path: root/doc/rfc/rfc6071.txt

Internet Engineering Task Force (IETF)                        S. Frankel
Request for Comments: 6071                                          NIST
Obsoletes: 2411                                              S. Krishnan
Category: Informational                                         Ericsson
ISSN: 2070-1721                                            February 2011


  IP Security (IPsec) and Internet Key Exchange (IKE) Document Roadmap

Abstract

   Over the past few years, the number of RFCs that define and use IPsec
   and Internet Key Exchange (IKE) has greatly proliferated.  This is
   complicated by the fact that these RFCs originate from numerous IETF
   working groups: the original IPsec WG, its various spin-offs, and
   other WGs that use IPsec and/or IKE to protect their protocols'
   traffic.

   This document is a snapshot of IPsec- and IKE-related RFCs.  It
   includes a brief description of each RFC, along with background
   information explaining the motivation and context of IPsec's
   outgrowths and extensions.  It obsoletes RFC 2411, the previous "IP
   Security Document Roadmap."

   The obsoleted IPsec roadmap (RFC 2411) briefly described the
   interrelationship of the various classes of base IPsec documents.
   The major focus of RFC 2411 was to specify the recommended contents
   of documents specifying additional encryption and authentication
   algorithms.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6071.






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Copyright Notice

   Copyright (c) 2011 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
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   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
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   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1. Introduction ....................................................4
   2. IPsec/IKE Background Information ................................5
      2.1. Interrelationship of IPsec/IKE Documents ...................5
      2.2. Versions of IPsec ..........................................6
           2.2.1. Differences between "Old" IPsec (IPsec-v2) and
                  "New" IPsec (IPsec-v3) ..............................6
      2.3. Versions of IKE ............................................7
           2.3.1. Differences between IKEv1 and IKEv2 .................8
      2.4. IPsec and IKE IANA Registries ..............................9
   3. IPsec Documents .................................................9
      3.1. Base Documents .............................................9
           3.1.1. "Old" IPsec (IPsec-v2) ..............................9
           3.1.2. "New" IPsec (IPsec-v3) .............................11
      3.2. Additions to IPsec ........................................11
      3.3. General Considerations ....................................14
   4. IKE Documents ..................................................15
      4.1. Base Documents ............................................15
           4.1.1. IKEv1 ..............................................15
           4.1.2. IKEv2 ..............................................16



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      4.2. Additions and Extensions ..................................17
           4.2.1. Peer Authentication Methods ........................17
           4.2.2. Certificate Contents and Management (PKI4IPsec) ....18
           4.2.3. Dead Peer Detection ................................19
           4.2.4. Remote Access ......................................19
   5. Cryptographic Algorithms and Suites ............................21
      5.1. Algorithm Requirements ....................................22
      5.2. Encryption Algorithms .....................................23
      5.3. Integrity-Protection (Authentication) Algorithms ..........27
      5.4. Combined Mode Algorithms ..................................30
      5.5. Pseudo-Random Functions (PRFs) ............................33
      5.6. Cryptographic Suites ......................................34
      5.7. Diffie-Hellman Algorithms .................................35
   6. IPsec/IKE for Multicast ........................................36
   7. Outgrowths of IPsec/IKE ........................................38
      7.1. IPsec Policy ..............................................38
      7.2. IPsec MIBs ................................................39
      7.3. IPComp (Compression) ......................................39
      7.4. Better-Than-Nothing Security (BTNS) .......................39
      7.5. Kerberized Internet Negotiation of Keys (KINK) ............40
      7.6. IPsec Secure Remote Access (IPSRA) ........................41
      7.7. IPsec Keying Information Resource Record (IPSECKEY) .......42
   8. Other Protocols That Use IPsec/IKE .............................42
      8.1. Mobile IP (MIPv4 and MIPv6) ...............................42
      8.2. Open Shortest Path First (OSPF) ...........................44
      8.3. Host Identity Protocol (HIP) ..............................45
      8.4. Stream Control Transmission Protocol (SCTP) ...............46
      8.5. Robust Header Compression (ROHC) ..........................46
      8.6. Border Gateway Protocol (BGP) .............................47
      8.7. IPsec Benchmarking ........................................47
      8.8. Network Address Translators (NAT) .........................48
      8.9. Session Initiation Protocol (SIP) .........................48
      8.10. Explicit Packet Sensitivity Labels .......................49
   9. Other Protocols That Adapt IKE for Non-IPsec Functionality .....49
      9.1. Extensible Authentication Protocol (EAP) ..................49
      9.2. Fibre Channel .............................................49
      9.3. Wireless Security .........................................50
   10. Acknowledgements ..............................................50
   11. Security Considerations .......................................50
   12. References ....................................................50
      12.1. Informative References ...................................50
   Appendix A.  Summary of Algorithm Requirement Levels ..............61









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1.  Introduction

   IPsec (Internet Protocol Security) is a suite of protocols that
   provides security to Internet communications at the IP layer.  The
   most common current use of IPsec is to provide a Virtual Private
   Network (VPN), either between two locations (gateway-to-gateway) or
   between a remote user and an enterprise network (host-to-gateway); it
   can also provide end-to-end, or host-to-host, security.  IPsec is
   also used by other Internet protocols (e.g., Mobile IP version 6
   (MIPv6)) to protect some or all of their traffic.  IKE (Internet Key
   Exchange) is the key negotiation and management protocol that is most
   commonly used to provide dynamically negotiated and updated keying
   material for IPsec.  IPsec and IKE can be used in conjunction with
   both IPv4 and IPv6.

   In addition to the base documents for IPsec and IKE, there are
   numerous RFCs that reference, extend, and in some cases alter the
   core specifications.  This document obsoletes [RFC2411].  It attempts
   to list and briefly describe those RFCs, providing context and
   rationale where indicated.  The title of each RFC is followed by a
   letter that indicates its category in the RFC series [RFC2026], as
   follows:

      o S: Standards Track (Proposed Standard, Draft Standard, or
           Standard)

      o E: Experimental

      o B: Best Current Practice

      o I: Informational

   For each RFC, the publication date is also given.

   This document also categorizes the requirements level of each
   cryptographic algorithm for use with IKEv1, IKEv2, IPsec-v2, and
   IPsec-v3.  These requirements are summarized in Appendix A.  These
   levels are current as of February 2011; subsequent RFCs may result in
   altered requirement levels.

   This document does not define requirement levels; it simply restates
   those found in the IKE and IPsec RFCs.  If there is a conflict
   between this document and any other RFC, then the other RFC takes
   precedence.

   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].



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2.  IPsec/IKE Background Information

2.1.  Interrelationship of IPsec/IKE Documents

   The main documents describing the set of IPsec protocols are divided
   into seven groups.  This is illustrated in Figure 1.  There is a main
   Architecture document that broadly covers the general concepts,
   security requirements, definitions, and mechanisms defining IPsec
   technology.

   There are an Encapsulating Security Payload (ESP) Protocol document
   and an Authentication Header (AH) Protocol document that cover the
   packet format and general issues regarding the respective protocols.
   The "Encryption Algorithm" document set, shown on the left, is the
   set of documents describing how various encryption algorithms are
   used for ESP.  The "Combined Algorithm" document set, shown in the
   middle, is the set of documents describing how various combined mode
   algorithms are used to provide both encryption and integrity
   protection for ESP.  The "Integ-Protection Algorithm" document set,
   shown on the right, is the set of documents describing how various
   integrity-protection algorithms are used for both ESP and AH.

   The "IKE" documents, shown at the bottom, are the documents
   describing the IETF Standards-Track key management schemes.



























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                             +--------------+
                             | Architecture |
                             +--------------+
                                v         v
               +<-<-<-<-<-<-<-<-+         +->->->->->->->->+
               v                                           v
      +----------+                                      +----------+
      |   ESP    |                                      |    AH    |
      | Protocol |                                      | Protocol |
      +----------+                                      +----------+
        v      v                                          v       v
        v      +->->->->->->->->+->->->->->->->->+        v       v
        v      v                v                v        v       v
        v      v                v                v        v       v
        v  +------------+   +-----------+    +----------------+   v
        v  | +------------+ | +------------+ | +----------------+ v
        v  | | Encryption | | | Combined   | | |Integ-Protection| v
        v  +-| Algorithm  | +-| Algorithm  | +-| Algorithm      | v
        v    +------------+   +------------+   +----------------+ v
        v        v                  v                   v         v
        v        v                  v                   v         v
        +>->->->-+->->->->->->->->->--<-<-<-<-<-<-<-<-<-+-<-<-<-<-+
                                    ^
                                    ^
                              +------------+
                              |    IKE     |
                              |  Protocol  |
                              +------------+

               Figure 1. IPsec/IKE Document Interrelationships

2.2.  Versions of IPsec

   Two versions of IPsec can currently be found in implementations.  The
   "new" IPsec (referred to as IPsec-v3 in this document; see Section
   3.1.1 for the RFC descriptions) obsoleted the "old" IPsec (referred
   to as IPsec-v2 in this document; see Section 3.1.2 for the RFC
   descriptions); however, IPsec-v2 is still commonly found in
   operational use.  In this document, when the unqualified term IPsec
   is used, it pertains to both versions of IPsec.  An earlier version
   of IPsec (defined in RFCs 1825-1829), obsoleted by IPsec-v2, is not
   covered in this document.

2.2.1.  Differences between "Old" IPsec (IPsec-v2) and "New" IPsec
        (IPsec-v3)

   IPsec-v3 incorporates "lessons learned" from implementation and
   operational experience with IPsec-v2 and its predecessor, IPsec-v1.



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   Knowledge was gained about the barriers to IPsec deployment, the
   scenarios in which IPsec is most effective, and the requirements that
   needed to be added to IPsec to facilitate its use with other
   protocols.  In addition, the documentation for IPsec-v3 clarifies and
   expands details that were underspecified or ambiguous in IPsec-v2.

   Changes to the architecture document [RFC4301] include:

      o More detailed descriptions of IPsec processing, both unicast and
        multicast, and the interactions among the various IPsec
        databases

      o In IPsec-v2, an SA (Security Association) is uniquely identified
        by a combination of the SPI (Security Parameters Index),
        protocol (ESP or AH) and the destination address.  In IPsec-v3,
        a unicast SA is uniquely identified by the SPI and, optionally,
        by the protocol; a multicast SA is identified by a combination
        of the SPI and the destination address and, optionally, the
        source address.

      o More flexible SPD (Security Policy Database) selectors,
        including ranges of values and ICMP message types as selectors

      o Decorrelated (order-independent) SAD (Security Association
        Database) replaced the former ordered SAD

      o Extended sequence numbers (ESNs) were added

      o Mandatory algorithms defined in standalone document

      o AH [RFC4302] is mandatory to implement (MUST) in IPsec-v2,
        optional (MAY) in IPsec-v3

   Changes to ESP [RFC4303] include:

      o Combined mode algorithms were added, necessitating changes to
        packet format and processing

      o NULL authentication, mandatory (MUST) in ESP-v2, is optional
        (MAY) in ESP-v3

2.3.  Versions of IKE

   Two versions of IKE can currently be found in implementations.  The
   "new" IKE (generally referred to as IKEv2) obsoleted the "old" IKE
   (generally referred to as IKEv1); however, IKEv1 is still commonly
   found in operational use.  In this document, when the unqualified
   term IKE is used, it pertains to both versions of IKE.



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2.3.1.  Differences between IKEv1 and IKEv2

   As with IPsec-v3, IKEv2 incorporates "lessons learned" from
   implementation and operational experience with IKEv1.  Knowledge was
   gained about the barriers to IKE deployment, the scenarios in which
   IKE is most effective, and the requirements that needed to be added
   to IKE to facilitate its use with other protocols as well as in
   general-purpose use.  The documentation for IKEv2 replaces multiple,
   at times contradictory, documents with a single document; it also
   clarifies and expands details that were underspecified or ambiguous
   in IKEv1.

   Once an IKE negotiation is successfully completed, the peers have
   established two pairs of one-way (inbound and outbound) SAs.  Since
   IKE always negotiates pairs of SAs, the term "SA" is generally used
   to refer to a pair of SAs (e.g., an "IKE SA" or an "IPsec SA" is in
   reality a pair of one-way SAs).  The first SA, the IKE SA, is used to
   protect IKE traffic.  The second SA provides IPsec protection to data
   traffic between the peers and/or other devices for which the peers
   are authorized to negotiate.  It is called the IPsec SA in IKEv1 and,
   in the IKEv2 RFCs, it is referred to variously as a CHILD_SA, a child
   SA, and an IPsec SA.  This document uses the term "IPsec SA".  To
   further complicate the terminology, since IKEv1 consists of two
   sequential negotiations, called phases, the IKE SA is also referred
   to as a Phase 1 SA and the IPsec SA is referred to as a Phase 2 SA.

   Changes to IKE include:

      o Replaced multiple alternate exchange types with a single,
        shorter exchange

      o Streamlined negotiation format to avoid combinatorial bloat for
        multiple proposals

      o Protect responder from committing significant resources to the
        exchange until the initiator's existence and identity are
        confirmed

      o Reliable exchanges: every request expects a response

      o Protection of IKE messages based on ESP, rather than a method
        unique to IKE

      o Add traffic selectors: distinct from peer IDs and more flexible

      o Support of EAP-based authentication methods and asymmetric
        authentication (i.e., initiator and responder can use different
        authentication methods)



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2.4.  IPsec and IKE IANA Registries

   Numerous IANA registries contain values that are used in IPsec, IKE,
   and related protocols.  They include:

      o  IKE Attributes
         (http://www.iana.org/assignments/ipsec-registry): values used
         during IKEv1 Phase 1 exchanges, defined in [RFC2409].

      o  "Magic Numbers" for Internet Security Association and Key
         Management Protocol (ISAKMP)
         (http://www.iana.org/assignments/isakmp-registry): values used
         during IKEv1 Phase 2 exchanges, defined in [RFC2407],
         [RFC2408], and numerous other cryptographic algorithm RFCs.

      o  IKEv2 Parameters
         (http://www.iana.org/assignments/ikev2-parameters): values used
         in IKEv2 exchanges, defined in [RFC5996] and numerous other
         cryptographic algorithm RFCs.

      o  Cryptographic Suites for IKEv1, IKEv2, and IPsec
         (http://www.iana.org/assignments/crypto-suites): names of
         cryptographic suites in [RFC4308] and [RFC4869].

3.  IPsec Documents

3.1.  Base Documents

   IPsec protections are provided by two special headers: the
   Encapsulating Security Payload (ESP) Header and the Authentication
   Header (AH).  In IPv4, these headers take the form of protocol
   headers; in IPv6, they are classified as extension headers.  There
   are three base IPsec documents: one that describes the IP security
   architecture, and one for each of the IPsec headers.

3.1.1.  "Old" IPsec (IPsec-v2)

3.1.1.1.  RFC 2401, Security Architecture for the Internet Protocol
          (S, November 1998)

   [RFC2401] specifies the mechanisms, procedures, and components
   required to provide security services at the IP layer.  It also
   describes their interrelationship and the general processing required
   to inject IPsec protections into the network architecture.







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   The components include:

      - SA (Security Association): a one-way (inbound or outbound)
        agreement between two communicating peers that specifies the
        IPsec protections to be provided to their communications.  This
        includes the specific security protections, cryptographic
        algorithms, and secret keys to be applied, as well as the
        specific types of traffic to be protected.

      - SPI (Security Parameters Index): a value that, together with the
        destination address and security protocol (AH or ESP), uniquely
        identifies a single SA.

      - SAD (Security Association Database): each peer's SA repository.
        The RFC describes how this database functions (SA lookup, etc.)
        and the types of information it must contain to facilitate SA
        processing; it does not dictate the format or layout of the
        database.  SAs can be established in either transport mode or
        tunnel mode (see below).

      - SPD (Security Policy Database): an ordered database that
        expresses the security protections to be afforded to different
        types and classes of traffic.  The three general classes of
        traffic are traffic to be discarded, traffic that is allowed
        without IPsec protection, and traffic that requires IPsec
        protection.

   RFC 2401 describes general inbound and outbound IPsec processing; it
   also includes details on several special cases: packet fragments,
   ICMP messages, and multicast traffic.

