draft-ietf-ace-cbor-web-token-00.txt		draft-ietf-ace-cbor-web-token-01.txt
	ACE Working Group E. Wahlstroem		ACE Working Group E. Wahlstroem
	Internet-Draft Nexus Technology		Internet-Draft
	Intended status: Informational M. Jones		Intended status: Informational M. Jones
	Expires: November 21, 2016 Microsoft		Expires: January 8, 2017 Microsoft
	H. Tschofenig		H. Tschofenig
	ARM Ltd.		ARM Ltd.
	May 20, 2016		S. Erdtman
			Spotify AB
			July 7, 2016
	CBOR Web Token (CWT)		CBOR Web Token (CWT)
	draft-ietf-ace-cbor-web-token-00		draft-ietf-ace-cbor-web-token-01
	Abstract		Abstract
	CBOR Web Token (CWT) is a compact means of representing claims to be		CBOR Web Token (CWT) is a compact means of representing claims to be
	transferred between two parties. CWT is a profile of the JSON Web		transferred between two parties. CWT is a profile of the JSON Web
	Token (JWT) that is optimized for constrained devices. The claims in		Token (JWT) that is optimized for constrained devices. The claims in
	a CWT are encoded in the Concise Binary Object Representation (CBOR)		a CWT are encoded in the Concise Binary Object Representation (CBOR)
	and CBOR Object Signing and Encryption (COSE) is used for added		and CBOR Object Signing and Encryption (COSE) is used for added
	application layer security protection. A claim is a piece of		application layer security protection. A claim is a piece of
	information asserted about a subject and is represented as a name/		information asserted about a subject and is represented as a name/
	skipping to change at page 1, line 40 ¶		skipping to change at page 1, line 42 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at http://datatracker.ietf.org/drafts/current/.		Drafts is at http://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 November 21, 2016.		This Internet-Draft will expire on January 8, 2017.
	Copyright Notice		Copyright Notice
	Copyright (c) 2016 IETF Trust and the persons identified as the		Copyright (c) 2016 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
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://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
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	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 . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
	3. Claims . . . . . . . . . . . . . . . . . . . . . . . . . . . 3		3. Claims . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
	3.1. Claim Names . . . . . . . . . . . . . . . . . . . . . . . 4		3.1. Claim Names . . . . . . . . . . . . . . . . . . . . . . . 4
	3.1.1. iss (Issuer) Claim . . . . . . . . . . . . . . . . . 4		3.1.1. iss (Issuer) Claim . . . . . . . . . . . . . . . . . 4
	3.1.2. sub (Subject) Claim . . . . . . . . . . . . . . . . . 4		3.1.2. sub (Subject) Claim . . . . . . . . . . . . . . . . . 4
	3.1.3. aud (Audience) Claim . . . . . . . . . . . . . . . . 4		3.1.3. aud (Audience) Claim . . . . . . . . . . . . . . . . 4
	3.1.4. exp (Expiration Time) Claim . . . . . . . . . . . . . 4		3.1.4. exp (Expiration Time) Claim . . . . . . . . . . . . . 5
	3.1.5. nbf (Not Before) Claim . . . . . . . . . . . . . . . 4		3.1.5. nbf (Not Before) Claim . . . . . . . . . . . . . . . 5
	3.1.6. iat (Issued At) Claim . . . . . . . . . . . . . . . . 5		3.1.6. iat (Issued At) Claim . . . . . . . . . . . . . . . . 5
	3.1.7. cti (CWT ID) Claim . . . . . . . . . . . . . . . . . 5		3.1.7. cti (CWT ID) Claim . . . . . . . . . . . . . . . . . 5
	4. Summary of the values, CBOR major types and encoded claim		4. Summary of the values, CBOR major types and encoded claim
	keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5		keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
	5. Security Considerations . . . . . . . . . . . . . . . . . . . 5		5. Creating and Validating CWTs . . . . . . . . . . . . . . . . 6
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6		5.1. Creating a CWT . . . . . . . . . . . . . . . . . . . . . 6
	7. Normative References . . . . . . . . . . . . . . . . . . . . 6		5.2. Validating a CWT . . . . . . . . . . . . . . . . . . . . 7
	Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 6		6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
	A.1. CWT with "aud" and symmetric key . . . . . . . . . . . . 7		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
	A.2. CWT with "aud" and EC key . . . . . . . . . . . . . . . . 8		7.1. CBOR Web Token (CWT) Claims Registry . . . . . . . . . . 8
	A.3. Full CWT . . . . . . . . . . . . . . . . . . . . . . . . 10		7.1.1. Registration Template . . . . . . . . . . . . . . . . 8
	Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 12		7.1.2. Initial Registry Contents . . . . . . . . . . . . . . 9
