<div dir="ltr">Thanks Rick.<div><br></div><div>I have no particular preferences regarding that last sentence - but agree, it sounds good. The first sentence makes it clear in (iii) that it has to be documented, which is the main goal.</div>
<div><br></div><div>The only modification I would suggest would be that you remove "IP Addresses" from (i), since you only have CAA for Domain Names (as mentioned in the text you quoted from 6844)</div></div><div class="gmail_extra">
<br><br><div class="gmail_quote">On Thu, May 1, 2014 at 3:26 PM, Rick Andrews <span dir="ltr"><<a href="mailto:Rick_Andrews@symantec.com" target="_blank">Rick_Andrews@symantec.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>
<font face="Calibri, sans-serif">
<div>I’m attaching Phillip’s original proposal for CAA and Jeremy’s suggestion for enhancement. Here’s my proposal.</div>
<div> </div>
<div> </div>
<div> </div>
<div>Add to Section 4 Definitions, new item:</div>
<div> </div>
<div><b>CAA</b>: From RFC 6844 (<a href="http:tools.ietf.org/html/rfc6844):" target="_blank">http:tools.ietf.org/html/rfc6844):</a> “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.”</div>
<div> </div>
<div>Add to Section 7.1.2 Certificate Warranties, new item:</div>
<div> </div>
<div> 9. <b>CAA</b>: That, at the time of issuance, the CA (i) implemented a procedure for consideration of CAA records for each Domain Name(s) and IP address(es) listed in the Certificate’s subject field and subjectAltName extension; (ii) followed the
procedure when issuing the Certificate; and (iii) accurately described the procedure in the CA’s Certificate Policy and/or Certification Practice Statement. It is permissible (although not desirable) for the CA to ignore CAA records completely, as long as that
“procedure” is documented in the CA’s Certificate Policy and/or Certification Practice Statement. If the CA’s Certificate Policy and/or Certification Practice Statement is based on RFC 3647, the statement describing the CA’s CAA procedure SHOULD appear in Section
4.4.2. Certificate Application Processing.</div>
<div> </div>
<div>(I defer to Tom and Ryan S on that last sentence. You read many more CPs and CPSs than I do.</div><span class="HOEnZb"><font color="#888888">
<div> </div>
<div>-Rick</div>
<div> </div>
</font></span></font>
</div>
<br><br>---------- Forwarded message ----------<br>From: Jeremy Rowley <<a href="mailto:jeremy.rowley@digicert.com">jeremy.rowley@digicert.com</a>><br>To: 'Phillip' <<a href="mailto:philliph@comodo.com">philliph@comodo.com</a>>, "<a href="mailto:public@cabforum.org">public@cabforum.org</a>" <<a href="mailto:public@cabforum.org">public@cabforum.org</a>><br>
Cc: <br>Date: Fri, 7 Jun 2013 14:32:44 -0700<br>Subject: Re: [cabfpub] CAA Proposal<br>
<div lang="EN-US" link="blue" vlink="purple">
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Although I am starting to like the concept of CAA, I think this is an improper way to implement a CAA requirement. If a CA already has rigorous validation
practices and can accurately identify the request as originating from the proper entity, I’m not sure that additional checks are necessary.
