< draft-ietf-stir-enhance-rfc8226-02.txt		draft-ietf-stir-enhance-rfc8226-03.txt >
	Network Working Group R. Housley		Network Working Group R. Housley
	Internet-Draft Vigil Security		Internet-Draft Vigil Security
	Updates: 8226 (if approved) 15 April 2021		Updates: 8226 (if approved) 10 June 2021
	Intended status: Standards Track		Intended status: Standards Track
	Expires: 17 October 2021		Expires: 12 December 2021
	Enhanced JWT Claim Constraints for STIR Certificates		Enhanced JWT Claim Constraints for STIR Certificates
	draft-ietf-stir-enhance-rfc8226-02		draft-ietf-stir-enhance-rfc8226-03
	Abstract		Abstract
	RFC 8226 provides a certificate extension to constrain the JWT claims		RFC 8226 specifies the use of certificates for Secure Telephone
	that can be included in the PASSporT as defined in RFC 8225. If the		Identity Credentials, and these certificates are often called "STIR
	signer includes a JWT claim outside the constraint boundaries, then		Certificates". RFC 8226 provides a certificate extension to
	the recipient will reject the entire PASSporT. This document defines		constrain the JSON Web Token (JWT) claims that can be included in the
	an additional way that the JWT claims can be constrained.		Personal Assertion Token (PASSporT) as defined in RFC 8225. If the
			PASSporT signer includes a JWT claim outside the constraint
			boundaries, then the PASSporT recipient will reject the entire
			PASSporT. This document updates RFC 8226 to define an additional way
			that the JWT claims can be constrained.
	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 17 October 2021.		This Internet-Draft will expire on 12 December 2021.
	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 . . . . . . . . . . . . . . . . . . . . . . . . . 2		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
	3. Enhanced JWT Claim Constraints Syntax . . . . . . . . . . . . 3		3. Enhanced JWT Claim Constraints Syntax . . . . . . . . . . . . 3
	4. Usage Examples . . . . . . . . . . . . . . . . . . . . . . . 4		4. Usage Examples . . . . . . . . . . . . . . . . . . . . . . . 4
	5. Certificate Extension Example . . . . . . . . . . . . . . . . 5		5. Certificate Extension Example . . . . . . . . . . . . . . . . 5
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 7		7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
	8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8		8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
	9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8		9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
	9.1. Normative References . . . . . . . . . . . . . . . . . . 8		9.1. Normative References . . . . . . . . . . . . . . . . . . 8
	9.2. Informative References . . . . . . . . . . . . . . . . . 8		9.2. Informative References . . . . . . . . . . . . . . . . . 9
	Appendix A. ASN.1 Module . . . . . . . . . . . . . . . . . . . . 9		Appendix A. ASN.1 Module . . . . . . . . . . . . . . . . . . . . 9
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 10		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].		telephone numbers is described in [RFC8226]. These certificates are
			often called "STIR Certificates". STIR certificates are an important
			element of the overall system that prevents the impersonation of
			telephone numbers on the Internet.
	Section 8 of [RFC8226] provides a certificate extension to constrain		Section 8 of [RFC8226] provides a certificate extension to constrain
	the JWT claims that can be included in the PASSporT [RFC8225]. If		the JSON Web Token (JWT) claims that can be included in the Personal
	the signer includes a JWT claim outside the constraint boundaries,		Assertion Token (PASSporT) [RFC8225]. If the PASSporT signer
	then the recipient will reject the entire PASSporT.		includes a JWT claim outside the constraint boundaries, then the
			PASSporT recipient will reject the entire PASSporT.
	This document defines an enhanced JWTClaimConstraints certificate		This document defines an enhanced JWTClaimConstraints certificate
	extension, which provides all of the capabilities available in the		extension, which provides all of the capabilities available in the
	original certificate extension as well as an additional way to		original certificate extension as well as an additional way to
	constrain the allowable JWT claims. That is, the enhanced extension		constrain the allowable JWT claims. That is, the enhanced extension
	can provide a list of claims that are not allowed to be included in		can provide a list of claims that are not allowed to be included in
	the PASSporT.		the PASSporT.
			The Enhanced JWT Claim Constraints certificate extension is needed to
			limit the authority when a parent STIR certificate delegates to a
			subordinate STIR certificate. For example,
			[I-D.ietf-stir-cert-delegation] describes the situation where service
			providers issue a STIR certificate to enterprises or other customers
			to sign PASSporTs, and the Enhanced JWT Claim Constraints certificate
			extension can be used to prevent specific claims from being included
			in PASSporTs and accepted as valid by the PASSporT recipient.
			The JWT Claim Constraints certificate extension defined in [RFC8226]
			provides a list of claims that must be included in a valid PASSporT
			as well as a list if permitted values for selected claims. The
			Enhanced JWT Claim Constraints certificate extension defined in this
			document includes those capabilities and adds a list of claims that
			must not be included in a valid PASSporT.
