draft-ietf-ace-pubsub-profile-01.txt		draft-ietf-ace-pubsub-profile-02.txt
	ACE Working Group F. Palombini		ACE Working Group F. Palombini
	Internet-Draft Ericsson		Internet-Draft Ericsson
	Intended status: Standards Track July 03, 2020		Intended status: Standards Track C. Sengul
	Expires: January 4, 2021		Expires: 7 July 2021 Brunel University
			3 January 2021
	Pub-Sub Profile for Authentication and Authorization for Constrained		Pub-Sub Profile for Authentication and Authorization for Constrained
	Environments (ACE)		Environments (ACE)
	draft-ietf-ace-pubsub-profile-01		draft-ietf-ace-pubsub-profile-02
	Abstract		Abstract
	This specification defines an application profile for authentication		This specification defines an application profile for authentication
	and authorization for publishers and subscribers in a pub-sub setting		and authorization for publishers and subscribers in a pub-sub setting
	scenario in a constrained environment, using the ACE framework. This		scenario in a constrained environment, using the ACE framework. This
	profile relies on transport layer or application layer security to		profile relies on transport layer or application layer security to
	authorize the publisher to the broker. Moreover, it relies on		authorize the publisher to the broker. Moreover, it relies on
	application layer security for publisher-broker and subscriber-broker		application layer security for publisher-broker and subscriber-broker
	communication.		communication.
			Note to Readers
			Source for this draft and an issue tracker can be found at
			https://github.com/ace-wg/pubsub-profile (https://github.com/ace-wg/
			pubsub-profile).
	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 https://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
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	This Internet-Draft will expire on January 4, 2021.		This Internet-Draft will expire on 7 July 2021.
	Copyright Notice		Copyright Notice
	Copyright (c) 2020 IETF Trust and the persons identified as the		Copyright (c) 2021 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. Application Profile Overview . . . . . . . . . . . . . . . . 3		2. Application Profile Overview . . . . . . . . . . . . . . . . 3
	3. PubSub Application Profiles . . . . . . . . . . . . . . . . . 5		3. PubSub Application Profiles . . . . . . . . . . . . . . . . . 5
	3.1. Retrieval of COSE Key for protection of content . . . . . 6		3.1. Retrieval of COSE Key for protection of content . . . . . 6
	3.2. coap_pubsub_app Application Profile . . . . . . . . . . . 9		3.2. coap_pubsub_app Application Profile . . . . . . . . . . . 9
	3.3. mqtt_pubsub_app Application Profile . . . . . . . . . . . 9		3.3. mqtt_pubsub_app Application Profile . . . . . . . . . . . 9
	4. Publisher . . . . . . . . . . . . . . . . . . . . . . . . . . 9		4. Publisher . . . . . . . . . . . . . . . . . . . . . . . . . . 9
	4.1. CoAP Publisher . . . . . . . . . . . . . . . . . . . . . 11		4.1. CoAP Publisher . . . . . . . . . . . . . . . . . . . . . 11
	4.2. MQTT Publisher . . . . . . . . . . . . . . . . . . . . . 12		4.2. MQTT Publisher . . . . . . . . . . . . . . . . . . . . . 11
	5. Subscriber . . . . . . . . . . . . . . . . . . . . . . . . . 12		5. Subscriber . . . . . . . . . . . . . . . . . . . . . . . . . 12
	5.1. CoAP Subscriber . . . . . . . . . . . . . . . . . . . . . 13		5.1. CoAP Subscriber . . . . . . . . . . . . . . . . . . . . . 12
	5.2. MQTT Subscriber . . . . . . . . . . . . . . . . . . . . . 13		5.2. MQTT Subscriber . . . . . . . . . . . . . . . . . . . . . 13
	6. Pub-Sub Protected Communication . . . . . . . . . . . . . . . 13		6. Pub-Sub Protected Communication . . . . . . . . . . . . . . . 13
	6.1. Using COSE Objects To Protect The Resource Representation 14		6.1. Using COSE Objects To Protect The Resource
			Representation . . . . . . . . . . . . . . . . . . . . . 14
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 16		7. Security Considerations . . . . . . . . . . . . . . . . . . . 16
	8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17		8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
	8.1. ACE Groupcomm Profile Registry . . . . . . . . . . . . . 17		8.1. ACE Groupcomm Profile Registry . . . . . . . . . . . . . 16
	8.1.1. CoAP Profile Registration . . . . . . . . . . . . . . 17		8.1.1. CoAP Profile Registration . . . . . . . . . . . . . . 17
	8.1.2. CoAP Profile Registration . . . . . . . . . . . . . . 17		8.1.2. CoAP Profile Registration . . . . . . . . . . . . . . 17
	8.2. ACE Groupcomm Key Registry . . . . . . . . . . . . . . . 18		8.2. ACE Groupcomm Key Registry . . . . . . . . . . . . . . . 17
	9. References . . . . . . . . . . . . . . . . . . . . . . . . . 18		9. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
	9.1. Normative References . . . . . . . . . . . . . . . . . . 18		9.1. Normative References . . . . . . . . . . . . . . . . . . 17
	9.2. Informative References . . . . . . . . . . . . . . . . . 19		9.2. Informative References . . . . . . . . . . . . . . . . . 18
	Appendix A. Requirements on Application Profiles . . . . . . . . 19		Appendix A. Requirements on Application Profiles . . . . . . . . 19
	Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 21		Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 21
