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<div class="">Le 4 févr. 2016 à 18:26, Erwann Abalea <<a href="mailto:Erwann.Abalea@docusign.com" class="">Erwann.Abalea@docusign.com</a>> a écrit :</div>
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<div class="">Le 2 févr. 2016 à 20:02, Peter Bowen <<a href="mailto:pzb@amzn.com" class="">pzb@amzn.com</a>> a écrit :</div>
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On Feb 2, 2016, at 10:06 AM, Ryan Sleevi <<a href="mailto:sleevi@google.com" class="">sleevi@google.com</a>> wrote:</div>
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[…]</div>
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<div class="">And it is certs like <a href="https://crt.sh/?id=11880495" class="">https://crt.sh/?id=11880495</a> that prove that this is true. That certificate was issued in the last month, has no SAN or EKU, has a FQDN in the CN, and chains back to one or
more roots trusted by every browser (<a href="https://gist.github.com/pzb/c55a802c283c7b44002d" class="">https://gist.github.com/pzb/c55a802c283c7b44002d</a>). <a href="https://www.ssllabs.com/ssltest/analyze.html?d=aflsa.jag.af.mil" class="">https://www.ssllabs.com/ssltest/analyze.html?d=aflsa.jag.af.mil</a> shows
that the certificate is in use at the FQDN in the CN.</div>
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<div class="">According to the ssllabs analysis, the chain should fail due to policy constraints, but I’m not sure if anything enforces such constraints.</div>
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<div class="">Correct.</div>
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<div class="">From top to bottom, the chain is:</div>
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<li class="">DST ACES CA X6 (trust anchor)</li><li class="">IdenTrust ACES CA 1</li><li class="">Federal Bridge CA 2013</li><li class="">Federal Common Policy CA</li><li class="">SHA-1 Federal Root CA</li><li class="">DoD Interoperability Root CA 1</li><li class="">DoD Root CA 2</li><li class="">DOD CA-28</li><li class="">aflsa.jag.af.mil</li></ul>
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<div class="">Using RFC5280 wording, valid_policy_tree is equal to NULL at « SHA-1 Federal Root CA », and the chain fails at the « DoD Root CA 2 » certificate, because now explicit_policy is equal to 0 (and valid_policy_tree is NULL).</div>
<div class="">Strangely, certificate for « DoD Interoperability Root CA 1 » has a PolicyMappings extension, but policy mapping is forbidden since « SHA-1 Federal Root CA ».</div>
<div class="">Strangely again, the PolicyConstraints extension contained in « DoD Root CA 2 » is not critical. It’s a MUST for RFC5280, and a MAY for X.509 (with a recommendation to set it critical). It’s the extension that requires an explicit policy and makes
the chain fail.</div>
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<div class="">OpenSSL is able to reject such a chain (it doesn’t seem to handle the policy mappings), I’ve been told that MS can correctly reject it, I’m pretty sure that the recent Mozilla PKIX lib accepts it while the previous one rejects it. (And I wouldn’t
bet a cent on GnuTLS to do such things correctly)</div>
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<div class="">A correction here. Mozilla should be able to reject this chain because of unhandled critical extensions upper in the chain (Federal Bridge CA 2013 and Federal Common Policy CA).</div>
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