Hi Donald,

If you're pre-registering a client with a defined set of scopes, then Section 
3.3 of RFC 6749 applies: 
https://datatracker.ietf.org/doc/html/rfc6749#section-3.3 

Yours,
Emelia

> On 7 Aug 2026, at 23:34, [email protected] wrote:
> 
> Hi Frederick,
>  
> Thanks for your response.
> 
> Although scope is an optional parameter for an Authorization Code request, 
> the ESPI standard requires it.  The third-party registration process requires 
> that all scope profiles are defined as part of their registration process.  
> Therefore, shouldn’t the submission of a scope parameter that matches a 
> defined scope profile be validated, and, if incorrect, return an 
> ?error=invalid_scope response?
>  
> Best regards,
> Don
> Donald F. Coffin
> Founder/CTO
>  
> REMI Networks
> 2335 Dunwoody Crossing Suite E
> Dunwoody, GA 30338-8221
>  
> From: Frederik Krogsdal Jacobsen <[email protected]> 
> Sent: Friday, August 7, 2026 3:35 AM
> To: [email protected]
> Cc: [email protected]; Jeremy J. Roberts <[email protected]>; 
> Emelia S. <[email protected]>
> Subject: Re: [OAUTH-WG] Re: How to properly implement Section 4.1.2.1 
> Authorization Error Response for OAuth 2.x
>  
> Hi Donald,
>  
> I am not familiar with the NAESB ESPI standard, but if it does not use the 
> OpenID Connect standard, then IBM's argument regarding OpenID certification 
> is moot.
> OpenID Connect does not supersede OAuth 2.0, it merely profiles it for 
> certain purposes.
>  
> Regarding case 5, the OAuth 2.0 standard says the following in section 3.3:
>> The authorization server MAY fully or partially ignore the scope requested 
>> by the client, based on the authorization server policy or the resource 
>> owner's instructions. 
> This means that you can't expect an authorization server to provide the 
> invalid_scope parameter for any particular scope. The authorization server 
> controls its own policy for when it returns that error.
> As Emelia said, however, the NAESB ESPI could define a profile of OAuth 2.0 
> that provides this policy by defining the valid scopes  (and maybe it already 
> does; as I mentioned, I am not familiar with it).
> In that case, however, the question is not about compliance with OAuth 2.0, 
> but rather about compliance with the profile.
>  
> Cheers,
> Frederik
>  
> On Thu, 6 Aug 2026 at 19:43, Emelia S. 
> <[email protected] 
> <mailto:[email protected]>> wrote:
>> Also, Donald, the other thing that should be considered is the format of 
>> your scope strings: they're not individual scopes, but rather a payload 
>> that's parsed to infer some meaning. This means that the authorization 
>> server cannot advertise the scopes supported by that authorization server in 
>> the OAuth Authorization Server Metadata response (RFC8414).
>>  
>> I would strongly encourage NAESB ESPI to adopt Rich Authorization Requests 
>> (RFC9396) in the future, which are specifically designed for these sort of 
>> complex authorization requests, and where scope strings often fall short, 
>> since they're requiring an exact comparison.
>>  
>> For your test case 5, I assumed it was that the scope value was 
>> syntactically valid per the RFC, and that the scope was not supported by the 
>> authorization server, in which case invalid_scope or silently ignoring is 
>> correct. If you instead meant "the scope value does not parse according to 
>> NAESB ESPI's parsing logic", well, the specification for that would need to 
>> define what the correct behaviour is.
>>  
>> Rich Authorization Requests are still probably what you want instead of 
>> parsing a scope string as anything more than a space separated set of scopes.
>>  
>> — Emelia
>> 
>> 
>>> On 6 Aug 2026, at 18:30, [email protected] 
>>> <mailto:[email protected]> wrote:
>>>  
>>> I am the Technical Manager of the Green Button Alliance.  I am responsible 
>>> for certifying that electric, natural gas, and water utilities comply with 
>>> the North American Energy Standards (NAESB) Energy Service Provider 
>>> Interface (ESPI) standard and need a ruling from the IETF OAuth WG 
>>> regarding an issue that has arisen for Hydro One Networks, Inc.
