Internet DRAFT - draft-palombini-ace-coap-pubsub-profile
draft-palombini-ace-coap-pubsub-profile
ACE Working Group F. Palombini
Internet-Draft Ericsson
Intended status: Standards Track November 04, 2019
Expires: May 7, 2020
CoAP Pub-Sub Profile for Authentication and Authorization for
Constrained Environments (ACE)
draft-palombini-ace-coap-pubsub-profile-06
Abstract
This specification defines an application profile for authentication
and authorization for publishers and subscribers in a pub-sub setting
scenario in a constrained environment, using the ACE framework. This
profile relies on transport layer or application layer security to
authorize the publisher to the broker. Moreover, it relies on
application layer security for publisher-broker and subscriber-broker
communication.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on May 7, 2020.
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document authors. All rights reserved.
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include Simplified BSD License text as described in Section 4.e of
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2
2. Application Profile Overview . . . . . . . . . . . . . . . . 3
3. coap_pubsub_app Application Profile . . . . . . . . . . . . . 5
3.1. Retrieval of COSE Key for protection of content . . . . . 5
4. Publisher . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5. Subscriber . . . . . . . . . . . . . . . . . . . . . . . . . 10
6. Pub-Sub Protected Communication . . . . . . . . . . . . . . . 12
6.1. Using COSE Objects To Protect The Resource Representation 13
7. Security Considerations . . . . . . . . . . . . . . . . . . . 14
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
8.1. ACE Groupcomm Profile Registry . . . . . . . . . . . . . 15
8.2. ACE Groupcomm Key Registry . . . . . . . . . . . . . . . 16
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
9.1. Normative References . . . . . . . . . . . . . . . . . . 16
9.2. Informative References . . . . . . . . . . . . . . . . . 17
Appendix A. Requirements on Application Profiles . . . . . . . . 17
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 19
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction
The publisher-subscriber setting allows for devices with limited
reachability to communicate via a broker that enables store-and-
forward messaging between the devices. The pub-sub scenario using
the Constrained Application Protocol (CoAP) is specified in
[I-D.ietf-core-coap-pubsub]. This document defines a way to
authorize nodes in a CoAP pub-sub type of setting, using the ACE
framework [I-D.ietf-ace-oauth-authz], and to provide the keys for
protecting the communication between these nodes.
1.1. Terminology
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 RFC 2119 [RFC2119].
Readers are expected to be familiar with the terms and concepts
described in [I-D.ietf-ace-oauth-authz], [I-D.ietf-ace-key-groupcomm]
and [I-D.ietf-core-coap-pubsub]. In particular, analogously to
[I-D.ietf-ace-oauth-authz], terminology for entities in the
architecture such as Client (C), Resource Server (RS), and
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Authorization Server (AS) is defined in OAuth 2.0 [RFC6749] and
[I-D.ietf-ace-actors], and terminology for entities such as the Key
Distribution Center (KDC) and Dispatcher in
[I-D.ietf-ace-key-groupcomm].
2. Application Profile Overview
The objective of this document is to specify how to authorize nodes,
provide keys, and protect a CoAP pub-sub communication, as described
in [I-D.ietf-core-coap-pubsub], using [I-D.ietf-ace-key-groupcomm],
which itself expands the Ace framework ([I-D.ietf-ace-oauth-authz]),
and transport profiles ([I-D.ietf-ace-dtls-authorize],
[I-D.ietf-ace-oscore-profile]).
The architecture of the scenario is shown in Figure 1.
+----------------+ +----------------+
| | | |
| Authorization | | Authorization |
| Server 1 | | Server 2 |
| | | |
+----------------+ +----------------+
^ ^ ^
| | |
+---------(A)----+ | +-----(D)------+
| +--------------------(B)--------+ |
v v v
+------------+ +------------+ +------------+
| CoAP | ----(C)---> | CoAP | | CoAP |
| Client - | ----(E)---> | Server - | | Client - |
| | | | <----(F)---- | |
| Publisher | | Broker | -----(G)---> | Subscriber |
+------------+ +------------+ +------------+
Figure 1: Architecture CoAP pubsub with Authorization Servers
The RS is the broker, which contains the topic. This node
corresponds to the Dispatcher, in [I-D.ietf-ace-key-groupcomm]. The
AS1 hosts the policies about the Broker: what endpoints are allowed
to Publish on the Broker. The Clients access this node to get write
access to the Broker. The AS2 hosts the policies about the topic:
what endpoints are allowed to access what topic. This node
represents both the AS and Key Distribution Center roles from
[I-D.ietf-ace-key-groupcomm].
