Contributions to security and privacy protection in recommendation systems

A recommender system is an automatic system that, given a customer model and a set of available documents, is able to select and offer those documents that are more interesting to the customer. From the point of view of security, there are two main issues that recommender systems must face: protection of the users' privacy and protection of other participants of the recommendation process. Recommenders issue personalized recommendations taking into account not only the profile of the documents, but also the private information that customers send to the recommender. Hence, the users' profiles include personal and highly sensitive information, such as their likes and dislikes. In order to have a really useful recommender system and improve its efficiency, we believe that users shouldn't be afraid of stating their preferences. The second challenge from the point of view of security involves the protection against a new kind of attack. Copyright holders have shifted their targets to attack the document providers and any other participant that aids in the process of distributing documents, even unknowingly. In addition, new legislation trends such as ACTA or the ¿Sinde-Wert law¿ in Spain show the interest of states all over the world to control and prosecute these intermediate nodes. we proposed the next contributions: 1.A social model that captures user's interests into the users' profiles, and a metric function that calculates the similarity between users, queries and documents. This model represents profiles as vectors of a social space. Document profiles are created by means of the inspection of the contents of the document. Then, user profiles are calculated as an aggregation of the profiles of the documents that the user owns. Finally, queries are a constrained view of a user profile. This way, all profiles are contained in the same social space, and the similarity metric can be used on any pair of them. 2.Two mechanisms to protect the personal information that the user profiles contain. The first mechanism takes advantage of the Johnson-Lindestrauss and Undecomposability of random matrices theorems to project profiles into social spaces of less dimensions. Even if the information about the user is reduced in the projected social space, under certain circumstances the distances between the original profiles are maintained. The second approach uses a zero-knowledge protocol to answer the question of whether or not two profiles are affine without leaking any information in case of that they are not. 3.A distributed system on a cloud that protects merchants, customers and indexers against legal attacks, by means of providing plausible deniability and oblivious routing to all the participants of the system. We use the term DocCloud to refer to this system. DocCloud organizes databases in a tree-shape structure over a cloud system and provide a Private Information Retrieval protocol to avoid that any participant or observer of the process can identify the recommender. This way, customers, intermediate nodes and even databases are not aware of the specific database that answered the query. 4.A social, P2P network where users link together according to their similarity, and provide recommendations to other users in their neighborhood. We defined an epidemic protocol were links are established based on the neighbors similarity, clustering and randomness. Additionally, we proposed some mechanisms such as the use SoftDHT to aid in the identification of affine users, and speed up the process of creation of clusters of similar users. 5.A document distribution system that provides the recommended documents at the end of the process. In our view of a recommender system, the recommendation is a complete process that ends when the customer receives the recommended document. We proposed SCFS, a distributed and secure filesystem where merchants, documents and users are protectedEste documento explora c omo localizar documentos interesantes para el usuario en grandes redes distribuidas mediante el uso de sistemas de recomendaci on. Se de fine un sistema de recomendaci on como un sistema autom atico que, dado un modelo de cliente y un conjunto de documentos disponibles, es capaz de seleccionar y ofrecer los documentos que son m as interesantes para el cliente. Las caracter sticas deseables de un sistema de recomendaci on son: (i) ser r apido, (ii) distribuido y (iii) seguro. Un sistema de recomendaci on r apido mejora la experiencia de compra del cliente, ya que una recomendaci on no es util si es que llega demasiado tarde. Un sistema de recomendaci on distribuido evita la creaci on de bases de datos centralizadas con informaci on sensible y mejora la disponibilidad de los documentos. Por ultimo, un sistema de recomendaci on seguro protege a todos los participantes del sistema: usuarios, proveedores de contenido, recomendadores y nodos intermedios. Desde el punto de vista de la seguridad, existen dos problemas principales a los que se deben enfrentar los sistemas de recomendaci on: (i) la protecci on de la intimidad de los usuarios y (ii) la protecci on de los dem as participantes del proceso de recomendaci on. Los recomendadores son capaces de emitir recomendaciones personalizadas teniendo en cuenta no s olo el per l de los documentos, sino tambi en a la informaci on privada que los clientes env an al recomendador. Por tanto, los per les de usuario incluyen informaci on personal y altamente sensible, como sus gustos y fobias. Con el n de desarrollar un sistema de recomendaci on util y mejorar su e cacia, creemos que los usuarios no deben tener miedo a la hora de expresar sus preferencias. Para ello, la informaci on personal que est a incluida en los per les de usuario debe ser protegida y la privacidad del usuario garantizada. El segundo desafi o desde el punto de vista de la seguridad implica un nuevo tipo de ataque. Dado que la prevenci on de la distribuci on ilegal de documentos con derechos de autor por medio de soluciones t ecnicas no ha sido efi caz, los titulares de derechos de autor cambiaron sus objetivos para atacar a los proveedores de documentos y cualquier otro participante que ayude en el proceso de distribuci on de documentos. Adem as, tratados y leyes como ACTA, la ley SOPA de EEUU o la ley "Sinde-Wert" en España ponen de manfi esto el inter es de los estados de todo el mundo para controlar y procesar a estos nodos intermedios. Los juicios recientes como MegaUpload, PirateBay o el caso contra el Sr. Pablo Soto en España muestran que estas amenazas son una realidad

