Identities are present in the interactions between individuals and organizations. Online shopping requires credit card information, while e-government services require social security or passport numbers. The involvement of identities, however, makes them susceptible to theft and misuse. The most prominent approach for maintaining the privacy of individuals is the enforcement of privacy policies that regulate the flow and use of identity information. This approach suffers two drawbacks that severely limit its effectiveness. First, recent research in data-mining facilitates the fusion of partial identities into complete identities. That holds true even if the attributes examined are not, normally considered, to be identifying. Second, policies are prone to human error, allowing for identity information to be released accidentally. This thesis presents a system that enables an individual to interact with organizations, without allowing these organizations to link the interactions of that individual together. The system does not release individuals' identities to organizations. Instead, certified artificial identities are used to guarantee that individuals possess the required attributes to successfully participate in the interactions. The system limits the fusion of partial identities and minimizes the effects of human error. The concept of using certified artificial identities has been extensively researched. The system, however, tackles several unaddressed scenarios. The system works not only for interactions that involve an individual and an organization, but also for interactions that involve a set of individuals connected by structured relations. The individuals should prove the existence of relations among them to organizations, yet organizations cannot profile the actions of these individuals. Further, the system allows organizations to be anonymous, while proving their attributes to individuals. Reputation-based trust is incorporated to help individuals make informed decisions whether to deal with a particular organization. The system is used to design applications in e-commerce, access control, reputation management, and cloud computing. The thesis describes the applications in detail. / Thesis (Ph.D, Computing) -- Queen's University, 2010-04-07 11:17:37.68

Video surveillance is an important tool used in security and environmental monitoring, however, the widespread deployment of surveillance cameras has raised serious privacy concerns. Many privacy-enhancing schemes have been recently proposed to automatically redact images of selected individuals in the surveillance video for protection. To identify these individuals for protection, the most reliable approach is to use biometric signals as they are immutable and highly discriminative. If misused, these characteristics of biometrics can seriously defeat the goal of privacy protection. In this dissertation, an Anonymous Biometric Access Control (ABAC) procedure is proposed based on biometric signals for privacy-aware video surveillance. The ABAC procedure uses Secure Multi-party Computational (SMC) based protocols to verify membership of an incoming individual without knowing his/her true identity. To make SMC-based protocols scalable to large biometric databases, I introduce the k-Anonymous Quantization (kAQ) framework to provide an effective and secure tradeoff of privacy and complexity. kAQ limits systems knowledge of the incoming individual to k maximally dissimilar candidates in the database, where k is a design parameter that controls the amount of complexity-privacy tradeoff. The relationship between biometric similarity and privacy is experimentally validated using a twin iris database. The effectiveness of the entire system is demonstrated based on a public iris biometric database. To provide the protected subjects with full access to their privacy information in video surveillance system, I develop a novel privacy information management system that allows subjects to access their information via the same biometric signals used for ABAC. The system is composed of two encrypted-domain protocols: the privacy information encryption protocol encrypts the original video records using the iris pattern acquired during ABAC procedure; the privacy information retrieval protocol allows the video records to be anonymously retrieved through a GC-based iris pattern matching process. Experimental results on a public iris biometric database demonstrate the validity of my framework.

