[OAUTH-WG] Francesca Palombini's No Objection on draft-ietf-oauth-access-token-jwt-12: (with COMMENT)

[Francesca Palombini via Datatracker <[e-mail]>]

Francesca Palombini has entered the following ballot position for
draft-ietf-oauth-access-token-jwt-12: No Objection

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COMMENT:
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Thank you for the work on this document. Please find some comments and
clarifying questions below.

Francesca

1. -----

      registration.  If encryption was negotiated with the authorization
      server at registration time and the incoming JWT access token is
      not encrypted, the resource server SHOULD reject it.

FP: Why is this just SHOULD and not MUST? In which case does it make sense to
accept a non-encrypted token when encryption was negotiated?

2. -----

Section 2.1:

   Section 4).  JWT access tokens MUST NOT use "none" as the signing
   algorithm.  See Section 4 for more details.

Section 4:

   For the purpose of facilitating validation data retrieval, it is here
   RECOMMENDED that authorization servers sign JWT access tokens with an
   asymmetric algorithm.

   ...

   o  The resource server MUST validate the signature of all incoming
      JWT access tokens according to [RFC7515] using the algorithm
      specified in the JWT alg Header Parameter.  The resource server

FP: It might be obvious, but I think it would be useful to have an explicit
sentence stating that JWT MUST be signed. The quoted text from Section 2.1 seem
to imply it. Section 4 only RECOMMENDS that the JWT is signed with and
asymmetric algorithm. Later on, Section 4 implies that all JWT are signed. On
the other hand I note that encryption can be negotiated (and is optional) from
the followig point; in that case it is not clear that the token is still signed
(so the nested JWT would be a JWE nested in a JWS), or only JWE is used. What I
am looking for is simple clarifications to be added for example in the
introduction.

     o  If the JWT access token is encrypted, decrypt it using the keys
      and algorithms that the resource server specified during
      registration.  If encryption was negotiated with the authorization

3. -----

On the same note, and depending on the previous answer, why is the media type
registered and used "application/at+jwt" and not something like
"application/at+jws"/"application/at+jwe" or rather "application/at+jose" to be
compliant with https://www.rfc-editor.org/rfc/rfc7515.html#section-9.2.1 ? I
think that the structure transported is in fact a JWS or a JWE, rather than the
JWT, and if that's the case that should be made clear in the text (one example
where this could be clarified is in the following sentence)

   Resource servers receiving a JWT access token MUST validate it in the
   following manner.