Contextual Spaces with Functional Skins as OpenSocial Extension

Portability, flexibility and extensibility are essential features of social media platforms. When such Web platforms are able to take user's context into account, they provide better user experience and enhance the effectiveness of users' actions. In this paper, we discuss an extension to OpenSocial standard, namely contextual space, that shapes the framework, in which people carry out online activities. The proposed contextual space extension defines how a set of OpenSocial widgets are aggregated as a Web environment for a given purpose and with a given functional skin as a user interface. Additionally it allows to create contextualized widgets. In this paper we discuss the proposed extension in details and provide the examples of its use based on real life scenarios. Finally, we detail an implementation scheme

Towards a Privacy-enhanced Social Networking Site

L’avénement des réseaux sociaux, tel que Facebook, MySpace et LinkedIn, a fourni une plateforme permettant aux individus de rester facilement connectés avec leurs amis, leurs familles ou encore leurs collègues tout en les encourageant activement à partager leurs données personnelles à travers le réseau. Avec la richesse des activités disponibles sur un réseau social, la quantité et la variété des informations personnelles partagées sont considérables. De plus, de part leur nature numérique, ces informations peuvent être facilement copiées, modifiées ou divulguées sans le consentement explicite de leur propriétaire. Ainsi, l’information personnelle révélée par les réseaux sociaux peut affecter de manière concrète la vie de leurs utilisateurs avec des risques pour leur vie privée allant d’un simple embarras à la ruine complète de leur réputation, en passant par l’usurpation d’identité. Malheureusement, la plupart des utilisateurs ne sont pas conscients de ces risques et les outils mis en place par les réseaux sociaux actuels ne sont pas suffisants pour protéger efficacement la vie privée de leurs utilisateurs. En outre, même si un utilisateur peut contrôler l’accès à son propre profil, il ne peut pas contrôler ce que les autres révèlent à son sujet. En effet, les “amis” d’un utilisateur sur un réseau social peuvent parfois révéler plus d’information à son propos que celui-ci ne le souhaiterait. Le respect de la vie privée est un droit fondamental pour chaque individu. Nous pré- sentons dans cette thèse une approche qui vise à accroître la prise de conscience des utilisateurs des risques par rapport à leur vie privée et à maintenir la souveraineté sur leurs données lorsqu’ils utilisent un réseau social. La première contribution de cette thèse réside dans la classification des risques multiples ainsi que les atteintes à la vie privée des utilisateurs d’un réseau social. Nous introduisons ensuite un cadre formel pour le respect de la vie privée dans les réseaux sociaux ainsi que le concept de politique de vie privée (UPP). Celle-ci définie par l’utilisateur offre une manière simple et flexible de spécifier et communiquer leur attentes en terme de respect de la vie privée à d’autres utilisateurs, tiers parties ainsi qu’au fournisseur du réseau social. Par ailleurs, nous dé- finissons une taxonomie (possiblement non-exhaustive) des critères qu’un réseau social peut intégrer dans sa conception pour améliorer le respect de la vie privée. En introduisant le concept de réseau social respectueux de la vie privée (PSNS), nous proposons Privacy Watch, un réseau social respectueux de la vie privée qui combine les concepts de provenance et d’imputabilité afin d’aider les utilisateurs à maintenir la souveraineté sur leurs données personnelles. Finalement, nous décrivons et comparons les différentes propositions de réseaux sociaux respectueux de la vie privée qui ont émergé récemment. Nous classifions aussi ces différentes approches au regard des critères de respect de la vie privée introduits dans cette thèse.The rise of Social Networking Sites (SNS), such as Facebook, Myspace, and LinkedIn has provided a platform for individuals to easily stay in touch with friends, family and colleagues and actively encourage their users to share personal information. With the wealth of activities available on SNS, the amount and variety of personal information shared is considerable and diverse. Additionally, due to its digital nature, this information can be easily copied, modified and disclosed without the explicit consent of their owner. Personal information disclosed from SNS could affect users’ life, with privacy risks ranging from simple embarrassment to ruining their reputation, or even identity theft. Unfortunately, many users are not fully aware of the danger of divulging their personal information and the current privacy solutions are not flexible and thorough enough to protect user data. Furthermore, even though users of SNS can control access to their own profile, they cannot control what others may reveal about them. Friends can sometimes be untrustworthy and disclose more information about the user than they should. Considering that privacy is a fundamental right for every individual, in this thesis, we present an approach that increases privacy awareness of the users and maintains the sovereignty of their data when using SNS. The first contribution of this thesis is the classification of multiple types of risks as well as user expectations regarding privacy in SNS. Afterwards, we introduce the Privacy Framework for SNS and the concept of User Privacy Policy (UPP) to offer users an easy and flexible way to specify and communicate their privacy concerns to other users, third parties and SNS provider. Additionally, we define a taxonomy (possibly non-exhaustive) of privacy criteria that can enhance the user privacy if they are integrated within the design of a SNS and introduce the concept of a Privacy-enhanced SNS (PSNS). Furthermore, we present also Privacy Watch, a theoretical proposal of a PSNS platform that combines the concept of provenance and accountability to help SNS users maintain sovereignty over their personal data. Finally, we survey and compare several privacy-enhanced SNS that were recently proposed that try to integrate some privacy features directly into the design of the system. We also classify these different approaches with respect to the privacy criteria developed

