  Motivated by the recent studies on post-quantum steering, we generalize the
notion of bipartite channel steering by introducing the concept of multipartite
no-signaling channel assemblages. We first show that beyond the bipartite case,
the no-signaling and quantum descriptions of channel assemblages do not
coincide. Using the Choi-Jamio{\l}kowski isomorphism, we present a complete
characterization of these classes of assemblages and use this characterization
to provide sufficient conditions for extremality of quantum channel assemblages
within the set of all no-signaling channel assemblages. Finally, we introduce
and discuss a relaxed version of channel steering where only certain subsystems
obey the no-signaling constraints. In this latter asymmetric scenario we show
the possibility of certifying a perfect key bit that is secure against a
general no-signaling eavesdropper.