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 21		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
	1. Introduction		1. Introduction
	The publisher-subscriber setting allows for devices with limited		The publisher-subscriber setting allows for devices with limited
	reachability to communicate via a broker that enables store-and-		reachability to communicate via a broker that enables store-and-
	forward messaging between the devices. The pub-sub scenario using		forward messaging between the devices. The pub-sub scenario using
	the Constrained Application Protocol (CoAP) is specified in		the Constrained Application Protocol (CoAP) is specified in
	[I-D.ietf-core-coap-pubsub], while the one using MQTT is specified in		[I-D.ietf-core-coap-pubsub], while the one using MQTT is specified in
	REF MQTT. This document defines a way to authorize nodes in a CoAP		REF MQTT. This document defines a way to authorize nodes in a CoAP
	pub-sub type of setting, using the ACE framework		pub-sub type of setting, using the ACE framework
	skipping to change at page 6, line 27 ¶		skipping to change at page 6, line 33 ¶
	| |		| |
	| [------ Pub Key Format Negociation Request --->] |		| [------ Pub Key Format Negociation Request --->] |
	| |		| |
	| [<---- Pub Key Format Negociation Response ----] |		| [<---- Pub Key Format Negociation Response ----] |
	| |		| |
	| -- Authorization + Key Distribution Request ---> |		| -- Authorization + Key Distribution Request ---> |
	| |		| |
	| <-- Authorization + Key Distribution Response -- |		| <-- Authorization + Key Distribution Response -- |
	| |		| |
	Figure 2: B: Access request - response		Figure 2: B: Access request - response
	Complementary to what is defined in [I-D.ietf-ace-oauth-authz]		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		(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		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		of the topic back to the Client in the 'AS' parameter in the AS
	Information, as a response to an Unauthorized Resource Request		Information, as a response to an Unauthorized Resource Request
	(Section 5.1.2). The uri of AS2 is concatenated to the uri of AS1,		(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		and separated by a comma. An example using CBOR diagnostic notation
	and CoAP is given below:		and CoAP is given below:
	4.01 Unauthorized		4.01 Unauthorized
	Content-Format: application/ace+cbor		Content-Format: application/ace+cbor
	{"AS": "coaps://as1.example.com/token,		{"AS": "coaps://as1.example.com/token,
	coaps://as2.example.com/pubsubkey"}		coaps://as2.example.com/pubsubkey"}
	Figure 3: AS1, AS2 Information example		Figure 3: AS1, AS2 Information example
	After retrieving the AS2 address, the Client MAY send a request to		After retrieving the AS2 address, the Client MAY send a request to
	the AS, in order to retrieve necessary information concerning the		the AS, in order to retrieve necessary information concerning the
	public keys in the group, as well as concerning the algorithm and		public keys in the group, as well as concerning the algorithm and
	related parameters for computing signatures in the group. This		related parameters for computing signatures in the group. This
	request is a subset of the Token POST request defined in Section 3.3		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		of [I-D.ietf-ace-key-groupcomm], specifically a CoAP POST request to
	a specific resource at the AS, including only the parameters		a specific resource at the AS, including only the parameters
	'sign_info' and 'pub_key_enc' in the CBOR map in the payload. The		'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		default url-path for this resource is /ace-group/gid/cs-info, where
	skipping to change at page 7, line 23 ¶		skipping to change at page 7, line 32 ¶
	which is an Authorization Request merged with a Joining Request, as		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		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		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		and the KDC, in this setting, so the Authorization Response and the
	Post Token message are not necessary.		Post Token message are not necessary.
	More specifically, the Client sends a POST request to the /ace-group/		More specifically, the Client sends a POST request to the /ace-group/
	gid endpoint on AS2, with Content-Format = "application/ace+cbor"		gid endpoint on AS2, with Content-Format = "application/ace+cbor"
	that MUST contain in the payload (formatted as a CBOR map):		that MUST contain in the payload (formatted as a CBOR map):
	o the following fields from the Joining Request (Section 4.2 of		* the following fields from the Joining Request (Section 4.2 of
	[I-D.ietf-ace-key-groupcomm]):		[I-D.ietf-ace-key-groupcomm]):
	* 'scope' parameter set to a CBOR array containing:		- 'scope' parameter set to a CBOR array containing:
	+ the broker's topic as first element, and		o the broker's topic as first element, and
	+ the text string "publisher" if the client request to be a		o the text string "publisher" if the client request to be a
	publisher, "subscriber" 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		subscriber, or a CBOR array containing both, if the client
	request to be both.		request to be both.
