Network Working Group A. Melnikov
Internet-Draft Isode Ltd
Intended status: Informational G. Lunt
Expires: April 24, 2012 SMHS Ltd
October 22, 2011
Registration of Military Message Handling System (MMHS) header fields
for use in Internet Mail
draft-melnikov-mmhs-header-fields-05
Abstract
A Miltary Message Handling System (MMHS) processes formal messages
ensuring release, distribution, security, and timely delivery across
national and international strategic and tactical networks. The MMHS
Elements of Service are defined as a set of extensions to the ITU-T
X.400 (1992) international standards and are specified in STANAG 4406
Edition 2 or ACP 123. This document specifies message header fields
and associated processing for RFC 5322 (Internet Email) to provide a
comparable messaging service. In addition, this document provides
for a STANAG 4406 / Internet Email Gateway that supports message
conversion.
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 http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 24, 2012.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
3. Registration Templates . . . . . . . . . . . . . . . . . . . . 3
3.1. Header field: MMHS-Exempted-Address . . . . . . . . . . . 5
3.2. Header field: MMHS-Extended-Authorisation-Info . . . . . . 5
3.3. Header field: MMHS-Subject-Indicator-Codes . . . . . . . . 6
3.4. Header field: MMHS-Handling-Instructions . . . . . . . . . 6
3.5. Header field: MMHS-Message-Instructions . . . . . . . . . 7
3.6. Header field: MMHS-Codress-Message-Indicator . . . . . . . 7
3.7. Header field: MMHS-Originator-Reference . . . . . . . . . 8
3.8. Header field: MMHS-Primary-Precedence . . . . . . . . . . 8
3.9. Header field: MMHS-Copy-Precedence . . . . . . . . . . . . 9
3.10. Header field: MMHS-Message-Type . . . . . . . . . . . . . 10
3.11. Header field: MMHS-Other-Recipients-Indicator-To . . . . . 11
3.12. Header field: MMHS-Other-Recipients-Indicator-Cc . . . . . 11
3.13. Header field: MMHS-Acp127-Message-Identifier . . . . . . . 12
3.14. Header field: MMHS-Originator-PLAD . . . . . . . . . . . . 13
4. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 13
5. Service in Comparison to ACP 123/STANAG 4406 . . . . . . . . . 15
6. Gatewaying with ACP 123/STANAG 4406 . . . . . . . . . . . . . 16
7. Gatewaying with ACP 127 . . . . . . . . . . . . . . . . . . . 17
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
9. Security Considerations . . . . . . . . . . . . . . . . . . . 17
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
10.1. Normative References . . . . . . . . . . . . . . . . . . . 17
10.2. Informative References . . . . . . . . . . . . . . . . . . 18
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 18
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1. Introduction
[RFC5322] defines a protocol for the format of electronic messages
exchanged on the Internet. MMHS is a military specification defined
in ACP 123 [ACP123] (also specified in STANAG 4406 [STANAG-4406])
which defines a number of extensions to the basic X.400 (1992)
protocol for the services required by military messaging.
This document supports translating most of the elements of service
defined in ACP 123 [ACP123] to Internet message header fields. This
specification is written to extend the MIXER specification [RFC2156]
to enable inter-conversion in a MIXER gateway with the X.400 IPMS
heading extensions defined in STANAG 4406 Annex A.
The document is aimed at the ability to represent MMHS messages in
RFC 5322. All RFC 5322 header fields defined in this document are
prefixed with the string "MMHS-" to distinguish them from any other
header fields.
This document is structured as follows: Section 3 and its subsections
formally define new Internet header fields and show some examples.
Section 4 provides ABNF syntax for them. Section 5 provides some
background information about which features of ACP 123/STANAG 4406
were not implemented in this specification. Subsequent sections talk
about additional requirements for gatewaying to/from ACP 123/STANAG
4406 and ACP 127 environments respectively.
2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
The formal syntax uses the Augmented Backus-Naur Form (ABNF)
[RFC5234] notation including the core rules defined in Appendix B of
RFC 5234 [RFC5234].
3. Registration Templates
Header field entries are summarized below in tabular form for
convenience of reference and presented in full in the following
subsections.
