[Smcwg-public] Cardinality of subject fields

[Dimitris Zacharopoulos (HARICA)]

Hi Corey,

So, to summarize, the current proposals for multiple values in the 
subjectDN are the following:

 1. OU (probably makes sense to allow multiple instances until we decide
    further actions)
 2. streetAddress (probably makes sense to forbid because of lack of
    support)
 3. organizationIdentifier (probably makes sense to forbid multiple
    instances because of lack of support by Certificate Consumers)

Is this a fair summary?

Dimitris.

On 13/7/2021 11:40 μ.μ., Corey Bonnell via Smcwg-public wrote:
>
> Hi Seb,
>
> Generally, I agree with you that multiple instances of a given 
> attribute type may introduce complexity, although I think for the 
> orgId case, there is value in allowing multiple registration schemes 
> to assist RP software in automated lookups of supplementary 
> information regarding the Subject.
>
> The rationale for including streetAddress as an allowed duplicate 
> attribute type stems solely from historical practice seen in the TLS 
> world. It appears that a common practice was/is to include the street 
> information in one streetAddress RDN and any apartment/suite, etc. 
> information in a subsequent RDN. If we decide that is not desirable 
> for S/MIME, then we can forbid that attribute type from appearing more 
> than once. I don’t have strong feelings either way.
>
> I suppose the cardinality of OU will go alongside the discussion of 
> what we want to do with OU in general; as you mentioned, permitting 
> its presence (or “presences”) in Legacy and Multipurpose but 
> restricting it in Strict may be a viable way of providing a transition 
> path.
>
> Thanks,
>
> Corey
>
> *From:* Sebastian Schulz <sebastian.schulz at globalsign.com>
> *Sent:* Tuesday, July 13, 2021 11:01 AM
> *To:* Corey Bonnell <Corey.Bonnell at digicert.com>; 
> smcwg-public at cabforum.org
> *Subject:* RE: Cardinality of subject fields
>
> Hey Corey, Hey All,
>
> Agreed – would be good to clarify that right off the bat. Is there a 
> reason why multiple instances of the S field should be supported? For 
> the organisational Identifier the different registration schemes are a 
> valid point.
>
> Generally, I’d say that having multiple instances of attributes 
> present significantly complicates validation and increases the risk of 
> the certificate representing outdated information at some point during 
> its validity. But given your argument for OID and the widespread use 
> of multiple OU for all sorts of information it might be yet another 
> case of something we’d want to avoid for “Strict” and allow for other 
> profiles?
>
> Best,
>
> Seb
>
> *Sebastian Schulz*
> /Product Manager Client Certificates/
>
> *From:* Smcwg-public <smcwg-public-bounces at cabforum.org 
> <mailto:smcwg-public-bounces at cabforum.org>> *On Behalf Of *Corey 
> Bonnell via Smcwg-public
> *Sent:* 13 July 2021 15:16
> *To:* SMIME Certificate Working Group <smcwg-public at cabforum.org 
> <mailto:smcwg-public at cabforum.org>>
> *Subject:* [Smcwg-public] Cardinality of subject fields
>
> Hello,
>
> When reviewing the proposed set of allowed/required subject fields for 
> the profiles we have discussed this far, I realized that there is room 
> for better clarity regarding the allowed number of each attribute type 
> that may be present in each subject. For example, the current 
> specification leaves it unclear whether multiple CN attributes may be 
> present in the subject Name. The cardinality of each attribute type is 
> currently left unstated in the TLS BRs, which has led to a lack of 
> clarity and disagreements on the allowed number of various attribute 
> types.
>
> To prevent this confusion and provide concrete written guidance, I 
> suggest that we add a column to the profiles spreadsheet that 
> indicates whether multiple instances of an attribute type are allowed.
>
> To start, I propose that the following attributes be allowed to appear 
> more than once:
>
>   * OU (if we decide to allow its presence at all)
>   * streetAddress
>   * organizationalIdentifier (if different registration schemes are
>     specified)
>
> All other attribute types must not appear more than once in each subject.
>
> Thoughts?
>
> Thanks,
>
> Corey
>
>
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