draft-ietf-ace-dtls-authorize-02.txt   draft-ietf-ace-dtls-authorize-03.txt 
ACE Working Group S. Gerdes ACE Working Group S. Gerdes
Internet-Draft O. Bergmann Internet-Draft O. Bergmann
Intended status: Standards Track C. Bormann Intended status: Standards Track C. Bormann
Expires: May 3, 2018 Universitaet Bremen TZI Expires: September 6, 2018 Universitaet Bremen TZI
G. Selander G. Selander
Ericsson Ericsson
L. Seitz L. Seitz
RISE SICS RISE SICS
October 30, 2017 March 05, 2018
Datagram Transport Layer Security (DTLS) Profiles for Authentication and Datagram Transport Layer Security (DTLS) Profile for Authentication and
Authorization for Constrained Environments (ACE) Authorization for Constrained Environments (ACE)
draft-ietf-ace-dtls-authorize-02 draft-ietf-ace-dtls-authorize-03
Abstract Abstract
This specification defines two profiles for delegating client This specification defines a profile for delegating client
authentication and authorization in a constrained environment by authentication and authorization in a constrained environment by
establishing a Datagram Transport Layer Security (DTLS) channel establishing a Datagram Transport Layer Security (DTLS) channel
between resource-constrained nodes. The protocol relies on DTLS for between resource-constrained nodes. The protocol relies on DTLS for
communication security between entities in a constrained network communication security between entities in a constrained network
using either raw public keys or pre-shared keys. A resource- using either raw public keys or pre-shared keys. A resource-
constrained node can use this protocol to delegate management of constrained node can use this protocol to delegate management of
authorization information to a trusted host with less severe authorization information to a trusted host with less severe
limitations regarding processing power and memory. limitations regarding processing power and memory.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
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This Internet-Draft will expire on May 3, 2018. This Internet-Draft will expire on September 6, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 3 2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Resource Access . . . . . . . . . . . . . . . . . . . . . 5 2.1. Resource Access . . . . . . . . . . . . . . . . . . . . . 5
2.2. Dynamic Update of Authorization Information . . . . . . . 6 2.2. Dynamic Update of Authorization Information . . . . . . . 7
2.3. Token Expiration . . . . . . . . . . . . . . . . . . . . 7 2.3. Token Expiration . . . . . . . . . . . . . . . . . . . . 8
3. RawPublicKey Mode . . . . . . . . . . . . . . . . . . . . . . 8 3. RawPublicKey Mode . . . . . . . . . . . . . . . . . . . . . . 9
4. PreSharedKey Mode . . . . . . . . . . . . . . . . . . . . . . 10 4. PreSharedKey Mode . . . . . . . . . . . . . . . . . . . . . . 10
4.1. DTLS Channel Setup Between C and RS . . . . . . . . . . . 11 4.1. DTLS Channel Setup Between C and RS . . . . . . . . . . . 12
4.2. Updating Authorization Information . . . . . . . . . . . 13 4.2. Updating Authorization Information . . . . . . . . . . . 14
5. Security Considerations . . . . . . . . . . . . . . . . . . . 13 5. Security Considerations . . . . . . . . . . . . . . . . . . . 14
6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 13 6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 14
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
8.1. Normative References . . . . . . . . . . . . . . . . . . 14 8.1. Normative References . . . . . . . . . . . . . . . . . . 15
8.2. Informative References . . . . . . . . . . . . . . . . . 15 8.2. Informative References . . . . . . . . . . . . . . . . . 16
8.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 16 8.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction 1. Introduction
This specification defines a profile of the ACE framework This specification defines a profile of the ACE framework
[I-D.ietf-ace-oauth-authz]. In this profile, a client and a resource [I-D.ietf-ace-oauth-authz]. In this profile, a client and a resource
server use CoAP [RFC7252] over DTLS [RFC6347] to communicate. The server use CoAP [RFC7252] over DTLS [RFC6347] to communicate. The
client uses an access token, bound to a key (the proof-of-possession client uses an access token, bound to a key (the proof-of-possession
key) to authorize its access to protected resources hosted by the key) to authorize its access to protected resources hosted by the
resource server. DTLS provides communication security, proof of resource server. DTLS provides communication security, proof of
possession, and server authentication. Optionally the client and the possession, and server authentication. Optionally the client and the
skipping to change at page 4, line 24 skipping to change at page 4, line 24
Figure 1: Retrieving an Access Token Figure 1: Retrieving an Access Token
To determine the AS in charge of a resource hosted at the RS, the To determine the AS in charge of a resource hosted at the RS, the
client C MAY send an initial Unauthorized Resource Request message to client C MAY send an initial Unauthorized Resource Request message to
the RS. The RS then denies the request and sends the address of its the RS. The RS then denies the request and sends the address of its
AS back to the client C. AS back to the client C.
