draft-ietf-uta-smtp-tlsrpt-05.txt		draft-ietf-uta-smtp-tlsrpt-06.txt
	Using TLS in Applications D. Margolis		Using TLS in Applications D. Margolis
	Internet-Draft Google, Inc		Internet-Draft Google, Inc
	Intended status: Standards Track A. Brotman		Intended status: Standards Track A. Brotman
	Expires: November 4, 2017 Comcast, Inc		Expires: December 01, 2017 Comcast, Inc
	B. Ramakrishnan		B. Ramakrishnan
	Yahoo!, Inc		Yahoo!, Inc
	J. Jones		J. Jones
	Microsoft, Inc		Microsoft, Inc
	M. Risher		M. Risher
	Google, Inc		Google, Inc
	May 3, 2017		May 31, 2017
	SMTP TLS Reporting		SMTP TLS Reporting
	draft-ietf-uta-smtp-tlsrpt-05		draft-ietf-uta-smtp-tlsrpt-06
	Abstract		Abstract
	A number of protocols exist for establishing encrypted channels		A number of protocols exist for establishing encrypted channels
	between SMTP Mail Transfer Agents, including STARTTLS [RFC3207], DANE		between SMTP Mail Transfer Agents, including STARTTLS [RFC3207], DANE
	[RFC6698], and MTA-STS (TODO: Add ref). These protocols can fail due		[RFC6698], and MTA-STS (TODO: Add ref). These protocols can fail due
	to misconfiguration or active attack, leading to undelivered messages		to misconfiguration or active attack, leading to undelivered messages
	or delivery over unencrypted or unauthenticated channels. This		or delivery over unencrypted or unauthenticated channels. This
	document describes a reporting mechanism and format by which sending		document describes a reporting mechanism and format by which sending
	systems can share statistics and specific information about potential		systems can share statistics and specific information about potential
	skipping to change at page 1, line 46 ¶		skipping to change at page 1, line 46 ¶
	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 4, 2017.		This Internet-Draft will expire on November 26, 2017.
	Copyright Notice		Copyright Notice
	Copyright (c) 2017 IETF Trust and the persons identified as the		Copyright (c) 2017 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 2, line 27 ¶		skipping to change at page 2, line 27 ¶
	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 . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
	1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3		1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Related Technologies . . . . . . . . . . . . . . . . . . . . 4		2. Related Technologies . . . . . . . . . . . . . . . . . . . . 4
	3. Reporting Policy . . . . . . . . . . . . . . . . . . . . . . 4		3. Reporting Policy . . . . . . . . . . . . . . . . . . . . . . 4
	3.1. Example Reporting Policy . . . . . . . . . . . . . . . . 5		3.1. Example Reporting Policy . . . . . . . . . . . . . . . . 5
	3.1.1. Report using MAILTO . . . . . . . . . . . . . . . . . 5		3.1.1. Report using MAILTO . . . . . . . . . . . . . . . . . 6
	3.1.2. Report using HTTPS . . . . . . . . . . . . . . . . . 6		3.1.2. Report using HTTPS . . . . . . . . . . . . . . . . . 6
	4. Reporting Schema . . . . . . . . . . . . . . . . . . . . . . 6		4. Reporting Schema . . . . . . . . . . . . . . . . . . . . . . 6
	4.1. Report Time-frame . . . . . . . . . . . . . . . . . . . . 7		4.1. Report Time-frame . . . . . . . . . . . . . . . . . . . . 7
	4.2. Delivery Summary . . . . . . . . . . . . . . . . . . . . 7		4.2. Delivery Summary . . . . . . . . . . . . . . . . . . . . 7
	4.2.1. Success Count . . . . . . . . . . . . . . . . . . . . 7		4.2.1. Success Count . . . . . . . . . . . . . . . . . . . . 7
	4.2.2. Failure Count . . . . . . . . . . . . . . . . . . . . 7		4.2.2. Failure Count . . . . . . . . . . . . . . . . . . . . 7
	4.3. Result Types . . . . . . . . . . . . . . . . . . . . . . 7		4.3. Result Types . . . . . . . . . . . . . . . . . . . . . . 7
	4.3.1. Negotiation Failures . . . . . . . . . . . . . . . . 7		4.3.1. Negotiation Failures . . . . . . . . . . . . . . . . 7
	4.3.2. Policy Failures . . . . . . . . . . . . . . . . . . . 8		4.3.2. Policy Failures . . . . . . . . . . . . . . . . . . . 8
	4.3.3. General Failures . . . . . . . . . . . . . . . . . . 8		4.3.3. General Failures . . . . . . . . . . . . . . . . . . 8
	4.3.4. Transient Failures . . . . . . . . . . . . . . . . . 8		4.3.4. Transient Failures . . . . . . . . . . . . . . . . . 9
	5. Report Delivery . . . . . . . . . . . . . . . . . . . . . . . 9		4.4. JSON Report Schema . . . . . . . . . . . . . . . . . . . 9
	5.1. Report Filename . . . . . . . . . . . . . . . . . . . . . 9		5. Report Delivery . . . . . . . . . . . . . . . . . . . . . . . 11
	5.2. Compression . . . . . . . . . . . . . . . . . . . . . . . 9		5.1. Report Filename . . . . . . . . . . . . . . . . . . . . . 11
	5.3. Email Transport . . . . . . . . . . . . . . . . . . . . . 10		5.2. Compression . . . . . . . . . . . . . . . . . . . . . . . 12
