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

[David Goulet]

On 19 May (13:55:37), Nick Mathewson wrote:
> On Wed, May 13, 2020 at 10:09 AM David Goulet <dgoulet at torproject.org> wrote:
> >
> > On 11 May (16:47:53), Nick Mathewson wrote:

[snip]

> > So thus, I personally will argue that moving v2 to ntor is really not the
> > right thing to do. Onion service v2 are, at this point in time, _dangerous_
> > choice for the users.

[snip]

> 
> 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 don't believe at any point since v3 is stable we made public statement
through our TPO channels that v2 should not be used anymore.

> 
> 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.

One easy timeline here would be "No v2 support in walking onions means
deprecation for v2 by the time the entire network updates".

But apart from that, yes we should work on a timeline and it should not be a
complicated one nor eternally long to deploy.

> 
> One possible role for this proposal is to be kept in reserve, in case
> somebody feels so strongly that they want v2 services to work that
> they want to maintain them themselves, or pay for somebody else to do
> it.  If so, we can indicate this proposal as "the right way to keep v2
> services working without TAP", make it clear that we don't plan to
> implement it, and move along.

Honestly, I really don't think we should even provide or mention a possible
path with an option where v2 can stay alive...

Regardless of threat modelling or v2 use cases or large community of users,
the basic fact that the crypto is *dangerously* out of date with RSA1024 and
truncated SHA-1 is just something we have to _stop_ using. I see this not only
about TAP.

I'll say it and say it again and again, today, in 2020, v2 is _dangerous_ and
it is our responsibility at this point to make sure it goes away sooner than
later for the safety of Tor's users.

Cheers!
David


-- 
2dLUG6IluthaObnf5+xfKeuu4WDC9xYQHzFNeGRqvzw=
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