Re: [OAUTH-WG] JWT Secured Authorization Request (JAR) vs OIDC request object

[Takahiko Kawasaki <[e-mail]>]

Thank you, Justin. Actually, I wanted to see someone write a summary about
what happens in each combination from a viewpoint of both RP and AS with
regard to backward compatibility (as I told you in other channel just
before you posted your email ^_^).

So,

*(1) New Client + New Server*
No problem will happen.

*(2) New Client + Old Server*
*[Problem 2-1]* If an authorization request contains 'request' or
'request_uri' but doesn't have old mandatory request parameters
('client_id' and 'response_type') outside the request object, the request
is rejected.

*[Solution 2]* New Client should include the old mandatory request
parameters duplicately outside the request object. This means that New
Client should always send old mandatory request parameters duplicately
outside the request object if it wants to get maximum compatibility.

*(3) Old Client + New Server*
*[Problem 3-1]* If an authorization request contains 'request' or
'request_uri' and some "optional" request parameters are not included in
the request object, AS will interpret the request differently. Imagine what
happens when optional parameters such as 'scope', 'state', 'nonce',
'redirect_uri', 'response_mode', 'max_age', 'acr_values', 'code_challenge',
'code_challenge_method' and 'prompt' are not included in the request object
but present outside the request object.

*[Problem 3-2]* If an authorization request contains 'request' or
'request_uri' and some "mandatory" request parameters ('client_id' and
'response_type') are not included in the request object, the request is
rejected.

*[Solution 3]* Old Client should include all request parameters duplicately
in the request object. This means that Old Client should always include all
request parameters duplicately in the request object if it wants to get
maximum compatibility.

*(4) Old Client + Old Server*
No problem will happen.

- - -

>From a Client's point of view, for maximum compatibility, both Old and New
Clients should put mandatory request parameters outside the request object
and put all request parameters duplicately inside the request object.

[Problem 3-1] is difficult to detect because the authorization request is
not rejected. But, if New Server requires that all request parameters
outside the request object be put inside the request object duplicately,
[Problem 3-1] is handled as an error and thus client developers can detect
the problem.

Consequently, introducing the following requirement in "FAPI Part 2, 5.2.2
<https://openid.net/specs/openid-financial-api-part-2-ID2.html#authorization-server>,
10" to JAR seems a good compromise (as I told before)

shall require that all parameters are present inside the signed request
object passed in the request or request_uri parameter;


instead of just saying "the authorization server supporting this
specification MUST only use the parameters included in the request object."
which will bring about [Problem 3-1]. That is, how about adding a rule like
"if request parameters exist outside the request object, they must exist
inside the request object, too."?

Any thoughts?

Best,
Taka


On Fri, Jan 3, 2020 at 12:48 AM Justin Richer <[e-mail]> wrote:

