[cabfpub] Pre-Ballot 125 - CAA Records

Mon Jun 30 15:17:09 UTC 2014

During the CABF discussion about CAA in June 2013, a browser representative pointed out that companies may hit against size constraints when using CAA:

Adding the records increased our authoritative nameserver's DNS response from an already juicy 458 bytes to supreme juicyness of 506 bytes (512 bytes is still somewhat of the limit, at the very least resource usage will increase when topping that). 

And besides, we've seen that before of course, and our TXT SPF record is the main offender here, but 506 byte responses is probably on the "winning" side when it comes to selecting authoritative DNS servers for DNS amplification attacks. Or spoken more generally: Maybe the CABForum should discuss how eager the community is to add a potential massive load of additional records to the root element of a zone/"domain". 

If you use more than one CA for signing "https" certs, this can quickly explode in size all on itself, without the help of SPF entries in the zone. I'd guess this needs to be discussed. 

The technical discussion dropped off at this point.  I believe it bears further analysis. 

Best, Stephen

From: Doug Beattie [mailto:doug.beattie at globalsign.com] 
Sent: Friday, June 27, 2014 4:26 PM
To: Stephen Davidson; 'Ryan Sleevi'
Cc: 'cabfpub'
Subject: RE: [cabfpub] Pre-Ballot 125 - CAA Records

Agree, thanks for stating that so clearly.

Doug

From: Stephen Davidson [mailto:S.Davidson at quovadisglobal.com] 
Sent: Friday, June 27, 2014 3:22 PM
To: Ryan Sleevi; Doug Beattie
Cc: cabfpub
Subject: RE: [cabfpub] Pre-Ballot 125 - CAA Records

The alternative ballot inserts CAA checking in the Section 7.1.2 list of MUSTs.  Section 7.1.3 amends it to say CAs can document a policy on how they interpret the record.  

But bottom line is that the alternative ballot calls for an auditable technical implementation of CAA within 6 months.

From: public-bounces at cabforum.org [mailto:public-bounces at cabforum.org] On Behalf Of Ryan Sleevi
Sent: Friday, June 27, 2014 4:01 PM
To: Doug Beattie
Cc: cabfpub
Subject: Re: [cabfpub] Pre-Ballot 125 - CAA Records

Hi Doug,

I'm trying to understand a bit of the concern as well. I don't see the proposed amendment as requiring that a CA support CAA, merely setting forth what "CAA support" would look like. That is, a CA's procedures for CAA records (2.i) might be "The records are ignored"

For "CAA support" to be meaningful, we at least need a common set of policies related to what it means to "check CAA", much in the same way we have policies established related to the validation of domain information or identity verification.

The ballot, as proposed, still allows CAs to say that they're ignored, but merely establishes a consistent criteria for what it means to ignore/support CAA.

For example, we wouldn't want to see a certificate with 3 domain names, where CAA is only checked for the first domain name. That provides little assurances for subscribers wishing to employ CAA.

On Fri, Jun 27, 2014 at 11:42 AM, Doug Beattie <doug.beattie at globalsign.com> wrote:

Hi Ben,

We liked your original ballot, before you added this section:

Amend subparagraph 2 of 7.1.2 to read as follows: 

 2.  Authorization for Certificate:  That, at the time of issuance, the CA (i) implemented procedures for verifying that the Subject authorized the issuance of the Certificate, including procedures to (a) consider the CAA record of each Domain Name to be listed in the Certificate’s subject field or subjectAltName extension, and (b) to establish that the Applicant Representative is authorized to request the Certificate on behalf of the Subject; (ii) followed the procedures when issuing the Certificate; and (iii) accurately described the procedures in the CA’s Certificate Policy and/or Certification Practices Statement;

From: Ben Wilson [mailto:ben at digicert.com] 
Sent: Friday, June 27, 2014 2:39 PM
To: 'Doug Beattie'; 'cabfpub'
Subject: RE: [cabfpub] Pre-Ballot 125 - CAA Records

Doug,

Could you re-state in its entirety what you’d like to see?  I’m not following.

