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Versions: (draft-ietf-mobileip-aaa-key) 00 01 02 03 04 05 06 RFC 3957

Mobile IP Working Group                               Charles E. Perkins
INTERNET DRAFT                                     Nokia Research Center
29 March 2004                                             Pat R. Calhoun
                                                               Airespace
                 AAA Registration Keys for Mobile IPv4
                     draft-ietf-mip4-aaa-key-05.txt



Status of This Memo


   This document is a submission by the mobile-ip Working Group of the
   Internet Engineering Task Force (IETF).  Comments should be submitted
   to the mobile-ip@sunroof.eng.sun.com mailing list.


   Distribution of this memo is unlimited.


   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.  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/ietf/1id-abstracts.txt
   The list of Internet-Draft Shadow Directories can be accessed at:
        http://www.ietf.org/shadow.html.



Abstract


   AAA servers, such as RADIUS and DIAMETER, are in use within
   the Internet today to provide authentication and authorization
   services for dial-up computers.  Mobile IP for IPv4 requires strong
   authentication between the mobile node and its home agent.  When the
   mobile node shares an AAA Security Association with its home AAA
   server, however, it is possible to use that AAA Security Association
   to create derived Mobility Security Associations between the mobile
   node and its home agent, and again between the mobile node and the
   foreign agent currently offering connectivity to the mobile node.
   This document specifies extensions to Mobile IP registration messages
   that can be used to create Mobility Security Associations between the








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   mobile node and its home agent, and/or between the mobile node and a
   foreign agent.


                                Contents



Status of This Memo                                                    i


Abstract                                                               i


 1. Introduction                                                       2


 2. Terminology                                                        3


 3. Overview of Operations with Key Generation Nonce Extensions        5


 4. Mobility Security Associations                                     7


 5. Key Generation Nonce Creation and Key Derivation                   8


 6. Key Generation Extensions                                          9
     6.1. Generalized MN-FA Key Generation Nonce Request Extension     9
     6.2. Generalized MN-FA Key Generation Nonce Reply Extension  .   10
     6.3. Generalized MN-HA Key Generation Nonce Request Extension    13
     6.4. Generalized MN-HA Key Generation Nonce Reply Extension  .   14


 7. Error Values                                                      16


 8. IANA Considerations                                               16


 9. Security Considerations                                           17


10. Acknowledgements                                                  17


References                                                            19


 A. Changes Since Previous Revision                                   20


 B. Older Changes                                                     20


 C. AAA Infrastructure                                                22


 D. Message Flow for Requesting and Receiving Registration Keys       25


Intellectual Property                                                 29


Full Copyright Statement                                              29


Addresses                                                             29




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1. Introduction


   AAA servers, such as RADIUS [11] and DIAMETER [12], are in use within
   the Internet today to provide authentication and authorization
   services for dial-up computers.  Such services are likely to
   be valuable for mobile nodes using Mobile IP for IPv4 [1], when
   the nodes are attempting to connect to foreign domains with AAA
   servers.  In this document Mobile IP for IPv4 is called "Mobile
   IPv4" or just "Mobile IP" for short, since no confusion with other
   versions is expected.  Requirements for interactions between AAA and
   Mobile IP are outlined in RFC 2977 [13]; that document describes
   an infrastructure which enables AAA servers to authenticate and
   authorize network access requests from mobile nodes.  See also
   appendix C.  The Mobile IP Registration Request is considered to
   be a request for network access.  It is then possible to augment
   the functionality of the Mobile IP mobility agents so that they can
   translate between Mobile IP registration messages and the messages
   used within the AAA infrastructure, as described in RFC 2977.
   Mobility agents and AAA servers that conform to the requirements of
   RFC 2977 can be considered as appropriate network entities to support
   the message types specified in this document.  Please consult RFC
   2977 [13] for further details.


   This specification makes use of a single AAA Security Association
   to create derivative Mobility Security Associations.  A Mobility
   Security Association in this specification is a simplex connection
   that serves to authenticate MIPv4 control traffic between a MN and HA
   and/or a MN and FA. A Mobility Security Association is identified by
   the two end points, such as a MN IP address and a HA IP address, and
   a SPI. Two nodes may have one or more Mobility Security Associations
   established between each other; however, typically there is no reason
   to have more than one Mobility Security Association between two
   nodes.


   This document specifies extensions to Mobile IP registration messages
   that can be used to create Mobiity Security Associations between the
   MN and FA and/or MN and HA based on the AAA Security Association
   between the MN and HAAA. These additional Mobility Security
   Associations may then be used in Mobile IP extensions to calculate
   the Authentication Data need by authentication extensions used in
   Mobile IP control messages.  It is assumed that the AAA Security
   Association between the MN and its HAAA has been appropriately
   configured so that the AAA server has the authorization to provide
   key material to be used as the basis for the necessary Mobility
   Security Assocation between the MN and its prospective mobility
   agents.


   The extensions in this document are intended to provide the
   appropriate level of security for Mobile IP entities (mobile node,




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   foreign agent, and home agent) to calculate the Authentication Data
   needed by authentication extensions used with Mobile IP registration
   messages.  It is assumed that the security association between the
   mobile node and its AAA server has been appropriately configured so
   that the AAA server has authorization to provide key material to be
   used as the basis for the necessary Mobility Security Association(s)
   between the mobile node and its prospective mobility agents.


   AAA servers typically use the Network Access Identifier (NAI) [2] to
   uniquely identify the mobile node; the mobile node's home address is
   not always necessary to provide that function.  Thus, it is possible
   for a mobile node to authenticate itself, and be authorized for
   connection to the foreign domain, without having any home address.
   However, for Mobile IP to work, the mobile node is required to
   have a home address and a Mobility Security Association [1] with
   its home agent.  When the Mobile IP Registration Reply packet is
   authenticated by the MN-AAA Authentication Extension [3], the mobile
   node can verify that the key material contained in the extensions
   were produced by the AAA server, and thus may be reliably used to
   create Mobility Security Associations with the home agent and/or the
   foreign agent.