	Appendix C. Document History . . . . . . . . . . . . . . . . . . 12		7.2. CoAP Content-Format Registration . . . . . . . . . . . . 10
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13		7.2.1. Registry Contents . . . . . . . . . . . . . . . . . . 10
			8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
			8.1. Normative References . . . . . . . . . . . . . . . . . . 11
			8.2. Informative References . . . . . . . . . . . . . . . . . 12
			Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 12
			A.1. CWT with "aud" and symmetric key . . . . . . . . . . . . 12
			A.2. CWT with "aud" and EC key . . . . . . . . . . . . . . . . 13
			A.3. Full CWT . . . . . . . . . . . . . . . . . . . . . . . . 15
			Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 18
			Appendix C. Document History . . . . . . . . . . . . . . . . . . 19
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
	1. Introduction		1. Introduction
	The JSON Web Token (JWT) [5] is a standardized security token format		The JSON Web Token (JWT) [RFC7519] is a standardized security token
	that has found use in OAuth 2.0 and OpenID Connect deployments, among		format that has found use in OAuth 2.0 and OpenID Connect
	other applications. JWT uses JSON Web Signatures (JWS) [3] and JSON		deployments, among other applications. JWT uses JSON Web Signatures
	Web Encryption (JWE) [4] to secure the contents of the JWT, which is		(JWS) [RFC7515] and JSON Web Encryption (JWE) [RFC7516] to secure the
	a set of claims represented in JSON [5]. The use of JSON for		contents of the JWT, which is a set of claims represented in JSON
	encoding information is popular for Web and native applications, but		[RFC7519]. The use of JSON for encoding information is popular for
	it is considered inefficient for some Internet of Things (IoT)		Web and native applications, but it is considered inefficient for
	systems that use low power radio technologies.		some Internet of Things (IoT) systems that use low power radio
			technologies.
	In this document an alternative encoding of claims is defined.		In this document an alternative encoding of claims is defined.
	Instead of using JSON, as provided by JWTs, this specification uses		Instead of using JSON, as provided by JWTs, this specification uses
	CBOR [6] and calls this new structure "CBOR Web Token (CWT)", which		CBOR [RFC7049] and calls this new structure "CBOR Web Token (CWT)",
	is a compact means of representing secured claims to be transferred		which is a compact means of representing secured claims to be
	between two parties. CWT is closely related to JWT. It references		transferred between two parties. CWT is closely related to JWT. It
	the JWT claims and both its name and pronunciation are derived from		references the JWT claims and both its name and pronunciation are
	JWT. To protect the claims contained in CWTs, the CBOR Object		derived from JWT. To protect the claims contained in CWTs, the CBOR
	Signing and Encryption (COSE) [7] specification is used.		Object Signing and Encryption (COSE) [I-D.ietf-cose-msg]
			specification is used.
	The suggested pronunciation of CWT is the same as the English word		The suggested pronunciation of CWT is the same as the English word
	"cot".		"cot".
	2. Terminology		2. 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		"OPTIONAL" in this document are to be interpreted as described in
	"Key words for use in RFCs to Indicate Requirement Levels" [1].		"Key words for use in RFCs to Indicate Requirement Levels" [RFC2119].
	This document reuses terminology from JWT [5] and COSE [7].		This document reuses terminology from JWT [RFC7519] and COSE
			[I-D.ietf-cose-msg].
	Type3StringOrURI:		Type3StringOrURI:
	The "Type3StringOrURI" term has the same meaning, syntax, and		The "Type3StringOrURI" term has the same meaning, syntax, and
	processing rules as the "StringOrUri" term defined in Section 2 of		processing rules as the "StringOrUri" term defined in Section 2 of
	JWT [5], except that Type3StringOrURI uses CBOR major type 3		JWT [RFC7519], except that Type3StringOrURI uses CBOR major type 3
	instead of a JSON string value.		instead of a JSON string value.
	FIXME: Use tag 32 for URIs?
	Type6NumericDate:		Type6NumericDate:
	The "Type6NumericDate" term has the same meaning, syntax, and		The "Type6NumericDate" term has the same meaning, syntax, and
	processing rules as the "NumericDate" term defined in Section 2 of		processing rules as the "NumericDate" term defined in Section 2 of
	JWT [5], except that Type6NumericDate uses CBOR major type 6, with		JWT [RFC7519], except that Type6NumericDate uses CBOR major type
	tag value 1, instead of a numeric JSON value.		6, with tag value 1, instead of a numeric JSON value.
