[cabfpub] Ballot 208 - dnQualifiers

Mon Oct 23 15:02:49 UTC 2017

What about using serialNumber (2.5.4.5)?

     Li-Chun Chen 

From: Ryan Sleevi [mailto:sleevi at google.com] 
Sent: Monday, October 23, 2017 9:54 PM
To: 陳立群
Cc: Geoff Keating; CA/Browser Forum Public Discussion List
Subject: [外部郵件] Re: [cabfpub] Ballot 208 - dnQualifiers

Given that the naming authority is the DNS, and two entities with the same 64 character prefix domain would be equivalent, it does not seem at all incorrect or imprecise to include this information in the dnQualifier.

Hopefully we can find a solution other than "Don't have long domains because the commonName" - a field deprecated nearly two decades ago.

On Sun, Oct 22, 2017 at 10:41 AM, 陳立群 <realsky at cht.com.tw> wrote:

I would like to second Geoff's opinion about the dnQualifier attribute. In the ITU-T X.520 standard, the definition of the dnQualifier attribute is as the following:

The DN Qualifier attribute type specifies disambiguating information to add to the relative distinguished name of an entry. It is intended to be used for entries held in multiple DSAs which would otherwise have the same name, and that its value be the same in a given DSA for all entries to which this information has been added.

From what I understand, the dnQualifier attribute is intended to distinguish two different entities which would otherwise have the same DN if they are named by different DSAs (or naming authorities). Therefore, the attribute value of the dnQualifier is usually used to indicate the name of the DSA which is in charge of naming the entity.

If we use the dnQualifier attribute in the manner proposed this ballot, that will be a distortion on its original definition in the X.520 standard.

         Li-Chun Chen

        Chunghwa Telecom

From: Public [mailto:public-bounces at cabforum.org] On Behalf Of Geoff Keating via Public
Sent: Saturday, October 21, 2017 3:15 AM
To: Ryan Sleevi
Cc: CA/Browser Forum Public Discussion List
Subject: [外部郵件] Re: [cabfpub] Ballot 208 - dnQualifiers

On Oct 20, 2017, at 11:30 AM, Ryan Sleevi <sleevi at google.com> wrote:

On Fri, Oct 20, 2017 at 2:20 PM, Geoff Keating via Public <public at cabforum.org> wrote:

- How this matches with the X.520 definition of dnQualifier, in particular the second sentence:

The DN Qualifier attribute type specifies disambiguating information to add to the relative distinguished name of an entry. It is intended to be used for entries held in multiple DSAs which would otherwise have the same name, and that its value be the same in a given DSA for all entries to which this information has been added.

This matches 1:1. Is there a concern that it doesn't match, or that more rules are necessary?

What I quoted above is X.520.  It doesn't seem to me to be describing the same thing as the ballot.  In particular, normally you would consider a CA’s issuing infrastructure to be one single DSA, which produces a contradiction between the ballot text "The CA MAY set the dnQualifer value to the base64 encoding of the SHA1 hash of the subjectAlternativeName” and X.520’s text “its value be the same in a given DSA”.

- How this is actually intended to be used in the web PKI?

As raised on our most recent call, one notable thing is that this allows CAs to issue single certificates for domain names greater than 64 characters, at a DV level, while interoperably working with the Web PKI. This flows as follows:

- The X.509/RFC 5280 definition for commonName is limited to 64 characters.

- If you have a certificate with a domain name greater than 64 characters, you cannot place it in the common name of the subject.

- The common name of the subject may only contain domain names and IP addresses.

- All other specified fields of the Subject must be validated to OV level.

As a consequence, the only way with DV today to represent these certificates is with an empty sequence for the subject name and a critical subjectAltName, pursuant with RFC5280. You can see this at https://no-subject.badssl.com

If you tried to load that on Apple iOS, it would load.

If you tried to load that on Apple macOS earlier than 10.10, it would load.

If you tried to load that on Apple macOS since 10.10, it will fail, as empty subjects are no longer supported.

It works for me in 10.11—so does that mean this ballot is no longer needed?