Any header field specified in this document MUST NOT appear more than
once in message headers.
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+------------------------------------+----------+-------------------+
| Header name | Protocol | Reference |
+------------------------------------+----------+-------------------+
| MMHS-Exempted-Address | mail | [ACP123], |
| | | Appendix A1.1 and |
| | | Appendix B.105 |
| MMHS-Extended-Authorisation-Info | mail | [ACP123], |
| | | Appendix A1.2 and |
| | | Appendix B.106 |
| MMHS-Subject-Indicator-Codes | mail | [ACP123], |
| | | Appendix A1.3 and |
| | | Appendix B.107 |
| MMHS-Handling-Instructions | mail | [ACP123][ACP123], |
| | | Appendix A1.4 and |
| | | Appendix B.108 |
| MMHS-Message-Instructions | mail | [ACP123], |
| | | Appendix A1.5 and |
| | | Appendix B.109 |
| MMHS-Codress-Message-Indicator | mail | [ACP123], |
| | | Appendix A1.6 and |
| | | Appendix B.110 |
| MMHS-Originator-Reference | mail | [ACP123], |
| | | Appendix A1.7 and |
| | | Appendix B.111 |
| MMHS-Primary-Precedence | mail | [ACP123], |
| | | Appendix A1.8 and |
| | | Appendix B.101 |
| MMHS-Copy-Precedence | mail | [ACP123], |
| | | Appendix A1.9 and |
| | | Appendix B.102 |
| MMHS-Message-Type | mail | [ACP123], |
| | | Appendix A1.10 |
| | | and Appendix |
| | | B.103 |
| MMHS-Other-Recipients-Indicator-To | mail | [ACP123], |
| | | Appendix A1.12 |
| | | and Appendix |
| | | B.113 |
| MMHS-Other-Recipients-Indicator-Cc | mail | [ACP123], |
| | | Appendix A1.12 |
| | | and Appendix |
| | | B.113 |
| MMHS-Acp127-Message-Identifier | mail | [ACP123], |
| | | Appendix A1.14 |
| | | and Appendix |
| | | B.116 |
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| MMHS-Originator-PLAD | mail | [ACP123], |
| | | Appendix A1.15 |
| | | and Appendix |
| | | B.117 |
+------------------------------------+----------+-------------------+
3.1. Header field: MMHS-Exempted-Address
Applicable protocol: mail [RFC5322]
Status: informational
Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
Specification document(s): [[anchor4: this document]]
The exempted address header field, by its presence, indicates the
addresses of members in an Address List (AL) that should not receive
the message. If this extension is absent from the Extensions heading
field, all members of an AL will be considered to be valid recipients
of the message. Note: There is no guarantee that the exempted
addresses will not receive the message as the result of redirection,
Distribution List (DL) expansion, etc.
Example:
MMHS-Exempted-Address: UK SHL CGT Samuals G
<graham.samuals@shl.example.com>, UK SHL Duty Officer
<duty@shl.example.com>
3.2. Header field: MMHS-Extended-Authorisation-Info
Applicable protocol: mail [RFC5322]
Status: informational
Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
Specification document(s): [[anchor6: this document]]
The extended authorisation info header field, by its presence
indicates either the date and the time when the message was
officially released by the releasing officer or the date and time
when the message was initially submitted to a communication facility
for transmission.
This header field SHOULD always be present in an email message which
complies with this specification.
Example:
MMHS-Extended-Authorisation-Info:
Mon, 09 Aug 2010 15:27:40 +0100
The example above demonstrates use of folding white space (FWS
[RFC5322]).
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3.3. Header field: MMHS-Subject-Indicator-Codes
Applicable protocol: mail [RFC5322]
Status: informational
Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
Specification document(s): [[anchor8: this document]]
Subject Indicator Codes (SICs) are a mechanism for formally
identifying the topic of a message. SICs are nested codes that
provide information for message distribution after delivery to the
recipient organisation. SIC codes are usually three letters or three
letters and digits, but may be up to 8 characters long. Nations and
organizations using SIC codes usually maintain a central registry.
