[Docs] [txt|pdf|xml|html] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-mglt-ipsecme-implicit-iv) 00 01 02 03 04

IPSECME                                                       D. Migault
Internet-Draft                                                  Ericsson
Intended status: Standards Track                             T. Guggemos
Expires: November 10, 2018                                    LMU Munich
                                                                  Y. Nir
                                                                Dell EMC
                                                             May 9, 2018


Implicit IV for Counter-based Ciphers in Encapsulating Security Payload
                                 (ESP)
                   draft-ietf-ipsecme-implicit-iv-04

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on November 10, 2018.

Copyright Notice

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




Migault, et al.         Expires November 10, 2018               [Page 1]


Internet-Draft             Implicit IV in ESP                   May 2018


   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
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   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 . . . . . . . . . . . . . . . .   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.



Migault, et al.         Expires November 10, 2018               [Page 2]


Internet-Draft             Implicit IV in ESP                   May 2018


   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
   an explicit IV.

   This document limits its scope to the algorithms mentioned above.
   Other algorithms with similar properties may later be defined to use
   this extension.

   This document does not consider AES-CBC ([RFC3602]) as AES-CBC
   requires the IV to be unpredictable.  Deriving it directly from the
   packet counter as described below is insecure as mentioned in
   Security Consideration of [RFC3602] and has led to real world chosen
   plain-text attack such as BEAST [BEAST].

3.  Terminology

   o  IoT: Internet of Things.

   o  IV: Initialization Vector.

   o  IIV: Implicit Initialization Vector.

   o  Nonce: a fixed-size octet string used only once.  This is similar
      to IV, except that in common usage there is no implication of non-
      predictability.

4.  Implicit IV

   With the algorithms listed in Section 2, the 8 byte nonce MUST NOT
   repeat.  The binding between a ESP packet and its nonce is provided
   using the Sequence Number or the Extended Sequence Number.  Figure 1
   and Figure 2 represent the IV with a regular 4-byte Sequence Number
   and with an 8-byte Extended Sequence Number respectively.

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              Zero                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Sequence Number                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            Figure 1: Implicit IV with a 4 byte Sequence Number

   o  Sequence Number: the 4 byte Sequence Number carried in the ESP
      packet.




Migault, et al.         Expires November 10, 2018               [Page 3]


Internet-Draft             Implicit IV in ESP                   May 2018


   o  Zero: a 4 byte array with all bits set to zero.

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Extended                              |
   |                      Sequence Number                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Figure 2: Implicit IV with an 8 byte Extended Sequence Number

   o  Extended Sequence Number: the 8 byte Extended Sequence Number of
      the Security Association.  The 4 byte low order bytes are carried
      in the ESP packet.

   As the IV MUST NOT repeat for one SA when Counter-Mode ciphers are
   used, Implicit IV as described in this document MUST NOT be used in
   setups with the chance that the Sequence Number overlaps for one SA.
   Multicast as described in [RFC5374], [RFC6407] and
   [I-D.yeung-g-ikev2] is a prominent example, where many senders share
   one secret and thus one SA.  As such, it is NOT RECOMMENDED to use
   Implicit IV with Multicast.

5.  Initiator Behavior

   An initiator supporting this feature SHOULD propose implicit IV
   algorithms in the Transform Type 1 (Encryption Algorithm)
   Substructure of the Proposal Substructure inside the SA Payload.  To
   facilitate backward compatibility with non-supporting peers the
   initiator SHOULD also include those same algorithms without Implicit
   IV (IIV) as separate transforms.

6.  Responder Behavior

   The rules of SA Payload processing require that responder picks its
   algorithms from the proposal sent by the initiator, thus this will
   ensure that the responder will never send an SA payload containing
   the IIV transform to an initiator that did not propose it.

7.  Security Consideration

   Nonce generation for these algorithms has not been explicitly
   defined.  It has been left to the implementation as long as certain
   security requirements are met.  Typically, for AES-GCM, AES-CCM, AES-
   CTR and ChaCha20-Poly1305, the IV is not allowed being repeated for
   one particular key.  This document provides an explicit and normative
   way to generate IVs.  The mechanism described in this document meets
   the IV security requirements of all relevant algorithms.



Migault, et al.         Expires November 10, 2018               [Page 4]


Internet-Draft             Implicit IV in ESP                   May 2018


8.  IANA Considerations

   This section assigns new code points to the recommended AEAD suites
   provided in [RFC8221], thus the new Transform Type 1 - Encryption
   Algorithm Transform IDs [IANA] are as defined below:

   -  ENCR_AES_CCM_8_IIV: 29

   -  ENCR_AES_GCM_16_IIV: 30

   -  ENCR_CHACHA20_POLY1305_IIV: 31

   These algorithms should be added with this document as ESP Reference
   and "Not Allowed" for IKEv2 Reference.

