| Internet-Draft | OAuth 2.0 Protected Resource Metadata | October 2024 |
| Jones, et al. | Expires 18 April 2025 | [Page] |
This specification defines a metadata format that an OAuth 2.0 client or authorization server can use to obtain the information needed to interact with an OAuth 2.0 protected resource.¶
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 18 April 2025.¶
Copyright (c) 2024 IETF Trust and the persons identified as the document authors. All rights reserved.¶
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶
This specification defines a metadata format enabling OAuth 2.0 clients and authorization servers to obtain information needed to interact with an OAuth 2.0 protected resource. The structure and content of this specification is intentionally as parallel as possible to that of "OAuth 2.0 Dynamic Client Registration Protocol" [RFC7591], which enables a client to provide metadata about itself to an OAuth 2.0 authorization server and to OAuth 2.0 Authorization Server Metadata [RFC8414], which enables a client to obtain metadata about an OAuth 2.0 authorization server.¶
The means by which the client obtains the location of the protected resource is out of scope of this document. In some cases, the location may be manually configured into the client; for example, an email client could provide an interface for a user to enter the URL of their JMAP [RFC8620] server. In other cases, it may be dynamically discovered; for example, a user could enter their email address into an email client, the client could perform WebFinger [RFC7033] discovery (in a manner related to the description in Section 2 of "OpenID Connect Discovery 1.0" [OpenID.Discovery]) to find the resource server, then fetch the resource server metadata to find the authorization server to use to obtain authorization to access the user's email.¶
The metadata for a protected resource is retrieved from a well-known location as a JSON [RFC8259] document, which declares information about its capabilities and optionally, its relationships to other services. This process is described in Section 3.¶
This metadata can either be communicated in a self-asserted fashion or as a set of signed metadata values represented as claims in a JSON Web Token (JWT) [JWT]. In the JWT case, the issuer is vouching for the validity of the data about the protected resource. This is analogous to the role that the Software Statement plays in OAuth Dynamic Client Registration [RFC7591].¶
Each protected resource publishing metadata about itself makes its own metadata document available at a well-known location deterministically derived from the protected resource's URL, even when the resource server implements multiple protected resources. This prevents attackers from publishing metadata supposedly describing the protected resource, but that is not actually authoritative for the protected resource, as described in Section 7.3.¶
Section 2 defines metadata parameters that a protected
resource can publish, which includes things like which scopes are
supported, how a client can present an access token, and more.
These values may be used by other specifications, such as the jwks_uri
used to publish public keys the resource server uses to sign
resource responses, for instance,
as described in [FAPI.MessageSigning].¶
Section 5 describes the use of
WWW-Authenticate by protected resources
to dynamically inform clients of
the URL of their protected resource metadata.
This use of WWW-Authenticate can indicate that
the protected resource metadata may have changed.¶
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.¶
All uses of JSON Web Signature (JWS) [JWS] and JSON Web Encryption (JWE) [JWE] data structures in this specification utilize the JWS Compact Serialization or the JWE Compact Serialization; the JWS JSON Serialization and the JWE JSON Serialization are not used. Choosing a single serialization is intended to facilitate interoperability.¶
This specification uses the terms "Access Token", "Authorization Code", "Authorization Endpoint", "Authorization Grant", "Authorization Server", "Client", "Client Authentication", "Client Identifier", "Client Secret", "Grant Type", "Protected Resource", "Redirection URI", "Refresh Token", "Resource Owner", "Resource Server", "Response Type", and "Token Endpoint" defined by OAuth 2.0 [RFC6749], the terms "Claim Name", "Claim Value", and "JSON Web Token (JWT)" defined by JSON Web Token (JWT) [JWT].¶
This specification defines the following term:¶
https scheme and has no fragment component.
As in Section 2 of [RFC8707], it also SHOULD NOT include
a query component, but it is recognized that there are cases that make
a query component a useful and necessary part of a resource identifier.
Protected resource metadata is published at a
.well-known location
[RFC8615]
derived from this resource identifier,
as described in Section 3.¶
Protected resources can have metadata describing their configuration. The following protected resource metadata parameters are used by this specification and are registered in the IANA "OAuth Protected Resource Metadata" registry established in Section 8.1:¶
https scheme.
