OAuth Working Group J. Richer
Internet-Draft The MITRE Corporation
Intended status: Standards Track M. Jones
Expires: August 10, 2014 Microsoft
J. Bradley
Ping Identity
M. Machulak
Newcastle University
P. Hunt
Oracle Corporation
February 6, 2014
OAuth 2.0 Dynamic Client Registration Core Protocol
draft-ietf-oauth-dyn-reg-16
Abstract
This specification defines mechanisms used to dynamically register
OAuth 2.0 clients at authorization servers.
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 http://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 August 10, 2014.
Copyright Notice
Copyright (c) 2014 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
(http://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
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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 . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Notational Conventions . . . . . . . . . . . . . . . . . . 4
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
1.3. Protocol Flow . . . . . . . . . . . . . . . . . . . . . . 6
2. Client Metadata . . . . . . . . . . . . . . . . . . . . . . . 7
2.1. Relationship between Grant Types and Response Types . . . 9
3. Software Statement . . . . . . . . . . . . . . . . . . . . . . 10
4. Client Registration Endpoint . . . . . . . . . . . . . . . . . 10
4.1. Client Registration Request . . . . . . . . . . . . . . . 11
4.2. Client Registration Response . . . . . . . . . . . . . . . 13
5. Responses . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.1. Client Information Response . . . . . . . . . . . . . . . 13
5.2. Client Registration Error Response . . . . . . . . . . . . 15
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
6.1. OAuth Registration Client Metadata Registry . . . . . . . 16
6.1.1. Registration Template . . . . . . . . . . . . . . . . 17
6.1.2. Initial Registry Contents . . . . . . . . . . . . . . 17
6.2. OAuth Token Endpoint Authentication Methods Registry . . . 18
6.2.1. Registration Template . . . . . . . . . . . . . . . . 18
6.2.2. Initial Registry Contents . . . . . . . . . . . . . . 19
7. Security Considerations . . . . . . . . . . . . . . . . . . . 19
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8.1. Normative References . . . . . . . . . . . . . . . . . . . 20
8.2. Informative References . . . . . . . . . . . . . . . . . . 21
Appendix A. Use Cases . . . . . . . . . . . . . . . . . . . . . . 22
A.1. Open versus Protected Dynamic Client Registration . . . . 22
A.1.1. Open Dynamic Client Registration . . . . . . . . . . . 22
A.1.2. Protected Dynamic Client Registration . . . . . . . . 22
A.2. Registration Without or With Software Statements . . . . . 22
A.2.1. Registration Without a Software Statement . . . . . . 22
A.2.2. Registration With a Software Statement . . . . . . . . 22
A.3. Registration by the Client or the Developer . . . . . . . 23
A.3.1. Registration by the Client . . . . . . . . . . . . . . 23
A.3.2. Registration by the Developer . . . . . . . . . . . . 23
A.4. Client ID per Client Instance or per Client Software . . . 23
A.4.1. Client ID per Client Software Instance . . . . . . . . 23
A.4.2. Client ID Shared between all Instances of Client
Software . . . . . . . . . . . . . . . . . . . . . . . 23
A.5. Stateful or Stateless Registration . . . . . . . . . . . . 23
A.5.1. Stateful Client Registration . . . . . . . . . . . . . 24
A.5.2. Stateless Client Registration . . . . . . . . . . . . 24
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . . 24
Appendix C. Document History . . . . . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 29
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1. Introduction
In order for an OAuth 2.0 client to utilize an OAuth 2.0
authorization server, the client needs specific information to
interact with the server, including an OAuth 2.0 Client ID to use at
that server. This specification describes how an OAuth 2.0 client
can be dynamically registered with an authorization server to obtain
this information.
As part of the registration process, this specification also defines
a mechanism for the client to present the authorization server with a
set of metadata, such as a set of valid redirection URIs. This
metadata can either be communicated in a self-asserted fashion or as
a set of metadata called a software statement, which can be signed;
in the case of a signed software statement, the signer is vouching
for the validity of the data about the client.
The mechanisms defined in this specification can be used either for a
client to dynamically register itself with authorization servers or
for a client developer to programmatically register the client with
authorization servers.
1.1. Notational Conventions
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT',
'SHOULD', 'SHOULD 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.
1.2. Terminology
This specification uses the terms "Access Token", "Refresh Token",
"Authorization Code", "Authorization Grant", "Authorization Server",
"Authorization Endpoint", "Client", "Client Identifier", "Client
Secret", "Protected Resource", "Resource Owner", "Resource Server",
"Response Type", and "Token Endpoint" defined by OAuth 2.0 [RFC6749]
and uses the term "Claim" defined by JSON Web Token (JWT) [JWT].
This specification defines the following terms:
Client Developer The person or organization that builds a client
software package and prepares it for distribution. A client
developer obtains a software statement from a software publisher,
or self-generates one for the purposes of facilitating client
registration.
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Client Instance A deployed instance of a piece of client software.
Multiple instances of the same piece of client software MAY use
the same Client ID value at an authorization server, provided that
the Redirection URI values and potentially other values dictated
by authorization server policy are the same for all instances.
