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Versions: (draft-ietf-manet-nhdp-sec) 00 01 02 03 04 05 RFC 7183

Mobile Ad hoc Networking (MANET)                              U. Herberg
Internet-Draft                           Fujitsu Laboratories of America
Updates: RFC6130 (if approved)                               C. Dearlove
Intended status: Standards Track                         BAE Systems ATC
Expires: September 24, 2013                                   T. Clausen
                                                LIX, Ecole Polytechnique
                                                          March 23, 2013


      Integrity Protection for Control Messages in NHDP and OLSRv2
                  draft-ietf-manet-nhdp-olsrv2-sec-01

Abstract

   This document specifies integrity and replay protection for required
   implementation in the MANET Neighborhood Discovery Protocol (NHDP)
   and the Optimized Link State Routing Protocol version 2 (OLSRv2).
   This document specifies how an included integrity check value (ICV)
   and a timestamp TLV, defined in RFC6622bis, are used by NHDP and
   OLSRv2 for countering a number of security threats.  The ICV TLV uses
   a SHA-256 based HMAC and one or more shared secret keys.  The
   timestamp TLV is based on POSIX time, and assumes that the clocks in
   all routers in the network can be synchronized with sufficient
   precision.  The mechanism in this specification can also be used for
   other MANET protocols using RFC5444.

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 September 24, 2013.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   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
   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
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Applicability Statement  . . . . . . . . . . . . . . . . . . .  4
   4.  Protocol Overview and Functioning  . . . . . . . . . . . . . .  6
   5.  Parameters . . . . . . . . . . . . . . . . . . . . . . . . . .  7
   6.  Message Generation and Processing  . . . . . . . . . . . . . .  8
     6.1.  Message Content  . . . . . . . . . . . . . . . . . . . . .  8
     6.2.  Message Generation . . . . . . . . . . . . . . . . . . . .  9
     6.3.  Message Processing . . . . . . . . . . . . . . . . . . . .  9
       6.3.1.  Invalidating a Message Based on Timestamp  . . . . . . 10
       6.3.2.  Invalidating a Message Based on Integrity Check  . . . 10
   7.  Provisioning of Routers  . . . . . . . . . . . . . . . . . . . 11
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11
     9.1.  Alleviated Attacks . . . . . . . . . . . . . . . . . . . . 11
       9.1.1.  Identity Spoofing  . . . . . . . . . . . . . . . . . . 11
       9.1.2.  Link Spoofing  . . . . . . . . . . . . . . . . . . . . 11
       9.1.3.  Replay Attack  . . . . . . . . . . . . . . . . . . . . 12
     9.2.  Limitations  . . . . . . . . . . . . . . . . . . . . . . . 12
   10. Normative References . . . . . . . . . . . . . . . . . . . . . 12
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13

















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1.  Introduction

   This specification defines a framework of security mechanisms that
   must be included in conforming implementations of the Neighborhood
   Discovery Protocol (NHDP) [RFC6130] and the Optimized Link State
   Routing Protocol version 2 (OLSRv2) [OLSRv2] for Mobile Ad hoc
   NETworks (MANETs).  A deployment of these protocols may choose to
   employ alternative(s) to these mechanisms, in particular it may
   choose to protect packets rather than messages, it may choose to use
   an alternative integrity check value (ICV) with preferred properties,
   or it may use an alternative timestamp.  A deployment may choose to
   use no such security mechanisms, but this is not recommended.

   The mechanisms specified are the use of an ICV for protection of the
   protocols' control messages, and the use of timestamps in those
   messages to prevent replay attacks.  Both use the TLV mechanism
   specified in [RFC5444] to add this information to the messages.
   These ICV and timestamp TLVs are defined in [RFC6622bis].  Different
   ICV TLVs are used for HELLO messages in NHDP and TC messages in
   OLSRv2, the former also protecting the source address of the IP
   datagram that contains the HELLO message, because the IP datagram
   source address is used by NHDP to determine the address of a neighbor
   interface, and is not necessarily otherwise contained in the HELLO
   message.

   The mechanism specified in this document exists between NHDP's and
   OLSRv2's message processing/generation and the [RFC5444] packet
   parsing/generation, as illustrated in Figure 1.























