draft-ietf-ace-oscore-profile-03.txt		draft-ietf-ace-oscore-profile-04.txt
	ACE Working Group L. Seitz		ACE Working Group F. Palombini
	Internet-Draft RISE SICS AB		Internet-Draft Ericsson AB
	Intended status: Standards Track F. Palombini		Intended status: Standards Track L. Seitz
	Expires: April 4, 2019 Ericsson AB		Expires: April 11, 2019 RISE SICS AB
	M. Gunnarsson
	RISE SICS AB
	G. Selander		G. Selander
	Ericsson AB		Ericsson AB
	October 1, 2018		M. Gunnarsson
			RISE SICS AB
			October 8, 2018
	OSCORE profile of the Authentication and Authorization for Constrained		OSCORE profile of the Authentication and Authorization for Constrained
	Environments Framework		Environments Framework
	draft-ietf-ace-oscore-profile-03		draft-ietf-ace-oscore-profile-04
	Abstract		Abstract
	This memo specifies a profile for the Authentication and		This memo 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, server authentication,		(OSCORE) to provide communication security, server authentication,
	and proof-of-possession for a key owned by the client and bound to an		and proof-of-possession for a key owned by the client and bound to an
	OAuth 2.0 access token.		OAuth 2.0 access token.
	skipping to change at page 1, line 41 ¶		skipping to change at page 1, line 41 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on April 4, 2019.		This Internet-Draft will expire on April 11, 2019.
	Copyright Notice		Copyright Notice
	Copyright (c) 2018 IETF Trust and the persons identified as the		Copyright (c) 2018 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 2, line 19 ¶		skipping to change at page 2, line 19 ¶
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3		1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 3		2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 3
	3. Client-AS Communication . . . . . . . . . . . . . . . . . . . 5		3. Client-AS Communication . . . . . . . . . . . . . . . . . . . 5
	3.1. C-to-AS: POST /token . . . . . . . . . . . . . . . . . . 5		3.1. C-to-AS: POST /token . . . . . . . . . . . . . . . . . . 5
	3.2. AS-to-C: Access Token . . . . . . . . . . . . . . . . . . 6		3.2. AS-to-C: Access Token . . . . . . . . . . . . . . . . . . 7
	4. Client-RS Communication . . . . . . . . . . . . . . . . . . . 11		4. Client-RS Communication . . . . . . . . . . . . . . . . . . . 11
	4.1. C-to-RS: POST /authz-info . . . . . . . . . . . . . . . . 11		4.1. C-to-RS: POST /authz-info . . . . . . . . . . . . . . . . 12
	4.2. RS-to-C: 2.01 (Created) . . . . . . . . . . . . . . . . . 11		4.2. RS-to-C: 2.01 (Created) . . . . . . . . . . . . . . . . . 12
	4.3. OSCORE Setup . . . . . . . . . . . . . . . . . . . . . . 12		4.3. OSCORE Setup . . . . . . . . . . . . . . . . . . . . . . 13
	4.4. Access rights verification . . . . . . . . . . . . . . . 13		4.4. Access rights verification . . . . . . . . . . . . . . . 15
	5. Secure Communication with AS . . . . . . . . . . . . . . . . 14		5. Secure Communication with AS . . . . . . . . . . . . . . . . 15
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 14		6. Security Considerations . . . . . . . . . . . . . . . . . . . 15
	7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 15		7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 16
	8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15		8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
	9. References . . . . . . . . . . . . . . . . . . . . . . . . . 16		9. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
	9.1. Normative References . . . . . . . . . . . . . . . . . . 16		9.1. Normative References . . . . . . . . . . . . . . . . . . 18
	9.2. Informative References . . . . . . . . . . . . . . . . . 17		9.2. Informative References . . . . . . . . . . . . . . . . . 19
	Appendix A. Profile Requirements . . . . . . . . . . . . . . . . 17		Appendix A. Profile Requirements . . . . . . . . . . . . . . . . 19
	Appendix B. Using the pop-key with EDHOC (EDHOC+OSCORE) . . . . 18		Appendix B. Using the pop-key with EDHOC (EDHOC+OSCORE) . . . . 20
	B.1. Using Asymmetric Keys . . . . . . . . . . . . . . . . . . 18		B.1. Using Asymmetric Keys . . . . . . . . . . . . . . . . . . 20
	B.2. Using Symmetric Keys . . . . . . . . . . . . . . . . . . 20		B.2. Using Symmetric Keys . . . . . . . . . . . . . . . . . . 22
	B.3. Processing . . . . . . . . . . . . . . . . . . . . . . . 22		B.3. Processing . . . . . . . . . . . . . . . . . . . . . . . 24
	Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 23		Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 25
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26
	1. Introduction		1. Introduction
	This memo specifies a profile of the ACE framework		This memo specifies a profile of the ACE framework
	[I-D.ietf-ace-oauth-authz]. In this profile, a client and a resource		[I-D.ietf-ace-oauth-authz]. In this profile, a client and a resource
	server use CoAP [RFC7252] to communicate. The client uses an access		server use CoAP [RFC7252] to communicate. The client uses an access
	token, bound to a key (the proof-of-possession key) to authorize its		token, bound to a key (the proof-of-possession key) to authorize its
	access to the resource server. In order to provide communication		access to the resource server. In order to provide communication
	security, proof of possession, and server authentication they use		security, proof of possession, and server authentication they use
	Object Security for Constrained RESTful Environments (OSCORE)		Object Security for Constrained RESTful Environments (OSCORE)
	skipping to change at page 3, line 36 ¶		skipping to change at page 3, line 36 ¶
	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.
	2. Protocol Overview		2. Protocol Overview
	This section gives an overview on how to use the ACE Framework		This section gives an overview on how to use the ACE Framework
	[I-D.ietf-ace-oauth-authz] to secure the communication between a		[I-D.ietf-ace-oauth-authz] to secure the communication between a
	client and a resource server using OSCORE		client and a resource server using OSCORE
	[I-D.ietf-core-object-security]. The parameters needed to negotiate		[I-D.ietf-core-object-security]. The parameters needed by the client
	the use of this profile with the token resource at the authorization		to negotiate the use of this profile with the authorization server,
	server as specified in section 5.6 of [I-D.ietf-ace-oauth-authz] are		as well as OSCORE setup process, are described in detail in the
	described in detail in the following sections.		following sections.
	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 a RS, using the token		AS for the resource it wants to access on a RS, using the token
	endpoint, as specified in section 5.6.1 of		resource, as specified in section 5.6 of [I-D.ietf-ace-oauth-authz].
