rfc9203.original		rfc9203.txt
	ACE Working Group F. Palombini		Internet Engineering Task Force (IETF) F. Palombini
	Internet-Draft Ericsson AB		Request for Comments: 9203 Ericsson AB
	Intended status: Standards Track L. Seitz		Category: Standards Track L. Seitz
	Expires: 7 November 2021 Combitech		ISSN: 2070-1721 Combitech
	G. Selander		G. Selander
	Ericsson AB		Ericsson AB
	M. Gunnarsson		M. Gunnarsson
	RISE		RISE
	6 May 2021		March 2022
	OSCORE Profile of the Authentication and Authorization for Constrained		The Object Security for Constrained RESTful Environments (OSCORE)
	Environments Framework		Profile of the Authentication and Authorization for Constrained
	draft-ietf-ace-oscore-profile-19		Environments (ACE) Framework
	Abstract		Abstract
	This document specifies a profile for the Authentication and		This document specifies a profile for the Authentication and
	Authorization for Constrained Environments (ACE) framework. It		Authorization for Constrained Environments (ACE) framework. It
	utilizes Object Security for Constrained RESTful Environments		utilizes Object Security for Constrained RESTful Environments
	(OSCORE) to provide communication security and proof-of-possession		(OSCORE) to provide communication security and proof-of-possession
	for a key owned by the client and bound to an OAuth 2.0 access token.		for a key owned by the client and bound to an OAuth 2.0 access token.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This is an Internet Standards Track document.
	provisions of BCP 78 and BCP 79.
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	Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		This document is a product of the Internet Engineering Task Force
	and may be updated, replaced, or obsoleted by other documents at any		(IETF). It represents the consensus of the IETF community. It has
	time. It is inappropriate to use Internet-Drafts as reference		received public review and has been approved for publication by the
	material or to cite them other than as "work in progress."		Internet Engineering Steering Group (IESG). Further information on
			Internet Standards is available in Section 2 of RFC 7841.
	This Internet-Draft will expire on 7 November 2021.		Information about the current status of this document, any errata,
			and how to provide feedback on it may be obtained at
			https://www.rfc-editor.org/info/rfc9203.
	Copyright Notice		Copyright Notice
	Copyright (c) 2021 IETF Trust and the persons identified as the		Copyright (c) 2022 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
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	provided without warranty as described in the Simplified BSD License.		in the Revised BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction
	1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3		1.1. Terminology
	2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 4		2. Protocol Overview
	3. Client-AS Communication . . . . . . . . . . . . . . . . . . . 7		3. Client-AS Communication
	3.1. C-to-AS: POST to token endpoint . . . . . . . . . . . . . 7		3.1. C-to-AS: POST to Token Endpoint
	3.2. AS-to-C: Access Token . . . . . . . . . . . . . . . . . . 9		3.2. AS-to-C: Access Token
	3.2.1. The OSCORE_Input_Material . . . . . . . . . . . . . . 13		3.2.1. The OSCORE_Input_Material
	4. Client-RS Communication . . . . . . . . . . . . . . . . . . . 16		4. Client-RS Communication
	4.1. C-to-RS: POST to authz-info endpoint . . . . . . . . . . 16		4.1. C-to-RS: POST to authz-info Endpoint
	4.1.1. The Nonce 1 Parameter . . . . . . . . . . . . . . . . 18		4.1.1. The Nonce 1 Parameter
	4.1.2. The ace_client_recipientid Parameter . . . . . . . . 18		4.1.2. The ace_client_recipientid Parameter
	4.2. RS-to-C: 2.01 (Created) . . . . . . . . . . . . . . . . . 19		4.2. RS-to-C: 2.01 (Created)
	4.2.1. The Nonce 2 Parameter . . . . . . . . . . . . . . . . 20		4.2.1. The Nonce 2 Parameter
	4.2.2. The ace_server_recipientid Parameter . . . . . . . . 20		4.2.2. The ace_server_recipientid Parameter
	4.3. OSCORE Setup . . . . . . . . . . . . . . . . . . . . . . 20		4.3. OSCORE Setup
	4.4. Access rights verification . . . . . . . . . . . . . . . 23		4.4. Access Rights Verification
	5. Secure Communication with AS . . . . . . . . . . . . . . . . 23		5. Secure Communication with AS
	6. Discarding the Security Context . . . . . . . . . . . . . . . 23		6. Discarding the Security Context
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 24		7. Security Considerations
	8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 26		8. Privacy Considerations
	9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26		9. IANA Considerations
	9.1. ACE Profile Registry . . . . . . . . . . . . . . . . . . 27		9.1. ACE Profile Registry
	9.2. OAuth Parameters Registry . . . . . . . . . . . . . . . . 27		9.2. OAuth Parameters Registry
	9.3. OAuth Parameters CBOR Mappings Registry . . . . . . . . . 27		9.3. OAuth Parameters CBOR Mappings Registry
	9.4. OSCORE Security Context Parameters Registry . . . . . . . 28		9.4. OSCORE Security Context Parameters Registry
	9.5. CWT Confirmation Methods Registry . . . . . . . . . . . . 29		9.5. CWT Confirmation Methods Registry
	9.6. JWT Confirmation Methods Registry . . . . . . . . . . . . 29		9.6. JWT Confirmation Methods Registry
	9.7. Expert Review Instructions . . . . . . . . . . . . . . . 29		9.7. Expert Review Instructions
	10. References . . . . . . . . . . . . . . . . . . . . . . . . . 30		10. References
	10.1. Normative References . . . . . . . . . . . . . . . . . . 30		10.1. Normative References
	10.2. Informative References . . . . . . . . . . . . . . . . . 32		10.2. Informative References
	Appendix A. Profile Requirements . . . . . . . . . . . . . . . . 33		Appendix A. Profile Requirements
	Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 34		Acknowledgments
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34		Authors' Addresses
	1. Introduction		1. Introduction
	This document specifies the "coap_oscore" profile of the ACE		This document specifies the "coap_oscore" profile of the ACE
	framework [I-D.ietf-ace-oauth-authz]. In this profile, a client and		framework [RFC9200]. In this profile, a client (C) and a resource
	a resource server use the Constrained Application Protocol (CoAP)		server (RS) use the Constrained Application Protocol (CoAP) [RFC7252]
	[RFC7252] to communicate. The client uses an access token, bound to		to communicate. The client uses an access token, bound to a
	a symmetric key (the proof-of-possession key) to authorize its access		symmetric key (the proof-of-possession (PoP) key) to authorize its
	to the resource server. Note that this profile uses a symmetric-		access to the resource server. Note that this profile uses a
	crypto-based scheme, where the symmetric secret is used as input		symmetric-crypto-based scheme, where the symmetric secret is used as
	material for keying material derivation. In order to provide		input material for keying material derivation. In order to provide
	communication security and proof of possession, the client and		communication security and PoP, the client and resource server use
	resource server use Object Security for Constrained RESTful		Object Security for Constrained RESTful Environments (OSCORE) as
	Environments (OSCORE) [RFC8613]. Note that the proof of possession		defined in [RFC8613]. Note that the PoP is not achieved through a
	is not achieved through a dedicated protocol element, but rather		dedicated protocol element but rather occurs after the first message
	occurs after the first message exchange using OSCORE.		exchange using OSCORE.
	OSCORE specifies how to use CBOR Object Signing and Encryption (COSE)		OSCORE specifies how to use CBOR Object Signing and Encryption (COSE)
	[I-D.ietf-cose-rfc8152bis-struct][I-D.ietf-cose-rfc8152bis-algs] to		[RFC9052] [RFC9053] to secure CoAP messages. Note that OSCORE can be
	secure CoAP messages. Note that OSCORE can be used to secure CoAP		used to secure CoAP messages, as well as HTTP and combinations of
	messages, as well as HTTP and combinations of HTTP and CoAP; a		HTTP and CoAP; a profile of ACE similar to the one described in this
	profile of ACE similar to the one described in this document, with		document, with the difference of using HTTP instead of CoAP as the
	the difference of using HTTP instead of CoAP as communication		communication protocol, could be specified analogously to this one.
	protocol, could be specified analogously to this one.
	1.1. Terminology		1.1. Terminology
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in BCP		"OPTIONAL" in this document are to be interpreted as described in
	14 [RFC2119] [RFC8174] when, and only when, they appear in all		BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	Certain security-related terms such as "authentication",		Certain security-related terms such as "authentication",
	"authorization", "confidentiality", "(data) integrity", "Message		"authorization", "confidentiality", "(data) integrity", "Message
	Authentication Code (MAC)", "Hash-based Message Authentication Code		Authentication Code (MAC)", "Hash-based Message Authentication Code
	(HMAC)", and "verify" are taken from [RFC4949].		(HMAC)", and "verify" are taken from [RFC4949].
	RESTful terminology follows HTTP [RFC7231].		RESTful terminology follows HTTP [RFC7231].
	Readers are expected to be familiar with the terms and concepts		Readers are expected to be familiar with the terms and concepts
	defined in OSCORE [RFC8613], such as "Security Context" and		defined in OSCORE [RFC8613], such as "Security Context" and
	"Recipient ID".		"Recipient ID".
	Terminology for entities in the architecture is defined in OAuth 2.0		Terminology for entities in the architecture is defined in OAuth 2.0
	[RFC6749], such as client (C), resource server (RS), and		[RFC6749], such as client (C), resource server (RS), and
	authorization server (AS). It is assumed in this document that a		authorization server (AS). It is assumed in this document that a
	given resource on a specific RS is associated to a unique AS.		given resource on a specific RS is associated to a unique AS.
	Concise Binary Object Representation (CBOR) [RFC8949] and Concise		Concise Binary Object Representation (CBOR) [RFC8949] and Concise
	Data Definition Language (CDDL) [RFC8610] are used in this document.		Data Definition Language (CDDL) [RFC8610] are used in this document.
	CDDL predefined type names, especially bstr for CBOR byte strings and		CDDL predefined type names, especially "bstr" for CBOR byte strings
	tstr for CBOR text strings, are used extensively in this document.		and "tstr" for CBOR text strings, are used extensively in this
			document.
	Note that the term "endpoint" is used here, as in		Note that the term "endpoint" is used as in [RFC9200], following its
	[I-D.ietf-ace-oauth-authz], following its OAuth definition, which is		OAuth definition, which is to denote resources such as token and
	to denote resources such as token and introspect at the AS and authz-		introspect at the AS and authz-info at the RS. The CoAP definition,
	info at the RS. The CoAP [RFC7252] definition, which is "An entity		which is "[a]n entity participating in the CoAP protocol" [RFC7252],
	participating in the CoAP protocol" is not used in this document.		is not used in this document.
	Examples throughout this document are expressed in CBOR diagnostic		Examples throughout this document are expressed in CBOR diagnostic
	notation without the tag and value abbreviations.		notation without the tag and value abbreviations.
	2. Protocol Overview		2. Protocol Overview
	This section gives an overview of how to use the ACE Framework		This section gives an overview of how to use the ACE Framework
	[I-D.ietf-ace-oauth-authz] to secure the communication between a		[RFC9200] to secure the communication between a client and a resource
	client and a resource server using OSCORE [RFC8613]. The parameters		server using OSCORE [RFC8613]. The parameters needed by the client
	needed by the client to negotiate the use of this profile with the		to negotiate the use of this profile with the AS, as well as the
	authorization server, as well as the OSCORE setup process, are		OSCORE setup process, are described in detail in the following
	described in detail in the following sections.		sections.
	The RS maintains a collection of OSCORE Security Contexts with		The RS maintains a collection of OSCORE Security Contexts with
	associated authorization information for all the clients that it is		associated authorization information for all the clients that it is
	communicating with. The authorization information is maintained as		communicating with. The authorization information is maintained as
	policy that is used as input to processing requests from those		policy that is used as input to processing requests from those
	clients.		clients.
	This profile requires a client to retrieve an access token from the		This profile requires a client to retrieve an access token from the
	AS for the resource it wants to access on an RS, by sending an access		AS for the resource it wants to access on an RS, by sending an access
	token request to the token endpoint, as specified in section 5.8 of		token request to the token endpoint, as specified in Section 5.8 of
	[I-D.ietf-ace-oauth-authz]. The access token request and response		[RFC9200]. The access token request and response MUST be
	MUST be confidentiality-protected and ensure authenticity. This		confidentiality protected and ensure authenticity. The use of OSCORE
	profile RECOMMENDS the use of OSCORE between client and AS, to reduce		between the client and AS is RECOMMENDED in this profile, to reduce
	the number of libraries the client has to support, but other		the number of libraries the client has to support, but other
	protocols fulfilling the security requirements defined in section 5		protocols fulfilling the security requirements defined in Section 5
	of [I-D.ietf-ace-oauth-authz] MAY alternatively be used, such as TLS		of [RFC9200] MAY alternatively be used, such as TLS [RFC8446] or DTLS
	[RFC8446] or DTLS [I-D.ietf-tls-dtls13].		[RFC9147].
	Once the client has retrieved the access token, it generates a nonce		Once the client has retrieved the access token, it generates a nonce
	N1, defined in this document (see Section 4.1.1). The client also		N1, as defined in this document (see Section 4.1.1). The client also
	generates its own OSCORE Recipient ID ID1 (see Section 3.1 of		generates its own OSCORE Recipient ID, ID1 (see Section 3.1 of
	[RFC8613]), for use with the keying material associated to the RS.		[RFC8613]), for use with the keying material associated to the RS.
	The client posts the token, N1 and its Recipient ID to the RS using		The client posts the token N1 and its Recipient ID to the RS using
	the authz-info endpoint and mechanisms specified in section 5.8 of		the authz-info endpoint and mechanisms specified in Section 5.8 of
	[I-D.ietf-ace-oauth-authz] and Content-Format = application/ace+cbor.		[RFC9200] and Content-Format = application/ace+cbor. When using this
	When using this profile, the communication with the authz-info		profile, the communication with the authz-info endpoint is not
	endpoint is not protected, except for update of access rights.		protected, except for the update of access rights.
	If the access token is valid, the RS replies to this request with a		If the access token is valid, the RS replies to this request with a
	2.01 (Created) response with Content-Format = application/ace+cbor,		2.01 (Created) response with Content-Format = application/ace+cbor,
	which contains a nonce N2 and its newly generated OSCORE Recipient		which contains a nonce N2 and its newly generated OSCORE Recipient
	ID, ID2, for use with the keying material associated to the client.		ID, ID2, for use with the keying material associated to the client.
