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<p class="MsoNormal">Here are screen shots of the Facebook.com cert, if anyone hasn’t seen it. The .onion domains are in the second shot in the SANs field.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><img width="419" height="521" id="Picture_x0020_3" src="cid:image001.png@01D046C1.D1682440"><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><img width="419" height="521" id="Picture_x0020_1" src="cid:image002.png@01D046C1.D1682440"><span style="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""> Kirk Hall (RD-US)
<br>
<b>Sent:</b> Thursday, February 12, 2015 12:44 PM<br>
<b>To:</b> Jeremy Rowley (jeremy.rowley@digicert.com); Ben Wilson (Ben.Wilson@digicert.com)<br>
<b>Cc:</b> CABFPub (public@cabforum.org)<br>
<b>Subject:</b> Ballot 144 -.onion domains<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Jeremy and Ben – sorry we didn’t ask these questions last week, but I was travelling and didn’t realize the comment period had begun.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">(1) We are concerned that under Ballot 144 there could be two .onion certs with the SAME domain but identifying two DIFFERENT subjects.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">For example, Evil Corp. and Angel Corp. could each submit a request for a .onion cert and get the same domain:
<u>[same 16 digit hash of their public keys].onion</u> if their public keys hash to the same value. One cert would say O=Evil Corp. the other would say O=Angel Corp., so that a .onion domain would not be uniquely identified with one subject. While unlikely,
it could happen.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">How does Tor resolve this if the same .onion domain is assigned to multiple, different subjects? If someone types in [16 digit hash].onion and that could lead to multiple Tor locations, how does Tor decide where to direct the user?
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">(2) Does this also create an opportunity for a hacker? For example, one of the .onion domains in the SANs field of the Facebook cert you created is
<u>*.xx.fbcdn23dssr3jqnq.onion</u> – could a hacker create a public key that would hash to the same value in order to get a cert with the same .onion domain and imitate the Facebook cert? (This is maybe the more serious case.)<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">(3) Another concern is there is no central registry to identify the owner of a .onion domain (of course, there could be multiple owners of the domain under the scenario above). If there is no Subject info in the O field, etc., with no
registry there is no real way to contact the domain (or cert owner). <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Any information you can provide on these point will be very helpful.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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