Implicit IV for Counter-based Ciphers in Encapsulating Security Payload (ESP)
draft-ietf-ipsecme-implicit-iv-06

Document Type Active Internet-Draft (ipsecme WG)
Last updated 2018-11-16
Replaces draft-mglt-ipsecme-implicit-iv
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IPSECME                                                       D. Migault
Internet-Draft                                                  Ericsson
Intended status: Standards Track                             T. Guggemos
Expires: May 20, 2019                                         LMU Munich
                                                                  Y. Nir
                                                                Dell EMC
                                                       November 16, 2018

Implicit IV for Counter-based Ciphers in Encapsulating Security Payload
                                 (ESP)
                   draft-ietf-ipsecme-implicit-iv-06

Abstract

   Encapsulating Security Payload (ESP) sends an initialization vector
   (IV) or nonce in each packet.  The size of IV depends on the applied
   transform, being usually 8 or 16 octets for the transforms defined by
   the time this document is written.  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.  This avoids
   sending the nonce itself, and saves in the case of AES-GCM, AES-CCM,
   AES-CTR and ChaCha20-Poly1305 8 octets per packet.  This document
   describes how to do this.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on May 20, 2019.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   described in the Simplified BSD License.

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.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   5
     10.2.  Informational References . . . . . . . . . . . . . . . .   7
   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.

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