Implicit IV for Counter-based Ciphers in IPsec
draft-mglt-ipsecme-implicit-iv-04

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Last updated 2017-11-11 (latest revision 2017-06-21)
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IPSECME                                                  D. Migault, Ed.
Internet-Draft                                                  Ericsson
Intended status: Standards Track                        T. Guggemos, Ed.
Expires: December 22, 2017                                    LMU Munich
                                                                  Y. Nir
                                                                Dell EMC
                                                           June 20, 2017

             Implicit IV for Counter-based Ciphers in IPsec
                   draft-mglt-ipsecme-implicit-iv-04

Abstract

   IPsec ESP sends an initialization vector (IV) or nonce in each
   packet, adding 8 or 16 octets.  Some algorithms such as AES-GCM, AES-
   CCM, AES-CTR and ChaCha20-Poly1305 require a unique nonce but do not
   require an unpredictable nonce.  When using such algorithms the
   packet counter value can be used to generate a nonce, saving 8 octets
   per packet.  This document describes how to do this.

Status of This Memo

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   This Internet-Draft will expire on December 22, 2017.

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   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   carefully, as they describe your rights and restrictions with respect

Migault, et al.         Expires December 22, 2017               [Page 1]
Internet-Draft                 Implicit IV                     June 2017

   to this document.  Code Components extracted from this document must
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Table of Contents

   1.  Requirements notation . . . . . . . . . . . . . . . . . . . .   2
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Implicit IV . . . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Initiator Behavior  . . . . . . . . . . . . . . . . . . . . .   4
   6.  Responder Behavior  . . . . . . . . . . . . . . . . . . . . .   4
   7.  Security Consideration  . . . . . . . . . . . . . . . . . . .   4
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     9.2.  Informational References  . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Requirements notation

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

2.  Introduction

   Counter-based AES modes of operation such as AES-CTR ([RFC3686]),
   AES-CCM ([RFC4309]), and AES-GCM ([RFC4106]) require the
   specification of an nonce for each ESP packet.  The same applies for
   ChaCha20-Poly1305 ([RFC7634].  Currently this nonce is sent in each
   ESP packet ([RFC4303]).  This practice is designated in this document
   as "explicit nonce".

   In some context, such as IoT, it may be preferable to avoid carrying
   the extra bytes associated to the IV and instead generate it locally
   on each peer.  The local generation of the nonce is designated in
   this document as "implicit IV".

   The size of this nonce depends on the specific algorithm, but all of
   the algorithms mentioned above take an 8-octet nonce.

   This document defines how to compute the nonce locally when it is
   implicit.  It also specifies how peers agree with the Internet Key
   Exchange version 2 (IKEv2 - [RFC7296]) on using an implicit IV versus
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