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

Vladimir Dzhuvinov <vladimir@connect2id.com> Sat, 11 January 2020 09:17 UTC

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To: John Bradley <ve7jtb@ve7jtb.com>, Mike Jones <Michael.Jones@microsoft.com>
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From: Vladimir Dzhuvinov <vladimir@connect2id.com>
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Subject: Re: [OAUTH-WG] [EXTERNAL] Re: JWT Secured Authorization Request (JAR) vs OIDC request object
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Thanks Mike for the rfc7519 section-5.3
<https://tools.ietf.org/html/rfc7519#section-5.3> pointer. Can this
parameter replication be used for client_id or the client_id ass "iss"
even though it isn't explicitly mentioned in the JAR spec?

On 11/01/2020 02:58, John Bradley wrote:
> Right we just don't say to put the iss there in OIDC if it's
> symetricly encrypted.

OIDC doesn't have the symmetric key selection issue, I suppose that why
the possibility to replicate params to the JWE header isn't mentioned at
all. OIDC requires the top-level query params to represent a valid OAuth
2.0 request, and there client_id is required. If the client_id is
present the client registration together with any present client_secret
can be retrieved.

I reread the JAR spec, this is the only place that mentions handling of
symmetric JWE.

https://tools.ietf.org/html/draft-ietf-oauth-jwsreq-20#section-10.2

>    (b)  Verifying that the symmetric key for the JWE encryption is the
>         correct one if the JWE is using symmetric encryption.


Vladimir


>
> On Fri, Jan 10, 2020, 9:41 PM Mike Jones <Michael.Jones@microsoft.com
> <mailto:Michael.Jones@microsoft.com>> wrote:
>
>     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 <oauth-bounces@ietf.org
>     <mailto:oauth-bounces@ietf.org>> *On Behalf Of * John Bradley
>     *Sent:* Friday, January 10, 2020 2:15 PM
>     *To:* Vladimir Dzhuvinov <vladimir@connect2id.com
>     <mailto:vladimir@connect2id.com>>
>     *Cc:* IETF oauth WG <oauth@ietf.org <mailto:oauth@ietf.org>>
>     *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
>     <vladimir@connect2id.com <mailto:vladimir@connect2id.com>> 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
>         <vladimir@connect2id.com <mailto:vladimir@connect2id.com>>:
>         >>
>         >> 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
>         <ve7jtb@ve7jtb.com <mailto:ve7jtb@ve7jtb.com>>:
>         >>>> 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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-- 
Vladimir Dzhuvinov