[Openid-specs-fapi] FAPI Profile and openid scope value

[Torsten Lodderstedt]

Hi Dave, 

in my opinion, the „openid" scope value was designed to exactly address the use case of providing the client with an user id (and further user claims). That’s why further claims can be requested via additional scope values and the claims parameter if the „openid" scope is present. 

So I’m rather reluctant to use another scope value to achieve the result I can today (w/o FAPI) achieve with any OpenID Connect OP. I would rather enhance the spec and state the signed authorization response (aka ID Token) can be triggered using a distinct response type (possible a new one), as response types can be freely defined in OAuth. 

kind regards,
Torsten. 

> Am 29.07.2018 um 07:36 schrieb Dave Tonge <dave.tonge at momentumft.co.uk>:
> 
> Hi Torsten
> 
> We have an issue open to make it more explicit about the `openid` scope value:
> https://bitbucket.org/openid/fapi/issues/149/make-it-clear-that-the-entire-flow-is-oidc
> 
> Your use-case is definitely valid and we've heard it a few times and definitely need a solution.
> 
> I'm hesitant to say that the hybrid flow should be able to be implemented without the `openid` scope value. My understanding is that many implementations of authorisation servers use the presence of `openid` in the scope to turn on all the OIDC related features such as: id tokens, hybrid flow, request object, claims parameter, stricter processing rules, etc.
> 
> Wouldn't it be better to use another `scope` value for the RP to indicate that it wants a long-lived end-user identifier (and possibly other claims), rather than an "ephemeral subject identifier". From a spec perspective using a scope value of `openid` doesn't' guarantee the RP that they will receive back a long-lived user identifier.
> 
> I agree with you that it would be better to handle both use cases from a single client.
> 
> What do you think about using another scope value?
> 
> Dave
> 
> 
> 
> 
> On Sat, 28 Jul 2018 at 13:58, Torsten Lodderstedt via Openid-specs-fapi <openid-specs-fapi at lists.openid.net> wrote:
> Hi all,
> 
> the "Read and Write API Security Profile" mandates the AS to use response type values "code id_token" or "code id_token token“ meaning an ID Token is provided in any case. In my understanding ID Token is primarily used to further secure the interaction, e.g. by providing the client with an iss claim used to detect mix-up.
> 
> Is it possible for the RP to use this functionality without the „openid" scope value? The reason I’m asking is I would like to let a RP/client differentiate use cases where it just wants to obtain an access token for API access but is not interested in the user id and use cases where the same client (now as RP) wants to obtain user id and further claims. Using the scope value „openid“ to differentiate those use cases seams straightforward to me. Otherwise the RP would need to use two different client ids with different sub claim policies for the different use cases, which most likely will cause complexity in the AS/OP's consent handling as I assume the RP would like to be the same legal entity in both cases.  
> 
> Thoughts? 
> 
> kind regards,
> Torsten. _______________________________________________
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> 
> -- 
> Dave Tonge
> CTO
> 
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