draft-ietf-dmarc-eaiauth-03.txt   draft-ietf-dmarc-eaiauth-04.txt 
Network Working Group J. Levine Network Working Group J. Levine
Internet-Draft Taughannock Networks Internet-Draft Taughannock Networks
Updates: 6376, 7208, 7489 (if approved) February 27, 2019 Updates: 6376, 7208, 7489 (if approved) March 25, 2019
Intended status: Standards Track Intended status: Standards Track
Expires: August 31, 2019 Expires: September 26, 2019
E-mail Authentication for Internationalized Mail E-mail Authentication for Internationalized Mail
draft-ietf-dmarc-eaiauth-03 draft-ietf-dmarc-eaiauth-04
Abstract Abstract
SPF (RFC7208), DKIM (RFC6376), and DMARC (RFC7489) enable a domain SPF (RFC7208), DKIM (RFC6376), and DMARC (RFC7489) enable a domain
owner to publish e-mail authentication and policy information in the owner to publish e-mail authentication and policy information in the
DNS. In internationalized e-mail, domain names can occur both as DNS. In internationalized e-mail, domain names can occur both as
U-labels and A-labels. The Authentication-Results header reports the U-labels and A-labels. This specification updates the SPF, DKIM, and
result of authentication checks made with SPF, DKIM, DMARC, and other DMARC specifications to clarify which form of internationalized
schemes. This specification updates the SPF, DKIM, and DMARC domain names to use in those specifications.
specifications to clarify which form of internationalized domain
names to use in those specifications, and when creating
Authentication-Results headers.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 31, 2019. This Internet-Draft will expire on September 26, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 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
(https://trustee.ietf.org/license-info) in effect on the date of (https://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
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
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 . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. General principles . . . . . . . . . . . . . . . . . . . . . 3 3. General principles . . . . . . . . . . . . . . . . . . . . . 3
4. SPF and internationalized mail . . . . . . . . . . . . . . . 3 4. SPF and internationalized mail . . . . . . . . . . . . . . . 3
5. DKIM and internationalized mail . . . . . . . . . . . . . . . 4 5. DKIM and internationalized mail . . . . . . . . . . . . . . . 4
6. DMARC and internationalized mail . . . . . . . . . . . . . . 5 6. DMARC and internationalized mail . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Security Considerations . . . . . . . . . . . . . . . . . . . 5 8. Security Considerations . . . . . . . . . . . . . . . . . . . 5
9. Normative References . . . . . . . . . . . . . . . . . . . . 5 9. Normative References . . . . . . . . . . . . . . . . . . . . 5
Appendix A. Change history . . . . . . . . . . . . . . . . . . . 6 Appendix A. Change history . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
SPF [RFC7208], DKIM [RFC6376], and DMARC [RFC7489] enable a domain SPF [RFC7208], DKIM [RFC6376], and DMARC [RFC7489] enable a domain
owner to publish e-mail authentication and policy information in the owner to publish e-mail authentication and policy information in the
DNS. SPF primarily publishes information about what host addresses DNS. SPF primarily publishes information about what host addresses
are authorized to send mail for a domain. DKIM places cryptographic are authorized to send mail for a domain. DKIM places cryptographic
signatures on e-mail messages, with the validation keys published in signatures on e-mail messages, with the validation keys published in
the DNS. DMARC publishes policy information related to the domain in the DNS. DMARC publishes policy information related to the domain in
the From: header of e-mail messages. the From: header of e-mail messages.
In conventional e-mail, all domain names are ASCII in all contexts so In conventional e-mail, all domain names are ASCII in all contexts so
there is no question about the representation of the domain names. there is no question about the representation of the domain names.
All internationalized domain names are represented as A-labels All internationalized domain names are represented as A-labels
[RFC5890] in unencoded message bodies, in SMTP sessions, and in the [RFC5890] in message headers, in SMTP sessions, and in the DNS.
DNS. Internationalized mail [RFC6530] allows U-labels in SMTP Internationalized mail [RFC6530] allows U-labels in SMTP sessions
sessions [RFC6531] and in message headers [RFC6532]. [RFC6531] and in message headers [RFC6532].
Every U-label is equivalent to an A-label, so in principle the choice Every U-label is equivalent to an A-label, so in principle the choice
of label format should not cause any ambiguities. But in practice, of label format should not cause any ambiguities. But in practice,
consistent use of label formats will make it more likely that mail consistent use of label formats will make it more likely that mail
senders' and receivers' code interoperates. senders' and receivers' code interoperates.
Internationalized mail also allows UTF-8 characters in the local Internationalized mail also allows UTF-8 encoded Unicode characters
parts of mailbox names, which were historically only ASCII. in the local parts of mailbox names, which were historically only
ASCII.
2. Definitions 2. Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] and [RFC8174]. when they appear in all capitals, as 14 [RFC2119] and [RFC8174]. when they appear in all capitals, as
shown here. shown here.
The term IDN, for Internationalized Domain Name, refers to a domain The term IDN, for Internationalized Domain Name, refers to a domain
skipping to change at page 4, line 14 skipping to change at page 4, line 12
U-labels in domains, there is no way to rewrite non-ASCII local parts U-labels in domains, there is no way to rewrite non-ASCII local parts
into ASCII.) into ASCII.)
5. DKIM and internationalized mail 5. DKIM and internationalized mail
DKIM [RFC6376] specifies a message header that contains a DKIM [RFC6376] specifies a message header that contains a
cryptographic message signature and a DNS record that contains the cryptographic message signature and a DNS record that contains the
validation key. validation key.
