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Versions: (draft-lodderstedt-oauth-rar) 00 01 02 03

Web Authorization Protocol                                T. Lodderstedt
Internet-Draft                                                   yes.com
Intended status: Standards Track                               J. Richer
Expires: 21 April 2021                               Bespoke Engineering
                                                             B. Campbell
                                                           Ping Identity
                                                         18 October 2020


                 OAuth 2.0 Rich Authorization Requests
                        draft-ietf-oauth-rar-03

Abstract

   This document specifies a new parameter "authorization_details" that
   is used to carry fine grained authorization data in the OAuth
   authorization request.

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 21 April 2021.

Copyright Notice

   Copyright (c) 2020 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 Simplified BSD License text
   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions and Terminology . . . . . . . . . . . . . . .   4
   2.  Request parameter "authorization_details" . . . . . . . . . .   4
     2.1.  Authorization data elements types . . . . . . . . . . . .   5
     2.2.  Authorization Data Types  . . . . . . . . . . . . . . . .   8
     2.3.  Relationship to "scope" parameter . . . . . . . . . . . .   9
       2.3.1.  Scope value "openid" and "claims" parameter . . . . .   9
     2.4.  Relationship to "resource" parameter  . . . . . . . . . .   9
       2.4.1.  Authorization Request . . . . . . . . . . . . . . . .  10
       2.4.2.  Token Request . . . . . . . . . . . . . . . . . . . .  10
   3.  Using "authorization_details" . . . . . . . . . . . . . . . .  12
     3.1.  Authorization Request . . . . . . . . . . . . . . . . . .  12
     3.2.  Authorization Request Processing  . . . . . . . . . . . .  15
     3.3.  Token Request . . . . . . . . . . . . . . . . . . . . . .  16
     3.4.  Token Response  . . . . . . . . . . . . . . . . . . . . .  16
       3.4.1.  Enriched authorization details in Token Response  . .  17
     3.5.  Token Content . . . . . . . . . . . . . . . . . . . . . .  20
     3.6.  Token Introspection Request . . . . . . . . . . . . . . .  22
     3.7.  Token Introspection Response  . . . . . . . . . . . . . .  22
   4.  Metadata  . . . . . . . . . . . . . . . . . . . . . . . . . .  23
   5.  Implementation Considerations . . . . . . . . . . . . . . . .  24
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  24
   7.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  24
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  25
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  25
   10. Normative References  . . . . . . . . . . . . . . . . . . . .  25
   11. Informative References  . . . . . . . . . . . . . . . . . . .  26
   Appendix A.  Additional Examples  . . . . . . . . . . . . . . . .  28
     A.1.  OpenID Connect  . . . . . . . . . . . . . . . . . . . . .  28
     A.2.  Remote Electronic Signing . . . . . . . . . . . . . . . .  29
     A.3.  Access to Tax Data  . . . . . . . . . . . . . . . . . . .  30
     A.4.  eHealth . . . . . . . . . . . . . . . . . . . . . . . . .  31
   Appendix B.  Document History . . . . . . . . . . . . . . . . . .  34
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  35

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 make a payment
   with the amount of 45 Euros" or "please give me read access to folder
   A and write access to file X".



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   This draft 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, a request for payment authorization can be represented
   using a JSON object like this:

   {
      "type": "payment_initiation",
      "locations": [
         "https://example.com/payments"
      ],
      "instructedAmount": {
         "currency": "EUR",
         "amount": "123.50"
      },
      "creditorName": "Merchant123",
      "creditorAccount": {
         "iban": "DE02100100109307118603"
      },
      "remittanceInformationUnstructured": "Ref Number Merchant"
   }

   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].

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

   Most notably, the field "locations" allows a client to specify where
   it intends to use a certain authorization, i.e., it is now 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).  In combination
   with the "resource" token request parameter as specified in [RFC8707]
   it enables the AS to mint RS-specific structured access tokens that
   only contain the permissions applicable to the respective RS.





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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.