	Moreover, the server concatenates the input salt received in the		Moreover, the server concatenates the input salt received in the
	token, N1, and N2 to obtain the Master Salt of the OSCORE Security		token, N1, and N2 to obtain the Master Salt of the OSCORE Security
	Context (see section 3 of [RFC8613]). The RS then derives the		Context (see Section 3 of [RFC8613]). The RS then derives the
	complete Security Context associated with the received token from the		complete Security Context associated with the received token from the
	Master Salt, the OSCORE Recipient ID generated by the client (set as		Master Salt; the OSCORE Recipient ID generated by the client (set as
	its OSCORE Sender ID), its own OSCORE Recipient ID, plus the		its OSCORE Sender ID); its own OSCORE Recipient ID; plus the
	parameters received in the access token from the AS, following		parameters received in the access token from the AS, following
	section 3.2 of [RFC8613].		Section 3.2 of [RFC8613].
	In a similar way, after receiving the nonce N2, the client		In a similar way, after receiving the nonce N2, the client
	concatenates the input salt, N1 and N2 to obtain the Master Salt of		concatenates the input salt N1 and N2 to obtain the Master Salt of
	the OSCORE Security Context. The client then derives the complete		the OSCORE Security Context. The client then derives the complete
	Security Context from the Master Salt, the OSCORE Recipient ID		Security Context from the Master Salt; the OSCORE Recipient ID
	generated by the RS (set as its OSCORE Sender ID), its own OSCORE		generated by the RS (set as its OSCORE Sender ID); its own OSCORE
	Recipient ID, plus the parameters received from the AS.		Recipient ID; plus the parameters received from the AS.
	Finally, the client starts the communication with the RS by sending a		Finally, the client starts the communication with the RS by sending a
	request protected with OSCORE to the RS. If the request is		request protected with OSCORE to the RS. If the request is
	successfully verified, the server stores the complete Security		successfully verified, the server stores the complete Security
	Context state that is ready for use in protecting messages, and uses		Context state that is ready for use in protecting messages and uses
	it in the response, and in further communications with the client,		it in the response, and in further communications with the client,
	until token deletion due to, for example, expiration. This Security		until token deletion due to, for example, expiration. This Security
	Context is discarded when a token (whether the same or a different		Context is discarded when a token (whether the same or a different
	one) is used to successfully derive a new Security Context for that		one) is used to successfully derive a new Security Context for that
	client.		client.
	The use of nonces N1 and N2 during the exchange prevents the reuse of		The use of nonces N1 and N2 during the exchange prevents the reuse of
	an Authenticated Encryption with Associated Data (AEAD) nonce/key		an Authenticated Encryption with Associated Data (AEAD) nonce/key
	pair for two different messages. Reuse might otherwise occur when		pair for two different messages. Reuse might otherwise occur when
	client and RS derive a new Security Context from an existing (non-		the client and RS derive a new Security Context from an existing
	expired) access token, as might occur when either party has just		(non-expired) access token, as might occur when either party has just
	rebooted, and might lead to loss of both confidentiality and		rebooted, and that might lead to loss of both confidentiality and
	integrity. Instead, by using the exchanged nonces N1 and N2 as part		integrity. Instead, by using the exchanged nonces N1 and N2 as part
	of the Master Salt, the request to the authz-info endpoint posting		of the Master Salt, the request to the authz-info endpoint posting
	the same token results in a different Security Context, by OSCORE		the same token results in a different Security Context, by OSCORE
	construction, since even though the Master Secret, Sender ID and		construction, since even though the Master Secret, Sender ID, and
	Recipient ID are the same, the Master Salt is different (see		Recipient ID are the same, the Master Salt is different (see
	Section 3.2.1 of [RFC8613]). If the exchanged nonces were reused, a		Section 3.2.1 of [RFC8613]). If the exchanged nonces were reused, a
	node reusing a non-expired old token would be susceptible to on-path		node reusing a non-expired old token would be susceptible to on-path
	attackers provoking the creation of an OSCORE message using an old		attackers provoking the creation of an OSCORE message using an old
	AEAD key and nonce.		AEAD key and nonce.
	After the whole message exchange has taken place, the client can		After the whole message exchange has taken place, the client can
	contact the AS to request an update of its access rights, sending a		contact the AS to request an update of its access rights, sending a
	similar request to the token endpoint that also includes an		similar request to the token endpoint that also includes an
	identifier so that the AS can find the correct OSCORE security input		identifier so that the AS can find the correct OSCORE security input
	material it has previously shared with the client. This specific		material it has previously shared with the client. This specific
	identifier, encoded as a byte string, is assigned by the AS to be		identifier, encoded as a byte string, is assigned by the AS to be
	unique in the sets of its OSCORE security input materials, and is not		unique in the sets of its OSCORE security input materials, and it is
	used as input material to derive the full OSCORE Security Context.		not used as input material to derive the full OSCORE Security
			Context.
	An overview of the profile flow for the OSCORE profile is given in		An overview of the profile flow for the OSCORE profile is given in
	Figure 1. The names of messages coincide with those of		Figure 1. The names of messages coincide with those of [RFC9200]
	[I-D.ietf-ace-oauth-authz] when applicable.		when applicable.
	C RS AS		C RS AS
	| | |		| | |
	| ----- POST /token ----------------------------> |		| ----- POST /token ----------------------------> |
	| | |		| | |
	| <---------------------------- Access Token ----- |		| <---------------------------- Access Token ----- |
	| + Access Information |		| + Access Information |
	| ---- POST /authz-info ---> | |		| ---- POST /authz-info ---> | |
	| (access_token, N1, ID1) | |		| (access_token, N1, ID1) | |
	| | |		| | |
	skipping to change at page 7, line 40 ¶		skipping to change at line 283 ¶
	| | |		| | |
	| <--- OSCORE Response ----- | |		| <--- OSCORE Response ----- | |
	| | |		| | |
	| ... | |		| ... | |
	Figure 1: Protocol Overview		Figure 1: Protocol Overview
	3. Client-AS Communication		3. Client-AS Communication
	The following subsections describe the details of the POST request		The following subsections describe the details of the POST request
	and response to the token endpoint between client and AS.		and response to the token endpoint between the client and AS.
	Section 3.2 of [RFC8613] defines how to derive a Security Context		Section 3.2 of [RFC8613] defines how to derive a Security Context
	based on a shared master secret and a set of other parameters,		based on a shared Master Secret and a set of other parameters,
	established between client and server, which the client receives from		established between the client and server, which the client receives
	the AS in this exchange. The proof-of-possession key (pop-key)		from the AS in this exchange. The PoP key included in the response
	included in the response from the AS MUST be used as master secret in		from the AS MUST be used as a Master Secret in OSCORE.
	OSCORE.
	3.1. C-to-AS: POST to token endpoint		3.1. C-to-AS: POST to Token Endpoint
	The client-to-AS request is specified in Section 5.8.1 of		The client-to-AS request is specified in Section 5.8.1 of [RFC9200].
	[I-D.ietf-ace-oauth-authz].
	The client must send this POST request to the token endpoint over a		The client must send this POST request to the token endpoint over a
	secure channel that guarantees authentication, message integrity and		secure channel that guarantees authentication, message integrity, and
	confidentiality (see Section 5).		confidentiality (see Section 5).
	An example of such a request is shown in Figure 2		An example of such a request is shown in Figure 2.
	Header: POST (Code=0.02)		Header: POST (Code=0.02)
	Uri-Host: "as.example.com"		Uri-Host: "as.example.com"
	Uri-Path: "token"		Uri-Path: "token"
	Content-Format: "application/ace+cbor"		Content-Format: "application/ace+cbor"
	Payload:		Payload:
	{		{
	"audience" : "tempSensor4711",		"audience" : "tempSensor4711",
	"scope" : "read"		"scope" : "read"
	}		}
	Figure 2: Example C-to-AS POST /token request for an access token		Figure 2: Example C-to-AS POST /token Request for an Access Token
	bound to a symmetric key.		Bound to a Symmetric Key
	If the client wants to update its access rights without changing an		If the client wants to update its access rights without changing an
	existing OSCORE Security Context, it MUST include in its POST request		existing OSCORE Security Context, it MUST include a "req_cnf" object
	to the token endpoint a req_cnf object, with the kid field carrying a		in its POST request to the token endpoint, with the kid field
	CBOR byte string containing the OSCORE Input Material Identifier		carrying a CBOR byte string containing the OSCORE Input Material
	(assigned as discussed in Section 3.2). This identifier, together		identifier (assigned as discussed in Section 3.2). This identifier,
	with other information such as audience (see Section 5.8.1 of		together with other information such as audience (see Section 5.8.1
	[I-D.ietf-ace-oauth-authz]), can be used by the AS to determine the		of [RFC9200]), can be used by the AS to determine the shared secret
	shared secret bound to the proof-of-possession token and therefore		bound to the proof-of-possession token; therefore, it MUST identify a
	MUST identify a symmetric key that was previously generated by the AS		symmetric key that was previously generated by the AS as a shared
	as a shared secret for the communication between the client and the		secret for the communication between the client and the RS. The AS
	RS. The AS MUST verify that the received value identifies a proof-		MUST verify that the received value identifies a proof-of-possession
	of-possession key that has previously been issued to the requesting		key that has previously been issued to the requesting client. If
	client. If that is not the case, the Client-to-AS request MUST be		that is not the case, the client-to-AS request MUST be declined with
	declined with the error code "invalid_request" as defined in		the error code invalid_request as defined in Section 5.8.3 of
	Section 5.8.3 of [I-D.ietf-ace-oauth-authz].		[RFC9200].
			An example of such a request is shown in Figure 3.
	An example of such a request is shown in Figure 3
	Header: POST (Code=0.02)		Header: POST (Code=0.02)
	Uri-Host: "as.example.com"		Uri-Host: "as.example.com"
	Uri-Path: "token"		Uri-Path: "token"
	Content-Format: "application/ace+cbor"		Content-Format: "application/ace+cbor"
	Payload:		Payload:
	{		{
	"audience" : "tempSensor4711",		"audience" : "tempSensor4711",
	"scope" : "write",		"scope" : "write",
	"req_cnf" : {		"req_cnf" : {
	"kid" : h'01'		"kid" : h'01'
	}		}
	Figure 3: Example C-to-AS POST /token request for updating rights		Figure 3: Example C-to-AS POST /token Request for Updating Rights
	to an access token bound to a symmetric key.		to an Access Token Bound to a Symmetric Key
	3.2. AS-to-C: Access Token		3.2. AS-to-C: Access Token
	After verifying the POST request to the token endpoint and that the		After verifying the POST request to the token endpoint and that the
	client is authorized to obtain an access token corresponding to its		client is authorized to obtain an access token corresponding to its
	access token request, the AS responds as defined in section 5.8.2 of		access token request, the AS responds as defined in Section 5.8.2 of
	[I-D.ietf-ace-oauth-authz]. If the client request was invalid, or		[RFC9200]. If the client request was invalid, or not authorized, the
	not authorized, the AS returns an error response as described in		AS returns an error response as described in Section 5.8.3 of
	section 5.8.3 of [I-D.ietf-ace-oauth-authz].		[RFC9200].
	The AS can signal that the use of OSCORE is REQUIRED for a specific		The AS can signal that the use of OSCORE is REQUIRED for a specific
	access token by including the "ace_profile" parameter with the value		access token by including the ace_profile parameter with the value
	"coap_oscore" in the access token response. This means that the		"coap_oscore" in the access token response. This means that the
	client MUST use OSCORE towards all resource servers for which this		client MUST use OSCORE towards all resource servers for which this
	access token is valid, and follow Section 4.3 to derive the security		access token is valid, and follow Section 4.3 to derive the security
	context to run OSCORE. Usually it is assumed that constrained		context to run OSCORE. Usually, it is assumed that constrained
	devices will be pre-configured with the necessary profile, so that		devices will be preconfigured with the necessary profile, so that
	this kind of profile signaling can be omitted.		this kind of profile signaling can be omitted.
	Moreover, the AS MUST send the following data:		Moreover, the AS MUST send the following data:
	* a master secret		* a Master Secret
	* an identifier of the OSCORE Input Material		* an identifier of the OSCORE Input Material
	Additionally, the AS MAY send the following data, in the same		Additionally, the AS MAY send the following data, in the same
	response.		response.
	* a context identifier		* a context identifier
	* an AEAD algorithm		* an AEAD algorithm
	* an HMAC-based key derivation function (HKDF, [RFC5869]) algorithm,
	see section 3.1 of [I-D.ietf-cose-rfc8152bis-algs]		* an HMAC-based key derivation function (HKDF) algorithm [RFC5869];
			see Section 3.1 of [RFC9053]
	* a salt		* a salt
	* the OSCORE version number		* the OSCORE version number
	This data is transported in the OSCORE_Input_Material. The		This data is transported in the OSCORE_Input_Material. The
	OSCORE_Input_Material is a CBOR map object, defined in Section 3.2.1.		OSCORE_Input_Material is a CBOR map object, defined in Section 3.2.1.
	This object is transported in the "cnf" parameter of the access token		This object is transported in the cnf parameter of the access token
	response as defined in Section 3.2 of [I-D.ietf-ace-oauth-params], as		response, as defined in Section 3.2 of [RFC9201], as the value of a
	the value of a field named "osc", registered in Section 9.5 and		field named "osc", which is registered in Sections 9.5 and 9.6.
	Section 9.6.
	The AS MAY assign an identifier to the context (context identifier).		The AS MAY assign an identifier to the context (context identifier).
	This identifier is used as ID Context in the OSCORE context as		This identifier is used as ID Context in the OSCORE context as
	described in section 3.1 of [RFC8613]. If assigned, this parameters		described in Section 3.1 of [RFC8613]. If assigned, these parameters
	MUST be communicated as the "contextId" field in the		MUST be communicated as the contextId field in the
	OSCORE_Input_Material. The application needs to consider that this		OSCORE_Input_Material. The application needs to consider that this
	identifier is sent in the clear and may reveal information about the		identifier is sent in the clear and may reveal information about the
	endpoints, as mentioned in section 12.8 of [RFC8613].		endpoints, as mentioned in Section 12.8 of [RFC8613].
