  We propose a wide class of distillation schemes for multi-partite entangled
states that are CSS-states. Our proposal provides not only superior efficiency,
but also new insights on the connection between CSS-states and bipartite graph
states. We then consider the applications of our distillation schemes for two
cryptographic tasks--namely, (a) conference key agreement and (b) quantum
sharing of classical secrets. In particular, we construct
``prepare-and-measure'' protocols. Also we study the yield of those protocols
and the threshold value of the fidelity above which the protocols can function
securely. Surprisingly, our protocols will function securely even when the
initial state does not violate the standard Bell-inequalities for GHZ states.
Experimental realization involving only bi-partite entanglement is also
suggested.