Made available in DSpace on 2016-06-02T20:25:03Z (GMT). No. of bitstreams: 1 2417.pdf: 520101 bytes, checksum: b440f1c6ce31e0f267eb0297cb55e5c7 (MD5) Previous issue date: 2009-02-19 / Financiadora de Estudos e Projetos / This study is developed under the theoretical-methodological perspective of Semântica do Acontecimento, and its objective is to understand the function of argumentation and designation in the language, more specifically, analyze how juridical argumentation works. Our object of analysis was a lawsuit characterized as Indemnity Action3, through which the petitioners request the closure of a website where they were offended anonymously and the consequent indemnity payment. Firstly, we established two cenas enunciativas from the corpus characterized by the court cena and the website cena, composed of smaller cenas. Through this analysis, we could observe how argumentative orientation happens when mobilizing the speakers and the memoráveis present, as well as establish how the anonymity in this cena enunciativa works. For that, we established a relation between silence and rumor, studied by Orlandi4 (mmeo) and the anonymity present in court. It was possible, therefore, to conclude from the characterization of the cena the nonexistence of this anonymity. Secondly, we used the concept of Domínio Semantico de Determinação to observe how the designation of Court, space that moves the action, takes place. We observed a relation of antonymy in its designation, which characterizes it either as a space for offenses or as a space for indictment, and that, through the designations and the memoráveis, orient the argumentation to the advantage of the website closure, as well as indemnity payment to the petitioners. / Este trabalho desenvolve-se sob a perspectiva teórico-metodológica da Semântica do Acontecimento e tem por objetivo compreender o funcionamento da argumentação e da designação na linguagem, mais especificamente, analisar como funciona a argumentação jurídica. Utilizamos como corpus um processo jurídico caracterizado como Ação Indenizatória1, por meio do qual os requerentes solicitam a interdição de um site em que foram ofendidos anonimamente no chamado Fórum , e o conseqüente pagamento de indenização. Em um primeiro momento da análise, estabelecemos duas cenas enunciativas a partir do corpus analisado, caracterizadas pela cena do tribunal e pela cena do site. Através desta análise foi possível observar como se dá a orientação argumentativa ao mobilizarmos os locutores e os memoráveis presentes, assim como, estabelecer como funciona o anonimato nessa cena enunciativa. Para isso, fizemos uma relação entre o silêncio e o boato, estudado por Orlandi2 (mmeo), e o anonimato presente no Fórum , de forma que foi possível concluir a partir da caracterização da cena a não presença desse caráter anônimo. Em um segundo momento, lançamos mão do conceito de Domínio Semântico de Determinação para observar como se dá a designação de Fórum , espaço que movimenta a ação. Observamos uma relação de antonímia presente na designação do mesmo, que o caracteriza ora como um espaço para ofensas ora como um espaço para denúncias, e que por meio das designações e dos memoráveis na relação com a cena enunciativa, orientam a argumentação em favor da interdição do site, assim como o pagamento da indenização aos requerentes.

This master thesis studies teenage users that are common to the semi-anonymous question and answer platform Sayat.me. Sayat.me offers users with a profile the possibility to receive questions and feedback from friends and peers. What is so special about the platform is that the commenters’ identity remains undisclosed, which means that all messages are by default anonymous. Previous research has demonstrated the frequent occurrence of cyberbullying or online abuse on these platforms. Adults are puzzled as to why semi-anonymous question and answer platforms are so popular amongst teenagers. Departing from a theoretical framework with key concepts from digital and social media theories, the analysis tries to create a better understanding of this phenomenon from Belgian teenagers’ point of view. The results of the interviews show that, first of all, Sayat.me is not considered as an independent social media site, but rather as an extension of it. On social media, ‘sociality’ and ‘connection’ is what matters, but on Sayat.me sociality mainly plays an indirect role where users receive compliments from and are comforted by friends. Compliments, approval and admiration is what teenagers keeps coming back to the platform. Although teenagers often encounter online abuse, they do not feel cyberbullied, even so they consider this abuse as ‘natural’ on the platform. In addition, it appears that the way you are handling Sayat.me says a lot about you as a person, which is why teens use Sayat.me to present themselves or to portray a certain image. However, teenagers only imagine their friends or peers as the audience and do not consider their Sayat.me for their parents’ eyes. The situation is that parents are confused and do not understand their children’s online behaviour, whilst teenagers are annoyed with their parents’ incomprehension and overprotectiveness.

