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<p class="MsoNormal"><span style="color:#002060">Filip is correct. The intent is only to enforce this behavior in certified implementations – not to change the specifications. This is being done to increase interoperability.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#002060"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#002060">There’s lots of cases where we intentionally constrain certified implementations beyond what’s strictly required by the specifications to increase interoperability. For instance, the test “(OP-IDToken-kid) IDToken
has kid [Basic, Implicit, Hybrid]” requires that the ID Token always contains a Key ID, even though the Connect spec only requires it when there are multiple keys in the JWK Set. This was done so that it could be counted on.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#002060"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#002060">Likewise, the WG decision to require unique “kid” values goes beyond the spec, but eliminates a number of potential errors resulting from odd corner cases. I firmly believe that the working made the right call
to enforce this in the certification suite.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#002060"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#002060"> -- Mike<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#002060"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b>From:</b> Openid-specs-fapi <openid-specs-fapi-bounces@lists.openid.net>
<b>On Behalf Of </b>Filip Skokan via Openid-specs-fapi<br>
<b>Sent:</b> Friday, January 17, 2020 1:42 PM<br>
<b>To:</b> Financial API Working Group List <openid-specs-fapi@lists.openid.net><br>
<b>Cc:</b> Filip Skokan <panva.ip@gmail.com><br>
<b>Subject:</b> [EXTERNAL] Re: [Openid-specs-fapi] Duplicate kids in jwks<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I don’t think it’s clear whether the intent was an errata or a proposal to the WG to further constrain the Connect certification profile. <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">I believe we could only do the latter. <o:p></o:p></p>
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<p class="MsoNormal">Odesláno z iPhonu<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">17. 1. 2020 v 22:05, Brian Campbell via Openid-specs-fapi <<a href="mailto:openid-specs-fapi@lists.openid.net">openid-specs-fapi@lists.openid.net</a>>:<o:p></o:p></p>
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<p class="MsoNormal"><o:p></o:p></p>
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<p class="MsoNormal">For better or worse JOSE allowed for duplicate kids and Connect didn't constrain it. So requiring uniqueness is a breaking change that an erratum shouldn't be doing. I guess that counts as a negative opinion towards the decision in
<a href="https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbitbucket.org%2Fopenid%2Fconnect%2Fissues%2F1127&data=02%7C01%7CMichael.Jones%40microsoft.com%7C3551ece54c0549a9fb0008d79b962a4e%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637148942095112814&sdata=lqMLz%2BB19FKwQyV4z4m8hWZZ%2FrAJArE6Pd84xfRaBdk%3D&reserved=0" target="_blank">
https://bitbucket.org/openid/connect/issues/1127</a> <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Fri, Jan 17, 2020 at 12:50 AM Joseph Heenan via Openid-specs-fapi <<a href="mailto:openid-specs-fapi@lists.openid.net">openid-specs-fapi@lists.openid.net</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Hi all,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I wanted to direct the FAPI working group to this discussion within the Connect working group:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><a href="https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbitbucket.org%2Fopenid%2Fconnect%2Fissues%2F1127&data=02%7C01%7CMichael.Jones%40microsoft.com%7C3551ece54c0549a9fb0008d79b962a4e%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637148942095122809&sdata=xOLPeYfXtphZIKATqdr6Qun9LLSkZrWWL0G2JdTsC8Q%3D&reserved=0" target="_blank">https://bitbucket.org/openid/connect/issues/1127</a><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Namely that duplicate kids are not permitted in JWKS.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">A test for this was recently added to all the conformance tests, which caused one of the UK banks to opine:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">it is valid for the JWK endpoint to return multiple KID instances, one for each ‘alg’ supported?<br>
The spec calls for the alg PS256 or longer to be supported, so we also have (for instance) PS384, PS512. And although we may show a couple that we don’t need, my point is that it must be valid to show multiple key entries to support multiple valid alg values. <o:p></o:p></p>
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<p class="MsoNormal">To some extent this seems a reasonable point, reusing a key across across two algs that can use the same key seems ok, and arguably perhaps better than having the key once without an ‘alg’ specified.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">As this affects the FAPI certification tests, I wanted to check the FAPI WG agrees with the decision in <a href="https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbitbucket.org%2Fopenid%2Fconnect%2Fissues%2F1127&data=02%7C01%7CMichael.Jones%40microsoft.com%7C3551ece54c0549a9fb0008d79b962a4e%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637148942095132801&sdata=V8UtOzKQhIeFFBnhGyaRUWQn1nLqGhTrIAm7vQakV1o%3D&reserved=0" target="_blank">https://bitbucket.org/openid/connect/issues/1127</a> -
any opinions (positive & negative) would be great please.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Thanks<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Joseph Heenan<o:p></o:p></p>
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<p class="MsoNormal">OpenID Certification Team<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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