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                              |                        |
                   Incoming   |                       /|\ Outgoing
                    packet   \|/                       |   packet
                              |                        |
                          +--------------------------------+
                          |                                |
                          |         RFC5444 packet         |
                          |      parsing / generation      |
                          |                                |
                          +--------------------------------+
                              |                        |
                   Messages   |                       /|\ Messages with
                             \|/                       |  added TLVs
                              |                        |
   D                      +--------------------------------+
   R  /__________________ |                                |
   O  \      Messages     |       This specification       |
   P      (failed check)  |                                |
                          +--------------------------------+
                              |                        |
                 Messages     |                       /|\ Messages
              (passed check) \|/                       |
                              |                        |
                          +--------------------------------+
                          |                                |
                          |      NHDP/OLSRv2 message       |
                          |    processing / generation     |
                          |                                |
                          +--------------------------------+

            Figure 1: Relationship with RFC5444 and NHDP/OLSRv2


2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   [RFC2119].

   Additionally, this document uses the terminology of [RFC5444],
   [RFC6130], [OLSRv2], and [RFC6622bis].


3.  Applicability Statement

   [RFC6130] and [OLSRv2] enable extensions to recognize additional
   reasons for rejecting a message as "badly formed and therefore



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   invalid for processing", and mention security (integrity protection)
   as an explicit example.  This document specifies a framework that
   provides this functionality.

   Implementations of [RFC6130] and [OLSRv2] MUST include this
   framework, and deployments of [RFC6130] and [OLSRv2] SHOULD use this
   framework, except for when a different security mechanism is more
   appropriate.

   The applicability of this framework is determined by its
   characteristics, which are that it:

   o  Specifies a security framework that is required to be included in
      conforming implementations of [RFC6130] and [OLSRv2].

   o  Specifies an association of ICVs with messages, and for using
      missing or invalid ICVs as such an additional reason for rejecting
      a message as "badly formed and therefore invalid for processing".

   o  Specifies the implementation of an ICV TLV, defined in
      [RFC6622bis], using a SHA-256 based HMAC applied to the
      appropriate message contents (and for HELLO messages also
      including the IP datagram source address).  Deployments of
      [RFC6130] and [OLSRv2] using this framework should use the HMAC/
      SHA-256 ICV TLV, but may use different algorithms if more
      appropriate in a deployment.  An implementation may also use more
      than one ICV TLV in a message as long as they each use a different
      algorithm to calculate the ICV.

   o  Specifies the implementation of a TIMESTAMP TLV, defined in
      [RFC6622bis], to provide message replay protection.  Deployments
      of [RFC6130] and [OLSRv2] using this framework SHOULD use a POSIX
      time based timestamp, if the clocks in all routers in the network
      can be synchronized with sufficient precision.

   o  Assumes that a router that is able to generate correct integrity
      check values is considered trusted.

   This framework does not:

   o  Specify which key identifiers are to be used in a MANET in which
      the routers share more than one secret key.  (Such keys wil be
      differentiated using the <key-id> field defined in an ICV TLV in
      [RFC6622bis].)

   o  Specify how to distribute cryptographic material (shared secret
      key(s)).




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   o  Specify how to detect compromised routers with valid keys.

   o  Specify how to handle (revoke) compromised routers with valid
      keys.


4.  Protocol Overview and Functioning

   The framework specified in this document provides the following
   functionalities for use with messages owned by [RFC6130] and
   [OLSRv2]:

   o  Generation of ICV TLVs (as defined in [RFC6622bis]) for inclusion
      in an outgoing message.  An implementation of [RFC6130] and
      [OLSRv2] may use more than one ICV TLV in a message, even with the
      same type extension, but these ICV TLVs MUST each use a different
      algorithm to calculate the ICV, e.g., with different hash and/or
      cryptographic functions when using type extension 1 or 2.  An
      implementation of [RFC6130] and [OLSRv2] must at least be able to
      generate an ICV TLV using HMAC/SHA-256 and one or more secret keys
      shared by all routers.

   o  Generation of TIMESTAMP TLVs (as defined in [RFC6622bis]) for
      inclusion in an outgoing message.  An implementation of [RFC6130]
      and [OLSRv2], that is able to synchronize the clocks in all
      routers in the network with sufficient precision, must at least be
      able to generate a TIMESTAMP TLV using POSIX time.