	CBOR encoded claim key:		CBOR encoded claim key:
	The key used to identify a claim value.		The key used to identify a claim value.
	3. Claims		3. Claims
	The set of claims that a CWT must contain to be considered valid is		The set of claims that a CWT must contain to be considered valid is
	context dependent and is outside the scope of this specification.		context dependent and is outside the scope of this specification.
	Specific applications of CWTs will require implementations to		Specific applications of CWTs will require implementations to
	skipping to change at page 4, line 20 ¶		skipping to change at page 4, line 31 ¶
	None of the claims defined below are intended to be mandatory to use		None of the claims defined below are intended to be mandatory to use
	or implement. They rather provide a starting point for a set of		or implement. They rather provide a starting point for a set of
	useful, interoperable claims. Applications using CWTs should define		useful, interoperable claims. Applications using CWTs should define
	which specific claims they use and when they are required or		which specific claims they use and when they are required or
	optional.		optional.
	3.1.1. iss (Issuer) Claim		3.1.1. iss (Issuer) Claim
	The "iss" (issuer) claim has the same meaning, syntax, and processing		The "iss" (issuer) claim has the same meaning, syntax, and processing
	rules as the "iss" claim defined in Section 4.1.1 of JWT [5], except		rules as the "iss" claim defined in Section 4.1.1 of JWT [RFC7519],
	that the format MUST be a Type3StringOrURI. The CBOR encoded claim		except that the format MUST be a Type3StringOrURI. The CBOR encoded
	key 1 MUST be used to identify this claim.		claim key 1 MUST be used to identify this claim.
	3.1.2. sub (Subject) Claim		3.1.2. sub (Subject) Claim
	The "sub" (subject) claim has the same meaning, syntax, and		The "sub" (subject) claim has the same meaning, syntax, and
	processing rules as the "sub" claim defined in Section 4.1.2 of JWT		processing rules as the "sub" claim defined in Section 4.1.2 of JWT
	[5], except that the format MUST be a Type3StringOrURI. The CBOR		[RFC7519], except that the format MUST be a Type3StringOrURI. The
	encoded claim key 2 MUST be used to identify this claim.		CBOR encoded claim key 2 MUST be used to identify this claim.
	3.1.3. aud (Audience) Claim		3.1.3. aud (Audience) Claim
	The "aud" (audience) claim has the same meaning, syntax, and		The "aud" (audience) claim has the same meaning, syntax, and
	processing rules as the "aud" claim defined in Section 4.1.3 of JWT		processing rules as the "aud" claim defined in Section 4.1.3 of JWT
	[5], except that the format MUST be a Type3StringOrURI. The CBOR		[RFC7519], except that the format MUST be a Type3StringOrURI. The
	encoded claim key 3 MUST be used to identify this claim.		CBOR encoded claim key 3 MUST be used to identify this claim.
	3.1.4. exp (Expiration Time) Claim		3.1.4. exp (Expiration Time) Claim
	The "exp" (expiration time) claim has the same meaning, syntax, and		The "exp" (expiration time) claim has the same meaning, syntax, and
	processing rules as the "exp" claim defined in Section 4.1.4 of JWT		processing rules as the "exp" claim defined in Section 4.1.4 of JWT
	[5], except that the format MUST be a Type6NumericDate. The CBOR		[RFC7519], except that the format MUST be a Type6NumericDate. The
	encoded claim key 4 MUST be used to identify this claim.		CBOR encoded claim key 4 MUST be used to identify this claim.
	3.1.5. nbf (Not Before) Claim		3.1.5. nbf (Not Before) Claim
	The "nbf" (not before) claim has the same meaning, syntax, and		The "nbf" (not before) claim has the same meaning, syntax, and
	processing rules as the "nbf" claim defined in Section 4.1.5 of JWT		processing rules as the "nbf" claim defined in Section 4.1.5 of JWT
	[5], except that the format MUST be a Type6NumericDate. The CBOR		[RFC7519], except that the format MUST be a Type6NumericDate. The
	encoded claim key 5 MUST be used to identify this claim.		CBOR encoded claim key 5 MUST be used to identify this claim.
