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OAuth 2.0 Rich Authorization Requests
draft-ietf-oauth-rar-12

Document Type Active Internet-Draft (oauth WG)
Authors Torsten Lodderstedt , Justin Richer , Brian Campbell
Last updated 2022-05-05
Stream Internet Engineering Task Force (IETF)
Intended RFC status Proposed Standard
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Document shepherd Hannes Tschofenig
Shepherd write-up Show Last changed 2022-05-04
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Send notices to hannes.tschofenig@arm.com, Hannes.Tschofenig@gmx.net
draft-ietf-oauth-rar-12
Web Authorization Protocol                                T. Lodderstedt
Internet-Draft                                                   yes.com
Intended status: Standards Track                               J. Richer
Expires: 6 November 2022                             Bespoke Engineering
                                                             B. Campbell
                                                           Ping Identity
                                                              5 May 2022

                 OAuth 2.0 Rich Authorization Requests
                        draft-ietf-oauth-rar-12

Abstract

   This document specifies a new parameter authorization_details that is
   used to carry fine-grained authorization data in OAuth messages.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 6 November 2022.

Copyright Notice

   Copyright (c) 2022 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Conventions and Terminology . . . . . . . . . . . . . . .   4
   2.  Request parameter "authorization_details" . . . . . . . . . .   4
     2.1.  Authorization Details Types . . . . . . . . . . . . . . .   7
     2.2.  Common data fields  . . . . . . . . . . . . . . . . . . .   8
   3.  Authorization Request . . . . . . . . . . . . . . . . . . . .  11
     3.1.  Relationship to "scope" parameter . . . . . . . . . . . .  13
     3.2.  Relationship to "resource" parameter  . . . . . . . . . .  14
   4.  Authorization Response  . . . . . . . . . . . . . . . . . . .  14
   5.  Authorization Error Response  . . . . . . . . . . . . . . . .  14
   6.  Token Request . . . . . . . . . . . . . . . . . . . . . . . .  15
     6.1.  Comparing authorization details . . . . . . . . . . . . .  15
   7.  Token Response  . . . . . . . . . . . . . . . . . . . . . . .  18
     7.1.  Enriched authorization details in Token Response  . . . .  19
   8.  Token Error Response  . . . . . . . . . . . . . . . . . . . .  22
   9.  Resource Servers  . . . . . . . . . . . . . . . . . . . . . .  23
     9.1.  JWT-based Access Tokens . . . . . . . . . . . . . . . . .  23
     9.2.  Token Introspection . . . . . . . . . . . . . . . . . . .  25
   10. Metadata  . . . . . . . . . . . . . . . . . . . . . . . . . .  26
   11. Implementation Considerations . . . . . . . . . . . . . . . .  27
     11.1.  Using authorization details in a certain deployment  . .  27
     11.2.  Minimal product support  . . . . . . . . . . . . . . . .  28
     11.3.  Use of Machine-readable Type Schemas . . . . . . . . . .  28
     11.4.  Large requests . . . . . . . . . . . . . . . . . . . . .  29
   12. Security Considerations . . . . . . . . . . . . . . . . . . .  30
   13. Privacy Considerations  . . . . . . . . . . . . . . . . . . .  30
   14. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  31
   15. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  31
     15.1.  OAuth Parameters Registration  . . . . . . . . . . . . .  31
     15.2.  JSON Web Token Claims Registration . . . . . . . . . . .  31
     15.3.  OAuth Token Introspection Response . . . . . . . . . . .  32
     15.4.  OAuth Authorization Server Metadata  . . . . . . . . . .  32
     15.5.  OAuth Dynamic Client Registration Metadata . . . . . . .  32
     15.6.  OAuth Extensions Error registry  . . . . . . . . . . . .  33
   16. Normative References  . . . . . . . . . . . . . . . . . . . .  33
   17. Informative References  . . . . . . . . . . . . . . . . . . .  33
   Appendix A.  Additional Examples  . . . . . . . . . . . . . . . .  35
     A.1.  OpenID Connect  . . . . . . . . . . . . . . . . . . . . .  35
     A.2.  Remote Electronic Signing . . . . . . . . . . . . . . . .  37
     A.3.  Access to Tax Data  . . . . . . . . . . . . . . . . . . .  38
     A.4.  eHealth . . . . . . . . . . . . . . . . . . . . . . . . .  39
   Appendix B.  Document History . . . . . . . . . . . . . . . . . .  42
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  44

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1.  Introduction

   The OAuth 2.0 authorization framework [RFC6749] defines the parameter
   scope that allows OAuth clients to specify the requested scope, i.e.,
   the permission, of an access token.  This mechanism is sufficient to
   implement static scenarios and coarse-grained authorization requests,
   such as "give me read access to the resource owner's profile" but it
   is not sufficient to specify fine-grained authorization requirements,
   such as "please let me transfer an amount of 45 Euros to Merchant A"
   or "please give me read access to directory A and write access to
   file X".

   This specification introduces a new parameter authorization_details
   that allows clients to specify their fine-grained authorization
   requirements using the expressiveness of JSON data structures.

   For example, an authorization request for a credit transfer
   (designated as "payment initiation" in several open banking
   initiatives) can be represented using a JSON object like this:

   {
      "type": "payment_initiation",
      "locations": [
         "https://example.com/payments"
      ],
      "instructedAmount": {
         "currency": "EUR",
         "amount": "123.50"
      },
      "creditorName": "Merchant A",
      "creditorAccount": {
         "iban": "DE02100100109307118603"
      },
      "remittanceInformationUnstructured": "Ref Number Merchant"
   }

       Figure 1: Example authorization request for a credit transfer.

   This object contains detailed information about the intended payment,
   such as amount, currency, and creditor, that are required to inform
   the user and obtain her consent.  The AS and the respective RS
   (providing the payment initiation API) will together enforce this
   consent.

   For a comprehensive discussion of the challenges arising from new use
   cases in the open banking and electronic signing spaces see
   [transaction-authorization].

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   In addition to facilitating custom authorization requests, this
   specification also introduces a set of common data type fields for
   use across different APIs.

1.1.  Conventions and Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   This specification uses the terms "access token", "refresh token",
   "authorization server", "resource server", "authorization endpoint",
   "authorization request", "authorization response", "token endpoint",
   "grant type", "access token request", "access token response", and
   "client" defined by The OAuth 2.0 Authorization Framework [RFC6749].

2.  Request parameter "authorization_details"

   The request parameter authorization_details contains, in JSON
   notation, an array of objects.  Each JSON object contains the data to
   specify the authorization requirements for a certain type of
   resource.  The type of resource or access requirement is determined
   by the type field, which is defined as follow:

   type:  The type of authorization details as a string.  The value of
      the type field determines the allowable contents of the object
      which contains it.  This field is REQUIRED.

   This field MUST be compared using an exact byte match of the string
   value against known types by the AS.  The AS MUST ensure that there
   is no collision between different authorization details types that it
   supports.  The AS MUST NOT do any collation or normalization of data
   types during comparison.

