draft-ietf-marf-dkim-reporting-15.txt		draft-ietf-marf-dkim-reporting.txt
	MARF Working Group M. Kucherawy		MARF Working Group M. Kucherawy
	Internet-Draft Cloudmark		Internet-Draft Cloudmark
	Intended status: Standards Track March 14, 2012		Intended status: Standards Track March 19, 2012
	Expires: September 15, 2012		Expires: September 20, 2012
	Extensions to DKIM for Failure Reporting		Extensions to DKIM for Failure Reporting
	draft-ietf-marf-dkim-reporting-15		draft-ietf-marf-dkim-reporting-16
	Abstract		Abstract
	This memo presents extensions to the DomainKeys Identified Mail		This document presents extensions to the DomainKeys Identified Mail
	(DKIM) specification to allow for detailed reporting of message		(DKIM) specification to allow for detailed reporting of message
	authentication failures in an on-demand fashion.		authentication failures in an on-demand fashion.
	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 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 September 15, 2012.		This Internet-Draft will expire on September 20, 2012.
	Copyright Notice		Copyright Notice
	Copyright (c) 2012 IETF Trust and the persons identified as the		Copyright (c) 2012 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 10		skipping to change at page 2, line 10
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	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
	2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 4		2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 4
	2.1. Keywords . . . . . . . . . . . . . . . . . . . . . . . . . 4		2.1. Keywords . . . . . . . . . . . . . . . . . . . . . . . . . 4
	2.2. Imported Definitions . . . . . . . . . . . . . . . . . . . 4		2.2. Notation . . . . . . . . . . . . . . . . . . . . . . . . . 4
	2.3. Notation . . . . . . . . . . . . . . . . . . . . . . . . . 4		2.3. Imported Definitions . . . . . . . . . . . . . . . . . . . 4
	2.4. Other Definitions . . . . . . . . . . . . . . . . . . . . 4		2.4. Other Definitions . . . . . . . . . . . . . . . . . . . . 4
	3. Optional Reporting for DKIM . . . . . . . . . . . . . . . . . 5		3. Optional Reporting for DKIM . . . . . . . . . . . . . . . . . 5
	3.1. Extension DKIM Signature Tag . . . . . . . . . . . . . . . 5		3.1. Extension DKIM Signature Tag . . . . . . . . . . . . . . . 5
	3.2. DKIM Reporting TXT Record . . . . . . . . . . . . . . . . 5		3.2. DKIM Reporting TXT Record . . . . . . . . . . . . . . . . 5
	3.3. DKIM Reporting Algorithm . . . . . . . . . . . . . . . . . 7		3.3. DKIM Reporting Algorithm . . . . . . . . . . . . . . . . . 7
	4. Optional Reporting Address for DKIM-ADSP . . . . . . . . . . . 10		4. Optional Reporting Address for DKIM-ADSP . . . . . . . . . . . 9
	5. Requested Reports . . . . . . . . . . . . . . . . . . . . . . 12		5. Requested Reports . . . . . . . . . . . . . . . . . . . . . . 11
	5.1. Requested Reports for DKIM Failures . . . . . . . . . . . 12		5.1. Requested Reports for DKIM Failures . . . . . . . . . . . 11
	5.2. Requested Reports for DKIM ADSP Failures . . . . . . . . . 12		5.2. Requested Reports for DKIM ADSP Failures . . . . . . . . . 11
	6. Report Generation . . . . . . . . . . . . . . . . . . . . . . 14		6. Report Generation . . . . . . . . . . . . . . . . . . . . . . 13
	6.1. Report Format . . . . . . . . . . . . . . . . . . . . . . 14		6.1. Report Format . . . . . . . . . . . . . . . . . . . . . . 13
	6.2. Other Guidance . . . . . . . . . . . . . . . . . . . . . . 14		6.2. Other Guidance . . . . . . . . . . . . . . . . . . . . . . 13
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
	7.1. DKIM Signature Tag Registration . . . . . . . . . . . . . 15		7.1. DKIM Signature Tag Registration . . . . . . . . . . . . . 14
	7.2. DKIM ADSP Tag Registration . . . . . . . . . . . . . . . . 15		7.2. DKIM ADSP Tag Registration . . . . . . . . . . . . . . . . 14
	7.3. DKIM Reporting Tag Registry . . . . . . . . . . . . . . . 15		7.3. DKIM Reporting Tag Registry . . . . . . . . . . . . . . . 14
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 17		8. Security Considerations . . . . . . . . . . . . . . . . . . . 16
	8.1. Inherited Considerations . . . . . . . . . . . . . . . . . 17		8.1. Inherited Considerations . . . . . . . . . . . . . . . . . 16
	8.2. Report Volume . . . . . . . . . . . . . . . . . . . . . . 17		8.2. Report Volume . . . . . . . . . . . . . . . . . . . . . . 16
	8.3. Deliberate Misuse . . . . . . . . . . . . . . . . . . . . 17		8.3. Deliberate Misuse . . . . . . . . . . . . . . . . . . . . 16
	8.4. Unreported Fraud . . . . . . . . . . . . . . . . . . . . . 18		8.4. Unreported Fraud . . . . . . . . . . . . . . . . . . . . . 17