	* 'get_pub_keys' parameter set to the empty array if the Client		- 'get_pub_keys' parameter set to the empty array if the Client
	needs to retrieve the public keys of the other pubsub members,		needs to retrieve the public keys of the other pubsub members,
	* 'client_cred' parameter containing the Client's public key		- 'client_cred' parameter containing the Client's public key
	formatted as a COSE_Key, if the Client needs to directly send		formatted as a COSE_Key, if the Client needs to directly send
	that to the AS2,		that to the AS2,
	* 'cnonce', set to a 8 bytes long pseudo-random nonce, if		- 'cnonce', set to a 8 bytes long pseudo-random nonce, if
	'client_cred' is present,		'client_cred' is present,
	* 'client_cred_verify', set to a singature computed over the		- 'client_cred_verify', set to a singature computed over the
	rsnonce concatenated with cnonce, if 'client_cred' is present,		rsnonce concatenated with cnonce, if 'client_cred' is present,
	* OPTIONALLY, if needed, the 'pub_keys_repos' parameter		- OPTIONALLY, if needed, the 'pub_keys_repos' parameter
	o the following fields from the Authorization Request (Section 3.1		* the following fields from the Authorization Request (Section 3.1
	of [I-D.ietf-ace-key-groupcomm]):		of [I-D.ietf-ace-key-groupcomm]):
	* OPTIONALLY, if needed, additional parameters such as		- OPTIONALLY, if needed, additional parameters such as
	'client_id'		'client_id'
	TODO: 'cnonce' might change name. TODO: register media type ace+json		TODO: 'cnonce' might change name. TODO: register media type ace+json
	for HTTP?		for HTTP?
	Note that the alg parameter in the 'client_cred' COSE_Key MUST be a		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		signing algorithm, as defined in section 8 of [RFC8152], and that it
	is the same algorithm used to compute the signature sent in		is the same algorithm used to compute the signature sent in
	'client_cred_verify'.		'client_cred_verify'.
	skipping to change at page 8, line 27 ¶		skipping to change at page 8, line 35 ¶
	specified in Figure 5 and Figure 8.		specified in Figure 5 and Figure 8.
	The AS2 verifies that the Client is authorized to access the topic		The AS2 verifies that the Client is authorized to access the topic
	and, if the 'client_cred' parameter is present, stores the public key		and, if the 'client_cred' parameter is present, stores the public key
	of the Client.		of the Client.
	The AS2 response is an Authorization + Joining Response, with		The AS2 response is an Authorization + Joining Response, with
	Content-Format = "application/ace+cbor". The payload (formatted as a		Content-Format = "application/ace+cbor". The payload (formatted as a
	CBOR map) MUST contain:		CBOR map) MUST contain:
	o the following fields from the Joining Response (Section 4.2 of		* the following fields from the Joining Response (Section 4.2 of
	[I-D.ietf-ace-key-groupcomm]):		[I-D.ietf-ace-key-groupcomm]):
	* 'kty' identifies a key type "COSE_Key", as defined in		- 'kty' identifies a key type "COSE_Key", as defined in
	Section 8.2.		Section 8.2.
	* 'key', which contains a "COSE_Key" object (defined in		- 'key', which contains a "COSE_Key" object (defined in
	[RFC8152], containing:		[RFC8152], containing:
	+ 'kty' with value 4 (symmetric)		o 'kty' with value 4 (symmetric)
	+ 'alg' with value defined by the AS2 (Content Encryption		o 'alg' with value defined by the AS2 (Content Encryption
	Algorithm)		Algorithm)
	+ 'Base IV' with value defined by the AS2		o 'Base IV' with value defined by the AS2
	+ 'k' with value the symmetric key value
	+ OPTIONALLY, 'kid' with an identifier for the key value		o 'k' with value the symmetric key value
			o OPTIONALLY, 'kid' with an identifier for the key value
	* OPTIONALLY, 'exp' with the expiration time of the key		- OPTIONALLY, 'exp' with the expiration time of the key
	* 'pub_keys', containing the public keys of all authorized		- 'pub_keys', containing the public keys of all authorized
	signing members formatted as COSE_Keys, if the 'get_pub_keys'		signing members formatted as COSE_Keys, if the 'get_pub_keys'
	parameter was present and set to the empty array in the		parameter was present and set to the empty array in the
	Authorization + Key Distribution Request		Authorization + Key Distribution Request
	o the following fields from the Authorization Response (Section 3.2		* the following fields from the Authorization Response (Section 3.2
	of [I-D.ietf-ace-key-groupcomm]):		of [I-D.ietf-ace-key-groupcomm]):
	* 'profile' set to the corresponding value, see Section 3.2 or		- 'profile' set to the corresponding value, see Section 3.2 or
	Section 3.3		Section 3.3
	* OPTIONALLY 'scope', set to a CBOR array containing:		- OPTIONALLY 'scope', set to a CBOR array containing:
	+ the broker's topic as first element, and		o the broker's topic as first element, and
	+ the string "publisher" if the client is an authorized		o the string "publisher" if the client is an authorized
	publisher, "subscriber" if the client is an authorized		publisher, "subscriber" if the client is an authorized
	subscriber, or a CBOR array containing both, if the client		subscriber, or a CBOR array containing both, if the client
	is authorized to be both.		is authorized to be both.
	Examples for the response payload are detailed in Figure 6 and		Examples for the response payload are detailed in Figure 6 and
	Figure 9.		Figure 9.