Once the client C knows the authorization server's address, it can Once the client C knows the authorization server's address, it can
send an Access Token request to the token endpoint at the AS as send an Access Token request to the token endpoint at the AS as
specified in [I-D.ietf-ace-oauth-authz]. If C wants to use the CoAP specified in [I-D.ietf-ace-oauth-authz]. As the Access Token request
RawPublicKey mode as described in Section 9 of RFC 7252 [2] it MUST as well as the response may contain confidential data, the
provide a key or key identifier within a "cnf" object in the token communication between the client and the authorization server MUST be
request. If the authorization server AS decides that the request is confidentiality-protected and ensure authenticity. How the mutual
to be authorized it generates an access token response for the client authentication between the client and the authorization server is
C containing a "profile" parameter with the value "coap_dtls" to achieved is out of scope for this document; the client may have been
indicate that this profile MUST be used for communication between the configured with a public key of the authorization server and have
client C and the resource server. Is also adds a "cnf" parameter been registered at the AS via the OAuth client registration mechanism
with additional data for the establishment of a secure DTLS channel as outlined in section 5.3 of draft-ietf-ace-oauth-authz [2].
between the client and the resource server. The semantics of the
'cnf' parameter depend on the type of key used between the client and If C wants to use the CoAP RawPublicKey mode as described in
the resource server, see Section 3 and Section 4. Section 9 of RFC 7252 [3] it MUST provide a key or key identifier
within a "cnf" object in the token request. If the authorization
server AS decides that the request is to be authorized it generates
an access token response for the client C containing a "profile"
parameter with the value "coap_dtls" to indicate that this profile
MUST be used for communication between the client C and the resource
server. Is also adds a "cnf" parameter with additional data for the
establishment of a secure DTLS channel between the client and the
resource server. The semantics of the 'cnf' parameter depend on the
type of key used between the client and the resource server and
control whether the client must use RPK mode or PSK mode to establish
a DTLS session with the resource server, see Section 3 and Section 4.
The Access Token returned by the authorization server then can be The Access Token returned by the authorization server then can be
used by the client to establish a new DTLS session with the resource used by the client to establish a new DTLS session with the resource
server. When the client intends to use asymmetric cryptography in server. When the client intends to use asymmetric cryptography in
the DTLS handshake with the resource server, the client MUST upload the DTLS handshake with the resource server, the client MUST upload
the Access Token to the authz-info resource on the resource server the Access Token to the authz-info resource on the resource server
before starting the DTLS handshake, as described in section 5.8.1 of before starting the DTLS handshake, as described in section 5.8.1 of
draft-ietf-ace-oauth-authz [3]. If only symmetric cryptography is draft-ietf-ace-oauth-authz [4]. If only symmetric cryptography is
used between the client and the resource server, the Access Token MAY used between the client and the resource server, the Access Token MAY
instead be transferred in the DTLS ClientKeyExchange message (see instead be transferred in the DTLS ClientKeyExchange message (see
Section 4.1). Section 4.1).
Figure 2 depicts the common protocol flow for the DTLS profile after Figure 2 depicts the common protocol flow for the DTLS profile after
the client C has retrieved the Access Token from the authorization the client C has retrieved the Access Token from the authorization
server AS. server AS.
C RS AS C RS AS
| [--- Access Token ------>] | | | [--- Access Token ------>] | |
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info resource hosted by the resource server. info resource hosted by the resource server.
On the resource server side, successful establishment of the DTLS On the resource server side, successful establishment of the DTLS
channel binds the client to the access token, functioning as a proof- channel binds the client to the access token, functioning as a proof-
of-possession associated key. Any request that the resource server of-possession associated key. Any request that the resource server
receives on this channel MUST be checked against these authorization receives on this channel MUST be checked against these authorization
rules that are associated with the identity of the client. Incoming rules that are associated with the identity of the client. Incoming
CoAP requests that are not authorized with respect to any Access CoAP requests that are not authorized with respect to any Access
Token that is associated with the client MUST be rejected by the Token that is associated with the client MUST be rejected by the
resource server with 4.01 response as described in Section 5.1.1 of resource server with 4.01 response as described in Section 5.1.1 of
draft-ietf-ace-oauth-authz [4]. draft-ietf-ace-oauth-authz [5].
