Individual Submission K. Meadors, Ed.
Internet-Draft Drummond Group Inc.
Intended status: Informational June 29, 2011
Expires: December 31, 2011
Multiple Attachments for EDI-INT
draft-meadors-multiple-attachments-ediint-14
Abstract
The EDI-INT AS1, AS2 and AS3 messages were designed specifically for
the transport of EDI documents. Since multiple interchanges could be
placed within a single EDI document, there was not a need for sending
multiple EDI documents in a single message. As adoption of EDI-INT
grew, other uses developed aside from single EDI document transport.
Some transactions required multiple attachments to be interpreted
together and stored in a single message. This informational draft
describes how multiple documents, including non-EDI payloads, can be
attached and transmitted in a single EDI-INT transport message. The
attachments are stored within the MIME Multipart/Related structure.
A minimal list of content-types to be supported as attachments is
provided.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on December 31, 2011.
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document authors. All rights reserved.
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Provisions Relating to IETF Documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Using Multiple-Attachments in EDI-INT . . . . . . . . . . . . 4
2.1. Multipart/Related Structure . . . . . . . . . . . . . . . 4
2.2. EDI-INT Features Header . . . . . . . . . . . . . . . . . 4
2.3. MIC Calculation . . . . . . . . . . . . . . . . . . . . . 5
2.4. Document Processing . . . . . . . . . . . . . . . . . . . 6
2.5. Content-Types to Support . . . . . . . . . . . . . . . . . 6
3. Example Message . . . . . . . . . . . . . . . . . . . . . . . 7
4. Security Considerations . . . . . . . . . . . . . . . . . . . 9
5. Normative References . . . . . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10
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1. Introduction
The primary work of EDI-INT was to develop a secure means of
transporting EDI documents over the Internet. This was described in
the three working group developed standards for secure transport over
SMTP AS1 [RFC3335], HTTP AS2 [RFC4130] and FTP AS3 [RFC4823]. For
most uses of EDI, all relevant information to complete a single
business transaction could be stored in a single document. As
adoption of EDI-INT grew, new industries and businesses began using
AS2 and needing to include multiple documents in a single message to
complete a trading partner transaction. These documents were a
variety of MIME media types. This informational draft describes how
to use the MIME multipart/related body structure within EDI-INT
messages to store multiple document attachments. Details of
computing the MIC value over this body are covered. A minimum
listing of MIME media types to support within the multipart/related
body is given along with information on extracting these documents.
1.1. Requirements Language
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 RFC 2119 [RFC2119].
2. Using Multiple-Attachments in EDI-INT
2.1. Multipart/Related Structure
Multiple payload attachments for EDI-INT messages are stored within a
multipart/related MIME body [RFC2387]. The multipart/related
structure allows an multiple number of MIME attachments or message
payloads to be communicated in a single structure and message.
The attached payloads can be of any MIME content-type depending on
the trading partner agreement, but section 2.4 lists the content-
types which MUST be supported. The use and format of the multipart/
related body follows the rules in RFC 2387, including the required
type parameter to determine the root body part. The use of the
optional start parameter is RECOMMENDED.
2.2. EDI-INT Features Header
To indicate support for multiple-attachments (MA), an EDI-INT
application MUST use the EDI-INT Features header [RFC6017]. The
Feature Header indicates the instance application can support various
features, such as certification exchange. The header is present in
all messages from the instance application, not just those which
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feature certification exchange.
For applications implementing multiple attachments, the MA-Feature-
Name MUST be used within the EDI-INT Features header as listed in
this ABNF [RFC5234] syntax:
MA-Feature-Name = "multiple-attachments"
An example of the EDI-INT Features header in a message from an
application supporting MA:
EDIINT-Features: multiple-attachments
2.3. MIC Calculation
MIC calculation in an EDI-INT message with multiple attachments is
performed in the same manner as for a single EDI payload. The only
difference is calculating the message integrity check (MIC) over the
whole multipart/related body rather than a single EDI payload.
Section 5.2.1 of AS1 [RFC3335] and section 2 of EDIINT COMPRESSION
[RFC5402] describe the MIC calculations used for single payload
document within an EDI-INT message. The approach is summerized below
for multipart/related. Refer to stated sections above for more
details.
For a compressed but unsigned message, regardless of encryption, the
MIC is calculated over the uncompressed multipart/related body
including any applied Content-Transfer-Encoding. The body MUST be
canonicalized according to the procedure described in the underlying
transport protocol (e.g. HTTP AS2 [RFC4130]) before the MIC is
calculated.
For an encrypted but unsigned and uncompressed message, the MIC is
calculated on the decrypted multipart/related body, including header
and all attached documents. The body MUST be canonicalized according
to the procedure described in the underlying transport protocol (e.g.
