  A polar coding scheme is introduced in this paper for the wire-tap channel.
It is shown that the provided scheme achieves the entire rate-equivocation
region for the case of symmetric and degraded wire-tap channel, where the weak
notion of secrecy is assumed. For the particular case of binary erasure
wire-tap channel, an alternative proof is given. The case of general
non-degraded wire-tap channels is also considered.