Note: The identity of the client is determined by the authentication Note: The identity of the client is determined by the authentication
process process
during the DTLS handshake. In the asymmetric case, the public key during the DTLS handshake. In the asymmetric case, the public key
will define the client's identity, while in the PSK case, the will define the client's identity, while in the PSK case, the
client's identity is defined by the session key generated by the client's identity is defined by the session key generated by the
authorization server for this communication. authorization server for this communication.
The resource server SHOULD treat an incoming CoAP request as The resource server SHOULD treat an incoming CoAP request as
authorized if the following holds: authorized if the following holds:
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4. The resource URI specified in the request is covered by the 4. The resource URI specified in the request is covered by the
authorization information. authorization information.
5. The request method is an authorized action on the resource with 5. The request method is an authorized action on the resource with
respect to the authorization information. respect to the authorization information.
Incoming CoAP requests received on a secure DTLS channel MUST be Incoming CoAP requests received on a secure DTLS channel MUST be
rejected according to [Section 5.1.1 of draft-ietf-ace-oauth- rejected according to [Section 5.1.1 of draft-ietf-ace-oauth-
authz](https://tools.ietf.org/html/draft-ietf-ace-oauth-authz- authz](https://tools.ietf.org/html/draft-ietf-ace-oauth-authz-
08#section-5.1.1 10#section-5.1.1
1. with response code 4.03 (Forbidden) when the resource URI 1. with response code 4.03 (Forbidden) when the resource URI
specified in the request is not covered by the authorization specified in the request is not covered by the authorization
information, and information, and
2. with response code 4.05 (Method Not Allowed) when the resource 2. with response code 4.05 (Method Not Allowed) when the resource
URI specified in the request covered by the authorization URI specified in the request covered by the authorization
information but not the requested action. information but not the requested action.
The client cannot always know a priori if an Authorized Resource The client cannot always know a priori if an Authorized Resource
Request will succeed. If the client repeatedly gets error responses Request will succeed. If the client repeatedly gets error responses
containing AS Information (cf. Section 5.1.1 of draft-ietf-ace- containing AS Information (cf. Section 5.1.1 of draft-ietf-ace-
oauth-authz [5] as response to its requests, it SHOULD request a new oauth-authz [6] as response to its requests, it SHOULD request a new
Access Token from the authorization server in order to continue Access Token from the authorization server in order to continue
communication with the resource server. communication with the resource server.
2.2. Dynamic Update of Authorization Information 2.2. Dynamic Update of Authorization Information
The client can update the authorization information stored at the The client can update the authorization information stored at the
resource server at any time without changing an established DTLS resource server at any time without changing an established DTLS
session. To do so, the Client requests from the authorization server session. To do so, the Client requests from the authorization server
a new Access Token for the intended action on the respective resource a new Access Token for the intended action on the respective resource
and uploads this Access Token to the authz-info resource on the and uploads this Access Token to the authz-info resource on the
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Figure 3 depicts the message flow where the client C requests a new Figure 3 depicts the message flow where the client C requests a new
Access Token after a security association between the client and the Access Token after a security association between the client and the
resource server RS has been established using this protocol. The resource server RS has been established using this protocol. The
token request MUST specify the key identifier of the existing DTLS token request MUST specify the key identifier of the existing DTLS
channel between the client and the resource server in the "kid" channel between the client and the resource server in the "kid"
parameter of the Client-to-AS request. The authorization server MUST parameter of the Client-to-AS request. The authorization server MUST
verify that the specified "kid" denotes a valid verifier for a proof- verify that the specified "kid" denotes a valid verifier for a proof-
of-possession ticket that has previously been issued to the of-possession ticket that has previously been issued to the
requesting client. Otherwise, the Client-to-AS request MUST be requesting client. Otherwise, the Client-to-AS request MUST be
declined with a the error code "unsupported_pop_key" as defined in declined with a the error code "unsupported_pop_key" as defined in
Section 5.6.3 of draft-ietf-ace-oauth-authz [6]. Section 5.6.3 of draft-ietf-ace-oauth-authz [7].
When the authorization server issues a new access token to update When the authorization server issues a new access token to update
existing authorization information it MUST include the specified existing authorization information it MUST include the specified
"kid" parameter in this access token. A resource server MUST "kid" parameter in this access token. A resource server MUST
associate the updated authorization information with any existing associate the updated authorization information with any existing
DTLS session that is identified by this key identifier. DTLS session that is identified by this key identifier.
