Privacy Enhancement for Internet Electronic Mail: Part I: Message Encryption and Authentication Procedures
RFC 1421
Document | Type |
RFC - Historic
(February 1993; No errata)
Obsoletes RFC 1113
Was draft-ietf-pem-msgproc (pem WG)
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Author | John Linn | ||
Last updated | 2013-03-02 | ||
Stream | Internet Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 1421 (Historic) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group J. Linn Request for Comments: 1421 IAB IRTF PSRG, IETF PEM WG Obsoletes: 1113 February 1993 Privacy Enhancement for Internet Electronic Mail: Part I: Message Encryption and Authentication Procedures Status of this Memo This RFC specifies an IAB standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "IAB Official Protocol Standards" for the standardization state and status of this protocol. Distribution of this memo is unlimited. Acknowledgements This document is the outgrowth of a series of meetings of the Privacy and Security Research Group (PSRG) of the IRTF and the PEM Working Group of the IETF. I would like to thank the members of the PSRG and the IETF PEM WG, as well as all participants in discussions on the "pem-dev@tis.com" mailing list, for their contributions to this document. 1. Executive Summary This document defines message encryption and authentication procedures, in order to provide privacy-enhanced mail (PEM) services for electronic mail transfer in the Internet. It is intended to become one member of a related set of four RFCs. The procedures defined in the current document are intended to be compatible with a wide range of key management approaches, including both symmetric (secret-key) and asymmetric (public-key) approaches for encryption of data encrypting keys. Use of symmetric cryptography for message text encryption and/or integrity check computation is anticipated. RFC 1422 specifies supporting key management mechanisms based on the use of public-key certificates. RFC 1423 specifies algorithms, modes, and associated identifiers relevant to the current RFC and to RFC 1422. RFC 1424 provides details of paper and electronic formats and procedures for the key management infrastructure being established in support of these services. Privacy enhancement services (confidentiality, authentication, message integrity assurance, and non-repudiation of origin) are offered through the use of end-to-end cryptography between originator and recipient processes at or above the User Agent level. No special processing requirements are imposed on the Message Transfer System at Linn [Page 1] RFC 1421 Privacy Enhancement for Electronic Mail February 1993 endpoints or at intermediate relay sites. This approach allows privacy enhancement facilities to be incorporated selectively on a site-by-site or user-by-user basis without impact on other Internet entities. Interoperability among heterogeneous components and mail transport facilities is supported. The current specification's scope is confined to PEM processing procedures for the RFC-822 textual mail environment, and defines the Content-Domain indicator value "RFC822" to signify this usage. Follow-on work in integration of PEM capabilities with other messaging environments (e.g., MIME) is anticipated and will be addressed in separate and/or successor documents, at which point additional Content-Domain indicator values will be defined. 2. Terminology For descriptive purposes, this RFC uses some terms defined in the OSI X.400 Message Handling System Model per the CCITT Recommendations. This section replicates a portion of (1984) X.400's Section 2.2.1, "Description of the MHS Model: Overview" in order to make the terminology clear to readers who may not be familiar with the OSI MHS Model. In the [MHS] model, a user is a person or a computer application. A user is referred to as either an originator (when sending a message) or a recipient (when receiving one). MH Service elements define the set of message types and the capabilities that enable an originator to transfer messages of those types to one or more recipients. An originator prepares messages with the assistance of his or her User Agent (UA). A UA is an application process that interacts with the Message Transfer System (MTS) to submit messages. The MTS delivers to one or more recipient UAs the messages submitted to it. Functions performed solely by the UA and not standardized as part of the MH Service elements are called local UA functions. The MTS is composed of a number of Message Transfer Agents (MTAs). Operating together, the MTAs relay messages and deliver them to the intended recipient UAs, which then make the messages available to the intended recipients. The collection of UAs and MTAs is called the Message Handling System (MHS). The MHS and all of its users are collectively referred to as the Message Handling Environment. Linn [Page 2]Show full document text