  This paper follows very closely a famous paper by Csisz\'{a}r and K\"{o}rner
about classical (non-quantum) wiretap coding. Our paper gives a self-contained
and slightly novel review of some important results of the paper by Csisz\'{a}r
and K\"{o}rner. Then we present a generalization of those results to the
quantum realm, thus giving one of the first half-decent treatments of quantum
wiretap coding. Like Csisz\'{a}r and K\"{o}rner, we too find a capacity region
(i.e., the maximal achievable region of rates) characterized in terms of
one-letter informations. We try to make our treatment of quantum wiretap coding
as parallel a possible to our treatment of classical wiretap coding. This
parallel treatment is facilitated by the use of CB nets (classical Bayesian
networks) for the classical case and QB nets (quantum Bayesian networks) for
the quantum one.
