To be considered for the 2017 IEEE Jack Keil
Wolf ISIT Student Paper Award. We study the state-dependent
(SD) wiretap channel (WTC) with non-causal channel state
information (CSI) at the encoder. This model subsumes all other
instances of CSI availability as special cases, and calls for an
efficient utilization of the state sequence both for reliability and
security purposes. A lower bound on the secrecy-capacity, that
improves upon the previously best known result by Chen and
Han Vinck, is derived based on a novel superposition coding
scheme. The improvement over the Chen and Han Vinck result
is strict for some SD-WTCs. Specializing the lower bound to the
case where CSI is also available to the decoder reveals that it
is at least as good as the achievable formula by Chia and ElGamal,
which is already known to outperform the adaptation
of the Chen and Han Vinck code to the encoder and decoder
CSI scenario. The results are derived under the strict semanticsecurity
metric that requires negligible information leakage for
all message distributions. The proof of achievability relies on
a stronger version of the soft-covering lemma for superposition
codes.