3.1.1.2.  RFC 2402, IP Authentication Header (S, November 1998)

   [RFC2402] defines the Authentication Header (AH), which provides
   integrity protection; it also provides data-origin authentication,
   access control, and, optionally, replay protection.  A transport mode
   AH SA, used to protect peer-to-peer communications, protects upper-
   layer data, as well as those portions of the IP header that do not
   vary unpredictably during packet delivery.  A tunnel mode AH SA can
   be used to protect gateway-to-gateway or host-to-gateway traffic; it
   can optionally be used for host-to-host traffic.  This class of AH SA
   protects the inner (original) header and upper-layer data, as well as
   those portions of the outer (tunnel) header that do not vary
   unpredictably during packet delivery.  Because portions of the IP
   header are not included in the AH calculations, AH processing is more
   complex than ESP processing.  AH also does not work in the presence
   of Network Address Translation (NAT).  Unlike IPsec-v3, IPsec-v2
   classifies AH as mandatory to implement.



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3.1.1.3.  RFC 2406, IP Encapsulating Security Payload (ESP)
          (S, November 1998)

   [RFC2406] defines the IP Encapsulating Security Payload (ESP), which
   provides confidentiality (encryption) and/or integrity protection; it
   also provides data-origin authentication, access control, and,
   optionally, replay and/or traffic analysis protection.  A transport
   mode ESP SA protects the upper-layer data, but not the IP header.  A
   tunnel mode ESP SA protects the upper-layer data and the inner
   header, but not the outer header.

3.1.2.  "New" IPsec (IPsec-v3)

3.1.2.1.  RFC 4301, Security Architecture for the Internet Protocol
          (S, December 2005)

   [RFC4301] obsoletes [RFC2401], and it includes a more complete and
   detailed processing model.  The most notable changes are detailed
   above in Section 2.2.1.  IPsec-v3 processing incorporates an
   additional database:

      - PAD (Peer Authorization Database): contains information
        necessary to conduct peer authentication, providing a link
        between IPsec and the key management protocol (e.g., IKE)

3.1.2.2.  RFC 4302, IP Authentication Header (S, December 2005)

   [RFC4302] obsoletes [RFC2402].  Unlike IPsec-v2, IPsec-v3 classifies
   AH as optional.

3.1.2.3.  RFC 4303, IP Encapsulating Security Payload (ESP)
          (S, December 2005)

   [RFC4303] obsoletes [RFC2406].  The most notable changes are detailed
   above in Section 2.2.1.

3.2.  Additions to IPsec

   Once the IKEv1 and IPsec-v2 RFCs were finalized, several additions
   were defined in separate documents: negotiation of NAT traversal,
   extended sequence numbers, UDP encapsulation of ESP packets,
   opportunistic encryption, and IPsec-related ICMP messages.
   Additional uses of IPsec transport mode were also described:
   protection of manually configured IPv6-in-IPv4 tunnels and protection
   of IP-in-IP tunnels.  These documents describe atypical uses of IPsec
   transport mode, but do not define any new IPsec features.





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   Once the original IPsec Working Group concluded, additional IPsec-
   related issues were handled by the IPsecME (IPsec Maintenance and
   Extensions) Working Group.  One such problem is the capability of
   middleboxes to distinguish unencrypted ESP packets (ESP-NULL) from
   encrypted ones in a fast and accurate manner.  Two solutions are
   described: a new protocol that requires changes to IKEv2 and IPsec-v3
   and a heuristic method that imposes no new requirements.  Another
   issue that was addressed is the problem of using IKE and IPsec in a
   high-availability environment.

3.2.1.  RFC 3947, Negotiation of NAT-Traversal in the IKE
        (S, January 2005)

   [RFC3947] defines an optional extension to IKEv1.  It enables IKEv1
   to detect whether there are any NATs between the negotiating peers
   and whether both peers support NAT traversal.  It also describes how
   IKEv1 can be used to negotiate the use of UDP encapsulation of ESP
   packets for the IPsec SA.  For IKEv2, this capability is described in
   [RFC5996].

3.2.2.  RFC 3948, UDP Encapsulation of IPsec ESP Packets
        (S, January 2005)

   [RFC3948] is an optional extension for IPsec-v2 and IPsec-v3.  It
   defines how to encapsulate ESP packets in UDP packets to enable the
   traversal of NATs that discard packets with protocols other than UDP
   or TCP.  This makes it possible for ESP packets to pass through the
   NAT device without requiring any change to the NAT device itself.
   The use of this solution is negotiated by IKE, as described in
   [RFC3947] for IKEv1 and [RFC5996] for IKEv2.

3.2.3.  RFC 4304, Extended Sequence Number (ESN) Addendum to IPsec
        Domain of Interpretation (DOI) for Internet Security Association
        and Key Management Protocol (ISAKMP) (S, December 2005)

   The use of ESNs allows IPsec to use 64-bit sequence numbers for
   replay protection, but to send only 32 bits of the sequence number in
   the packet, enabling shorter packets and avoiding a redesign of the
   packet format.  The larger sequence numbers allow an existing IPsec
   SA to be used for larger volumes of data.  [RFC4304] describes an
   optional extension to IKEv1 that enables IKEv1 to negotiate the use
   of ESNs for IPsec SAs.  For IKEv2, this capability is described in
   [RFC5996].








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3.2.4.  RFC 4322, Opportunistic Encryption using the Internet Key
        Exchange (IKE) (I, December 2005)

   Opportunistic encryption allows a pair of end systems to use
   encryption without any specific pre-arrangements.  [RFC4322]
   specifies a mechanism that uses DNS to distribute the public keys of
   each system involved and uses DNS Security (DNSSEC) to secure the
   mechanism against active attackers.  It specifies the changes that
   are needed in existing IPsec and IKE implementations.  The majority
   of the changes are needed in the IKE implementation and these changes
   relate to the handling of key acquisition requests, the lookup of
   public keys and TXT records, and the interactions with firewalls and
   other security facilities that may be co-resident on the same
   gateway.

3.2.5.  RFC 4891, Using IPsec to Secure IPv6-in-IPv4 Tunnels
        (I, May 2007)

   [RFC4891] describes how to use IKE and transport-mode IPsec to
   provide security protection to manually configured IPv6-in-IPv4
   tunnels.  This document uses standard IKE and IPsec, without any new
   extensions.  It does not apply to tunnels that are initiated in an
   automated manner (e.g., 6to4 tunnels [RFC3056]).

3.2.6.  RFC 3884, Use of IPsec Transport Mode for Dynamic Routing
        (I, September 2004)

   [RFC3884] describes the use of transport-mode IPsec to secure IP-in-
   IP tunnels, which constitute the links of a multi-hop, distributed
   virtual network (VN).  This allows the traffic to be dynamically
   routed via the VN's trusted routers, rather than routing all traffic
   through a statically routed IPsec tunnel.  This RFC has not been
   widely adopted.

3.2.7.  RFC 5840, Wrapped Encapsulating Security Payload (ESP) for
        Traffic Visibility  (S, April 2010)

   ESP, as defined in [RFC4303], does not allow a network device to
   easily determine whether protected traffic that is passing through
   the device is encrypted or only integrity protected (referred to as
   ESP-NULL packets).  [RFC5840] extends ESPv3 to provide explicit
   notification of integrity-protected packets, and extends IKEv2 to
   negotiate this capability between the IPsec peers.








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3.2.8.  RFC 5879, Heuristics for Detecting ESP-NULL packets
        (I, May 2010)

   [RFC5879] offers an alternative approach to differentiating between
   ESP-encrypted and ESP-NULL packets through packet inspection.  This
   method does not require any change to IKE or ESP; it can be used with
   ESP-v2 or ESP-v3.

3.3.  General Considerations

3.3.1.  RFC 3715, IPsec-Network Address Translation (NAT) Compatibility
        Requirements (I, March 2004)

   [RFC3715] "describes known incompatibilities between NAT and IPsec,
   and describes the requirements for addressing them".  This is a
   critical issue, since IPsec is frequently used to provide VPN access
   to the corporate network for telecommuters, and NATs are widely
   deployed in home gateways, hotels, and other access networks
   typically used for remote access.

3.3.2.  RFC 5406, Guidelines for Specifying the Use of IPsec Version 2
        (B, February 2009)

   [RFC5406] offers guidance to protocol designers on how to ascertain
   whether IPsec is the appropriate security mechanism to provide an
   interoperable security solution for the protocol.  If this is not the
   case, it advises against attempting to define a new security
   protocol; rather, it suggests using another standards-based security
   protocol.  The details in this document apply only to IPsec-v2.

3.3.3.  RFC 2521, ICMP Security Failures Messages (E, March 1999)

   [RFC2521] specifies an ICMP message for indicating failures related
   to the use of IPsec protocols (AH and ESP).  The specified ICMP
   message defines several codes for handling common failure modes for
   IPsec.  The failures that are signaled by this message include
   invalid or expired SPIs, failure of authenticity or integrity checks
   on datagrams, decryption and decompression errors, etc.  These
   messages can be used to trigger automated session-key management or
   to signal to an operator the need to manually reconfigure the SAs.
   This RFC has not been widely adopted.  Furthermore, [RFC4301]
   discusses the pros and cons of relying on unprotected ICMP messages.

3.3.4.  RFC 6027, IPsec Cluster Problem Statement (I, October 2010)

   [RFC6027] describes the problems of using IKE and IPsec in a high
   availability environment, in which one or both of the peers are
   clusters of gateways.  It details the numerous types of stateful



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   information shared by IKE and IPsec peers that would have to be
   available to other members of the cluster in order to provide high-
   availability, load sharing, and/or failover capabilities.

4.  IKE Documents

4.1.  Base Documents

4.1.1.  IKEv1

   IKE is the preferred key management protocol for IPsec.  It is used
   for peer authentication; to negotiate, modify, and delete SAs; and to
   negotiate authenticated keying material for use within those SAs.
   The standard peer authentication methods used by IKEv1 (pre-shared
   secret keys and digital certificates) had several shortcomings
   related to use of IKEv1 to enable remote user authentication to a
   corporate VPN: it could not leverage the use of legacy authentication
   systems (e.g. RADIUS databases) to authenticate a remote user to a
   security gateway; and it could not be used to configure remote users
   with network addresses or other information needed in order to access
   the internal network.  Automatic key distribution is required for
   IPsec-v2, but alternatives to IKE may be used to satisfy that
   requirement.

   Several Internet Drafts were written to address these problems: two
   such documents include "Extended Authentication within IKE (XAUTH)"
   [IKE-XAUTH] (and its predecessor, "Extended Authentication within
   ISAKMP/Oakley (XAUTH)" [ISAKMP-XAUTH]) and "The ISAKMP Configuration
   Method" [IKE-MODE-CFG] (and its predecessor [ISAKMP-MODE-CFG]).
   These Internet Drafts did not progress to RFC status due to security
   flaws and other problems related to these solutions.  However, many
   current IKEv1 implementations incorporate aspects of these solutions
   to facilitate remote user access to corporate VPNs.  These solutions
   were not standardized, and different implementations implemented
   different versions.  Thus, there is no assurance that the
   implementations adhere fully to the suggested solutions or that one
   implementation can interoperate with others that claim to incorporate
   the same features.  Furthermore, these solutions have known security
   issues.  All of those problems and security issues have been solved
   in IKEv2; thus, use of these non-standardized IKEv1 solutions is not
   recommended.

4.1.1.1.  RFC 2409, The Internet Key Exchange (IKE) (S, November 1998)

   This document defines a key exchange protocol that can be used to
   negotiate authenticated keying material for SAs.  This document
   implements a subset of the Oakley protocol in conjunction with ISAKMP
   to obtain authenticated keying material for use with ISAKMP, and for



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   other security associations such as AH and ESP for the IETF IPsec
   DOI.  While, historically, IKEv1 was created by combining two
   security protocols, ISAKMP and Oakley, in practice, the combination
   (along with the IPsec DOI) has commonly been viewed as one protocol,
   IKEv1.  The protocol's origins can be seen in the organization of the
   documents that define it.

4.1.1.2.  RFC 2408, Internet Security Association and Key Management
          Protocol (ISAKMP) (S, November 1998)

   This document defines procedures and packet formats to establish,
   negotiate, modify, and delete Security Associations (SAs).  It is
   intended to support the negotiation of SAs for security protocols at
   all layers of the network stack.  ISAKMP can work with many different
   key exchange protocols, each with different security properties.

4.1.1.3.  RFC 2407, The Internet IP Security Domain of Interpretation
          for ISAKMP (S, November 1998)

   Within ISAKMP, a Domain of Interpretation is used to group related
   protocols using ISAKMP to negotiate security associations.  Security
   protocols sharing a DOI choose security protocol and cryptographic
   transforms from a common namespace and share key exchange protocol
   identifiers.  This document defines the Internet IP Security DOI
   (IPSEC DOI), which instantiates ISAKMP for use with IP when IP uses
   ISAKMP to negotiate security associations.

4.1.1.4.  RFC 2412, The OAKLEY Key Determination Protocol
          (I, November 1998)

   [RFC2412] describes a key establishment protocol that two
   authenticated parties can use to agree on secure and secret keying
   material.  The Oakley protocol describes a series of key exchanges --
   called "modes" -- and details the services provided by each (e.g.,
   perfect forward secrecy for keys, identity protection, and
   authentication).  This document provides additional theory and
   background to explain some of the design decisions and security
   features of IKE and ISAKMP; it does not include details necessary for
   the implementation of IKEv1.

4.1.2.  IKEv2

4.1.2.1.  RFC 4306, Internet Key Exchange (IKEv2) Protocol
          (S, December 2005)

   This document contains the original description of version 2 of the
   Internet Key Exchange (IKE) protocol.  It covers what was previously
   covered by separate documents: ISAKMP, IKE, and DOI.  It also



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   addresses NAT traversal, legacy authentication, and remote address
   acquisition.  IKEv2 is not interoperable with IKEv1.  Automatic key
   distribution is required for IPsec-v3, but alternatives to IKE may be
   used to satisfy that requirement.  This document has been superseded
   by [RFC5996].

4.1.2.2.  RFC 4718, IKEv2 Clarifications and Implementation Guidelines
          (I, October 2006)

   [RFC4718] clarifies many areas of the original IKEv2 specification
   [RFC4306] that were seen as potentially difficult to understand for
   developers who were not intimately familiar with the specification
   and its history.  It does not introduce any changes to the protocol,
   but rather provides descriptions that are less prone to ambiguous
   interpretations.  The goal of this document was to encourage the
   development of interoperable implementations.  The clarifications in
   this document have been included in the new version of the IKEv2
   specification [RFC5996].

4.1.2.3.  RFC 5996, Internet Key Exchange Protocol Version 2 (IKEv2)
          (S, September 2010)

   [RFC5996] combines the original IKEv2 RFC [RFC4306] with the
   Clarifications RFC [RFC4718], and resolves many implementation issues
   discovered by the community since the publication of these two
   documents.  This document was developed by the IPsecME (IPsec
   Maintenance and Extensions) Working Group, after the conclusion of
   the original IPsec Working Group.  Automatic key distribution is
   required for IPsec-v3, but alternatives to IKE may be used to satisfy
   that requirement.

4.2.  Additions and Extensions

4.2.1.  Peer Authentication Methods

4.2.1.1.  RFC 4478, Repeated Authentication in Internet Key Exchange
          (IKEv2) Protocol (E, April 2006)

   [RFC4478] addresses a problem unique to remote access scenarios.  How
   can the gateway (the IKE responder) force the remote user (the IKE
   initiator) to periodically reauthenticate, limiting the damage in the
   case where an unauthorized user gains physical access to the remote
   host? This document defines a new status notification, that a
   responder can send to an initiator, which notifies the initiator that
   the IPsec SA will be revoked unless the initiator reauthenticates
   within a specified period of time.  This optional extension applies
   only to IKEv2, not to IKEv1.




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4.2.1.2.  RFC 4739, Multiple Authentication Exchanges in the Internet
          Key Exchange (IKEv2) Protocol (E, November 2006)

   IKEv2 supports several mechanisms for authenticating the parties but
   each endpoint uses only one of these mechanisms to authenticate
   itself.  [RFC4739] specifies an extension to IKEv2 that allows the
   use of multiple authentication exchanges, using either different
   mechanisms or the same mechanism.  This extension allows, for
   instance, performing certificate-based authentication of the client
   host followed by an EAP authentication of the user.  This also allows
   for authentication by multiple administrative domains, if needed.
   This optional extension applies only to IKEv2, not to IKEv1.