   An authorization_details array MAY contain multiple entries of the
   same type.

   This example shows the specification of authorization details of type
   payment_initiation using the example data shown above:

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   [
      {
         "type": "payment_initiation",
         "actions": [
            "initiate",
            "status",
            "cancel"
         ],
         "locations": [
            "https://example.com/payments"
         ],
         "instructedAmount": {
            "currency": "EUR",
            "amount": "123.50"
         },
         "creditorName": "Merchant A",
         "creditorAccount": {
            "iban": "DE02100100109307118603"
         },
         "remittanceInformationUnstructured": "Ref Number Merchant"
      }
   ]

       Figure 2: Example authorization details for a credit transfer.

   This example shows a combined request asking for access to account
   information and permission to initiate a payment:

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   [
      {
         "type": "account_information",
         "actions": [
            "list_accounts",
            "read_balances",
            "read_transactions"
         ],
         "locations": [
            "https://example.com/accounts"
         ]
      },
      {
         "type": "payment_initiation",
         "actions": [
            "initiate",
            "status",
            "cancel"
         ],
         "locations": [
            "https://example.com/payments"
         ],
         "instructedAmount": {
            "currency": "EUR",
            "amount": "123.50"
         },
         "creditorName": "Merchant A",
         "creditorAccount": {
            "iban": "DE02100100109307118603"
         },
         "remittanceInformationUnstructured": "Ref Number Merchant"
      }
   ]

      Figure 3: Example authorization details for a combined request.

   The JSON objects with type fields of account_information and
   payment_initiation represent the different authorization details to
   be used by the AS to ask for consent.

   Note: The AS will make this data subsequently available to the
   respective resource servers (see Section 9).

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2.1.  Authorization Details Types

   Interpretation of the value of the type parameter, and the object
   fields that the type parameter allows, is under the control of the
   AS.  However, the value of the type parameter is also generally
   documented and intended to be used by developers, it is RECOMMENDED
   that API designers choose type values that are easily copied without
   ambiguity.  For example, some glyphs have multiple Unicode code
   points for the same visual character, and a developer could
   potentially type a different character than what the AS has defined.
   Possible means of reducing potential confusion are limiting the value
   to ASCII characters, providing a machine-readable listing of data
   type values, or instructing developers to copy and paste directly
   from the documentation.

   If an application or API is expected to be deployed across different
   servers, such as the case in an open standard, the API designer is
   RECOMMENDED to use a collision-resistant namespace under their
   control, such as a URI that the API designer controls.

   The following example shows how an implementation could utilize the
   namespace https://scheme.example.org/ to ensure collision-resistant
   type values.

   {
      "type": "https://scheme.example.org/files",
      "locations": [
         "https://example.com/files"
      ],
      "permissions": [
         {
            "path": "/myfiles/A",
            "access": [
               "read"
            ]
         },
         {
            "path": "/myfiles/A/X",
            "access": [
               "read",
               "write"
            ]
         }
      ]
   }

       Figure 4: Example for authorization details with a URL as type
                                identifier.

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2.2.  Common data fields

   This specification defines a set of common data fields that are
   designed to be usable across different types of APIs.  These data
   fields MAY be combined in different ways depending on the needs of
   the API.  All data fields are OPTIONAL for use by a given API
   definition.  The allowable values of all fields are determined by the
   API being protected.

   locations:  An array of strings representing the location of the
      resource or resource server.  These strings are typically URIs
      identifying the location of the RS.  This field can allow a client
      to specify a particular RS, as discussed in Section 12.
   actions:  An array of strings representing the kinds of actions to be
      taken at the resource.
   datatypes:  An array of strings representing the kinds of data being
      requested from the resource.
   identifier:  A string identifier indicating a specific resource
      available at the API.
   privileges:  An array of strings representing the types or levels of
      privilege being requested at the resource.

   When different common data fields are used in combination, the
   permissions the client requests is the cartesian product of the
   values.  That is to say, the object represents a request for all
   action values listed within the object to be used at all locations
   values listed within the object for all datatype values listed within
   the object.  In the following example, the client is requesting read
   and write access to both the contacts and photos belonging to
   customers in a customer_information API.  If this request is granted,
   the client would assume it would be able to use any combination of
   rights defined by the API, such as reading the photos and writing the
   contacts.

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   [
      {
         "type": "customer_information",
         "locations": [
            "https://example.com/customers"
         ],
         "actions": [
            "read",
            "write"
         ],
         "datatypes": [
            "contacts",
            "photos"
         ]
      }
   ]

    Figure 5: Example for authorization details with common data fields.

   If the client wishes to have finer control over its access, it can
   send multiple objects.  In this example, the client is asking for
   read access to the contacts and write access to the photos in the
   same API endpoint.  If this request is granted, the client would not
   be able to write to the contacts.

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   [
      {
         "type": "customer_information",
         "locations": [
            "https://example.com/customers"
         ],
         "actions": [
            "read"
         ],
         "datatypes": [
            "contacts"
         ]
      },
      {
         "type": "customer_information",
         "locations": [
            "https://example.com/customers"
         ],
         "actions": [
            "write"
         ],
         "datatypes": [
            "photos"
         ]
      }
   ]

        Figure 6: Example for authorization details with common data
                        fields in multiple objects.

   An API MAY define its own extensions, subject to the type of the
   respective authorization object.  It is anticipated that API
   designers will use a combination of common data fields defined in
   this specification as well as fields specific to the API itself.  The
   following non-normative example shows the use of both common and API-
   specific fields as part of two different fictitious API type values.
   The first access request includes the actions, locations, and
   datatypes fields specified here as well as the API-specific
   geolocation field.  The second access request includes the actions
   and identifier fields specified here as well as the API-specific
   currency fields.

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   [
      {
         "type":"photo-api",
         "actions":[
            "read",
            "write"
         ],
         "locations":[
            "https://server.example.net/",
            "https://resource.local/other"
         ],
         "datatypes":[
            "metadata",
            "images"
         ],
         "geolocation":[
            {
               "lat":-32.364,
               "lng":153.207
            },
            {
               "lat":-35.364,
               "lng":158.207
            }
         ]
      },
      {
         "type":"financial-transaction",
         "actions":[
            "withdraw"
         ],
         "identifier":"account-14-32-32-3",
         "currency":"USD"
      }
   ]

        Figure 7: Example for authorization details using common and
                           extension data fields.

   If this request is approved, the resulting access token's access
   rights will be the union of the requested types of access for each of
   the two APIs, just as above.

3.  Authorization Request

   The authorization_details authorization request parameter can be used
   to specify authorization requirements in all places where the scope
   parameter is used for the same purpose, examples include:

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   *  Authorization requests as specified in [RFC6749],
   *  Device Authorization Request as specified in [RFC8628],
   *  Backchannel Authentication Requests as defined in [OpenID.CIBA].

   In case of authorization requests as defined in [RFC6749],
   implementors MAY consider to use pushed authorization requests
   [RFC9126] to improve to security, privacy, and reliability of the
   flow.  See Section 12, Section 13, and Section 11.4 for details.

