< draft-ietf-ace-cbor-web-token-13.txt		draft-ietf-ace-cbor-web-token-14.txt >
	ACE Working Group M. Jones		ACE Working Group M. Jones
	Internet-Draft Microsoft		Internet-Draft Microsoft
	Intended status: Standards Track E. Wahlstroem		Intended status: Standards Track E. Wahlstroem
	Expires: September 6, 2018		Expires: September 16, 2018
	S. Erdtman		S. Erdtman
	Spotify AB		Spotify AB
	H. Tschofenig		H. Tschofenig
	ARM Ltd.		ARM Ltd.
	March 5, 2018		March 15, 2018
	CBOR Web Token (CWT)		CBOR Web Token (CWT)
	draft-ietf-ace-cbor-web-token-13		draft-ietf-ace-cbor-web-token-14
	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. The claims in a CWT are encoded in		transferred between two parties. The claims in a CWT are encoded in
	the Concise Binary Object Representation (CBOR) and CBOR Object		the Concise Binary Object Representation (CBOR) and CBOR Object
	Signing and Encryption (COSE) is used for added application layer		Signing and Encryption (COSE) is used for added application layer
	security protection. A claim is a piece of information asserted		security protection. A claim is a piece of information asserted
	about a subject and is represented as a name/value pair consisting of		about a subject and is represented as a name/value pair consisting of
	a claim name and a claim value. CWT is derived from JSON Web Token		a claim name and a claim value. CWT is derived from JSON Web Token
	skipping to change at page 1, line 42 ¶		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 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 September 6, 2018.		This Internet-Draft will expire on September 16, 2018.
	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 3, line 13 ¶		skipping to change at page 3, line 13 ¶
	A.2.1. 128-bit Symmetric Key . . . . . . . . . . . . . . . . 17		A.2.1. 128-bit Symmetric Key . . . . . . . . . . . . . . . . 17
	A.2.2. 256-bit Symmetric Key . . . . . . . . . . . . . . . . 17		A.2.2. 256-bit Symmetric Key . . . . . . . . . . . . . . . . 17
	A.2.3. ECDSA P-256 256-bit COSE Key . . . . . . . . . . . . 17		A.2.3. ECDSA P-256 256-bit COSE Key . . . . . . . . . . . . 17
	A.3. Example Signed CWT . . . . . . . . . . . . . . . . . . . 18		A.3. Example Signed CWT . . . . . . . . . . . . . . . . . . . 18
	A.4. Example MACed CWT . . . . . . . . . . . . . . . . . . . . 19		A.4. Example MACed CWT . . . . . . . . . . . . . . . . . . . . 19
	A.5. Example Encrypted CWT . . . . . . . . . . . . . . . . . . 20		A.5. Example Encrypted CWT . . . . . . . . . . . . . . . . . . 20
	A.6. Example Nested CWT . . . . . . . . . . . . . . . . . . . 21		A.6. Example Nested CWT . . . . . . . . . . . . . . . . . . . 21
	A.7. Example MACed CWT with a floating-point value . . . . . . 22		A.7. Example MACed CWT with a floating-point value . . . . . . 22
	Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 23		Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 23
	Appendix C. Document History . . . . . . . . . . . . . . . . . . 23		Appendix C. Document History . . . . . . . . . . . . . . . . . . 23
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
	1. Introduction		1. Introduction
	The JSON Web Token (JWT) [RFC7519] is a standardized security token		The JSON Web Token (JWT) [RFC7519] is a standardized security token
	format that has found use in OAuth 2.0 and OpenID Connect		format that has found use in OAuth 2.0 and OpenID Connect
	deployments, among other applications. JWT uses JSON Web Signature		deployments, among other applications. JWT uses JSON Web Signature
	(JWS) [RFC7515] and JSON Web Encryption (JWE) [RFC7516] to secure the		(JWS) [RFC7515] and JSON Web Encryption (JWE) [RFC7516] to secure the
	contents of the JWT, which is a set of claims represented in JSON.		contents of the JWT, which is a set of claims represented in JSON.
	The use of JSON for encoding information is popular for Web and		The use of JSON for encoding information is popular for Web and
	native applications, but it is considered inefficient for some		native applications, but it is considered inefficient for some
	skipping to change at page 4, line 11 ¶		skipping to change at page 4, line 11 ¶
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in BCP		"OPTIONAL" in this document are to be interpreted as described in BCP
	14 [RFC2119] [RFC8174] when, and only when, they appear in all		14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	This document reuses terminology from JWT [RFC7519] and COSE		This document reuses terminology from JWT [RFC7519] and COSE
	[RFC8152].		[RFC8152].