	[I-D.ietf-ace-oauth-authz]. To determine the AS in charge of a		To determine the AS in charge of a resource hosted at the RS, the
	resource hosted at the RS, the client C MAY send an initial		client C MAY send an initial Unauthorized Resource Request message to
	Unauthorized Resource Request message to the RS. The RS then denies		the RS. The RS then denies the request and sends the address of its
	the request and sends the address of its AS back to the client C as		AS back to the client C as specified in section 5.1 of
	specified in section 5.1 of [I-D.ietf-ace-oauth-authz]. The access		[I-D.ietf-ace-oauth-authz]. The access token request and response
	token request and response MUST be confidentiality-protected and		MUST be confidentiality-protected and ensure authenticity. This
	ensure authenticity. This profile RECOMMENDS the use of OSCORE		profile RECOMMENDS the use of OSCORE between client and AS, but TLS
	between client and AS, but TLS or DTLS MAY be used additionally or		or DTLS MAY be used additionally or instead.
	instead.
	Once the client has retrieved the access token, it forwards it to the		Once the client has retrieved the access token, it posts it to the RS
	RS using the authz-info endpoint and mechanisms specified in section		using the authz-info resource and mechanisms specified in section 5.8
	5.8.1. of [I-D.ietf-ace-oauth-authz]. If the access token is valid,		of [I-D.ietf-ace-oauth-authz]. If the access token is valid, the RS
	the RS replies to this request with a 2.01 (Created) response, which		replies to this request with a 2.01 (Created) response, which
	contains a nonce N1.		contains a nonce N1.
	After receiving the nonce N1, the client generates a nonce N2,		After receiving the nonce N1, the client generates a nonce N2,
	concatenates it with N1 and sets the ID Context in its Security		concatenates it with N1 and sets the ID Context in its Security
	Context (see section 3 of [I-D.ietf-core-object-security]) to N1		Context (see section 3 of [I-D.ietf-core-object-security]) to N1
	concatenated with N2. The client then derives the complete Security		concatenated with N2. The client then derives the complete Security
	Context from the ID Context plus the parameters received from the AS.		Context from the ID Context plus the parameters received from the AS.
	Finally, the client sends a request protected with OSCORE to the RS.		Finally, the client sends a request protected with OSCORE to the RS.
	This message contains the ID Context value. When receiving this		This message contains the ID Context value. When receiving this
	request after the 2.01 (Created) response, the server extract the ID		request after the 2.01 (Created) response, the server extract the ID
	Context from it, verifies that the first part is equal to the nonce		Context from it, verifies that the first part is equal to the nonce
	N1 it previously sent, and if so, sets its own ID Context and derives		N1 it previously sent, and if so, sets its own ID Context and derives
	the complete Security Context from it plus the parameters received in		the complete Security Context from it plus the parameters received in
	the AS, following section 3.2 of [I-D.ietf-core-object-security]. If		the AS, following section 3.2 of [I-D.ietf-core-object-security]. If
	the request verifies, then this Security Context is stored in the		the request verifies, then this Security Context is stored in the
	server, and used in the response, and in further communications with		server, and used in the response, and in further communications with
	the client, until token expiration. The client will not include the		the client, until token expiration. Once the client receives a valid
	ID Context value in further requests.		response, it does not continue to include the ID Context value in
			further requests.
	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.		Figure 1.
	C RS AS		C RS AS
	| [-- Resource Request --->] | |		| [-- Resource Request --->] | |
	| | |		| | |
	| [<----- AS Information --] | |		| [<----- AS Information --] | |
	| | |		| | |
	| ----- POST /token ----------------------------> |		| ----- POST /token ----------------------------> |
	skipping to change at page 5, line 38 ¶		skipping to change at page 5, line 38 ¶
	| | |		| | |
	| <--- 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 /token		The following subsections describe the details of the POST /token
	request and response between client and AS. Section 3.2 of		request and response between client and AS. Section 3.2 of
	[I-D.ietf-core-object-security] defines how to derive a security		[I-D.ietf-core-object-security] defines how to derive a Security
	context based on a shared master secret and a set of other		Context based on a shared master secret and a set of other
	parameters, established between client and server, which the client		parameters, established between client and server, which the client
	receives from the AS in this exchange. The proof-of-possession key		receives from the AS in this exchange. The proof-of-possession key
	(pop-key) provisioned from the AS MUST be used as master secret in		(pop-key) provisioned from the AS MUST be used as master secret in
	OSCORE.		OSCORE.
	3.1. C-to-AS: POST /token		3.1. C-to-AS: POST /token
	The client-to-AS request is specified in Section 5.6.1 of		The client-to-AS request is specified in Section 5.6.1 of
	[I-D.ietf-ace-oauth-authz].		[I-D.ietf-ace-oauth-authz].
	If the client wants to update its access rights using the same OSCORE
	Security Context, it MUST include in its POST /token request a cnf
	object carrying the Sender ID in the kid field. This identifier can
	be used by the AS to determine the shared secret to construct the
	proof-of-possession token and therefore MUST specify a symmetric key
	that was previously generated by the AS as a shared secret for the
	communication between the client and the RS.
	The client MUST send this POST /token request over a secure channel		The client MUST send this POST /token request over a secure channel
	that guarantees authentication, message integrity and confidentiality		that guarantees authentication, message integrity and confidentiality
	(see Section 5).		(see Section 5).
	An example of such a request, in CBOR diagnostic notation without the		An example of such a request, in CBOR diagnostic notation without the
	tag and value abbreviations is reported in Figure 2		tag and value abbreviations is reported 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:
	{		{
	"grant_type" : "client_credentials",		"grant_type" : "client_credentials",
	"client_id" : "myclient",		"client_id" : "myclient",
	"aud" : "tempSensor4711"		"req_aud" : "tempSensor4711",
			"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
			existing OSCORE Security Context, it MUST include in its POST /token
			request a req_cnf object carrying the client's identifier (that was
			assigned in section Section 3.2) in the kid field. This identifier
			can be used by the AS to determine the shared secret to construct the
			proof-of-possession token and therefore MUST identify a symmetric key
			that was previously generated by the AS as a shared secret for the
			communication between the client and the RS. The AS MUST verify that
			the received value identifies a proof-of-possession key and token
			that have previously been issued to the requesting client. If that
			is not the case, the Client-to-AS request MUST be declined with the
			error code 'invalid_request' as defined in Section 5.6.3 of
			[I-D.ietf-ace-oauth-authz].