   It is also assumed that the AAA entities involved (i.e., the AAAH,
   AAAL, and the AAA interface features of the foreign agents and home
   agents) all have means outside of the scope of this document for
   exchanging keys.  The extensions within this document are intended to
   work with any AAA protocol suite that allows for such key exchange,
   as long as it satisfies the requirements specified in RFC 2977 [13].
   One such AAA protocol is defined within the Diameter framework [14].



2. 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 [4].


      AAA           Authentication, Authorization, and Accounting
                    (see [10]).


      AAA entity    A network node processing AAA messages according to
                    the requirements for AAA protocols (see [10]).


      AAA Security Association
                    A security association between a AAA entity
                    and another node needing the services of that
                    AAA entity.  In this document all AAA Security
                    Associations are between a mobile node and its home
                    AAA server (AAAH). A mobile node's AAA Security




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                    Association with its home AAA server (AAAH) may be
                    based either on the mobile node's IP address or on
                    its NAI [2].  The key is referred to as "AAA-key" in
                    this specification.


      Key           a number, kept secret.  Only nodes in possession
                    of the key have any hope of using the security
                    transform to obtain correct results.


      Key Generation Nonce
                    Nonce data used for the purpose of creating a key.


      Mobility Security Association
                    A Mobility Security Association is a simplex
                    connection that applies security services to RFC
                    3344 MIPv4 control traffic between a MN and HA (or
                    MN and FA) using RFC 3344 Authentication Extensions.
                    A Mobility Security Association is uniquely
                    identified by the peer source and destination IP
                    addresses and an SPI. Two nodes may have one or more
                    Mobility Security Associations; however, typically
                    there is no reason to have more than one Mobility
                    Security Association between two nodes, except as a
                    transient condition during re-keying events.


      Registration Key
                    A key used in the MN-FA or MN-HA Mobility Security
                    Association A registration key is typically
                    only used once or a very few times, and only
                    for the purposes of verifying a small volume of
                    Authentication data.


      Security Algorithm
                    A set of rules for using input data and a secret key
                    for producing data for use in security protocols.


      SPI
                    Security Parameters Index.  The SPI is an arbitrary
                    32-bit value that assists in the identification of
                    an AAA, IP, or Mobility Security Association.


   Other terminology is used as defined in the base Mobile IP
   specification [1].  Furthermore, in order to simplify the discussion,
   we have used the word "Extension" instead of "Subtype of the
   Generalized Extension" in many cases.  So, for instance, instead of
   using the phrase "The MN-FA Key Generation Nonce From AAA Subtype
   of the Generalized MN-FA Key Generation Nonce Reply Extension", we
   would instead use the phrase "The MN-FA Key Generation Nonce From AAA
   Extension".




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3. Overview of Operations with Key Generation Nonce Extensions


   When a mobile node depends on an AAA infrastructure to obtain
   authorization for network connectivity and Mobile IP registration,
   it may lack any pre-existing Mobility Security Associations with
   either its home agent, or the foreign agent controlling the access to
   the foreign network.  The extensions defined in this document allow
   a AAA entity to supply key material to mobile nodes to be used as
   the basis of its Mobility Security Association with mobile agents.
   The AAA entity that will act on these extensions is part of the AAA
   infrastructure, and is typically identified within the foreign domain
   by methods outside the scope of this specification (see appendix C).


   The key material may be requested by the mobile node in new
   extensions (defined below) to Mobile IP Registration Request
   messages, and supplied to the mobile node in extensions to the Mobile
   IP Registration Reply messages.  Alternatively, the AAA server MAY
   provide unsolicited key material via mobility agents to mobile nodes;
   the mobile node MUST then calculate new keys and update or create
   its relevant Mobility Security Association.  The method by which key
   material is supplied to the mobility agents themselves is out of
   scope for this document, and would depend on the particular details
   of the security architecture for the AAA servers in the foreign and
   home domains (see RFC 2977 and appendix C).  For the purposes of
   this document, we assume that there is a suitable AAA infrastructure
   available to the home and foreign agents, and that the mobile node
   does have an AAA Security Association with at least one AAA server in
   its home domain.


   When a mobile node travels away from home, it may not have a Mobility
   Security Association with its home agent, perhaps because it does
   not yet have a home address [5].  The protocol and messages in
   this document are intended to facilitate the following operations
   which may occur between the mobile node, foreign agent, home agent,
   and AAA servers in the visited (local) domain (Authentication,
   Authorization and Accounting Local or AAAL) and in the home domain
   (Authentication, Authorization, and Accounting Home or AAAH). In the
   following sequence of messages, the only message flows specified in
   this document are the Registration Request between the mobile node
   and the foreign agent, and Registration Reply between the foreign
   agent and the mobile node.  The other messages described here result
   from the presumed action of the AAA entities as described in RFC
   2977.  See also appendix D.


    1. If the mobile node does not have a Mobility Security Association
       with the foreign agent, it SHOULD include an MN-FA Key Generation
       Nonce Request extension (see Section 6.1) as part of its
       Registration Request that it sends to the Foreign Agent.





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    2. If the mobile node does not have a Mobility Security Association
       with the home agent, it MUST add an MN-HA Key Generation Nonce
       Request extension (see Section 6.3) as part of its Registration
       Request that it sends to the Foreign Agent.


    3. If one or more AAA Key Generation Nonce Request extensions
       were added, the mobile node MUST add the MN-AAA Authentication
       extension to its Registration Request.


    4. By action of the foreign agent, which is presumed to be also a
       AAA entity, the mobile node's key requests and authentication
       data are transferred to the local AAA server (AAAL), typically
       after reformatting to fit into the appropriate AAA messages,
       which are out of scope for this document.


    5. After the information within the MN-AAA Authentication extension
       is verified by the AAA server in the home domain (AAAH), it then
       also generates the key material that has been requested by the
       mobile node, for the necessary Mobility Security Associations.


    6. The respective keys for the Mobility Security Associations are
       distributed to the Home Agent and Foreign Agent via the AAA
       protocol.