   This example shows the specification of authorization details using
   the payment authorization object shown above:

   [
      {
         "type": "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"
      }
   ]




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

   [
      {
         "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": "Merchant123",
         "creditorAccount": {
            "iban": "DE02100100109307118603"
         },
         "remittanceInformationUnstructured": "Ref Number Merchant"
      }
   ]

   The JSON objects with "type" fields of "account_information" and
   "payment_initiation" represent the different authorization data to be
   used by the AS to ask for consent and MUST subsequently also be made
   available to the respective resource servers.  The array MAY contain
   several elements of the same "type".

2.1.  Authorization data elements types

   The allowable contents of the authorization details object are
   determined by the "type" parameter.




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   "type":  The type of authorization data as a string.  This field MAY
      define which other elements are allowed in the request.  This
      element 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 data types that it
   supports.  The AS MUST NOT do any collation or normalization of data
   types during comparison.

   This draft defines a set of common data elements that are designed to
   be usable across different types of APIs.  These data elements MAY be
   combined in different ways depending on the needs of the API.  All
   data elements are OPTIONAL.

   "locations":  An array of strings representing the location of the
      resource or resource server.  This is typically composed of URIs.

   "actions":  An array of strings representing the kinds of actions to
      be taken at the resource.  The values of the strings are
      determined by the API being protected.

   "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.

   When different element types are used in combination, the permissions
   the client requests is the cartesian product of the values.  In the
   following example

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



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   the client is requesting read and write access to both the contacts
   and photos belonging to customers in a customer information API.  If
   the client wishes to have finer control over its access, it can send
   multiple objects.  For example:

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

   The client is asking for read access to the contacts and write access
   to the photos in the same API endpoint.

   An API MAY define its own extensions, subject to the "type" of the
   respective authorization object.  It is assumed that the full
   structure of each of the authorization objects is tailored to the
   needs of a certain application, API, or resource type, and can
   contain a mix of general-purpose and api-specific elements within the
   structure.  The example structures shown above are based on certain
   kinds of APIs that can be found in the Open Banking space.









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2.2.  Authorization Data Types

   Interpretation of the value of the "type" parameter, and the object
   elements 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 depending 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 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
   element names.

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






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2.3.  Relationship to "scope" parameter

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

   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.

   It is RECOMMENDED that a given API use only one form of requirement
   specification.

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

2.3.1.  Scope value "openid" and "claims" parameter

   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 a 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 data type for OpenID
   Connect.  Appendix A.1 gives an example of how such an authorization
   data type could look like.

2.4.  Relationship to "resource" parameter

   The request parameter "resource" as defined in [RFC8707] indicates to
   the AS the resource(s) where the client intends to use the access
   tokens issued based on a certain grant.  This mechanism is a way to
   audience-restrict access tokens and to allow the AS to create
   resource server specific access tokens.  The "authorization_details"
   parameter also allows the client to designate the audience of a
   certain authorization details object in the respective "locations"
   element.

   This specification allows a client to use both parameters together in
   an authorization request, and it defines how the "resource" parameter
   in the token request can be used to assign authorization details to a
   certain access token.



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   If used together, the "locations" element within objects of the
   "authorization_details" parameter overrides the value of the
   "resources" parameter.  In the absence of a "locations" element, the
   value of the "resources" parameter is applied to the object.

2.4.1.  Authorization Request

   If a client uses "authorization_details" with "locations" elements
   and the "resource" parameter in the same authorization request, the
   meaning is as follows:

   *  for every authorization details object containing a "locations"
      element, the intended audience is defined by the "locations"
      element only.  The "resource" parameter value is not applied.

   *  for every authorization details object not containing a
      "locations" element, this authorization details object is bound to
      the audience(s) defined by the "resource" parameter.

   The authorization server will consider this audience restriction in
   the user consent if needed.

2.4.2.  Token Request

   If a client uses the "resource" parameter in a token requests, the AS
   MUST utilize the data provided in the "locations" elements to filter
   the authorization data objects applicable to the respective
   resource(s).

   The logic is as follows:

   *  For every authorization details object without a "locations"
      element: the authorization server treats it as applicable to all
      resources, i.e. it assigns this authorization details object to
      the access token.