There are four phases, the first three can be done in parallel.
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1. The Publisher requests publishing access to the Broker at the
AS1, and communicates with the Broker to set up security.
2. The Publisher requests access to a specific topic at the AS2
3. The Subscriber requests access to a specific topic at the AS2.
4. The Publisher and the Subscriber securely post to and get
publications from the Broker.
This exchange aims at setting up 2 different security associations:
on the one hand, the Publisher has a security association with the
Broker, to protect the communication and securely authorize the
Publisher to publish on a topic (Security Association 1). On the
other hand, the Publisher has a security association with the
Subscriber, to protect the publication content itself (Security
Association 2). The Security Association 1 is set up using AS1 and a
transport profile of [I-D.ietf-ace-oauth-authz], the Security
Association 2 is set up using AS2 and [I-D.ietf-ace-key-groupcomm].
Note that, analogously to the Publisher, the Subscriber can also set
up an additional security association with the Broker, using an AS,
in the same way the Publisher does with AS1. In this case, only
authorized Subscribers would be able to get notifications from the
Broker. The overhead would be that each Subscriber should access the
AS and get all the information to start a secure exchange with the
Broker.
+------------+ +------------+ +------------+
| CoAP | | CoAP | | CoAP |
| Client - | | Server - | | Client - |
| | | | | |
| Publisher | | Broker | | Subscriber |
+------------+ +------------+ +------------+
: : : :
: '------ Security -------' :
: Association 1 :
'------------------------------- Security --------------'
Association 2
Note that AS1 and AS2 might either be co-resident or be 2 separate
physical entities, in which case access control policies must be
exchanged between AS1 and AS2, so that they agree on rights for
joining nodes about specific topics. How the policies are exchanged
is out of scope for this specification.
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3. coap_pubsub_app Application Profile
This profile uses [I-D.ietf-ace-key-groupcomm], which expands the ACE
framework. This document specifies which exact parameters from
[I-D.ietf-ace-key-groupcomm] have to be used, and the values for each
parameter.
The Publisher and the Subscriber map to the Client in
[I-D.ietf-ace-key-groupcomm], the AS2 maps to the AS and to the KDC,
the Broker maps to the Dispatcher.
Note that both publishers and subscribers use the same profile,
called "coap_pubsub_app".
3.1. Retrieval of COSE Key for protection of content
This phase is common to both Publisher and Subscriber. To maintain
the generality, the Publisher or Subscriber is referred as Client in
this section.
Client Broker AS2
| [----- Resource Request ---->] | |
| | |
| [<-- AS1, AS2 Information ---] | |
| |
| [------ Pub Key Format Negociation Request --->] |
| |
| [<---- Pub Key Format Negociation Response ----] |
| |
| -- Authorization + Key Distribution Request ---> |
| |
| <-- Authorization + Key Distribution Response -- |
| |
Figure 2: B: Access request - response
Complementary to what is defined in [I-D.ietf-ace-oauth-authz]
(Section 5.1.1), to determine the AS2 in charge of a topic hosted at
the Broker, the Broker MAY send the address of both the AS in charge
of the topic back to the Client in the 'AS' parameter in the AS
Information, as a response to an Unauthorized Resource Request
(Section 5.1.2). The uri of AS2 is concatenated to the uri of AS1,
and separated by a comma. An example using CBOR diagnostic notation
is given below:
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4.01 Unauthorized
Content-Format: application/ace+cbor
{"AS": "coaps://as1.example.com/token,
coaps://as2.example.com/pubsubkey"}
Figure 3: AS1, AS2 Information example
After retrieving the AS2 address, the Client MAY send a request to
the AS, in order to retrieve necessary information concerning the
public keys in the group, as well as concerning the algorithm and
related parameters for computing signatures in the group. This
request is a subset of the Token POST request defined in Section 3.3
of [I-D.ietf-ace-key-groupcomm], specifically a CoAP POST request to
a specific resource at the AS, including only the parameters
'sign_info' and 'pub_key_enc' in the CBOR map in the payload. The
default url-path for this resource is /ace-group/gid/cs-info, where
"gid" is the topic identifier, but implementations are not required
to use this name, and can use their own instead. The AS MUST respond
with the response defined in Section 3.3 of
[I-D.ietf-ace-key-groupcomm], specifically including the parameters
'sign_info', 'pub_key_enc', and 'rsnonce' (8 bytes pseudo-random
nonce generated by the AS).
