Network Working Group J. Richer, Ed.
Internet-Draft The MITRE Corporation
Intended status: Standards Track J. Bradley
Expires: July 11, 2013 Ping Identity
M. Jones
Microsoft
M. Machulak
Newcastle University
January 7, 2013
OAuth Dynamic Client Registration Protocol
draft-ietf-oauth-dyn-reg-04
Abstract
This specification defines an endpoint and protocol for dynamic
registration of OAuth Clients at an Authorization Server.
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 July 11, 2013.
Copyright Notice
Copyright (c) 2013 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
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Notational Conventions . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
1.3. Requirements . . . . . . . . . . . . . . . . . . . . . . . 4
1.3.1. The client needs to be uniquely identifiable by
the authorization server . . . . . . . . . . . . . . . 4
1.3.2. The authorization server must collect metadata
about a client for later user interaction . . . . . . 4
1.3.3. The authorization server should have the option of
strongly authenticating the client and its metadata . 4
1.3.4. Dynamic client registration must be possible from
both web-server applications and applications with
other capabilities and limitations, such as native
applications . . . . . . . . . . . . . . . . . . . . . 4
1.3.5. Transaction integrity must be ensured . . . . . . . . 5
2. Client Metadata . . . . . . . . . . . . . . . . . . . . . . . 5
3. Client Registration Endpoint . . . . . . . . . . . . . . . . . 8
3.1. Client Registration Request . . . . . . . . . . . . . . . 9
3.2. Client Registration Response . . . . . . . . . . . . . . . 10
3.3. Client Update Request . . . . . . . . . . . . . . . . . . 11
3.4. Client Update Response . . . . . . . . . . . . . . . . . . 13
3.5. Rotate Secret Request . . . . . . . . . . . . . . . . . . 13
3.6. Rotate Secret Response . . . . . . . . . . . . . . . . . . 14
3.7. Client Registration Error Response . . . . . . . . . . . . 15
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
5. Security Considerations . . . . . . . . . . . . . . . . . . . 16
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17
7. Document History . . . . . . . . . . . . . . . . . . . . . . . 17
8. Normative References . . . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19
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1. Introduction
In some use-case scenarios, it is desirable or necessary to allow
OAuth clients to obtain authorization from an OAuth authorization
server without requiring the two parties to interact before hand.
Nevertheless, in order for the authorization server to accurately and
securely represent to end-users which client is seeking authorization
to access the end-user's resources, a method for automatic and unique
registration of clients is needed. The OAuth2 authorization
framework does not define how the relationship between the Client and
the Authorization Server is initialized, or how a given client is
assigned a unique Client Identifier. Historically, this has happened
out-of-band from the OAuth protocol. This draft provides a mechanism
for a client to register itself with the Authorization Server, which
can be used to dynamically provision a Client Identifier, and
optionally a Client Secret.
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 display name and icon to be presented to
the user during the authorization step. This draft provides a method
for the client to register and update this information over time.
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",
and "Token Endpoint" defined by OAuth 2.0 [RFC6749].
This specification defines the following additional terms:
o Client Registration Endpoint: The OAuth 2.0 Endpoint through which
a Client can request new registration and manage the metadata
associated with it.
o Registration Access Token: An OAuth 2.0 Bearer Token issued by the
Authorization Server through the Client Registration Endpoint
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which is used by the Client to authenticate itself during update
and secret rotation operations.
1.3. Requirements
[[ Following are proposed requirements for dynamic client
registration. This section is intended for discussion and will
likely be removed in the final draft. ]]
1.3.1. The client needs to be uniquely identifiable by the
authorization server
In order for an authorization server to do proper user-delegated
authorization and prevent unauthorized access it must be able to
identify clients uniquely. As is done today in OAuth, the client
identifier (and optional secret) should thus be issued by the
authorization server and not simply accepted as proposed by the
client.
1.3.2. The authorization server must collect metadata about a client
for later user interaction
In order for the authorization server to describe a client to an end-
user in an authorization step it needs information about the client.
