O gênero Lactobacillus é o principal grupo de bactérias contaminantes em dornas de fermentação para produção de etanol em larga escala. A alta proliferação destes microrganismos prejudica a viabilidade de cepas de Saccharomyces cerevisiae selecionadas, podendo diminuir a produção de etanol nas dornas de fermentação. Os métodos mais utilizados para identificação destes microrganismos são bioquímicos e moleculares baseados na sequência do DNA, que são muito demorados, onerosos e muitas vezes remetem a resultados ambíguos. MALDI-TOF MS é uma poderosa ferramenta de identificação microbiana e foi testada neste trabalho para identificação de diferentes isolados de Lactobacillus e S. cerevisiae presentes no processo de produção de etanol. Os métodos de preparo e aplicação da amostra para aquisição espectral foram estabelecidos, tanto para bactérias quanto para leveduras. Vinte e sete isolados de Lactobacillus foram identificados pela região 16S rDNA e dois genes housekeeping, pheS e groEL e, três cepas de leveduras selecionadas do processo foram identificadas pela região ITS e 28S nr-LSU. As identificações genômicas foram contrastadas com as identificações obtidas com o perfil proteico por MALDI-TOF MS e 97% dos Lactobacillus tiveram a mesma classificação molecular que o gene pheS, eleito como o mais discriminatório, e 100% das cepas de leveduras foram classificadas como S. cerevisiae por ambas as técnicas. A técnica MALDI- TOF MS se mostrou altamente eficiente para discriminação intraespecífica de leveduras e interespecífica de Lactobacillus, não havendo apenas discriminação para isolados classificados como L. casei pelos genes housekeeping. Além disso, quando comparado o poder discriminatório da técnica MALDI-TOF MS em relação ao banco de dados espectral disponível no Biotyper e, posteriormente, ao banco de dados complementar criado neste trabalho com os microrganismos próprios do processo de produção de etanol, houve um aumento de 57 a 100% das repetições que foram identificadas ao nível de espécie com alta confiabilidade. Desta forma, os resultados deste estudo mostraram que a técnica MALDI-TOF MS pode ser utilizada como uma alternativa rápida e eficaz para identificação de Lactobacillus e Saccharomyces do processo etanólico. / The genus Lactobacillus is the main group of contaminating bacteria in fermentation tanks for large-scale ethanol production. The high proliferation of these organisms affect the viability of selected strains of Saccharomyces cerevisiae, which can reduce the production of ethanol in fermentation tanks. The most used methods for identifying these microorganisms are biochemical and molecular based on DNA sequence, which are very time-consuming, costly and often revert to ambiguous results. MALDI-TOF MS is a powerful microbial identification tool and it was tested in this work to identify different isolates of Lactobacillus and S. cerevisiae present in the ethanol production process. The sample preparation and application in the MALDI plate for spectral acquisition were established for both bacteria and yeasts. Twenty-seven isolates of Lactobacillus were identified by the 16S rDNA region and two housekeeping genes (pheS and groEL genes) and three yeast strains selected from the process were identified by the ITS and 28S nr-LSU regions. The genomic identifications were compared with the MALDI-TOF MS protein profiles and 97% of the Lactobacillus had the same molecular classification as the pheS gene, which was chosen as the most discriminatory gene, and 100% of the yeast strains were classified as S. cerevisiae by both techniques. The MALDI-TOF MS technique proved highly efficient for intraspecific yeast and interspecific discrimination of Lactobacillus, and there was no discrimination for isolates classified as L. casei by housekeeping genes. Furthermore, when compared to the discriminatory power of MALDI-TOF MS technique in relation to spectral database available on Biotyper and subsequently, the complementary database created in this work with the microorganisms themselves in the ethanol production process, there was an increase from 57 to 100% of the repetitions that were identified at the species level with high reliability. Thus, the results of this study showed that the MALDI-TOF MS technique can be used as a fast and efficient alternative for the identification of Lactobacillus and Saccharomyces of the ethanolic process.

