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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">If “critical” is still an issue then the sunset date will devalue the enterprise CAs that use Name Constraints while the public CAs will continue on with no
Name Constraints. This might not be a good solution for the constrained CAs.<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">Bruce.<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>
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<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""> public-bounces@cabforum.org [mailto:public-bounces@cabforum.org]
<b>On Behalf Of </b>Rich Smith<br>
<b>Sent:</b> Friday, May 25, 2012 1:45 PM<br>
<b>To:</b> '</span><span lang="JA" style="font-size:10.0pt">王瘢雹文正</span><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">'; 'Rob Stradling'<br>
<b>Cc:</b> public@cabforum.org<br>
<b>Subject:</b> Re: [cabfpub] More changes to proposed policy update<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">How about, as a compromise solution, we implement non-critical with a specific sunset date, at which time implementations must be changed to critical, and we
break with precedent and add in that by that sunset date all browser/client vendors who are members of the Forum will be expected to have updated to fully support name constraints in RFC5280 compliant fashion?<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">-Rich<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>
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<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:[mailto:public-bounces@cabforum.org]">
[mailto:public-bounces@cabforum.org]</a> <b>On Behalf Of </b>???<br>
<b>Sent:</b> Friday, May 25, 2012 1:33 PM<br>
<b>To:</b> Rob Stradling<br>
<b>Cc:</b> <a href="mailto:public@cabforum.org">public@cabforum.org</a><br>
<b>Subject:</b> Re: [cabfpub] More changes to proposed policy update<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Rob,<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Times New Roman","serif""> </span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Times New Roman","serif"">Believe it or not. Even the Name Constraints extension is marked non-critical, there still exist dumb clients that will explode when encountering it.</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Times New Roman","serif"">Dumb clients might explode simply because they never saw this kind of extensions rather than because they are marked critical.</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Times New Roman","serif"">In that situations, what can you do?</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Times New Roman","serif""> </span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Times New Roman","serif"">Currently, if major browsers/operating systems all can live peacefully with "Critical" Name Constraints extensions, why bother making the BR inconsistent with RFC5280?</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Times New Roman","serif""> </span><o:p></o:p></p>
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<p class="MsoNormal">Wen-Cheng Wang<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Times New Roman","serif""> </span><o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><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""> Rob Stradling [rob.stradling@comodo.com]<br>
<b>Sent:</b> Friday, May 25, 2012 9:56 PM<br>
<b>To:</b> </span><span lang="JA" style="font-size:10.0pt">王瘢雹文正</span><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""><br>
<b>Cc:</b> Ryan Hurst; Steve Roylance; 'Chris Palmer'; <a href="mailto:public@cabforum.org">
public@cabforum.org</a><br>
<b>Subject:</b> Re: [cabfpub] More changes to proposed policy update</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.0pt">On 25/05/12 14:41, <span lang="JA">
王瘢雹文正</span> wrote:<br>
<snip><br>
</span><span style="font-size:10.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:10.0pt">> On the contrary, I think marking the Name Constraints extension<br>
</span><span style="font-size:10.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:10.0pt">> critical is the way to provide the motive power. If dumb clients<br>
</span><span style="font-size:10.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:10.0pt">> explode, their users will ask the implementers to support it.<br>
<br>
I don't think that that is what would happen.</span><span style="font-size:10.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:10.0pt"> I think the actual
<br>
scenario would be closer to this...<br>
<br>
Dumb client explodes when encountering a Critical Name Constraints <br>
extension.</span><span style="font-size:10.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:10.0pt"> User complains to the Certificate Holder that the
<br>
