Internet Engineering Task Force (IETF) D. Brossard
Request for Comments: 1 Axiomatics
Category: Informational O. Gazitt
ISSN: 2070-1721 Aserto
A. Babeanu
3Edges
4 July 2024
AuthZEN Request/Response Profile for OAuth 2.0 Rich Authorization
Requests
Abstract
This specification defines a profile of OAuth 2.0 Rich Authorization
Requests leveraging the OpenID AuthZEN authorization request/response
formats within the authorization_details JSON object. Authorization
servers and resource servers from different vendors can leverage this
profile to request and receive relevant authorization decisions from
an AuthZEN-compatible PDP in an interoperable manner.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are candidates for any level of Internet
Standard; see Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc1.
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Table of Contents
1. Introduction
2. Conventions and Definitions
3. Request Parameter authorization_details
3.1. authorization_details Structure
3.2. Authorization Details Types
3.3. Common Data Fields
4. Authorization Request
4.1. Example (non-normative)
5. Support for Multiple Authorization Requests
5.1. Example (non-normative)
6. Security Considerations
7. IANA Considerations
8. References
8.1. Normative References
8.2. Informative References
Acknowledgments
Authors' Addresses
1. Introduction
OpenID AuthZEN is a Working Group under the OpenID Foundation which
aims to increase interoperability and standardization in the
authorization realm. In particular, AuthZEN aims to:
* build standards-based authorization APIs
* define standard design patterns for authorization
* produce educational material to help raise awareness of
externalized authorization.
The aim of this profile is to define an AuthZEN-conformant profile of
the OAuth 2.0 Rich Authorization Requests [RFC9396]. [RFC9396]
introduces a new parameter authorization_details that allows clients
to specify their fine-grained authorization requirements using the
expressiveness of JSON [RFC8259] data structures.
This specification introduces a more structured format for the
authorization_details parameter. The new format is also JSON
[RFC8259] as a result of which this specification is conformant with
[RFC9396] and is merely a stricter profile.
For example the authorization request for a credit transfer mentioned
in [RFC9396] would now be structured as follows
{
"subject": {
"type": "user",
"id": "Alice"
},
"resource": {
"type": "payment_initiation",
"id": "123",
"recipient": {
"creditorName": "Merchant A",
"creditorAccount": {
"bic": "ABCIDEFFXXX",
"iban": "DE02100100109307118603"
}
}
},
"action": {
"name": "transfer",
"instructedAmount": {
"currency": "EUR",
"amount": "123.50"
}
},
"context": {
"remittance": "Ref Number Merchant"
}
}
Figure 1: Source Authorization Request
Using AuthZEN as a format for authorization_details will increase the
usability and the interoperability of [RFC9396]. In particular, it
will be possible for the AS to forward the contents of the
authorization_details parameter to an AuthZEN-conformant Policy
Decision Point (PDP).
2. Conventions and Definitions
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" (AS), "resource server" (RS), "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]. This specification uses the terms "PDP" and
"PEP" defined by [ABAC] and [XACML].
3. Request Parameter authorization_details
In [RFC9396], 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. This specification defines the format for each one of
these objects such that it conforms to [AUTHZEN] and [RFC9396].
[AUTHZEN] groups JSON datastructures into 4 JSON objects:
* subject: A Subject is the user or robotic principal about whom the
Authorization API is being invoked. The Subject may be requesting
access at the time the Authorization API is invoked.
* resource: A Resource is the target of an access request. It is a
JSON ([RFC8259]) object that is constructed similar to a Subject
entity.
* action: An Action is the type of access that the requester intends
to perform. Action is a JSON ([RFC8259]) object that contains at
least a name field.
* context: The Context object is a set of attributes that represent
environmental or contextual data about the request such as time of
day. It is a JSON ([RFC8259]) object.
Note: the aforementioned is indicative only. Always refer to
[AUTHZEN] for the formal definition of each element.
3.1. authorization_details Structure
Because *type* is *REQUIRED*, the new _authorization_details_
structure is as follows:
* type: An identifier for the authorization details type as a
string. The value for this profile is "authzen_evaluation" or
"authzen_evaluations", corresponding to the AuthZEN API being
invoked. The value is case-insensitive. This field is
*REQUIRED*.
* request: this field contains the entire AuthZEN-conformant
authorization request. This field is *REQUIRED*.
3.2. Authorization Details Types
This profile declares a new value for the _type_ field as stated in
the previous section. The value for this profile is
"authzen_evaluation" or "authzen_evaluations". This indicates there
will be another field called request and its value will be an
AuthZEN-conformant authorization request.
AuthZEN also defines a _type_ field in the Subject and Resource
categories. This field is meant to describe the type of user and/or
resource required.
3.3. Common Data Fields
No field other than type and request shall be allowed in
authorization_details when the type is authzen_evaluation or
authzen_evaluations. All other fields such as the ones mentioned in
[RFC9396] shall be inserted inside the AuthZEN request in the
relevant object (Subject, Resource, Action, or Context).