			An example of such a request, in CBOR diagnostic notation without the
			tag and value abbreviations is reported in Figure 3
			Header: POST (Code=0.02)
			Uri-Host: "as.example.com"
			Uri-Path: "token"
			Content-Format: "application/ace+cbor"
			Payload:
			{
			"grant_type" : "client_credentials",
			"client_id" : "myclient",
			"req_aud" : "tempSensor4711",
			"scope" : "write",
			"req_cnf" : {
			"kid" : b64'Qg'
			}
			Figure 3: Example C-to-AS POST /token request for updating rights 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 /token request and that the client is		After verifying the POST /token request and that the client is
	authorized to obtain an access token corresponding to its access		authorized to obtain an access token corresponding to its access
	token request, the AS responds as defined in section 5.6.2 of		token request, the AS responds as defined in section 5.6.2 of
	[I-D.ietf-ace-oauth-authz]. It signals that the use of OSCORE is		[I-D.ietf-ace-oauth-authz]. If the client request was invalid, or
	REQUIRED for a specific access token by including the "profile"		not authorized, the AS returns an error response as described in
	parameter with the value "coap_oscore" in the access token response.		section 5.6.3 of [I-D.ietf-ace-oauth-authz].
	This means that the client MUST use OSCORE towards all resource
	servers for which this access token is valid, and follow Section 4.3
	to derive the security context to run OSCORE.
	The error response procedures defined in section 5.6.3 of the ACE		The AS signals that the use of OSCORE is REQUIRED for a specific
	framework are unchanged by this profile.		access token by including the "profile" parameter with the value
			"coap_oscore" in the access token response. This means that the
			client MUST use OSCORE towards all resource servers for which this
			access token is valid, and follow Section 4.3 to derive the security
			context to run OSCORE.
	Moreover, the AS MUST provision the following data:		Moreover, the AS MUST provision the following data:
	o a master secret		o a master secret
	o a client identifier		o a client identifier
	o a server identifier		o a server identifier
	Additionally, the AS MAY provision the following data, in the same		Additionally, the AS MAY provision the following data, in the same
	response.		response.
	o an AEAD algorithm		o an AEAD algorithm
	o an HKDF algorithm		o an HKDF algorithm
	o a salt		o a salt
	o a replay window type and size		o a replay window type and size
	The master secret MUST be communicated as COSE_Key in the 'cnf'		The master secret MUST be communicated as COSE_Key in the 'cnf'
	parameter of the access token response as defined in Section 5.6.4.5		parameter of the access token response as defined in Section 3.2 of
	of [I-D.ietf-ace-oauth-authz]. The AEAD algorithm MAY be included as		[I-D.ietf-ace-oauth-params]. The AEAD algorithm MAY be included as
	the 'alg' parameter in the COSE_Key; the HKDF algorithm MAY be		the 'alg' parameter in the COSE_Key; the HKDF algorithm MAY be
	included as the 'hkdf' parameter of the COSE_Key and the salt MAY be		included as the 'hkdf' parameter of the COSE_Key and the salt MAY be
	included as the 'slt' parameter of the COSE_Key as defined in		included as the 'slt' parameter of the COSE_Key as defined in
	Figure 3.		Figure 4.
	The same parameters MUST be included as metadata of the access token.		The same parameters MUST be included as metadata of the access token.
	This profile RECOMMENDS the use of CBOR web token (CWT) as specified		This profile RECOMMENDS the use of CBOR web token (CWT) as specified
	in [RFC8392]. If the token is a CWT, the same COSE_Key structure		in [RFC8392]. If the token is a CWT, the same COSE_Key structure
	defined above MUST be placed in the 'cnf' claim of this token.		defined above MUST be placed in the 'cnf' claim of this token.
	The AS MUST also assign identifiers to both client and RS, which are		The AS MUST also assign identifiers to both client and RS, which are
	then used as Sender ID and Recipient ID in the OSCORE context as		then used as Sender ID and Recipient ID in the OSCORE context as
	described in section 3.1 of [I-D.ietf-core-object-security]. These		described in section 3.1 of [I-D.ietf-core-object-security]. These
	identifiers MUST be unique in the set of all clients and RS		identifiers MUST be unique in the set of all clients and RS
	identifiers for a certain AS. Moreover, these MUST be included in		identifiers for a certain AS. Moreover, these MUST be included in
	the COSE_Key as header parameters, as defined in Figure 3.		the COSE_Key as header parameters, as defined in Figure 4.
	We assume in this document that a resource is associated to one		We assume in this document that a resource is associated to one
	single AS, which makes it possible to assume unique identifiers for		single AS, which makes it possible to assume unique identifiers for
	each client requesting a particular resource to a RS. If this is not		each client requesting a particular resource to a RS. If this is not
	the case, collisions of identifiers may appear in the RS, in which		the case, collisions of identifiers may appear in the RS, in which
	case the RS needs to have a mechanism in place to disambiguate		case the RS needs to have a mechanism in place to disambiguate
	identifiers or mitigate their effect.		identifiers or mitigate their effect.
	Note that C should set the Sender ID of its Security Context to the		Note that in Section 4.3 C sets the Sender ID of its Security Context
	clientId value received and the Recipient ID to the serverId value,		to the clientId value received and the Recipient ID to the serverId
	and RS should do the opposite.		value, and RS does the opposite.
	+----------+-------+--------------+------------+-------------------+		+----------+-------+--------------+------------+-------------------+
	| name | label | CBOR type | registry | description |		| name | label | CBOR type | registry | description |
	+----------+-------+--------------+------------+-------------------+		+----------+-------+--------------+------------+-------------------+
	| clientId | TBD1 | bstr | | Identifies the |		| clientId | TBD1 | bstr | | Identifies the |
	| | | | | client in an |		| | | | | client in an |
	| | | | | OSCORE context |		| | | | | OSCORE context |
	| | | | | using this key |		| | | | | using this key |
	| | | | | |		| | | | | |
	| serverId | TBD2 | bstr | | Identifies the |		| serverId | TBD2 | bstr | | Identifies the |
	skipping to change at page 8, line 29 ¶		skipping to change at page 9, line 29 ¶
	| | | | | KDF algorithm in |		| | | | | KDF algorithm in |
	| | | | | an OSCORE context |		| | | | | an OSCORE context |
	| | | | | using this key |		| | | | | using this key |
	| | | | | |		| | | | | |
	| slt | TBD4 | bstr | | Identifies the |		| slt | TBD4 | bstr | | Identifies the |
	| | | | | master salt in |		| | | | | master salt in |
	| | | | | an OSCORE context |		| | | | | an OSCORE context |
	| | | | | using this key |		| | | | | using this key |
	+----------+-------+--------------+------------+-------------------+		+----------+-------+--------------+------------+-------------------+
	Figure 3: Additional COSE_Key Common Parameters		Figure 4: Additional COSE_Key Common Parameters
	Figure 4 shows an example of such an AS response, in CBOR diagnostic		Figure 5 shows an example of such an AS response, in CBOR diagnostic
	notation without the tag and value abbreviations.		notation without the tag and value abbreviations.