Client Software Software implementing an OAuth 2.0 client.
Client Registration Endpoint OAuth 2.0 endpoint through which a
client can be registered at an authorization server. The means by
which the URL for this endpoint is obtained are out of scope for
this specification.
Initial Access Token OAuth 2.0 access token optionally issued by an
Authorization Server and used to authorize calls to the client
registration endpoint. The type and format of this token are
likely service-specific and are out of scope for this
specification. The means by which the authorization server issues
this token as well as the means by which the registration endpoint
validates this token are out of scope for this specification.
Deployment Organization An administrative security domain under
which, a software API is deployed and protected by an OAuth 2.0
framework. In simple cloud deployments, the software API
publisher and the deployment organization may be the same. In
other scenarios, a software publisher may be working with many
different deployment organizations.
Software API Deployment A deployment instance of a software API that
is protected by OAuth 2.0 in a particular deployment organization
domain. For any particular software API, there may be one or more
deployments. A software API deployment typically has an
associated OAuth 2.0 authorization server endpoint as well as a
client registration endpoint. The means by which endpoints are
obtained (discovery) are out of scope for this specification.
Software API Publisher The organization that defines a particular
web accessible API that may deployed in one or more deployment
environments. A publisher may be any commercial, public, private,
or open source organization that is responsible for publishing and
distributing software that may be protected via OAuth 2.0. A
software API publisher may issue software statements which client
developers use to distribute with their software to facilitate
registration. In some cases a software API publisher and a client
developer may be the same organization.
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Software Statement A JSON Web Token (JWT) [JWT] that asserts
metadata values about the client software. The JWT MUST be signed
and contain an "iss" (issuer) claim if its metadata values are
being attested to by the issuer; if the metadata values are not
being attested to, the JWT MAY be unsigned. This can be used by
the registration system to qualify clients for eligibility to
register. It may also be accepted by some authorization servers
directly as a Client ID value, without prior registration.
1.3. Protocol Flow
+--------(A)- Initial Access Token (OPTIONAL)
|
| +----(B)- Software Statement (OPTIONAL)
| |
v v
+-----------+ +---------------+
| |--(C)- Client Registration Request -->| Client |
| Client or | | Registration |
| Developer |<-(D)- Client Information Response ---| Endpoint |
| | +---------------+
+-----------+
Figure 1: Abstract Dynamic Client Registration Flow
The abstract OAuth 2.0 client dynamic registration flow illustrated
in Figure 1 describes the interaction between the client or developer
and the endpoint defined in this specification. This figure does not
demonstrate error conditions. This flow includes the following
steps:
(A) Optionally, the client or developer is issued an initial access
token giving access to the client registration endpoint. The
method by which the initial access token is issued to the client
or developer is out of scope for this specification.
(B) Optionally, the client or developer is issued a software
statement for use with the client registration endpoint. The
method by which the software statement is issued to the client or
developer is out of scope for this specification.
(C) The client or developer calls the client registration endpoint
with its desired registration metadata, optionally including the
initial access token from (A) if one is required by the
authorization server.
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(D) The authorization server registers the client and returns the
client's registered metadata, a client identifier that is unique
at the server, a set of client credentials such as a client secret
if applicable for this client, and possibly other values.
2. Client Metadata
Clients have a set of metadata values associated with their unique
client identifier at an authorization server, such as the list of
valid redirect URIs.
The client metadata values are used in two ways:
o as input values to registration requests, and
o as output values in registration responses.
These client metadata values are defined by this specification:
redirect_uris Array of redirect URIs for use in redirect-based flows
such as the authorization code and implicit grant types. It is
RECOMMENDED that clients using these flows register this
parameter, and an authorization server SHOULD require registration
of valid redirect URIs for all clients that use these grant types
to protect against token and credential theft attacks.
token_endpoint_auth_method The requested authentication method for
the token endpoint. Values defined by this specification are:
* "none": The client is a public client as defined in OAuth 2.0
and does not have a client secret.
* "client_secret_post": The client uses the HTTP POST parameters
defined in OAuth 2.0 section 2.3.1.
* "client_secret_basic": the client uses HTTP Basic defined in
OAuth 2.0 section 2.3.1
Additional values can be defined via the IANA OAuth Token Endpoint
Authentication Methods Registry Section 6.2. Absolute URIs can
also be used as values for this parameter without being
registered. If unspecified or omitted, the default is
"client_secret_basic", denoting HTTP Basic Authentication Scheme
as specified in Section 2.3.1 of OAuth 2.0.
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grant_types Array of OAuth 2.0 grant types that the Client may use.
These grant types are defined as follows:
* "authorization_code": The Authorization Code Grant described in
OAuth 2.0 Section 4.1
* "implicit": The Implicit Grant described in OAuth 2.0 Section
4.2
* "password": The Resource Owner Password Credentials Grant
described in OAuth 2.0 Section 4.3
* "client_credentials": The Client Credentials Grant described in
OAuth 2.0 Section 4.4
* "refresh_token": The Refresh Token Grant described in OAuth 2.0
Section 6.
