[Servercert-wg] [EXTERNAL] Ballot SC12 - Sunset of Underscores in dNSNames

Bruce Morton Bruce.Morton at entrustdatacard.com
Fri Nov 9 08:15:30 MST 2018

Entrust votes No to ballot SC12.

We do agree that the issue for use of underscores needs to be resolved as to whether they are allowed or not allowed. However, this ballot does not address whether underscores can be used. The ballot assumes that underscores are not required. The ballot does not address the threat, nor does it justify the urgency to remove underscores. The urgency of removing underscores by decreasing validity period and revocation, does not give Subscribers sufficient time to change how they deploy their certificates.


From: Servercert-wg [mailto:servercert-wg-bounces at cabforum.org] On Behalf Of Wayne Thayer via Servercert-wg
Sent: November 2, 2018 6:11 PM
To: CA/B Forum Server Certificate WG Public Discussion List <servercert-wg at cabforum.org>
Subject: [EXTERNAL][Servercert-wg] Ballot SC12 - Sunset of Underscores in dNSNames

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This begins the voting period for Ballot SC12 - Sunset of Underscores in dNSNames

Purpose of Ballot

Ballot 202 included a provision creating a permanent exception permitting the underscore character to be used in SAN fields of type dNSName. Since that ballot failed in 2017, the practice has continued despite being non-compliant with RFC 5280. This ballot creates a brief sunset period intended to allow Subscribers who are relying on FQDNs containing underscores to transition away from them, either by changing the name or deploying a wildcard certificate.

The following motion has been proposed by Wayne Thayer of Mozilla and endorsed by Dave Blunt of Amazon and Tim Shirley of Trustwave.

Add the following language to BR section (Subject Alternative Name Extension):

Prior to April 1, 2019, certificates containing underscore characters (“_”) in domain labels in dNSName entries MAY be issued as follows:
* dNSName entries MAY include underscore characters such that replacing all underscore characters with hyphen characters (“-“) would result in a valid domain label, and;
* Underscore characters MUST NOT be placed in the left most domain label, and;
* Such certificates MUST NOT be valid for longer than 30 days.

All certificates containing an underscore character in any dNSName entry and having a validity period of more than 30 days MUST be revoked prior to January 15, 2019.

After April 30, 2019, underscore characters (“_”) MUST NOT be present in dNSName entries.


This ballot proposes a Final Maintenance Guideline. A comparison of the changes can be found at: https://github.com/wthayer/documents/compare/master...wthayer:Underscores<https://github.com/wthayer/documents/commit/9926d75d0b9a1969034a25864741eae4421a51e5>

The procedure for approval of this ballot is as follows:

Discussion (7-21 days)
Start Time: 2018-10-26, 19:00 UTC
End Time: 2018-11-02, 22:00 UTC

Vote for approval (7 days)
Start Time: 2018-11-02, 22:00 UTC
End Time: 2018-11-09, 22:00 UTC
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