[OpenID-Specs-eKYC-IDA] Usage of scopes and purposes when requesting verified claims

Jaap Francke jaap.francke at iwelcome.com
Mon May 11 14:38:23 UTC 2020

Hi Torsten, Achim and others

Resuming our previous email conversation….

On the topic of RP-specific scopes. Yes I’ve seen this in practice, maybe not in eIDAS context, but in general with OAuth, we have seen various situations where custom claims are requested via custom scopes, which may be RP specific. I think Achim’s proposal addresses my initial remark.

On the the topic of consent and legal aspects. I started drafting proposed texts and changes as you suggested and came to realize that in my view a claim may be requested for one or multiple purposes. GDPR mandates that legal grounds for processing need to be addressed at a granular level. Processing purposes should not be bundled.
The point from my previous email was to not make an assumption on how legal aspects are addressed in the protocol itself. So to facilitate both of ‘my’ requirements, I think the protocol should maybe allow for the following:
- RP can indicate for what purpose(s) it is requesting a (verified) claim
- The OP can indicate which purpose(s) it knows that are somehow ‘legally covered’ (which applies both to regular and verified claims)
- Instead of a processing purpose being a descriptive string, it could be a urn.
In response to Achim’s remark, I do believe that data protection details should be covered by a specification. The challenge is to not do so in a flexible way. Another option could be to take the whole concept of ‘purpose’ out of the spec, since it is not by definition related to the concept of VERIFIED claims.

So as a reult of these ideas of mine, I am proposing enhancements of the specifications as per ‘below'. I hope it makes sense (and also hope it is well formulated, not being a native speaker sometimes makes it a bit difficult for me to express myself clearly).

Kind regards,

Jaap Francke


SECTION 4.4 Lawful purposes Element
This specification defines a generic mechanism to add purposes to claims. Since both verified cliams and regular claims transfer personal data the purposes can be indicated for any of such claims.

The normative definition is given in the following.¶<https://openid.net/specs/openid-connect-4-identity-assurance-1_0.html#section-4-5>

lawful_purposes: Object or array containing one or more purposes for processing of a user's data by RP and for which the OP knows a lawful basis exists. A purpose may be a descriptive sentence or may be a urn for a previously established processing purpose.

Note: An OP may decide to provide a claim without knowledge of a lawfull basis for the specific user. The protocol does not mandate a specific devision of responsibilities over the OP and RP.

Note: User’s consent is a lawful basis. Another example may be a legal obligation for the RP.

Note: An RP and a OP may agree on a set of data processing purposes and refer to those using a urn. Part of tis agreement may be a their lawful bases, user’s consent on Privacy Policies and how to obtain consent, etc. At the urn, more generic details about the lawful basis may be made available, such as an indicator for the Data Controller (legally responsible entity), etc.


         "verification": {
            "trust_framework": “ial_example_gold"
            "family_name": "Meier",
            "birthdate": "0000-03-22"
      “lawful_purposes" : {
         "given_name" : {
            "To make communication look more personal"
         "birthdate" : {
            "To validate the user is an adult and parental responsibilities are not applicable",
            “The user has reached the age of majority"


This specification introduces the additional field purposes to allow an RP to state the purpose(s) for the transfer of a certain End-User Claim it is asking for. The field purposes can be a member value of each individually requested Claim. A Claim can have more than one associated purpose.<https://openid.net/specs/openid-connect-4-identity-assurance-1_0.html#section-5.1-9>

purposes: OPTIONAL. An array of string describing the purposes for obtaining a certain End-User Claim from the OP.

Each purpose MUST NOT be shorter than 3 characters or longer than 300 characters. If this rule is violated, the authentication request MUST fail and the OP return an error invalid_request to the RP. A purpose may be a descriptive sentence or may be a urn for a previously established processing purpose.

The OP MAY display one or more of the purposes on a user screen(s) in order to inform the user about the designated use of the data to be transferred. The lawful basis for the transfer of the personal data may differ for different implementations and the legal aspects are out of scope of this specification. A specific purpose may or may not require that the user’s consent is obtained by either OP or RP. If the parameter purpose is not present in the request, the OP MAY display a value that was pre-configured for the respective RP. For details on UI localization, see Section 8<https://openid.net/specs/openid-connect-4-identity-assurance-1_0.html#purpose>.



         "verification": {
            "trust_framework": null
               "purposes": [
                  "To make communication look more personal"
               "purposes": [
                  "To send you best wishes on your birthday”,
                  "To validate the user is an adult and parental responsibilities are not applicable"

On 1 May 2020, at 18:25, Torsten Lodderstedt <torsten at lodderstedt.net<mailto:torsten at lodderstedt.net>> wrote:

Hi Jaap,

On 1. May 2020, at 15:23, Jaap Francke <jaap.francke at iwelcome.com<mailto:jaap.francke at iwelcome.com>> wrote:

Hi Torsten,

Thanks for your reply. My comments are also inline.


The "OIDC for identity Assurance” specs introduce a number of claims, in addition to the ones specificied by OIDC core.
In OIDC Core, there are 2 mechanisms to request claims:
- one is by usage of OAuth-scopes, (section 5.4 of Core spec)
- one by usage of the “claims” parameter in the request. (section 5.5 of Core spec)
Section 5 of the OIDC—identity-assurance specs indicate the usage of the claims pararameter. This may suggest it’s the only mechanism to be used in the context of Identity Assurance.
My view is that also the ’scope’ mechanism should be supported and may even be preferred for certain use cases.
Please enhance the specification to be more explicit about usage of scopes as a means to request verified claims.