This can be the client name at a minimum, but today servers usually
request at least a description, a homepage URL, and an icon when
doing manual registration.
1.3.3. The authorization server should have the option of strongly
authenticating the client and its metadata
In order to prevent spoofing of clients and enable dynamic building
of strong trust relationships, the authorization server should have
the option to verify the provided information. This might be solved
using message signature verification.
1.3.4. Dynamic client registration must be possible from both web-
server applications and applications with other capabilities and
limitations, such as native applications
Each instance of a native application (that is, the specific instance
running on each device) that is installed and run by the same user
may need the option of getting a unique client identifier. In this
case, there are implications around gathering and displaying enough
information to ensure that the end-user is delegating authorization
to the intended application. The registration protocol should be
simple and flexible enough to allow for multiple types of
applications.
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1.3.5. Transaction integrity must be ensured
When a client sends information to a server endpoint, it might take
time for this data to propagate through big server installations that
spread across various data centers. Care needs to be taken that
subsequent interactions with the user after the registration process,
such as an authorization request, show the correct data.
2. Client Metadata
Clients generally have an array of metadata associated with their
unique Client Identifier at the Authorization Server. These can
range from human-facing display strings, such as a client name, to
items that impact the security of the protocol, such as the list of
valid redirect URIs.
Extensions and profiles of this specification MAY expand this list,
but MUST at least accept all parameters on this list. The
Authorization Server MUST ignore any additional parameters sent by
the Client that it does not understand.
redirect_uris
RECOMMENDED. A space-delimited list of redirect URIs for use in
the Authorization Code and Implicit grant types. An Authorization
Server SHOULD require registration of valid redirect URIs for all
clients to protect against token and credential theft attacks.
client_name
RECOMMENDED. Human-readable name of the Client to be presented to
the user. If omitted, the Authorization Server MAY display to the
user the raw client_id value instead.
client_url
RECOMMENDED. URL of the homepage of the Client. If present, the
server SHOULD display this URL to the end user in a clickable
fashion.
logo_url
OPTIONAL. URL that references a logo for the Client application.
If present, the server SHOULD display this image to the end user
during approval.
contacts
OPTIONAL. Space delimited list of email addresses for people
responsible for this client. The Authorization Server MAY may
these addresses available to end users for support queries. An
Authorization Server MAY use these email addresses as identifiers
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for an administrative page for this client.
tos_url
OPTIONAL. URL that points to a human-readable Terms of Service
for the Client. The Authorization Server SHOULD display this URL
to the End-User if it is given.
token_endpoint_auth_type
OPTIONAL. The requested authentication type for the Token
Endpoint. Valid values are:
* "none": this 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 OAuth2.0 section 2.3.1
* "client_secret_basic": the client uses HTTP Basic defined in
OAuth 2.0 section 2.3.1
* "client_secret_jwt": the client uses the JWT Assertion profile
with a symmetric secret issued by the server
* "private_key_jwt": the client uses the JWT Assertion profile
with its own private key
Other Authentication methods may be defined by extension. 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.
scope
OPTIONAL. Space separated list of scopes that the client will be
allowed to request tokens for. If omitted, an Authorization
Server MAY register a Client with a default set of allowed scopes.
grant_type
OPTIONAL. Space separated list of grant types that a client may
use. These grant types are defined as follows:
* "authorization_code": The Authorization Code Grant described in
OAuth2 Section 4.1.
* "implicit": The Implicit Grant described in OAuth2 Section 4.2.
* "password": The Resource Owner Password Credentials Grant
described in OAuth2 Section 4.3
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* "client_credentials": The Client Credentials Grant described in
OAuth2 Section 4.4
* "refresh_token": The Refresh Token Grant described in OAuth2
Section 6.