   *  For every authorization details object with a "locations" element:
      the authorization server adds this object to the access token, if
      at least one of the "locations" values exactly matches the
      "resource" parameter value.  The authorization server MUST compare
      both values using an exact byte match of the string values.

   This shall be illustrated using an example.

   The client has sent an authorization request using the following
   example authorization details.





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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": "Merchant123",
         "creditorAccount": {
            "iban": "DE02100100109307118603"
         },
         "remittanceInformationUnstructured": "Ref Number Merchant"
      }
   ]

   If this client then sends the following token request to the AS,

   POST /token HTTP/1.1
   Host: as.example.com
   Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW
   Content-Type: application/x-www-form-urlencoded

   grant_type=authorization_code&code=SplxlOBeZQQYbYS6WxSbIA
   &redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb
   &resource=https%3A%2F%2Fexample%2Ecom%2Fpayments

   that contains a resource parameter with the value of
   "https://example.com/payments", this value will be matched against
   the locations elements ("https://example.com/accounts" and



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   "https://example.com/payments") and will select the element of type
   "payment_initiation" for inclusion in the access token as illustrated
   by the following example JWT content.

   {
      "iss": "https://as.example.com",
      "sub": "24400320",
      "aud": "a7AfcPcsl2",
      "exp": 1311281970,
      ...
      "authorization_details": [
         {
            "type": "https://www.someorg.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"
         }
      ],
      ...
   }

3.  Using "authorization_details"

3.1.  Authorization Request

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

   *  Authorization requests as specified in [RFC6749],

   *  Access token requests as specified in [RFC6749], if also used as
      authorization requests, e.g. in the case of assertion grant types
      [RFC7521],



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   *  Request objects as specified in [I-D.ietf-oauth-jwsreq],

   *  Device Authorization Request as specified in [RFC8628],

   *  Backchannel Authentication Requests as defined in [OpenID.CIBA].

   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
   example:

   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%5Finformati
      on%22%2C%22actions%22%3A%5B%22list%5Faccounts%22%2C%22read%5Fbal
      ances%22%2C%22read%5Ftransactions%22%5D%2C%22locations%22%3A%5B%
      22https%3A%2F%2Fexample%2Ecom%2Faccounts%22%5D%7D%5D HTTP/1.1
   Host: server.example.com

   Implementors MUST ensure to protect personal identifiable information
   in transit.  One way is to utilize encrypted request objects as
   defined in [I-D.ietf-oauth-jwsreq].  In the context of a request
   object, "authorization_details" is added as another top level JSON
   element.





















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   {
      "iss": "s6BhdRkqt3",
      "aud": "https://server.example.com",
      "response_type": "code",
      "client_id": "s6BhdRkqt3",
      "redirect_uri": "https://client.example.com/cb",
      "state": "af0ifjsldkj",
      "code_challenge_method": "S256",
      "code_challenge": "K2-ltc83acc4h0c9w6ESC_rEMTJ3bwc-uCHaoeK1t8U",
      "authorization_details": [
         {
            "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": "Merchant123",
            "creditorAccount": {
               "iban": "DE02100100109307118603"
            },
            "remittanceInformationUnstructured": "Ref Number Merchant"
         }
      ]
   }

   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 [I-D.ietf-oauth-jwsreq] in combination with



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   the pushed request object mechanism as defined in
   [I-D.ietf-oauth-par] 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 a 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

3.2.  Authorization Request Processing

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

   The AS MUST refuse to process any unknown authorization data type or
   authorization details not conforming to the respective type
   definition.  If any of the objects in "authorization_details"
   contains an unknown authorization data type or an object of known
   type but containing unknown elements or elements of the wrong type,
   the AS MUST abort processing and respond with an error
   "invalid_authorization_details" to the client.

   Note: If the authorization request also contained the "scope"
   parameter, the AS MUST present the merged set of requirements
   represented by the authorization request in the user consent.





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   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).

   Note: The AS MUST make the "authorization_details" available to the
   respective resource servers.  The AS MAY add the
   "authorization_details" element to access tokens in JWT format and to
   Token Introspection responses (see below).

3.3.  Token Request

   Clients utilizing authorization details are RECOMMENDED to use the
   "resource" token request parameter to allow the AS to issue audience
   restricted access tokens as recommended in
   [I-D.ietf-oauth-security-topics].