>>> 
>>> Hydro One Networks, Inc., the largest electric utility in Ontario, Canada, 
>>> implemented the NAESB ESPI (a.k.a. Green Button) standard in 2023, which 
>>> uses the OAuth 2.0 standard for customers to authorize client applications 
>>> to access their energy data.  At the time, they were using an IBM Tivoli 
>>> Authorization Server, which fully complied with the Green Button Alliance 
>>> legislatively mandated certification test for Section 4.1.2.1.  
>>> Authorization Error Response.  They recently upgraded to the IBM Verify 
>>> Authorization Server, which no longer passes the same Section 4.1.2.1. 
>>> Authorization Error Response tests.  IBM has agreed to comply with the IETF 
>>> OAuth Working Group’s response to my questions.
>>> 
>>> The GBA Certification test platform currently submits the following invalid 
>>> Authorization Endpoint requests and expects the Authorization Server to 
>>> comply with Section 4.1.2.1. Authorization Error Response error messages: 
>>>  
>>> iTestID
>>> Label
>>> Test Name
>>> Query string
>>> Status Code
>>> Expected Error Message
>>> 0
>>> Case 0: no response_type
>>> Malformed Authorization Code Request (No response_type field-value)
>>> ?client_id=(client_id)&redirect_uri=(redirect_uri)&scope=(scope)&state=ee148ec2-9898-466e-a013-4dedf1eb3018
>>> 302/303
>>> ?error=invalid_request parameter and no or empty location header
>>> 1
>>> Case 1: no client_id
>>> Malformed Authorization Code Request (No client_id field-value)
>>> ?response_type=code&redirect_uri=(redirect_uri)&scope=(scope)&state=ee148ec2-9898-466e-a013-4dedf1eb3018
>>> 302/303
>>> ?error=invalid_request parameter and no or empty location header
>>> 2
>>> Case 2: invalid response_type
>>> Malformed Authorization Code Request (Invalid response_type field-value:
>>> ?response_type=badresponsetype& 
>>> client_id=(client_id)&redirect_uri=(redirect_uri)&scope=(scope)&state=ee148ec2-9898-466e-a013-4dedf1eb3018
>>> 302/303
>>> ?error=unsupported_response_type parameter and no or empty location header
>>> 3
>>> Case 3: invalid client_id
>>> Malformed Authorization Code Request (Invalid client_id field-value)
>>> ?response_type=code& 
>>> client_id=invalid_third_party&redirect_uri=(redirect_uri)&scope=(scope)&state=ee148ec2-9898-466e-a013-4dedf1eb3018
>>> 302/303
>>> ?error=unauthorized_client parameter and no or empty location header
>>> 4
>>> Case 4: invalid redirect_uri
>>> Malformed Authorization Code Request (Invalid redirect_uri field-value)
>>> ?response_type=code& 
>>> client_id=(client_id)&redirect_uri=https://services.greenbuttondata.org&scope=(scope)&state=ee148ec2-9898-466e-a013-4dedf1eb3018
>>>  
>>> <https://services.greenbuttondata.org&scope=(scope)&state=ee148ec2-9898-466e-a013-4dedf1eb3018/>
>>>       
>>> 302/303
>>> ?error=invalid_request parameter and no or empty location header
>>> 5
>>> Case 5: invalid scope
>>> Malformed Authorization Code Request (Invalid scope field-value)
>>> ?response_type=code& 
>>> client_id=(client_id)&redirect_uri=(redirect_uri)&scope=FB=????&state=ee148ec2-9898-466e-a013-4dedf1eb3018
>>> 302/303
>>> ?error=invalid_scope parameter and no or empty location header
>>> 
>>> All scope string values are application variable contents shown as () 
>>> entries if present.  Malformed values are shown as strings.  I do not test 
>>> for missing state= elements, although the NAESB ESPI standard requires them.
