  This paper considers the problem of secure coding design for a type II
wiretap channel, where the main channel is noiseless and the eavesdropper
channel is a general binary-input symmetric-output memoryless channel. The
proposed secure error-correcting code has a nested code structure. Two secure
nested coding schemes are studied for a type II Gaussian wiretap channel. The
nesting is based on cosets of a good code sequence for the first scheme and on
cosets of the dual of a good code sequence for the second scheme. In each case,
the corresponding achievable rate-equivocation pair is derived based on the
threshold behavior of good code sequences. The two secure coding schemes
together establish an achievable rate-equivocation region, which almost covers
the secrecy capacity-equivocation region in this case study. The proposed
secure coding scheme is extended to a type II binary symmetric wiretap channel.
A new achievable perfect secrecy rate, which improves upon the previously
reported result by Thangaraj et al., is derived for this channel.