4.2.1.3.  RFC 4754, IKE and IKEv2 Authentication Using the Elliptic
          Curve Digital Signature Algorithm (ECDSA) (S, January 2007)

   [RFC4754] describes how the Elliptic Curve Digital Signature
   Algorithm (ECDSA) may be used as the authentication method within the
   IKEv1 and IKEv2 protocols.  ECDSA provides many benefits including
   computational efficiency, small signature sizes, and minimal
   bandwidth compared to other available digital signature methods like
   RSA and DSA.  This optional extension applies to both IKEv1 and
   IKEv2.

4.2.1.4.  RFC 5998, An Extension for EAP-Only Authentication in IKEv2
          (S, September 2010)

   IKEv2 allows an initiator to use EAP for peer authentication, but
   requires the responder to authenticate through the use of a digital
   signature.  [RFC5998] extends IKEv2 so that EAP methods that provide
   mutual authentication and key agreement can also be used to provide
   peer authentication for the responder.  This optional extension
   applies only to IKEv2, not to IKEv1.

4.2.2.  Certificate Contents and Management (PKI4IPsec)

   The format, contents, and interpretation of Public Key Certificates
   (PKCs) proved to be a source of interoperability problems within IKE
   and IPsec.  PKI4IPsec was an attempt to set in place some common
   procedures and interpretations to mitigate those problems.

4.2.2.1.  RFC 4809, Requirements for an IPsec Certificate Management
          Profile (I, February 2007)

   [RFC4809] enumerates requirements for Public Key Certificate (PKC)
   lifecycle transactions between different VPN System and PKI System
   products in order to better enable large scale, PKI-enabled IPsec




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   deployments with a common set of transactions.  This document
   discusses requirements for both the IPsec and the PKI products.
   These optional requirements apply to both IKEv1 and IKEv2.

4.2.2.2.  RFC 4945, The Internet IP Security PKI Profile of
          IKEv1/ISAKMP, IKEv2, and PKIX (S, August 2007)

   [RFC4945] defines a profile of the IKE and Public Key Infrastructure
   using X.509 (PKIX) frameworks in order to provide an agreed-upon
   standard for using PKI technology in the context of IPsec.  It also
   documents the contents of the relevant IKE payloads and further
   specifies their semantics.  In addition, it summarizes the current
   state of implementations and deployment and provides advice to avoid
   common interoperability issues.  This optional extension applies to
   both IKEv1 and IKEv2.

4.2.2.3.  RFC 4806, Online Certificate Status Protocol (OCSP) Extensions
          to IKEv2 (S, February 2007)

   When certificates are used with IKEv2, the communicating peers need a
   mechanism to determine the revocation status of the peer's
   certificate.  OCSP is one such mechanism.  [RFC4806] defines the
   "OCSP Content" extension to IKEv2.  This document is applicable when
   OCSP is desired and security policy (e.g., firewall policy) prevents
   one of the IKEv2 peers from accessing the relevant OCSP responder
   directly.  This optional extension applies only to IKEv2, not to
   IKEv1.

4.2.3.  Dead Peer Detection

4.2.3.1.  RFC 3706, A Traffic-Based Method of Detecting Dead Internet
          Key Exchange (IKE) Peers (I, February 2004)

   When two peers communicate using IKE and IPsec, it is possible for
   the connectivity between the two peers to drop unexpectedly.  But the
   SAs can still remain until their lifetimes expire, resulting in the
   packets getting tunneled into a "black hole".  [RFC3706] describes an
   approach to detect peer liveliness without needing to send messages
   at regular intervals.  This RFC defines an optional extension to
   IKEv1; dead peer detection (DPD) is an integral part of IKEv2, which
   refers to this feature as a "liveness check" or "liveness test".

4.2.4.  Remote Access

   The IKEv2 Mobility and Multihoming (MOBIKE) protocol enables two
   additional capabilities for IPsec VPN users: 1) moving from one
   address to another without re-establishing existing SAs and 2) using




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   multiple interfaces simultaneously.  These solutions are limited to
   IPsec VPNs; they are not intended to provide more general mobility or
   multihoming capabilities.

   The IPsecME Working Group identified some missing components needed
   for more extensive IKEv2 and IPsec-v3 support for remote access
   clients.  These include efficient client resumption of a previously
   established session with a VPN gateway, efficient client redirection
   to an alternate VPN gateway, and support for IPv6 client
   configuration using IPsec configuration payloads.

4.2.4.1.  RFC 4555, IKEv2 Mobility and Multihoming Protocol (MOBIKE)
          (S, June 2006)

   IKEv2 assumes that an IKE SA is created implicitly between the IP
   address pair that is used during the protocol execution when
   establishing the IKEv2 SA.  IPsec-related documents had no provision
   to change this pair after an IKE SA was created.  [RFC4555] defines
   extensions to IKEv2 that enable an efficient management of IKE and
   IPsec Security Associations when a host possesses multiple IP
   addresses and/or where IP addresses of an IPsec host change over
   time.

4.2.4.2.  RFC 4621, Design of the IKEv2 Mobility and Multihoming
          (MOBIKE) Protocol (I, August 2006)

   [RFC4621] discusses the involved network entities and the
   relationship between IKEv2 signaling and information provided by
   other protocols.  It also records design decisions for the MOBIKE
   protocol, background information, and records discussions within the
   working group.

4.2.4.3.  RFC 5266, Secure Connectivity and Mobility Using Mobile IPv4
          and IKEv2 Mobility and Multihoming (MOBIKE) (B, June 2008)

   [RFC5266] describes a solution using Mobile IPv4 (MIPv4) and mobility
   extensions to IKEv2 (MOBIKE) to provide secure connectivity and
   mobility to enterprise users when they roam into untrusted networks.

4.2.4.4.  RFC 5723, Internet Key Exchange Protocol Version 2 (IKEv2)
          Session Resumption (S, January 2010)

   [RFC5723] enables a remote client that has been disconnected from a
   gateway to re-establish SAs with the gateway in an expedited manner,
   without repeating the complete IKEv2 negotiation.  This capability
   requires changes to IKEv2.  This optional extension applies only to
   IKEv2, not to IKEv1.




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4.2.4.5.  RFC 5685, Re-direct Mechanism for the Internet Key Exchange
          Protocol Version 2 (IKEv2) (S, November 2009)

   [RFC5685] enables a gateway to securely redirect VPN clients to
   another VPN gateway, either during or after the IKEv2 negotiation.
   Possible reasons include, but are not limited to, an overloaded
   gateway or a gateway that needs to shut down.  This requires changes
   to IKEv2.  This optional extension applies only to IKEv2, not to
   IKEv1.

4.2.4.6.  RFC 5739, IPv6 Configuration in Internet Key Exchange Protocol
          Version 2 (IKEv2) (E, February 2010)

   In IKEv2, a VPN gateway can assign an internal network address to a
   remote VPN client.  This is accomplished through the use of
   configuration payloads.  For an IPv6 client, the assignment of a
   single address is not sufficient to enable full-fledged IPv6
   communications.  [RFC5739] proposes several solutions that might
   remove this limitation.  This optional extension applies only to
   IKEv2, not to IKEv1.

5.  Cryptographic Algorithms and Suites

   Two basic requirements must be met for an algorithm to be used within
   IKE and/or IPsec: assignment of one or more IANA values and an RFC
   that describes how to use the algorithm within the relevant protocol,
   packet formats, special considerations, etc.  For each RFC that
   describes a cryptographic algorithm, this roadmap will classify its
   requirement level for each protocol, as either MUST, SHOULD, or MAY
   [RFC2119]; SHOULD+, SHOULD-, or MUST- [RFC4835]; optional; undefined;
   or N/A (not applicable).  A designation of "optional" means that the
   algorithm meets the two basic requirements, but its use is not
   specifically recommended for that protocol.  "Undefined" means that
   one of the basic requirements is not met: either there is no relevant
   IANA number for the algorithm or there is no RFC specifying how it
   should be used within that specific protocol.  "N/A" means that use
   of the algorithm is inappropriate in the context (e.g., NULL
   encryption for IKE, which always requires encryption; or combined
   mode algorithms, a new feature in IPsec-v3, for use with IPsec-v2).

   This document categorizes the requirement level of each algorithm for
   IKEv1, IKEv2, IPsec-v2, and IPsec-v3.  If an algorithm is recommended
   for use within IKEv1 or IKEv2, it is used either to protect the IKE
   SA's traffic (encryption and integrity-protection algorithms) or to
   generate keying material (Diffie-Hellman or DH groups, Pseudorandom
   Functions or PRFs).  If an algorithm is recommended for use within
   IPsec, it is used to protect the IPsec/child SA's traffic, and IKE is
   capable of negotiating its use for that purpose.  These requirements



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   are summarized in Table 1 (Appendix A).  These levels are current as
   of February 2011; subsequent RFCs may result in altered requirement
   levels.  For algorithms, this could mean the introduction of new
   algorithms or upgrading or downgrading the requirement levels of
   current algorithms.

   The IANA registries for IKEv1 and IKEv2 include IANA values for
   various cryptographic algorithms.  IKE uses these values to negotiate
   IPsec SAs that will provide protection using those algorithms.  If a
   specific algorithm lacks a value for IKEv1 and/or IKEv2, that
   algorithm's use is classified as "undefined" (no IANA #) within
   IPsec-v2 and/or IPsec-v3.

5.1.  Algorithm Requirements

   Specifying a core set of mandatory algorithms for each protocol
   facilitates interoperability.  Defining those algorithms in an RFC
   separate from the base protocol RFC enhances algorithm agility.
   IPsec-v3 and IKEv2 each have an RFC that specifies their mandatory-
   to-implement (MUST), recommended (SHOULD), optional (MAY), and
   deprecated (SHOULD NOT) algorithms.  For IPsec-v2, this is included
   in the base protocol RFC.  That was originally the case for IKEv1,
   but IKEv1's algorithm requirements were updated in [RFC4109].

5.1.1.  RFC 4835, Cryptographic Algorithm Implementation Requirements
        for Encapsulating Security Payload (ESP) and Authentication
        Header (AH) (S, April 2007)

   [RFC4835] specifies the encryption and integrity-protection
   algorithms for IPsec (both versions).  Algorithms for IPsec-v2 were
   originally defined in [RFC2402] and [RFC2406].  [RFC4305] obsoleted
   those requirements, and was in turn obsoleted by [RFC4835].
   Therefore, [RFC4835] applies to IPsec-v2 as well as IPsec-v3.
   Combined mode algorithms are mentioned, but not assigned a
   requirement level.

5.1.2.  RFC 4307, Cryptographic Algorithms for Use in the Internet Key
        Exchange Version 2 (IKEv2) (S, December 2005)

   [RFC4307] specifies the encryption and integrity-protection
   algorithms used by IKEv2 to protect its own traffic, the Diffie-
   Hellman (DH) groups used within IKEv2, and the pseudorandom functions
   used by IKEv2 to generate keys, nonces, and other random values.
   [RFC4307] contains conflicting requirements for IKEv2 encryption and
   integrity-protection algorithms.  Where there are contradictory
   requirements, this document takes its requirement levels from Section





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   3.1.1, "Encrypted Payload Algorithms", rather than from Section
   3.1.3, "IKEv2 Transform Type 1 Algorithms", or Section 3.1.4, "IKEv2
   Transform Type 2 Algorithms".

5.1.3.  RFC 4109, Algorithms for Internet Key Exchange version 1 (IKEv1)
        (S, May 2005)

   [RFC4109] updates IKEv1's algorithm specifications, which were
   originally defined in [RFC2409].  It specifies the encryption and
   integrity-protection algorithms used by IKEv1 to protect its own
   traffic; the Diffie-Hellman (DH) groups used within IKEv1; the hash
   and pseudorandom functions used by IKEv1 to generate keys, nonces and
   other random values; and the authentication methods and algorithms
   used by IKEv1 for peer authentication.

5.2.  Encryption Algorithms

   The encryption-algorithm RFCs describe how to use these algorithms to
   encrypt IKE and/or ESP traffic, providing confidentiality protection
   to the traffic.  They describe any special constraints, requirements,
   or changes to packet format appropriate for the specific algorithm.
   In general, they do not describe the detailed algorithmic
   computations; the reference section of each RFC includes pointers to
   documents that define the inner workings of the algorithm.  Some of
   the RFCs include sample test data, to enable implementors to compare
   their results with standardized output.

   When any encryption algorithm is used to provide confidentiality, the
   use of integrity protection is strongly recommended.  If the
   encryption algorithm is a stream cipher, omitting integrity
   protection seriously compromises the security properties of the
   algorithm.

   DES, as described in [RFC2405], was originally a required algorithm
   for IKEv1 and ESP-v2.  Since the use of DES is now deprecated, this
   roadmap does not include [RFC2405].

5.2.1.  RFC 2410, The NULL Encryption Algorithm and Its Use With IPsec
        (S, November 1998)

   [RFC2410] is a tongue-in-cheek description of the no-op encryption
   algorithm (i.e., using ESP without encryption).  In order for IKE to
   negotiate the selection of the NULL encryption algorithm for use in
   an ESP SA, an identifying IANA number is needed.  This number (the
   value 11 for ESP_NULL) is found on the IANA registries for both IKEv1
   and IKEv2, but it is not mentioned in [RFC2410].





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   Requirement levels for ESP-NULL:

     IKEv1 - N/A
     IKEv2 - N/A
     ESP-v2 - MUST [RFC4835]
     ESP-v3 - MUST [RFC4835]

   NOTE: RFC 4307 erroneously classifies ESP-NULL as MAY for IKEv2; this
   has been corrected in an errata submission for RFC 4307.

5.2.2.  RFC 2451, The ESP CBC-Mode Cipher Algorithms (S, November 1998)

   [RFC2451] describes how to use encryption algorithms in cipher-block-
   chaining (CBC) mode to encrypt IKE and ESP traffic.  It specifically
   mentions Blowfish, CAST-128, Triple DES (3DES), International Data
   Encryption Algorithm (IDEA), and RC5, but it is applicable to any
   block-cipher algorithm used in CBC mode.  The algorithms mentioned in
   the RFC all have a 64-bit blocksize and a 64-bit random
   Initialization Vector (IV) that is sent in the packet along with the
   encrypted data.

   Requirement levels for 3DES-CBC:

     IKEv1 - MUST [RFC4109]
     IKEv2 - MUST- [RFC4307]
     ESP-v2 - MUST [RFC4835]
     ESP-v3 - MUST- [RFC4835]

   Requirement levels for other CBC algorithms (Blowfish, CAST, IDEA,
   RC5):

     IKEv1 - optional
     IKEv2 - optional
     ESP-v2 - optional
     ESP-v3 - optional

5.2.3.  RFC 3602, The AES-CBC Cipher Algorithm and Its Use with IPsec
        (S, September. 2003)

   [RFC3602] describes how to use AES in cipher block chaining (CBC)
   mode to encrypt IKE and ESP traffic.  AES is the successor to DES.
   AES-CBC is a block-mode cipher with a 128-bit blocksize, a random IV
   that is sent in the packet along with the encrypted data, and
   keysizes of 128, 192 and 256 bits.  If AES-CBC is implemented,
   128-bit keys are MUST; the other sizes are MAY.  [RFC3602] includes
   IANA values for use in IKEv1 and ESP-v2.  A single IANA value is
   defined for AES-CBC, so IKE negotiations need to specify the keysize.




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   Requirement levels for AES-CBC with 128-bit keys:

     IKEv1 - SHOULD [RFC4109]
     IKEv2 - SHOULD+ [RFC4307]
     ESP-v2 - MUST [RFC4835]
     ESP-v3 - MUST [RFC4835]

   Requirement levels for AES-CBC with 192- or 256-bit keys:

     IKEv1 - optional
     IKEv2 - optional
     ESP-v2 - optional
     ESP-v3 - optional

5.2.4.  RFC 3686, Using Advanced Encryption Standard (AES) Counter Mode
        With IPsec Encapsulating Security Payload (ESP)
        (S, January 2004)

   [RFC3686] describes how to use AES in counter (CTR) mode to encrypt
   ESP traffic.  AES-CTR is a stream cipher with a 32-bit random nonce
   (1/SA) and a 64-bit IV.  If AES-CTR is implemented, 128-bit keys are
   MUST; 192- and 256-byte keys are MAY.  Reuse of the IV with the same
   key and nonce compromises the data's security; thus, AES-CTR should
   not be used with manual keying.  AES-CTR can be pipelined and
   parallelized; it uses only the AES encryption operations for both
   encryption and decryption.

