<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<!--[if !mso]><style>v\:* {behavior:url(#default#VML);}
o\:* {behavior:url(#default#VML);}
w\:* {behavior:url(#default#VML);}
.shape {behavior:url(#default#VML);}
</style><![endif]--><style><!--
/* Font Definitions */
@font-face
{font-family:Wingdings;
panose-1:5 0 0 0 0 0 0 0 0 0;}
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
@font-face
{font-family:Consolas;
panose-1:2 11 6 9 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman",serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p
{mso-style-priority:99;
mso-margin-top-alt:auto;
margin-right:0in;
mso-margin-bottom-alt:auto;
margin-left:0in;
font-size:12.0pt;
font-family:"Times New Roman",serif;}
pre
{mso-style-priority:99;
mso-style-link:"HTML Preformatted Char";
margin:0in;
margin-bottom:.0001pt;
font-size:10.0pt;
font-family:"Courier New";}
p.MsoAcetate, li.MsoAcetate, div.MsoAcetate
{mso-style-priority:99;
mso-style-link:"Balloon Text Char";
margin:0in;
margin-bottom:.0001pt;
font-size:8.0pt;
font-family:"Tahoma",sans-serif;}
p.MsoListParagraph, li.MsoListParagraph, div.MsoListParagraph
{mso-style-priority:34;
margin-top:0in;
margin-right:0in;
margin-bottom:0in;
margin-left:.5in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman",serif;}
span.BalloonTextChar
{mso-style-name:"Balloon Text Char";
mso-style-priority:99;
mso-style-link:"Balloon Text";
font-family:"Tahoma",sans-serif;}
span.EmailStyle20
{mso-style-type:personal;
font-family:"Calibri",sans-serif;
color:#1F497D;}
span.EmailStyle21
{mso-style-type:personal;
font-family:"Calibri",sans-serif;
color:#1F497D;}
span.HTMLPreformattedChar
{mso-style-name:"HTML Preformatted Char";
mso-style-priority:99;
mso-style-link:"HTML Preformatted";
font-family:Consolas;}
span.EmailStyle24
{mso-style-type:personal-reply;
font-family:"Calibri",sans-serif;
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
/* List Definitions */
@list l0
{mso-list-id:408231722;
mso-list-type:hybrid;
mso-list-template-ids:-2003939192 67698689 67698691 67698693 67698689 67698691 67698693 67698689 67698691 67698693;}
@list l0:level1
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;
font-family:Symbol;}
@list l0:level2
{mso-level-number-format:bullet;
mso-level-text:o;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;
font-family:"Courier New";}
@list l0:level3
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;
font-family:Wingdings;}
@list l0:level4
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;
font-family:Symbol;}
@list l0:level5
{mso-level-number-format:bullet;
mso-level-text:o;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;
font-family:"Courier New";}
@list l0:level6
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;
font-family:Wingdings;}
@list l0:level7
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;
font-family:Symbol;}
@list l0:level8
{mso-level-number-format:bullet;
mso-level-text:o;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;
font-family:"Courier New";}
@list l0:level9
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;
font-family:Wingdings;}
ol
{margin-bottom:0in;}
ul
{margin-bottom:0in;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-US" link="blue" vlink="purple">
<div class="WordSection1">
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Hi Kirk,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">I had previously supplied this as a recommended method of validation:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="font-size:11.0pt;font-family:Symbol;color:#1F497D"><span style="mso-list:Ignore">·<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Having the Applicant demonstrate practical control over the FQDN by the Applicant requesting and then installing a Test Certificate issued by the CA
on the FQDN which is accessed and then validated via https by the CA.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">We also added a defined term:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Test Certificate: A Certificate which includes data that renders the Certificate unusable for use by an application software vendor or publicly trusted TLS server
such as the inclusion of a critical extension that is not recognized by any known application software vendor or a certificate issued under a root certificate not subject to these Requirements.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">In this case the “Random Value” is the signature applied by the CA on the test certificate. This could just as well be a signed challenge provided by the web
server and then made available to the CA on the web server. I believe the ACME protocol has something along these lines as well.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">If we think that the current #10 is too generic and we want to break it down, then I suggest we add this back as an approved method of domain validation (it was
listed as item 8 back in February)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Doug<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><a name="_MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></a></p>
<div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> public-bounces@cabforum.org [mailto:public-bounces@cabforum.org]
<b>On Behalf Of </b>kirk_hall@trendmicro.com<br>
<b>Sent:</b> Thursday, May 7, 2015 4:51 PM<br>
<b>To:</b> Tim Hollebeek; Ryan Sleevi<br>
<b>Cc:</b> CABFPub<br>
<b>Subject:</b> Re: [cabfpub] Domain validation<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Well said, Tim. All the other practical demonstration methods (6-9) are effectively “challenge and response” mechanisms involving both the CA and Applicant, and all are pretty
clear as to who, what, where, how – How is the Random Value transmitted to the Applicant, where is the Random Value placed on the Applicant’s website, who does it (for the other methods, it is the Applicant – for method 10?), even what is the exact means by
which the CA verifies the Random Value was placed in the right place.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">For method 10, those specifics are missing. They need to be added or else we can’t evaluate the security of the method – and ambiguity could allow some CAs to misinterpret
and implement an unsecure method.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Here is the current language that needs to be made much more specific (sorry for the haiku format, but it makes it easier to analyze this way):<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt;font-family:"Arial",sans-serif">Having the Applicant demonstrate control over the FQDN
<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt;font-family:"Arial",sans-serif">by providing a TLS service on a host found in DNS for the FQDN
<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt;font-family:"Arial",sans-serif">and having the CA
<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt;font-family:"Arial",sans-serif">(i) initiate a TLS connection with the host and
<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt;font-family:"Arial",sans-serif">(ii) verify a Random Value that is a in a format recognized as a valid TLS response.</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Doug mentioned a different verification method where the CA sends the customer a cert from a private (untrusted) root and asks the customer to install on the FQDN being verified,
then confirms it is there and issues a production cert. Doug – can you write that up as “new” method 9 (as we have no method 3 in the current draft – we can renumber current 4-9 to be 3-8, and insert your new method as method 9)?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></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">public-bounces@cabforum.org</a> [<a href="mailto:public-bounces@cabforum.org">mailto:public-bounces@cabforum.org</a>]
<b>On Behalf Of </b>Tim Hollebeek<br>
<b>Sent:</b> Thursday, May 07, 2015 1:09 PM<br>
<b>To:</b> Ryan Sleevi<br>
<b>Cc:</b> CABFPub<br>
<b>Subject:</b> Re: [cabfpub] Domain validation<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">In the #10 use case Gerv was discussing, the certificates are self-signed, so the TLS-ness doesn’t provide much value, so it doesn’t matter where the TLS terminates.
