Re: [lamps] Warren Kumari's Block on charter-ietf-lamps-02-00: (with BLOCK and COMMENT)

On Wed, May 23, 2018 at 1:39 PM Yoav Nir <ynir.ietf@gmail.com> wrote:

> Hi Warren.
>
> Since it was my draft and presentation at SecDispatch that led to this
> item, I feel I can answer this.  Inline.
>
> > On 23 May 2018, at 20:10, Warren Kumari <warren@kumari.net> wrote:
> >
> > Warren Kumari has entered the following ballot position for
> > charter-ietf-lamps-02-00: Block
> >
> > When responding, please keep the subject line intact and reply to all
> > email addresses included in the To and CC lines. (Feel free to cut this
> > introductory paragraph, however.)
> >
> >
> >
> > The document, along with other ballot positions, can be found here:
> > https://datatracker.ietf.org/doc/charter-ietf-lamps/
> >
> >
> >
> > ----------------------------------------------------------------------
> > BLOCK:
> > ----------------------------------------------------------------------
> >
> > "3. Specify the use of short-lived X.509 certificates for which no
> > revocation information is made available by the Certification Authority.
> > Short-lived certificates have a lifespan that is shorter than the time
> > needed to detect, report, and distribute revocation information, as a
> > result revoking them pointless."
> >
> > This makes me twitch -- how short is "short”?
>
> [YN] I expect this to be contentious within the working group, and I
> expect the exact cut-off point to be different from one use-case to
> another. For highly reliable systems with good clock synchronization
> “short” could be as low as an hour. For typical systems I think the likely
> lifetime will be between 1 day and 1 week.  IMHO it’s valid for the working
> group to leave the cut-off between “short” and “not short” to per-domain
> profiles, but I don’t think anything beyond 2 weeks would ever count as
> short.
>
> > And how long is the time to
> > "detect, report, and distribute revocation information"? With e.g: CT,
> > misissued certificates may be visible before they are used in an attack,
> > decreasing the detection time.
>
> [YN] Someone needs to see the certificate to add it to the log, and
> someone needs to find the certificate on the log and understand that it is
> mis-issued. And then someone needs to add it to the CRL / database that
> feeds the OCSP responder. And when this is updated, relying parties may
> have cached copies of older revocation information. Add it up and it can
> take days on the web.  In closed environments there may not be CT at all.
>
>
So, here you say: "Add it up and it can take days on the web." and above
that you say: "For typical systems I think the likely lifetime will be
between 1 day and 1 week.  [...] , but I don’t think anything beyond 2
weeks would ever count as short."

"1 week" minus "days" is still greater than zero, and so it still *seems*
to me that removing revocation is a bad idea -- but, my role is (or should
be!) to make sure that this charter doesn't conflict with other work (esp.
ops work), that the charter "describes the specific problem or deliverables
(a guideline, standards specification, etc.) it has been formed to address.
WG charters state the scope of work for group, and lay out goals and
milestones that show how this work will be completed." It is (IMO) the
sponsoring ADs, the WGs and IETFs decision as to if the ideas themselves
are acceptable.
I'm not (yet!) so arrogant that I'm sure I know the right answer to
everything, so I'd like to discuss this with EKR on the call tomorrow, and
will clear my block once I've been assured process is being followed
/ this has been considered.

>
> > Also, I would figure that it is still useful to know that a certificate
> was
> > revoked and didn't just expire -- if I see a certificate which expired 10
> > minutes ago I may be willing (after some consideration, checking my
> clock, etc)
> > to decide to trust it anyway (even if that's a bad idea!), but a revoked
> > certificate is a clear indication that something bad happened, and
> changes my
> > risk assessment.
>
> [YN] Yes, and the candidate draft has a SHOULD-level requirement to not
> allow any grace periods for such certificates. One of the feedbacks I got
> was that this should be upgraded to MUST (or rather MUST NOT)
>
>
Ok. That helps.

Thanks!
W

>
> > It's entirely possible that there is a really good reason why I'm wrong
> / that
> > this argument doesn't make sense in some use cases (or just that I'm
> nuts!)
>
> [YN] There was some push-back about the name. The important point is not
> so much that the lifetime is short, but that there is no revocation
> information. We want these certificates because we don’t want to deal with
> revocation information. Non-revocation is the end.  Making them short-term
> is the means, or rather the sacrifice we need to make to make (other)
> security people happy.
>
> > ----------------------------------------------------------------------
> > COMMENT:
> > ----------------------------------------------------------------------
> >
> >
> > Also, "revoking them pointless" does not parse - perhaps "revoking them
> is pointless"?
> >
> >
> > _______________________________________________
> > Spasm mailing list
> > Spasm@ietf.org
> > https://www.ietf.org/mailman/listinfo/spasm
>
>

-- 
I don't think the execution is relevant when it was obviously a bad idea in
the first place.
This is like putting rabid weasels in your pants, and later expressing
regret at having chosen those particular rabid weasels and that pair of
pants.
   ---maf