When both signing and encryption keys are made available,
a use (public key use) parameter
value is REQUIRED for all keys in the referenced JWK Set
to indicate each key's intended usage.¶
scope values that
are used in authorization requests to request access to this protected resource.
Protected resources MAY choose not to advertise some scope values supported
even when this parameter is used.¶
["header", "body", "query"],
corresponding to Sections 2.1, 2.2, and 2.3 of RFC 6750.
The empty array [] can be used
to indicate that no Bearer methods are supported.
If this entry is omitted,
no default Bearer methods supported are implied,
nor does its absence indicate that they are not supported.¶
alg values) [JWA]
supported by the protected resource for signing resource responses,
for instance,
as described in [FAPI.MessageSigning].
No default algorithms are implied if this entry is omitted.
The value none MUST NOT be used.¶
type values supported by the resource server
when the authorization_details
request parameter [RFC9396] is used.¶
Additional protected resource metadata parameters MAY also be used.¶
Human-readable resource metadata values
and resource metadata values that reference human-readable content
MAY be represented in multiple languages and scripts.
For example, the values of fields such as
resource_name,
resource_documentation,
resource_tos_uri, and
resource_policy_uri
might have multiple locale-specific metadata values
to facilitate use in different locations.¶
To specify the languages and scripts, BCP 47 [RFC5646]
language tags are added to resource metadata parameter names,
delimited by a # character.
Since JSON [RFC8259] member names are case sensitive,
it is RECOMMENDED that language tag values used in Claim Names be spelled
using the character case with which they are registered in the
"IANA Language Subtag" registry [IANA.Language].
In particular, normally language names are spelled with lowercase
characters, region names are spelled with uppercase characters,
and languages are spelled with mixed-case characters.
However, since BCP 47 language tag values are case-insensitive,
implementations SHOULD interpret the language tag values supplied
in a case insensitive manner.
Per the recommendations in BCP 47, language tag values used in
metadata parameter names should only be as specific as necessary.
For instance, using fr might be sufficient
in many contexts, rather than fr-CA
or fr-FR.¶
For example, a resource could represent its name in English as
"resource_name#en": "My Resource"
and its name in Italian as
"resource_name#it": "La mia bella risorsa"
within its metadata.
Any or all of these names MAY be displayed to the end-user,
choosing which names to display based on system configuration,
user preferences, or other factors.¶
If any human-readable field is sent without a language tag, parties using it MUST NOT make any assumptions about the language, character set, or script of the string value, and the string value MUST be used as is wherever it is presented in a user interface. To facilitate interoperability, it is RECOMMENDED that each kind of human-readable metadata provided includes an instance of its metadata parameter without any language tags in addition to any language-specific parameters, and it is RECOMMENDED that any human-readable fields sent without language tags contain values suitable for display on a wide variety of systems.¶
In addition to JSON elements, metadata values MAY also be provided
as a signed_metadata value,
which is a JSON Web Token (JWT) [JWT]
that asserts metadata values about the protected resource as a bundle.
A set of metadata parameters that can be used in signed metadata as claims
are defined in Section 2.
The signed metadata MUST be digitally signed or MACed
using JSON Web Signature (JWS) [JWS]
and MUST contain an iss (issuer) claim
denoting the party attesting to the claims in the signed metadata.
Consumers of the metadata MAY ignore the signed metadata
if they do not support this feature.
If the consumer of the metadata supports signed metadata,
metadata values conveyed in the signed metadata
MUST take precedence over the corresponding values conveyed using plain JSON elements.¶
Signed metadata is included in the protected resource metadata JSON object using this OPTIONAL metadata parameter:¶
signed_metadata
parameter SHOULD NOT appear as a claim in the JWT;
it is RECOMMENDED to reject any metadata in which this occurs.¶
Protected resources supporting metadata
MUST make a JSON document containing metadata as specified in Section 2
available at a URL formed by
inserting a well-known URI string into the protected resource's resource identifier
between the host component and the path and/or query components, if any.
