Open Authentication Protocol A. Parecki
Internet-Draft Okta
Intended status: Standards Track August 29, 2019
Expires: March 1, 2020
OAuth 2.0 Client Intermediary Metadata
draft-parecki-oauth-client-intermediary-metadata-00
Abstract
This specification defines a mechanism for including information
about additional parties involved in an OAuth transaction by adding a
new section to the OAuth 2.0 Dynamic Client Registration request, as
well as requires that authorization servers surface this information
to users during an OAuth transaction.
Status of This Memo
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1. Introduction
In some applications of OAuth, an OAuth client is acting on behalf of
one or more intermediary or user-facing applications, and is not the
entity that the user has an established relationship with. In the
traditional OAuth model, a client_id represents only one application,
and so the consent screen lists just one third party: the OAuth
client. In these cases, it is not appropriate to list only the
actual OAuth client or only the user-facing application. Listing
only the actual OAuth client would be confusing to the user, since
the user does not have a relationship with this entity. Listing only
the user-facing application would be inaccurate and misrepresent the
situation, since the user would be unaware that their data is
actually being handled by additional parties.
This specification extends [RFC7591] and [RFC7592] to define a
mechanism for including information about the additional parties
involved in an OAuth transaction by including information about the
additional intermediaries as well as the user-facing application into
the Dynamic Client Registration request. This specification also
defines requirements of the OAuth authorization server to present
this information about the additional parties in the OAuth consent
screen during an OAuth transaction.
2. Notational Conventions
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
[RFC2119].
Unless otherwise noted, all the protocol parameter names and values
are case sensitive.
3. Terminology
In addition to the terms defined in referenced specifications, this
document uses the following terms:
"OAuth": In this document, "OAuth" refers to OAuth 2.0, [RFC6749].
"End User Application (EUA)": The software that the end user
interacts with and has a relationship with, which is not the same
as the OAuth client interacting with the Resource Server.
"Intermediary": One or more entities that the user's data will pass
through or be shared with by using the OAuth client. This
information is voluntarily provided by the OAuth client, and is
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typically enforced by a business relationship between the
organization providing the Client and the organization providing
the Resource Server.
"Client": "Client" has the same definition as in OAuth 2.0, but is
worth pointing out explicitly here that the client in this case is
requesting and obtaining permission from the user to access their
resources while acting on behalf of the End User Application.
4. End User Application and Intermediary Metadata
Registered end user applications, as well as intermediaries, have a
set of metadata values associated with the client identifier of the
client that represents them in the OAuth transaction, such as a user-
visible name, logo, and URL.
Like the OAuth client metadata defined in [RFC7591] and [RFC7592],
these metadata values are used in the following ways:
o as input values to registration and update requests, and
o as output values in registration responses.
These values are used by the authorization server when displaying the
OAuth consent screen to the end user, to inform them of all the
additional parties that will be handling the user's data upon
approval.
The following metadata fields are defined by this specification. The
implementation and use of the fields is OPTIONAL unless stated
otherwise. All data member types (strings, arrays, numbers) are
defined in terms of their JSON ([RFC7159]) representations.
Some fields are expected to be displayed in the OAuth consent UI and
are designated accordingly.
"name"
REQUIRED. A human-readable name of the end user application or
intermediary. Authorization servers MUST display this field to the
end user on the OAuth consent screen.
"description"
REQUIRED. A human-readable description of the end user application
or intermediary. This is not intended to be displayed in the OAuth
consent screen.
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"uri"
A URL string of a web page providing information about the end user
application or intermediary. If present, the authorization server
SHOULD display this URL to the end user in a clickable fashion. It
is RECOMMENDED that clients always send this field. The value of
this field MUST point to a valid web page.
"logo_uri"
A URL string that references a logo for this end user application or
intermediary. If present, the authorization server SHOULD display
this image to the end user in the OAuth consent screen. The value of
this field MUST be a valid image file.
"contacts"
Array of strings representing ways to contact people responsible for
this end user application or intermediary, typically email addresses
or phone numbers. The authorization server MAY display these to the
end user in the OAuth consent screen. See Section 6 of [RFC7591] for
information on Privacy Considerations.
5. Client Registration Endpoint
The client registration endpoint is described in Section 3 of
[RFC7591].
Since this specification provides a mechanism for a client to assert
user information about additional parties other than itself, the
registration endpoint MUST be protected by an OAuth 2.0 access token
obtained by the client. The method by which the initial access token
is obtained by the client or developer is out of scope of this
specification, but is likely to be obtained using the client
credentials grant.
5.1. Client Registration Request
This specification extends the client registration request defined in
[RFC7591].
This operation registers a combination of client, end user
application, and optionally one or more intermediaries with an
authorization server. The authorization server assigns a unique
client identifier (and optionally a client secret) that represents
the combination of all the entities described in the registration
request.
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To register, the client or developer sends an HTTP POST as described
in Section 3.1 of [RFC7591], with an additional property named
"end_user_application" containing a JSON object with the end user
application registration information, and optionally a property named
"intermediaries" with a JSON array of objects of each intermediary's
registration information.
For example, the client could send the following registration request
to the client registration endpoint using its OAuth 2.0 access token
it has previously obtained using the client credentials grant.
