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Versions: (draft-denniss-oauth-device-flow)
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OAuth W. Denniss
Internet-Draft Google
Intended status: Standards Track S. Myrseth
Expires: January 19, 2017 ForgeRock
J. Bradley
Ping Identity
M. Jones
Microsoft
H. Tschofenig
ARM Limited
July 18, 2016
OAuth 2.0 Device Flow
draft-ietf-oauth-device-flow-03
Abstract
The device flow is suitable for OAuth 2.0 clients executing on
devices that do not have an easy data-entry method (e.g., game
consoles, TVs, picture frames, and media hubs), but where the end-
user has separate access to a user-agent on another computer or
device (e.g., desktop computer, a laptop, a smart phone, or a
tablet).
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 January 19, 2017.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Specification . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Device Authorization Request . . . . . . . . . . . . . . 4
3.2. Device Authorization Response . . . . . . . . . . . . . . 5
3.3. User Instruction . . . . . . . . . . . . . . . . . . . . 6
3.4. Device Token Request . . . . . . . . . . . . . . . . . . 6
3.5. Device Token Response . . . . . . . . . . . . . . . . . . 7
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
4.1. OAuth URI Registration . . . . . . . . . . . . . . . . . 8
4.1.1. Registry Contents . . . . . . . . . . . . . . . . . . 8
4.2. OAuth Extensions Error Registration . . . . . . . . . . . 8
4.2.1. Registry Contents . . . . . . . . . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 9
6. Normative References . . . . . . . . . . . . . . . . . . . . 9
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 9
Appendix B. Document History . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
The device flow is suitable for clients executing on devices that do
not have an easy data-entry method and where the client is incapable
of receiving incoming requests from the authorization server
(incapable of acting as an HTTP server).
Instead of interacting with the end-user's user-agent, the client
instructs the end-user to use another computer or device and connect
to the authorization server to approve the access request. Since the
client cannot receive incoming requests, it polls the authorization
server repeatedly until the end-user completes the approval process.
Note that this device flow does not utilize the client secret.
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+----------+ +----------------+
| |>---(A)-- Client Identifier --->| |
| | | |
| |<---(B)-- Verification Code, --<| |
| | User Code, | |
| | & Verification URI | |
| Device | | |
| Client | Client Identifier & | |
| |>---(E)-- Verification Code --->| |
| | polling... | |
| |>---(E)-- Verification Code --->| |
| | | Authorization |
| |<---(F)-- Access Token --------<| Server |
+----------+ (w/ Optional Refresh Token) | |
v | |
: | |
(C) User Code & Verification URI | |
: | |
v | |
+----------+ | |
| End-user | | |
| at |<---(D)-- User authenticates -->| |
| Browser | | |
+----------+ +----------------+
Figure 1: Device Flow.
The device flow illustrated in Figure 1 includes the following steps:
(A) The client requests access from the authorization server and
includes its client identifier in the request.
(B) The authorization server issues a verification code, an end-
user code, and provides the end-user verification URI.
(C) The client instructs the end-user to use its user-agent
(elsewhere) and visit the provided end-user verification URI. The
client provides the end-user with the end-user code to enter in
order to grant access.
(D) The authorization server authenticates the end-user (via the
user-agent) and prompts the end-user to grant the client's access
request. If the end-user agrees to the client's access request,
the end-user enters the end-user code provided by the client. The
authorization server validates the end-user code provided by the
end-user.
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(E) While the end-user authorizes (or denies) the client's request
(D), the client repeatedly polls the authorization server to find
out if the end-user completed the end-user authorization step.
The client includes the verification code and its client
identifier.
(F) Assuming the end-user granted access, the authorization server
validates the verification code provided by the client and
responds back with the access token.
2. Terminology
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].
Device Endpoint:
The authorization server's endpoint capable of issuing
verification codes, user codes, and verification URLs.
Device Verification Code:
A short-lived token representing an authorization session.
End-User Verification Code:
A short-lived token which the device displays to the end user, is
entered by the end-user on the authorization server, and is thus
used to bind the device to the end-user.
3. Specification
3.1. Device Authorization Request
The client initiates the flow by requesting a set of verification
codes from the authorization server by making an HTTP "POST" request
to the device endpoint. The client constructs a request URI by
adding the following parameters to the request:
response_type:
REQUIRED. The parameter value MUST be set to "device_code".
client_id:
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REQUIRED. The client identifier as described in Section 2.2 of
[RFC6749].
scope:
OPTIONAL. The scope of the access request as described by
Section 3.3 of [RFC6749].
For example, the client makes the following HTTPS request (line
breaks are for display purposes only):
POST /token HTTP/1.1
Host: server.example.com
Content-Type: application/x-www-form-urlencoded
response_type=device_code&client_id=s6BhdRkqt3
3.2. Device Authorization Response
In response, the authorization server generates a verification code
and an end-user code and includes them in the HTTP response body
using the "application/json" format with a 200 status code (OK). The
response contains the following parameters:
device_code
REQUIRED. The verification code.
user_code
REQUIRED. The end-user verification code.
verification_uri
REQUIRED. The end-user verification URI on the authorization
server. The URI should be short and easy to remember as end-
users will be asked to manually type it into their user-agent.
expires_in
OPTIONAL. The duration in seconds of the verification code
lifetime.
interval
OPTIONAL. The minimum amount of time in seconds that the client
SHOULD wait between polling requests to the token endpoint.
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For example:
HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store
{
"device_code":"74tq5miHKB",
"user_code":"94248",
"verification_uri":"http://www.example.com/device",
"interval"=5
}
3.3. User Instruction
After receiving a successful Authorization Response, the client
displays the end-user code and the end-user verification URI to the
end-user, and instructs the end-user to visit the URI using a user-
agent and enter the end-user code.
