< draft-ietf-stir-enhance-rfc8226-03.txt		draft-ietf-stir-enhance-rfc8226-04.txt >
	Network Working Group R. Housley		Network Working Group R. Housley
	Internet-Draft Vigil Security		Internet-Draft Vigil Security
	Updates: 8226 (if approved) 10 June 2021		Updates: 8226 (if approved) 30 June 2021
	Intended status: Standards Track		Intended status: Standards Track
	Expires: 12 December 2021		Expires: 1 January 2022
	Enhanced JWT Claim Constraints for STIR Certificates		Enhanced JWT Claim Constraints for STIR Certificates
	draft-ietf-stir-enhance-rfc8226-03		draft-ietf-stir-enhance-rfc8226-04
	Abstract		Abstract
	RFC 8226 specifies the use of certificates for Secure Telephone		RFC 8226 specifies the use of certificates for Secure Telephone
	Identity Credentials, and these certificates are often called "STIR		Identity Credentials, and these certificates are often called "STIR
	Certificates". RFC 8226 provides a certificate extension to		Certificates". RFC 8226 provides a certificate extension to
	constrain the JSON Web Token (JWT) claims that can be included in the		constrain the JSON Web Token (JWT) claims that can be included in the
	Personal Assertion Token (PASSporT) as defined in RFC 8225. If the		Personal Assertion Token (PASSporT) as defined in RFC 8225. If the
	PASSporT signer includes a JWT claim outside the constraint		PASSporT signer includes a JWT claim outside the constraint
	boundaries, then the PASSporT recipient will reject the entire		boundaries, then the PASSporT recipient will reject the entire
	PASSporT. This document updates RFC 8226 to define an additional way		PASSporT. This document updates RFC 8226; it provides all of the
	that the JWT claims can be constrained.		capabilities available in the original certificate extension as well
			as an additional way to constrain the allowable JWT claims. The
			enhanced extension can also provide a list of claims that are not
			allowed to be included in the PASSporT.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	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 12 December 2021.		This Internet-Draft will expire on 1 January 2022.
	Copyright Notice		Copyright Notice
	Copyright (c) 2021 IETF Trust and the persons identified as the		Copyright (c) 2021 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	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 (https://trustee.ietf.org/		Provisions Relating to IETF Documents (https://trustee.ietf.org/
	license-info) in effect on the date of publication of this document.		license-info) in effect on the date of publication of this document.
	Please review these documents carefully, as they describe your rights		Please review these documents carefully, as they describe your rights
	and restrictions with respect to this document. Code Components		and restrictions with respect to this document. Code Components
	extracted from this document must include Simplified BSD License text		extracted from this document must include Simplified BSD License text
	as described in Section 4.e of the Trust Legal Provisions and are		as described in Section 4.e of the Trust Legal Provisions and are
	provided without warranty as described in the Simplified BSD License.		provided without warranty as described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
	3. Enhanced JWT Claim Constraints Syntax . . . . . . . . . . . . 3		3. Enhanced JWT Claim Constraints Syntax . . . . . . . . . . . . 3
	4. Usage Examples . . . . . . . . . . . . . . . . . . . . . . . 4		4. Usage Examples . . . . . . . . . . . . . . . . . . . . . . . 5
	5. Certificate Extension Example . . . . . . . . . . . . . . . . 5		5. Certificate Extension Example . . . . . . . . . . . . . . . . 5
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7		6. Guidance to Certification Authorities . . . . . . . . . . . . 7
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 7		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
	8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8		8. Security Considerations . . . . . . . . . . . . . . . . . . . 7
	9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8		9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
	9.1. Normative References . . . . . . . . . . . . . . . . . . 8		10. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
	9.2. Informative References . . . . . . . . . . . . . . . . . 9		10.1. Normative References . . . . . . . . . . . . . . . . . . 8
	Appendix A. ASN.1 Module . . . . . . . . . . . . . . . . . . . . 9		10.2. Informative References . . . . . . . . . . . . . . . . . 9
			Appendix A. ASN.1 Module . . . . . . . . . . . . . . . . . . . . 10
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 11		Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 11
	1. Introduction		1. Introduction
	The use of certificates [RFC5280] in establishing authority over		The use of certificates [RFC5280] in establishing authority over
	telephone numbers is described in [RFC8226]. These certificates are		telephone numbers is described in [RFC8226]. These certificates are
	often called "STIR Certificates". STIR certificates are an important		often called "STIR Certificates". STIR certificates are an important
	element of the overall system that prevents the impersonation of		element of the overall system that prevents the impersonation of
	telephone numbers on the Internet.		telephone numbers on the Internet.
	skipping to change at page 4, line 8 ¶		skipping to change at page 4, line 8 ¶
	required by [RFC8225], and these claims SHOULD NOT be part of the		required by [RFC8225], and these claims SHOULD NOT be part of the
	mustInclude list. If mustInclude is absent, the iat, orig, and		mustInclude list. If mustInclude is absent, the iat, orig, and
	dest claims MUST appear in the PASSporT.		dest claims MUST appear in the PASSporT.
