OSPF Working Group                                             M. Bhatia
Internet-Draft                                            Alcatel-Lucent
Intended status: Standards Track                               V. Manral
Expires: October 16, 2011                                    IP Infusion
                                                               A. Lindem
                                                                Ericsson
                                                          April 14, 2011


              Supporting Authentication Trailer for OSPFv3
                 draft-ietf-ospf-auth-trailer-ospfv3-04

Abstract

   Currently OSPFv3 uses IPsec for authenticating protocol packets.
   However, there are some environments, e.g., Mobile Ad-hoc Networks
   (MANETs), where IPsec is difficult to configure and maintain, and
   this mechanism cannot be used.  This draft proposes an alternative
   mechanism that can be used so that OSPFv3 does not depend upon IPsec
   for authentication.

Status of this Memo

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

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

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

   This Internet-Draft will expire on October 16, 2011.

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
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect



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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Requirements Section . . . . . . . . . . . . . . . . . . .  4
   2.  Proposed Solution  . . . . . . . . . . . . . . . . . . . . . .  5
     2.1.  AT-Bit in Options Field  . . . . . . . . . . . . . . . . .  5
     2.2.  Basic Operation  . . . . . . . . . . . . . . . . . . . . .  6
   3.  OSPFv3 Security Association  . . . . . . . . . . . . . . . . .  7
   4.  Authentication Procedure . . . . . . . . . . . . . . . . . . .  9
     4.1.  Authentication Trailer . . . . . . . . . . . . . . . . . .  9
     4.2.  OSPFv3 Header Checksum . . . . . . . . . . . . . . . . . . 10
     4.3.  Cryptographic Authentication Procedure . . . . . . . . . . 10
     4.4.  Cryptographic Aspects  . . . . . . . . . . . . . . . . . . 11
     4.5.  Message Verification . . . . . . . . . . . . . . . . . . . 13
   5.  Migration and Backward Compatibility . . . . . . . . . . . . . 15
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 17
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 18
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 18
   Appendix A.  Acknowledgments . . . . . . . . . . . . . . . . . . . 20
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21























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1.  Introduction

   Unlike Open Shortest Path First version 2 (OSPFv2) [RFC2328], OSPF
   for IPv6 (OSPFv3) [RFC5340], does not include the AuType and
   Authentication fields in its headers for authenticating protocol
   packets.  Instead, OSPFv3 relies on the IPv6 Authentication Header
   (AH)[RFC4302] and IPv6 Encapsulating Security Payload (ESP) [RFC4303]
   to provide integrity, authentication, and/or confidentiality.

   [RFC4552] describes how IPv6 AH and ESP extension headers can be used
   to provide authentication and/or confidentiality to OSPFv3.

   However, there are some environments, e.g., Mobile Ad-hoc Networks
   (MANETs), where IPsec is difficult to configure and maintain, and
   this mechanism cannot be used.  There is also an issue with IPsec not
   being available on some platforms or it requiring an additional
   license.

   [RFC4552] discusses, at length, the reasoning behind using manually
   configured keys, rather than some automated key management protocol
   such as IKEv2 [RFC5996].  The primary problem is the lack of suitable
   key management mechanism, as OSPF adjacencies are formed on a one-to-
   many basis and most key management mechanisms are designed for a one-
   to-one communication model.  This forces the system administrator to
   use manually configured security associations (SAs) and cryptographic
   keys to provide the authentication and, if desired, confidentiality
   services.

   Regarding replay protection [RFC4552] states that:

   "As it is not possible as per the current standards to provide
   complete replay protection while using manual keying, the proposed
   solution will not provide protection against replay attacks."

   Since there is no replay protection provided there are a number of
   vulnerabilities in OSPFv3 which have been discussed in [RFC6039].

   Since there is no deterministic way to differentiate between
   encrypted and unencrypted ESP packets by simply examining the packet,
   it could become tricky for some implementations to prioritize certain
   OSPFv3 packets (Hellos for example) over the others.

