Security and Privacy of Distributed Online Social Networks

Online social networks (OSNs) suffer from various security and privacy problems. The main source of the security problems is the central service provider that observes users´ data and relationships. Distributed OSN (DOSN) is an alternative approach where users control their data without having any central service provider. In DOSNs, for the sake of data availability, users replicate or cache data in other users of the OSN. The replica nodes are indeed another kind of service provider in a small scale and with a local view. Therefore, even though decentralization removes the global view of the single provider, it results in having several small ones. By this claim, centralized and distributed OSNs have several common security concerns. Although there exist prior studies discussing and classifying security issues, a fine grained classification of various state-of-the-art solutions is not available. In this paper, we focus on the data privacy, data integrity, and secure social search solutions for centralized and distributed OSNs. Furthermore, we discuss open security problems and concerns, that can be used as future research directions.