   Parameter encoding is determined by the respective context.  In the
   context of an authorization request according to [RFC6749], the
   parameter is encoded using the application/x-www-form-urlencoded
   format of the serialized JSON as shown in the following using the
   example from Section 2 (line breaks for display purposes only):

  GET /authorize?response_type=code
     &client_id=s6BhdRkqt3
     &state=af0ifjsldkj
     &redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb
     &code_challenge_method=S256
     &code_challenge=K2-ltc83acc4h0c9w6ESC_rEMTJ3bwc-uCHaoeK1t8U
     &authorization_details=%5B%7B%22type%22%3A%22account%5Finfo
     rmation%22%2C%22actions%22%3A%5B%22list%5Faccounts%22%2C%22
     read%5Fbalances%22%2C%22read%5Ftransactions%22%5D%2C%22loca
     tions%22%3A%5B%22https%3A%2F%2Fexample%2Ecom%2Faccounts%22%
     5D%7D%2C%7B%22type%22%3A%22payment%5Finitiation%22%2C%22act
     ions%22%3A%5B%22initiate%22%2C%22status%22%2C%22cancel%22%5
     D%2C%22locations%22%3A%5B%22https%3A%2F%2Fexample%2Ecom%2Fp
     ayments%22%5D%2C%22instructedAmount%22%3A%7B%22currency%22%
     3A%22EUR%22%2C%22amount%22%3A%22123%2E50%22%7D%2C%22credito
     rName%22%3A%22Merchant%20A%22%2C%22creditorAccount%22%3A%7B%
     22iban%22%3A%22DE02100100109307118603%22%7D%2C%22remittance
     InformationUnstructured%22%3A%22RefNumberMerchant%22%7D%5D HTTP/1.1
  Host: server.example.com

   Figure 8: Example authorization request with authorization_details.

   Based on the data provided in the authorization_details parameter the
   AS will ask the user for consent to the requested access permissions.

   Note: the user may also grant a subset of the requested authorization
   details.

   In this example, the client wants to get access to account
   information and intiate a payment:

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   [
      {
         "type": "account_information",
         "actions": [
            "list_accounts",
            "read_balances",
            "read_transactions"
         ],
         "locations": [
            "https://example.com/accounts"
         ]
      },
      {
         "type": "payment_initiation",
         "actions": [
            "initiate",
            "status",
            "cancel"
         ],
         "locations": [
            "https://example.com/payments"
         ],
         "instructedAmount": {
            "currency": "EUR",
            "amount": "123.50"
         },
         "creditorName": "Merchant A",
         "creditorAccount": {
            "iban": "DE02100100109307118603"
         },
         "remittanceInformationUnstructured": "Ref Number Merchant"
      }
   ]

                Figure 9: URL decoded authorization details.

3.1.  Relationship to "scope" parameter

   authorization_details and scope can be used in the same authorization
   request for carrying independent authorization requirements.

   Combined use of authorization_details and scope is supported by this
   specification in part to allow existing OAuth-based applications to
   incrementally migrate towards using authorization_details
   exclusively.  It is RECOMMENDED that a given API use only one form of
   requirement specification.

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   The AS MUST consider both sets of requirements in combination with
   each other for the given authorization request.  The details of how
   the AS combines these parameters are specific to the APIs being
   protected and outside the scope of this specification.

   When gathering user consent, the AS MUST present the merged set of
   requirements represented by the authorization request.

   If the resource owner grants the client the requested access, the AS
   will issue tokens to the client that are associated with the
   respective authorization_details (and scope values, if applicable).

3.2.  Relationship to "resource" parameter

   The resource authorization request parameter as defined in [RFC8707]
   can be used to further determine the resources where the requested
   scope can be applied.  The resource parameter does not have any
   impact on the way the AS processes the authorization_details
   authorization request parameter.

4.  Authorization Response

   This specification does not define extensions to the authorization
   response.

5.  Authorization Error Response

   The AS MUST refuse to process any unknown authorization details type
   or authorization details not conforming to the respective type
   definition.  The AS MUST abort processing and respond with an error
   invalid_authorization_details to the client if any of the following
   are true of any of the objects in authorization_details structure:

   *  Contains an unknown authorization details type value,
   *  An object of known type but containing unknown fields,
   *  Contains fields of the wrong type for the authorization details
      type,
   *  Contains fields with invalid values for the authorization details
      type, or
   *  Missing required fields for the authorization details type.

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6.  Token Request

   The authorization_details token request parameter can be used to
   specify the authorization details a client wants the AS to assign to
   an access token.  The AS checks whether the underlying grant (in case
   of grant types authorization_code, refresh_token, ...) or the
   client's policy (in case of grant type client_credential) allows the
   issuance of an access token with the requested authorization details.
   Otherwise, the AS refuses the request with the error code
   invalid_authorization_details (similar to invalid_scope).

6.1.  Comparing authorization details

   Many actions in the OAuth protocol allow the AS and RS to make
   security decisions based on whether or not the request is asking for
   "more" or "less" than a previous, existing request.  For example,
   upon refreshing a token, the client can ask for a new access token
   with "fewer permissions" than had been previously authorized by the
   resource owner.  Since the nature of an authorization details request
   is based solely on the API or APIs that it is describing, there is
   not a simple means of comparing any two arbitrary authorization
   details requests.  Authorization servers should not rely on simple
   object comparison in most cases, as the intersection of some fields
   within a request could have side effects on the access rights
   granted, depending on how the API has been designed and deployed.
   This is a similar effect to the scope values used with some APIs.

   However, when comparing a new request to an existing request,
   authorization servers can use the same processing techniques as used
   in granting the request in the first place to determine if a resource
   owner needs to authorize the request.  The details of this comparison
   are dependent on the definition of the type of authorization request
   and outside the scope of this specification, but common patterns can
   be applied.

   This shall be illustrated using our running example.  The example
   authorization request in Section 3, if approved by the user, resulted
   in the issuance of an authorization code associated with the
   privileges to

   *  list accounts
   *  access the balance of one or more accounts,
   *  access the transactions of one or more accounts, and
   *  to initiate a payment.

   The client could now request the AS to issue an access token assigned
   with the privilege to just access a list of accounts as follows:

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   [
      {
         "type": "account_information",
         "actions": [
            "list_accounts"
         ],
         "locations": [
            "https://example.com/accounts"
         ]
      }
   ]

      Figure 10: Example for authorization details reduced privileges.

   The example API is designed such that each field used by the
   account_information type contains additive rights, with each value
   within the actions and locations arrays specifying a different
   element of access.  To make a comparison in this instance, the AS
   would perform the following steps:

   *  compare that the authorization code issued in the previous step
      contains an authorization details object of type
      account_information
   *  compare whether the approved list of actions contains
      list_account, and
   *  whether the locations value includes only previously-approved
      locations.

   If all checks succeed, the AS would issue the requested access token
   with the reduced set of access.

