Deprecation of IKEv1 and obsoleted algorithms
draft-ietf-ipsecme-ikev1-algo-to-historic-00

Document Type Active Internet-Draft (ipsecme WG)
Author Paul Wouters 
Last updated 2021-04-28
Replaces draft-pwouters-ikev1-ipsec-graveyard
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Network                                                  P. Wouters, Ed.
Internet-Draft                                                   No Hats
Updates: 7296, 8221, 8247 (if approved)                    27 April 2021
Intended status: Standards Track                                        
Expires: 29 October 2021

             Deprecation of IKEv1 and obsoleted algorithms
                draft-ietf-ipsecme-ikev1-algo-to-historic-00

Abstract

   Internet Key Exchange version 1 (IKEv1) is deprecated.  Accordingly,
   IKEv1 has been moved to Historic status.  A number of old algorithms
   that are associated with IKEv1, and not widely implemented for IKEv2
   are deprecated as well.  This document adds a Status column to the
   IANA IKEv2 Transform Type registries.

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 29 October 2021.

Copyright Notice

   Copyright (c) 2021 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
   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
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   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   2
   3.  RFC 2409 to Historic  . . . . . . . . . . . . . . . . . . . .   3
   4.  IKEv1 feature equivalents for IKEv2 . . . . . . . . . . . . .   3
     4.1.  IKEv2 postquantum support . . . . . . . . . . . . . . . .   3
     4.2.  IKEv2 Labeled IPsec support . . . . . . . . . . . . . . .   4
     4.3.  IKEv2 Group SA / Multicast support  . . . . . . . . . . .   4
   5.  Deprecating obsolete algorithms . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   IKEv1 [RFC2409] and its related documents for ISAKMP [RFC2408] and
   IPsec DOI [RFC2407] were obsoleted by IKEv2 [RFC4306] in December
   2005.  The latest version of IKEv2 at the time of writing was
   published in 2014 in [RFC7296].  The Internet Key Exchange (IKE)
   version 2 has replaced version 1 over 15 years ago.  IKEv2 has now
   seen wide deployment and provides a full replacement for all IKEv1
   functionality.  No new modifications or new algorithms have been
   accepted for IKEv1 for at least a decade.  IKEv2 addresses various
   issues present in IKEv1, such as IKEv1 being vulnerable to
   amplification attacks.  IKEv1 has been moved to Historic status.

   Algorithm implementation requirements and usage guidelines for IKEv2
   [RFC8247] and ESP/AH [RFC8223] gives guidance to implementors but
   limits that guidance to avoid broken or weak algorithms.  It does not
   deprecate algorithms that have aged and are not in use, but leave
   these algorithms in a state of "MAY be used".  This document
   deprecates those algorithms that are no longer advised but for which
   there are no known attacks resulting in their earlier deprecation.

2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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3.  RFC 2409 to Historic

   IKEv1 is deprecated.  Systems running IKEv1 should be upgraded and
   reconfigured to run IKEv2.  Systems that support IKEv1 but not IKEv2
   are most likely also unsuitable candidates for continued operation:

   *  A number of IKEv1 systems have reached their End of Life and
      therefor will never be patched by the vendor if a vulnerability is
      found.

   *  A number of vendors still provide updates for their equipment that
      supports IKEv1 and IKEv2, but have "frozen" their IKEv1
      implementation, and will never make any changes to it.  This also
      results in running unmaintained code and its associated security
      risks.

   *  IKEv1 systems can be abused for packet amplification attacks, see
      CVE-2016-5361.

   *  IKEv1 systems most likely do not support modern cryptographic
      algorithms.  AES-GCM is only defined for ESP and not IKE, and
      often not implemented for ESP.  And CHACHA20_POLY1305 is not
      defined for IKEv1.  Often, IKEv1 is configured with the very weak
      Diffie-Hellman Groups 2 and 5 and some implementatipons do not
      support any stronger alternatives.

