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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Who do you want to say something about the “session strength” to?
<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> openid-specs-ab-bounces@lists.openid.net [mailto:openid-specs-ab-bounces@lists.openid.net]
<b>On Behalf Of </b>Tim Bray<br>
<b>Sent:</b> Monday, August 12, 2013 1:05 PM<br>
<b>To:</b> <openid-specs-ab@lists.openid.net><br>
<b>Subject:</b> [Openid-specs-ab] acr values<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">In our IDP role, we’re coming under a lot of pressure to say something about “session strength” and maybe in some circumstances force re-auth and so on. There are a lot of different vocabularies in play that
you could use to talk about this stuff, including NIST and ISO publications; and the work of the Fido alliance is maybe interesting. So I expect a lot of churn in this space, and OIDC needs to allow sufficient elbow room.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">So, the purpose of this note is to confirm my understandings, based on looking at the OIDC Messages draft. Do people agree with these?<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">- It’s perfectly OK to provide any old URI we dream up as a value for the “acr” claim.<o:p></o:p></p>
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<p class="MsoNormal">- There may be awkwardness around multiple values; suppose I wanted to assert, for example, that the session is less than ten minutes old AND two-factor authent was used. All I can think of is composing a URI along the lines of urn:google-auth-claims?max-age=10&two-factor=true;
which is a little kludgy but I guess OK. Awkward, though, in the case where there’s a Fido vocabulary for 2-factor-flavor and someone else’s vocabulary for session-freshness.<o:p></o:p></p>
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