Decentralized Online Social Networks (DOSNs) are evolving as a promising approach to mitigate design-inherent privacy flaws of logically centralized services such as Facebook, Google+ or Twitter. Common approaches to implement a DOSN build upon a peer-to-peer (P2P) architecture in order to avoid the central aggregation of sensitive user data at one provider-controlled location. While the absence of a single point of data aggregation strikes the most powerful attacker from the list of adversaries, the decentralization also removes some privacy protection afforded by the provider's intermediation of all communication in a centralized Online Social Network (OSN). As content storage, access right management, retrieval and other administrative tasks of the service become the obligation of the users, it is non-trivial to hide the metadata of objects and information flows, even when the content itself is encrypted. Such metadata is, deliberately or as a side effect, hidden by the provider in a centralized system. Implementing the different features of a privacy-presvering DOSN does not only face these general challenges but must also cope with the absence of a trusted agent with full access to all data. For example user authentication should provide the same usabilty known from common centralized OSN services, such as ease of changing a password, revoking the access of a stolen device or resetting a forgotten password via e-mail or security questions. All this without relying on a trusted third party such as an identity provider. Another example is user search, where the challenge is to protect user data while making user findable at the same time. An implementation of such a feature in a DOSN has to work without assuming a trusted provider having access to all user profiles maintaining a global search index. In this work we analyze the general privacy-problems in a DOSN, especially those arising from metadata. Furthermore, we suggest two privacy-preserving implementations of standard OSN features, i.e., user authentication via password-login and user search via a knowledge threshold. Both implementations do not rely on a trusted, central provider and are therefore applicable in a DOSN cenario but can be applied in other P2P or low-trust environments as well. / I dagens populära sociala nätverkstjänster, såsom Facebook, Google+ och Twitter, finns en risk för integritetskränkningar. Risken är en oundviklig konsekvens av den logiskt centraliserade struktur som dessa tjänster bygger på.  Decentraliserade sociala nätverkstjänster (eng. Decentralized Online Social Networks, DOSNs) är en lovande utveckling för att minska risken och skydda användarnas personliga information från tjänsteleverantören och dem som leverantören samarbetar med. Ett vanligt sätt att implementera ett DOSN är genom en icke-hierarkisk nätverksarkitektur (eng. peer-to-peer network) för att undvika att känsliga personuppgifter ansamlas på ett ställe under tjäns televerantörens kontroll.   Att inte längre ha en tjänsteleverantör som har tillgång till alla data tar bort den största risken för integritetskränkningar. Men genom att ersätta den centrala tjänsteleverantören med ett decentraliserat system tar vi även bort visst integritetsskydd. Integritetsskyddet var en konsekvens av att förmedlingen av all användarkommunikation skedde genom tjänsteleverantörens mellanservrar. När ansvaret för lagring av innehållet, hantering av behörigheterna, åtkomst och andra administrativa uppgifter övergår till användarna själva, då blir det en utmaning att skydda metadata för objekten och informationsflöden, även om innehållet är krypterat. I ett centraliserat system är dessa metadata faktiskt skyddade av tjänsteleverantören - avsiktligt eller som en sidoeffekt.   För att implementera de olika funktioner som ska finnas i ett integritetsskyddande DOSN, är det nödvändigt att både lösa dessa generella utmaningar och att hantera frånvaron av ett betrodd tredjepart som har full tillgång till all data. Autentiseringen av användarna, till exempel, borde ha samma användbarhet som finns i centraliserade system. Det vill säga att det är lätt att ändra lösenordet, dra tillbaka rättigheterna för en stulen klientenhet, eller återställa ett glömt lösenord med hjälp av e-post eller säkerhetsfrågor - allt utan att förlita sig på en betrodd tredjepart. Ett annat exempel är funktionen att kunna söka efter andra användare. Utmaningen där är att skydda informationen om användarna samtidigt som det måste vara möjligt att hitta användare baserad på samma information. En implementation av denna funktion i ett DOSN måste klara sig utan en betrodd tjänsteleverantör som med tillgång till alla användares data kan upprätthålla ett globalt sökindex. I den här avhandlingen analyserar vi de generella risker för integritetskränkningar i DOSN, särskilt de som orsakas av metadata. Dessutom föreslår vi två integritetskyddande implementationer av vanliga funktioner i en socialt nätverkstjänst: lösenordbaserad användarautentisering och en användarsökfunktionen med en kunskaptröskel. Båda implementationerna är lämpliga för DOSN-scenarier eftersom de klarar sig helt utan en betrodd, central tjänstleverantör, och kan därför också användas i andra sammanhang: såsom icke-hierarkiska nätverk eller andra system som måste klara sig utan en betrodd tredjepart. / <p>QC 20150428</p>

