The ever increasing popularity of Facebook and other Online Social Networks has left a wealth of personal and private data on the web, aggregated and readily accessible for broad and automatic retrieval. Protection from both undesired recipients as well as harvesting through crawlers is implemented by simple access control at the provider, configured by manual authorization through the publishing user. Several studies demonstrate that standard settings directly cause an unnoticed over-sharing and that the users have trouble understanding and configuring adequate settings. Using the three simple principles of color coding, ease of access, and application of common practices, we developed a new privacy interface that increases the usability significantly. The results of our user study underlines the extent of the initial problem and documents that our interface enables faster, more precise authorisation and leads to increased intelligibility.
To address privacy concerns over Online Social Networks (OSNs), we propose a distributed, peer-to-peer approach coupled with encryption. Moreover, extending this distributed approach by direct data exchange between user devices removes the strict Internet-connectivity requirements of web-based OSNs. In order to verify the feasibility of this approach, we designed a two-tiered architecture and protocols that recreate the core features of OSNs in a decentralized way. This paper focuses on the description of the prototype built for the P2P infrastructure for social networks, as a first step without the encryption part, and shares early experiences from the prototype and insights gained since first outlining the challenges and possibilities of decentralized alternatives to OSNs. Increasingly, Internet users trade privacy for service. Facebook, Google, and others mine personal information to target advertising. This paper presents a preliminary and partial answer to the general question "Can users retain their privacy while still benefiting from these web services?". We propose NOYB, a novel approach that provides privacy while preserving some of the functionality provided by online services. We apply our approach to the Facebook online social networking website. Through a proof-of-concept implementation we demonstrate that NOYB is practical and incrementally deployable, requires no changes to or cooperation from an existing online service, and indeed can be non-trivial for the online service to detect.  The publication of private data in user profiles in a both secure and private way is a rising problem and of special interest in, e.g., online social networks that become more and more popular. Current approaches, especially for decentralized networks, often do not address this issue or impose large storage overhead. In this paper, we present a cryptographic approach to Private Profile Management that is seen as a building block for applications in which users maintain their own profiles, publish and retrieve data, and authorize other users to access different portions of data in their profiles. In this course, we provide: (i) formalization of confidentiality and unlinkability as two main security and privacy goals for the data which is kept in profiles and users who are authorized to retrieve this data, and (ii) specification, analysis, and comparison of two private profile management schemes based on different encryption techniques.