Le champ du traitement des images et des vidéos attire l'attention depuis les deux dernières décennies. Ce champ couvre maintenant un spectre énorme d'applications comme la TV 3D, la télé-surveillance, la vision par ordinateur, l'imagerie médicale, la compression, la transmission, etc. En ce début de vingt et unième siècle nous sommes témoins d'une révolution importante. Les largeurs de bande des réseaux, les capacités de mémoire et les capacités de calcul ont été fortement augmentés durant cette période. Un client peut avoir un débit de plus de 100~mbps tandis qu'un autre peut utiliser une ligne à 56~kbps. Simultanément, un client peut avoir un poste de travail puissant, tandis que d'autres peuvent avoir juste un téléphone mobile. Au milieu de ces extrêmes, il y a des milliers de clients avec des capacités et des besoins très variables. De plus, les préférences d'un client doivent s'adapter à sa capacité, par exemple un client handicapé par sa largeur de bande peut être plus intéressé par une visualisation en temps réel sans interruption que d'avoir une haute résolution. Pour y faire face, des architectures hiérarchiques de codeurs vidéo ont été introduites afin de comprimer une seule fois, et de décomprimer de différentes manières. Comme la DCT n'a pas la fonctionnalité de multi-résolution, une architecture vidéo hiérarchique est conçue pour faire face aux défis des largeurs de bande et des puissances de traitement hétérogènes. Avec l'inondation des contenus numériques, qui peuvent être facilement copiés et modifiés, le besoin de la protection des contenus vidéo a pris plus d'importance. La protection de vidéos peut être réalisée avec l'aide de trois technologies : le tatouage de méta-données et l'insertion de droits d'auteur, le cryptage pour limiter l'accès aux personnes autorisées et la prise des empreintes digitales active pour le traçage de traître. L'idée principale dans notre travail est de développer des technologies de protection transparentes à l'utilisateur. Cela doit aboutir ainsi à un codeur vidéo modifié qui sera capable de coder et d'avoir un flux de données protégé. Puisque le contenu multimédia hiérarchique a déjà commencé à voir le jour, algorithmes pour la protection indépendante de couches d 'amélioration sont également proposées. / Field of image and video processing has got lot of attention during the last two decades. This field now covers a vast spectrum of applications like 3D TV, tele-surveillance, computer vision, medical imaging, compression, transmission and much more. Of particular interest is the revolution being witnessed by the first decade of twenty-first century. Network bandwidths, memory capacities and computing efficiencies have got revolutionized during this period. One client may have a 100~mbps connection whereas the other may be using a 56~kbps dial up modem. Simultaneously, one client may have a powerful workstation while others may have just a smart-phone. In between these extremes, there may be thousands of clients with varying capabilities and needs. Moreover, the preferences of a client may adapt to his capacity, e.g. a client handicapped by bandwidth may be more interested in real-time visualization without interruption than in high resolution. To cope with it, scalable architectures of video codecs have been introduced to 'compress once, decompress many ways' paradigm. Since DCT lacks the multi-resolution functionality, a scalable video architecture is designed to cope with challenges of heterogeneous nature of bandwidth and processing power. With the inundation of digital content, which can be easily copied and modified, the need for protection of video content has got attention. Video protection can be materialized with help of three technologies: watermarking for meta data and copyright insertion, encryption to restrict access to authorized persons, and active fingerprinting for traitor tracing. The main idea in our work is to make the protection technology transparent to the user. This would thus result in a modified video codec which will be capable of encoding and playing a protected bitstream. Since scalable multimedia content has already started coming to the market, algorithms for independent protection of enhancement layers are also proposed.

