[cabfpub] Proposed Ballot 183 - Allowing 822 Names and (limited) otherNames

Rich Smith richard.smith at comodo.com
Mon Jan 9 10:39:59 MST 2017


  - HS2.0 Intermediate Certificates again don't follow CABF BR for the 
NameConstraints extension; HS2.0 states that this extension shall not be 
critical, when CABF BR states that it SHOULD be critical; please keep in 
mind that RFC5280 says it MUST be critical, CABF has reduced this 
requirement to a SHOULD to accommodate Apple devices; now that recent 
versions of MacOS and iOS support the NC extension, is it really a good 
sign to lower again the requirements on this extension?

[JR] This is complaint with the current BRs. It doesn't lower the 
requirements on the extension as no change to the BRs is required for 
the root to issue publicly trusted certs.

No, it doesn't lower the requirement, but it does give Digicert 
incentive to argue against increasing the requirement when the time 
comes to do so.  If memory serves our intent when we made the decision 
to make the criticality of name constraints a SHOULD rather than a MUST, 
thereby bucking the RFC5280 requirement, we did so both reluctantly, and 
with the intent that we would update this to a MUST as soon as it was 
feasible to do so w/out adversely affecting a massive number of relying 
parties.  I think the discrepancy in policies here is far more serious 
than you are allowing for, and lends credence to Ryan's arguments 
against this proposal.
Scenario:
We ignore this and Ryan's arguments against, and we pass this proposal.
Next month we decide that the various browsers all now have enough 
support for critical name constraints to update the BRs to MUST, but 
because it will break your newly authorized dual-use certs Digicert is 
now arguing against bringing the BRs back into full compliance w/RFC5280.

-Rich

On 1/4/2017 11:44 AM, Jeremy Rowley via Public wrote:
>
> Thanks Erwann for looking at this.
>
>  - Hotspot 2.0 Root Certificates don't follow CABF BR in the subject 
> field; HS2.0 require « C=US, O=WFA Hotspot 2.0, CN=Hotspot 2.0 Trust 
> Root CA - <ID#> », where CABF BR clause 7.1.2.1 has different 
> expectations on C and O
>
> [JR] I disagree. C the O both accurately represent the CA in this case 
> (the WFA). Although DigiCert operates a root on behalf of the WFA, I 
> believe the CA in this case is the WFA.
>
>  - HS2.0 Intermediate Certificates again don't follow CABF BR for the 
> NameConstraints extension; HS2.0 states that this extension shall not 
> be critical, when CABF BR states that it SHOULD be critical; please 
> keep in mind that RFC5280 says it MUST be critical, CABF has reduced 
> this requirement to a SHOULD to accommodate Apple devices; now that 
> recent versions of MacOS and iOS support the NC extension, is it 
> really a good sign to lower again the requirements on this extension?
>
> [JR] This is complaint with the current BRs. It doesn't lower the 
> requirements on the extension as no change to the BRs is required for 
> the root to issue publicly trusted certs.
>
>  - HS2.0 Intermediate Certificates let the CRLDP extension to be 
> optional, when it's mandatory for CABF BR
>
> [JR] This is not inconsistent. Anyone wanting to issue publicly 
> trusted Hotspot certs would be required to have a CRLDP extension in 
> the intermediate.
>
>  - there has been some effort to standardize the SRVName name form 
> (RFC4985), with (incomplete) Name Constraints matching rules. I don't 
> see any comparable effort for this hotspot-friendlyName name form. 
> Since technically-constrained CAs is a preferred model for enterprises 
> (and browsers), I think it's preferable to describe the expected 
> behaviour of a relying party facing such combinations before blindly 
> allowing them, even more with the « shall not be critical » describe 
> above, which will surely transform someday into a « I won't implement 
> it, it's not critical anyway » and will bite us in the future.
>
> [JR] I4985 has been around since 2007. The WFA friendly name has only 
> existed since 2015. I can bring up technically constrained Sub CAs 
> with the WFA (they'd be open to it), but I do not think the lack of a 
> standardized version of technical constraints creates an inconsistency 
> between the BRs and the WFA CP. Until name constraints are fully 
> defined for friendly names, the cert would never qualify as 
> technically constrained, meaning an audit would be required for each 
> publicly trusted intermediate, etc.
>
> The only change in the BRs I'm asking for is to permit WFA otherNames. 
> As browsers don't currently use the otherName, they won't be affected 
> by the modification, especially the certs themselves would be 
> completely compliant with the BR requirements.
>
> Jeremy
>
>     Le 3 janv. 2017 à 22:07, Jeremy Rowley via Public
>     <public at cabforum.org <mailto:public at cabforum.org>> a écrit :
>
>     Agreed, but this line of reasoning always leads to simply not
>     supporting third party projects because the projects may cause
>     issues with the CAB Forum update. IMO, if a group wants to use
>     publicly trusted certs, then that group inherits all the baggage
>     that goes with it. We really control all the cards on this one as
>     the interoperability is one-way. What would you propose to make
>     sure we can update requirements in the future?  A statement like
>     "CAB Forum can do whatever it wants without notice" is superfluous
>     as this is already the case.
>
>     Jeremy
>
>     *From:*Ryan Sleevi [mailto:sleevi at google.com]
>     *Sent:*Tuesday, January 3, 2017 1:54 PM
>     *To:*Jeremy Rowley <jeremy.rowley at digicert.com
>     <mailto:jeremy.rowley at digicert.com>>
>     *Cc:*CA/Browser Forum Public Discussion List <public at cabforum.org
>     <mailto:public at cabforum.org>>; Peter Bowen <pzb at amzn.com
>     <mailto:pzb at amzn.com>>
>     *Subject:*Re: [cabfpub] Proposed Ballot 183 - Allowing 822 Names
>     and (limited) otherNames
>
>     On Tue, Jan 3, 2017 at 12:46 PM, Jeremy Rowley
>     <jeremy.rowley at digicert.com <mailto:jeremy.rowley at digicert.com>>
>     wrote:
>
>         There is a public file (in the link I provided), but it
>         requires filling out information to access. It's the HotSpot
>         2.0 Technical documentation, which includes the Certificate
>         Policy ("Hostspot 2-0 (R2) OSU Certificate Policy
>         Specification").  The documentation is already free to anyone
>         who wants to enter information and agree to the terms of use.
>
>     Ah, the many meanings of free ;) I suppose it wasn't clear that I
>     was talking more about freedom than beer there :)
>
>         We essentially already have a liaison member from the WFA
>         (DigiCert, Microsoft, Apple, and Google are all members).
>
>     I wouldn't put Google in that list - none of Google's CA/B Forum
>     participants participate in HotSpot 2.0 nor communicate
>     developments on either side of that profile to the other party. I
>     would suggest, to date, only DigiCert does, and only to the extent
>     you've shared anything to the Forum.
>
>     Obviously, the context was that we shouldn't be introducing this
>     to the Web PKI unless we're sure we're not going to repeat all the
>     same mistakes we're currently going through the SHA-1 exception
>     process - or at least trying to learn from them. It would be
>     foolish to ignore the feedback we've received from those affected
>     by SHA-1 when considering expanding that scope.
>
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