Social Palimpsests - clouding the lens of the personal panopticon

The use of personal data has incredible potential to benefit both society and individuals, through increased understanding of behaviour, communication and support for emerging forms of socialisation and connectedness. However, there are risks associated with disclosing personal information, and present systems show a systematic asymmetry between the subjects of the data and those who control and manage the way that data is propagated and used. This leads to a tension between a desire to engage with online society and enjoy its benefits on one hand, and a distrust of those with whom the data is shared on the other. In this chapter, we explore a set of obfuscation techniques which may help to redress the balance of power when sharing personal data, and return agency and choice to users of online services

The Play in the System

What does artistic resistance look like in the twenty-first century, when disruption and dissent have been co-opted and commodified in ways that reinforce dominant systems? In The Play in the System Anna Watkins Fisher locates the possibility for resistance in artists who embrace parasitism—tactics of complicity that effect subversion from within hegemonic structures. Fisher tracks the ways in which artists on the margins—from hacker collectives like Ubermorgen to feminist writers and performers like Chris Kraus—have willfully abandoned the radical scripts of opposition and refusal long identified with anticapitalism and feminism. Space for resistance is found instead in the mutually, if unevenly, exploitative relations between dominant hosts giving only as much as required to appear generous and parasitical actors taking only as much as they can get away with. The irreverent and often troubling works that result raise necessary and difficult questions about the conditions for resistance and critique under neoliberalism today

Automating the Discovery of Censorship Evasion Strategies

Censoring nation-states deploy complex network infrastructure to regulate what content citizens can access, and such restrictions to open sharing of information threaten the freedoms of billions of users worldwide, especially marginalized groups. Researchers and censoring regimes have long engaged in a cat-and-mouse game, leading to increasingly sophisticated Internet-scale censorship techniques and methods to evade them. In this dissertation, I study the technology that underpins this Internet censorship: middleboxes (e.g. firewalls). I argue the following thesis: It is possible to automatically discover packet sequence modifications that render deployed censorship middleboxes ineffective across multiple application-layer protocols. To evaluate this thesis, I develop Geneva, a novel genetic algorithm that discovers packet-manipulation-based censorship evasion strategies automatically against nation-state level censors. Training directly against a live adversary, Geneva com- poses, mutates, and evolves sophisticated strategies out of four basic packet manipulation primitives (drop, tamper, duplicate, and fragment). I show that Geneva can be effective across different application layer protocols (HTTP, HTTPS+SNI, HTTPS+ESNI, DNS, SMTP, FTP), censoring regimes (China, Iran, India, and Kazakhstan), and deployment contexts (client-side, server- side), even in cases where multiple middleboxes work in parallel to perform censorship. In total, I present 112 client-side strategies (85 of which work by modifying application layer data), and the first ever server-side strategies (11 in total). Finally, I use Geneva to discover two novel attacks that show censoring middleboxes can be weaponized to launch attacks against innocent hosts anywhere on the Internet. Collectively, my work shows that censorship evasion can be automated and that censorship infrastructures pose a greater threat to Internet availability than previously understood

The politics of cyberconflict: ethnoreligious conflicts in computer mediated environments

