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<div class="moz-cite-prefix">I'm fine with adding private_key_jwt
back into Baseline. It seems that there are good reasons to do so.
Security-wise, the difference to MTLS is negligible. <br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">I will do so in the next commit. <br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">-Daniel<br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">Am 27.02.20 um 15:22 schrieb Ralph
Bragg:<br>
</div>
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cite="mid:8366A1AB-B071-408E-849F-E8EDACE0B25F@raidiam.com">
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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">As
a follow up there are some implementations which are making
use of the jwt authorization grant that currently use
client_id within the grant to perform client authentication.
I’ve seen this used as and it is being proposed as a means
of getting around the 90 day re-auth where a TPP can attest
in a way that can be validated that it has obtained ongoing
re-authorization from its customer without the customer
being present.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><a class="moz-txt-link-freetext" href="https://tools.ietf.org/html/rfc7523#section-2.1">https://tools.ietf.org/html/rfc7523#section-2.1</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">The
tokens are still sender constrained to tls but the
authentication mechanism is performed by signing it also
protects the “scope” parameter as this can be included
inside the JWT. To reiterate, I’m fully onboard with sender
constrains but I have concerns about push back and
subsequent adoption if we force everyone to support
tls_client_auth… especially as tls_client_auth is explicitly
excluded by the Australian CDR.
<a
href="https://consumerdatastandardsaustralia.github.io/standards/#end-points"
moz-do-not-send="true">
https://consumerdatastandardsaustralia.github.io/standards/#end-points</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="font-size:12.0pt;color:black">From: </span></b><span
style="font-size:12.0pt;color:black">Ralph Bragg
<a class="moz-txt-link-rfc2396E" href="mailto:ralph.bragg@raidiam.com"><ralph.bragg@raidiam.com></a><br>
<b>Date: </b>Thursday, 27 February 2020 at 13:50<br>
<b>To: </b>Torsten Lodderstedt
<a class="moz-txt-link-rfc2396E" href="mailto:torsten@lodderstedt.net"><torsten@lodderstedt.net></a>, Financial API Working
Group List <a class="moz-txt-link-rfc2396E" href="mailto:openid-specs-fapi@lists.openid.net"><openid-specs-fapi@lists.openid.net></a><br>
<b>Cc: </b>Daniel Fett <a class="moz-txt-link-rfc2396E" href="mailto:fett@danielfett.de"><fett@danielfett.de></a><br>
<b>Subject: </b>Re: [Openid-specs-fapi] FAPI 2.0<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Hi,</span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-family:Symbol">·</span>
MUST <span style="background:yellow;mso-highlight:yellow">
support client authentication</span> and sender-constraining
of access tokens using Mutual TLS as described in [@!RFC8705]<o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">From
a security point of view, MTLS is an edge device capability,
private_key_jwt is preferred by many security folks, myself
included that are worried about request alteration from
within network segments that are behind the edge MATLS
gateway. I also have concerns about this – immediately
Australian CDR would be not FAPI compliant in anyway.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Sender
constrained using MTLS but that can be done without
mandating client authentication as well.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Be
interested in others thoughts.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Kind
Regards,</span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Ralph</span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="font-size:12.0pt;color:black">From: </span></b><span
style="font-size:12.0pt;color:black">Ralph Bragg
<a class="moz-txt-link-rfc2396E" href="mailto:ralph.bragg@raidiam.com"><ralph.bragg@raidiam.com></a><br>
<b>Date: </b>Thursday, 27 February 2020 at 13:36<br>
<b>To: </b>Torsten Lodderstedt
<a class="moz-txt-link-rfc2396E" href="mailto:torsten@lodderstedt.net"><torsten@lodderstedt.net></a>, Financial API Working
Group List <a class="moz-txt-link-rfc2396E" href="mailto:openid-specs-fapi@lists.openid.net"><openid-specs-fapi@lists.openid.net></a><br>
<b>Cc: </b>Daniel Fett <a class="moz-txt-link-rfc2396E" href="mailto:fett@danielfett.de"><fett@danielfett.de></a><br>
<b>Subject: </b>Re: [Openid-specs-fapi] FAPI 2.0</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Nope
– just the fact that if an RS must do something then then an
AS must provide a means of doing it and potentially
describing how. Introspection? Shared keys for AT
decryption? Either works.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">We
were pretty good in the OB security profile to make sure
both sides, where mutuality of obligation is required was
detailed in the requirements.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="font-size:12.0pt;color:black">From: </span></b><span
style="font-size:12.0pt;color:black">Torsten Lodderstedt
<a class="moz-txt-link-rfc2396E" href="mailto:torsten@lodderstedt.net"><torsten@lodderstedt.net></a><br>
<b>Date: </b>Thursday, 27 February 2020 at 13:30<br>
<b>To: </b>Financial API Working Group List
<a class="moz-txt-link-rfc2396E" href="mailto:openid-specs-fapi@lists.openid.net"><openid-specs-fapi@lists.openid.net></a><br>
<b>Cc: </b>Daniel Fett <a class="moz-txt-link-rfc2396E" href="mailto:fett@danielfett.de"><fett@danielfett.de></a>, Ralph
Bragg <a class="moz-txt-link-rfc2396E" href="mailto:ralph.bragg@raidiam.com"><ralph.bragg@raidiam.com></a><br>
<b>Subject: </b>Re: [Openid-specs-fapi] FAPI 2.0</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">Are you referring to validity beyond
„exp“, i.e. checking for revocation?<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><br>
<br>
<br>
<br>
<o:p></o:p></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal" style="margin-bottom:12.0pt">Am
27.02.2020 um 14:09 schrieb Ralph Bragg via
Openid-specs-fapi
