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[Resending; hopefully this message won't get lost in a moderation queue/blackhole this time]</div>
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<span style="margin:0px;font-size:12pt">> However, in all the documentation I’ve seen regarding Authenticode, it appears that the revocation date is the value that is checked by Windows and<span> </span><span data-markjs="true" class="markevaru7uc9" data-ogac="" data-ogab="" data-ogsc="" data-ogsb="" style="margin:0px">invalidity</span>Date
is seemingly not used.</span>
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<div style="margin:0px;font-size:12pt">That matches our experience.</div>
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<div style="margin:0px;font-size:12pt">On 2010-11-12, I received the following email from Tom Albertson, who at that time was in charge of the Microsoft Root Program:</div>
<div style="margin:0px;font-size:12pt"><i>'Hi Rob,</i>
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<div style="margin:0px"><i>I’m in over my technical head on this one, so treat it as more of a relay than anything else. When folks over here were looking at recent UserTrust CRLs, they noticed errors in Windows parsing the revocation date used. I’m not sure
if it is a recent change or something you have been doing for a reason, but in any event:</i></div>
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<div style="margin:0px"><i>In parsing CRLS, we populate the “Revocation Date” with the effective revocation date, but UserTrust is using the<span> </span><span data-markjs="true" class="markevaru7uc9" data-ogac="" data-ogab="" data-ogsc="" data-ogsb="" style="margin:0px">Invalidity</span><span> </span>Date
extension in its CRLs. RFC 5280 defines the<span> </span><span data-markjs="true" class="markevaru7uc9" data-ogac="" data-ogab="" data-ogsc="" data-ogsb="" style="margin:0px">Invalidity</span><span> </span>Date extension as “a non-critical CRL entry extension
that provides the date on which it is known or suspected that the private key was compromised or that the certificate otherwise became invalid.” This extension has been around in the standards since 1999 at least as a recommended (SHOULD) extension. However,
Windows has never supported it. Windows sets the effective revocation date in the RevocationDate field, which is supported by other code signing CAs. Or at least we haven’t noted this use of the<span> </span><span data-markjs="true" class="markevaru7uc9" data-ogac="" data-ogab="" data-ogsc="" data-ogsb="" style="margin:0px">Invalidity</span><span> </span>Date
extension by other CAs so far.</i></div>
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<div style="margin:0px"><i>Can you look into this practice on your end, and try to find out the reason for it? Would there be any problem going forward indicating the effective revocation date in the RevocationDate field? This would appear to require re-issuing
the CRLS, but not require rolling over any of your certificates.</i></div>
<div style="margin:0px"><i> </i></div>
<div style="margin:0px"><i>Thanks and best regards,</i></div>
<i>Tom Albertson'</i></div>
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<div style="margin:0px;font-size:12pt">The end result of that conversation was that we felt we had to treat Tom's request as a requirement from a root store operator that overrode RFC5280, which meant that we had to change our (previously RFC5280-compliant)
implementation to start putting the effective revocation date into the "Revocation Date" field instead of the "<span data-markjs="true" class="markevaru7uc9" data-ogac="" data-ogab="" data-ogsc="" data-ogsb="" style="margin:0px">Invalidity</span><span> </span>Date"
extension. Since we haven't heard anything new from Microsoft on this topic since then, our implementation still behaves this way today. (I commented rather than deleted our original code, in the hope that we would one day be permitted to return to being
RFC5280-compliant).</div>
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<div style="margin:0px;font-size:12pt">I don't like it when any aspect of policy is defined by a private communication that a root store operator sent only to a subset of CAs, but that seems to be what happened in this case.</div>
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<div style="margin:0px;font-size:12pt">> Could Ian or Mike confirm Windows’s behavior in this regard?</div>
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<div style="margin:0px;font-size:12pt">An official, public update on Microsoft's policy requirements for encoding the effective revocation date in CRLs would also be much appreciated!</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Cscwg-public <cscwg-public-bounces@cabforum.org> on behalf of Corey Bonnell via Cscwg-public <cscwg-public@cabforum.org><br>
<b>Sent:</b> 25 August 2021 22:50<br>
<b>To:</b> Bruce Morton <bruce.morton@entrust.com>; cscwg-public@cabforum.org <cscwg-public@cabforum.org><br>
<b>Subject:</b> Re: [Cscwg-public] Invalidity Date</font>
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Hi Bruce,</p>
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I agree that using the invalidityDate CRL entry extension to express when the key corresponding to a revoked code signing certificate can no longer be trusted as opposed to the revocation date is conceptually cleaner and more in line with 5280 (which states
that the revocation date SHOULD NOT be backdated such that it is before the issue date of the latest CRL).