Note: By associating the access tokens with the identifier of an Note: By associating the access tokens with the identifier of an
existing DTLS session, the authorization information can be existing DTLS session, the authorization information can be
updated without changing the cryptographic keys for the DTLS updated without changing the cryptographic keys for the DTLS
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2.3. Token Expiration 2.3. Token Expiration
DTLS sessions that have been established in accordance with this DTLS sessions that have been established in accordance with this
profile are always tied to a specific set of access tokens. As these profile are always tied to a specific set of access tokens. As these
tokens may become invalid at any time (either because the token has tokens may become invalid at any time (either because the token has
expired or the responsible authorization server has revoked the expired or the responsible authorization server has revoked the
token), the session may become useless at some point. A resource token), the session may become useless at some point. A resource
server therefore may decide to terminate existing DTLS sessions after server therefore may decide to terminate existing DTLS sessions after
the last valid access token for this session has been deleted. the last valid access token for this session has been deleted.
As specified in section 5.8.2 of draft-ietf-ace-oauth-authz [7], the As specified in section 5.8.2 of draft-ietf-ace-oauth-authz [8], the
resource server MUST notify the client with an error response with resource server MUST notify the client with an error response with
code 4.01 (Unauthorized) for any long running request before code 4.01 (Unauthorized) for any long running request before
terminating the session. terminating the session.
The resource server MAY also keep the session alive for some time and The resource server MAY also keep the session alive for some time and
respond to incoming requests with a 4.01 (Unauthorized) error message respond to incoming requests with a 4.01 (Unauthorized) error message
including AS Information to signal that the client needs to upload a including AS Information to signal that the client needs to upload a
new access token before it can continue using this DTLS session. The new access token before it can continue using this DTLS session. The
AS Information is created as specified in section 5.1.2 of draft- AS Information is created as specified in section 5.1.2 of draft-
ietf-ace-oauth-authz [8]. The resource server SHOULD add a "kid" ietf-ace-oauth-authz [9]. The resource server SHOULD add a "kid"
parameter to the AS Information denoting the identifier of the key parameter to the AS Information denoting the identifier of the key
that it uses internally for this DTLS session. The client then that it uses internally for this DTLS session. The client then
includes this "kid" parameter in a Client-to-AS request used to includes this "kid" parameter in a Client-to-AS request used to
retrieve a new access token to be used with this DTLS session. In retrieve a new access token to be used with this DTLS session. In
case the key identifier is already known by the client (e.g. because case the key identifier is already known by the client (e.g. because
it was included in the RS Information in an AS-to-Client response), it was included in the RS Information in an AS-to-Client response),
the "kid" parameter MAY be elided from the AS Information. the "kid" parameter MAY be elided from the AS Information.
Table 1 updates Figure 2 in section 5.1.2 of draft-ietf-ace-oauth- Table 1 updates Figure 2 in section 5.1.2 of draft-ietf-ace-oauth-
authz [9] with the new "kid" parameter in accordance with [RFC8152]. authz [10] with the new "kid" parameter in accordance with [RFC8152].
+----------------+----------+-----------------+ +----------------+----------+-----------------+
| Parameter name | CBOR Key | Major Type | | Parameter name | CBOR Key | Major Type |
+----------------+----------+-----------------+ +----------------+----------+-----------------+
| kid | 4 | 2 (byte string) | | kid | 4 | 2 (byte string) |
+----------------+----------+-----------------+ +----------------+----------+-----------------+
Table 1: Updated AS Information parameters Table 1: Updated AS Information parameters
3. RawPublicKey Mode 3. RawPublicKey Mode
To retrieve an access token for the resource that the client wants to To retrieve an access token for the resource that the client wants to
access, the client requests an Access Token from the authorization access, the client requests an Access Token from the authorization
server. The client MUST add a "cnf" object carrying either its raw server. The client MUST add a "cnf" object carrying either its raw
public key or a unique identifier for a public key that it has public key or a unique identifier for a public key that it has
previously made known to the authorization server. previously made known to the authorization server. To prove that the
client is in possession of this key, it MUST use the same public key
as in certificate message that is used to establish the DTLS session
with the authorization server.
An example Access Token request from the client to the resource An example Access Token request from the client to the resource
server is depicted in Figure 4. server is depicted in Figure 4.