	3.2. coap_pubsub_app Application Profile		3.2. coap_pubsub_app Application Profile
	In case CoAP PubSub is used as communication protocol:		In case CoAP PubSub is used as communication protocol:
	o 'profile' set to "coap_pubsub_app", as specified in Section 8.1.1.		* 'profile' set to "coap_pubsub_app", as specified in Section 8.1.1.
	3.3. mqtt_pubsub_app Application Profile		3.3. mqtt_pubsub_app Application Profile
	In case mQTT PubSub is used as communication protocol:		In case mQTT PubSub is used as communication protocol:
	o 'profile' set to "mqtt_pubsub_app", as specified in Section 8.1.2.		* 'profile' set to "mqtt_pubsub_app", as specified in Section 8.1.2.
	4. Publisher		4. Publisher
	In this section, it is specified how the Publisher requests, obtains		In this section, it is specified how the Publisher requests, obtains
	and communicates to the Broker the access token, as well as the		and communicates to the Broker the access token, as well as the
	retrieval of the keying material to protect the publication.		retrieval of the keying material to protect the publication.
	+----------------+ +----------------+		+----------------+ +----------------+
	| | | |		| | | |
	| Authorization | | Authorization |		| Authorization | | Authorization |
	skipping to change at page 10, line 27 ¶		skipping to change at page 10, line 27 ¶
	| | ----(C)---> | |		| | ----(C)---> | |
	| Publisher | | Broker |		| Publisher | | Broker |
	| | | |		| | | |
	| | | |		| | | |
	+------------+ +------------+		+------------+ +------------+
	Figure 4: Phase 1: Publisher side		Figure 4: Phase 1: Publisher side
	This is a combination of two independent phases:		This is a combination of two independent phases:
	o one is the establishment of a secure connection between Publisher		* one is the establishment of a secure connection between Publisher
	and Broker, using an ACE transport profile such as DTLS		and Broker, using an ACE transport profile such as DTLS
	[I-D.ietf-ace-dtls-authorize], OSCORE		[I-D.ietf-ace-dtls-authorize], OSCORE
	[I-D.ietf-ace-oscore-profile] or REF MQTT Profile. (A)(C)		[I-D.ietf-ace-oscore-profile] or REF MQTT Profile. (A)(C)
	o the other is the Publisher's retrieval of keying material to		* the other is the Publisher's retrieval of keying material to
	protect the publication. (B)		protect the publication. (B)
	In detail:		In detail:
	(A) corresponds to the Access Token Request and Response between		(A) corresponds to the Access Token Request and Response between
	Publisher and Authorization Server to retrieve the Access Token and		Publisher and Authorization Server to retrieve the Access Token and
	RS (Broker) Information. As specified, the Publisher has the role of		RS (Broker) Information. As specified, the Publisher has the role of
	a CoAP client, the Broker has the role of the CoAP server.		a CoAP client, the Broker has the role of the CoAP server.
	(C) corresponds to the exchange between Publisher and Broker, where		(C) corresponds to the exchange between Publisher and Broker, where
	skipping to change at page 11, line 47 ¶		skipping to change at page 11, line 47 ¶
	Figure 5: Authorization + Joining Request payload for a Publisher		Figure 5: Authorization + Joining Request payload for a Publisher
	{		{
	"profile" : "coap_pubsub_app",		"profile" : "coap_pubsub_app",
	"kty" : "COSE_Key",		"kty" : "COSE_Key",
	"key" : {1: 4, 2: h'1234', 3: 12, 5: h'1f389d14d17dc7',		"key" : {1: 4, 2: h'1234', 3: 12, 5: h'1f389d14d17dc7',
	-1: h'02e2cc3a9b92855220f255fff1c615bc'}		-1: h'02e2cc3a9b92855220f255fff1c615bc'}
	}		}
	Figure 6: Authorization + Joining Response payload for a Publisher		Figure 6: Authorization + Joining Response payload for a Publisher
	4.2. MQTT Publisher		4.2. MQTT Publisher
	TODO		TODO
	5. Subscriber		5. Subscriber
	In this section, it is specified how the Subscriber retrieves the		In this section, it is specified how the Subscriber retrieves the
	keying material to protect the publication.		keying material to protect the publication.
	skipping to change at page 12, line 32 ¶		skipping to change at page 12, line 28 ¶
	+-----(D)------+		+-----(D)------+
	|		|
	v		v
	+------------+		+------------+
	| |		| |
	| Subscriber |		| Subscriber |
	| |		| |
	| |		| |
	+------------+		+------------+
	Figure 7: Phase 2: Subscriber side		Figure 7: Phase 2: Subscriber side
	Step (D) between Subscriber and AS2 corresponds to the retrieval of		Step (D) between Subscriber and AS2 corresponds to the retrieval of
	the keying material to verify the publication end-to-end with the		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		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),		This step is the same as (B) between Publisher and AS2 (Section 3.1),
	with the following differences:		with the following differences:
	o The Authorization + Joining Request MUST NOT contain the		* The Authorization + Joining Request MUST NOT contain the
	'client_cred parameter', the role element in the 'scope' parameter		'client_cred parameter', the role element in the 'scope' parameter
	MUST be set to "subscriber". The Subscriber MUST have access to		MUST be set to "subscriber". The Subscriber MUST have access to
	the public keys of all the Publishers; this MAY be achieved in the		the public keys of all the Publishers; this MAY be achieved in the
	Authorization + Joining Request by using the parameter		Authorization + Joining Request by using the parameter
	'get_pub_keys' set to empty array.		'get_pub_keys' set to empty array.
	o The Authorization + Key Distribution Response MUST contain the		* The Authorization + Key Distribution Response MUST contain the
	'pub_keys' parameter.		'pub_keys' parameter.
