  Wyner's elegant model of wiretap channel exploits noise in the communication
channel to provide perfect secrecy against a computationally unlimited
eavesdropper without requiring a shared key. We consider an adversarial model
of wiretap channel proposed in [18,19] where the adversary is active: it
selects a fraction $\rho_r$ of the transmitted codeword to eavesdrop and a
fraction $\rho_w$ of the codeword to corrupt by "adding" adversarial error. It
was shown that this model also captures network adversaries in the setting of
1-round Secure Message Transmission [8]. It was proved that secure
communication (1-round) is possible if and only if $\rho_r + \rho_w <1$.
  In this paper we show that by allowing communicants to have access to a
public discussion channel (authentic communication without secrecy) secure
communication becomes possible even if $\rho_r + \rho_w >1$. We formalize the
model of \awtppd protocol and for two efficiency measures, {\em information
rate } and {\em message round complexity} derive tight bounds. We also
construct a rate optimal protocol family with minimum number of message rounds.
We show application of these results to Secure Message Transmission with Public
Discussion (SMT-PD), and in particular show a new lower bound on transmission
rate of these protocols together with a new construction of an optimal SMT-PD
protocol.
