  Quantum State Sharing (QSS) is a protocol by which a (secret) quantum state
may be securely split, shared between multiple potentially dishonest players,
and reconstructed. Crucially the players are each assumed to be dishonest, and
so QSS requires that only a collaborating authorised subset of players can
access the original secret state; any dishonest unauthorised conspiracy cannot
reconstruct it. We analyse a QSS protocol involving three untrusted players and
demonstrate that quantum steering is the required resource which enables the
protocol to proceed securely. We analyse the level of steering required to
share any single-mode Gaussian secret which enables the states to be shared
with the optimal use of resources.