When present a MMHS-Subject-Indicator-Codes header field contains one
or more SICs, which indicates distribution information to a recipient
or a recipient's User Agent. This information can be used to perform
automatic or manual local distribution of a message. If the MMHS-
Subject-Indicator-Codes header field is absent, then the local
distribution will be in accordance with the message handling policy
of the recipient's domain.
[ACP123] specifies two optional components of the Distribution Code
Element of Service. The MMHS-Subject-Indicator-Codes header field
covers only the SIC code variant of distribution codes.
Example:
MMHS-Subject-Indicator-Codes: SDM; KKZ ; BRL
The example above includes 3 SIC codes: "SDM" (GROUND/LAND
REQUIREMENTS), "KKZ" (HELICOPTER PUBLICATIONS/MANUALS) and "BRL"
(HILEX INCIDENTS).
3.4. Header field: MMHS-Handling-Instructions
Applicable protocol: mail [RFC5322]
Status: informational
Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
Specification document(s): [[anchor10: this document]]
The handling instructions header field, by its presence indicates
human readable local handling instructions that requires some manual
handling by a traffic operator. If this header field is absent the
message will be considered as not requiring manual handling by a
traffic operator.
Handling instructions (also called transmission instructions) are a
part of format line 4 as defined in ACP 127 [ACP127], and concern the
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sending of the message, e.g. that a particular system shall be used
for transfer of the message.
This header field is used to support interoperability with ACP 127
systems.
Example:
MMHS-Handling-Instructions: RXFPA ZOV MINDEF
The example above includes one ACP 131(F) handling instruction:
"RXFPA ZOV MINDEF". The "ZOV MINDEF" indicates that MINDEF rerouted
the message for some reason, and the correct routing is via RXFPA.
3.5. Header field: MMHS-Message-Instructions
Applicable protocol: mail [RFC5322]
Status: informational
Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
Specification document(s): [[anchor12: this document]]
The message instructions header field, by its presence indicates
message instructions accompanying the message (e.g., similar to the
operating signals specified in ACP 131 [ACP131]). If this header
field is absent the message will be considered received without
message instructions.
The difference between Handling instructions and Message instructions
is that the former is only for manual handling by traffic operators,
while the latter also contains information of interest to the persons
reading the message.
Example:
MMHS-Message-Instructions: MINIMIZE CONSIDERED; NO DISTRIBUTION
The example above includes 2 ACP123(B) [ACP123] defined message
instructions: "MINIMIZE CONSIDERED" indicating that the originating
user has considered the Minimize status of the recipients and "NO
DISTRIBUTION", indicating that the recipients should not distribute
the message further without the originating user's approval.
3.6. Header field: MMHS-Codress-Message-Indicator
Applicable protocol: mail [RFC5322]
Status: informational
Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
Specification document(s): [[anchor14: this document]]
The codress message indicator header field, by its presence indicates
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that the message is in Codress format. If this header field is
absent the message will be considered received without the Codress
format.
A Codress message is one in which all addresses, i.e. the sender and
all recipients, is encrypted within the ACP 127 text (body). The
heading of any Codress message contains only the minimum of
information which will enable a receiving station to deal properly
and expeditiously with the particular transmission. The general
rules for the preparation and transmission of Codress messages are
given in ACP 121 [ACP121].
This header field is used only to support interoperability with ACP
127 systems.
Example:
MMHS-Codress-Message-Indicator: 23
3.7. Header field: MMHS-Originator-Reference
Applicable protocol: mail [RFC5322]
Status: informational
Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
Specification document(s): [[anchor16: this document]]
The originator reference header field, by its presence indicates a
user defined reference called the "originator's number". If this
header field is absent, then the message will be considered received
without any user defined reference.
The "originator's number" is used by the originating organisational
unit and is further qualified within national policy.
Note: trailing and leading spaces in an originator reference are not
allowed by syntax.
Example:
MMHS-Originator-Reference: IMSCOM-JIC-612-78
3.8. Header field: MMHS-Primary-Precedence
Applicable protocol: mail [RFC5322]
Status: informational
Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
Specification document(s): [[anchor18: this document]]
The primary precedence header field, by its presence indicates the
precedence level of the primary ("action") recipients. The message
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originating domain MUST ensure that this header field is always
present if the message contains "To:" ("action") addresses.
