Securing X.400 Content with Secure/Multipurpose Internet Mail Extensions (S/MIME)
RFC 3854

• Status
• IESG evaluation record
• IESG writeups
• Email expansions
• History

• Versions
• 09

Network Working Group                                         P. Hoffman
Request for Comments: 3854                                           IMC
Category: Standards Track                                     C. Bonatti
                                                                    IECA
                                                                A. Eggen
                                                                     FFI
                                                               July 2004

     Securing X.400 Content with Secure/Multipurpose Internet Mail
                          Extensions (S/MIME)

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2004).

Abstract

   This document describes a protocol for adding cryptographic signature
   and encryption services to X.400 content with Secure/Multipurpose
   Internet Mail Extensions (S/MIME).

1.  Introduction

   The techniques described in the Cryptographic Message Syntax [CMS]
   specification are general enough to support many different content
   types.  The [CMS] specification thus provides many options for
   providing different security mechanisms.  In order to ensure
   interoperability of systems within the X.400 community, it is
   necessary to specify the use of CMS features to protect X.400 content
   (called "CMS-X.400" in this document).

1.1.  Specification Overview

   This document is intended to be similar to the S/MIME Version 3.1
   Message Specification [MSG] except that it is tailored to the
   requirements of X.400 content rather than Multipurpose Internet Mail
   Extensions (MIME).

Hoffman, et al.             Standards Track                     [Page 1]
RFC 3854               Securing X.400 with S/MIME              July 2004

   This document defines how to create an X.400 content type that has
   been cryptographically enhanced according to [CMS].  In order to
   create S/MIME messages carrying X.400 content, an S/MIME agent has to
   follow specifications in this document, as well as the specifications
   listed in [CMS].  This memo also defines new parameter values for the
   application/pkcs7-mime MIME type that can be used to transport those
   body parts.

   Throughout this document, there are requirements and recommendations
   made for how receiving agents handle incoming messages.  There are
   separate requirements and recommendations for how sending agents
   create outgoing messages.  In general, the best strategy is to "be
   liberal in what you receive and conservative in what you send".  Most
   of the requirements are placed on the handling of incoming messages
   while the recommendations are mostly on the creation of outgoing
   messages.

   This document does not address transport of CMS-X.400 content.  It is
   assumed that CMS-X.400 content would be transported by Internet mail
   systems, X.400, or other suitable transport.

   This document describes applying security services to the content of
   entire X.400 messages, which may or may not be IPMS messages.  These
   objects can be carried by several means, including SMTP-based mail
   and X.400 mail.  Note that cooperating S/MIME agents must support
   common forms of message content in order to achieve interoperability.

   If the CMS objects are sent as parts of an RFC 822 message, a
   standard MIXER gateway [MIXER] will most likely choose to encapsulate
   the message.  This is not likely to be a format that is usable by an
   X.400 recipient.  MIXER is specifically focused on translation
   between X.420 Interpersonal Messages and non-secure RFC822/MIME
   messages.  The discussion of security-related body parts in sections
   7.3 and 7.4 of [BODYMAP] is relevant to CMS messages.

   Definition of gateway services to support relay of CMS object between
   X.400 and SMTP environments is beyond the scope of this document.

1.2.  Terminology

   The key words "MUST", "SHALL", "REQUIRED", "SHOULD", "RECOMMENDED",
   and "MAY" in this document are to be interpreted as described in BCP
   14, RFC 2119 [MUSTSHOULD].

Hoffman, et al.             Standards Track                     [Page 2]
RFC 3854               Securing X.400 with S/MIME              July 2004

1.3.  Definitions

   For the purposes of this document, the following definitions apply.

   ASN.1:             Abstract Syntax Notation One, as defined in
                      ISO/IEC 8824.

   BER:               Basic Encoding Rules for ASN.1, as defined in
                      ISO/IEC 8825-1.

   Certificate:       A type that binds an entity's distinguished name
                      to a public key with a digital signature.