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.

Users and resources in online social networks (OSNs) are interconnected via various types of relationships. In particular, user-to-user relationships form the basis of the OSN structure, and play a significant role in specifying and enforcing access control. Individual users and the OSN provider should be allowed to specify which access can be granted in terms of existing relationships. We propose a novel user-to-user relationship-based access control (UURAC) model for OSN systems that utilizes regular expression notation for such policy specification. We develop a path checking algorithm to determine whether the required relationship path between users for a given access request exists, and provide proofs of correctness and complexity analysis for this algorithm.

Users and resources in online social networks (OSNs) are interconnected via various types of relationships. In particular, user-to-user relationships form the basis of the OSN structure, and play a significant role in specifying and enforcing access control. Individual users and the OSN provider should be enabled to specify which access can be granted in terms of existing relationships. In this paper, we propose a novel user-to-user relationship-based access control (UURAC) model for OSN systems that utilizes regular expression notation for such policy specification. Access control policies on users and resources are composed in terms of requested action, multiple relationship types, the starting point of the evaluation, and the number of hops on the path. We present two path checking algorithms to determine whether the required relationship path between users for a given access request exists. We validate the feasibility of our approach by implementing a prototype system and evaluating the performance of these two algorithms.

Relationship-based access control (ReBAC) has been adopted as themost prominent approach for access control in online social networks (OSNs), where authorization policies are typically specified in terms of relationships of certain types and/or depth between the access requester and the target. However, using relationships alone is often not sufficient to enforce various security and privacy requirements that meet the expectation fromtoday’sOSN users. In thiswork, we integrate attribute-based policies into relationship-based access control. The proposed attribute-aware Re- BAC enhances access control capability and allows finer-grained controls that are not available in ReBAC. The policy specification language for the user-to-user relationship-based access control (UURAC) model proposed in [6] is extended to enable such attribute-aware access control. We also present an enhanced path-checking algorithm to determine the existence of the required attributes and relationships in order to grant access.

Today's ever-evolving online social networks (OSNs) need an effective and usable access control framework. OSN users typically have discretionary control over their content, relationships, and interactions, while the OSN's policies consolidate these individual choices into specific access and filtering decisions. OSN access control can be built around the concept of user activity. To this end, the authors distinguish usage activity from control activity and identify four core control activities: attribute, policy, relationship, and session. Their user-activity-centric framework enables future extensions as needed.