Submitted by Morgana Silva (morgana_linhares@yahoo.com.br) on 2016-06-16T19:25:34Z No. of bitstreams: 1 arquivototal.pdf: 1917941 bytes, checksum: df05a39cc9a050dba0687a2e607e64e9 (MD5) / Approved for entry into archive by Viviane Lima da Cunha (viviane@biblioteca.ufpb.br) on 2016-06-17T16:03:45Z (GMT) No. of bitstreams: 1 arquivototal.pdf: 1917941 bytes, checksum: df05a39cc9a050dba0687a2e607e64e9 (MD5) / Approved for entry into archive by Viviane Lima da Cunha (viviane@biblioteca.ufpb.br) on 2016-06-17T16:05:26Z (GMT) No. of bitstreams: 1 arquivototal.pdf: 1917941 bytes, checksum: df05a39cc9a050dba0687a2e607e64e9 (MD5) / Made available in DSpace on 2016-06-17T16:06:42Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1917941 bytes, checksum: df05a39cc9a050dba0687a2e607e64e9 (MD5) Previous issue date: 2016-02-29 / E-participation, as complement to traditional political participation, represents a promise of revival of the civil society in the information age. Despite the reduced financial costs, e-participation is still in the early stages, if we consider the division that exists among those who participate and those who are outside of the online political debate. E-participation comes up against social risks derived from the expression of personal opinion, an example being ideological persecution. Anonymous communication on the Internet has been identified as dubious, because on the one hand it facilitates personal expression, but on the other it interferes with the debate, mainly because people lose their inhibitions. Therefore, an analysis of the relationship among risk attitudes, anonymity perception and intention of e-participation in virtual social networks was conducted. An experimental study was conducted by manipulating the perception of anonymity of professionals of a high-risk occupation in the public sector and measuring their risk attitudes and intentions of e-participation through Facebook. The results indicate that there is a strong association (R2 = 0,80; Β = 9,54; p-value < 0.01) between risk attitudes and intention of e-participation, and that this relationship is even stronger when the e-participation occurs in presence of greater perceived anonymity. Thus, it was observed that anonymity perception interacts with risk attitudes in an effect that moderates the relationship between the latter and intention of e-participation. / A e-participação, como complemento da participação política tradicional, representa uma promessa de reavivamento da sociedade civil na era da informação. Apesar dos reduzidos custos financeiros, a e-participação ainda está em fase inicial se considerarmos a divisão que existe entre os que participam e os que ficam à margem do debate político online. A e-participação esbarra em alguns fatores de risco social, derivados da exposição de opinião pessoal, tendo como exemplo a perseguição ideológica. A comunicação anônima na internet tem sido apontada como uma via dúbia, pois por um lado facilita a expressão pessoal, mas por outro dificulta o debate, principalmente porque as pessoas perdem suas inibições. Assim, buscou-se analisar a relação entre atitudes em relação a riscos, percepção de anonimato e intenção de e-participação nas redes sociais virtuais. Realizou-se um estudo experimental, manipulando-se a percepção de anonimato de profissionais de uma ocupação de alto risco do setor público e medindo-se suas atitudes em relação a riscos e intenções de e-participação através do Facebook. Os resultados mostraram uma forte associação (R2 = 0,80; Β = 9,54; p-valor < 0.01) entre atitudes em relação a riscos e intenção de e-participação e que essa relação fica ainda mais forte quando a e-participação ocorre na presença de uma maior percepção de anonimato. Com isso, observou-se que a percepção de anonimato interage com a atitude em relação a riscos num efeito que modera a relação desta com a intenção de e-participação.

Este artículo presenta una reflexión sobre la ética de la investigación etnográfica en los espacios sociales digitales conocidos como mundos virtuales o cibermundos. Partiendo de la propia experiencia del autor en los cibermundos Second Life, There, Onverse y Twinity, se exploran y analizan cuestiones relacionadas con la transparencia y presencia del etnógrafo en los cibermundos, las expectativas de privacidad o la cuestión del anonimato. si bien los cibermundos recogen problemas éticos presentes en la etnografía tradicional y virtual, también presentan nuevas dificultades y dilemas éticos que deben ser identificados y analizados desde un punto de vista crítico. / The following paper presents a reflection on the ethics of ethnographic research in so-called virtual worlds or cyberworlds. based on my own experience in Second Life, there, Onverse and Twinity, issues related to transparency, presence, privacy and anonymity are discussed. Although research in cyberworlds shares some ethical problems with traditional and virtual ethnography, they present newdifficulties and ethical dilemmas during fieldwork that should be identified and analyzed from a critical point of view.

AvanÃos em tÃcnicas de computaÃÃo mÃvel aliados à difusÃo de serviÃos baseados em localizaÃÃo tÃm gerado uma grande quantidade de dados de trajetÃria. Tais dados podem ser utilizados para diversas finalidades, tais como anÃlise de fluxo de trÃfego, planejamento de infraestrutura, entendimento do comportamento humano, etc. No entanto, a publicaÃÃo destes dados pode levar a sÃrios riscos de violaÃÃo de privacidade. Semi-identificadores sÃo pontos de trajetÃria que podem ser combinados com informaÃÃes externas e utilizados para identificar indivÃduos associados à sua trajetÃria. Por esse motivo, analisando semi-identificadores, um usuÃrio malicioso pode ser capaz de restaurar trajetÃrias anonimizadas de indivÃduos por meio de aplicaÃÃes de redes sociais baseadas em localizaÃÃo, por exemplo. Muitas das abordagens jà existentes envolvendo anonimizaÃÃo de dados foram propostas para ambientes de computaÃÃo centralizados, assim elas geralmente apresentam um baixo desempenho para anonimizar grandes conjuntos de dados de trajetÃria. Neste trabalho propomos uma estratÃgia distribuÃda e eficiente que adota o modelo de privacidade km-anonimato e utiliza o escalÃvel paradigma MapReduce, o qual permite encontrar semi-identificadores em um grande volume de dados. NÃs tambÃm apresentamos uma tÃcnica que minimiza a perda de informaÃÃo selecionando localizaÃÃes chaves a serem removidas a partir do conjunto de semi-identificadores. Resultados de avaliaÃÃo experimental demonstram que nossa soluÃÃo de anonimizaÃÃo à mais escalÃvel e eficiente que trabalhos jà existentes na literatura. / Advancements in mobile computing techniques along with the pervasiveness of location-based services have generated a great amount of trajectory data. These data can be used for various data analysis purposes such as traffic flow analysis, infrastructure planning, understanding of human behavior, etc. However, publishing this amount of trajectory data may lead to serious risks of privacy breach. Quasi-identifiers are trajectory points that can be linked to external information and be used to identify individuals associated with trajectories. Therefore, by analyzing quasi-identifiers, a malicious user may be able to trace anonymous trajectories back to individuals with the aid of location-aware social networking applications, for example. Most existing trajectory data anonymization approaches were proposed for centralized computing environments, so they usually present poor performance to anonymize large trajectory data sets. In this work we propose a distributed and efficient strategy that adopts the $k^m$-anonymity privacy model and uses the scalable MapReduce paradigm, which allows finding quasi-identifiers in larger amount of data. We also present a technique to minimize the loss of information by selecting key locations from the quasi-identifiers to be suppressed. Experimental evaluation results demonstrate that our proposed approach for trajectory data anonymization is more scalable and efficient than existing works in the literature.