	9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19		9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
	9.1. Normative References . . . . . . . . . . . . . . . . . . . 19		9.1. Normative References . . . . . . . . . . . . . . . . . . . 18
	9.2. Informative References . . . . . . . . . . . . . . . . . . 20		9.2. Informative References . . . . . . . . . . . . . . . . . . 19
	Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 21		Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 20
	Appendix B. Examples . . . . . . . . . . . . . . . . . . . . . . 22		Appendix B. Examples . . . . . . . . . . . . . . . . . . . . . . 21
	B.1. Example Use of DKIM Signature Extension Tag . . . . . . . 22		B.1. Example Use of DKIM Signature Extension Tag . . . . . . . 21
	B.2. Example DKIM Reporting TXT Record . . . . . . . . . . . . 22		B.2. Example DKIM Reporting TXT Record . . . . . . . . . . . . 21
	B.3. Example Use of DKIM ADSP Extension Tags . . . . . . . . . 23		B.3. Example Use of DKIM ADSP Extension Tags . . . . . . . . . 22
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 24		Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 23
	1. Introduction		1. Introduction
	DomainKeys Identified Mail [DKIM] introduced a mechanism for message		DomainKeys Identified Mail [DKIM] introduced a mechanism for message
	signing and authentication. It uses digital signing to associate a		signing and authentication. It uses digital signing to associate a
	domain name with a message in a reliable (i.e. not easily forged)		domain name with a message in a reliable manner. The verified domain
	manner. The output is a verified domain name that can then be		name can then be evaluated (e.g., checking advertised sender policy,
	subjected to some sort of evaluation process (e.g., advertised sender		comparison to a known-good list, submission to a reputation service,
	policy, comparison to a known-good list, submission to a reputation		etc.).
	service, etc.).
	Deployers of message authentication technologies are increasingly		Deployers of message authentication technologies are increasingly
	seeking visibility into DKIM verification failures and conformance		seeking visibility into DKIM verification failures and conformance
	failures involving the published signing practices (e.g., Author		failures involving the published signing practices (e.g., Author
	Domain Signing Practices, [ADSP]) of an Administrative Management		Domain Signing Practices, [ADSP]) of an Administrative Management
	Domain (ADMD; see [EMAIL-ARCH]).		Domain (ADMD; see [EMAIL-ARCH]).
	This document extends [DKIM] and [ADSP] to add an optional reporting		This document extends [DKIM] and [ADSP] to add an optional reporting
	address and some reporting parameters. Reports are generated using		address and some reporting parameters. Reports are generated using
	the format defined in [I-D.IETF-MARF-AUTHFAILURE-REPORT].		the format defined in [I-D.IETF-MARF-AUTHFAILURE-REPORT].
	2. Definitions		2. Definitions
	2.1. Keywords		2.1. Keywords
	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", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in [KEYWORDS].		document are to be interpreted as described in [KEYWORDS].
	2.2. Imported Definitions		2.2. Notation
	The [ABNF] token "qp-section" is imported from [MIME].
	Numerous DKIM-specific terms used here are defined in [DKIM]. The
	definition of the ABNF token "domain-name" can also be found there.
	2.3. Notation
	Certain properties of email messages described in this document are		Certain properties of email messages described in this document are
	referenced using notation found in [EMAIL-ARCH] (e.g.,		referenced using notation found in [EMAIL-ARCH] (e.g.,
	"RFC5322.From").		"RFC5322.From").
			2.3. Imported Definitions
			Numerous DKIM-specific terms used here are defined in [DKIM]. The
			definitions of the [ABNF] tokens "domain-name" and "dkim-quoted-
			printable" can also be found there.
	2.4. Other Definitions		2.4. Other Definitions
	report generator: A report generator is an entity that generates and		report generator: A report generator is an entity that generates and
	sends reports. For the scope of this memo, the term refers to		sends reports. For the scope of this document, the term refers to
	Verifiers, as defined in Section 2.2 of [DKIM], designed also to		Verifiers, as defined in Section 2.2 of [DKIM], with the added
	generate authentication failure reports according to this		capability to generate authentication failure reports according to
	specification.		this specification.
