[Search] [txt|pdf|bibtex] [Tracker] [Email] [Nits]

Versions: 00 01 02 03 04 05                                             
INTERNET DRAFT                                                  T. Polk
Intended Status: Informational                                     NIST
                                                             R. Housley
                                                         Vigil Security
Expires: 19 April 2010                                  19 October 2009


Routing Authentication Using A Database of Long-Lived Cryptographic Keys
                draft-polk-saag-rtg-auth-keytable-00.txt


Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as
   Internet-Drafts.

   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."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/1id-abstracts.html

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html

Abstract

   This document describes the application of a database of long-lived
   cryptographic keys to establish session-specific cryptographic keys
   to support authentication services in routing protocols.  Keys may be
   established between two peers for pair-wise communications, or
   between groups of peers for multicast traffic.












Polk & Housley           Expires 19 April 2010                  [Page 1]


INTERNET DRAFT                                           19 October 2009


Table of Contents

   1  Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 2
      1.1  Terminology . . . . . . . . . . . . . . . . . . . . . . . . 2
   2 Architecture and Design . . . . . . . . . . . . . . . . . . . . . 2
   3 Pair-wise Application . . . . . . . . . . . . . . . . . . . . . . 3
   4 Identifier Mapping  . . . . . . . . . . . . . . . . . . . . . . . 5
      4.1 Selected Range Reservation . . . . . . . . . . . . . . . . . 5
      4.2 Protocol Specific Mapping Tables . . . . . . . . . . . . . . 6
   5 Worked Example: TCP-AO  . . . . . . . . . . . . . . . . . . . . . 6
   6  Security Considerations  . . . . . . . . . . . . . . . . . . . . 7
   6  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . . 7
   7  References . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
      7.1  Normative References  . . . . . . . . . . . . . . . . . . . 7
      7.2  Informative References  . . . . . . . . . . . . . . . . . . 7
   Author's Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 7
   Full Copyright Statement  . . . . . . . . . . . . . . . . . . . . . 8

1  Introduction

   This document describes the application of a database of long-lived
   cryptographic keys, as defined in [KEYTAB], to establish session-
   specific cryptographic keys to provide authentication services in
   routing protocols.  Keys may be established between two peers for
   pair-wise communications, or between groups of peers for multicast
   traffic.


1.1  Terminology

   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 RFC 2119 [RFC2119].

2 Architecture and Design
















Polk & Housley           Expires 19 April 2010                  [Page 2]


INTERNET DRAFT                                           19 October 2009


   Figure 1 illustrates the establishment and use of cryptographic keys
   for authentication in routing protocols.  Long-lived cryptographic
   keys are inserted in a database manually.  In the future, we
   anticipate an automated key management protocol to insert these keys
   in the database. In this future environment, we do not anticipate an
   environment where the automated key management protocol will be used
   to create short-lived cryptographic session keys.  The structure of
   the database of long-lived cryptographic keys is described in
   [KEYTAB].

   The cryptographic keying material for individual sessions is derived
   from the keying material stored in the database of long-lived
   cryptographic keys.  A key derivation function (KDF) and its inputs
   are named in the database of long-lived cryptographic keys; session
   specific values based on the routing protocol are input the the KDF.
   Protocol specific key identifiers may be assigned to the
   cryptographic keying material for individual sessions if needed.

      +--------------+   +----------------+
      |              |   |                |
      |  Manual Key  |   | Automated Key  |
      | Installation |   | Mgmt. Protocol |
      |              |   |                |
      +------+-------+   +--+----------+--+
             |              |          |
             |              |          |
             V              V          |<== Not expected for security
      +------------------------+       |    of routing protocols, but
      |                        |       |    often used in other
      | Long-lived Crypto Keys |       |    protocol environments
      |                        |       |    like IPsec and TLS.
      +------------+-----------+       |
                   |                   |
                   |                   |
                   V                   V
        +---------------------------------+
        |                                 |
        | Short-lived Crypto Session Keys |
        |                                 |
        +---------------------------------+

          Figure 1.  Cryptographic key establishment and use.


3 Pair-wise Application
   Figure 2 illustrates how the long-lived cryptographic keys are
   accessed and employed when an entity wishes to establish a protected
   session with a peer.  As one step in the initiation process, the



Polk & Housley           Expires 19 April 2010                  [Page 3]


INTERNET DRAFT                                           19 October 2009


   intitator requests the set of long term keys associated with the peer
   for the particular protocol.  If the set contains more than one key,
   the initiator selects one long-term key based on the local policy.
   The long-term key is provided as an input, along with session-
   specific information (e.g., ports or initial counters), to a key
   derivation function.  The result is session-specific key material
   which is used to generate cryptographic authentication.

   Where the initiator is establishing a multicast session, the Peer in
   the key request identifies the set of systems that will receive this
   information.