   Requirement levels for AES-CTR:

     IKEv1 - undefined (no IANA #)
     IKEv2 - optional [RFC5930]
     ESP-v2 - SHOULD [RFC4835]
     ESP-v3 - SHOULD [RFC4835]

5.2.5.  RFC 5930, Using Advanced Encryption Standard Counter Mode (AES-
        CTR) with the Internet Key Exchange version 02 (IKEv2) Protocol
        (I, July 210).

   [RFC5930] extends [RFC3686] to enable the use of AES-CTR to provide
   encryption and integrity protection for IKEv2 messages.

5.2.6.  RFC 4312, The Camellia Cipher Algorithm and Its Use with IPsec
        (S, December 2005)

   [RFC4312] describes how to use Camellia in cipher block chaining
   (CBC) mode to encrypt IKE and ESP traffic.  Camellia-CBC is a block-
   mode cipher with a 128-bit blocksize, a random IV that is sent in the
   packet along with the encrypted data, and keysizes of 128, 192, and



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   256 bits.  If Camellia-CBC is implemented, 128-bit keys are MUST; the
   other sizes are MAY.  [RFC4312] includes IANA values for use in IKEv1
   and IPsec-v2.  A single IANA value is defined for Camellia-CBC, so
   IKEv1 negotiations need to specify the keysize.

5.2.7.  RFC 5529, Modes of Operation for Camellia for Use with IPsec
        (S, April 2009)

   [RFC5529] describes the use of the Camellia block-cipher algorithm in
   conjunction with several different modes of operation.  It describes
   the use of Camellia in cipher block chaining (CBC) mode and counter
   (CTR) mode as an encryption algorithm within ESP.  It also describes
   the use of Camellia in Counter with CBC-MAC (CCM) mode as a combined
   mode algorithm in ESP.  This document defines how to use IKEv2 to
   generate keying material for a Camellia ESP SA; it does not define
   how to use Camellia within IKEv2 to protect an IKEv2 SA's traffic.
   However, this RFC, in conjunction with IKEv2's generalized
   description of block-mode encryption, provide enough detail to allow
   the use of Camellia-CBC algorithms within IKEv2.  All three modes can
   use keys of length 128 bits, 192 bits, or 256 bits. [RFC5529]
   includes IANA values for use in IKEv2 and IPsec-v3.  A single IANA
   value is defined for each Camellia mode, so IKEv2 negotiations need
   to specify the keysize.

   Requirement levels for Camellia-CBC:

     IKEv1 - optional
     IKEv2 - optional
     ESP-v2 - optional
     ESP-v3 - optional

   Requirement levels for Camellia-CTR:

     IKEv1 - undefined (no IANA #)
     IKEv2 - undefined (no RFC)
     ESP-v2 - optional (but no IANA #, so cannot be negotiated by IKE)
     ESP-v3 - optional

   Requirement levels for Camellia-CCM:

     IKEv1 - N/A
     IKEv2 - undefined (no RFC)
     ESP-v2 - N/A
     ESP-v3 - optional







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5.2.8.  RFC 4196, The SEED Cipher Algorithm and Its Use with IPsec
        (S, October 2005)

   [RFC4196] describes how to use SEED in cipher block chaining (CBC)
   mode to encrypt ESP traffic.  It describes how to use IKEv1 to
   negotiate a SEED-ESP SA, but does not define the use of SEED to
   protect IKEv1 traffic.  SEED-CBC is a block-mode cipher with a
   128-bit blocksize, a random IV that is sent in the packet along with
   the encrypted data, and a keysize of 128 bits.  [RFC4196] includes
   IANA values for use in IKEv1 and IPsec-v2.  [RFC4196] includes test
   data.

   Requirement levels for SEED-CBC:

     IKEv1 - undefined (no IANA #)
     IKEv2 - undefined (no IANA #)
     ESP-v2 - optional
     ESP-v3 - optional (but no IANA #, so cannot be negotiated by IKE)

5.3.  Integrity-Protection (Authentication) Algorithms

   The integrity-protection algorithm RFCs describe how to use these
   algorithms to authenticate IKE and/or IPsec traffic, providing
   integrity protection to the traffic.  This protection is provided by
   computing an Integrity Check Value (ICV), which is sent in the
   packet.  The RFCs describe any special constraints, requirements, or
   changes to packet format appropriate for the specific algorithm.  In
   general, they do not describe the detailed algorithmic computations;
   the reference section of each RFC includes pointers to documents that
   define the inner workings of the algorithm.  Some of the RFCs include
   sample test data, to enable implementors to compare their results
   with standardized output.

   Some of these algorithms generate a fixed-length ICV, which is
   truncated when it is included in an IPsec-protected packet.  For
   example, standard HMAC-SHA-1 (Hashed Message Authentication Code)
   generates a 160-bit ICV, which is truncated to 96 bits when it is
   used to provide integrity protection to an ESP or AH packet.  The
   individual RFC descriptions mention those algorithms that are
   truncated.  When these algorithms are used to protect IKEv2 SAs, they
   are also truncated.  For IKEv1, HMAC-SHA-1 and HMAC-MD5 are
   negotiated by requesting the hash algorithms SHA-1 and MD5,
   respectively; these algorithms are not truncated when used to protect
   an IKEv1 SA.  For HMAC-SHA-1 and HMAC-MD5, the IKEv2 IANA registry
   contains values for both the truncated version and the standard non-
   truncated version; thus, IKEv2 has the capability to negotiate either
   version of the algorithm.  However, only the truncated version is
   used for IKEv2 SAs and for IPsec SAs.  The non-truncated version is



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   reserved for use by the Fibre Channel protocol [RFC4595].  For the
   other algorithms (AES-XCBC, HMAC-SHA-256/384/512, AES-CMAC, and HMAC-
   RIPEMD), only the truncated version can be used for both IKEv2 and
   IPsec-v3 SAs.

   One other algorithm, AES-GMAC [RFC4543], can also provide integrity
   protection.  It has two versions: an integrity-protection algorithm
   for use within AH-v3, and a combined mode algorithm with null
   encryption for use within ESP-v3.  [RFC4543] is described in Section
   5.4, "Combined Mode Algorithms".

5.3.1.  RFC 2404, The Use of HMAC-SHA-1-96 within ESP and AH
        (S, November 1998)

   [RFC2404] describes HMAC-SHA-1, an integrity-protection algorithm
   with a 512-bit blocksize, and a 160-bit key and Integrity Check Value
   (ICV).  For use within IPsec, the ICV is truncated to 96 bits.  This
   is currently the most commonly used integrity-protection algorithm.

   Requirement levels for HMAC-SHA-1:

     IKEv1 - MUST [RFC4109]
     IKEv2 - MUST [RFC4307]
     IPsec-v2 - MUST [RFC4835]
     IPsec-v3 - MUST [RFC4835]

5.3.2.  RFC 3566, The AES-XCBC-MAC-96 Algorithm and Its Use With IPsec
        (S, September 2003)

   [RFC3566] describes AES-XCBC-MAC, a variant of CBC-MAC, which is
   secure for messages of varying lengths (unlike classic CBC-MAC).  It
   is an integrity-protection algorithm with a 128-bit blocksize and a
   128-bit key and ICV.  For use within IPsec, the ICV is truncated to
   96 bits.  [RFC3566] includes test data.

   Requirement levels for AES-XCBC-MAC:

     IKEv1 - undefined (no RFC)
     IKEv2 - optional
     IPsec-v2 - SHOULD+ [RFC4835]
     IPsec-v3 - SHOULD+ [RFC4835]

5.3.3.  RFC 4868, Using HMAC-SHA-256, HMAC-SHA-384, and HMAC-SHA-512
        with IPsec (S, May 2007)

   [RFC4868] describes a family of algorithms, successors to HMAC-SHA-1.
   HMAC-SHA-256 has a 512-bit blocksize and a 256-bit key and ICV.
   HMAC-SHA-384 has a 1024-bit blocksize and a 384-bit key and ICV.



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   HMAC-SHA-512 has a 1024-bit blocksize and a 512-bit key and ICV.  For
   use within IKE and IPsec, the ICV is truncated to half its original
   size (128 bits, 192 bits, or 256 bits).  Each of the three algorithms
   has its own IANA value, so IKE does not have to negotiate the
   keysize.

   Requirement levels for HMAC-SHA-256, HMAC-SHA-384, HMAC-SHA-512:

     IKEv1 - optional
     IKEv2 - optional
     IPsec-v2 - optional
     IPsec-v3 - optional

5.3.4.  RFC 2403, The Use of HMAC-MD5-96 within ESP and AH
        (S, November 1998)

   [RFC2403] describes HMAC-MD5, an integrity-protection algorithm with
   a 512-bit blocksize and a 128-bit key and Integrity Check Value
   (ICV).  For use within IPsec, the ICV is truncated to 96 bits.  It
   was a required algorithm for IKEv1 and IPsec-v2.  The use of plain
   MD5 is now deprecated, but [RFC4835] states: "Weaknesses have become
   apparent in MD5; however, these should not affect the use of MD5 with
   HMAC".

   Requirement levels for HMAC-MD5:

     IKEv1 - MAY [RFC4109]
     IKEv2 - optional [RFC4307]
     IPsec-v2 - MAY [RFC4835]
     IPsec-v3 - MAY [RFC4835]

5.3.5.  RFC 4494, The AES-CMAC-96 Algorithm and Its Use with IPsec
        (S, June 2006)

   [RFC4494] describes AES-CMAC, another variant of CBC-MAC, which is
   secure for messages of varying lengths.  It is an integrity-
   protection algorithm with a 128-bit blocksize and 128-bit key and
   ICV.  For use within IPsec, the ICV is truncated to 96 bits.
   [RFC4494] includes test data.

   Requirement levels for AES-CMAC:

     IKEv1 - undefined (no IANA #)
     IKEv2 - optional
     IPsec-v2 - optional (but no IANA #, so cannot be negotiated by IKE)
     IPsec-v3 - optional





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5.3.6.  RFC 2857, The Use of HMAC-RIPEMD-160-96 within ESP and AH
        (S, June 2000)

   [RFC2857] describes HMAC-RIPEMD, an integrity-protection algorithm
   with a 512-bit blocksize and a 160-bit key and ICV.  For use within
   IPsec, the ICV is truncated to 96 bits.

   Requirement levels for HMAC-RIPEMD:

     IKEv1 - undefined (no IANA #)
     IKEv2 - undefined (no IANA #)
     IPsec-v2 - optional
     IPsec-v3 - optional (but no IANA #, so cannot be negotiated by IKE)

5.3.7.  RFC 4894, Use of Hash Algorithms in Internet Key Exchange (IKE)
        and IPsec (I, May 2007)

   In light of recent attacks on MD5 and SHA-1, [RFC4894] examines
   whether it is necessary to replace the hash functions currently used
   by IKE and IPsec for key generation, integrity protection, digital
   signatures, or PKIX certificates.  It concludes that the algorithms
   recommended for IKEv2 [RFC4307] and IPsec-v3 [RFC4305] are not
   currently susceptible to any known attacks.  Nonetheless, it suggests
   that implementors add support for AES-XCBC-MAC-96 [RFC3566], AES-
   XCBC-PRF-128 [RFC4434], and HMAC-SHA-256, -384, and -512 [RFC4868]
   for future use.  It also suggests that IKEv2 implementors add support
   for PKIX certificates signed with SHA-256, -384, and -512.

5.4.  Combined Mode Algorithms

   IKEv1 and ESP-v2 use separate algorithms to provide encryption and
   integrity protection, and IKEv1 can negotiate different combinations
   of algorithms for different SAs.  In ESP-v3, a new class of
   algorithms was introduced, in which a single algorithm can provide
   both encryption and integrity protection.  [RFC5996] describes how
   IKEv2 can negotiate combined mode algorithms to be used in ESP-v3
   SAs.  [RFC5282] adds that capability to IKEv2, enabling IKEv2 to
   negotiate and use combined mode algorithms for its own traffic.  When
   properly designed, these algorithms can provide increased efficiency
   in both implementation and execution.

   Although ESP-v2 did not originally include combined mode algorithms,
   some IKEv1 implementations have added the capability to negotiate
   combined mode algorithms for use in IPsec SAs; these implementations
   do not include the capability to use combined mode algorithms to
   protect IKE SAs.  IANA numbers for combined mode algorithms have been
   added to the IKEv1 registry.




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5.4.1.  RFC 4309, Using Advanced Encryption Standard (AES) CCM Mode with
        IPsec Encapsulating Security Payload (ESP) (S, December 2005)

   [RFC4309] describes how to use AES in counter with CBC-MAC (CCM)
   mode, a combined algorithm, to encrypt and integrity protect ESP
   traffic.  AES-CCM is a block-mode cipher with a 128-bit blocksize; a
   random IV that is sent in the packet along with the encrypted data; a
   24-bit salt value (1/SA); keysizes of 128, 192, and 256 bits and ICV
   sizes of 64, 96 and 128 bits.  If AES-CCM is implemented, 128-bit
   keys are MUST; the other sizes are MAY.  ICV sizes of 64 and 128 bits
   are MUST; 96 bits is MAY.  The salt value is generated by IKE during
   the key-generation process.  Reuse of the IV with the same key
   compromises the data's security; thus, AES-CCM should not be used
   with manual keying.  [RFC4309] includes IANA values that IKE can use
   to negotiate ESP-v3 SAs.  Each of the three ICV lengths has its own
   IANA value, but IKE negotiations need to specify the keysize.
   [RFC4309] includes test data.  [RFC4309] describes how IKE can
   negotiate the use of AES-CCM to use in an ESP SA.  [RFC5282] extends
   this to the use of AES-CCM to protect an IKEv2 SA.

   Requirement levels for AES-CCM:

     IKEv1 - N/A
     IKEv2 - optional
     ESP-v2 - N/A
     ESP-v3 - optional [RFC4835]

   NOTE: The IPsec-v2 IANA registry includes values for AES-CCM, but
   combined mode algorithms are not a feature of IPsec-v2.  Although
   some IKEv1/IPsec-v2 implementations include this capability (see
   Section 5.4), it is not part of the protocol.

5.4.2.  RFC 4106, The Use of Galois/Counter Mode (GCM) in IPsec
        Encapsulating Security Payload (ESP) (S, June 2005)

   [RFC4106] describes how to use AES in Galois/Counter (GCM) mode, a
   combined algorithm, to encrypt and integrity protect ESP traffic.
   AES-GCM is a block-mode cipher with a 128-bit blocksize; a random IV
   that is sent in the packet along with the encrypted data; a 32-bit
   salt value (1/SA); keysizes of 128, 192, and 256 bits; and ICV sizes
   of 64, 96, and 128 bits.  If AES-GCM is implemented, 128-bit keys are
   MUST; the other sizes are MAY.  An ICV size of 128 bits is a MUST; 64
   and 96 bits are MAY.  The salt value is generated by IKE during the
   key-generation process.  Reuse of the IV with the same key
   compromises the data's security; thus, AES-GCM should not be used
   with manual keying.  [RFC4106] includes IANA values that IKE can use
   to negotiate ESP-v3 SAs.  Each of the three ICV lengths has its own
   IANA value, but IKE negotiations need to specify the keysize.



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   [RFC4106] includes test data.  [RFC4106] describes how IKE can
   negotiate the use of AES-GCM to use in an ESP SA.  [RFC5282] extends
   this to the use of AES-GCM to protect an IKEv2 SA.

   Requirement levels for AES-GCM:

     IKEv1 - N/A
     IKEv2 - optional
     ESP-v2 - N/A
     ESP-v3 - optional [RFC4835]

   NOTE: The IPsec-v2 IANA registry includes values for AES-GCM, but
   combined mode algorithms are not a feature of IPsec-v2.  Although
   some IKEv1/IPsec-v2 implementations include this capability (see
   Section 5.4), it is not part of the protocol.

5.4.3.  RFC 4543, The Use of Galois Message Authentication Code (GMAC)
        in IPsec ESP and AH (S, May 2006)

   [RFC4543] is the variant of AES-GCM [RFC4106] that provides integrity
   protection without encryption.  It has two versions: an integrity-
   protection algorithm for use within AH, and a combined mode algorithm
   with null encryption for use within ESP.  It can use a key of 128-,
   192-, or 256-bits; the ICV is always 128 bits, and is not truncated.
   AES-GMAC uses a nonce, consisting of a 64-bit IV and a 32-bit salt
   (1/SA).  The salt value is generated by IKE during the key generation
   process.  Reuse of the salt value with the same key compromises the
   data's security; thus, AES-GMAC should not be used with manual
   keying.  For use within AH, each keysize has its own IANA value, so
   IKE does not have to negotiate the keysize.  For use within ESP,
   there is only one IANA value, so IKE negotiations must specify the
   keysize.  AES-GMAC cannot be used by IKE to protect its own SAs,
   since IKE traffic requires encryption.

