Re: [GNAP] [Txauth] Three Client-Server use cases with several ASs built along "Privacy by Design" (PbD)

[Dick Hardt <[e-mail]>]

Tom, do you have a straw man on how a client would interact with an AS on
the user's device?
ᐧ

On Tue, Aug 11, 2020 at 3:43 PM Tom Jones <[e-mail]>
wrote:

> I guess I need to ask the group as a whole then.
> Will GNAP support self-issued Identifiers?
> If so then the AS is on the user's device.
> I need to understand that SII are in-scope.
> Peace ..tom
>
>
> On Tue, Aug 11, 2020 at 3:40 PM Francis Pouatcha <[e-mail]> wrote:
>
>> On Tue, Aug 11, 2020 at 6:27 PM Tom Jones <[e-mail]>
>> wrote:
>>
>>> "The token request must not mention any reference of the RS."
>>> this cannot be an absolute rule. I have cases were the client needs to
>>> tell the user which they are coming back for additional grants.
>>> The reason is typically because a request by the client for data/access
>>> from the rs was rejected. The reason for the rejection is important for the
>>> client to make the case to the user for additional permissions.
>>> Peace ..tom
>>>
>> - If you want privacy, *don't* expose RS identity to AS.
>> - If you want transparency, expose RS identity to AS.
>> You can't have both.....
>> /Francis
>>
>>>
>>>
>>>
>>> On Tue, Aug 11, 2020 at 2:27 PM Francis Pouatcha <fpo=
>>> [e-mail]> wrote:
>>>
>>>> Hello Fabian,
>>>>
>>>> On Tue, Aug 11, 2020 at 2:17 AM Fabien Imbault <
>>>> [e-mail]> wrote:
>>>>
>>>>> Hi Francis,
>>>>>
>>>>> I think Denis points to the fact that, in the current situation, the
>>>>> AS receives the resource request from the Client and therefore knows what
>>>>> tokens are asked.
>>>>>
>>>> The token request must not mention any reference of the RS.
>>>>
>>>>
>>>>> Then it also implements the consent interface (and possibly the login
>>>>> too) and so it also knows who validates and what is accepted or not.
>>>>>
>>>> Decoupling this does not change the privacy context, as the AS issues
>>>> the Token. AS needs to add a reference to the RC in the token. SO AS can
>>>> correlate on StudentId anyway.
>>>>
>>>>
>>>>> I don't think the abstract flow deals with those privacy concerns.
>>>>>
>>>> To solve the privacy problem addressed in this thread, we need to go
>>>> the (SSI/DiD/VC) way. Then UNIV-0 (in his role of RS) will have to issue a
>>>> VC (Verifiable Credential) to the Student (in his role of RC). The Student
>>>> will then present this claim to UNIV-1 during his registration. In this
>>>> case we need no Grant negotiation and no AS.
>>>>
>>>> Best regards.
>>>> /Francis
>>>>
>>>>>
>>>>
>>>>>
>>>>> Then I agree with you on the audience field of the token, if left
>>>>> empty it simplifies part of the problem, although it removes a big part of
>>>>> the control you may want from directed tokens. That's why I'm willing to
>>>>> better develop the RS hiding idea.
>>>>>
>>>>> Fabien
>>>>>
>>>>> Le mar. 11 août 2020 à 05:58, Francis Pouatcha <fpo=
>>>>> [e-mail]> a écrit :
>>>>>
>>>>>> Hello Denis,
>>>>>>
>>>>>> what you describe in the use case seems to be the default behavior of
>>>>>> the protocol. Let me map it with this abstract protocol flow:
>>>>>>
>>>>>> +-----------+      +--------------+  +-----------+  +----+
>>>>>>  +---------------------+
>>>>>> | Requestor |      | Orchestrator |  | RS        |  | GS |  |
>>>>>> Resource Controller |
>>>>>> | is UNIV-1 |      |  is UNIV-1   |  | is UNIV-0 |  | or |  |
>>>>>>  is          |
>>>>>> |   Staff   |      | Registr. App |  | Server    |  | AS |  |
>>>>>>  Student       |
>>>>>> +-----------+      +--------------+  +-----------+  +----+
>>>>>>  +---------------------+
>>>>>>   |(1) RegisterStudent    |                |           |
>>>>>>   |
>>>>>>   |---------------------->|                |           |
>>>>>>   |
>>>>>>   |                       |(2)
>>>>>> RequestRecordIntent(RecordType,StudentId,
