draft-ietf-uta-mta-sts-15.txt		draft-ietf-uta-mta-sts-16.txt
	Using TLS in Applications D. Margolis		Using TLS in Applications D. Margolis
	Internet-Draft M. Risher		Internet-Draft M. Risher
	Intended status: Standards Track Google, Inc		Intended status: Standards Track Google, Inc
	Expires: October 6, 2018 B. Ramakrishnan		Expires: November 3, 2018 B. Ramakrishnan
	Yahoo!, Inc		Yahoo!, Inc
	A. Brotman		A. Brotman
	Comcast, Inc		Comcast, Inc
	J. Jones		J. Jones
	Microsoft, Inc		Microsoft, Inc
	April 4, 2018		May 2, 2018
	SMTP MTA Strict Transport Security (MTA-STS)		SMTP MTA Strict Transport Security (MTA-STS)
	draft-ietf-uta-mta-sts-15		draft-ietf-uta-mta-sts-16
	Abstract		Abstract
	SMTP Mail Transfer Agent Strict Transport Security (MTA-STS) is a		SMTP Mail Transfer Agent Strict Transport Security (MTA-STS) is a
	mechanism enabling mail service providers to declare their ability to		mechanism enabling mail service providers to declare their ability to
	receive Transport Layer Security (TLS) secure SMTP connections, and		receive Transport Layer Security (TLS) secure SMTP connections, and
	to specify whether sending SMTP servers should refuse to deliver to		to specify whether sending SMTP servers should refuse to deliver to
	MX hosts that do not offer TLS with a trusted server certificate.		MX hosts that do not offer TLS with a trusted server certificate.
	Status of This Memo		Status of This Memo
	skipping to change at page 1, line 40 ¶		skipping to change at page 1, line 40 ¶
	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 October 6, 2018.		This Internet-Draft will expire on November 3, 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
	(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
	skipping to change at page 3, line 30 ¶		skipping to change at page 3, line 30 ¶
	o whether MTAs sending mail to this domain can expect PKIX-		o whether MTAs sending mail to this domain can expect PKIX-
	authenticated TLS support		authenticated TLS support
	o what a conforming client should do with messages when TLS cannot		o what a conforming client should do with messages when TLS cannot
	be successfully negotiated		be successfully negotiated
	1.1. Terminology		1.1. 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", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	document are to be interpreted as described in [RFC2119]. These		"OPTIONAL" in this document are to be interpreted as described in
	words may also appear in this document in lowercase, absent their		[BCP 14] [RFC2119] [RFC8174] when, and only when, they appear in all
	normative meanings.		capitals, as shown here.
	We also define the following terms for further use in this document:		We also define the following terms for further use in this document:
	o MTA-STS Policy: A commitment by the Policy Domain to support PKIX		o MTA-STS Policy: A commitment by the Policy Domain to support PKIX
	[RFC5280] authenticated TLS for the specified MX hosts.		[RFC5280] authenticated TLS for the specified MX hosts.
	o Policy Domain: The domain for which an MTA-STS Policy is defined.		o Policy Domain: The domain for which an MTA-STS Policy is defined.
	This is the next-hop domain; when sending mail to		This is the next-hop domain; when sending mail to
	"alice@example.com" this would ordinarily be "example.com", but		"alice@example.com" this would ordinarily be "example.com", but
	this may be overridden by explicit routing rules (as described in		this may be overridden by explicit routing rules (as described in
	skipping to change at page 7, line 36 ¶		skipping to change at page 7, line 36 ¶
	sts-policy-version-field = %s"version"		sts-policy-version-field = %s"version"
	sts-policy-version-value = %s"STSv1"		sts-policy-version-value = %s"STSv1"
	sts-policy-mode = sts-policy-mode-field field-delim		sts-policy-mode = sts-policy-mode-field field-delim
	sts-policy-mode-value		sts-policy-mode-value
	sts-policy-mode-field = %s"mode"		sts-policy-mode-field = %s"mode"
	sts-policy-model-value = %s"testing" / %s"enforce" / %s"none"		sts-policy-mode-value = %s"testing" / %s"enforce" / %s"none"
	sts-policy-mx = sts-policy-mx-field field-delim		sts-policy-mx = sts-policy-mx-field field-delim
	sts-policy-mx-value		sts-policy-mx-value
	sts-policy-mx-field = %s"mx"		sts-policy-mx-field = %s"mx"
	sts-policy-mx-value = 1*(ALPHA / DIGIT / "_" / "-" / ".")		sts-policy-mx-value = 1*(ALPHA / DIGIT / "_" / "-" / ".")