   Requirement levels for AES-GMAC:

     IKEv1 - N/A
     IKEv2 - N/A
     IPsec-v2 - N/A
     IPsec-v3 - optional

   NOTE: The IPsec-v2 IANA registry includes values for AES-GMAC, but
   combined mode algorithms are not a feature of IPsec-v2.  Although
   some IKEv1/IPsec-v2 implementations include this capability (see
   Section 5.4), it is not part of the protocol.






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5.4.4.  RFC 5282, Using Authenticated Encryption Algorithms with the
        Encrypted Payload of the Internet Key Exchange version 2 (IKEv2)
        Protocol (S, August 2008)

   [RFC5282] extends [RFC4309] and [RFC4106] to enable the use of AES-
   CCM and AES-GCM to provide encryption and integrity protection for
   IKEv2 messages.

5.5.  Pseudo-Random Functions (PRFs)

   IKE uses pseudorandom functions (PRFs) to generate the secret keys
   that are used in IKE SAs and IPsec SAs.  These PRFs are generally the
   same algorithms used for integrity protection, but their output is
   not truncated, since all of the generated bits are generally needed
   for the keys.  If the PRF's output is not long enough to supply the
   required number of bits of keying material, the PRF is applied
   iteratively until the requisite amount of keying material is
   generated.

   For each IKEv2 SA, the peers negotiate both a PRF algorithm and an
   integrity-protection algorithm; the former is used to generate keying
   material and other values, and the latter is used to provide
   protection to the IKE SA's traffic.

   IKEv1's approach is more complicated.  IKEv1 [RFC2409] does not
   specify any PRF algorithms.  For each IKEv1 SA, the peers agree on an
   unkeyed hash function (e.g., SHA-1).  IKEv1 uses the HMAC version of
   this function to generate keying material and to provide integrity
   protection for the IKE SA.  Therefore, PRFs that are not HMACs cannot
   currently be used in IKEv1.

   Requirement levels for PRF-HMAC-SHA1:

     IKEv1 - MUST [RFC4109]
     IKEv2 - MUST [RFC4307]

   Requirement levels for PRF-HMAC-SHA-256, PRF-HMAC-SHA-384, and PRF-
   HMAC-SHA-512:

     IKEv1 - optional [RFC4868]
     IKEv2 - optional [RFC4868]

5.5.1.  RFC 4434, The AES-XCBC-PRF-128 Algorithm for the Internet Key
        Exchange Protocol (IKE) (S, February 2006)

   [RFC3566] defines AES-XCBC-MAC-96, which is used for integrity
   protection within IKE and IPsec.  [RFC4434] enables the use of AES-
   XCBC-MAC as a PRF within IKE.  The PRF differs from the integrity-



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   protection algorithm in two ways: its 128-bit output is not truncated
   to 96 bits, and it accepts a variable-length key, which is modified
   (lengthened via padding or shortened through application of AES-XCBC)
   to a 128-bit key.  [RFC4434] includes test data.

   Requirement levels for AES-XCBC-PRF:

     IKEv1 - undefined (no RFC)
     IKEv2 - SHOULD+ [RFC4307]

   NOTE: RFC 4109 erroneously classifies AES-XCBC-PRF as SHOULD for
   IKEv1; this has been corrected in an errata submission for RFC 4109.

5.5.2.  RFC 4615, The Advanced Encryption Standard-Cipher-based Message
        Authentication Code-Pseudorandom Function-128 (AES-CMAC-PRF-128)
        Algorithm for the Internet Key Exchange Protocol (IKE)
        (S, August 2006)

   [RFC4615] extends [RFC4494] to enable the use of AES-CMAC as a PRF
   within IKEv2, in a manner analogous to that used by [RFC4434] for
   AES-XCBC.

   Requirement levels for AES-CMAC-PRF:

     IKEv1 - undefined (no IANA #)
     IKEv2 - optional

5.6.  Cryptographic Suites

5.6.1.  RFC 4308, Cryptographic Suites for IPsec (S, December 2005)

   An IKE negotiation consists of multiple cryptographic attributes,
   both for the IKE SA and for the IPsec SA.  The number of possible
   combinations can pose a challenge to peers trying to find a common
   policy.  To enhance interoperability, [RFC4308] defines two pre-
   defined suites, consisting of combinations of algorithms that
   comprise typical security policies.  IKE/ESP suite "VPN-A" includes
   use of 3DES, HMAC-SHA-1, and 1024-bit modular exponentiation group
   (MODP) Diffie-Hellman (DH); IKE/ESP suite "VPN-B" includes AES-CBC,
   AES-XCBC-MAC, and 2048-bit MODP DH.  These suites are intended to be
   named "single-button" choices in the administrative interface, but do
   not prevent the use of alternative combinations.

5.6.2.  RFC 4869, Suite B Cryptographic Suites for IPsec (I, May 2007)

   [RFC4869] adds four pre-defined suites, based upon the United States
   National Security Agency's "Suite B" specifications, to those
   specified in [RFC4308].  IKE/ESP suites "Suite-B-GCM-128" and "Suite-



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   B-GCM-256" include use of AES-CBC, AES-GCM, HMAC-SHA-256, or HMAC-
   SHA-384, and 256-bit or 384-bit elliptic-curve (EC) DH groups.
   IKE/AH suites "Suite-B-GMAC-128" and "Suite-B-GMAC-256" include use
   of AES-CBC, AES-GMAC, HMAC-SHA-256, or HMAC-SHA-384, and 256-bit or
   384-bit EC DH groups.  While [RFC4308] does not specify a peer-
   authentication method, [RFC4869] mandates pre-shared key
   authentication for IKEv1; public key authentication using ECDSA is
   recommended for IKEv1 and required for IKEv2.

5.7.  Diffie-Hellman Algorithms

   IKE negotiations include a Diffie-Hellman exchange, which establishes
   a shared secret to which both parties contributed.  This value is
   used to generate keying material to protect both the IKE SA and the
   IPsec SA.

   IKEv1 [RFC2409] contains definitions of two DH MODP groups and two
   elliptic curve (EC) groups; IKEv2 [RFC5996] only references the MODP
   groups.  The requirements levels of these groups are:

   Requirement levels for DH MODP group 1:

     IKEv1 - MAY [RFC4109]
     IKEv2 - optional

   Requirement levels for DH MODP group 2:

     IKEv1 - MUST [RFC4109]
     IKEv2 - MUST- [RFC4307]

   Requirement levels for EC groups 3-4:

     IKEv1 - MAY [RFC4109]
     IKEv2 - undefined (no IANA #)

5.7.1.  RFC 3526, More Modular Exponential (MODP) Diffie-Hellman groups
        for Internet Key Exchange (IKE) (S, May 2003)

   [RFC2409] and [RFC5996] define two MODP DH groups (groups 1 and 2)
   for use within IKE.  [RFC3526] adds six more groups (groups 5 and
   14-18).  Group 14 is a 2048-bit group that is strongly recommended
   for use in IKE.

   Requirement levels for DH MODP group 14:

     IKEv1 - SHOULD [RFC4109]
     IKEv2 - SHOULD+ [RFC4307]




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   Requirement levels for DH MODP groups 5, 15-18:

     IKEv1 - optional [RFC4109]
     IKEv2 - optional

5.7.2.  RFC 4753, ECP Groups For IKE and IKEv2 (I, January 2007)

   [RFC4753] defines three EC DH groups (groups 19-21) for use within
   IKE.

   The document includes test data.

   Requirement levels for DH EC groups  19-21:

     IKEv1 - optional [RFC4109]
     IKEv2 - optional

5.7.3.  RFC 5903, Elliptic Curve Groups modulo a Prime (ECP Groups) for
        IKE and IKEv2 (I, June 2010)

   [RFC5903] obsoletes [RFC4753], fixing an inconsistency in the DH
   shared secret value.

5.7.4.  RFC 5114, Additional Diffie-Hellman Groups for Use with IETF
        Standards (I, January 2008)

   [RFC5114] defines five additional DH groups (MODP groups 22-24 and EC
   groups 25-26) for use in IKE.  It also includes three EC DH groups
   (groups 19-21) that were originally defined in [RFC4753]; however,
   the current specification for these groups is [RFC5903].  The IANA
   group numbers are specific to IKE, but the DH groups are intended for
   use in multiple IETF protocols, including Transport Layer
   Security/Secure Socket Layer (TLS/SSL), Secure/Multipurpose Internet
   Mail Extensions (S/MIME), and X.509 Certificates.

   Requirement levels for DH MODP groups 22-24, EC groups 25-26:

     IKEv1 - optional
     IKEv2 - optional

6.  IPsec/IKE for Multicast

   [RFC4301] describes IPsec processing for unicast and multicast
   traffic.  However, classical IPsec SAs provide point-to-point
   protection; the security afforded by IPsec's cryptographic algorithms
   is not applicable when the SA is one-to-many or many-to-many, the
   case for multicast.  The Multicast Security (msec) Working Group has
   defined alternatives to IKE and extensions to IPsec for use with



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   multicast traffic.  Different multicast groups have differing
   characteristics and requirements: number of senders (one-to-many or
   many-to-many), number of members (few, moderate, very large),
   volatility of membership, real-time delivery, etc.  Their security
   requirements vary as well.  Each solution defined by msec applies to
   a subset of the large variety of possible multicast groups.

6.1.  RFC 3740, The Multicast Group Security Architecture
      (I, March 2004)

   [RFC3740] defines the multicast security architecture, which is used
   to provide security for packets exchanged by large multicast groups.
   It defines the components of the architectural framework; discusses
   Group Security Associations (GSAs), key management, data handling,
   and security policies.  Several existing protocols, including Group
   DOI (GDOI) [RFC3547], Group Secure Association Key Management
   Protocol (GSAKMP) [RFC4535],  and Multimedia Internet KEYing (MIKEY)
   [RFC3830], satisfy the group key management requirements defined in
   this document.  Both the architecture and the components for
   Multicast Group Security differ from IPsec.

6.2.  RFC 5374, Multicast Extensions to the Security Architecture for
      the Internet Protocol (S, November 2008)

   [RFC5374] extends the security architecture defined in [RFC4301] to
   apply to multicast traffic.  It defines a new class of SAs (GSAs -
   Group Security Associations) and additional databases used to apply
   IPsec protection to multicast traffic.  It also describes revisions
   and additions to the processing algorithms in [RFC4301].

6.3.  RFC 3547, The Group Domain of Interpretation (S, July 2003)

   GDOI [RFC3547] extends IKEv1 so that it can be used to establish SAs
   to protect multicast traffic.  This document defines additional
   exchanges and payloads to be used for that purpose.

6.4.  RFC 4046, Multicast Security (MSEC) Group Key Management
      Architecture (I, April 2005)

   [RFC4046] sets out the general requirements and design principles for
   protocols that are used for multicast key management.  It does not go
   into the specifics of an individual protocol that can be used for
   that purpose.








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6.5.  RFC 4359, The Use of RSA/SHA-1 Signatures within Encapsulating
      Security Payload (ESP) and Authentication Header (AH)
      (S, January 2006)

   [RFC4359] describes the use of the RSA digital signature algorithm to
   provide integrity protection for multicast traffic within ESP and AH.
   The algorithms used for integrity protection for unicast traffic
   (e.g., HMAC) are not suitable for this purpose when used with
   multicast traffic.

7.  Outgrowths of IPsec/IKE

   Operational experience with IPsec revealed additional capabilities
   that could make IPsec more useful in real-world scenarios.  These
   include support for IPsec policy mechanisms, IPsec MIBs, payload
   compression (IPComp), extensions to facilitate additional peer
   authentication methods (Better-Than-Nothing Security (BTNS),
   Kerberized Internet Negotiation of Keys (KINK), and IPSECKEY), and
   additional capabilities for VPN clients (IPSRA).

7.1.  IPsec Policy

   The IPsec Policy (ipsp) Working Group originally planned an RFC that
   would allow entities with no common Trust Anchor and no prior
   knowledge of each other's security policies to establish an IPsec-
   protected connection.  The solutions that were proposed for gateway
   discovery and security policy negotiation proved to be overly complex
   and fragile, in the absence of prior knowledge or compatible
   configuration policies.

7.1.1.  RFC 3586, IP Security Policy (IPSP) Requirements
        (S, August 2003)

   [RFC3586] describes the functional requirements of a generalized
   IPsec policy framework, that could be used to discover, negotiate,
   and manage IPsec policies.

7.1.2.  RFC 3585, IPsec Configuration Policy Information Model
        (S, August 2003)

   As stated in [RFC3585]:

      This document presents an object-oriented information model of IP
      Security (IPsec) policy designed to facilitate agreement about the
      content and semantics of IPsec policy, and enable derivations of
      task-specific representations of IPsec policy such as storage
      schema, distribution representations, and policy specification
      languages used to configure IPsec-enabled endpoints.



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   This RFC has not been widely adopted.

7.2.  IPsec MIBs

   Over the years, several MIB-related Internet Drafts were proposed for
   IPsec and IKE, but only one progressed to RFC status.

7.2.1.  RFC 4807, IPsec Security Policy Database Configuration MIB
        (S, March 2007)

   [RFC4807] defines a MIB module that can be used to configure the SPD
   of an IPsec device.  This RFC has not been widely adopted.

7.3.  IPComp (Compression)

   The IP Payload Compression Protocol (IPComp) is a protocol that
   provides lossless compression for IP datagrams.  Although IKE can be
   used to negotiate the use of IPComp in conjunction with IPsec, IPComp
   can also be used when IPsec is not applied.

   The IPComp protocol allows the compression of IP datagrams by
   supporting different compression algorithms.  Three of these
   algorithms are: DEFLATE [RFC2394], LZS [RFC2395], and the ITU-T V.44
   Packet Method [RFC3051], which is based on the LZJH algorithm.

7.3.1.  RFC 3173, IP Payload Compression Protocol (IPComp)
        (S, September 2001)

   IP payload compression is especially useful when IPsec-based
   encryption is applied to IP datagrams.  Encrypting the IP datagram
   causes the data to be random in nature, rendering compression at
   lower protocol layers ineffective.  If IKE is used to negotiate
   compression in conjunction with IPsec, compression can be performed
   prior to encryption.  [RFC3173] defines the payload compression
   protocol, the IPComp packet structure, the IPComp Association (IPCA),
   and several methods to negotiate the IPCA.

7.4.  Better-Than-Nothing Security (BTNS)

   One of the major obstacles to widespread implementation of IPsec is
   the lack of pre-existing credentials that can be used for peer
   authentication.  Better-Than-Nothing Security (BTNS) is an attempt to
   sidestep this problem by allowing IKE to negotiate unauthenticated
   (anonymous) IPsec SAs, using credentials such as self-signed
   certificates or "bare" public keys (public keys that are not
   connected to a public key certificate) for peer authentication.  This
   ensures that subsequent traffic protected by the SA is conducted with




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   the same peer, and protects the communications from passive attack.
   These SAs can then be cryptographically bound to a higher-level
   application protocol, which performs its own peer authentication.

7.4.1.  RFC 5660, IPsec Channels: Connection Latching (S, October 2009)

   [RFC5660] specifies, abstractly, how to interface applications and
   transport protocols with IPsec so as to create channels by latching
   connections (packet flows) to certain IPsec Security Association (SA)
   parameters for the lifetime of the connections.  Connection latching
   is layered on top of IPsec and does not modify the underlying IPsec
   architecture.

7.4.2.  RFC 5386, Better-Than-Nothing-Security: An Unauthenticated Mode
        of IPsec (S, November 2008)

   [RFC5386] specifies how to use IKEv2 to set up unauthenticated
   security associations (SAs) for use with the IPsec Encapsulating
   Security Payload (ESP) and the IPsec Authentication Header (AH).
   This document does not require any changes to the bits on the wire,
   but specifies extensions to the Peer Authorization Database (PAD) and
   Security Policy Database (SPD).