> I think the nature of the backwards incompatibility is important here. The
> way that things are now, using merge-with-precedence, you have the
> following matrix of compatibility:
>
>
>              New Server  |  Old Server  |
> -----------+-------------+--------------+
> New Client |      YES    |      NO      |
> Old Client |      YES    |     YES      |
>
>
> If you ask me, this is the right balance for a breaking change. Old
> clients, where the vast majority of the code is, don’t have to change. New
> clients can only talk to servers with the new features, which is the
> ability to drop parameters from the external request. This would apply to
> both OIDC and plain OAuth.
>
> I think we should follow this kind of pattern in the discussions on OAuth
> 2.1, which I think JAR should be a part of/
>
>  — Justin
>
>
>
> On Jan 2, 2020, at 3:40 AM, Takahiko Kawasaki <[e-mail]> wrote:
>
> Breaking backward compatibility in this part would mean that OpenID
> Certification given to AS implementations with request_uri support will be
> invalidated once they support JAR. It also would mean that test cases in
> the official conformance suite need to be changed in a
> backward-incompatible manner, which would implicitly encourage that all
> certified implementations should re-try to get certification.
>
> Changing the spec now might need more three to six months, but it would be
> worth considering what we get and lose by saving the months and breaking
> backward compatibility.
>
> Best Regards,
> Taka
>
> On Wed, Dec 18, 2019 at 4:14 PM Nat Sakimura <[e-mail]> wrote:
>
>> So, no change is OK?
>>
>> On Wed, Dec 11, 2019 at 10:01 PM John Bradley <[e-mail]> wrote:
>>
>>> I also slightly prefer the merge approach.
>>>
>>> There are plusses and minuses to both.
>>>
>>> Changing again now that it is past ISEG review and backing out a Discuss
>>> will add another three to six months at this point, if we can get them to
>>> agree to the change.
>>>
>>> John B.
>>>
>>> On Tue, Dec 10, 2019, 11:29 PM Nat Sakimura <[e-mail]> wrote:
>>>
>>>> Correct. The WG supported the precedence approach and even merge just
>>>> like OIDC as it is very useful from the implementation point of view and
>>>> helps with a bunch of deployment patter.
>>>>
>>>> The push back came in from the Ben Campbell’s DISCUSS.
>>>> See
>>>>
>>>> https://bitbucket.org/Nat/oauth-jwsreq/issues/70/bc-the-current-text-actually-specifies-the
>>>>
>>>> I am willing to go either way as long as people agree. My slight
>>>> preference is to the original approach.
>>>>
>>>> Best,
>>>>
>>>> Nat Sakimura
>>>>
>>>> 2019年8月29日(木) 6:56 Brian Campbell <bcampbell=
>>>> [e-mail] <[e-mail]>
>>>> >:
>>>>
>>>>> FWIW, as best I can remember the change in question came as I result
>>>>> of directorate/IESG review rather than a WG decision/discussion.
>>>>> Which is likely why you can't find the "why" anywhere in the mailing list
>>>>> archive.
>>>>>
>>>>> On Wed, Aug 28, 2019 at 3:23 PM Filip Skokan <[e-mail]>
>>>>> wrote:
>>>>>
>>>>>> Well it kind of blows, doesn't it? I wasn't able to find the "why"
>>>>>> anywhere in the mailing list archive around the time this was changed.
>>>>>>
>>>>>> My take on satisfying both worlds looks like this
>>>>>>
>>>>>> - allow just JAR - no other params when possible.
>>>>>>     (which btw isn't possible to do with request_uri when enforcing
>>>>>> client based uri whitelist and the jwsreq 5.2.2 shows as much)
>>>>>> - enforce the "dupe behaviours" defined in OIDC (if response_type or
>>>>>> client_id is in request object it must either be missing or the same in
>>>>>> regular request).
>>>>>> - allows merging request object and regular parameters with request
>>>>>> object taking precedence since it is a very useful feature when having
>>>>>> pre-signed request object that's not one time use and clients using it wish
>>>>>> to vary state/nonce per-request.
>>>>>>
>>>>>> I wish the group reconsidered making this breaking change from OIDC's
>>>>>> take on request objects - allow combination of parameters from the request
>>>>>> object with ones from regular parameters (if not present in request object).
>>>>>>
>>>>>> S pozdravem,
>>>>>> *Filip Skokan*
>>>>>>
>>>>>>
>>>>>> On Wed, 28 Aug 2019 at 23:02, Brian Campbell <
>>>>>> [e-mail]> wrote:
>>>>>>
>>>>> Filip, for better or worse, I believe your assessment of the situation
>>>>>>> is correct. I know of one AS that didn't choose which of the two to follow
>>>>>>> but rather implemented a bit of a hybrid where it basically ignores
>>>>>>> everything outside of the request object per JAR but also checks for and
>>>>>>> enforces the presence and value of the few regular parameters (client_id,
>>>>>>> response_type) that OIDC mandates.
>>>>>>>
>>>>>>> On Tue, Aug 27, 2019 at 5:47 AM Filip Skokan <[e-mail]>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> Hello everyone,
>>>>>>>>
>>>>>>>> in an earlier thread I've posed the following question that might
>>>>>>>> have gotten missed, this might have consequences for the existing
>>>>>>>> implementations of Request Objects in OIDC implementations - its making
>>>>>>>> pure JAR requests incompatible with OIDC Core implementations.
>>>>>>>>
>>>>>>>> draft 14 of jwsreq (JAR) introduced this language
>>>>>>>>
>>>>>>>> The client MAY send the parameters included in the request object
>>>>>>>>> duplicated in the query parameters as well for the backward
>>>>>>>>> compatibility etc.
>>>>>>>>>
>>>>>>>>> *However, the authorization server supporting thisspecification
>>>>>>>>> MUST only use the parameters included in the requestobject. *
>>>>>>>>
>>>>>>>>
>>>>>>>> Server MUST only use the parameters in the Request Object even if
>>>>>>>>> the
>>>>>>>>> same parameter is provided in the query parameter.  The
>>>>>>>>> Authorization
>>>>>>>>
>>>>>>>>
>>>>>>>> The client MAY send the parameters included in the request object
>>>>>>>>> duplicated in the query parameters as well for the backward
>>>>>>>>> compatibility etc.
>>>>>>>>>
>>>>>>>>> *However, the authorization server supporting thisspecification
>>>>>>>>> MUST only use the parameters included in the requestobject.. *
>>>>>>>>
>>>>>>>>
>>>>>>>> Nat, John, everyone - *does this mean a JAR compliant AS ignores
>>>>>>>> everything outside of the request object while OIDC Request Object one
>>>>>>>> merges the two with the ones in the request object being used over ones
>>>>>>>> that are sent in clear?* The OIDC language also includes sections
>>>>>>>> which make sure that some required arguments are still passed outside of
>>>>>>>> the request object with the same value to make sure the request is "valid"
>>>>>>>> OAuth 2.0 request (client_id, response_type), something which an example in
>>>>>>>> the JAR spec does not do. Not having this language means that existing
>>>>>>>> authorization request pipelines can't simply be extended with e.g. a
>>>>>>>> middleware, they need to branch their codepaths.
>>>>>>>>
>>>>>>>> Is an AS required to choose which of the two it follows?
>>>>>>>>
>>>>>>>> Thank you for clarifying this in advance. I think if either the
>>>>>>>> behaviour is the same as in OIDC or different this should be called out in
>>>>>>>> the language to avoid confusion, especially since this already exists in
>>>>>>>> OIDC and likely isn't going to be read in isolation, especially because the
>>>>>>>> Request Object is even called out to be already in place in OIDC in the JAR
>>>>>>>> draft.
>>>>>>>>
>>>>>>>> Best,
>>>>>>>> *Filip*
>>>>>>>> _______________________________________________
>>>>>>>> OAuth mailing list
>>>>>>>> [e-mail]
>>>>>>>> https://www.ietf.org/mailman/listinfo/oauth
>>>>>>>>
>>>>>>>
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>>>> --
>>>> Nat Sakimura (=nat)
>>>> Chairman, OpenID Foundation
>>>> http://nat.sakimura.org/
>>>> @_nat_en
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>>
>> --
>> Nat Sakimura (=nat)
>> Chairman, OpenID Foundation
>> http://nat.sakimura.org/
>> @_nat_en
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