  We consider the wiretap channel, where the individual channel uses have
memory or are influenced by an adversary. We analyze the explicit and
computationally efficient construction of information-theoretically secure
coding schemes which use the inverse of an extractor and an error-correcting
code. These schemes are known to achieve secrecy capacity on a large class of
memoryless wiretap channels. We show that this also holds for certain channel
types with memory. In particular, they can achieve secrecy capacity on channels
where an adversary can pick a sequence of ``states'' governing the channel's
behavior, as long as, given every possible state, the channel is strongly
symmetric.