Presentation of self on a decentralised web

Self presentation is evolving; with digital technologies, with the Web and personal publishing, and then with mainstream adoption of online social media. Where are we going next? One possibility is towards a world where we log and own vast amounts of data about ourselves. We choose to share - or not - the data as part of our identity, and in interactions with others; it contributes to our day-to-day personhood or sense of self. I imagine a world where the individual is empowered by their digital traces (not imprisoned), but this is a complex world. This thesis examines the many factors at play when we present ourselves through Web technologies. I optimistically look to a future where control over our digital identities are not in the hands of centralised actors, but our own, and both survey and contribute to the ongoing technical work which strives to make this a reality. Decentralisation changes things in unexpected ways. In the context of the bigger picture of our online selves, building on what we already know about self-presentation from decades of Social Science research, I examine what might change as we move towards decentralisation; how people could be affected, and what the possibilities are for a positive change. Finally I explore one possible way of self-presentation on a decentralised social Web through lightweight controls which allow an audience to set their expectations in order for the subject to meet them appropriately. I seek to acknowledge the multifaceted, complicated, messy, socially-shaped nature of the self in a way that makes sense to software developers. Technology may always fall short when dealing with humanness, but the framework outlined in this thesis can provide a foundation for more easily considering all of the factors surrounding individual self-presentation in order to build future systems which empower participants

