on Mon, Nov 20, 2000 at 09:22:16AM +1100, Brian May (bam@debian.org) wrote:
> >>>>> "Dave" == Dave Sherohman <esper@sherohman.org> writes:
>
> Dave> OK, now you's lost me... I thought the big advantage of
> Dave> public keys was exactly that - they're public. You don't
> Dave> have to worry about transferring them securely, so long as
> Dave> the corresponding private key remains safe.
>
> Yes. You are correct. The key can be public.
>
> Dave> To map this onto the specific case at hand, ssh, if you were
> Dave> to obtain my public ssh key, the worst thing that could
> Dave> result from this interception is that you could add it to
> Dave> your list of authorized_keys and allow me to freely use your
> Dave> account - which is a detriment to the person intercepting
> Dave> the key, not the person owning it. (I'm ignoring the
> Dave> possibility that you might try to factor the public key, as
> Dave> doing so is generally considered to be a practical
> Dave> impossibility for the foreseeable future.)
>
> However, you are incorrect here. The worse case situation is that I
> can intercept your public key *and* replace it with my own, meaning I
> can use now use *your* account. Just because the key is "public"
> doesn't mean you can freely transfer it without regard to security
> :-(.
Sorry?
- I establish a private RSA authentication key for ssh.
- I send the corresponding public key to remoteserver.
- You intercept the transmission and replace my public key with yours.
I can now:
- *Not* access the host I'd intended to provide access to (wrong
public key).
- Possibly be tricked into accessing a host of your chosing via your
key.
...though this is a rather byzantine attack, and not particularly
useful, IMO.
--
Karsten M. Self <kmself@ix.netcom.com> http://www.netcom.com/~kmself
Evangelist, Zelerate, Inc. http://www.zelerate.org
What part of "Gestalt" don't you understand? There is no K5 cabal
http://gestalt-system.sourceforge.net/ http://www.kuro5hin.org
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