RFC 1113 (rfc1113) - Page 2 of 34


Privacy enhancement for Internet electronic mail: Part I - message encipherment and authentication procedures



Alternative Format: Original Text Document



RFC 1113                Mail Privacy: Procedures             August 1989


   4.6.1  Per-Message Encapsulated Header Fields                      20
   4.6.1.1  X-Proc-Type Field                                         20
   4.6.1.2  X-DEK-Info Field                                          21
   4.6.2  Encapsulated Header Fields Normally Per-Message             21
   4.6.2.1  X-Sender-ID Field                                         22
   4.6.2.2  X-Certificate Field                                       22
   4.6.2.3  X-MIC-Info Field                                          23
   4.6.3  Encapsulated Header Fields with Variable Occurrences        23
   4.6.3.1  X-Issuer-Certificate Field                                23
   4.6.4  Per-Recipient Encapsulated Header Fields                    24
   4.6.4.1  X-Recipient-ID Field                                      24
   4.6.4.2  X-Key-Info Field                                          24
   4.6.4.2.1  Symmetric Key Management                                24
   4.6.4.2.2  Asymmetric Key Management                               25
   5.  Key Management                                                 26
   5.1  Data Encrypting Keys (DEKs)                                   26
   5.2  Interchange Keys (IKs)                                        26
   5.2.1  Subfield Definitions                                        28
   5.2.1.1  Entity Identifier Subfield                                28
   5.2.1.2  Issuing Authority Subfield                                29
   5.2.1.3  Version/Expiration Subfield                               29
   5.2.2  IK Cryptoperiod Issues                                      29
   6.  User Naming                                                    29
   6.1  Current Approach                                              29
   6.2  Issues for Consideration                                      30
   7.  Example User Interface and Implementation                      30
   8.  Areas For Further Study                                        31
   9.  References                                                     32
   NOTES                                                              32

1.  Executive Summary

   This RFC defines message encipherment and authentication procedures,
   in order to provide privacy enhancement services for electronic mail
   transfer in the Internet.  It is one member of a related set of four
   RFCs.  The procedures defined in the current RFC 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-1114 specifies supporting key
   management mechanisms based on the use of public-key certificates.
   RFC-1115 specifies algorithm and related information relevant to the
   current RFC and to RFC-1114.  A subsequent RFC will provide 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, and



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