New statistical disclosure attacks on anonymous communications networks

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Informática, Departamento de Ingeniería del Software e Inteligencia Artificial, leída el 5-02-2016.El anonimato es una dimensi on de la privacidad en la que una persona se reserva su identidad en las relaciones sociales que mantiene. Desde el punto de vista del area de las comunicaciones electr onicas, el anonimato posibilita mantener oculta la informaci on que pueda conducir a la identi caci on de las partes involucradas en una transacci on. Actualmente, conservar el anonimato en las transacciones de informaci on en red representa uno de los aspectos m as importantes. Con este n se han desarrollado diversas tecnolog as, com unmente denominadas tecnolog as para la mejora de la privacidad. Una de las formas m as populares y sencillas de proteger el anonimato en las comunicaciones entre usuarios son los sistemas de comunicaci on an onima de baja latencia basados en redes de mezcladores. Estos sistemas est an expuestos a una serie de ataques basados en an alisis de tr a co que comprometen la privacidad de las relaciones entre los usuarios participantes en la comunicaci on, esto es, que determinan, en mayor o menor medida, las identidades de emisores y receptores. Entre los diferentes tipos de ataques destacan los basados en la inundaci on de la red con informaci on falsa para obtener patrones en la red de mezcladores, los basados en el control del tiempo, los basados en el contenido de los mensajes, y los conocidos como ataques de intersecci on, que pretenden inferir, a trav es de razonamientos probabil sticos o de optimizaci on, patrones de relaciones entre usuarios a partir de la informaci on recabada en lotes o durante un per odo de tiempo por parte del atacante. Este ultimo tipo de ataque es el objeto de la presente tesis...Anonymity is a privacy dimension related to people's interest in preserving their identity in social relationships. In network communications, anonymity makes it possible to hide information that could compromise the identity of parties involved in transactions. Nowadays, anonymity preservation in network information transactions represents a crucial research eld. In order to address this issue, a number of Privacy Enhancing Technologies have been developed. Low latency communications systems based on networks of mixes are very popular and simple measures to protect anonymity in users communications. These systems are exposed to a series of attacks based on tra c analysis that compromise the privacy of relationships between user participating in communications, leading to determine the identity of sender and receiver in a particular information transaction. Some of the leading attacks types are attacks based on sending dummy tra c to the network, attacks based on time control, attacks that take into account the textual information within the messages, and intersections attacks, that pretend to derive patterns of communications between users using probabilistic reasoning or optimization algorithms. This last type of attack is the subject of the present work. Intersection attacks lead to derive statistical estimations of the communications patterns (mean number of sent messages between a pair of users, probability of relationship between users, etc). These models were named Statistical Disclosure Attacks, and were soon considered able to compromise seriously the anonymity of networks based on mixes. Nevertheless, the hypotheses assumed in the rst publications for the concrete development of the attacks were excessively demanding and unreal. It was common to suppose that messages were sent with uniform probability to the receivers, to assume the knowledge of the number of friends an user has or the knowledge a priori of some network parameters, supposing similar behavior between users, etc...Depto. de Ingeniería de Software e Inteligencia Artificial (ISIA)Fac. de InformáticaTRUEunpu

A user-managed access control model and mechanisms for web based social networks: enhancing expressive power, co-ownership management, interoperability and authorized data exposures