	2. permittedValues indicates that if the claim name is present, the		2. permittedValues indicates that if the claim name is present, the
	claim MUST exactly match one of the listed values.		claim MUST exactly match one of the listed values.
	3. mustExclude indicates JWT claims that MUST NOT appear in the		3. mustExclude indicates JWT claims that MUST NOT appear in the
	PASSporT. The baseline PASSporT claims ("iat", "orig", and		PASSporT. The baseline PASSporT claims ("iat", "orig", and
	"dest") are always permitted, and these claims MUST NOT be part		"dest") are always permitted, and these claims MUST NOT be part
	of the mustExclude list.		of the mustExclude list. If one of these baseline PASSporT
			claims appears in the mustExclude list, then the certificate MUST
			be treated as if the extension was not present.
			Following the precedent in [RFC8226], JWT Claim Names MUST be ASCII
			strings, which are also known as strings using the International
			Alphabet No. 5 [ISO646].
	The Enhanced JWT Claim Constraints certificate extension is		The Enhanced JWT Claim Constraints certificate extension is
	identified by the following object identifier (OID):		identified by the following object identifier (OID):
	id-pe-eJWTClaimConstraints OBJECT IDENTIFIER ::= { id-pe TBD1 }		id-pe-eJWTClaimConstraints OBJECT IDENTIFIER ::= { id-pe TBD1 }
	The Enhanced JWT Claim Constraints certificate extension has the		The Enhanced JWT Claim Constraints certificate extension has the
	following syntax:		following syntax:
	EnhancedJWTClaimConstraints ::= SEQUENCE {		EnhancedJWTClaimConstraints ::= SEQUENCE {
	skipping to change at page 5, line 15 ¶		skipping to change at page 5, line 27 ¶
	service will treat as invalid any PASSporT it receives without a		service will treat as invalid any PASSporT it receives without a
	"confidence" PASSporT claim.		"confidence" PASSporT claim.
	* If a CA issues a certificate to an authentication service that		* If a CA issues a certificate to an authentication service that
	includes an Enhanced JWT Claim Constraints certificate extension		includes an Enhanced JWT Claim Constraints certificate extension
	that contains the permittedValues JWTClaimName "confidence" and a		that contains the permittedValues JWTClaimName "confidence" and a
	permitted "high" value, then a verification service will treat as		permitted "high" value, then a verification service will treat as
	invalid any PASSporT it receives with a PASSporT "confidence"		invalid any PASSporT it receives with a PASSporT "confidence"
	claim with a value other than "high". However, a verification		claim with a value other than "high". However, a verification
	service will not treat as invalid a PASSporT it receives without a		service will not treat as invalid a PASSporT it receives without a
	PASSporT "confidence" claim at all.		PASSporT "confidence" claim at all, unless "confidence" also
			appears in mustInclude.
	* If a CA issues a certificate to an authentication service that		* If a CA issues a certificate to an authentication service that
	includes an Enhanced JWT Claim Constraints certificate extension		includes an Enhanced JWT Claim Constraints certificate extension
	that contains the mustExclude JWTClaimName "confidence", then a		that contains the mustExclude JWTClaimName "confidence", then a
	verification service will treat as invalid any PASSporT it		verification service will treat as invalid any PASSporT it
	receives with a PASSporT "confidence" claim regardless of the		receives with a PASSporT "confidence" claim regardless of the
	claim value.		claim value.
	5. Certificate Extension Example		5. Certificate Extension Example
	skipping to change at page 7, line 5 ¶		skipping to change at page 7, line 5 ¶
	: }		: }
	52 12: [2] {		52 12: [2] {
	54 10: SEQUENCE {		54 10: SEQUENCE {
	56 8: IA5String 'priority'		56 8: IA5String 'priority'
	: }		: }
	: }		: }
	: }		: }
	Figure 2. Example EnhancedJWTClaimConstraints extension.		Figure 2. Example EnhancedJWTClaimConstraints extension.
	6. IANA Considerations		6. Guidance to Certification Authorities
			The EnhancedJWTClaimConstraints extension specified in this document
			and the JWTClaimConstraints extension specified in [RFC8226] MUST NOT
			both appear in the same certificate.
			If the situation calls for mustExclude constraints, then the
			EnhancedJWTClaimConstraints extension is the only extension that can
			express the constraints.
			On the other hand, if the situation does not call for mustExclude
			constraints, then either the EnhancedJWTClaimConstraints extension or
			the JWTClaimConstraints extension can express the constraints. Until
			such time as the EnhancedJWTClaimConstraints become widely
			implemented, the use of the JWTClaimConstraints extension may be more
			likely to be implemented. This guess is based on the presumption
			that the first specified extension will be implemented more widely in
			the next few years.