   o  Verification of ICV TLVs contained in a message, in order to
      determine if this message MUST be rejected as "badly formed and
      therefore invalid for processing" [RFC6130] [OLSRv2].  An
      implementation of [RFC6130] and [OLSRv2] must at least be able to
      verify an ICV TLV using HMAC/SHA-256 and one or more secret keys
      shared by all routers.

   o  Verification of a TIMESTAMP TLV (as defined in [RFC6622bis])
      contained in a message, in order to determine if this message MUST
      be rejected as "badly formed and therefore invalid for processing"
      [RFC6130] [OLSRv2].  An implementation of [RFC6130] and [OLSRv2]
      that is able to synchronize the clocks in all routers in the
      network with sufficient precision, must at least be able to verify
      a TIMESTAMP TLV using POSIX time.

   ICV Packet TLVs (as defined in [RFC6622bis]) may be used by a
   deployment of the multiplexing process defined in [RFC5444], either
   as well as, or instead of, the protection of the NHDP and OLSRv2
   messages.  (Note that in the case of NHDP, the packet protection is
   equally good, and also protects the packet header.  In the case of



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   OLSRv2, the packet protection has different properties than the
   message protection, especially for some forms of ICV.  When packets
   contain more than one message, the packet protection has lower
   overheads in space and computation time.)

   When a router generates a message on a MANET interface, this
   framework:

   o  Specifies how to calculate an integrity check value for the
      message.

   o  Specifies how to include that integrity check value using an ICV
      Message TLV.

   [RFC6130] and [OLSRv2] allow for rejecting incoming messages prior to
   processing by NHDP or OLSRv2.  This framework specifies that a
   message must be rejected if the ICV Message TLV is absent, or its
   value cannot be verified.


5.  Parameters

   This following router parameters is specified for use by the two
   protocols; the first is required only by NHDP, but may be visible to
   OLSRv2, the second is required only by OLSRv2:

   o  MAX_HELLO_TIMESTAMP_DIFF - The maximum age that a HELLO message to
      be validated may have.  If the current POSIX time of the router
      validating the HELLO message, minus the timestamp indicated in the
      TIMESTAMP TLV of the HELLO message, is greater than
      MAX_HELLO_TIMESTAMP_DIFF, the HELLO message MUST be silently
      discarded.

   o  MAX_TC_TIMESTAMP_DIFF - The maximum age that a TC message to be
      validated may have.  If the current POSIX time of the router
      validating the TC message, minus the timestamp indicated in the
      TIMESTAMP TLV of the TC message, is greater than
      MAX_TC_TIMESTAMP_DIFF, the TC message MUST be silently discarded.

   The following constraints apply to these parameters:

   o  MAX_HELLO_TIMESTAMP_DIFF > 0

   o  MAX_HELLO_TIMESTAMP_DIFF < REFRESH_INTERVAL

   o  MAX_TC_TIMESTAMP_DIFF > 0





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   o  MAX_TC_TIMESTAMP_DIFF < T_HOLD_TIME

   The second and fourth of those constraints assume ideal time
   synchronization of the clocks in all routers in the network.  These
   bounds MAY be relaxed to allow for expected timing differences
   between routers (between neighboring routers for
   MAX_HELLO_TIMESTAMP_DIFF).  However it should also be noted that, in
   the ideal case, the parameters SHOULD be significantly less than
   those bounds.


6.  Message Generation and Processing

   This section specifies how messages are generated and processed by
   [RFC6130] and [OLSRv2] when using this framework.

6.1.  Message Content

   Messages MUST have the content specified in [RFC6130] and [OLSRv2]
   respectively.  In addition, in order to conform to this framework,
   each message MUST contain:

   o  At least one ICV Message TLV (as specified in [RFC6622bis]),
      generated according to Section 6.2.  Implementations of [RFC6130]
      and [OLSRv2] MUST support the following version of the ICV TLV,
      but other versions MAY be used instead, or in addition, in a
      deployment, if more appropriate:

      *  For TC messages:

         +  type-extension := 1

      *  For HELLO messages:

         +  type-extension := 2

      *  hash-function := 3 (SHA-256)

      *  cryptographic-function := 3 (HMAC)