In Fluid-, Filter- und Sedimentproben von vier geothermischen Anlagen des Norddeutschen Beckens wurden mit molekulargenetischen Verfahren unterschiedliche mikrobielle Gemeinschaften nachgewiesen. Die mikrobielle Zusammensetzung in den Prozesswässern wurde dabei durch die Aquiferteufe, die Salinität, die Temperatur und den verfügbaren Elektronendonatoren und -akzeptoren beeinflusst. Die in den anoxischen Prozesswässern identifizierten Organismen zeichneten sich durch einen chemoheterotrophen oder chemoautotrophen Stoffwechsel aus, wobei Nitrat, Sulfat, Eisen (III) oder Bikarbonat als terminale Elektronenakzeptoren fungierten. Mikroorganismen beeinflussten den Betrieb von zwei Anlagen negativ. So reduzierten im Prozesswasser des Kältespeichers am Berliner Reichstag vorhandene Eisenoxidierer, nahe verwandt zu der Gattung Gallionella, die Injektivität der Bohrungen durch Eisenhydroxidausfällungen in den Filterschlitzen. Biofilme, die von schwefeloxidierenden Bakterien der Gattung Thiothrix in den Filtern der obertägigen Anlage gebildet wurden, führten ebenfalls zu Betriebsstörungen, indem sie die Injektion des Fluids in den Aquifer behinderten. Beim Wärmespeicher in Neubrandenburg waren Sulfatreduzierer vermutlich an der Bildung von Eisensulfidausfällungen in den obertägigen Filtern und im bohrlochnahen Bereich beteiligt und verstärkten Korrosionsprozesse an der Pumpe im Bohrloch der kalten Aquiferseite. Organische Säuren in den Fluiden sowie mineralische Ausfällungen in den Filtern der obertägigen Anlagen waren Belege für die Aktivität der in den verschiedenen Anlagen vorhandenen Mikroorganismen. Es wurde zudem deutlich, dass Mikroorganismen auf Grund der hohen Durchflussraten in den Anlagen chemische Veränderungen in den Prozesswässern deutlich sensitiver anzeigen als chemische Analyseverfahren. So deuteten Änderungen in der Zusammensetzung der mikrobiellen Biozönosen und speziell die Identifikation von Indikatororganismen wie Eisen- und Schwefeloxidierern, fermentativen Bakterien und Sulfatreduzierern auf eine erhöhte Verfügbarkeit von Elektronendonatoren oder akzeptoren in den Prozesswässern hin. Die Ursachen für die an den Geothermieanlagen auftretenden Betriebsstörungen konnten dadurch erkannt werden. / Distinct microbial communities were found in fluid, filter, and sediment samples taken from four geothermal plants in the North German Basin by using molecular genetic techniques. The microbial composition in process fluids was influenced by aquifer depth, salinity, temperature, and available electron donors and acceptors. The organisms identified in the anoxic process fluids were closely related to chemoheterotrophs and chemoautotrophs that use nitrate, sulfate, ferric iron, and bicarbonate as the terminal electron acceptor. Microorganisms adversely affected operation of two geothermal plants. For example, Gallionella-related iron oxidizing bacteria, abundant in process fluids of the cold store at the Berliner Reichstag caused operation failures due to the formation of iron hydroxide scale that clogged the filter slots in the wells and led to a reduction of injectivity. In addition, biofilms formed by sulfur oxidizing Thiothrix sp. in filters of the topside facility drastically reduced injectivity. At the heat store in Neubrandenburg, sulfate reducing bacteria were probably involved in the formation of iron sulfides in filters of the topside facility and in the near wellbore area, and may have increased corrosion processes on the well pump at the cold side of the aquifer. Volatile fatty acids in process fluids and mineral scales in filters of the topside facility indicated the activity of microorganisms present in the different geothermal plants. In addition, it was shown that microorganisms react more sensitive than chemical analyses because of the high fluid flow in the plants, and thus indicate chemical changes in process fluids. Changes in the microbial community composition, and particularly the identification of indicator organisms, such as iron and sulfur oxidizer, fermentative, and sulfate reducing bacteria were suitable for the detection of increased availability of electron donors and acceptors. Thus, reasons for operation failures occurring at geothermal plants could be identified.