    7. The mobile node receives the Registration Reply message from the
       Foreign Agent.


    8. If a MN-HA Key Generation Nonce From AAA extension is present
       in the Registration Reply message, then the mobile node MUST
       create or update its Mobility Security Association with the Home
       Agent indicated in the Registration Reply, using the key computed
       from the key material in the MN-HA Key Generation Nonce From
       AAA extension.  In this case, if no MN-HA Key Generation Nonce
       Reply extension is present, the mobile node MUST discard the
       Registration Reply.


    9. Using its (perhaps newly created) Mobility Security Association
       with the home agent, the mobile node authenticates the
       Registration Reply message by checking the Authentication Data in
       the Mobile-Home Authentication extension.  If the check fails,
       the MN MUST discard the Registration Reply and the new Mobility
       Security Association, reverting to the old Mobility Security
       Association with the home agent, if any.


   10. If the Registration Reply passes authentication and contains a
       MN-FA Key Generation Nonce From AAA extension (see section 6.2),
       the mobile node generates the registration key using the
       Key Generation Nonce provided, according to its AAA Security
       Association with the AAA. The resulting registration key is used




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       to establish the mobile node's Mobility Security Association with
       its foreign agent, and is used to compute the authentication data
       used in the Mobile-Foreign authentication extension.


       If verification of the Mobile-Foreign authentication extension
       fails, and if the MN-FA Key Generation Nonce Reply extension was
       not protected by another, valid authentication extension, the MN
       MUST discard the new Mobility Security Association, reverting to
       the old Mobility Security Association with the foreign agent, if
       any.


   Any registration reply containing the MN-HA Key Generation Nonce
   From AAA extension MUST also contain a subsequent Mobile Home
   Authentication extension, created using the generated MN-HA key.
   Similarly, a reply containing the MN-FA Key Generation Nonce
   From AAA extension MUST also contain a subsequent Mobile Foreign
   Authentication extension, created using the registration key.



4. Mobility Security Associations


   Mobility Security Associations between Mobile IP entities (mobile
   nodes, home agents, foreign agents) contain both the necessary
   cryptographic key information and a way to identify the cryptographic
   transform that uses the key to produce the authentication information
   that is present in the Mobile-Home Authentication extension or
   the Mobile-Foreign Authentication extension.  In order for the
   mobile node to make use of key material created by the AAA server,
   the mobile node also has to be able to identify and select the
   appropriate cryptographic transform that uses the key to produce the
   authentication.


   The transform identifiers are the same as those used in IPsec.  They
   are tabulated in the list of Authentication Algorithms allowable
   as values for the "Attribute Type" (5) (i.e., "Authentication
   Algorithm"), one of the classifications in the tabulated
   Attribute Types for "IPSEC Security Association Attributes".  See
   http://www.iana.org/assignments/isakmp-registry for the full listing
   of all Attribute Types and other Attributes for IPSEC Security
   Associations.


   Mobility Security Associations shared between mobile nodes and home
   agents also require a replay protection method.  The following table
   contains the supported replay detection methods.









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      Replay Method     Name           Reference
      --------------    ------------   --------------
      0,1               Reserved
      2                 Timestamps     RFC 3344 [1]
      3                 Nonces         RFC 3344 [1]
      4-65535           Unallocated





5. Key Generation Nonce Creation and Key Derivation


   This section contains the procedures followed in the creation of
   the Key Generation Nonce by AAA servers, and the key derivation
   procedures used by mobile nodes.  Note that the AAA servers will also
   deliver the keys to the mobility agents (home agent, foreign agent)
   via the AAA protocol.  AAA servers that follow these procedures will
   produce results that can be understood by mobile nodes.  The mobility
   agents will faithfully transcribe the results into the appropriate
   Mobile IP extensions.


   The following example uses HMAC-SHA1 [6].  All mobile nodes and
   mobility agents implementing Mobile IP [1] and implementing the
   extensions specified in this document MUST implement HMAC-SHA1 [1].
   Other message authentication codes or keyed hash functions MAY also
   be used.


   The following steps are performed on the AAAH server:


    1. The AAA server identifies the mobile node.  If the NAI field is
       present in the Registration Request, then the NAI is used as the
       mobile node identifier.  Otherwise, the Home Address field of the
       Registration Request is used.


    2. The AAA server generates a random [7] value of at least 128 bits
       to be used as the Key Generation Nonce.


    3. The AAA server inserts the random value into the Key Generation
       Nonce Reply extension in the "Key Generation Nonce" field.


   The following steps are performed by the mobile node (here ||
   represents concatenation):


    1. The mobile node calculates


          key = HMAC-SHA1 (AAA-key, {Key Generation Nonce || mobile
          node identifier})





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       Here the Key Generation Nonce is from the extension in the
       Registration Reply, and the mobile node identifier is the MN's
       NAI, if present in the Registration Request, or the Home Address
       from the Registration Request otherwise.


    2. The mobile node creates the Mobility Security Association(s),
       using the resulting key and the other relevant information in the
       Key Generation Nonce Extension.


   The secret key used within the HMAC-SHA1 computation is indicated by
   the AAA Security Association indexed by the AAA SPI, which has been
   previously configured as the basis for the AAA Security Association
   between the mobile node and the AAA server creating the key material.



6. Key Generation Extensions


   This section defines new Extensions to Mobile IP Registration
   Requests and Replies [1].



6.1. Generalized MN-FA Key Generation Nonce Request Extension


   Figure 1 illustrates the Generalized MN-FA Key Generation Nonce
   Request Extension (MN-FA KeyGen Request for short).



       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Type      |    Subtype    |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Mobile Node SPI                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           MN-FA Key Generation Nonce Request Subtype Data ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



        Figure 1: The Generalized Mobile IP MN-FA Key Generation
                        Nonce Request Extension



      Type             TBD1 (not skippable) (see [1] and section 8)


      Subtype          A number assigned to identify the way in
                       which the MN-FA Key Generation Nonce Request
                       Subtype Data is to be used when generating the
                       registration key





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      Length           The 16-bit Length field indicates the length of
                       the extension.  It is equal to the number of
                       bytes in the MN-FA Key Generation Nonce Request
                       Subtype Data plus 4 (for the Mobile Node SPI
                       field).


      Mobile Node SPI  The Security Parameters Index that the mobile
                       node will assign for the Mobility Security
                       Association created for use with the registration
                       key.