* "urn:ietf:params:oauth:grant-type:jwt-bearer": The JWT Bearer
Grant defined in OAuth JWT Bearer Token Profiles [OAuth.JWT].
* "urn:ietf:params:oauth:grant-type:saml2-bearer": The SAML 2
Bearer Grant defined in OAuth SAML 2 Bearer Token Profiles
[OAuth.SAML2].
Authorization Servers MAY allow for other values as defined in
grant type extensions to OAuth 2.0. The extension process is
described in OAuth 2.0 Section 2.5. If the token endpoint is used
in the grant type, the value of this parameter MUST be the same as
the value of the "grant_type" parameter passed to the token
endpoint defined in the extension.
response_types Array of the OAuth 2.0 response types that the Client
may use. These response types are defined as follows:
* "code": The Authorization Code response described in OAuth 2.0
Section 4.1.
* "token": The Implicit response described in OAuth 2.0 Section
4.2.
Authorization servers MAY allow for other values as defined in
response type extensions to OAuth 2.0. The extension process is
described in OAuth 2.0 Section 2.5. If the authorization endpoint
is used by the grant type, the value of this parameter MUST be the
same as the value of the "response_type" parameter passed to the
authorization endpoint defined in the extension.
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Authorization servers MUST accept all fields in this list.
Extensions and profiles of this specification MAY expand this list.
For instance, the [OAuth.Registration.Metadata] specification defines
additional client metadata values. The authorization server MUST
ignore any client metadata values sent by the Client that it does not
understand.
Client metadata values can either be communicated directly in the
body of a registration request, as described in Section 4.1, or
included as claims in a software statement, as described in
Section 3. If the same client metadata name is present in both
locations, the value in the software statement SHOULD take
precedence.
2.1. Relationship between Grant Types and Response Types
The "grant_types" and "response_types" values described above are
partially orthogonal, as they refer to arguments passed to different
endpoints in the OAuth protocol. However, they are related in that
the "grant_types" available to a client influence the
"response_types" that the client is allowed to use, and vice versa.
For instance, a "grant_types" value that includes
"authorization_code" implies a "response_types" value that includes
"code", as both values are defined as part of the OAuth 2.0
authorization code grant. As such, a server supporting these fields
SHOULD take steps to ensure that a client cannot register itself into
an inconsistent state.
The correlation between the two fields is listed in the table below.
+-----------------------------------------------+-------------------+
| grant_types value includes: | response_types |
| | value includes: |
+-----------------------------------------------+-------------------+
| authorization_code | code |
| implicit | token |
| password | (none) |
| client_credentials | (none) |
| refresh_token | (none) |
| urn:ietf:params:oauth:grant-type:jwt-bearer | (none) |
| urn:ietf:params:oauth:grant-type:saml2-bearer | (none) |
+-----------------------------------------------+-------------------+
Extensions and profiles of this document that introduce new values to
either the "grant_types" or "response_types" parameter MUST document
all correspondences between these two parameter types.
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3. Software Statement
A Software Statement is a JSON Web Token (JWT) [JWT] that asserts
metadata values about the client software. The JWT MUST be signed
and contain an "iss" (issuer) claim if its metadata values are being
attested to by the issuer; if the metadata values are not being
attested to, the JWT MAY be unsigned. This can be used by the
registration system to qualify clients for eligibility to register.
It may also be accepted by some authorization servers directly as a
Client ID value, without prior registration.
To obtain a software statement, a client developer may generate a
client specific JWT, or a client developer may register with a
software API publisher to obtain a software statement. The statement
is typically distributed with all copies of a client application.
The criteria by which authorization servers determine whether to
trust and utilize the information in a software statement is beyond
the scope of this specification.
If the authorization server determines that the claims in a software
statement uniquely identify a piece of software, the same Client ID
value MAY be returned for all dynamic registrations using that
software statement. However, authorization servers MAY alternatively
return a unique Client ID value for each dynamic registration of a
piece of software.
In some cases, authorization servers MAY choose to accept a software
statement value directly as a Client ID in an authorization request,
without a prior dynamic client registration having been performed.
The circumstances under which an authorization server would do so,
and the specific software statement characteristics required in this
case, are beyond the scope of this specification.
4. Client Registration Endpoint
The client registration endpoint is an OAuth 2.0 endpoint defined in
this document that is designed to allow a client to be registered
with the authorization server. The client registration endpoint MUST
accept HTTP POST messages with request parameters encoded in the
entity body using the "application/json" format. The client
registration endpoint MUST be protected by a transport-layer security
mechanism, and the server MUST support TLS 1.2 RFC 5246 [RFC5246]
and/or TLS 1.0 [RFC2246] and MAY support additional transport-layer
mechanisms meeting its security requirements. When using TLS, the
Client MUST perform a TLS/SSL server certificate check, per RFC 6125
[RFC6125].
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The client registration endpoint MAY be an OAuth 2.0 protected
resource and accept an initial access token in the form of an OAuth
2.0 [RFC6749] access token to limit registration to only previously
authorized parties. The method by which the initial access token is
obtained by the registrant is generally out-of-band and is out of
scope for this specification. The method by which the initial access
token is verified and validated by the client registration endpoint
is out of scope for this specification.
