Postquantum Preshared Keys for IKEv2
draft-fluhrer-qr-ikev2-03

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Last updated 2017-01-30 (latest revision 2016-10-28)
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Internet Engineering Task Force                               S. Fluhrer
Internet-Draft                                                 D. McGrew
Intended status: Informational                             P. Kampanakis
Expires: May 1, 2017                                       Cisco Systems
                                                        October 28, 2016

                  Postquantum Preshared Keys for IKEv2
                       draft-fluhrer-qr-ikev2-03

Abstract

   This document describes an extension of IKEv2 to allow it to be
   resistant to a Quantum Computer, by using preshared keys

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Fluhrer, et al.            Expires May 1, 2017                  [Page 1]
Internet-Draft       Postquantum Security for IKEv2         October 2016

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Changes . . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Assumptions . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Exchanges . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Creating Child SA Keying Material . . . . . . . . . . . . . .   5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     6.2.  Informational References  . . . . . . . . . . . . . . . .   7
   Appendix A.  Discussion and Rationale . . . . . . . . . . . . . .   7
   Appendix B.  Acknowledgement  . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   It is an open question whether or not it is feasible to build a
   quantum computer, but if it is, many of the cryptographic algorithms
   and protocols currently in use would be insecure.  A quantum computer
   would be able to solve DH and ECDH problems, and this would imply
   that the security of existing IKEv2 systems would be compromised.
   IKEv1 when used with preshared keys does not share this
   vulnerability, because those keys are one of the inputs to the key
   derivation function.  If the preshared key have sufficient entropy
   and the PRF and encryption and authentication transforms are
   postquantum secure, then the resulting system is believed to be
   quantum resistant, that is, believed to be invulnerable to an
   attacker with a Quantum Computer.

   This document describes a way to extend IKEv2 to have a similar
   property; assuming that the two end systems share a long secret key,
   then the resulting exchange is quantum resistant.  By bringing
   postquantum security to IKEv2, this note removes the need to use an
   obsolete version of the Internet Key Exchange in order to achieve
   that security goal.

   The general idea is that we add an additional secret that is shared
   between the initiator and the responder; this secret is in addition
   to the authentication method that is already provided within IKEv2.
   We stir in this secret when generating the key material (KEYMAT) keys
   for the child SAs (along with the parameters that IKEv2 normally
   uses); this secret provides quantum resistance to the IPsec SAs.

   It was considered important to minimize the changes to IKEv2.  The
   existing mechanisms to do authentication and key exchange remain in
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