	3.1.6. iat (Issued At) Claim		3.1.6. iat (Issued At) Claim
	The "iat" (issued at) claim has the same meaning, syntax, and		The "iat" (issued at) claim has the same meaning, syntax, and
	processing rules as the "iat" claim defined in Section 4.1.6 of JWT		processing rules as the "iat" claim defined in Section 4.1.6 of JWT
	[5], except that the format MUST be a Type6NumericDate. The CBOR		[RFC7519], except that the format MUST be a Type6NumericDate. The
	encoded claim key 6 MUST be used to identify this claim.		CBOR encoded claim key 6 MUST be used to identify this claim.
	3.1.7. cti (CWT ID) Claim		3.1.7. cti (CWT ID) Claim
	The "cti" (CWT ID) claim has the same meaning, syntax, and processing		The "cti" (CWT ID) claim has the same meaning, syntax, and processing
	rules as the "jti" claim defined in Section 4.1.7 of JWT [5], except		rules as the "jti" claim defined in Section 4.1.7 of JWT [RFC7519],
	that the format MUST be of major type 3 with a case-sensitive string		except that the format MUST be of major type 2, binary string. The
	value. The CBOR encoded claim key 7 MUST be used to identify this		CBOR encoded claim key 7 MUST be used to identify this claim.
	claim.
	4. Summary of the values, CBOR major types and encoded claim keys		4. Summary of the values, CBOR major types and encoded claim keys
	/---------+------------------------+--------------------------\		/---------+------------------------+--------------------------\
	| Claim | CBOR encoded claim key | CBOR major type of value |		| Claim | CBOR encoded claim key | CBOR major type of value |
	|---------+------------------------+--------------------------|		|---------+------------------------+--------------------------|
	| iss | 1 | 3 |		| iss | 1 | 3 |
	| sub | 2 | 3 |		| sub | 2 | 3 |
	| aud | 3 | 3 |		| aud | 3 | 3 |
	| exp | 4 | 6 tag value 1 |		| exp | 4 | 6 tag value 1 |
	| nbf | 5 | 6 tag value 1 |		| nbf | 5 | 6 tag value 1 |
	| iat | 6 | 6 tag value 1 |		| iat | 6 | 6 tag value 1 |
	| cti | 7 | 3 |		| cti | 7 | 2 |
	\---------+------------------------+--------------------------/		\---------+------------------------+--------------------------/
	Figure 1: Summary of the values, CBOR major types and encoded claim		Figure 1: Summary of the values, CBOR major types and encoded claim
	keys.		keys.
	Note: Claims defined by the OpenID Foundation have not yet been		5. Creating and Validating CWTs
	included in the table above.
	5. Security Considerations		5.1. Creating a CWT
			To create a CWT, the following steps are performed. The order of the
			steps is not significant in cases where there are no dependencies
			between the inputs and outputs of the steps.
			1. Create a CWT Claims Set containing the desired claims.
			2. Let the Message be the binary representation of the CWT Claims
			Set.
			3. Create a COSE Header containing the desired set of Header
			Parameters. The CWT Header MUST be a valid according to the
			[I-D.ietf-cose-msg] specification.
			4. Depending upon whether the CWT is signed, MACed or encrypted,
			there are three cases:
			* If the CWT is signed, create a COSE_Sign/COSE_Sign1 object
			using the Message as the COSE_Sign/COSE_Sign1 Payload; all
			steps specified in [I-D.ietf-cose-msg] for creating a
			COSE_Sign/COSE_Sign1 object MUST be followed.
			* Else, if the CWT is MACed, create a COSE_Mac/COSE_Mac0 object
			using the Message as the COSE_Mac/COSE_Mac0 Payload; all steps
			specified in [I-D.ietf-cose-msg] for creating a COSE_Mac/
			COSE_Mac0 object MUST be followed.
			* Else, if the CWT is a COSE_Encrypt/COSE_Encrypt0 object,
			create a COSE_Encrypt/COSE_Encrypt0 using the Message as the
			plaintext for the COSE_Encrypt/COSE_Encrypt0 object; all steps
			specified in [I-D.ietf-cose-msg] for creating a COSE_Encrypt/
			COSE_Encrypt0 object MUST be followed.
			5. If a nested signing, MACing or encryption operation will be
			performed, let the Message be the COSE_Sign/COSE_Sign1, COSE_Mac/
			COSE_Mac0 or COSE_Encrypt/COSE_Encrypt0, and return to Step 3,
			using "content type" header value of "CWT" in the new COSE Header
			created in that step.
			Note: If integrity (signing/MACing) and confidentiality
			(encryption) protection are needed, it is recommended to use an
			authenticated encryption algorithm to save space and processing.
