents with limited memory and capable of wireless communication in pairs. This thesis aims at extending the understanding and analysis of population protocols as well as their links to other models of population dynamics including ones from game theory. The first contribution of this thesis is to translate in terms of population protocols the dynamics of a population of agents playing a game repeatedly against each-other and adapting their strategy according to the PAVLOV behaviour. We show that protocols born from games are exactly as powerful as general population protocols. The second contribution consists in the study of the impact of symmetry on games and in the transitions of a population protocol to show that, if symmetric population protocols are equivalent to general protocols, symmetric games are significantly less powerful. The third contribution is to show how the dynamic of a population protocol can be approximated by an ordinary differential equation when the population grows to infinity. We then define a computation by a large population to be the convergence of this differential equation to a stable equilibrium. The fourth and final contribution of this thesis is the characterisation of the numbers computable in the above sense as exactly the algebraic real numbers in [0,1]
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alyanbaawi, ashraf. "DESIGN OF EFFICIENT MULTICAST ROUTING PROTOCOLS FOR COMPUTER NETWORKS." OpenSIUC, 2020. https://opensiuc.lib.siu.edu/dissertations/1775.
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Multicasting can be done in two different ways: source based tree approach andshared tree approach. Shared tree approach is preferred over source-based treeapproach because in the later construction of minimum cost tree per source is neededunlike a single shared tree in the former approach. However, in shared tree approach asingle core needs to handle the entire traffic load resulting in degraded multicastperformance. Besides, it also suffers from „single point failure‟. Multicast is acommunication between one or multiple senders and multiple receivers, which used asa way of sending IP datagrams to a group of interested receivers in one transmission.Core-based trees major concerns are core selection and core as single point of failure.The problem of core selection is to choose the best core or cores in the network toimprove the network performance.In this dissertation we propose 1) a multiple core selection approach for core-based tree multicasting, senders can select different cores to have an efficient loadbalanced multicore multicasting. It will overcome any core failure as well. 2) Novel andefficient schemes for load shared multicore multicasting are presented. Multiple coresare selected statically, that is, independent of any existing multicast groups and also theselection process is independent of any underlying unicast protocol. Some of theselected cores can be used for fault- tolerant purpose also to guard against any possible core failures. 3) We have presented two novel and efficient schemes forgroup-based load shared multicore multicasting in which members of a multicast groupuse the same core tree for their multicasting. 4) We also presented two schemes aim atachieving low latency multicasting along with load sharing for delay sensitive multicastapplications. Besides, we have presented a unique approach for core migration, whichuses two very important parameters, namely, depth of a core tree and pseudo diameterof a core. One noteworthy point from the viewpoint of fault tolerance is that the degreeof fault-tolerance can be enhanced from covering single point-failure to any number ofcore failures.
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Curty, Alonso Marcos. "Cryptographic protocols in optical communication." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=979048621.
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Gheorghiu, Steluta. "Network coding for transport protocols." Doctoral thesis, Universitat Politècnica de Catalunya, 2011. http://hdl.handle.net/10803/32195.
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With the proliferation of smart devices that require Internet connectivity anytime, anywhere, and the recent technological
advances that make it possible, current networked systems will have to provide a various range of services, such as content
distribution, in a wide range of settings, including wireless environments. Wireless links may experience temporary losses,
however, TCP, the de facto protocol for robust unicast communications, reacts by reducing the congestion window drastically
and injecting less traffic in the network. Consequently the wireless links are underutilized and the overall performance of the
TCP protocol in wireless environments is poor. As content delivery (i.e. multicasting) services, such as BBC iPlayer, become
popular, the network needs to support the reliable transport of the data at high rates, and with specific delay constraints. A
typical approach to deliver content in a scalable way is to rely on peer-to-peer technology (used by BitTorrent, Spotify and
PPLive), where users share their resources, including bandwidth, storage space, and processing power. Still, these systems
suffer from the lack of incentives for resource sharing and cooperation, and this problem is exacerbated in the presence of
heterogenous users, where a tit-for-tat scheme is difficult to implement.
Due to the issues highlighted above, current network architectures need to be changed in order to accommodate the users¿
demands for reliable and quality communications. In other words, the emergent need for advanced modes of information
transport requires revisiting and improving network components at various levels of the network stack.