This thesis argues that it is important to distinguish between two different phenomena in cyberpolitical spaces: First of all, between ethnic or religious groups fighting over in cyberspace, as they do in real life (Ethnoreligious cyberconflict) and second, between a social movement and its antagonistic institution (Sociopolitical cyberconflict). These different kinds of cyberconflict can be explained in the context of international conflict analysis for ethnoreligious cyberconflict and social movement theory for sociopolitical cyberconflict, while keeping in mind that this takes place in a media environment by using media theory. By combining elements of these approaches and justifying the link to cyberconflict, it is possible to use them as a theoretical light to look at the environment of Cyberconflict (CC) and analysis of incidents of CC. Consequently, this work looks at the leading groups using the internet either as weapon or a resource against governments, while also looking at networks, international organisations and new social movements. Searching for a satisfactory theoretical framework, I propose the following parameters to be looked at while analysing cyberconflicts: 1. Environment of Conflict and Conflict Mapping (real and virtual). The world system generates an arborescent apparatus, which is haunted by lines of flight, emerging through underground networks connected horizontally and lacking a hierarchic centre (Deleuze and Guattari). The structure of the internet is ideal for network groups, (a global network with no central authority) has offered another experience of governance (no governance), time and space (compression), ideology (freedom of information and access to it), identity (multiplicity) and fundamentally an opposition to surveillance and control, boundaries and apparatuses. 2. Sociopolitical Cyberconflicts: The impact of ICTs on: a. Mobilising structures (network style of movements using the internet, participation, recruitment, tactics, goals), b. Framing Processes (issues, strategy, identity, the effect of the internet on these processes), c. Political opportunity structure (the internet as a component of this structure), d. hacktivism. 3. Ethnoreligious Cyberconflicts: a. Ethnic/religious affiliation, chauvinism, national identity, b. Discourses of inclusion and exclusion, c. Information warfare, the use of the internet as a weapon, propaganda and mobilisational resource d. Conflict resolution depends on legal, organisational framework, number of parties issues, distribution of power, values and beliefs. 4. The internet as a medium: a. Analysing discourses (representations of the world, constructions of social identities and social relations), b. Control of information, level of censorship, alternative sources, c. Wolsfeld: Political contest model among antagonists: the ability to initiate and control events, dominate political discourse, mobilise supporters, d. Media effects on policy (strategic, tactical, and representational)

Electronic Evidence: 4th Edition

This well-established practitioner text provides an exhaustive treatment of electronic evidence. The revised outline for the fourth edition will continue to follow the tradition in English evidence text books by basing the text on the law of England and Wales, with appropriate citations of relevant case law and legislation from other jurisdictions

Electronic Evidence and Electronic Signatures

In this updated edition of the well-established practitioner text, Stephen Mason and Daniel Seng have brought together a team of experts in the field to provide an exhaustive treatment of electronic evidence and electronic signatures. This fifth edition continues to follow the tradition in English evidence text books by basing the text on the law of England and Wales, with appropriate citations of relevant case law and legislation from other jurisdictions. Stephen Mason (of the Middle Temple, Barrister) is a leading authority on electronic evidence and electronic signatures, having advised global corporations and governments on these topics. He is also the editor of International Electronic Evidence (British Institute of International and Comparative Law 2008), and he founded the innovative international open access journal Digital Evidence and Electronic Signatures Law Review in 2004. Daniel Seng (Associate Professor, National University of Singapore) is the Director of the Centre for Technology, Robotics, AI and the Law (TRAIL). He teaches and researches information technology law and evidence law. Daniel was previously a partner and head of the technology practice at Messrs Rajah & Tann. He is also an active consultant to the World Intellectual Property Organization, where he has researched, delivered papers and published monographs on copyright exceptions for academic institutions, music copyright in the Asia Pacific and the liability of Internet intermediaries

Electronic Evidence and Electronic Signatures

In this updated edition of the well-established practitioner text, Stephen Mason and Daniel Seng have brought together a team of experts in the field to provide an exhaustive treatment of electronic evidence and electronic signatures. This fifth edition continues to follow the tradition in English evidence text books by basing the text on the law of England and Wales, with appropriate citations of relevant case law and legislation from other jurisdictions. Stephen Mason (of the Middle Temple, Barrister) is a leading authority on electronic evidence and electronic signatures, having advised global corporations and governments on these topics. He is also the editor of International Electronic Evidence, and he founded the innovative international open access journal Digital Evidence and Electronic Signatures Law Review in 2004. Daniel Seng (Associate Professor, National University of Singapore) is the Director of the Centre for Technology, Robotics, AI and the Law (TRAIL). He teaches and researches information technology law and evidence law. Daniel was previously a partner and head of the technology practice at Messrs Rajah & Tann. He is also an active consultant to the World Intellectual Property Organization, where he has researched, delivered papers and published monographs on copyright exceptions for academic institutions, music copyright in the Asia Pacific and the liability of Internet intermediaries