Cryptographic Algorithm Implementation Requirements and Usage Guidance for Encapsulating Security Payload (ESP) and Authentication Header (AH)
RFC 7321

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Internet Engineering Task Force (IETF)                         D. McGrew
Request for Comments: 7321                                 Cisco Systems
Obsoletes: 4835                                               P. Hoffman
Category: Standards Track                                 VPN Consortium
ISSN: 2070-1721                                              August 2014

 Cryptographic Algorithm Implementation Requirements and Usage Guidance
for Encapsulating Security Payload (ESP) and Authentication Header (AH)

Abstract

   This document updates the Cryptographic Algorithm Implementation
   Requirements for the Encapsulating Security Payload (ESP) and
   Authentication Header (AH).  It also adds usage guidance to help in
   the selection of these algorithms.

   ESP and AH protocols make use of various cryptographic algorithms to
   provide confidentiality and/or data origin authentication to
   protected data communications in the IP Security (IPsec)
   architecture.  To ensure interoperability between disparate
   implementations, the IPsec standard specifies a set of mandatory-to-
   implement algorithms.  This document specifies the current set of
   mandatory-to-implement algorithms for ESP and AH, specifies
   algorithms that should be implemented because they may be promoted to
   mandatory at some future time, and also recommends against the
   implementation of some obsolete algorithms.  Usage guidance is also
   provided to help the user of ESP and AH best achieve their security
   goals through appropriate choices of cryptographic algorithms.

   This document obsoletes RFC 4835.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7321.

McGrew & Hoffman             Standards Track                    [Page 1]
RFC 7321               Requirements for ESP and AH           August 2014

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   document authors.  All rights reserved.

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   Without obtaining an adequate license from the person(s) controlling
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   than English.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Implementation Requirements . . . . . . . . . . . . . . . . .   4
     2.1.  ESP Authenticated Encryption (Combined Mode Algorithms) .   4
     2.2.  ESP Encryption Algorithms . . . . . . . . . . . . . . . .   4
     2.3.  ESP Authentication Algorithms . . . . . . . . . . . . . .   5
     2.4.  AH Authentication Algorithms  . . . . . . . . . . . . . .   5
     2.5.  Summary of Changes from RFC 4835  . . . . . . . . . . . .   5
   3.  Usage Guidance  . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Rationale . . . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  Authenticated Encryption  . . . . . . . . . . . . . . . .   7
     4.2.  Encryption Transforms . . . . . . . . . . . . . . . . . .   7
     4.3.  Authentication Transforms . . . . . . . . . . . . . . . .   7
   5.  Algorithm Diversity . . . . . . . . . . . . . . . . . . . . .   8
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9