[cabfpub] Section 9.2.3 modification

[Jeremy Rowley]

The certificates do not indicate the subject per se.  They are part of the
subject in that the DC is domain for the community of interest, but the
domain in the DC fields is not typically controlled by the subject. In the
example certs I provided, the DC varies. I'll need to do further research,
but I believe these fields are an important part on how the IGTF LDAP
directory works (per RFC2247).

I can't speak for other CAs, but in our grid certs, we use the DigICert
domain (since we are acting as the RA for each community).  We don't need to
contact anyone since we already know we control the domain.  For other
entities, the most common one I've seen and know of is Terena, where the DC
specifies a Terena controlled domain.  I imagine the domain listed in the DC
is verified in a typical BR fashion.

As far as usability, the practical effect of the BRs on this area is to
create a conflict with another community that has been using the DC field
for control purposes for a long time.  The conflict is unnecessary since
browsers aren't currently using the DC field. The practical effect is to
drive community members away from publicly trusted certificates and create
headaches with managing multiple certificates on the same device.

The original language for the rule originated from RFC2247 which says " As
with a domain name, the most significant component, closest to the root of
the namespace, is written last." Instead of re-writing the rules, I think it
would be more accurate to simply tie the DC field to RFC2247.  I can see the
concern about making sure the domain is authorized, but the only requirement
in the BRs to include a certificate is verification under Section 11.1. I
don't think we should deviate on that for that simply because this is the DC
field instead of the subjectAltName extension.

How about the following:
 9.2.3 Subject Domain Component Field
Certificate Field: subject:domainComponent (OID 0.9.2342.19200300.100.1.25)
Required/Optional: Optional.
Contents: If present, this field MUST comply with RFC 2247 and  contain
components of a Domain Name that is verified pursuant to Section 11.1.

Thanks,
Jeremy


-----Original Message-----
From: public-bounces at cabforum.org [mailto:public-bounces at cabforum.org] On
Behalf Of Ryan Sleevi
Sent: Wednesday, May 22, 2013 6:00 PM
To: jeremy rowley
Cc: CABFPub
Subject: Re: [cabfpub] Section 9.2.3 modification

On Wed, May 22, 2013 at 4:32 PM, Jeremy Rowley <jeremy.rowley at digicert.com>
wrote:
> Hi everyone,
>
>
>
> As mentioned there is an incompatibility between the Baseline 
> Requirements and other industry groups on what information should be 
> included in a Domain Component Field. I modified the motion slightly 
> based on Ryan Sleevi's comments during last week's phone call.  Please 
> let me know if you are willing to endorse or have suggestions.
>
>
>
> ---Motion Begins----
>
> Replace Section 9.2.3
>
>
>
> Certificate Field:  subject:domainComponent (OID 
> 0.9.2342.19200300.100.1.25)
>
> Required/Optional:  Optional.
>
> Contents:  If present, this field MUST contain all components of the 
> subject's Registered Domain Name in ordered sequence, with the most 
> significant component, closest to the root of the namespace, written last.
>
>
>
> With the following:
>
>
>
> 9.2.3 Subject Domain Component Field
>
> Certificate Field: subject:domainComponent (OID 
> 0.9.2342.19200300.100.1.25)
>
> Required/Optional: Optional.
>
> Contents: If present, this field MUST contain components of a Domain 
> Name verified under Section 11.1.1 in ordered sequence, with the most 
> significant component, closest to the root of the namespace, written 
> last. The CA SHALL implement and follow a process that prevents a 
> Domain Component field from including  information if the CA is 
> unaware of the logical association between the Domain Component field 
> information and the Certificate's Subject.
>
>
>
> -----Motion Ends-----
>

Jeremy

In looking at the original language - which your proposal refines - it
actually strikes me as a bit odd.

Namely: "with the most significant component, closest to the root of the
namespace, written last"

I'm guessing this is the classic "hierarchy of name components"
problem that has bit many an implementation, due to questions about the
correct-way to stringify an X.500 name.

Recall that the ASN.1 structure for a Name is (roughly):
SEQUENCE  -- RDNSequence
  SET -- RelativeDistinguishedName
    SEQUENCE  -- AttributeTypeAndValue
      OBJECT IDENTIFIER  -- AttributeType
      ANY  -- AttributeValue

Because SEQUENCEs are ordered, but SETs are not, I would expect that the
proper form of any name using a DomainComponent field to follow a meaningful
(hierarchical) ordering. The current language attempts to do so, but in a
way that I think is both wrong and misleading - by suggesting "written last"
- but in fact means *present first* (since there is no agreed upon
stringization)

That is
SEQUENCE  -- RDNSequence
  SET  -- RelativeDistinguishedName
    SEQUENCE
       "0.9.2342.19200300.100.1.25"
       "example"
  SET  -- RelativeDistinguishedName
     SEQUENCE
        "0.9.2342.19200300.100.1.25"
        "mysite"
  SET  -- RelativeDistinguishedName
      SEQUENCE
        "0.9.2342.19200300.100.1.25"
        "test"

For the domain "test.mysite.example"

Suggested wording:
If present, values of this field MUST be structured as followed:
 - Each instance of a RelativeDistinguishedName must contain only a single
AttributeType of domainComponent, OID ....
 - Each RelativeDistinguishedName containing a domainComponent must form an
ordered sequence that is encoded in order of the most significant component,
closest to the root of the namespace, to the least significant component.

Note that I'm trying to eliminate any reference to how it "is written", and
focus solely on how it is encoded.


On the topic of your proposal, I'm confused. Your example of the IGTF
document indicates that the DC portion of the subject indicates "a
responsible community or verifier". That is, it does not indicate the
subject, per-se.

So when verifying the domain according to Section 11.1.1, who is being
contacted, if NOT the Applicant? How does a CA obtain such information? Etc

Additionally, I'm incredibly nervous about such broad language as "the
logical association between the Domain Component field information and the
Certificate's subject". If I did business with a firm at some point in the
past, does that mean they have "a logical association"
with a domain I may operate?

I realize that this is information that browsers do not (or SHOULD not. I
certainly hope no implementations are using it...) use for domain validation
(eg: RFC 6125), but when we talk about the overall SSL ecosystem, such a
proposal would prevent the DC field from ever being useful for any form of
programatic enforcement. Is that acceptable? I'm not sure...
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