	The master secret and the identifier of the OSCORE_Input_Material		The Master Secret and the identifier of the OSCORE_Input_Material
	MUST be communicated as the "ms" and "id" field in the "osc" field in		MUST be communicated as the ms and id field in the osc field in the
	the "cnf" parameter of the access token response. If included, the		cnf parameter of the access token response. If included, the
	AEAD algorithm is sent in the "alg" parameter in the		following are sent: the AEAD algorithm in the alg parameter in the
	OSCORE_Input_Material; the HKDF algorithm in the "hkdf" parameter of		OSCORE_Input_Material; the HKDF algorithm in the hkdf parameter of
	the OSCORE_Input_Material; a salt in the "salt" parameter of the		the OSCORE_Input_Material; a salt in the salt parameter of the
	OSCORE_Input_Material; and the OSCORE version in the "version"		OSCORE_Input_Material; and the OSCORE version in the version
	parameter of the OSCORE_Input_Material.		parameter of the OSCORE_Input_Material.
	The same parameters MUST be included in the claims associated with		The same parameters MUST be included in the claims associated with
	the access token. The OSCORE master secret MUST be encrypted by the		the access token. The OSCORE Master Secret MUST be encrypted by the
	authorization server so that only the resource server can decrypt it		authorization server so that only the resource server can decrypt it
	(see Section 6.1. of [I-D.ietf-ace-oauth-authz]). This profile		(see Section 6.1 of [RFC9200]). The use of a CBOR Web Token (CWT)
	RECOMMENDS the use of a CBOR web token (CWT) protected with		protected with COSE_Encrypt/COSE_Encrypt0 as specified in [RFC8392]
	COSE_Encrypt/COSE_Encrypt0 as specified in [RFC8392]. If the token		is RECOMMENDED in this profile. If the token is a CWT, the same
	is a CWT, the same OSCORE_Input_Material structure defined above MUST		OSCORE_Input_Material structure defined above MUST be placed in the
	be placed in the "osc" field of the "cnf" claim of this token.		osc field of the cnf claim of this token.
	The AS MUST send different OSCORE_Input_Material (and therefore		The AS MUST send a different OSCORE_Input_Material (and therefore
	different access tokens) to different authorized clients, in order		different access tokens) to different authorized clients, in order
	for the RS to differentiate between clients.		for the RS to differentiate between clients.
	Figure 4 shows an example of an AS response. The access token has		Figure 4 shows an example of an AS response. The access token has
	been truncated for readability.		been truncated for readability.
	Header: Created (Code=2.01)		Header: Created (Code=2.01)
	Content-Type: "application/ace+cbor"		Content-Type: "application/ace+cbor"
	Payload:		Payload:
	{		{
	skipping to change at page 11, line 21 ¶		skipping to change at line 439 ¶
	"ace_profile" : "coap_oscore",		"ace_profile" : "coap_oscore",
	"expires_in" : "3600",		"expires_in" : "3600",
	"cnf" : {		"cnf" : {
	"osc" : {		"osc" : {
	"id" : h'01',		"id" : h'01',
	"ms" : h'f9af838368e353e78888e1426bd94e6f'		"ms" : h'f9af838368e353e78888e1426bd94e6f'
	}		}
	}		}
	}		}
	Figure 4: Example AS-to-C Access Token response with OSCORE profile.		Figure 4: Example AS-to-C Access Token Response with an OSCORE
			Profile
	Figure 5 shows an example CWT Claims Set, including the relevant		Figure 5 shows an example CWT Claims Set, including the relevant
	OSCORE parameters in the "cnf" claim.		OSCORE parameters in the cnf claim.
	{		{
	"aud" : "tempSensorInLivingRoom",		"aud" : "tempSensorInLivingRoom",
	"iat" : "1360189224",		"iat" : "1360189224",
	"exp" : "1360289224",		"exp" : "1360289224",
	"scope" : "temperature_g firmware_p",		"scope" : "temperature_g firmware_p",
	"cnf" : {		"cnf" : {
	"osc" : {		"osc" : {
	"ms" : h'f9af838368e353e78888e1426bd94e6f',		"ms" : h'f9af838368e353e78888e1426bd94e6f',
	"id" : h'01'		"id" : h'01'
	}		}
	}		}
	}		}
	Figure 5: Example CWT Claims Set with OSCORE parameters.		Figure 5: Example CWT Claims Set with OSCORE Parameters
	The same CWT Claims Set as in Figure 5, using the value abbreviations		The same CWT Claims Set as in Figure 5, using the value abbreviations
	defined in [I-D.ietf-ace-oauth-authz] and [RFC8747] and encoded in		defined in [RFC9200] and [RFC8747] and encoded in CBOR, is shown in
	CBOR is shown in Figure 6. The bytes in hexadecimal are reported in		Figure 6. The bytes in hexadecimal are reported in the first column,
	the first column, while their corresponding CBOR meaning is reported		while their corresponding CBOR meaning is reported after the # sign
	after the "#" sign on the second column, for easiness of readability.		on the second column, for readability.
	NOTE TO THE RFC EDITOR: before publishing, it should be checked (and
	in case fixed) that the values used below (which are not yet
	registered) are the final values registered in IANA.
	A5 # map(5)		A5 # map(5)
	63 # text(3)		63 # text(3)
	617564 # "aud"		617564 # "aud"
	76 # text(22)		76 # text(22)
	74656D7053656E736F72496E4C6976696E67526F6F6D		74656D7053656E736F72496E4C6976696E67526F6F6D
	# "tempSensorInLivingRoom"		# "tempSensorInLivingRoom"
	63 # text(3)		63 # text(3)
	696174 # "iat"		696174 # "iat"
	6A # text(10)		6A # text(10)
	skipping to change at page 12, line 41 ¶		skipping to change at line 502 ¶
	6D73 # "ms"		6D73 # "ms"
	50 # bytes(16)		50 # bytes(16)
	F9AF838368E353E78888E1426BD94E6F		F9AF838368E353E78888E1426BD94E6F
	# "\xF9\xAF\x83\x83h\xE3S\xE7		# "\xF9\xAF\x83\x83h\xE3S\xE7
	\x88\x88\xE1Bk\xD9No"		\x88\x88\xE1Bk\xD9No"
	62 # text(2)		62 # text(2)
	6964 # "id"		6964 # "id"
	41 # bytes(1)		41 # bytes(1)
	01 # "\x01"		01 # "\x01"
	Figure 6: Example CWT Claims Set with OSCORE parameters, CBOR		Figure 6: Example CWT Claims Set with OSCORE Parameters Using
	encoded.		CBOR Encoding
	If the client has requested an update to its access rights using the		If the client has requested an update to its access rights using the
	same OSCORE Security Context, which is valid and authorized, the AS		same OSCORE Security Context, which is valid and authorized, the AS
	MUST omit the "cnf" parameter in the response, and MUST carry the		MUST omit the cnf parameter in the response and MUST carry the OSCORE
	OSCORE Input Material identifier in the "kid" field in the "cnf"		Input Material identifier in the kid field in the cnf claim of the
	claim of the token. This identifier needs to be included in the		token. This identifier needs to be included in the token in order
	token in order for the RS to identify the correct OSCORE Input		for the RS to identify the correct OSCORE Input Material.
	Material.
	Figure 7 shows an example of such an AS response The access token has		Figure 7 shows an example of such an AS response. The access token
	been truncated for readability.		has been truncated for readability.
	Header: Created (Code=2.01)		Header: Created (Code=2.01)
	Content-Type: "application/ace+cbor"		Content-Type: "application/ace+cbor"
	Payload:		Payload:
	{		{
	"access_token" : h'8343a1010aa2044c53 ...		"access_token" : h'8343a1010aa2044c53 ...
	(remainder of access token (CWT) omitted for brevity)',		(remainder of access token (CWT) omitted for brevity)',
	"ace_profile" : "coap_oscore",		"ace_profile" : "coap_oscore",
	"expires_in" : "3600"		"expires_in" : "3600"
	}		}
	Figure 7: Example AS-to-C Access Token response with OSCORE		Figure 7: Example AS-to-C Access Token Response with an OSCORE
	profile, for update of access rights.		Profile for the Update of Access Rights
	Figure 8 shows an example CWT Claims Set, containing the necessary		Figure 8 shows an example CWT Claims Set that contains the necessary
	OSCORE parameters in the "cnf" claim for update of access rights.		OSCORE parameters in the cnf claim for the update of access rights.
	{		{
	"aud" : "tempSensorInLivingRoom",		"aud" : "tempSensorInLivingRoom",
	"iat" : "1360189224",		"iat" : "1360189224",
	"exp" : "1360289224",		"exp" : "1360289224",
	"scope" : "temperature_h",		"scope" : "temperature_h",
	"cnf" : {		"cnf" : {
	"kid" : h'01'		"kid" : h'01'
	}		}
	}		}
	Figure 8: Example CWT Claims Set with OSCORE parameters for		Figure 8: Example CWT Claims Set with OSCORE Parameters for the
	update of access rights.		Update of Access Rights
	3.2.1. The OSCORE_Input_Material		3.2.1. The OSCORE_Input_Material
	An OSCORE_Input_Material is an object that represents the input		An OSCORE_Input_Material is an object that represents the input
	material to derive an OSCORE Security Context, i.e., the local set of		material to derive an OSCORE Security Context, i.e., the local set of
	information elements necessary to carry out the cryptographic		information elements necessary to carry out the cryptographic
	operations in OSCORE (Section 3.1 of [RFC8613]). In particular, the		operations in OSCORE (Section 3.1 of [RFC8613]). In particular, the
	OSCORE_Input_Material is defined to be serialized and transported		OSCORE_Input_Material is defined to be serialized and transported
	between nodes, as specified by this document, but can also be used by		between nodes, as specified by this document, but it can also be used
	other specifications if needed. The OSCORE_Input_Material can either		by other specifications if needed. The OSCORE_Input_Material can be
	be encoded as a JSON object or as a CBOR map. The set of common		encoded as either a JSON object or a CBOR map. The set of common
	parameters that can appear in an OSCORE_Input_Material can be found		parameters that can appear in an OSCORE_Input_Material can be found
	in the IANA "OSCORE Security Context Parameters" registry		in the IANA "OSCORE Security Context Parameters" registry
	(Section 9.4), defined for extensibility, and the initial set of		(Section 9.4), defined for extensibility, and the initial set of
	parameters defined in this document is specified below. All		parameters defined in this document is specified below. All
	parameters are optional. Table 1 provides a summary of the		parameters are optional. Table 1 provides a summary of the
	OSCORE_Input_Material parameters defined in this section.		OSCORE_Input_Material parameters defined in this section.
	+===========+=======+==========+===================+===============+		+===========+=======+==========+===================+===============+
	| name | CBOR | CBOR | registry | description |		| name | CBOR | CBOR | registry | description |
	| | label | type | | |		| | label | type | | |
	+===========+=======+==========+===================+===============+		+===========+=======+==========+===================+===============+
	| id | 0 | byte | | OSCORE Input |		| id | 0 | byte | | OSCORE Input |
	| | | string | | Material |		| | | string | | Material |
	| | | | | Identifier |		| | | | | identifier |
	+-----------+-------+----------+-------------------+---------------+		+-----------+-------+----------+-------------------+---------------+
	| version | 1 | unsigned | | OSCORE |		| version | 1 | unsigned | | OSCORE |
	| | | integer | | Version |		| | | integer | | version |
	+-----------+-------+----------+-------------------+---------------+		+-----------+-------+----------+-------------------+---------------+
	| ms | 2 | byte | | OSCORE Master |		| ms | 2 | byte | | OSCORE Master |
	| | | string | | Secret value |		| | | string | | Secret value |
	+-----------+-------+----------+-------------------+---------------+		+-----------+-------+----------+-------------------+---------------+
	| hkdf | 3 | text | [COSE.Algorithms] | OSCORE HKDF |		| hkdf | 3 | text | [COSE.Algorithms] | OSCORE HKDF |
	| | | string / | Values (HMAC- | value |		| | | string / | values (HMAC- | value |
	| | | integer | based) | |		| | | integer | based) | |
	+-----------+-------+----------+-------------------+---------------+		+-----------+-------+----------+-------------------+---------------+
	| alg | 4 | text | [COSE.Algorithms] | OSCORE AEAD |		| alg | 4 | text | [COSE.Algorithms] | OSCORE AEAD |
	| | | string / | Values (AEAD) | Algorithm |		| | | string / | values (AEAD) | Algorithm |
	| | | integer | | value |		| | | integer | | value |
	+-----------+-------+----------+-------------------+---------------+		+-----------+-------+----------+-------------------+---------------+
	| salt | 5 | byte | | an input to |		| salt | 5 | byte | | an input to |
	| | | string | | OSCORE Master |		| | | string | | OSCORE Master |
	| | | | | Salt value |		| | | | | Salt value |
	+-----------+-------+----------+-------------------+---------------+		+-----------+-------+----------+-------------------+---------------+
	| contextId | 6 | byte | | OSCORE ID |		| contextId | 6 | byte | | OSCORE ID |
	| | | string | | Context value |		| | | string | | Context value |
	+-----------+-------+----------+-------------------+---------------+		+-----------+-------+----------+-------------------+---------------+
	Table 1: OSCORE_Input_Material Parameters		Table 1: OSCORE_Input_Material Parameters
	id: This parameter identifies the OSCORE_Input_Material and is		id: This parameter identifies the OSCORE_Input_Material and is
	encoded as a byte string. In JSON, the "id" value is a Base64		encoded as a byte string. In JSON, the "id" value is a
	encoded byte string. In CBOR, the "id" type is byte string, and		base64-encoded byte string. In CBOR, the "id" type is a byte
	has label 0.		string, and it has label 0.
	version: This parameter identifies the OSCORE Version number, which		version: This parameter identifies the OSCORE version number, which
	is an unsigned integer. For more information about this field,		is an unsigned integer. For more information about this field,
	see section 5.4 of [RFC8613]. In JSON, the "version" value is an		see Section 5.4 of [RFC8613]. In JSON, the "version" value is an
	integer. In CBOR, the "version" type is integer, and has label 1.		integer. In CBOR, the "version" type is an integer, and it has
			label 1.
	ms: This parameter identifies the OSCORE Master Secret value, which		ms: This parameter identifies the OSCORE Master Secret value, which
	is a byte string. For more information about this field, see		is a byte string. For more information about this field, see
	section 3.1 of [RFC8613]. In JSON, the "ms" value is a Base64		Section 3.1 of [RFC8613]. In JSON, the "ms" value is a
	encoded byte string. In CBOR, the "ms" type is byte string, and		base64-encoded byte string. In CBOR, the "ms" type is byte
	has label 2.		string, and it has label 2.