Thesis (MSc (Genetics))--University of Stellenbosch, 2007. / The aim of this study was to develop a DNA-based diagnostic system that can be used to distinguish between genotypes in the wheat breeding program at the University of Stellenbosch. Known marker systems were investigated and the chosen marker system would then be implemented to determine its utility in the breeding program. Three marker systems were considered, i.e. microsatellites, Amplified Fragment Length Polymorphisms (AFLPs) and various retrotransposon-based markers. Each system is based on polymerase chain reaction (PCR) amplification from specific primer pairs. The multitude of primer options was narrowed down during a review of published literature regarding wheat molecular markers. Thirty nine microsatellite primer pairs and nine AFLP primer combinations were chosen for the initial genotype evaluation. Four different retrotransposonbased techniques were investigated; namely Inter-Retrotransposon Amplified Polymorphism (IRAP), REtrotransposon-Microsatellite Amplified Polymorphism (REMAP), Sequence- Specific Amplified Polymorphism (SSAP) and, a derivative of these developed in this study, Wis-2 Retrotransposon Amplification. The study started with twenty genotypes which included varieties/breeding lines from five breeding programmes. The genotypes were chosen as representative of the respective breeding populations and were used in the initial testing of the marker systems. Eighteen microsatellites were evaluated using the panel of twenty genotypes. From this, six primer pairs (Xgwm190, Xgwm437, Xgwm539, Xwmc11, Xwmc59 and Xwmc177) were chosen to test the semi-automated DNA sequencer detection system. A single band/peak in each microsatellite profile was used for genotyping. Four of the primer pairs were labelled with different fluorochromes which enabled them to be multiplexed. The differences in amplification products of the six microsatellites meant that all six could be detected in one electrophoresis run. The banding pattern produced by microsatellite Xwmc177 was complex and highly polymorphic and was therefore also analysed in the same way as the AFLP patterns. When analyzed in this manner it proved to be more informative than the combination of six microsatellites (with a single prominent band scored in each). Three AFLP primer combinations could also be multiplexed and visualised together. The three EcoRI selective primers were labelled with different dyes and used with one MseI selective primer. The SSAP system also used fluorescently labelled primers and proved to be the most useful of the retrotransposon-based methods. However, this system produced such a large amount of data that it made analysis too time consuming. Therefore the six microsatellites and three AFLP primer combinations (MseI-CTC and EcoRI-ACA, -AAC, - AGG) were selected for routine genotyping. Due to the numerous highly polymorphic bands produced by the SSAP system it could be very useful to differentiate very closely related genotypes that cannot be distinguished with the markers proposed for routine use. A panel of 119 breeding lines were then used to implement the two chosen marker systems. The results obtained for these markers were used to produce a dendrogram of the lines using the SAS cluster analysis function. The clusters showed that most of the lines could be distinguished from each other. The MseI-CTC and EcoRI-AGG primer combination was the most informative. It produced the largest number of clusters (53) and could therefore discriminate between more of the lines than any other method. The dendrograms and clusters allowed sixteen of the breeding lines to be selected to test the optimal number of seeds to represent an entire population (variety/breeding line) as one seed was not sufficient. It was decided that eight seeds could provide a good representation of the intra-line variability.

Made available in DSpace on 2015-03-26T13:39:29Z (GMT). No. of bitstreams: 1 texto completo.pdf: 731854 bytes, checksum: 4c122a7309d2868902ca66fc7edfe89f (MD5) Previous issue date: 2008-02-25 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The use of the soybean oil for industrial and nutritional purposes is defined by the composition of the fatty acids present in the seeds, which directly affect the physical and chemical characteristics and the nutritional value of the oil produced. The reduction of the linolenic acid content is associated with the increase of the oxidative stability and the improvement of the oil taste. This work takes part in the soybean breeding program of the BIOAGRO/UFV and its objective was to achieve productive soybean lineages, with low content of linolenic acid, having as donator the American access A29. For such, the following stages were carried out: (1) non-destructive analysis of the linolenic content of seeds in two contrasting F2 populations for this characteristic; (2) selection of seeds with lower contents of linolenic acid of each crossing; (3) evaluation of