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Versions: (draft-hoeper-hokey-arch-design) 00 01 02 03 04 05 06 07 08 09 10 11 RFC 6697

Network Working Group                                          K. Hoeper
Internet-Draft                                                  Motorola
Intended status: Informational                                S. Decugis
Expires: April 28, 2011                                             NICT
                                                                 G. Zorn
                                                             Network Zen
                                                                   Q. Wu
                                                               T. Taylor
                                                                  Huawei
                                                        October 25, 2010


              Handover Keying (HOKEY) Architecture Design
                    draft-ietf-hokey-arch-design-01

Abstract

   The Handover Keying (HOKEY) Working Group seeks to minimize handover
   delay due to authentication when a peer moves from one point of
   attachment to another.  Work has progressed on two different
   approaches to reduce handover delay: early authentication (so that
   authentication does not need to be performed during handover), and
   reuse of cryptographic material generated during an initial
   authentication to save time during re-authentication.  A starting
   assumption is that the mobile host or "peer" is initially
   authenticated using the Extensible Authentication Protocol (EAP),
   executed between the peer and an EAP server as defined in RFC 3748.

   This document documents the HOKEY architecture.  Specifically, it
   describes design objectives, the functional environment within which
   handover keying operates, the functions to be performed by the HOKEY
   architecture itself, and the assignment of those functions to
   architectural components.  It goes on to illustrate the operation of
   the architecture within various deployment scenarios that are
   described more fully in other documents produced by the HOKEY Working
   Group.

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



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   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 April 28, 2011.

Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.































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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  6
   3.  Design Goals . . . . . . . . . . . . . . . . . . . . . . . . .  6
     3.1.  Reducing Signalling Overhead . . . . . . . . . . . . . . .  6
       3.1.1.  Minimized Communications with Home Servers . . . . . .  6
       3.1.2.  Integrated Local Domain Name (LDN) Discovery . . . . .  7
     3.2.  Better Deployment Scalability  . . . . . . . . . . . . . .  7
   4.  Functions That Must Be Supported . . . . . . . . . . . . . . .  7
     4.1.  System Overview  . . . . . . . . . . . . . . . . . . . . .  7
     4.2.  Pre-Authentication Function (Direct or Indirect) . . . . . 10
     4.3.  EAP Re-authentication Function . . . . . . . . . . . . . . 10
     4.4.  EAP Authentication Function  . . . . . . . . . . . . . . . 10
     4.5.  Authenticated Anticipatory Keying (AAK) Function . . . . . 10
     4.6.  EAP-Based Handover Key Management  . . . . . . . . . . . . 11
   5.  Components of the HOKEY Architecture . . . . . . . . . . . . . 11
     5.1.  Functions of the Peer  . . . . . . . . . . . . . . . . . . 12
     5.2.  Functions of the Serving Authenticator . . . . . . . . . . 12
     5.3.  Functions of the Candidate Authenticator . . . . . . . . . 13
     5.4.  Functions of the EAP Server  . . . . . . . . . . . . . . . 14
     5.5.  Functions of the ER Server . . . . . . . . . . . . . . . . 15
   6.  Deployment Scenarios . . . . . . . . . . . . . . . . . . . . . 16
   7.  AAA Consideration  . . . . . . . . . . . . . . . . . . . . . . 16
     7.1.  Standalone HOKEY server  . . . . . . . . . . . . . . . . . 16
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 17
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 17
   10. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 17
   11. Informative References . . . . . . . . . . . . . . . . . . . . 17
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18





















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1.  Introduction

   The Extensible Authentication Protocol (EAP) [RFC3748] is an
   authentication framework that supports different types of
   authentication methods.  Originally designed for dial-up connections,
   EAP is now commonly used for authentication in wireless access
   networks.

   When a host (or "peer", the term used from this point onward) changes
   its point of attachment to the network, it must be re-authenticated.
   If a full EAP authentication must be repeated, several message round-
   trips between the peer and the home EAP server may be involved.  The
   resulting delay will result in degradation or in the worst case loss
   of any service session in progress if communication is suspended
   while re-authentication is carried out.  The delay is worse if the
   new point of attachment is in a visited network rather than the
   peer's home network, because of the extra procedural steps involved
   as well as because of the probable increase in round-trip time.

   [RFC5169] describes this problem more fully and establishes design
   goals for solutions to reduce re-authentication delay for transfers
   within a single administrative domain.  [RFC5169] also suggests a
   number of ways to achieve a solution:

   o  specification of a method-independent, efficient, re-
      authentication protocol;

   o  reuse of keying material from the initial authentication;

   o  deployment of re-authentication servers local to the peer to
      reduce round-trip delay; and

   o  specification of the additional protocol needed to allow the EAP
      server to pass authentication information to the local re-
      authentication servers.