	Header: Created (Code=2.01)		Header: Created (Code=2.01)
	Content-Type: "application/cose+cbor"		Content-Type: "application/cose+cbor"
	Payload:		Payload:
	{		{
	"access_token" : b64'SlAV32hkKG ...		"access_token" : b64'SlAV32hkKG ...
	(remainder of access token omitted for brevity)',		(remainder of access token omitted for brevity)',
	"profile" : "coap_oscore",		"profile" : "coap_oscore",
	"expires_in" : "3600",		"expires_in" : "3600",
	skipping to change at page 9, line 24 ¶		skipping to change at page 10, line 24 ¶
	"COSE_Key" : {		"COSE_Key" : {
	"kty" : "Symmetric",		"kty" : "Symmetric",
	"alg" : "AES-CCM-16-64-128",		"alg" : "AES-CCM-16-64-128",
	"clientId" : b64'qA',		"clientId" : b64'qA',
	"serverId" : b64'Qg',		"serverId" : b64'Qg',
	"k" : b64'+a+Dg2jjU+eIiOFCa9lObw'		"k" : b64'+a+Dg2jjU+eIiOFCa9lObw'
	}		}
	}		}
	}		}
	Figure 4: Example AS-to-C Access Token response with OSCORE profile.		Figure 5: Example AS-to-C Access Token response with OSCORE profile.
	Figure 5 shows an example CWT, containing the necessary OSCORE		Figure 6 shows an example CWT, containing the necessary OSCORE
	parameters in the 'cnf' claim, in CBOR diagnostic notation without		parameters in the 'cnf' claim, in CBOR diagnostic notation without
	tag and value abbreviations.		tag and value abbreviations.
	{		{
	"aud" : "tempSensorInLivingRoom",		"aud" : "tempSensorInLivingRoom",
	"iat" : "1360189224",		"iat" : "1360189224",
	"exp" : "1360289224",		"exp" : "1360289224",
	"scope" : "temperature_g firmware_p",		"scope" : "temperature_g firmware_p",
	"cnf" : {		"cnf" : {
	"COSE_Key" : {		"COSE_Key" : {
	"kty" : "Symmetric",		"kty" : "Symmetric",
	"alg" : "AES-CCM-16-64-128",		"alg" : "AES-CCM-16-64-128",
	"clientId" : b64'Qg',		"clientId" : b64'Qg',
	"serverId" : b64'qA',		"serverId" : b64'qA',
	"k" : b64'+a+Dg2jjU+eIiOFCa9lObw'		"k" : b64'+a+Dg2jjU+eIiOFCa9lObw'
	}		}
	}		}
	Figure 5: Example CWT with OSCORE parameters.		Figure 6: Example CWT with OSCORE parameters.
	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, and the token associated with it is not		same OSCORE Security Context, which is valid and authorized, the AS
	expired, the AS MAY omit the master secret and server identifier both		MUST omit the 'cnf' parameter in the response, and MUST carry the
	in the COSE_Key in the 'cnf' parameter and in the token. The client		client identifier in the 'kid' field in the 'cnf' parameter of the
	identifier needs to be provisioned, in order for the RS to identify		token. The client identifier needs to be provisioned, in order for
	the previously generated Security Context.		the RS to identify the previously generated Security Context.
	Figure 6 shows an example of such an AS response, in CBOR diagnostic		Figure 7 shows an example of such an AS response, in CBOR diagnostic
	notation without the tag and value abbreviations.		notation without the tag and value abbreviations.
	Header: Created (Code=2.01)		Header: Created (Code=2.01)
	Content-Type: "application/cose+cbor"		Content-Type: "application/cose+cbor"
	Payload:		Payload:
	{		{
	"access_token" : b64'SlAV32hkKG ...		"access_token" : b64'SlAV32hkKG ...
	(remainder of access token omitted for brevity)',		(remainder of access token omitted for brevity)',
	"profile" : "coap_oscore",		"profile" : "coap_oscore",
	"expires_in" : "3600",		"expires_in" : "3600"
	"cnf" : {
	"COSE_Key" : {
	"clientId" : b64'qA'
	}
	}
	}		}
	Figure 6: Example AS-to-C Access Token response with OSCORE profile,		Figure 7: Example AS-to-C Access Token response with OSCORE profile,
	for update of access rights.		for update of access rights.
	Figure 7 shows an example CWT, containing the necessary OSCORE		Figure 8 shows an example CWT, containing the necessary OSCORE
	parameters in the 'cnf' claim for update of access rights, in CBOR		parameters in the 'cnf' claim for update of access rights, in CBOR
	diagnostic notation without tag and value abbreviations.		diagnostic notation without tag and value abbreviations.
	{		{
	"aud" : "tempSensorInLivingRoom",		"aud" : "tempSensorInLivingRoom",
	"iat" : "1360189224",		"iat" : "1360189224",
	"exp" : "1360289224",		"exp" : "1360289224",
	"scope" : "temperature_h",		"scope" : "temperature_h",
	"cnf" : {		"cnf" : {
	"COSE_Key" : {		"kid" : b64'Qg'
	"clientId" : b64'Qg'
	}		}
	}		}
	Figure 7: Example CWT with OSCORE parameters for update of access		Figure 8: Example CWT with OSCORE parameters for update of access
	rights.		rights.
	4. Client-RS Communication		4. Client-RS Communication
	The following subsections describe the details of the POST /authz-		The following subsections describe the details of the POST /authz-
	info request and response between client and RS. The client posts		info request and response between client and RS. The client posts
	the token that includes the materials provisioned by the AS to the		the token that includes the materials provisioned by the AS to the
	RS, which can then use Section 3.2 of [I-D.ietf-core-object-security]		RS, which can then use Section 3.2 of [I-D.ietf-core-object-security]
	to derive a security context based on a shared master secret and a		to derive a security context based on a shared master secret and a
	set of other parameters, established between client and server.		set of other parameters, established between client and server.