	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
	BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all		BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	3. Enhanced JWT Claim Constraints Syntax		3. Enhanced JWT Claim Constraints Syntax
	The Enhanced JWT Claim Constraints certificate extension limits the		The Enhanced JWT Claim Constraints certificate extension is non-
	PASSporT claims and the claim values that can successfully validated		critical, applicable only to end-entity certificates, and defined
	by the certificate that contains the extension. Certificate issuers		with ASN.1 [X.680]. The syntax of the JWT claims in a PASSporT is
	permit all claims by omitting the Enhanced JWT Claim Constraints		specified in [RFC8225].
	certificate extension from the extension field of the certificate
	[RFC5280]. The certificate extension is non-critical, applicable
	only to end-entity certificates, and defined with ASN.1 [X.680]. The
	syntax of the JWT claims in a PASSporT is specified in [RFC8225].
	The Enhanced JWT Claim Constraints certificate extension is optional,		The Enhanced JWT Claim Constraints certificate extension is optional,
	but when present, it constrains the JWT claims that authentication		but when present, it constrains the JWT claims that authentication
	services may include in the PASSporT objects they sign. Constraints		services may include in the PASSporT objects they sign. Constraints
	are applied by certificate issuers and enforced by recipients when		are applied by certificate issuers and enforced by recipients when
	validating PASSporT claims as follows:		validating PASSporT claims as follows:
	1. mustInclude indicates JWT claims that MUST appear in the PASSporT		1. mustInclude indicates JWT claims that MUST appear in the PASSporT
	in addition to the iat, orig, and dest claims. The baseline		in addition to the iat, orig, and dest claims. The baseline
	PASSporT claims ("iat", "orig", and "dest") are considered to be		PASSporT claims ("iat", "orig", and "dest") are considered to be
	skipping to change at page 4, line 36 ¶		skipping to change at page 4, line 49 ¶
	JWTClaimName ::= IA5String		JWTClaimName ::= IA5String
	4. Usage Examples		4. Usage Examples
	Consider these usage examples with a PASSporT claim called		Consider these usage examples with a PASSporT claim called
	"confidence" with values "low", "medium", and "high". These examples		"confidence" with values "low", "medium", and "high". These examples
	illustrate the constraints that are imposed by mustInclude,		illustrate the constraints that are imposed by mustInclude,
	permittedValues, and mustExclude:		permittedValues, and mustExclude:
	* If a CA issues to an authentication service certificate 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 mustInclude JWTClaimName "confidence", then an		that contains the mustInclude JWTClaimName "confidence", then an
	authentication service is required to include the "confidence"		authentication service is required to include the "confidence"
	claim in all PASSporTs it generates and signs; a verification		claim in all PASSporTs it generates and signs. A verification
	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 to an authentication service certificate 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.
	* If a CA issues to an authentication service certificate 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
	A certificate containing an example of the		A certificate containing an example of the
	EnhancedJWTClaimConstraints certificate extension is provided in		EnhancedJWTClaimConstraints certificate extension is provided in
	skipping to change at page 7, line 30 ¶		skipping to change at page 8, line 5 ¶
	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 must take care when imposing constraints on the
	PASSporT claims and the claim values that can successfully validated;
	some combinations can prevent any PASSporT from being successfully
	validated by the certificate. For example, an entry in mustInclude
	and an entry in mustExclude for the same claim will prevent
	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,
	skipping to change at page 8, line 10 ¶		skipping to change at page 8, line 26 ¶
	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		8. 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 for the thoughtful review and comments. The		Thanks to Ben Campbell and Theresa Enghardt for the thoughtful review
	document is much better as a result of the comments.		and comments. The document is much better as a result of the
			comments.
	9. References		9. References
	9.1. Normative References		9.1. 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>.
	skipping to change at page 9, line 5 ¶		skipping to change at page 9, line 21 ¶
	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		9.2. Informative References
			[I-D.ietf-stir-cert-delegation]
			Peterson, J., "STIR Certificate Delegation", Work in
			Progress, Internet-Draft, draft-ietf-stir-cert-delegation-
			04, 22 February 2021, <https://www.ietf.org/archive/id/
			draft-ietf-stir-cert-delegation-04.txt>.
	[I-D.ietf-stir-passport-rcd]		[I-D.ietf-stir-passport-rcd]
	Peterson, J. and C. Wendt, "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-09, 18 November 2020,		stir-passport-rcd-11, 29 March 2021,
	<http://www.ietf.org/internet-drafts/draft-ietf-stir-		<https://www.ietf.org/archive/id/draft-ietf-stir-passport-
	passport-rcd-09.txt>.		rcd-11.txt>.
	[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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