Additional OAuth Parameters for Authorization in Constrained Environments (ACE)
draft-ietf-ace-oauth-params-00
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| Document | Type | Active Internet-Draft (ace WG) | |
|---|---|---|---|
| Author | Ludwig Seitz | ||
| Last updated | 2018-11-04 (Latest revision 2018-09-18) | ||
| Stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-ace-oauth-params-00
ACE Working Group L. Seitz
Internet-Draft RISE
Intended status: Standards Track September 18, 2018
Expires: March 22, 2019
Additional OAuth Parameters for Authorization in Constrained
Environments (ACE)
draft-ietf-ace-oauth-params-00
Abstract
This specification defines new parameters for the OAuth 2.0 token and
introspection endpoints when used with framework for authentication
and authorization for constrained environments (ACE). These are used
to express the desired audience of a requested access token, the
desired proof-of-possession key, the proof-of-possession key that the
AS has selected, and the key the RS should use to authenticate to the
client.
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
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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 March 22, 2019.
Copyright Notice
Copyright (c) 2018 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
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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 . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Parameters for the Token Endpoint . . . . . . . . . . . . . . 3
3.1. Client-to-AS Request . . . . . . . . . . . . . . . . . . 3
3.2. AS-to-Client Response . . . . . . . . . . . . . . . . . . 3
4. Parameters for the Introspection Endpoint . . . . . . . . . . 4
4.1. AS-to-RS Response . . . . . . . . . . . . . . . . . . . . 4
5. Confirmation Method Parameters . . . . . . . . . . . . . . . 4
6. CBOR Mappings . . . . . . . . . . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 5
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
9.1. OAuth Parameter Registration . . . . . . . . . . . . . . 6
9.2. OAuth Introspection Response Parameter Registration . . . 6
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
11. Normative References . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
The Authorization for the Internet of Things specification
[I-D.ietf-ace-oauth-authz] requires some new parameters for requests
and responses to the OAuth 2.0 [RFC6749] token and introspection
endpoints, as well as some new claims to be used in access tokens.
This document specifies these new parameters and claims separately
from the framework, so they can be used and updated independently.
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 BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
Readers are assumed to be familiar with the terminology from
[I-D.ietf-ace-oauth-authz].
Note that the term "endpoint" is used here following its OAuth 2.0
[RFC6749] definition, which is to denote resources such as token and
introspection at the AS and authz-info at the RS. The CoAP [RFC7252]
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definition, which is "An entity participating in the CoAP protocol"
is not used in this specification.
3. Parameters for the Token Endpoint
3.1. Client-to-AS Request
This document defines the following additional parameters for
requesting an access token from a token endpoint in the ACE framework
[I-D.ietf-ace-oauth-authz]:
req_aud
OPTIONAL. Specifies the audience for which the client is
requesting an access token. If this parameter is missing, it is
assumed that the AS has a default audience for access tokens
issued to this client. If a client submits a request for an
access token without specifying a "req_aud" parameter, and the AS
does not have a default audience value for this client, then the
AS MUST respond with an error message using a response code
equivalent to the CoAP response code 4.00 (Bad Request).
req_cnf
OPTIONAL. This field contains information about the key the
client would like to bind to the access token for proof-of-
possession. It is RECOMMENDED that an AS reject a request
containing a symmetric key value in the 'req_cnf' field, since the
AS is expected to be able to generate better symmetric keys than a
potentially constrained client. See Section 5 for more details on
the use of this parameter.
3.2. AS-to-Client Response
This document defines the following additional parameters for an AS
response to a request to the token endpoint:
cnf
REQUIRED if the token type is "pop" and a symmetric key is used.
MAY be present for asymmetric proof-of-possession keys. This
field contains the proof-of-possession key that the AS selected
for the token. See Section 5 for details on the use of this
parameter.
rs_cnf
OPTIONAL if the token type is "pop" and asymmetric keys are used.
MUST NOT be present otherwise. This field contains information
about the public key used by the RS to authenticate. If this
parameter is absent, either the RS does not use a public key or
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the AS assumes that the client already knows the public key of the
RS. See Section 5 for details on the use of this parameter.
4. Parameters for the Introspection Endpoint
4.1. AS-to-RS Response
This document defines the following additional parameters for an AS
response to a request to the introspection endpoint:
cnf
OPTIONAL. This field contains information about the proof-of-
possession key that binds the client to the access token. See
Section 5 for more details on the use of the "cnf" parameter.
rs_cnf
OPTIONAL. If the RS has several keys it can use to authenticate
towards the client, the AS can give the RS a hint using this
parameter, as to which key it should use (e.g., if the AS
previously informed the client about a public key the RS is
holding). See Section 5 for more details on the use of this
parameter.
5. Confirmation Method Parameters
The confirmation method parameters are used as follows:
o "req_cnf" in the token request C -> AS, OPTIONAL to indicate the
client's raw public key, or the key-identifier of a previously
established key between C and RS that the client wishes to use for
proof-of-possession of the access token.
o "cnf" in the token response AS -> C, OPTIONAL if using an
asymmetric key or a key that the client requested via a key
identifier in the request. REQUIRED if the client didn't specify
a "req_cnf" and symmetric keys are used. Used to indicate the
symmetric key generated by the AS for proof-of-possession of the
access token.
o "cnf" in the introspection response AS -> RS, REQUIRED if the
token that was subject to introspection is a proof-of-possession
token, absent otherwise. Indicates the proof-of-possession key
bound to the token.
o "rs_cnf" in the token response AS -> C, OPTIONAL to indicate the
public key of the RS if it has one.
o "rs_cnf" in the introspection response AS -> RS, OPTIONAL to
indicate to the RS which asymmetric key pair to use for
authenticating to the client if the RS has several public keys.
