[cabfpub] Pre-Ballot - Short-Life Certificates
Jeremy.Rowley
jeremy.rowley at digicert.com
Tue Oct 28 16:08:17 MST 2014
The BR change wouldn't prohibit revocation pointers. Instead, the BRs
should give CAs the option of using certificate expiration as an
alternative to revocation. CAs who are worried about immediate
revocation (<2 days) can still chose to include the pointers.
Whether DigiCert will issue short-lived certs with or without the BR
change is irrelevant. If short-lived certs are something CAs can
implement without requiring browser updates, why not roll it out that
way? What advantage is there in requiring browsers to change all their
code instead of letting CAs do the work?
Jeremy
On 10/28/2014 4:46 PM, Ryan Sleevi wrote:
>
>
> On Oct 28, 2014 3:42 PM, "kirk_hall at trendmicro.com
> <mailto:kirk_hall at trendmicro.com>" <kirk_hall at trendmicro.com
> <mailto:kirk_hall at trendmicro.com>> wrote:
> >
> > Jeremy – as a CA who is potentially interested in issuing short-life
> certs – are you saying you would not want to issue any short-life
> certs if (say) 30% of browsers in use will do revocation checking and
> 70% will not (because some but not all browsers modify their code to
> ignore revocation pointers in the short lived certs as a policy
> matter)? It seem in that example that the load on your OCSP servers
> will be only 30% of today’s load for longer life certs with revocation
> checking – isn’t that an improvement?
> >
> >
> >
> > Put another way, are you only willing to issue short-life certs if
> you know that 100% of browsers and applications will not check for
> revocation (because the BRs would prohibit revocation pointers in the
> short-life certs)?
> >
> >
> >
> > Related to that – what happens today in the browsers if they
> encounter a cert that has NO revocation pointers (no CDP or AIA inside
> the cert)? Do they treat the cert as valid? Or do they put up a
> warning?
> >
> >
> >
> > If browsers today put up a warning, it seems that 100% of browsers
> would have to modify and distribute their code to stop showing
> warnings in order for short lived certs to be viable – true? Just
> prohibiting revocation pointers in these certs via the BRs will not
> automatically make them viable in 100% of browsers.
> >
>
> No browser shows a warning for DV in the standard configuration.
>
> Several browsers offer (generally undocumented) functionality to
> always require revocation checking, but this is so awful that users
> are already conditioned to see errors regularly.
>
> >
> >
> > From: Jeremy.Rowley [mailto:jeremy.rowley at digicert.com
> <mailto:jeremy.rowley at digicert.com>]
> > Sent: Tuesday, October 28, 2014 3:15 PM
> > To: i-barreira at izenpe.net <mailto:i-barreira at izenpe.net>;
> philliph at comodo.com <mailto:philliph at comodo.com>; Kirk Hall (RD-US)
> > Cc: public at cabforum.org <mailto:public at cabforum.org>
> >
> > Subject: Re: [cabfpub] Pre-Ballot - Short-Life Certificates
> >
> >
> >
> > The benefit is to everyone:
> > 1) CAs benefit by having a reduced load on their OCSP servers (at
> the exchange of more certificates issued)
> > 2) Subscribers benefit from a shortened lifecycle for revocation
> (two days instead of 10)
> > 3) Server operators benefit from smaller certificate sizes and no
> call back to the CA to check revocation information
> >
> > Jeremy
> >
> > On 10/28/2014 8:27 AM, i-barreira at izenpe.net
> <mailto:i-barreira at izenpe.net> wrote:
> >>
> >> How do you already know this is going to be a benefit? For who?
> Subscribers?
> >>
> >>
> >>
> >>
> >>
> >> Iñigo Barreira
> >> Responsable del Área técnica
> >> i-barreira at izenpe.net <mailto:i-barreira at izenpe.net>
> >>
> >> 945067705
> >>
> >>
> >>
> >> ERNE! Baliteke mezu honen zatiren bat edo mezu osoa legez babestuta
> egotea. Mezua badu bere hartzailea. Okerreko helbidera heldu bada
> (helbidea gaizki idatzi, transmisioak huts egin) eman abisu igorleari,
> korreo honi erantzuna. KONTUZ!
