  We consider the task of certification of genuine entanglement of tripartite
states. For this purpose, we first present an "all-versus-nothing" proof of
genuine tripartite Einstein-Podolsky-Rosen (EPR) steering by demonstrating the
non-existence of a hybrid local hidden state (LHS) model in the tripartite
network as a motivation to our main result. A full logical contradiction of the
predictions of the hybrid LHS model with quantum mechanical outcome statistics
for any three-qubit generalized Greenberger-Horne-Zeilinger (GGHZ) states and
pure W-class states is shown. Using logical contradiction, we can distinguish
between the GGHZ and W-class state in a two-sided device-independent (2SDI)
steering scenario. We next formulate a 2SDI steering inequality which is a
generalization of the fine-grained steering inequality (FGI) derived in
\cite{PKM14} for the tripartite scenario. We show that the maximum quantum
violation of this tripartite FGI can be used to certify genuine entanglement of
three-qubit pure states.