	5.4. HTTPS Transport . . . . . . . . . . . . . . . . . . . . . 10		5.3. Email Transport . . . . . . . . . . . . . . . . . . . . . 12
	5.5. Delivery Retry . . . . . . . . . . . . . . . . . . . . . 11		5.3.1. Example Report . . . . . . . . . . . . . . . . . . . 13
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11		5.4. HTTPS Transport . . . . . . . . . . . . . . . . . . . . . 14
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 11		5.5. Delivery Retry . . . . . . . . . . . . . . . . . . . . . 14
	8. Appendix 1: Example Reporting Policy . . . . . . . . . . . . 12		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
	8.1. Report using MAILTO . . . . . . . . . . . . . . . . . . . 12		6.1. Message headers . . . . . . . . . . . . . . . . . . . . . 15
	8.2. Report using HTTPS . . . . . . . . . . . . . . . . . . . 12		6.2. Report Type . . . . . . . . . . . . . . . . . . . . . . . 15
	9. Appendix 2: JSON Report Schema . . . . . . . . . . . . . . . 12		6.3. application/tlsrpt+* Media Types . . . . . . . . . . . . 15
	10. Appendix 3: Example JSON Report . . . . . . . . . . . . . . . 15		6.4. STARTTLS Validation Result Types . . . . . . . . . . . . 16
	11. Normative References . . . . . . . . . . . . . . . . . . . . 16		7. Security Considerations . . . . . . . . . . . . . . . . . . . 17
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17		8. Appendix 1: Example Reporting Policy . . . . . . . . . . . . 18
			8.1. Report using MAILTO . . . . . . . . . . . . . . . . . . . 18
			8.2. Report using HTTPS . . . . . . . . . . . . . . . . . . . 18
			9. Appendix 2: Example JSON Report . . . . . . . . . . . . . . . 18
			10. Normative References . . . . . . . . . . . . . . . . . . . . 20
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
	1. Introduction		1. Introduction
	The STARTTLS extension to SMTP [RFC3207] allows SMTP clients and		The STARTTLS extension to SMTP [RFC3207] allows SMTP clients and
	hosts to establish secure SMTP sessions over TLS. The protocol		hosts to establish secure SMTP sessions over TLS. The protocol
	design is based on "Opportunistic Security" (OS) [RFC7435], which		design is based on "Opportunistic Security" (OS) [RFC7435], which
	maintains interoperability with clients that do not support STARTTLS		maintains interoperability with clients that do not support STARTTLS
	but means that any attacker who can delete parts of the SMTP session		but means that any attacker who can delete parts of the SMTP session
	(such as the "250 STARTTLS" response) or redirect the entire SMTP		(such as the "250 STARTTLS" response) or redirect the entire SMTP
	session (perhaps by overwriting the resolved MX record of the		session (perhaps by overwriting the resolved MX record of the
	skipping to change at page 4, line 20 ¶		skipping to change at page 4, line 22 ¶
	MTAs should deliver reports.		MTAs should deliver reports.
	o Policy Domain: The domain against which an MTA-STS or DANE Policy		o Policy Domain: The domain against which an MTA-STS or DANE Policy
	is defined.		is defined.
	o Sending MTA: The MTA initiating the delivery of an email message.		o Sending MTA: The MTA initiating the delivery of an email message.
	2. Related Technologies		2. Related Technologies
	o This document is intended as a companion to the specification for		o This document is intended as a companion to the specification for
	SMTP MTA Strict Transport Security (MTA-STS, TODO: Add ref).		SMTP MTA Strict Transport Security (MTA-STS, TODO: Add RFC ref).
	o SMTP-TLSRPT defines a mechanism for sending domains that are		o SMTP-TLSRPT defines a mechanism for sending domains that are
	compatible with MTA-STS or DANE to share success and failure		compatible with MTA-STS or DANE to share success and failure
	statistics with recipient domains. DANE is defined in [RFC6698]		statistics with recipient domains. DANE is defined in [RFC6698]
	and MTA-STS is defined in [TODO]		and MTA-STS is defined in [TODO : Add RFC ref]
	3. Reporting Policy		3. Reporting Policy
	A domain publishes a record to its DNS indicating that it wishes to		A domain publishes a record to its DNS indicating that it wishes to
	receive reports. These SMTP TLSRPT policies are distributed via DNS		receive reports. These SMTP TLSRPT policies are distributed via DNS
	from the Policy Domain's zone, as TXT records (similar to DMARC		from the Policy Domain's zone, as TXT records (similar to DMARC
	policies) under the name "_smtp-tlsrpt". For example, for the Policy		policies) under the name "_smtp-tlsrpt". For example, for the Policy
	Domain "example.com", the recipient's TLSRPT policy can be retrieved		Domain "example.com", the recipient's TLSRPT policy can be retrieved
	from "_smtp-tlsrpt.example.com".		from "_smtp-tlsrpt.example.com".