                          +-------------------------+
                          |                         |
                          |        Long-Lived       |
                          |        Crypto Keys      |
                          |                         |
                          +-+---------------------+-+
                            ^                     |
                            |                     |
                            |                     V
                    +-------+-------+     +-------+-------+
                    |               |     |               |
                    |  Lookup Keys  |     |  Select Key   |
                    |    By Peer    |     |   By Policy   |
                    |  and Protocol |     |               |
                    |               |     +-------+-------+
                    +-------+-------+             |
                            ^                     |
                            |                     V
                            |             +-------+-------+
                            |             |               |
                            |             |  Session Key  |
                            |             |   Derivation  |
                            |             |               |
                            |             +-------+-------+
                            |                     |
                            |                     |
                    +-------+-------+             V
                    |               |     +-------+-------+
                    |   Initiate    |     |               |
                    |     Session   |     |Authentication |
                    |   with Peer   |     |   Mechanism   |
                    |               |     |               |
                    +---------------+     +---------------+


   Figure 3 illustrates how an entity that receives a session generates



Polk & Housley           Expires 19 April 2010                  [Page 4]


INTERNET DRAFT                                           19 October 2009


   the necessary long-lived cryptographic keys to verify data when a
   protected session is requested.  As step one in the initiation
   process, the receiver extracts the keyID for the long-term keyID from
   the received data.  The receiver then requests the specified long-
   term key from the table. The long-term key is provided as an input,
   along with session-specific information (e.g., ports or initial
   counters), to a key derivation function.  The result is session-
   specific key material which is used to verify the cryptographic
   authentication information.

                          +-------------------------+
                          |                         |
                          |        Long-Lived       |
                          |        Crypto Keys      |
                          |                         |
                          +-+---------------------+-+
                            ^                     |
                            |                     |
                            |                     V
                    +-------+-------+     +-------+-------+
                    |               |     |               |
                    |  Lookup Key   |     |  Session Key  |
                    |    By KeyID   |     |   Derivation  |
                    |               |     |               |
                    +-------+-------+     +-------+-------+
                            ^                     |
                            |                     |
                            |                     V
                    +-------+-------+     +-------+-------+
                    |               |     |               |
                    | Receive Data  |     |Authentication |
                    |    From Peer  |     |   Mechanism   |
                    |               |     |               |
                    +---------------+     +---------------+



4 Identifier Mapping

   [KEYTAB] specifies a 16-bit identifier, but protocols already exist
   with key identifiers of various sizes.  Where the identifiers are of
   different sizes, an extra mapping step may be required.  Note that
   mapping mechanisms are local - that is, different mapping mechanisms
   could be employed on different peers.

4.1 Selected Range Reservation

   Where a protocol sues an index of less than 16 bits, a selected range



Polk & Housley           Expires 19 April 2010                  [Page 5]


INTERNET DRAFT                                           19 October 2009


   of the local index space can be reserved for a particular protocol.
   For example, consider two protocols P1 and P2 that each use 8 bit key
   identifiers.   Sharing the space {0x0000 through 0x00ff} would limit
   the pair pair of protocols to 256 keys in total.  By reserving the
   ranges {0xff00 through 0xffff} and {0xfe00 through 0xfeff} for P1 and
   P2 respectively permits each protocol to use the full 256 key
   identifiers and establishes an unambiguous mapping for the protocol
   key identifiers and local table identifiers.

   When an initiator selects a key from the set in the table, the given
   key identifier needs to be masked or shifted to the on-the-wire
   range.  Before requesting a specific key, the receiver would use a
   shim layer would need to map the on-the-wire identifier into the
   reserved range.

4.2 Protocol Specific Mapping Tables

   Each protocol can also maintain a simple mapping table with two
   fields: the l6 bit index and the protocol specific value

   KEYTAB index (16 bits)   |  Protocol specific index (8 bits)

   In this case, the host system would maintain separate mapping tables
   for protocols P1 and P2.

5 Worked Example: TCP-AO

   This section describes the way a TCP-AO implementation could use the
   database. [tcpao] TCP-AO protocol is an example where the key
   identifier is limited to 8 bits, so an identifier mapping is needed.

   We will assume two peers Xp and Yp.  Xp employs the range reservation
   method for mapping and has reserved the range {0xff00 ... 0xffff}
   mapping to {0x00 ... 0xff}. Yp employs a protocol specific mapping
   table.

   <<Completed Example TBD>>














Polk & Housley           Expires 19 April 2010                  [Page 6]


INTERNET DRAFT                                           19 October 2009


6  Security Considerations

   <Security considerations text>


6  IANA Considerations

   This document requires no actions by IANA.

7  References

7.1  Normative References

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

   [KEYTAB]   R. Housley and Polk, T. "Database of Long-Lived
               Cryptographic Keys", draft-housley-saag-crypto-key-table-
               00.txt, September 2009.


7.2  Informative References

   [tcpao]   J. Touch, Mankin A., and Bonica R. "The TCP Authentication
               Option", draft-ietf-tcpm-tcp-auth-opt-05.txt, July 2009.


Author's Addresses


   Tim Polk
   National Institute of Standards and Technology
   100 Bureau Drive, Mail Stop 8930
   Gaithersburg, MD 20899-8930
   USA
   EMail: tim.polk@nist.gov

   Russell Housley
   Vigil Security, LLC
   918 Spring Knoll Drive
   Herndon, VA 20170
   USA
   EMail: housley@vigilsec.com








Polk & Housley           Expires 19 April 2010                  [Page 7]


INTERNET DRAFT                                           19 October 2009


Full Copyright Statement

   Copyright (c) 2009 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 in effect on the date of
   publication of this document (http://trustee.ietf.org/license-info).
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.


   All IETF Documents and the information contained therein are provided
   on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
   REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE
   IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL
   WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
   WARRANTY THAT THE USE OF THE INFORMATION THEREIN WILL NOT INFRINGE
   ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
   FOR A PARTICULAR PURPOSE.































Polk & Housley           Expires 19 April 2010                  [Page 8]