David Wagner wrote: > One could reasonably ask how often it is in practice that we have a > physical channel whose authenticity we trust, but where eavesdropping > is a threat. I don't know.
The only answer that I have come across - to which I ascribe no view on accuracy - is "undersea fibre" . According to the story, it is possible tap into an undersea fibre without cutting into it, or the shield. Something about a device that bends the fibre, and listens to the energy that escapes... It's accurate enough to isolate individual fibres in a bundle. Of course. Which makes the attack simply a matter of getting there, and for this purpose there are special assets available. (I.e., submarines. google USS Jimmy Carter.) So, the analysis shifts to your threat model described above. How do you know when the enemy - a state that has these subs and these beam benders - is listening on our fibre? Personally, it all sounds like too much like a bad science fiction novel, where normal crypto practices are forgotten for plot reasons. But, that may still be indistinguishable from the actions of your average empire, from where we sit. It remains an interesting thought experiment, as long as we don't forget to challenge the "because we said so" assumptions... iang PS: I think there is one place where "QC" might make more sense: SOSUS. With that network, you don't so much care that the enemy is listening in on your fibre (e.g., RTP commsec says that you don't encrypt the enemy's location because he already knows it. Although there is more to it than that.) What you want is to find out where the enemy is listening in, and when. Then, it just becomes another data point in the tracking game. Still, it seems too elusive an advantage to worry about, in a practical sense. Once the enemy figures it out, he'll stop doing it. Or do it to insert bad data.  http://zdnet.com.com/2100-11-529826.html?legacy=zdnn http://www.spectrum.ieee.org/WEBONLY/publicfeature/apr03/code.html --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]