[tor-dev] 5-hop hidden service circuits (was: Potential projects for SponsorR (Hidden Services))

Zack Weinberg zackw at panix.com
Tue Oct 21 12:57:27 UTC 2014

On Tue, Oct 21, 2014 at 8:23 AM, Michael Rogers
<michael at briarproject.org> wrote:
> On 20/10/14 14:37, George Kadianakis wrote:
>> On an even more researchy tone, Qingping Hou et al wrote a
>> proposal to reduce the length of HS circuits to 5 hops (down from
>> 6). You can find their proposal here:
>> https://lists.torproject.org/pipermail/tor-dev/2014-February/006198.html
>>  The project is crazy and dangerous and needs lots of analysis,
>> but it's something worth considering. Maybe this is a good time to
>> do this analysis?
> One aspect of this proposal that might be problematic: the client and
> hidden service negotiate a random number and use it to pick a
> rendezvous point from a list of candidates. They must have matching
> lists of candidates.
> With a similar idea in mind, I recently looked into how long it takes
> for two clients to obtain copies of the same consensus. I found out
> that this is never guaranteed to happen, because each client may skip
> a consensus each time it downloads a fresh one. That would need to be
> addressed before implementing the 5-hop proposal.

Yeah, Qingping assumed that clients did converge on the same
consensus, and handwaved over the "and they prove to each other they
are using the same consensus" part.  I agree that needs to get fixed

Qingping graduated and my group has a lot of other projects to juggle
right now, but we are in principle still interested in pursuing that
to some sort of definite conclusion.  Funding of course helps free up
student time :)


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