Policy specification and enforcement in online social networks using MKNF+

Emerging tools that ease sharing information in online social networks (OSNs) can cause various privacy issues for users. Access control is the main security mechanism in OSNs which is used to tackle such issues. In this paper, a prioritized ontology based access control model for protecting users´ information in OSNs is proposed. In the proposed model, description logic (DL) is used for modeling social networks and MKNF⁺ rules are used for specification of users´ access control policies. Using MKNF⁺, we can have nonmonotonic inference (i.e., closed-world reasoning) in the access control procedure. Conflict among access rules defined by a user in an OSN, is another problem, which is resolved in the proposed model by defining priority levels for the rules in a logical manner. Logical foundation of the model gives accuracy, expressiveness, and inference (of implicit access rules from the explicit ones) to the model, and thus decreases the risk of sharing information in OSNs.