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</o:shapelayout></xml><![endif]--></head><body lang=EN-AU link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>The sector_identifier_uri [<a href="http://openid.net/specs/openid-connect-core-1_0.html#PairwiseAlg">core §8.1</a>, <a href="http://openid.net/specs/openid-connect-registration-1_0.html#SectorIdentifierValidation">dynamic reg §5</a>] lists the redirect_uris of apps that can receive the same subscriber ids (subs) from OIDC providers that issuer pairwise subs. The list is effectively a domain authorizing the apps that are allowed to be associated with it.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Because it conveys a domain’s authority, the sector_identifier_uri should have a fixed /.well-known/ path on the domain.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Otherwise, a domain may unwittingly authorize an app. Any content on a domain that happens to be a URI in square brackets can be misused by using it as a sector_identifier_uri to receive the domain’s subs. Any redirect from a domain (not just an open redirector) can be misused by the destination of the redirect to receive the domain’s subs.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>To address this risk, how about we require sector_identifier_uri to be:<o:p></o:p></p><p class=MsoNormal> https://<domain>/.well-known/openid/apps.json<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I’m not sure if this extra restriction can be done as a errata (to core & dynamic reg), or something more substantial is necessary.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='mso-fareast-language:EN-AU'>--<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-AU'>James Manger<o:p></o:p></span></p></div></body></html>