By default, the well-known URI string used is
/.well-known/oauth-protected-resource.
The syntax and semantics of .well-known
are defined in [RFC8615].
The well-known URI path suffix used MUST be registered in the IANA
"Well-Known URIs" registry [IANA.well-known].
Examples of this construction can be found in Section 3.1.¶
The term "application", as used below (and as used in [RFC8414]), encompasses all the components used to accomplish the task for the use case. That can include OAuth clients, authorization servers, protected resources, and non-OAuth components, inclusive of the code running in each of them. Applications are built to solve particular problems and may utilize many components and services.¶
Different applications utilizing OAuth protected resources in application-specific ways
MAY define and register different well-known URI path suffixes
for publishing protected resource metadata used by those applications.
For instance, if the Example application uses an OAuth protected resource in an Example-specific way,
and there are Example-specific metadata values that it needs to publish,
then it might register and use the
example-protected-resource URI path suffix and publish
the metadata document at the URL formed by inserting
/.well-known/example-protected-resource
between the host and path and/or query components of the
protected resource's resource identifier.
Alternatively, many such applications will use the default well-known URI string
/.well-known/oauth-protected-resource,
which is the right choice for general-purpose OAuth protected resources,
and not register an application-specific one.¶
An OAuth 2.0 application using this specification MUST specify
what well-known URI suffix it will use for this purpose.
The same protected resource MAY choose to publish its metadata at multiple
well-known locations derived from its resource identifier,
for example, publishing metadata at both
/.well-known/example-protected-resource and
/.well-known/oauth-protected-resource.¶
A protected resource metadata document MUST be queried using an HTTP
GET request at the previously specified URL.¶
The consumer of the metadata would make the following request when the
resource identifier is https://resource.example.com
and the well-known URI path suffix is oauth-protected-resource
to obtain the metadata,
since the resource identifier contains no path component:¶
GET /.well-known/oauth-protected-resource HTTP/1.1 Host: resource.example.com¶
If the resource identifier value contains a path or query component,
any terminating / following the host component
MUST be removed before inserting
/.well-known/ and the well-known URI path suffix
between the host component and the path and/or query components.
The consumer of the metadata would make the following request when the
resource identifier is https://resource.example.com/resource1
and the well-known URI path suffix is oauth-protected-resource
to obtain the metadata,
since the resource identifier contains a path component:¶
GET /.well-known/oauth-protected-resource/resource1 HTTP/1.1 Host: resource.example.com¶
Using path components enables supporting multiple resources per host.
This is required in some multi-tenant hosting configurations.
This use of .well-known is for supporting
multiple resources per host; unlike its use in
[RFC8615], it does not provide
general information about the host.¶
The response is a set of metadata parameters about the protected resource's
configuration.
A successful response MUST use the 200 OK HTTP status code and return
a JSON object using the application/json content type
that contains a set of metadata parameters as its members
that are a subset of the metadata parameters defined in
Section 2.
Additional metadata parameters MAY be defined and used;
any metadata parameters that are not understood MUST be ignored.¶
Parameters with multiple values are represented as JSON arrays. Parameters with zero values MUST be omitted from the response.¶
An error response uses the applicable HTTP status code value.¶
The following is a non-normative example response:¶
HTTP/1.1 200 OK
Content-Type: application/json
{
"resource":
"https://resource.example.com",
"authorization_servers":
["https://as1.example.com",
"https://as2.example.net"],
"bearer_methods_supported":
["header", "body"],
"scopes_supported":
["profile", "email", "phone"],
"resource_documentation":
"https://resource.example.com/resource_documentation.html"
}
¶
The resource value returned MUST be identical to
the protected resource's resource identifier value into which
the well-known URI path suffix was inserted to create the URL
used to retrieve the metadata.
If these values are not identical, the data contained in the response MUST NOT be used.¶
If the protected resource metadata was retrieved from a URL
returned by the protected resource via the WWW-Authenticate
resource_metadata parameter, then
the resource value returned MUST be identical to
the URL that the client used to make the request to the resource server.