   For example the following token request selects authorization details
   applicable for the resource server represented by the URI
   "https://example.com/payments".

   POST /token HTTP/1.1
   Host: as.example.com
   Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW
   Content-Type: application/x-www-form-urlencoded

   grant_type=authorization_code&code=SplxlOBeZQQYbYS6WxSbIA
   &redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb
   &resource=https%3A%2F%2Fexample%2Ecom%2Fpayments

3.4.  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.

   This is shown in the following example:














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

   {
      "access_token": "2YotnFZFEjr1zCsicMWpAA",
      "token_type": "example",
      "expires_in": 3600,
      "refresh_token": "tGzv3JOkF0XG5Qx2TlKWIA",
      "authorization_details": [
         {
            "type": "https://www.someorg.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"
         }
      ]
   }

3.4.1.  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
   she wants the client to entitle to access in the course of the
   authorization process.  In order to allow the client to determine the
   accounts it is entitled to access, the authorization server will 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
      }
   ]

   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-cache, 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
         }
      ]
   }

   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" ]
      }
   ]

   When the user interacts with the AS, they select which of the medical
   records they are responsible for to give 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/" ]
        }
     ]
   }

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

3.5.  Token Content

   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.

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






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   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
   initation example above:

   {
      "iss": "https://as.example.com",
      "sub": "24400320",
      "aud": "a7AfcPcsl2",
      "exp": 1311281970,
      "acr": "psd2_sca",
      "txn": "8b4729cc-32e4-4370-8cf0-5796154d1296",
      "authorization_details": [
         {
            "type": "https://www.someorg.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"
      }
   }

   In this case, the AS added the following example claims:

   *  "sub": conveys the user on which behalf the client is asking for
      payment initation




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   *  "txn": transaction id used to trace the transaction across the
      services of provider "example.com"

   *  "debtorAccount": API-specific element 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.  The field "user_role" conveys the role the
      user has with respect to this particuar account.  In this case,
      she is the owner.  This data is used for access control at the
      payment API (the RS).

3.6.  Token Introspection Request

   In case of opaque access tokens, the data provided to a certain RS is
   determined using the RS's identifier with the AS (see
   [I-D.ietf-oauth-jwt-introspection-response], section 3).

3.7.  Token Introspection Response

   The token endpoint 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.

   Here is an example for the payment initation 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://www.someorg.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"
      }
   }

4.  Metadata

   The AS advertises support for "authorization_details" using the
   metadata parameter "authorization_details_supported" of type boolean.

   The authorization data types supported can be determined using the
   metadata parameter "authorization_data_types_supported", which is an
   JSON array.

   Clients announce the authorization data types they use in the new
   dynamic client registration parameter "authorization_data_types".





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   The registration of new authorization data types with the AS is out
   of scope of this draft.

5.  Implementation Considerations

   The scheme and processing will vary significantly among different
   authorization data types.  Any implementation of this draft is
   therefore supposed to allow the customization of the user consent and
   the handling of access token data.

   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.

6.  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.  In order to ensure their integrity, the
   client SHOULD send authorization details in a signed request object
   as defined in [I-D.ietf-oauth-jwsreq] or use the "request_uri"
   authorization request parameter as defined in [I-D.ietf-oauth-jwsreq]
   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.

7.  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 [I-D.ietf-oauth-jwsreq] or transmission of authorization details
   via end-to-end encrypted connections between client and authorization
   server by utilizing the "request_uri" authorization request parameter
   as defined in [I-D.ietf-oauth-jwsreq].

   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



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   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 counter measures, e.g. by only showing portions of the
   data or, if possible, determing 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 resource servers.  The AS
   SHOULD share this data with the resource servers on a "need to know"
   basis.

8.  Acknowledgements

   We would 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 draft.

   We would also like to thank Vladimir Dzhuvinov, Takahiko Kawasaki,
   Daniel Fett, Dave Tonge, Travis Spencer, Jørgen Binningsbø,
   Aamund Bremer, Steinar Noem, and Aaron Parecki for their valuable
   feedback to this draft.