Authorization Servers MAY allow for other values as defined in
grant type extensions to OAuth2. The extension process is
described in OAuth2 Section 2.5, and the value of this parameter
MUST be the same as the value of the grant_type parameter defined
in the extension.
policy_url
OPTIONAL. A URL location that the Client provides to the End-User
to read about the how the profile data will be used. The
Authorization Server SHOULD display this URL to the End-User if it
is given.
jwk_url
OPTIONAL. URL for the Client's JSON Web Key [JWK] document that
is used for signing requests, such as requests to the Token
Endpoint using the "private_key_jwt" assertion client credential.
If the Client registers both "x509_url" and "jwk_url", the keys
contained in both formats MUST be the same.
jwk_encryption_url
OPTIONAL. URL for the Client's JSON Web Key [JWK] that the server
can use to encrypt responses to the Client. If the Client
registers both "jwk_encryption_url" and "x509_encryption_url", the
keys contained in both formats MUST be the same.
x509_url
OPTIONAL. URL for the Client's PEM encoded X.509 Certificate or
Certificate chain that is used for signing requests, such as
requests to the Token Endpoint using the "private_key_jwt"
assertion client credential. If the Client registers both
"x509_url" and "jwk_url", the keys contained in both formats MUST
be the same.
x509_encryption_url
OPTIONAL. URL for the Client's PEM encoded X.509 Certificate or
Certificate chain that the server can use to encrypt responses to
the Client. If the Client registers both "jwk_encryption_url" and
"x509_encryption_url", the keys contained in both formats SHOULD
be the same.
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3. 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 register itself
with the Authorization Server. The Client Registration Endpoint MUST
accept HTTP POST messages with request parameters encoded in the
entity body using the "application/x-www-form-urlencoded" 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].
The Endpoint defines three operations that a client can take on it,
switched by the "operation" parameter:
o "client_register": request that the Authorization Server generate
a new Client Identifier (and optionally a Client Secret) and
associate it with the set of presented metadata (Section 2)
o "client_update": update the metadata (Section 2) associated with a
Client Identifier
o "rotate_secret": requst a new Registration Access Token and, if
applicable, a Client Secret for a Client
The Client Registration Endpoint MAY accept an initial authorization
credential in the form of an OAuth 2.0 [RFC6749] access token in
order to limit registration to only previously authorized parties.
The method by which this access token is obtained by the registrant
is generally out-of-band and is out of scope of this specification.
In order to support open registration and facilitate wider
interoperability, the Client Registration Endpoint SHOULD allow
initial "client_register" requests with no authentication. These
requests MAY be rate-limited or otherwise limited to prevent a
denial-of-service attack on the Client Registration Endpoint.
In order to facilitate registered clients updating their information,
the Client Registration Endpoint issues a Request Access Token for
clients to securely identify themselves in future connections. As
such, the Endpoint MUST accept requests with OAuth 2.0 Bearer Tokens
[RFC6750] for these operations, whether or not the initial
"client_register" call requires authentication of some form.
These two aspects, operation selection and client authentication, are
represented by two parameters common to all operations:
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operation
REQUIRED. Valid values are "client_register", "rotate_secret",
and "client_update", as described above.
access_token
OPTIONAL. An OAuth2 Bearer token used to access the Client
Registration Endpoint, as defined in OAuth2 Bearer [RFC6750].
This parameter MUST NOT be sent if the Access Token is sent in the
HTTP Authorization header as described in Section 7.1 of OAuth 2.0
[RFC6749]. Access Tokens sent in the authorization header must be
OAuth 2.0 Bearer Tokens [RFC6750].
Each operation takes a different parameter set, and all operations
are described below.
The Client Registration Endpoint MUST ignore all parameters it does
not understand.
