[cabfpub] Ballot 92 - Subject Alternative Names

Rich Smith richard.smith at comodo.com
Thu Nov 15 21:52:17 UTC 2012

Since many clients and servers will still choke on a cert with no Common Name.  Prohibiting Reserved IPs and Internal host names in the CN field effectively prohibits single site certificates for Reserved IPs and internal names.  What's the reasoning behind this?


From: public-bounces at cabforum.org [mailto:public-bounces at cabforum.org] On Behalf Of Steve Roylance
Sent: Thursday, November 15, 2012 12:28 PM
To: public at cabforum.org; CABForum Management
Subject: [cabfpub] Ballot 92 - Subject Alternative Names




Steve Roylance of GlobalSign made the following motion and Yngve Pettersen of Opera and Jeremy Rowley of Digicert have endorsed it:

... Motion begins...

Effective on the 1st July 2013

... Erratum begins ...

The following sections will be amended in the Baseline Requirements document.

INSERT in Section 4. Definitions the following:

Public IP Address: An IP Address that is not a Reserved IP Address.

REPLACE Section 9.2.1 (Subject Alternative Name Extension) with the following:

9.2.1 Subject Alternative Name Extension

Certificate Field: extensions:subjectAltName

Required/Optional: Required

Contents: This extension MUST contain at least one entry that is either a Fully-Qualified Domain Name or Public IP Address. Each subjectAltName entry MUST either be a Domain Name or an IP Address. The CA MUST confirm the Applicant’s control of each dNSName or Public IP Address entry in accordance with Section 11.1.

SubjectAltName entries MAY include domain Names containing wildcard characters.

If the subjectAltName is:

1) a Public IP Address,

2) a Registered Domain Name that has a Domain Name Registrant different than (and not an Affiliate of) the Domain Name Registrant of any other Registered Domain Name in the subjectAltName extension in the Certificate, or

3) a Reserved IP Address or Internal Server Name.

then the CA MUST verify the identity of an entity that controls the private key in accordance with Section 11.2 and include the Subject Identity Information in the issued Certificate in accordance with 9.2.4. The CA MAY include explanatory information in the Subject Organizational Unit field or a non-subject certificate field to clarify the Subject Identity Information included in the Certificate.

Prior to issuing a Certificate containing an Internal Server Name or Reserved IP Address, the CA SHALL notify the Applicant that the use of such Certificates has been deprecated by the CA / Browser Forum and that the practice will be eliminated by October 2016. As of the Effective Date, the CA SHALL NOT issue a certificate with an Expiry Date later than 1 November 2015 if the subjectAlternativeName contains a Reserved IP Address or Internal Server Name. Effective 1 October 2016, CAs SHALL revoke all unexpired Certificates whose subjectAlternativeName extension or Subject commonName field contains a Reserved IP Address or Internal Server Name.

REPLACE Section 9.2.2 (Subject Common Name Field) with the following:

9.2.2 Subject Common Name Field

Certificate Field: subject:commonName (OID

Required/Optional: Deprecated (Discouraged, but not prohibited)

Contents: If present, this field MUST contain a single Public IP address or single Fully-Qualified Domain Name that is one of the values contained in the Certificate’s subjectAltName extension (see Section 9.2.1). Reserved IP Addresses and Internal Server Names are prohibited.

REPLACE Section 10.2.3 (Information Requirements) with the following:

10.2.3 Information Requirements

The certificate request MAY include all factual information about the Applicant to be included in the Certificate, and such additional information as is necessary for the CA to obtain from the Applicant in order to comply with these Requirements and the CA’s Certificate Policy and/or Certification Practice Statement. In cases where the certificate request does not contain all the necessary information about the Applicant, the CA SHALL obtain the remaining information from the Applicant or, having obtained it from a reliable, independent, third-party data source, confirm it with the Applicant.

Applicant information MUST include, but not be limited to, at least one Subject Alternative Name as defined in Section 9.2.1.

INSERT in Section 11.1 (Authorization by Domain Name Registrant) the following two new sections:

11.1.3 Wildcard Domain Validation

Before issuing a certificate with a wildcard character (*) in a CN or subjectAltName of type DNS-ID, the CA MUST establish and follow a documented procedure† that determines if the wildcard character occurs in the first label position to the left of a “registry-controlled” label or “public suffix” (e.g. “*.com”, “*.co.uk”, see RFC 6454 Section 8.2 for further explanation). If a wildcard would fall within the label immediately to the left of a registry-controlled† or public suffix, CAs SHALL refuse issuance unless the applicant proves its rightful control of the entire Domain Namespace. (e.g. CAs SHALL NOT issue “*.co.uk”, but MAY issue “*.example.co.uk” to Example Ltd.)

†Determination of what is “registry-controlled” versus the registerable portion of a Country Code Top-Level Domain Namespace is not standardized at the time of writing and is not a property of the DNS itself. Current best practice is to consult a “public suffix list” such as  <http://publicsuffix.org/> http://publicsuffix.org/. If the process for making this determination is standardized by an RFC, then such a procedure SHOULD be preferred.

... Erratum ends ...

The review period for this ballot shall commence at 21:00 UTC on 15 November 2012 and will close at 21:00 UTC on 22 November 2012. Unless the motion is withdrawn during the review period, the voting period will start immediately thereafter and will close at 21:00 UTC on 29 November 2012. Votes must be cast by posting an on-list reply to this thread.

... Motions ends ...

A vote in favor of the motion must indicate a clear 'yes' in the response.

A vote against must indicate a clear 'no' in the response. A vote to abstain must indicate a clear 'abstain' in the response. Unclear responses will not be counted. The latest vote received from any representative of a voting member before the close of the voting period will be counted.

Voting members are listed here:  <http://www.cabforum.org/forum.html> http://www.cabforum.org/forum.html

In order for the motion to be adopted, two thirds or more of the votes cast by members in the CA category and one half or more of the votes cast by members in the browser category must be in favor. Also, at least six members must participate in the ballot, either by voting in favor, voting against or abstaining.

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