The MMHS Primary Precedence Element of Service indicates the relative
order in which Military Messages are to be handled for primary
(action) recipients, i.e. a Military Message with higher MMHS-
Primary-Precedence header field value SHOULD be handled before a
Military Message with a lower MMHS-Primary-Precedence header field
value.
The header field value is a non-negative integer, or one of the 6
predefined case-insensitive labels: "deferred" (same as "0"),
"routine" (same as "1"), "priority" (same as "2"), "immediate" (same
as "3"), "flash" (same as "4"), or "override" (same as "5"),
optionally followed by a comment. Note that according to ACP 123
values in the range from 0 to 15 are reserved for NATO defined
precedence levels and values in the range from 16 to 31 are reserved
for national users.
Example 1:
MMHS-Primary-Precedence: 0 (Deferred)
Example 2:
MMHS-Primary-Precedence: FLASH
Example 3:
MMHS-Primary-Precedence: 7
3.9. Header field: MMHS-Copy-Precedence
Applicable protocol: mail [RFC5322]
Status: informational
Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
Specification document(s): [[anchor20: this document]]
The copy precedence header field by its presence indicates the
precedence level of the copy ("information") recipients. The message
originating domain MUST ensure that this header field is always
present if the message contains "Cc:" or "Bcc:" ("information")
addresses.
The MMHS Copy Precedence Element of Service indicates the relative
order in which Military Messages are to be handled for copy
(information) recipients. i.e. a Military Message with higher MMHS-
Copy-Precedence header field value SHOULD be handled before a
Military Message with a lower MMHS-Copy-Precedence header field
value.
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The header field value is a non-negative integer, or one of the 6
predefined case-insensitive labels: "deferred" (same as "0"),
"routine" (same as "1"), "priority" (same as "2"), "immediate" (same
as "3"), "flash" (same as "4"), or "override" (same as "5"),
optionally followed by a comment. Note that according to ACP 123
values in the range from 0 to 15 are reserved for NATO defined
precedence levels and values in the range from 16 to 31 are reserved
for national users.
Example 1:
MMHS-Copy-Precedence: 2 (priority)
Example 2:
MMHS-Copy-Precedence: Priority
3.10. Header field: MMHS-Message-Type
Applicable protocol: mail [RFC5322]
Status: informational
Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
Specification document(s): [[anchor22: this document]]
The message type heading extension, by its presence indicates whether
the message is to be considered as an exercise, an operation, a
project or a drill. (Note that the list of types is extensible and
other types can be specified using the numeric form, see below.) It
may include an optional parameter specifying the name of the
exercise, operation, project or drill. If this extension is absent
the message will be considered to be of an undefined type.
The header field value is a non-negative integer, or one of the 4
predefined case-insensitive labels: "exercise" (same as "0"),
"operation" (same as "1"), "project" (same as "2"), "drill" (same as
"3"). Note that according to ACP 123 values in the range from 0 to
127 are reserved for NATO defined Message Type identifiers and values
in the range from 128 to 255 are not defined by NATO and may be used
nationally or bilaterally.
Example 1:
MMHS-Message-Type: 0(exercise); identifier="CANDLE FISH"
Example 2:
MMHS-Message-Type: 3
Example 3:
MMHS-Message-Type: 2 (projet)
Example 4:
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MMHS-Message-Type: project
Note that some of the examples above demonstrate use of optional
comments. See Section 4 for the exact syntax of this header field.
3.11. Header field: MMHS-Other-Recipients-Indicator-To
Applicable protocol: mail [RFC5322]
Status: informational
Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
Specification document(s): [[anchor24: this document]]
The other primary recipients indicator header field, by its presence
indicates the names of primary recipients that are intended to
receive or have received the message via means other than MMHS. The
absence of this element does not guarantee that all recipients are
within the MMHS.
This MMHS Element of Service enables an MMHS recipient to determine
all recipients of a Military Message. There are several reasons as
to why a recipient of a Military Message may be identified by this
header:
1. The recipient is not part of the MMHS
2. The path to the recipient through the MMHS may not be secure,
therefore, the originator has used alternative mechanisms to
distribute the Military Message
3. The recipient was already in receipt of the Military Message
prior to it being inserted into the MMHS
Example:
MMHS-Other-Recipients-Indicator-To: UK SHL COS; UK SHL IM
The example above includes names of 2 primary recipients which
received the message via means other than MMHS.