      MN-FA Key Generation Nonce Request Subtype Data
                       Data needed to carry out the creation of the
                       registration key on behalf of the mobile node.


   The MN-FA KeyGen Request defines a set of extensions, identified
   by subtype, which may be used by a mobile node in a Mobile IP
   Registration Request message to request that some other entity create
   a Registration Key for use by the mobile node with the mobile node's
   new foreign agent.


   This document defines the subtype 1 for the MN-FA Key Generation
   Nonce >From AAA Request (MN-FA AAA KeyGen Request for short).  The
   MN-FA AAA KeyGen Request has a zero-length Subtype Data field
   and MUST appear in the Registration Request before the MN-AAA
   Authentication extension.  The subtype data field is zero in length.



6.2. Generalized MN-FA Key Generation Nonce Reply Extension


   The Generalized MN-FA Key Generation Nonce Reply extension (MN-FA
   KeyGen Reply for short) supplies keying material requested by the
   MN-FA KeyGen Request extension.  Figure 2 illustrates the format of
   the Generalized MN-FA Key Generation Nonce Reply Extension.



       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Type      |    Subtype    |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             MN-FA Key Generation Nonce Reply Subtype Data ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



             Figure 2: The Generalized Mobile IP MN-FA Key
                    Generation Nonce Reply Extension






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      Type       TBD2 (not skippable) (see [1] and section 8)


      Subtype    A number assigned to identify the way in which the
                 MN-FA Key Generation Nonce Reply Subtype Data is to be
                 used to obtain the registration key.


      Length     The 16-bit Length field is equal to the number of bytes
                 in the MN-FA Key Generation Nonce Reply Subtype Data.


      MN-FA Key Generation Nonce Reply Subtype Data
                 An encoded copy of the keying material, along with any
                 other information needed by the recipient to create the
                 designated Mobility Security Association.


   For each subtype, the format of the MN-FA Key Generation Nonce Reply
   Subtype Data has to be separately defined according to the particular
   method required to set up the Mobility Security Association.


   For the subtype defined in this document, the MN-FA Key Generation
   Nonce supplied in the data for a subtype of this extension may
   come as a result of a request which was sent using a subtype of
   the Generalized MN-FA Key Generation Nonce Request Extension.  In
   such cases, the SPI to be used when employing the Mobility Security
   Association defined by the registration key is the same as given in
   the original request.


   Once the mobile node creates the Mobility Security Association with
   the foreign agent, by using the transform indexed by the AAA SPI, it
   stores that Mobility Security Association indexed by the FA SPI in
   its list of Mobile Security Associations.


   If the foreign agent receives a Registration Reply that has no MN-FA
   Key Generation Nonce Reply extension, and if it has no existing
   Mobility Security Association with the mobile node, the foreign agent
   MAY change the Code value of the Registration Reply to MISSING_MN_FA
   (see section 7), effectively causing the registration to fail.


   This document defines subtype 1 of the MN-FA KeyGen Reply for the
   MN-FA Key Generation Nonce From AAA extension (MN-FA AAA KeyGen Reply
   for short), shown in figure 3.













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       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            Lifetime                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            AAA SPI                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             FA SPI                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Algorithm Identifier     |      Key Generation Nonce ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



           Figure 3: The MN-FA Key Generation Nonce From AAA
                         Subtype-Specific Data




      lifetime   This field indicates the duration of time (in seconds)
                 for which the keying material used to create the
                 registration key is valid.


      AAA SPI    A 32-bit opaque value, indicating the SPI that the
                 mobile node must use to determine the transform to use
                 for establishing the Mobility Security Association
                 between the mobile node and its prospective foreign
                 agent.


      FA SPI     The SPI for the Mobility Security Association to the FA
                 that the mobile node creates using the Key Generation
                 Nonce


      Algorithm Identifier
                 This field indicates the transform to be used (stored
                 as part of the Mobility Security Association with
                 the foreign agent, and selected from among the
                 values in the "Authentication Algorithm" table
                 cited in section 4), for future computations of the
                 Mobile-Foreign Authentication Extension.


      Key Generation Nonce
                 A random [7] value of at least 128 bits.


   The MN-FA AAA KeyGen Reply extension MUST appear in the Registration
   Reply before the Mobile-Foreign Authentication extension.


   The Key Generation Nonce is provided by the AAA server for use by the
   mobile node in creating the registration key, which is used to secure
   future Mobile IP registrations with the same foreign agent.




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6.3. Generalized MN-HA Key Generation Nonce Request Extension


   Figure 4 illustrates the Generalized MN-HA Key Generation Nonce
   Request Extension (MN-HA KeyGen Request for short).



       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Type      |    Subtype    |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Mobile Node SPI                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            MN-HA Key Generation Nonce Request Subtype Data ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



        Figure 4: The Generalized Mobile IP MN-HA Key Generation
                        Nonce Request Extension



      Type             TBD3 (not skippable) (see [1] and section 8)


      Subtype          a number assigned to identify the way in
                       which the MN-HA Key Generation Nonce Request
                       Subtype Data is to be used when generating the
                       registration key


      Length           The 16-bit Length field indicates the length of
                       the extension.  It is equal to the number of
                       bytes in the MN-HA Key Generation Nonce Request
                       Subtype Data plus 4 (for the Mobile Node SPI
                       field).


      Mobile Node SPI  The Security Parameters Index that the mobile
                       node will assign for the Mobility Security
                       Association created for use with the registration
                       key.


      MN-HA Key Generation Nonce Request Subtype Data
                       Data needed to carry out the creation of the
                       MN-HA key on behalf of the mobile node.


   The MN-HA KeyGen Request Extension defines a set of extensions,
   identified by subtype, which may be used by a mobile node in a Mobile
   IP Registration Request message to request that some other entity
   create an MN-HA key for use by the mobile node with the mobile node's
   new home agent.





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   This document defines the subtype 1 for the MN-HA Key Generation
   Nonce >From AAA Request (MN-HA AAA KeyGen Request for short).  The
   MN-HA AAA KeyGen Request has a zero-length Subtype Data field
   and MUST appear in the Registration Request before the MN-AAA
   Authentication extension.  The subtype data field is zero in length.