Social networking services on the Internet are growing and increasing numbers of people are using these new ways to communicate and share information. Many users are communicating with both friends from outside the service as well as with people they have only been in contact with through a social networking service. At the same time mobile phones are becoming more powerful and increasingly offer high speed Internet connectivity. Because of this people expect these social networking services to be available on their mobile device, as well as on their personal computer. Given the capabilities of today’s mobile devices, it is possible to extend the existing phonebook with capabilities to support a variety of social networking services in addition to the existing communication options. By integrating the contacts gained from the social networking service into the mobile phonebook the user can reach these contacts easily. Communication in online social networks via a mobile phone is expected to grow in popularity in the near future [1]. Several operators are simplifying access to these networks for their customers by offering different ways to connect to social networks [2][3]. However, access to these networks is often done via web sites or dedicated applications. These solutions are not optimal since browsing the web using a mobile browser can be bothersome and dedicated applications require installation of the application as well as any subsequent updates. Widgets on the other hand solve these problems in a convenient way. They can enable access to a device’s full functionality, just like dedicated applications, and provide a platform for easy development using web technologies. Furthermore, widgets are highly flexible for example, updates do not require reinstallation, and when new social networks become popular new widgets that connect to them can easily be developed and distributed. The goal of this thesis is to expand the mobile phonebook with functionality to enable communication on online social networks. To reach this goal I have created a new widget platform, where hybrid widgets run partly in a Java ME application and partly in the mobile web browser. This solution has the potential to significantly enhance the ways we communicate and interact with people. The users are therefore likely to have a larger number of people whom they interact with – rather than a smaller number; hence increasing the overall communication between people. This thesis project was performed at Ericsson Research in Kista. Any opinions stated in the thesis are strictly my own. Similarly any technology selections made are my own and do not necessarily reflect any official position(s) of Ericsson. / Sociala nätverkstjänster på Internet växer och ett ökande antal personer använder dessa nya sätt att kommunicera och dela information. Många användare kommunicerar med både tidigare vänner och med personer de endast har haft kontakt med genom en social nätverkstjänst. Samtidigt som de sociala nätverkstjänsterna har växt har mobiltelefoner fått betydligt bättre prestanda och erbjuder i allt högre grad höghastighetsanslutningar till Internet. På grund av detta förväntar sig människor att dessa sociala nätverkstjänster ska vara tillgängliga från deras mobiltelefon, precis som från deras dator. Givet dagens mobiltelefoners förmåga är det möjligt att utvidga den befintliga telefonboken med funktionalitet för att stödja en mängd olika sociala nätverkstjänster utöver de kommunikationsalternativ som redan finns. Genom att integrera kontakterna från de sociala nätverkstjänsterna i mobilens telefonbok kan användaren enkelt nå dessa kontakter. Kommunikationen på Internetbaserade sociala nätverkstjänster från mobiltelefonen förväntas växa i popularitet den närmaste tiden [1]. Flertalet operatörer håller för närvarande på att förenkla åtkomsten till dessa nätverk för deras kunder genom att erbjuda olika sätt att ansluta till social nätverk [2][3]. Åtkomst till dessa nätverks sker ofta genom hemsidor eller dedikerade applikationer. Dessa lösningar är dock inte optimala eftersom att använda mobiltelefonen för att surfa på webben kan vara ansträngande och dedikerade applikationer kräver installering av applikationen samt efterföljande uppdateringar. Widgets kan lösa dessa problem på ett smidigt sätt. De möjliggör åtkomst till enhetens fulla funktionalitet, som en dedikerad applikation, men tillhandahåller en plattform för enkel utveckling med hjälp av webb teknologier. Fortsättningsvis så är widgets mycket flexibla, uppdateringar kräver inte ominstallallation och när nya sociala nätverk blir populära kan nya widgets som ansluter till dem enkelt utvecklas. Målet med denna uppsats är att utvidga mobiltelefonens adressbok med funktionalitet som möjliggör kommunikation på Internetbaserade sociala nätverkstjänster. För att förverkliga detta har jag skapat en ny widget platform där hybrida widgets körs delvis i en Java ME applikation och delvis i den mobila web läsaren. Denna lösning har potentialen att betydligt förhöja sätten som vi kommunicerar och interagerar med människor. Användarna kommer därför antagligen att ha ett större antal människor som de interagerar med – snarare än ett litet antal. Följaktligen kommer det att öka den totala kommunikationen mellan människor. Detta examensarbete utfördes på Ericsson Research i Kista. Alla åsikter som uttrycks i uppsatsen är mina egna. Likaså är alla val av teknologier som gjorts mina egna och reflekterar inte nödvändigtvis Ericssons officiella position(er).