POST coaps://as.example.com/token POST coaps://as.example.com/token
Content-Format: application/cbor Content-Format: application/cbor
{ {
grant_type: client_credentials, grant_type: client_credentials,
aud: "tempSensor4711", aud: "tempSensor4711",
cnf: { cnf: {
skipping to change at page 9, line 37 skipping to change at page 10, line 13
Access Token and a "cnf" object in the AS-to-Client response. Before Access Token and a "cnf" object in the AS-to-Client response. Before
the client initiates the DTLS handshake with the resource server, it the client initiates the DTLS handshake with the resource server, it
MUST send a "POST" request containing the new Access Token to the MUST send a "POST" request containing the new Access Token to the
authz-info resource hosted by the resource server. If this operation authz-info resource hosted by the resource server. If this operation
yields a positive response, the client SHOULD proceed to establish a yields a positive response, the client SHOULD proceed to establish a
new DTLS channel with the resource server. To use raw public key new DTLS channel with the resource server. To use raw public key
mode, the client MUST pass the same public key that was used for mode, the client MUST pass the same public key that was used for
constructing the Access Token with the SubjectPublicKeyInfo structure constructing the Access Token with the SubjectPublicKeyInfo structure
in the DTLS handshake as specified in [RFC7250]. in the DTLS handshake as specified in [RFC7250].
An implementation that supports the RPK mode of this profile MUST at
least support the ciphersuite TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8
[RFC7251] with the ed25519 curve (cf. [RFC8032],
[I-D.ietf-tls-rfc4492bis]).
Note: According to [RFC7252], CoAP implementations MUST support the Note: According to [RFC7252], CoAP implementations MUST support the
ciphersuite TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8 [RFC7251] and the ciphersuite TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8 [RFC7251] and the
NIST P-256 curve. the client is therefore expected to offer at NIST P-256 curve. As discussed in [RFC7748], new ECC curves have
least this ciphersuite to the resource server. been defined recently that are considered superior to the so-
called NIST curves. The curve that is mandatory to implement in
this specification is said to be efficient and less dangerous
regarding implementation errors than the secp256r1 curve mandated
in [RFC7252].
The Access Token is constructed by the authorization server such that The Access Token is constructed by the authorization server such that
the resource server can associate the Access Token with the Client's the resource server can associate the Access Token with the Client's
public key. If CBOR web tokens [I-D.ietf-ace-cbor-web-token] are public key. If CBOR web tokens [I-D.ietf-ace-cbor-web-token] are
used as recommended in [I-D.ietf-ace-oauth-authz], the authorization used as recommended in [I-D.ietf-ace-oauth-authz], the authorization
server MUST include a "COSE_Key" object in the "cnf" claim of the server MUST include a "COSE_Key" object in the "cnf" claim of the
Access Token. This "COSE_Key" object MAY contain a reference to a Access Token. This "COSE_Key" object MAY contain a reference to a
key for the client that is already known by the resource server key for the client that is already known by the resource server
(e.g., from previous communication). If the authorization server has (e.g., from previous communication). If the authorization server has
no certain knowledge that the Client's key is already known to the no certain knowledge that the Client's key is already known to the
skipping to change at page 10, line 36 skipping to change at page 11, line 22
to-Client response with the profile parameter set to "coap_dtls" and to-Client response with the profile parameter set to "coap_dtls" and
a "cnf" parameter carrying a "COSE_Key" object that contains the a "cnf" parameter carrying a "COSE_Key" object that contains the
symmetric session key to be used between the client and the resource symmetric session key to be used between the client and the resource
server as illustrated in Figure 5. server as illustrated in Figure 5.
2.01 Created 2.01 Created
Content-Format: application/cbor Content-Format: application/cbor
Location-Path: /token/asdjbaskd Location-Path: /token/asdjbaskd
Max-Age: 86400 Max-Age: 86400
{ {
access_token: b64'SlAV32hkKG ... access_token: h'd08343a10...
(remainder of CWT omitted for brevity; (remainder of CWT omitted for brevity)
token_type: pop, token_type: pop,
alg: HS256, alg: HS256,
expires_in: 86400, expires_in: 86400,
profile: coap_dtls, profile: coap_dtls,
cnf: { cnf: {
COSE_Key: { COSE_Key: {
kty: symmetric, kty: symmetric,
k: h'73657373696f6e6b6579' k: h'73657373696f6e6b6579'
} }
} }
skipping to change at page 11, line 12 skipping to change at page 11, line 45
Figure 5: Example Access Token response Figure 5: Example Access Token response
In this example, the authorization server returns a 2.01 response In this example, the authorization server returns a 2.01 response
containing a new Access Token. The information is transferred as a containing a new Access Token. The information is transferred as a
CBOR data structure as specified in [I-D.ietf-ace-oauth-authz]. The CBOR data structure as specified in [I-D.ietf-ace-oauth-authz]. The
Max-Age option tells the receiving Client how long this token will be Max-Age option tells the receiving Client how long this token will be
valid. valid.