   Note that this comparison is relevant to this specific API type
   definition.  A different API type definition could have different
   processing rules.  For example, the value of an action could subsume
   the rights associated with another action value.  For example, if a
   client initially asks for a token with write access, which implies
   both read and write access to this API:

   [
       {
           "type": "example_api",
           "actions": [
               "write"
           ]
       }
   ]

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      Figure 11: Example for authorization details requesting "write"
                             access to an API.

   Later that same client makes a refresh request for read access:

   [
       {
           "type": "example_api",
           "actions": [
               "read"
           ]
       }
   ]

       Figure 12: Example for authorization details requesting "read"
                             access to an API.

   The AS would compare the type value and the action value to determine
   that the read access is already covered by the write access
   previously granted to the client.

   This same API could be designed with a possible value for privileges
   of admin, used in this example to denote that the resulting token is
   allowed to perform any functions on the resources.  If that client is
   then granted such admin privileges to the API:

   [
       {
           "type": "example_api",
           "privileges": [
               "admin"
           ]
       }
   ]

      Figure 13: Example for authorization details requesting "admin"
                             access to an API.

   The AS would compare the type value and find the privileges value
   subsumes any aspects of read or write access that had been granted to
   the client previously.  Note that other API definitions can use
   privileges in a non-subsuming fashion.

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   The next example shows how the client can use the common data element
   locations (see Section 2.2) to request the isaunce of an access token
   restricted to a certain resource server.  In our running example, the
   client may ask for all permissions of the approved grant of type
   payment_iniation applicable to the resource server residing at
   https://example.com/payments as follows:

   [
      {
         "type": "payment_initiation",
         "locations": [
            "https://example.com/payments"
         ]
      }
   ]

         Figure 14: Example for authorization details requesting an
                     audience restricted access token.

7.  Token Response

   In addition to the token response parameters as defined in [RFC6749],
   the authorization server MUST also return the authorization details
   as granted by the resource owner and assigned to the respective
   access token.

   The authorization details assigned to the access token issued in a
   token response are determined by the authorization_details parameter
   of the corresponding token request.  If the client does not specify
   the authorization_details token request parameters, the AS determines
   the resulting authorization details at its discretion.  The
   authorization server MAY consider the values of other parameters such
   as resource and scope if they are present during this processing, and
   the details of such considerations are outside the scope of this
   specification.

   The AS MAY omit values in the authorization_details to the client in
   the token Response if these are deemed of no intended use for the
   client.

   For our running example, this would look like this:

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   HTTP/1.1 200 OK
   Content-Type: application/json
   Cache-Control: no-store

   {
      "access_token": "2YotnFZFEjr1zCsicMWpAA",
      "token_type": "example",
      "expires_in": 3600,
      "refresh_token": "tGzv3JOkF0XG5Qx2TlKWIA",
      "authorization_details": [
         {
            "type": "https://scheme.example.com/payment_initiation",
            "actions": [
               "initiate",
               "status",
               "cancel"
            ],
            "locations": [
               "https://example.com/payments"
            ],
            "instructedAmount": {
               "currency": "EUR",
               "amount": "123.50"
            },
            "creditorName": "Merchant A",
            "creditorAccount": {
               "iban": "DE02100100109307118603"
            },
            "remittanceInformationUnstructured": "Ref Number Merchant"
         }
      ]
   }

                     Figure 15: Example token response.

7.1.  Enriched authorization details in Token Response

   The authorization details attached to the access token MAY differ
   from what the client requests.  In addition to the user authorizing
   less than what the client requested, there are use cases where the
   authorization server enriches the data in an authorization details
   object.  For example, a client may ask for access to account
   information but leave the decision about the accounts it will be able
   to access to the user.  The user would select the sub set of accounts
   they want the client to entitle to access in the course of the
   authorization process.  As one design option to convey the selected
   accounts, the authorization server could add this information to the
   respective authorization details object.

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   As an example, the requested authorization detail parameter could
   look like this:

   "authorization_details": [
      {
         "type": "account_information",
         "access": {
            "accounts": [],
            "balances": [],
            "transactions": []
         },
         "recurringIndicator":true
      }
   ]

          Figure 16: Example for requested authorization details.

   The authorization server then would expand the authorization details
   object and add the respective account identifiers.

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   HTTP/1.1 200 OK
   Content-Type: application/json
   Cache-Control: no-store

   {
      "access_token":"2YotnFZFEjr1zCsicMWpAA",
      "token_type":"example",
      "expires_in":3600,
      "refresh_token":"tGzv3JokF0XG5Qx2TlKWIA",
      "authorization_details":[
         {
            "type":"account_information",
            "access":{
               "accounts":[
                  {
                     "iban":"DE2310010010123456789"
                  },
                  {
                     "maskedPan":"123456xxxxxx1234"
                  }
               ],
               "balances":[
                  {
                     "iban":"DE2310010010123456789"
                  }
               ],
               "transactions":[
                  {
                     "iban":"DE2310010010123456789"
                  },
                  {
                     "maskedPan":"123456xxxxxx1234"
                  }
               ]
            },
            "recurringIndicator":true
         }
      ]
   }

           Figure 17: Example for enriched authorization details.

   For another example, the client is asking for access to a medical
   record but does not know the record number at request time.  In this
   example, the client specifies the type of access it wants but doesn't
   specify the location or identifier of that access.

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   {
   "authorization_details": [
      {
         "type": "medical_record",
         "sens": [ "HIV", "ETH", "MART" ],
         "actions": [ "read" ],
         "datatypes": [ "Patient", "Observation", "Appointment" ]
      }
   ]}

          Figure 18: Example for requested authorization details.

   When the user interacts with the AS, they select which of the medical
   records they are responsible for giving to the client.  This
   information gets returned with the access token.

   {
      "access_token":"2YotnFZFEjr1zCsicMWpAA",
      "token_type":"example",
      "expires_in":3600,
      "refresh_token":"tGzv3JokF0XG5Qx2TlKWIA",
      "authorization_details":[
       {
         "type": "medical_record",
         "sens": [ "HIV", "ETH", "MART" ],
         "actions": [ "read" ],
         "datatypes": [ "Patient", "Observation", "Appointment" ],
         "identifier": "patient-541235",
         "locations": [ "https://records.example.com/" ]
        }
     ]
   }

           Figure 19: Example for enriched authorization details.

   Note: the client needs to be aware upfront of the possibility that a
   certain authorization details object can be enriched.  It is assumed
   that this property is part of the definition of the respective
   authorization details type.

8.  Token Error Response

   The AS MUST refuse to process any unknown authorization details type
   or authorization details not conforming to the respective type
   definition.  If any of the objects in authorization_details contains
   an unknown authorization details type or an object of known type but
   containing unknown fields or fields of the wrong type, fields with
   invalid values, or if required fields are missing, the AS MUST abort

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   processing and respond with an error invalid_authorization_details to
   the client.

9.  Resource Servers

   In order to enable the RS to enforce the authorization details as
   approved in the authorization process, the AS MUST make this data
   available to the RS.  The AS MAY add the authorization_details field
   to access tokens in JWT format or to Token Introspection responses.