If these values are not identical, the data contained in the response MUST NOT be used.¶
These validation actions can thwart impersonation attacks, as described in Section 7.3.¶
The recipient MUST validate that any signed metadata was signed by a key belonging to the issuer and that the signature is valid. If the signature does not validate or the issuer is not trusted, the recipient SHOULD treat this as an error condition.¶
To support use cases in which the set of legitimate protected resources
to use with the authorization server is enumerable,
this specification defines the authorization server metadata parameter
protected_resources,
which enables the authorization server to explicitly list the protected resources.
Note that if the set of legitimate authorization servers
to use with a protected resource is also enumerable,
lists in the authorization server metadata and protected resource metadata
should be cross-checked against one another for consistency
when these lists are used by the application profile.¶
The following authorization server metadata parameter is defined by this specification and is registered in the IANA "OAuth Authorization Server Metadata" registry established in OAuth 2.0 Authorization Server Metadata [RFC8414].¶
A protected resource MAY use the WWW-Authenticate
[RFC9110] HTTP response header field
to return a URL to its protected resource metadata to the client.
The client can then retrieve protected resource metadata as described in Section 3.
The client might then, for instance, determine what authorization server to use for the resource
based on protected resource metadata retrieved.¶
A typical end-to-end flow doing so is as follows. Note that while this example uses the OAuth 2.0 Authorization Code flow, a similar sequence could also be implemented with any other OAuth flow.¶
The client makes a request to a protected resource without presenting an access token.¶
The resource server responds with a WWW-Authenticate header including the URL of the protected resource metadata.¶
The client fetches the protected resource metadata from this URL.¶
The resource server responds with the protected resource metadata according to Section 3.2.¶
The client validates the protected resource metadata, as described in Section 3.3.¶
The client builds the authorization server metadata URL from an issuer identifier in the resource metadata according to [RFC8414] and makes a request to fetch the authorization server metadata.¶
The authorization server responds with the authorization server metadata document according to [RFC8414].¶
The client directs the user agent to the authorization server to begin the authorization flow.¶
The authorization exchange is completed and the authorization server returns an access token to the client.¶
The client repeats the resource request from step 1, presenting the newly obtained access token.¶
The resource server returns the requested protected resource.¶
This specification introduces a new parameter in the
WWW-Authenticate HTTP response header field
to indicate the protected resource metadata URL:¶
The response below is an example of a WWW-Authenticate header that includes the resource identifier.¶
HTTP/1.1 400 Bad Request
WWW-Authenticate: Bearer error="invalid_request",
error_description="No access token was provided in this request",
resource_metadata=
"https://resource.example.com/.well-known/oauth-protected-resource"
¶
The HTTP status code and error string in the example response above are defined by [RFC6750].¶
This parameter MAY also be used in
WWW-Authenticate responses using
Authorization schemes other than
Bearer [RFC6750],
such as the DPoP scheme
defined by [RFC9449].¶
The resource_metadata parameter MAY be combined with other parameters defined in other extensions,
such as the max_age parameter defined by [RFC9470].¶
At any point, for any reason determined by the resource server,
the protected resource MAY respond with a new WWW-Authenticate challenge
that includes a value for the protected resource metadata URL to indicate that its metadata may have changed.
If the client receives such a WWW-Authenticate response,
it SHOULD retrieve the updated protected resource metadata
and use the new metadata values obtained, after validating them
as described in Section 3.3.
Among other things,
this enables a resource server to change which authorization servers it uses without any other coordination with clients.¶
The way in which the client identifier is established at the authorization server is out of scope of this specification.¶
This specification is intended to be deployed in scenarios where the client has no prior knowledge about the resource server, and the resource server might or might not have prior knowledge about the client.¶
There are some existing methods by which an unrecognized client can make use of an authorization server, such as using Dynamic Client Registration [RFC7591] to register the client prior to initiating the authorization flow. Future OAuth extensions might define alternatives, such as using URLs to identify clients.¶
Resource servers MAY return other WWW-Authenticate headers indicating various authentication schemes.