The innovative paradigm of network coding has been shown as a promising technique to change the design of networked
systems, by providing a shift from how data flows traditionally move through the network. This shift implies that data flows are
no longer kept separate, according to the ¿store-and-forward¿ model, but they are also processed and mixed in the network. By
appropriately combining data by means of network coding, it is expected to obtain significant benefits in several areas of
network design and architecture.
In this thesis, we set out to show the benefits of including network coding into three communication paradigms, namely point-topoint
communications (e.g. unicast), point-to-multipoint communications (e.g. multicast), and multipoint-to-multipoint
communications (e.g. peer-to-peer networks). For the first direction, we propose a network coding-based multipath scheme and
show that TCP unicast sessions are feasible in highly volatile wireless environments. For point-to-multipoint communications,
we give an algorithm to optimally achieve all the rate pairs from the rate region in the case of degraded multicast over the
combination network. We also propose a system for live streaming that ensures reliability and quality of service to heterogenous
users, even if data transmissions occur over lossy wireless links. Finally, for multipoint-to-multipoint communications, we design
a system to provide incentives for live streaming in a peer-to-peer setting, where users have subscribed to different levels of
quality.
Our work shows that network coding enables a reliable transport of data, even in highly volatile environments, or in delay
sensitive scenarios such as live streaming, and facilitates the implementation of an efficient incentive system, even in the
presence of heterogenous users. Thus, network coding can solve the challenges faced by next generation networks
in order to support advanced information transport.
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Jaafar, Talal Mohamed. "Simulation-Based Routing Protocols Analyses." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16197.
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A new approach to distributed network simulations that eases the burdens on the simulation developer in creating space-parallel simulations is presented. It provides a full-topology knowledge for every federate (simulator instance) to make the best routing decision to destinations simulated at other federates. Later, this technique was used to characterize the benefits of IP Anycast mechanism at large scale. Different IP Anycast scenarios were simulated in a detailed Border Gateway Protocol (BGP) simulator using a realistic large-scale AS topology. Results indicated that Anycast indeed provides higher availability and decreased end-to-end delay. It also showed that Anycast does not provide load balancing, and the BGP overhead associated with a topology change is reduced when Anycast is deployed. In addition, a simulation model of Enhanced Interior Gateway Routing Protocol (EIGRP) was developed and used to present a new approach for host mobility within an AS. The new solution is to allow end systems to retain a fixed IP address as those systems move across subnet boundaries, and to use route advertisement updates (by EIGRP) to inform routers of new or revised routes to reach the mobile hosts as they migrate. The simulation results showed the viability of this approach, and the ability of EIGRP to update routing tables in a timely fashion.
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Mohammed, Alalelddin Fuad Yousif. "Studying Media Access andControl Protocols." Thesis, KTH, Kommunikationssystem, CoS, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91193.
Full textAbstract:
This thesis project’s goal is to enable undergraduate students to gain insight into media access and control protocols based upon carrying out laboratory experiments. The educational goal is to de-mystifying radio and other link and physical layer communication technologies as the students can follow packets from the higher layers down through the physical layer and back up again. The thesis fills the gap between the existing documentation for the Universal Software Radio Peripheral (USRP) resources and the knowledge of undergraduate students. This was necessary because the existing document is targeted at advanced audiences rather than undergraduates. This thesis describes the design and evolution of a workbench for students to experiment with a variety of media access and control protocols, much as Wireshark gives students the ability to watch network and higher layer protocols. Another motivation for this thesis is that an increasing number of communication networks use complex media access and control protocols and existing tools do not allow students to see the details of what is taking place in these protocols, except via simulation. Today an software defined radio and computer are affordable as laboratory equipment for an undergraduate course. Hence the time is ripe for the development of undergraduate laboratory course material using these tools. The thesis is targeted at (1) instructors of undergraduates who might use this work to develop their own lesson plans and course material and (2) students of physical and link layer protocols who want a practical tool for carrying out experiments in these layers. Hopefully by de-mystifying these lower layers and by making the USRP more approachable by undergraduate students we will encourage lots of students to view wireless network technology as being just as approachable as a wired Ethernet. Due to the widespread use of wireless communications technologies, there is a great need by industry for more graduates who can understand communication systems from the physical to the application layer - rather than the current situation where there is a hard boundary between the lower two layers and the upper layers. While there has been a lot of research concerning cross layer optimization, much of this is theoretical and not very approachable by students. A desired outcome of this thesis project is that undergraduate students will be able to understand tradeoffs at all layers of the protocol stack and not be limited to the upper layers.Detta examensarbete har som mål att göra det möjligt för studenter att få inblick i tillgång till medierna och protokoll som grundar sig på att utföra laboratorieexperiment. Det pedagogiska målet är att de-mystifierande radio och annan länk och fysiska lagret kommunikationsteknik som studenterna kan följa paket från högre skikt ner genom det fysiska lagret och upp igen. Avhandlingen fyller gapet mellan den befintliga dokumentationen för Universal Software Radio Peripheral (usrp) resurser och kunskap om studerande. Detta var nödvändigt eftersom det befintliga dokument riktar sig till avancerade publik snarare än studenter. Denna avhandling beskriver utformningen och utvecklingen av en arbetsbänk för studenter att experimentera med olika tillgång till medierna och protokoll kontroll, mycket som Wireshark ger studenterna möjlighet att titta på nätet och högre skikt protokoll. Ett annat motiv för denna tes är att ett ökande antal kommunikationsnät använda komplicerade tillgång till medierna och protokoll kontroll och befintliga verktyg inte tillåter eleverna att se detaljer om vad som sker i dessa protokoll, utom via simulering. Idag en programvarustyrd radio och dator är överkomliga laboratorieutrustning för en grundutbildningskurs. Därför är tiden mogen för utvecklingen av grundutbildningen laborationer material med hjälp av dessa verktyg. Avhandlingen riktar sig till (1) instruktörer för studenter som kan använda detta arbete för att utveckla sin egen lektionsplanering och kursmaterial och (2) studenter på fysisk och länka protokoll skikt som vill ha ett praktiskt verktyg för att utföra experiment i dessa lager. Förhoppningsvis genom de-mystifierande de undre lagren och genom att göra usrp mer tillgänglig genom att studenter ska vi uppmuntra många elever att visa trådlös nätverksteknik vara lika lättillgänglig som ett ethernet. På grund av den utbredda användningen av trådlös kommunikationsteknik, finns ett stort behov från näringslivet för fler studenter som kan förstå kommunikationssystem från det fysiska till applikationslagret - i stället för den nuvarande situationen där det finns en hård gräns mellan de två lägre skikten och de övre skikten. Samtidigt som det har varit en hel del forskning om cross lager optimering, mycket av detta är teoretisk och inte särskilt tillgänglig av studenter. Ett önskat resultat med detta examensarbete är att studenter ska kunna förstå kompromisser på alla nivåer inom den protokollstack och inte vara begränsade till de övre skikten.
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Donta, Praveen Kumar. "Performance Analysis of Security Protocols." UNF Digital Commons, 2007. http://digitalcommons.unf.edu/etd/172.
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Security is critical to a wide range of applications and services. Numerous security mechanisms and protocols have been developed and are widely used with today’s Internet. These protocols, which provide secrecy, authentication, and integrity control, are essential to protecting electronic information.
There are many types of security protocols and mechanisms, such as symmetric key algorithms, asymmetric key algorithms, message digests, digital certificates, and secure socket layer (SSL) communication. Symmetric and asymmetric key algorithms provide secrecy. Message digests are used for authentication. SSL communication provides a secure connection between two sockets.
The purpose of this graduate project was to do performance analysis on various security protocols. These are performance comparisons of symmetric key algorithms DES (Data Encryption Standard), 3DES (Triple DES), AES (Advanced Encryption Standard), and RC4; of public-private key algorithms RSA and ElGamal; of digital certificates using message digests SHA1 (Secure Hash Algorithm) and MD5; and of SSL (Secure Sockets Layer) communication using security algorithms 3DES with SHA1 and RC4 with MD5.
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Haqqani, Mujeeb. "Fast prototyping of communication protocols." Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5718.