6.4. Generalized MN-HA Key Generation Nonce Reply Extension


   The Generalized MN-HA Key Generation Nonce Reply extension (MN-HA
   KeyGen Reply for short) supplies keying material requested by the
   MN-HA KeyGen Request extension.  Figure 5 illustrates the format of
   the Generalized MN-HA Key Generation Nonce Reply Extension.



       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Type      |    Subtype    |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            Lifetime                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |              MN-HA Key Generation Nonce Reply Subtype Data ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



             Figure 5: The Generalized Mobile IP MN-HA Key
                    Generation Nonce Reply Extension



      Type       TBD4 (not skippable) (see [1] and section 8)


      Subtype    a number assigned to identify the way in which the
                 MN-HA Key Generation Nonce Reply Subtype Data is to be
                 used to obtain the MN-HA key


      Length     The 16-bit Length field indicates the length of the
                 extension.  It is equal to the number of bytes in the
                 MN-HA Key Generation Nonce Reply Subtype Data plus 4
                 (for the Lifetime field).


      Lifetime   This field indicates the duration of time (in seconds)
                 for which the MN-HA key is valid.


      MN-HA Key Generation Nonce Reply Subtype Data
                 Data used to derive the MN-HA key, along with any other
                 information needed by the mobile node to create the
                 designated Mobility Security Association with the home
                 agent.




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   For each subtype, the format of the MN-HA Key Generation Nonce Reply
   Subtype Data has to be separately defined according to the particular
   method required to set up the Mobility Security Association.


   This document defines subtype 1 of the MN-HA KeyGen Reply for the
   MN-HA Key Generation Nonce From AAA extension (MN-HA AAA KeyGen Reply
   for short), shown in figure 6.



       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            AAA SPI                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             HA SPI                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Algorithm Identifier      |         Replay Method         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Key Generation Nonce ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



           Figure 6: The MN-HA Key Generation Nonce From AAA
                         Subtype-Specific Data



      AAA SPI    A 32-bit opaque value, indicating the SPI that the
                 mobile node must use to determine the transform to use
                 for establishing the Mobility Security Association
                 between the mobile node and its home agent.


      HA SPI     The SPI for the Mobility Security Association to the HA
                 that the mobile node creates using the Key Generation
                 Nonce


      Algorithm Identifier
                 This field indicates the transform to be used for
                 future computations of the Mobile-Home Authentication
                 Extension (see section 4)


      Replay Method
                 This field contains the replay method to be used for
                 future Registration messages (see section 4).


      Key Generation Nonce
                 A random [7] value of at least 128 bits.


   The MN-HA AAA KeyGen Reply subtype-specific data is shown in
   figure 6.  The Mobile Node calculates the MN-HA key using the




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   Key Generation Nonce provided by the AAA server.  The calculation
   proceeds by using the key shared between the mobile node and the
   AAA server that has previously been configured for securing all
   such communication requirements with the AAA server which will be
   contacted within the AAA infrastructure (see appendix C).  The MN-HA
   key is intended for use by the mobile node to secure future Mobile
   IP registrations with its home agent.  The MN-HA AAA KeyGen Reply
   extension MUST appear in the Registration Reply before the MN-HA
   Authentication extension.


   Once the mobile node creates the MN-HA Key, by using the transform
   specified in the AAA SPI, it stores the HA Security Information
   indexed by the HA SPI in its list of Mobile Security Associations.
   The mobile node uses the Identification field data from the
   Registration Request as its initial synchronization data with the
   home agent.



7. Error Values


   Each entry in the following table contains the name of the Code [1]
   value to be returned in a Registration Reply, the value for that
   Code, and the section in which the error is first mentioned in this
   specification.


      Error Name               Value   Section
      ----------------------   -----   ---------
      MISSING_MN_FA            107     6.2




8. IANA Considerations


   This document defines 4 new extensions (see Section 6) taken from the
   (non-skippable) numbering space defined for Mobile IP registration
   extensions defined in RFC 3344 [1] as extended in RFC 2356 [8].  The
   values for these extensions are:


      Name                  Value   Section
      --------------------- ------- ---------
      MN-FA-KeyGen Request  TBD1    6.1
      MN-FA-KeyGen Reply    TBD2    6.2
      MN-HA-KeyGen Request  TBD3    6.3
      MN-HA-KeyGen Reply    TBD4    6.4



   IANA will create and maintain new registry for the KeyGen
   Request/Reply subtypes.  The initial contents of the registry is a
   single entry for the subtypes defined in this document:




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      Name                          Value   Section
      ----------------------------- ------- ---------
      KeyGen Request/Reply from AAA 1       6



   New subtypes for these two registries are assigned through Standards
   Action as defined in [9].


   IANA will assign a code value for error MISSING_MN_FA, listed in
   section 7.  This value is to be taken from the space of error values
   conventionally associated with rejection by the foreign agent (i.e.,
   64-127).


   IANA will create and maintain a namespace for the Replay Method
   Identifier.  This specification makes use of 2 and 3; all other
   values other than zero (0) and (1) are available for assignment,
   pending review and approval by a Designated Expert [9].



9. Security Considerations


   The extensions in this document are intended to provide the
   appropriate level of security for Mobile IP entities (mobile node,
   foreign agent, and home agent) to calculate the Authentication Data
   needed by authentication extensions used with Mobile IP registration
   messages.  The Mobility Security Associations resulting from use of
   these extensions do not offer any higher level of security than what
   is already implicit in use of the AAA Security Association between
   the mobile node and the AAAH. In order to deny any adversary the
   luxury of unbounded time to analyze and break the secrecy of the AAA
   Security Association between the mobile node and the AAA server, that
   AAA Security Association MUST be refreshed periodically.


   The provisioning and refreshing of the AAA key in the MN and AAA
   server is outside the scope of this document.


   Since the Reply extensions defined in this specification only carry
   Key Generation Nonces, which are used to derive keys, they do not
   expose any data that could be used in an attack aimed at recovering
   the key shared between the mobile node and the AAA. The authors
   do not believe this specification introduces any new security
   vulnerability.