This allows the resource server to support clients that may or may not implement this specification,
and allows clients to choose their preferred authentication scheme.¶
Processing some OAuth 2.0 messages requires comparing
values in the messages to known values. For example, the
member names in the metadata response might be
compared to specific member names such as resource. Comparing Unicode [UNICODE] strings,
however, has significant security implications.¶
Therefore, comparisons between JSON strings and other Unicode strings MUST be performed as specified below:¶
Remove any JSON applied escaping to produce an array of Unicode code points.¶
Unicode Normalization [USA15] MUST NOT be applied at any point to either the JSON string or to the string it is to be compared against.¶
Comparisons between the two strings MUST be performed as a Unicode code point to code point equality comparison.¶
Note that this is the same equality comparison procedure described in Section 8.3 of [RFC8259].¶
Implementations MUST support TLS. They MUST follow the guidance in BCP 195 [RFC8996] [RFC9325], which provides recommendations and requirements for improving the security of deployed services that use TLS.¶
Use of TLS at the protected resource metadata URLs protects against information disclosure and tampering.¶
The scopes_supported parameter is the list of scopes the resource server is willing to disclose that it supports. It is not meant to indicate that an OAuth client should request all scopes in the list. The client SHOULD still follow OAuth best practices and request tokens with as limited scope as possible for the given operation, as described in Section 2.3 of OAuth 2.0 Security Best Current Practice [I-D.ietf-oauth-security-topics].¶
TLS certificate checking MUST be performed by the client as described in [RFC9525] when making a protected resource metadata request. Checking that the server certificate is valid for the resource identifier URL prevents man-in-middle and DNS-based attacks. These attacks could cause a client to be tricked into using an attacker's resource server, which would enable impersonation of the legitimate protected resource. If an attacker can accomplish this, they can access the resources that the affected client has access to using the protected resource that they are impersonating.¶
An attacker may also attempt to impersonate a protected resource by publishing
a metadata document that contains a resource metadata parameter
using the resource identifier URL of the protected resource being impersonated,
but containing information of the attacker's choosing.
This would enable it to impersonate that protected resource, if accepted by the client.
To prevent this, the client MUST ensure that the resource identifier URL it is using
as the prefix for the metadata request exactly matches the value of
the resource metadata parameter
in the protected resource metadata document received by the client,
as described in Section 3.3.¶
If a client expects to interact with multiple resource servers, the client SHOULD request audience-restricted access tokens using [RFC8707], and the authorization server SHOULD support audience-restricted access tokens.¶
Without audience-restricted access tokens, a malicious resource server (RS1) may be
able to use the WWW-Authenticate header to get a client
to request an access token with a scope used by a legitimate resource server (RS2), and
after the client sends a request to RS1, then RS1 could re-use the access token at RS2.¶
While this attack is not explicitly enabled by this specification, and is possible in a plain OAuth 2.0 deployment, it is made somewhat more likely by the use of dynamically-configured clients. As such, the use of audience-restricted access tokens and Resource Indicators [RFC8707] is RECOMMENDED when using the features in this specification.¶
Publishing information about the protected resource in a standard format makes it easier for both legitimate clients and attackers to use the protected resource. Whether a protected resource publishes its metadata in an ad-hoc manner or in the standard format defined by this specification, the same defenses against attacks that might be mounted that use this information should be applied.¶
To support use cases in which the set of legitimate authorization servers
to use with the protected resource is enumerable,
this specification defines the authorization_servers
metadata parameter, which enables explicitly listing them.