HTTP AS2 [RFC4130]) before the MIC is calculated.
For an unsigned and unencrypted message, the MIC is calculated over
the data inside the multipart/related boundaries prior to Content-
Transfer-Encoding. However, unsigned and unencrypted messages SHOULD
NOT be sent due to lack of security.
If the expected MIC value differs from the calculated MIC value, all
attachments MUST be considered invalid and retransmitted.
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2.4. Document Processing
Upon receipt of an EDI-INT message with multiple attachments, the
receiving user agent MUST be able to extract the attached payloads
from the message rather than only removing the multipart/related body
from the message. The storing or processing of the documents as they
relate to the pending transaction is implementation dependent.
2.5. Content-Types to Support
Documents of the following MIME media types MAY be found in a
multipart/related body and MUST be accepted by the user agent.
However, any media type can be used depending upon industry need, and
other media types MAY be accepted depending upon trading partner
agreement.
application/xml
application/pdf
application/msword
application/vnd.ms-excel, application/x-msexcel
application/rtf
application/octet-stream
application/zip
image/bmp
image/gif
image/tiff
image/jpeg
text/plain
text/html
text/rtf
text/xml
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3. Example Message
Here is an example AS2 message which uses two attachments. The first
attachment is an XML document which is the root attachment, and the
second attachment is a PDF document. For both the XML and PDF
documents as well as the applied digital signature, their content has
been omitted for size consideration. This example is provided as an
illustration only and is not considered part of the specification.
If the example conflicts with the definitions specified above or in
the other referenced RFCs, the example is considered invalid.
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POST /as2 HTTP/1.1
Host: www.example.com:8080
Connection: Close, TE
Message-ID: <1109712943488@10.65.122.242>
Subject: Multiple Attachment Example
Date: Tue, 01 Mar 2005 21:37:03 GMT
AS2-To: TradingPartner
AS2-From: User
AS2-Version: 1.2
EDIINT-Features: multiple-attachments
Disposition-Notification-To: http://www.example.com/as2
Disposition-Notification-Options:
signed-receipt-protocol=optional,pkcs7-signature;
signed-receipt-micalg=optional,sha1
Content-type: multipart/signed;
protocol="application/pkcs7-signature"; micalg=sha1;
boundary="OUTER-BOUNDARY"
Content-length: 207440
--OUTER-BOUNDARY
Content-Type: Multipart/Related; boundary="INNER-BOUNDARY";
start="<root.attachment>"; type="application/xml"
--INNER-BOUNDARY
Content-Type: application/xml
Content-ID: <root.attachment>
[XML DOCUMENT]
--INNER-BOUNDARY
Content-Type: application/pdf
Content-ID: <2nd.attachment>
[PDF DOCUMENT]
--INNER-BOUNDARY--
--OUTER-BOUNDARY
Content-Type: application/pkcs7-signature
[DIGITAL SIGNATURE]
--OUTER-BOUNDARY--
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4. Security Considerations
Multiple attachments have very similar security concerns to what is
described in the three EDI-INT transport standards. This includes
the importance of using strong cryptography and the necessity of
using valid certificates and chaining to a trusted CA. Please refer
to these standards SMTP AS1 [RFC3335], HTTP AS2 [RFC4130] and FTP AS3
[RFC4823] for details of their security considerations.
The only additional security consideration is that if the MIC
calculation by user agent differs from expected MIC calculation, all
the attached documents MUST be considered invalid. Because the MIC
calculation is over the multipart/related body, the MIC validates the
content-integrity of all the documents.
5. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2387] Levinson, E., "The MIME Multipart/Related Content-type",
RFC 2387, August 1998.
[RFC3335] Harding, T., Drummond, R., and C. Shih, "MIME-based Secure
Peer-to-Peer Business Data Interchange over the Internet",
RFC 3335, September 2002.
[RFC4130] Moberg, D. and R. Drummond, "MIME-Based Secure Peer-to-
Peer Business Data Interchange Using HTTP, Applicability
Statement 2 (AS2)", RFC 4130, July 2005.
[RFC4823] Harding, T. and R. Scott, "FTP Transport for Secure Peer-
to-Peer Business Data Interchange over the Internet",
RFC 4823, April 2007.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC5402] Harding, T., "Compressed Data within an Internet
Electronic Data Interchange (EDI) Message", RFC 5402,
February 2010.
[RFC6017] Meadors, K., "Electronic Data Interchange - Internet
Integration (EDIINT) Features Header Field", RFC 6017,
September 2010.
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Author's Address
Kyle Meadors (editor)
Drummond Group Inc.
Nashville, Tennessee 37221
US
Phone: +1 (817) 709-1627
Email: kyle@drummondgroup.com
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