10. Acknowledgements


   Thanks to Fredrik Johansson, Tom Hiller, and the members of the IESG
   for their useful comments.  Thanks especially to Tom Hiller who has





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   contributed many textual improvements to later revisions of this
   document.


   Funding for the RFC Editor function is currently provided by the
   Internet Society.
















































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Normative References


    [1] C. Perkins.  IP Mobility Support.  Request for Comments
        (Proposed Standard) 3344, Internet Engineering Task Force,
        August 2002.


    [2] B. Aboba and M. Beadles.  The Network Access Identifier.
        Request for Comments (Proposed Standard) 2486, Internet
        Engineering Task Force, January 1999.


    [3] P. Calhoun and C. E. Perkins.  Mobile IP Foreign Agent
        Challenge/Response Extension.  Request for Comments (Proposed
        Standard) 3012, Internet Engineering Task Force, December 2000.


    [4] S. Bradner.  Key words for use in RFCs to Indicate Requirement
        Levels.  Request for Comments (Best Current Practice) 2119,
        Internet Engineering Task Force, March 1997.


    [5] P. Calhoun and C. Perkins.  Mobile IP network access identifier
        extension for IPv4.  Request for Comments (Proposed Standard)
        2794, Internet Engineering Task Force, January 2000.


    [6] H. Krawczyk, M. Bellare, and R. Canetti.  HMAC: Keyed-Hashing
        for Message Authentication.  Request for Comments
        (Informational) 2104, Internet Engineering Task Force,
        February 1997.


    [7] D. Eastlake, 3rd, S. Crocker, and J. Schiller.  Randomness
        Recommendations for Security.  Request for Comments
        (Informational) 1750, Internet Engineering Task Force, December
        1994.


    [8] G. Montenegro and V. Gupta.  Sun's SKIP Firewall Traversal for
        Mobile IP.  Request for Comments (Informational) 2356, Internet
        Engineering Task Force, June 1998.


    [9] T. Narten and H. Alvestrand.  Guidelines for Writing an IANA
        Considerations Section in RFCs.  Request for Comments (Best
        Current Practice) 2434, Internet Engineering Task Force, October
        1998.


   [10] D. Mitton, M. St.Johns, S. Barkley, D. Nelson, B. Patil,
        M. Stevens, and B. Wolff.  Authentication, Authorization,
        and Accounting:  Protocol Evaluation.  Request for Comments
        (Informational) 3127, Internet Engineering Task Force, June
        2001.






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Informative References


   [11] C. Rigney, A. Rubens, W. Simpson, and S. Willens.  Remote
        Authentication Dial In User Service (RADIUS).  Request for
        Comments (Proposed Standard) 2865, Internet Engineering Task
        Force, June 2000.


   [12] Pat R. Calhoun, John Loughney, E. Guttman, Glen Zorn, and Jari
        Arkko.  DIAMETER base protocol (work in progress).  Internet
        Draft, Internet Engineering Task Force, October 2002.


   [13] S. Glass, T. Hiller, S. Jacobs, and C. Perkins.  Mobile IP
        Authentication, Authorization, and Accounting Requirements.
        Request for Comments (Proposed Standard) 2977, Internet
        Engineering Task Force, October 2000.


   [14] P. Calhoun and C. Perkins.  DIAMETER mobile IP extensions (work
        in progress).  Internet Draft, Internet Engineering Task Force,
        February 2004.



A. Changes Since Previous Revision


   The following changes were made in this document since the previous
   revision.


    -  Clarified use of NAI by AAAH when computing the key as detailed
       in Section 5



B. Older Changes


   The following changes were also made as a result of suggestions
   received during and after Last Call.


    -  Expanded the definition of "Registration Key" to include MN-HA as
       well as MN-FA key.


    -  Eliminated HMAC-MD5 with HMAC-SHA1.


    -  Reorganized extensions so that subtypes appear right after the
       generalized forms.


    -  Reorganized IANA considerations to reflect the single number
       space for all 4 kinds of subtypes.


    -  Generalized Key Extensions previously specified in another
       document have been instead specified in this document in order




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       that this document can be self-contained and not dependent on the
       standardization status of the other document.


    -  Additional explanation has been included for the purposes of
       clarifying the problem space and solution approach.


    -  An appendix has been added to describe the expected AAA
       infrastructure that will produce the keys that are to be
       distributed within the extensions specified in this document.


    -  Ladder diagrams have been included to illustrate the expected
       message flows containing the extensions defined in this document.


    -  HMAC-MD5 has been mandated for implementation by the mobile node,
       for compatibility with RFC 3344 [1].  The example text has been
       modified accordingly (see section 5).


    -  A table of Algorithm Identifiers has been identified as the
       numbering space for transform selection when establishing the
       Mobility Security Association using the keys distributed with the
       extensions in this document.  See section 4.


    -  A terminology section has been added.


    -  This appendix has been added.


        *  New terminology entries for "Registration Key", "AAA", "AAA
           entity", "Mobility Security Association", "AAA Security
           Association",


        *  All instances of MN-FA key are now called "registration key"


        *  All instances of the key between mobile node and home agent
           are called "MN-HA" key.


    -  Removed extraneous IANA considerations paragraph for HMAC_MD5


    -  Removed "Unsolicited" from subtype names


    -  Changed minimum Key Material length from 64 bits to 128 bits


    -  Cleaned up terminology:


        *  Clarified the use of "Security Association" throughout the
           document as either "IPSec" or "Mobility" or "AAA".


        *  Changed "Key Material" to "Key Generation Nonce".






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C. AAA Infrastructure


   In this appendix, we attempt to capture the main features of a basic
   model for operation of AAA servers that is assumed for understanding
   of the use of the Mobile IP registration extensions described in this
   document.  This information has been adapted from the discussion in
   RFC 2977 [13].