After that, the Client sends an Authorization + Joining Request,
which is an Authorization Request merged with a Joining Request, as
described in [I-D.ietf-ace-key-groupcomm], Sections 3.1 and 4.2. The
reason for merging these two messages is that the AS2 is both the AS
and the KDC, in this setting, so the Authorization Response and the
Post Token message are not necessary.
More specifically, the Client sends a POST request to the /ace-group/
gid endpoint on AS2, with Content-Format = "application/ace+cbor"
that MUST contain in the payload (formatted as a CBOR map):
o the following fields from the Joining Request (Section 4.2 of
[I-D.ietf-ace-key-groupcomm]):
* 'scope' parameter set to a CBOR array containing:
+ the broker's topic as first element, and
+ the text string "publisher" if the client request to be a
publisher, "subscriber" if the client request to be a
subscriber, or a CBOR array containing both, if the client
request to be both.
* 'get_pub_keys' parameter set to the empty array if the Client
needs to retrieve the public keys of the other pubsub members,
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* 'client_cred' parameter containing the Client's public key
formatted as a COSE_Key, if the Client needs to directly send
that to the AS2,
* 'cnonce', set to a 8 bytes long pseudo-random nonce, if
'client_cred' is present,
* 'client_cred_verify', set to a singature computed over the
rsnonce concatenated with cnonce, if 'client_cred' is present,
* OPTIONALLY, if needed, the 'pub_keys_repos' parameter
o the following fields from the Authorization Request (Section 3.1
of [I-D.ietf-ace-key-groupcomm]):
* OPTIONALLY, if needed, additional parameters such as
'client_id'
Note that the alg parameter in the 'client_cred' COSE_Key MUST be a
signing algorithm, as defined in section 8 of [RFC8152], and that it
is the same algorithm used to compute the signature sent in
'client_cred_verify'.
Examples of the payload of a Authorization + Joining Request are
specified in Figure 5 and Figure 8.
The AS2 verifies that the Client is authorized to access the topic
and, if the 'client_cred' parameter is present, stores the public key
of the Client.
The AS2 response is an Authorization + Joining Response, with
Content-Format = "application/ace+cbor". The payload (formatted as a
CBOR map) MUST contain:
o the following fields from the Joining Response (Section 4.1 of
[I-D.ietf-ace-key-groupcomm]):
* 'kty' identifies a key type "COSE_Key", as defined in
Section 8.2.
* 'key', which contains a "COSE_Key" object (defined in
[RFC8152], containing:
+ 'kty' with value 4 (symmetric)
+ 'alg' with value defined by the AS2 (Content Encryption
Algorithm)
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+ 'Base IV' with value defined by the AS2
+ 'k' with value the symmetric key value
+ OPTIONALLY, 'kid' with an identifier for the key value
* OPTIONALLY, 'exp' with the expiration time of the key
* 'pub_keys', containing the public keys of all authorized
signing members formatted as COSE_Keys, if the 'get_pub_keys'
parameter was present and set to the empty array in the
Authorization + Key Distribution Request
o the following fields from the Authorization Response (Section 3.2
of [I-D.ietf-ace-key-groupcomm]):
* 'profile' set to "coap_pubsub_app", as specified in Section 8.1
* OPTIONALLY 'scope', set to a CBOR array containing:
+ the broker's topic as first element, and
+ the string "publisher" if the client is an authorized
publisher, "subscriber" if the client is an authorized
subscriber, or a CBOR array containing both, if the client
is authorized to be both.