9.1.  JWT-based Access Tokens

   If the access token is a JWT [RFC7519], the AS is RECOMMENDED to add
   the authorization_details object, filtered to the specific audience,
   as a top-level claim.

   The AS will typically also add further claims to the JWT the RS
   requires for request processing, e.g., user id, roles, and
   transaction-specific data.  What claims the particular RS requires is
   defined by the RS-specific policy with the AS.

   The following shows the contents of an example JWT for the payment
   initiation example above:

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   {
      "iss": "https://as.example.com",
      "sub": "24400320",
      "aud": "a7AfcPcsl2",
      "exp": 1311281970,
      "acr": "psd2_sca",
      "txn": "8b4729cc-32e4-4370-8cf0-5796154d1296",
      "authorization_details": [
         {
            "type": "https://scheme.example.com/payment_initiation",
            "actions": [
               "initiate",
               "status",
               "cancel"
            ],
            "locations": [
               "https://example.com/payments"
            ],
            "instructedAmount": {
               "currency": "EUR",
               "amount": "123.50"
            },
            "creditorName": "Merchant A",
            "creditorAccount": {
               "iban": "DE02100100109307118603"
            },
            "remittanceInformationUnstructured": "Ref Number Merchant"
         }
      ],
      "debtorAccount": {
         "iban": "DE40100100103307118608",
         "user_role": "owner"
      }
   }

      Figure 20: Example for authorization details in JWT-based access
                                   token.

   In this case, the AS added the following example claims to the JWT-
   based access token:

   *  sub: conveys the user on which behalf the client is asking for
      payment initiation
   *  txn: transaction id used to trace the transaction across the
      services of provider example.com
   *  debtorAccount: API-specific field containing the debtor account.
      In the example, this account was not passed in the authorization
      details but selected by the user during the authorization process.

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      The field user_role conveys the role the user has with respect to
      this particular account.  In this case, they are the owner.  This
      data is used for access control at the payment API (the RS).

9.2.  Token Introspection

   Token introspection [!@RFC7662] provides a means for an RS to inquire
   to the AS what a given access token is good for.  The token
   introspection response provides the RS with the authorization details
   applicable to it as a top-level JSON element along with the claims
   the RS requires for request processing.  The authorization_details
   member contains the same structure defined in Section 2, potentially
   filtered and extended for the RS making the introspection request.

   Here is an example for the payment initiation example RS:

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   {
      "active": true,
      "sub": "24400320",
      "aud": "s6BhdRkqt3",
      "exp": 1311281970,
      "acr": "psd2_sca",
      "txn": "8b4729cc-32e4-4370-8cf0-5796154d1296",
      "authorization_details": [
         {
            "type": "https://scheme.example.com/payment_initiation",
            "actions": [
               "initiate",
               "status",
               "cancel"
            ],
            "locations": [
               "https://example.com/payments"
            ],
            "instructedAmount": {
               "currency": "EUR",
               "amount": "123.50"
            },
            "creditorName": "Merchant123",
            "creditorAccount": {
               "iban": "DE02100100109307118603"
            },
            "remittanceInformationUnstructured": "Ref Number Merchant"
         }
      ],
      "debtorAccount": {
         "iban": "DE40100100103307118608",
         "user_role": "owner"
      }
   }

       Figure 21: Example for authorization details in introspection
                                 response.

10.  Metadata

   The AS publishes the list of authorization details types it supports
   using the metadata parameter authorization_details_types_supported,
   which is a JSON array.

   This is illustrated by the following example:

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   {
      ...
      "authorization_details_types_supported":[
         "payment_initiation",
         "account_information"
      ]
   }

    Figure 22: Example for server metadata about authorization details.

   Clients announce the authorization details types they use in the new
   dynamic client registration parameter authorization_details_types.

   This is illustrated by the following example:

   {
      ...
      "authorization_details_types":[
         "payment_initiation"
      ]
   }

    Figure 23: Example for server metadata about authorization details.

   The registration of authorization details types with the AS is out of
   scope of this specification.

11.  Implementation Considerations

11.1.  Using authorization details in a certain deployment

   Using authorization details in a certain deployment will require the
   following steps:

   *  Define authorization details types
   *  Publish authorization details types in the OAuth server metadata
   *  Determine how authorization details are shown to the user in the
      user consent
   *  (if needed) Enrich authorization details in the user consent
      process (e.g. add selected accounts or set expirations)
   *  (if needed) Determine how authorization details are reflected in
      access token content or introspection responses
   *  Determine how the resource server(s) process(s) the authorization
      details or token data derived from authorization details

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11.2.  Minimal product support

   Products supporting this specification should provide the following
   basic functions:

   *  Support advertisement of supported authorization details types in
      OAuth server metadata
   *  Accept authorization_details parameter in authorization requests
      including basic syntax check for compliance with this
      specification
   *  Support storage of consented authorization details as part of a
      grant
   *  Implement default behavior for adding authorization details to
      access tokens and token introspection responses in order to make
      them available to resource servers (similar to scope values).
      This should work with any grant type, especially
      authorization_code and refresh_token.

   Processing and presentation of authorization details will vary
   significantly among different authorization details types.  Products
   should therefore support customization of the respective behavior.
   In particular, products should

   *  allow deployments to determine presentation of the authorization
      details
   *  allow deployments to modify requested authorization details in the
      user consent process, e.g. adding fields
   *  allow deployments to merge requested and pre-existing
      authorization details

   One option would be to have a mechanism allowing the registration of
   extension modules, each of them responsible for rendering the
   respective user consent and any transformation needed to provide the
   data needed to the resource server by way of structured access tokens
   or token introspection responses.

11.3.  Use of Machine-readable Type Schemas

   Products might allow deployments to use machine-readable schema
   languages for defining authorization details types to facilitate
   creating and validating authorization details objects against such
   schemas.  For example, if an authorization details type were defined
   using JSON Schemas [JSON.Schema], the JSON schema id could be used as
   type value in the respective authorization details objects.

   Note however that type values are identifiers understood by the AS
   and, to the extent necessary, the client and RS.  This specification
   makes no assumption that a type value point to a machine-readable

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   schema format, or that any party in the system (such as the client,
   AS, or RS) dereference or process the contents of the type field in
   any specific way.

