[tor-talk] NSA, Tempora, PRISM And Company always know who is behind Tor?

[Andreas Krey]

On Sun, 21 Jul 2013 13:06:31 +0000, Eugen Leitl wrote:
...
> > tor uses a circut guard - middle - exit and unless the NSA can get access
> > to the guard's isp, the middle's isp, and the exit's isp which more than
> 
> The Internet topology is mostly a tree. Tapping the fiber at a few chokepoints
> (e.g. 5 for Germany) is sufficient to access the bulk of traffic.

Yes, but doing that doesn't help the adversary if the chokepoint doesn't
observe the connection between end user and guard node, and that's the
point in trying to select 'sufficiently local' guards. In that case
you (the adversary, that is) can see the guard's aggregated traffic,
but not deduce which end users cause it.

Tapping chokepoints isn't quite global, you'd need to get at the
locally-chosed guard's traffic as well.

Andreas

-- 
"Totally trivial. Famous last words."
From: Linus Torvalds <torvalds@*.org>
Date: Fri, 22 Jan 2010 07:29:21 -0800