It is clear that the internet is being used more often for social interactions but the reasons why people adopt these newer technologies are still unclear. Over the last thirty years numerous adoption theories have been proposed however few account for the newer types of technology, such as social website usage. Purpose – The study will compare and contrast two different models of adoption to see if one model is better than the other in understanding the usage of social networking websites such as Facebook. At an organisational level the idea of extended usage of technology has been encapsulated in the construct of infusion of technology into a work place. The study will also show that infusion of technology may occur at an individual level of research. The argument is made that since national culture has been shown to affect usage, national culture may moderate the level of infusion that is found. Methodology – The study will use a quantitative methodology to survey potential (or actual) users of Facebook using a structured questionnaire. Since two adoption models are being tested, two questionnaires were developed and tested. The items for the questionnaires have been adapted from prior literature. Reliability and validity tests confirmed the scales from prior literature. The sample was selected from higher education institutions within the Johannesburg region .Specifically, students from the University of the Witwatersrand and the University of Johannesburg were invited to complete the questionnaires. The two questionnaires were mixed randomly between the students. Findings – It was found that the traditional technology acceptance model could better explain the usage of social networking websites when compared to the more modern WebQual framework. The study found that there is a strong positive relationship between usage and infusion. In line with the prior research on national culture moderating usage, the study found that national culture does moderate the relationship between usage and infusion. Implications – The study has a number of implications. Firstly, the research compared two models of technology usage. The study showed that the technology acceptance model was better at explaining the usage of social networking websites. Future research should focus on improving the TAM model and may result in better understanding the usage of social websites. Secondly, a set of scales are provided for future research which allow for the measurement of infusion at an individual level. These scales were tested for reliability and validity in two separate data collections and in both collections the scales met or exceeded the statistical requirements. Thirdly, the relationship between usage and infusion is seen to be moderated by national culture. This has 5 large implications for organisations and people who use Web2.0 as a medium for business. As an example, marketers could use the results in better understanding the usage of these types of websites, in the hope that it would allow for better targeting and placement of adverts. Lastly, the implications may extend beyond the context of the research. The study found a relationship between usage and infusion at an individual level of analysis. The relationship may exist in other areas of research which relate to Information systems including but not limited to Marketing (increasing the life cycle of products and increasing the value of customers through brand loyalty) and human resources (increasing employee efficiency through understanding peoples infusion of different types of technology). Research limitations – The research is limited to the sample that was achieved. The findings can be directly inferred to a similar sample base within South Africa, however cannot be generalised to samples of dissimilar natures. While the study used Facebook as a case, it should be cautioned that the results should not be generalised to other forms of social networking websites such as Twitter. Originality – The study is original in the following ways: Firstly, the study was conducted in South Africa where few other studies been found with a similar nature. Secondly, the study extended the thoughts on usage to the idea of infusion. Thirdly, two models were directly compared with independent data collections occurring. Fourthly, the relationship between usage and infusion is seen to be moderated by national culture. Both the relationship as well as the moderation effects has previously been empirically shown.