Bitcoin has emerged as the leading cryptographic currency since its inception in 2009 and at the time of writing holds a market capitalization of $28.4 billion. This ever-increasing figure has attracted adopters seeking to advance their investments, often leaving purely technical aspects on the sidelines. As is the case with any innovative technology, misconceptions are plentiful and information is not always conclusive. The research effort presented in this paper consists of a quantitative study seeking to address the subject of user anonymity in the Bitcoin network by employing an online survey on one of the most prominent Bitcoin forums. This includes 50 eligible participants, whose motivation is derived through the application of temporal motivation theory. The survey seeks to form an understanding of user attitudes towards the aspect of anonymity by following a methodological approach for exploring common tendencies among the representatives and will serve as the underlying data set from which conclusions can be drawn. Furthermore, this paper will present a literary study of the actual state of anonymity in this peer-to-peer technology by reviewing current findings highlighted in the area, thus presenting a comprehensive view of anonymity in the Bitcoin network, which will contrast the user study.

A person who is communication about (the data subject) has to keep track of all of his revealed data in order to protect his right of informational self-determination. This is important when data is going to be processed in an automatic manner and, in particular, in case of automatic inquiries. A data subject should, therefore, be enabled to recognize useful decisions with respect to data disclosure, only by using data which is available to him. For the scope of this thesis, we assume that a data subject is able to protect his communication contents and the corresponding communication context against a third party by using end-to-end encryption and Mix cascades. The objective is to develop a model for analyzing the linkability of communication contents by using Formal Concept Analysis. In contrast to previous work, only the knowledge of a data subject is used for this analysis instead of a global view on the entire communication contents and context. As a first step, the relation between disclosed data is explored. It is shown how data can be grouped by types and data implications can be represented. As a second step, behavior, i. e. actions and reactions, of the data subject and his communication partners is included in this analysis in order to find critical data sets which can be used to identify the data subject. Typical examples are used to verify this analysis, followed by a conclusion about pros and cons of this method for anonymity and linkability measurement. Results can be used, later on, in order to develop a similarity measure for human-computer interfaces.

Many security services today only provides one security configuration at run-time, and cannot then utilize the trade-off between performance and security. In order to make use of this trade-off, tunable security services providing several security configurations that can be selected at run-time are needed. To be able to make intelligent choices on which security configuration to use for different situations we need to know how good they are, i.e., we need to order the different security configurations with respect to each security attribute using measures for both security and performance. However, a key issue with computer security is that it is due to its complex nature hard to measure. As the title of this thesis indicates, it discusses both security measures and tunable security services. Thus, it can be seen to consist of two parts. In the first part, discussing security measures for tunable security services, an investigation on the security implications of selective encryption by using guesswork as a security measure is made. Built on this an investigation of the relationship between guesswork and entropy. The result shows that guesswork, after a minor redefinition, is equal to the sum of the entropy and the relative entropy. The second part contributes to the area of tunable security services, e.g., services that provides several security configurations at run-time. In particular, we present the mobile Crowds (mCrowds) system, an anonymity technology for the mobile Internet developed at Karlstad University, and a tunable encryption service, that is based on a selective encryption paradigm and designed as a middleware. Finally, an investigation of the tunable features provided by Mix-Nets and Crowds are done, using a conceptual model for tunable security services.