11.4.  Large requests

   Authorization request URIs containing authorization details in a
   request parameter or a request object can become very long.
   Implementers should therefore consider using the request_uri
   parameter as defined in [RFC9101] in combination with the pushed
   request object mechanism as defined in [RFC9126] to pass
   authorization details in a reliable and secure manner.  Here is an
   example of such a pushed authorization request that sends the
   authorization request data directly to the AS via an HTTPS-protected
   connection:

     POST /as/par HTTP/1.1
     Host: as.example.com
     Content-Type: application/x-www-form-urlencoded
     Authorization: Basic czZCaGRSa3F0Mzo3RmpmcDBaQnIxS3REUmJuZlZkbUl3

     response_type=code&
     client_id=s6BhdRkqt3
     &state=af0ifjsldkj
     &redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb
     &code_challenge_method=S256
     &code_challenge=K2-ltc83acc4h0c9w6ESC_rEMTJ3bwc-uCHaoeK1t8U
     &authorization_details=%5B%7B%22type%22%3A%22account_information%22
     %2C%22actions%22%3A%5B%22list_accounts%22%2C%22read_balances%22%2C%
     22read_transactions%22%5D%2C%22locations%22%3A%5B%22https%3A%2F%2Fe
     xample.com%2Faccounts%22%5D%7D%2C%7B%22type%22%3A%22payment_initiat
     ion%22%2C%22actions%22%3A%5B%22initiate%22%2C%22status%22%2C%22canc
     el%22%5D%2C%22locations%22%3A%5B%22https%3A%2F%2Fexample.com%2Fpaym
     ents%22%5D%2C%22instructedAmount%22%3A%7B%22currency%22%3A%22EUR%22
     %2C%22amount%22%3A%22123.50%22%7D%2C%22creditorName%22%3A%22Merchan
     t123%22%2C%22creditorAccount%22%3A%7B%22iban%22%3A%22DE021001001093
     07118603%22%7D%2C%22remittanceInformationUnstructured%22%3A%22Ref%2
     0Number%20Merchant%22%7D%5D

   Figure 24: Example for large request including authorization details.

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12.  Security Considerations

   Authorization details are sent through the user agent in case of an
   OAuth authorization request, which makes them vulnerable to
   modifications by the user.  If integrity of the authorization details
   is a concern, clients MUST protect authorization details against
   tampering and swapping.  This can be achieved by signing the request
   using signed request objects as defined in [RFC9101] or using the
   request_uri authorization request parameter as defined in [RFC9101]
   in conjunction with [RFC9126] to pass the URI of the request object
   to the authorization server.

   All strings MUST be compared using the exact byte representation of
   the characters as defined by [RFC8259].  This is especially true for
   the type field, which dictates which other fields and functions are
   allowed in the request.  The server MUST NOT perform any form of
   collation, transformation, or equivalence on the string values.

   The common data field locations allows a client to specify where it
   intends to use a certain authorization, i.e., it is possible to
   unambiguously assign permissions to resource servers.  In situations
   with multiple resource servers, this prevents unintended client
   authorizations (e.g. a read scope value potentially applicable for an
   email as well as a cloud service) through audience restriction.

13.  Privacy Considerations

   Implementers MUST design and use authorization details in a privacy-
   preserving manner.

   Any sensitive personal data included in authorization details MUST be
   prevented from leaking, e.g., through referrer headers.
   Implementation options include encrypted request objects as defined
   in [RFC9101] or transmission of authorization details via end-to-end
   encrypted connections between client and authorization server by
   utilizing [RFC9126] and the request_uri authorization request
   parameter as defined in [RFC9101].  The latter does not require
   application level encryption but it requires another message exchange
   between client and AS.

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   Even if the request data is encrypted, an attacker could use the
   authorization server to learn the user data by injecting the
   encrypted request data into an authorization request on a device
   under his control and use the authorization server's user consent
   screens to show the (decrypted) user data in the clear.
   Implementations MUST consider this attacker vector and implement
   appropriate countermeasures, e.g. by only showing portions of the
   data or, if possible, determining whether the assumed user context is
   still the same (after user authentication).

   The AS MUST take into consideration the privacy implications when
   sharing authorization details with the client or resource servers.
   The AS SHOULD share this data with those parties on a "need to know"
   basis.

14.  Acknowledgements

   We would like to thank Daniel Fett, Sebastian Ebling, Dave Tonge,
   Mike Jones, Nat Sakimura, and Rob Otto for their valuable feedback
   during the preparation of this specification.

   We would also like to thank Vladimir Dzhuvinov, Takahiko Kawasaki,
   Daniel Fett, Dave Tonge, Travis Spencer, Joergen Binningsboe, Aamund
   Bremer, Steinar Noem, Francis Pouatcha, Jacob Ideskog, Hannes
   Tschofenig, and Aaron Parecki for their valuable feedback to this
   specification.

15.  IANA Considerations

15.1.  OAuth Parameters Registration

   This specification requests registration of the following parameter
   in the "OAuth Parameters" registry [IANA.OAuth.Parameters]
   established by [RFC6749].

   Name:  authorization_details
   Parameter Usage Location:  authorization request, token request,
      token response
   Change Controller:  IESG
   Specification Document(s):  this document

15.2.  JSON Web Token Claims Registration

   This specification requests registration of the following value in
   the IANA "JSON Web Token Claims Registry" established by [RFC7519].

   Claim Name:  authorization_details
   Claim Description:  The claim authorization_details contains a JSON

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      array of JSON objects representing the rights of the access token.
      Each JSON object contains the data to specify the authorization
      requirements for a certain type of resource.
   Change Controller:  IESG
   Specification Document(s):  Section 9.1 of this document

15.3.  OAuth Token Introspection Response

   This specification requests registration of the following value in
   the IANA "OAuth Token Introspection Response Registry" established by
   [RFC7662].

   Name:  authorization_details
   Description:  The member authorization_details contains a JSON array
      of JSON objects representing the rights of the access token.  Each
      JSON object contains the data to specify the authorization
      requirements for a certain type of resource.
   Change Controller:  IESG
   Specification Document(s):  Section 9.2 of this document

15.4.  OAuth Authorization Server Metadata

   This specification requests registration of the following values in
   the IANA "OAuth Authorization Server Metadata" registry of
   [IANA.OAuth.Parameters] established by [RFC8414].

   Metadata Name:  authorization_details_types_supported
   Metadata Description:  JSON array containing the authorization
      details types the AS supports
   Change Controller:  IESG
   Specification Document(s):  Section 10 of [[ this document ]]

15.5.  OAuth Dynamic Client Registration Metadata

   This specification requests registration of the following value in
   the IANA "OAuth Dynamic Client Registration Metadata" registry of
   [IANA.OAuth.Parameters] established by [RFC7591].

   Metadata Name:  authorization_details_types
   Metadata Description:  Indicates what authorization details types the
      client uses.
   Change Controller:  IESG
   Specification Document(s):  Section 10 of [[ this document ]]

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15.6.  OAuth Extensions Error registry

   This specification requests registration of the following value in
   the IANA "OAuth Extensions Error registry" registry of
   [IANA.OAuth.Parameters] established by [RFC6749].

   Metadata Name:  invalid_authorization_details
   Metadata Description:  indicates invalid
      authorization_details_parameterto the client.
   Change Controller:  IESG
   Specification Document(s):  Section 5 of [[ this document ]]

16.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC7519]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
              (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
              <https://www.rfc-editor.org/info/rfc7519>.

   [RFC7662]  Richer, J., Ed., "OAuth 2.0 Token Introspection",
              RFC 7662, DOI 10.17487/RFC7662, October 2015,
              <https://www.rfc-editor.org/info/rfc7662>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8414]  Jones, M., Sakimura, N., and J. Bradley, "OAuth 2.0
              Authorization Server Metadata", RFC 8414,
              DOI 10.17487/RFC8414, June 2018,
              <https://www.rfc-editor.org/info/rfc8414>.

