Private relationships in social networks

Current social networks implement very simple protection mechanisms, according to which a user can state 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/her resources and personal information. With this aim, in [21 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 enforce a selective dissemination of information concerning relationships across a social network.