I study two privacy-preserving social network graphs to dis- close the types of relationships of connecting edges and provide flexible multigrained access control. To create such graphs, my schemes employ the concept of secretaries and types of relationships. It is significantly more efficient than those that using expensive cryptographic primitives. I also show how these schemes can be used for multigrained access control with various options. In addition, I describe how much these schemes are resilient to infer the types of connecting edges.
Carminati @cite_8 described an access control model where authorized users determined based on the relationships are only granted to access to another user's social network. They stored the encrypted relationship information with relationship keys using public key cryptography.
@cite_8
2010429444 1998591172 2095966401 1986789125
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. 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. Current social networks implement very simple protection mechanisms, according to which a user can slate whether his her personal data, relationships, and resources should be either public or accessible only by him herself (or, at most, by users with whom he she has a direct relationship). This is not enough, in that there is the need of more flexible mechanisms, making a user able to decide which network participants are authorized to access his lier resources and personal information. With this aim, we have proposed an access control model where authorized users are denoted based on the relationships they participate in. Nonetheless, we believe that this is just a first step towards a more comprehensive privacy framework for social networks. Indeed, besides users' resources and personal data, also users' relationships may convey sensitive information. For this reason, in this paper we focus on relationship protection, by proposing a strategy exploiting cryptographic techniques to enfotce a selective dissemination of information concerning relationships across a social network. In this paper we introduce a novel scheme for key management in social networks that is a first step towards the creation of a private social network. A social network graph (i.e., the graph of friendship relationships) is private and social networks are often used to share content, which may be private, amongst its users. In the status quo, the social networking server has access to both this graph and to all of the content, effectively requiring that it is a trusted third party. The goal of this paper is to produce a mechanism through which users can control how their content is shared with other users, without relying on a trusted third party to manage the social network graph and the users' data. The specific access control model considered here is that users will specify access policies based on distance in the social network; for example some content is visible to friends only, while other content is visible to friends of friends, etc. This access control is enforced via key management. That is for each user, there is a key that only friends should be able to derive, there is a key that both friends of the user and friends of friends can derive, etc. The proposed scheme enjoys the following properties: i) the scheme is asynchronous in that it does not require users to be online at the same time, ii) the scheme provides key indistinguishability (that is if a user is not allowed to derive a key according to the access policy, then that key is indistinguishable from a random value), iii) the scheme is efficient in terms of server storage and key derivation time, and iv) the scheme is collusion resistant.