[OAUTH-WG] oauth-access-token-jwt: comments and clarifications

Roberto Polli <robipolli@gmail.com> Fri, 02 April 2021 09:55 UTC

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From: Roberto Polli <robipolli@gmail.com>
Date: Fri, 2 Apr 2021 11:55:27 +0200
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Subject: [OAUTH-WG] oauth-access-token-jwt: comments and clarifications
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Hi Vittorio et al,

some considerations on oauth access token jwt follows.
You can see them here too
https://docs.google.com/document/d/1XsvBzGvhcY0N6vJNgLx6G1dJ5trvgwYRJA9F_NCakbU/edit

An example with client_credential grant type would be nice too.

My 2¢,
R.

§ 1.2  Terminology

+ The terms "Collision-Resistant",  is used according to Section 2 of
{{JWT}}.

§2.1 Header

- mentioning "none" alg can be redundant. I'd reference all the JWT BCP
instead.
- I'd add an example header, eg

~~~ example

{

  "typ": "at+jwt",

  "alg": "PS256"

}

~~~


§ 2.2.1 Authentication Information Claims

Is it worth mentioning the "implicit flow"?

§2.2.2 Identity Claims

- use the "Collision-Resistant" definition in {{JWT}}

§2.2.3 Authorization Claims

- " ... scope parameter..."  should `scope` be quoted?
-  "All the individual scope strings in the "scope" claim MUST have meaning
for the resources indicated in the "aud" claim."
^ otherwise the error returned is ...? Should we reference §4 here?

§2.2.3.1 Claims for Authorization Outside of Delegation Scenarios
- which are the delegated scenarios described in RFC7519? Do you refer to
"When using an administratively delegated
      namespace" ? It is not clear to a first-reader.

§3 Requesting a JWT Access Token
- an example with `client_credential` grant type would be great.
- iiuc `jti` is required, the example does not report it.

§4 Validating JWT Access Tokens

- the step about forbidding "none" is limitative WRT JWT BCP 8725