Internet DRAFT - draft-melnikov-iana-reg-cd-encapsulated
draft-melnikov-iana-reg-cd-encapsulated
Network Working Group A. Melnikov
Internet-Draft Isode Ltd
Intended status: Informational B. Hoeneisen
Expires: 17 August 2023 pEp Foundation
13 February 2023
IANA Registration of Content-Disposition Header Field value
'encapsulated'
draft-melnikov-iana-reg-cd-encapsulated-00
Abstract
This document defines a new Content-Disposition header field value
"encapsulated" to be used with "message/rfc822" and "message/global"
media types. Content-Disposition "encapsulated" signals that
enclosed message should be presented inline, instead of being
presented as a forwarded message. One use case for this is for S/
MIME header protection.
About This Document
This note is to be removed before publishing as an RFC.
Status information for this document may be found at
https://datatracker.ietf.org/doc/draft-melnikov-iana-reg-cd-
encapsulated/.
Discussion of this document takes place on the dispatch non-WG
mailing list (mailto:dispatch@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/browse/dispatch/.
Source for this draft and an issue tracker can be found at
https://gitea.pep.foundation/pEp.foundation/internet-drafts.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
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Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on 17 August 2023.
Copyright Notice
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Implementations . . . . . . . . . . . . . . . . . . . . . 3
1.3. Requirements Language . . . . . . . . . . . . . . . . . . 3
1.4. Terms . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Specification . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. Privacy Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . 6
Appendix A. Document Changelog . . . . . . . . . . . . . . . . . 7
Appendix B. Open Issues . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
This document defines a new Content-Disposition header field
[RFC2183] value "encapsulated" to be used with "message/rfc822"
[RFC2046] and "message/global" [RFC6532] media types. The value
"encapsulated" is meaningful when used within S/MIME or PGP/MIME
signed or encrypted body parts (e.g., as specified in
[I-D.ietf-lamps-header-protection] for S/MIME). Absence of Content-
Disposition header field (or presence of any value other than
"encapsulated") when Content-Type is "message/rfc822" or "message/
global" means that the message nested inside "message/rfc822" (or
"message/global") is a simple forwarded message. Presence of
"Content-Disposition: encapsulated" means that encapsulation is used
for header protection, but otherwise the message should be displayed
inline.
1.1. Use Cases
Two use cases have been discovered so far:
1. This Content-Disposition value indicates whether a nested message
is signed and/or encrypted (S/MIME or PGP/MIME), which tells the
receiving side how to display the message to the user.
Currently, many email clients display "weird artefacts" to users
due to this missing information.
2. This Content-Disposition values indicates to mailing lists which
signed and/or encrypted (S/MIME or PGP/MIME) email messages are
forwarded, and which are just encapsulated for the purpose of
header protection, and how to handle these respective messages.
1.2. Implementations
At this time, the following email systems are known to use this
Content-Disposition header field value:
1. Isode Harrier Web Server with S/MIME [RFC8551] support
1.3. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
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1.4. Terms
The following terms are defined for the scope of this document:
* Header Field (HF): cf. [RFC5322]
* Header Section (HS): cf. [RFC5322]
2. Specification
This section defines the new "encapsulated" Content-Disposition
header field value.
An implementation that supports Content-Disposition header field as
defined in [RFC2183], but doesn't support this specification will
interpret "encapsulated" in the same way as the value "attachment"
(as per requirements in [RFC2183]).
An implementation that supports this specification uses the Content-
Disposition value "encapsulated" with Content-Type "message/rfc822"
or "message/global" to signal that the message is encapsulated for
header protection (cf. [I-D.ietf-lamps-header-protection]).
Presence of Content-Disposition "encapsulated" with any other
Content-Type should be treated in the same way as the Content-
Disposition value "inline".
3. Example
The following example shows the usage of the Content-Disposition
header field value "encapsulated" for an email message that is not
forwarded, but encapsulated in another email message.