	3. Optional Reporting for DKIM		3. Optional Reporting for DKIM
	A domain name owner employing [DKIM] for email signing and		A domain name owner employing [DKIM] for email signing and
	authentication might want to know when signatures that ought to be		authentication might want to know when signatures that ought to be
	verifiable with specific public keys are not successfully verifying.		verifiable are not successfully verifying. Currently there is no
	Currently there is no such mechanism defined.		such mechanism defined.
	This document adds optional "tags" (as defined in [DKIM]) to the		This section adds optional "tags" (as defined in [DKIM]) to the DKIM-
	DKIM-Signature header field and the DKIM key record in the DNS, using		Signature header field and the DKIM key record in the DNS, using the
	the formats defined in that specification.		formats defined in that specification.
	3.1. Extension DKIM Signature Tag		3.1. Extension DKIM Signature Tag
	The following tag is added to DKIM-Signature header fields when a		The following tag is added to DKIM-Signature header fields when a
	Signer wishes to request that reports of failed verifications be		Signer wishes to request that reports of failed verifications be
	generated by a Verifier:		generated by a Verifier:
	r= Reporting Requested (plain-text; OPTIONAL; no default). If		r= Reporting Requested (plain-text; OPTIONAL; no default). If
	present, this tag indicates that the Signer requests that		present, this tag indicates that the Signer requests that
	Verifiers generate a report when verification of the DKIM		Verifiers generate a report when verification of the DKIM
	signature fails. At present, the only legal value is the single		signature fails. At present, the only legal value is the single
	character "y" (in either upper or lower case). A complete		character "y". A complete description and illustration of how
	description and illustration of how this is applied can be found		this is applied can be found in Section 3.3.
	in Section 3.3.
	ABNF:		ABNF:
	sig-r-tag = %x72 *WSP "=" *WSP %x79		sig-r-tag = %x72 *WSP "=" *WSP %x79
	; "r=y" (lower-case only)		; "r=y" (lower-case only)
	3.2. DKIM Reporting TXT Record		3.2. DKIM Reporting TXT Record
	When a Signer wishes to advertise that it wants to receive failed		When a Signer wishes to advertise that it wants to receive failed
	verification reports, it places in the DNS a TXT resource record		verification reports, it places in the DNS a TXT resource record
	(RR). The RR is made up of a sequence of tag-value objects (much		(RR). The RR contains a sequence of tag-value objects in a format
	like DKIM key records, as defined in Section 3.6.1 of [DKIM]), but it		similar to DKIM key records (see Section 3.6.1 of [DKIM]), but it is
	is entirely independent of those key records and is found at a		entirely independent of those key records and is found at a different
	different name. In the case of a record advertising the desire for		name. The tag-value objects in this case comprise the parameters to
	authentication failure reports, the tags and values comprise the		be used when generating the reports. A report generator will request
	parameters to be used when generating the reports. A report		the content of this record when it sees an "r=" tag in a DKIM-
	generator will request the content of this record when it sees an		Signature header field.
	"r=" tag in a DKIM-Signature header field.
	Section 3.6.2.2 of [DKIM] provides guidance with respect to handling		Section 3.6.2.2 of [DKIM] provides guidance with respect to handling
	of a TXT RR that comprises multiple distinct strings ("character-		of a TXT RR that comprises multiple distinct strings ("character-
	strings" in the parlance of [DNS]). The same process MUST be applied		strings" in the parlance of [DNS]). The same process MUST be applied
	here.		here.
	Implementations MUST support all tags defined in this document, and		Implementations MUST support all tags defined in this document, and
	any other tag found in the content of the record that is not		any other tag found in the content of the record that is not
	recognized by an implementation MUST be ignored. See Section 7.3 for		recognized by an implementation MUST be ignored. See Section 7.3 for
	details about finding or registering extension tags.		details about finding or registering extension tags.
