[tor-dev] Silly (or not so silly) question

[Roger Dingledine]

On Wed, Jul 23, 2014 at 11:24:47PM +0100, Noel David Torres Taño wrote:
> What would happen if a Tor node changes behaviour and uses four or five
> relay steps instead of three?
>
> Would it enhance Tor's security?

I assume you mean a Tor client?

https://www.torproject.org/docs/faq#ChoosePathLength

> Is it possible to relay Tor through a Tor connection? I mean using Tor
> with its three steps to reach a Tor entry node to get three extra steps.

Yes, it is possible. But it is currently considered a flaw, because it
can be used to work around the 'infinite path length' defenses.
http://freehaven.net/anonbib/#congestion-longpaths
https://gitweb.torproject.org/torspec.git/blob/HEAD:/proposals/110-avoid-infinite-circuits.txt
https://trac.torproject.org/projects/tor/ticket/2667

> Would that difficult correlation attacks?

Defending against correlation attacks is an open research, so "maybe".
But it's not clear how it would, since an adversary who can see or
measure your first hop (on the first circuit) and also your last hop
(on the last circuit) would still be in the right place to do the attack.

--Roger