			7. IANA Considerations
	This document makes use of object identifiers for the Enhanced JWT		This document makes use of object identifiers for the Enhanced JWT
	Claim Constraints certificate extension defined in Section 3 and the		Claim Constraints certificate extension defined in Section 3 and the
	ASN.1 module identifier defined in Appendix A. Therefore, IANA is		ASN.1 module identifier defined in Appendix A. Therefore, IANA is
	asked to made the following assignments within the SMI Numbers		asked to made the following assignments within the SMI Numbers
	Registry.		Registry.
	For the Enhanced JWT Claim Constraints certificate extension in the		For the Enhanced JWT Claim Constraints certificate extension in the
	"SMI Security for PKIX Certificate Extension" (1.3.6.1.5.5.7.1)		"SMI Security for PKIX Certificate Extension" (1.3.6.1.5.5.7.1)
	registry:		registry:
	TBD1 id-pe-eJWTClaimConstraints		TBD1 id-pe-eJWTClaimConstraints
	For the ASN.1 module identifier in the "SMI Security for PKIX Module		For the ASN.1 module identifier in the "SMI Security for PKIX Module
	Identifier" (1.3.6.1.5.5.7.0) registry:		Identifier" (1.3.6.1.5.5.7.0) registry:
	TBD2 id-mod-eJWTClaimConstraints-2021		TBD2 id-mod-eJWTClaimConstraints-2021
	7. Security Considerations		8. Security Considerations
	For further information on certificate security and practices, see		For further information on certificate security and practices, see
	[RFC5280], especially the Security Considerations section.		[RFC5280], especially the Security Considerations section.
			Since non-critical certificate extension are ignored by
			implementations that do not recognize the extension object identifier
			(OID), constraints on PASSporT validation will only be applied by
			relying parties that recognize the EnhancedJWTClaimConstraints
			extension.
	The Enhanced JWT Claim Constraints certificate extension can be used		The Enhanced JWT Claim Constraints certificate extension can be used
	by certificate issuers to provide limits on the acceptable PASSporTs		by certificate issuers to provide limits on the acceptable PASSporTs
	that will be accepted by verification services. Enforcement of these		that can be accepted by verification services. Enforcement of these
	limits depends upon proper implementation by the verification		limits depends upon proper implementation by the verification
	services. The digital signature on the PASSportT data structure will		services. The digital signature on the PASSportT data structure will
	be valid even if the limits are violated.		be valid even if the limits are violated.
	Use of the Enhanced JWT Claim Constraints certificate extension		Use of the Enhanced JWT Claim Constraints certificate extension
	permittedValues constraint is most useful when the claim definition		permittedValues constraint is most useful when the claim definition
	allows a specified set of values. In this way, all of the values		allows a specified set of values. In this way, all of the values
	that are not listed in the JWTClaimValuesList are prohibited in a		that are not listed in the JWTClaimValuesList are prohibited in a
	valid PASSporT.		valid PASSporT.
	Certificate issuers must take care when imposing constraints on the		Certificate issuers must take care when imposing constraints on the
	PASSporT claims and the claim values that can successfully validated;		PASSporT claims and the claim values that can successfully validated;
	some combinations can prevent any PASSporT from being successfully		some combinations can prevent any PASSporT from being successfully
	validated by the certificate. For example, an entry in mustInclude		validated by the certificate. For example, an entry in mustInclude
	and an entry in mustExclude for the same claim will prevent		and an entry in mustExclude for the same claim will prevent
	successful validation on any PASSporT.		successful validation on any PASSporT.
	Certificate issuers should not include an entry in mustExclude for		Certificate issuers SHOULD NOT include an entry in mustExclude for
	the "rcdi" claim for a certificate that will be used with the		the "rcdi" claim for a certificate that will be used with the
	PASSporT Extension for Rich Call Data defined in		PASSporT Extension for Rich Call Data defined in
	[I-D.ietf-stir-passport-rcd]. Excluding this claim would prevent the		[I-D.ietf-stir-passport-rcd]. Excluding this claim would prevent the
	integrity protection mechanism from working properly.		integrity protection mechanism from working properly.
	Certificate issuers must take care when performing certificate		Certificate issuers must take care when performing certificate
	renewal [RFC4949] to include exactly the same Enhanced JWT Claim		renewal [RFC4949] to include exactly the same Enhanced JWT Claim
	Constraints certificate extension in the new certificate as the old		Constraints certificate extension in the new certificate as the old
	one. Renewal usually takes place before the old certificate expires,		one. Renewal usually takes place before the old certificate expires,
	so there is a period of time where both the new certificate and the		so there is a period of time where both the new certificate and the
	old certificate are valid. If different constraints appear in the		old certificate are valid. If different constraints appear in the
	two certificates with the same public key, some PASSporTs might be		two certificates with the same public key, some PASSporTs might be
	valid when one certificate is used and invalid when the other one is		valid when one certificate is used and invalid when the other one is
	used.		used.