	skipping to change at page 8, line 26 ¶		skipping to change at page 8, line 31 ¶
	o "tlsa-invalid": This indicates a validation error in the TLSA		o "tlsa-invalid": This indicates a validation error in the TLSA
	record associated with a DANE policy. None of the records in the		record associated with a DANE policy. None of the records in the
	RRset were found to be valid.		RRset were found to be valid.
	o "dnssec-invalid": This would indicate that no valid records were		o "dnssec-invalid": This would indicate that no valid records were
	returned from the recursive resolver. The request returned with		returned from the recursive resolver. The request returned with
	SERVFAIL for the requested TLSA record.		SERVFAIL for the requested TLSA record.
	4.3.2.2. MTA-STS-specific Policy Failures		4.3.2.2. MTA-STS-specific Policy Failures
	o "sts-invalid": This indicates a validation error for the overall		o "sts-policy-invalid": This indicates a validation error for the
	MTA-STS policy.		overall MTA-STS policy.
	o "webpki-invalid": This indicates that the MTA-STS policy could not		o "sts-webpki-invalid": This indicates that the MTA-STS policy could
	be authenticated using PKIX validation.		not be authenticated using PKIX validation.
	4.3.3. General Failures		4.3.3. General Failures
	When a negotiation failure can not be categorized into one of the		When a negotiation failure can not be categorized into one of the
	"Negotiation Failures" stated above, the reporter SHOULD use the		"Negotiation Failures" stated above, the reporter SHOULD use the
	"validation-failure" category. As TLS grows and becomes more		"validation-failure" category. As TLS grows and becomes more
	complex, new mechanisms may not be easily categorized. This allows		complex, new mechanisms may not be easily categorized. This allows
	for a generic feedback category. When this category is used, the		for a generic feedback category. When this category is used, the
	reporter SHOULD also use the "failure-reason-code" to give some		reporter SHOULD also use the "failure-reason-code" to give some
	feedback to the receiving entity. This is intended to be a short		feedback to the receiving entity. This is intended to be a short
	text field, and the contents of the field should be an error code or		text field, and the contents of the field should be an error code or
	error text, such as "X509_V_ERR_UNHANDLED_CRITICAL_CRL_EXTENSION".		error text, such as "X509_V_ERR_UNHANDLED_CRITICAL_CRL_EXTENSION".
	4.3.4. Transient Failures		4.3.4. Transient Failures
	Transient errors due to too-busy network, TCP timeouts, etc. are not		Transient errors due to too-busy network, TCP timeouts, etc. are not
	required to be reported.		required to be reported.
			4.4. JSON Report Schema
			The JSON schema is derived from the HPKP JSON schema [RFC7469] (cf.
			Section 3)
			{
			"organization-name": organization-name,
			"date-range": {
			"start-datetime": date-time,
			"end-datetime": date-time
			},
			"contact-info": email-address,
			"report-id": report-id,
			"policy": {
			"policy-type": policy-type,
			"policy-string": policy-string,
			"policy-domain": domain,
			"mx-host": mx-host-pattern
			},
			"summary": {
			"success-aggregate": total-successful-session-count,
			"failure-aggregate:" total-failure-session-count
			}
			"failure-details": [
			{
			"result-type": result-type,
			"sending-mta-ip": ip-address,
			"receiving-mx-hostname": receiving-mx-hostname,
			"receiving-mx-helo": receiving-mx-helo,
			"session-count": failed-session-count,
			"additional-information": additional-info-uri,
			"failure-reason-code": "Text body"
			}
			]
			}
			JSON Report Format
			o "organization-name": The name of the organization responsible for
			the report. It is provided as a string.
			o "date-time": The date-time indicates the start- and end-times for
			the report range. It is provided as a string formatted according
			to Section 5.6, "Internet Date/Time Format", of [RFC3339]. The
			report should be for a full UTC day, 0000-2400.
			o "email-address": The contact information for a responsible party
			of the report. It is provided as a string formatted according to
			Section 3.4.1, "Addr-Spec", of [RFC5322].
			o "report-id": A unique identifier for the report. Report authors
			may use whatever scheme they prefer to generate a unique
			identifier. It is provided as a string.
			o "policy-type": The type of policy that was applied by the sending
			domain. Presently, the only three valid choices are "tlsa",
			"sts", and the literal string "no-policy-found". It is provided
			as a string.
			o "policy-string": The JSON string serialization ([RFC7159] section
			7) of the policy, whether TLSA record ([RFC6698] section 2.3) or
			MTA-STS policy.
			o "domain": The Policy Domain is the domain against which the MTA-
			STS or DANE policy is defined.