3.12. Header field: MMHS-Other-Recipients-Indicator-Cc
Applicable protocol: mail [RFC5322]
Status: informational
Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
Specification document(s): [[anchor26: this document]]
The other copy recipients indicator header field, by its presence
indicates the names of copy recipients that are intended to receive
or have received the message via means other than MMHS. The absence
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of this element does not guarantee that all recipients are within the
MMHS.
This MMHS Element of Service enables an MMHS recipient to determine
all recipients of a Military Message. There are several reasons as
to why a recipient of a Military Message may be identified by this
header:
1. The recipient is not part of the MMHS
2. The path to the recipient through the MMHS may not be secure,
therefore, the originator has used alternative mechanisms to
distribute the Military Message
3. The recipient was already in receipt of the Military Message
prior to it being inserted into the MMHS
Example:
MMHS-Other-Recipients-Indicator-Cc: UK SHL LEGAD
The example above includes 1 copy (information) recipient which
received the message via means other than MMHS.
3.13. Header field: MMHS-Acp127-Message-Identifier
Applicable protocol: mail [RFC5322]
Status: informational
Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
Specification document(s): [[anchor28: this document]]
The ACP127 message identifier header field, by its presence indicates
an ACP 127 message identifier [ACP127] for a message that originated
from an ACP 127 domain. If this extension is absent, then the
message did not encounter an ACP 127 domain.
The acp127-message-identifier contains the contents of ACP127 format
line 3 consisting of three space (SP) separated fields: the Calling
Station (DERI), Station Serial Number (SSN), and Filing Time (JFT)
[ACP127].
This header field is used only to support interoperability with ACP
127 systems, it should be treated as opaque by a pure MMHS system.
Example:
MMHS-Acp127-Message-Identifier: RPDLE 1234 0341215
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3.14. Header field: MMHS-Originator-PLAD
Applicable protocol: mail [RFC5322]
Status: informational
Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
Specification document(s): [[anchor30: this document]]
The originator Plain Language Address Designators (PLAD) header
field, by its presence indicates the plain language address
associated with an originator for cross-reference purposes. If this
header field is absent, then the message will be considered to not
having an originators PLAD cross reference between the MMHS and ACP
127 domains.
This header field is used only to support interoperability with ACP
127 systems.
This header field and the Extended Authorisation Info header field
provide a cross-reference for message identification in both ACP 127
and MMHS domains.
Example:
MMHS-Originator-PLAD: SACLANT
4. Formal Syntax
The following syntax specification uses the Augmented Backus-Naur
Form (ABNF) as described in [RFC5234]. Terms not defined here are
taken from [RFC5322], [RFC5234] and [RFC2156].
NZ-DIGIT = %x31-39
; "1".."9"
nonneg-integer = "0" / (NZ-DIGIT *DIGIT)
military-string = 1*69( ps-char )
quoted-military-string = DQUOTE military-string DQUOTE
military-string-sequence = military-string
*( [FWS] ";" [FWS] military-string )
Exempted-Address = "MMHS-Exempted-Address:"
[FWS] address-list [FWS] CRLF
Extended-Authorisation-Info = "MMHS-Extended-Authorisation-Info:"
[FWS] date-time CRLF
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Subject-Indicator-Codes = "MMHS-Subject-Indicator-Codes:"
[FWS] sic-sequence [FWS] CRLF
sic-sequence = sic *( [FWS] ";" [FWS] sic )
; ACP 123 specifies that the maximum number of
; SICs is 8. Use of more than 8 SIC codes is
; permitted, but additional SIC codes might not
; be transferred to ACP 123 system.