	StringOrURI		StringOrURI
	The "StringOrURI" term has the same meaning and processing rules		The "StringOrURI" term in this specification has the same meaning
	as the "StringOrURI" term defined in Section 2 of [RFC7519],		and processing rules as the JWT "StringOrURI" term defined in
	except that it uses a CBOR text string instead of a JSON string		Section 2 of [RFC7519], except that it is represented as a CBOR
	value.		text string instead of a JSON text string.
	NumericDate		NumericDate
	The "NumericDate" term has the same meaning and processing rules		The "NumericDate" term in this specification has the same meaning
	as the "NumericDate" term defined in Section 2 of [RFC7519],		and processing rules as the JWT "NumericDate" term defined in
	except that the CBOR numeric date representation (from		Section 2 of [RFC7519], except that it is represented as a CBOR
	Section 2.4.1 of [RFC7049]) is used. The encoding is modified so		numeric date (from Section 2.4.1 of [RFC7049]) instead of a JSON
	that the leading tag 1 (epoch-based date/time) MUST be omitted.		number. The encoding is modified so that the leading tag 1
			(epoch-based date/time) MUST be omitted.
	Claim Name		Claim Name
	The human-readable name used to identify a claim.		The human-readable name used to identify a claim.
	Claim Key		Claim Key
	The CBOR map key used to identify a claim.		The CBOR map key used to identify a claim.
	Claim Value		Claim Value
	The CBOR map value representing the value of the claim.		The CBOR map value representing the value of the claim.
	skipping to change at page 5, line 17 ¶		skipping to change at page 5, line 17 ¶
	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 and processing rules as		The "iss" (issuer) claim has the same meaning and processing rules as
	the "iss" claim defined in Section 4.1.1 of [RFC7519], except that		the "iss" claim defined in Section 4.1.1 of [RFC7519], except that
	the value is of type StringOrURI. The Claim Key 1 is used to		the value is a StringOrURI. The Claim Key 1 is used to identify this
	identify this claim.		claim.
	3.1.2. sub (Subject) Claim		3.1.2. sub (Subject) Claim
	The "sub" (subject) claim has the same meaning and processing rules		The "sub" (subject) claim has the same meaning and processing rules
	as the "sub" claim defined in Section 4.1.2 of [RFC7519], except that		as the "sub" claim defined in Section 4.1.2 of [RFC7519], except that
	the value is of type StringOrURI. The Claim Key 2 is used to		the value is a StringOrURI. The Claim Key 2 is used to identify this
	identify this claim.		claim.
	3.1.3. aud (Audience) Claim		3.1.3. aud (Audience) Claim
	The "aud" (audience) claim has the same meaning and processing rules		The "aud" (audience) claim has the same meaning and processing rules
	as the "aud" claim defined in Section 4.1.3 of [RFC7519], except that		as the "aud" claim defined in Section 4.1.3 of [RFC7519], except that
	the value of the audience claim is of type StringOrURI when it is not		the value of the audience claim is a StringOrURI when it is not an
	an array or the values of the audience array elements are of type		array or each of the audience array element values is a StringOrURI
	StringOrURI when the audience claim value is an array. The Claim Key		when the audience claim value is an array. The Claim Key 3 is used
	3 is used to identify this claim.		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 and processing		The "exp" (expiration time) claim has the same meaning and processing
	rules as the "exp" claim defined in Section 4.1.4 of [RFC7519],		rules as the "exp" claim defined in Section 4.1.4 of [RFC7519],
	except that the value is of type NumericDate. The Claim Key 4 is		except that the value is a NumericDate. The Claim Key 4 is used to
	used to identify this claim.		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 and processing		The "nbf" (not before) claim has the same meaning and processing
	rules as the "nbf" claim defined in Section 4.1.5 of [RFC7519],		rules as the "nbf" claim defined in Section 4.1.5 of [RFC7519],
	except that the value is of type NumericDate. The Claim Key 5 is		except that the value is a NumericDate. The Claim Key 5 is used to
	used to identify this claim.		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 and processing rules		The "iat" (issued at) claim has the same meaning and processing rules
	as the "iat" claim defined in Section 4.1.6 of [RFC7519], except that		as the "iat" claim defined in Section 4.1.6 of [RFC7519], except that
	the value is of type NumericDate. The Claim Key 6 is used to		the value is a NumericDate. The Claim Key 6 is used to identify this
	identify this claim.		claim.
	3.1.7. cti (CWT ID) Claim		3.1.7. cti (CWT ID) Claim
	The "cti" (CWT ID) claim has the same meaning and processing rules as		The "cti" (CWT ID) claim has the same meaning and processing rules as
	the "jti" claim defined in Section 4.1.7 of [RFC7519], except that		the "jti" claim defined in Section 4.1.7 of [RFC7519], except that
	the value is of type byte string. The Claim Key 7 is used to		the value is a byte string. The Claim Key 7 is used to identify this
	identify this claim.		claim.