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In this thesis we present a methodology and a life-cycle system for rapid implementation of communication protocols. Our proposed approach includes a scheme for automated coding and decoding of protocol (single module) formal specifications in Estelle into (and from) a KnowledgeBase(KB). An interactive experimental system, FPCP (Fast Prototyping of Communication Protocols), is designed and implemented. It automatically generates an interrogatable KnowledgeBase representation of the specification, and automatically generates an executable prototype of communication software corresponding to the formal (single module, normalized) specifications in ESTELLE format. Our approach allows developers to maintain single, useful and authoritative "reference specifications" throughout the protocol development life cycle. The automated encoding of the specifications into a rule based KB allows users to take advantage of rule based system features (Mackert) and yet maintain the Estelle specifications as the single authoritative reference specifications. (Abstract shortened by UMI.)
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Bergström, Patrik. "Automated Setup of Display Protocols." Thesis, Linköpings universitet, Databas och informationsteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-117745.
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Radiologists' workload has been steadily increasing for decades. As digital technology matures it improves the workflow for radiology departments and decreases the time necessary to examine patients. Computer systems are widely used in health care and are for example used to view radiology images. To simplify this, display protocols based on examination data are used to automatically create a layout and hang images for the user. To cover a wide variety of examinations hundreds of protocols must be created, which is a time-consuming task and the system can still fail to hang series if strict requirements on the protocols are not met. To remove the need for this manual step we propose to use machine learning based on past manually corrected presentations. The classifiers are trained on the metadata in the examination and how the radiologist preferred to hang the series. The chosen approach was to create classifiers for different layout rules and then use these predictions in an algorithm for assigning series types to individual image slots according to categories based on metadata, similar to how display protocol works. The resulting presentations shows that the system is able to learn, but must increase its prediction accuracy if it is to be used commercially. Analyses of the different parts show that increased accuracy in early steps should improve overall success.Röntgenläkares arbetsbörda har under flera årtionden ökat. Den digitala sjukvårdsteknologin utvecklas ständigt vilket bidrar till ett förbättrat arbetsflöde och kortare undersökningstider i radiologiavdelningar. Datorsystem används idag överallt inom sjukvården och används bland annat för att visa bilder åt röntgenläkare. För att underlätta visningen används display protocol som automatiskt skapar layouts och hänger bilder åt användaren. För att täcka ett stort antal olika undersökningstyper krävs att användaren skapar hundratals protokoll vilket är en tidskrävande uppgift, och systemet kan ändå misslyckas med att hänga upp bilder om de strikta kraven protokollen ställer inte uppfylls. För att ta bort detta manuella steg föreslår vi att man använder maskininlärning baserat på tidigare sparade presentationer. Klassificerarna tränas på undersökningens metadata och radiologens preferenser på hängning av serier. Den valda metoden går ut på att skapa klassificerare för olika layout-regler och att sedan använda deras output i en algoritm som placerar ut series-typer till individuella bildplatser enligt kategorier baserade på metadata. Denna metod liknar den process de nuvarande display protokollen utför. De presentationer som skapats visar att systemet kan läras upp, men kräver högre precision om det ska användas kommersiellt. Analys av de olika delarna tyder på att ökad precision tidigt i systemet skulle öka den totala precision.
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Long, Nguyen Hoang. "Authentication protocols in pervasive computing." Thesis, University of Oxford, 2009. https://ora.ox.ac.uk/objects/uuid:d21c0ce6-5dd6-43ef-b6c6-01346d02031b.