	hkdf: This parameter identifies the OSCORE HKDF Algorithm. For more		hkdf: This parameter identifies the OSCORE HKDF Algorithm. For more
	information about this field, see section 3.1 of [RFC8613]. The		information about this field, see Section 3.1 of [RFC8613]. The
	values used MUST be registered in the IANA "COSE Algorithms"		values used MUST be registered in the IANA "COSE Algorithms"
	registry (see [COSE.Algorithms]) and MUST be HMAC-based HKDF		registry (see [COSE.Algorithms]) and MUST be HMAC-based HKDF
	algorithms (see section 3.1 of [I-D.ietf-cose-rfc8152bis-algs]).		algorithms (see Section 3.1 of [RFC9053]). The value can be
	The value can either be the integer or the text string value of		either the integer or the text-string value of the HMAC-based HKDF
	the HMAC-based HKDF algorithm in the "COSE Algorithms" registry.		algorithm in the "COSE Algorithms" registry. In JSON, the "hkdf"
	In JSON, the "hkdf" value is a case-sensitive ASCII string or an		value is a case-sensitive ASCII string or an integer. In CBOR,
	integer. In CBOR, the "hkdf" type is text string or integer, and		the "hkdf" type is a text string or integer, and it has label 3.
	has label 3.
	alg: This parameter identifies the OSCORE AEAD Algorithm. For more		alg: This parameter identifies the OSCORE AEAD Algorithm. For more
	information about this field, see section 3.1 of [RFC8613] The		information about this field, see Section 3.1 of [RFC8613]. The
	values used MUST be registered in the IANA "COSE Algorithms"		values used MUST be registered in the IANA "COSE Algorithms"
	registry (see [COSE.Algorithms]) and MUST be AEAD algorithms. The		registry (see [COSE.Algorithms]) and MUST be AEAD algorithms. The
	value can either be the integer or the text string value of the		value can be either the integer or the text-string value of the
	HMAC-based HKDF algorithm in the "COSE Algorithms" registry. In		HMAC-based HKDF algorithm in the "COSE Algorithms" registry. In
	JSON, the "alg" value is a case-sensitive ASCII string or an		JSON, the "alg" value is a case-sensitive ASCII string or an
	integer. In CBOR, the "alg" type is text string or integer, and		integer. In CBOR, the "alg" type is a text string or integer, and
	has label 4.		it has label 4.
	salt: This parameter identifies an input to the OSCORE Master Salt		salt: This parameter identifies an input to the OSCORE Master Salt
	value, which is a byte string. For more information about this		value, which is a byte string. For more information about this
	field, see section 3.1 of [RFC8613]. In JSON, the "salt" value is		field, see Section 3.1 of [RFC8613]. In JSON, the "salt" value is
	a Base64 encoded byte string. In CBOR, the "salt" type is byte		a base64-encoded byte string. In CBOR, the "salt" type is a byte
	string, and has label 5.		string, and it has label 5.
	contextId: This parameter identifies the security context as a byte		contextId: This parameter identifies the security context as a byte
	string. This identifier is used as OSCORE ID Context. For more		string. This identifier is used as OSCORE ID Context. For more
	information about this field, see section 3.1 of [RFC8613]. In		information about this field, see Section 3.1 of [RFC8613]. In
	JSON, the "contextID" value is a Base64 encoded byte string. In		JSON, the "contextID" value is a base64-encoded byte string. In
	CBOR, the "contextID" type is byte string, and has label 6.		CBOR, the "contextID" type is a byte string, and it has label 6.
	An example of JSON OSCORE_Input_Material is given in Figure 9.		An example of JSON OSCORE_Input_Material is given in Figure 9.
	"osc" : {		"osc" : {
	"alg" : "AES-CCM-16-64-128",		"alg" : "AES-CCM-16-64-128",
	"id" : b64'AQ=='		"id" : b64'AQ=='
	"ms" : b64'+a+Dg2jjU+eIiOFCa9lObw'		"ms" : b64'+a+Dg2jjU+eIiOFCa9lObw'
	}		}
	Figure 9: Example JSON OSCORE_Input_Material		Figure 9: Example JSON OSCORE_Input_Material
	skipping to change at page 16, line 21 ¶		skipping to change at line 668 ¶
	? 3 => tstr / int, ; hkdf		? 3 => tstr / int, ; hkdf
	? 4 => tstr / int, ; alg		? 4 => tstr / int, ; alg
	? 5 => bstr, ; salt		? 5 => bstr, ; salt
	? 6 => bstr, ; contextId		? 6 => bstr, ; contextId
	* int / tstr => any		* int / tstr => any
	}		}
	4. Client-RS Communication		4. Client-RS Communication
	The following subsections describe the details of the POST request		The following subsections describe the details of the POST request
	and response to the authz-info endpoint between client and RS. The		and response to the authz-info endpoint between the client and RS.
	client generates a nonce N1 and an identifier ID1 unique in the sets		The client generates a nonce N1 and an identifier ID1 that is unique
	of its own Recipient IDs, and posts them together with the token that		in the sets of its own Recipient IDs and posts them together with the
	includes the materials (e.g., OSCORE parameters) received from the AS		token that includes the materials (e.g., OSCORE parameters) received
	to the RS. The RS then generates a nonce N2 and an identifier ID2		from the AS to the RS. The RS then generates a nonce N2 and an
	unique in the sets of its own Recipient IDs, and uses Section 3.2 of		identifier ID2 that is unique in the sets of its own Recipient IDs
	[RFC8613] to derive a security context based on a shared master		and uses Section 3.2 of [RFC8613] to derive a security context based
	secret, the two exchanged nonces and the two identifiers, established		on a shared Master Secret, the two exchanged nonces, and the two
	between client and server. The exchanged nonces and identifiers are		identifiers, established between the client and server. The
	encoded as CBOR byte string if CBOR is used, and as Base64 string if		exchanged nonces and identifiers are encoded as a CBOR byte string if
	JSON is used. This security context is used to protect all future		CBOR is used and as a base64 string if JSON is used. This security
	communication between client and RS using OSCORE, as long as the		context is used to protect all future communication between the
	access token is valid.		client and RS using OSCORE, as long as the access token is valid.
	Note that the RS and client authenticate each other by generating the		Note that the RS and client authenticate each other by generating the
	shared OSCORE Security Context using the pop-key as master secret.		shared OSCORE Security Context using the PoP key as the Master
	An attacker posting a valid token to the RS will not be able to		Secret. An attacker posting a valid token to the RS will not be able
	generate a valid OSCORE Security Context and thus not be able to		to generate a valid OSCORE Security Context and thus will not be able
	prove possession of the pop-key. Additionally, the mutual		to prove possession of the PoP key. Additionally, the mutual
	authentication is only achieved after the client has successfully		authentication is only achieved after the client has successfully
	verified a response from the RS protected with the generated OSCORE		verified a response from the RS protected with the generated OSCORE
	Security Context.		Security Context.
	4.1. C-to-RS: POST to authz-info endpoint		4.1. C-to-RS: POST to authz-info Endpoint
	The client MUST generate a nonce value N1 very unlikely to have been		The client MUST generate a nonce value N1 that is very unlikely to
	previously used with the same input keying material. This profile		have been previously used with the same input keying material. The
	RECOMMENDS using a 64-bit long random number as the nonce's value.		use of a 64-bit long random number as the nonce's value is
	The client MUST store the nonce N1 as long as the response from the		RECOMMENDED in this profile. The client MUST store the nonce N1 as
	RS is not received and the access token related to it is still valid		long as the response from the RS is not received and the access token
	(to the best of the client's knowledge).		related to it is still valid (to the best of the client's knowledge).
	The client generates its own Recipient ID, ID1, for the OSCORE		The client generates its own Recipient ID, ID1, for the OSCORE
	Security Context that it is establishing with the RS. By generating		Security Context that it is establishing with the RS. By generating
	its own Recipient ID, the client makes sure that it does not collide		its own Recipient ID, the client makes sure that it does not collide
	with any of its Recipient IDs, nor with any other identifier ID1 if		with any of its Recipient IDs, nor with any other identifier ID1 if
	the client is executing this exchange with a different RS at the same		the client is executing this exchange with a different RS at the same
	time.		time.
	The client MUST use CoAP and the Authorization Information resource		The client MUST use CoAP and the authorization information resource
	as described in section 5.8.1 of [I-D.ietf-ace-oauth-authz] to		as described in Section 5.8.1 of [RFC9200] to transport the token,
	transport the token, N1 and ID1 to the RS.		N1, and ID1 to the RS.
	Note that the use of the payload and the Content-Format is different		Note that the use of the payload and the Content-Format is different
	from what is described in section 5.8.1 of		from what is described in Section 5.8.1 of [RFC9200], which only
	[I-D.ietf-ace-oauth-authz], which only transports the token without		transports the token without any CBOR wrapping. In this profile, the
	any CBOR wrapping. In this profile, the client MUST wrap the token,		client MUST wrap the token, N1, and ID1 in a CBOR map. The client
	N1 and ID1 in a CBOR map. The client MUST use the Content-Format		MUST use the Content-Format "application/ace+cbor" defined in
	"application/ace+cbor" defined in section 8.14 of		Section 8.14 of [RFC9200]. The client MUST include the access token
	[I-D.ietf-ace-oauth-authz]. The client MUST include the access token		using the access_token parameter; N1 using the nonce1 parameter
	using the "access_token" parameter, N1 using the "nonce1" parameter		defined in Section 4.1.1; and ID1 using the ace_client_recipientid
	defined in Section 4.1.1, and ID1 using the "ace_client_recipientid"
	parameter defined in Section 4.1.2.		parameter defined in Section 4.1.2.
	The communication with the authz-info endpoint does not have to be		The communication with the authz-info endpoint does not have to be
	protected, except for the update of access rights case described		protected, except for the update of access rights case described
	below.		below.
	Note that a client may be required to re-POST the access token in		Note that a client may be required to re-POST the access token in
	order to complete a request, since an RS may delete a stored access		order to complete a request, since an RS may delete a stored access
	token (and associated Security Context) at any time, for example due		token (and associated Security Context) at any time, for example, due
	to all storage space being consumed. This situation is detected by		to all storage space being consumed. This situation is detected by
	the client when it receives an AS Request Creation Hints response.		the client when it receives an AS Request Creation Hints response.
	Reposting the same access token will result in deriving a new OSCORE		Reposting the same access token will result in deriving a new OSCORE
	Security Context to be used with the RS, as different exchanged		Security Context to be used with the RS, as different exchanged
	nonces will be used.		nonces will be used.
	The client may also choose to re-POST the access token in order to		The client may also choose to re-POST the access token in order to
	update its OSCORE Security Context. In that case, the client and the		update its OSCORE Security Context. In that case, the client and the
	RS will exchange newly generated nonces, re-negotiate identifiers,		RS will exchange newly generated nonces, renegotiate identifiers, and
	and derive new keying material. The client and RS might decide to		derive new keying material. The client and RS might decide to keep
	keep the same identifiers or renew them during the re-negotiation.		the same identifiers or renew them during the renegotiation.
	Figure 10 shows an example of the request sent from the client to the		Figure 10 shows an example of the request sent from the client to the
	RS. The access token has been truncated for readability.		RS. The access token has been truncated for readability.
	Header: POST (Code=0.02)		Header: POST (Code=0.02)
	Uri-Host: "rs.example.com"		Uri-Host: "rs.example.com"
	Uri-Path: "authz-info"		Uri-Path: "authz-info"
	Content-Format: "application/ace+cbor"		Content-Format: "application/ace+cbor"
	Payload:		Payload:
	{		{
	"access_token": h'8343a1010aa2044c53 ...		"access_token": h'8343a1010aa2044c53 ...
	(remainder of access token (CWT) omitted for brevity)',		(remainder of access token (CWT) omitted for brevity)',
	"nonce1": h'018a278f7faab55a',		"nonce1": h'018a278f7faab55a',
	"ace_client_recipientid" : h'1645'		"ace_client_recipientid" : h'1645'
	}		}
	Figure 10: Example C-to-RS POST /authz-info request using CWT		Figure 10: Example C-to-RS POST /authz-info Request Using CWT
	If the client has already posted a valid token, has already		If the client has already posted a valid token, has already
	established a security association with the RS, and wants to update		established a security association with the RS, and wants to update
	its access rights, the client can do so by posting the new token		its access rights, the client can do so by posting the new token
	(retrieved from the AS and containing the update of access rights) to		(retrieved from the AS and containing the update of access rights) to
	the /authz-info endpoint. The client MUST protect the request using		the /authz-info endpoint. The client MUST protect the request using
	the OSCORE Security Context established during the first token		the OSCORE Security Context established during the first token
	exchange. The client MUST only send the "access_token" field in the		exchange. The client MUST only send the access_token field in the
	CBOR map in the payload, no nonce or identifier are sent. After		CBOR map in the payload; no nonce or identifier is sent. After
	proper verification (see Section 4.2), the RS will replace the old		proper verification (see Section 4.2), the RS will replace the old
	token with the new one, maintaining the same Security Context.		token with the new one, maintaining the same Security Context.
	4.1.1. The Nonce 1 Parameter		4.1.1. The Nonce 1 Parameter
	This parameter MUST be sent from the client to the RS, together with		The nonce 1 parameter MUST be sent from the client to the RS,
	the access token, if the ace profile used is coap_oscore, and the		together with the access token, if the ACE profile used is
	message is not an update of access rights, protected with an existing		"coap_oscore", and the message is not an update of access rights,
	OSCORE Security Context. The parameter is encoded as a byte string		protected with an existing OSCORE Security Context. The parameter is
	for CBOR-based interactions, and as a string (Base64 encoded binary)		encoded as a byte string for CBOR-based interactions and as a string
	for JSON-based interactions. This parameter is registered in		(base64-encoded binary) for JSON-based interactions. This parameter
	Section 9.2.		is registered in Section 9.2.
