Re: [tor-talk] On the Theory of Remailers

[Tom Ritter <tom@xxxxxxxxx>]

On 9 January 2013 10:33, Alexandre Guillioud
<guillioud.alexandre@xxxxxxxxx> wrote:
> Wooo thank's Tom ! First time using mailing lists, i'm going to like it :D
> (and it's not a problem to answer from work :DD).
> Ok, so i understand what you're meaning by high/low latency network.
>
> Just, why don't apply this to web browsing ? Can't each node keep packet up
> to 5 seconde based on random ? 5 second isn't a problem, as tor network is
> already long to serve pages/packets.
>
> From  my point of view, you can't allow some sort of different latency
> paths for clients.
> It will confuse basics users,
> And power users will tweak this to allow only low latency circuits.

Allowing a client to choose their 'delay' and combining low and high
latency networks is (as I understand it) the basis behind Alpha Mixing
[0].

As far as a 5 second window in Tor nodes - off the top of my head, I'm
not sure 5 seconds would really gain anything.  If the nodes you're
using (.e.g bridges) aren't used much, 5 seconds doesn't help you.  On
the other hand, adding 30 seconds (3 hops, 2 directions) to *each*
request, keeping in mind a page maybe have 20 requests quickly makes
web browsing near-unusuable.

The other elephant in the room is that *even with* high latency, given
*enough* traffic, you can always link it statistically.  Think of it
this way: If I'm sending a packet a day to a recipient, you can see a
packet a second leave my machine, and a packet a day received at the
other end.  Even if my message is mixed well, held for an hour and
mixed with other messages - it's not hard after a few days to realize
the correlation.  High latency makes this harder, harder still if you
don't have a regular pattern.  If statistically it's still easy, even
with a 5 second delay, what's the point in making the software harder
to use if you're not getting the defense you seek?

I'm not the authority on Tor's design decisions, but those are my thoughts.

-tom

[0] http://www.freehaven.net/doc/alpha-mixing/alpha-mixing.pdf
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