			5.2. Validating a CWT
			When validating a CWT, the following steps are performed. The order
			of the steps is not significant in cases where there are no
			dependencies between the inputs and outputs of the steps. If any of
			the listed steps fail, then the CWT MUST be rejected -- that is,
			treated by the application as an invalid input.
			1. Verify that the CWT is a valid CBOR object.
			2. Verify that the resulting COSE Header includes only parameters
			and values whose syntax and semantics are both understood and
			supported or that are specified as being ignored when not
			understood.
			3. Use the CBOR tag to determine the type the CWT, COSE_Sign/
			COSE_Sign1, COSE_Mac/COSE_Mac0 or COSE_Encrypt/COSE_Encrypt0.
			4. Depending upon whether the CWT is a COSE_Sign/COSE_Sign1,
			COSE_Mac/COSE_Mac0 or COSE_Encrypt/COSE_Encrypt0, there are three
			cases:
			* If the CWT is a COSE_Sign/COSE_Sign1, follow the steps
			specified in [I-D.ietf-cose-msg] Section 4 (Signing Objects)
			for validating a COSE_Sign/COSE_Sign1 object. Let the Message
			be the COSE_Sign/COSE_Sign1 payload.
			* Else, if the CWT is a COSE_Mac/COSE_Mac0, follow the steps
			specified in [I-D.ietf-cose-msg] Section 6 (MAC Objects) for
			validating a COSE_Mac/COSE_Mac0 object. Let the Message be
			the COSE_Mac/COSE_Mac0 payload.
			* Else, if the CWT is a COSE_Encrypt/COSE_Encrypt0 object,
			follow the steps specified in [I-D.ietf-cose-msg] Section 5
			(Encryption Objects) for validating a COSE_Encrypt/
			COSE_Encrypt0 object. Let the Message be the resulting
			plaintext.
			5. If the JOSE Header contains a "content type" value of "CWT", then
			the Message is a CWT that was the subject of nested signing or
			encryption operations. In this case, return to Step 1, using the
			Message as the CWT.
			6. Verify that the Message is a valid CBOR object; let the CWT
			Claims Set be this CBOR object.
			6. Security Considerations
	The security of the CWT is dependent on the protection offered by		The security of the CWT is dependent on the protection offered by
	COSE. Without protecting the claims contained in a CWT an adversary		COSE. Without protecting the claims contained in a CWT an adversary
	is able to modify, add or remove claims. Since the claims conveyed		is able to modify, add or remove claims. Since the claims conveyed
	in a CWT are used to make authorization decisions it is not only		in a CWT are used to make authorization decisions it is not only
	important to protect the CWT in transit but also to ensure that the		important to protect the CWT in transit but also to ensure that the
	recipient is able to authenticate the party that collected the claims		recipient is able to authenticate the party that collected the claims
	and created the CWT. Without trust of the recipient in the party		and created the CWT. Without trust of the recipient in the party
	that created the CWT no sensible authorization decision can be made.		that created the CWT no sensible authorization decision can be made.
	Furthermore, the creator of the CWT needs to carefully evaluate each		Furthermore, the creator of the CWT needs to carefully evaluate each
	claim value prior to including it in the CWT so that the recipient		claim value prior to including it in the CWT so that the recipient
	can be assured about the correctness of the provided information.		can be assured about the correctness of the provided information.
	6. IANA Considerations		7. IANA Considerations
	This section will create a registry for CWT claims, possibly relating		7.1. CBOR Web Token (CWT) Claims Registry
	them to the JWT Claims Registry.
	7. Normative References		This section establishes the IANA "CBOR Web Token (CWT) Claims"
			registry.
	[1] Bradner, S., "Key words for use in RFCs to Indicate		Values are registered on a Specification Required [RFC5226] basis, on
			the advice of one or more Designated Experts. However, to allow for
			the allocation of values prior to publication, the Designated Experts
			may approve registration once they are satisfied that such a
			specification will be published.
			Criteria that should be applied by the Designated Experts includes
			determining whether the proposed registration duplicates existing
			functionality, whether it is likely to be of general applicability or
			whether it is useful only for a single application, and whether the
			registration description is clear.
			7.1.1. Registration Template
			Claim Name:
			The human-readable name requested (e.g., "iss").
			Claim Description:
			Brief description of the claim (e.g., "Issuer").
			JWT Claim Name:
			Claim Name of the equivalent JWT claim as registered in
			[IANA.JWT.Claims]. CWT claims should normally have a
			corresponding JWT claim. If a corresponding JWT claim would not
			make sense, the Designated Experts can choose to accept
			registrations for which the JWT Claim Name is listed as "N/A".