A response that declines any operation on the requested resource is A response that declines any operation on the requested resource is
constructed according to Section 5.2 of RFC 6749 [10], (cf. constructed according to Section 5.2 of RFC 6749 [11], (cf.
Section 5.7.3 of [I-D.ietf-ace-oauth-authz]). Section 5.7.3 of [I-D.ietf-ace-oauth-authz]).
4.00 Bad Request 4.00 Bad Request
Content-Format: application/cbor Content-Format: application/cbor
{ {
error: invalid_request error: invalid_request
} }
Figure 6: Example Access Token response with reject Figure 6: Example Access Token response with reject
skipping to change at page 11, line 41 skipping to change at page 12, line 31
in the "cnf" parameter of the AS response as PSK when constructing in the "cnf" parameter of the AS response as PSK when constructing
the premaster secret. the premaster secret.
In PreSharedKey mode, the knowledge of the session key by the client In PreSharedKey mode, the knowledge of the session key by the client
and the resource server is used for mutual authentication between and the resource server is used for mutual authentication between
both peers. Therefore, the resource server must be able to determine both peers. Therefore, the resource server must be able to determine
the session key from the Access Token. Following the general ACE the session key from the Access Token. Following the general ACE
authorization framework, the client can upload the Access Token to authorization framework, the client can upload the Access Token to
the resource server's authz-info resource before starting the DTLS the resource server's authz-info resource before starting the DTLS
handshake. Alternatively, the client MAY provide the most recent handshake. Alternatively, the client MAY provide the most recent
base64-encoded Access Token in the "psk_identity" field of the Access Token in the "psk_identity" field of the ClientKeyExchange
ClientKeyExchange message. message. To do so, the client MUST treat the contents of the
"access_token" field from the AS-to-Client response as opaque data
and not perform any re-coding.
Note: As stated in section 4.2 of [RFC7925], the PSK identity should
be treated as binary data in the Internet of Things space and not
assumed to have a human-readable form of any sort.
If a resource server receives a ClientKeyExchange message that If a resource server receives a ClientKeyExchange message that
contains a "psk_identity" with a length greater zero, it MUST contains a "psk_identity" with a length greater zero, it uses the
base64-decode its contents and use the resulting byte sequence as contents as index for its key store (i.e., treat the contents as key
index for its key store (i.e., treat the contents as key identifier). identifier). The resource server MUST check if it has one or more
The resource server MUST check if it has one or more Access Tokens Access Tokens that are associated with the specified key. If no
that are associated with the specified key. If no valid Access Token valid Access Token is available for this key, the DTLS session setup
is available for this key, the DTLS session setup is terminated with is terminated with an "illegal_parameter" DTLS alert message.
an "illegal_parameter" DTLS alert message.
If no key with a matching identifier is found the resource server the If no key with a matching identifier is found the resource server the
resource server MAY process the decoded contents of the resource server MAY process the decoded contents of the
"psk_identity" field as access token that is stored with the "psk_identity" field as access token that is stored with the
authorization information endpoint before continuing the DTLS authorization information endpoint before continuing the DTLS
handshake. If the decoded contents of the "psk_identity" do not handshake. If the decoded contents of the "psk_identity" do not
yield a valid access token for the requesting client, the DTLS yield a valid access token for the requesting client, the DTLS
session setup is terminated with an "illegal_parameter" DTLS alert session setup is terminated with an "illegal_parameter" DTLS alert
message. message.
skipping to change at page 12, line 44 skipping to change at page 13, line 38
provided in the "psk_identity" field. Usually, this is done by provided in the "psk_identity" field. Usually, this is done by
including a "COSE_Key" object carrying either a key that has been including a "COSE_Key" object carrying either a key that has been
encrypted with a shared secret between the authorization server and encrypted with a shared secret between the authorization server and
the resource server, or a key identifier that can be used by the the resource server, or a key identifier that can be used by the
resource server to lookup the session key. resource server to lookup the session key.
Instead of the "COSE_Key" object, the authorization server MAY Instead of the "COSE_Key" object, the authorization server MAY
include a "COSE_Encrypt" structure to enable the resource server to include a "COSE_Encrypt" structure to enable the resource server to
calculate the session key from the Access Token. The "COSE_Encrypt" calculate the session key from the Access Token. The "COSE_Encrypt"
structure MUST use the _Direct Key with KDF_ method as described in structure MUST use the _Direct Key with KDF_ method as described in
Section 12.1.2 of RFC 8152 [11]. The authorization server MUST Section 12.1.2 of RFC 8152 [12]. The authorization server MUST
include a Context information structure carrying a PartyU "nonce" include a Context information structure carrying a PartyU "nonce"
parameter carrying the nonce that has been used by the authorization parameter carrying the nonce that has been used by the authorization
server to construct the session key. server to construct the session key.
