Privacy Enhancement for Internet Electronic Mail: Part III: Algorithms, Modes, and Identifiers
RFC 1423

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• 01

Network Working Group                                        D. Balenson
Request for Comments: 1423                                           TIS
Obsoletes: 1115                               IAB IRTF PSRG, IETF PEM WG
                                                           February 1993

           Privacy Enhancement for Internet Electronic Mail:
              Part III: Algorithms, Modes, and Identifiers

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.

Abstract

   This document provides definitions, formats, references, and
   citations for cryptographic algorithms, usage modes, and associated
   identifiers and parameters used in support of Privacy Enhanced Mail
   (PEM) in the Internet community.  It is intended to become one member
   of the set of related PEM RFCs.  This document is organized into four
   primary sections, dealing with message encryption algorithms, message
   integrity check algorithms, symmetric key management algorithms, and
   asymmetric key management algorithms (including both asymmetric
   encryption and asymmetric signature algorithms).

   Some parts of this material are cited by other documents and it is
   anticipated that some of the material herein may be changed, added,
   or replaced without affecting the citing documents.  Therefore,
   algorithm-specific material has been placed into this separate
   document.

   Use of other algorithms and/or modes will require case-by-case study
   to determine applicability and constraints.  The use of additional
   algorithms may be documented first in Prototype or Experimental RFCs.
   As experience is gained, these protocols may be considered for
   incorporation into the standard.  Additional algorithms and modes
   approved for use in PEM in this context will be specified in
   successors to this document.

Acknowledgments

   This specification was initially developed by the Internet Research
   Task Force's Privacy and Security Research Group (IRTF PSRG) and
   subsequently refined based on discussion in the Internet Engineering

Balenson                                                        [Page 1]
RFC 1423         PEM: Algorithms, Modes and Identifiers    February 1993

   Task Force's Privacy Enhanced Mail Working Group (IETF PEM WG).  John
   Linn contributed significantly to the predecessor of this document
   (RFC 1115).  I would like to thank the members of the PSRG and PEM
   WG, as well as all participants in discussions on the "pem-
   dev@tis.com" mailing list, for their contributions to this document.

Table of Contents

      1.  Message Encryption Algorithms ....................... 2
      1.1  DES in CBC Mode (DES-CBC) .......................... 2
      2.  Message Integrity Check Algorithms .................. 4
      2.1  RSA-MD2 Message Digest Algorithm ................... 4
      2.2  RSA-MD5 Message Digest Algorithm ................... 5
      3.  Symmetric Key Management Algorithms ................. 6
      3.1  DES in ECB mode (DES-ECB) .......................... 6
      3.2  DES in EDE mode (DES-EDE) .......................... 7
      4.  Asymmetric Key Management Algorithms ................ 7
      4.1  Asymmetric Keys .................................... 7
      4.1.1  RSA Keys ......................................... 7
      4.2  Asymmetric Encryption Algorithms ..................  9
      4.2.1  RSAEncryption ...................................  9
      4.3  Asymmetric Signature Algorithms ................... 10
      4.3.1  md2WithRSAEncryption ............................ 11
      5.  Descriptive Grammar ................................ 11
      References ............................................. 12
      Patent Statement ....................................... 13
      Security Considerations ................................ 14
      Author's Address ....................................... 14

1.  Message Encryption Algorithms

   This section identifies the alternative message encryption algorithms
   and modes that shall be used to encrypt message text and, when
   asymmetric key management is employed in an ENCRYPTED PEM message, for
   encryption of message signatures.  Character string identifiers are
   assigned and any parameters required by the message encryption
   algorithm are defined for incorporation in an encapsulated "DEK-
   Info:" header field.

   Only one alternative is currently defined in this category.

1.1  DES in CBC Mode (DES-CBC)

   Message text and, if required, message signatures are encrypted using
   the Data Encryption Standard (DES) algorithm in the Cipher Block
   Chaining (CBC) mode of operation.  The DES algorithm is defined in
   FIPS PUB 46-1 [1], and is equivalent to the Data Encryption Algorithm