Note that if the set of legitimate protected resources
to use with an authorization server is also enumerable,
lists in the protected resource metadata and authorization server metadata
should be cross-checked against one another for consistency
when these lists are used by the application profile.¶
Secure determination of appropriate authorization servers to use with a protected resource for all use cases is out of scope of this specification. This specification assumes that the client has a means of determining appropriate authorization servers to use with a protected resource and that the client is using the correct metadata for each protected resource. Implementers need to be aware that if an inappropriate authorization server is used by the client, that an attacker may be able to act as a man-in-the-middle proxy to a valid authorization server without it being detected by the authorization server or the client.¶
The ways to determine the appropriate authorization servers to use with a protected resource are in general, application-dependent. For instance, some protected resources are used with a fixed authorization server or set of authorization servers, the locations of which may be well known, or which could be published as metadata values by the protected resource. In other cases, the set of authorization servers that can be used with a protected resource can by dynamically changed by administrative actions or by changes to the set of authorization servers adhering to a trust framework. Many other means of determining appropriate associations between protected resources and authorization servers are also possible.¶
The OAuth client is expected to fetch the authorization server metadata based on the value of the issuer in the resource server metadata. Since this specification enables clients to interoperate with RSs and ASs it has no prior knowledge of, this opens a risk for SSRF attacks by malicious users or malicious resource servers. Clients SHOULD take appropriate precautions against SSRF attacks, such as blocking requests to internal IP address ranges. Further recommendations can be found in the OWASP SSRF Prevention Cheat Sheet [OWASP.SSRF].¶
This specification may be deployed in a scenario where the desired HTTP resource is identified by a user-selected URL. If this resource is malicious or compromised, it could mislead the user into revealing their account credentials or authorizing unwanted access to OAuth-controlled capabilities. This risk is reduced, but not eliminated, by following best practices for OAuth user interfaces, such as providing clear notice to the user, displaying the authorization server's domain name, supporting origin-bound phishing-resistant authenticators, supporting the use of password managers, and applying heuristic checks such as domain reputation.¶
Unsigned metadata is integrity protected by use of TLS at the site where it is hosted. This means that its security is dependent upon the Internet Public Key Infrastructure (PKI) [RFC9525]. Signed metadata is additionally integrity protected by the JWS signature applied by the issuer, which is not dependent upon the Internet PKI.¶
When using unsigned metadata, the party issuing the metadata
is the protected resource itself, which is represented by the
resource value in the metadata.
Whereas, when using signed metadata, the party issuing the metadata
is represented by the iss (issuer) claim
in the signed metadata.
When using signed metadata, applications can make trust decisions
based on the issuer that performed the signing --
information that is not available when using unsigned metadata.
How these trust decisions are made is out of scope for this specification.¶
Protected resource metadata is retrieved using an HTTP
GET request,
as specified in Section 3.1.
Normal HTTP caching behaviors apply, meaning that the GET may retrieve
a cached copy of the content, rather than the latest copy.
Implementations should utlize HTTP caching directives such as
Cache-Control
with max-age,
as defined in [RFC7234],
to enable caching of retrieved metadata for appropriate time periods.¶
The following registration procedure is used for the registry established by this specification.¶
Values are registered on a Specification Required [RFC8126] basis after a two-week review period on the oauth-ext-review@ietf.org mailing list, on the advice of one or more Designated Experts. However, to allow for the allocation of values prior to publication of the final version of a specification, the Designated Experts may approve registration once they are satisfied that the specification will be completed and published. However, if the specification is not completed and published in a timely manner, as determined by the Designated Experts, the Designated Experts may request that IANA withdraw the registration.¶
Registration requests sent to the mailing list for review should use an appropriate subject (e.g., "Request to register OAuth Protected Resource Metadata: example").¶