	skipping to change at page 6, line 25		skipping to change at page 6, line 22
	local-part of an email address to which a report SHOULD be sent		local-part of an email address to which a report SHOULD be sent
	when mail fails DKIM verification for one of the reasons		when mail fails DKIM verification for one of the reasons
	enumerated below. The value MUST be interpreted as a local-part		enumerated below. The value MUST be interpreted as a local-part
	only. To construct the actual address to which the report is		only. To construct the actual address to which the report is
	sent, the Verifier simply appends to this value an "@" followed by		sent, the Verifier simply appends to this value an "@" followed by
	the domain name found in the "d=" tag of the DKIM-Signature header		the domain name found in the "d=" tag of the DKIM-Signature header
	field. Therefore, an ADMD making use of this specification MUST		field. Therefore, an ADMD making use of this specification MUST
	ensure that an email address thus constructed can receive reports		ensure that an email address thus constructed can receive reports
	generated as described in Section 6. ABNF:		generated as described in Section 6. ABNF:
	rep-ra-tag = %x72.61 *WSP "=" *WSP qp-section		rep-ra-tag = %x72.61 *WSP "=" *WSP dkim-quoted-printable
	; "ra=..." (lower-case only for the tag name)		; "ra=..." (lower-case only for the tag name)
	rp= Requested Report Percentage (plain-text; OPTIONAL; default is		rp= Requested Report Percentage (plain-text; OPTIONAL; default is
	"100"). The value is an integer from 0 to 100 inclusive that		"100"). The value is an integer from 0 to 100 inclusive that
	indicates what percentage of incidents of signature authentication		indicates what percentage of incidents of signature authentication
	failures, selected at random, are to cause reports to be		failures, selected at random, are to cause reports to be
	generated. The report generator SHOULD NOT issue reports for more		generated. The report generator SHOULD NOT issue reports for more
	than the requested percentage of incidents. Report generators MAY		than the requested percentage of incidents. Report generators MAY
	make use of the "Incidents:" field in [ARF] to indicate that there		make use of the "Incidents:" field in [ARF] to indicate that there
	are more reportable incidents than there are reports. ABNF:		are more reportable incidents than there are reports. ABNF:
	rep-rp-tag = %x72.70 *WSP "=" *WSP 1*3DIGIT		rep-rp-tag = %x72.70 *WSP "=" *WSP 1*3DIGIT
	; "rp=..." (lower-case only)		; "rp=..." (lower-case only)
	rr= Requested Reports (plain-text; OPTIONAL; default is "all"). The		rr= Requested Reports (plain-text; OPTIONAL; default is "all"). The
	value MUST be a colon-separated list of tokens representing those		value MUST be a colon-separated list of tokens representing those
	conditions under which a report is desired. See Section 5.1 for a		conditions under which a report is desired. See Section 5.1 for a
	list of valid tags. ABNF:		list of valid tokens. ABNF:
	rep-rr-type = ( "all" / "d" / "o" / "p"/ "s" / "u" / "v" / "x" )		rep-rr-type = ( "all" / "d" / "o" / "p"/ "s" / "u" / "v" / "x" )
	rep-rr-tag = %x72.72 *WSP "=" *WSP rep-rr-type		rep-rr-tag = %x72.72 *WSP "=" *WSP rep-rr-type
	*WSP 0* ( ":" *WSP rep-rr-type )		*WSP *( ":" *WSP rep-rr-type )
	; "rr=..." (lower-case only for the tag name)		; "rr=..." (lower-case only for the tag name)
	rs= Requested SMTP Error String (text; OPTIONAL; no default). The		rs= Requested SMTP Error String (text; OPTIONAL; no default). The
	value is a dkim-quoted-printable string that the publishing ADMD		value is a dkim-quoted-printable string that the publishing ADMD
	requests be included in [SMTP] error strings if messages are		requests be included in [SMTP] error strings if messages are
	rejected during the delivery SMTP session. ABNF:		rejected during the delivery SMTP session. ABNF:
	rep-rs-tag = %x72.73 *WSP "=" qp-section		rep-rs-tag = %x72.73 *WSP "=" dkim-quoted-printable
	; "rs=..." (lower-case only for the tag name)		; "rs=..." (lower-case only for the tag name)
	In the absence of an "ra=" tag, the "rp=" and "rr=" tags MUST be		In the absence of an "ra=" tag, the "rp=" and "rr=" tags MUST be
	ignored, and the report generator MUST NOT issue a report.		ignored, and the report generator MUST NOT issue a report.
	3.3. DKIM Reporting Algorithm		3.3. DKIM Reporting Algorithm
	Report generators MUST apply the following algorithm, or one		Report generators MUST apply the following algorithm, or one
	semantically equivalent to it, for each DKIM-Signature header field		semantically equivalent to it, for each DKIM-Signature header field
	whose verification fails for some reason. Note that this processing		whose verification fails for some reason. Note that this processing
	skipping to change at page 8, line 8		skipping to change at page 7, line 52
	number between 0 and 99, inclusive; if the selected number is		number between 0 and 99, inclusive; if the selected number is
	not lower than the tag's value, terminate.		not lower than the tag's value, terminate.
	8. If no "ra=" tag was present, skip this step and the next one.		8. If no "ra=" tag was present, skip this step and the next one.
	Otherwise, determine the reporting address by extracting the		Otherwise, determine the reporting address by extracting the
	value of the "ra=" tag and appending to it "@" followed by the		value of the "ra=" tag and appending to it "@" followed by the
	domain name found in the "d=" tag of the DKIM-Signature header		domain name found in the "d=" tag of the DKIM-Signature header
	field.		field.