      A message MAY contain several ICV Message TLVs.

   o  At least one TIMESTAMP Message TLV (as specified in
      [RFC6622bis])"/>), generated according to Section 6.2.
      Implementations of [RFC6130] and [OLSRv2] using this framework
      MUST support the following version of the TIMESTAMP TLV, but other
      versions MAY be used instead, or in addition, in a deployment, if
      more appropriate:



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      *  type-extension := 1

6.2.  Message Generation

   After message generation (Section 11.1 of [RFC6130] and Section 16.1.
   of [OLSRv2]) and before message transmission (Section 11.2 of
   [RFC6130] and Section 16.2 of [OLSRv2]), the additional TLVs
   specified in Section 6.1 MUST (unless already present) be added to an
   outgoing message when using this framework.

   The following processing steps MUST be performed for a cryptographic
   algorithm that is used for generating an ICV for a message:

   1.  All ICV TLVs (if any) are temporarily removed from the message.
       Any temporarily removed ICV TLVs MUST be stored, in order to be
       reinserted into the message in step 5.  The message size is
       updated accordingly.

   2.  <msg-hop-count> and <msg-hop-limit>, if present, are temporarily
       set to 0.

   3.  A TLV of type TIMESTAMP, as specified in Section 6.1, is added to
       the Message TLV block.  The message size is updated accordingly.

   4.  A TLV of type ICV, as specified in Section 6.1, is added to the
       Message TLV block.  The message size is updated accordingly.

   5.  All ICV TLVs that were temporary removed in step 1, are restored.
       The message size is updated accordingly.

   6.  <msg-hop-count> and <msg-hop-limit>, if present, are restored to
       their previous values.

6.3.  Message Processing

   Both [RFC6130] and [OLSRv2] specify that:

      "On receiving a ... message, a router MUST first check if the
      message is invalid for processing by this router"

   [RFC6130] and [OLSRv2] proceed to give a number of conditions that,
   each, will lead to a rejection of the message as "badly formed and
   therefore invalid for processing".  When using a single timestamp
   version, and a single ICV algorithm, the following conditions to that
   list, each of which, if true, MUST cause NHDP or OLSRv2 (as
   appropriate) to consider the message as invalid for processing when
   using this framework:




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   1.  The Message TLV Block of the message does not contain exactly one
       TIMESTAMP TLV of the selected version.  This version
       specification includes the type extension.  (The Message TLV
       Block may also contain TIMESTAMP TLVs of other versions.)

   2.  The Message TLV block does not contain exactly one ICV TLV using
       the selected algorithm and key identifier.  This algorithm
       specification includes the type extension, and for type
       extensions 1 and 2, the hash function and cryptographic function.
       (The Message TLV Block may also contain ICV TLVs using other
       algorithms and key identifiers.)

   3.  Validation of the identified (in step 1) TIMESTAMP TLV in the
       Message TLV block of the message fails, as according to
       Section 6.3.1.

   4.  Validation of the identified (in step 2) ICV TLVs in the Message
       TLV block of the message fails, as according to Section 6.3.2.

   An implementation MAY check the existence of, and verify, either
   alternative TIMESTAMP and/or ICV TLVs, or more than one TIMESTAMP
   and/or ICV TLVs.

6.3.1.  Invalidating a Message Based on Timestamp

   For a TIMESTAMP Message TLV with type extension 1 (POSIX time)
   identified as described in Section 6.2:

   1.  If the current POSIX time minus the value of that TIMESTAMP TLV
       is greater than MAX_HELLO_TIMESTAMP_DIFF (for a HELLO message) or
       MAX_TC_TIMESTAMP_DIFF (for a TC message) then the message
       validation fails.

   2.  Otherwise, the message validation succeeds.

   If a deployment chooses to use a different type extension from 1,
   appropriate measures MUST be taken to verify freshness of the
   message.

6.3.2.  Invalidating a Message Based on Integrity Check

   For an ICV Message TLV identified as described in Section 6.2:

   1.  All ICV Message TLVs (including the identified ICV Message TLV)
       are temporarily removed from the message, and the message size is
       updated accordingly.





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   2.  The message's <msg-hop-count> and <msg-hop-limit> fields are
       temporarily set to 0.