>>> 
>>> The following table contains the current response by the IBM Verify 
>>> Authorization Server for each of the above test cases:
>>> 
>>> iTestID
>>> Status Code
>>> Response
>>> 0
>>> 303
>>> https://cmdcert.greenbuttonalliance.org:8445/ThirdParty/espi/1_1/OAuthCallBack?error=unsupported_response_type&error_description=...
>>> 1
>>> 401
>>> The response included a full-screen HTML showing the error “CSIAQ0154E The 
>>> requested OAuth 2.0 Client does not exist”
>>> 2
>>> 303
>>> https://cmdcert.greenbuttonalliance.org:8445/ThirdParty/espi/1_1/OAuthCallBack?error=unsupported_response_type&error_description...
>>> 3
>>> 401
>>> The response included a full-screen HTML showing the error “CSIAQ0154E The 
>>> requested OAuth 2.0 Client does not exist”
>>> 4
>>> 400
>>> The response included a full-screen HTML showing the error “CSIAQ0167E The 
>>> redirection URI provided in the request is either invalid or does not match 
>>> any of the OAuth 2.0 Client’s pre-registered redirect URLs”
>>> 5
>>> 302
>>> https://...verify.ibm.com/idaas/mtfim/sps/idaas/login...
>>>  
>>> Note: 
>>> https://cmdcert.greenbuttonalliance.org:8445/ThirdParty/espi/1_1/OAuthCallback
>>>  is the value of the redirect_uri for all but the negative redirect_uri 
>>> tests
>>> 
>>> The IBM team indicated that case 5 (invalid scope): The OpenID Connect spec 
>>> allows ignoring unknown scopes vs. returning an invalid_scope error 
>>> (https://openid.net/specs/openid-connect-core-1_0.html#AuthRequest).  The 
>>> referenced section of the OpenID Connect standard is the Authentication 
>>> section, which is NOT what case 5 is testing.  However, Section 3.1.2.2. 
>>> Authentication Request Validation of the OpenID Connect specification 
>>> indicates the Authorization Server MUST validate all the OAuth 2.0 
>>> parameters according to the OAuth 2.0 specification.  That includes (2) 
>>> verifying that a scope parameter is present and contains the openid scope 
>>> value (If no openid scope value is present, the request may still be a 
>>> valid OAuth 2.0 request but is not an OpenID Connect request).
>>> The IBM team indicated that case 4 (invalid redirect): An OpenID Connect 
>>> certification has precedence over the IETF OAuth 2.0 RFC 6749 and 
>>> referenced their official OpenID Foundation cert test for invalid redirect 
>>> URI, which expects an error page, not a redirect 
>>> (https://www.certification.openid.net/log-detail.html?log=Lbzq5uCWSM1Sij3&public=true).
>>> The NAESB ESPI standard does not support the OpenID Connect standard, so we 
>>> contend that the IBM Verify team’s position that their OpenID Connect 
>>> server does not need to comply with the IETF RFC 6749 and 6750 standards is 
>>> a “red herring”.  For cases 0 and 2, they have demonstrated the ability to 
>>> support Section 4.1.2.4 Authorization Error Response properly.
>>> 
>>> The business issue and why I am submitting this email is that Hydro One 
>>> Networks, Inc. is required by Ontario legislation to be certified by the 
>>> Green Button Alliance as being in compliance with the NAESB ESPI standard.  
>>> Without that certification, Hydro One Networks, Inc. will face continuing 
>>> financial penalties from the Ontario Energy Board.
>>>  
>>>  
>>> Best regards,
>>> Don
>>> Donald F. Coffin
>>> Founder/CTO
>>>  
>>> REMI Networks
>>> 2335 Dunwoody Crossing Suite E
>>> Dunwoody, GA 30338-8221
>>>  
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