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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>I think the random value should simply be tied to a particular certificate request and leave the rest up to the CA and the subscriber. More detailed comments inline below.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b>From:</b> Public [mailto:public-bounces@cabforum.org] <b>On Behalf Of </b>Jeremy Rowley via Public<br><b>Sent:</b> Tuesday, July 25, 2017 11:21 PM<br><b>To:</b> CA/Browser Forum Public Discussion List <public@cabforum.org><br><b>Subject:</b> [cabfpub] Random value reuse<o:p></o:p></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>An interesting question came up today in connection with random values used for validation. Methods 2, 4, 6, 7, and 10 permit use of a random values. Methods 2 and 4, require a unique random value per email. Methods 6, 7, and 10 do not require unique random values per request for the random value. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Some customers would like to use the same random value across multiple methods (method 2, 6, and 7), having us look for the first instance of the random value, or across multiple domains. Method 6 and 7 require a unique random value per certificate request, not per domain. This means, that the same Random Value can appear in multiple DNS records at once to confirm control. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The questions raised by this are:<o:p></o:p></p><ol style='margin-top:0in' start=1 type=1><li class=MsoNormal style='margin-left:0in;mso-list:l0 level1 lfo3'>Should the random value be unique per verified domain name instead of per certificate request?<o:p></o:p></li></ol><p class=MsoNormal><b><i>[RWS] No. I think it should be tied to the request. Consider the case of multiple domain certificate for which the applicant is a web host or CDN which controls the DNS for all domain names contained w/in. Why should they not be able to use the same random value to verify all those domains?<o:p></o:p></i></b></p><p class=MsoNormal style='margin-left:.5in'> With email methods, use of a single email to verify multiple domain names with the same email address makes sense. I’m not sure this makes as much sense for DNS records.<o:p></o:p></p><p class=MsoNormal><b><i>[RWS] I think it does if for no other reason than to cut down on confusion on the part of the subscriber. Consider the non-web host/CDN. Just an enterprise customer who has multiple domains. Why make one guy deal with 5 different random values for a single MDC request.<o:p></o:p></i></b></p><p class=MsoNormal style='margin-left:.5in'> <o:p></o:p></p><ol style='margin-top:0in' start=2 type=1><li class=MsoNormal style='margin-left:0in;mso-list:l0 level1 lfo3'>Can multiple methods use the same random value? Can you request a random value and then the CA just scour the permitted locations to find it? This seems okay to me as nothing requires the CA to specify the method of validation associated with the Random Value, but thought I’d get other opinions.<o:p></o:p></li></ol><p class=MsoNormal><b><i>[RWS] As long as the random value is tied to the specific request, I think this is fine.</i></b><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Jeremy<o:p></o:p></p></div></body></html>