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All confirmation parameters use the same formatting and semantics as
the "cnf" claim specified in [I-D.ietf-ace-cwt-proof-of-possession]
when used with a CBOR encoding. When these parameters are used with
a JSON encoding, the formatting and semantics of the "cnf" claim
specified in [RFC7800] is used.
Note that the COSE_Key structure in a confirmation claim or parameter
may contain an "alg" or "key_ops" parameter. If such parameters are
present, a client MUST NOT use a key that is not compatible with the
profile or proof-of-possession algorithm according to those
parameters. An RS MUST reject a proof-of-possession using such a
key.
If an access token is issued for an audience that includes several
RS, the "rs_cnf" parameter MUST NOT be used, since the client cannot
determine for which RS the key applies. This document recommends to
specify a different endpoint that the client can use to acquire RS
authentication keys in such cases. The specification of such an
endpoint is out of scope for this document.
6. CBOR Mappings
If CBOR is used, the new parameters and claims defined in this
document MUST be mapped to CBOR types as specified in Figure 1, using
the given integer abbreviation for the map key.
/-----------------+----------+----------------------------------\
| Parameter name | CBOR Key | Value Type |
|-----------------+----------+----------------------------------|
| cnf | 8 | map |
| rs_cnf | 17 | map |
| req_aud | 18 | text string |
| req_cnf | 19 | map |
\-----------------+----------+----------------------------------/
Figure 1: CBOR mappings for new parameters.
7. Security Considerations
This document is an extension to [I-D.ietf-ace-oauth-authz]. All
security considerations from that document apply here as well.
8. Privacy Considerations
This document is an extension to [I-D.ietf-ace-oauth-authz]. All
privacy considerations from that document apply here as well.
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9. IANA Considerations
9.1. OAuth Parameter Registration
This section registers the following parameters in the "OAuth
Parameters" registry [IANA.OAuthParameters]:
o Name: "req_aud"
o Parameter Usage Location: authorization request, token request
o Change Controller: IESG
o Reference: Section 3.1 of [this document]
o Name: "req_cnf"
o Parameter Usage Location: token request
o Change Controller: IESG
o Reference: Section 5 of [this document]
o Name: "rs_cnf"
o Parameter Usage Location: token response
o Change Controller: IESG
o Reference: Section 5 of [this document]
o Name: "cnf"
o Parameter Usage Location: token response
o Change Controller: IESG
o Reference: Section 5 of [this document]
9.2. OAuth Introspection Response Parameter Registration
This section registers the following parameters in the OAuth Token
Introspection Response registry [IANA.TokenIntrospectionResponse].
o Name: "cnf"
o Description: Key to prove the right to use a PoP token.
o Change Controller: IESG
o Reference: Section 4.1 of [this document]
o Name: "rs_cnf"
o Description: The key the RS should use to authenticate to the
client.
o Change Controller: IESG
o Reference: Section 4.1 of [this document]
10. Acknowledgments
This document is a product of the ACE working group of the IETF.
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Ludwig Seitz worked on this document as part of the CelticPlus
project CyberWI, with funding from Vinnova.
11. Normative References
[I-D.ietf-ace-cwt-proof-of-possession]
Jones, M., Seitz, L., Selander, G., Erdtman, S., and H.
Tschofenig, "Proof-of-Possession Key Semantics for CBOR
Web Tokens (CWTs)", draft-ietf-ace-cwt-proof-of-
possession-03 (work in progress), June 2018.
[I-D.ietf-ace-oauth-authz]
Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and
H. Tschofenig, "Authentication and Authorization for
Constrained Environments (ACE) using the OAuth 2.0
Framework (ACE-OAuth)", draft-ietf-ace-oauth-authz-13
(work in progress), July 2018.
[IANA.OAuthParameters]
IANA, "OAuth Parameters",
<https://www.iana.org/assignments/oauth-parameters/oauth-
parameters.xhtml#parameters>.
[IANA.TokenIntrospectionResponse]
IANA, "OAuth Token Introspection Response",
<https://www.iana.org/assignments/oauth-parameters/oauth-
parameters.xhtml#token-introspection-response>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
editor.org/info/rfc2119>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012,
<https://www.rfc-editor.org/info/rfc6749>.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252,
DOI 10.17487/RFC7252, June 2014, <https://www.rfc-
editor.org/info/rfc7252>.
[RFC7800] Jones, M., Bradley, J., and H. Tschofenig, "Proof-of-
Possession Key Semantics for JSON Web Tokens (JWTs)",
RFC 7800, DOI 10.17487/RFC7800, April 2016,
<https://www.rfc-editor.org/info/rfc7800>.
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[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
Author's Address
Ludwig Seitz
RISE
Scheelevaegen 17
Lund 223 70
Sweden
Email: ludwig.seitz@ri.se
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