3.1. 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 the two parameters described above as well as any
parameters described in Client Metadata (Section 2). The
Authorization Server MAY provision default values for any items
omitted in the Client Metadata.
operation
REQUIRED. MUST have the value "client_register"
access_token
OPTIONAL. OAuth2 Access token used to restrict new client
registration. This parameter MUST NOT be sent if the Access Token
is sent in the HTTP Authorization header as described in Section
7.1 of OAuth 2.0 [RFC6749]. Access Tokens sent in the
authorization header must be OAuth 2.0 Bearer Tokens [RFC6750].
redirect_uris RECOMMENDED
client_name RECOMMENDED
client_url RECOMMENDED
logo_url OPTIONAL
contacts OPTIONAL
tos_url OPTIONAL
token_endpoint_auth_type OPTIONAL
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policy_url OPTIONAL
scope OPTIONAL
grant_type OPTIONAL
jwk_url OPTIONAL
jwk_encryption_url OPTIONAL
x509_url OPTIONAL
x509_encryption_url OPTIONAL
For example, a client could send the following registration request
to the Client Registration Endpoint:
Following is a non-normative example request (with line wraps for
display purposes only):
POST /register HTTP/1.1
Accept: application/x-www-form-urlencoded
Host: server.example.com
operation=client_register
&redirect_uris=https://client.example.org/callback
%20https://client.example.org/callback2
&client_name=My%20Example%20Client
&token_endpoint_auth_type=client_secret_basic%20client_secret_post
&scope=read%20write%20dolphin
&logo_url=https://client.example.org/logo.png
&jwk_url=https://client.example.org/my_rsa_public_key.jwk
3.2. Client Registration Response
Upon successful registration, the Client Registration Endpoint
returns the newly-created Client Identifier and, if applicable, a
Client Secret, along with all registered metadata (Section 2) 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 field values and substitute them with suitable
values. If this happens, the Authorization Server MUST include these
fields in the response to the client.
The response also contains a Registration Access Token that is to be
used by the client to perform subsequent operations at this endpoint,
such as "client_update" and "rotate_secret".
All of the response items are returned as a JSON document [RFC4627]
with the following fields as top-level members of the root JSON
object.
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client_id
REQUIRED. The unique Client identifier, MUST NOT be currently
valid for any other registered Client.
client_secret
OPTIONAL. The Client secret. 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
Section 2.3.1.
registration_access_token
REQUIRED. The Access token to be used by the client to perform
"client_update" and "rotate_secret" requests.
issued_at
OPTIONAL. Specifies the timestamp when the Client Identifier was
issued. The timestamp value MUST be a positive integer. The
value is expressed in the number of seconds since January 1, 1970
00:00:00 GMT.
expires_at
OPTIONAL. The number of seconds from 1970-01-01T0:0:0Z as
measured in UTC that the "client_secret" will expire or "0" if
they do not expire. See RFC 3339 [RFC3339] for details regarding
date/times in general and UTC in particular.
Following is a non-normative example response:
HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store
{
"client_id":"s6BhdRkqt3",
"client_secret": "cf136dc3c1fc93f31185e5885805d",
"scope": "read write dolphin",
"grant_type": "authorization_code refresh_token",
"token_endpoint_auth_type": "client_secret_basic client_secret_post",
"logo_url": "https://client.example.org/logo.png",
"jwk_url": "https://client.example.org/my_rsa_public_key.jwk",
"registration_access_token": "reg-23410913-abewfq.123483",
"expires_at":2893276800
}
3.3. Client Update Request
This operation updates a previously-registered client with new
metadata at the Authorization Server. This request MUST be protected
by the Registration Authorization Token associated with the Client.
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This request MAY include any fields described in Client Metadata
(Section 2). If included in the request, valid values of Client
Metadata fields in this request MUST replace, not augment, the values
previously associated with this Client. Empty values in Client
Metadata MUST be taken as a request to clear any existing value of
that field. Omitted values in the Client Metadata MUST remain
unchanged by the Authorization Server. The Authorization Server MAY
replace any invalid values with suitable values.
operation
REQUIRED, MUST have the value "client_update"
access_token
REQUIRED, unless presented in the Authorization Header as in
OAuth2 Bearer [RFC6750]. The Registration Access Token that was
issued during the "client_register" step, or previous
"client_update" or "rotate_secret" calls.
