[tahoe-dev] switching from introducers to gossip?

[Greg Troxel]

  It seems people are only aware of the last feature because of the
  poorly chosen name.  IMO, the "hidden" aspect is one of the less
  interesting features.  I've heard a rumor that there's a proposal to
  make a version of this feature which provides the other features
  without the hidden part for the benefit of lower latency.


An important point is that hidden services consume resources on other
people's systems, and those systems are volunteered for the purpose of
providing anonymity.  The use of bittorrent is discouraged over tor, not
because of philosophical objections, but because the tor network can't
really handle the load.  So while I think tahoe-lafs should work over
tor, I don't think it's entirely responsible (to the set of people that
volunteer tor relays) to suggest routine use of tor merely for firewall
traversal.

That said, it seems connecting to hidden services doesn't require exit
relay use, so hidden services tread more lightly on the really scarce
resource; non-exit relays are much easier to come by.

  As for connection capability: onion addresses are an 80 bit substring
  of a public key hash, so that's 80 bits of unguessable [1].  The
  design doc [2] does not mention a goal such as "undiscoverability"
  which would be necessary for capabilities (ie: You can only learn an
  onion by generating one or being told one out of band, but not by
  sniffing tor introducer or directory service traffic).  However, from
  chatting with tor devs I believe this may be an implemented feature.
  I'm still browsing source code and specs to see if that's true.

My gut feeling is that it's a bad idea to use tor addresses as
capabilities in a system that needs capabilities from other transports.
Instead, I would treat onion addresses simply as addresses.  I see the
point about perhaps eking out a bit of efficiency, but I think it adds
complexity, fragility, and testing difficulty that greatly outweight the
win.

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