Re: OpenSSH & S/Key information leakage

From: Markus Friedl (markusat_private)
Date: Tue Nov 13 2001 - 04:00:04 PST

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On Sun, Nov 11, 2001 at 06:29:38PM -0700, Joel Maslak wrote:
> There are some bad implementations of S/Key in client programs.  OpenSSH
> (at least on OpenBSD 2.9) is one such bad implementation.  OpenSSH only
> provides this challenge string if (1) the user exists and (2) the user is
> using one-time-passwords.

This depends very much on the version of the OpenSSH and the versions
of your skey library. OpenSSH switched away from creating fake skey
challenges, and now depends on the skey/otp/bsdauth/whatever-library to
created fake challenges. With BSD_AUTH it even depends on the
authentication algorithms available in the default class.

With a post-Nov 2000 OpenBSD, skeychallenge() creates fake challenges,
so OpenSSH does not need to care.

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