	5.1. CoAP Subscriber		5.1. CoAP Subscriber
	An example of the payload of an Authorization + Joining Request and		An example of the payload of an Authorization + Joining Request and
	corresponding Response for a CoAP Subscriber using CoAP and CBOR is		corresponding Response for a CoAP Subscriber using CoAP and CBOR is
	specified in Figure 8 and Figure 9.		specified in Figure 8 and Figure 9.
	{		{
	"scope" : ["Broker1/Temp", "subscriber"],		"scope" : ["Broker1/Temp", "subscriber"],
	"get_pub_keys" : [ ]		"get_pub_keys" : [ ]
	}		}
	Figure 8: Authorization + Joining Request payload for a Subscriber		Figure 8: Authorization + Joining Request payload for a Subscriber
	{		{
	"profile" : "coap_pubsub_app",		"profile" : "coap_pubsub_app",
	"scope" : ["Broker1/Temp", "subscriber"],		"scope" : ["Broker1/Temp", "subscriber"],
	"kty" : "COSE_Key"		"kty" : "COSE_Key"
	"key" : {1: 4, 2: h'1234', 3: 12, 5: h'1f389d14d17dc7',		"key" : {1: 4, 2: h'1234', 3: 12, 5: h'1f389d14d17dc7',
	-1: h'02e2cc3a9b92855220f255fff1c615bc'},		-1: h'02e2cc3a9b92855220f255fff1c615bc'},
	"pub_keys" : [		"pub_keys" : [
	{		{
	1 : 2, / type EC2 /		1 : 2, / type EC2 /
	skipping to change at page 14, line 11 ¶		skipping to change at page 14, line 4 ¶
	Subscriber-Broker, after the previous phases have taken place. The		Subscriber-Broker, after the previous phases have taken place. The
	operations of publishing and subscribing are defined in		operations of publishing and subscribing are defined in
	[I-D.ietf-core-coap-pubsub].		[I-D.ietf-core-coap-pubsub].
	+------------+ +------------+ +------------+		+------------+ +------------+ +------------+
	| | | | | |		| | | | | |
	| Publisher | ----(E)---> | Broker | | Subscriber |		| Publisher | ----(E)---> | Broker | | Subscriber |
	| | | | <----(F)---- | |		| | | | <----(F)---- | |
	| | | | -----(G)---> | |		| | | | -----(G)---> | |
	+------------+ +------------+ +------------+		+------------+ +------------+ +------------+
			Figure 10: Phase 3: Secure communication between Publisher and
	Figure 10: Phase 3: Secure communication between Publisher and		Subscriber
	Subscriber
	The (E) message corresponds to the publication of a topic on the		The (E) message corresponds to the publication of a topic on the
	Broker. The publication (the resource representation) is protected		Broker. The publication (the resource representation) is protected
	with COSE ([RFC8152]). The (F) message is the subscription of the		with COSE ([RFC8152]). The (F) message is the subscription of the
	Subscriber, which is unprotected, unless a profile of ACE		Subscriber, which is unprotected, unless a profile of ACE
	[I-D.ietf-ace-oauth-authz] is used between Subscriber and Broker.		[I-D.ietf-ace-oauth-authz] is used between Subscriber and Broker.
	The (G) message is the response from the Broker, where the		The (G) message is the response from the Broker, where the
	publication is protected with COSE.		publication is protected with COSE.
	The flow graph is presented below.		The flow graph is presented below.
	Publisher Broker Subscriber		Publisher Broker Subscriber
	| --- PUT /topic ----> | |		| --- PUT /topic ----> | |
	| protected with COSE | |		| protected with COSE | |
	| | <--- GET /topic ----- |		| | <--- GET /topic ----- |
	| | |		| | |
	| | ---- response ------> |		| | ---- response ------> |
	| | protected with COSE |		| | protected with COSE |
	Figure 11: (E), (F), (G): Example of protected communication		Figure 11: (E), (F), (G): Example of protected communication
	6.1. Using COSE Objects To Protect The Resource Representation		6.1. Using COSE Objects To Protect The Resource Representation
	The Publisher uses the symmetric COSE Key received from AS2 in		The Publisher uses the symmetric COSE Key received from AS2 in
	exchange B (Section 3.1) to protect the payload of the PUBLISH		exchange B (Section 3.1) to protect the payload of the PUBLISH
	operation (Section 4.3 of [I-D.ietf-core-coap-pubsub] and REF MQTT).		operation (Section 4.3 of [I-D.ietf-core-coap-pubsub] and REF MQTT).