7.4.3.  RFC 5387, Problem and Applicability Statement for Better-Than-
        Nothing Security (BTNS) (I, November 2008)

   [RFC5387] considers that the need to deploy authentication
   information and its associated identities is a significant obstacle
   to the use of IPsec.  This document explains the rationale for
   extending the Internet network security protocol suite to enable use
   of IPsec security services without authentication.

7.5.  Kerberized Internet Negotiation of Keys (KINK)

   Kerberized Internet Negotiation of Keys (KINK) is an attempt to
   provide an alternative to IKE for IPsec peer authentication.  It uses
   Kerberos, instead of IKE, to establish IPsec SAs.  For enterprises
   that already deploy the Kerberos centralized key management system,
   IPsec can then be implemented without the need for additional peer
   credentials.  Some vendors have implemented proprietary extensions
   for using Kerberos in IKEv1, as an alternative to the use of KINK.
   These extensions, as well as the KINK protocol, apply only to IKEv1,
   and not to IKEv2.








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7.5.1.  RFC 3129, Requirements for Kerberized Internet Negotiation of
        Keys (I, June 2001)

   [RFC3129] considers that peer-to-peer authentication and keying
   mechanisms have inherent drawbacks such as computational complexity
   and difficulty in enforcing security policies.  This document
   specifies the requirements for using basic features of Kerberos and
   uses them to its advantage to create a protocol that can establish
   and maintain IPsec security associations ([RFC2401]).

7.5.2.  RFC 4430, Kerberized Internet Negotiation of Keys (KINK)
        (S, March 2006)

   [RFC4430] defines a low-latency, computationally inexpensive, easily
   managed, and cryptographically sound protocol to establish and
   maintain security associations using the Kerberos authentication
   system.  This document reuses the Quick Mode payloads of IKEv1 in
   order to foster substantial reuse of IKEv1 implementations.  This RFC
   has not been widely adopted.

7.6.  IPsec Secure Remote Access (IPSRA)

   IPsec Secure Remote Access (IPSRA) was an attempt to extend IPsec
   protection to "road warriors", allowing IKE to authenticate not only
   the user's device but also the user, without changing IKEv1.  The
   working group defined generic requirements of different IPsec remote
   access scenarios.  An attempt was made to define an IKE-like protocol
   that would use legacy authentication mechanisms to create a temporary
   or short-lived user credential that could be used for peer
   authentication within IKE.  This protocol proved to be more
   cumbersome than standard Public Key protocols, and was abandoned.
   This led to the development of IKEv2, which incorporates the use of
   EAP for user authentication.

7.6.1.  RFC 3457, Requirements for IPsec Remote Access Scenarios
        (I, January 2003)

   [RFC3457] explores and enumerates the requirements of various IPsec
   remote access scenarios, without suggesting particular solutions for
   them.

7.6.2.  RFC 3456, Dynamic Host Configuration Protocol (DHCPv4)
        Configuration of IPsec Tunnel Mode (S, January 2003)

   [RFC3456] explores the requirements for host configuration in IPsec
   tunnel mode, and describes how the Dynamic Host Configuration
   Protocol (DHCPv4) may be used for providing such configuration
   information.  This RFC has not been widely adopted.



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7.7.  IPsec Keying Information Resource Record (IPSECKEY)

   The IPsec Keying Information Resource Record (IPSECKEY) enables the
   storage of public keys and other information that can be used to
   facilitate opportunistic IPsec in a new type of DNS resource record.

7.7.1.  RFC 4025, A method for storing IPsec keying material in DNS
        (S, February 2005)

   [RFC4025] describes a method of storing IPsec keying material in the
   DNS using a new type of resource record.  This document describes how
   to store the public key of the target node in this resource record.
   This RFC has not been widely adopted.

8.  Other Protocols That Use IPsec/IKE

   IPsec and IKE were designed to provide IP-layer security protection
   to other Internet protocols' traffic as well as generic
   communications.  Since IPsec is a general-purpose protocol, in some
   cases, its features do not provide the granularity or distinctive
   features required by another protocol; in some cases, its overhead or
   prerequisites do not match another protocol's requirements.  However,
   a number of other protocols do use IKE and/or IPsec to protect some
   or all of their communications.

8.1.  Mobile IP (MIPv4 and MIPv6)

8.1.1.  RFC 4093, Problem Statement: Mobile IPv4 Traversal of Virtual
        Private Network (VPN) Gateways (I, August 2005)

   [RFC4093] describes the issues with deploying Mobile IPv4 across
   virtual private networks (VPNs).  IPsec is one of the VPN
   technologies covered by this document.  It identifies and describes
   practical deployment scenarios for Mobile IPv4 running alongside
   IPsec in enterprise and operator environments.  It also specifies a
   set of framework guidelines to evaluate proposed solutions for
   supporting multi-vendor seamless IPv4 mobility across IPsec-based VPN
   gateways.

8.1.2.  RFC 5265, Mobile IPv4 Traversal across IPsec-Based VPN Gateways
        (S, June 2008)

   [RFC5265] describes a basic solution that uses Mobile IPv4 and IPsec
   to provide session mobility between enterprise intranets and external
   networks.  The proposed solution minimizes changes to existing
   firewall/VPN/DMZ deployments and does not require any changes to
   IPsec or key exchange protocols.  It also proposes a mechanism to
   minimize IPsec renegotiation when the mobile node moves.



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8.1.3.  RFC 3776, Using IPsec to Protect Mobile IPv6 Signaling Between
        Mobile Nodes and Home Agents (S, June 2004)

   This document specifies the use of IPsec in securing Mobile IPv6
   traffic between mobile nodes and home agents.  It specifies the
   required wire formats for the protected packets and illustrates
   examples of Security Policy Database and Security Association
   Database entries that can be used to protect Mobile IPv6 signaling
   messages.  It also describes how to configure either manually keyed
   IPsec security associations or IKEv1 to establish the SAs
   automatically.  Mobile IPv6 requires considering the home address
   destination option and Routing Header in IPsec processing.  Also,
   IPsec and IKE security association addresses can be updated by Mobile
   IPv6 signaling messages.

8.1.4.  RFC 4877, Mobile IPv6 Operation with IKEv2 and the Revised IPsec
        Architecture (S, April 2007)

   This document updates [RFC3776] in order to work with the revised
   IPsec architecture [RFC4301].  Since the revised IPsec architecture
   expands the list of selectors to include the Mobility Header message
   type, it becomes much easier to differentiate between different
   mobility header messages.  Since the ICMP message type and code are
   also newly added as selectors, this document uses them to protect
   Mobile Prefix Discovery messages.  This document also specifies the
   use of IKEv2 configuration payloads for dynamic home address
   configuration.  Finally, this document describes the use of IKEv2 in
   order to set up the SAs for Mobile IPv6.

8.1.5.  RFC 5026, Mobile IPv6 Bootstrapping in Split Scenario
        (S, October 2007)

   [RFC5026] extends [RFC4877] to support dynamic discovery of home
   agents and the home network prefix; for the latter purpose, it
   specifies a new IKEv2 configuration attribute and notification.  It
   describes how a Mobile IPv6 node can obtain the address of its home
   agent, its home address, and create IPsec security associations with
   its home agent using DNS lookups and security credentials
   preconfigured on the Mobile Node.  It defines how a mobile node (MN)
   can request its home address and home prefixes through the
   Configuration Payload in the IKE_AUTH exchange and what attributes
   need to be present in the CFG_REQUEST messages in order to do this.
   It also specifies how the home agent can authorize the credentials
   used for IKEv2 exchange.







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8.1.6.  RFC 5213, Proxy Mobile IPv6 (S, August 2008)

   [RFC5213] describes a network-based mobility management protocol that
   is used to provide mobility services to hosts without requiring their
   participation in any mobility-related signaling.  It uses IPsec to
   protect the mobility signaling messages between the two network
   entities called the mobile access gateway (MAG) and the local
   mobility anchor (LMA).  It also uses IKEv2 in order to set up the
   security associations between the MAG and the LMA.

8.1.7.  RFC 5568, Mobile IPv6 Fast Handovers (S, July 2009)

   When Mobile IPv6 is used for a handover, there is a period during
   which the Mobile Node is unable to send or receive packets because of
   link switching delay and IP protocol operations.  [RFC5568] specifies
   a protocol between the Previous Access Router (PAR) and the New
   Access Router (NAR) to improve handover latency due to Mobile IPv6
   procedures.  It uses IPsec ESP in transport mode with integrity
   protection for protecting the signaling messages between the PAR and
   the NAR.  It also describes the SPD entries and the PAD entries when
   IKEv2 is used for setting up the required SAs.

8.1.8.  RFC 5380, Hierarchical Mobile IPv6 (HMIPv6) Mobility Management
        (S, October 2008)

   [RFC5380] describes extensions to Mobile IPv6 and IPv6 Neighbor
   Discovery to allow for local mobility handling in order to reduce the
   amount of signaling between the mobile node, its correspondent nodes,
   and its home agent.  It also improves handover speed of Mobile IPv6.
   It uses IPsec for protecting the signaling between the mobile node
   and a local mobility management entity called the Mobility Anchor
   Point (MAP).  The MAP also uses IPsec Peer Authorization Database
   (PAD) entries and configuration payloads described in [RFC4877] in
   order to allocate a Regional Care-of Address (RCoA) for mobile nodes.

8.2.  Open Shortest Path First (OSPF)

8.2.1.  RFC 4552, Authentication/Confidentiality for OSPFv3
        (S, June 2006)

   OSPF is a link-state routing protocol that is designed to be run
   inside a single Autonomous System.  OSPFv2 provided its own
   authentication mechanisms using the AuType and Authentication
   protocol header fields but OSPFv3 removed these fields and uses IPsec
   instead.  [RFC4552] describes how to use IPsec ESP and AH in order to
   protect OSPFv3 signaling between two routers.  It also enumerates the
   IPsec capabilities the routers require in order to support this
   specification.  Finally, it also describes the operation of OSPFv3



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   with IPsec over virtual links where the other endpoint is not known
   at configuration time.  Since OSPFv3 exchanges multicast packets as
   well as unicast ones, the use of IKE within OSPFv3 is not
   appropriate.  Therefore, this document mandates the use of manual
   keys.

8.3.  Host Identity Protocol (HIP)

8.3.1.  RFC 5201, Host Identity Protocol (E, April 2008)

   IP addresses perform two distinct functions: host identifier and
   locator.  This document specifies a protocol that allows consenting
   hosts to securely establish and maintain shared IP-layer state,
   allowing separation of the identifier and locator roles of IP
   addresses.  This enables continuity of communications across IP
   address (locator) changes.  It uses public key identifiers from a new
   Host Identity (HI) namespace for peer authentication.  It uses the
   HMAC-SHA-1-96 and the AES-CBC algorithms with IPsec ESP and AH for
   protecting its signaling messages.

8.3.2.  RFC 5202, Using the Encapsulating Security Payload (ESP)
        Transport Format with the Host Identity Protocol (HIP)
        (E, April 2008)

   The HIP base exchange specification [RFC5201] does not describe any
   transport formats or methods for describing how ESP is used to
   protect user data to be used during the actual communication.
   [RFC5202] specifies a set of HIP extensions for creating a pair of
   ESP Security Associations (SAs) between the hosts during the base
   exchange.  After the HIP association and required ESP SAs have been
   established between the hosts, the user data communication is
   protected using ESP.  In addition, this document specifies how the
   ESP Security Parameter Index (SPI) is used to indicate the right host
   context (host identity) and methods to update an existing ESP
   Security Association.

8.3.3.  RFC 5206, End-Host Mobility and Multihoming with the Host
        Identity (E, April 2008)

   When a host uses HIP, the overlying protocol sublayers (e.g.,
   transport layer sockets) and Encapsulating Security Payload (ESP)
   Security Associations (SAs) are bound to representations of these
   host identities, and the IP addresses are only used for packet
   forwarding.  [RFC5206] defines a generalized LOCATOR parameter for
   use in HIP messages that allows a HIP host to notify a peer about
   alternate addresses at which it is reachable.  It also specifies how
   a host can change its IP address and continue to send packets to its
   peers without necessarily rekeying.



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8.3.4.  RFC 5207, NAT and Firewall Traversal Issues of Host Identity
        Protocol (HIP) (I, April 2008)

   [RFC5207] discusses the problems associated with HIP communication
   across network paths that include network address translators and
   firewalls.  It analyzes the impact of NATs and firewalls on the HIP
   base exchange and the ESP data exchange.  It discusses possible
   changes to HIP that attempt to improve NAT and firewall traversal and
   proposes a rendezvous point for letting HIP nodes behind a NAT be
   reachable.  It also suggests mechanisms for NATs to be more aware of
   the HIP messages.

8.4.  Stream Control Transmission Protocol (SCTP)

8.4.1.  RFC 3554, On the Use of Stream Control Transmission Protocol
        (SCTP) with IPsec (S, July 2003)

   The Stream Control Transmission Protocol (SCTP) is a reliable
   transport protocol operating on top of a connection-less packet
   network such as IP.  [RFC3554] describes functional requirements for
   IPsec and IKE to be used in securing SCTP traffic.  It adds support
   for SCTP in the form of a new ID type in IKE [RFC2409] and
   implementation choices in the IPsec processing to account for the
   multiple source and destination addresses associated with a single
   SCTP association.  This document applies only to IKEv1 and IPsec-v2;
   it does not apply to IKEv2 AND IPsec-v3.

8.5.  Robust Header Compression (ROHC)

8.5.1.  RFC 3095, RObust Header Compression (ROHC): Framework and four
        profiles: RTP, UDP, ESP, and uncompressed (S, July 2001)

   ROHC is a framework for header compression, intended to be used in
   resource-constrained environments. [RFC3095] applies this framework
   to four protocols, including ESP.

8.5.2.  RFC 5225, RObust Header Compression Version 2 (ROHCv2): Profiles
        for RTP, UDP, IP, ESP, and UDP-Lite (S, April 2008)

   [RFC5225] defines an updated ESP/IP profile for use with ROHC version
   2.  It analyzes the ESP header and classifies the fields into several
   classes like static, well-known, irregular, etc., in order to
   efficiently compress the headers.








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8.5.3.  RFC 5856, Integration of Robust Header Compression over IPsec
        Security Associations (I, May 2010)

   [RFC5856] describes a mechanism to compress inner IP headers at the
   ingress point of IPsec tunnels and to decompress them at the egress
   point.  Since the Robust Header Compression (ROHC) specifications
   only describe operations on a per-hop basis, this document also
   specifies extensions to enable ROHC over multiple hops.  This
   document applies only to tunnel mode SAs and does not support
   transport mode SAs.

8.5.4.  RFC 5857, IKEv2 Extensions to Support Robust Header Compression
        over IPsec (S, May 2010)

   ROHC requires initial configuration at the compressor and
   decompressor ends.  Since ROHC usually operates on a per-hop basis,
   this configuration information is carried over link-layer protocols
   such as PPP.  Since [RFC5856] operates over multiple hops, a
   different signaling mechanism is required.  [RFC5857] describes how
   to use IKEv2 in order to dynamically communicate the configuration
   parameters between the compressor and decompressor.

8.5.5.  RFC 5858, IPsec Extensions to Support Robust Header Compression
        over IPsec (S, May 2010)

   [RFC5856] describes how to use ROHC with IPsec.  This is not possible
   without extensions to IPsec.  [RFC5858] describes the extensions
   needed to IPsec in order to support ROHC.  Specifically, it describes
   extensions needed to the IPsec SPD, SAD, and IPsec processing
   including ICV computation and integrity verification.

8.6.  Border Gateway Protocol (BGP)

8.6.1.  RFC 5566, BGP IPsec Tunnel Encapsulation Attribute
        (S, June 2009)

   [RFC5566] adds an additional BGP Encapsulation Subsequent Address
   Family Identifier (SAFI), allowing the use of IPsec and, optionally,
   IKE to protect BGP tunnels.  It defines the use of AH and ESP in
   tunnel mode and the use of AH and ESP in transport mode to protect IP
   in IP and MPLS-in-IP tunnels.  It also defines how public key
   fingerprints (hashes) are distributed via BGP and used later to
   authenticate IKEv2 exchange between the tunnel endpoints.

8.7.  IPsec Benchmarking

   The Benchmarking Methodology WG in the IETF is working on documents
   that relate to benchmarking IPsec [BMWG-1] [BMWG-2].



