Hi Francesca,
Thanks for your review and thoughtful comments!
Comments below.
> 1. -----
> [...]
While it is reasonable to expect that a RS receiving an unencrypted token after
requesting it to be encrypted will reject it, there are a number of cases where
the RS might elect to do otherwise. For example, the solution might be already
working in production: the encryption requirement might be an improvement that
is still propagating thru the system, and there might still be access tokens
cached in clients that the RS might still be willing to accept to guarantee
business continuity. "SHOULD" gives a strong signal to implementers of what the
desired behavior is, but leaves them some freedom to accommodate situations
like the aforementioned one.
> 2. ---
> [...]
Fair enough. I added the following text at the beginning of 2.1. Thanks for
catching this.
JWT access tokens MUST be signed. Although JWT access tokens can use any
signing algorithm[..]
This change will appear in the next revision, which I will post soon.
> 3. -----
> [...]
Formally, I agree that JOSE would also work. The choice of media type derives
from https://tools.ietf.org/html/rfc7519#section-10.3.1. There is no functional
difference between JWS and JWE in the intent a client has when calling an RS,
here there's not much to be gained in using different MIME types for those
cases. Furthermore, whereas developers are familiar with the term "JWT", both
from direct use and thanks to the popularity of OpenID Connect (which does use
application/jwt), terms like JWS, JWE or JOSE wouldn't be as promptly
understood as JWT. Throughout the discussions in the last couple of years, the
consensus on the use of at+jwt was solid- my hope is that will make intuitive
sense for implementers, too.
On 4/4/21, 11:01, "Francesca Palombini via Datatracker" <[email protected]>
wrote:
Francesca Palombini has entered the following ballot position for
draft-ietf-oauth-access-token-jwt-12: No Objection
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The document, along with other ballot positions, can be found here:
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----------------------------------------------------------------------
COMMENT:
----------------------------------------------------------------------
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.
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