   IKEv2 is a more secure protocol than IKEv1 in every aspect.
   IKEv1-only systems should be upgraded or replaced by systems
   supporting IKEv2.  IKEv1 configurations SHOULD NOT be directly
   translated to IKEv2 configurations without updating the cryptographic
   algorithms used.

4.  IKEv1 feature equivalents for IKEv2

   A few notably IKEv1 features are not present in the IKEv2 core
   specification [RFC7296] but are available for IKEv2 via an additional
   specification:

4.1.  IKEv2 postquantum support

   IKEv1 and its way of using Preshared Keys (PSKs) protects against
   quantum computer based attacks.  IKEv2 updated its use of PSK to
   improve the error reporting, but at the expense of post-quantum
   security.  If post-quantum security is required, these systems should
   be migrated to use IKEv2 Postquantum Preshared Keys (PPK) [RFC8784]

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4.2.  IKEv2 Labeled IPsec support

   Some IKEv1 implementations support Labeled IPsec, a method to
   negotiate an addition Security Context selector to the SPD, but this
   method was never standarized in IKEv1.  Those IKEv1 systems that
   require Labeled IPsec should migrate to an IKEv2 system supporting
   Labeled IPsec as specified in [draft-ietf-ipsecme-labeled-ipsec].

4.3.  IKEv2 Group SA / Multicast support

   In IKEv1, [RFC6407], [RFC3740], [RFC5374] define the support for
   Group SA and Multicast support.  For IKEv2, this work is currently in
   progress via [draft-ietf-ipsecme-g-ikev2]

5.  Deprecating obsolete algorithms

   This document deprecates the following algorithms:

   *  Encryption Algorithms: RC5, IDEA, CAST, Blowfish, and the
      unspecified 3IDEA, ENCR_DES_IV64 and ENCR_DES_IV32

   *  PRF Algorithms: the unspecified PRF_HMAC_TIGER

   *  Integrity Algorithms: HMAC-MD5-128

   *  Diffie-Hellman groups: none

6.  Security Considerations

   There are only security benefits by deprecating IKEv1 for IKEv2.

   The deprecated algorithms have long been in disuse and are no longer
   actively deployed or researched.  It presents an unknown security
   risk that is best avoided.  Additionally, these algorithms not being
   supported in implementations simplifies those implementations and
   reduces the accidental use of these deprecated algorithms through
   misconfiguration or downgrade attacks.

7.  IANA Considerations

   This document instructs IANA to add an additional Status column to
   the IKEv2 Transform Type registries and mark the following entries as
   DEPRECATED:

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             Transform Type 1 - Encryption Algorithm IDs

             Number    Name                Status
             ------    ---------------     ------
             1         ENCR_DES_IV64       DEPRECATED [this document]
             2         ENCR_DES            DEPRECATED [RFC8247]
             4         ENCR_RC5            DEPRECATED [this document]
             5         ENCR_IDEA           DEPRECATED [this document]
             6         ENCR_CAST           DEPRECATED [this document]
             7         ENCR_BLOWFISH       DEPRECATED [this document]
             8         ENCR_3IDEA          DEPRECATED [this document]
             9         ENCR_DES_IV32       DEPRECATED [this document]

                                  Figure 1

             Transform Type 2 - Pseudorandom Function Transform IDs

             Number    Name                Status
             ------    ------------        ----------
             1         PRF_HMAC_MD5        DEPRECATED [RFC8247]
             1         PRF_HMAC_TIGER      DEPRECATED [this document]

                                  Figure 2

             Transform Type 3 - Integrity Algorithm Transform IDs

             Number    Name                Status
             ------    -----------------   ----------
             1         AUTH_HMAC_MD5_96    DEPRECATED [RFC8247]
             3         AUTH_DES_MAC        DEPRECATED [RFC8247]
             4         AUTH_KPDK_MD5       DEPRECATED [RFC8247]
             6         AUTH_HMAC_MD5_128   DEPRECATED [this document]
             7         AUTH_HMAC_SHA1_160  DEPRECATED [this document]