Section 2.11 of [RFC6376] defines dkim-quoted-printable. Its Section 2.11 of [RFC6376] defines dkim-quoted-printable. Its
definition is modified in internationalized messages so that non- definition is modified in messages with internationalized headers so
ASCII UTF-8 characters need not be quoted. The ABNF for dkim-safe- that non-ASCII UTF-8 characters need not be quoted. The ABNF for
char in internationalized messages is replaced by the following, dkim-safe-char in those messages is replaced by the following, adding
adding non-ASCII UTF-8 characters from [RFC3629]: non-ASCII UTF-8 characters from [RFC3629]:
dkim-safe-char = %x21-3A / %x3C / %x3E-7E / dkim-safe-char = %x21-3A / %x3C / %x3E-7E /
UTF8-2 / UTF8-3 / UTF8-4 UTF8-2 / UTF8-3 / UTF8-4
; '!' - ':', '<', '>' - '~', non-ASCII ; '!' - ':', '<', '>' - '~', non-ASCII
UTF8-2 = <Defined in Section 4 of RFC 3629> UTF8-2 = <Defined in Section 4 of RFC 3629>
UTF8-3 = <Defined in Section 4 of RFC 3629> UTF8-3 = <Defined in Section 4 of RFC 3629>
UTF8-4 = <Defined in Section 4 of RFC 3629> UTF8-4 = <Defined in Section 4 of RFC 3629>
Section 3.5 of [RFC6376] states that IDNs in the d=, i=, and s= tags Section 3.5 of [RFC6376] states that IDNs in the d=, i=, and s= tags
of a DKIM-Signature header MUST be encoded as A-labels. This rule is of a DKIM-Signature header MUST be encoded as A-labels. This rule is
relaxed only for headers in internationalized messages [RFC6532] so relaxed only for internationalized messages headers [RFC6532] so IDNs
IDNs SHOULD be represented as U-labels but MAY be A-labels. This SHOULD be represented as U-labels but MAY be A-labels. This provides
provides improved consistency with other headers. The set of improved consistency with other headers. The set of allowable
allowable characters in the local-part of an i= tag is extended as characters in the local-part of an i= tag is extended as described in
described in [RFC6532]. When computing or verifying the hash in a [RFC6532]. When computing or verifying the hash in a DKIM signature
DKIM signature as described in section 3.7, the hash MUST use the as described in section 3.7, the hash MUST use the domain name in the
domain name in the format it occurs in the header. format it occurs in the header.
Section 3.4.2 of [RFC6376] describes relaxed header canonicalization. Section 3.4.2 of [RFC6376] describes relaxed header canonicalization.
Its first step converts all header field names from upper case to Its first step converts all header field names from upper case to
lower case. Field names are restricted to printable ASCII (see lower case. Field names are restricted to printable ASCII (see
[RFC5322] section 3.6.8) so this case conversion remains the usual [RFC5322] section 3.6.8) so this case conversion remains the usual
ASCII conversion. ASCII conversion.
DKIM key records, described in section 3.6.1, do not contain domain DKIM key records, described in section 3.6.1, do not contain domain
names, so there is no change to their specification. names, so there is no change to their specification.
skipping to change at page 5, line 31 skipping to change at page 5, line 23
internationalized addresses. internationalized addresses.
7. IANA Considerations 7. IANA Considerations
This document makes no request of IANA. This document makes no request of IANA.
8. Security Considerations 8. Security Considerations
E-mail is subject to a vast range of threats and abuses. This E-mail is subject to a vast range of threats and abuses. This
document attempts to slightly mitigate some of them but does not, as document attempts to slightly mitigate some of them but does not, as
far as the author knows, add any new ones. far as the author knows, add any new ones. The updates to SPF, DKIM,
and DMARC are intended to allow the respective specifications work as
reliably on internationalized mail as they do on ASCII mail, so that
applications that use them, such as some kinds of spam and phish
filtering, can work more reliably on internationalized mail.
9. Normative References 9. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
skipping to change at page 6, line 43 skipping to change at page 6, line 43
Message Authentication, Reporting, and Conformance Message Authentication, Reporting, and Conformance
(DMARC)", RFC 7489, DOI 10.17487/RFC7489, March 2015, (DMARC)", RFC 7489, DOI 10.17487/RFC7489, March 2015,
<https://www.rfc-editor.org/info/rfc7489>. <https://www.rfc-editor.org/info/rfc7489>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
Appendix A. Change history Appendix A. Change history
03 to 04 remove dangling A-R reference, add more i18nish and
security goodness
02 to 03 minor edits per Alexey 02 to 03 minor edits per Alexey
01 to 02 update references 01 to 02 update references
00 to 01 Relaxed canon, Typos 00 to 01 Relaxed canon, Typos
00 First WG version 00 First WG version
Author's Address Author's Address
John Levine John Levine
Taughannock Networks Taughannock Networks
PO Box 727 PO Box 727
Trumansburg, NY 14886 Trumansburg, NY 14886
Phone: +1 831 480 2300
Email: standards@taugh.com Email: standards@taugh.com
URI: http://jl.ly URI: http://jl.ly
 End of changes. 14 change blocks. 
30 lines changed or deleted 34 lines changed or added

This html diff was produced by rfcdiff 1.47. The latest version is available from http://tools.ietf.org/tools/rfcdiff/