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8.7.1.  Methodology for Benchmarking IPsec Devices (Work in Progress)

   [BMWG-1] defines a set of tests that can be used to measure and
   report the performance characteristics of IPsec devices.  It extends
   the methodology defined for benchmarking network interconnecting
   devices to include IPsec gateways and adds further tests that can be
   used to measure IPsec performance of end-hosts.  The document focuses
   on establishing a performance testing methodology for IPsec devices
   that support manual keying and IKEv1, but does not cover IKEv2.

8.7.2.  Terminology for Benchmarking IPsec Devices (Work in Progress)

   [BMWG-2] defines the standardized performance testing terminology for
   IPsec devices that support manual keying and IKEv1.  It also
   describes the benchmark tests that would be used to test the
   performance of the IPsec devices.

8.8.  Network Address Translators (NAT)

8.8.1.  RFC 2709, Security Model with Tunnel-mode IPsec for NAT domains
        (I, October 1999)

   NAT devices provide transparent routing to end-hosts trying to
   communicate from disparate address realms, by modifying IP and
   transport headers en route.  This makes it difficult for applications
   to pursue end-to-end application-level security.  [RFC2709] describes
   a security model by which tunnel mode IPsec security can be
   architected on NAT devices.  It defines how NATs administer security
   policies and SA attributes based on private realm addressing.  It
   also specifies how to operate IKE in such scenarios by specifying an
   IKE-ALG (Application Level Gateway) that translates policies from
   private realm addressing into public addressing.  Although the model
   presented here uses terminology from IKEv1, it can be deployed within
   IKEv1, IKEv2, IPsec-v2, and IPsec-v3.  This security model has not
   been widely adopted

8.9.  Session Initiation Protocol (SIP)

8.9.1.  RFC 3329, Security Mechanism Agreement for the Session
        Initiation Protocol (SIP) (S, January 2003)

   [RFC3329] describes how a SIP client can select one of the various
   available SIP security mechanisms.  In particular, the method allows
   secure negotiation to prevent bidding down attacks.  It also
   describes a security mechanism called ipsec-3gpp and its associated
   parameters (algorithms, protocols, mode, SPIs and ports) as they are
   used in the 3GPP IP Multimedia Subsystem.




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8.10.  Explicit Packet Sensitivity Labels

8.10.1.  RFC 5570, Common Architecture Label IPv6 Security Option
        (CALIPSO) (I, July 2009)

   [RFC5570] describes a mechanism used to encode explicit packet
   Sensitivity Labels on IPv6 packets in Multi-Level Secure (MLS)
   networks.  The method is implemented using an IPv6 hop-by-hop option.
   This document uses the IPsec Authentication Header (AH) in order to
   detect any malicious modification of the Sensitivity Label in a
   packet.

9.  Other Protocols That Adapt IKE for Non-IPsec Functionality

   Some protocols protect their traffic through mechanisms other than
   IPsec, but use IKEv2 as a basis for their key negotiation and key
   management functionality.

9.1.  Extensible Authentication Protocol (EAP)

9.1.1.  RFC 5106, The Extensible Authentication Protocol-Internet Key
        Exchange Protocol version 2 (EAP-IKEv2) Method
        (E, February 2008)

   [RFC5106] specifies an Extensible Authentication Protocol (EAP)
   method that is based on the Internet Key Exchange version 2 (IKEv2)
   protocol.  EAP-IKEv2 provides mutual authentication and session-key
   establishment between an EAP peer and an EAP server.  It describes
   the full EAP-IKEv2 message exchange and the composition of the
   protocol messages.

9.2.  Fibre Channel

9.2.1.  RFC 4595, Use of IKEv2 in the Fibre Channel Security Association
        Management Protocol (I, July 2006)

   Fibre Channel (FC) is a gigabit-speed network technology used for
   Storage Area Networking.  The Fibre Channel Security Protocols (FC-
   SP) standard has adapted the IKEv2 protocol [RFC4306] to provide
   authentication of Fibre Channel entities and setup of security
   associations.  Since IP is transported over Fibre Channel and Fibre
   Channel is transported over IP, there is the potential for confusion
   when IKEv2 is used for both IP and FC traffic.  [RFC4595] specifies
   identifiers for IKEv2 over FC in a fashion that ensures that any
   mistaken usage of IKEv2/FC over IP or IKEv2/IP over FC will result in
   a negotiation failure due to the absence of an acceptable proposal.





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9.3.  Wireless Security

9.3.1.  RFC 4705, GigaBeam High-Speed Radio Link Encryption
        (I, October 2006)

   [RFC4705] describes the encryption and key management used by
   GigaBeam as part of the WiFiber(tm) family of radio-link products and
   is intended to serve as a guideline for similar wireless product
   development efforts to include comparable capabilities.  It specifies
   the algorithms that are used to provide confidentiality and integrity
   protection of both subscriber and management traffic.  It also
   specifies a custom security protocol that runs between two Gigabeam
   Radio Control Modules (RCMs).

10.  Acknowledgements

   The authors would like to thank Yaron Sheffer, Paul Hoffman, Yoav
   Nir, Rajeshwar Singh Jenwar, Alfred Hoenes, Al Morton, Gabriel
   Montenegro, Sean Turner, Julien Laganier, Grey Daley, Scott Moonen,
   Richard Graveman, Tero Kivinen, Pasi Eronen, Ran Atkinson, David
   Black, and Tim Polk for reviewing this document and suggesting
   changes.

11.  Security Considerations

   This RFC serves as a review of other documents and introduces no new
   security considerations itself; however, please see each of the
   individual documents described herein for security considerations
   related to each protocol.

12. References

12.1. Informative References

   [BMWG-1]   Kaeo, M. and T. Van Herck, "Methodology for Benchmarking
              IPsec Devices", Work in Progress, July 2009.

   [BMWG-2]   Kaeo, M., Van Herck T., and M. Bustos, "Terminology for
              Benchmarking IPsec Devices", Work in Progress, July 2009.

   [IKE-MODE-CFG]
              Dukes, D. and R. Pereira, "The ISAKMP Configuration
              Method", Work in Progress, September 2001.

   [IKE-XAUTH]
              Beaulieu, S. and R. Pereira, "Extended Authentication
              within IKE (XAUTH)", Work in Progress, October 2001.




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   [ISAKMP-MODE-CFG]
              Pereira, R., Anand, S., and B. Patel, "The ISAKKMP
              Configuration Method", Work in Progress, August 1999.

   [ISAKMP-XAUTH]
              Pereira, R. and S. Beaulieu, "Extended Authentication
              within ISAKMP/Oakley (XAUTH)", Work in Progress, December
              1999.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2026]  Bradner, S., "The Internet Standards Process -- Revision
              3", BCP 9, RFC 2026, October 1996.

   [RFC2394]  Pereira, R., "IP Payload Compression Using DEFLATE", RFC
              2394, December 1998.

   [RFC2395]  Friend, R. and R. Monsour, "IP Payload Compression Using
              LZS", RFC 2395, December 1998.

   [RFC2401]  Kent, S. and R. Atkinson, "Security Architecture for the
              Internet Protocol", RFC 2401, November 1998.

   [RFC2402]  Kent, S. and R. Atkinson, "IP Authentication Header", RFC
              2402, November 1998.

   [RFC2403]  Madson, C. and R. Glenn, "The Use of HMAC-MD5-96 within
              ESP and AH", RFC 2403, November 1998.

   [RFC2404]  Madson, C. and R. Glenn, "The Use of HMAC-SHA-1-96 within
              ESP and AH", RFC 2404, November 1998.

   [RFC2405]  Madson, C. and N. Doraswamy, "The ESP DES-CBC Cipher
              Algorithm With Explicit IV", RFC 2405, November 1998.

   [RFC2406]  Kent, S. and R. Atkinson, "IP Encapsulating Security
              Payload (ESP)", RFC 2406, November 1998.

   [RFC2407]  Piper, D., "The Internet IP Security Domain of
              Interpretation for ISAKMP", RFC 2407, November 1998.

   [RFC2408]  Maughan, D., Schertler, M., Schneider, M., and J. Turner,
              "Internet Security Association and Key Management Protocol
              (ISAKMP)", RFC 2408, November 1998.

   [RFC2409]  Harkins, D. and D. Carrel, "The Internet Key Exchange
              (IKE)", RFC 2409, November 1998.



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   [RFC2410]  Glenn, R. and S. Kent, "The NULL Encryption Algorithm and
              Its Use With IPsec", RFC 2410, November 1998.

   [RFC2411]  Thayer, R., Doraswamy, N., and R. Glenn, "IP Security
              Document Roadmap", RFC 2411, November 1998.

   [RFC2412]  Orman, H., "The OAKLEY Key Determination Protocol", RFC
              2412, November 1998.

   [RFC2451]  Pereira, R. and R. Adams, "The ESP CBC-Mode Cipher
              Algorithms", RFC 2451, November 1998.

   [RFC2521]  Karn, P. and W. Simpson, "ICMP Security Failures
              Messages", RFC 2521, March 1999.

   [RFC2709]  Srisuresh, P., "Security Model with Tunnel-mode IPsec for
              NAT Domains", RFC 2709, October 1999.

   [RFC2857]  Keromytis, A. and N. Provos, "The Use of HMAC-
              RIPEMD-160-96 within ESP and AH", RFC 2857, June 2000.

   [RFC3051]  Heath, J. and J. Border, "IP Payload Compression Using
              ITU-T V.44 Packet Method", RFC 3051, January 2001.

   [RFC3056]  Carpenter, B. and K. Moore, "Connection of IPv6 Domains
              via IPv4 Clouds", RFC 3056, February 2001.

   [RFC3095]  Bormann, C., Burmeister, C., Degermark, M., Fukushima, H.,
              Hannu, H., Jonsson, L-E., Hakenberg, R., Koren, T., Le,
              K., Liu, Z., Martensson, A., Miyazaki, A., Svanbro, K.,
              Wiebke, T., Yoshimura, T., and H. Zheng, "RObust Header
              Compression (ROHC): Framework and four profiles: RTP, UDP,
              ESP, and uncompressed", RFC 3095, July 2001.

   [RFC3129]  Thomas, M., "Requirements for Kerberized Internet
              Negotiation of Keys", RFC 3129, June 2001.

   [RFC3173]  Shacham, A., Monsour, B., Pereira, R., and M. Thomas, "IP
              Payload Compression Protocol (IPComp)", RFC 3173,
              September 2001.

   [RFC3329]  Arkko, J., Torvinen, V., Camarillo, G., Niemi, A., and T.
              Haukka, "Security Mechanism Agreement for the Session
              Initiation Protocol (SIP)", RFC 3329, January 2003.

   [RFC3456]  Patel, B., Aboba, B., Kelly, S., and V. Gupta, "Dynamic
              Host Configuration Protocol (DHCPv4) Configuration of
              IPsec Tunnel Mode", RFC 3456, January 2003.



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   [RFC3457]  Kelly, S. and S. Ramamoorthi, "Requirements for IPsec
              Remote Access Scenarios", RFC 3457, January 2003.

   [RFC3526]  Kivinen, T. and M. Kojo, "More Modular Exponential (MODP)
              Diffie-Hellman groups for Internet Key Exchange (IKE)",
              RFC 3526, May 2003.

   [RFC3547]  Baugher, M., Weis, B., Hardjono, T., and H. Harney, "The
              Group Domain of Interpretation", RFC 3547, July 2003.

   [RFC3554]  Bellovin, S., Ioannidis, J., Keromytis, A., and R.
              Stewart, "On the Use of Stream Control Transmission
              Protocol (SCTP) with IPsec", RFC 3554, July 2003.

   [RFC3566]  Frankel, S. and H. Herbert, "The AES-XCBC-MAC-96 Algorithm
              and Its Use With IPsec", RFC 3566, September 2003.

   [RFC3585]  Jason, J., Rafalow, L., and E. Vyncke, "IPsec
              Configuration Policy Information Model", RFC 3585, August
              2003.

   [RFC3586]  Blaze, M., Keromytis, A., Richardson, M., and L. Sanchez,
              "IP Security Policy (IPSP) Requirements", RFC 3586, August
              2003.

   [RFC3602]  Frankel, S., Glenn, R., and S. Kelly, "The AES-CBC Cipher
              Algorithm and Its Use with IPsec", RFC 3602, September
              2003.

   [RFC3686]  Housley, R., "Using Advanced Encryption Standard (AES)
              Counter Mode With IPsec Encapsulating Security Payload
              (ESP)", RFC 3686, January 2004.

   [RFC3706]  Huang, G., Beaulieu, S., and D. Rochefort, "A Traffic-
              Based Method of Detecting Dead Internet Key Exchange (IKE)
              Peers", RFC 3706, February 2004.

   [RFC3715]  Aboba, B. and W. Dixon, "IPsec-Network Address Translation
              (NAT) Compatibility Requirements", RFC 3715, March 2004.

   [RFC3740]  Hardjono, T. and B. Weis, "The Multicast Group Security
              Architecture", RFC 3740, March 2004.

   [RFC3776]  Arkko, J., Devarapalli, V., and F. Dupont, "Using IPsec to
              Protect Mobile IPv6 Signaling Between Mobile Nodes and
              Home Agents", RFC 3776, June 2004.





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   [RFC3830]  Arkko, J., Carrara, E., Lindholm, F., Naslund, M., and K.
              Norrman, "MIKEY: Multimedia Internet KEYing", RFC 3830,
              August 2004.

   [RFC3884]  Touch, J., Eggert, L., and Y. Wang, "Use of IPsec
              Transport Mode for Dynamic Routing", RFC 3884, September
              2004.

   [RFC3947]  Kivinen, T., Swander, B., Huttunen, A., and V. Volpe,
              "Negotiation of NAT-Traversal in the IKE", RFC 3947,
              January 2005.

   [RFC3948]  Huttunen, A., Swander, B., Volpe, V., DiBurro, L., and M.
              Stenberg, "UDP Encapsulation of IPsec ESP Packets", RFC
              3948, January 2005.

   [RFC4025]  Richardson, M., "A Method for Storing IPsec Keying
              Material in DNS", RFC 4025, March 2005.

   [RFC4046]  Baugher, M., Canetti, R., Dondeti, L., and F. Lindholm,
              "Multicast Security (MSEC) Group Key Management
              Architecture", RFC 4046, April 2005.

   [RFC4093]  Adrangi, F., Ed., and H. Levkowetz, Ed., "Problem
              Statement: Mobile IPv4 Traversal of Virtual Private
              Network (VPN) Gateways", RFC 4093, August 2005.

   [RFC4106]  Viega, J. and D. McGrew, "The Use of Galois/Counter Mode
              (GCM) in IPsec Encapsulating Security Payload (ESP)", RFC
              4106, June 2005.

   [RFC4109]  Hoffman, P., "Algorithms for Internet Key Exchange version
              1 (IKEv1)", RFC 4109, May 2005.

   [RFC4196]  Lee, H., Yoon, J., Lee, S., and J. Lee, "The SEED Cipher
              Algorithm and Its Use with IPsec", RFC 4196, October 2005.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, December 2005.

   [RFC4302]  Kent, S., "IP Authentication Header", RFC 4302, December
              2005.

   [RFC4303]  Kent, S., "IP Encapsulating Security Payload (ESP)", RFC
              4303, December 2005.






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   [RFC4304]  Kent, S., "Extended Sequence Number (ESN) Addendum to
              IPsec Domain of Interpretation (DOI) for Internet Security
              Association and Key Management Protocol (ISAKMP)", RFC
              4304, December 2005.

   [RFC4305]  Eastlake 3rd, D., "Cryptographic Algorithm Implementation
              Requirements for Encapsulating Security Payload (ESP) and
              Authentication Header (AH)", RFC 4305, December 2005.

   [RFC4306]  Kaufman, C., Ed., "Internet Key Exchange (IKEv2)
              Protocol", RFC 4306, December 2005.

   [RFC4307]  Schiller, J., "Cryptographic Algorithms for Use in the
              Internet Key Exchange Version 2 (IKEv2)", RFC 4307,
              December 2005.

   [RFC4308]  Hoffman, P., "Cryptographic Suites for IPsec", RFC 4308,
              December 2005.

   [RFC4309]  Housley, R., "Using Advanced Encryption Standard (AES) CCM
              Mode with IPsec Encapsulating Security Payload (ESP)", RFC
              4309, December 2005.

   [RFC4312]  Kato, A., Moriai, S., and M. Kanda, "The Camellia Cipher
              Algorithm and Its Use With IPsec", RFC 4312, December
              2005.