   Within the Internet, a mobile node belonging to one administrative
   domain (called the home domain) often needs to use resources
   provided by another administrative domain (called the foreign
   domain).  A foreign agent that handles the mobile node's Registration
   Request is likely to require that the mobile node provide some
   credentials that can be authenticated before access to the resources
   is permitted.  These credentials may be provided as part of the
   Mobile-AAA Authentication extension [3], relying on the existence
   of an AAA infrastructure such as is described in this section, and
   also described in RFC 2977 and RFC 3012 [3].  Such credentials are
   typically managed by entities within the mobile node's home domain.
   They may be also used for setting up secure communications with the
   mobile node and the foreign agent, or between the mobile node and its
   home agent if necessary.



                  Local Domain                  Home Domain
                +--------------+           +----------------------+
                |   +------+   |           |   +------+           |
                |   |      |   |           |   |      |           |
                |   | AAAL |   |           |   | AAAH |           |
                |   |      +-------------------+      |           |
                |   +---+--+   |           |   +------+           |
                |       |      |           |                      |
                |       |      |           +----------------------+
     +------+   |   +---+--+   |
     |      |   |   |      |   |       MN   =  mobile node
     |  MN  |- -|- -|  FA  |   |       FA   =  foreign agent
     |      |   |   |      |   |       AAAL =  local authority
     +------+   |   +------+   |       AAAH =  home authority
                |              |
                +--------------+



            Figure 7: AAA Servers in Home and Local Domains



   The foreign agent often does not have direct access to the data
   needed to verify the credentials.  Instead, the foreign agent is
   expected to consult an authority (typically in the same foreign
   domain) in order to request proof that the mobile node has acceptable




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   credentials.  Since the foreign agent and the local authority (AAAL)
   are part of the same administrative domain, they are expected to have
   established, or be able to establish for the necessary lifetime, a
   secure channel for the purposes of exchanging sensitive (access)
   information, and keeping it private from (at least) the visiting
   mobile node.


   The local authority (AAAL) itself may not have enough information
   stored locally to carry out the verification for the credentials
   of the mobile node.  In contrast to the foreign agent, however,
   the AAAL is expected to be configured with enough information to
   negotiate the verification of mobile node credentials with its home
   domain.  The home and foreign domains should be configured with
   sufficient IP Security Associations (i.e., IPSec) and access controls
   so that they can negotiate the authorization, and also enable the
   mobile node to acquire Mobility Security Associations with the
   mobility agents within the foreign domain.  For the purposes of the
   key exchanges specified within this document, the authorization is
   expected to depend only upon secure authentication of the mobile
   node's credentials.


   Once the authorization has been obtained by the local authority, and
   the authority has notified the foreign agent about the successful
   negotiation, the foreign agent can deliver the Registration Reply to
   the mobile node along with the key material.


   In figure 7, there might be many mobile nodes from many different
   Home Domains.  Each Home Domain provides a AAAH that can check
   credentials originating from mobile nodes administered by that Home
   Domain.  There is a security model implicit in figure 7, and it is
   crucial to identify the specific security associations assumed in
   the security model.  These IP Security Associations are illustrated
   in figure 8, and are considered to be relatively long-lived security
   associations.


   First, it is natural to assume that the mobile node has an AAA
   Security Association with the AAAH, since that is roughly what it
   means for the mobile node to belong to the home domain.


   Second, from the model illustrated in figure 7 it is clear that AAAL
   and AAAH have to share an IP Security Association, because otherwise
   they could not rely on the authentication results, authorizations,
   nor even the accounting data which might be transacted between them.
   Requiring such bilateral IP Security Associations is, however, in the
   end not scalable; the AAA framework must provide for more scalable
   mechanisms, but the methods by which such a broker model is to be
   created are out of scope for this document.  See RFC 2977 for more
   details.





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   Finally, from figure 7, it is clear that the foreign agent can
   naturally share an IP Security Association with the AAAL. This is
   necessary in order for the model to work because the foreign agent
   has to have a way to find out that it is permissible to allocate
   the local resources to the mobile node, and further to transmit any
   successful Registration Reply to the mobile node.


   Figure 8 illustrates the IP Security Associations we understand from
   our proposed model.  Note that there may be, by mutual agreement
   between AAAL and AAAH, a third party inserted between AAAL and
   AAAH to help them arbitrate secure transactions in a more scalable
   fashion.  The broker model which has been designed to enable such
   third-party processing should not have any effect on the Mobile IP
   extensions specified in this document, and so no description is
   provided here; see RFC 2977 [13] for more details.



                               +------+              +------+
                               |      |              |      |
                               | AAAL +--------------+ AAAH |
                               |      |              |      |
                               +---+--+              +--+---+
                                   |                    |
                                   |                    |
                               +---+--+              +--+---+
   MN   =  mobile node         |      |              |      |
   FA   =  foreign agent       |  FA  |              |  MN  |
   AAAL =  local authority     |      |              |      |
   AAAH =  home authority      +------+              +------+



                   Figure 8: IP Security Associations




   Nodes in two separate administrative domains (for instance, AAAH
   and AAAL) often must take additional steps to verify the identity
   of their communication partners, or alternatively to guarantee
   the privacy of the data making up the communication.  While these
   considerations lead to important security requirements, as mentioned
   above in the context of security between servers, we consider the
   exact choice of IP Security Associations between the AAA servers to
   be beyond the scope of this document.  The choices are unlikely to
   depend upon Mobile IP, or any specific features of the general model
   illustrated in figure 7.  On the other hand, the Mobility Security
   Associations needed between Mobile IP entities are of central
   importance in the design of the key derivation extensions in this
   document.





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   One further detail deserves mention.  The Mobility Security
   Association to be established between the mobile node and the foreign
   agent has to be communicated to the foreign agent as well as to the
   mobile node.  The following requirements are placed on the mechanism
   used by the AAA infrastructure to effect key distribution:


    -  The AAAH must establish strong, fresh session keys.


    -  The mechanism must maintain algorithm independence, allowing for
       the distribution of authentication algorithm identification along
       with the keys.


    -  The mechanism must include replay detection.


    -  The mechanism must authenticate all parties, including the AAA
       servers and the FA and HA.


    -  The mechanism must provide for authorization of the client, FA,
       and HA.


    -  The mechanism must not rely on plaintext passwords.


    -  The mechanism must maintain confidentiality of session keys.


    -  The mechanism must uniquely name session keys.