	4. Summary of the claim names, keys, and value types		4. Summary of the claim names, keys, and value types
	+------+-----+----------------------------------+		+------+-----+----------------------------------+
	| Name | Key | Value type |		| Name | Key | Value type |
	+------+-----+----------------------------------+		+------+-----+----------------------------------+
	| iss | 1 | text string |		| iss | 1 | text string |
	| sub | 2 | text string |		| sub | 2 | text string |
	| aud | 3 | text string |		| aud | 3 | text string |
	| exp | 4 | integer or floating-point number |		| exp | 4 | integer or floating-point number |
	skipping to change at page 9, line 41 ¶		skipping to change at page 9, line 41 ¶
	Since the claims conveyed in a CWT may be used to make authorization		Since the claims conveyed in a CWT may be used to make authorization
	decisions, it is not only important to protect the CWT in transit but		decisions, it is not only important to protect the CWT in transit but
	also to ensure that the recipient can authenticate the party that		also to ensure that the recipient can authenticate the party that
	assembled the claims and created the CWT. Without trust of the		assembled the claims and created the CWT. Without trust of the
	recipient in the party that created the CWT, no sensible		recipient in the party that created the CWT, no sensible
	authorization decision can be made. Furthermore, the creator of the		authorization decision can be made. Furthermore, the creator of the
	CWT needs to carefully evaluate each claim value prior to including		CWT needs to carefully evaluate each claim value prior to including
	it in the CWT so that the recipient can be assured of the validity of		it in the CWT so that the recipient can be assured of the validity of
	the information provided.		the information provided.
	While syntactically, the signing and encryption operations for Nested		While syntactically the signing and encryption operations for Nested
	CWTs may be applied in any order, if both signing and encryption are		CWTs may be applied in any order, if both signing and encryption are
	necessary, normally producers should sign the message and then		necessary, normally producers should sign the message and then
	encrypt the result (thus encrypting the signature). This prevents		encrypt the result (thus encrypting the signature). This prevents
	attacks in which the signature is stripped, leaving just an encrypted		attacks in which the signature is stripped, leaving just an encrypted
	message, as well as providing privacy for the signer. Furthermore,		message, as well as providing privacy for the signer. Furthermore,
	signatures over encrypted text are not considered valid in many		signatures over encrypted text are not considered valid in many
	jurisdictions.		jurisdictions.
	9. IANA Considerations		9. IANA Considerations
	skipping to change at page 10, line 36 ¶		skipping to change at page 10, line 36 ¶
	iesg@ietf.org mailing list) for resolution.		iesg@ietf.org mailing list) for resolution.
	Criteria that should be applied by the Designated Experts includes		Criteria that should be applied by the Designated Experts includes
	determining whether the proposed registration duplicates existing		determining whether the proposed registration duplicates existing
	functionality, whether it is likely to be of general applicability or		functionality, whether it is likely to be of general applicability or
	whether it is useful only for a single application, and whether the		whether it is useful only for a single application, and whether the
	registration description is clear. Registrations for the limited set		registration description is clear. Registrations for the limited set
	of values between -256 and 255 and strings of length 1 are to be		of values between -256 and 255 and strings of length 1 are to be
	restricted to claims with general applicability.		restricted to claims with general applicability.
			IANA must only accept registry updates from the Designated Experts
			and should direct all requests for registration to the review mailing
			list.
	It is suggested that multiple Designated Experts be appointed who are		It is suggested that multiple Designated Experts be appointed who are
	able to represent the perspectives of different applications using		able to represent the perspectives of different applications using
	this specification in order to enable broadly informed review of		this specification in order to enable broadly informed review of
	registration decisions. In cases where a registration decision could		registration decisions. In cases where a registration decision could
	be perceived as creating a conflict of interest for a particular		be perceived as creating a conflict of interest for a particular
	Expert, that Expert should defer to the judgment of the other		Expert, that Expert should defer to the judgment of the other
	Experts.		Experts.
	Since a high degree of overlap is expected between the contents of		Since a high degree of overlap is expected between the contents of
	the "CBOR Web Token (CWT) Claims" registry and the "JSON Web Token		the "CBOR Web Token (CWT) Claims" registry and the "JSON Web Token
	skipping to change at page 11, line 22 ¶		skipping to change at page 11, line 22 ¶
	JWT Claim Name:		JWT Claim Name:
	Claim Name of the equivalent JWT claim, as registered in		Claim Name of the equivalent JWT claim, as registered in
	[IANA.JWT.Claims]. CWT claims should normally have a		[IANA.JWT.Claims]. CWT claims should normally have a
	corresponding JWT claim. If a corresponding JWT claim would not		corresponding JWT claim. If a corresponding JWT claim would not
	make sense, the Designated Experts can choose to accept		make sense, the Designated Experts can choose to accept
	registrations for which the JWT Claim Name is listed as "N/A".		registrations for which the JWT Claim Name is listed as "N/A".
