[tor-relays] Onion v2 HSDir Support (ref: v3 prop224) [was: fishy fingerprint patterns]

[Mirimir]

On 01/03/2019 11:06 PM, teor wrote:

<SNIP>

> Hopefully, we'll have feature parity on v3 very soon. And then
> apps will migrate from v2 to v3 (or dual-stack).
> 
> It's best if we transition slowly, in a planned manner. But we do
> need to transition in the next few years. Otherwise, we might have
> to transition quickly due to network or crypto breaks. And that's
> not a good experience for anyone.

I get how that's a great plan. However, OnionCat can't work with v3,
even with tweaking, because the address space is orders of magnitude
greater than the available IPv6 /48. I suppose that one could use a
_way_ bigger IPv6 range, but that would necessarily use IPv6 addresses
that are actually assigned on the clearnet. And that'd create chaos if
someone peered OnionCat to clearnet.

Alternately, one could somehow restrict v3 hostname creation to a
subset, equal in size to the v2 address space (and so to the IPv6 /48
address space). But that sounds computationally expensive. And also
perhaps quite the vulnerability.

If OnionCat doesn't get fixed or replaced, and Tor drops v2 support,
there will be lots of unhappy users. It's already becoming problematic,
with all the unpatched v2 bugs. There might even be enough of a userbase
to fork Tor. And that won't be good for anyone, either. But perhaps
impacts could be mitigated if fork relays worked with the main network.

<SNIP>