[Smcwg-public] Common Name contents

Stephen Davidson Stephen.Davidson at digicert.com
Wed Mar 2 17:43:35 UTC 2022

Hi Doug:

1. Further to our discussion today, the language in ETSI EN 319 412-2 probably has the clearest definition:

The commonName attribute value shall contain a name of the subject. This may be in the subject's preferred presentation format, or a format preferred by the CA, or some other format. Pseudonyms, nicknames, and names with spelling other than defined by the registered name may be used.

NOTE 1: The commonName attribute has a usage purpose that is different from the required choice of pseudonym or givenName/surname. commonName is used for user friendly representation of the person's name, whereas givenName/surname is used where more formal representation or verification of specific identity of the user is required. To maximize interoperability both are considered necessary.

It does not give guidance on the scope for "user friendly representation of the person's name" and as far as I can tell, most TSPs apply either (givenName and surname) or pseudonym in that field.

Notwithstanding this, our previous discussions had been for the commonName to include verified information for the purposes of the S/MIME BR, leading to the options described here<https://github.com/cabforum/smime/blob/preSBR/SBR.md#71422-subject-distinguished-name-fields>.

We are interested in hearing perspectives from both Certificate Issuers and Certificate Issuers on this point.

2.  The handling of subject:pseudonym is still an unresolved issue - and so text still needs to be tightened up. We are working from the basis that Subject information must be verified, so this would also apply to pseudonym (ie not a self reported name). Pseudonym identity is, by definition, linked to the person's real identity

ETSI TS 199 461 tries to deal with it by saying:

Although the outcome of the identity proofing can be a pseudonym identity, identity proofing requires identification of the real identity of the person as determined by applicable identity documents, official registers or other authoritative sources.

But as far as I can tell, only Germany provides pseudonym as an information attribute on official identity documents.  Given the lack of clarity, we could even chose to exclude this attribute from the allowed profiles.

We'd be interested to hear from Certificate Issuers what their practices are using the pseudonym in regulated certificate types.

Best, Stephen

Stephen Davidson

DigiCert Governance, Risk & Compliance
stephen.davidson at digicert.com

O 1.441.278.2803 | M 1.441.505.4908

From: Doug Beattie <doug.beattie at globalsign.com>
Sent: Wednesday, March 2, 2022 1:10 PM
To: Stephen Davidson <Stephen.Davidson at digicert.com>; SMIME Certificate Working Group <smcwg-public at cabforum.org>
Subject: Common Name contents

Hey Stephen,

During the call today it was mentioned that all of the subject info pulled from the certificates and displayed via GUI needs to be validated (no more OU logic). I went back and looked at the options for Sponsor validated certs and it permits the Pseudonym to be present in the CN.

I went to check the rules for validation and found this:

f. Certificate Field: subject:pseudonym (
Contents: The pseudonym attribute MUST NOT be present if the givenName and/or surname attribute are present. If present, the subject:pseudonym field field MUST be verified according to Section 3.2.3<https://github.com/cabforum/smime/blob/preSBR/SBR.md#323-authentication-of-individual-identity>.

But I could not find any references to this field in that section, or section 3.2.4 that indicates how this is to be validated.  Are there CA validation rules for this, or can any value be supplied?


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