	Claim Key:		Claim Key:
	CBOR map key for the claim. Different ranges of values use		CBOR map key for the claim. Different ranges of values use
	different registration policies [RFC8126]. Integer values between		different registration policies [RFC8126]. Integer values from
	-256 and 255 and strings of length 1 are designated as Standards		-256 to 255 and strings of length 1 are designated as Standards
	Action. Integer values from -65536 to 65535 and strings of length		Action. Integer values from -65536 to -257 and from 256 to 65535
	2 are designated as Specification Required. Integer values of		and strings of length 2 are designated as Specification Required.
	greater than 65535 and strings of length greater than 2 are		Integer values greater than 65535 and strings of length greater
	designated as Expert Review. Integer values less than -65536 are		than 2 are designated as Expert Review. Integer values less than
	marked as Private Use.		-65536 are marked as Private Use.
	Claim Value Type(s):		Claim Value Type(s):
	CBOR types that can be used for the claim value.		CBOR types that can be used for the claim value.
	Change Controller:		Change Controller:
	For Standards Track RFCs, list the "IESG". For others, give the		For Standards Track RFCs, list the "IESG". For others, give the
	name of the responsible party. Other details (e.g., postal		name of the responsible party. Other details (e.g., postal
	address, email address, home page URI) may also be included.		address, email address, home page URI) may also be included.
	Specification Document(s):		Specification Document(s):
	skipping to change at page 23, line 28 ¶		skipping to change at page 23, line 28 ¶
	)		)
	Figure 19: MACed CWT with a floating-point value in CBOR diagnostic		Figure 19: MACed CWT with a floating-point value in CBOR diagnostic
	notation		notation
	Appendix B. Acknowledgements		Appendix B. Acknowledgements
	This specification is based on JSON Web Token (JWT) [RFC7519], the		This specification is based on JSON Web Token (JWT) [RFC7519], the
	authors of which also include Nat Sakimura and John Bradley. It also		authors of which also include Nat Sakimura and John Bradley. It also
	incorporates suggestions made by many people, including Carsten		incorporates suggestions made by many people, including Carsten
	Bormann, Esko Dijk, Benjamin Kaduk, Carlos Martinez, Kathleen		Bormann, Alissa Cooper, Esko Dijk, Benjamin Kaduk, Warren Kumari,
	Moriarty, Dan Romascanu, Kyle Rose, Jim Schaad, Ludwig Seitz, and		Carlos Martinez, Alexey Melnikov, Kathleen Moriarty, Eric Rescorla,
			Dan Romascanu, Adam Roach, Kyle Rose, Jim Schaad, Ludwig Seitz, and
	Goeran Selander.		Goeran Selander.
	[[ RFC Editor: Is it possible to preserve the non-ASCII spellings of		[[ RFC Editor: Is it possible to preserve the non-ASCII spellings of
	the names Erik Wahlstroem and Goeran Selander in the final		the names Erik Wahlstroem and Goeran Selander in the final
	specification? ]]		specification? ]]
	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 ]]
			-14
			o Cleaned up the descriptions of the numeric ranges of claim keys
			being registered in the registration template for the "CBOR Web
			Token (CWT) Claims" registry, as suggested by Adam Roach.
			o Clarified the relationships between the JWT and CWT "NumericDate"
			and "StringOrURI" terms, as suggested by Adam Roach.
			o Eliminated unnecessary uses of the word "type", as suggested by
			Adam Roach.
			o Added the text "IANA must only accept registry updates from the
			Designated Experts and should direct all requests for registration
			to the review mailing list" from RFC 7519, as suggested by Amanda
			Baber of IANA, which is also intended to address Alexey Melnikov's
			comment.
			o Removed a superfluous comma, as suggested by Warren Kumari.
			o Acknowledged additional reviewers.
	-13		-13
	o Clarified the registration criteria applied to different ranges of		o Clarified the registration criteria applied to different ranges of
	Claim Key values, as suggested by Kathleen Moriarty and Dan		Claim Key values, as suggested by Kathleen Moriarty and Dan
	Romascanu.		Romascanu.
	o No longer describe the syntax of CWT claims as being the same as		o No longer describe the syntax of CWT claims as being the same as
	that of the corresponding JWT claims, as suggested by Kyle Rose.		that of the corresponding JWT claims, as suggested by Kyle Rose.
	o Added guidance about the selection of the Designated Experts, as		o Added guidance about the selection of the Designated Experts, as
End of changes. 19 change blocks.
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