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Re: Hey guys, here is another (great?) idea

On Sat, Nov 19, 2005 at 01:40:56PM -0600, Arrakis Tor wrote:
  [reformatted to fix top-post.]
> On 11/19/05, Nick Mathewson <nickm@xxxxxxxxxxxxx> wrote:
> > On Sat, Nov 19, 2005 at 12:45:48PM -0600, Arrakis Tor wrote:
> > > How do routers do it with DNS tables, that we can't with Tor servers?
> >
> > DNS maps names to values, and doesn't worry about vulenrabilities
> > resulting from adversary knowing which clients have learned which
> > values.  That's not our problem.  Our problem is finding a way for
> > clients to learn about servers and build paths through those servers
> > so that if you (an adversary) see a client, and you control a
> > directory cache, and you control some servers, and you see part of the
> > client's path, you can't deduce with a better-than-chance probability
> > whether the path was generated by the client.
> No no. I mean how routers propagate routes and know paths. Inherently,
> a router does not know the entire path of the internet, however it
> does know who is around, and how to get where it wants data to go.

Ah. I was thrown off by the fact that you said "DNS", not "BGP" or
something.  DNS has nothing to do with how routers learn paths on the
Internet, so I didn't know you were talking about how routers learn
paths on the Internet.

Once again, BGP solves a very different problem: how to make sure that
each router knows the best way to send an IP packet closer to where it
is supposed to go.  It doesn't concern itself with the anonymity
questions I mention above in the slightest.

Trivial example: In Internet routing, you typically trust the first
router you use to route your packets.  But in Tor, if you trust the
first router to pick your path, or give you a list of routers, you are
completely vulnerable to a compromised first router.  There might be
ways around this problem (and the other problems) but they need design
and analysis.

Nick Mathewson

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