To support open registration and facilitate wider interoperability,
the client registration endpoint SHOULD allow initial registration
requests with no authorization (which is to say, with no OAuth 2.0
access token in the request). These requests MAY be rate-limited or
otherwise limited to prevent a denial-of-service attack on the client
registration endpoint.
The client registration endpoint MUST ignore all parameters it does
not understand.
4.1. Client Registration Request
This operation registers a new client to the authorization server.
The authorization server assigns this client a unique client
identifier, optionally assigns a client secret, and associates the
metadata given in the request with the issued client identifier. The
request includes any client metadata parameters being specified for
the client during the registration. The authorization server MAY
provision default values for any items omitted in the client
metadata.
Client metadata values may also be provided in a software statement,
as described in Section 3. Software statements are included in
registration requests using this registration parameter:
software_statement A software statement containing client metadata
values about the client software as claims.
To register, the client or developer sends an HTTP POST to the client
registration endpoint with a content type of "application/json". The
HTTP Entity Payload is a JSON [RFC4627] document consisting of a JSON
object and all parameters as top-level members of that JSON object.
For example, if the server supports open registration (with no
initial access token), the client could send the following
registration request to the client registration endpoint:
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The following is a non-normative example request not using an initial
access token (with line wraps within values for display purposes
only):
POST /register HTTP/1.1
Content-Type: application/json
Accept: application/json
Host: server.example.com
{
"redirect_uris":[
"https://client.example.org/callback",
"https://client.example.org/callback2"],
"token_endpoint_auth_method":"client_secret_basic",
"example_extension_parameter": "example_value"
}
Alternatively, if the server supports authorized registration, the
developer or the client will be provisioned with an initial access
token (the method by which the initial access token is obtained is
out of scope for this specification). The developer or client sends
the following authorized registration request to the client
registration endpoint. Note that the initial access token sent in
this example as an OAuth 2.0 Bearer Token [RFC6750], but any OAuth
2.0 token type could be used by an authorization server.
The following is a non-normative example request using an initial
access token (with line wraps within values for display purposes
only):
POST /register HTTP/1.1
Content-Type: application/json
Accept: application/json
Authorization: Bearer ey23f2.adfj230.af32-developer321
Host: server.example.com
{
"redirect_uris":["https://client.example.org/callback",
"https://client.example.org/callback2"],
"token_endpoint_auth_method":"client_secret_basic",
"example_extension_parameter": "example_value"
}
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In the following example, some registration parameters are conveyed
as claims in a software statement (with line wraps within values for
display purposes only):
POST /register HTTP/1.1
Content-Type: application/json
Accept: application/json
Host: server.example.com
{
"redirect_uris":[
"https://client.example.org/callback",
"https://client.example.org/callback2"
],
"software_statement":"eyJhbGciOiJFUzI1NiJ9.
eyJpc3Mi[...omitted for brevity...].
J9l-ZhwP[...omitted for brevity...]",
"extension_parameter":"foo"
}
4.2. Client Registration Response
Upon successful registration, the authorization server generates a
new client identifier for the client. This client identifier MUST be
unique at the server and MUST NOT be in use by any other client. The
server responds with an HTTP 201 Created code and a body of type
"application/json" with content as described in Section 5.1.
Upon an unsuccessful registration, the authorization server responds
with an error, as described in Section 5.2.
5. Responses
The following responses are sent in response to registration
requests.
5.1. Client Information Response
The response contains the client identifier as well as the client
secret, if the client is a confidential client. The response MAY
contain additional fields as specified by extensions to this
specification.
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client_id REQUIRED. Unique client identifier. It MUST NOT be
currently valid for any other distinct registered client. It MAY
be the same as the Client ID value used by other instances of this
client, provided that the Redirection URI values and potentially
other values dictated by authorization server policy are the same
for all instances.
client_secret OPTIONAL. The client secret. If issued, this MUST be
unique for each "client_id". This value is used by confidential
clients to authenticate to the token endpoint as described in
OAuth 2.0 [RFC6749] Section 2.3.1.
client_id_issued_at OPTIONAL. Time at which the Client Identifier
was issued. The time is represented as the number of seconds from
1970-01-01T0:0:0Z as measured in UTC until the date/time.
client_secret_expires_at REQUIRED if "client_secret" is issued.
Time at which the "client_secret" will expire or 0 if it will not
expire. The time is represented as the number of seconds from
1970-01-01T0:0:0Z as measured in UTC until the date/time.
Additionally, the Authorization Server MUST return all registered
metadata about this client, including any fields provisioned by the
authorization server itself. The authorization server MAY reject or
replace any of the client's requested metadata values submitted
during the registration or update requests and substitute them with
suitable values.
The response is an "application/json" document with all parameters as
top-level members of a JSON object [RFC4627].
If a software statement was used as part of the registration, its
value SHOULD be returned in the response and its value MUST be
returned if the authorization server supports registration management
operations [OAuth.Registration.Management] that would require its
presence in subsequent operations. Client metadata elements used
from the software statement MUST also be returned directly as top-
level client metadata values in the registration response (possibly
with different values, since the values requested and the values used
may differ).
