Re: [Tails-dev] tordate issue in Tails 0.14~rc1

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Autor: intrigeri
Data:  
Para: The Tails public development discussion list
Assunto: Re: [Tails-dev] tordate issue in Tails 0.14~rc1
Hi,

anonym wrote (16 Oct 2012 13:17:06 GMT) :

> commit 87622e4c7e1a3b5c80e67141de7947d0304b6f31
> Author: Nick Mathewson <nickm@???>
> Date: Mon Nov 14 22:21:45 2011 -0500


>     Allow up to a 30 days future skew, 48 hours past skew in certs.


> In other words, Tor will now back off on the TLS level when
> contacting the dir servers, so if the clock is more than 30 days in
> the past or 2 days in the future, Tor won't download any consensus.


Just curious: this commit makes Tor tolerate servers with *more* clock
skew than previously, so I'm wondering -- did a previous commit, in
the 0.2.3 cycle, introduce this class of checks entirely?
In other words, does Tor 0.2.2 ignore TLS certificates' valid-until?

> To fix this I propose we change our current approach in tordate.
> We replace the "if is_clock_way_off ..." section of tordate with
> something like this:
> [...]
> I know it's a quite hideous beast, but that's the only way I can
> think of that makes tordate behave as it does now.


It's ugly, but I agree we can live with that for a while.
Going to look at the implementation.

> It's quite clear that we need to find a real long-term solution,
> perhaps an option
> SetSystemTimeToMedianOfAllDirectoryAuthoritiesOnBootstrap in
> upstream Tor. But that's a concern we'll have to tackle later.


Yeah. TODO++?

> The only other quick fix I can come up with is using Jacob's tlsdate
> in the clear to set the time (which effectively broadcasts to the
> world "Hey! I'm using Tails!" :/). Well, I suppose the last
> alternative is to not care and ship Tails
> 0.14 with a broken tordate.


Worst case is: not supporting clocks that are more than 30 days in the
past of 2 days in the future, and documenting it in Known Issues.

That would not be very nice, but still, it seems much better to me
than introducing a new piece of software in a hurry: we might want to
use tlsdate at some point, within a rethought time sync' system, but
I'd want to see it live in experimental for a while before we ship it
in a stable Tails release. BTW, I'm happy I've seen a lot of work
being done on tlsdate recently, which probably means a least a few
users / testers, and possibly new features that might be useful in the
context of Tails :)

IMHO: either we manage to implement the proposed ugly hack in a sane
way, or we walk the "Known Issues" way.

Cheers,
--
intrigeri
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