I have severe concerns with this approach. It’s not appropriate to register
arbitrary JSON object member names as JWT claim names – especially when the
JSON object member names are not even being used as JWT claim names. Please do
not do this, as it would needlessly pollute the JWT claim name namespace with
registered names that are application specific.
Secondarily, I have concerns about these names and suggestions for how to
address them.
“active” – This claim is not presently adequately defined. And its definition
will of necessity be specific to the introspection application. Therefore, it
should not be registered as a general JWT claim name. A name I would be
comfortable with for this concept would be
urn:ietf:params:oauth:introspection:active, since it makes it clear what
application the name is used with.
“user_id” – The concept you’re describing is almost universally called
“username”. User ID is typically the numeric account identifier (carried in
the “sub” claim in a JWT), and so is not the right name for this. Compare it
to the preferred_username claim in OpenID Connect. Please change this either
to “username” or urn:ietf:params:oauth:introspection:username.
“token_type” – While this is well-defined, the usage is fairly specific to this
application. Again, adding the urn:ietf:params:oauth:introspection: name
prefix would address this issue.
If you give up registering these names in the JWT Claims registry, I’m OK with
you using short names. But if you want them to live alongside other JWT claim
names, please include the urn:ietf:params:oauth:introspection: in lieu of
registration.
Thank you,
-- Mike
From: OAuth [mailto:[email protected]] On Behalf Of Justin Richer
Sent: Wednesday, March 04, 2015 1:46 PM
To: Hannes Tschofenig
Cc: <[email protected]>
Subject: Re: [OAUTH-WG] Alignment of JWT Claims and Token Introspection "Claims"
Hi Hannes, thanks for the feedback. Responses inline.
On Mar 3, 2015, at 5:56 AM, Hannes Tschofenig
<[email protected]<mailto:[email protected]>> wrote:
Hi Justin, Hi all,
in OAuth we provide two ways for a resource server to make an
authorization decision.
1) The resource server receives a self-contained token that contains all
the necessary information to make a local authorization decision. With
the JWT we have created such a standardized information and data model.
2) With an access request from a client the resource server asks the
authorization server for "help". The authorization server provides
information that help make the authorization decision. This is the token
introspection approach.
I believe the two approaches need to be aligned with regard to the
information and the data model. Since both documents already use JSON as
a way to encode information (=data model) and almost have an identical
information model (the data that is being passed around).
What needs to be done?
* Use the term 'claims' in both documents.
* Use the same registry (i.e., the registry established with the JWT).
* Register the newly defined claims from the token introspection
document in the claims registry.
We’ve already done this in the latest draft. Or at least, that’s the intent of
the current text — the registry is referenced and the new claims are
registered. Can you specifically point to places where this needs to be
improved upon?
Then, I have a few comments on the new claims that are proposed:
Here is the definition of the 'active' claim:
active
REQUIRED. Boolean indicator of whether or not the presented token
is currently active. The authorization server determines whether
and when a given token is in an active state.
This claim is not well-defined. You need to explain what "active" means.
It could, for example, mean that the token is not yet expired. Then,
there is of course the question why you are not returning the 'exp'
claim together with the 'nbf' claim.
The definition of “active” is really up to the authorization server, and I’ve
yet to hear from an actual implementor who’s confused by this definition. When
you’re the one issuing the tokens, you know what an “active” token means to
you. Still, perhaps we can be even more explicit, such as:
active
REQUIRED. Boolean indicator of whether or not the presented token is
currently active. The specifics of a token’s active state will vary depending
on the implementation of the authorization server, but generally this will
indicate that a given token has been issued by this authorization server, has
not been revoked by the resource owner, and is within its given time window of
validity (e.g. not expired).
Also, this is one of the places where the overlap between JWT and introspection
claims don’t make sense. It doesn’t make any sense for a JWT to carry an
“active” claim at all. Why would you have a JWT claim to be anything but
active? We should register it with the JWT registry to avoid name collisions,
but there’s nothing in the JWT registry that says “don’t use this inside of a
JWT”. Do you have any advice on how to address this?
client_id: What is the resource server going to do with the client_id?
What authorization decision could it make?
Whatever it wants to. If an RS can figure out something from the client_id, why
not let it? The client_id is a piece of information about the context of the
issuance of the token, and a common enough OAuth value for decision making.
I have a couple of reactions when I read the 'user_id' claim:
- I believe the inclusion of a user id field in the response could
lead to further confusion regarding OAuth access token usage for
authentication.
This isn’t any different from having a userinfo-endpoint equivalent (like
social graph or twitter API) and it’s got the same trouble.
- Since you define it as a human readable identifier I am wondering
whether you want to say something about the usage. Here it seems that it
might be used for displaying something on a webpage rather than making
an authorization decision but I might well be wrong.
We added in “user_id” to our implementation due to developer demand — they
wanted a username associated with the return value, but to leave the “sub”
value the same as that defined by OpenID Connect. Note that this is in an
environment where the username is a known quantity, and they’re not trying to
do cross-domain authentication. They just want to know whose token this was so
they can figure out whose data to return. It’s not used for display, but I
tried to make the definition in contrast to the machine-facing “sub” value.
- I am missing a discussion about the privacy implications of it.
While there is a privacy consideration section I am wondering what
controls the release of this sensitive information from the
authorization server to the resource server. While in some cases the two
parties might belong to the same organization but in other cases that
may not necessarily be true.
You’re correct, this is currently missing and I’ll add that in.
- In terms of the information exchanged about the user I am curious
about the usefulness of including other information as well, such as the
info that is included in an id token (see
http://openid.net/specs/openid-connect-core-1_0.html#IDToken). If this
has nothing to do with the ID token concept and the information carried
within it then I would add that remark.
You could introspect an ID token if you wanted to, but it’s usually easier to
just parse it yourself because it’s self-contained. The ID Token also extends
JWT, so there’s nothing stopping you from returning those claims as well.
However, note that the audience of the ID token is the OAuth *client* whereas
the targeted user of the introspection endpoint is the *protected resource*.
The PR isn’t going to see the ID Token most of the time, and the client’s not
going to need to (or be able to) introspect its tokens most of the time, so in
practice there’s not really any overlap.
— Justin
Ciao
Hannes
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