	4.1.2. The ace_client_recipientid Parameter		4.1.2. The ace_client_recipientid Parameter
	This parameter MUST be sent from the client to the RS, together with		The ace_client_recipientid parameter MUST be sent from the client to
	the access token, if the ace profile used is coap_oscore, and the		the RS, together with the access token, if the ACE profile used is
	message is not an update of access rights, protected with an existing		"coap_oscore", and the message is not an update of access rights,
	OSCORE Security Context. The parameter is encoded as a byte string		protected with an existing OSCORE Security Context. The parameter is
	for CBOR-based interactions, and as a string (Base64 encoded binary)		encoded as a byte string for CBOR-based interactions and as a string
	for JSON-based interactions. This parameter is registered in		(base64-encoded binary) for JSON-based interactions. This parameter
	Section 9.2.		is registered in Section 9.2.
	4.2. RS-to-C: 2.01 (Created)		4.2. RS-to-C: 2.01 (Created)
	The RS MUST follow the procedures defined in section 5.8.1 of		The RS MUST follow the procedures defined in Section 5.8.1 of
	[I-D.ietf-ace-oauth-authz]: the RS must verify the validity of the		[RFC9200]: the RS must verify the validity of the token. If the
	token. If the token is valid, the RS must respond to the POST		token is valid, the RS must respond to the POST request with 2.01
	request with 2.01 (Created). If the token is valid but is associated		(Created). If the token is valid but is associated to claims that
	to claims that the RS cannot process (e.g., an unknown scope), or if		the RS cannot process (e.g., an unknown scope), or if any of the
	any of the expected parameters is missing (e.g., any of the mandatory		expected parameters are missing (e.g., any of the mandatory
	parameters from the AS or the identifier "id1"), or if any parameters		parameters from the AS or the identifier ID1), or if any parameters
	received in the "osc" field is unrecognized, the RS must respond with		received in the osc field are unrecognized, the RS must respond with
	an error response code equivalent to the CoAP code 4.00 (Bad		an error response code equivalent to the CoAP code 4.00 (Bad
	Request). In the latter two cases, the RS may provide additional		Request). In the latter two cases, the RS may provide additional
	information in the error response, in order to clarify what went		information in the error response, in order to clarify what went
	wrong. The RS may make an introspection request (see Section 5.9.1		wrong. The RS may make an introspection request (see Section 5.9.1
	of [I-D.ietf-ace-oauth-authz]) to validate the token before		of [RFC9200]) to validate the token before responding to the POST
	responding to the POST request to the authz-info endpoint.		request to the authz-info endpoint.
	Additionally, the RS MUST generate a nonce N2 very unlikely to have		Additionally, the RS MUST generate a nonce N2 that is very unlikely
	been previously used with the same input keying material, and its own		to have been previously used with the same input keying material and
	Recipient ID, ID2. The RS makes sure that ID2 does not collide with		its own Recipient ID, ID2. The RS makes sure that ID2 does not
	any of its Recipient IDs. The RS MUST ensure that ID2 is different		collide with any of its Recipient IDs. The RS MUST ensure that ID2
	from the value received in the ace_client_recipientid parameter. The		is different from the value received in the ace_client_recipientid
	RS sends N2 and ID2 within the 2.01 (Created) response. The payload		parameter. The RS sends N2 and ID2 within the 2.01 (Created)
	of the 2.01 (Created) response MUST be a CBOR map containing the		response. The payload of the 2.01 (Created) response MUST be a CBOR
	"nonce2" parameter defined in Section 4.2.1, set to N2, and the		map containing the nonce2 parameter defined in Section 4.2.1, set to
	"ace_server_recipientid" parameter defined in Section 4.2.2, set to		N2, and the ace_server_recipientid parameter defined in
	ID2. This profile RECOMMENDS using a 64-bit long random number as		Section 4.2.2, set to ID2. The use of a 64-bit long random number as
	the nonce's value. The RS MUST use the Content-Format "application/		the nonce's value is RECOMMENDED in this profile. The RS MUST use
	ace+cbor" defined in section 8.14 of [I-D.ietf-ace-oauth-authz].		the Content-Format "application/ace+cbor" defined in Section 8.14 of
			[RFC9200].
	Figure 11 shows an example of the response sent from the RS to the		Figure 11 shows an example of the response sent from the RS to the
	client.		client.
	Header: Created (Code=2.01)		Header: Created (Code=2.01)
	Content-Format: "application/ace+cbor"		Content-Format: "application/ace+cbor"
	Payload:		Payload:
	{		{
	"nonce2": h'25a8991cd700ac01',		"nonce2": h'25a8991cd700ac01',
	"ace_server_recipientid" : h'0000'		"ace_server_recipientid" : h'0000'
	}		}
	Figure 11: Example RS-to-C 2.01 (Created) response		Figure 11: Example RS-to-C 2.01 (Created) Response
	As specified in section 5.8.3 of [I-D.ietf-ace-oauth-authz], the RS		As specified in Section 5.8.3 of [RFC9200], the RS must notify the
	must notify the client with an error response with code 4.01		client with an error response with code 4.01 (Unauthorized) for any
	(Unauthorized) for any long running request before terminating the		long running request before terminating the session, when the access
	session, when the access token expires.		token expires.
	If the RS receives the token in a OSCORE protected message, it means		If the RS receives the token in an OSCORE-protected message, it means
	that the client is requesting an update of access rights. The RS		that the client is requesting an update of access rights. The RS
	MUST ignore any nonce and identifiers in the request, if any was		MUST ignore any nonce and identifiers in the request, if any were
	sent. The RS MUST check that the "kid" of the "cnf" claim of the new		sent. The RS MUST check that the "kid" of the cnf claim of the new
	access token matches the identifier of the OSCORE Input Material of		access token matches the identifier of the OSCORE Input Material of
	the context used to protect the message. If that is the case, the RS		the context used to protect the message. If that is the case, the RS
	MUST overwrite the old token and associate the new token to the		MUST overwrite the old token and associate the new token to the
	Security Context identified by the "kid" value in the "cnf" claim.		Security Context identified by the "kid" value in the cnf claim. The
	The RS MUST respond with a 2.01 (Created) response protected with the		RS MUST respond with a 2.01 (Created) response protected with the
	same Security Context, with no payload. If any verification fails,		same Security Context, with no payload. If any verification fails,
	the RS MUST respond with a 4.01 (Unauthorized) error response.		the RS MUST respond with a 4.01 (Unauthorized) error response.
	As specified in section 5.8.1 of [I-D.ietf-ace-oauth-authz], when		As specified in Section 5.8.1 of [RFC9200], when receiving an updated
	receiving an updated access token with updated authorization		access token with updated authorization information from the client
	information from the client (see Section 3.1), it is recommended that		(see Section 3.1), it is recommended that the RS overwrites the
	the RS overwrites the previous token, that is only the latest		previous token; that is, only the latest authorization information in
	authorization information in the token received by the RS is valid.		the token received by the RS is valid. This simplifies the process
	This simplifies the process needed by the RS to keep track of		needed by the RS to keep track of authorization information for a
	authorization information for a given client.		given client.
	4.2.1. The Nonce 2 Parameter		4.2.1. The Nonce 2 Parameter
	This parameter MUST be sent from the RS to the client if the ace		The nonce 2 parameter MUST be sent from the RS to the client if the
	profile used is coap_oscore, and the message is not a response to an		ACE profile used is "coap_oscore" and the message is not a response
	update of access rights, protected with an existing OSCORE Security		to an update of access rights, protected with an existing OSCORE
	Context. The parameter is encoded as a byte string for CBOR-based		Security Context. The parameter is encoded as a byte string for
	interactions, and as a string (Base64 encoded binary) for JSON-based		CBOR-based interactions and as a string (base64-encoded binary) for
	interactions. This parameter is registered in Section 9.2		JSON-based interactions. This parameter is registered in Section 9.2
	4.2.2. The ace_server_recipientid Parameter		4.2.2. The ace_server_recipientid Parameter
	This parameter MUST be sent from the RS to the client if the ace		The ace_server_recipientid parameter MUST be sent from the RS to the
	profile used is coap_oscore, and the message is not a response to an		client if the ACE profile used is "coap_oscore" and the message is
	update of access rights, protected with an existing OSCORE Security		not a response to an update of access rights, protected with an
	Context. The parameter is encoded as a byte string for CBOR-based		existing OSCORE Security Context. The parameter is encoded as a byte
	interactions, and as a string (Base64 encoded binary) for JSON-based		string for CBOR-based interactions and as a string (base64-encoded
	interactions. This parameter is registered in Section 9.2		binary) for JSON-based interactions. This parameter is registered in
			Section 9.2
	4.3. OSCORE Setup		4.3. OSCORE Setup
	Once the 2.01 (Created) response is received from the RS, following		Once the 2.01 (Created) response is received from the RS, following
	the POST request to authz-info endpoint, the client MUST extract the		the POST request to authz-info endpoint, the client MUST extract the
	bstr nonce N2 from the "nonce2" parameter in the CBOR map in the		bstr nonce N2 from the nonce2 parameter in the CBOR map in the
	payload of the response. Then, the client MUST set the Master Salt		payload of the response. Then, the client MUST set the Master Salt
	of the Security Context created to communicate with the RS to the		of the Security Context created to communicate with the RS to the
	concatenation of salt, N1, and N2, in this order: Master Salt =		concatenation of salt, N1, and N2 in this order: Master Salt = salt |
	salt | N1 | N2, where | denotes byte string concatenation, where salt		N1 | N2, where | denotes byte string concatenation, salt is the CBOR
	is the CBOR byte string received from the AS in Section 3.2, and		byte string received from the AS in Section 3.2, and N1 and N2 are
	where N1 and N2 are the two nonces encoded as CBOR byte strings. An		the two nonces encoded as CBOR byte strings. An example of Master
	example of Master Salt construction using CBOR encoding is given in		Salt construction using CBOR encoding is given in Figure 12.
	Figure 12.
	N1, N2 and input salt expressed in CBOR diagnostic notation:		N1, N2 and input salt expressed in CBOR diagnostic notation:
	nonce1 = h'018a278f7faab55a'		nonce1 = h'018a278f7faab55a'
	nonce2 = h'25a8991cd700ac01'		nonce2 = h'25a8991cd700ac01'
	input salt = h'f9af838368e353e78888e1426bd94e6f'		input salt = h'f9af838368e353e78888e1426bd94e6f'
	N1, N2 and input salt as CBOR encoded byte strings:		N1, N2 and input salt as CBOR encoded byte strings:
	nonce1 = 0x48018a278f7faab55a		nonce1 = 0x48018a278f7faab55a
	nonce2 = 0x4825a8991cd700ac01		nonce2 = 0x4825a8991cd700ac01
	input salt = 0x50f9af838368e353e78888e1426bd94e6f		input salt = 0x50f9af838368e353e78888e1426bd94e6f
	Master Salt = 0x50 f9af838368e353e78888e1426bd94e6f		Master Salt = 0x50 f9af838368e353e78888e1426bd94e6f
	48 018a278f7faab55a 48 25a8991cd700ac01		48 018a278f7faab55a 48 25a8991cd700ac01
	Figure 12: Example of Master Salt construction using CBOR encoding		Figure 12: Example of Master Salt Construction Using CBOR Encoding
	If JSON is used instead of CBOR, the Master Salt of the Security		If JSON is used instead of CBOR, the Master Salt of the Security
	Context is the Base64 encoding of the concatenation of the same		Context is the base64 encoding of the concatenation of the same
	parameters, each of them prefixed by their size, encoded in 1 byte.		parameters, each of them prefixed by their size, encoded in 1 byte.
	When using JSON, the nonces and input salt have a maximum size of 255		When using JSON, the nonces and input salt have a maximum size of 255
	bytes. An example of Master Salt construction using Base64 encoding		bytes. An example of Master Salt construction using base64 encoding
	is given in Figure 13.		is given in Figure 13.
	N1, N2 and input salt values:		N1, N2 and input salt values:
	nonce1 = 0x018a278f7faab55a (8 bytes)		nonce1 = 0x018a278f7faab55a (8 bytes)
	nonce2 = 0x25a8991cd700ac01 (8 bytes)		nonce2 = 0x25a8991cd700ac01 (8 bytes)
	input salt = 0xf9af838368e353e78888e1426bd94e6f (16 bytes)		input salt = 0xf9af838368e353e78888e1426bd94e6f (16 bytes)
	Input to Base64 encoding: 0x10 f9af838368e353e78888e1426bd94e6f		Input to Base64 encoding: 0x10 f9af838368e353e78888e1426bd94e6f
	08 018a278f7faab55a 08 25a8991cd700ac01		08 018a278f7faab55a 08 25a8991cd700ac01
	Master Salt = b64'EPmvg4No41PniIjhQmvZTm8IAYonj3+qtVoIJaiZHNcArAE='		Master Salt = b64'EPmvg4No41PniIjhQmvZTm8IAYonj3+qtVoIJaiZHNcArAE='
	Figure 13: Example of Master Salt construction using Base64 encoding		Figure 13: Example of Master Salt Construction Using Base64 Encoding
	The client MUST set the Sender ID to the ace_server_recipientid		The client MUST set the Sender ID to the ace_server_recipientid
	received in Section 4.2, and the Recipient ID to the		received in Section 4.2 and set the Recipient ID to the
	ace_client_recipientid sent in Section 4.1. The client MUST set the		ace_client_recipientid sent in Section 4.1. The client MUST set the
	Master Secret from the parameter received from the AS in Section 3.2.		Master Secret from the parameter received from the AS in Section 3.2.
	The client MUST set the AEAD Algorithm, ID Context, HKDF, and OSCORE		The client MUST set the AEAD algorithm, ID Context, HKDF, and OSCORE
	Version from the parameters received from the AS in Section 3.2, if		version from the parameters received from the AS in Section 3.2, if
	present. In case an optional parameter is omitted, the default value		present. In case an optional parameter is omitted, the default value
	SHALL be used as described in sections 3.2 and 5.4 of [RFC8613].		SHALL be used as described in Sections 3.2 and 5.4 of [RFC8613].
	After that, the client MUST derive the complete Security Context		After that, the client MUST derive the complete Security Context
	following section 3.2.1 of [RFC8613]. From this point on, the client		following Section 3.2.1 of [RFC8613]. From this point on, the client
	MUST use this Security Context to communicate with the RS when		MUST use this Security Context to communicate with the RS when
	accessing the resources as specified by the authorization		accessing the resources as specified by the authorization
	information.		information.