	Specifically, the COSE Key is used to create a COSE_Encrypt0 with		Specifically, the COSE Key is used to create a COSE_Encrypt0 with
	algorithm specified by AS2. The Publisher uses the private key		algorithm specified by AS2. The Publisher uses the private key
	corresponding to the public key sent to the AS2 in exchange B		corresponding to the public key sent to the AS2 in exchange B
	(Section 3.1) to countersign the COSE Object as specified in		(Section 3.1) to countersign the COSE Object as specified in
	skipping to change at page 15, line 7 ¶		skipping to change at page 14, line 47 ¶
	object before the publication is sent to the Broker.		object before the publication is sent to the Broker.
	The Subscriber uses the kid in the countersignature field in the COSE		The Subscriber uses the kid in the countersignature field in the COSE
	object to retrieve the right public key to verify the		object to retrieve the right public key to verify the
	countersignature. It then uses the symmetric key received from AS2		countersignature. It then uses the symmetric key received from AS2
	to verify and decrypt the publication received in the payload of the		to verify and decrypt the publication received in the payload of the
	CoAP Notification from the Broker.		CoAP Notification from the Broker.
	The COSE object is constructed in the following way:		The COSE object is constructed in the following way:
	o The protected Headers (as described in Section 3 of [RFC8152]) MAY		* The protected Headers (as described in Section 3 of [RFC8152]) MAY
	contain the kid parameter, with value the kid of the symmetric		contain the kid parameter, with value the kid of the symmetric
	COSE Key received in Section 3.1 and MUST contain the content		COSE Key received in Section 3.1 and MUST contain the content
	encryption algorithm.		encryption algorithm.
	o The unprotected Headers MUST contain the Partial IV, with value a		* The unprotected Headers MUST contain the Partial IV, with value a
	sequence number that is incremented for every message sent, and		sequence number that is incremented for every message sent, and
	the counter signature that includes:		the counter signature that includes:
	* the algorithm (same value as in the asymmetric COSE Key		- the algorithm (same value as in the asymmetric COSE Key
	received in (B)) in the protected header;		received in (B)) in the protected header;
	* the kid (same value as the kid of the asymmetric COSE Key		- the kid (same value as the kid of the asymmetric COSE Key
	received in (B)) in the unprotected header;		received in (B)) in the unprotected header;
	* the signature computed as specified in Section 4.5 of		- the signature computed as specified in Section 4.5 of
	[RFC8152].		[RFC8152].
	o The ciphertext, computed over the plaintext that MUST contain the		* The ciphertext, computed over the plaintext that MUST contain the
	CoAP payload.		CoAP payload.
	The external_aad is an empty string.		The external_aad is an empty string.
	An example is given in Figure 12		An example is given in Figure 12
	16(		16(
	[		[
	/ protected / h'a2010c04421234' / {		/ protected / h'a2010c04421234' / {
	\ alg \ 1:12, \ AES-CCM-64-64-128 \		\ alg \ 1:12, \ AES-CCM-64-64-128 \
	\ kid \ 4: h'1234'		\ kid \ 4: h'1234'
	} / ,		} / ,
	/ unprotected / {		/ unprotected / {
	/ iv / 5:h'89f52f65a1c580',		/ iv / 5:h'89f52f65a1c580',
	/ countersign / 7:[		/ countersign / 7:[
	/ protected / h'a10126' / {		/ protected / h'a10126' / {
	skipping to change at page 16, line 26 ¶		skipping to change at page 15, line 47 ¶
	/ unprotected / {		/ unprotected / {
	/ kid / 4:h'11'		/ kid / 4:h'11'
	},		},
	/ signature / SIG / 64 bytes signature /		/ signature / SIG / 64 bytes signature /
	]		]
	},		},
	/ ciphertext / h'8df0a3b62fccff37aa313c8020e971f8aC8d'		/ ciphertext / h'8df0a3b62fccff37aa313c8020e971f8aC8d'
	]		]
	)		)
	Figure 12: Example of COSE Object sent in the payload of a PUBLISH		Figure 12: Example of COSE Object sent in the payload of a
	operation		PUBLISH operation
	The encryption and decryption operations are described in sections		The encryption and decryption operations are described in sections
	5.3 and 5.4 of [RFC8152].		5.3 and 5.4 of [RFC8152].
	7. Security Considerations		7. Security Considerations
	In the profile described above, the Publisher and Subscriber use		In the profile described above, the Publisher and Subscriber use
	asymmetric crypto, which would make the message exchange quite heavy		asymmetric crypto, which would make the message exchange quite heavy
	for small constrained devices. Moreover, all Subscribers must be		for small constrained devices. Moreover, all Subscribers must be
	able to access the public keys of all the Publishers to a specific		able to access the public keys of all the Publishers to a specific
	skipping to change at page 18, line 31 ¶		skipping to change at page 18, line 7 ¶
	Description: COSE_Key object		Description: COSE_Key object
	References: [RFC8152], [[This document]]		References: [RFC8152], [[This document]]
	9. References		9. References
	9.1. Normative References		9.1. Normative References
	[I-D.ietf-ace-key-groupcomm]		[I-D.ietf-ace-key-groupcomm]
	Palombini, F. and M. Tiloca, "Key Provisioning for Group		Palombini, F. and M. Tiloca, "Key Provisioning for Group
	Communication using ACE", draft-ietf-ace-key-groupcomm-07		Communication using ACE", Work in Progress, Internet-
	(work in progress), June 2020.		Draft, draft-ietf-ace-key-groupcomm-10, 2 November 2020,
			<http://www.ietf.org/internet-drafts/draft-ietf-ace-key-
			groupcomm-10.txt>.