   This draft proposes a new mechanism that works similar to OSPFv2
   [RFC5709]for providing authentication to the OSPFv3 packets and
   attempts to solve the problems described above for OSPFv3.

   Additionally this document describes how HMAC-SHA authentication can
   be used for OSPFv3.



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   By definition, HMAC ([RFC2104] , [FIPS-198]) requires a cryptographic
   hash function.  This document proposes to use any one of SHA-1, SHA-
   256, SHA-384, or SHA-512 [FIPS-180-3] to authenticate the OSPFv3
   packets.

   It is believed that [RFC2104] is mathematically identical to
   [FIPS-198] and it is also believed that algorithms in [RFC4634] are
   mathematically identical to [FIPS-180-3].

1.1.  Requirements Section

   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 [RFC2119].

   When used in lowercase, these words convey their typical use in
   common language, and are not to be interpreted as described in
   RFC2119 [RFC2119].

































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2.  Proposed Solution

   To perform non-IPsec cryptographic authentication, OSPFv3 routers
   append a special data block, henceforth referred to as, the
   authentication trailer to the end of the OSPFv3 packets.  The length
   of the authentication trailer is not included into the length of the
   OSPFv3 packet, but is included in the IPv6 payload length.

    +---------------------+ --              --  +----------------------+
    | IPv6 Header Length  | ^               ^   | IPv6 Header Length   |
    | HL = PL + LL        | |               |   | HL = PL + LL + AL    |
    |                     | v               v   |                      |
    +---------------------+ --              --  +----------------------+
    | OSPF Header         | ^               ^   | OSPFv3 Header        |
    | Length = PL         | |               |   | Length = PL          |
    |                     | |               |   |                      |
    |.....................| |    Packet     |   |......................|
    |                     | |    Length     |   |                      |
    | OSPFv3 Packet       | |               |   | OSPFv3 Packet        |
    |                     | v               v   |                      |
    +---------------------+ --              --  +----------------------+
    |                     | ^               ^   |                      |
    | Optional LLS        | |    LLS Data   |   | Optional LLS         |
    | LLS Block Len = LL  | |    Block      |   | LLS Block Len = LL   |
    |                     | v    Length     v   |                      |
    +---------------------+ --              --  +----------------------+
                                            ^   |                      |
                       AL = HL - (PL + LL)  |   | Authentication       |
                                            |   | AL = Fixed Trailer + |
                                            v   |      Digest Length   |
                                            --  +----------------------+

                Figure 1: Authentication Trailer in OSPFv3

   The presence of the Link Local Signaling (LLS) [RFC5613] block, is
   determined by the L-bit setting in OSPFv3 options field in OSPFv3
   Hello and Database Description packets.  If present, the LLS block is
   included along with the OSPFv3 packet in the cryptographic
   authentication computation.

2.1.  AT-Bit in Options Field

   A new AT-bit (AT stands for Authentication Trailer) is introduced
   into the OSPFv3 Options field.  OSPFv3 routers MUST set the AT-bit in
   OSPFv3 Hello and Database Description packets to indicate that the
   OSPFv3 router will include the authentication trailer in all OSPFv3
   packets on the link.  For OSPFv3 Hello and Database Description
   packets, the AT-bit indicates the AT is present.  For other OSPFv3



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   packet types, the OSPFv3 AT bit setting is preserved from the OSPFv3
   Hello/Database Description setting.


           0                   1                      2
           0 1 2 3 4 5 6 7 8 9 0 1 2 3  4 5  6 7 8  9 0 1  2 3
           +-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+--+-+-+--+-+-+--+-+--+
           | | | | | | | | | | | | | |AT|L|AF|*|*|DC|R|N|MC|E|V6|
           +-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+--+-+-+--+-+-+--+-+--+


                      Figure 2: OSPFv3 Options Field

   The AT-bit must be set in all OSPFv3 Hello and Database Description
   packets that contain an authentication trailer.

2.2.  Basic Operation

   The procedure followed for computing the Authentication Trailer is
   much same as described in [RFC5709] and [RFC2328].  One difference is
   that the LLS block, if present, is included in the cryptographic
   authentication computation.