   [RFC5295] tackles the problem of reuse of keying material by
   specifying how to derive a hierarchy of cryptographically independent
   purpose-specific keys from the results of the original EAP
   authentication.  [RFC5296] specifies a method-independent re-
   authentication protocol (ERP) applicable to two specific deployment
   scenarios:

   o  where the peer's home EAP server also performs re-authentication;
      and

   o  where a local re-authentication server exists but is collocated
      with a AAA proxy within the domain.



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   Other work provides further pieces of the solution or insight into
   the problem.  For the purpose of this draft, [RFC5749] provides an
   abstract mechanism for distribution of keying material from the EAP
   server to re-authentication servers.  [RFC5836] contrasts the EAP re-
   authentication (ER) strategy provided by [RFC5296] with an
   alternative strategy called "early authentication".  [RFC5836]
   defines EAP early authentication as the use of EAP by a mobile peer
   to establish authenticated keying material on a target attachment
   point prior to its arrival.  Here, a full EAP execution occurs before
   the handover of the peer takes place.  Hence, the goal of EAP early
   authentication is to complete all EAP-related communications,
   including AAA signaling, in preparation for the handover, before the
   mobile device actually moves.  Early authentication includes direct
   and indirect pre-authentication as well as Authenticated Anticipatory
   Keying (AKK).  All three mechanims provide means to execute a full
   EAP authentication with a Candidate Access Point (CAP) while still
   being connected to the Serving Access Point (SAP) but vary in their
   respective system assumptions and communication paths.  In
   particular, direct pre-authentication assumes that clients are
   capable of discovering candidate access points and all communications
   are routed through the serving access point.  On the other hand,
   indirect pre-authentication assumes an existing relationship betweem
   SAP and CAP, whereas in AAK the client interacts with the AAA to
   discover and connect to CAPs.

   Both EAP re-authentication and early authentication enable faster
   inter-authenticator handovers.  However, it is currently unclear how
   the necessary handover infrastructure is deployed and can be
   integrated into existing EAP infrastructures.  In particular,
   previous work has not described how ER servers that act as endpoints
   in the re-authentication process should be integrated into local and
   home domain networks.  Furthermore, it is currently unspecified how
   EAP infrastructure can support the timely triggering of early
   authentications and aid with the selection of candidate access
   points.

   This document proposes a general HOKEY architecture and demonstrates
   how it can be adapted to different deployment scenarios.  To begin
   with, Section 3 recalls the design objectives for the HOKEY
   architecture.  Section 4 reviews the functions that must be supported
   within the architecture.  Section 5 describes the components of the
   HOKEY architecture.  Finally, Section 6 describes the different
   deployment scenarios that the HOKEY Working Group has addressed and
   the information flows that must occur within those scenarios, by
   reference to the documents summarized above where possible and
   otherwise within this document itself.





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2.  Terminology

   This document contains no normative language, hence [RFC2119]
   language does not apply.

   This document reuses most of the terms defined in Section 2.2 of
   [RFC5836].  In addition, it defines the following:

   EAP Early Authentication
      The use of EAP by a mobile peer to establish authenticated keying
      material on a target attachment point prior to its arrival, see
      [RFC5836].

   EAP Re-authentication (ER)
      The use of keying material derived from an initial EAP
      authentication to enable single-roundtrip re-authentication of a
      mobile peer.  For a detailed description of the keying material
      see Section 3 of [RFC5296].

   ER Server
      A component of the HOKEY architecture that terminates the EAP re-
      authentication exchange with the peer.

   ER Key Management
      An instantiation of the mechanism provided by [RFC5749] for
      creating and delivering root keys from an EAP server to an ER
      server.


3.  Design Goals

   This section investigates the design goals for the HOKEY
   architecture.  These include reducing the signaling overhead for re-
   authentication and early authentication, integrating local domain
   name discovery, and improving deployment scalability.  These goals
   supplement the discussion in [RFC5169].

3.1.  Reducing Signalling Overhead

3.1.1.  Minimized Communications with Home Servers

   ERP requires only one round trip, however, this roundtrip may require
   communications between a peer and its home ER and/or home AAA server
   even if the peer is currently attached to a visited (local) network.
   As a result, even this one round trip may introduce long delays
   because home ER and home AAA servers may be distant from the peer.
   To lower the signaling overhead, communication with the home ER
   server and home AAA server should be minimized.  Ideally, a peer



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   should only need to communicate with local servers and other local
   entities.

