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<p class="MsoNormal" style="background:white"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">></span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222"> I am ok with RECOMMENDing that these audience
to be encoded in the access_token itself, but would like to let the implementors have choices on it<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222"><o:p> </o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">Not sure what you mean by encoded in the access_token, I assume you mean that there is a aud_restriction claim in the token, not that
the token is encoded somehow that the receiving parties can decode?</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<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""> openid-specs-ab-bounces@lists.openid.net [mailto:openid-specs-ab-bounces@lists.openid.net]
<b>On Behalf Of </b>Nat Sakimura<br>
<b>Sent:</b> Thursday, November 10, 2011 5:04 PM<br>
<b>To:</b> openid-specs-ab@lists.openid.net<br>
<b>Subject:</b> [Openid-specs-ab] Audience restriction of access_token/resource ep response in OpenID Connect<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span class="apple-style-span"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222;background:white">Hi. </span></span><o:p></o:p></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">Currently, as it turns out in OpenID Connect, the way to audience restrict <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">the response of a resource endpoint is to encrypt the response <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">using the key of the intended client. The server has to keep track of <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">to whom the access_token was issued, i.e., client audience restriction, <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">and use the registration information of that client to find out the relevant key. <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">By doing so, even if the request comes from a rogue party who phished the <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">legitimate client, the rogue party cannot read the response, so it is secure. <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">As to the resource endpoint audience restriction is concerned, <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">it is done implicitly in the sense that as the access_token is opaque, <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">only the intended endpoint can actually interprete and validate it. <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">This is how the resource endpoint audience restriction is done <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">in OAuth 2.0 as I understand. <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">As it is written right now, how to record both client and resource endpoint <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">audience restriction is an implementation detail. <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">I think it should remain implementation detail, but <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">it is worthwhile to note that somehow the audience restriction MUST be done. <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">I am ok with RECOMMENDing that these audience to be encoded <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">in the access_token itself, but would like to let the implementors have <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#222222">choices on it. <o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">-- <br>
Nat Sakimura (=nat)<o:p></o:p></p>
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<p class="MsoNormal">Chairman, OpenID Foundation<br>
<a href="http://nat.sakimura.org/" target="_blank">http://nat.sakimura.org/</a><br>
@_nat_en<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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