			o "mx-host-pattern": The pattern of MX hostnames from the applied
			policy. It is provided as a string, and is interpreted in the
			same manner as the "Checking of Wildcard Certificates" rules in
			Section 6.4.3 of [RFC6125].
			o "result-type": A value from Section 4.3, "Result Types", above.
			o "ip-address": The IP address of the sending MTA that attempted the
			STARTTLS connection. It is provided as a string representation of
			an IPv4 or IPv6 address in dot-decimal or colon-hexadecimal
			notation.
			o "receiving-mx-hostname": The hostname of the receiving MTA MX
			record with which the sending MTA attempted to negotiate a
			STARTTLS connection.
			o "receiving-mx-helo": (optional) The HELO or EHLO string from the
			banner announced during the reported session.
			o "success-aggregate": The aggregate number (integer) of
			successfully negotiated TLS-enabled connections to the receiving
			site.
			o "failure-aggregate": The aggregate number (integer) of failures to
			negotiate an TLS-enabled connection to the receiving site.
			o "session-count": The number of (attempted) sessions that match the
			relevant "result-type" for this section.
			o "additional-info-uri": An optional URI pointing to additional
			information around the relevant "result-type". For example, this
			URI might host the complete certificate chain presented during an
			attempted STARTTLS session.
			o "failure-reason-code": A text field to include an TLS-related
			error code or error message.
	5. Report Delivery		5. Report Delivery
	Reports can be delivered either as an email message via SMTP or via		Reports can be delivered either as an email message via SMTP or via
	HTTP POST.		HTTP POST.
	5.1. Report Filename		5.1. Report Filename
	The filename is typically constructed using the following ABNF:		The filename is typically constructed using the following ABNF:
	filename = sender "!" policy-domain "!" begin-timestamp		filename = sender "!" policy-domain "!" begin-timestamp
	skipping to change at page 10, line 7 ¶		skipping to change at page 12, line 19 ¶
	5.2. Compression		5.2. Compression
	The report SHOULD be subjected to GZIP compression for both email and		The report SHOULD be subjected to GZIP compression for both email and
	HTTPS transport. Declining to apply compression can cause the report		HTTPS transport. Declining to apply compression can cause the report
	to be too large for a receiver to process (a commonly observed		to be too large for a receiver to process (a commonly observed
	receiver limit is ten megabytes); compressing the file increases the		receiver limit is ten megabytes); compressing the file increases the
	chances of acceptance of the report at some compute cost.		chances of acceptance of the report at some compute cost.
	5.3. Email Transport		5.3. Email Transport
	The report MAY be delivered by email. No specific MIME message		The report MAY be delivered by email. To make the reports machine-
	structure is required. It is presumed that the aggregate reporting		parsable for the receivers, we define a top-level media type
	address will be equipped to extract MIME parts with the prescribed		"multipart/report" with a new parameter "report-type="tlsrpt"".
	media type and filename and ignore the rest.		Inside it, there are two parts: The first part is human readable,
			typically "text/plain", and the second part is machine readable with
			a new media type defined called "application/tlsrpt+json". If
			compressed, the report should use the media type "application/
			tlsrpt+gzip".
	If compressed, the report should use the media type "application/		In addition, the following two new top level message header fields
	gzip" if compressed (see [RFC6713]), and "application/json"		are defined:
	otherwise.
			TLS-Report-Domain: Receiver-Domain
			TLS-Report-Submitter: Sender-Domain
			These message headers would allow for easy searching for all reports
			submitted by a report domain or a particular submitter, for example
			in IMAP:
			"s SEARCH HEADER "TLS-Report-Domain" "example.com""
			It is presumed that the aggregate reporting address will be equipped
			to process new message header fields and extract MIME parts with the
			prescribed media type and filename, and ignore the rest.