certificate is broken.</span><span style="font-size:10.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:10.0pt"> Certificate Holder complains to the CA.</span><span style="font-size:10.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:10.0pt">
CA <br>
blames the dumb client software, but neither the Certificate Holder nor <br>
the User accepts this explanation (even though the explanation is <br>
correct!)</span><span style="font-size:10.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:10.0pt"> Certificate Holder asks for a refund and then obtains a new
<br>
certificate from a different CA that doesn't use the Name Constraints <br>
extension.</span><span style="font-size:10.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:10.0pt"> Very quickly every CA realizes that it is not commercially
<br>
viable to use Critical Name Constraints.</span><span style="font-size:10.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:10.0pt"> Back to square one.<br>
<br>
On 25/05/12 14:41, <span lang="JA">王瘢雹文正</span> wrote:<br>
> Dear Rob, Steve, Ryan and Chris,<br>
><br>
> Thank you all for your patience in explain your logic.<br>
><br>
> Now I understand your rationale goes like this: If we turn the Name Constraints extension into an 'informative' extension first by marking it non-critical, hopefully it will become a real constraint-type extension in the end.<br>
><br>
> Making it as an informative extension is better than nothing. Maybe you are right. However, my guess is it will stay as an informative extension forever. I do not believe allowing the non-critical Name Constraints extension can help pushing the world to reach
the desired end state (I mean all clients become supporting the critical Name Constraints extension.). Since it is non-critical, it will not provide the motive power to push those dumb clients to change themselves because they can simply ignore it. On the
contrary, I think marking the Name Constraints extension critical is the way to provide the motive power. If dumb clients explode, their users will ask the implementers to support it. Otherwise, the users will switch to more smart clients. I do understand
that if we goes this way, the process to reach the desired end state might be bloody. If your goal is to reach the desired end state, this is the way that can really accelerate the process.<br>
><br>
> If the forum finally decide to approve the motion of allowing non-critical Name Constraints extension, then we should ask ourselves a question: when will we turn back to change the BR to require marking the Name Constraints extension as critical? Until 100%
of clients become smart? Or 95% (whatever) is acceptable? Can we really reach the so-called "desired end state" in this way?<br>
><br>
> Wen-Cheng Wang<br>
><br>
> -----Original Message-----<br>
> From: Rob Stradling [<a href="mailto:rob.stradling@comodo.com" target="_blank">mailto:rob.stradling@comodo.com</a>]<br>
> Sent: Friday, May 25, 2012 7:12 PM<br>
> To: <span lang="JA">王瘢雹文正</span><br>
> Cc: Ryan Hurst; 'Chris Palmer'; <a href="mailto:public@cabforum.org">public@cabforum.org</a><br>
> Subject: Re: [cabfpub] More changes to proposed policy update<br>
><br>
> On 25/05/12 11:43, <span lang="JA">王瘢雹文正</span> wrote:<br>
>> I do not get the logic here.<br>
><br>
> I think Ryan's post explained the logic clearly and succinctly.<br>
><br>
> You're looking only at the "desired end state".</span><span style="font-size:10.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:10.0pt"> Please consider the "transition problem".<br>
><br>
> Security versus Usability.</span><span style="font-size:10.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:10.0pt"> If we can't ever Use it in practice, we won't ever benefit from the Security it offers.<br>
><br>
> Today, Critical Name Constraints are considered undeployable by many CAs, because too much relying party software would break.</span><span style="font-size:10.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:10.0pt"> Therefore, using
the Name Constraints extension _at all_ is not an option for us.<br>
><br>
> Non-critical Name Constraints are better than No Name Constraints!<br>
><br>
> The "desired end state" is...<br>
> 1. Name Constraints always Critical.<br>
> 2. Name Constraints actually used!<br>
><br>
> If you can suggest an alternative way to solve the "transition problem"<br>
> so that we can reach the "desired end state", we would love to hear it!<br>
><br>
> Nobody is suggesting that CAs should be prohibited from setting the Name Constraints extension to Critical.</span><span style="font-size:10.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:10.0pt"> All we are saying is that CAs should
be allowed to use non-critical Name Constraints instead of No Name Constraints at all.<br>
><br>