	Note that the proof-of-possession required to bind the access token		Note that the proof-of-possession required to bind the access token
	to the client is implicitly performed by generating the shared OSCORE		to the client is implicitly performed by generating the shared OSCORE
	Security Context using the pop-key as master secret, for both client		Security Context using the pop-key as master secret, for both client
	and RS. An attacker using a stolen token will not be able to		and RS. An attacker using a stolen token will not be able to
	generate a valid OSCORE context and thus not be able to prove		generate a valid OSCORE context and thus not be able to prove
	possession of the pop-key.		possession of the pop-key.
	4.1. C-to-RS: POST /authz-info		4.1. C-to-RS: POST /authz-info
	The client MUST use CoAP and the Authorization Information endpoint		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 [I-D.ietf-ace-oauth-authz] to
	transport the token to the RS.		transport the token to the RS.
	The authz-info endpoint is not protected, nor are the responses from		The authz-info resource is not protected, nor are the responses from
	this endpoint.		this resource.
	The access token MUST be encrypted, since it is transferred from the		The access token MUST be encrypted, since it is transferred from the
	client to the RS over an unprotected channel.		client to the RS over an unprotected channel.
	Figure 8 shows an example of the request sent from the client to the		Note that a client may be required to re-POST the access token, since
			an RS may delete a stored access token, due to lack of memory.
			Figure 9 shows an example of the request sent from the client to the
	RS.		RS.
	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/cwt"		Content-Format: "application/cwt"
	Payload:		Payload:
	b64'SlAV32hkKG ...		b64'SlAV32hkKG ...
	(remainder of access token omitted for brevity)',		(remainder of access token omitted for brevity)',
	Figure 8: Example C-to-RS POST /authz-info request using CWT		Figure 9: Example C-to-RS POST /authz-info request using CWT
	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		[I-D.ietf-ace-oauth-authz]: the RS MUST verify the validity of the
	token. If the token is valid, the RS MUST respond to the POST		token. If the token is valid, the RS MUST respond to the POST
	request with 2.01 (Created). This response MAY contain an identifier		request with 2.01 (Created). If the token is valid but is associated
	of the token (e.g., the cti for a CWT) as a payload, in order to		to claims that the RS cannot process (e.g., an unknown scope) the RS
	allow the client to refer to the token. If the token is valid but is		MUST respond with a response code equivalent to the CoAP code 4.00
	associated to claims that the RS cannot process (e.g., an unknown		(Bad Request). In the latter case the RS MAY provide additional
	scope) the RS MUST respond with a response code equivalent to the		information in the error response, in order to clarify what went
	CoAP code 4.00 (Bad Request). In the latter case the RS MAY provide		wrong. The RS MAY make an introspection request to validate the
	additional information in the error response, in order to clarify		token before responding to the POST request to the authz-info
	what went wrong. The RS MAY make an introspection request to		resource.
	validate the token before responding to the POST request to the
	authz-info endpoint.
	Additionally, the RS MUST generate a nonce (N1) with a good amount of		Additionally, the RS MUST generate a nonce (N1) with a good amount of
	randomness, and include it in the payload of the 2.01 (Created)		randomness, and include it in the payload of the 2.01 (Created)
	response as a CBOR byte string. This profile RECOMMENDS to use a		response as a CBOR byte string. This profile RECOMMENDS to use a
	nonce of 64 bits. The RS MUST store this nonce as long as the access		nonce of 64 bits. The RS MUST store this nonce as long as the access
	token related to it is still valid.		token related to it is still valid.
	Figure 9 shows an example of the response sent from the RS to the		Note that, when using this profile, an identifier of the token (e.g.,
			the cti for a CWT) is not transported in the payload of this request,
			as section 5.8.1 of [I-D.ietf-ace-oauth-authz] allows.
			Figure 10 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/cbor"		Content-Format: "application/cbor"
	Payload:		Payload:
	h'018a278f7faab55a',		h'018a278f7faab55a',
	Figure 9: Example RS-to-C 2.01 (Created) response		Figure 10: Example RS-to-C 2.01 (Created) response
			When receiving an updated access token with updated authorization
			information from the client (see section Section 3.1), it is
			RECOMMENDED that the RS overwrites the previous token, that is only
			the latest authorization information in the token received by the RS
			is valid. This simplifies for the RS to keep track of authorization
			information for a given client.
	As specified in section 5.8.3 of [I-D.ietf-ace-oauth-authz], the RS		As specified in section 5.8.3 of [I-D.ietf-ace-oauth-authz], the RS
	MUST notify the client with an error response with code 4.01		MUST notify the client with an error response with code 4.01
	(Unauthorized) for any long running request before terminating the		(Unauthorized) for any long running request before terminating the
	session, when the access token expires.		session, when the access token expires.
	4.3. OSCORE Setup		4.3. OSCORE Setup
	Once receiving the 2.01 (Created) response from the RS, following the		Once receiving the 2.01 (Created) response from the RS, following the
	POST /authz-info request, the client MUST extract the nonce N1 from		POST /authz-info request, the client MUST extract the nonce N1 from
	skipping to change at page 13, line 48 ¶		skipping to change at page 15, line 8 ¶
	responses are used, as specified in section 8 of		responses are used, as specified in section 8 of
	[I-D.ietf-core-object-security]. Additionally, if OSCORE		[I-D.ietf-core-object-security]. Additionally, if OSCORE
	verification succeeds, the verification of access rights is performed		verification succeeds, the verification of access rights is performed
	as described in section Section 4.4. The RS MUST NOT use the		as described in section Section 4.4. The RS MUST NOT use the
	Security Context after the related token has expired, and MUST		Security Context after the related token has expired, and MUST
	respond with a unprotected 4.01 (Unauthorized) error message.		respond with a unprotected 4.01 (Unauthorized) error message.
	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 a OSCORE-protected		[I-D.ietf-ace-oauth-authz]: if an RS receives an OSCORE-protected
	request from a client, then it processes according to		request from a client, then it processes according to
	[I-D.ietf-core-object-security]. If OSCORE verification succeeds,		[I-D.ietf-core-object-security]. If OSCORE verification succeeds,
	and the target resource requires authorization, the RS retrieves the		and the target resource requires authorization, the RS retrieves the
	authorization information from the access token associated to the		authorization information from the access token associated to the
	Security Context. The RS then MUST verify that the authorization		Security Context. The RS then MUST verify that the authorization
	information covers the resource and the action requested.		information covers the resource and the action requested.