9.  Acknowledgements

   We would like to thanks people Valery Smyslov for their valuable
   comments, David Schinazi for its implementation, as well as the
   ipseceme chairs Tero Kivinen and David Waltermire for moving this
   work forward.

10.  References

10.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3602]  Frankel, S., Glenn, R., and S. Kelly, "The AES-CBC Cipher
              Algorithm and Its Use with IPsec", RFC 3602,
              DOI 10.17487/RFC3602, September 2003,
              <https://www.rfc-editor.org/info/rfc3602>.

   [RFC3686]  Housley, R., "Using Advanced Encryption Standard (AES)
              Counter Mode With IPsec Encapsulating Security Payload
              (ESP)", RFC 3686, DOI 10.17487/RFC3686, January 2004,
              <https://www.rfc-editor.org/info/rfc3686>.

   [RFC4106]  Viega, J. and D. McGrew, "The Use of Galois/Counter Mode
              (GCM) in IPsec Encapsulating Security Payload (ESP)",
              RFC 4106, DOI 10.17487/RFC4106, June 2005,
              <https://www.rfc-editor.org/info/rfc4106>.






Migault, et al.         Expires November 10, 2018               [Page 5]


Internet-Draft             Implicit IV in ESP                   May 2018


   [RFC4303]  Kent, S., "IP Encapsulating Security Payload (ESP)",
              RFC 4303, DOI 10.17487/RFC4303, December 2005,
              <https://www.rfc-editor.org/info/rfc4303>.

   [RFC4309]  Housley, R., "Using Advanced Encryption Standard (AES) CCM
              Mode with IPsec Encapsulating Security Payload (ESP)",
              RFC 4309, DOI 10.17487/RFC4309, December 2005,
              <https://www.rfc-editor.org/info/rfc4309>.

   [RFC5374]  Weis, B., Gross, G., and D. Ignjatic, "Multicast
              Extensions to the Security Architecture for the Internet
              Protocol", RFC 5374, DOI 10.17487/RFC5374, November 2008,
              <https://www.rfc-editor.org/info/rfc5374>.

   [RFC6407]  Weis, B., Rowles, S., and T. Hardjono, "The Group Domain
              of Interpretation", RFC 6407, DOI 10.17487/RFC6407,
              October 2011, <https://www.rfc-editor.org/info/rfc6407>.

   [RFC7296]  Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
              Kivinen, "Internet Key Exchange Protocol Version 2
              (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
              2014, <https://www.rfc-editor.org/info/rfc7296>.

   [RFC7634]  Nir, Y., "ChaCha20, Poly1305, and Their Use in the
              Internet Key Exchange Protocol (IKE) and IPsec", RFC 7634,
              DOI 10.17487/RFC7634, August 2015,
              <https://www.rfc-editor.org/info/rfc7634>.

   [RFC8221]  Wouters, P., Migault, D., Mattsson, J., Nir, Y., and T.
              Kivinen, "Cryptographic Algorithm Implementation
              Requirements and Usage Guidance for Encapsulating Security
              Payload (ESP) and Authentication Header (AH)", RFC 8221,
              DOI 10.17487/RFC8221, October 2017,
              <https://www.rfc-editor.org/info/rfc8221>.

10.2.  Informational References

   [BEAST]    Thai, T. and J. Juliano, "Here Come The xor Ninjas",  ,
              May 2011, <https://www.researchgate.net/
              publication/266529975_Here_Come_The_Ninjas>.

   [I-D.yeung-g-ikev2]
              Weis, B., Nir, Y., and V. Smyslov, "Group Key Management
              using IKEv2", draft-yeung-g-ikev2-13 (work in progress),
              March 2018.






Migault, et al.         Expires November 10, 2018               [Page 6]


Internet-Draft             Implicit IV in ESP                   May 2018


   [IANA]     "IANA IKEv2 Parameter - Type 1 - Encryption Algorithm
              Transform IDs", <https://www.iana.org/assignments/ikev2-
              parameters/ikev2-parameters.xhtml#ikev2-parameters-5>.

Authors' Addresses

   Daniel Migault
   Ericsson
   8275 Trans Canada Route
   Saint Laurent, QC H4S 0B6
   Canada

   Email: daniel.migault@ericsson.com


   Tobias Guggemos
   LMU Munich
   Oettingenstr. 67
   80538 Munich, Bavaria
   Germany

   Email: guggemos@mnm-team.org
   URI:   http://mnm-team.org/~guggemos


   Yoav Nir
   Dell EMC
   9 Andrei Sakharov St
   Haifa  3190500
   Israel

   Email: ynir.ietf@gmail.com



















Migault, et al.         Expires November 10, 2018               [Page 7]


Html markup produced by rfcmarkup 1.126, available from https://tools.ietf.org/tools/rfcmarkup/