Indiana University-Purdue University Indianapolis (IUPUI) / Following the trend of online data sharing and publishing, researchers raise their concerns about the privacy problem. Online Social Networks (OSNs), for example, often contain sensitive information about individuals. Therefore, anonymizing network data before releasing it becomes an important issue. This dissertation studies the privacy preservation problem from the perspectives of both attackers and defenders. To defenders, preserving the private information while keeping the utility of the published OSN is essential in data anonymization. At one extreme, the final data equals the original one, which contains all the useful information but has no privacy protection. At the other extreme, the final data is random, which has the best privacy protection but is useless to the third parties. Hence, the defenders aim to explore multiple potential methods to strike a desirable tradeoff between privacy and utility in the published data. This dissertation draws on the very fundamental problem, the definition of utility and privacy. It draws on the design of the privacy criterion, the graph abstraction model, the utility method, and the anonymization method to further address the balance between utility and privacy. To attackers, extracting meaningful information from the collected data is essential in data de-anonymization. De-anonymization mechanisms utilize the similarities between attackers’ prior knowledge and published data to catch the targets. This dissertation focuses on the problems that the published data is periodic, anonymized, and does not cover the target persons. There are two thrusts in studying the de-anonymization attacks: the design of seed mapping method and the innovation of generating-based attack method. To conclude, this dissertation studies the online data privacy problem from both defenders’ and attackers’ point of view and introduces privacy and utility enhancement mechanisms in different novel angles.

No description available.

In this work, we propose a PRivAcy-Diversity-Aware Team Formation framework, namely PRADA-TF, that can be deployed based on the trust relationships between users in online social networks (OSNs). Our proposed PRADA-TF is mainly designed to reflect team members' domain expertise and privacy preserving preferences when a task requires a wide range of diverse domain expertise for its successful completion. The proposed PRADA-TF aims to form a team for maximizing its productivity based on members' characteristics in their diversity, privacy preserving, and information sharing. We leveraged a game theory called Mechanism Design in order for a mechanism designer as a team leader to select team members that can maximize the team's social welfare, which is the sum of all team members' utilities considering team productivity, members' privacy preserving, and potential privacy loss caused by information sharing. To screen a set of candidate teams in the OSN, we built an expert social network based on real co-authorship datasets (i.e., Netscience) with 1,590 scientists, used the semi-synthetic datasets to construct a trust network based on a belief model called Subjective Logic, and identified trustworthy users as candidate team members. Via our extensive simulation experiments, we compared the seven different TF schemes, including our proposed and existing TF algorithms, and analyzed the key factors that can significantly impact the expected and actual social welfare, expected and actual potential privacy leakout, and team diversity of a selected team. / Master of Science / In this work, we propose a PRivAcy-Diversity-Aware Team Formation framework, namely PRADA-TF, that can be deployed based on the trust relationships between users in online social networks (OSNs). Our proposed PRADA-TF is mainly designed to reflect team members' domain expertise and privacy preserving preferences when a task requires a wide range of diverse domain expertise for its successful completion. The proposed PRADA-TF aims to form a team based on members' characteristics in their diversity, privacy preserving, and information sharing so as to maximize the performance of the team. We leveraged a game theory called Mechanism Design in order for a mechanism designer as a team leader to select team members that can maximize the team's social welfare, which is the sum of all team members' utilities considering team productivity, members' privacy preserving, and potential privacy loss caused by information sharing. To screen a set of candidate teams in the OSN, we built an expert social network based on real co-authorship datasets with 1,590 scientists, used the semi-synthetic datasets to construct a trust network representing the trust relationship between the users in OSNs, and identified trustworthy users as candidate team members. Via our extensive simulation experiments, we compared the seven different team formation (TF) schemes, including our proposed and existing TF algorithms, and analyzed the key factors that can significantly impact the expected and actual social welfare, expected and actual potential privacy leakout, and team diversity of a selected team.

