  Mobile social networks (MSNs) are specific types of social media which
consolidate the ability of omnipresent connection for mobile users/devices to
share user-centric data objects among interested users. Taking advantage of the
characteristics of both social networks and opportunistic networks, MSNs are
capable of providing an efficient and effective mobile environment for users to
access, share, and distribute data. However, lack of a protective
infrastructure in these networks has turned them in to convenient targets for
various perils. This is the main impulse why MSNs carry disparate and intricate
safety concerns and embrace divergent safety challenging problems. In this
paper, we aim to provide a clear categorization on safety challenges and a deep
exploration over some recent solutions in MSNs. This work narrows the safety
challenges and solution techniques down from opportunistic networks (OppNets)
and delay tolerant networks (DTNs) to MSNs with the hope of covering all the
work proposed around security, privacy and trust in MSNs. To conclude, several
major open research issues are discussed and future research directions are
outlined.
