🚀 go-pugleaf

In article <1992Oct15.162327.28555@decuac.dec.com> mjr@hussar.dco.dec.com (Marcus J. "Buddy can you spare a clue?" Ranum) writes:

	   I'm just wondering. What kinds of techniques are usually used for
   synching two crypto streams? Suppose I have a pair of boxes that each can
   talk DES. There is a wire between them. I want to pass data back and
   forth encrypted. What kinds of tricks might I use to get them both talking
   together (and able to understand eachother) ;) without having to pass some
   kind of a key over the wire that an enemy could use?

How timely you should ask this, I'm just about to go off and read up
on key exchange protocols, so I'll be interested in what other answers
come up. But, to get you closer to solid ground, in the case of
symmetric (private-key) systems, the boxes have to have one master key
which is securely installed; they then use this key to exchange
session keys in a secure fashion. Since wiretapping is the threat
being guarded against when you do point-to-point encryption, you need
to assume that the bad guy has recorded every bit you transmitted from
the diagnostics on installation day to the message saying it's been
nice talking to you, we don't need this link anymore
*click* Hmmmmmmmmmmmmmmmmmmm

-- Craig Presson