<div dir="ltr">They are, however, if the logout_token is encrypted you can't peek in :) This is a concern if the software handles more issuers by the same backchannel_logout_uri.<div><div><br clear="all"><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature">Best,<br><b>Filip</b></div></div><br></div></div></div><br><div class="gmail_quote"><div dir="ltr">On Fri, Sep 21, 2018 at 5:38 PM Phil Hunt via Openid-specs-ab <<a href="mailto:openid-specs-ab@lists.openid.net">openid-specs-ab@lists.openid.net</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Interesting. My assumption is iss, aud etc are req’d claims from JWT. <br>
<br>
However maybe a reminder is important?<br>
<br>
Phil<br>
<br>
> On Sep 21, 2018, at 4:52 AM, Hans Zandbelt via Openid-specs-ab <<a href="mailto:openid-specs-ab@lists.openid.net" target="_blank">openid-specs-ab@lists.openid.net</a>> wrote:<br>
> <br>
> New issue 1049: backchannel logout requests should include a reference to the OP<br>
> <a href="https://urldefense.proofpoint.com/v2/url?u=https-3A__bitbucket.org_openid_connect_issues_1049_backchannel-2Dlogout-2Drequests-2Dshould-2Dinclude&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=na5FVzBTWmanqWNy4DpctyXPpuYqPkAI1aLcLN4KZNA&m=lm9I-tIhoNwvye6UOWEMPW8NY3NHLUhJ9SotrZMkfjo&s=3LFWnJR17VF0dS5xSTSpiGzBJQ6AFN3Pu3Oa8M3ONMQ&e=" rel="noreferrer" target="_blank">https://urldefense.proofpoint.com/v2/url?u=https-3A__bitbucket.org_openid_connect_issues_1049_backchannel-2Dlogout-2Drequests-2Dshould-2Dinclude&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=na5FVzBTWmanqWNy4DpctyXPpuYqPkAI1aLcLN4KZNA&m=lm9I-tIhoNwvye6UOWEMPW8NY3NHLUhJ9SotrZMkfjo&s=3LFWnJR17VF0dS5xSTSpiGzBJQ6AFN3Pu3Oa8M3ONMQ&e=</a><br>
> <br>
> Hans Zandbelt:<br>
> <br>
> Whilst taking a stab at implementing backchannel logout according to:<br>
> <a href="https://urldefense.proofpoint.com/v2/url?u=https-3A__openid.net_specs_openid-2Dconnect-2Dbackchannel-2D1-5F0.html&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=na5FVzBTWmanqWNy4DpctyXPpuYqPkAI1aLcLN4KZNA&m=lm9I-tIhoNwvye6UOWEMPW8NY3NHLUhJ9SotrZMkfjo&s=L6lYaopVVDpj0Pk2gtvli2CrojHXip4pHWm-fsGlHyQ&e=" rel="noreferrer" target="_blank">https://urldefense.proofpoint.com/v2/url?u=https-3A__openid.net_specs_openid-2Dconnect-2Dbackchannel-2D1-5F0.html&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=na5FVzBTWmanqWNy4DpctyXPpuYqPkAI1aLcLN4KZNA&m=lm9I-tIhoNwvye6UOWEMPW8NY3NHLUhJ9SotrZMkfjo&s=L6lYaopVVDpj0Pk2gtvli2CrojHXip4pHWm-fsGlHyQ&e=</a><br>
> <br>
> I found that for an RP that connects to multiple OPs it would be impossible to deduct the OP from the `logout_token` if it is encrypted with a symmetric key. Since following the OpenID Connect `id_token` guidelines (as suggested) it would have to decrypt with the `client_secret` which is (hopefully) a per-provider setting. Trying all OPs/`client_secret`'s consecutively would be very inefficient and probably not what anyone would want to do.<br>
> <br>
> I suggest to add an `iss` parameter to the backchannel logout request in addition to the `logout_token` parameter. <br>
> <br>
> This will also make it easier for implementors to share the code path with `id_token` validation since they'd no longer have to "peek" into the `id_token` before calling the validation routine that may be issuer specific. The issuer would typically be known before validating the id_token since it is recorded in the (browser bound) state.<br>
> <br>
> <br>
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