redirect_uris RECOMMENDED
client_name RECOMMENDED
client_url RECOMMENDED
logo_url OPTIONAL
contacts OPTIONAL
tos_url OPTIONAL
token_endpoint_auth_type OPTIONAL
policy_url OPTIONAL
jwk_url OPTIONAL
jwk_encryption_url OPTIONAL
x509_url OPTIONAL
x509_encryption_url OPTIONAL
For example, a client could send the following request to the Client
Registration Endpoint to update the client registration in the above
example:
Following is a non-normative example request (with line wraps for
display purposes only):
POST /register HTTP/1.1
Accept: application/x-www-form-urlencoded
Host: server.example.com
Authorization: Bearer reg-23410913-abewfq.123483
operation=client_update
&redirect_uri=https://client.example.org/callback
%20https://client.example.org/alt
&client_name=My%20New%20Example%20
&logo_url=https://client.example.org/newlogo.png
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3.4. Client Update Response
Upon successful update, the Client Registration Endpoint returns the
Client ID, along with all current registered metadata (Section 2)
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 field values and substitute
them suitable values. If this happens, the Authorization Server MUST
include these fields in the response to the client.
The Authorization Server MUST NOT include the Client Secret or
Request Access Token in this response.
These fields are returned in a JSON Document [RFC4627] as top-level
members of the root JSON object.
client_id
REQUIRED. The unique Client identifier, MUST equal the value of
the client_id returned in the original client_register request.
Following is a non-normative example response:
HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store
{
"client_id": "s6BhdRkqt3",
"client_name": "My New Example",
"redirect_uri":
"https://client.example.org/callback https://client.example.org/alt"
"scope": "read write dolphin",
"grant_type": "authorization_code refresh_token",
"token_endpoint_auth_type": "client_secret_basic client_secret_post",
"logo_url": "https://client.example.org/newlogo.png",
"jwk_url": "https://client.example.org/my_rsa_public_key.jwk",
}
3.5. Rotate Secret Request
This operation allows the client to rotate its current Registration
Access Token as well as its Client Secret, if it has one.
operation
REQUIRED. MUST have the value rotate_secret
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access_token
REQUIRED, unless presented in the Authorization Header as in
OAuth2 Bearer [RFC6750]. The Registration Access Token that was
issued during the "client_register" step, or previous
"client_update" or "rotate_secret" calls.
Following is a non-normative example request (with line wraps for
display purposes only):
POST /register HTTP/1.1
Accept: application/x-www-form-urlencoded
Host: server.example.com
Authorization: Bearer reg-23410913-abewfq.123483
operation=rotate_secret
3.6. Rotate Secret Response
Upon successful rotation of the Registration Access Token, and
optionally the Client Secret, the Client Registration Endpoint
returns a JSON document [RFC4627] with the following fields as top-
level members of the root JSON object. This response MUST NOT
include any other client metadata.
client_id
REQUIRED. The unique Client identifier, MUST match the client_id
issued in the original client_register request.
client_secret
REQUIRED if the server initially issued this Client a Client
Secret, otherwise the server MUST NOT return a value. The value
MUST be unique for each "client_id".
registration_access_token
REQUIRED The Access token to be used by the client to perform
subsequent "client_update" and "rotate_secret" requests.
issued_at
OPTIONAL. Specifies the timestamp when the identifier was issued.
The timestamp value MUST be a positive integer. The value is
expressed in the number of seconds since January 1, 1970 00:00:00
GMT.
expires_at
OPTIONAL. The number of seconds from 1970-01-01T0:0:0Z as
measured in UTC that the "client_secret" will expire or "0" if
they do not expire. See RFC 3339 [RFC3339] for details regarding
date/times in general and UTC in particular.
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Following is a non-normative example response:
HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store
{
"client_id":"s6BhdRkqt3",
"client_secret": "7fce6c93f31185e5885805d",
"registration_access_token": "reg-02348913-oieqer.983421",
"expires_at":2893276800
}
The Authorization Server SHOULD discard and invalidate the Request
Access Token and the Client Secret associated with this Client after
successful completion of this request.