Web Based Social Networks (WBSNs) are well-known applications which are used by thousands of people worldwide. However, privacy issues, and access control in particular, cannot be disregarded. WBSNs consist of users who upload data to be shared with other users and the management of who is able to access to the uploaded data is a subject to study. In this respect, this thesis focuses on four aspects. First, WBSN users have to specify their privacy preferences in a fine-grained way. Second, WBSN data is not usually related to a single user, who uploads it and who is considered the owner, but to multiple users who are referred to as co-owners. Then, access control has to be managed preserving the privacy of both, owners and co-owners, such that all their privacy preferences are satisfied without restrictions. Thirdly, the great quantity of WBSNs forces users upon being enrolled in many of them, though being access control management a cumbersome task. Lastly, users upload data to WBSNs and providers store it and may use it for unnoticed or unauthorized purposes. The widespread development of WBSNs has contributed to the enhancement of these applications. The demanding necessity of providing users with tools to control accesses to their data, has boosted the development of proposals in this regard. Nonetheless, a general lack of fine-grained management is detected. The goal of this thesis is to facilitate fine-grained access control management along the whole usage process within and among different WBSNs in a privacy preserving way. Firstly, an expressive usage control model, together with its administrative model, is proposed to achieve the definition of fine-grained access control preferences. Based on previous models, a mechanism to manage co-ownership corresponds to the second contribution of this thesis. Data is decomposed in parts and each of them is assigned to the owner or to a co-owner who establishes access control preferences. Then, these preferences are jointly evaluated and the privacy of all users is completely preserved. Having the right tools to manage access control in a fine-grained way, the third and last contribution of this thesis is a pair of protocols, one being based on an extension of the other, to attain interoperability, reusability and unauthorized data exposures among different WBSNs. Also taking the proposed usage control model as the underlying base to manage access control, these protocols reduce the burden of managing access control in different applications and thus, they help to increase users' control over their data. As a result, this thesis aims to be a challenging step towards the enhancement of access control management procedures in the social networking field.Las Redes Sociales (RSs) son aplicaciones conocidas y utilizadas a lo largo y ancho del mundo. Sin embargo, los problemas de privacidad, y de control de acceso en particular, no pueden menospreciarse. Las RSs se basan en usuarios que comparten datos entre sí, siendo la gestión de quién puede acceder a dichos datos un tema al que hay que prestar especial interés. En base a esto, la presente Tesis estudia cuatro cuestiones. Primero, los usuarios de las RSs tienen que especificar sus preferencias con alta granularidad. Segundo, los datos de las RSs no se asocian a un único usuario, considerado el propietario y quien sube los datos a las RSs, sino que pueden estar asociados a múltiples usuarios, los cuales reciben el nombre de copropietarios. Por ello, el control de acceso tiene que preservar la privacidad de todos los usuarios, tanto de los propietarios como de los copropietarios, consiguiendo satisfacer las preferencias de control de acceso de todos ellos. Tercero, la gran cantidad de RSs existentes obliga a los usuarios a crear cuentas en cada una de ellas en las que quieran participar, siendo la gestión del control de acceso una tarea tediosa. En último lugar, los usuarios suben sus datos a las RSs y los proveedores de servicio los almacenan, pudiéndolos utilizar para su propio beneficio. La necesidad de proporcionar a los usuarios las herramientas adecuadas para que puedan controlar sus datos ha acelerado el desarrollo de propuestas para la mejora de las RSs. Sin embargo, se detecta una falta de granularidad en la gestión del control de acceso. El objetivo de esta Tesis es facilitar la gestión del control de acceso con alta granularidad entre distintas RSs a lo largo de todo el proceso de uso y preservando la privacidad. En primer lugar se propone un modelo de uso expresivo, junto con el modelo administrativo complementario, para conseguir la definición de preferencias de control de acceso con alta granularidad. Basado en los modelos anteriores, la segunda de las contribuciones se corresponde con el desarrollo de un mecanismo para la gestión de la copropiedad. Los datos son descompuestos en partes y cada parte asignada al propietario o a un copropietario para que éste establezca las preferencias de privacidad deseadas. Posteriormente, en cada solicitud de acceso a un dato se evalúan todas las preferencias, preservándose así la privacidad de todos los usuarios. Disponiendo de las herramientas adecuadas para gestionar el control de acceso con alta granularidad, la tercera y última de las contribuciones de esta tesis consiste en el desarrollo de un par de protocolos, uno extendiendo el otro. Estos protocolos facilitan la interoperabilidad, la reusabilidad y la minimización del acceso a los datos de forma no autorizada entre distintas RSs. Igualmente, aplicando el modelo de uso propuesto para la gestión del control de acceso, estos protocolos reducen las tareas a realizar para gestionar el acceso en distintas aplicaciones y por tanto, ayudan a incrementar el control que los usuarios tienen sobre sus datos. En resumen, esta tesis pretende dar un paso en la mejora del control de acceso en las RSs.Programa en Ciencia y Tecnología InformáticaPresidente: Juan Manuel Estévez Tapiador; Vocal: Flavio Lombardi; Secretario: María Isabel González Vasc

Contributions to affective learning through the use of data analysis, visualizations and recommender sytems

Student modeling is an important issue in telematics learning environments, e.g. learning resources can be adapted based on the students' information. An emergent area of student modeling is the inclusion of affective information. The improvement of emotion detectors based on the students' events in different telematics learning environments is an open issue. Moreover, there is a need of proposing and evaluating new visualizations involving affective information, and proposing generic solutions for the recommendation of learning materials based on the affective information. This PhD proposes two different models for the detection of emotions in two different telematics learning environments. The first model uses a Hidden Markov Model to infer the emotions in a programming learning environment in which students should use different tools to learn how to program. The second model uses a set of rules to infer the emotions in a Massive Open Online Course platform in which students should solve exercises and watch videos. An evaluation of the first model for the detection of emotions was performed using a controlled experiment, comparing the results of the model with the students' answers regarding their emotions in different instants of times. The results showed that the model was not able to detect accurately the students' answers regarding their emotions. Other models of the literature applied in other learning environments were tested and they were not able to predict accurately the students' answers regarding their emotions. Therefore, the detection of emotions based on students' events in these types of environments might not be feasible, or the reference data of students' answers to a survey with different questions about emotions should be redefined. Moreover, this PhD proposes a set of affective-related visualizations for learning environments. Some of these visualizations only involve affective information, while others combine this affective information with other related to the students' activities with the learning platforms. Some of these visualizations were evaluated with real students and results showed a good usability, usefulness and effectiveness. Finally, this work proposes a generic framework for enabling the recommendation of learning resources based on affective information. The solution includes an Application Programming Interface for the definition of the different possible events. A specific implementation of this recommender has been developed as a plugin of the ROLE SDK platform.Programa Oficial de Doctorado en Ingeniería TelemáticaPresidente: Carlos Enrique Palau Salvador.- Secretario: Eva María Méndez Rodríguez, Eva Maria.- Vocal: Ruth Cobos Pére