	The [RFC5322].Subject field for individual report submissions SHOULD		The [RFC5322].Subject field for individual report submissions SHOULD
	conform to the following ABNF:		conform to the following ABNF:
	tlsrpt-subject = %x52.65.70.6f.72.74 1*FWS ; "Report"		tlsrpt-subject = %x52.65.70.6f.72.74 1*FWS ; "Report"
	%x44.6f.6d.61.69.6e.3a 1*FWS ; "Domain:"		%x44.6f.6d.61.69.6e.3a 1*FWS ; "Domain:"
	domain-name 1*FWS ; from RFC 6376		domain-name 1*FWS ; from RFC 6376
	%x53.75.62.6d.69.74.74.65.72.3a ; "Submitter:"		%x53.75.62.6d.69.74.74.65.72.3a ; "Submitter:"
	1*FWS domain-name 1*FWS		1*FWS domain-name 1*FWS
	%x52.65.70.6f.72.74.2d.49.44.3a ; "Report-ID:"		%x52.65.70.6f.72.74.2d.49.44.3a ; "Report-ID:"
	skipping to change at page 10, line 43 ¶		skipping to change at page 13, line 29 ¶
	For instance, this is a possible Subject field for a report to the		For instance, this is a possible Subject field for a report to the
	Policy Domain "example.net" from the Sending MTA		Policy Domain "example.net" from the Sending MTA
	"mail.sender.example.com". It is line-wrapped as allowed by		"mail.sender.example.com". It is line-wrapped as allowed by
	[RFC5322]:		[RFC5322]:
	Subject: Report Domain: example.net		Subject: Report Domain: example.net
	Submitter: mail.sender.example.com		Submitter: mail.sender.example.com
	Report-ID: <735ff.e317+bf22029@mailexample.net>		Report-ID: <735ff.e317+bf22029@mailexample.net>
			5.3.1. Example Report
			From: tlsrpt@mail.sender.example.com
			Date: Fri, May 09 2017 16:54:30 -0800
			To: mts-sts-tlsrpt@example.net
			Subject: Report Domain: example.net
			Submitter: mail.sender.example.com
			Report-ID: <735ff.e317+bf22029@example.net>
			TLS-Report-Domain: example.net
			TLS-Report-Submitter: mail.sender.example.com
			MIME-Version: 1.0
			Content-Type: multipart/report; report-type="tlsrpt";
			boundary="----=_NextPart_000_024E_01CC9B0A.AFE54C00"
			Content-Language: en-us
			This is a multipart message in MIME format.
			------=_NextPart_000_024E_01CC9B0A.AFE54C00
			Content-Type: text/plain; charset="us-ascii"
			Content-Transfer-Encoding: 7bit
			This is an aggregate TLS report from mail.sender.example.com
			------=_NextPart_000_024E_01CC9B0A.AFE54C00
			Content-Type: application/tlsrpt+gzip
			Content-Transfer-Encoding: base64
			Content-Disposition: attachment;
			filename="mail.sender.example!example.com!
			1013662812!1013749130.gz"
			<gzipped content of report>
			------=_NextPart_000_024E_01CC9B0A.AFE54C00--
			...
	Note that, when sending failure reports via SMTP, sending MTAs MUST		Note that, when sending failure reports via SMTP, sending MTAs MUST
	NOT honor MTA-STS or DANE TLSA failures.		NOT honor MTA-STS or DANE TLSA failures.
	5.4. HTTPS Transport		5.4. HTTPS Transport
	The report MAY be delivered by POST to HTTPS. If compressed, the		The report MAY be delivered by POST to HTTPS. If compressed, the
	report should use the media type "application/gzip" (see [RFC6713]),		report should use the media type "application/tlsrpt+gzip", and
	and "application/json" otherwise.		"application/tlsrpt+json" otherwise (see section Section 6, "IANA
			Considerations").
	5.5. Delivery Retry		5.5. Delivery Retry
	In the event of a delivery failure, regardless of the delivery		In the event of a delivery failure, regardless of the delivery
	method, a sender SHOULD attempt redelivery for up to 24hrs after the		method, a sender SHOULD attempt redelivery for up to 24hrs after the
	initial attempt. As previously stated the reports are optional, so		initial attempt. As previously stated the reports are optional, so
	while it is ideal to attempt redelivery, it is not required. If		while it is ideal to attempt redelivery, it is not required. If
	multiple retries are attempted, they should be on a logarithmic		multiple retries are attempted, they should be on a logarithmic
	scale.		scale.
	6. IANA Considerations		6. IANA Considerations
	There are no IANA considerations at this time.		The following are the IANA considerations discussed in this document.
			6.1. Message headers
			Below is the Internet Assigned Numbers Authority (IANA) Permanent
			Message Header Field registration information per [RFC3864].
			Header field name: TLS-Report-Domain
			Applicable protocol: smtp
			Status: standard
			Author/Change controller: IETF
			Specification document(s): this one
			Header field name: TLS-Report-Submitter
			Applicable protocol: smtp
			Status: standard
			Author/Change controller: IETF
			Specification document(s): this one
			6.2. Report Type
			This document registers a new parameter "report-type="tlsrpt"" under
			"multipart/report" top-level media type for use with [RFC6522].
			The media type suitable for use as a report-type is defined in the
			following section.
			6.3. application/tlsrpt+* Media Types
			This document registers multiple media types, listed in Table 1
			below.
			+-------------+----------------+-------------+-------------------+
			| Type | Subtype | File extn | Specification |
			+-------------+----------------+-------------+-------------------+
			| application | tlsrpt+json | .json | Section 5.3 |
			| application | tlsrpt+gzip | .gz | Section 5.3 |
			+-------------+----------------+-------------+-------------------+
			Table 1: SMTP TLS Reporting Media Types
			Type name: application
			Subtype name: This documents registers multiple subtypes, as listed
			in Table 1.
			Required parameters: n/a
			Optional parameters: n/a
			Encoding considerations: Encoding considerations are identical to
			those specified for the "application/json" media type. See
			[RFC7159].
			Security considerations: Security considerations relating to SMTP TLS
			Reporting are discussed in Section 7.
			Interoperability considerations: This document specifies format of
			conforming messages and the interpretation thereof.