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Following is a non-normative example response:
HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store
Pragma: no-cache
{
"client_id":"s6BhdRkqt3",
"client_secret": "cf136dc3c1fc93f31185e5885805d",
"client_id_issued_at":2893256800,
"client_secret_expires_at":2893276800,
"redirect_uris":[
"https://client.example.org/callback",
"https://client.example.org/callback2"],
"grant_types": ["authorization_code", "refresh_token"],
"token_endpoint_auth_method": "client_secret_basic",
"example_extension_parameter": "example_value"
}
5.2. Client Registration Error Response
When an OAuth 2.0 error condition occurs, such as the client
presenting an invalid initial access token, the authorization server
returns an error response appropriate to the OAuth 2.0 token type.
When a registration error condition occurs, the authorization server
returns an HTTP 400 status code (unless otherwise specified) with
content type "application/json" consisting of a JSON object [RFC4627]
describing the error in the response body.
The JSON object contains two members:
error Single ASCII error code string.
error_description Human-readable ASCII text description of the error
used for debugging.
This specification defines the following error codes:
invalid_redirect_uri The value of one or more "redirect_uris" is
invalid.
invalid_client_metadata The value of one of the client metadata
fields is invalid and the server has rejected this request. Note
that an Authorization server MAY choose to substitute a valid
value for any requested parameter of a client's metadata.
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invalid_software_statement The software statement presented is
invalid.
unapproved_software_statement The software statement presented is
not approved for use with this authorization server.
Following is a non-normative example of an error response (with line
wraps for display purposes only):
HTTP/1.1 400 Bad Request
Content-Type: application/json
Cache-Control: no-store
Pragma: no-cache
{
"error":"invalid_redirect_uri",
"error_description":"The redirect URI http://sketchy.example.com
is not allowed for this server."
}
6. IANA Considerations
6.1. OAuth Registration Client Metadata Registry
This specification establishes the OAuth Registration Client Metadata
registry.
OAuth registration client metadata values are registered with a
Specification Required ([RFC5226]) 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, the Designated Expert(s) may approve
registration once they are satisfied that such a specification will
be published.
Registration requests must be sent to the oauth-ext-review@ietf.org
mailing list for review and comment, with an appropriate subject
(e.g., "Request to register OAuth Registration Client Metadata name:
example").
Within the review period, the Designated Expert(s) 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.
IANA must only accept registry updates from the Designated Expert(s)
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and should direct all requests for registration to the review mailing
list.
6.1.1. Registration Template
Client Metadata Name: The name requested (e.g., "example"). This
name is case sensitive. Names that match other registered names
in a case insensitive manner SHOULD NOT be accepted.
Client Metadata Description:
Brief description of the metadata value (e.g., "Example
description").
Change controller: For Standards Track RFCs, state "IETF". For
others, give the name of the responsible party. Other details
(e.g., postal address, email address, home page URI) may also be
included.
Specification document(s): Reference to the document(s) that specify
the token endpoint authorization method, preferably including a
URI that can be used to retrieve a copy of the document(s). An
indication of the relevant sections may also be included but is
not required.
6.1.2. Initial Registry Contents
The initial contents of the OAuth Registration Client Metadata
registry are:
o Client Metadata Name: "redirect_uris"
o Client Metadata Description: Array of redirect URIs for use in
redirect-based flows
o Change controller: IESG
o Specification document(s): [[ this document ]]
o Client Metadata Name: "token_endpoint_auth_method"
o Client Metadata Description: Requested authentication method for
the token endpoint
o Change controller: IESG
o Specification document(s): [[ this document ]]
o Client Metadata Name: "grant_types"
o Client Metadata Description: Array of OAuth 2.0 grant types that
the Client may use
o Change controller: IESG
o Specification document(s): [[ this document ]]
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o Client Metadata Name: "response_types"
o Client Metadata Description: Array of the OAuth 2.0 response types
that the Client may use
o Change controller: IESG
o Specification document(s): [[ this document ]]
6.2. OAuth Token Endpoint Authentication Methods Registry
This specification establishes the OAuth Token Endpoint
Authentication Methods registry.
Additional values for use as "token_endpoint_auth_method" metadata
values are registered with a Specification Required ([RFC5226]) 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, the
Designated Expert(s) may approve registration once they are satisfied
that such a specification will be published.
Registration requests must be sent to the oauth-ext-review@ietf.org
mailing list for review and comment, with an appropriate subject
(e.g., "Request to register token_endpoint_auth_method value:
example").
Within the review period, the Designated Expert(s) 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.
IANA must only accept registry updates from the Designated Expert(s)
and should direct all requests for registration to the review mailing
list.
6.2.1. Registration Template
Token Endpoint Authorization Method Name: The name requested (e.g.,
"example"). This name is case sensitive. Names that match other
registered names in a case insensitive manner SHOULD NOT be
accepted.
Change controller: For Standards Track RFCs, state "IETF". For
others, give the name of the responsible party. Other details
(e.g., postal address, email address, home page URI) may also be
included.