<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">If we plan to implement CAA in the Forum, we should develop a discernible standard that can be used to measure compliance. In fact, perhaps the RFC should
be revised prior to the Forum’s adoption to identify what additional verification requirements should be considered necessary before issuance of a certificate. That way the Forum has a basis for setting the additional checks and CAs will have a better understanding
of how to comply.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Jeremy<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<div>
<div style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> <a href="mailto:public-bounces@cabforum.org" target="_blank">public-bounces@cabforum.org</a> [mailto:<a href="mailto:public-bounces@cabforum.org" target="_blank">public-bounces@cabforum.org</a>]
<b>On Behalf Of </b>Phillip<br>
<b>Sent:</b> Friday, June 07, 2013 10:10 AM<br>
<b>To:</b> <a href="mailto:public@cabforum.org" target="_blank">public@cabforum.org</a><br>
<b>Subject:</b> [cabfpub] CAA Proposal<u></u><u></u></span></p>
</div>
</div>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Following up on the CAA threads, I would like to propose the following (subject to discussion):<u></u><u></u></p>
<div>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
<div>
<p class="MsoNormal">1) CABForum endorse the publication of CAA records by domain name owners to mitigate the risk of issue of certificates in response to an unauthorized or fraudulent request.<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
<div>
<p class="MsoNormal">2) The Basic requirements be updated to add a requirement that CAs state their policy for use of CAA records in their CPS.<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
<div>
<p class="MsoNormal">"A CA MUST state its policy for processing CAA records as defined in RFC 6844"<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
<div>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
<div>
<p class="MsoNormal">Rationale: <u></u><u></u></p>
</div>
<div>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
<div>
<p class="MsoNormal"><a href="http://tools.ietf.org/html/rfc6844" target="_blank">http://tools.ietf.org/html/rfc6844</a><u></u><u></u></p>
</div>
<div>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
<div>
<p class="MsoNormal">To be compliant with the RFC, a CA MUST comply with the requirements of section 4:<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
<div>
<pre style="text-align:start;word-spacing:0px"><span style="font-size:12.0pt;color:black">Before issuing a certificate, a compliant CA MUST check for<u></u><u></u></span></pre>
<pre><span style="font-size:12.0pt;color:black"> publication of a relevant CAA Resource Record set. If such a record<u></u><u></u></span></pre>
<pre><span style="font-size:12.0pt;color:black"> set exists, a CA MUST NOT issue a certificate unless the CA<u></u><u></u></span></pre>
<pre><span style="font-size:12.0pt;color:black"> determines that either (1) the certificate request is consistent with<u></u><u></u></span></pre>
<pre><span style="font-size:12.0pt;color:black"> the applicable CAA Resource Record set or (2) an exception specified<u></u><u></u></span></pre>
<pre><span style="font-size:12.0pt;color:black"> in the relevant Certificate Policy or Certification Practices<u></u><u></u></span></pre>
<pre><span style="font-size:12.0pt;color:black"> Statement applies.<u></u><u></u></span></pre>
<div>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
</div>
<div>
<p class="MsoNormal">A CA can be minimally compliant with the specification by simply publishing a statement that says that they retrieve and process CAA records for each request and then grant an automatic exception in every case.<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
<div>
<p class="MsoNormal">This is deliberate because there is a peculiar edge case in which the Domain Name owner does not control their DNS publication infrastructure and the party that does inserts a spurious CAA record to limit competition. It also avoided the
need for theological debates on what is and is not a public delegation point.<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
<div>
<p class="MsoNormal">The point of CAA is to benefit CAs by reducing the cost of detecting potential fraudulent applications and mitigating the risk of issuing a certificate. But as with any other validation check, the response to a request that is non-consistent
is not going to be to kick the request back to manual processing. There is going to be a person in the loop making enquiries. Either the CAA record is spurious and the CA wants to get it changed so that they can take the business or they have just detected
an unauthorized request which they are going to want to look at an analyze and study.<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
<div>
<p class="MsoNormal">A CA could write a CPS statement that says they look at CAA records and then ignore them completely but that would not look good. I think it rather more likely that it would say something like they have some sort of process for determining
that CAA records do not represent the intention of the Domain Owner and publish a list of domains they will ignore CAA records from. This might include top-level domains like .com etc. But the fact that CAs have the option of ignoring the CAA records is probably
sufficient to deter an attack.<u></u><u></u></p>
</div>
</div>
</div>
<br>_______________________________________________<br>
Public mailing list<br>
<a href="mailto:Public@cabforum.org">Public@cabforum.org</a><br>
<a href="https://cabforum.org/mailman/listinfo/public" target="_blank">https://cabforum.org/mailman/listinfo/public</a><br>
<br></blockquote></div><br></div>