9.  IANA Considerations

   TBD

   *  "authorization_details" as JWT claim

   *  "authorization_details_supported" and
      "authorization_data_types_supported" as metadata parameters

   *  "authorization_data_types" as dynamic client registration
      parameter

   *  [[ possibly establish authorization data type registry (and
      declare: "type", "actions", "locations", "datatypes",
      "identifier", others?) ]]

   *  [[ register type "openid_claims" on a URL by the OpenID
      foundation? ]]

   *  register invalid_authorization_details to OAuth Extensions Error
      Registry

10.  Normative References





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   [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>.

   [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>.

   [RFC7521]  Campbell, B., Mortimore, C., Jones, M., and Y. Goland,
              "Assertion Framework for OAuth 2.0 Client Authentication
              and Authorization Grants", RFC 7521, DOI 10.17487/RFC7521,
              May 2015, <https://www.rfc-editor.org/info/rfc7521>.

   [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>.

   [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>.

   [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>.

   [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>.

11.  Informative References

   [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,
              <http://openid.net/specs/openid-connect-core-1_0.html>.

   [I-D.ietf-oauth-jwt-introspection-response]
              Lodderstedt, T. and V. Dzhuvinov, "JWT Response for OAuth
              Token Introspection", Work in Progress, Internet-Draft,
              draft-ietf-oauth-jwt-introspection-response-09, 25 April
              2020, <https://tools.ietf.org/html/draft-ietf-oauth-jwt-
              introspection-response-09>.







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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>.

   [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>.

   [I-D.ietf-oauth-par]
              Lodderstedt, T., Campbell, B., Sakimura, N., Tonge, D.,
              and F. Skokan, "OAuth 2.0 Pushed Authorization Requests",
              Work in Progress, Internet-Draft, draft-ietf-oauth-par-04,
              18 September 2020,
              <https://tools.ietf.org/html/draft-ietf-oauth-par-04>.

   [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>.

   [I-D.ietf-oauth-security-topics]
              Lodderstedt, T., Bradley, J., Labunets, A., and D. Fett,
              "OAuth 2.0 Security Best Current Practice", Work in
              Progress, Internet-Draft, draft-ietf-oauth-security-
              topics-16, 5 October 2020, <https://tools.ietf.org/html/
              draft-ietf-oauth-security-topics-16>.

   [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>.

   [I-D.ietf-oauth-jwsreq]
              Sakimura, N., Bradley, J., and M. Jones, "The OAuth 2.0
              Authorization Framework: JWT Secured Authorization Request
              (JAR)", Work in Progress, Internet-Draft, draft-ietf-
              oauth-jwsreq-30, 10 September 2020,
              <https://tools.ietf.org/html/draft-ietf-oauth-jwsreq-30>.






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   [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>.

Appendix A.  Additional Examples

A.1.  OpenID Connect

   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 elements 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]

   This is a simple request for some claim sets.

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

   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
               }
            }
         }
      }
   ]

A.2.  Remote Electronic Signing

   The following example is based on the concept layed 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"
      }
   ]

   The top-level elements 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" elements).  Additionally, the corresponding
      "label" element identifies the respective document to the user,
      e.g. to be used in user consent.

   *  "hashAlgorithm": algomrithm that was used to calculate the hash
      values.

   The AS is supposed to ask the user for consent for the creation of
   signatues for the documents listed in the structure.  The client uses
   the access token issued as 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 credit worthiness.





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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"
       }
   ]

   The top-level elements 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.  She wants to
   look at the electronic patient records of a certain patient and she
   also wants 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]"
                   }
               }
           }
       }
   }

   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": [
               {
                  "system": " urn:oid:2.16.578.1.12.4.1.4.4",
                  "value": "1234567"



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               }
            ],
            "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"
                     }
                  ]
               }
            }
         }
      }
   ]

   Description of the elements:

   *  "patient_identifier": the identifier of the patient composed of a
      system identifier in OID format (namespace) and the acutal 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 ]]

   -03

   *  Updated referenes 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"

   *  Added text on token request & response and "authorization_details"





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   *  Added text on how authorization details are conveyed to RSs by
      JWTs or token 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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