s/key authentication for Apache on FreeBSD?

[Michael Sierchio]

Brett Glass wrote:

> The people in question have Palm Pilots. And, yes, in a pinch
> slips of paper could be generated. The key thing is to be able
> to get in from a public kiosk without the risk of compromised
> passwords.

The problem with S/key or OPIE authentication is that it
is sadly subject to a MITM attack, and relies on
blind trust in the server.

The challenge is not a random challenge, it is unfortunately
a sequence number and salt -- if I trick you into typing in
the one-time password with a lower sequence number than the
current one you are proper fucked.  I can then generate all of
the subsequent "one-time" passwords.

If you have a half-authenticated SSL connection, and are
conducting the exchange over it, then it should be fine.