   [RFC8628]  Denniss, W., Bradley, J., Jones, M., and H. Tschofenig,
              "OAuth 2.0 Device Authorization Grant", RFC 8628,
              DOI 10.17487/RFC8628, August 2019,
              <https://www.rfc-editor.org/info/rfc8628>.

   [RFC8707]  Campbell, B., Bradley, J., and H. Tschofenig, "Resource
              Indicators for OAuth 2.0", RFC 8707, DOI 10.17487/RFC8707,
              February 2020, <https://www.rfc-editor.org/info/rfc8707>.

17.  Informative References

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   [CSC]      Consortium, C. S., "Architectures and protocols for remote
              signature applications", 1 June 2019,
              <https://cloudsignatureconsortium.org/wp-
              content/uploads/2019/07/CSC_API_V1_1.0.4.0.pdf>.

   [ETSI]     ETSI, "ETSI TS 119 432, Electronic Signatures and
              Infrastructures (ESI); Protocols for remote digital
              signature creation", 20 March 2019,
              <https://www.etsi.org/deliver/
              etsi_ts/119400_119499/119432/01.01.01_60/
              ts_119432v010101p.pdf>.

   [IANA.OAuth.Parameters]
              IANA, "OAuth Parameters",
              <https://www.iana.org/assignments/oauth-parameters>.

   [JSON.Schema]
              json-schema.org, "JSON Schema",
              <https://json-schema.org/>.

   [OIDC]     Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and
              C. Mortimore, "OpenID Connect Core 1.0 incorporating
              errata set 1", 8 November 2014,
              <https://openid.net/specs/openid-connect-core-1_0.html>.

   [OpenID.CIBA]
              Fernandez, G., Walter, F., Nennker, A., Tonge, D., and B.
              Campbell, "OpenID Connect Client Initiated Backchannel
              Authentication Flow - Core 1.0", 16 January 2019,
              <https://openid.net/specs/openid-client-initiated-
              backchannel-authentication-core-1_0.html>.

   [RFC6749]  Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
              RFC 6749, DOI 10.17487/RFC6749, October 2012,
              <https://www.rfc-editor.org/info/rfc6749>.

   [RFC7591]  Richer, J., Ed., Jones, M., Bradley, J., Machulak, M., and
              P. Hunt, "OAuth 2.0 Dynamic Client Registration Protocol",
              RFC 7591, DOI 10.17487/RFC7591, July 2015,
              <https://www.rfc-editor.org/info/rfc7591>.

   [RFC8259]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", STD 90, RFC 8259,
              DOI 10.17487/RFC8259, December 2017,
              <https://www.rfc-editor.org/info/rfc8259>.

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   [RFC9101]  Sakimura, N., Bradley, J., and M. Jones, "The OAuth 2.0
              Authorization Framework: JWT-Secured Authorization Request
              (JAR)", RFC 9101, DOI 10.17487/RFC9101, August 2021,
              <https://www.rfc-editor.org/info/rfc9101>.

   [RFC9126]  Lodderstedt, T., Campbell, B., Sakimura, N., Tonge, D.,
              and F. Skokan, "OAuth 2.0 Pushed Authorization Requests",
              RFC 9126, DOI 10.17487/RFC9126, September 2021,
              <https://www.rfc-editor.org/info/rfc9126>.

   [transaction-authorization]
              Lodderstedt, T., "Transaction Authorization or why we need
              to re-think OAuth scopes", 20 April 2019,
              <https://medium.com/oauth-2/transaction-authorization-or-
              why-we-need-to-re-think-oauth-scopes-2326e2038948>.

Appendix A.  Additional Examples

A.1.  OpenID Connect

   OpenID Connect [OIDC] specifies the JSON-based claims request
   parameter that can be used to specify the claims a client (acting as
   OpenID Connect Relying Party) wishes to receive in a fine-grained and
   privacy-preserving way as well as assign those claims to certain
   delivery mechanisms, i.e. ID Token or userinfo response.

   The combination of the scope value openid and the additional
   parameter claims can be used beside authorization_details in the same
   way as every non-OIDC scope value.

   Alternatively, there could be an authorization details type for
   OpenID Connect.  This section gives an example of what such an
   authorization details type could look like, but defining this
   authorization details type is outside the scope of this
   specification.

   These hypothetical examples try to encapsulate all details specific
   to the OpenID Connect part of an authorization process into an
   authorization JSON object.

   The top-level field are based on the definitions given in [OIDC]:

   *  claim_sets: names of predefined claim sets, replacement for
      respective scope values, such as profile
   *  max_age: Maximum Authentication Age
   *  acr_values: array of ACR values
   *  claims: the claims JSON structure as defined in [OIDC]

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   This is a simple request for some claim sets.

   [
      {
         "type": "openid",
         "locations": [
            "https://op.example.com/userinfo"
         ],
         "claim_sets": [
            "email",
            "profile"
         ]
      }
   ]

          Figure 25: Example for OpenID Connect request utilizing
                           authorization details.

   Note: locations specifies the location of the userinfo endpoint since
   this is the only place where an access token is used by a client (RP)
   in OpenID Connect to obtain claims.

   A more sophisticated example is shown in the following

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   [
      {
         "type": "openid",
         "locations": [
            "https://op.example.com/userinfo"
         ],
         "max_age": 86400,
         "acr_values": "urn:mace:incommon:iap:silver",
         "claims": {
            "userinfo": {
               "given_name": {
                  "essential": true
               },
               "nickname": null,
               "email": {
                  "essential": true
               },
               "email_verified": {
                  "essential": true
               },
               "picture": null,
               "http://example.info/claims/groups": null
            },
            "id_token": {
               "auth_time": {
                  "essential": true
               }
            }
         }
      }
   ]

      Figure 26: Advanced example for OpenID Connect request utilizing
                           authorization details.

A.2.  Remote Electronic Signing

   The following example is based on the concept laid out for remote
   electronic signing in ETSI TS 119 432 [ETSI] and the CSC API for
   remote signature creation [CSC].

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   [
      {
         "type": "sign",
         "locations": [
            "https://signing.example.com/signdoc"
         ],
         "credentialID": "60916d31-932e-4820-ba82-1fcead1c9ea3",
         "documentDigests": [
            {
               "hash": "sTOgwOm+474gFj0q0x1iSNspKqbcse4IeiqlDg/HWuI=",
               "label": "Credit Contract"
            },
            {
               "hash": "HZQzZmMAIWekfGH0/ZKW1nsdt0xg3H6bZYztgsMTLw0=",
               "label": "Contract Payment Protection Insurance"
            }
         ],
         "hashAlgorithmOID": "2.16.840.1.101.3.4.2.1"
      }
   ]

                 Figure 27: Example for electronic signing.

   The top-level fields have the following meaning:

   *  credentialID: identifier of the certificate to be used for signing
   *  documentDigests: array containing the hash of every document to be
      signed (hash fields).  Additionally, the corresponding label field
      identifies the respective document to the user, e.g. to be used in
      user consent.
   *  hashAlgorithm: algorithm that was used to calculate the hash
      values.