	8. Acknowledgements		9. Acknowledgements
	Many thanks to Chris Wendt for his insight into the need for the for		Many thanks to Chris Wendt for his insight into the need for the for
	the Enhanced JWT Claim Constraints certificate extension.		the Enhanced JWT Claim Constraints certificate extension.
	Thanks to Ben Campbell and Theresa Enghardt for the thoughtful review		Thanks to Ben Campbell, Theresa Enghardt, Ben Kaduk, Erik Kline, Eric
	and comments. The document is much better as a result of the		Vyncke, and Rob Wilton for their thoughtful review and comments. The
	comments.		document is much better as a result of their efforts.
	9. References		10. References
	9.1. Normative References		10.1. Normative References
	[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>.
	[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,		[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
	Housley, R., and W. Polk, "Internet X.509 Public Key		Housley, R., and W. Polk, "Internet X.509 Public Key
	Infrastructure Certificate and Certificate Revocation List		Infrastructure Certificate and Certificate Revocation List
	(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,		(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
	skipping to change at page 9, line 19 ¶		skipping to change at page 9, line 39 ¶
	[RFC8226] Peterson, J. and S. Turner, "Secure Telephone Identity		[RFC8226] Peterson, J. and S. Turner, "Secure Telephone Identity
	Credentials: Certificates", RFC 8226,		Credentials: Certificates", RFC 8226,
	DOI 10.17487/RFC8226, February 2018,		DOI 10.17487/RFC8226, February 2018,
	<https://www.rfc-editor.org/info/rfc8226>.		<https://www.rfc-editor.org/info/rfc8226>.
	[X.680] International Telecommunication Union, "Information		[X.680] International Telecommunication Union, "Information
	Technology - Abstract Syntax Notation One (ASN.1):		Technology - Abstract Syntax Notation One (ASN.1):
	Specification of basic notation", ISO/IEC 8824-1, August		Specification of basic notation", ISO/IEC 8824-1, August
	2021.		2021.
	9.2. Informative References		10.2. Informative References
	[I-D.ietf-stir-cert-delegation]		[I-D.ietf-stir-cert-delegation]
	Peterson, J., "STIR Certificate Delegation", Work in		Peterson, J., "STIR Certificate Delegation", Work in
	Progress, Internet-Draft, draft-ietf-stir-cert-delegation-		Progress, Internet-Draft, draft-ietf-stir-cert-delegation-
	04, 22 February 2021, <https://www.ietf.org/archive/id/		04, 22 February 2021, <https://www.ietf.org/archive/id/
	draft-ietf-stir-cert-delegation-04.txt>.		draft-ietf-stir-cert-delegation-04.txt>.
	[I-D.ietf-stir-passport-rcd]		[I-D.ietf-stir-passport-rcd]
	Wendt, C. and J. Peterson, "PASSporT Extension for Rich		Wendt, C. and J. Peterson, "PASSporT Extension for Rich
	Call Data", Work in Progress, Internet-Draft, draft-ietf-		Call Data", Work in Progress, Internet-Draft, draft-ietf-
	stir-passport-rcd-11, 29 March 2021,		stir-passport-rcd-11, 29 March 2021,
	<https://www.ietf.org/archive/id/draft-ietf-stir-passport-		<https://www.ietf.org/archive/id/draft-ietf-stir-passport-
	rcd-11.txt>.		rcd-11.txt>.
			[ISO646] International Organization for Standardization,
			"Information processing - ISO 7-bit coded character set
			for information interchange", ISO/IEC 646:1991, December
			1991.
	[RFC4949] Shirey, R., "Internet Security Glossary, Version 2",		[RFC4949] Shirey, R., "Internet Security Glossary, Version 2",
	FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,		FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,
	<https://www.rfc-editor.org/info/rfc4949>.		<https://www.rfc-editor.org/info/rfc4949>.
	[RFC7468] Josefsson, S. and S. Leonard, "Textual Encodings of PKIX,		[RFC7468] Josefsson, S. and S. Leonard, "Textual Encodings of PKIX,
	PKCS, and CMS Structures", RFC 7468, DOI 10.17487/RFC7468,		PKCS, and CMS Structures", RFC 7468, DOI 10.17487/RFC7468,
	April 2015, <https://www.rfc-editor.org/info/rfc7468>.		April 2015, <https://www.rfc-editor.org/info/rfc7468>.
	Appendix A. ASN.1 Module		Appendix A. ASN.1 Module
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