> >> ATENCION! Este mensaje contiene informacion privilegiada o
> confidencial a la que solo tiene derecho a acceder el destinatario. Si
> usted lo recibe por error le agradeceriamos que no hiciera uso de la
> informacion y que se pusiese en contacto con el remitente.
> >>
> >>
> >>
> >> De: public-bounces at cabforum.org
> <mailto:public-bounces at cabforum.org>
> [mailto:public-bounces at cabforum.org
> <mailto:public-bounces at cabforum.org>] En nombre de Jeremy.Rowley
> >> Enviado el: martes, 28 de octubre de 2014 15:19
> >> Para: Phillip Hallam-Baker; kirk_hall at trendmicro.com
> <mailto:kirk_hall at trendmicro.com>
> >> CC: public at cabforum.org <mailto:public at cabforum.org>
> >> Asunto: Re: [cabfpub] Pre-Ballot - Short-Life Certificates
> >>
> >>
> >>
> >> By not making a change in the BRs, the CAB Forum is essentially
> saying CAs can't use expiration as a means of revocation. Without the
> benefit provided by short lived certs, you won't have subscribers
> using them.
> >>
> >> Jeremy
> >>
> >> On 10/28/2014 7:49 AM, Phillip Hallam-Baker wrote:
> >>>
> >>> Which is why I disagreed with Gerv’s claim that there is no point
> to issuing short lived certs with the revocation indicators present.
> The point is that it establishes a base of deployment that can then be
> used to justify the necessary changes in the BRs.
> >>>
> >>>
> >>>
> >>> The reason that I am interested in short lived certs even with the
> compressed CRL technology is because even a compressed delta CRL is
> still a list. The scaling issue is postponed, not eliminated.
> >>>
> >>>
> >>>
> >>> If however we combine short lived certs with compressed CRLs we
> can reduce the vulnerability window from days to hours. Which is a big
> gain because it would mean that we likely remove the incentive to
> attempt an attack.
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> The secret to keeping Disneyland clean is that the park is already
> clean. People feel bad about littering if the place is clean. If there
> is litter they don’t feel bad about making more.
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> On Oct 27, 2014, at 10:26 PM, kirk_hall at trendmicro.com
> <mailto:kirk_hall at trendmicro.com> wrote:
> >>>
> >>>
> >>>
> >>>
> >>> Not everyone agrees at this point that the risk profile of
> short-lived certs that can't be recalled (no revocation checking
> possible) is equivalent to the risk profile of long-lived certs with
> revocation checking but with all the limitations discussed.
> >>>
> >>> Leaving the decision on whether to accept short-lived certs with
> no revocation checking to the interested browsers and interested CAs
> means that other CAs and browsers don't have to approve or participate
> -- and no changes to the BRs would be required.
> >>>
> >>> -----Original Message-----
> >>> From: Jeremy Rowley [mailto:jeremy.rowley at digicert.com
> <mailto:jeremy.rowley at digicert.com>]
> >>> Sent: Monday, October 27, 2014 6:26 PM
> >>> To: Kirk Hall (RD-US); Gervase Markham; Tim
> Hollebeek;public at cabforum.org <mailto:Hollebeek%3Bpublic at cabforum.org>
> >>> Subject: RE: [cabfpub] Pre-Ballot - Short-Life Certificates
> >>>
> >>> If short-lived certs are an acceptable form of revocation
> checking, then what advantage is there to use a phased-in approach
> with customer browser code? You get the same benefits with no changes
> by simply omitting the revocation pointers. I don't see what risks
> are mitigated by phasing in short-lived certs only for new browsers.
> >>>
> >>> Jeremy
> >>>
> >>> -----Original Message-----
> >>> From: public-bounces at cabforum.org
> <mailto:public-bounces at cabforum.org>
> [mailto:public-bounces at cabforum.org
> <mailto:public-bounces at cabforum.org>] On Behalf Of
> kirk_hall at trendmicro.com <mailto:kirk_hall at trendmicro.com>
> >>> Sent: Monday, October 27, 2014 5:44 PM
> >>> To: Gervase Markham; Tim Hollebeek; public at cabforum.org
> <mailto:public at cabforum.org>
> >>> Subject: Re: [cabfpub] Pre-Ballot - Short-Life Certificates
> >>>
> >>> Gerv, I've pasted in your original response to this question below.