4. Authorization Request
Conformant to [RFC9396], the authorization_details authorization
request parameter can be used to specify authorization requirements
in all places where the scope parameter is used for the same purpose,
examples include:
* authorization requests as specified in [RFC6749]
* device authorization requests as specified in [RFC8628]
* backchannel authentication requests as defined in [OID-CIBA]
Parameter encoding follows the exact same rules as [RFC9396].
4.1. Example (non-normative)
{
"type": "authzen_evaluation",
"request":
{
"subject": {
"type": "user",
"id": "Alice"
},
"resource": {
"type": "payment_initiation",
"id": "123",
"recipient": {
"creditorName": "Merchant A",
"creditorAccount": {
"bic": "ABCIDEFFXXX",
"iban": "DE02100100109307118603"
}
}
},
"action": {
"name": "transfer",
"instructedAmount": {
"currency": "EUR",
"amount": "123.50"
}
},
"context": {
"remittance": "Ref Number Merchant"
}
}
}
Figure 2: Source Authorization Request
5. Support for Multiple Authorization Requests
[AUTHZEN] supports a profile that allows the expression of multiple
authorization requests in a single JSON object. As a result, this
profile recommends the use of a single authorization_details object
containing _boxcarred_ requests as described in [BOXCAR] when
possible and the use of the authorization_details array otherwise.
5.1. Example (non-normative)
This example is based on the one in [RFC9396] under section 3.
Authorization Request.
[
{
"type": "authzen_evaluations",
"request":
{
"subject": {
"id": "alice@acmecorp.com",
"type": "user"
},
"resource":{
"id": "123",
"type": "account_information",
"location": "https://example.com/accounts"
},
"evaluations": {
"eval-1": {
"action": {
"name": "list_accounts"
}
},
"eval-2": {
"action": {
"name": "read_balances"
}
},
"eval-3": {
"action": {
"name": "read_transactions"
}
}
}
}
},
{
"type": "authzen_evaluations",
"request":
{
"subject": {
"id": "alice@acmecorp.com",
"type": "user"
},
"resource":{
"id": "123",
"type": "payment_initiation",
"location": "https://example.com/payments",
"recipient": {
"creditorName": "Merchant A",
"creditorAccount": {
"bic": "ABCIDEFFXXX",
"iban": "NL02RABO2228161411"
}
}
},
"context":{
"remittance": "Ref Number Merchant"
},
"evaluations": {
"eval-1": {
"action": {
"name": "initiate",
"instructedAmount": {
"currency": "EUR",
"amount": "123.50"
}
}
},
"eval-2": {
"action": {
"name": "status"
}
},
"eval-3": {
"action": {
"name": "cancel"
}
}
}
}
}
]
6. Security Considerations
The Security Considerations of [RFC9396], [RFC6749], [RFC7662], and
[RFC8414] all apply.
7. IANA Considerations
This document has no IANA actions.
8. References
8.1. Normative References
[AUTHZEN] Gazitt, O., Brossard, D., and A. Tulshibagwale, "OpenID
AuthZEN Authorization API", July 2024,
.
[BOXCAR] Gazitt, O., Brossard, D., and A. Tulshibagwale, "OpenID
AuthZEN Authorization API", July 2024,
.
[OID-CIBA] Fernandez, G., Walter, F., Nennker, A., Tonge, D., and B.
Campbell, "OpenID Connect Client-Initiated Backchannel
Authentication Flow - Core 1.0", September 2021,
.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012,
.
[RFC7662] Richer, J., Ed., "OAuth 2.0 Token Introspection",
RFC 7662, DOI 10.17487/RFC7662, October 2015,
.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, .
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
.
[RFC8414] Jones, M., Sakimura, N., and J. Bradley, "OAuth 2.0
Authorization Server Metadata", RFC 8414,
DOI 10.17487/RFC8414, June 2018,
.
[RFC8628] Denniss, W., Bradley, J., Jones, M., and H. Tschofenig,
"OAuth 2.0 Device Authorization Grant", RFC 8628,
DOI 10.17487/RFC8628, August 2019,
.
[RFC9396] Lodderstedt, T., Richer, J., and B. Campbell, "OAuth 2.0
Rich Authorization Requests", RFC 9396,
DOI 10.17487/RFC9396, May 2023,
.
8.2. Informative References
[ABAC] Hu, V. and D. Ferraiolo, "Guide to Attribute Based Access
Control (ABAC) Definition and Considerations - NIST
Special Publication 800-162", January 2014,
.
[XACML] Rissanen, E., "eXtensible Access Control Markup Language
(XACML) Version 3.0, OASIS Standard", January 2013,
.
Acknowledgments
We would like to thank members of the OpenID AuthZEN Working Group
for their valuable feedback during the preparation of this
specification. In particular our thanks go to Gerry Gebel and Allan
Foster.
We would also like to thank Justin Richer and Pieter Kasselman for
their guidance on this spec and the overall IETF process.
Authors' Addresses
David Brossard
Axiomatics
Email: david.brossard@axiomatics.com
Omri Gazitt
Aserto
Email: omri@aserto.com
Alex Babeanu
3Edges
Email: alex@3edges.com