   3.  Calculate the integrity check value for the parameters specified
       in the identified ICV Message TLV, as specified in [RFC6622bis].

   4.  If this integrity check value differs from the value of <ICV-
       data> in the ICV Message TLV, then the message validation fails.

   5.  Otherwise, the message validation succeeds.  The message's <msg-
       hop-count> and <msg-hop-limit> fields are restored to their
       previous value, and the ICV Message TLVs are returned to the
       message, whose size is updated accordingly.


7.  Provisioning of Routers

   Before a router is able to generate ICVs or validate messages, it
   MUST acquire the shared secret key(s) to be used by all routers that
   are to participate in the network.  This specification does not
   define how a router acquires secret keys.


8.  IANA Considerations

   This document has no actions for IANA.


9.  Security Considerations

   This document specifies a security framework for use with NHDP and
   OLSRv2 that allows for alleviating several security threats.

9.1.  Alleviated Attacks

   This section briefly summarizes security threats that are alleviated
   by the framework presented in this document.

9.1.1.  Identity Spoofing

   As only routers possessing the selected shared secret key are able to
   add a valid ICV TLV to a message, identity spoofing is countered.

9.1.2.  Link Spoofing

   Link spoofing is countered by the framework specified in this
   document, using the same argument as in Section 9.1.1.




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9.1.3.  Replay Attack

   Replay attacks are partly counteracted by the framework specified in
   this document, but this depends on synchronized clocks of all routers
   in the MANET.  An attacker that records messages to replay them later
   can only do so in the selected time interval after the timestamp that
   is contained in message.  As an attacker cannot modify the content of
   this timestamp (as it is protected by the identity check value), an
   attacker cannot replay messages after this time.  Within this time
   interval it is still possible to perform replay attacks, however the
   limits on the time interval are specified so that this will have a
   limited effect on the operation of the protocol.

9.2.  Limitations

   If no synchronized clocks are available in the MANET, replay attacks
   cannot be countered by the framework provided by this document.  An
   alternative version of the TIMESTAMP TLV defined in [RFC6622bis],
   with a monotonic sequence number, may have some partial value in this
   case, but will necessitate adding state to record observed message
   sequence number information.

   The framework provided by this document does not avoid or detect
   security attacks by routers possessing the shared secret key that is
   used to generate integrity check values for messages.

   This framework relies on an out-of-band protocol or mechanism for
   distributing the shared secret key(s) (and if an alternative
   integrity check value is used, any additional cryptographic
   parameters).

   This framework does not provide a key revocation mechanism.


10.  Normative References

   [OLSRv2]   Clausen, T., Dearlove, C., Jacquet, P., and U. Herberg,
              "The Optimized Link State Routing Protocol version 2",
              work in progress draft-ietf-manet-olsrv2-19, March 2013.

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

   [RFC5444]  Clausen, T., Dearlove, C., Dean, J., and C. Adjih,
              "Generalized MANET Packet/Message Format", RFC 5444,
              February 2009.

   [RFC6130]  Clausen, T., Dean, J., and C. Dearlove, "Mobile Ad Hoc



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              Network (MANET) Neighborhood Discovery Protocol (NHDP)",
              RFC 6130, April 2011.

   [RFC6622bis]
              Herberg, U., Clausen, T., and C. Dearlove, "Integrity
              Check Value and Timestamp TLV Definitions for Mobile Ad
              Hoc Networks (MANETs)", work in
              progress draft-ietf-manet-rfc6622-bis-01, March 2013.


Authors' Addresses

   Ulrich Herberg
   Fujitsu Laboratories of America
   1240 E. Arques Ave.
   Sunnyvale, CA, 94085,
   USA

   Email: ulrich@herberg.name
   URI:   http://www.herberg.name/


   Christopher Dearlove
   BAE Systems Advanced Technology Centre
   West Hanningfield Road
   Great Baddow, Chelmsford
   United Kingdom

   Phone: +44 1245 242194
   Email: chris.dearlove@baesystems.com
   URI:   http://www.baesystems.com/


   Thomas Heide Clausen
   LIX, Ecole Polytechnique
   91128 Palaiseau Cedex,
   France

   Phone: +33 6 6058 9349
   Email: T.Clausen@computer.org
   URI:   http://www.thomasclausen.org/










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