sic = 3*8( ps-char )
Handling-Instructions = "MMHS-Handling-Instructions:"
[FWS] military-string-sequence [FWS] CRLF
Message-Instructions = "MMHS-Message-Instructions:"
[FWS] military-string-sequence [FWS] CRLF
Codress-Message-Indicator = "MMHS-Codress-Message-Indicator:"
[FWS] nonneg-integer [FWS] CRLF
Originator-Reference = "MMHS-Originator-Reference:"
[FWS] military-string [FWS] CRLF
PrimaryPrecedence = "MMHS-Primary-Precedence:" [FWS] precedence CRLF
CopyPrecedence = "MMHS-Copy-Precedence:" [FWS] precedence CRLF
precedence = (nonneg-integer / std-precedence) [CFWS]
std-precedence = "deferred" / "routine" / "priority" /
"immediate" / "flash" / "override"
; deferred == 0
; routine == 1
; priority == 2
; immediate == 3
; flash == 4
; override == 5
MessageType = "MMHS-Message-Type:" [FWS] message-type [CFWS]
[";" [FWS] MessageTypeParam [FWS] ] CRLF
message-type = nonneg-integer / std-message-type
std-message-type = "exercise" / "operation" / "project" / "drill"
; exercise == 0
; operation == 1
; project == 2
; drill == 3
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MessageTypeParam = "identifier" [FWS] "=" [FWS]
quoted-military-string
Designator = military-string
OtherRecipIndicatorPrimary = "MMHS-Other-Recipients-Indicator-To:"
[FWS] Designator *([FWS] ";" [FWS] Designator)
[FWS] CRLF
OtherRecipIndicatorCopy = "MMHS-Other-Recipients-Indicator-Cc:"
[FWS] Designator *([FWS] ";" [FWS] Designator)
[FWS] CRLF
Acp127MessageIdentifier = "MMHS-Acp127-Message-Identifier:"
[FWS] military-string [FWS] CRLF
OriginatorPLAD = "MMHS-Originator-PLAD:" [FWS] military-string [FWS]
CRLF
address-list = <Defined in RFC 5322>
5. Service in Comparison to ACP 123/STANAG 4406
The service specified in this document is a subset of the
functionality set out in Annex A1 "Military Heading Extensions" of
[ACP123]. The majority of this functionality is supported in this
document. A few capabilities have been left out which would have
significantly increased the complexity of this specification.
For Distribution Codes (A.1.3) only Subject Indicator Codes are
supported and Distribution Extensions are omitted. Authors of this
document believe that distribution extensions are not widely used.
Address List Indication (A.1.11) is not supported. This complex
extension is deprecated in [ACP123].
Pilot Forwarding Information (A.1.13) is not supported.
Security Information Labels (A.1.16) is not supported. This
extension is deprecated in favour of Annex A, which uses ESS Labels
[RFC2634] which can be supported in a directly compatible manner in
S/MIME [RFC5751].
ACP 127 Notification Requests (A.2.1) and Responses (A.3.1) are not
supported. These extensions are used to request and return
notifications from ACP 127 gateways, and are not relevant to an SMTP
gateway.
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6. Gatewaying with ACP 123/STANAG 4406
The header fields defined in this specification are designed to be
mapped with ACP 123 Annex A1 heading extensions as part of a MIXER
mapping according to [RFC2156]. The syntax of these headings is
defined such that mapping is mechanical. OR Names SHOULD be mapped
with Internet Email addresses according to [RFC2156].
This section summarizes how a gateway between [ACP123] and [RFC5322]
conformant to this specification operates.
If an incoming X.400 message is encoded as P772, [RFC5322] header
fields MUST be generated according to this specification for all ACP
123 heading extensions where an equivalent header is defined in this
specification. For the three heading extensions where no mapping is
defined the heading extension MAY be discarded or mapped in a
proprietary manner. If a Distribution Extension is encoded this MAY
be discarded or represented as a comment (<CFWS>). The whole message
MAY be signed according to [RFC5652]. These rules also apply to
heading extensions in forwarded messages. MM-Message MUST be treated
as a forwarded message for the purposes of MIXER mapping. If an ACP
127 Notification Request is present, this MAY be discarded or
represented as a comment (<CFWS>).
Incoming X.400 notifications are encoded according to [RFC2156]. If
an ACP 127 Notification Response is present, this MAY be discarded or
mapped in a proprietary manner.
If an incoming SMTP message contains any of the header fields defined
in this specification, the outgoing X.400 message MUST be encoded as
P772. The outgoing message MAY be encoded as P772 for other reasons,
such as policy or characteristics such as the message containing a
military body part. The X.400 message MAY be signed according to ACP
123 Annex B and Annex G. message/rfc822 body parts included in the
message SHOULD be mapped to MM-Message, and the heading mapping rules
applied.