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Specification document(s): Reference to the document(s) that specify
the token endpoint authorization method, preferably including a
URI that can be used to retrieve a copy of the document(s). An
indication of the relevant sections may also be included but is
not required.
6.2.2. Initial Registry Contents
The initial contents of the OAuth Token Endpoint Authentication
Methods registry are:
o Token Endpoint Authorization Method Name: "none"
o Change controller: IESG
o Specification document(s): [[ this document ]]
o Token Endpoint Authorization Method Name: "client_secret_post"
o Change controller: IESG
o Specification document(s): [[ this document ]]
o Token Endpoint Authorization Method Name: "client_secret_basic"
o Change controller: IESG
o Specification document(s): [[ this document ]]
7. Security Considerations
Since requests to the client registration endpoint result in the
transmission of clear-text credentials (in the HTTP request and
response), the Authorization Server MUST require the use of a
transport-layer security mechanism when sending requests to the
registration endpoint. The server MUST support TLS 1.2 RFC 5246
[RFC5246] and/or TLS 1.0 [RFC2246] and MAY support additional
transport-layer mechanisms meeting its security requirements. When
using TLS, the Client MUST perform a TLS/SSL server certificate
check, per RFC 6125 [RFC6125].
For clients that use redirect-based grant types such as
"authorization_code" and "implicit", authorization servers SHOULD
require clients to register their "redirect_uris". Requiring clients
to do so can help mitigate attacks where rogue actors inject and
impersonate a validly registered client and intercept its
authorization code or tokens through an invalid redirect URI.
Public clients MAY register with an authorization server using this
protocol, if the authorization server's policy allows them. Public
clients use a "none" value for the "token_endpoint_auth_method"
metadata field and are generally used with the "implicit" grant type.
Often these clients will be short-lived in-browser applications
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requesting access to a user's resources and access is tied to a
user's active session at the authorization server. Since such
clients often do not have long-term storage, it's possible that such
clients would need to re-register every time the browser application
is loaded. Additionally, such clients may not have ample opportunity
to unregister themselves using the delete action before the browser
closes. To avoid the resulting proliferation of dead client
identifiers, an authorization server MAY decide to expire
registrations for existing clients meeting certain criteria after a
period of time has elapsed.
Since different OAuth 2.0 grant types have different security and
usage parameters, an authorization server MAY require separate
registrations for a piece of software to support multiple grant
types. For instance, an authorization server might require that all
clients using the "authorization_code" grant type make use of a
client secret for the "token_endpoint_auth_method", but any clients
using the "implicit" grant type do not use any authentication at the
token endpoint. In such a situation, a server MAY disallow clients
from registering for both the "authorization_code" and "implicit"
grant types simultaneously. Similarly, the "authorization_code"
grant type is used to represent access on behalf of an end user, but
the "client_credentials" grant type represents access on behalf of
the client itself. For security reasons, an authorization server
could require that different scopes be used for these different use
cases, and as a consequence it MAY disallow these two grant types
from being registered together by the same client. In all of these
cases, the authorization server would respond with an
"invalid_client_metadata" error response.
8. References
8.1. Normative References
[JWT] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", draft-ietf-oauth-json-web-token (work in
progress), January 2014.
[OAuth.JWT]
Jones, M., Campbell, B., and C. Mortimore, "JSON Web Token
(JWT) Profile for OAuth 2.0 Client Authentication and
Authorization Grants", draft-ietf-oauth-jwt-bearer (work
in progress), December 2013.
[OAuth.Registration.Management]
Richer, J., Jones, M., Bradley, J., Machulak, M., and P.
Hunt, "OAuth 2.0 Dynamic Client Registration Management
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Protocol", draft-ietf-oauth-dyn-reg-management (work in
progress), February 2014.
[OAuth.SAML2]
Campbell, B., Mortimore, C., and M. Jones, "SAML 2.0
Profile for OAuth 2.0 Client Authentication and
Authorization Grants", draft-ietf-oauth-saml2-bearer (work
in progress), December 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
RFC 2246, January 1999.
[RFC4627] Crockford, D., "The application/json Media Type for
JavaScript Object Notation (JSON)", RFC 4627, July 2006.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC6125] Saint-Andre, P. and J. Hodges, "Representation and
Verification of Domain-Based Application Service Identity
within Internet Public Key Infrastructure Using X.509
(PKIX) Certificates in the Context of Transport Layer
Security (TLS)", RFC 6125, March 2011.
[RFC6749] Hardt, D., "The OAuth 2.0 Authorization Framework",
RFC 6749, October 2012.
[RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
Framework: Bearer Token Usage", RFC 6750, October 2012.
8.2. Informative References
[OAuth.Registration.Metadata]
Richer, J., Jones, M., Bradley, J., Machulak, M., and P.
Hunt, "OAuth 2.0 Dynamic Client Registration Metadata",
draft-ietf-oauth-dyn-reg-metadata (work in progress),
February 2014.
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Appendix A. Use Cases
This appendix describes different ways that this specification can be
utilized, including describing some of the choices that may need to
be made. Some of the choices are independent and can be used in
combination, whereas some of the choices are interrelated.