Usage of ’scope’ to request verified claims makes sense to me because in a typical “identity landscape” the requested claims do not vary on a request-by-request basis, but instead are a reflection of an RP’s functionality which can be rather static. By pre-defining/configuring scopes at the OP (potentially in terms of ’essential’, ’trust_framework’, etc..), the scope is essentially a profile of the claim request. This would not only simplify the protocol implementation both at the RP and OP side, but it would also make it easier for the OP to make the authorisation decision whether or not the RP will be granted the requested verified claims. 'It is at the discretion of the OP to decide whether the requested verification data is provided to the RP.’ Making this decision is much easier when a request includes a scope as a reference to a predefined profile of requested end-user claims and associated verification data. My suggestion is to consider including such a mechanism in the specifications.

What do you have in mind? I agree a certain RP or deployment could define scope values as short cut to request certain verified claims. However, the number and value range of verification elements + the number of end user claims creates is so big I cannot envision how the spec could define concrete scope values.

Yes, so what i had in mind is that the spec would acknowledge the practice of defining a ‘custom' scope value as shortcut to request certain claims. The current spec only mentions the ‘claims’ request parameter as mechanism to request claims, which I see as somewhat ambigous The spec could mention both mechanisms as valid options and leave it to the the implementor to make a choice which mechanism is more appropriate.
My preference is the ’scope’ approach, since it fits into what i see as a typical situation where the interaction between RP and OP has a more ’static’ nature.
I could imagine the spec even stating perceived pros&cons of both approaches. Claims approach gives a lot of flexibility to vary on a request-by-request basis. The scope approach is easier in situations where there is a ’static’ interaction between OP and RP; i.e. an RP may always want to receive the same set of claims, for the same data processing and purpose, etc.

I assume the interaction can be static for a certain RP with a certain OP. This would call for RP-specific scope values. Have you ever seen this in practice? I haven’t.

Additionally, the spec no longer defines values for trust frameworks, verification methods and evidence, i.e. there are unknown values from a spec perspective.

My second observation is about the optional ‘purpose’ parameter in a claims request. The specs state that the OP MUST display this purpose in the respective user consent screen(s) in order to inform the user about the designated use of the data to be transferred or the authorization to be approved. If the parameter purpose is not present in the request, the OP MAY display a value that was pre-configured for the respective RP.’
This part of the specification assumes or seems to imply that the user gets a consent screen every time that verified data is requested. I think that this is not realistic:
- it is common practice that certain consents are included in a Privacy Policy (PP) and/or Terms of Service (ToS). The user gives his consent once and the consent is persisted at the OP for future purposes.

Are you referring to ToS/PP of the RP or the OP?

Good question. I think it could be either one or maybe even both. My understanding of the European GDPR is that the OP may need the user’s consent to provide data to the RP and the RP needs a legal ground to collect a person’s data. This is assuming that RP and OP are different legal entities / Data Controllers. Different scenario’s can also be possible where OP and/or RP (from a legal perspecrive) could be Data Controller or Data Processor. Moreover, i think legal entities can even delegate the responsibility to get a user’s consent (if consent is the legal ground that is applicable)

- if not in PP or ToS, a consent screen may be presented only ‘once’ and the user’s consent is taken to be valid for the next 6 months (as an example)
- in some situations there are other legal grounds/reasons/purposes to request the claims and verification data. Besides ‘consent’, the European GDPR indicates other legal grounds (contract, vital interest, legal obligation, ..). When an RP asks for a verified claim, it may do so based on a legal obligation and the user’s consent would not be needed.
- Privacy regulations aim at situations where personal data is exchanged between legal entities (data controllers, data processors). From an IT perspective, the OP and the RP may be operated by the same entity (for example an Insurance company as data controller that is both the data controller for the OP and various RPs) so consent would not apply at the moment of requesting the claim. The consent should already have been given at the moment the personal data was provided to the OP.
My proposal would be that the ‘purpose’ could be a string (as per current specification) or a reference to a ‘purpose’ that has already been established somewhere. This approach makes it easier for the OP to make the decision to provide the requested data or not.

I agree the text is too strong. The purpose should be used to further inform the user in case a user consent screen is required. I will try to change the text accordingly.

Extending my previous replies, my suggestion would be that the eKYC standard would not ‘enforce’ or assume whatever particular legal set-up of responsibilities, but instead facilitate any legal context and/or interpretation.
I think the way to do so would be to include the possibility to include one or more references to types of data processing (‘purposes’) that should somehow be legally covered.
How this ‘legal cover’ is arranged for may vary per implementation:
- Is the OP Data Controller or Data Processer? Is the RP Data Controller or Data Processer?
- Does the intended data processing require the user’s consent or does one of the other legal grounds apply?
- Did RP and OP agree on some delegation about getting the user’s consent (if needed)?
In this way the protocol can facilitate any set-up in a transparant way, without making assumptions on legal reponsibilities at either OP and/or RP.

What does this mean to protocol constructs? Can you please suggest concrete changes/text?

Furthermore, it could be considered to extend the list of verification methods with the ones defined by NISTIR 8112.

You mean „Document Verification”, “Record Verification”, “Document Verification with Record Verification”, “Proof of Possession”, “Probabilistic Verification”, „Not Verified”? We could add this to our Wiki. May I ask you to add the values?

Yes that’s what I meant. I need to familiarize with the wiki.

You may find the existing definitions at https://bitbucket.org/openid/ekyc-ida/wiki/identifiers.

Let me know if you want to contribute changes, the I would give you the respective permissions.

best regards,

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