> >>>
> >>> If I can summarize, you don't want revocation pointers in new
> "short lived certs" as defined because legacy browsers and apps (i.e.,
> every browser and app in use today) will continue to check for
> revocation information, thereby lowering the benefit of this new type
> of cert. (You estimated 90% will still check for revocation -- but is
> that number realistic under Google's and Mozilla's current revocation
> checking processes? I thought revocation checking was already omitted
> today for many long-lived certs...)
> >>>
> >>> My question back is: how long would it take Firefox and Google
> (and other interested browsers) to modify your browser software as Tim
> and Rich have suggested - ignore revocation pointers if the cert is a
> short lived cert? And how quickly would those code changes get
> distributed to your users?
> >>>
> >>> The burden of revocation checking falls mostly on CAs, and it can
> only get better (fewer revocation checks) if some browsers decide not
> to check revocation for (self-designated) short lived cert by
> modifying their software. So why not just move forward as browsers to
> do this? The revocation checking burden on CAs that decide to start
> issuing short-lived certs would not go up as compared to current long
> lived certs, and over time (maybe quickly) would go down.
> >>>
> >>> Having said that, Trend Micro is not yet convinced this is a good
> idea for the reasons stated by others -- but the browsers don't have
> to wait if they think the risk from eliminating revocation checking
> for short lived certs is acceptable.
> >>>
> >>> -----Original Message-----
> >>> From: public-bounces at cabforum.org
> <mailto:public-bounces at cabforum.org>
> [mailto:public-bounces at cabforum.org
> <mailto:public-bounces at cabforum.org>] On Behalf Of Gervase Markham
> >>> Sent: Monday, October 27, 2014 12:33 PM
> >>> To: Tim Hollebeek; public at cabforum.org <mailto:public at cabforum.org>
> >>> Subject: Re: [cabfpub] Pre-Ballot - Short-Life Certificates
> >>>
> >>> On 27/10/14 14:14, Tim Hollebeek wrote:
> >>>
> >>>
> >>> What does not having the revocation information in the cert
> actually solve?
> >>>
> >>>
> >>> I've covered this earlier in the thread :-)
> >>>
> >>> Gerv
> >>> _______________________________________________
> >>>
> >>> On 24/10/14 13:40, Rich Smith wrote:
> >>>
> >>>
> >>> I keep coming back to this same question every time this comes up,
> and
> >>> I have not received a satisfactory answer yet:
> >>> Why MUST a short lived certificate be issued without containing
> >>> revocation information?
> >>>
> >>>
> >>> And I keep asking it every time you ask: because putting in
> revocation information eliminates 90% of their advantage, because
> there is then no advantage in all the currently-existing clients. A
> short-lived cert with revocation pointers will still incur the delay
> of revocation checking, even though (this is the argument, and the
> argument with which I hope you will engage) it's not necessary to
> provide them because the security properties of a 3-day cert are
> broadly comparable to a 1-year cert with 10-day, 5-day or 3-day-expiry
> OCSP responses.
> >>>
> >>>
> >>>
> >>> The simple fact of the matter is that revocation info in the
> >>> certificate MAY help SOME users IF the certificate gets revoked,
> and I
> >>> have yet to see anyone offer up any decent argument for why the
> >>> revocation info absolutely MUST NOT be present for short-lived
> certs to work.
> >>>
> >>>
> >>> No one is arguing that it MUST NOT be present for short-lived
> certificates to "work". But if a site and a CA are together
> considering deploying such a technology, they will look at the costs
> and benefits.
> >>> There will be significant costs in setting up the system; if the
> benefits are only in 5% or 10% of clients, it may well be judged not
> to be worth it.
> >>>
> >>>
> >>>
> >>> I'm open
> >>> to such an argument, but until I see it I remain opposed to a ballot
> >>> to allow any certificate to be issued without revocation information.
> >>>
> >>>
> >>> I don't understand this position. Surely the acceptability or not
> of short-lived certificates should depend on whether their security
> properties are broadly comparable to existing solutions, not on
> whether I can construct an argument that shows it's required to remove
> the revocation information for it to be technically feasible to deploy
> them?
> >>>
> >>> Gerv
> >>> <table class="TM_EMAIL_NOTICE"><tr><td><pre>
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