	9. Construct and send a report in compliance with Section 6 of this		9. Construct and send a report in compliance with Section 6 of this
	memo that includes as its intended recipient the address		document that includes as its intended recipient the address
	constructed in the previous step.		constructed in the previous step.
	10. If the [SMTP] session during which the DKIM signautre was		10. If the [SMTP] session during which the DKIM signautre was
	evaluated is still active and the SMTP server has not already		evaluated is still active and the SMTP server has not already
	given its response to the DATA command that relayed the message,		given its response to the DATA command that relayed the message,
	and an "rs=" tag was present in the TXT record, the SMTP server		and an "rs=" tag was present in the TXT record, the SMTP server
	SHOULD include the decoded string found in the "rs=" tag in its		SHOULD include the decoded string found in the "rs=" tag in its
	SMTP reply to the DATA command.		SMTP reply to the DATA command.
	In order to thwart attacks that seek to convert report generators		In order to thwart attacks that seek to convert report generators
	skipping to change at page 9, line 5		skipping to change at page 8, line 47
	malicious Signer cannot falsely assert that someone else wants		malicious Signer cannot falsely assert that someone else wants
	failure reports and cause unwanted mail to be generated. It can		failure reports and cause unwanted mail to be generated. It can
	cause additional DNS traffic against the domain listed in the		cause additional DNS traffic against the domain listed in the
	"d=" signature tag, but negative caching of the requested DNS		"d=" signature tag, but negative caching of the requested DNS
	record will help to mitigate this issue.		record will help to mitigate this issue.
	c. It is not possible for a Signer to direct reports to an email		c. It is not possible for a Signer to direct reports to an email
	address outside of its own domain, preventing distributed email-		address outside of its own domain, preventing distributed email-
	based denial-of-service attacks.		based denial-of-service attacks.
	See Section 8.4 for some considerations regardin limitations of this		See Section 8.4 for some considerations regarding limitations of this
	mechanism.		mechanism.
	4. Optional Reporting Address for DKIM-ADSP		4. Optional Reporting Address for DKIM-ADSP
	There also exist cases in which a domain name owner employing [ADSP]		A domain name owner employing Author Domain Signing Practices [ADSP]
	for announcing signing practises with DKIM may want to know when		may also want to know when messages are received without valid author
	messages are received without valid author domain signatures.		domain signatures. Currently there is no such mechanism defined.
	Currently there is no such mechanism defined.
	This document adds the following optional "tags" (as defined in		This section adds the following optional "tags" (as defined in
	[ADSP]) to the DKIM ADSP records, using the form defined in that		[ADSP]) to the DKIM ADSP records, using the form defined in that
	specification:		specification:
	ra= Reporting Address (plain-text; OPTIONAL; no default). The value		ra= Reporting Address (plain-text; OPTIONAL; no default). The value
	MUST be a dkim-quoted-printable string containing the local-part		MUST be a dkim-quoted-printable string containing the local-part
	of an email address to which a report SHOULD be sent when mail		of an email address to which a report SHOULD be sent when mail
	claiming to be from this domain failed the verification algorithm		claiming to be from this domain failed the verification algorithm
	described in [ADSP], in particular because a message arrived		described in [ADSP], in particular because a message arrived
	without a signature that validates, which contradicts what the		without a signature that validates, which contradicts what the
	ADSP record claims. The value MUST be interpreted as a local-part		ADSP record claims. The value MUST be interpreted as a local-part
	only. To construct the actual address to which the report is		only. To construct the actual address to which the report is
	sent, the Verifier simply appends to this value an "@" followed by		sent, the Verifier simply appends to this value an "@" followed by
	the domain whose policy was queried in order to evaluate the		the domain whose policy was queried in order to evaluate the
	sender's ADSP, i.e., the RFC5322.From domain of the message under		sender's ADSP, i.e., the RFC5322.From domain of the message under
	evaluation. Therefore, a signer making use of this extension tag		evaluation. Therefore, a signer making use of this extension tag
	MUST ensure that an email address thus constructed can receive		MUST ensure that an email address thus constructed can receive
	reports generated as described in Section 6. ABNF:		reports generated as described in Section 6. ABNF:
	adsp-ra-tag = %x72.61 *WSP "=" qp-section		adsp-ra-tag = %x72.61 *WSP "=" dkim-quoted-printable