   The way the authentication data is carried in the Authentication
   Trailer is very similar to how it is done in case of [RFC2328].  The
   only difference between the OSPFv2 authentication trailer and the
   OSPFv3 authentication trailer is that information in addition to the
   message digest is included.

   Consistent with OSPFv2 cryptographic authentication [RFC2328], both
   OSPFv3 header checksum calculation and verification are omitted when
   the OSPFv3 authentication mechanisms described in this specification
   are used.


















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3.  OSPFv3 Security Association

   An OSPFv3 Security Association (SA) contains a set of parameters
   shared between any two legitimate OSPFv3 speakers.

   Parameters associated with an OSPFv3 SA:

   o  Security Association Identifier (SA ID)

      This is a 32-bit unsigned integer used to uniquely identify an
      OSPFv3 SA, as manually configured by the network operator.

      The receiver determines the active SA by looking at the SA ID
      field in the incoming protocol packet.

      The sender based on the active configuration, selects an SA to use
      and puts the correct Key ID value associated with the SA in the
      OSPFV3 protocol packet.  If multiple valid and active OSPFv3 SAs
      exist for a given interface, the sender may use any of those SAs
      to protect the packet.

      Using SA IDs makes changing keys while maintaining protocol
      operation convenient.  Each SA ID specifies two independent parts,
      the authentication protocol and the authentication key, as
      explained below.

      Normally, an implementation would allow the network operator to
      configure a set of keys in a key chain, with each key in the chain
      having fixed lifetime.  The actual operation of these mechanisms
      is outside the scope of this document.

      Note that each SA ID can indicate a key with a different
      authentication protocol.  This allows the introduction of new
      authentication mechanisms without disrupting existing OSPFv3
      adjacencies.

   o  Authentication Algorithm

      This signifies the authentication algorithm to be used with the
      OSPFv3 SA.  This information is never sent in clear text over the
      wire.  Because this information is not sent on the wire, the
      implementer chooses an implementation specific representation for
      this information.

      Currently, the following algorithms are supported:

      HMAC-SHA-1, HMAC-SHA-256, HMAC-SHA-384, and HMAC-SHA-512.




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   o  Authentication Key

      This value denotes the cryptographic authentication key associated
      with the OSPFv3 SA.  The length of this key is variable and
      depends upon the authentication algorithm specified by the OSPFv3
      SA.













































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4.  Authentication Procedure

4.1.  Authentication Trailer

   The authentication trailer that is appended to the OSPFv3 protocol
   packet is described below:


      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |             Auth Type         |        Auth Data Len          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               Security Association ID (SA ID)                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |           Cryptographic Sequence Number (High Order 32 Bits)  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |           Cryptographic Sequence Number (Low Order 32 Bits)   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     |                Authentication Data (Variable)                 |
     ~                                                               ~
     |                                                               |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                  Figure 3: Authentication Trailer Format

   The various fields in the Authentication trailer are:

   o  Auth Type

      16-bit field identifying the type of authentication.  The
      following values are defined in this specification:

         0 - Reserved.
         1 - Cryptographic Authentication as described herein.

   o  Auth Data Len

      The length in bytes of the message digest appended to the OSPF
      packet.

   o  Security Association Identifier (SA ID)

      32-bit field that identifies the algorithm and the secret key used
      to create the message digest appended to the OSPFv3 protocol



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      packet.  Key Identifiers are unique per-interface.

   o  Cryptographic Sequence Number

      64-bit strictly increasing sequence number that is used to guard
      against replay attacks.  The 64-bit sequence number MUST be
      incremented for every OSPFv3 packet sent by the OSPFv3 router.
      Upon reception, the sequence number MUST be greater than the
      sequence number in the last OSPFv3 packet accepted from the
      sending OSPFv3 neighbor.  Otherwise, the OSPFv3 packet is
      considered a replayed packet and dropped.