This provides a way for a CA to ensure that a DV certificate with a domain name of more than 64 characters can be issued, by using the dnQualifier field (which is CA-controlled, as noted in the relevant X.520 text you cited) to serve as a disambiguator between certificates the CA has issued.

Does that help capture it?

I see the problem but I’m very hesitant to standardise something in CABforum which contradicts X.520.

Have we really explored other alternatives?  For example, truncate the commonName to 60 characters and append an ellipsis in Unicode (“…”) so that it can’t be confused with a domain name.

On Oct 12, 2017, at 11:04 AM, Ben Wilson via Public <public at cabforum.org> wrote:

Ballot 208 - dnQualifiers

This ballot allows CAs to use dnQualifiers in certificates to partition groups of certificates into different sets and to allow non-identity information to be included in DV certificates. 

The following motion has been proposed by Peter Bowen of Amazon and endorsed by Ben Wilson of DigiCert and Ryan Sleevi of Google. 

-- MOTION BEGINS -- 

In the Baseline Requirements, REPLACE the definition of "Subject Identity Information" with: 

"Information that identifies the Certificate Subject. Subject Identity Information does not include [strikeout]a domain name listed in the subjectAltName extension or the Subject commonName field[/strikeout] [insert]dnQualifier attributes in Distinguished Names, commonName attributes in Distinguished Names, dNSName Subject Alternative Names, iPAddress Subject Alternative Names, or SRVName Subject Alternative Names[/insert]." 

In Section 7.1.4.2.2 Subject Distinguished Name Fields, re-letter "j" (Other Subject Attributes) as letter "k" and INSERT a new subsection j. that reads: 

j. Certificate Field: subject:dnQualifier 

*	Optional. Contents: This field is intended to be used when several certificates with the same subject can be partitioned into sets of related certificates. Each related certificate set MAY have the same dnQualifier. The CA may include a dnQualifier attribute with a zero length value to explicitly indicate that the CA makes no assertion about relationship with other certificates with the same subject. The CA MAY set the dnQualifer value to the base64 encoding of the SHA1 hash of the subjectAlternativeName extnValue if it wishes to indicate grouping of certificates by alternative name set. 

-- MOTION ENDS -- 

The procedure for approval of this Final Maintenance Guideline ballot is as follows (exact start and end times may be adjusted to comply with applicable Bylaws and IPR Agreement): 

BALLOT 208 Status: Final Maintenance Guideline Start time (22:00 UTC) End time (22:00 UTC) 

Discussion begins October 12, 2017 22:00 UTC and ends October 19, 2017 22:00 UTC (7 days) 

Vote for approval begins October 19, 2017 22:00 UTC and ends October 26, 2017 22:00 UTC (7 days) 

If vote approves ballot: Review Period (Chair to send Review Notice) (30 days). If Exclusion Notice(s) filed, ballot approval is rescinded and PAG to be created. If no Exclusion Notices filed, ballot becomes effective at end of Review Period. Upon filing of Review Notice by Chair 30 days after filing of Review Notice by Chair 

From Bylaw 2.3: If the Draft Guideline Ballot is proposing a Final Maintenance Guideline, such ballot will include a redline or comparison showing the set of changes from the Final Guideline section(s) intended to become a Final Maintenance Guideline, and need not include a copy of the full set of guidelines. Such redline or comparison shall be made against the Final Guideline section(s) as they exist at the time a ballot is proposed, and need not take into consideration other ballots that may be proposed subsequently, except as provided in Bylaw Section 2.3(j). 

Votes must be cast by posting an on-list reply to this thread on the Public list. 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:  <https://cabforum.org/members/> https://cabforum.org/members/

In order for the motion to be adopted, two thirds or more of the votes cast by members in the CA category and greater than 50% of the votes cast by members in the browser category must be in favor. Quorum is shown on CA/Browser Forum wiki. Under Bylaw 2.2(g), at least the required quorum number must participate in the ballot for the ballot to be valid, either by voting in favor, voting against, or abstaining. 

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