   The AS is supposed to ask the user for consent for the creation of
   signatures for the documents listed in the structure.  The client
   uses the access token issued as a result of the process to call the
   sign doc endpoint at the respective signing service to actually
   create the signature.  This access token is bound to the client, the
   user id and the hashes (and signature algorithm) as consented by the
   user.

A.3.  Access to Tax Data

   This example is inspired by an API allowing third parties to access
   citizen's tax declarations and income statements, for example, to
   determine their creditworthiness.

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   [
       {
           "type": "tax_data",
           "locations": [
               "https://taxservice.govehub.no"
           ],
           "actions":"read_tax_declaration",
           "periods": ["2018"],
           "duration_of_access": 30,
           "tax_payer_id": "23674185438934"
       }
   ]

                  Figure 28: Example for tax data access.

   The top-level fields have the following meaning:

   *  periods: determines the periods the client wants to access
   *  duration_of_access: how long does the client intend to access the
      data in days
   *  tax_payer_id: identifier of the tax payer (if known to the client)

A.4.  eHealth

   These two examples are inspired by requirements for APIs used in the
   Norwegian eHealth system.

   In this use case, the physical therapist sits in front of her
   computer using a local Electronic Health Records (EHR) system.  They
   want to look at the electronic patient records of a certain patient
   and they also want to fetch the patients journal entries in another
   system, perhaps at another institution or a national service.  Access
   to this data is provided by an API.

   The information necessary to authorize the request at the API is only
   known by the EHR system, and must be presented to the API.

   In the first example, the authorization details object contains the
   identifier of an organization.  In this case, the API needs to know
   if the given organization has the lawful basis for processing
   personal health information to give access to sensitive data.

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   "authorization_details": {
       "type": "patient_record",
       "requesting_entity": {
           "type": "Practitioner",
           "identifier": [
           {
               "system": "urn:oid:2.16.578.1.12.4.1.4.4",
               "value": "1234567"
           }],
           "practitioner_role": {
               "organization": {
                   "identifier": {
                       "system": "urn:oid:2.16.578.1.12.4.1.2.101",
                       "type": "ENH",
                       "value": "[organizational number]"
                   }
               }
           }
       }
   }

                        Figure 29: eHealth Example.

   In the second example, the API requires more information to authorize
   the request.  In this case, the authorization details object contains
   additional information about the health institution and the current
   profession the user has at the time of the request.  The additional
   level of detail could be used for both authorization and data
   minimization.

   [
      {
         "type": "patient_record",
         "location": "https://fhir.example.com/patient",
         "actions": [
            "read"
         ],
         "patient_identifier": [
            {
               "system": "urn:oid:2.16.578.1.12.4.1.4.1",
               "value": "12345678901"
            }
         ],
         "reason_for_request": "Clinical treatment",
         "requesting_entity": {
            "type": "Practitioner",
            "identifier": [
               {

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                  "system": "urn:oid:2.16.578.1.12.4.1.4.4",
                  "value": "1234567"
               }
            ],
            "practitioner_role": {
               "organization": {
                  "identifier": [
                     {
                        "system": "urn:oid:2.16.578.1.12.4.1.2.101",
                        "type": "ENH",
                        "value": "<organizational number>"
                     }
                  ],
                  "type": {
                     "coding": [
                        {
                           "system":
                              "http://hl7.org/fhir/organization-type",
                           "code": "dept",
                           "display": "Hospital Department"
                        }
                     ]
                  },
                  "name": "Akuttmottak"
               },
               "profession": {
                  "coding": [
                     {
                        "system": "http://snomed.info/sct",
                        "code": "36682004",
                        "display": "Physical therapist"
                     }
                  ]
               }
            }
         }
      }
   ]

                    Figure 30: Advanced eHaelth example.

   Description of the fields:

   *  patient_identifier: the identifier of the patient composed of a
      system identifier in OID format (namespace) and the actual value
      within this namespace.
   *  reason_for_request: the reason why the user wants to access a
      certain API

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   *  requesting_entity: specification of the requester by means of
      identity, role and organizational context.  This data is provided
      to facilitate authorization and for auditing purposes.

   In this use case, the AS authenticates the requester, who is not the
   patient, and approves access based on policies.

Appendix B.  Document History

   [[ To be removed from the final specification ]]

   -12

   *  Clarify introspection response.

   -11

   *  Updated IANA registrations adding authorization_details parameter

   -10

   *  Updated IANA registrations

   -09

   *  Incorporated feedback by Hannes as document shepherd

   -08

   *  formatting in authorization details type section
   *  added example for privileges common data element

   -07

   *  incorporated review feedback from WGLC
   *  fixed wording in token introspection section
   *  added privacy considerations re authorization details in token
      response

   -06

   *  removed use of resource indicators to filter authorization details
      in token response

   -05

   *  added authorization_details token request parameter and discussion
      on authorization details comparison

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   *  added privileges field to authorization details (to align with
      GNAP)
   *  added IANA text and changed metadata parameter names
   *  added text about use of machine-readable type schemas, e.g.  JSON
      Schema
   *  added text on how authorization details are determined for access
      token issued with token response
   *  added token error response and further error conditions to
      authorization error response

   -04

   *  restructured draft for better readability
   *  simplified normative text about use of the resource parameter with
      authorization_details
   *  added implementation considerations for deployments and products
   *  added type union language from GNAP
   *  added recommendation to use PAR to cope with large requests and
      for request protection

   -03

   *  Updated references to current revisions or RFC numbers
   *  Added section about enrichment of authorization details objects by
      the AS
   *  Clarified processing of unknown authorization details parameters
   *  clarified dependencies between resource and authorization_details
      parameters

   -02

   *  Clarify "type" parameter processing

   -01

   *  Minor fix-up in a few examples

   -00 (WG draft)

   *  initial WG revision

   -03

   *  Reworked examples to illustrate privacy preserving use of
      authorization_details
   *  Added text on audience restriction
   *  Added description of relationship between scope and
      authorization_details

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   *  Added text on token request & response and authorization_details
   *  Added text on how authorization details are conveyed to RSs by
      JWTs or token introspection endpoint response
   *  Added description of relationship between claims and
      authorization_details
   *  Added more example from different sectors
   *  Clarified string comparison to be byte-exact without collation

   -02

   *  Added Security Considerations
   *  Added Privacy Considerations
   *  Added notes on URI size and authorization details
   *  Added requirement to return the effective authorization details
      granted by the resource owner in the token response
   *  changed authorization_details structure from object to array
   *  added Justin Richer & Brian Campbell as Co-Authors

   -00 / -01

   *  first draft

Authors' Addresses

   Torsten Lodderstedt
   yes.com
   Email: torsten@lodderstedt.net

   Justin Richer
   Bespoke Engineering
   Email: ietf@justin.richer.org

   Brian Campbell
   Ping Identity
   Email: bcampbell@pingidentity.com

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