	The response code MUST be 4.01 (Unauthorized) in case the client has		The response code MUST be 4.01 (Unauthorized) in case the client has
	not used the Security Context associated with the access token, or if		not used the Security Context associated with the access token, or if
	RS has no valid access token for the client. If RS has an access		RS has no valid access token for the client. If RS has an access
	token for the client but not for the resource that was requested, RS		token for the client but not for the resource that was requested, RS
	MUST reject the request with a 4.03 (Forbidden). If RS has an access		MUST reject the request with a 4.03 (Forbidden). If RS has an access
	token for the client but it does not cover the action that was		token for the client but it does not cover the action that was
	requested on the resource, RS MUST reject the request with a 4.05		requested on the resource, RS MUST reject the request with a 4.05
	(Method Not Allowed).		(Method Not Allowed).
	5. Secure Communication with AS		5. Secure Communication with AS
	As specified in the ACE framework (section 5.7 of		As specified in the ACE framework (section 5.7 of
	[I-D.ietf-ace-oauth-authz]), the requesting entity (RS and/or client)		[I-D.ietf-ace-oauth-authz]), the requesting entity (RS and/or client)
	and the AS communicates via the introspection or token endpoint. The		and the AS communicates via the introspection or token resource. The
	use of CoAP and OSCORE for this communication is RECOMMENDED in this		use of CoAP and OSCORE for this communication is RECOMMENDED in this
	profile, other protocols (such as HTTP and DTLS or TLS) MAY be used		profile, other protocols (such 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 pre-established 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 using OSCORE		Furthermore the requesting entity and the AS communicate using OSCORE
	([I-D.ietf-core-object-security]) through the introspection endpoint		([I-D.ietf-core-object-security]) through the introspection resource
	as specified in section 5.7 of [I-D.ietf-ace-oauth-authz] and through		as specified in section 5.7 of [I-D.ietf-ace-oauth-authz] and through
	the token endpoint as specified in section 5.6 of		the token resource as specified in section 5.6 of
	[I-D.ietf-ace-oauth-authz].		[I-D.ietf-ace-oauth-authz].
	6. Security Considerations		6. Security Considerations
	This document specifies a profile for the Authentication and		This document specifies a profile for the Authentication and
	Authorization for Constrained Environments (ACE) framework		Authorization for Constrained Environments (ACE) framework
	[I-D.ietf-ace-oauth-authz]. Thus the general security considerations		[I-D.ietf-ace-oauth-authz]. Thus the general security considerations
	from the framework also apply to this profile.		from the framework also apply to this profile.
	Furthermore the general security considerations of OSCORE		Furthermore the general security considerations of OSCORE
	skipping to change at page 15, line 7 ¶		skipping to change at page 16, line 13 ¶
	the OSCORE protocol.		the OSCORE protocol.
	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 usecase corresponds to the		this profile should make sure that their usecase 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.
	TODO: explain the rationale for the nonces construction, and the		The use of nonces during the OSCORE Setup Section 4.3 prevents the
	security implications for Man-in-the-Middle attacks.		reuse of AEAD nonces in the RS Security Context, in case the RS loses
			the Security Context associated with a client (e.g. in case of
			unplanned reboot) and receives a replayed access token. In fact, by
			using random nonces as ID Context, the POST /auth-info request
			results in a different Security Context, since Master Secret, Sender
			ID and Recipient ID are the same but ID Context is different.
			Therefore, the main requirement for the nonces is that they have a
			good amount of randomness. Moreover, the client echoes the nonce
			created by the RS, which verifies it before deriving the Security
			Context, and this protects against an adversary acting as a Man-in-
			the-Middle and substituting the nonce in transit from client to RS to
			provoke the creation of different Security Contexts in the client and
			RS.
			This profiles recommends that the RS maintains a single access token
			for a client. The use of multiple access tokens for a single client
			increases the strain on the resource server as it must consider every
			access token and calculate the actual permissions of the client.
			Also, tokens may contradict each other which may lead the server to
			enforce wrong permissions. If one of the access tokens expires
			earlier than others, the resulting permissions may offer insufficient
			protection. Developers should avoid using multiple access tokens for
			a client.
	7. Privacy Considerations		7. Privacy Considerations
	TBD.		This document specifies a profile for the Authentication and
			Authorization for Constrained Environments (ACE) framework
			[I-D.ietf-ace-oauth-authz]. Thus the general privacy considerations
			from the framework also apply to this profile.
			As this document uses OSCORE, thus the privacy considerations from
			[I-D.ietf-core-object-security] apply here as well.
			An unprotected response to an unauthorized request may disclose
			information about the resource server and/or its existing
			relationship with the client. It is advisable to include as little
			information as possible in an unencrypted response. When an OSCORE
			Security Context already exists between the client and the resource
			server, more detailed information may be included.
			Note that some information might still leak after OSCORE is
			established, due to observable message sizes, the source, and the
			destination addresses.
	8. IANA Considerations		8. IANA Considerations
	Note to RFC Editor: Please replace all occurrences of "[[this		Note to RFC Editor: Please replace all occurrences of "[[this
	specification]]" with the RFC number of this specification and delete		specification]]" with the RFC number of this specification and delete
	this paragraph.		this paragraph.
	The following registration is done for the ACE OAuth Profile Registry		The following registration is done for the ACE OAuth Profile Registry
	following the procedure specified in section 8.6 of		following the procedure specified in section 8.7 of
	[I-D.ietf-ace-oauth-authz]:		[I-D.ietf-ace-oauth-authz]:
	o Profile name: coap_oscore		o Profile name: coap_oscore
	o Profile Description: Profile for using OSCORE to secure		o Profile Description: Profile for using OSCORE to secure
	communication between constrained nodes using the Authentication		communication between constrained nodes using the Authentication
	and Authorization for Constrained Environments framework.		and Authorization for Constrained Environments framework.
	o Profile ID: TBD (value between 1 and 255)		o Profile ID: TBD (value between 1 and 255)
	o Change Controller: IESG		o Change Controller: IESG
	o Specification Document(s): [[this specification]]		o Specification Document(s): [[this specification]]
	skipping to change at page 16, line 28 ¶		skipping to change at page 18, line 26 ¶
	9.1. Normative References		9.1. Normative References
	[I-D.ietf-ace-oauth-authz]		[I-D.ietf-ace-oauth-authz]
	Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and		Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and
	H. Tschofenig, "Authentication and Authorization for		H. Tschofenig, "Authentication and Authorization for
	Constrained Environments (ACE) using the OAuth 2.0		Constrained Environments (ACE) using the OAuth 2.0
	Framework (ACE-OAuth)", draft-ietf-ace-oauth-authz-15		Framework (ACE-OAuth)", draft-ietf-ace-oauth-authz-15
	(work in progress), September 2018.		(work in progress), September 2018.