                                  Figure 3

           Transform Type 4 - Diffie Hellman Group Transform IDs

           Number    Name                           Status
           ------    ----------------------------   ----------
           1         768-bit MODP Group             DEPRECATED [RFC8247]
           22        1024-bit MODP Group with
                     160-bit Prime Order Subgroup   DEPRECATED [RFC8247]

                                Figure 4

   All entries not mentioned here should receive no value in the new
   Status field.

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8.  Normative References

   [draft-ietf-ipsecme-g-ikev2]
              Smyslov, V. and B. Weis, "Group Key Management using
              IKEv2", Work in Progress, Internet-Draft, draft-ietf-
              ipsecme-labeled-ipsec, 11 January 2021,
              <https://tools.ietf.org/id/draft-ietf-ipsecme-labeled-
              ipsec-01.txt>.

   [draft-ietf-ipsecme-labeled-ipsec]
              Wouters, P. and S. Prasad, "Labeled IPsec Traffic Selector
              support for IKEv2", Work in Progress, Internet-Draft,
              draft-ietf-ipsecme-labeled-ipsec, 30 October 2020,
              <https://tools.ietf.org/id/draft-ietf-ipsecme-labeled-
              ipsec-01.txt>.

   [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>.

   [RFC2407]  Piper, D., "The Internet IP Security Domain of
              Interpretation for ISAKMP", RFC 2407,
              DOI 10.17487/RFC2407, November 1998,
              <https://www.rfc-editor.org/info/rfc2407>.

   [RFC2408]  Maughan, D., Schertler, M., Schneider, M., and J. Turner,
              "Internet Security Association and Key Management Protocol
              (ISAKMP)", RFC 2408, DOI 10.17487/RFC2408, November 1998,
              <https://www.rfc-editor.org/info/rfc2408>.

   [RFC2409]  Harkins, D. and D. Carrel, "The Internet Key Exchange
              (IKE)", RFC 2409, DOI 10.17487/RFC2409, November 1998,
              <https://www.rfc-editor.org/info/rfc2409>.

   [RFC3740]  Hardjono, T. and B. Weis, "The Multicast Group Security
              Architecture", RFC 3740, DOI 10.17487/RFC3740, March 2004,
              <https://www.rfc-editor.org/info/rfc3740>.

   [RFC4306]  Kaufman, C., Ed., "Internet Key Exchange (IKEv2)
              Protocol", RFC 4306, DOI 10.17487/RFC4306, December 2005,
              <https://www.rfc-editor.org/info/rfc4306>.

   [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>.

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   [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>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8223]  Esale, S., Torvi, R., Jalil, L., Chunduri, U., and K.
              Raza, "Application-Aware Targeted LDP", RFC 8223,
              DOI 10.17487/RFC8223, August 2017,
              <https://www.rfc-editor.org/info/rfc8223>.

   [RFC8247]  Nir, Y., Kivinen, T., Wouters, P., and D. Migault,
              "Algorithm Implementation Requirements and Usage Guidance
              for the Internet Key Exchange Protocol Version 2 (IKEv2)",
              RFC 8247, DOI 10.17487/RFC8247, September 2017,
              <https://www.rfc-editor.org/info/rfc8247>.

   [RFC8784]  Fluhrer, S., Kampanakis, P., McGrew, D., and V. Smyslov,
              "Mixing Preshared Keys in the Internet Key Exchange
              Protocol Version 2 (IKEv2) for Post-quantum Security",
              RFC 8784, DOI 10.17487/RFC8784, June 2020,
              <https://www.rfc-editor.org/info/rfc8784>.

Author's Address

   Paul Wouters (editor)
   No Hats

   Email: paul@nohats.ca

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