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Date: Mon, 25 Sep 2017 17:31:42 +0100 (GMT Daylight Time)
Message-ID: <e4a483cb-1dfb-481d-903b-298c92c21f5e@matt.example.net>
Subject: Meeting at my place
From: "Alexey Melnikov" <alexey.melnikov@example.net>
MIME-Version: 1.0
Content-Type: multipart/signed; charset=us-ascii; micalg=sha1;
protocol="application/pkcs7-signature";
boundary=.cbe16d2a-e1a3-4220-b821-38348fc97237
This is a multipart message in MIME format.
--.cbe16d2a-e1a3-4220-b821-38348fc97237
Content-Type: message/rfc822
Content-Disposition: encapsulated
Date: Mon, 25 Sep 2017 17:31:42 +0100 (GMT Daylight Time)
From: "Alexey Melnikov" <alexey.melnikov@example.net>
Message-ID: <e4a483cb-1dfb-481d-903b-298c92c21f5e@matt.example.net>
MIME-Version: 1.0
MMHS-Primary-Precedence: 3
Subject: Meeting at my place
To: somebody@example.net
X-Mailer: Example Mailer
Content-Type: text/plain; charset=us-ascii
This is an important message that I don't want to be modified.
--.cbe16d2a-e1a3-4220-b821-38348fc97237
Content-Transfer-Encoding: base64
Content-Type: application/pkcs7-signature
[[base-64 encoded signature]]
--.cbe16d2a-e1a3-4220-b821-38348fc97237--
4. Security Considerations
This document does not define a new protocol, and thus does not
create new security concerns in and of itself.
5. Privacy Considerations
This document does not introduce any new issues regarding Privacy.
6. IANA Considerations
This document requests IANA to register the Content-Disposition
header field value [RFC2183] "encapsulated" with the reference [RFC
THIS].
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[[ RFC Editor: Replace [RFC THIS] with the number of this RFC before
publication. ]]
7. Acknowledgments
The authors would like to thank the following people who have
provided helpful comments and suggestions for this document: David
Wilson, Kelly Bristol, Krista Bennett, Robert Williams, Steve Kille,
and Wei Chuang.
8. References
8.1. Normative References
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046,
DOI 10.17487/RFC2046, November 1996,
<https://www.rfc-editor.org/info/rfc2046>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2183] Troost, R., Dorner, S., and K. Moore, Ed., "Communicating
Presentation Information in Internet Messages: The
Content-Disposition Header Field", RFC 2183,
DOI 10.17487/RFC2183, August 1997,
<https://www.rfc-editor.org/info/rfc2183>.
[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322,
DOI 10.17487/RFC5322, October 2008,
<https://www.rfc-editor.org/info/rfc5322>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8551] Schaad, J., Ramsdell, B., and S. Turner, "Secure/
Multipurpose Internet Mail Extensions (S/MIME) Version 4.0
Message Specification", RFC 8551, DOI 10.17487/RFC8551,
April 2019, <https://www.rfc-editor.org/info/rfc8551>.
8.2. Informative References
[I-D.ietf-lamps-header-protection]
Gillmor, D. K., Hoeneisen, B., and A. Melnikov, "Header
Protection for S/MIME", Work in Progress, Internet-Draft,
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draft-ietf-lamps-header-protection-11, 24 January 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-lamps-
header-protection-11>.
[RFC6532] Yang, A., Steele, S., and N. Freed, "Internationalized
Email Headers", RFC 6532, DOI 10.17487/RFC6532, February
2012, <https://www.rfc-editor.org/info/rfc6532>.
Appendix A. Document Changelog
[[ RFC Editor: This section is to be removed before publication ]]
* draft-melnikov-iana-reg-cd-encapsulated-00
- Renamed document
- Replaced Content-Type forwarded parameter with Content-
Disposition "encapsulated"
* draft-melnikov-iana-reg-forwarded-00
- Initial version derived from draft-ietf-lamps-header-
protection-requirements-01
Appendix B. Open Issues
[[ RFC Editor: This section should be empty and is to be removed
before publication. ]]
Authors' Addresses
Alexey Melnikov
Isode Ltd
14 Castle Mews
Hampton, Middlesex
TW12 2NP
United Kingdom
Email: alexey.melnikov@isode.com
Bernie Hoeneisen
pEp Foundation
Oberer Graben 4
CH- 8400 Winterthur
Switzerland
Email: bernie.hoeneisen@pep.foundation
URI: https://pep.foundation/
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