System deployment projects are extremely complex and with more and more organisations now choosing to configure and deploy off-the-shelf systems, the project teams are presented with new challenges. The aim of this study was to gain an understanding of the issues faced during such configuration and deployment projects and see if support could be provided. A year long observational study of one of these projects was carried. While it was initially assumed that it would be technical issues related to the system’s configuration that would be the primary problems, the study revealed communication issues to be at the heart of a large number of the issues. Online social networks such as Facebook are extremely popular, allowing users to stay in touch with large numbers of distributed people. Private social network sites were applied to projects to see if they could replicate the benefits the sites provide and support project communications. A social network site was created for both a distributed research project and an administrative systems project and their use observed. Statistical data on the use of the sites and qualitative feedback from users is presented to assess the viability of the approach. The experiments showed social network sites to have many benefits when used as a complementary mechanism to traditional channels for project communications. It is clear however, that social network sites cannot solve all the problems projects may encounter. If the use of a site is to be a success it is vital it gains a critical mass of users. The approach taken to the site’s configuration and introduction will be hugely influential in its success. In order to choose the right approach a clear understanding of what the project’s communication needs are and the possible uses of the site is needed. A process of configuration and development with a small group of potential users is recommended to ensure it is as user friendly as possible before going live to a large user base.

University of Macau / Faculty of Social Sciences. / Department of Communication

Chen Yun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 92-100). / Abstracts in English and Chinese; appendix in Chinese. / Chapter Chapter 1 --- Prologue --- p.1 / Chapter Chapter 2： --- "Internet, J-blog, and the Public Sphere..…" --- p.4 / Chapter 2.1. --- The Public Sphere： from West to East --- p.4 / Chapter 2.2. --- Internet and the Public Sphere --- p.8 / Chapter 2.3. --- A Brief History of blog and its Development in China --- p.11 / Chapter 2.4. --- Blogs and the Public Sphere --- p.14 / Chapter 2.5. --- Blogs and Journalism --- p.18 / Chapter 2.6. --- Media and Journalism in China --- p.22 / Chapter 2.7. --- Identity and Public Sphere --- p.26 / Chapter Chapter 3： --- Research Question and Research Methods --- p.30 / Chapter 3.1. --- Research Scope and the Selected Sample --- p.30 / Chapter 3.2. --- A Single Case Study of Anti blog --- p.31 / Chapter 3.3. --- Research Questions: --- p.35 / Chapter 3.4. --- Qualitative methods： --- p.37 / Chapter 3.5. --- Quantitative method： --- p.39 / Chapter Chapter 4： --- Findings --- p.40 / Chapter 4.1 --- Anti blog as alternative public sphere --- p.40 / Chapter 4.2 --- Identity and authority construction of Anti blog --- p.66 / Chapter 4.3. --- The Personalization of j-blog： empowerment and its discontent --- p.76 / Chapter Chapter 5 --- "Discussion： Internet, public sphere and identity construction" --- p.78 / Appendix --- p.90 / Bibliography --- p.92

This study discusses Facebook as a social network site and a social media application. It compares perceived emotional support, general life stress, and media affordance-based stress from two participant samples - one that reported using the Facebook desktop site most frequently to reach out for emotional support, and one that reported using the mobile application. The media affordance measure asked participants if perceiving a media affordance was more likely to increase or decrease their stress. In both samples, persistence was more likely to decrease stress, and personalization was more likely to increase stress. On the Facebook Desktop site, searchability was more likely to increase stress. On the Facebook mobile application, pervasiveness was more likely to decrease stress, and association to increase stress. When comparing affordances between samples, there were no significant differences found. When comparing samples, the Facebook mobile application users reported higher life stress, but there was no difference found in perception of emotional support. Within samples, there was no correlation between perceived stress and perceived emotional support. Finally, there was a significant correlation found between perception of emotional support on the site and frequency of reaching out for emotional support. On the Facebook desktop site, users reached out by public post and by private message significantly less frequently if they perceived a higher level of emotional support to be available on the site. On the Facebook mobile application, users reached out by public post significantly less frequently if they perceived a higher level of emotional support to be available on the application. No correlation was found for reaching out by private message on the Facebook mobile application.