3.1.2.  Integrated Local Domain Name (LDN) Discovery

   ERP bootstrapping must occur before (implicit) or during (explicit) a
   handover to transport the necessary re-authentication root keys to
   the local ER server involved.  Implicit bootstrapping is preferable
   because it does not require communication with the home ER server
   during handover (see previous section), but it requires the peer to
   know the domain name of the ER server in order to derive the
   necessary re-authentication keying material.  [RFC5296] does not
   specify such a domain name discovery mechanism and suggests that the
   peer may learn the domain name through the EAP- Initiate/
   Re-auth-Start message or via lower layer announcements.  To allow
   more efficient handovers, a HOKEY architecture should support an
   efficient domain name discovery mechanism and allow its integration
   with ERP implicit bootstrapping.  Even in the case of explicit
   bootstrapping, local domain name discovery should be optimized such
   that it does not require contacting the home AAA server, as is
   currently the case.

3.2.  Better Deployment Scalability

   To provide better deployment scalability, it should not be required
   that the HOKEY server and AAA servers or proxies are collocated.
   Separation of these entities may cause problems with routing, but
   allows flexibility in deployment and implementation.


4.  Functions That Must Be Supported

4.1.  System Overview

   This section views the HOKEY architecture as the implementation of a
   subsystem providing authentication services to AAA.  Not only does
   AAA depend on the authentication subsystem, but the latter also
   depends on AAA as a means for the routing and secure transport of
   messages internal to the operation of network access authentication.

   The operation of the authentication subsystem also depends on the
   availability of a number of discovery functions:

   o  discovery of candidate access points, by the peer, by the serving
      attachment point, or by some other entity;

   o  discovery of the authentication services supported at a given
      candidate access point;



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   o  discovery of the required server in the home domain when a
      candidate access point is not in the same domain as the serving
      attachment point, or no local server is available;

   o  peer discovery of the local domain name (LDN) when EAP re-
      authentication is used with a local server.

   It is assumed that these functions are provided by the environment
   within which the authentication subsystem operates, and are outside
   the scope of the authentication subsystem itself.  Local domain name
   discovery is a possible exception.

   Figure 1 shows the major functions comprising the authentication
   subsystem and their interdependencies.  These functions are described
   below.  [EDITOR'S NOTE: These probably need refinement.  The
   relationship of pre-authentication to EAP authentication, for
   instance, is currently not totally correct, when one takes account of
   the roles described in Section 5.  AAK also needs an extension of ER
   key management.]
































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   +------------------------------------------------------------+
   |   AAA Network Access Authentication and Authorization      |
   +---+-------------.----------------------------+-------------+
       |            /|\                           |
       |             |  Authentication subsystem  |
   +===|=============|============================|=============+
   |   |   +---------+----------+   +-------------V---------+   |
   |   |   |    Direct and      |   | EAP Re-authentication |   |
   |   |   |      Indirect      |   +--+------+-------------+   |
   |   |   | Pre-Authentication |     /      /                  |
   |   |   +--------------------+    /      /                   |
   |   |                            /      / +---------------+  |
   |   |                           /      |  | Authenticated |  |
   |   |                          /       |  | Anticipatory  |  |
   |   |                         /        |  | Keying (AAK)  |  |
   |   |                        /         |  +-------+-------+  |
   |   |                       /          |          |          |
   | +-V------------------+   / +---------V----------V--------+ |
   | | EAP Authentication |  |  |       ER Key Management     | |
   | +---------+----------+  |  |+------------+ +------------+| |
   |           |             |  ||Handover Key| |Handover Key|| |
   |           |             |  || Derivation | |Distribution|| |
   |           |             |  |+------------+ +------+-----+| |
   |           |             |  +----------------------|------+ |
   +===========|=============|=========================|========+
               |             |                         |
   +-----------V-------------V-------------------------V--------+
   |             AAA routing and secure transport               |
   +------------------------------------------------------------+

   Arrows show the direction of functional dependency.

          Figure 1: Authentication Subsystem  Functional Overview

   Figure 1 shows the following dependencies:

   o  When AAA is invoked to authenticate and authorize network access,
      it uses one of two services offered by the authentication
      subsystem: full EAP authentication, or EAP re-authentication.

   o  Pre-authentication triggers AAA network access authentication and
      authorization at each candidate access point, which in turn causes
      full EAP authentication to be invoked.

   o  EAP re-authentication invokes ER key management at the time of
      authentication to create and distribute keying material to ER
      servers.




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   o  Authenticated anticipatory keying (AAK) relies on ER key
      management to establish keying material on ER/AAK servers, but
      uses an extension to ER key management to derive and establish
      keying material on candidate authenticators.

   EAP authentication, EAP re-authentication, and handover key
   distribution depend on the routing and secure transport service
   provided by AAA.  Discovery functions and the function of
   authentication and authorization of network entities (access points,
   ER servers) are not shown.  As stated above, these are external to
   the authentication subsystem.

4.2.  Pre-Authentication Function (Direct or Indirect)

   The pre-authentication function is responsible for discovery of
   candidate access points and completion of network access
   authentication and authorization at each candidate access point in
   advance of handover.  The operation of this function is described in
   general terms in [RFC5836].  No document is yet available to describe
   the implementation of pre-authentication in terms of specific
   protocols.  [RFC5873] could be part of the solution, but is
   Experimental rather than Standards Track.