If we’re going to allow that, I think we should make it explicit what we’re allowing (self-signed or untrusted certificates), and also enforce the .well_known requirement for the same reasons why we did it for #6.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">However, on the validation working group call, another use case was discussed, where validation *<b>does</b>* matter, however the validation is against a non-publicly
trusted root (basically, the web site installs a test cert to prove they control the certs for the domain). It’s an interesting use case that I think should be allowed, though I think it should be a separate enumerated method because the security model is
different.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">I think #10 needs to be tightened up and clarified significantly. I’m sure this will be discussed extensively on the validation WG call in two weeks.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">-Tim<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<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"> Ryan Sleevi [<a href="mailto:sleevi@google.com">mailto:sleevi@google.com</a>]
<br>
<b>Sent:</b> Thursday, May 07, 2015 12:07 PM<br>
<b>To:</b> Tim Hollebeek<br>
<b>Cc:</b> CABFPub; Anoosh Saboori<br>
<b>Subject:</b> RE: [cabfpub] Domain validation<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p><br>
On May 7, 2015 6:47 AM, "Tim Hollebeek" <<a href="mailto:THollebeek@trustwave.com">THollebeek@trustwave.com</a>> wrote:<br>
><br>
> I’ll note that if you object to #6 on those grounds, you also object to #10, which is basically “do #6 via TLS, with fewer requirements around where the value must be placed.”<br>
><br>
> <br>
><br>
> In fact I’m starting to think that #10 should be eliminated and rolled into #6, simply by noting in #6 that for the purposes of #6, TLS with an untrusted server certificate can be used in place of HTTP.<br>
><br>
> <br>
><br>
> -Tim<br>
><o:p></o:p></p>
<p>No Tim, they aren't equivalent under the threat model / equivalency that Anoosh agreed as (part of) the concern.<o:p></o:p></p>
<p>In both the Azure and the AppEngine case, the hosting provider terminates TLS, and thus the tenant cannot influence it.<o:p></o:p></p>
<p>This isn't universal for all hosting scenarios (e.g. Google Compute Engine, AWS), but it does represent a material difference to the threat model that we should not consider them equivalent.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div class="MsoNormal" align="center" style="text-align:center">
<hr size="2" width="100%" align="center">
</div>
<p class="MsoNormal"><span style="font-size:7.5pt;font-family:"Arial",sans-serif;color:gray"><br>
This transmission may contain information that is privileged, confidential, and/or exempt from disclosure under applicable law. If you are not the intended recipient, you are hereby notified that any disclosure, copying, distribution, or use of the information
contained herein (including any reliance thereon) is strictly prohibited. If you received this transmission in error, please immediately contact the sender and destroy the material in its entirety, whether in electronic or hard copy format.</span><o:p></o:p></p>
<table class="MsoNormalTable" border="0" cellspacing="3" cellpadding="0">
<tbody>
<tr>
<td style="background:white;padding:.75pt .75pt .75pt .75pt">
<table class="MsoNormalTable" border="0" cellspacing="3" cellpadding="0">
<tbody>
<tr>
<td style="padding:.75pt .75pt .75pt .75pt">
<pre><o:p> </o:p></pre>
<pre>TREND MICRO EMAIL NOTICE<o:p></o:p></pre>
<pre>The information contained in this email and any attachments is confidential <o:p></o:p></pre>
<pre>and may be subject to copyright or other intellectual property protection. <o:p></o:p></pre>
<pre>If you are not the intended recipient, you are not authorized to use or <o:p></o:p></pre>
<pre>disclose this information, and we request that you notify us by reply mail or<o:p></o:p></pre>
<pre>telephone and delete the original message from your mail system.<o:p></o:p></pre>
</td>
</tr>
</tbody>
</table>
</td>
</tr>
</tbody>
</table>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
</body>
</html>