			CBOR Key Value:
			Key value for the claim. The key value MUST be an integer in the
			range of 1 to 65536.
			CBOR Major Type:
			CBOR Major type and optional tag for the claim.
			Change Controller:
			For Standards Track RFCs, list the "IESG". For others, give the
			name of the responsible party. Other details (e.g., postal
			address, email address, home page URI) may also be included.
			Specification Document(s):
			Reference to the document or documents that specify the parameter,
			preferably including URIs that can be used to retrieve copies of
			the documents. An indication of the relevant sections may also be
			included but is not required.
			7.1.2. Initial Registry Contents
			o Claim Name: "iss"
			o Claim Description: Issuer
			o JWT Claim Name: "iss"
			o CBOR Key Value: 1
			o CBOR Major Type: 3
			o Change Controller: IESG
			o Specification Document(s): Section 3.1.1 of [[ this specification
			]]
			o Claim Name: "sub"
			o Claim Description: Subject
			o JWT Claim Name: "sub"
			o CBOR Key Value: 2
			o CBOR Major Type: 3
			o Change Controller: IESG
			o Specification Document(s): Section 3.1.2 of [[ this specification
			]]
			o Claim Name: "aud"
			o Claim Description: Audience
			o JWT Claim Name: "aud"
			o CBOR Key Value: 3
			o CBOR Major Type: 3
			o Change Controller: IESG
			o Specification Document(s): Section 3.1.3 of [[ this specification
			]]
			o Claim Name: "exp"
			o Claim Description: Expiration Time
			o JWT Claim Name: "exp"
			o CBOR Key Value: 4
			o CBOR Major Type: 6, tag value 1
			o Change Controller: IESG
			o Specification Document(s): Section 3.1.4 of [[ this specification
			]]
			o Claim Name: "nbf"
			o Claim Description: Not Before
			o JWT Claim Name: "nbf"
			o CBOR Key Value: 5
			o CBOR Major Type: 6, tag value 1
			o Change Controller: IESG
			o Specification Document(s): Section 3.1.5 of [[ this specification
			]]
			o Claim Name: "iat"
			o Claim Description: Issued At
			o JWT Claim Name: "iat"
			o CBOR Key Value: 6
			o CBOR Major Type: 6, tag value 1
			o Change Controller: IESG
			o Specification Document(s): Section 3.1.6 of [[ this specification
			]]
			o Claim Name: "cti"
			o Claim Description: CWT ID
			o JWT Claim Name: "jti"
			o CBOR Key Value: 7
			o CBOR Major Type: 2
			o Change Controller: IESG
			o Specification Document(s): Section 3.1.7 of [[ this specification
			]]
			7.2. CoAP Content-Format Registration
			This section registers the "application/cwt" CoAP Content-Format ID
			in the "CoRE Parameters" sub-registry "CoAP Content-Format" in the
			manner described in [RFC7252].
			7.2.1. Registry Contents
			o Media Type: application/cwt
			o Encoding: -
			o Id: TBD (maybe 61)
			o Reference: [[ this specification ]]
			8. References
			8.1. Normative References
			[I-D.ietf-cose-msg]
			Schaad, J., "CBOR Object Signing and Encryption (COSE)",
			draft-ietf-cose-msg-14 (work in progress), June 2016.
			[IANA.JWT.Claims]
			IANA, "JSON Web Token Claims",
			<http://www.iana.org/assignments/jwt>.
			[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,
	<http://www.rfc-editor.org/info/rfc2119>.		<http://www.rfc-editor.org/info/rfc2119>.
	[2] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data		[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
			IANA Considerations Section in RFCs", BCP 26, RFC 5226,
			DOI 10.17487/RFC5226, May 2008,
			<http://www.rfc-editor.org/info/rfc5226>.
			[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
			Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
			October 2013, <http://www.rfc-editor.org/info/rfc7049>.
			[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
	Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March		Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
	2014, <http://www.rfc-editor.org/info/rfc7159>.		2014, <http://www.rfc-editor.org/info/rfc7159>.
	[3] Jones, M., Bradley, J., and N. Sakimura, "JSON Web		[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
			Application Protocol (CoAP)", RFC 7252,
			DOI 10.17487/RFC7252, June 2014,
			<http://www.rfc-editor.org/info/rfc7252>.
			[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
	Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May		Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
	2015, <http://www.rfc-editor.org/info/rfc7515>.		2015, <http://www.rfc-editor.org/info/rfc7515>.