			[I-D.ietf-ace-oauth-params]
			Seitz, L., "Additional OAuth Parameters for Authorization
			in Constrained Environments (ACE)", draft-ietf-ace-oauth-
			params-00 (work in progress), September 2018.
	[I-D.ietf-core-object-security]		[I-D.ietf-core-object-security]
	Selander, G., Mattsson, J., Palombini, F., and L. Seitz,		Selander, G., Mattsson, J., Palombini, F., and L. Seitz,
	"Object Security for Constrained RESTful Environments		"Object Security for Constrained RESTful Environments
	(OSCORE)", draft-ietf-core-object-security-15 (work in		(OSCORE)", draft-ietf-core-object-security-15 (work in
	progress), August 2018.		progress), August 2018.
	[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>.
	skipping to change at page 18, line 34 ¶		skipping to change at page 20, line 38 ¶
	asymmetric) is used to authenticate the messages in EDHOC, then the		asymmetric) is used to authenticate the messages in EDHOC, then the
	AS MUST provision the following data, in response to the access token		AS MUST provision the following data, in response to the access token
	request:		request:
	o a symmetric or public key (associated to the RS)		o a symmetric or public key (associated to the RS)
	o a key identifier;		o a key identifier;
	How these parameters are communicated depends on the type of key		How these parameters are communicated depends on the type of key
	(asymmetric or symmetric). Moreover, the AS MUST signal the use of		(asymmetric or symmetric). Moreover, the AS MUST signal the use of
	OSCORE + EDHOC with the 'profile' parameter set to		OSCORE + EDHOC with the 'profile' parameter set to
	"coap_oscore_edhoc" and follow Appendix B to derive the security		"coap_oscore_edhoc".
	context to run OSCORE.
	Note that in the case described in this section, the 'expires_in'		Note that in the case described in this section, the 'expires_in'
	parameter, defined in Section 4.2.2. of [RFC6749] defines the		parameter, defined in Section 4.2.2. of [RFC6749] defines the
	lifetime in seconds of both the access token and the shared secret.		lifetime in seconds of both the access token and the shared secret.
	After expiration, C MUST acquire a new access token from the AS, and		After expiration, C MUST acquire a new access token from the AS, and
	run EDHOC again, as specified in this section		run EDHOC again, as specified in this section
	B.1. Using Asymmetric Keys		B.1. Using Asymmetric Keys
	In case of an asymmetric key, C MUST communicate its own asymmetric		In case of an asymmetric key, C MUST communicate its own asymmetric
	key to the AS in the 'cnf' parameter of the access token request, as		key to the AS in the 'req_cnf' parameter of the access token request,
	specified in Section 5.6.1 of [I-D.ietf-ace-oauth-authz]; the AS MUST		as specified in Section 3.1 of [I-D.ietf-ace-oauth-params]; the AS
	communicate the RS's public key to C in the response, in the 'rs_cnf'		MUST communicate the RS's public key to C in the response, in the
	parameter, as specified in Section 5.6.1 of		'rs_cnf' parameter, as specified in Section 3.2 of
	[I-D.ietf-ace-oauth-authz]. Note that the RS's public key MUST		[I-D.ietf-ace-oauth-params]. Note that the RS's public key MUST
	include a 'kid' parameter, and that the value of the 'kid' MUST be		include a 'kid' parameter, and that the value of the 'kid' MUST be
	included in the access token, to let the RS know which of its public		included in the access token, to let the RS know which of its public
	keys C used. If the access token is a CWT [RFC8392], the key		keys C used. If the access token is a CWT [RFC8392], the key
	identifier MUST be placed directly in the 'cnf' structure (if the key		identifier MUST be placed directly in the 'cnf' structure (if the key
	is only referenced).		is only referenced).
	Figure 3 shows an example of such a request in CBOR diagnostic		Figure 3 shows an example of such a request in CBOR diagnostic
	notation without tag and value abbreviations.		notation without tag and value abbreviations.
	Header: POST (Code=0.02)		Header: POST (Code=0.02)
	Uri-Host: "server.example.com"		Uri-Host: "server.example.com"
	Uri-Path: "token"		Uri-Path: "token"
	Content-Type: "application/cose+cbor"		Content-Type: "application/cose+cbor"
	Payload:		Payload:
	{		{
	"grant_type" : "client_credentials",		"grant_type" : "client_credentials",
	"cnf" : {		"req_cnf" : {
	"COSE_Key" : {		"COSE_Key" : {
	"kid" : "client_key"		"kid" : "client_key"
	"kty" : "EC",		"kty" : "EC",
	"crv" : "P-256",		"crv" : "P-256",
	"x" : b64'usWxHK2PmfnHKwXPS54m0kTcGJ90UiglWiGahtagnv8',		"x" : b64'usWxHK2PmfnHKwXPS54m0kTcGJ90UiglWiGahtagnv8',
	"y" : b64'IBOL+C3BttVivg+lSreASjpkttcsz+1rb7btKLv8EX4'		"y" : b64'IBOL+C3BttVivg+lSreASjpkttcsz+1rb7btKLv8EX4'
	}		}
	}		}
	}		}
	skipping to change at page 20, line 30 ¶		skipping to change at page 22, line 30 ¶
	}		}
	}		}
	}		}
	Figure 4: Example AS response (EDHOC+OSCORE, asymmetric).		Figure 4: Example AS response (EDHOC+OSCORE, asymmetric).
	B.2. Using Symmetric Keys		B.2. Using Symmetric Keys
	In the case of a symmetric key, the AS MUST communicate the key to		In the case of a symmetric key, the AS MUST communicate the key to
	the client in the 'cnf' parameter of the access token response, as		the client in the 'cnf' parameter of the access token response, as
	specified in Section 5.6.2. of [I-D.ietf-ace-oauth-authz]. AS MUST		specified in Section 3.2. of [I-D.ietf-ace-oauth-params]. The AS
	also select a key identifier, that MUST be included as the 'kid'		MUST also select a key identifier, that MUST be included as the 'kid'
	parameter either directly in the 'cnf' structure, as in figure 4 of		parameter of the COSE_key, as in figure 9 of
	[I-D.ietf-ace-oauth-authz], or as the 'kid' parameter of the		[I-D.ietf-ace-oauth-authz].