the genetic variability, herdabilities, selection gains, predicted and realized, for the content of linolenic acid in both F2 populations studied; (4) performance of the fingerprinting of the F2 plants selected with microsatellite markers; (5) confirmation of the low content of linolenic acid present in the F3 seeds; (6) determination of the genetic divergence between recurrent parents and parents that are donators of alleles that condition the low content of linolenic acid; (7) selection, with the help of molecular markers, of hybrids derivative from genotypes which are genetically more similar to the lineages of the COODETEC, and which confirmed the linolenic acid low content condition in the F3 seeds. Both F2 populations presented high heritabilities for the linolenic acid content, suggesting that they are adequate for the achievement of gains for the low content of linolenic acid, and that the selection can be performed in precocious generations. Only the F2 population of the A29 x Tucunaré crossing presented heritability higher than 50%, when estimated by parent-child regression. Although the F2 population from the A29 x Tucunaré crossing presented higher predicted and realized gains, due to its high genetic variability, the 30 individuals selected presented linolenic acid contents below 2,5%. The different environmental conditions in which the F2 and F3 populations from the A29 x CS303TNKCA crossing were carried out provided a low realized gain. The study on genetic divergence showed that the parents are different from one another, and the genotype A29, donator of alleles for very low linolenic contents, was the most divergent. However, the lineages from the COODETEC were very similar due to the genetic background proximity of such lineages. The DNA fingerprinting allowed the identification of the most similar individuals as to the COODETEC lineages. It was possible to select, in both F2 populations studied, four individuals which are closer to the COODETEC lineages and that confirmed the low contents of linolenic acid in the F3 generation. / A utilização do óleo de soja para fins industriais e nutricionais é definida pela composição dos ácidos graxos presentes nas sementes, que afetam diretamente as características físicas e químicas e o valor nutricional do óleo produzido. A redução do teor de ácido linolênico está associada com aumento da estabilidade oxidativa e melhoria do sabor do óleo. Este trabalho integra parte do programa de melhoramento para a qualidade da soja do BIOAGRO/UFV e teve como objetivo a obtenção de linhagens de soja produtivas, com baixo teor de ácido linolênico tendo como doador o acesso norte-americano A29. Para isso, foram realizadas as etapas de: (1) análise não destrutiva do teor de ácido linolênico de sementes em duas populações F2 contrastantes para esta característica; (2) seleção das sementes com menor teor de ácido linolênico de cada cruzamento; (3) avaliação da variabilidade genética, herdabilidades, ganhos de seleção, predito e realizado, para teor de ácido linolênico nas duas populações F2 estudadas; (4) realização de fingerprinting das plantas F2 selecionadas com marcadores microssatélites; (5) confirmação do baixo teor de ácido linolênico nas sementes F3; (6) determinação da divergência genética entre progenitores recorrentes e progenitores doadores de alelos que condicionam o baixo teor de ácido linolênico; (7) seleção de híbridos derivados de genótipos geneticamente mais similares às linhagens da COODETEC com auxílio de marcadores moleculares e que confirmaram a condição de baixo teor de ácido linolênico nas sementes F3. As duas populações F2 apresentaram herdabilidades altas para teor de ácido linolênico sugerindo que são adequadas para a obtenção de ganhos para baixo teor de ácido linolênico, e que a seleção pode ser efetuada em gerações precoces. Somente a população F2 do cruzamento entre A29 x Tucunaré apresentou herdabilidade acima de 50%, quando estimada por meio da regressão pai/filho. Apesar da população F2 do cruzamento entre A29 x Tucunaré ter apresentado maiores ganhos predito e realizado, devido à alta variabilidade genética desta população, os 30 indivíduos selecionados tinham teores de ácido linolênico abaixo de 2,5%. As diferentes condições ambientais em que foram conduzidas as populações F2 e F3 do cruzamento entre A29 x CS303TNKCA promoveram baixo ganho realizado. O estudo da divergência genética evidenciou que os progenitores são divergentes entre si, sendo o genótipo A29, doador de alelos para baixíssimos teores de linolênico, o mais divergente, entretanto, as linhagens da COODETEC foram bastante similares entre si devido à proximidade do background genético dessas linhagens. O fingerprinting de DNA possibilitou a identificação dos indivíduos mais similares em relação às linhagens da COODETEC. Foi possível selecionar, nas duas populações F2 estudadas, quatro indivíduos mais próximos das linhagens da COODETEC e que confirmaram baixos teores de ácido linolênico na geração F3.