	[4] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",		[RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
	RFC 7516, DOI 10.17487/RFC7516, May 2015,		RFC 7516, DOI 10.17487/RFC7516, May 2015,
	<http://www.rfc-editor.org/info/rfc7516>.		<http://www.rfc-editor.org/info/rfc7516>.
	[5] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token		[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
	(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,		(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
	<http://www.rfc-editor.org/info/rfc7519>.		<http://www.rfc-editor.org/info/rfc7519>.
	[6] Bormann, C. and P. Hoffman, "Concise Binary Object		8.2. Informative References
	Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
	October 2013, <http://www.rfc-editor.org/info/rfc7049>.
	[7] Schaad, J., "CBOR Encoded Message Syntax", draft-ietf-
	cose-msg-12 (work in progress), May 2016.
	[8] Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and		[I-D.seitz-ace-oauth-authz]
			Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and
	H. Tschofenig, "Authorization for the Internet of Things		H. Tschofenig, "Authorization for the Internet of Things
	using OAuth 2.0", draft-seitz-ace-oauth-authz-00 (work in		using OAuth 2.0", draft-seitz-ace-oauth-authz-00 (work in
	progress), October 2015.		progress), October 2015.
	Appendix A. Examples		Appendix A. Examples
	Three examples of CWTs follow.		Three examples of CWTs follow.
	A.1. CWT with "aud" and symmetric key		A.1. CWT with "aud" and symmetric key
	skipping to change at page 7, line 25 ¶		skipping to change at page 12, line 37 ¶
	[ // COSE_Key is a CBOR map with an array of keys		[ // COSE_Key is a CBOR map with an array of keys
	{		{
	"kty":4, // symmetric key is indicated using kty 4		"kty":4, // symmetric key is indicated using kty 4
	"k": "loremipsum" // the symmetric key		"k": "loremipsum" // the symmetric key
	}		}
	]		]
	}		}
	Figure 2: "aud" claim and symmetric key in non-normative JSON		Figure 2: "aud" claim and symmetric key in non-normative JSON
	Using the CBOR encoded claim keys according to Section 4 and COSE [7]		Using the CBOR encoded claim keys according to Section 4 and COSE
	makes a CWT with "aud" and a symmetric key look like this in CBOR		[I-D.ietf-cose-msg] makes a CWT with "aud" and a symmetric key look
	diagnostic notation:		like this in CBOR diagnostic notation:
	{		{
	3: "coap://light.example.com",		3: "coap://light.example.com",
	8:		8:
	[		[
	{		{
	1: 4,		1: 4,
	-1: "loremipsum"		-1: "loremipsum"
	}		}
	]		]
	skipping to change at page 8, line 44 ¶		skipping to change at page 14, line 21 ¶
	"kid": "11",		"kid": "11",
	"crv": 1, // using P-384		"crv": 1, // using P-384
	"x": h'bac5b11cad8f99f9c72b05cf4b9e26d244dc189f745228255a219a86d6a09eff',		"x": h'bac5b11cad8f99f9c72b05cf4b9e26d244dc189f745228255a219a86d6a09eff',
	"y": h'20138bf82dc1b6d562be0fa54ab7804a3a64b6d72ccfed6b6fb6ed28bbfc117e'		"y": h'20138bf82dc1b6d562be0fa54ab7804a3a64b6d72ccfed6b6fb6ed28bbfc117e'
	}		}
	]		]
	}		}
	Figure 5: "aud" claim and EC key in non-normative JSON		Figure 5: "aud" claim and EC key in non-normative JSON
	Using the CBOR encoded claim keys according to Section 4 and COSE [7]		Using the CBOR encoded claim keys according to Section 4 and COSE
	makes a CWT with "aud" and an EC key look like this in CBOR		[I-D.ietf-cose-msg] makes a CWT with "aud" and an EC key look like
	diagnostic notation:		this in CBOR diagnostic notation:
	{		{
	3: "coap://light.example.com",		3: "coap://light.example.com",
	8:		8:
	[		[
	{		{
	1: 2,		1: 2,
	2: "11",		2: "11",
	-1: 1,		-1: 1,
	-2: h'bac5b11cad8f99f9c72b05cf4b9e26d244dc189f745228255a219a86d6a09eff',		-2: h'bac5b11cad8f99f9c72b05cf4b9e26d244dc189f745228255a219a86d6a09eff',