			Published specification: This document is the specification for these
			media types; see Table 1 for the section documenting each media type.
			Applications that use this media type: Mail User Agents (MUA) and
			Mail Transfer Agents.
			Additional information:
			Magic number(s): n/a
			File extension(s): As listed in Table 1.
			Macintosh file type code(s): n/a
			Person & email address to contact for further information: See
			Authors' Addresses section.
			Intended usage: COMMON
			Restrictions on usage: n/a
			Author: See Authors' Addresses section.
			Change controller: Internet Engineering Task Force
			(mailto:iesg@ietf.org).
			6.4. STARTTLS Validation Result Types
			This document creates a new registry, "STARTTLS Validation Result
			Types". The initial entries in the registry are:
			+-------------------------------+
			| Result Type |
			+-------------------------------+
			| "starttls-not-supported" |
			| "certificate-host-mismatch" |
			| "certificate-expired" |
			| "tlsa-invalid" |
			| "dnssec-invalid" |
			| "sts-policy-invalid" |
			| "sts-webpki-invalid" |
			| "validation-failure" |
			+-------------------------------+
			The above entries are described in section Section 4.3, "Result
			Types." New result types can be added to this registry without the
			need to update this document.
	7. Security Considerations		7. Security Considerations
	SMTP TLS Reporting provides transparency into misconfigurations or		SMTP TLS Reporting provides transparency into misconfigurations or
	attempts to intercept or tamper with mail between hosts who support		attempts to intercept or tamper with mail between hosts who support
	STARTTLS. There are several security risks presented by the		STARTTLS. There are several security risks presented by the
	existence of this reporting channel:		existence of this reporting channel:
	o Flooding of the Aggregate report URI (rua) endpoint: An attacker		o Flooding of the Aggregate report URI (rua) endpoint: An attacker
	could flood the endpoint and prevent the receiving domain from		could flood the endpoint with excessive reporting traffic and
	accepting additional reports. This type of Denial-of-Service		prevent the receiving domain from accepting additional reports.
	attack would limit visibility into STARTTLS failures, leaving the		This type of Denial-of-Service attack would limit visibility into
	receiving domain blind to an ongoing attack.		STARTTLS failures, leaving the receiving domain blind to an
			ongoing attack.
	o Untrusted content: An attacker could inject malicious code into		o Untrusted content: An attacker could inject malicious code into
	the report, opening a vulnerability in the receiving domain.		the report, opening a vulnerability in the receiving domain.
	Implementers are advised to take precautions against evaluating		Implementers are advised to take precautions against evaluating
	the contents of the report.		the contents of the report.
	o Report snooping: An attacker could create a bogus TLSRPT record to		o Report snooping: An attacker could create a bogus TLSRPT record to
	receive statistics about a domain the attacker does not own.		receive statistics about a domain the attacker does not own.
	Since an attacker able to poison DNS is already able to receive		Since an attacker able to poison DNS is already able to receive
	counts of SMTP connections (and, absent DANE or MTA-STS policies,		counts of SMTP connections (and, absent DANE or MTA-STS policies,
	actual SMTP message payloads), this does not present a significant		actual SMTP message payloads), this does not present a significant
	new vulnerability.		new vulnerability.
	o Reports as DDoS: TLSRPT allows specifying destinations for the		o Reports as DDoS: TLSRPT allows specifying destinations for the
	reports that are outside the authority of the Policy Domain, which		reports that are outside the authority of the Policy Domain, which
	allows domains to delegate processing of reports to a partner		allows domains to delegate processing of reports to a partner
	organization. However, an attacker who controls the Policy Domain		organization. However, an attacker who controls the Policy Domain
	DNS could also use this mechanism to direct the reports to an		DNS could also use this mechanism to direct the reports to an
	unwitting victim, flooding that victim with excessive reports.		unwitting victim, flooding that victim with excessive reports.
	DMARC [RFC7489] defines an elegant solution for verifying		DMARC [RFC7489] defines a solution for verifying delegation to
	delegation; however, since the attacker had less ability to		avoid such attacks; the need for this is greater with DMARC,
	generate large reports than with DMARC failures, and since the		however, because DMARC allows an attacker to trigger reports to a
	reports are generated by the sending MTA, such a delegation		target from an innocent third party by sending that third party
	mechanism is left for a future version of this specification.		mail (which triggers a report from the third party to the target).
			In the case of TLSRPT, the attacker would have to induce the third
			party to send the attacker mail in order to trigger reports from
			the third party to the victim; this reduces the risk of such an
			attack and the need for a verification mechanism.