>> Since the purpose of adding the Name Constraints extension is to technically constrain the name space the externally-operated subordinate CA is allowed to issue subsequent certificates, I do not see how this purpose can be accomplished if we allow clients
to ignore the Name Constraints extension (by marking it non-critical).<br>
>><br>
>> To those smart clients, marking the Name Constraints extension critical cause no problem because that extension is recognized. To those dumb clients, if they do not understand the meaning of the Name Constraints extension, it is dangerous for them to blindly
accept the certificate. It comes naturally that those dumb clients should reject constrained certificate they do not understand. I do not see why allowing clients to blindly accept certificates which may be out of the allowed name space can materially reduce
the risk of those that rely on us.<br>
>><br>
>> I do not oppose the use of the Name Constraints extension, but I want that extension to be used in the correct way.<br>
>><br>
>> Wen-Cheng Wang<br>
>><br>
>> -----Original Message-----<br>
>> From: Ryan Hurst [<a href="mailto:ryan.hurst@globalsign.com" target="_blank">mailto:ryan.hurst@globalsign.com</a>]<br>
>> Sent: Friday, May 25, 2012 6:15 AM<br>
>> To: 'Chris Palmer'; <span lang="JA">王瘢雹文正</span><br>
>> Cc: <a href="mailto:public@cabforum.org">public@cabforum.org</a><br>
>> Subject: RE: [cabfpub] More changes to proposed policy update<br>
>><br>
>> I agree with Chris and others on this topic.<br>
>><br>
>> The intent of a standard is to document the desired end state, only sometimes do they bother themselves with the transition problem (which is why so many never really get fully deployed IMHO).<br>
>><br>
>> In this case the only downside of doing this is not complying with a clause in some document, the upside is materially reducing the risk of those that rely on us.<br>
>><br>
>> We are actively moving our customers to this model.<br>
>><br>
>> Ryan<br>
>><br>
>> -----Original Message-----<br>
>> From: <a href="mailto:public-bounces@cabforum.org">public-bounces@cabforum.org</a> [<a href="mailto:public-bounces@cabforum.org" target="_blank">mailto:public-bounces@cabforum.org</a>]<br>
>> On Behalf Of Chris Palmer<br>
>> Sent: Thursday, May 24, 2012 1:38 PM<br>
>> To: <span lang="JA">王瘢雹文正</span><br>
>> Cc: <a href="mailto:public@cabforum.org">public@cabforum.org</a><br>
>> Subject: Re: [cabfpub] More changes to proposed policy update<br>
>><br>
>> On Thu, May 24, 2012 at 6:42 AM, <span lang="JA">王瘢雹文正</span><<a href="mailto:wcwang@cht.com.tw">wcwang@cht.com.tw</a>></span><span style="font-size:10.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:10.0pt"> wrote:<br>
>><br>
>>> For the criticality of the Name Constraints extension, the text in<br>
>>> the ITU-T X.509 standard reads "It is recommended that it be flagged critical; otherwise, a certificate user may not check that subsequent certificates in a certification path are located in the constrained name spaces intended by the issuing CA."<br>
>><br>
>> Sure, but otherwise-acceptable certificate chains fail in some clients when the client sees critical fields it doesn't understand. That effectively stops us from deploying name-constrained certificates without an Internet Flag Day where everyone fixes their
clients. Since that is not going to happen, the way to get incremental improvement is to allow non-critical name constraints, and for the vendors of smart clients to enforce them where present.<br>
>><br>
>> That is, to smart clients they will be effectively critical, but dumb clients at least won't explode. That's not ideal, but it is significantly Better Than Nothing. Name constraints are so wonderfully good that it's still very nice to get their benefits
in some clients, even if not in all clients.<br>
>><br>
>> So Google would most likely vote for it and implement it.<br>
>><br>
>><br>
>> --<br>
>> If it's not safe, is it really usable?<br>
>> _______________________________________________<br>
>> Public mailing list<br>
>> <a href="mailto:Public@cabforum.org">Public@cabforum.org</a><br>
>> <a href="http://cabforum.org/mailman/listinfo/public" target="_blank">http://cabforum.org/mailman/listinfo/public</a><br>
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>> <a href="http://cabforum.org/mailman/listinfo/public" target="_blank">http://cabforum.org/mailman/listinfo/public</a><br>
><br>
> --<br>
> Rob Stradling<br>
> Senior Research&</span><span style="font-size:10.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:10.0pt"> Development Scientist<br>
> COMODO - Creating Trust Online<br>
> Office Tel: +44.(0)1274.730505<br>
> Office Fax: +44.(0)1274.730909<br>
> <a href="http://www.comodo.com/" target="_blank">www.comodo.com</a><br>
><br>
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COMODO - Creating Trust Online<br>
Office Tel: +44.(0)1274.730505<br>
Office Fax: +44.(0)1274.730909<br>
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