Generated P772 messages SHOULD follow the following rules, generating
heading extensions if needed.
a. Extended Authorization is required. If the MMHS-Extended-
Authorisation-Info header field is absent, then the default value
is taken from the Date: header field.
b. Primary Precedence is required if the To header field is present.
If the MMHS-Primary-Precedence header field is absent, the
default value is "priority".
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c. Copy Precedence is required if the Cc header field is present.
If the MMHS-Copy-Precedence header field is absent, then the
Default value is the value of the Primary Precedence as
constructed above.
d. For Message-ID fields, ACP 123 applies additional constraints
over X.400, leading to the following rules additional to
[RFC2156] which SHOULD be followed by a gateway following this
specification.
1. The local identifier MUST be at least 15 characters long. If
the [RFC2156] generated value is shorter than this, then it
is padded with spaces to 15 characters. This value will
correctly reverse map.
2. The OR Address part is required, and not usually generated by
an [RFC2156] mapping. It is mandatory in ACP 123. The
gateway SHOULD generate an OR Address in a manner that can be
reverse mapped. It MAY use the OR Address to encode long
message ids that cannot be encoded in the local identifier.
7. Gatewaying with ACP 127
The header fields defined in this specification include fields to
carry ACP 127 specific elements of service [ACP127]. This
specification does not define a mapping of these header fields to ACP
127. In the absence of this mapping, it is recommended that these
heading should be mapped to ACP 123 and hence into ACP 127 following
the Annex D (Gateway Translation) of [ACP123].
8. IANA Considerations
IANA is requested to add the list of header fields specified in
subsections of Section 3 to the "Permanent Message Header Field
Registry", defined by Registration Procedures for Message Header
Fields [RFC3864].
9. Security Considerations
No security considerations are introduced by this document beyond
those already inherent in use of the MMHS header fields referenced.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322,
October 2008.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC2156] Kille, S., "MIXER (Mime Internet X.400 Enhanced
Relay): Mapping between X.400 and RFC 822/MIME",
RFC 2156, January 1998.
[RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration
Procedures for Message Header Fields", BCP 90,
RFC 3864, September 2004.
[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)",
STD 70, RFC 5652, September 2009.
[ACP123] CCEB, "Common Messaging strategy and procedures",
ACP 123, May 2009.
[ACP127] CCEB, "Communication Instructions - Tape Relay
Procedures", ACP 127, November 1988.
10.2. Informative References
[RFC2634] Hoffman, P., "Enhanced Security Services for S/MIME",
RFC 2634, June 1999.
[RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose
Internet Mail Extensions (S/MIME) Version 3.2 Message
Specification", RFC 5751, January 2010.
[STANAG-4406] NATO, "STANAG 4406 Edition 2: Military Message
Handling System", STANAG 4406, March 2005.
[ACP121] CCEB, "Comms Instructions - General", ACP 121,
May 2010.
[ACP131] CCEB, "Comms Instructions - Operating Signals",
ACP 131, April 2009.
Appendix A. Acknowledgements
This document copies lots of text from
draft-onions-x400p772-822-mapping-01.txt and STANAG 4066 (2nd
Edition). So the authors of this document would like to acknowledge
contributions made by the authors of these documents.
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Many thanks for reviews and text provided by Steve Kille, Alan Ross,
David Wilson, James Usmar, Kathy Nuckles, Andy Trayler, Ken Carlberg,
Chris Bonatti, Oeyvind Jonsson, Mykyta Yevstifeyev, Sean Turner,
Stephen Farrell, Adrian Farrel and Peter Saint-Andre.
Authors' Addresses
Alexey Melnikov
Isode Ltd
5 Castle Business Village
36 Station Road
Hampton, Middlesex TW12 2BX
UK
EMail: Alexey.Melnikov@isode.com
Graeme Lunt
SMHS Ltd
Bescar Moss Farm
Bescar Lane
Ormskirk L40 9QN
UK
EMail: graeme.lunt@smhs.co.uk
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