  We give new arguments in support of \emph{signed quantum key establishment},
where quantum cryptography is used in a public-key infrastructure that provides
the required authentication. We also analyze more thoroughly than previous
works the benefits that quantum key establishment protocols have over certain
classical protocols, motivated in part by the various objections to quantum key
establishment that are sometimes raised. Previous knowledge of quantum
cryptography on the reader's part is not required for this article, as the
definition of "quantum key establishment" that we use is an entirely classical
and black-box characterization (one need only trust that protocols satisfying
the definition exist).
