OAuth 2.0 Rich Authorization Requests
draft-ietf-oauth-rar-04
The information below is for an old version of the document.
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|---|---|---|---|
| Authors | Torsten Lodderstedt , Justin Richer , Brian Campbell | ||
| Last updated | 2021-02-07 | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-oauth-rar-04
Web Authorization Protocol T. Lodderstedt
Internet-Draft yes.com
Intended status: Standards Track J. Richer
Expires: 11 August 2021 Bespoke Engineering
B. Campbell
Ping Identity
7 February 2021
OAuth 2.0 Rich Authorization Requests
draft-ietf-oauth-rar-04
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 11 August 2021.
Copyright Notice
Copyright (c) 2021 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 . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions and Terminology . . . . . . . . . . . . . . . 4
2. Request parameter "authorization_details" . . . . . . . . . . 4
2.1. Authorization data elements types . . . . . . . . . . . . 6
2.2. Authorization Data Types . . . . . . . . . . . . . . . . 10
3. Authorization Request . . . . . . . . . . . . . . . . . . . . 11
3.1. Relationship to "scope" parameter . . . . . . . . . . . . 12
3.2. Relationship to "resource" parameter . . . . . . . . . . 13
4. Authorization Response . . . . . . . . . . . . . . . . . . . 13
5. Authorization Error Response . . . . . . . . . . . . . . . . 13
6. Token Request . . . . . . . . . . . . . . . . . . . . . . . . 13
7. Token Response . . . . . . . . . . . . . . . . . . . . . . . 14
7.1. Enriched authorization details in Token Response . . . . 15
8. Resource Servers . . . . . . . . . . . . . . . . . . . . . . 18
8.1. JWT-based Access Tokens . . . . . . . . . . . . . . . . . 19
8.2. Token Introspection . . . . . . . . . . . . . . . . . . . 20
9. Metadata . . . . . . . . . . . . . . . . . . . . . . . . . . 21
10. Scope value "openid" and "claims" parameter . . . . . . . . . 22
11. Implementation Considerations . . . . . . . . . . . . . . . . 22
11.1. Using authorization details in a certain deployment . . 22
11.2. Minimal product support . . . . . . . . . . . . . . . . 22
11.3. Large requests . . . . . . . . . . . . . . . . . . . . . 23
12. Security Considerations . . . . . . . . . . . . . . . . . . . 24
13. Privacy Considerations . . . . . . . . . . . . . . . . . . . 24
14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 25
15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
16. Normative References . . . . . . . . . . . . . . . . . . . . 26
17. 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
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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 make a payment
with the amount of 45 Euros" or "please give me read access to folder
A and write access to file X".
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.
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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.
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:
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[
{
"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"
}
]
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": "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.
"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.
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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. 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"
]
}
]
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"
]
}
]
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 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" field.
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"resources": [
{
"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"
}
]
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.
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.
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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"
]
}
]
}
3. Authorization Request
The "authorization_details" 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],
* 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].
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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%22Merchant123%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
Based on the data provided in the "authorization_details" parameter
the AS will ask the user for consent to the requested access
permissions.
3.1. 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 uses only one form of requirement
specification.
When gathering user consent, the AS MUST present the merged set of
requirements represented by the authorization request.
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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).
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" 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 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.
6. Token Request
The "resource" token request parameter as defined in [RFC8707] MAY be
used in the token request to request the creation of an audience
restricted access token (as recommended in
[I-D.ietf-oauth-security-topics]). If the client uses this
parameter, the AS MUST consider the audience restriction defined by
the "locations" elements of the "authorization_details" 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.
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* 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" token request parameter value. The authorization
server MUST compare both values using an exact byte match of the
string values.
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
Using the example given above, this request would result in the
assignment of the "payment_initiation" authorization details object
from (#authz_details) to the access token to be issued (see below).
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.
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-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"
}
]
}
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 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.
8. 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"
element to access tokens in JWT format or to Token Introspection
responses.
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8.1. 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 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
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"
}
}
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In this case, the AS added the following example claims:
* "sub": conveys the user on which behalf the client is asking for
payment initation
* "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,
they is the owner. This data is used for access control at the
payment API (the RS).
8.2. Token Introspection
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).
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"
}
}
9. 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.
10. 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 what such an authorization
data type could look like.
11. Implementation Considerations
11.1. Using authorization details in a certain deployment
Using authorization details in a certain deployment will require the
follwowing steps:
* Define authorization details types (might include definition and
publication of JSON schemas)
* 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
11.2. Minimal product support
Products supporting this specification should provide the following
basic functions:
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* 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, espceially
"authorization_code" and "refresh_token".
* If the product supports resource indicators, it should also
support filtering of the authorization details to be assigned to
access tokens using the "resource" token request parameter.
Processing and presentation of authorization details will vary
significantly among different authorization data 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. 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 [I-D.ietf-oauth-jwsreq] in combination with
the pushed request object mechanism as defined in
[I-D.ietf-oauth-par] to pass authorization details in a reliable and
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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
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. 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.
13. Privacy Considerations
Implementers MUST design and use authorization details in a privacy
preserving manner.
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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
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.
14. 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.
15. 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
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* [[ 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
16. Normative References
[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>.
[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>.
[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>.
[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>.
[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>.
[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>.
17. Informative References
[I-D.ietf-oauth-jwt-introspection-response]
Lodderstedt, T. and V. Dzhuvinov, "JWT Response for OAuth
Token Introspection", Work in Progress, Internet-Draft,
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draft-ietf-oauth-jwt-introspection-response-10, 18 October
2020, <https://tools.ietf.org/html/draft-ietf-oauth-jwt-
introspection-response-10>.
[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>.
[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>.
[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-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>.
[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>.
[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-05,
14 December 2020,
<https://tools.ietf.org/html/draft-ietf-oauth-par-05>.
[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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[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>.
[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
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.
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A more sophisticated example is shown in the following
[
{
"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. They wants to
look at the electronic patient records of a certain patient and they
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 ]]
-04
* restructured draft for better readability
* added implemnentation considerations for deployments and products
* added type union language from GNAP
-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"
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* Added text on audience restriction
* Added description of relationship between "scope" and
"authorization_details"
* Added text on token request & response and "authorization_details"
* 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
Lodderstedt, et al. Expires 11 August 2021 [Page 35]
Internet-Draft oauth-rar February 2021
Brian Campbell
Ping Identity
Email: bcampbell@pingidentity.com
Lodderstedt, et al. Expires 11 August 2021 [Page 36]