A.1. Open versus Protected Dynamic Client Registration
A.1.1. Open Dynamic Client Registration
Authorization servers that support open registration allow
registrations to be made with no initial access token. This allows
all client software to register with the authorization server.
A.1.2. Protected Dynamic Client Registration
Authorization servers that support protected registration require
that an initial access token be used when making registration
requests. While the method by which a client or developer receives
this initial access token and the method by which the authorization
server validates this initial access token are out of scope for this
specification, a common approach is for the developer to use a manual
pre-registration portal at the authorization server that issues an
initial access token to the developer.
A.2. Registration Without or With Software Statements
A.2.1. Registration Without a Software Statement
When a software statement is not used in the registration request,
the authorization server must be willing to use client metadata
values without them being signed (and thereby attested to) by any
authority. (Note that this choice is independent of the Open versus
Protected choice, and that an initial access token is another
possible form of attestation.)
A.2.2. Registration With a Software Statement
A software statement can be used in a registration request to provide
attestation for a set of client metadata values for a piece of client
software by an authority. This can be useful when the authorization
server wants to restrict registration to client software attested to
by a set of authorities or when it wants to know that multiple
registration requests refer to the same piece of client software.
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A.3. Registration by the Client or the Developer
A.3.1. Registration by the Client
In some use cases, client software will dynamically register itself
with an authorization server to obtain a Client ID and other
information needed to interact with the authorization server. In
this case, no Client ID for the authorization server is packaged with
the client software.
A.3.2. Registration by the Developer
In some cases, the developer (or development software being used by
the developer) will pre-register the client software with the
authorization server or a set of authorization servers. In this
case, the Client ID value(s) for the authorization server(s) can be
packaged with the client software.
A.4. Client ID per Client Instance or per Client Software
A.4.1. Client ID per Client Software Instance
In some cases, each deployed instance of a piece of client software
will dynamically register and obtain distinct Client ID values. This
can be advantageous, for instance, if the code flow is being used, as
it also enables each client instance to have its own client secret.
This can be useful for native clients, which cannot maintain the
secrecy of a client secret value packaged with the software, but
which may be able to maintain the secrecy of a per-instance client
secret.
A.4.2. Client ID Shared between all Instances of Client Software
In some cases, each deployed instance of a piece of client software
will share a common Client ID value. For instance, this is often the
case for native client using implicit flow, when no client secret is
involved. Particular authorization servers might choose, for
instance, to maintain a mapping between software statement values and
Client ID values, and return the same Client ID value for all
registration requests for a particular piece of software. The
circumstances under which an authorization server would do so, and
the specific software statement characteristics required in this
case, are beyond the scope of this specification.
A.5. Stateful or Stateless Registration
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A.5.1. Stateful Client Registration
In some cases, authorization servers will maintain state about
registered clients, typically indexing this state using the Client ID
value. This state would typically include the client metadata values
associated with the client registration, and possibly other state
specific to the authorization server's implementation. When stateful
registration is used, operations to support retrieving and/or
updating this state may be supported, as described in the
[OAuth.Registration.Management] specification.
A.5.2. Stateless Client Registration
In some cases, authorization servers will be implemented in a manner
the enables them to not maintain any local state about registered
clients. One means of doing this is to encode all the registration
state in the returned Client ID value, and possibly encrypting the
state to the authorization server to maintain the confidentiality and
integrity of the state.
Appendix B. Acknowledgments
The authors thank the OAuth Working Group, the User-Managed Access
Working Group, and the OpenID Connect Working Group participants for
their input to this document. In particular, the following
individuals have been instrumental in their review and contribution
to various versions of this document: Amanda Anganes, Derek Atkins,
Tim Bray, Domenico Catalano, Donald Coffin, Vladimir Dzhuvinov,
George Fletcher, Thomas Hardjono, Phil Hunt, William Kim, Torsten
Lodderstedt, Eve Maler, Josh Mandel, Nov Matake, Tony Nadalin, Nat
Sakimura, Christian Scholz, and Hannes Tschofenig.
Appendix C. Document History
[[ to be removed by the RFC editor before publication as an RFC ]]
-16
o Replaced references to draft-jones-oauth-dyn-reg-metadata and
draft-jones-oauth-dyn-reg-management with
draft-ietf-oauth-dyn-reg-metadata and
draft-ietf-oauth-dyn-reg-management.
o Addressed review comments by Phil Hunt and Tony Nadalin.
-15
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o Partitioned the Dynamic Client Registration specification into
core, metadata, and management specifications. This built on work
first published as draft-richer-oauth-dyn-reg-core-00 and
draft-richer-oauth-dyn-reg-management-00.
o Added the ability to use Software Statements. This built on work
first published as draft-hunt-oauth-software-statement-00 and
draft-hunt-oauth-client-association-00.
o Created the IANA OAuth Registration Client Metadata registry for
registering Client Metadata values.
o Defined Client Instance term and stated that multiple instances
can use the same Client ID value under certain circumstances.
o Rewrote the introduction.
o Rewrote the Use Cases appendix.