	sts-policy-max-age = sts-policy-max-age-field field-delim		sts-policy-max-age = sts-policy-max-age-field field-delim
	sts-policy-max-age-value		sts-policy-max-age-value
	skipping to change at page 8, line 11 ¶		skipping to change at page 8, line 11 ¶
	sts-policy-max-age-value = 1*10(DIGIT)		sts-policy-max-age-value = 1*10(DIGIT)
	sts-policy-extension = sts-policy-ext-name ; additional		sts-policy-extension = sts-policy-ext-name ; additional
	field-delim ; extension		field-delim ; extension
	sts-policy-ext-value ; fields		sts-policy-ext-value ; fields
	sts-policy-ext-name = (ALPHA / DIGIT)		sts-policy-ext-name = (ALPHA / DIGIT)
	*31(ALPHA / DIGIT / "_" / "-" / ".")		*31(ALPHA / DIGIT / "_" / "-" / ".")
	sts-policy-ext-value = 1*(%x21-3A / %x3C / %x3E-7E)		sts-policy-ext-value = 1*(%x21-3A / %x3C / %x3E-7E)
	; chars, excluding "=", ";", SP, and		; chars, excluding control chars
	; control chars
	Parsers MUST accept TXT records and policy files which are		Parsers MUST accept TXT records and policy files which are
	syntactically valid (i.e. valid key/value pairs separated by semi-		syntactically valid (i.e. valid key/value pairs separated by semi-
	colons for TXT records) and but containing additional key/value pairs		colons for TXT records) and but containing additional key/value pairs
	not specified in this document, in which case unknown fields SHALL be		not specified in this document, in which case unknown fields SHALL be
	ignored. If any non-repeated field--i.e. all fields excepting "mx"--		ignored. If any non-repeated field--i.e. all fields excepting "mx"--
	is duplicated, all entries except for the first SHALL be ignored. If		is duplicated, all entries except for the first SHALL be ignored. If
	any field is not specified, the policy SHALL be treated as invalid.		any field is not specified, the policy SHALL be treated as invalid.
	3.3. HTTPS Policy Fetching		3.3. HTTPS Policy Fetching
	skipping to change at page 19, line 7 ¶		skipping to change at page 19, line 7 ¶
	One approach commonly employed by Web browsers to help mitigate		One approach commonly employed by Web browsers to help mitigate
	against some of these attacks is to allow for revocation of		against some of these attacks is to allow for revocation of
	compromised or fraudulent certificates via OCSP [RFC6960] or CRLs		compromised or fraudulent certificates via OCSP [RFC6960] or CRLs
	[RFC6818]. Such mechanisms themselves represent tradeoffs and are		[RFC6818]. Such mechanisms themselves represent tradeoffs and are
	not universally implemented; we nonetheless recommend implementors of		not universally implemented; we nonetheless recommend implementors of
	MTA-STS to implement revocation mechanisms which are most applicable		MTA-STS to implement revocation mechanisms which are most applicable
	to their implementations.		to their implementations.