   [RFC4322]  Richardson, M. and D. Redelmeier, "Opportunistic
              Encryption using the Internet Key Exchange (IKE)", RFC
              4322, December 2005.

   [RFC4359]  Weis, B., "The Use of RSA/SHA-1 Signatures within
              Encapsulating Security Payload (ESP) and Authentication
              Header (AH)", RFC 4359, January 2006.

   [RFC4430]  Sakane, S., Kamada, K., Thomas, M., and J. Vilhuber,
              "Kerberized Internet Negotiation of Keys (KINK)", RFC
              4430, March 2006.

   [RFC4434]  Hoffman, P., "The AES-XCBC-PRF-128 Algorithm for the
              Internet Key Exchange Protocol (IKE)", RFC 4434, February
              2006.

   [RFC4478]  Nir, Y., "Repeated Authentication in Internet Key Exchange
              (IKEv2) Protocol", RFC 4478, April 2006.

   [RFC4494]  Song, JH., Poovendran, R., and J. Lee, "The AES-CMAC-96
              Algorithm and Its Use with IPsec", RFC 4494, June 2006.



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   [RFC4535]  Harney, H., Meth, U., Colegrove, A., and G. Gross,
              "GSAKMP: Group Secure Association Key Management
              Protocol", RFC 4535, June 2006.

   [RFC4543]  McGrew, D. and J. Viega, "The Use of Galois Message
              Authentication Code (GMAC) in IPsec ESP and AH", RFC 4543,
              May 2006.

   [RFC4552]  Gupta, M. and N. Melam, "Authentication/Confidentiality
              for OSPFv3", RFC 4552, June 2006.

   [RFC4555]  Eronen, P., "IKEv2 Mobility and Multihoming Protocol
              (MOBIKE)", RFC 4555, June 2006.

   [RFC4595]  Maino, F. and D. Black, "Use of IKEv2 in the Fibre Channel
              Security Association Management Protocol", RFC 4595, July
              2006.

   [RFC4615]  Song, J., Poovendran, R., Lee, J., and T. Iwata, "The
              Advanced Encryption Standard-Cipher-based Message
              Authentication Code-Pseudo-Random Function-128 (AES-CMAC-
              PRF-128) Algorithm for the Internet Key Exchange Protocol
              (IKE)", RFC 4615, August 2006.

   [RFC4621]  Kivinen, T. and H. Tschofenig, "Design of the IKEv2
              Mobility and Multihoming (MOBIKE) Protocol", RFC 4621,
              August 2006.

   [RFC4705]  Housley, R. and A. Corry, "GigaBeam High-Speed Radio Link
              Encryption", RFC 4705, October 2006.

   [RFC4718]  Eronen, P. and P. Hoffman, "IKEv2 Clarifications and
              Implementation Guidelines", RFC 4718, October 2006.

   [RFC4739]  Eronen, P. and J. Korhonen, "Multiple Authentication
              Exchanges in the Internet Key Exchange (IKEv2) Protocol",
              RFC 4739, November 2006.

   [RFC4753]  Fu, D. and J. Solinas, "ECP Groups For IKE and IKEv2", RFC
              4753, January 2007.

   [RFC4754]  Fu, D. and J. Solinas, "IKE and IKEv2 Authentication Using
              the Elliptic Curve Digital Signature Algorithm (ECDSA)",
              RFC 4754, January 2007.

   [RFC4806]  Myers, M. and H. Tschofenig, "Online Certificate Status
              Protocol (OCSP) Extensions to IKEv2", RFC 4806, February
              2007.



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   [RFC4807]  Baer, M., Charlet, R., Hardaker, W., Story, R., and C.
              Wang, "IPsec Security Policy Database Configuration MIB",
              RFC 4807, March 2007.

   [RFC4809]  Bonatti, C., Ed., Turner, S., Ed., and G. Lebovitz, Ed.,
              "Requirements for an IPsec Certificate Management
              Profile", RFC 4809, February 2007.

   [RFC4835]  Manral, V., "Cryptographic Algorithm Implementation
              Requirements for Encapsulating Security Payload (ESP) and
              Authentication Header (AH)", RFC 4835, April 2007.

   [RFC4868]  Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-
              SHA-384, and HMAC-SHA-512 with IPsec", RFC 4868, May 2007.

   [RFC4869]  Law, L. and J. Solinas, "Suite B Cryptographic Suites for
              IPsec", RFC 4869, May 2007.

   [RFC4877]  Devarapalli, V. and F. Dupont, "Mobile IPv6 Operation with
              IKEv2 and the Revised IPsec Architecture", RFC 4877, April
              2007.

   [RFC4891]  Graveman, R., Parthasarathy, M., Savola, P., and H.
              Tschofenig, "Using IPsec to Secure IPv6-in-IPv4 Tunnels",
              RFC 4891, May 2007.

   [RFC4894]  Hoffman, P., "Use of Hash Algorithms in Internet Key
              Exchange (IKE) and IPsec", RFC 4894, May 2007.

   [RFC4945]  Korver, B., "The Internet IP Security PKI Profile of
              IKEv1/ISAKMP, IKEv2, and PKIX", RFC 4945, August 2007.

   [RFC5026]  Giaretta, G., Ed., Kempf, J., and V. Devarapalli, Ed.,
              "Mobile IPv6 Bootstrapping in Split Scenario", RFC 5026,
              October 2007.

   [RFC5106]  Tschofenig, H., Kroeselberg, D., Pashalidis, A., Ohba, Y.,
              and F. Bersani, "The Extensible Authentication Protocol-
              Internet Key Exchange Protocol version 2 (EAP-IKEv2)
              Method", RFC 5106, February 2008.

   [RFC5114]  Lepinski, M. and S. Kent, "Additional Diffie-Hellman
              Groups for Use with IETF Standards", RFC 5114, January
              2008.

   [RFC5201]  Moskowitz, R., Nikander, P., Jokela, P., Ed., and T.
              Henderson, "Host Identity Protocol", RFC 5201, April 2008.




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   [RFC5202]  Jokela, P., Moskowitz, R., and P. Nikander, "Using the
              Encapsulating Security Payload (ESP) Transport Format with
              the Host Identity Protocol (HIP)", RFC 5202, April 2008.

   [RFC5206]  Nikander, P., Henderson, T., Ed., Vogt, C., and J. Arkko,
              "End-Host Mobility and Multihoming with the Host Identity
              Protocol", RFC 5206, April 2008.

   [RFC5207]  Stiemerling, M., Quittek, J., and L. Eggert, "NAT and
              Firewall Traversal Issues of Host Identity Protocol (HIP)
              Communication", RFC 5207, April 2008.

   [RFC5213]  Gundavelli, S., Ed., Leung, K., Devarapalli, V.,
              Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC
              5213, August 2008.

   [RFC5225]  Pelletier, G. and K. Sandlund, "RObust Header Compression
              Version 2 (ROHCv2): Profiles for RTP, UDP, IP, ESP and
              UDP-Lite", RFC 5225, April 2008.

   [RFC5265]  Vaarala, S. and E. Klovning, "Mobile IPv4 Traversal across
              IPsec-Based VPN Gateways", RFC 5265, June 2008.

   [RFC5266]  Devarapalli, V. and P. Eronen, "Secure Connectivity and
              Mobility Using Mobile IPv4 and IKEv2 Mobility and
              Multihoming (MOBIKE)", BCP 136, RFC 5266, June 2008.

   [RFC5282]  Black, D. and D. McGrew, "Using Authenticated Encryption
              Algorithms with the Encrypted Payload of the Internet Key
              Exchange version 2 (IKEv2) Protocol", RFC 5282, August
              2008.

   [RFC5380]  Soliman, H., Castelluccia, C., ElMalki, K., and L.
              Bellier, "Hierarchical Mobile IPv6 (HMIPv6) Mobility
              Management", RFC 5380, October 2008.

   [RFC5386]  Williams, N. and M. Richardson, "Better-Than-Nothing
              Security: An Unauthenticated Mode of IPsec", RFC 5386,
              November 2008.

   [RFC5374]  Weis, B., Gross, G., and D. Ignjatic, "Multicast
              Extensions to the Security Architecture for the Internet
              Protocol", RFC 5374, November 2008.

   [RFC5387]  Touch, J., Black, D., and Y. Wang, "Problem and
              Applicability Statement for Better-Than-Nothing Security
              (BTNS)", RFC 5387, November 2008.




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   [RFC5406]  Bellovin, S., "Guidelines for Specifying the Use of IPsec
              Version 2", BCP 146, RFC 5406, February 2009.

   [RFC5529]  Kato, A., Kanda, M., and S. Kanno, "Modes of Operation for
              Camellia for Use with IPsec", RFC 5529, April 2009.

   [RFC5566]  Berger, L., White, R., and E. Rosen, "BGP IPsec Tunnel
              Encapsulation Attribute", RFC 5566, June 2009.

   [RFC5568]  Koodli, R., Ed., "Mobile IPv6 Fast Handovers", RFC 5568,
              July 2009.

   [RFC5570]  StJohns, M., Atkinson, R., and G. Thomas, "Common
              Architecture Label IPv6 Security Option (CALIPSO)", RFC
              5570, July 2009.

   [RFC5660]  Williams, N., "IPsec Channels: Connection Latching", RFC
              5660, October 2009.

   [RFC5685]  Devarapalli, V. and K. Weniger, "Redirect Mechanism for
              the Internet Key Exchange Protocol Version 2 (IKEv2)", RFC
              5685, November 2009.

   [RFC5723]  Sheffer, Y. and H. Tschofenig, "Internet Key Exchange
              Protocol Version 2 (IKEv2) Session Resumption", RFC 5723,
              January 2010.

   [RFC5739]  Eronen, P., Laganier, J., and C. Madson, "IPv6
              Configuration in Internet Key Exchange Protocol Version 2
              (IKEv2)", RFC 5739, February 2010.

   [RFC5840]  Grewal, K., Montenegro, G., and M. Bhatia, "Wrapped
              Encapsulating Security Payload (ESP) for Traffic
              Visibility", RFC 5840, April 2010.

   [RFC5856]  Ertekin, E., Jasani, R., Christou, C., and C. Bormann,
              "Integration of Robust Header Compression over IPsec
              Security Associations", RFC 5856, May 2010.

   [RFC5857]  Ertekin, E., Christou, C., Jasani, R., Kivinen, T., and C.
              Bormann, "IKEv2 Extensions to Support Robust Header
              Compression over IPsec", RFC 5857, May 2010.

   [RFC5858]  Ertekin, E., Christou, C., and C. Bormann, "IPsec
              Extensions to Support Robust Header Compression over
              IPsec", RFC 5858, May 2010.





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   [RFC5879]  Kivinen, T. and D. McDonald, "Heuristics for Detecting
              ESP-NULL Packets", RFC 5879, May 2010.

   [RFC5903]  Fu, D. and J. Solinas, "Elliptic Curve Groups modulo a
              Prime (ECP Groups) for IKE and IKEv2", RFC 5903, June
              2010.

   [RFC5930]  Shen, S., Mao, Y., and NSS. Murthy, "Using Advanced
              Encryption Standard Counter Mode (AES-CTR) with the
              Internet Key Exchange version 02 (IKEv2) Protocol", RFC
              5930, July 2010.

   [RFC5996]  Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen,
              "Internet Key Exchange Protocol Version 2 (IKEv2)", RFC
              5996, September 2010.

   [RFC5998]  Eronen, P., Tschofenig, H., and Y. Sheffer, "An Extension
              for EAP-Only Authentication in IKEv2", RFC 5998, September
              2010.

   [RFC6027]  Nir, Y., "IPsec Cluster Problem Statement", RFC 6027,
              October 2010.





























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Appendix A.  Summary of Algorithm Requirement Levels

                   Table 1: Algorithm Requirement Levels

 +--------------------------+----------------------------------------+
 |         ALGORITHM        |            REQUIREMENT LEVEL           |
 |                          | IKEv1     IKEv2     IPsec-v2  IPsec-v3 |
 +--------------------------+----------------------------------------+
 |Encryption Algorithms:                                             |
 |---------------------                                              |
 | ESP-NULL                 | N/A       N/A       MUST      MUST     |
 |                          |                                        |
 | 3DES-CBC                 | MUST      MUST-     MUST      MUST-    |
 |                          |                                        |
 | Blowfish/CAST/IDEA/RC5   | optional  optional  optional  optional |
 |                          |                                        |
 | AES-CBC 128-bit key      | SHOULD    SHOULD+   MUST      MUST     |
 |                          |                                        |
 | AES-CBC 192/256-bit key  | optional  optional  optional  optional |
 |                          |                                        |
 | AES-CTR                  | undefined optional  SHOULD    SHOULD   |
 |                          |                                        |
 | Camellia-CBC             | optional  optional  optional  optional |
 |                          |                                        |
 | Camellia-CTR             | undefined undefined undefined optional |
 |                          |                                        |
 | SEED-CBC                 | undefined undefined optional  undefined|
 |                          |                                        |
 |Integrity-Protection Algorithms:                                   |
 |------------------------------                                     |
 | HMAC-SHA-1               | MUST      MUST      MUST      MUST     |
 |                          |                                        |
 | AES-XCBC-MAC             | undefined optional  SHOULD+   SHOULD+  |
 |                          |                                        |
 | HMAC-SHA-256/384/512     | optional  optional  optional  optional |
 |                          |                                        |
 | AES-GMAC                 | N/A       N/A       undefined optional |
 |                          |                                        |
 | HMAC-MD5                 | MAY       optional  MAY       MAY      |
 |                          |                                        |
 | AES-CMAC                 | undefined optional  undefined optional |
 |                          |                                        |
 | HMAC-RIPEMD              | undefined undefined optional  undefined|
 +--------------------------+----------------------------------------+







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RFC 6071                    IPsec/IKE Roadmap              February 2011


           Table 1: Algorithm Requirement Levels (continued)

 +--------------------------+----------------------------------------+
 |         ALGORITHM        |            REQUIREMENT LEVEL           |
 |                          | IKEv1     IKEv2     IPsec-v2  IPsec-v3 |
 +--------------------------+----------------------------------------+
 |Combined Mode Algorithms:                                          |
 |------------------------                                           |
 | AES-CCM                  | N/A       optional  N/A       optional |
 |                          |                                        |
 | AES-GCM                  | N/A       optional  N/A       optional |
 |                          |                                        |
 | AES-GMAC                 | N/A       N/A       undefined optional |
 |                          |                                        |
 | Camellia-CCM             | N/A       undefined N/A       optional |
 |                          |                                        |
 |Pseudorandom Functions:                                            |
 |-----------------------                                            |
 | PRF-HMAC-SHA1            | MUST      MUST                         |
 |                          |                                        |
 | PRF-HMAC-SHA-256/384/512 | optional  optional                     |
 |                          |                                        |
 | AES-XCBC-PRF             | undefined SHOULD+                      |
 |                          |                                        |
 | AES-CMAC-PRF             | undefined optional                     |
 |                          |                                        |
 |Diffie-Hellman Algorithms:                                         |
 |-------------------------                                          |
 | DH MODP grp 1            | MAY       optional                     |
 |                          |                                        |
 | DH MODP grp 2            | MUST      MUST-                        |
 |                          |                                        |
 | DH MODP grp 5            | optional  optional                     |
 |                          |                                        |
 | DH MODP grp 14           | SHOULD    SHOULD+                      |
 |                          |                                        |
 | DH MODP grp 15-18        | optional  optional                     |
 |                          |                                        |
 | DH MODP grp 22-24        | optional  optional                     |
 |                          |                                        |
 | DH EC grp 3-4            | MAY       undefined                    |
 |                          |                                        |
 | DH EC grp 19-21          | optional  optional                     |
 |                          |                                        |
 | DH EC grp 25-26          | optional  optional                     |
 +--------------------------+----------------------------------------+





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RFC 6071                    IPsec/IKE Roadmap              February 2011


Authors' Addresses

   Sheila Frankel
   NIST
   Bldg. 223 Rm. B366
   Gaithersburg, MD 20899

   Phone: 1-301-975-3297
   EMail: sheila.frankel@nist.gov


   Suresh Krishnan
   Ericsson
   8400 Decarie Blvd.
   Town of Mount Royal, QC
   Canada

   Phone: 1-514-345-7900 x42871
   EMail: suresh.krishnan@ericsson.com
































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