	If any of the expected parameters is missing (e.g., any of the		If any of the expected parameters are missing (e.g., any of the
	mandatory parameters from the AS or the RS), or if		mandatory parameters from the AS or the RS), or if
	ace_client_recipientid equals ace_server_recipientid (and as a		ace_client_recipientid equals ace_server_recipientid (and as a
	consequence the Sender and Recipient Keys derived would be equal, see		consequence, the Sender and Recipient Keys derived would be equal;
	section 3.3 of [RFC8613]), then the client MUST stop the exchange,		see Section 3.3 of [RFC8613]), then the client MUST stop the exchange
	and MUST NOT derive the Security Context. The client MAY restart the		and MUST NOT derive the Security Context. The client MAY restart the
	exchange, to get the correct security material.		exchange, to get the correct security material.
	The client then uses this Security Context to send requests to the RS		The client then uses this Security Context to send requests to the RS
	using OSCORE.		using OSCORE.
	After sending the 2.01 (Created) response, the RS MUST set the Master		After sending the 2.01 (Created) response, the RS MUST set the Master
	Salt of the Security Context created to communicate with the client		Salt of the Security Context created to communicate with the client
	to the concatenation of salt, N1, and N2, in the same way described		to the concatenation of salt, N1, and N2 in the same way described
	above. An example of Master Salt construction using CBOR encoding is		above. An example of Master Salt construction using CBOR encoding is
	given in Figure 12 and using Base64 encoding is given in Figure 13.		given in Figure 12 and using base64 encoding is given in Figure 13.
	The RS MUST set the Sender ID from the ace_client_recipientid		The RS MUST set the Sender ID from the ace_client_recipientid
	received in Section 4.1, and the Recipient ID from the		received in Section 4.1 and set the Recipient ID from the
	ace_server_recipientid sent in Section 4.2. The RS MUST set the		ace_server_recipientid sent in Section 4.2. The RS MUST set the
	Master Secret from the parameter received from the AS and forwarded		Master Secret from the parameter received from the AS and forwarded
	by the client in the access token in Section 4.1 after validation of		by the client in the access token in Section 4.1 after validation of
	the token as specified in Section 4.2. The RS MUST set the AEAD		the token as specified in Section 4.2. The RS MUST set the AEAD
	Algorithm, ID Context, HKDF, and OSCORE Version from the parameters		algorithm, ID Context, HKDF, and OSCORE version from the parameters
	received from the AS and forwarded by the client in the access token		received from the AS and forwarded by the client in the access token
	in Section 4.1 after validation of the token as specified in		in Section 4.1 after validation of the token as specified in
	Section 4.2, if present. In case an optional parameter is omitted,		Section 4.2, if present. In case an optional parameter is omitted,
	the default value SHALL be used as described in sections 3.2 and 5.4		the default value SHALL be used as described in Sections 3.2 and 5.4
	of [RFC8613]. After that, the RS MUST derive the complete Security		of [RFC8613]. After that, the RS MUST derive the complete Security
	Context following section 3.2.1 of [RFC8613], and MUST associate this		Context following Section 3.2.1 of [RFC8613] and MUST associate this
	Security Context with the authorization information from the access		Security Context with the authorization information from the access
	token.		token.
	The RS then uses this Security Context to verify requests and send		The RS then uses this Security Context to verify requests and send
	responses to the client using OSCORE. If OSCORE verification fails,		responses to the client using OSCORE. If OSCORE verification fails,
	error responses are used, as specified in section 8 of [RFC8613].		error responses are used, as specified in Section 8 of [RFC8613].
	Additionally, if OSCORE verification succeeds, the verification of		Additionally, if OSCORE verification succeeds, the verification of
	access rights is performed as described in section Section 4.4. The		access rights is performed as described in Section 4.4. The RS MUST
	RS MUST NOT use the Security Context after the related token has		NOT use the Security Context after the related token has expired and
	expired, and MUST respond with a unprotected 4.01 (Unauthorized)		MUST respond with an unprotected 4.01 (Unauthorized) error message to
	error message to requests received that correspond to a Security		requests received that correspond to a Security Context with an
	Context with an expired token.		expired token.
	Note that the ID Context can be assigned by the AS, communicated and		Note that the ID Context can be assigned by the AS, communicated and
	set in both the RS and client after the exchange specified in this		set in both the RS and client after the exchange specified in this
	profile is executed. Subsequently, client and RS can update their ID		profile is executed. Subsequently, the client and RS can update
	Context by running a mechanism such as the one defined in		their ID Context by running a mechanism such as the one defined in
	Appendix B.2 of [RFC8613] if they both support it and are configured		Appendix B.2 of [RFC8613] if they both support it and are configured
	to do so. In that case, the ID Context in the OSCORE Security		to do so. In that case, the ID Context in the OSCORE Security
	Context will not match the "contextId" parameter of the corresponding		Context will not match the contextId parameter of the corresponding
	OSCORE_Input_Material. Running Appendix B.2 results in the keying		OSCORE_Input_Material. Running Appendix B.2 results in the keying
	material in the Security Contexts of client and RS being updated;		material being updated in the Security Contexts of the client and RS;
	this same result can also be achieved by the client reposting the		this same result can also be achieved by the client reposting the
	access token to the unprotected /authz-info endpoint at the RS, as		access token to the unprotected /authz-info endpoint at the RS, as
	described in Section 4.1, but without updating the ID Context.		described in Section 4.1, but without updating the ID Context.
	4.4. Access rights verification		4.4. Access Rights Verification
	The RS MUST follow the procedures defined in section 5.8.2 of		The RS MUST follow the procedures defined in Section 5.8.2 of
	[I-D.ietf-ace-oauth-authz]: if an RS receives an OSCORE-protected		[RFC9200]: if an RS receives an OSCORE-protected request from a
	request from a client, then the RS processes it according to		client, then the RS processes it according to [RFC8613]. If OSCORE
	[RFC8613]. If OSCORE verification succeeds, and the target resource		verification succeeds, and the target resource requires
	requires authorization, the RS retrieves the authorization		authorization, the RS retrieves the authorization information using
	information using the access token associated to the Security		the access token associated to the Security Context. The RS then
	Context. The RS then must verify that the authorization information		must verify that the authorization information covers the resource
	covers the resource and the action requested.		and the action requested.
	5. Secure Communication with AS		5. Secure Communication with AS
	As specified in the ACE framework (section 5.9 of		As specified in the ACE framework (Section 5.9 of [RFC9200]), the
	[I-D.ietf-ace-oauth-authz]), the requesting entity (RS and/or client)		requesting entity (RS and/or client) and the AS communicates via the
	and the AS communicates via the introspection or token endpoint. The		introspection or token endpoint. The use of CoAP and OSCORE
	use of CoAP and OSCORE ([RFC8613]) for this communication is		[RFC8613] for this communication is RECOMMENDED in this profile;
	RECOMMENDED in this profile; other protocols fulfilling the security		other protocols fulfilling the security requirements defined in
	requirements defined in section 5 of [I-D.ietf-ace-oauth-authz] (such		Section 5 of [RFC9200] (such as HTTP and DTLS or TLS) MAY be used
	as HTTP and DTLS or TLS) MAY be used instead.		instead.
	If OSCORE is used, the requesting entity and the AS are expected to		If OSCORE is used, the requesting entity and the AS are expected to
	have pre-established security contexts in place. How these security		have preestablished security contexts in place. How these security
	contexts are established is out of scope for this profile.		contexts are established is out of scope for this profile.
	Furthermore the requesting entity and the AS communicate through the		Furthermore, the requesting entity and the AS communicate through the
	introspection endpoint as specified in section 5.9 of		introspection endpoint as specified in Section 5.9 of [RFC9200] and
	[I-D.ietf-ace-oauth-authz] and through the token endpoint as		through the token endpoint as specified in Section 5.8 of [RFC9200].
	specified in section 5.8 of [I-D.ietf-ace-oauth-authz].
	6. Discarding the Security Context		6. Discarding the Security Context
	There are a number of scenarios where a client or RS needs to discard		There are a number of scenarios where a client or RS needs to discard
	the OSCORE security context, and acquire a new one.		the OSCORE security context and acquire a new one.
	The client MUST discard the current Security Context associated with		The client MUST discard the current Security Context associated with
	an RS when any of the following occurs:		an RS when any of the following occurs:
	* the Sequence Number space ends.		* the sequence number space ends.
	* the access token associated with the context becomes invalid due		* the access token associated with the context becomes invalid due
	to, for example, expiration.		to, for example, expiration.
	* the client receives a number of 4.01 Unauthorized responses to		* the client receives a number of 4.01 Unauthorized responses to
	OSCORE requests using the same Security Context. The exact number		OSCORE requests using the same Security Context. The exact number
	needs to be specified by the application.		needs to be specified by the application.
	* the client receives a new nonce in the 2.01 (Created) response		* the client receives a new nonce in the 2.01 (Created) response
	(see Section 4.2) to a POST request to the authz-info endpoint,		(see Section 4.2) to a POST request to the authz-info endpoint,
	when re-posting a (non-expired) token associated to the existing		when reposting a (non-expired) token associated to the existing
	context.		context.
	The RS MUST discard the current Security Context associated with a		The RS MUST discard the current Security Context associated with a
	client when any of the following occurs:		client when any of the following occurs:
	* the Sequence Number space ends.		* the sequence number space ends.
	* the access token associated with the context expires.		* the access token associated with the context expires.
	* the client has successfully replaced the current security context		* the client has successfully replaced the current security context
	with a newer one by posting an access token to the unprotected		with a newer one by posting an access token to the unprotected
	/authz-info endpoint at the RS, e.g., by re-posting the same		/authz-info endpoint at the RS, e.g., by reposting the same token,
	token, as specified in Section 4.1.		as specified in Section 4.1.
	Whenever one more access token is successfully posted to the RS, and		Whenever one more access token is successfully posted to the RS, and
	a new Security Context is derived between the client and RS, messages		a new Security Context is derived between the client and RS, messages
	in transit that were protected with the previous Security Context		in transit that were protected with the previous Security Context
	might not pass verification, as the old context is discarded. That		might not pass verification, as the old context is discarded. That
	means that messages sent shortly before the client posts one more		means that messages sent shortly before the client posts one more
	access token to the RS might not successfully reach the destination.		access tokens to the RS might not successfully reach the destination.
	Analogously, implementations may want to cancel CoAP observations at		Analogously, implementations may want to cancel CoAP observations at
	the RS registered before the Security Context is replaced, or		the RS registered before the Security Context is replaced, or
	conversely they will need to implement a mechanism to ensure that		conversely, they will need to implement a mechanism to ensure that
	those observations are to be protected with the newly derived		those observations are to be protected with the newly derived
	Security Context.		Security Context.
	7. Security Considerations		7. Security Considerations
	This document specifies a profile for the Authentication and		This document specifies a profile for the ACE framework [RFC9200].
	Authorization for Constrained Environments (ACE) framework		Thus, the general security considerations from the framework also
	[I-D.ietf-ace-oauth-authz]. Thus the general security considerations		apply to this profile.
	from the framework also apply to this profile.
	Furthermore the general security considerations of OSCORE [RFC8613]		Furthermore, the general security considerations of OSCORE [RFC8613]
	also apply to this specific use of the OSCORE protocol.		also apply to this specific use of the OSCORE protocol.
	As previously stated, the proof-of-possession in this profile is		As previously stated, the proof of possession in this profile is
	performed by both parties verifying that they have established the		performed by both parties verifying that they have established the
	same Security Context, as specified in Section 4.3, which means that		same Security Context, as specified in Section 4.3, which means that
	both the OSCORE request and the OSCORE response passes verification.		both the OSCORE request and the OSCORE response passes verification.
	RS authentication requires both that the client trusts the AS and		RS authentication requires both that the client trusts the AS and
	that the OSCORE response from the RS passes verification.		that the OSCORE response from the RS passes verification.
	OSCORE is designed to secure point-to-point communication, providing		OSCORE is designed to secure point-to-point communication, providing
	a secure binding between the request and the response(s). Thus the		a secure binding between the request and the response(s). Thus, the
	basic OSCORE protocol is not intended for use in point-to-multipoint		basic OSCORE protocol is not intended for use in point-to-multipoint
	communication (e.g., multicast, publish-subscribe). Implementers of		communication (e.g., multicast, publish-subscribe). Implementers of
	this profile should make sure that their use case corresponds to the		this profile should make sure that their use case corresponds to the
	expected use of OSCORE, to prevent weakening the security assurances		expected use of OSCORE, to prevent weakening the security assurances
	provided by OSCORE.		provided by OSCORE.
	Since the use of nonces N1 and N2 during the exchange guarantees		Since the use of nonces N1 and N2 during the exchange guarantees
	uniqueness of AEAD keys and nonces, it is REQUIRED that the exchanged		uniqueness of AEAD keys and nonces, it is REQUIRED that the exchanged
	nonces are not reused with the same input keying material even in		nonces are not reused with the same input keying material even in
	case of re-boots. This document RECOMMENDS the exchange of 64 bit		case of reboots. The exchange of 64-bit random nonces is RECOMMENDED
	random nonces. Considering the birthday paradox, the average		in this document. Considering the birthday paradox, the average
	collision for each nonce will happen after 2^32 messages, which is		collision for each nonce will happen after 2^32 messages, which is
	considerably more token provisioned than would be expected for		considerably more token provisionings than would be expected for
	intended applications. If applications use something else, such as a		intended applications. If applications use something else, such as a
	counter, they need to guarantee that reboot and loss of state on		counter, they need to guarantee that reboot and loss of state on
	either node does not provoke reuse. If that is not guaranteed, nodes		either node does not provoke reuse. If that is not guaranteed, nodes
	are susceptible to reuse of AEAD (nonce, key) pairs, especially since		are susceptible to reuse of AEAD (nonce, key) pairs, especially since
	an on-path attacker can cause the use of a previously exchanged		an on-path attacker can cause the use of a previously exchanged
	client nonce N1 for Security Context establishment by replaying the		client nonce N1 for Security Context establishment by replaying the
	corresponding client-to-server message.		corresponding client-to-server message.
	This profile RECOMMENDS that the RS maintains a single access token		In this profile, it is RECOMMENDED that the RS maintains a single
	for each client. The use of multiple access tokens for a single		access token for each client. The use of multiple access tokens for
	client increases the strain on the resource server as it must		a single client increases the strain on the resource server as it
	consider every access token and calculate the actual permissions of		must consider every access token and calculate the actual permissions
	the client. Also, tokens indicating different or disjoint		of the client. Also, tokens indicating different or disjoint
	permissions from each other may lead the server to enforce wrong		permissions from each other may lead the server to enforce wrong
	permissions. If one of the access tokens expires earlier than		permissions. If one of the access tokens expires earlier than
	others, the resulting permissions may offer insufficient protection.		others, the resulting permissions may offer insufficient protection.