	skipping to change at page 10, line 33 ¶		skipping to change at page 16, line 28 ¶
	"crv": 1, // using P-384		"crv": 1, // using P-384
	"x": h'bac5b11cad8f99f9c72b05cf4b9e26d244dc189f745228255a219a86d6a09eff',		"x": h'bac5b11cad8f99f9c72b05cf4b9e26d244dc189f745228255a219a86d6a09eff',
	"y": h'20138bf82dc1b6d562be0fa54ab7804a3a64b6d72ccfed6b6fb6ed28bbfc117e'		"y": h'20138bf82dc1b6d562be0fa54ab7804a3a64b6d72ccfed6b6fb6ed28bbfc117e'
	}		}
	],		],
	"aif": [["/s/light", 1], ["/a/led", 5], ["/dtls", 2]]		"aif": [["/s/light", 1], ["/a/led", 5], ["/dtls", 2]]
	}		}
	Figure 8: All claims, "aif" and EC key in non-normative JSON		Figure 8: All claims, "aif" and EC key in non-normative JSON
	Using the CBOR encoded claim keys according to Section 4 and COSE [7]		Using the CBOR encoded claim keys according to Section 4 and COSE
	makes a full CWT look like this in CBOR diagnostic notation:		[I-D.ietf-cose-msg] makes a full CWT look like this in CBOR
			diagnostic notation:
	{		{
	1: "coap://as.example.com",		1: "coap://as.example.com",
	3: "coap://light.example.com",		3: "coap://light.example.com",
	2: "erikw",		2: "erikw",
	4: 1(1444064944),		4: 1(1444064944),
	5: 1(1443944944),		5: 1(1443944944),
	6: 1(1443944944),		6: 1(1443944944),
	7: 2929,		7: 2929,
	8: [		8: [
	skipping to change at page 12, line 41 ¶		skipping to change at page 18, line 41 ¶
	2f64746c73 # "/dtls"		2f64746c73 # "/dtls"
	02 # unsigned(2)		02 # unsigned(2)
	Figure 10: Full CWT with EC in CBOR		Figure 10: Full CWT with EC in CBOR
	Size of the CWT with an EC key is 194 bytes. This is then packaged		Size of the CWT with an EC key is 194 bytes. This is then packaged
	signed and encrypted using COSE.		signed and encrypted using COSE.
	Appendix B. Acknowledgements		Appendix B. Acknowledgements
	A straw man proposal of CWT was written in the draft "Authorization		This specification is based on JSON Web Token (JWT) [RFC7519], the
	for the Internet of Things using OAuth 2.0" [8] with the help of		authors of which also include Nat Sakimura and John Bradley. A straw
	Ludwig Seitz, Goeran Selander, and Samuel Erdtman.		man proposal of CWT was written in the draft "Authorization for the
			Internet of Things using OAuth 2.0" [I-D.seitz-ace-oauth-authz] with
			the help of Ludwig Seitz and Goeran Selander.
	Appendix C. Document History		Appendix C. Document History
	[[ to be removed by the RFC Editor before publication as an RFC ]]		[[ to be removed by the RFC Editor before publication as an RFC ]]
			-01
			o Added IANA registration for CWT Claims.
			o Added IANA registration for the application/cwt CoAP content-
			format type.
			o Added Samuel Erdtman as an editor.
			o Changed Erik's e-mail address.
	-00		-00
	o Created the initial working group version based on draft-		o Created the initial working group version based on draft-
	wahlstroem-ace-cbor-web-token-00.		wahlstroem-ace-cbor-web-token-00.
	Authors' Addresses		Authors' Addresses
	Erik Wahlstroem		Erik Wahlstroem
	Nexus Technology
	Sweden		Sweden
	Email: erik.wahlstrom@nexusgroup.com		Email: erik@wahlstromstekniska.se
	URI: https://www.nexusgroup.com
	Michael B. Jones		Michael B. Jones
	Microsoft		Microsoft
	Email: mbj@microsoft.com		Email: mbj@microsoft.com
	URI: http://self-issued.info/		URI: http://self-issued.info/
	Hannes Tschofenig		Hannes Tschofenig
	ARM Ltd.		ARM Ltd.
	Hall in Tirol 6060		Hall in Tirol 6060
	Austria		Austria
	Email: Hannes.Tschofenig@arm.com		Email: Hannes.Tschofenig@arm.com
			Samuel Erdtman
			Spotify AB
			Birger Jarlsgatan 61, 4tr
			Stockholm 113 56
			Sweden
			Phone: +46702691499
			Email: erdtman@spotify.com
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