Thanks,

Ben

From: public-bounces at cabforum.org [mailto:public-bounces at cabforum.org] On Behalf Of Doug Beattie
Sent: Friday, June 27, 2014 11:43 AM
To: 'Ben Wilson'; 'cabfpub'
Subject: Re: [cabfpub] Pre-Ballot 125 - CAA Records

Hi Ben,

We can support the ballot you first drafted, but we have issues with the recent amendment in subparagraph 2 of 7.1.2.  That is not consistent with the goal of this ballot (have CAs publically disclose if/how they process CAA records in the CPS) as there are some statements that go beyond that regarding “implementing procedures…”.  That should be removed from this ballot.

Doug

From: public-bounces at cabforum.org [mailto:public-bounces at cabforum.org] On Behalf Of Ben Wilson
Sent: Friday, June 27, 2014 12:14 PM
To: 'Rick Andrews'; 'cabfpub'
Subject: [cabfpub] Pre-Ballot 125 - CAA Records

Rick,

Here are the alternative provisions for you to look at and choose from.

Ben

Pre-Ballot 125 - CAA Records 

Rick Andrews of Symantec made the following motion and Jeremy Rowley of Digicert and Ryan Sleevi of Google have endorsed it: 

Reasons for proposed ballot RFC 6844 defines a Certification Authority Authorization DNS Resource Record (CAA). A CAA allows a DNS domain name holder to specify the CAs authorized to issue certificates for that domain. Publication of the CAA allows a public Certification Authority to implement additional controls to reduce the risk of unintended certificate mis-issuance. 

The proponents of this ballot believe that this proposed modification to the Baseline Requirements, which gives CAs up to six months to update their CP and/or CPS to state the degree to which they implement CAA, provides all CAs with the flexibility needed to begin implementation of CAA. 

---MOTION BEGINS--- 

Add to Section 4 Definitions, new item: 

CAA: From RFC 6844 (http:tools.ietf.org/html/rfc6844 <http://tools.ietf.org/html/rfc6844> ): “The Certification Authority Authorization (CAA) DNS Resource Record allows a DNS domain name holder to specify the Certification Authorities (CAs) authorized to issue certificates for that domain. Publication of CAA Resource Records allows a public Certification Authority to implement additional controls to reduce the risk of unintended certificate mis-issue.” 

Amend subparagraph 2 of 7.1.2 to read as follows: 

 2.  Authorization for Certificate:  That, at the time of issuance, the CA (i) implemented procedures for verifying that the Subject authorized the issuance of the Certificate, including procedures to (a) consider the CAA record of each Domain Name to be listed in the Certificate’s subject field or subjectAltName extension, and (b) to establish that the Applicant Representative is authorized to request the Certificate on behalf of the Subject; (ii) followed the procedures when issuing the Certificate; and (iii) accurately described the procedures in the CA’s Certificate Policy and/or Certification Practices Statement;

Add a new section 7.1.3 CAA Disclosure as follows:

Effective as of [insert date that is six months from Ballot 125 adoption], Section 4.2 of the CA’s Certificate Policy or Certification Practice Statement SHALL set forth the CA’s policy regarding its procedures for considering CAA records for Domain Names to be listed in the Certificate’s subject field or subjectAltName extension.  

Add a new sentence to the end of Section 8.2.2, Disclosure, as follows: 

Effective as of [insert date that is six months from Ballot 125 adoption], section 4.2 of a CA's Certificate Policy and/or Certification Practice shall disclose the CA's policy and/or practices on processing CAA records. 

The resulting Section 8.2.2 would read as follows:

The CA SHALL publicly disclose its Certificate Policy and/or Certification Practice Statement through an appropriate and readily accessible online means that is available on a 24x7 basis. The CA SHALL publicly disclose its CA business practices to the extent required by the CA’s selected audit scheme (see Section 17.1). The disclosures MUST include all the material required by RFC 2527 or RFC 3647, and MUST be structured in accordance with either RFC 2527 or RFC 3647.  Effective as of [insert date that is six months from Ballot 125 adoption], section 4.2 of a CA's Certificate Policy and/or Certification Practice Statement shall disclose the CA's policy and/or practices on processing CAA records.

---MOTION ENDS---

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