Examples for the response payload are detailed in Figure 6 and
Figure 9.
4. Publisher
In this section, it is specified how the Publisher requests, obtains
and communicates to the Broker the access token, as well as the
retrieval of the keying material to protect the publication.
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+----------------+ +----------------+
| | | |
| Authorization | | Authorization |
| Server 1 | | Server 2 |
| | | |
+----------------+ +----------------+
^ ^
| |
+---------(A)----+ |
| +--------------------(B)--------+
v v
+------------+ +------------+
| CoAP | ----(C)---> | CoAP |
| Client - | | Server - |
| | | |
| Publisher | | Broker |
+------------+ +------------+
Figure 4: Phase 1: Publisher side
This is a combination of two independent phases:
o one is the establishment of a secure connection between Publisher
and Broker, using an ACE transport profile such as DTLS
[I-D.ietf-ace-dtls-authorize] or OSCORE
[I-D.ietf-ace-oscore-profile]. (A)(C)
o the other is the Publisher's retrieval of keying material to
protect the publication. (B)
In detail:
(A) corresponds to the Access Token Request and Response between
Publisher and Authorization Server to retrieve the Access Token and
RS (Broker) Information. As specified, the Publisher has the role of
a CoAP client, the Broker has the role of the CoAP server.
(C) corresponds to the exchange between Publisher and Broker, where
the Publisher sends its access token to the Broker and establishes a
secure connection with the Broker. Depending on the Information
received in (A), this can be for example DTLS handshake, or other
protocols. Depending on the application, there may not be the need
for this set up phase: for example, if OSCORE is used directly.
(A) and (C) details are specified in the profile used.
(B) corresponds to the retrieval of the keying material to protect
the publication end-to-end with the subscribers (see Section 6.1),
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and uses [I-D.ietf-ace-key-groupcomm]. The details are defined in
Section 3.1.
An example of the payload of an Authorization + Joining Request and
corresponding Response for a Publisher is specified in Figure 5 and
Figure 6, where SIG is a signature computed using the private key
associated to the public key and the algorithm in "client_cred".
{
"scope" : ["Broker1/Temp", "publisher"],
"client_id" : "publisher1",
"client_cred" :
{ / COSE_Key /
/ type / 1 : 2, / EC2 /
/ kid / 2 : h'11',
/ alg / 3 : -7, / ECDSA with SHA-256 /
/ crv / -1 : 1 , / P-256 /
/ x / -2 : h'65eda5a12577c2bae829437fe338701a10aaa375e1bb5b5de1
08de439c08551d',
/ y /-3 : h'1e52ed75701163f7f9e40ddf9f341b3dc9ba860af7e0ca7ca7e
9eecd0084d19c',
"cnonce" : h'd36b581d1eef9c7c,
"client_cred_verify" : SIG
}
}
Figure 5: Authorization + Joining Request payload for a Publisher
{
"profile" : "coap_pubsub_app",
"kty" : "COSE_Key",
"key" : {1: 4, 2: h'1234', 3: 12, 5: h'1f389d14d17dc7',
-1: h'02e2cc3a9b92855220f255fff1c615bc'}
}
Figure 6: Authorization + Joining Response payload for a Publisher
5. Subscriber
In this section, it is specified how the Subscriber retrieves the
keying material to protect the publication.