AFLP markers are widely used in breeding in some other crops, but their utilization in breeding of Brassica crops is not so frequent. AFLP markers are used for molecular characterization of particular varieties or genotypes and for evaluation of genetic diversity. The aim of this thesis was the application of this method in breeding of rapeseed and in comparative study of genetic variability of different oil seed rape cultivars of Czech, Czechoslovak and German origin. AFLP is based on selective amplification of genomic DNA. Technique consists of three basic steps: 1. restriction of genomic DNA on smaller fragments and ligation of adaptors; 2. selective amplification of fragments with specific primers and 3. electrophoresis of products and computer analysis (Vos et al., 1995). In this thesis 16 Czech (CZ) and Czechoslovak (CZS) and 16 German (G) cultivars of oilseed rape were compared. Two specific primers, EcoRI AGC and fluorescence labeled primer MseI ACC, were chosen for AFLP method. It was possible to distinguish group of CZ/CZS and G cultivars, which have origin in gene resources from Czech Republic and Germany. AFLP technique allows detection of very small differences in Brassica genome. The differences between studied cultivars exist, but they are not very distinct. They show on certain relationship and reduction of genetic basis of genetic resources, which are used in Central Europe.

Submitted by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-08-25T15:51:34Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação - Pablo Elleres.pdf: 5489693 bytes, checksum: b9a04e1146c232be81cf39a48ae1634d (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-08-25T15:52:08Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação - Pablo Elleres.pdf: 5489693 bytes, checksum: b9a04e1146c232be81cf39a48ae1634d (MD5) / Made available in DSpace on 2017-08-25T15:52:08Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação - Pablo Elleres.pdf: 5489693 bytes, checksum: b9a04e1146c232be81cf39a48ae1634d (MD5) Previous issue date: 2017-03-31 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Fingerprinting is a technique applied in order to identify or re-identify a User/ device via a set of attributes such as the size of the device’s screen, IP address identification, the versions of the software installed as well as through other existing features in the process Web communication. The technique is known in Nomenclature website fingerprinting and it has been used as a mechanism for marketing/product sales, however, its development aims to serve as a measure security of user authentication. The question is As it is considered a potencial threat to Web privacy, since personal and sensitive data can be captured and used for malicious purposes in various types of attacks and fraud. The point is that it may and should be considered a potential threat to the privacy of users on the Web, since personal and sensitive data can be captured and used for malicious purposes. Currently a technique that uses image rendering, called Canvas fingerprinting, has also been used for the same purposes as the previous one. This work presents a method that uses information retrieval techniques (via vectorial method) to perform the detection of Canvas Fingerprinting scripts in Web pages. The method consists in calculating the similarity between a base with 100 queries from a Canvas Fingerprinting database and a set of web pages labeled as benign and malignant. The result found showed high levels of similarities with a canvas base (97 %), a base of phishing pages (87 %) and a base with DMOZ directory pages (87 %). / Fingerprinting é a técnica aplicada com vistas a identificar ou reidentificar um usuário/dispositivo por intermédio de um conjunto de atributos como: o tamanho da tela do dispositivo, a identificação do endereço IP, as versões dos softwares instalados, assim como por meio de outras características existentes no processo de comunicação daWeb. A técnica é conhecida pela nomenclatura deWebsite fingerprinting e tem sido utilizada como mecanismo de marketing/vendas de produtos, mas pode muito bem ser empregada como medida de segurança na autenticação de usuários. A questão é que ela pode e deve ser considerada uma ameaça potencial a privacidade dos usuários na Web, já que dados pessoais e sigilosos podem ser capturados e empregados para fins maliciosos. Atualmente uma técnica que utiliza renderização de imagens, denominada Canvas fingerprinting, também tem sido utilizada para burlar a privacidade dos usuários de websites. Este trabalho apresenta um método que emprega técnicas de recuperação da informação (via método vetorial), para realizar a detecção de scripts Canvas Fingerpriting em páginas Web. O método consiste em realizar o cálculo da similaridade entre uma base com 100 consultas reconhecidamente ligadas à Canvas Fingerpriting e bases de dados com páginas tidas como benignas e malignas. O resultado encontrado mostrou que níveis altos de similaridades com uma base de Canvas (97%), uma base de páginas phishing (87%) e uma base com páginas do diretório DMOZ (87%).