	COSE_key, as in figure 6 of [I-D.ietf-ace-oauth-authz].
	Figure 5 shows an example of the necessary parameters in the AS		Figure 5 shows an example of the necessary parameters in the AS
	response to the access token request when EDHOC is used. The example		response to the access token request when EDHOC is used. The example
	uses CBOR diagnostic notation without tag and value abbreviations.		uses CBOR diagnostic notation without tag and value abbreviations.
	Header: Created (Code=2.01)		Header: Created (Code=2.01)
	Content-Type: "application/cose+cbor"		Content-Type: "application/cose+cbor"
	Payload:		Payload:
	{		{
	"access_token" : b64'SlAV32hkKG ...		"access_token" : b64'SlAV32hkKG ...
	skipping to change at page 21, line 51 ¶		skipping to change at page 23, line 51 ¶
	"kty" : "Symmetric",		"kty" : "Symmetric",
	"kid" : b64'5tOS+h42dkw',		"kid" : b64'5tOS+h42dkw',
	"k" : b64'+a+Dg2jjU+eIiOFCa9lObw'		"k" : b64'+a+Dg2jjU+eIiOFCa9lObw'
	}		}
	}		}
	Figure 6: Example CWT with EDHOC+OSCORE, symmetric case.		Figure 6: Example CWT with EDHOC+OSCORE, symmetric case.
	All other parameters defining OSCORE security context are derived		All other parameters defining OSCORE security context are derived
	from EDHOC message exchange, including the master secret (see		from EDHOC message exchange, including the master secret (see
	Appendix C.2 of [I-D.selander-ace-cose-ecdhe]).		Appendix D.2 of [I-D.selander-ace-cose-ecdhe]).
	B.3. Processing		B.3. Processing
	To provide forward secrecy and mutual authentication in the case of		To provide forward secrecy and mutual authentication in the case of
	pre-shared keys, pre-established raw public keys or with X.509		pre-shared keys, pre-established raw public keys or with X.509
	certificates it is RECOMMENDED to use EDHOC		certificates it is RECOMMENDED to use EDHOC
	[I-D.selander-ace-cose-ecdhe] to generate the keying material. EDHOC		[I-D.selander-ace-cose-ecdhe] to generate the keying material. EDHOC
	MUST be used as defined in Appendix C of		MUST be used as defined in Appendix D of
	[I-D.selander-ace-cose-ecdhe], with the following additions and		[I-D.selander-ace-cose-ecdhe], with the following additions and
	modifications.		modifications.
	The first EDHOC message is sent after the access token is posted to		The first EDHOC message is sent after the access token is posted to
	the /authz-info resource of the RS as specified in Section 5.8.1 of		the /authz-info resource of the RS as specified in Section 5.8.1 of
	[I-D.ietf-ace-oauth-authz]. Then the EDHOC message_1 is sent and the		[I-D.ietf-ace-oauth-authz]. Then the EDHOC message_1 is sent and the
	EDHOC protocol is initiated [I-D.selander-ace-cose-ecdhe]).		EDHOC protocol is initiated [I-D.selander-ace-cose-ecdhe]).
	Before the RS continues with the EDHOC protocol and responds to this		Before the RS continues with the EDHOC protocol and responds to this
	token submission request, additional verifications on the access		token submission request, additional verifications on the access
	token are done: the RS SHALL process the access token according to		token are done: the RS SHALL process the access token according to
	[I-D.ietf-ace-oauth-authz]. If the token is valid then the RS		[I-D.ietf-ace-oauth-authz]. If the token is valid then the RS
	continues processing EDHOC following Appendix C of		continues processing EDHOC following Appendix D of
	[I-D.selander-ace-cose-ecdhe], otherwise it discontinues EDHOC and		[I-D.selander-ace-cose-ecdhe], otherwise it discontinues EDHOC and
	responds with the error code as specified in		responds with the error code as specified in
	[I-D.ietf-ace-oauth-authz].		[I-D.ietf-ace-oauth-authz].
	o In case the EDHOC verification fails, the RS MUST return an error		o In case the EDHOC verification fails, the RS MUST return an error
	response to the client with code 4.01 (Unauthorized).		response to the client with code 4.01 (Unauthorized).
	o If RS has an access token for C but not for the resource that C		o If RS has an access token for C but not for the resource that C
	has requested, RS MUST reject the request with a 4.03 (Forbidden).		has requested, RS MUST reject the request with a 4.03 (Forbidden).
	o If RS has an access token for C but it does not cover the action C		o If RS has an access token for C but it does not cover the action C
	requested on the resource, RS MUST reject the request with a 4.05		requested on the resource, RS MUST reject the request with a 4.05
	skipping to change at page 23, line 48 ¶		skipping to change at page 25, line 48 ¶
	|<---------+ CoAP response +		|<---------+ CoAP response +
	| OSCORE | Object-Security option		| OSCORE | Object-Security option
	| response |		| response |
	| |		| |
	Figure 7: Access token and key establishment with EDHOC		Figure 7: Access token and key establishment with EDHOC
	Acknowledgments		Acknowledgments
	The authors wish to thank Jim Schaad and Marco Tiloca for the input		The authors wish to thank Jim Schaad and Marco Tiloca for the input
	on this memo. The error responses specified in Appendix B.3 were		on this memo.
	originally specified by Gerdes et al. in
	[I-D.gerdes-ace-dcaf-authorize].
	Authors' Addresses		Authors' Addresses
			Francesca Palombini
			Ericsson AB
			Email: francesca.palombini@ericsson.com
	Ludwig Seitz		Ludwig Seitz
	RISE SICS AB		RISE SICS AB
	Scheelevagen 17		Scheelevagen 17
	Lund 22370		Lund 22370
	Sweden		Sweden
	Email: ludwig.seitz@ri.se		Email: ludwig.seitz@ri.se
	Francesca Palombini		Goeran Selander
	Ericsson AB		Ericsson AB
	Farogatan 6
	Kista SE-16480 Stockholm
	Sweden
	Email: francesca.palombini@ericsson.com		Email: goran.selander@ericsson.com
	Martin Gunnarsson		Martin Gunnarsson
	RISE SICS AB		RISE SICS AB
	Scheelevagen 17		Scheelevagen 17
	Lund 22370		Lund 22370
	Sweden		Sweden
	Email: martin.gunnarsson@ri.se		Email: martin.gunnarsson@ri.se
	Goeran Selander
	Ericsson AB
	Farogatan 6
	Kista SE-16480 Stockholm
	Sweden
	Email: goran.selander@ericsson.com
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