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However, in all the documentation I’ve seen regarding Authenticode, it appears that the revocation date is the value that is checked by Windows and invalidityDate is seemingly not used.</p>
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Could Ian or Mike confirm Windows’s behavior in this regard?</p>
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Thanks,</p>
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Corey</p>
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<b>From:</b> Cscwg-public <cscwg-public-bounces@cabforum.org> <b>On Behalf Of </b>
Bruce Morton via Cscwg-public<br>
<b>Sent:</b> Wednesday, August 25, 2021 1:59 PM<br>
<b>To:</b> cscwg-public@cabforum.org<br>
<b>Subject:</b> [Cscwg-public] Invalidity Date</p>
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CSBR 13.2.1 states: A Certificate MAY have a one-to-one relationship or one-to-many relationship with the signed Code. Regardless, revocation of a Certificate may invalidate the Code Signatures on all signed Code, some of which could be perfectly sound. Because
of this, <span style="background:yellow">the CA MAY specify a revocation date in a CRL</span> or OCSP response to time-bind the set of software affected by the revocation, and software should continue to treat objects containing a timestamp dated before the
revocation date as valid.</p>
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The CSBRs are referring to “revocation date’, which I believe should be referring to “invalidity date” as specified in RFC 5280,
<a href="https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc5280%23section-5.3.2&data=04%7C01%7Crob%40sectigo.com%7C583b7f31a7a847c0708108d9681268be%7C0e9c48946caa465d96604b6968b49fb7%7C0%7C0%7C637655250558956991%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=rjQRyhLObdZAoDyvPX0fzZpbtBXIcvKsJtFsJYd0Pc0%3D&reserved=0" originalsrc="https://datatracker.ietf.org/doc/html/rfc5280#section-5.3.2" shash="vd7AR4p6OpBTmEMHAD3rVVMHji77PgwLk1Y9ERS7lctXhiPfQh7vMm6eFFXZo1imgcj7m+QO0yWaAYNzrXEEDnAEEffIKZLEHySRaezDdVFO5PEjd5arq8478xA2f1r9JWhfxqu1PlyGa22qmNHp55CsnbUO1yZKI/m00yseMWo=">
https://datatracker.ietf.org/doc/html/rfc5280#section-5.3.2</a>.</p>
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Note that we need to think of the following dates:</p>
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Valid from</li><li class="x_MsoListParagraph" style="margin: 0cm 0cm 0cm 36pt; font-size: 11pt; font-family: Calibri, sans-serif;margin-left:0cm">
Invalidity date</li><li class="x_MsoListParagraph" style="margin: 0cm 0cm 0cm 36pt; font-size: 11pt; font-family: Calibri, sans-serif;margin-left:0cm">
Revocation date</li><li class="x_MsoListParagraph" style="margin: 0cm 0cm 0cm 36pt; font-size: 11pt; font-family: Calibri, sans-serif;margin-left:0cm">
Valid to</li></ul>
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The purpose of the Invalidity date is to provide a date in the past, when the key was compromised. The revocation date would be on the date that the certificate was revoked and cannot be a past date.</p>
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Would there be any objections in changing “revocation date” to “invalidity date” in a future ballot?
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Thanks, Bruce</p>
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