Submitted by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2016-12-16T14:35:12Z No. of bitstreams: 1 Dissertação - Adriana R. Saraiva.pdf: 5916314 bytes, checksum: cf288d2a2930a048c67f43f933ab9524 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2016-12-16T14:35:35Z (GMT) No. of bitstreams: 1 Dissertação - Adriana R. Saraiva.pdf: 5916314 bytes, checksum: cf288d2a2930a048c67f43f933ab9524 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2016-12-22T15:21:06Z (GMT) No. of bitstreams: 1 Dissertação - Adriana R. Saraiva.pdf: 5916314 bytes, checksum: cf288d2a2930a048c67f43f933ab9524 (MD5) / Made available in DSpace on 2016-12-22T15:21:06Z (GMT). No. of bitstreams: 1 Dissertação - Adriana R. Saraiva.pdf: 5916314 bytes, checksum: cf288d2a2930a048c67f43f933ab9524 (MD5) Previous issue date: 2016-08-04 / FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas / Fingerprinting techniques are those used to identify (or re-identify) a user or device with a set of attributes (device screen size, versions of installed software, among many others) and other observable characteristics during the communication process. Commonly known by Website fingerprinting, such techniques can be used as a security measure (in user authentication, for example) and as a mechanism for sales / marketing. However, they can also be considered a potential threat to Web users’ privacy, since personal and sensitive data can be captured and used for malicious purposes in various types of attacks and fraud. In this context, this work proposes a methodology to detect fingerprinting artifacts in Web pages and measure the level of severity to user privacy. The results show that although simple, the method is effective to find fingerprinting codes in websites and categorizing them in severity levels. / Técnicas de fingerprinting são aquelas empregadas para identificar (ou reidentificar) um usuário ou um dispositivo através de um conjunto de atributos (tamanho da tela do dispositivo, versões de softwares instalados, entre muitos outros) e outras características observáveis durante o processo de comunicação. Comumente conhecidas por Website fingerprinting, tais técnicas podem ser usadas como medida de segurança (na autenticação de usuários, por exemplo) e como mecanismo para vendas / marketing. Por outro lado, também podem ser consideradas uma ameaça potencial à privacidade Web dos usuários, uma vez que dados pessoais e sigilosos podem ser capturados e empregados para fins maliciosos nos mais variados tipos de ataque e fraudes. Neste contexto, esta dissertação propõe uma metodologia para detectar artefatos (scripts) fingerprinting em páginas Web e mensurar o nível de severidade à privacidade do usuário. Os resultados mostram que embora simples, a metodologia é eficaz ao encontrar códigos fingerprinting nos websites e categorizá-los em níveis de severidade.

L'arrivée de l'Internet a révolutionné notre société à l'aube du 21e siècle. Nos habitudes se sont métamorphosées pour prendre en compte cette nouvelle manière de communiquer el de partager avec le monde. Grâce aux technologies qui en constituent ses fondations, le web est une plateforme universelle Que vous utilisiez un PC de bureau sous Windows, un PC portable sous MacOS, un serveur sous Linux ou une tablette sous Android, chacun a les moyens de se connecter à ce réseau de réseaux pour partager avec le monde. La technique dite de Browser fingerprinting est née de celle diversité logicielle et matérielle qui compose nos appareils du quotidien. En exécutant un script dans le navigateur web d'un utilisateur, un serveur peut récupér une très grande quantité d'informations. Il a été démontré qu'il est possible d'identifier de façon unique un appareil en récoltant suffisamment d'informations. L'impact d'une telle approche sur la vie privée des internautes est alors conséquente, car le browser fingerprinting est totalement indépendant des systèmes de traçage connu comme les cookies. Dans celle thèse, nous apportons les contributions suivantes : une analyse de 118 934 empreintes, deux contre-mesures appelées Blink et FPRandom et un protocole d'authentification basé sur le canvas fingerprinting. Le browser fingerprinting est un domaine fascinant qui en est encore à ses balbutiements. Avec cette thèse, nous contribuons à l'écriture des premières pages de son histoire en fournissant une vue d'ensemble du domaine, de ses fondations jusqu'à l'impact des nouvelles technologies du web sur cette technique. Nous nous tournons aussi vers le futur via l'exploration d'une nouvelle facette du domaine afin d'améliorer la sécurité des comptes sur Internet. / Users are presented with an ever-increasing number of choices to connect to the Internet. From desktops, laptops, tablets and smartphones, anyone can find the perfect device that suits his or her needs while factoring mobility, size or processing power. Browser fingerprinting became a reality thanks to the software and hardware diversity that compose every single one of our modem devices. By collecting device-specific information with a simple script running in the browser, a server can fully or partially identify a device on the web and follow it wherever it goes. This technique presents strong privacy implications as it does not require the use of stateful identifiers like cookies that can be removed or managed by the user. In this thesis, we provide the following contributions: an analysis of 118,934 genuine fingerprints to understand the current state of browser fingerprinting, two countermeasures called Blink and FPRandom and a complete protocol based on canvas fingerprinting to augment authentication on the web. Browser fingerprinting is still in its early days. As the web is in constant evolution and as browser vendors keep pushing the limits of what we can do online, the contours of this technique are continually changing. With this dissertation, we shine a light into its inner-workings and its challenges along with a new perspective on how it can reinforce account security.