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The popularity of personal computing devices (e.g. smart cards) exposes users to risks, notably identity theft, and creates new requirements for secure communication. A recently proposed approach to creating secure communication is to use human trust and human interactions. These approaches potentially eliminate the need for passwords as in Bluetooth, shared secrets or trusted parties, which are often too complex and expensive to use in portable devices. In this new technology, handheld devices exchange data (e.g. payment, heart rates or public keys) over some medium (e.g. WiFi) and then display a short and non-secret digest of the protocol's run that the devices' human owners manually compare to ensure they agree on the same data, i.e. human interactions are used to prevent fraud. In this thesis, we present several new protocols of this type which are designed to optimise the work required of humans to achieve a given level of security. We discover that the design of these protocols is influenced by several principles, including the ideas of commitment without knowledge and separation of security concerns, where random and cryptographic attacks should be tackled separately. Underpinning the technology is a new cryptographic function, termed a keyed digest function, which produces a short number for humans to compare. This is similar to the notion of a universal hash function, but its output length is shorter (e.g. 16 bits). Hence, it should be faster to compute. We propose several digest constructions using Toeplitz matrices, integer multiplication and pseudorandom numbers. The application of digest functions leads us to develop more efficient alternatives to standard digital signatures. Our protocol security analysis leads to a new bound on the key length for an almost universal hash function, which can be derived by the pigeon-hole principle. The new bound turns out to be tighter than another similar bound derived from the combination of the Singleton bound in coding theory and an equivalence between error-correcting codes and almost universal hash functions.
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Gonzãlez-Deleito, Collell Nicolãs. "Trust relationships in exchange protocols." Doctoral thesis, Universite Libre de Bruxelles, 2005. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210963.
Full textAbstract:
Les protocoles d'échange d'informations représentent un des grands domaines actuels de recherche en sécurité informatique, et sont entre autres à la base des mécanismes de commerce électronique. Ils sont par exemple nécessaires à la réalisation d'un achat en ligne, à la signature d'un contrat électronique et au courrier électronique recommandé. Dans ces exemples, les échanges d'informations consistent à échanger respectivement un objet électronique contre un paiement, des signatures digitales sur un même contrat, et un courrier électronique contre un accusé de réception.Informellement, un protocole mettant en oeuvre de tels types d'échanges est dit équitable si et seulement si à la fin du protocole soit l'échange d'information a eu lieu, soit aucune information (même en partie) n'a été échangée. Afin d'assurer cette propriété d'équité de manière efficace, et d'éviter ainsi des éventuels comportements malhonnêtes de la part des participants à l'échange d'informations qui chercheraient à nuire au bon déroulement du protocole, une tierce partie de confiance est utilisée.
Un des buts de cette thèse est de discerner les tâches devant être assurées par une telle tierce partie de confiance et développer des méthodes permettant d'en minimiser le nombre et l'importance, afin de limiter la confiance que les entités effectuant l'échange doivent porter à cette tierce partie. Pour cela, nous identifions tout d'abord de manière générique quels sont ces types de tâches, puis nous analysons sous ce point de vue les principaux protocoles ayant été proposés dans la littérature.
Cette démarche nous conduit ensuite naturellement à nous pencher sur les relations de confiance entre les participants à un protocole d'échange. Ce type de relations est particulièrement significatif pour des protocoles à plus de deux participants.
Enfin, dans ce travail, nous observons à la lumière des aspects de confiance, les différentes propriétés propres aux protocoles d'échange, et nous proposons plusieurs nouveaux protocoles ayant des besoins en confiance limités.
Doctorat en sciences, Spécialisation Informatique
info:eu-repo/semantics/nonPublished
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Koh, Sunny. "Stratified protocols for mobile gaming." University of Southern Queensland, Faculty of Sciences, 2006. http://eprints.usq.edu.au/archive/00003851/.
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[Abstract]: Mobile Games are becoming very popular. Players play games under various conditions and so we need protocols which can adapt. However, unlike the desktop, there are many issues with that of mobile communication. This dissertation proposes a stratified protocol to be implemented in order to solve these communication problems more effectively. The protocol itself dynamically adapts to the changing bandwidth capacity of the network. The term stratified means that the payload in the protocol packets is subdivided into different categories, or strata, of data which are handled differently dependingon network conditions. Such a protocol needs to be responsible as it must make decisions which do notworsen the problem of network congestion when it arises.An experiment was conducted with a view to determining whether it is important to address difficulties with technical quality of communication. This experiment showedthat gaming satisfaction of players does depend on technical quality of communication and that the way in which this dependence on technical quality is exhibited depends upon the particular gaming genre. This dependence on genre and the fact that different games make use of communication services differently suggests that stratification of communication protocols could be useful.
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Ehikioya, Sylvanus Agbonifoh. "Specification of transaction systems protocols." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq23597.pdf.
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