[tor-talk] What is preventing Bridge Enumeration?

[Roger Dingledine]

On Wed, Feb 15, 2017 at 12:10:05PM -0500, Philipp Winter wrote:
> On Wed, Feb 15, 2017 at 02:32:32PM +0100, BVpTuvb AVMV wrote:
> > What is preventing an attacker to start up a few mid-nodes and
> > enumerating all IPs and substracting those from the list of publicly
> > known entry-nodes to get a list of (all) unlisted bridges?
> 
> That is indeed a problem.  Section III.D of the following paper talks
> about the issue in greater detail:
> <https://censorbib.nymity.ch/pdf/Ling2012a.pdf>

Yep! Another resource to look at is
https://blog.torproject.org/blog/research-problems-ten-ways-discover-tor-bridges

There's plenty of work to be done, both in terms of research and in
terms of engineering, on making the bridge idea better.

--Roger