3.7. Client Registration Error Response
When an OAuth error condition occurs, the Client Registration
Endpoint returns an Error Response as defined in Section 5.2 of the
OAuth 2.0 specification.
When a registration error condition occurs, the Client Registration
Endpoint returns a HTTP 400 status code including a JSON object
[RFC4627] describing the error in the response body.
The JSON object contains two members:
error
The error code, a single ASCII string.
error_description
The additional text description of the error for debugging.
This specification defines the following error codes:
invalid_operation
The value of "operation" is invalid or not supported.
invalid_redirect_uri
The value of one or more "redirect_uris" is invalid.
invalid_client_metadata
The value of one of the client metadata (Section 2) 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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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
{
"error":"invalid_operation",
"error_description":"The value of the operation parameter must
be one of client_register, rotate_secret or client_update."
}
4. IANA Considerations
This document makes no requests of IANA.
5. Security Considerations
[[ Editor's note: Following are some security considerations taken
from the UMA and OpenID Connect source drafts. These need to be
massaged into a properly generic set of considerations. ]]
Since requests to the Client Registration Endpoint result in the
transmission of clear-text credentials (in the HTTP request and
response), the 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].
As this endpoint is an OAuth2 Protected Resource, requests to the
Registration Endpoint SHOULD have some rate limiting on failures to
prevent the Registration Access Token from being disclosed though
repeated access attempts.
The authorization server MUST treat all client metadata as self-
asserted. A rogue Client might use the name and logo for the
legitimate Client, which it is trying to impersonate. An
Authorization Server needs to take steps to mitigate this phishing
risk, since the logo could confuse users into thinking they're
logging in to the legitimate Client. For instance, an Authorization
Server could warn if the domain/site of the logo doesn't match the
domain/site of redirect URIs. An Authorization Server can also
present warning messages to end users about untrusted Clients in all
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cases, especially if such clients have been dynamically registered
and have not been trusted by any users at the Authorization Server
before.
In a situation where the Authorization Server is supporting open
Client registration, it must be extremely careful with any URL
provided by the Client that will be displayed to the user (e.g.
"logo_url" and "policy_url"). A rogue Client could specify a
registration request with a reference to a drive-by download in the
"policy_url". The Authorization Server should check to see if the
"logo_url" and "policy_url" have the same host as the hosts defined
in the array of "redirect_uris".
While the Client Secret can expire, the Registration Access Token
should not expire while a client is still actively registered. If
this token were to expire, a Client could be left in a situation
where it has no means of updating itself and must register itself
anew. As the Registration Access Tokens are long-term credentials,
they MUST be protected by the Client as a secret. [[ Editor's note:
with the right error codes returned from client_update, the AS could
force the Client to call rotate_secret before going forward,
lessening the window for abuse of a leaked registration token. ]]
6. 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: Torsten Lodderstedt, Eve Maler,
Thomas Hardjono, Christian Scholz, Nat Sakimura, George Fletcher,
Amanda Anganes, and Domenico Catalano.
7. Document History
[[ to be removed by RFC editor before publication as an RFC ]]
- 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
o clarified signing and encryption URLs
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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-paramter inputs to endpoint
o Removed pull-based registration
- 00
o Imported original UMA draft specification
8. Normative References
[JWK] Jones, M., "JSON Web Key (JWK)", May 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
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Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
RFC 2246, January 1999.
[RFC3339] Klyne, G., Ed. and C. Newman, "Date and Time on the
Internet: Timestamps", RFC 3339, July 2002.
[RFC4627] Crockford, D., "The application/json Media Type for
JavaScript Object Notation (JSON)", RFC 4627, July 2006.
[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.
Authors' Addresses
Justin Richer (editor)
The MITRE Corporation
Phone:
Fax:
Email: jricher@mitre.org
URI:
John Bradley
Ping Identity
Email: ve7jtb@ve7jtb.com
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Michael B. Jones
Microsoft
Email: mbj@microsoft.com
Maciej Machulak
Newcastle University
Email: m.p.machulak@ncl.ac.uk
URI: http://ncl.ac.uk/
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