	[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) using the OAuth 2.0		Constrained Environments (ACE) using the OAuth 2.0
	Framework (ACE-OAuth)", draft-ietf-ace-oauth-authz-35		Framework (ACE-OAuth)", Work in Progress, Internet-Draft,
	(work in progress), June 2020.		draft-ietf-ace-oauth-authz-36, 16 November 2020,
			<http://www.ietf.org/internet-drafts/draft-ietf-ace-oauth-
			authz-36.txt>.
	[I-D.ietf-core-coap-pubsub]		[I-D.ietf-core-coap-pubsub]
	Koster, M., Keranen, A., and J. Jimenez, "Publish-		Koster, M., Keranen, A., and J. Jimenez, "Publish-
	Subscribe Broker for the Constrained Application Protocol		Subscribe Broker for the Constrained Application Protocol
	(CoAP)", draft-ietf-core-coap-pubsub-09 (work in		(CoAP)", Work in Progress, Internet-Draft, draft-ietf-
	progress), September 2019.		core-coap-pubsub-09, 30 September 2019,
			<http://www.ietf.org/internet-drafts/draft-ietf-core-coap-
			pubsub-09.txt>.
	[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,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",		[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
	RFC 6749, DOI 10.17487/RFC6749, October 2012,		RFC 6749, DOI 10.17487/RFC6749, October 2012,
	<https://www.rfc-editor.org/info/rfc6749>.		<https://www.rfc-editor.org/info/rfc6749>.
	skipping to change at page 19, line 22 ¶		skipping to change at page 19, line 8 ¶
	[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>.
	9.2. Informative References		9.2. Informative References
	[I-D.ietf-ace-actors]		[I-D.ietf-ace-actors]
	Gerdes, S., Seitz, L., Selander, G., and C. Bormann, "An		Gerdes, S., Seitz, L., Selander, G., and C. Bormann, "An
	architecture for authorization in constrained		architecture for authorization in constrained
	environments", draft-ietf-ace-actors-07 (work in		environments", Work in Progress, Internet-Draft, draft-
	progress), October 2018.		ietf-ace-actors-07, 22 October 2018, <http://www.ietf.org/
			internet-drafts/draft-ietf-ace-actors-07.txt>.
	[I-D.ietf-ace-dtls-authorize]		[I-D.ietf-ace-dtls-authorize]
	Gerdes, S., Bergmann, O., Bormann, C., Selander, G., and		Gerdes, S., Bergmann, O., Bormann, C., Selander, G., and
	L. Seitz, "Datagram Transport Layer Security (DTLS)		L. Seitz, "Datagram Transport Layer Security (DTLS)
	Profile for Authentication and Authorization for		Profile for Authentication and Authorization for
	Constrained Environments (ACE)", draft-ietf-ace-dtls-		Constrained Environments (ACE)", Work in Progress,
	authorize-11 (work in progress), June 2020.		Internet-Draft, draft-ietf-ace-dtls-authorize-14, 29
			October 2020, <http://www.ietf.org/internet-drafts/draft-
			ietf-ace-dtls-authorize-14.txt>.
	[I-D.ietf-ace-oscore-profile]		[I-D.ietf-ace-oscore-profile]
	Palombini, F., Seitz, L., Selander, G., and M. Gunnarsson,		Palombini, F., Seitz, L., Selander, G., and M. Gunnarsson,
	"OSCORE profile of the Authentication and Authorization		"OSCORE Profile of the Authentication and Authorization
	for Constrained Environments Framework", draft-ietf-ace-		for Constrained Environments Framework", Work in Progress,
	oscore-profile-11 (work in progress), June 2020.		Internet-Draft, draft-ietf-ace-oscore-profile-14, 14
			December 2020, <http://www.ietf.org/internet-drafts/draft-
			ietf-ace-oscore-profile-14.txt>.
	[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data		[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
	Interchange Format", STD 90, RFC 8259,		Interchange Format", STD 90, RFC 8259,
	DOI 10.17487/RFC8259, December 2017,		DOI 10.17487/RFC8259, December 2017,
	<https://www.rfc-editor.org/info/rfc8259>.		<https://www.rfc-editor.org/info/rfc8259>.
