The popularity of online social networks (OSNs) makes the protection of users' private information an important but scientifically challenging problem. In the literature, relationship-based access control schemes have been proposed to address this problem. However, with the dynamic developments of OSNs, we identify new access control requirements which cannot be fully captured by the current schemes. In this paper, we focus on public information in OSNs and treat it as a new dimension which users can use to regulate access to their resources. We define a new OSN model containing users and their relationships as well as public information. Based on this model, we introduce a variant of hybrid logic for formulating access control policies. We exploit a type of category information and relationship hierarchy to further extend our logic for its usage in practice. In the end, we propose a few solutions to address the problem of information reliability in OSNs, and formally model collaborative access control in our access control scheme.
proposed a rich OSN model in @cite_6 . In their work, not only users but also resources are treated as entities and actions performed by users are considered as relationships in OSNs. As more information are incorporated in their model, many new access control policies can be expressed (more details can be found in Sect. ). Their model supports administrative and filtering policies as proposed in @cite_29 . Besides models, several security protocols based on cryptographic techniques are proposed to enforce relationship-based access control policies, e.g., see @cite_23 @cite_9 @cite_24 @cite_25 @cite_26 @cite_28 @cite_16 .
@cite_26 @cite_28 @cite_9 @cite_29 @cite_6 @cite_24 @cite_23 @cite_16 @cite_25
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User-to-user (U2U) relationship-based access control has become the most prevalent approach for modeling access control in online social networks (OSNs), where authorization is typically made by tracking the existence of a U2U relationship of particular type and or depth between the accessing user and the resource owner. However, today's OSN applications allow various user activities that cannot be controlled by using U2U relationships alone. In this paper, we develop a relationship-based access control model for OSNs that incorporates not only U2U relationships but also user-to-resource (U2R) and resource-to-resource (R2R) relationships. Furthermore, while most access control proposals for OSNs only focus on controlling users' normal usage activities, our model also captures controls on users' administrative activities. Authorization policies are defined in terms of patterns of relationship paths on social graph and the hop count limits of these path. The proposed policy specification language features hop count skipping of resource-related relationships, allowing more flexibility and expressive power. We also provide simple specifications of conflict resolution policies to resolve possible conflicts among authorization policies. The popularity of online social networks (OSNs) makes the protection of users' private information an important but scientifically challenging problem. In the literature, relationship-based access control schemes have been proposed to address this problem. However, with the dynamic developments of OSNs, we identify new access control requirements which cannot be fully captured by the current schemes. In this paper, we focus on public information in OSNs and treat it as a new dimension which users can use to regulate access to their resources. We define a new OSN model containing users and their relationships as well as public information. Based on this model, we introduce a variant of hybrid logic for formulating access control policies. We exploit a type of category information and relationship hierarchy to further extend our logic for its usage in practice. In the end, we propose a few solutions to address the problem of information reliability in OSNs, and formally model collaborative access control in our access control scheme. Topology-based access control is today a de-facto standard for protecting resources in On-line Social Networks (OSNs) both within the research community and commercial OSNs. According to this paradigm, authorization constraints specify the relationships (and possibly their depth and trust level) that should occur between the requestor and the resource owner to make the first able to access the required resource. In this paper, we show how topology-based access control can be enhanced by exploiting the collaboration among OSN users, which is the essence of any OSN. The need of user collaboration during access control enforcement arises by the fact that, different from traditional settings, in most OSN services users can reference other users in resources (e.g., a user can be tagged to a photo), and therefore it is generally not possible for a user to control the resources published by another user. For this reason, we introduce collaborative security policies, that is, access control policies identifying a set of collaborative users that must be involved during access control enforcement. Moreover, we discuss how user collaboration can also be exploited for policy administration and we present an architecture on support of collaborative policy enforcement. Web-based Social Networks (WBSNs) are today one of the hugest data source available on the Web and therefore data protection has become an urgent need. This has resulted in the proposals of some access control models for social networks (e.g., [1, 4, 5, 15, 16]). Quite all the models proposed so far enforce a relationship-based access control, where the granting of a resource depends on the relationships established in the network. An important issue is therefore to devise access control mechanisms able to enforce relationship-based access control by, at the same time, protecting relationships privacy. In this paper, we propose a solution to this problem, which enforces access control through a collaboration of selected nodes in the network. We exploit the ElGamal cryptosystem [11] to preserve relationship privacy when relationship information is used for access control purposes.