	8. Appendix 1: Example Reporting Policy		8. Appendix 1: Example Reporting Policy
	8.1. Report using MAILTO		8.1. Report using MAILTO
	_smtp-tlsrpt.mail.example.com. IN TXT \		_smtp-tlsrpt.mail.example.com. IN TXT \
	"v=TLSRPTv1;rua=mailto:reports@example.com"		"v=TLSRPTv1;rua=mailto:reports@example.com"
	8.2. Report using HTTPS		8.2. Report using HTTPS
	_smtp-tlsrpt.mail.example.com. IN TXT \		_smtp-tlsrpt.mail.example.com. IN TXT \
	"v=TLSRPTv1; \		"v=TLSRPTv1; \
	rua=https://reporting.example.com/v1/tlsrpt"		rua=https://reporting.example.com/v1/tlsrpt"
	9. Appendix 2: JSON Report Schema		9. Appendix 2: Example JSON Report
	The JSON schema is derived from the HPKP JSON schema [RFC7469] (cf.
	Section 3)
	{
	"organization-name": organization-name,
	"date-range": {
	"start-datetime": date-time,
	"end-datetime": date-time
	},
	"contact-info": email-address,
	"report-id": report-id,
	"policy": {
	"policy-type": policy-type,
	"policy-string": policy-string,
	"policy-domain": domain,
	"mx-host": mx-host-pattern
	},
	"summary": {
	"success-aggregate": total-successful-session-count,
	"failure-aggregate:" total-failure-session-count
	}
	"failure-details": [
	{
	"result-type": result-type,
	"sending-mta-ip": ip-address,
	"receiving-mx-hostname": receiving-mx-hostname,
	"receiving-mx-helo": receiving-mx-helo,
	"session-count": failed-session-count,
	"additional-information": additional-info-uri,
	"failure-reason-code": "Text body"
	}
	]
	}
	Figure: JSON Report Format
	o "organization-name": The name of the organization responsible for
	the report. It is provided as a string.
	o "date-time": The date-time indicates the start- and end-times for
	the report range. It is provided as a string formatted according
	to Section 5.6, "Internet Date/Time Format", of [RFC3339]. The
	report should be for a full UTC day, 0000-2400.
	o "email-address": The contact information for a responsible party
	of the report. It is provided as a string formatted according to
	Section 3.4.1, "Addr-Spec", of [RFC5322].
	o "report-id": A unique identifier for the report. Report authors
	may use whatever scheme they prefer to generate a unique
	identifier. It is provided as a string.
	o "policy-type": The type of policy that was applied by the sending
	domain. Presently, the only three valid choices are "tlsa",
	"sts", and the literal string "no-policy-found". It is provided
	as a string.
	o "policy-string": The JSON string serialization ([RFC7159] section
	7) of the policy, whether TLSA record ([RFC6698] section 2.3) or
	MTA-STS policy.
	o "domain": The Policy Domain is the domain against which the MTA-
	STS or DANE policy is defined.
	o "mx-host-pattern": The pattern of MX hostnames from the applied
	policy. It is provided as a string, and is interpreted in the
	same manner as the "Checking of Wildcard Certificates" rules in
	Section 6.4.3 of [RFC6125].
	o "result-type": A value from Section 4.3, "Result Types", above.
	o "ip-address": The IP address of the sending MTA that attempted the
	STARTTLS connection. It is provided as a string representation of
	an IPv4 or IPv6 address in dot-decimal or colon-hexadecimal
	notation.
	o "receiving-mx-hostname": The hostname of the receiving MTA MX
	record with which the sending MTA attempted to negotiate a
	STARTTLS connection.
	o "receiving-mx-helo": (optional) The HELO or EHLO string from the
	banner announced during the reported session.
	o "success-aggregate": The aggregate number (integer) of
	successfully negotiated TLS-enabled connections to the receiving
	site.
	o "failure-aggregate": The aggregate number (integer) of failures to
	negotiate an TLS-enabled connection to the receiving site.
	o "session-count": The number of (attempted) sessions that match the
	relevant "result-type" for this section.
	o "additional-info-uri": An optional URI pointing to additional
	information around the relevant "result-type". For example, this
	URI might host the complete certificate chain presented during an
	attempted STARTTLS session.
	o "failure-reason-code": A text field to include an TLS-related
	error code or error message.
	10. Appendix 3: Example JSON Report
	{		{
	"organization-name": "Company-X",		"organization-name": "Company-X",
	"date-range": {		"date-range": {
	"start-datetime": "2016-04-01T00:00:00Z",		"start-datetime": "2016-04-01T00:00:00Z",
	"end-datetime": "2016-04-01T23:59:59Z"		"end-datetime": "2016-04-01T23:59:59Z"
	},		},
	"contact-info": "sts-reporting@company-x.com",		"contact-info": "sts-reporting@company-x.com",
	"report-id": "5065427c-23d3-47ca-b6e0-946ea0e8c4be",		"report-id": "5065427c-23d3-47ca-b6e0-946ea0e8c4be",
	"policy": {		"policy": {
	"policy-type": "sts",		"policy-type": "sts",
	skipping to change at page 16, line 5 ¶		skipping to change at page 20, line 5 ¶
	}]		}]
	}		}
	Figure: Example JSON report for a messages from Company-X to		Figure: Example JSON report for a messages from Company-X to
	Company-Y, where 100 sessions were attempted to Company Y servers		Company-Y, where 100 sessions were attempted to Company Y servers
	with an expired certificate and 200 sessions were attempted to		with an expired certificate and 200 sessions were attempted to
	Company Y servers that did not successfully respond to the "STARTTLS"		Company Y servers that did not successfully respond to the "STARTTLS"
	command. Additionally 3 sessions failed due to		command. Additionally 3 sessions failed due to
	"X509_V_ERR_PROXY_PATH_LENGTH_EXCEEDED".		"X509_V_ERR_PROXY_PATH_LENGTH_EXCEEDED".
