[tor-dev] Proposal 320: Removing TAP usage from v2 onion services

[Sebastian Hahn]

Hi there,

> On 19. May 2020, at 19:55, Nick Mathewson <nickm at torproject.org> wrote:
> If we do decide to finally deprecate v2 onion services, that would be
> a significant maintenance burden reduced for us, but we'd have to
> handle the transition carefully.  Unlike all the other migrations
> we've done, there isn't a drop-in path to get the same functionality
> or keep the same identities with v3 onion services.  (And the problem
> is that there _can't_ be: the identities are strongly tied to
> 80-bit-truncated-SHA1 and RSA-1024, and the lack of key blinding makes
> them enumerable.)

I would be exstatic about not having V2 onions around anymore. This
would reduce a huge attack vector that incentivizes people to set up
malicious relays, which causes huge amounts of time lost, the relays
shouldn't have this opportunity to harvest onions, etc.

> The main reason I wrote this proposal is this: Any deprecation will
> probably cause a few users to stick with the old versions of the code
> for as long as they still work on the network, even if those versions
> become unsupported and insecure.  (After all, people who listen to our
> advice about what is secure and what isn't have already stopped using
> v2 onion services.) .

I kind of don't buy the statement in the parentheses, we don't seem
to discourage v2 strongly at all afaict. Or is there a warning when
you use it or connect to it, for example?

A question, is the HSDir flag for both v2 and v3 onions? If not we
could just take that away to break v2 at some point.

> Is it time to start this deprecation?  If so we need to start working
> on a timeline, and I agree with Teor that we'd need to figure out how
> that timeline would work with any walking onions timeline.

I think it should have been started a while ago :)

> What do others think?

Cheers
Sebastian