Within the review period, the Designated Experts will either approve or deny the registration request, communicating this decision to the review list and IANA. Denials should include an explanation and, if applicable, suggestions as to how to make the request successful. The IANA escalation process is followed when the Designated Experts are not responsive within 14 days.¶
Criteria that should be applied by the Designated Experts includes determining whether the proposed registration duplicates existing functionality, determining whether it is likely to be of general applicability or whether it is useful only for a single application, and whether the registration makes sense.¶
IANA must only accept registry updates from the Designated Experts and should direct all requests for registration to the review mailing list.¶
It is suggested that multiple Designated Experts be appointed who are able to represent the perspectives of different applications using this specification, in order to enable broadly-informed review of registration decisions. In cases where a registration decision could be perceived as creating a conflict of interest for a particular Expert, that Expert should defer to the judgment of the other Experts.¶
The reason for the use of the mailing list is to enable public review of registration requests, enabling both Designated Experts and other interested parties to provide feedback on proposed registrations. The reason to allow the Designated Experts to allocate values prior to publication as a final specification is to enable giving authors of specifications proposing registrations the benefit of review by the Designated Experts before the specification is completely done, so that if problems are identified, the authors can iterate and fix them before publication of the final specification.¶
This specification establishes the IANA "OAuth Protected Resource Metadata" registry for OAuth 2.0 protected resource metadata names. The registry records the protected resource metadata parameter and a reference to the specification that defines it.¶
Metadata Name: resource¶
Metadata Description: Protected resource's resource identifier URL¶
Change Controller: IETF¶
Specification Document(s): Section 2 of [[ this specification ]]¶
Metadata Name: authorization_servers¶
Metadata Description: JSON array containing a list of OAuth authorization server issuer identifiers¶
Change Controller: IETF¶
Specification Document(s): Section 2 of [[ this specification ]]¶
Metadata Name: jwks_uri¶
Metadata Description: URL of the protected resource's JWK Set document¶
Change Controller: IETF¶
Specification Document(s): Section 2 of [[ this specification ]]¶
Metadata Name: scopes_supported¶
Metadata Description:
JSON array containing a list of the OAuth 2.0
scope values that
are used in authorization requests to request access to this protected resource¶
Change Controller: IETF¶
Specification Document(s): Section 2 of [[ this specification ]]¶
Metadata Name: bearer_methods_supported¶
Metadata Description: JSON array containing a list of the OAuth 2.0 Bearer Token presentation methods that this protected resource supports¶
Change Controller: IETF¶
Specification Document(s): Section 2 of [[ this specification ]]¶
Metadata Name: resource_signing_alg_values_supported¶
Metadata Description:
JSON array containing a list of the JWS signing algorithms
(alg values)
supported by the protected resource
for signed content¶
Change Controller: IETF¶
Specification Document(s): Section 2 of [[ this specification ]]¶
Metadata Name: resource_name¶
Metadata Description: Human-readable name of the protected resource¶
Change Controller: IETF¶
Specification Document(s): Section 2 of [[ this specification ]]¶
Metadata Name: resource_documentation¶
Metadata Description: URL of a page containing human-readable information that developers might want or need to know when using the protected resource¶
Change Controller: IETF¶
Specification Document(s): Section 2 of [[ this specification ]]¶
Metadata Name: resource_policy_uri¶
Metadata Description: URL of a page containing human-readable information about the protected resource's requirements on how the client can use the data provided by the protected resource¶
Change Controller: IETF¶
Specification Document(s): Section 2 of [[ this specification ]]¶
Metadata Name: resource_tos_uri¶
Metadata Description: URL of a page containing human-readable information about the protected resource's terms of service¶
Change Controller: IETF¶
Specification Document(s): Section 2 of [[ this specification ]]¶
Metadata Name: tls_client_certificate_bound_access_tokens¶
Metadata Description: Boolean value indicating protected resource support for mutual-TLS client certificate-bound access tokens¶
Change Controller: IETF¶
Specification Document(s): Section 2 of [[ this specification ]]¶
Metadata Name: authorization_details_types_supported¶
Metadata Description:
JSON array containing a list of the authorization details
type values supported by the resource server