	11. Normative References		10. 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, DOI 10.17487/		Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
	RFC2119, March 1997,		RFC2119, March 1997,
	<http://www.rfc-editor.org/info/rfc2119>.		<http://www.rfc-editor.org/info/rfc2119>.
	[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, DOI 10.17487/		[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, DOI 10.17487/
	RFC2818, May 2000,		RFC2818, May 2000,
	<http://www.rfc-editor.org/info/rfc2818>.		<http://www.rfc-editor.org/info/rfc2818>.
	[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, <http://www.rfc-editor.org/info/rfc3207>.		February 2002, <http://www.rfc-editor.org/info/rfc3207>.
	[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:		[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
	Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,		Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
	<http://www.rfc-editor.org/info/rfc3339>.		<http://www.rfc-editor.org/info/rfc3339>.
			[RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration
			Procedures for Message Header Fields", BCP 90, RFC 3864,
			DOI 10.17487/RFC3864, September 2004,
			<http://www.rfc-editor.org/info/rfc3864>.
	[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax		[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
	Specifications: ABNF", STD 68, RFC 5234, DOI 10.17487/		Specifications: ABNF", STD 68, RFC 5234, DOI 10.17487/
	RFC5234, January 2008,		RFC5234, January 2008,
	<http://www.rfc-editor.org/info/rfc5234>.		<http://www.rfc-editor.org/info/rfc5234>.
	[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322, DOI		[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322, DOI
	10.17487/RFC5322, October 2008,		10.17487/RFC5322, October 2008,
	<http://www.rfc-editor.org/info/rfc5322>.		<http://www.rfc-editor.org/info/rfc5322>.
	[RFC6068] Duerst, M., Masinter, L., and J. Zawinski, "The 'mailto'		[RFC6068] Duerst, M., Masinter, L., and J. Zawinski, "The 'mailto'
	URI Scheme", RFC 6068, DOI 10.17487/RFC6068, October 2010,		URI Scheme", RFC 6068, DOI 10.17487/RFC6068, October 2010,
	<http://www.rfc-editor.org/info/rfc6068>.		<http://www.rfc-editor.org/info/rfc6068>.
	[RFC6125] Saint-Andre, P. and J. Hodges, "Representation and		[RFC6125] Saint-Andre, P. and J. Hodges, "Representation and
	Verification of Domain-Based Application Service Identity		Verification of Domain-Based Application Service Identity
	within Internet Public Key Infrastructure Using X.509		within Internet Public Key Infrastructure Using X.509
	(PKIX) Certificates in the Context of Transport Layer		(PKIX) Certificates in the Context of Transport Layer
	Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March		Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March
	2011, <http://www.rfc-editor.org/info/rfc6125>.		2011, <http://www.rfc-editor.org/info/rfc6125>.
			[RFC6522] Kucherawy, M., Ed., "The Multipart/Report Media Type for
			the Reporting of Mail System Administrative Messages", STD
			73, RFC 6522, DOI 10.17487/RFC6522, January 2012,
			<http://www.rfc-editor.org/info/rfc6522>.
	[RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication		[RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
	of Named Entities (DANE) Transport Layer Security (TLS)		of Named Entities (DANE) Transport Layer Security (TLS)
	Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August		Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August
	2012, <http://www.rfc-editor.org/info/rfc6698>.		2012, <http://www.rfc-editor.org/info/rfc6698>.
	[RFC6713] Levine, J., "The 'application/zlib' and 'application/gzip'
	Media Types", RFC 6713, DOI 10.17487/RFC6713, August 2012,
	<http://www.rfc-editor.org/info/rfc6713>.
	[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data		[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>.
	[RFC7435] Dukhovni, V., "Opportunistic Security: Some Protection		[RFC7435] Dukhovni, V., "Opportunistic Security: Some Protection
	Most of the Time", RFC 7435, DOI 10.17487/RFC7435,		Most of the Time", RFC 7435, DOI 10.17487/RFC7435,
	December 2014, <http://www.rfc-editor.org/info/rfc7435>.		December 2014, <http://www.rfc-editor.org/info/rfc7435>.
	[RFC7469] Evans, C., Palmer, C., and R. Sleevi, "Public Key Pinning		[RFC7469] Evans, C., Palmer, C., and R. Sleevi, "Public Key Pinning
	Extension for HTTP", RFC 7469, DOI 10.17487/RFC7469, April		Extension for HTTP", RFC 7469, DOI 10.17487/RFC7469, April
End of changes. 23 change blocks.
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