This specification mandates that at least the key derivation This specification mandates that at least the key derivation
algorithm "HKDF SHA-256" as defined in [RFC8152] MUST be supported. algorithm "HKDF SHA-256" as defined in [RFC8152] MUST be supported.
This key derivation function is the default when no "alg" field is This key derivation function is the default when no "alg" field is
included in the "COSE_Encrypt" structure for the resource server. included in the "COSE_Encrypt" structure for the resource server.
4.2. Updating Authorization Information 4.2. Updating Authorization Information
skipping to change at page 14, line 29 skipping to change at page 15, line 29
Profile Description: Profile for delegating client authentication and Profile Description: Profile for delegating client authentication and
authorization in a constrained environment by establishing a Datagram authorization in a constrained environment by establishing a Datagram
Transport Layer Security (DTLS) channel between resource-constrained Transport Layer Security (DTLS) channel between resource-constrained
nodes. nodes.
Profile ID: 1 Profile ID: 1
Change Controller: IESG Change Controller: IESG
Specification Document(s): [RFC-XXXX] Reference: [RFC-XXXX]
8. References 8. References
8.1. Normative References 8.1. Normative References
[I-D.ietf-ace-oauth-authz] [I-D.ietf-ace-oauth-authz]
Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and
H. Tschofenig, "Authentication and Authorization for H. Tschofenig, "Authentication and Authorization for
Constrained Environments (ACE)", draft-ietf-ace-oauth- Constrained Environments (ACE)", draft-ietf-ace-oauth-
authz-08 (work in progress), October 2017. authz-10 (work in progress), February 2018.
[I-D.tiloca-tls-dos-handshake] [I-D.tiloca-tls-dos-handshake]
Tiloca, M., Seitz, L., Hoeve, M., and O. Bergmann, Tiloca, M., Seitz, L., Hoeve, M., and O. Bergmann,
"Extension for protecting (D)TLS handshakes against Denial "Extension for protecting (D)TLS handshakes against Denial
of Service", draft-tiloca-tls-dos-handshake-01 (work in of Service", draft-tiloca-tls-dos-handshake-01 (work in
progress), October 2017. progress), October 2017.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, <https://www.rfc- DOI 10.17487/RFC2119, March 1997,
editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC4279] Eronen, P., Ed. and H. Tschofenig, Ed., "Pre-Shared Key [RFC4279] Eronen, P., Ed. and H. Tschofenig, Ed., "Pre-Shared Key
Ciphersuites for Transport Layer Security (TLS)", Ciphersuites for Transport Layer Security (TLS)",
RFC 4279, DOI 10.17487/RFC4279, December 2005, RFC 4279, DOI 10.17487/RFC4279, December 2005,
<https://www.rfc-editor.org/info/rfc4279>. <https://www.rfc-editor.org/info/rfc4279>.
[RFC5746] Rescorla, E., Ray, M., Dispensa, S., and N. Oskov, [RFC5746] Rescorla, E., Ray, M., Dispensa, S., and N. Oskov,
"Transport Layer Security (TLS) Renegotiation Indication "Transport Layer Security (TLS) Renegotiation Indication
Extension", RFC 5746, DOI 10.17487/RFC5746, February 2010, Extension", RFC 5746, DOI 10.17487/RFC5746, February 2010,
<https://www.rfc-editor.org/info/rfc5746>. <https://www.rfc-editor.org/info/rfc5746>.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347, Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <https://www.rfc-editor.org/info/rfc6347>. January 2012, <https://www.rfc-editor.org/info/rfc6347>.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained [RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252, Application Protocol (CoAP)", RFC 7252,
DOI 10.17487/RFC7252, June 2014, <https://www.rfc- DOI 10.17487/RFC7252, June 2014,
editor.org/info/rfc7252>. <https://www.rfc-editor.org/info/rfc7252>.
[RFC7925] Tschofenig, H., Ed. and T. Fossati, "Transport Layer
Security (TLS) / Datagram Transport Layer Security (DTLS)
Profiles for the Internet of Things", RFC 7925,
DOI 10.17487/RFC7925, July 2016,
<https://www.rfc-editor.org/info/rfc7925>.
[RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)", [RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)",
RFC 8152, DOI 10.17487/RFC8152, July 2017, RFC 8152, DOI 10.17487/RFC8152, July 2017,
<https://www.rfc-editor.org/info/rfc8152>. <https://www.rfc-editor.org/info/rfc8152>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
8.2. Informative References 8.2. Informative References
[I-D.ietf-ace-cbor-web-token] [I-D.ietf-ace-cbor-web-token]
Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig, Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
"CBOR Web Token (CWT)", draft-ietf-ace-cbor-web-token-09 "CBOR Web Token (CWT)", draft-ietf-ace-cbor-web-token-12
(work in progress), October 2017. (work in progress), February 2018.
[I-D.ietf-tls-rfc4492bis]
Nir, Y., Josefsson, S., and M. Pegourie-Gonnard, "Elliptic
Curve Cryptography (ECC) Cipher Suites for Transport Layer
Security (TLS) Versions 1.2 and Earlier", draft-ietf-tls-
rfc4492bis-17 (work in progress), May 2017.
[RFC6655] McGrew, D. and D. Bailey, "AES-CCM Cipher Suites for [RFC6655] McGrew, D. and D. Bailey, "AES-CCM Cipher Suites for
Transport Layer Security (TLS)", RFC 6655, Transport Layer Security (TLS)", RFC 6655,
DOI 10.17487/RFC6655, July 2012, <https://www.rfc- DOI 10.17487/RFC6655, July 2012,
editor.org/info/rfc6655>. <https://www.rfc-editor.org/info/rfc6655>.
[RFC7250] Wouters, P., Ed., Tschofenig, H., Ed., Gilmore, J., [RFC7250] Wouters, P., Ed., Tschofenig, H., Ed., Gilmore, J.,
Weiler, S., and T. Kivinen, "Using Raw Public Keys in Weiler, S., and T. Kivinen, "Using Raw Public Keys in
Transport Layer Security (TLS) and Datagram Transport Transport Layer Security (TLS) and Datagram Transport
Layer Security (DTLS)", RFC 7250, DOI 10.17487/RFC7250, Layer Security (DTLS)", RFC 7250, DOI 10.17487/RFC7250,
June 2014, <https://www.rfc-editor.org/info/rfc7250>. June 2014, <https://www.rfc-editor.org/info/rfc7250>.
[RFC7251] McGrew, D., Bailey, D., Campagna, M., and R. Dugal, "AES- [RFC7251] McGrew, D., Bailey, D., Campagna, M., and R. Dugal, "AES-
CCM Elliptic Curve Cryptography (ECC) Cipher Suites for CCM Elliptic Curve Cryptography (ECC) Cipher Suites for
TLS", RFC 7251, DOI 10.17487/RFC7251, June 2014, TLS", RFC 7251, DOI 10.17487/RFC7251, June 2014,
<https://www.rfc-editor.org/info/rfc7251>. <https://www.rfc-editor.org/info/rfc7251>.
[RFC7748] Langley, A., Hamburg, M., and S. Turner, "Elliptic Curves
for Security", RFC 7748, DOI 10.17487/RFC7748, January
2016, <https://www.rfc-editor.org/info/rfc7748>.
[RFC8032] Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital
Signature Algorithm (EdDSA)", RFC 8032,
DOI 10.17487/RFC8032, January 2017,
<https://www.rfc-editor.org/info/rfc8032>.
8.3. URIs 8.3. URIs
[1] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz- [1] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz-
08#section-5.8.1 10#section-5.8.1
[2] https://tools.ietf.org/html/rfc7252#section-9 [2] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz-
10#section-5.3
[3] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz- [3] https://tools.ietf.org/html/rfc7252#section-9
08#section-5.8.1
[4] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz- [4] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz-
08#section-5.5.1 10#section-5.8.1
[5] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz- [5] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz-
08#section-5.1.1 10#section-5.1.1
[6] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz- [6] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz-
08#section-5.6.3 10#section-5.1.1
[7] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz- [7] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz-
08#section-5.8.2 10#section-5.6.3
[8] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz- [8] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz-
08#section-5.1.2 10#section-5.8.2
[9] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz- [9] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz-
08#section-5.1.2 10#section-5.1.2
[10] https://tools.ietf.org/html/rfc6749#section-5.2 [10] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz-
10#section-5.1.2
[11] https://tools.ietf.org/html/rfc8152#section-12.1.2 [11] https://tools.ietf.org/html/rfc6749#section-5.2
[12] https://tools.ietf.org/html/rfc8152#section-12.1.2
Authors' Addresses Authors' Addresses
Stefanie Gerdes Stefanie Gerdes
Universitaet Bremen TZI Universitaet Bremen TZI
Postfach 330440 Postfach 330440
Bremen D-28359 Bremen D-28359
Germany Germany
Phone: +49-421-218-63906 Phone: +49-421-218-63906
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