Transporting Secure/Multipurpose Internet Mail Extensions (S/MIME) Objects in X.400
RFC 3855
Document | Type | RFC - Proposed Standard (July 2004; Errata) | |
---|---|---|---|
Authors | Paul Hoffman , Chistopher Bonatti | ||
Last updated | 2021-01-29 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized with errata bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 3855 (Proposed Standard) | |
Action Holders |
(None)
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||
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Russ Housley | ||
Send notices to | <turners@ieca.com>, <blake@brutesquadlabs.com> |
Network Working Group P. Hoffman Request for Comments: 3855 IMC Category: Standards Track C. Bonatti IECA July 2004 Transporting Secure/Multipurpose Internet Mail Extensions (S/MIME) Objects in X.400 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 protocol options for conveying objects that have been protected using the Cryptographic Message Syntax (CMS) and Secure/Multipurpose Internet Mail Extensions (S/MIME) version 3.1 over an X.400 message transfer system. 1. Introduction The techniques described in the Cryptographic Message Syntax [CMS] specification and message specifications can reasonably be transported via a variety of electronic mail systems. This specification defines the options and values necessary to enable interoperable transport of S/MIME messages over an X.400 system. This document describes a mechanism for using CMS objects as the message content of X.400 messages in a native X.400 environment. This means that gateways or other functions that expect to deal with IPMS, such as those specified in [MIXER] and [BODYMAP], cannot do anything with these messages. Note that cooperating S/MIME agents must support common forms of message content in order to achieve interoperability. Definition of gateway services to support relay of CMS object between X.400 and SMTP environments is beyond the scope of this document. Hoffman & Bonatti Standards Track [Page 1] RFC 3855 Transporting S/MIME Objects in X.400 July 2004 1.1. 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]. 1.2. Definitions For the purposes of this document, the following definitions apply. ASN.1: Abstract Syntax Notation One, as defined in ISO/IEC 8824. Object Identifier (OID): A globally unique identifier value consisting of a sequence of integer values assigned through distributed registration as specified by ISO/IEC 8824. Transfer Encoding: A reversible transformation made on data so 8-bit or binary data may be sent via a channel that only transmits 7-bit data. 1.3. Compatibility with Existing S/MIME Implementations It is a goal of this document to, if possible, maintain backward compatibility with existing X.400 implementations that employ S/MIME v3.1 wrappers. 2. S/MIME Packaging 2.1. The X.400 Message Structure This section reviews the X.400 message format. An X.400 message has two parts, the envelope and the content, as described in X.402 [X.400]: Envelope -- An information object whose composition varies from one transmittal step to another and that variously identifies the message's originator and potential recipients, documents its previous conveyance and directs its subsequent conveyance by the Message Transfer System (MTS), and characterizes its content. Content -- The content is the piece of information that the originating User Agent wants to be delivered to one or more recipients. The MTS neither examines nor modifies the content, except for conversion, during its conveyance of the message. MTS conversion is not applicable to the scenario of this document because such conversion is incompatible with CMS protection mechanisms. Hoffman & Bonatti Standards Track [Page 2] RFC 3855 Transporting S/MIME Objects in X.400 July 2004 One piece of information borne by the envelope identifies the type of the content. The content type is an identifier (an ASN.1 OID or Integer) that denotes the syntax and semantics of the content overall. This identifier enables the MTS to determine the message's deliverability to particular users, and enables User Agents and Message Stores to interpret and process the content. Some X.400 content types further refine the structure of content as a set of heading elements and body parts. An example of this is the Interpersonal Messaging System (IPMS). The IPMS content structure is able to convey zero or more arbitrary body parts each identified byShow full document text