	; "ra=..." (lower-case only for the tag name)		; "ra=..." (lower-case only for the tag name)
	rp= Requested Report Percentage (plain-text; OPTIONAL; default is		rp= Requested Report Percentage (plain-text; OPTIONAL; default is
	"100"). The value is a single integer from 0 to 100 inclusive		"100"). The value is a single integer from 0 to 100 inclusive
	that indicates what percentage of incidents of ADSP evaluation		that indicates what percentage of incidents of ADSP evaluation
	failures, selected at random, should cause reports to be		failures, selected at random, should cause reports to be
	generated. The report generator SHOULD NOT issue reports for more		generated. The report generator SHOULD NOT issue reports for more
	than the requested percentage of incidents. An exception to this		than the requested percentage of incidents. An exception to this
	might be some out-of-band arrangement between two parties to		might be some out-of-band arrangement between two parties to
	override it with some mutually agreed value. Report generators		override it with some mutually agreed value. Report generators
	MAY make use of the "Incidents:" field in [ARF] to indicate that		MAY make use of the "Incidents:" field in [ARF] to indicate that
	there are more reportable incidents than there are reports. ABNF:		there are more reportable incidents than there are reports. ABNF:
	adsp-rp-tag = %x72.70 *WSP "=" *WSP 1*3DIGIT		adsp-rp-tag = %x72.70 *WSP "=" *WSP 1*3DIGIT
	; "rp=..." (lower-case only)		; "rp=..." (lower-case only)
	rr= Requested Reports (plain-text; OPTIONAL; default is "all"). The		rr= Requested Reports (plain-text; OPTIONAL; default is "all"). The
	value MUST be a colon-separated list of tokens representing those		value MUST be a colon-separated list of tokens representing those
	conditions under which a report is desired. See Section 5.2 for a		conditions under which a report is desired. See Section 5.2 for a
	list of valid tags. ABNF:		list of valid tokens. ABNF:
	adsp-rr-type = ( "all" / "o" / "p" / "s" / "u" )		adsp-rr-type = ( "all" / "o" / "p" / "s" / "u" )
	adsp-rr-tag = %x72.72 *WSP "=" *WSP adsp-rr-type		adsp-rr-tag = %x72.72 *WSP "=" *WSP adsp-rr-type
	*WSP 0* ( ":" *WSP adsp-rr-type )		*WSP *( ":" *WSP adsp-rr-type )
	; "rr=..." (lower-case only for the tag name)		; "rr=..." (lower-case only for the tag name)
	rs= Requested SMTP Error String (plain-text; OPTIONAL; no default).		rs= Requested SMTP Error String (plain-text; OPTIONAL; no default).
	The value is a string the signing domain requests be included in		The value is a string the signing domain requests be included in
	[SMTP] error strings when messages are rejected during a single		[SMTP] error strings when messages are rejected during a single
	SMTP session. ABNF:		SMTP session. ABNF:
	adsp-rs-tag = %x72.73 *WSP "=" qp-section		adsp-rs-tag = %x72.73 *WSP "=" dkim-quoted-printable
	; "rs=..." (lower-case only for the tag name)		; "rs=..." (lower-case only for the tag name)
	In the absence of an "ra=" tag, the "rp=" and "rr=" tags MUST be		In the absence of an "ra=" tag, the "rp=" and "rr=" tags MUST be
	ignored, and the report generator MUST NOT issue a report.		ignored, and the report generator MUST NOT issue a report.
	5. Requested Reports		5. Requested Reports
	This memo also includes, as the "rr" tags defined above, the means by		This "rr" tags defined above allow a Signer to specify the types of
	which the signer can request reports for specific circumstances of		errors about which it is interested in receiving reports. This
	interest. Verifiers MUST NOT generate reports for incidents that do		section defines the error types and corresponding token values.
	not match a requested report, and MUST ignore requests for reports
	not included in this list.		Verifiers MUST NOT generate reports for incidents that do not match a
			requested report, and MUST ignore requests for reports not included
			in this list.
	5.1. Requested Reports for DKIM Failures		5.1. Requested Reports for DKIM Failures
	The following report requests are defined for DKIM keys:		The following report requests are defined for DKIM keys:
	all All reports are requested.		all All reports are requested.
	d Reports are requested for signature evaluation errors that		d Reports are requested for signature evaluation errors that
	resulted from DNS issues (e.g., key retrieval problems).		resulted from DNS issues (e.g., key retrieval problems).
	skipping to change at page 17, line 27		skipping to change at page 16, line 27
	8.2. Report Volume		8.2. Report Volume
	It is impossible to predict the volume of reports this facility will		It is impossible to predict the volume of reports this facility will
	generate when enabled by a report receiver. An implementer ought to		generate when enabled by a report receiver. An implementer ought to
	anticipate substantial volume, since the amount of abuse occurring at		anticipate substantial volume, since the amount of abuse occurring at
	receivers cannot be known ahead of time, and may vary rapidly and		receivers cannot be known ahead of time, and may vary rapidly and
	unpredictably.		unpredictably.