	Appendix A. Requirements on Application Profiles		Appendix A. Requirements on Application Profiles
	This section lists the specifications on this profile based on the		This section lists the specifications on this profile based on the
	requirements defined in Appendix A of [I-D.ietf-ace-key-groupcomm]		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		* REQ1: Specify the encoding and value of the identifier of group or
	topic of 'scope': see Section 3.1).		topic of 'scope': see Section 3.1).
	o REQ2: Specify the encoding and value of roles of 'scope': see		* REQ2: Specify the encoding and value of roles of 'scope': see
	Section 3.1).		Section 3.1).
	o REQ3: Optionally, specify the acceptable values for 'sign_alg':		* REQ3: Optionally, specify the acceptable values for 'sign_alg':
	TODO		TODO
	o REQ4: Optionally, specify the acceptable values for		* REQ4: Optionally, specify the acceptable values for
	'sign_parameters': TODO		'sign_parameters': TODO
	o REQ5: Optionally, specify the acceptable values for		* REQ5: Optionally, specify the acceptable values for
	'sign_key_parameters': TODO		'sign_key_parameters': TODO
	o REQ6: Optionally, specify the acceptable values for 'pub_key_enc':		* REQ6: Optionally, specify the acceptable values for 'pub_key_enc':
	TODO		TODO
	o REQ7: Specify the exact format of the 'key' value: COSE_Key, see		* REQ7: Specify the exact format of the 'key' value: COSE_Key, see
	Section 3.1.		Section 3.1.
	o REQ8: Specify the acceptable values of 'kty' : "COSE_Key", see		* REQ8: Specify the acceptable values of 'kty' : "COSE_Key", see
	Section 3.1.		Section 3.1.
	o REQ9: Specity the format of the identifiers of group members: TODO		* REQ9: Specity the format of the identifiers of group members: TODO
	o REQ10: Optionally, specify the format and content of		* REQ10: Optionally, specify the format and content of
	'group_policies' entries: not defined		'group_policies' entries: not defined
	o REQ11: Specify the communication protocol the members of the group		* REQ11: Specify the communication protocol the members of the group
	must use: CoAP pub/sub.		must use: CoAP pub/sub.
	o REQ12: Specify the security protocol the group members must use to		* REQ12: Specify the security protocol the group members must use to
	protect their communication. This must provide encryption,		protect their communication. This must provide encryption,
	integrity and replay protection: Object Security of Content using		integrity and replay protection: Object Security of Content using
	COSE, see Section 6.1.		COSE, see Section 6.1.
	o REQ13: Specify and register the application profile identifier :		* REQ13: Specify and register the application profile identifier :
	"coap_pubsub_app", see Section 8.1.		"coap_pubsub_app", see Section 8.1.
	o REQ14: Optionally, specify the encoding of public keys, of		* REQ14: Optionally, specify the encoding of public keys, of
	'client_cred', and of 'pub_keys' if COSE_Keys are not used: NA.		'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		* REQ15: Specify policies at the KDC to handle id that are not
	included in get_pub_keys: TODO		included in get_pub_keys: TODO
	o REQ16: Specify the format and content of 'group_policies': TODO		* REQ16: Specify the format and content of 'group_policies': TODO
	o REQ17: Specify the format of newly-generated individual keying		* REQ17: Specify the format of newly-generated individual keying
	material for group members, or of the information to derive it,		material for group members, or of the information to derive it,
	and corresponding CBOR label : not defined		and corresponding CBOR label : not defined
	o REQ18: Specify how the communication is secured between Client and		* REQ18: Specify how the communication is secured between Client and
	KDC. Optionally, specify tranport profile of ACE		KDC. Optionally, specify tranport profile of ACE
	[I-D.ietf-ace-oauth-authz] to use between Client and KDC: pre-set,		[I-D.ietf-ace-oauth-authz] to use between Client and KDC: pre-set,
	as KDC is AS.		as KDC is AS.
	o OPT1: Optionally, specify the encoding of public keys, of		* OPT1: Optionally, specify the encoding of public keys, of
	'client_cred', and of 'pub_keys' if COSE_Keys are not used: NA		'client_cred', and of 'pub_keys' if COSE_Keys are not used: NA
	o OPT2: Optionally, specify the negotiation of parameter values for		* OPT2: Optionally, specify the negotiation of parameter values for
	signature algorithm and signature keys, if 'sign_info' and		signature algorithm and signature keys, if 'sign_info' and
	'pub_key_enc' are not used: NA		'pub_key_enc' are not used: NA
	o OPT3: Optionally, specify the format and content of		* OPT3: Optionally, specify the format and content of
	'mgt_key_material': not defined		'mgt_key_material': not defined
	o OPT4: Optionally, specify policies that instruct clients to retain		* OPT4: Optionally, specify policies that instruct clients to retain
	unsuccessfully decrypted messages and for how long, so that they		unsuccessfully decrypted messages and for how long, so that they
	can be decrypted after getting updated keying material: not		can be decrypted after getting updated keying material: not
	defined		defined
	Acknowledgments		Acknowledgments
	The author wishes to thank Ari Keraenen, John Mattsson, Ludwig Seitz,		The author wishes to thank Ari Keraenen, John Mattsson, Ludwig Seitz,
	Goeran Selander, Cigdem Sengul, Jim Schaad and Marco Tiloca for the		Goeran Selander, Cigdem Sengul, Jim Schaad and Marco Tiloca for the
	useful discussion and reviews that helped shape this document.		useful discussion and reviews that helped shape this document.
	Author's Address		Authors' Addresses
	Francesca Palombini		Francesca Palombini
	Ericsson		Ericsson
	Email: francesca.palombini@ericsson.com		Email: francesca.palombini@ericsson.com
			Cigdem Sengul
			Brunel University
			Email: csengul@acm.org
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