A Network of One’s Own: Struggles to Domesticate the Internet

This thesis is a design research practice-led inquiry into the domesticated Internet. It first seeks to complicate simplistic corporate and academic visions by naming some of the struggles it encounters – not least to assert a private home and network of one's own. It is argued that a century of domestic technologies has emphasised invisibility, ubiquity, and automation in ways that obscure a network of exploited people and finite resources. Furthermore, these technological ambitions are met through machine surveillance, in ways newly enabled by the domesticated Internet, that threaten the privacy of the home. In response, this thesis seeks some practical ways to design alternatives that assert a network of one's own and makes the work it implicates visible. The methodological approach is broadly Research Through Design supplemented by a practice described as designerly hacking through which hidden technical potential is revealed and given meaning. Two empirical studies are described that together make an account of the technical possibility and social reality of the networked home: an autobiographical technical exploration of the author's home and network with the making of hacks and Research Products privately and in public; and a cultural probe engagement with six rented households surfacing contemporary accounts of the domesticated Internet and in particular the challenges and opportunities of wireless networking. Together this yields a series of technical and social insights for design and two forms are offered to communicate these: a framework for understanding change in the networked home (The Stuff of Home) and a set of 30 design patterns for a network of one's own; each invites different analyses. The conclusion then draws together the multiple threads developed through this thesis and offers some reflection on the complexity of doing contemporary technical design work