      OSPFv3 routers implementing this specification SHOULD use
      available mechanisms to preserve the sequence number's strictly
      increasing property for the deployed life of the OSPFv3 router
      (including cold restarts).  Techiques such as sequence number
      space partitioning and non-volatile storage preservation can be
      used but are beyond the scope of this specification.

   o  Authentication Data

      Variable data that is carrying the digest for the protocol packet
      and optional LLS block.

4.2.  OSPFv3 Header Checksum

   Both OSPFv3 header checksum calculation and verification are omitted
   when the OSPFv3 authentication mechanisms described in this
   specification are used.  This implies:

   o  For OSPFv3 packets to be transmitted, the OSPFv3 header checksum
      computation is omitted and the OSPFv3 header checksum SHOULD be
      set to 0 prior to computation of the OSPFv3 Authentication Trailer
      message digest.

   o  For received OSPFv3 packets including an OSPFv3 Authentication
      Trailer, OSPFv3 header checksum verification MUST be omitted.

4.3.  Cryptographic Authentication Procedure

   As noted earlier, the SA ID implicitly specifies the algorithms used
   to generate and verify the message digest.  This specification
   discusses the computation of OSPFv3 Cryptographic Authentication data
   when any of the NIST SHS family of algorithms is used in the Hashed
   Message Authentication Code (HMAC) mode.

   The currently valid algorithms (including mode) for OSPFv3
   Cryptographic Authentication include:



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   HMAC-SHA-1, HMAC-SHA-256, HMAC-SHA-384 and HMAC-SHA-512

   Of the above, implementations of this specification MUST include
   support for at least HMAC-SHA-1 and SHOULD include support for HMAC-
   SHA-256 and MAY also include support for HMAC-SHA-384 and HMAC-SHA-
   512.

4.4.  Cryptographic Aspects

   In the algorithm description below, the following nomenclature, which
   is consistent with [FIPS-198], is used:

   H is the specific hashing algorithm (e.g.  SHA-256).

   K is the Authentication Key for the OSPFv3 security association.

   Ko is the cryptographic key used with the hash algorithm.

   B is the block size of H, measured in octets rather than bits.

   Note that B is the internal block size, not the hash size.

      For SHA-1 and SHA-256: B == 64

      For SHA-384 and SHA-512: B == 128

   L is the length of the hash, measured in octets rather than bits.

   XOR is the exclusive-or operation.

   Opad is the hexadecimal value 0x5c repeated B times.

   Ipad is the hexadecimal value 0x36 repeated B times.

   Apad is the hexadecimal value 0x878FE1F3 repeated (L/4) times.

   Implementation Note:

   This definition of Apad means that Apad is always the same length as
   the hash output.

   1.  Preparation of the Key

       In this application, Ko is always L octets long.

       If the Authentication Key (K) is L octets long, then Ko is equal
       to K. If the Authentication Key (K) is more than L octets long,
       then Ko is set to H(K).  If the Authentication Key (K) is less



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       than L octets long, then Ko is set to the Authentication Key (K)
       with zeros appended to the end of the Authentication Key (K) such
       that Ko is L octets long.

   2.  First Hash

       First, the OSPFv3 packet's Authentication Trailer (which is very
       similar to the appendage described in RFC 2328, Section D.4.3,
       Page 233, items(6)(a) and (6)(d)) is filled with the value Apad.

       Then, a First-Hash, also known as the inner hash, is computed as
       follows:

          First-Hash = H(Ko XOR Ipad || (OSPFv3 Packet))

       Implementation Notes:

          Note that the First-Hash above includes the Authentication
          Trailer containing the Apad value, as well as the OSPFv3
          packet, as per RFC 2328, Section D.4.3 and, if present, the
          LLS block[RFC5613].

       The definition of Apad (above) ensures it is always the same
       length as the hash output.  This is consistent with RFC 2328.
       The "(OSPFv3 Packet)" mentioned in the First-Hash (above) does
       include both the optional LLS block and the OSPF Authentication
       Trailer.

       The digest length for SHA-1 is 20 bytes; for SHA-256, 32 bytes;
       for SHA-384, 48 bytes; and for SHA-512, 64 bytes.