	Developers SHOULD avoid using multiple access tokens for a same		Developers SHOULD avoid using multiple access tokens for the same
	client.		client.
	If a single OSCORE Input Material is used with multiple RSs, the RSs		If a single OSCORE Input Material is used with multiple RSs, the RSs
	can impersonate the client to one of the other RS, and impersonate		can impersonate the client to one of the other RSs and impersonate
	another RS to the client. If a master secret is used with several		another RS to the client. If a Master Secret is used with several
	clients, the clients can impersonate RS to one of the other clients.		clients, the clients can impersonate RS to one of the other clients.
			Similarly, if symmetric keys are used to integrity protect the token
	Similarly if symmetric keys are used to integrity protect the token
	between AS and RS and the token can be used with multiple RSs, the		between AS and RS and the token can be used with multiple RSs, the
	RSs can impersonate AS to one of the other RS. If the token key is		RSs can impersonate AS to one of the other RSs. If the token key is
	used for any other communication between the RSs and AS, the RSs can		used for any other communication between the RSs and AS, the RSs can
	impersonate each other to the AS.		impersonate each other to the AS.
	8. Privacy Considerations		8. Privacy Considerations
	This document specifies a profile for the Authentication and		This document specifies a profile for the ACE framework [RFC9200].
	Authorization for Constrained Environments (ACE) framework		Thus, the general privacy considerations from the framework also
	[I-D.ietf-ace-oauth-authz]. Thus the general privacy considerations		apply to this profile.
	from the framework also apply to this profile.
	As this document uses OSCORE, thus the privacy considerations from		As this document uses OSCORE, the privacy considerations from
	[RFC8613] apply here as well.		[RFC8613] apply here as well.
	An unprotected response to an unauthorized request may disclose		An unprotected response to an unauthorized request may disclose
	information about the resource server and/or its existing		information about the resource server and/or its existing
	relationship with the client. It is advisable to include as little		relationship with the client. It is advisable to include as little
	information as possible in an unencrypted response. When an OSCORE		information as possible in an unencrypted response. When an OSCORE
	Security Context already exists between the client and the resource		Security Context already exists between the client and the resource
	server, more detailed information may be included.		server, more detailed information may be included.
	The token is sent in the clear to the authz-info endpoint, so if a		The token is sent in the clear to the authz-info endpoint, so if a
	client uses the same single token from multiple locations with		client uses the same single token from multiple locations with
	multiple Resource Servers, it can risk being tracked by the token's		multiple resource servers, it can risk being tracked by the token's
	value even when the access token is encrypted.		value even when the access token is encrypted.
	The nonces exchanged in the request and response to the authz-info		The nonces exchanged in the request and response to the authz-info
	endpoint are also sent in the clear, so using random nonces is best		endpoint are also sent in the clear, so using random nonces is best
	for privacy (as opposed to, e.g., a counter, that might leak some		for privacy (as opposed to, e.g., a counter, which might leak some
	information about the client).		information about the client).
	The identifiers used in OSCORE, negotiated between client and RS are		The identifiers used in OSCORE, negotiated between the client and RS,
	privacy sensitive (see Section 12.8 of [RFC8613]), and could reveal		are privacy sensitive (see Section 12.8 of [RFC8613]) and could
	information about the client, or may be used for correlating requests		reveal information about the client, or they may be used for
	from one client.		correlating requests from one client.
	Note that some information might still leak after OSCORE is		Note that some information might still leak after OSCORE is
	established, due to observable message sizes, the source, and the		established, due to observable message sizes, the source, and the
	destination addresses.		destination addresses.
	9. IANA Considerations		9. IANA Considerations
	Note to RFC Editor: Please replace all occurrences of "[[this
	document]]" with the RFC number of this document. Please add a
	reference to the IANA ACE Profile registry in the nextt subsection
	once it has been created by IANA, and then delete this paragraph.
	9.1. ACE Profile Registry		9.1. ACE Profile Registry
	The following registration is done for the ACE Profile Registry		The following registration has been made in the "ACE Profiles"
	following the procedure specified in section 8.8 of		registry following the procedure specified in Section 8.8 of
	[I-D.ietf-ace-oauth-authz]:		[RFC9200]:
	* Name: coap_oscore		Name: coap_oscore
	* Description: Profile for using OSCORE to secure communication		Description: Profile for using OSCORE to secure communication
	between constrained nodes using the Authentication and		between constrained nodes using the Authentication and
	Authorization for Constrained Environments framework.		Authorization for Constrained Environments framework.
	* CBOR Value: TBD (value between 1 and 255)		CBOR Value: 2
	* Reference: [[this document]]		Reference: RFC 9203
	9.2. OAuth Parameters Registry		9.2. OAuth Parameters Registry
	The following registrations are done for the OAuth Parameters		The following registrations have been made in the "OAuth Parameters"
	Registry [IANA.OAuthParameters] following the procedure specified in		registry [IANA.OAuthParameters] following the procedure specified in
	section 11.2 of [RFC6749]:		Section 11.2 of [RFC6749]:
	* Parameter name: nonce1		Parameter name: nonce1
	* Parameter usage location: client-rs request		Parameter usage location: client-rs request
	* Change Controller: IESG		Change Controller: IETF
	* Specification Document(s): [[this document]]		Specification Document(s): RFC 9203
	* Parameter name: nonce2		Parameter name: nonce2
	* Parameter usage location: rs-client response		Parameter usage location: rs-client response
	* Change Controller: IESG		Change Controller: IETF
	* Specification Document(s): [[this document]]		Specification Document(s): RFC 9203
	* Parameter name: ace_client_recipientid		Parameter name: ace_client_recipientid
	* Parameter usage location: client-rs request		Parameter usage location: client-rs request
	* Change Controller: IESG		Change Controller: IETF
	* Specification Document(s): [[this document]]		Specification Document(s): RFC 9203
	* Parameter name: ace_server_recipientid		Parameter name: ace_server_recipientid
	* Parameter usage location: rs-client response		Parameter usage location: rs-client response
	* Change Controller: IESG		Change Controller: IETF
	* Specification Document(s): [[this document]]		Specification Document(s): RFC 9203
	9.3. OAuth Parameters CBOR Mappings Registry		9.3. OAuth Parameters CBOR Mappings Registry
	The following registrations are done for the OAuth Parameters CBOR		The following registrations have been made in the "OAuth Parameters
	Mappings Registry following the procedure specified in section 8.10		CBOR Mappings" registry following the procedure specified in
	of [I-D.ietf-ace-oauth-authz]:		Section 8.10 of [RFC9200]:
	* Name: nonce1		Name: nonce1
	* CBOR Key: TBD1		CBOR Key: 40
	* Value Type: bstr		Value Type: bstr
	* Reference: [[this document]]		Reference: RFC 9203
			Original Specification: RFC 9203
	* Name: nonce2		Name: nonce2
	* CBOR Key: TBD2		CBOR Key: 42
	* Value Type: bstr		Value Type: bstr
	* Reference: [[this document]]		Reference: RFC 9203
			Original Specification: RFC 9203
	* Name: ace_client_recipientid		Name: ace_client_recipientid
	* CBOR Key: TBD3		CBOR Key: 43
	* Value Type: bstr		Value Type: bstr
	* Reference: [[this document]]		Reference: RFC 9203
			Original Specification: RFC 9203
	* Name: ace_server_recipientid		Name: ace_server_recipientid
	* CBOR Key: TBD4		CBOR Key: 44
	* Value Type: bstr		Value Type: bstr
	* Reference: [[this document]]		Reference: RFC 9203
			Original Specification: RFC 9203
	9.4. OSCORE Security Context Parameters Registry		9.4. OSCORE Security Context Parameters Registry
	It is requested that IANA create a new registry entitled "OSCORE		IANA has created a new registry entitled "OSCORE Security Context
	Security Context Parameters" registry. The registry is to be created		Parameters". The registration procedure is Expert Review [RFC8126].
	as Expert Review Required. Guidelines for the experts is provided		Guidelines for the experts are provided in Section 9.7. It should be
	Section 9.7. It should be noted that in addition to the expert		noted that in addition to the Expert Review, some portions of the
	review, some portions of the registry require a specification,		registry require a specification, potentially on the Standards Track,
	potentially on standards track, be supplied as well.		be supplied as well.
	The columns of the registry are:		The columns of the registry are:
	name The JSON name requested (e.g., "ms"). Because a core goal of		Name: The JSON name requested (e.g., "ms"). Because a core goal of
	this document is for the resulting representations to be compact,		this document is for the resulting representations to be compact,
	it is RECOMMENDED that the name be short. This name is case		it is RECOMMENDED that the name be short. This name is case
	sensitive. Names may not match other registered names in a case-		sensitive. Names may not match other registered names in a case-
	insensitive manner unless the Designated Experts determine that		insensitive manner unless the designated experts determine that
	there is a compelling reason to allow an exception. The name is		there is a compelling reason to allow an exception. The name is
	not used in the CBOR encoding.		not used in the CBOR encoding.
	CBOR label The value to be used to identify this algorithm. Map key
	labels MUST be unique. The label can be a positive integer, a		CBOR Label: The value to be used to identify this algorithm. Map
	negative integer or a string. Integer values between -256 and 255		key labels MUST be unique. The label can be a positive integer, a
	and strings of length 1 are designated as Standards Track Document		negative integer, or a string. Integer values between -256 and
	required. Integer values from -65536 to -257 and from 256 to		255 and strings of length 1 are designated as Standards Track
	65535 and strings of length 2 are designated as Specification		document required. Integer values from -65536 to -257 and from
	Required. Integer values greater than 65535 and strings of length		256 to 65535 and strings of length 2 are designated as
	greater than 2 are designated as expert review. Integer values		Specification Required. Integer values greater than 65535 and
	less than -65536 are marked as private use.		strings of length greater than 2 are designated as Expert Review.
	CBOR Type This field contains the CBOR type for the field.		Integer values less than -65536 are marked as Private Use.
	registry This field denotes the registry that values may come from,
			CBOR Type: This field contains the CBOR type for the field.
			Registry: This field denotes the registry that values may come from,
	if one exists.		if one exists.
	description This field contains a brief description for the field.
	specification This contains a pointer to the public specification		Description: This field contains a brief description for the field.
	for the field if one exists
	This registry will be initially populated by the values in Table 1.		Reference: This contains a pointer to the public specification for
	The specification column for all of these entries will be this		the field, if one exists.
	document and [RFC8613].
			This registry has been initially populated by the values in Table 1.
			The Reference column for all of these entries is this document and
			[RFC8613].
	9.5. CWT Confirmation Methods Registry		9.5. CWT Confirmation Methods Registry
	The following registration is done for the CWT Confirmation Methods		The following registration has been made in the "CWT Confirmation
	Registry [IANA.CWTConfirmationMethods] following the procedure		Methods" registry [IANA.CWTConfirmationMethods] following the
	specified in section 7.2.1 of [RFC8747]:		procedure specified in Section 7.2.1 of [RFC8747]:
	* Confirmation Method Name: "osc"		Confirmation Method Name: "osc"
	* Confirmation Method Description: OSCORE_Input_Material carrying		Confirmation Method Description: OSCORE_Input_Material carrying the
	the parameters for using OSCORE per-message security with implicit		parameters for using OSCORE per-message security with implicit key
	key confirmation		confirmation
	* Confirmation Key: TBD (value between 4 and 255)		JWT Confirmation Method Name: osc
	* Confirmation Value Type(s): map		Confirmation Key: 4
	* Change Controller: IESG		Confirmation Value Type(s): map
	* Specification Document(s): Section 3.2.1 of [[this document]]		Change Controller: IETF
			Specification Document(s): Section 3.2.1 of RFC 9203
	9.6. JWT Confirmation Methods Registry		9.6. JWT Confirmation Methods Registry
	The following registration is done for the JWT Confirmation Methods		The following registration has been made in the "JWT Confirmation
	Registry [IANA.JWTConfirmationMethods] following the procedure		Methods" registry [IANA.JWTConfirmationMethods] following the
	specified in section 6.2.1 of [RFC7800]:		procedure specified in Section 6.2.1 of [RFC7800]:
	* Confirmation Method Value: "osc"		Confirmation Method Value: "osc"
	* Confirmation Method Description: OSCORE_Input_Material carrying		Confirmation Method Description: OSCORE_Input_Material carrying the
	the parameters for using OSCORE per-message security with implicit		parameters for using OSCORE per-message security with implicit key
	key confirmation		confirmation
	* Change Controller: IESG		Change Controller: IETF
	* Specification Document(s): Section 3.2.1 of [[this document]]		Specification Document(s): Section 3.2.1 of RFC 9203
	9.7. Expert Review Instructions		9.7. Expert Review Instructions
	The IANA registry established in this document is defined to use the		The IANA registry established in this document is defined to use the
	Expert Review registration policy. This section gives some general		Expert Review registration policy. This section gives some general
	guidelines for what the experts should be looking for, but they are		guidelines for what the experts should be looking for, but they are
	being designated as experts for a reason so they should be given		being designated as experts for a reason, so they should be given
	substantial latitude.		substantial latitude.
	Expert reviewers should take into consideration the following points:		Expert reviewers should take into consideration the following points:
	* Point squatting should be discouraged. Reviewers are encouraged		* Point squatting should be discouraged. Reviewers are encouraged
	to get sufficient information for registration requests to ensure		to get sufficient information for registration requests to ensure
	that the usage is not going to duplicate one that is already		that the usage is not going to duplicate one that is already
	registered and that the point is likely to be used in deployments.		registered and that the point is likely to be used in deployments.
	The zones tagged as private use are intended for testing purposes		The zones tagged as Private Use are intended for testing purposes
	and closed environments. Code points in other ranges should not		and closed environments. Code points in other ranges should not
	be assigned for testing.		be assigned for testing.