-14
o Added software_id and software_version metadata fields
o Added direct references to RFC6750 errors in read/update/delete
methods
-13
o Fixed broken example text in registration request and in delete
request
o Added security discussion of separating clients of different grant
types
o Fixed error reference to point to RFC6750 instead of RFC6749
o Clarified that servers must respond to all requests to
configuration endpoint, even if it's just an error code
o Lowercased all Terms to conform to style used in RFC6750
-12
o Improved definition of Initial Access Token
o Changed developer registration scenario to have the Initial Access
Token gotten through a normal OAuth 2.0 flow
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o Moved non-normative client lifecycle examples to appendix
o Marked differentiating between auth servers as out of scope
o Added protocol flow diagram
o Added credential rotation discussion
o Called out Client Registration Endpoint as an OAuth 2.0 Protected
Resource
o Cleaned up several pieces of text
-11
o Added localized text to registration request and response
examples.
o Removed "client_secret_jwt" and "private_key_jwt".
o Clarified "tos_uri" and "policy_uri" definitions.
o Added the OAuth Token Endpoint Authentication Methods registry for
registering "token_endpoint_auth_method" metadata values.
o Removed uses of non-ASCII characters, per RFC formatting rules.
o Changed "expires_at" to "client_secret_expires_at" and "issued_at"
to "client_id_issued_at" for greater clarity.
o Added explanatory text for different credentials (Initial Access
Token, Registration Access Token, Client Credentials) and what
they're used for.
o Added Client Lifecycle discussion and examples.
o Defined Initial Access Token in Terminology section.
-10
o Added language to point out that scope values are service-specific
o Clarified normative language around client metadata
o Added extensibility to token_endpoint_auth_method using absolute
URIs
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o Added security consideration about registering redirect URIs
o Changed erroneous 403 responses to 401's with notes about token
handling
o Added example for initial registration credential
-09
o Added method of internationalization for Client Metadata values
o Fixed SAML reference
-08
o Collapsed jwk_uri, jwk_encryption_uri, x509_uri, and
x509_encryption_uri into a single jwks_uri parameter
o Renamed grant_type to grant_types since it's a plural value
o Formalized name of "OAuth 2.0" throughout document
o Added JWT Bearer Assertion and SAML 2 Bearer Assertion to example
grant types
o Added response_types parameter and explanatory text on its use
with and relationship to grant_types
-07
o Changed registration_access_url to registration_client_uri
o Fixed missing text in 5.1
o Added Pragma: no-cache to examples
o Changed "no such client" error to 403
o Renamed Client Registration Access Endpoint to Client
Configuration Endpoint
o Changed all the parameter names containing "_url" to instead use
"_uri"
o Updated example text for forming Client Configuration Endpoint URL
-06
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o Removed secret_rotation as a client-initiated action, including
removing client secret rotation endpoint and parameters.
o Changed _links structure to single value registration_access_url.
o Collapsed create/update/read responses into client info response.
o Changed return code of create action to 201.
o Added section to describe suggested generation and composition of
Client Registration Access URL.
o Added clarifying text to PUT and POST requests to specify JSON in
the body.
o Added Editor's Note to DELETE operation about its inclusion.
o Added Editor's Note to registration_access_url about alternate
syntax proposals.
-05
o changed redirect_uri and contact to lists instead of space
delimited strings
o removed operation parameter
o added _links structure
o made client update management more RESTful
o split endpoint into three parts
o changed input to JSON from form-encoded
o added READ and DELETE operations
o removed Requirements section
o changed token_endpoint_auth_type back to
token_endpoint_auth_method to match OIDC who changed to match us
-04
o removed default_acr, too undefined in the general OAuth2 case
o removed default_max_auth_age, since there's no mechanism for
supplying a non-default max_auth_age in OAuth2
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o clarified signing and encryption URLs
o changed token_endpoint_auth_method to token_endpoint_auth_type to
match OIDC
-03
o added scope and grant_type claims
o fixed various typos and changed wording for better clarity
o endpoint now returns the full set of client information
o operations on client_update allow for three actions on metadata:
leave existing value, clear existing value, replace existing value
with new value
-02
o Reorganized contributors and references
o Moved OAuth references to RFC
o Reorganized model/protocol sections for clarity
o Changed terminology to "client register" instead of "client
associate"
o Specified that client_id must match across all subsequent requests
o Fixed RFC2XML formatting, especially on lists
-01
o Merged UMA and OpenID Connect registrations into a single document
o Changed to form-parameter inputs to endpoint
o Removed pull-based registration
-00
o Imported original UMA draft specification
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Authors' Addresses
Justin Richer
The MITRE Corporation
Email: jricher@mitre.org
Michael B. Jones
Microsoft
Email: mbj@microsoft.com
URI: http://self-issued.info/
John Bradley
Ping Identity
Email: ve7jtb@ve7jtb.com
Maciej Machulak
Newcastle University
Email: m.p.machulak@ncl.ac.uk
URI: http://ncl.ac.uk/
Phil Hunt
Oracle Corporation
Email: phil.hunt@yahoo.com
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