>>>>>>   |                       |
>>>>>>  OrchestratorId):AuthRequest[RecordType,StudentId]
>>>>>>   |                       |<-------------->|           |
>>>>>>   |
>>>>>>   |                       |                |           |
>>>>>>   |
>>>>>>   |                       |(3)
>>>>>> AuthZRequest(RecordType,StudentId,OrchestratorId)
>>>>>>   |                       |--------------------------->|
>>>>>>   |
>>>>>>   |                       |                |           |(4)
>>>>>> ConsentRequest(RecordType,
>>>>>>   |                       |                |           |
>>>>>>  OrchestratorId):Consent
>>>>>>   |                       |                |
>>>>>>  |<-------------->|
>>>>>>   |
>>>>>>  |(5) AuthZ[RecordType,StudentId,OrchestratorId]
>>>>>>   |                       |<---------------------------|
>>>>>>   |
>>>>>>   |                       |                |           |
>>>>>>   |
>>>>>>   |                       |(2)
>>>>>> RequestRecord(RecordType,StudentId,OrchestratorId)
>>>>>>   |                       |     :RecordOf[StudentId]   |
>>>>>>   |
>>>>>>   |                       |<-------------->|           |
>>>>>>   |
>>>>>>   |(7) Registered         |                |           |
>>>>>>   |
>>>>>>   |<----------------------|                |           |
>>>>>>   |
>>>>>>   +                       +                +           +
>>>>>>   +
>>>>>>
>>>>>> we assume the authz request sent by "Client" to "AS" describes the
>>>>>> protected resource without referring to the authz server. An AS can issue
>>>>>> the authz to release the graduation record  of a student
>>>>>> ((5) AuthZ[RecordType,StudentId,OrchestratorId]), without any reference to
>>>>>> the target university.
>>>>>>
>>>>>> What matters for this authz object is:
>>>>>> - StudentId: a reference to the student as known to the resource
>>>>>> server.
>>>>>> - RecordType: a reference to a resource of type graduation record as
>>>>>> understandable  by the resource server.
>>>>>> - OrchestratorId: reference to the Orchestrator. Can be used to bind
>>>>>> authz to Orchestrator..
>>>>>>
>>>>>> But:
>>>>>> - RS must trust AS issued token.
>>>>>> - StudentId must be known to RS, AS and Orchestrator.
>>>>>>
>>>>>> Therefore, the AS does not need to know the RS. Keep the audience
>>>>>> field empty.
>>>>>>
>>>>>> Same principle applies for the second use case.
>>>>>>
>>>>>> What privacy problem do you see here?
>>>>>>
>>>>>> Best regards.
>>>>>> /Francis
>>>>>>
>>>>>> On Tue, Aug 4, 2020 at 5:08 AM Denis <[e-mail]> wrote:
>>>>>>
>>>>>>> I tried my best twice to download three use cases in the Use cases
>>>>>>> directory, but I failed.
>>>>>>>
>>>>>>> Rather than failing a third time, here is the direct link of the
>>>>>>> second try:
>>>>>>>
>>>>>>>
>>>>>>> https://github.com/ietf-wg-gnap/general/wiki/Three-Client-Server-use-cases-with-several-ASs-built-along-%22Privacy-by-Design%22-(PbD)
>>>>>>>
>>>>>>> Denis
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
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>>>>>>> https://www.ietf.org/mailman/listinfo/txauth
>>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Francis Pouatcha
>>>>>> Co-Founder and Technical Lead
>>>>>> adorsys GmbH & Co. KG
>>>>>> https://adorsys-platform.de/solutions/
>>>>>> --
>>>>>> TXAuth mailing list
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>>>>>> https://www.ietf.org/mailman/listinfo/txauth
>>>>>>
>>>>>
>>>>
>>>> --
>>>> Francis Pouatcha
>>>> Co-Founder and Technical Lead
>>>> adorsys GmbH & Co. KG
>>>> https://adorsys-platform.de/solutions/
>>>> --
>>>> TXAuth mailing list
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>>>> https://www.ietf.org/mailman/listinfo/txauth
>>>>
>>>
>>
>> --
>> Francis Pouatcha
>> Co-Founder and Technical Lead
>> adorsys GmbH & Co. KG
>> https://adorsys-platform.de/solutions/
>>
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