when the authorization_details
request parameter is used¶
Change Controller: IETF¶
Specification Document(s): Section 2 of [[ this specification ]]¶
Metadata Name: dpop_signing_alg_values_supported¶
Metadata Description: JSON array containing a list of the JWS alg values supported by the resource server for validating DPoP proof JWTs¶
Change Controller: IETF¶
Specification Document(s): Section 2 of [[ this specification ]]¶
Metadata Name: dpop_bound_access_tokens_required¶
Metadata Description: Boolean value specifying whether the protected resource always requires the use of DPoP-bound access tokens¶
Change Controller: IETF¶
Specification Document(s): Section 2 of [[ this specification ]]¶
Metadata Name: signed_metadata¶
Metadata Description: Signed JWT containing metadata parameters about the protected resource as claims¶
Change Controller: IETF¶
Specification Document(s): Section 2.2 of [[ this specification ]]¶
The following authorization server metadata parameter is registered in the IANA "OAuth Authorization Server Metadata" registry established in OAuth 2.0 Authorization Server Metadata [RFC8414].¶
This specification registers the well-known URI defined in Section 3 in the IANA "Well-Known URIs" registry [IANA.well-known].¶
The authors of this specification would like to thank the attendees of the IETF 115 OAuth and HTTP API Working Group meetings and the attendees of subsequent OAuth Working Group meetings for their input on this specification. We would would also like to thank Amanda Baber, Mike Bishop, Ralph Bragg, Brian Campbell, Deb Cooley, Roman Danyliw, Gabriel Corona, Vladimir Dzhuvinov, George Fletcher, Arnt Gulbrandsen, Pieter Kasselman, Murray Kucherawy, David Mandelberg, Tony Nadalin, Francesca Palombini, John Scudder, Rifaat Shekh-Yusef, Filip Skokan, Orie Steele, Atul Tulshibagwale, Éric Vyncke, Paul Wouters, and Bo Wu for their contributions to the specification.¶
[[ to be removed by the RFC Editor before publication as an RFC ]]¶
-13¶
Described motivations for the IANA registration procedure, per additional comments by Murray Kucherawy.¶
-12¶
Incorporated responses to IESG review comments by John Scudder, Murray Kucherawy, Francesca Palombini, and Éric Vyncke. The IANA registration procedure was updated per the discussion on the IESG telechat.¶
-11¶
Incorporated responses to HttpDir review comments by Mike Bishop.¶
Incorporated responses to IESG review comments by Roman Danyliw.¶
Incorporated responses to IESG review comments by Orie Steele. Particularly, the specification now allows resource identifiers to contain a query component (but still discourages it).¶
Consistently use the term "metadata parameter". The terms "metadata value" and "claim" were previously inconsistently used for the same thing.¶
-10¶
Added metadata parameter declaring RAR types supported.¶
-09¶
Added metadata values declaring support for DPoP and mutual-TLS client certificate-bound access tokens.¶
Added missing word caught during IANA review.¶
Addressed ART, SecDir, and OpsDir review comments by Arnt Gulbrandsen, David Mandelberg, and Bo Wu, resulting in the following changes.¶
Added step numbers to sequence diagram.¶
Defined meaning of omitting
bearer_methods_supported
metadata parameter.¶
Added internationalization of human-readable metadata values using the mechanism from [RFC7591].¶
Added resource_name metadata parameter,
paralleling client_name in [RFC7591].¶
Added Security Considerations section on metadata caching.¶
Used and referenced Resource Identifier definition.¶
Added motivating example of an email client to intro.¶
-08¶
Added Security Considerations about the differences between unsigned and signed metadata, as suggested by Deb Cooley.¶
Updated obsolete references.¶
-07¶
Removed extraneous paragraph about downgrade attacks discussing an issue that's already addressed elsewhere in the specification.¶
-06¶
Addressed shepherd review comments by Rifaat Shekh-Yusef.¶
-05¶
Added SVG diagram¶
-04¶
Applied working group last call suggestions by Atul Tulshibagwale.¶
Better described the purpose of
resource_signing_alg_values_supported and
removed resource_encryption_alg_values_supported and
resource_encryption_enc_values_supported,
per WGLC comments by Vladimir Dzhuvinov and Brian Campbell.¶
Applied suggestions by Pieter Kasselman.¶
-03¶
Applied correction by Filip Skokan.¶
-02¶
Switched from concatenating .well-known to the end of the resource identifier to inserting it between the host and path components of it.¶
Have WWW-Authenticate return resource_metadata rather than resource.¶
-01¶
Renamed scopes_provided to scopes_supported.¶
Added security consideration for scopes_supported.¶
Use BCP 195 for TLS recommendations.¶
Clarified that resource metadata can be used by clients and authorization servers.¶
Updated references.¶
Added security consideration recommending audience-restricted access tokens.¶
Mention FAPI Message Signing as a use case for publishing signing keys.¶
-00¶
Initial working group version based on draft-jones-oauth-resource-metadata-04.¶