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+----------------+
| |
| Authorization |
| Server 2 |
| |
+----------------+
^
|
+-----(D)------+
|
v
+------------+
| CoAP |
| Client - |
| |
| Subscriber |
| |
+------------+
Figure 7: Phase 2: Subscriber side
Step (D) between Subscriber and AS2 corresponds to the retrieval of
the keying material to verify the publication end-to-end with the
publishers (see Section 6.1). The details are defined in Section 3.1
This step is the same as (B) between Publisher and AS2 (Section 3.1),
with the following differences:
o The Authorization + Joining Request MUST NOT contain the
'client_cred parameter', the role element in the 'scope' parameter
MUST be set to "subscriber". The Subscriber MUST have access to
the public keys of all the Publishers; this MAY be achieved in the
Authorization + Joining Request by using the parameter
'get_pub_keys' set to empty array.
o The Authorization + Key Distribution Response MUST contain the
'pub_keys' parameter.
An example of the payload of an Authorization + Joining Request and
corresponding Response for a Subscriber is specified in Figure 8 and
Figure 9.
{
"scope" : ["Broker1/Temp", "subscriber"],
"get_pub_keys" : [ ]
}
Figure 8: Authorization + Joining Request payload for a Subscriber
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{
"profile" : "coap_pubsub_app",
"scope" : ["Broker1/Temp", "subscriber"],
"kty" : "COSE_Key"
"key" : {1: 4, 2: h'1234', 3: 12, 5: h'1f389d14d17dc7',
-1: h'02e2cc3a9b92855220f255fff1c615bc'},
"pub_keys" : [
{
1 : 2, / type EC2 /
2 : h'11', / kid /
3 : -7, / alg ECDSA with SHA-256 /
-1 : 1 , / crv P-256 /
-2 : h'65eda5a12577c2bae829437fe338701a10aaa375e1bb5b5de108de43
9c08551d', / x /
-3 : h'1e52ed75701163f7f9e40ddf9f341b3dc9ba860af7e0ca7ca7e9eecd
0084d19c' / y /
}
]
}
Figure 9: Authorization + Joining Response payload for a Subscriber
6. Pub-Sub Protected Communication
This section specifies the communication Publisher-Broker and
Subscriber-Broker, after the previous phases have taken place. The
operations of publishing and subscribing are defined in
[I-D.ietf-core-coap-pubsub].
+------------+ +------------+ +------------+
| CoAP | | CoAP | | CoAP |
| Client - | | Server - | | Client - |
| | ----(E)---> | | | |
| Publisher | | Broker | <----(F)---- | Subscriber |
| | | | -----(G)---> | |
+------------+ +------------+ +------------+
Figure 10: Phase 3: Secure communication between Publisher and
Subscriber
The (E) message corresponds to the publication of a topic on the
Broker. The publication (the resource representation) is protected
with COSE ([RFC8152]). The (F) message is the subscription of the
Subscriber, which is unprotected, unless a profile of ACE
[I-D.ietf-ace-oauth-authz] is used between Subscriber and Broker.
The (G) message is the response from the Broker, where the
publication is protected with COSE.
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The flow graph is presented below.
Publisher Broker Subscriber
| --- PUT /topic ----> | |
| protected with COSE | |
| | <--- GET /topic ----- |
| | |
| | ---- response ------> |
| | protected with COSE |
Figure 11: (E), (F), (G): Example of protected communication
6.1. Using COSE Objects To Protect The Resource Representation
The Publisher uses the symmetric COSE Key received from AS2 in
exchange B (Section 3.1) to protect the payload of the PUBLISH
operation (Section 4.3 of [I-D.ietf-core-coap-pubsub]).
Specifically, the COSE Key is used to create a COSE_Encrypt0 with
algorithm specified by AS2. The Publisher uses the private key
corresponding to the public key sent to the AS2 in exchange B
(Section 3.1) to countersign the COSE Object as specified in
Section 4.5 of [RFC8152]. The CoAP payload is replaced by the COSE
object before the publication is sent to the Broker.
The Subscriber uses the kid in the countersignature field in the COSE
object to retrieve the right public key to verify the
countersignature. It then uses the symmetric key received from AS2
to verify and decrypt the publication received in the payload of the
CoAP Notification from the Broker.