<a class="moz-txt-link-rfc2396E" href="mailto:openid-specs-fapi@lists.openid.net"><openid-specs-fapi@lists.openid.net></a>:<o:p></o:p></p>
</blockquote>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<p class="MsoNormal"><span
style="mso-fareast-language:EN-US">Small one from me
Daniel</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b>Requirements
for Authorization Servers</b><o:p></o:p></p>
<p class="MsoNormal"><span
style="mso-fareast-language:EN-US">Doesn’t include
explicitly the requirement to support a means of
validating that an access token is still valid. I had to
add this to the Open Banking security profile to force
banks to either share the keys with their RS’s or expose
an introspection endpoint. I know it’s stupid but can we
please make sure that if there is an explicit
requirement to validate an access token on the RS then
there is an explicit obligation to provide a means to do
so on the AS.</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="font-size:12.0pt;color:black">From: </span></b><span
style="font-size:12.0pt;color:black">Openid-specs-fapi
<a class="moz-txt-link-rfc2396E" href="mailto:openid-specs-fapi-bounces@lists.openid.net"><openid-specs-fapi-bounces@lists.openid.net></a> on
behalf of Joseph Heenan via Openid-specs-fapi
<a class="moz-txt-link-rfc2396E" href="mailto:openid-specs-fapi@lists.openid.net"><openid-specs-fapi@lists.openid.net></a><br>
<b>Reply to: </b>Financial API Working Group List
<a class="moz-txt-link-rfc2396E" href="mailto:openid-specs-fapi@lists.openid.net"><openid-specs-fapi@lists.openid.net></a><br>
<b>Date: </b>Thursday, 27 February 2020 at 10:37<br>
<b>To: </b>Daniel Fett <a class="moz-txt-link-rfc2396E" href="mailto:fett@danielfett.de"><fett@danielfett.de></a><br>
<b>Cc: </b>Joseph Heenan <a class="moz-txt-link-rfc2396E" href="mailto:joseph@authlete.com"><joseph@authlete.com></a>,
Openid-specs-fapi
<a class="moz-txt-link-rfc2396E" href="mailto:openid-specs-fapi@lists.openid.net"><openid-specs-fapi@lists.openid.net></a><br>
<b>Subject: </b>Re: [Openid-specs-fapi] FAPI 2.0</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<p class="MsoNormal">Thanks Daniel - a few responses inline:
<o:p></o:p></p>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">(Any points I removed I agree with
your response - thanks!)<o:p></o:p></p>
<div>
<p class="MsoNormal"><br>
<br>
<br>
<br>
<br>
<o:p></o:p></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<p class="MsoNormal">On 27 Feb 2020, at 08:12,
Daniel Fett <<a
href="mailto:fett@danielfett.de"
moz-do-not-send="true">fett@danielfett.de</a>>
wrote:<o:p></o:p></p>
</div>
<p class="MsoNormal"> <o:p></o:p></p>
<div>
<div>
<div>
<p class="MsoNormal">Thanks for the feedback,
Joseph! Answers inline.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">Am 26.02.20 um 17:23
schrieb Joseph Heenan:<o:p></o:p></p>
</div>
<blockquote
style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal">Thanks Daniel! <o:p></o:p></p>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">A few quick initial
thoughts:<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">"2.4. Differences to FAPI
1.0” the first column doesn’t seem quite
right - as this is the base line profile
should it be comparing against FAPI-R rather
than FAPI-RW?<o:p></o:p></p>
</div>
</blockquote>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">It
is based off FAPI-RW. To reach the security
goals, it is easier to start from RW. If we find
that we can give some leeway, we can reintroduce
features from R. (Baseline and Advanced are not
just new names for R and RW.)<o:p></o:p></p>
</div>
</div>
</blockquote>
<div>
<p class="MsoNormal">Good answer :-) I think it’s also
a reasonable position given I believe we’re not
aware of deployments of FAPI-R.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<div>
<blockquote
style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">I have some concerns
about FAPI 2.0 baseline only allowing MTLS
for client authentication.As it stands today
this still adds quite a burden on RPs,
compared to FAPI-R which did allow simple RP
credentials.<o:p></o:p></p>
</div>
</blockquote>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Currently,
RPs need MTLS anyway for sender-constraining of
the AT. Therefore I'm not sure if RP credentials
would actually make things easier.<o:p></o:p></p>
</div>
</div>
</blockquote>
<p class="MsoNormal">Good point.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">I think it would be interesting to
discuss whether dPoP would meet the goals and is
something we could include as an alternative. DPoP
feels to me to be easier for clients than MTLS (and
potentially servers too - the certification team has
seen a LOT of people struggle to get MTLS working on
production systems due to issues with WAFs and similar
that are required for PCI compliance).<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><br>
<br>
<br>
<br>
<br>
<o:p></o:p></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<div>
<blockquote
style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">RS Checking access tokens
are not revoked ("MUST verify that the
access token is neither expired nor
revoked;”) is also very strong language in a
baseline profile, and appears to rule out
the implementation choice of having short
lived JWT access tokens that cannot be
revoked.<o:p></o:p></p>
</div>
</blockquote>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">That
is actually taken from the current R spec. How I
read it, it still allows for unrevokable
short-lived JWTs, since if they are never
revoked, the check always passes.<o:p></o:p></p>
</div>
</div>
</blockquote>
</div>
<p class="MsoNormal">Interesting, I never noticed that
before. We may want to make the language a little
clearer in both places I guess.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">Joseph<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<p class="MsoNormal">_______________________________________________<br>
Openid-specs-fapi mailing list<br>
<a class="moz-txt-link-abbreviated" href="mailto:Openid-specs-fapi@lists.openid.net">Openid-specs-fapi@lists.openid.net</a><br>
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</div>
</blockquote>
</div>
</blockquote>
<p><br>
</p>
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