The following is a non-normative example request:
POST /register HTTP/1.1
Content-Type: application/json
Accept: application/json
Host: server.example.com
Authorization: Bearer 8IGFGXKXZBV5LL38Y3X1
{
"client_name": "My Example Client",
"redirect_uris": [
"https://client.example.org/callback"
],
"logo_uri": "https://client.example.org/logo.png",
"end_user_application": {
"name": "User-Recognizable App Name",
"description": "This application is what the user
is interacting with in their browser",
"uri": "https://example.net/",
"logo_uri": "https://example.net/logo.png",
"contacts": [
"support@example.net"
]
},
"intermediaries": [
{
"name": "Partner App Name",
"description": "An application that may also receive
this user's data when the user authorizes the client",
"uri": "https://partner.example/",
"logo_uri": "https://partner.example/logo.png",
"contacts": [
"support@partner.example"
]
}
]
}
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5.2. Client Registration Response
This specification extends the client information response defined in
[RFC7591] and [RFC7592].
Upon a successful registration request, the authorization server
returns a client identifier for the combination of the client, end
user application, and any intermediaries specified in the request.
In addition to the response fields defined in Section 3.2 of
[RFC7591] and Section 3 of [RFC7592], the response MUST also contain
all registered metadata about the end user application and any
intermediaries. The authorization server MAY reject or replace any
of the requested metadata values submitted during the registration
and substitute them with suitable values.
The following is a non-normative example response of a successful
registration:
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HTTP/1.1 201 Created
Content-Type: application/json
Cache-Control: no-store
Pragma: no-cache
{
"client_id": "V8tvEkZWhDAdxSaKGUJZ",
"client_secret": "SpsuwZIxnp8bBEhp5sk1EKiIKTZ4X4DKU",
"grant_types": ["authorization_code", "refresh_token"],
"token_endpoint_auth_method": "client_secret_basic",
"registration_client_uri": "https://server.example.com/client/tmzaAMkyWlH3",
"registration_access_token": "MphaAqDaZT86C93ENWRZcf3dfU2dW6POASo8dFXa",
"client_name": "My Example Client",
"redirect_uris": [
"https://client.example.org/callback"
],
"logo_uri": "https://client.example.org/logo.png",
"end_user_application": {
"name": "User-Recognizable App Name",
"description": "This application is what the user is interacting
with in their browser",
"uri": "https://example.net/",
"logo_uri": "https://example.net/logo.png",
"contacts": [
"support@example.net"
]
},
"intermediaries": [
{
"name": "Partner App Name",
"description": "An application that may also receive
this user's data when the user authorizes the client",
"uri": "https://partner.example/",
"logo_uri": "https://partner.example/logo.png",
"contacts": [
"support@partner.example"
]
}
]
}
The "registration_client_uri" and "registration_access_token"
properties are required in order to support updating and deleting
this client as described in [RFC7592].
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5.3. Client Read Request
This specification extends the client read request defined in
[RFC7592] to include the additional metadata properties in the
response that describe the end user application and intermediaries.
No additional behavior is prescribed by this specification.
5.4. Client Update Request
This specification extends the client update request defined in
[RFC7592] to be able to update the additional metadata properties
that describe the end user application and intermediaries.
The additional properties are provided in the update request in the
same format as in the initial registration request.
Since these values were asserted by the client in the initial
registration, there is no need to prescribe any additional security
model around the ability to update them, even though these represent
additional parties.
5.5. Client Delete Request
No new behavior is prescribed for delete requests beyond that defined
in [RFC7592].
6. Providing End-User Application Details in the Authorization Request
When the authorization server begins a request from an OAuth client
identifier that has been registered with additional end user
application or intermediary information, it MUST display the
additional parties in the consent UI visible to the end user.
The authorization server MAY choose to emphasize or make the end user
application information the primary information displayed in the
consent screen. This is because the end user application is likely
the most recognizable entity to the end user, and the end user may
not be aware that it is actually a different organization's OAuth
client that is the one making requests for the user's data.
The authorization server chooses how best to display the additional
information, but it MUST include at least the name of the end user
application, intermediaries, and client, and SHOULD include the logo
of each as well.
Once an access token has been issued to this client, the client uses
the access token to make requests at the resource server on behalf of
the specific end user application on behalf of the end user.
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7. Acknowledgements
The authors would like to thank Ryan Christiansen and Preston
McFarland for their initial contributions of the concepts behind this
specification. The authors would also like to thank the OAuth
Working Group for their work on the referenced and related
specifications that this specification builds upon.
8. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[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>.
[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
2014, <https://www.rfc-editor.org/info/rfc7159>.
[RFC7591] Richer, J., Ed., Jones, M., Bradley, J., Machulak, M., and
P. Hunt, "OAuth 2.0 Dynamic Client Registration Protocol",
RFC 7591, DOI 10.17487/RFC7591, July 2015,
<https://www.rfc-editor.org/info/rfc7591>.
[RFC7592] Richer, J., Ed., Jones, M., Bradley, J., and M. Machulak,
"OAuth 2.0 Dynamic Client Registration Management
Protocol", RFC 7592, DOI 10.17487/RFC7592, July 2015,
<https://www.rfc-editor.org/info/rfc7592>.
Author's Address
Aaron Parecki
Okta
Email: aaron@parecki.com
URI: https://aaronparecki.com
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