    -  The mechanism must be such that the compromise of a single FA
       and HA cannot compromise any other part of the system, including
       session keys and long-term keys


    -  The mechanism must bind key(s) to an appropriate context


    -  The mechanism must not expose the keys to entities other than the
       AAAH and FA (or HA in the case of key distribution to the HA).


   The way that the key is distributed to the foreign agent (or
   home agent) is expected to be handled as part of the AAA protocol
   processing between the AAAH and AAAL, and the further AAA protocol
   processing between the AAAL and the foreign agent.  Such processing
   is outside the scope of this document, but must satisfy the above
   requirements.



D. Message Flow for Requesting and Receiving Registration Keys


   In this section, we show message flows for requesting and receiving
   a registration key from the AAA infrastructure, described in
   section C.  Challenge values, as specified in [3], might be added to





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   the Advertisement and Registration messages for additional replay
   protection, but are not illustrated here.


   Diagram 9 illustrates the message flow for the case when the mobile
   node explicitly requests keying material to create registration keys.



        MN                     FA                  AAA Infrastructure
         |                       |                           |
         |<--- Advertisement-----|                           |
         |      (if needed)      |                           |
         |                       |                           |
         |-- RReq+AAA Key Req.-->|                           |
         |                       |--- RReq + AAA Key Req.--->|
         |                       |                           |
         |                       |<--- RRep + AAA Key Rep.---|
         |<-- RRep+AAA Key Rep.--|                           |
         |                       |                           |



               Figure 9: Message Flows for Requesting and
                     Receiving Key Generation Nonce



   In diagram 9, the following message flow is illustrated:


    1. The foreign agent disseminates an Agent Advertisement.  This
       advertisement MAY have been produced after receiving an Agent
       Solicitation from the mobile node (not shown in the diagram).


    2. The mobile node creates a Registration Request including the
       MN-HA AAA KeyGen Request and/or MN-FA AAA KeyGen Request, as
       needed, along with an authorization-enabling authentication
       extension as required by Mobile IP [1].


    3. The foreign agent relays the Registration Request and/or Key
       Request(s) to its locally configured AAA Infrastructure (see
       appendix C), according to local policy.


    4. The foreign agent receives a AAA Response with the appropriate
       indications for authorizing connectivity for the mobile node.
       Along with this AAA Response, the foreign agent may also receive
       key material by some secure method appropriate for communications
       between it and its local AAA infrastructure.  At this point if
       the foreign agent has not relayed the Registration Request,
       it forwards it directly to the Home Agent and waits for a
       Registration Reply (not shown in the figure).






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    5. The foreign agent relays the Registration Reply to the mobile
       node, along with the new AAA KeyGen Reply extensions to be used
       by the mobile node to establish Mobility Security Associations
       with the relevant mobility agents (foreign agent and/or home
       agent).


   Diagram 10 illustrates the message flow for the case when the
   mobile node receives an unsolicited keying matereial from the AAA
   Infrastructure.



        MN                     FA                  AAA Infrastructure
         |                       |                           |
         |<--- Advertisement-----|                           |
         |      (if needed)      |                           |
         |                       |                           |
         | ------ RReq --------->|                           |
         |                       |------- RReq ------------->|
         |                       |                           |
         |                       |<--- RRep + AAA Key Rep.---|
         |<-- RRep+AAA Key Rep.--|                           |
         |                       |                           |



           Figure 10: Message Flow for Receiving Unsolicited
                          Key Generation Nonce



   In diagram 10, the following message flow is illustrated:


    1. The foreign agent disseminates an Agent Advertisement.  This
       advertisement MAY have been produced after receiving an Agent
       Solicitation from the mobile node (not shown in the diagram).


    2. The mobile node creates a Registration Request including an
       authorization-enabling authentication extension as required by
       Mobile IP [1].


    3. The foreign agent sends a AAA Request (possibly containing
       the Registration Request) to its locally configured AAA
       Infrastructure (see appendix C), according to local policy.


    4. The foreign agent receives a AAA Response with the appropriate
       indications for authorizing connectivity for the mobile node.
       Along with this AAA Response, the foreign agent may also receive
       key material by some secure method appropriate for communications
       between it and its local AAA infrastructure.  At this point,
       if the foreign agent has not relayed the Registration Request,





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       it forwards it directly to the Home Agent and waits for a
       Registration Reply (not shown in the figure).


    5. The foreign agent relays the Registration Reply to the mobile
       node, along with the new KeyGen Reply extensions to be used by
       the mobile node to establish Mobility Security Associations with
       the relevant mobility agents (foreign agent and/or home agent).














































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Intellectual Property


   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
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   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.


   Copies of IPR disclosures made to the IETF Secretariat and any
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   http://www.ietf.org/ipr.


   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at
   ietf-ipr@ietf.org.



Full Copyright Statement


   Full Copyright Statement


   Copyright (C) The Internet Society (2004).  This document is subject
   to the rights, licenses and restrictions contained in BCP 78 and
   except as set forth therein, the authors retain all their rights.


   This document and the information contained herein are provided
   on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
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   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.



Addresses


   The working group can be contacted via the current chairs:








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      Pete McCann                 Henrik Levkowetz
      Lucent Technologies         ipUnplugged AB
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      1960 Lucent Lane            Stockholm S-121 28
      Naperville, IL 60563        Sweden
      USA
      Phone:  +1 630 369 9693     Phone:  +46 708 32 16 08
      Email:  mccap@lucent.com    Email:  henrik@levkowetz.com




   Questions about this memo can also be directed to the authors:


      Charles E. Perkins                  Pat R. Calhoun
      Communications Systems Lab
      Nokia Research Center               Airespace Networks
      313 Fairchild Drive                 110 Nortech Parkway
      Mountain View, California 94043     San Jose, CA 95134
      USA                                 USA
      Phone:  +1-650 625-2986             Phone:  +1 408 635 2000
      EMail:  charles.perkins@nokia.com   Email:  pcalhoun@diameter.org
      Fax:  +1 650 625-2502               Fax:  +1 720-293-7501































Perkins, Calhoun           Expires 29 September 2004           [Page 30]

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