This paper introduces the notion of a secure data capsule, which refers to an encapsulation of sensitive user information (such as a credit card number) along with code that implements an interface suitable for the use of such information (such as charging for purchases) by a service (such as an online merchant). In our capsule framework, users provide their data in the form of such capsules to web services rather than raw data. Capsules can be deployed in a variety of ways, either on a trusted third party or the user's own computer or at the service itself, through the use of a variety of hardware or software modules, such as a virtual machine monitor or trusted platform module: the only requirement is that the deployment mechanism must ensure that the user's data is only accessed via the interface sanctioned by the user. The framework further allows an user to specify policies regarding which services or machines may host her capsule, what parties are allowed to access the interface, and with what parameters. The combination of interface restrictions and policy control lets us bound the impact of an attacker who compromises the service to gain access to the user's capsule or a malicious insider at the service itself.
Privacy frameworks that require only participation from users have been proposed as an alternative to web services. VIS @cite_0 maintains a social network is maintained in a completely decentralized fashion by users hosting their data on trusted parties of their own choice; there is no centralized web service. Capsules are more compatible with the current ecosystem of a web service storing user's data and rely on the use of interfaces to guarantee privacy. NOYB @cite_50 and LockR @cite_7 are two recent proposals that rely on end-to-end encryption to hide data from social networks; both these approaches are specific to social networks, and their mechanisms can be incorporated in the capsule framework as well, if so desired.
@cite_0 @cite_7 @cite_50
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People increasingly generate content on their mobile devices and upload it to third-party services such as Facebook and Google Latitude for sharing and backup purposes. Although these services are convenient and useful, their use has important privacy implications due to their centralized nature and their acquisitions of rights to user-contributed content. This paper argues that people's interests would be be better served by uploading their data to a machine that they themselves own and control. We term these machines Virtual Individual Servers (VISs) because our preferred instantiation is a virtual machine running in a highly-available utility computing infrastructure. By using VISs, people can better protect their privacy because they retain ownership of their data and remain in control over the software and policies that determine what data is shared with whom. This paper also describes a range of applications of VIS proxies. It then presents our initial implementation and evaluation of one of these applications, a decentralized framework for mobile social services based on VISs. Our experience so far suggests that building such applications on top of the VIS concept is feasible and desirable. Today's online social networking (OSN) sites do little to protect the privacy of their users' social networking information. Given the highly sensitive nature of the information these sites store, it is understandable that many users feel victimized and disempowered by OSN providers' terms of service. This paper presents Lockr, a system that improves the privacy of centralized and decentralized online content sharing systems. Lockr offers three significant privacy benefits to OSN users. First, it separates social networking content from all other functionality that OSNs provide. This decoupling lets users control their own social information: they can decide which OSN provider should store it, which third parties should have access to it, or they can even choose to manage it themselves. Such flexibility better accommodates OSN users' privacy needs and preferences. Second, Lockr ensures that digitally signed social relationships needed to access social data cannot be re-used by the OSN for unintended purposes. This feature drastically reduces the value to others of social content that users entrust to OSN providers. Finally, Lockr enables message encryption using a social relationship key. This key lets two strangers with a common friend verify their relationship without exposing it to others, a common privacy threat when sharing data in a decentralized scenario. This paper relates Lockr's design and implementation and shows how we integrate it with Flickr, a centralized OSN, and BitTorrent, a decentralized one. Our implementation demonstrates Lockr's critical primary benefits for privacy as well as its secondary benefits for simplifying site management and accelerating content delivery. These benefits were achieved with negligible performance cost and overhead. 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.