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

[Mike Jones <[e-mail]>]

The technique of replicating JWT claims that need to be publicly visible in an encrypted JWT in the header is defined at https://tools.ietf.org/html/rfc7519#section-5.3.  (Thanks to Dick Hardt for bringing this need to my attention as we were finishing the JWT spec.)

                                                       -- Mike

From: OAuth <[e-mail]> On Behalf Of John Bradley
Sent: Friday, January 10, 2020 2:15 PM
To: Vladimir Dzhuvinov <[e-mail]>
Cc: IETF oauth WG <[e-mail]>
Subject: [EXTERNAL] Re: [OAUTH-WG] JWT Secured Authorization Request (JAR) vs OIDC request object

The intent was to do that, but specs change once the OAuth WG and IESG get there hands on them.

Being backwards compatible with OIDC is not a compelling argument to the IESG.

We were mostly thinking of asymmetric encryption.

Specifying puting the issuer and or the audience in the headder has come up in the past but probably is not documented.

John B

On Fri, Jan 10, 2020, 6:29 PM Vladimir Dzhuvinov <[e-mail]<mailto:[e-mail]>> wrote:
Yes, putting the client_id into the JWE header is a way around the need
to have the client_id outside the JWE as top-level authZ request parameter.

Unfortunately this work around isn't mentioned anywhere, I just checked
the most recent draft-ietf-oauth-jwsreq-20.

Our DDoS attack mitigation (for OIDC request_uri) also relies on the
presence of client_id as top-level parameter, together with requiring
RPs to register their request_uri's (so that we don't need to build and
store an index of all request_uri's). I just had a look at "DDoS Attack
on the Authorization Server" and also realised the request_uri
registration isn't explicitly mentioned as attack prevention ("the
server should (a) check that the value of "request_uri" parameter does
not point to an unexpected location").

https://tools.ietf.org/html/draft-ietf-oauth-jwsreq-20#section-10.4.1<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftools.ietf.org%2Fhtml%2Fdraft-ietf-oauth-jwsreq-20%23section-10.4.1&data=02%7C01%7CMichael.Jones%40microsoft.com%7Cc470d4ec4bd14d481c0f08d7961a8abb%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637142913068793193&sdata=%2FvHVp68SN5CAHimqZ5jx93aOCIruxqLCRMUFCc5DSxc%3D&reserved=0>

To be honest, I feel quite bad about the situation with JAR we are in
now. For some reason I had the impression that OAuth JAR was going to be
the OIDC request / request_uri for general OAuth 2.0 use, as with other
OIDC bits that later became general purpose OAuth 2.0 specs.

I find it unfortunate I didn't notice this when I was reviewing the spec
in the past.

Vladimir


On 10/01/2020 22:39, Filip Skokan wrote:
> Vladimir,
>
> For that very case the payload claims may be repeated in the JWE protected header. An implementation wanting to handle this may look for iss/client_id there.
>
> Odesláno z iPhonu
>
>> 10. 1. 2020 v 21:19, Vladimir Dzhuvinov <[e-mail]<mailto:[e-mail]>>:
>>
>> I just realised there is one class of JARs where it's practially
>> impossible to process the request if merge isn't supported:
>>
>> The client submits a JAR encrypted (JWT) with a shared key. OIDC allows
>> for that and specs a method for deriving the shared key from the
>> client_secret:
>>
>> https://openid.net/specs/openid-connect-core-1_0.html#Encryption<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fopenid.net%2Fspecs%2Fopenid-connect-core-1_0.html%23Encryption&data=02%7C01%7CMichael.Jones%40microsoft.com%7Cc470d4ec4bd14d481c0f08d7961a8abb%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637142913068793193&sdata=soK9t7pzu504iILuDNFnG%2BMLxZPP2pN6ugEJ4ZOpqd4%3D&reserved=0>
>>
>> If the JAR is encrypted with the client_secret, and there is no
>> top-level client_id parameter, there's no good way for the OP to find
>> out which client_secret to get to try to decrypt the JWE. Unless the OP
>> keeps an index of all issued client_secret's.
>>
>>
>> OP servers which require request_uri registration
>> (require_request_uri_registration=true) and don't want to index all
>> registered request_uri's, also have no good way to process a request_uri
>> if the client_id isn't present as top-level parameter.
>>
>>
>> Vladimir
>>
>>
>>> On 10/01/2020 20:13, Torsten Lodderstedt wrote:
>>>
>>>>> Am 10.01.2020 um 16:53 schrieb John Bradley <[e-mail]<mailto:[e-mail]>>:
>>>> I think Torsten is speculating that is not a feature people use.
>>> I’m still trying to understand the use case for merging signed and unsigned parameters. Nat once explained a use case, where a client uses parameters signed by a 3rd party (some „certification authority“) in combination with transaction-specific parameters. Is this being done in the wild?
>>>
>>> PS: PAR would work with both modes.


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