The COSE object is constructed in the following way:
o The protected Headers (as described in Section 3 of [RFC8152]) MAY
contain the kid parameter, with value the kid of the symmetric
COSE Key received in Section 3.1 and MUST contain the content
encryption algorithm.
o The unprotected Headers MUST contain the Partial IV, with value a
sequence number that is incremented for every message sent, and
the counter signature that includes:
* the algorithm (same value as in the asymmetric COSE Key
received in (B)) in the protected header;
* the kid (same value as the kid of the asymmetric COSE Key
received in (B)) in the unprotected header;
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* the signature computed as specified in Section 4.5 of
[RFC8152].
o The ciphertext, computed over the plaintext that MUST contain the
CoAP payload.
The external_aad is an empty string.
An example is given in Figure 12
16(
[
/ protected / h'a2010c04421234' / {
\ alg \ 1:12, \ AES-CCM-64-64-128 \
\ kid \ 4: h'1234'
} / ,
/ unprotected / {
/ iv / 5:h'89f52f65a1c580',
/ countersign / 7:[
/ protected / h'a10126' / {
\ alg \ 1:-7
} / ,
/ unprotected / {
/ kid / 4:h'11'
},
/ signature / SIG / 64 bytes signature /
]
},
/ ciphertext / h'8df0a3b62fccff37aa313c8020e971f8aC8d'
]
)
Figure 12: Example of COSE Object sent in the payload of a PUBLISH
operation
The encryption and decryption operations are described in sections
5.3 and 5.4 of [RFC8152].
7. Security Considerations
In the profile described above, the Publisher and Subscriber use
asymmetric crypto, which would make the message exchange quite heavy
for small constrained devices. Moreover, all Subscribers must be
able to access the public keys of all the Publishers to a specific
topic to be able to verify the publications. Such a database could
be set up and managed by the same entity having control of the topic,
i.e. AS2.
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An application where it is not critical that only authorized
Publishers can publish on a topic may decide not to make use of the
asymmetric crypto and only use symmetric encryption/MAC to
confidentiality and integrity protect the publication, but this is
not recommended since, as a result, any authorized Subscribers with
access to the Broker may forge unauthorized publications without
being detected. In this symmetric case the Subscribers would only
need one symmetric key per topic, and would not need to know any
information about the Publishers, that can be anonymous to it and the
Broker.
Subscribers can be excluded from future publications through re-
keying for a certain topic. This could be set up to happen on a
regular basis, for certain applications. How this could be done is
out of scope for this work.
The Broker is only trusted with verifying that the Publisher is
authorized to publish, but is not trusted with the publications
itself, which it cannot read nor modify. In this setting, caching of
publications on the Broker is still allowed.
TODO: expand on security and privacy considerations
8. IANA Considerations
8.1. ACE Groupcomm Profile Registry
The following registrations are done for the "ACE Groupcomm Profile"
Registry following the procedure specified in
[I-D.ietf-ace-key-groupcomm].
Note to RFC Editor: Please replace all occurrences of "[[This
document]]" with the RFC number of this specification and delete this
paragraph.
Name: coap_pubsub_app
Description: Profile for delegating client authentication and
authorization for publishers and subscribers in a pub-sub setting
scenario in a constrained environment.
CBOR Key: TBD
Reference: [[This document]]
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8.2. ACE Groupcomm Key Registry
The following registrations are done for the ACE Groupcomm Key
Registry following the procedure specified in
[I-D.ietf-ace-key-groupcomm].
Note to RFC Editor: Please replace all occurrences of "[[This
document]]" with the RFC number of this specification and delete this
paragraph.
Name: COSE_Key
Key Type Value: TBD
Profile: coap_pubsub_app
Description: COSE_Key object
References: [RFC8152], [[This document]]
9. References
9.1. Normative References
[I-D.ietf-ace-key-groupcomm]
Palombini, F. and M. Tiloca, "Key Provisioning for Group
Communication using ACE", draft-ietf-ace-key-groupcomm-03
(work in progress), November 2019.
[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-25
(work in progress), October 2019.
[I-D.ietf-core-coap-pubsub]
Koster, M., Keranen, A., and J. Jimenez, "Publish-
Subscribe Broker for the Constrained Application Protocol
(CoAP)", draft-ietf-core-coap-pubsub-09 (work in
progress), September 2019.