   3.  Second Hash

       Then a second hash, also known as the outer hash, is computed as
       follows:


          Second-Hash = H(Ko XOR Opad || First-Hash)

   4.  Result

       The resulting Second-Hash becomes the authentication data that is
       sent in the Authentication Trailer of the OSPFv3 packet.  The
       length of the authentication data is always identical to the
       message digest size of the specific hash function H that is being
       used.

       This also means that the use of hash functions with larger output



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       sizes will also increase the size of the OSPFv3 packet as
       transmitted on the wire.

       Implementation Note:

          RFC 2328, Appendix D specifies that the Authentication Trailer
          is not counted in the OSPF packet's own Length field, but is
          included in the packet's IP Length field.  Similar to this,
          the Authentication Trailer is not included in OSPFv3's own
          Length field, but is included in IPv6's payload length.

4.5.  Message Verification

   A router would determine that OSPFv3 is using an Authentication
   trailer by examining the AT-bit in the Options field in the OSPFv3
   header for Hello and Database Description packets.  The specification
   in the Hello and Database description options indicates that other
   OSPFv3 packets will include the authentication trailer.

   The Authentication Trailer (AT) is accessed using the OSPFv3 packet
   header length to access the data after the OSPFv3 packet and, if an
   LLS Data Block [RFC5613] is present, using the LLS Data Block Length
   to access the data after the LLS Data Block.  The L-bit in the OSPFv3
   options in Hello and Database Description packets is examined to
   determine if an LLS Data Block is present.  If an LLS block is
   present (as specified by the L-bit), it is included along with the
   OSPFv3 Hello or Database Description packet in the cryptographic
   authentication computation.

   Due to the placement of the AT following the LLS block and the fact
   that the LLS block is included in the cryptographic authentication
   computation, OSPFv3 routers supporting this specification MUST
   minimally support examining the L-bit in the OSPFv3 options and using
   the length in the LLS block to access the AT.  It is RECOMMENDED that
   OSPFv3 routers supporting this specification fully support OSPFv3
   Link Local Signaling, [RFC5613].

   If usage of the Authentication Trailer (AT), as specified herein, is
   configured for an OSPFv3 link, OSPFv3 Hello and Database Description
   packets with the AT-bit clear in the options will be dropped.  All
   OSPFv3 packet types will be dropped if AT is configured for the link
   and the IPv6 header length is less than the amount necessary to
   include an authentication trailer.

   If the cryptographic sequence number in the AT is less than or equal
   to the last sequence number received from the neighbor, the OSPFv3
   packet MUST be dropped.




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   Authentication algorithm dependent processing needs to be performed,
   using the algorithm specified by the appropriate OSPFv3 SA for the
   received packet.

   Before an implementation performs any processing it needs to save the
   values of the Authentication data field from the Authentication
   Trailer appended to the OSPFv3 packet.

   It should then set the Authentication data field with Apad before the
   authentication data is computed.  The calculated data is compared
   with the received authentication data in the Authentication trailer
   and the packet MUST be discarded if the two do not match.  In such a
   case, an error event SHOULD be logged.






































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5.  Migration and Backward Compatibility

   In general, all OSPFv3 routers participating on a link should be
   migrated to OSPFv3 Authentication at the same time.  As with OSPFv2
   authentication, a mismatch in the SA ID, Authentication Type, or
   message digest will result in failure to form an adjacency.  For
   multi-access links, communities of OSPFv3 routers could be migrated
   using different interface instance IDs.  However, at least one router
   would need to form adjacencies between both the OSPFv3 routers
   including and not including the authentication trailer.  This would
   result in sub-optimal routing, as well as, added complexity and is
   only recommended in cases where authentication is desired on the link
   and it isn't feasible to migrate all the routers on the link at the
   same time.

   An implementation MAY have a transition mode where it includes the
   Authentication Trailer in the packets but does not verify this
   information.  This is provided as a transition aid for networks in
   the process of migrating to the mechanism described in this draft.
