	11. Contributors		11. Contributors
	Nicolas Lidzborski Google, Inc nlidz (at) google (dot com)
	Wei Chuang Google, Inc weihaw (at) google (dot com)		Wei Chuang Google, Inc weihaw (at) google (dot com)
			Viktor Dukhovni ietf-dane (at) dukhovni (dot org)
			Markus Laber 1&1 Mail & Media Development & Technology GmbH
			markus.laber (at) 1und1 (dot de)
			Nicolas Lidzborski Google, Inc nlidz (at) google (dot com)
	Brandon Long Google, Inc blong (at) google (dot com)		Brandon Long Google, Inc blong (at) google (dot com)
	Franck Martin LinkedIn, Inc fmartin (at) linkedin (dot com)		Franck Martin LinkedIn, Inc fmartin (at) linkedin (dot com)
	Klaus Umbach 1&1 Mail & Media Development & Technology GmbH		Klaus Umbach 1&1 Mail & Media Development & Technology GmbH
	klaus.umbach (at) 1und1 (dot de)		klaus.umbach (at) 1und1 (dot de)
	Markus Laber 1&1 Mail & Media Development & Technology GmbH
	markus.laber (at) 1und1 (dot de)
	12. References		12. References
	12.1. Normative References		12.1. Normative References
	[I-D.ietf-uta-smtp-tlsrpt]		[I-D.ietf-uta-smtp-tlsrpt]
	Margolis, D., Brotman, A., Ramakrishnan, B., Jones, J.,		Margolis, D., Brotman, A., Ramakrishnan, B., Jones, J.,
	and M. Risher, "SMTP TLS Reporting", draft-ietf-uta-smtp-		and M. Risher, "SMTP TLS Reporting", draft-ietf-uta-smtp-
	tlsrpt-17 (work in progress), March 2018.		tlsrpt-18 (work in progress), April 2018.
			[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
			Requirement Levels", BCP 14, RFC 2119,
			DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
			editor.org/info/rfc2119>.
	[RFC3207] Hoffman, P., "SMTP Service Extension for Secure SMTP over		[RFC3207] Hoffman, P., "SMTP Service Extension for Secure SMTP over
	Transport Layer Security", RFC 3207, DOI 10.17487/RFC3207,		Transport Layer Security", RFC 3207, DOI 10.17487/RFC3207,
	February 2002, <https://www.rfc-editor.org/info/rfc3207>.		February 2002, <https://www.rfc-editor.org/info/rfc3207>.
	[RFC3492] Costello, A., "Punycode: A Bootstring encoding of Unicode		[RFC3492] Costello, A., "Punycode: A Bootstring encoding of Unicode
	for Internationalized Domain Names in Applications		for Internationalized Domain Names in Applications
	(IDNA)", RFC 3492, DOI 10.17487/RFC3492, March 2003,		(IDNA)", RFC 3492, DOI 10.17487/RFC3492, March 2003,
	<https://www.rfc-editor.org/info/rfc3492>.		<https://www.rfc-editor.org/info/rfc3492>.
	skipping to change at page 20, line 32 ¶		skipping to change at page 20, line 42 ¶
	[RFC7405] Kyzivat, P., "Case-Sensitive String Support in ABNF",		[RFC7405] Kyzivat, P., "Case-Sensitive String Support in ABNF",
	RFC 7405, DOI 10.17487/RFC7405, December 2014,		RFC 7405, DOI 10.17487/RFC7405, December 2014,
	<https://www.rfc-editor.org/info/rfc7405>.		<https://www.rfc-editor.org/info/rfc7405>.
	[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,		[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
	"Recommendations for Secure Use of Transport Layer		"Recommendations for Secure Use of Transport Layer
	Security (TLS) and Datagram Transport Layer Security		Security (TLS) and Datagram Transport Layer Security
	(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May		(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
	2015, <https://www.rfc-editor.org/info/rfc7525>.		2015, <https://www.rfc-editor.org/info/rfc7525>.
	12.2. Informative References		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
			2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
			May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		12.2. Informative References
	Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
	editor.org/info/rfc2119>.
	[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.		[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
	Rose, "DNS Security Introduction and Requirements",		Rose, "DNS Security Introduction and Requirements",
	RFC 4033, DOI 10.17487/RFC4033, March 2005,		RFC 4033, DOI 10.17487/RFC4033, March 2005,
	<https://www.rfc-editor.org/info/rfc4033>.		<https://www.rfc-editor.org/info/rfc4033>.
	[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322,		[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322,
	DOI 10.17487/RFC5322, October 2008, <https://www.rfc-		DOI 10.17487/RFC5322, October 2008, <https://www.rfc-
	editor.org/info/rfc5322>.		editor.org/info/rfc5322>.
End of changes. 13 change blocks.
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