Over the last decade Online Social Networks (OSN) privacy has been thoroughly studied in many aspects. Some of these privacy related aspects are trust and credibility involving the OSN user-data conveyed by different relationships in the network. One of OSN major problems is that users expose their information in a manner thought to be relatively private, or even partially public, to unknown and possibly unwanted entities, such as adversaries, social bots, fake users, spammers or data-harvesters. Preventing this information leakage is the target of many OSN privacy models, such as Access Control, Relationship based models, Trust based models and many others. In this paper we suggest a new Role and Trust based Access Control model, denoted here as RTBAC, in which roles, that manifest different permissions, are assigned to the users connected to the Ego-node (the user sharing the information), and in addition, every user is evaluated trust wise by several criteria, such as total number of friends, age of user account, and friendship duration. An interesting extension of the model of image anonymization is also given, where a user that has a certain role with a proper permission can access a partial instance of the data, if a sufficient trust level is not achieved. These role and trust assessments provide more precise and viable information sharing decisions and enable better privacy control in the social network.
The subset sum problem (SSP) can be simply described as: given a set of integers A, and an integer s, find a subset of items from A summing up to s. To this classic problem there are many variants; one is the multiple-subset problem (MSSP) in which there is a selection of items from a given set to several identical bins, having each bin capacity not exceeded, and the total weight of the items is maximized. Here a related different kind of problem is approached: given a set of sets A = {A1,A2,…,An}, find an integer s, for which every subset of the given sets is summed up to, if such an integer exists. To this specific problem there are several parameters that are applicable: the size of each set-m, the number of sets-n, and the size of every integer (number of digits)-d. For equal sizes of these parameters, a cryptographic application is shown, in which the cipher text is the sequence of the given sets, the private keys are two of the parameters m, n, and d, and the encrypted plain text is the resulted sum s. As a variant of SSP, the problem is NPcomplete, and for known private keys, a relatively efficient algorithm is given, based on dispensing non-relevant values of the possible sums.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.