	8.3. Deliberate Misuse		8.3. Deliberate Misuse
	Some threats caused by deliberate misuse of this mechanism are		Some threats caused by deliberate misuse of this error reporting
	discussed in Section 3.3, but they warrant further discussion here.		mechanism are discussed in Section 3.3, but they warrant further
			discussion here.
	Negative caching offers some protection against this pattern of
	abuse, although it will work only as long as the negative time-to-
	live on the relevant SOA record in the DNS.
	The presence of the DNS record that indicates willingness to accept		The presence of the DNS record that indicates willingness to accept
	reports opens the recipient to abuse. In particular, it is possible		reports opens the recipient to abuse. In particular, it is possible
	for an attacker to attempt to cause a flood of reports toward the		for an attacker to attempt to cause a flood of reports toward the
	domain identified in a signature's "d=" tag in one of these ways:		domain identified in a signature's "d=" tag in one of these ways:
	1. Alter existing DKIM-Signature header fields by adding an "r=y"		1. Alter existing DKIM-Signature header fields by adding an "r=y"
	tag (and possibly altering the "d=" tag to point at the target		tag (and possibly altering the "d=" tag to point at the target
	domain);		domain);
	skipping to change at page 18, line 8		skipping to change at page 17, line 5
	tag pointing at the target domain.		tag pointing at the target domain.
	Consider, for example, the situation where an an attacker sends out a		Consider, for example, the situation where an an attacker sends out a
	multi-million-message spam run, and includes in the messages a fake		multi-million-message spam run, and includes in the messages a fake
	DKIM signature containing "d=example.com; r=y". It won't matter that		DKIM signature containing "d=example.com; r=y". It won't matter that
	those signatures couldn't possibly be real: each will fail		those signatures couldn't possibly be real: each will fail
	verification, and any implementations that support this specification		verification, and any implementations that support this specification
	will report those failures, in the millions and in short order, to		will report those failures, in the millions and in short order, to
	example.com.		example.com.
	Implementers are therefore strongly advised not to advertise that DNS		Implementers are therefore strongly advised not to advertise the DNS
	record except when reports desired, including the risk of receiving		record specified in this document except when failure reports are
	this kind of attack.		desired. Upon doing so, unexpected traffic volumes and attacks
			should be anticipated.
			Negative caching offers some protection against this pattern of
			abuse, although it will work only as long as the negative time-to-
			live on the relevant SOA record in the DNS.
	Positive caching of this DNS reply also means turning off the flow of		Positive caching of this DNS reply also means turning off the flow of
	reports by removing the record is not likely to have immediate		reports by removing the record is not likely to have immediate
	effect. A low time-to-live on the record needs to be considered.		effect. A low time-to-live on the record needs to be considered.
	8.4. Unreported Fraud		8.4. Unreported Fraud
	An attacker can craft fraudulent DKIM-Signature fields on messages,		An attacker can craft fraudulent DKIM-Signature fields on messages,
	without using "r=" tags, and avoid having these reported. The		without using "r=" tags, and avoid having these reported. The
	procedure described in Section 3.3 does not permit the detection and		procedure described in Section 3.3 does not permit the detection and
	skipping to change at page 19, line 50		skipping to change at page 18, line 50
	(work in progress), January 2012.		(work in progress), January 2012.
	[IANA-CONSIDERATIONS]		[IANA-CONSIDERATIONS]
	Alvestrand, H. and T. Narten, "Guidelines for Writing an		Alvestrand, H. and T. Narten, "Guidelines for Writing an
	IANA Considerations Section in RFCs", RFC 5226, May 2008.		IANA Considerations Section in RFCs", RFC 5226, May 2008.
	[KEYWORDS]		[KEYWORDS]
	Bradner, S., "Key words for use in RFCs to Indicate		Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", RFC 2119, March 1997.		Requirement Levels", RFC 2119, March 1997.
	[MIME] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
	Extensions (MIME) Part One: Format of Internet Message
	Bodies", RFC 2045, November 1996.
	[SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,		[SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
	October 2008.		October 2008.
	9.2. Informative References		9.2. Informative References
	[DSN] Moore, K. and G. Vaudreuil, "An Extensible Message Format		[DSN] Moore, K. and G. Vaudreuil, "An Extensible Message Format
	for Delivery Status Notifications", RFC 3464,		for Delivery Status Notifications", RFC 3464,
	January 2003.		January 2003.