[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>.
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[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>.
[RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)",
RFC 8152, DOI 10.17487/RFC8152, July 2017,
<https://www.rfc-editor.org/info/rfc8152>.
9.2. Informative References
[I-D.ietf-ace-actors]
Gerdes, S., Seitz, L., Selander, G., and C. Bormann, "An
architecture for authorization in constrained
environments", draft-ietf-ace-actors-07 (work in
progress), October 2018.
[I-D.ietf-ace-dtls-authorize]
Gerdes, S., Bergmann, O., Bormann, C., Selander, G., and
L. Seitz, "Datagram Transport Layer Security (DTLS)
Profile for Authentication and Authorization for
Constrained Environments (ACE)", draft-ietf-ace-dtls-
authorize-08 (work in progress), April 2019.
[I-D.ietf-ace-oscore-profile]
Palombini, F., Seitz, L., Selander, G., and M. Gunnarsson,
"OSCORE profile of the Authentication and Authorization
for Constrained Environments Framework", draft-ietf-ace-
oscore-profile-08 (work in progress), July 2019.
Appendix A. Requirements on Application Profiles
This section lists the specifications on this profile based on the
requirements defined in Appendix A of [I-D.ietf-ace-key-groupcomm]
o REQ1: Specify the encoding and value of the identifier of group or
topic of 'scope': see Section 3.1).
o REQ2: Specify the encoding and value of roles of 'scope': see
Section 3.1).
o REQ3: Optionally, specify the acceptable values for 'sign_alg':
TODO
o REQ4: Optionally, specify the acceptable values for
'sign_parameters': TODO
o REQ5: Optionally, specify the acceptable values for
'sign_key_parameters': TODO
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o REQ6: Optionally, specify the acceptable values for 'pub_key_enc':
TODO
o REQ7: Specify the exact format of the 'key' value: COSE_Key, see
Section 3.1.
o REQ8: Specify the acceptable values of 'kty' : "COSE_Key", see
Section 3.1.
o REQ9: Specity the format of the identifiers of group members: TODO
o REQ10: Optionally, specify the format and content of
'group_policies' entries: not defined
o REQ11: Specify the communication protocol the members of the group
must use: CoAP pub/sub.
o REQ12: Specify the security protocol the group members must use to
protect their communication. This must provide encryption,
integrity and replay protection: Object Security of Content using
COSE, see Section 6.1.
o REQ13: Specify and register the application profile identifier :
"coap_pubsub_app", see Section 8.1.
o REQ14: Optionally, specify the encoding of public keys, of
'client_cred', and of 'pub_keys' if COSE_Keys are not used: NA.
o REQ15: Specify policies at the KDC to handle id that are not
included in get_pub_keys: TODO
o REQ16: Specify the format and content of 'group_policies': TODO
o REQ17: Specify the format of newly-generated individual keying
material for group members, or of the information to derive it,
and corresponding CBOR label : not defined
o REQ18: Specify how the communication is secured between Client and
KDC. Optionally, specify tranport profile of ACE
[I-D.ietf-ace-oauth-authz] to use between Client and KDC: pre-set,
as KDC is AS.
o OPT1: Optionally, specify the encoding of public keys, of
'client_cred', and of 'pub_keys' if COSE_Keys are not used: NA
o OPT2: Optionally, specify the negotiation of parameter values for
signature algorithm and signature keys, if 'sign_info' and
'pub_key_enc' are not used: NA
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o OPT3: Optionally, specify the format and content of
'mgt_key_material': not defined
o OPT4: Optionally, specify policies that instruct clients to retain
unsuccessfully decrypted messages and for how long, so that they
can be decrypted after getting updated keying material: not
defined
Acknowledgments
The author wishes to thank Ari Keraenen, John Mattsson, Ludwig Seitz,
Goeran Selander, Jim Schaad and Marco Tiloca for the useful
discussion and reviews that helped shape this document.
Author's Address
Francesca Palombini
Ericsson
Email: francesca.palombini@ericsson.com
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