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<p class="MsoNormal">On Thu, Apr 7, 2016 at 11:34 AM, Peter Bowen <<a href="mailto:pzb@amzn.com" target="_blank">pzb@amzn.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Doug,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Would you be able to use the same subject public key and same subject distinguished name as their previous certificate?<o:p></o:p></p>
<p class="MsoNormal"><b><i><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">[Doug] Yes, We can do this.</span></i></b><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"><o:p> </o:p></p>
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<p class="MsoNormal">Would you be able to use the same certificate profile as your previously issued SHA-1 certificates?<o:p></o:p></p>
<p class="MsoNormal"><b><i><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></i></b></p>
<p class="MsoNormal"><b><i><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">[Doug] Not really, this cert was issued from a different CA, so:<o:p></o:p></span></i></b></p>
<p class="MsoNormal"><b><i><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">- The CDP, AIA, AKI and Certificate Policies content will be different (the extensions will be there, but content is different)<o:p></o:p></span></i></b></p>
<p class="MsoNormal"><b><i><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">- Currently, the EKU contains SGC, which we would not use, so that would be removed and just have server auth and client auth<o:p></o:p></span></i></b></p>
<p class="MsoNormal"><b><i><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">- Key usage, Basic Constraints, SKI and SAN extensions will remain the same<o:p></o:p></span></i></b></p>
<p class="MsoNormal"><b><i><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">- We would add the SKI extension, consistently with our OV certificate profiles<o:p></o:p></span></i></b></p>
<p class="MsoNormal"><b><i><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></i></b></p>
<p class="MsoNormal"><b><i><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">But, all of the extensions that will be different (CDP, AIA, EKU, Cert Policies) will contain exactly the same values as all other OV certificates issued
under this CA<o:p></o:p></span></i></b></p>
<p class="MsoNormal"><b><i><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></i></b></p>
<p class="MsoNormal"><b><i><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Obviously the IssuerDN, Cert NotBefore/NotAfter and Serial number will be different.<o:p></o:p></span></i></b></p>
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<p class="MsoNormal">If both are true, then I think that the hash collision risk is heavily mitigated.<o:p></o:p></p>
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<p class="MsoNormal">Agreed. Or, perhaps stated differently, if whatever changes is consistent for all such certificates (and, even more strongly, consistent with non-SHA1 certificates excluding the signature algorithm), the risk of a CA colluding seems mitigated. <o:p></o:p></p>
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