	[OPENDKIM]		[OPENDKIM]
	skipping to change at page 22, line 8		skipping to change at page 21, line 8
	Appendix A. Acknowledgements		Appendix A. Acknowledgements
	The authors wish to acknowledge the following for their review and		The authors wish to acknowledge the following for their review and
	constructive criticism of this proposal: Steve Atkins, Monica Chew,		constructive criticism of this proposal: Steve Atkins, Monica Chew,
	Dave Crocker, Tim Draegen, Frank Ellermann, JD Falk, John Levine,		Dave Crocker, Tim Draegen, Frank Ellermann, JD Falk, John Levine,
	Scott Kitterman, and Andrew Sullivan.		Scott Kitterman, and Andrew Sullivan.
	Appendix B. Examples		Appendix B. Examples
	This section contains examples of the use of each of the extensions		This section contains examples of the use of each of the extensions
	defined by this memo.		defined by this document.
	B.1. Example Use of DKIM Signature Extension Tag		B.1. Example Use of DKIM Signature Extension Tag
	A DKIM-Signature field including use of the extension tag defined by		A DKIM-Signature field including use of the extension tag defined by
	this memo:		this document:
	DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple;		DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple;
	d=example.com; s=jan2012; r=y;		d=example.com; s=jan2012; r=y;
	h=from:to:subject:date:message-id;		h=from:to:subject:date:message-id;
	bh=YJAYwiNdc3wMh6TD8FjVhtmxaHYHo7Z/06kHQYvQ4tQ=;		bh=YJAYwiNdc3wMh6TD8FjVhtmxaHYHo7Z/06kHQYvQ4tQ=;
	b=jHF3tpgqr6nH/icHKIqFK2IJPtCLF0CRJaz2Hj1Y8yNwTJ		b=jHF3tpgqr6nH/icHKIqFK2IJPtCLF0CRJaz2Hj1Y8yNwTJ
	IMYIZtLccho3ymGF2GYqvTl2nP/cn4dH+55rH5pqkWNnuJ		IMYIZtLccho3ymGF2GYqvTl2nP/cn4dH+55rH5pqkWNnuJ
	R9z54CFcanoKKcl9wOZzK9i5KxM0DTzfs0r8		R9z54CFcanoKKcl9wOZzK9i5KxM0DTzfs0r8
	Example 1: DKIM-Signature field using this extension		Example 1: DKIM-Signature field using this extension
	skipping to change at page 22, line 36		skipping to change at page 21, line 36
	indicates reports are requested on verification failure.		indicates reports are requested on verification failure.
	Assuming the public key retrieved from the DNS and processed		Assuming the public key retrieved from the DNS and processed
	according to [DKIM] would determine that the signature is invalid, a		according to [DKIM] would determine that the signature is invalid, a
	TXT query will be sent to "_report._domainkey.example.com" to		TXT query will be sent to "_report._domainkey.example.com" to
	retrieve a reporting address and other report parameters as described		retrieve a reporting address and other report parameters as described
	in Section 3.3.		in Section 3.3.
	B.2. Example DKIM Reporting TXT Record		B.2. Example DKIM Reporting TXT Record
	An example DKIM Reporting TXT Record as defined by this memo:		An example DKIM Reporting TXT Record as defined by this document:
	ra=dkim-errors; rp=100; rr=v:x		ra=dkim-errors; rp=100; rr=v:x
	Example 2: Example DKIM Reporting TXT Record		Example 2: Example DKIM Reporting TXT Record
	This example, continuing from the previous one, shows a message that		This example, continuing from the previous one, shows a message that
	might be found at "_report._domainkey.example.com" in a TXT record.		might be found at "_report._domainkey.example.com" in a TXT record.
	It makes the following requests:		It makes the following requests:
	o Reports about signature evaluation failures should be send to the		o Reports about signature evaluation failures should be send to the
	address "dkim-errors" at the signer's domain;		address "dkim-errors" at the signer's domain;
	o All (100%) incidents should be reported;		o All (100%) incidents should be reported;
	o Only reports about signature verification failures and expired		o Only reports about signature verification failures and expired
	signatures should be generated.		signatures should be generated.
	B.3. Example Use of DKIM ADSP Extension Tags		B.3. Example Use of DKIM ADSP Extension Tags
	A DKIM ADSP record including use of the extensions defined by this		A DKIM ADSP record including use of the extensions defined by this
	memo:		document:
	dkim=all; ra=dkim-adsp-errors; rr=u		dkim=all; ra=dkim-adsp-errors; rr=u
	Example 3: DKIM ADSP record using these extensions		Example 3: DKIM ADSP record using these extensions
	This example ADSP record makes the following assertions:		This example ADSP record makes the following assertions:
	o The sending domain (i.e. the one that is advertising this policy)		o The sending domain (i.e. the one that is advertising this policy)
	signs all mail it sends;		signs all mail it sends;
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