Internet Draft Editor: Terry Harding draft-ietf-ediint-compression-01.txt Cyclone Commerce Inc. Feburary 2003 Expires August 2003 Target Category: Informational Compressed Data for EDIINT Status of this memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Copyright (C) The Internet Society July 2001. All Rights Reserved. Abstract The intent of this document is to be placed on the RFC track as an Informational RFC. The EDIINT AS1 and AS2 message formats don't currently contain any transport neutral provisions for compressing data when utilizing S/MIME as the secure packaging standard. Compressing data before transmission provides a number of advantages including 1. reducing data redundancy, and so reducing opportunities for attacks exploiting redundancy, and 2. reducing the amount of data and so speeding up cryptographic processing such as signing, encryption, archiving, and 3. reducing the overall transmitted message size, reducing both time and bandwidth needed for transport. 1. Introduction Terry Harding [Page 1]
Compressed Data for EDIINT November, 2001 This document describes an additional mime layer of compressed data utilizing a new ContentInfo type for S/MIME. This new compressed-data content type is an extension to the types currently defined in CMS[RFC2630]. Further reference can be found in the reference section under [COMPRESSED-DATA]. The method of compression outlined in this document will support any type of business related media. Documents containing a large percentage of ASCII characters like xml, x12 or edifact will experience greater compression ratios than documents consisting largely of binary data. Ex: MSWord documents. The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 1.1 Compressed-Data Mime Wrapper The compressed-data cms object will encapsulate a mime wrapped business document. Implementors are to follow the appropriate specifications identified under "References" in [MIME-TYPES], for the type of object being transmitted. For example, to send an XML object, the MIME media type of application/xml is used in the Content-type MIME header and the specifications for enveloping the object are contained in [XMLTYPES]; for example: Content-type: application/xml; charset="utf-8" The mime wrapped object will be compressed and placed inside a CMS compressed-data object as outlined in [COMPRESSED-DATA]. The compressed data object will be mime wrapped according to details outlined in [S/MIME],Section 3.2. Since RFC2633 does not specifically reference the new compressed-data type, we will use the encrypted-only section 3.3 as a guide to properly mime wrapping the compressed data object. Example: Content-type: application/pkcs7-mime; smime-type=compressed-data; name=smime.p7m Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename=smime.p7m rfvbnj756tbBghyHhHUujhJhjH77n8HHGT9HG4VQpfyF467GhIGfHfYT6 7n8HHGghyHhHUujhJh4VQpfyF467GhIGfHfYGTrfvbnjT6jH7756tbB9H f8HHGTrfvhJhjH776tbB9HG4VQbnj7567GhIGfHfYT6ghyHhHUujpfyF4 0GhIGfHfQbnj756YT64V Note: Content-Transfer-Encoding would only be required if the mime wrapped CMS object was transferred via SMTP and it was visible in the outer layer of the mime message. If the compressed-data mime bodypart was place inside of an encrypted mime bodypart, Terry Harding [Page 2]
Compressed Data for EDIINT November, 2001 content-transfer-encoding would not be required on the compressed-data mime bodypart, but would be required on the encrypted mime bodypart. 1.2 Structure of an EDI MIME message utilizing compression 1.2.1 No encryption, no signature -RFC822/2045 -[COMPRESSED-DATA](application/pkcs7-mime) -[MIME-TYPES](application/xxxxxxx) 1.2.2 No encryption, signature -RFC822/2045 -RFC1847 (multipart/signed) -[COMPRESSED-DATA](application/pkcs7-mime) -[MIME-TYPES](application/xxxxxxx) -RFC2633 (application/pkcs7-signature) 1.2.3 Encryption, no signature -RFC822/2045 -RFC2633 (application/pkcs7-mime) -[COMPRESSED-DATA](application/pkcs7-mime) (encrypted) -[MIME-TYPES](application/xxxxxxx) (encrypted) 1.2.4 Encryption, signature -RFC822/2045 -RFC2633 (application/pkcs7-mime) -RFC1847 (multipart/signed) (encrypted) -[COMPRESSED-DATA](application/pkcs7-mime) (encrypted) -[MIME-TYPES](application/xxxxxxx) (encrypted) -RFC2633 (application/pkcs7-signature) (encrypted) 2. MIC Calculations For Signed Receipts For signed compressed messages, the MIC to be returned is calculated over the entire compressed data mime bodypart, including all RFC 822 headers and any Content-Transfer-Encoding that was applied to the compressed data. For encrypted, unsigned compressed messages, the MIC to be returned is calculated over the entire compressed data mime bodypart, including all RFC 822 headers and any Content-Transfer-Encoding that was applied to the compressed data. For unsigned, unencrypted compressed messages, the MIC MUST be calculated over the compressed message contents prior to Terry Harding [Page 3]
Compressed Data for EDIINT November, 2001 Content-Transfer-Encoding and without the MIME or any other RFC 822 headers. 3. Compression Formats Implementations SHOULD support ZLIB [RFC1950] which utilizes DEFLATE[RFC1951], and is free of any intellectual property restrictions and has a freely-available, portable and efficient reference implementation. 4. Security Considerations This document is not concerned with security, except for the fact that compressing data before encryption can enhance the security by reducing redundancy of the file. The lower the redundancy of the plaintext being encrypted, the more difficult the cryptanalysis, see reference[CRYPTANALYSIS]. Author Address Terry Harding Cyclone Commerce Inc. Scottsdale, Arizona, USA tharding@cyclonecommerce.com References [RFC2119] Key Words for Use in RFC's to Indicate Requirement Levels, S.Bradner, March 1997. [ZLIB] RFC1950 ZLIB Compressed Data Format Specification version 3.3, P.Deutsch and J-L Gailly, May 1996. [DEFLATE] RFC1951 DEFLATE Compressed Data Format Specification version 1.3, P.Deutsch, May 1996. [CMS] RFC2630 Cryptographic Message Syntax, R.Housley, June 1999. [S/MIME]RFC2633 S/MIME Version 3 Message Specification, B.Ramsdell, June 1999. [MIME-TYPES] "Media Types," http://www.isi.edu/in- notes/iana/assignments/media-types/media-types. [XMLTYPES] E. Whitehead, M. Murata, "XML Media Types", RFC 2376, July 1998. Terry Harding [Page 4]
Compressed Data for EDIINT November, 2001 [COMPRESSED-DATA] P. Gutmann, "Compressed Data Content Type for CMS" draft-ietf-smime-compression-05.txt, July 2001. [CRYPTANALYSIS] B. Schneier, "Self-Study Course in Block Cipher Cryptanalysis", http://www.counterpane.com/self-study.html, Jan 2000. Acknowledgements A number of the members of the EDIINT Working Group have also worked very hard and contributed to this document. The following people have made direct contributions to this document. David Fisher, Dale Moberg, Robert Asis. Full Copyright Statement Copyright (C) The Internet Society 2001. All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Terry Harding [Page 5]