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6.  Security Considerations

   The document proposes extensions to OSPFv3 which would make it more
   secure than [RFC5340].  It does not provide confidentiality as a
   routing protocol contains information that does not need to be kept
   secret.  It does, however, provide means to authenticate the sender
   of the packets which is of interest to us.

   It should be noted that authentication method described in this
   document is not being used to authenticate the specific originator of
   a packet, but is rather being used to confirm that the packet has
   indeed been issued by a router which had access to the password.

   The mechanism described here is not perfect and does not need to be
   perfect.  Instead, this mechanism represents a significant increase
   in the work function of an adversary attacking the OSPFv3 protocol,
   while not causing undue implementation, deployment, or operational
   complexity.

































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7.  IANA Considerations

   IANA is requested to allocate AT-bit in the OSPFv3 "Options Registry"

   IANA is also requested to create new OSPFv3 "Authentication Trailer
   Types Registry"

            +-------------+----------------------+--------------------+
            | Value/Range | Designation          | Assignment Policy  |
            +-------------+----------------------+--------------------+
            | 0           | Reserved             | Reserved           |
            |             |                      |                    |
            | 1           | Cryptographic        | Already assigned   |
            |             | Authentication       |                    |
            |             |                      |                    |
            | 2-65535     | Unassigned           | Standards Action   |
            +-------------+----------------------+--------------------+

                        OSPFv3 Authentication Types
































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8.  References

8.1.  Normative References

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

   [RFC2328]  Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.

   [RFC5709]  Bhatia, M., Manral, V., Fanto, M., White, R., Barnes, M.,
              Li, T., and R. Atkinson, "OSPFv2 HMAC-SHA Cryptographic
              Authentication", RFC 5709, October 2009.

8.2.  Informative References

   [FIPS-180-3]
              US National Institute of Standards & Technology, "Secure
              Hash Standard (SHS)", FIPS PUB 180-3 , October 2008.

   [FIPS-198]
              US National Institute of Standards & Technology, "The
              Keyed-Hash Message Authentication Code (HMAC)", FIPS PUB
              198 , March 2002.

   [RFC2104]  Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
              Hashing for Message Authentication", RFC 2104,
              February 1997.

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

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

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

   [RFC4634]  Eastlake, D. and T. Hansen, "US Secure Hash Algorithms
              (SHA and HMAC-SHA)", RFC 4634, July 2006.

   [RFC5340]  Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
              for IPv6", RFC 5340, July 2008.

   [RFC5613]  Zinin, A., Roy, A., Nguyen, L., Friedman, B., and D.
              Yeung, "OSPF Link-Local Signaling", RFC 5613, August 2009.

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



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              RFC 5996, September 2010.

   [RFC6039]  Manral, V., Bhatia, M., Jaeggli, J., and R. White, "Issues
              with Existing Cryptographic Protection Methods for Routing
              Protocols", RFC 6039, October 2010.














































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Appendix A.  Acknowledgments

   First and foremost, thanks to the authors of RFC5709[RFC5709] from
   which this work was derived.

   Thanks to Sam Hartman for discussions on replay mitigation and the
   use of a 64-bit non-decrasing sequence number.

   Thanks to Michael Barnes for numerous comments and strong input on
   the coverage of LLS by the Authentication Trailer (AT).

   Thanks to Rajesh Shetty for numerous comments including the
   suggestion to include an Authentication Type field in the
   Authentication Trailer for extendibility.

   Thanks to Srinivasan K L, Shraddha H, Alan Davey, and Glen Kent for
   their review comments.

   Thanks to Alan Davey, Russ White, Stan Ratliff, and others for their
   support of the draft.

   The RFC text was produced using Marshall Rose's xml2rfc tool.





























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Authors' Addresses

   Manav Bhatia
   Alcatel-Lucent
   Bangalore,
   India

   Phone:
   Email: manav.bhatia@alcatel-lucent.com


   Vishwas
   IP Infusion
   USA

   Phone:
   Email: vishwas@ipinfusion.com


   Acee Lindem
   Ericsson
   102 Carric Bend Court
   Cary,   NC 27519
   USA

   Phone:
   Email: acee.lindem@ericsson.com
























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