Draft Multiple Attachments for EDIINT June 2008 Private Working Group K. Meadors Internet-Draft Drummond Group Inc. Expires: December 2008 June 2008 Target Category: Informational Multiple Attachments for EDI-INT draft-meadors-multiple-attachments-ediint-06.doc Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Any questions, comments, and reports of defects or ambiguities in this specification may be sent to the mailing list for the EDIINT working group of the IETF Trust, using the address . Requests to subscribe to the mailing list should be addressed to . Copyright Notice Copyright (C) The IETF Trust (2008). Abstract The EDIINT AS1, AS2 and AS3 message 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 Meadors Expires - December 2008 [Page 1] Draft Multiple Attachments for EDIINT June 2008 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. 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 RFC-2119. Feedback Instructions NOTE TO RFC EDITOR: This section should be removed by the RFC editor prior to publication. If you want to provide feedback on this draft, follow these guidelines: -Send feedback via e-mail to kyle@drummondgroup.com, with "EDIINT Multiple Attachments" in the Subject field. -Be specific as to what section you are referring to, preferably quoting the portion that needs modification, after which you state your comments. -If you are recommending some text to be replaced with your suggested text, again, quote the section to be replaced, and be clear on the section in question. Table of Contents 1. Introduction...................................................3 2. Using Multiple-Attachments in EDI-INT..........................3 2.1 Multipart/Related Structure................................3 2.2 EDIINT Features Header.....................................3 2.3 MIC Calculation............................................4 2.4 Document Processing........................................5 2.5 Content-Types to Support...................................5 3. Example Message................................................5 4. Security Considerations........................................6 5. References.....................................................7 5.1 Normative References.......................................7 Meadors Expires - December 2008 [Page 2] Draft Multiple Attachments for EDIINT June 2008 5.2 Informative References.....................................7 Author's Address..................................................7 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], HTTP [AS2] and FTP [AS3]. 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 envelope structure within EDI-INT messages to store multiple document attachments. Details of computing the MIC value over this envelope is covered. A minimum listing of MIME media types to support within the multipart/related envelope is given along with information on extracting these documents. 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 envelope [RFC2387]. The multipart/related structure allows an unlimited number of attachments, but the attachments MUST be inter-related to complete a transaction. Multiple attachments in EDI-INT MUST NOT be used for batch processing of EDI or other documents which are not inter-related. For example numerous EDI purchase orders for different products must not be sent in a multipart/related envelope but instead be transmitted in separate, individual EDI-INT messages. 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 envelope 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 EDIINT Features Header To indicate support for MA, an EDIINT application MUST use the EDIINT Features header [EDIINT-FEATURE]. The Feature Header indicates the Meadors Expires - December 2008 [Page 3] Draft Multiple Attachments for EDIINT June 2008 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 feature certification exchange. For applications implementing certification exchange, the MA-Feature- Name MUST be used within the EDIINT Features header: MA-Feature-Name = "multiple-attachments" An example of the EDIINT 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 a similar fashion to a single EDI payload. Section 5.2.1 of [AS1] and section 2 of [EDIINT COMPRESSION] describe the MIC calculations used for single document attachments. When a digital signature is applied to the multipart/related envelope, the MIC is calculated on the entire multipart/related envelope, including the MIME header and all attached documents. If compression is first applied to the envelope and the digital signature is then applied to the compressed data, the MIC is calculated over the compressed envelope including the MIME headers. For a compressed but unsigned message, regardless of encryption, the MIC is calculated over the uncompressed multipart/related envelope including any applied Content-Transfer-Encoding. The envelope MUST be canonicalized before the MIC is calculated. For an encrypted but unsigned and uncompressed message, the MIC is calculated on the decrypted multipart/related envelope, including header and all attached documents. The envelope MUST be canonicalized 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. Meadors Expires - December 2008 [Page 4] Draft Multiple Attachments for EDIINT June 2008 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 envelope 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 envelop and MUST be accepted by the user agent. 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-string application/zip image/bmp image/gif image/tiff image/jpeg text/plain text/html text/rtf text/xml 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. POST /as2 HTTP/1.1 Host: www.example.com:8080 Connection: Close, TE Message-ID: <1109712943488@10.65.122.242> Subject: Multiple Attachment Example Meadors Expires - December 2008 [Page 5] Draft Multiple Attachments for EDIINT June 2008 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=""; type="application/xml" --INNER-BOUNDARY Content-Type: application/xml Content-ID: [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-- 4. Security Considerations Multiple attachments have very similar security concerns to what is described in the three EDI-INT transport standards. Please refer to these standards for 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 Meadors Expires - December 2008 [Page 6] Draft Multiple Attachments for EDIINT June 2008 over the multipart/related envelop, the MIC validates the content- integrity of all the documents. 5. References 5.1 Normative References [AS1] RFC3335 "MIME-based Secure Peer-to-Peer Business Data Interchange over the Internet using SMTP", T. Harding, R. Drummond, C. Shih, 2002. [AS2] RFC4130 "MIME-based Secure Peer-to-Peer Business Data Interchange over the Internet using HTTP", D. Moberg, R. Drummond, 2005. [AS3] RFC 4823 "FTP Transport for Secure Peer-to-Peer", T. Harding, R. Scott, 2007. [EDIINT COMPRESSION] draft-ietf-compression-10.txt "Compressed Data for EDIINT", T. Harding, 2008. [EDIINT-FEATURE] draft-meadors-ediint-feature-header-04.txt "Feature Header for EDI-INT", K. Meadors, 2008. [RFC2119] RFC2119 "Key Words for Use in RFC's to Indicate Requirement Levels", S.Bradner, March 1997. [RFC2387] RFC2387 "The MIME Multipart/Related Content-type", E. Levinson, August 1998. 5.2 Informative References Author's Address Kyle Meadors Drummond Group Inc. #238 13359 North Highway 183 Austin, TX 78750 USA Email: kyle@drummondgroup.com Full Copyright Statement Copyright (C) The IETF Trust (2008). Meadors Expires - December 2008 [Page 7] Draft Multiple Attachments for EDIINT June 2008 This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf- ipr@ietf.org. Meadors Expires - December 2008 [Page 8]