The disadvantage of requiring PKCE for OpenID Connect implementations is that
you’re trying to add a normative requirement that’s not required of OpenID
Connect deployments today, which would bifurcate the ecosystem. There are
hundreds of implementations (including the 141 certified ones at
https://openid.net/certification/), none of which have ever been required to
support PKCE. Therefore, most don’t.
Per feedback already provided, I believe that OAuth 2.1 should align with the
guidance already in the draft Security BCP, requiring EITHER the use of PKCE or
the OpenID Connect nonce. Trying to retroactively impose unnecessary
requirements on existing deployments is unlikely to succeed and will
significantly reduce the relevance of the OAuth 2.1 effort.
In particular, authorization servers shouldn’t be required to support PKCE when
they already support the OpenID Connect nonce. And clients shouldn’t reject
responses from servers that don’t support PKCE when they do contain the OpenID
Connect nonce. Doing so would unnecessarily break things and create confusion
in the marketplace.
-- Mike
From: OAuth <oauth-boun...@ietf.org> On Behalf Of Dick Hardt
Sent: Wednesday, May 6, 2020 10:48 AM
To: oauth@ietf.org
Subject: [OAUTH-WG] OAuth 2.1 - require PKCE?
Hello!
We would like to have PKCE be a MUST in OAuth 2.1 code flows. This is best
practice for OAuth 2.0. It is not common in OpenID Connect servers as the nonce
solves some of the issues that PKCE protects against. We think that most OpenID
Connect implementations also support OAuth 2.0, and hence have support for PKCE
if following best practices.
The advantages or requiring PKCE are:
- a simpler programming model across all OAuth applications and profiles as
they all use PKCE
- reduced attack surface when using S256 as a fingerprint of the verifier is
sent through the browser instead of the clear text value
- enforcement by AS not client - makes it easier to handle for client
developers and AS can ensure the check is conducted
What are disadvantages besides the potential impact to OpenID Connect
deployments? How significant is that impact?
Dick, Aaron, and Torsten
[https://mailfoogae..appspot.com/t?sender=aZGljay5oYXJkdEBnbWFpbC5jb20%3D&type=zerocontent&guid=452438ba-d429-4656-ace9-b284744bc171]ᐧ
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