	* Specifications are required for the standards track range of point		* Specifications are required for the Standards Track range of point
	assignment. Specifications should exist for specification		assignment. Specifications should exist for specification
	required ranges, but early assignment before a specification is		required ranges, but early assignment before a specification is
	available is considered to be permissible. Specifications are		available is considered to be permissible. Specifications are
	needed for the first-come, first-serve range if they are expected		needed for the First Come First Served range if they are expected
	to be used outside of closed environments in an interoperable way.		to be used outside of closed environments in an interoperable way.
	When specifications are not provided, the description provided		When specifications are not provided, the description provided
	needs to have sufficient information to identify what the point is		needs to have sufficient information to identify what the point is
	being used for.		being used for.
	* Experts should take into account the expected usage of fields when		* Experts should take into account the expected usage of fields when
	approving point assignment. The fact that there is a range for		approving point assignment. The fact that there is a range for
	standards track documents does not mean that a standards track		Standards Track documents does not mean that a Standards Track
	document cannot have points assigned outside of that range. The		document cannot have points assigned outside of that range. The
	length of the encoded value should be weighed against how many		length of the encoded value should be weighed against how many
	code points of that length are left, the size of device it will be		code points of that length are left, the size of device it will be
	used on, and the number of code points left that encode to that		used on, and the number of code points left that encode to that
	size.		size.
	10. References		10. References
	10.1. Normative References		10.1. Normative References
	[COSE.Algorithms]		[COSE.Algorithms]
	IANA, "COSE Algorithms",		IANA, "COSE Algorithms",
	<https://www.iana.org/assignments/cose/		<https://www.iana.org/assignments/cose>.
	cose.xhtml#algorithms>.
	[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)", Work in Progress, Internet-Draft,
	draft-ietf-ace-oauth-authz-40, 26 April 2021,
	<https://www.ietf.org/archive/id/draft-ietf-ace-oauth-
	authz-40.txt>.
	[I-D.ietf-ace-oauth-params]
	Seitz, L., "Additional OAuth Parameters for Authorization
	in Constrained Environments (ACE)", Work in Progress,
	Internet-Draft, draft-ietf-ace-oauth-params-14, 25 March
	2021, <https://www.ietf.org/archive/id/draft-ietf-ace-
	oauth-params-14.txt>.
	[I-D.ietf-cose-rfc8152bis-algs]
	Schaad, J., "CBOR Object Signing and Encryption (COSE):
	Initial Algorithms", Work in Progress, Internet-Draft,
	draft-ietf-cose-rfc8152bis-algs-12, 24 September 2020,
	<https://www.ietf.org/archive/id/draft-ietf-cose-
	rfc8152bis-algs-12.txt>.
	[I-D.ietf-cose-rfc8152bis-struct]
	Schaad, J., "CBOR Object Signing and Encryption (COSE):
	Structures and Process", Work in Progress, Internet-Draft,
	draft-ietf-cose-rfc8152bis-struct-15, 1 February 2021,
	<https://www.ietf.org/archive/id/draft-ietf-cose-
	rfc8152bis-struct-15.txt>.
	[IANA.CWTConfirmationMethods]		[IANA.CWTConfirmationMethods]
	IANA, "CWT Confirmation Methods",		IANA, "CWT Confirmation Methods",
	<https://www.iana.org/assignments/cwt/		<https://www.iana.org/assignments/cwt>.
	cwt.xhtml#confirmation-methods>.
	[IANA.JWTConfirmationMethods]		[IANA.JWTConfirmationMethods]
	IANA, "JWT Confirmation Methods",		IANA, "JWT Confirmation Methods",
	<https://www.iana.org/assignments/jwt/		<https://www.iana.org/assignments/jwt>.
	jwt.xhtml#confirmation-methods>.
	[IANA.OAuthParameters]		[IANA.OAuthParameters]
	IANA, "OAuth Parameters",		IANA, "OAuth Parameters",
	<https://www.iana.org/assignments/oauth-parameters/oauth-		<https://www.iana.org/assignments/oauth-parameters>.
	parameters.xhtml#parameters>.
	[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>.
	[RFC5869] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand		[RFC5869] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand
	Key Derivation Function (HKDF)", RFC 5869,		Key Derivation Function (HKDF)", RFC 5869,
	DOI 10.17487/RFC5869, May 2010,		DOI 10.17487/RFC5869, May 2010,
	<https://www.rfc-editor.org/info/rfc5869>.		<https://www.rfc-editor.org/info/rfc5869>.
	skipping to change at page 32, line 25 ¶		skipping to change at line 1398 ¶
	[RFC8613] Selander, G., Mattsson, J., Palombini, F., and L. Seitz,		[RFC8613] Selander, G., Mattsson, J., Palombini, F., and L. Seitz,
	"Object Security for Constrained RESTful Environments		"Object Security for Constrained RESTful Environments
	(OSCORE)", RFC 8613, DOI 10.17487/RFC8613, July 2019,		(OSCORE)", RFC 8613, DOI 10.17487/RFC8613, July 2019,
	<https://www.rfc-editor.org/info/rfc8613>.		<https://www.rfc-editor.org/info/rfc8613>.
	[RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object		[RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object
	Representation (CBOR)", STD 94, RFC 8949,		Representation (CBOR)", STD 94, RFC 8949,
	DOI 10.17487/RFC8949, December 2020,		DOI 10.17487/RFC8949, December 2020,
	<https://www.rfc-editor.org/info/rfc8949>.		<https://www.rfc-editor.org/info/rfc8949>.
	10.2. Informative References		[RFC9052] Schaad, J., "CBOR Object Signing and Encryption (COSE):
			Structures and Process", RFC 9052, DOI 10.17487/RFC9052,
			March 2022, <https://www.rfc-editor.org/info/rfc9052>.
	[I-D.ietf-tls-dtls13]		[RFC9053] Schaad, J., "CBOR Object Signing and Encryption (COSE):
	Rescorla, E., Tschofenig, H., and N. Modadugu, "The		Initial Algorithms", RFC 9053, DOI 10.17487/RFC9053, March
	Datagram Transport Layer Security (DTLS) Protocol Version		2022, <https://www.rfc-editor.org/info/rfc9053>.
	1.3", Work in Progress, Internet-Draft, draft-ietf-tls-
	dtls13-43, 30 April 2021, <https://www.ietf.org/internet-		[RFC9200] Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and
	drafts/draft-ietf-tls-dtls13-43.txt>.		H. Tschofenig, "Authentication and Authorization for
			Constrained Environments (ACE) Using the OAuth 2.0
			Framework (ACE-OAuth)", RFC 9200, DOI 10.17487/RFC9200,
			September 2021, <https://www.rfc-editor.org/info/rfc9200>.
			[RFC9201] Seitz, L., "Additional OAuth Parameters for Authentication
			and Authorization for Constrained Environments (ACE)",
			RFC 9201, DOI 10.17487/RFC9201, September 2021,
			<https://www.rfc-editor.org/info/rfc9201>.
			10.2. Informative References
	[RFC4949] Shirey, R., "Internet Security Glossary, Version 2",		[RFC4949] Shirey, R., "Internet Security Glossary, Version 2",
	FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,		FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,
	<https://www.rfc-editor.org/info/rfc4949>.		<https://www.rfc-editor.org/info/rfc4949>.
	[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>.
	[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer		[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
	Protocol (HTTP/1.1): Semantics and Content", RFC 7231,		Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
	DOI 10.17487/RFC7231, June 2014,		DOI 10.17487/RFC7231, June 2014,
	<https://www.rfc-editor.org/info/rfc7231>.		<https://www.rfc-editor.org/info/rfc7231>.
	[RFC7800] Jones, M., Bradley, J., and H. Tschofenig, "Proof-of-		[RFC7800] Jones, M., Bradley, J., and H. Tschofenig, "Proof-of-
	Possession Key Semantics for JSON Web Tokens (JWTs)",		Possession Key Semantics for JSON Web Tokens (JWTs)",
	RFC 7800, DOI 10.17487/RFC7800, April 2016,		RFC 7800, DOI 10.17487/RFC7800, April 2016,
	<https://www.rfc-editor.org/info/rfc7800>.		<https://www.rfc-editor.org/info/rfc7800>.
			[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
			Writing an IANA Considerations Section in RFCs", BCP 26,
			RFC 8126, DOI 10.17487/RFC8126, June 2017,
			<https://www.rfc-editor.org/info/rfc8126>.
	[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol		[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
	Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,		Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
	<https://www.rfc-editor.org/info/rfc8446>.		<https://www.rfc-editor.org/info/rfc8446>.
	[RFC8747] Jones, M., Seitz, L., Selander, G., Erdtman, S., and H.		[RFC8747] Jones, M., Seitz, L., Selander, G., Erdtman, S., and H.
	Tschofenig, "Proof-of-Possession Key Semantics for CBOR		Tschofenig, "Proof-of-Possession Key Semantics for CBOR
	Web Tokens (CWTs)", RFC 8747, DOI 10.17487/RFC8747, March		Web Tokens (CWTs)", RFC 8747, DOI 10.17487/RFC8747, March
	2020, <https://www.rfc-editor.org/info/rfc8747>.		2020, <https://www.rfc-editor.org/info/rfc8747>.
			[RFC9147] Rescorla, E., Tschofenig, H., and N. Modadugu, "The
			Datagram Transport Layer Security (DTLS) Protocol Version
			1.3", RFC 9147, DOI 10.17487/RFC9147, March 2022,
			<https://www.rfc-editor.org/info/rfc9147>.
	Appendix A. Profile Requirements		Appendix A. Profile Requirements
	This section lists the specifications on this profile based on the		This section lists the specifications of this profile based on the
	requirements on the framework, as requested in Appendix C of		requirements of the framework, as requested in Appendix C of
	[I-D.ietf-ace-oauth-authz].		[RFC9200].
	* Optionally define new methods for the client to discover the		* Optionally, define new methods for the client to discover the
	necessary permissions and AS for accessing a resource, different		necessary permissions and AS for accessing a resource, different
	from the one proposed in: Not specified		from the one proposed in: Not specified
	* Optionally specify new grant types: Not specified		* Optionally, specify new grant types: Not specified
	* Optionally define the use of client certificates as client		* Optionally, define the use of client certificates as client
	credential type: Not specified		credential type: Not specified
	* Specify the communication protocol the client and RS the must use:		* Specify the communication protocol the client and RS must use:
	CoAP		CoAP
	* Specify the security protocol the client and RS must use to		* Specify the security protocol the client and RS must use to
	protect their communication: OSCORE		protect their communication: OSCORE
	* Specify how the client and the RS mutually authenticate:		* Specify how the client and the RS mutually authenticate:
	Implicitly by possession of a common OSCORE security context.		Implicitly by possession of a common OSCORE security context.
	Note that the mutual authentication is not completed before the		Note that the mutual authentication is not completed before the
	client has verified an OSCORE response using this security		client has verified an OSCORE response using this security
	context.		context.
	* Specify the proof-of-possession protocol(s) and how to select one,		* Specify the proof-of-possession protocol(s) and how to select one,
	if several are available. Also specify which key types (e.g.,		if several are available. Also specify which key types (e.g.,
	symmetric/asymmetric) are supported by a specific proof-of-		symmetric/asymmetric) are supported by a specific proof-of-
	possession protocol: OSCORE algorithms; pre-established symmetric		possession protocol: OSCORE algorithms; preestablished symmetric
	keys		keys
	* Specify a unique ace_profile identifier: coap_oscore		* Specify a unique ace_profile identifier: coap_oscore
	* If introspection is supported: Specify the communication and		* If introspection is supported, specify the communication and
	security protocol for introspection: HTTP/CoAP (+ TLS/DTLS/OSCORE)		security protocol for introspection: HTTP/CoAP (+ TLS/DTLS/OSCORE)
	* Specify the communication and security protocol for interactions		* Specify the communication and security protocol for interactions
	between client and AS: HTTP/CoAP (+ TLS/DTLS/OSCORE)		between client and AS: HTTP/CoAP (+ TLS/DTLS/OSCORE)
	* Specify how/if the authz-info endpoint is protected, including how		* Specify if/how the authz-info endpoint is protected, including how
	error responses are protected: Not protected.		error responses are protected: Not protected
	* Optionally define other methods of token transport than the authz-		* Optionally, define methods of token transport other than the
	info endpoint: Not defined		authz-info endpoint: Not defined
	Acknowledgments		Acknowledgments
	The authors wish to thank Jim Schaad and Marco Tiloca for the		The authors wish to thank Jim Schaad and Marco Tiloca for the
	substantial input to this document, as well as Elwyn Davies, Linda		substantial input to this document, as well as Elwyn Davies, Linda
	Dunbar, Roman Danyliw, Martin Duke, Lars Eggert, Murray Kucherawy,		Dunbar, Roman Danyliw, Martin Duke, Lars Eggert, Murray Kucherawy,
	and Zaheduzzaman Sarker for their reviews and feedback. Special		and Zaheduzzaman Sarker for their reviews and feedback. Special
	thanks to the responsible area director Benjamin Kaduk for his		thanks to the responsible area director Benjamin Kaduk for his
	extensive review and contributed text. Ludwig Seitz worked on this		extensive review and contributed text. Ludwig Seitz worked on this
	document as part of the CelticNext projects CyberWI, and CRITISEC		document as part of the CelticNext projects CyberWI and CRITISEC with
	with funding from Vinnova. The work on this document has been partly		funding from Vinnova. The work on this document has been partly
	supported also by the H2020 project SIFIS-Home (Grant agreement		supported also by the H2020 project SIFIS-Home (Grant agreement
	952652).		952652).
	Authors' Addresses		Authors' Addresses
	Francesca Palombini		Francesca Palombini
	Ericsson AB		Ericsson AB
	Email: francesca.palombini@ericsson.com		Email: francesca.palombini@ericsson.com
	Ludwig Seitz		Ludwig Seitz
	Combitech		Combitech
	Djaeknegatan 31		Djäknegatan 31
	SE-211 35 Malmoe		SE-211 35 Malmö
	Sweden		Sweden
	Email: ludwig.seitz@combitech.com		Email: ludwig.seitz@combitech.com
	Göran Selander		Göran Selander
	Ericsson AB		Ericsson AB
	Email: goran.selander@ericsson.com		Email: goran.selander@ericsson.com
	Martin Gunnarsson		Martin Gunnarsson
	RISE		RISE
	Scheelevagen 17		Scheelevagen 17
	SE-22370 Lund		SE-22370 Lund
	Sweden		Sweden
	Email: martin.gunnarsson@ri.se		Email: martin.gunnarsson@ri.se
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