On Personal Storage Systems: Architecture and Design Considerations

Actualment, els usuaris necessiten grans quantitats d’espai d’emmagatzematge remot per guardar la seva informació personal. En aquesta dissertació, estudiarem dues arquitectures emergents de sistemes d’emmagatzematge d’informació personal: els Núvols Personals (centralitzats) i els sistemes d’emmagatzematge social (descentralitzats). A la Part I d'aquesta tesi, contribuïm desvelant l’operació interna d’un Núvol Personal d’escala global, anomenat UbuntuOne (U1), incloent-hi la seva arquitectura, el seu servei de metadades i les interaccions d’emmagatzematge de dades. A més, proporcionem una anàlisi de la part de servidor d’U1 on estudiem la càrrega del sistema, el comportament dels usuaris i el rendiment del seu servei de metadades. També suggerim tota una sèrie de millores potencials al sistema que poden beneficiar sistemes similars. D'altra banda, en aquesta tesi també contribuïm mesurant i analitzant la qualitat de servei (p.e., velocitat, variabilitat) de les transferències sobre les REST APIs oferides pels Núvols Personals. A més, durant aquest estudi, ens hem adonat que aquestes interfícies poden ser objecte d’abús quan són utilitzades sobre els comptes gratuïts que normalment ofereixen aquests serveis. Això ha motivat l’estudi d’aquesta vulnerabilitat, així com de potencials contramesures. A la Part II d'aquesta dissertació, la nostra primera contribució és analitzar la qualitat de servei que els sistemes d’emmagatzematge social poden proporcionar en termes de disponibilitat de dades, velocitat de transferència i balanceig de la càrrega. El nostre interès principal és entendre com fenòmens intrínsecs, com les dinàmiques de connexió dels usuaris o l’estructura de la xarxa social, limiten el rendiment d’aquests sistemes. També proposem nous mecanismes de manegament de dades per millorar aquestes limitacions. Finalment, dissenyem una arquitectura híbrida que combina recursos del Núvol i dels usuaris. Aquesta arquitectura té com a objectiu millorar la qualitat de servei del sistema i deixa als usuaris decidir la quantitat de recursos utilitzats del Núvol, o en altres paraules, és una decisió entre control de les seves dades i rendiment.Los usuarios cada vez necesitan espacios mayores de almacenamiento en línea para guardar su información personal. Este reto motiva a los investigadores a diseñar y evaluar nuevas infraestructuras de almacenamiento de datos personales. En esta tesis, nos centramos en dos arquitecturas emergentes de almacenamiento de datos personales: las Nubes Personales (centralización) y los sistemas de almacenamiento social (descentralización). Creemos que, pese a su creciente popularidad, estos sistemas requieren de un mayor estudio científico. En la Parte I de esta disertación, examinamos aspectos referentes a la operación interna y el rendimiento de varias Nubes Personales. Concretamente, nuestra primera contribución es desvelar la operación interna e infraestructura de una Nube Personal de gran escala (UbuntuOne, U1). Además, proporcionamos un estudio de la actividad interna de U1 que incluye la carga diaria soportada, el comportamiento de los usuarios y el rendimiento de su sistema de metadatos. También sugerimos mejoras sobre U1 que pueden ser de utilidad en sistemas similares. Por otra parte, en esta tesis medimos y caracterizamos el rendimiento del servicio de REST APIs ofrecido por varias Nubes Personales (velocidad de transferencia, variabilidad, etc.). También demostramos que la combinación de REST APIs sobre cuentas gratuitas de usuario puede dar lugar a abusos por parte de usuarios malintencionados. Esto nos motiva a proponer mecanismos para limitar el impacto de esta vulnerabilidad. En la Parte II de esta tesis, estudiamos la calidad de servicio que pueden ofrecer los sistemas de almacenamiento social en términos de disponibilidad de datos, balanceo de carga y tiempos de transferencia. Nuestro interés principal es entender la manera en que fenómenos intrínsecos, como las dinámicas de conexión de los usuarios o la estructura de su red social, limitan el rendimiento de estos sistemas. También proponemos nuevos mecanismos de gestión de datos para mejorar esas limitaciones. Finalmente, diseñamos y evaluamos una arquitectura híbrida para mejorar la calidad de servicio de los sistemas de almacenamiento social que combina recursos de usuarios y de la Nube. Esta arquitectura permite al usuario decidir su equilibrio entre control de sus datos y rendimiento.Increasingly, end-users demand larger amounts of online storage space to store their personal information. This challenge motivates researchers to devise novel personal storage infrastructures. In this thesis, we focus on two popular personal storage architectures: Personal Clouds (centralized) and social storage systems (decentralized). In our view, despite their growing popularity among users and researchers, there still remain some critical aspects to address regarding these systems. In the Part I of this dissertation, we examine various aspects of the internal operation and performance of various Personal Clouds. Concretely, we first contribute by unveiling the internal structure of a global-scale Personal Cloud, namely UbuntuOne (U1). Moreover, we provide a back-end analysis of U1 that includes the study of the storage workload, the user behavior and the performance of the U1 metadata store. We also suggest improvements to U1 (storage optimizations, user behavior detection and security) that can also benefit similar systems. From an external viewpoint, we actively measure various Personal Clouds through their REST APIs for characterizing their QoS, such as transfer speed, variability and failure rate. We also demonstrate that combining open APIs and free accounts may lead to abuse by malicious parties, which motivates us to propose countermeasures to limit the impact of abusive applications in this scenario. In the Part II of this thesis, we study the storage QoS of social storage systems in terms of data availability, load balancing and transfer times. Our main interest is to understand the way intrinsic phenomena, such as the dynamics of users and the structure of their social relationships, limit the storage QoS of these systems, as well as to research novel mechanisms to ameliorate these limitations. Finally, we design and evaluate a hybrid architecture to enhance the QoS achieved by a social storage system that combines user resources and cloud storage to let users infer the right balance between user control and QoS