The end-user manually types the provided verification URI and
authenticates with the authorization server. The authorization
server prompts the end-user to authorize the client's request by
entering the end-user code provided by the client. Once the end-user
approves or denies the request, the authorization server informs the
end-user to return to the device for further instructions.
3.4. Device Token Request
As the user is authorizing the request on secondary device which may
not have a way to communicate to the original device, the client
polls the token endpoint until the end-user grants or denies the
request, or the device code expires.
The client polls at reasonable interval which MUST NOT exceed the
minimum interval provided by the authorization server via the
"interval" parameter (if provided).
The client makes a request to the token endpoint by sending the
following parameters using the "application/x-www-form-urlencoded"
format per Appendix B with a character encoding of UTF-8 in the HTTP
request entity-body:
grant_type
REQUIRED. Value MUST be set to "urn:ietf:params:oauth:grant-
type:device_code".
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device_code
REQUIRED. The device verification code, "device_code" from the
Device Authorization Response, defined in Section 3.2.
client_id
REQUIRED, if the client is not authenticating with the
authorization server as described in Section 3.2.1. of [RFC6749]
For example, the client makes the following HTTPS request (line
breaks are for display purposes only):
POST /token HTTP/1.1
Host: server.example.com
Content-Type: application/x-www-form-urlencoded
grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Adevice_code&device_code=pxDoJ3Bt9WVMTXfDATLkxJ9u
&client_id=459691054427
Note that unlike the Access Token Request for the authorization_code
grant type defined in Section 4.1.3 of [RFC6749] the "redirect_uri"
parameter is NOT REQUIRED as part of this request.
If the client was issued client credentials (or assigned other
authentication requirements), the client MUST authenticate with the
authorization server as described in Section 3.2.1 of [RFC6749].
3.5. Device Token Response
If the user has approved the grant, the token endpoint responds with
a success response defined in Section 5.1 of [RFC6749] otherwise, it
responds with an error, as defined in Section 5.2 of [RFC6749].
In addition to the error codes defined in Section 5.2 of [RFC6749],
the following error codes are specific for the device flow:
authorization_pending
The authorization request is still pending as the end-user hasn't
yet visited the authorization server and entered their
verification code.
slow_down
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The client is polling too quickly and should back off at a
reasonable rate.
expired_token
The device_code has expired. The client will need to make a new
Device Authorization Request.
The error code "authorization_pending" and "slow_down" are considered
soft errors. The the client should continue to poll when receiving
"authorization_pending" errors, reducing the interval if a
"slow_down" error is received. Other error codes are considered hard
errors, the client should stop polling and react accordingly, for
example, by displaying an error to the user.
4. IANA Considerations
4.1. OAuth URI Registration
This specification registers the following values in the IANA "OAuth
URI" registry [IANA.OAuth.Parameters] established by [RFC6755].
4.1.1. Registry Contents
o URN: urn:ietf:params:oauth:grant-type:device_code
o Common Name: Device flow grant type for OAuth 2.0
o Change controller: IESG
o Specification Document: Section 3.1 of [[ this specification ]]
4.2. OAuth Extensions Error Registration
This specification registers the following values in the IANA "OAuth
Extensions Error Registry" registry [IANA.OAuth.Parameters]
established by [RFC6749].
4.2.1. Registry Contents
o Error name: authorization_pending
o Error usage location: Token endpoint response
o Related protocol extension: [[ this specification ]]
o Change controller: IETF
o Specification Document: Section 3.5 of [[ this specification ]]
o Error name: slow_down
o Error usage location: Token endpoint response
o Related protocol extension: [[ this specification ]]
o Change controller: IETF
o Specification Document: Section 3.5 of [[ this specification ]]
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o Error name: expired_token
o Error usage location: Token endpoint response
o Related protocol extension: [[ this specification ]]
o Change controller: IETF
o Specification Document: Section 3.5 of [[ this specification ]]
5. Security Considerations
TBD
6. Normative References
[IANA.OAuth.Parameters]
IANA, "OAuth Parameters",
<http://www.iana.org/assignments/oauth-parameters>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012,
<http://www.rfc-editor.org/info/rfc6749>.
[RFC6755] Campbell, B. and H. Tschofenig, "An IETF URN Sub-Namespace
for OAuth", RFC 6755, DOI 10.17487/RFC6755, October 2012,
<http://www.rfc-editor.org/info/rfc6755>.
Appendix A. Acknowledgements
The -00 version of this document was based on draft-recordon-oauth-
v2-device edited by David Recordon and Brent Goldman. The content of
that document was initially part of the OAuth 2.0 protocol
specification but was later removed due to the lack of sufficient
deployment expertise at that time. We would therefore also like to
thank the OAuth working group for their work on the initial content
of this specification through 2010.
Appendix B. Document History
[[ to be removed by the RFC Editor before publication as an RFC ]]
-01
o Applied spelling and grammar corrections and added the Document
History appendix.
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-00
o Initial working group draft based on draft-recordon-oauth-
v2-device.
Authors' Addresses
William Denniss
Google
1600 Amphitheatre Pkwy
Mountain View, CA 94043
USA
Phone: +1 650-253-0000
Email: wdenniss@google.com
URI: http://google.com/
Stein Myrseth
ForgeRock
Lysaker torg 2
Lysaker 1366
NORWAY
Email: stein.myrseth@forgerock.com
John Bradley
Ping Identity
Email: ve7jtb@ve7jtb.com
URI: http://www.thread-safe.com/
Michael B. Jones
Microsoft
Email: mbj@microsoft.com
URI: http://self-issued.info/
Hannes Tschofenig
ARM Limited
Austria
Email: Hannes.Tschofenig@gmx.net
URI: http://www.tschofenig.priv.at
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