Tor is a Privacy-Enhancing Technology based on onion routing which lets its users browse the web anonymously. Even though the traffic is encrypted in multiple layers, traffic analysis can still be used to gather information from meta-data such as time, size, and direction of the traffic. A Website Fingerprinting (WF) attack is characterized by monitoring traffic locally to the user in order to predict the destination website based on the observed patterns. TrafficSliver is a proposed defence against WF attacks which splits the traffic on multiple paths in the Tor network. This way, a local attacker is assumed to only be able to observe a subset of all the user's total traffic. The initial evaluation of TrafficSliver against Deep Fingerprinting (DF), the state-of-the-art WF attack, showed promising results for the defence, reducing the accuracy of DF from over 98% down to less than 7% without adding artificial delays or dummy traffic. In this thesis, we further evaluate TrafficSliver against DF beyond what was done in the original work by De la Cadena et al. by using a richer data representation and finding out whether it is possible to utilize simulated training data to improve the accuracy of the attack. By introducing directional time as a richer data representation and increasing the size of the training dataset using a simulator, the accuracy of DF was improved against TrafficSliver on three different datasets. Against the original dataset provided by the authors of TrafficSliver, the accuracy was initially 7.1% and then improved to 49.9%. The results were confirmed by using two additional datasets with TrafficSliver, where the accuracy was improved from 5.4% to 44.9% and from 9.8% to 37.7%. / Tor är ett personlig-integritetsverktyg baserat på onion routing som låter sina användare anonymnt besöka hemsidor på internet. Även om trafiken är enkrypterad i flera lager, kan trafikanalys användas för att utvinna information från metadata som exempelvis: tid, storlek och riktning av trafik. En Website Fingerprinting (WF)-attack karaktäriseras av att övervaka trafik nära användaren för att sedan avgöra vilken hemsida som besökts utifrån mönster. TrafficSliver är ett föreslaget försvar mot WF-attacker genom att dela upp trafiken på flera vägar genom nätverket. Detta gör att en attackerare antas endast kunna se en delmängd av användarens totala trafik. Den första utvärderingen av TrafficSliver mot Deep Fingerprinting (DF), spjutspetsen inom WF-attacker, visade lovande resultat för försvaret genom att reducera träffsäkerheten av DF från över 98% till mindre än 7% utan att lägga till artificiella fördröjningar eller falsk trafik. I denna uppsats strävar vi att fortsätta utvärderingen av TrafficSliver mot DF utöver vad som redan har gjorts av De la Cadena et al. med en rikare datarepresentation och en undersökning huruvida det går att använda simulerad data för att träna attacker mot försvaret. Genom att introducera riktad tid och öka mängden data för att träna attacken, ökades träffsäkerheten av DF mot TrafficSliver på tre distinkta dataset. Mot det dataset som samlades in av TrafficSliver var träffsäkerheten inledelsevis 7.1% och sedan förbättrad med hjälp av riktad tid och större mängder av simulerad träningsdata till 49.9%. Dessa resultat bekräftades även för två ytterligare dataset med TrafficSliver, där träffsäkerheten blev förbättrad från 5.4% till 44.9% och från 9.8% till 37.7%.