4.3.  EAP Re-authentication Function

   The EAP re-authentication function is responsible for authenticating
   the peer at a specific access point using keying material derived
   from a prior full EAP authentication.  [RFC5169] provides the design
   objectives for an implementation of this function.  [RFC5296]
   describes a protocol to implement EAP re-authentication subject to
   the architectural restrictions noted above.  Work is in progress to
   relax those restrictions.

4.4.  EAP Authentication Function

   The EAP authentication function is responsible for authenticating the
   peer at a specific access point using a full EAP exchange.  [RFC3748]
   defines the associated protocol.  [RFC5836] shows the use of EAP as
   part of pre-authentication.  Note that the HOKEY Working Group has
   not specified the non-AAA protocol required to transport EAP frames
   over IP that is shown in Figures 3 and 5 of [RFC5836], although
   [RFC5873] is a candidate.

4.5.  Authenticated Anticipatory Keying (AAK) Function

   The authenticated anticipatory keying function is responsible for
   pre-placing keying material derived from an initial full EAP
   authentication on candidate access points.  The operation is carried



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   out in two steps: ER key management (with trigger not currently
   specified) places root keys derived from initial EAP authentication
   onto an ER/AAK server associated with the peer.  When requested by
   the peer, the ER/AAK server derives and pushes predefined master
   session keys to a list of candidate access points.  The operation of
   the authenticated anticipatory keying function is described in very
   general terms in [RFC5836].  A protocol implementation is being
   specified in [I-D.ietf-hokey-erp-aak].

4.6.  EAP-Based Handover Key Management

   EAP-based handover key management consists of EAP method independent
   key derivation and distribution and comprises the following specific
   functions:

   o  handover key derivation; and

   o  handover key distribution.

   The derivation of handover keys is specified in [RFC5295], and key
   distribution is specified in [RFC5749].


5.  Components of the HOKEY Architecture

   This section describes the components of the HOKEY architecture, in
   terms of the functions they perform.  The components cooperate as
   described in this section to carry out the functions described in the
   previous section.  Section 6 describes the different deployment
   scenarios that are possible using these functions.

   The components of the HOKEY architecture are as follows:

   o  the peer;

   o  the authenticator, which is a part of the serving access point and
      candidate access points;

   o  the EAP server; and

   o  the ER server, either in the home domain or local to the
      authenticator.

   [EDITOR'S NOTE: probably have to add the ER/AAK server named in
   [I-D.ietf-hokey-erp-aak] to this list.]






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5.1.  Functions of the Peer

   The peer participates in the functions described in Section 4 as
   shown in Table 1.

   +--------------------+----------------------------------------------+
   | Function           | Peer Role                                    |
   +--------------------+----------------------------------------------+
   | EAP authentication | Determines that full EAP authentication is   |
   |                    | needed based on context (e.g., initial       |
   |                    | authentication), prompting from the          |
   |                    | authenticator, or discovery that only EAP    |
   |                    | authentication is supported.  Participates   |
   |                    | in the EAP exchange with the EAP server.     |
   | -                  | -                                            |
   | Direct             | Discovers candidate access points.           |
   | pre-authentication | Initiates pre-authentication with each,      |
   |                    | followed by EAP authentication as above, but |
   |                    | using IP rather than L2 transport for the    |
   |                    | EAP frames.                                  |
   | -                  | -                                            |
   | Indirect           | Enters into a full EAP exchange when         |
   | pre-authentication | triggered, using either L2 or L3 transport   |
   |                    | for the frames.                              |
   | -                  | -                                            |
   | EAP                | Determines that EAP re-authentication is     |
   | re-authentication  | possible based on discovery or authenticator |
   |                    | prompting.  Discovers ER server.             |
   |                    | Participates in ERP exchange with ER server. |
   | -                  | -                                            |
   | Authenticated      | Determines that AAK is possible based on     |
   | anticipatory       | discovery or serving authenticator           |
   | keying             | prompting.  Discovers candidate access       |
   |                    | points.  Sends request to serving            |
   |                    | authenticator to distribute keying material  |
   |                    | to the candidate access points.              |
   | -                  | -                                            |
   | ER key management  | No role.                                     |
   +--------------------+----------------------------------------------+

                      Table 1: Functions of the Peer

5.2.  Functions of the Serving Authenticator

   The serving authenticator participates in the functions described in
   Section 4 as shown in Table 2.





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   +--------------------+----------------------------------------------+
   | Function           | Serving Authenticator Role                   |
   +--------------------+----------------------------------------------+
   | EAP authentication | No role.                                     |
   | -                  | -                                            |
   | Direct             | No role.                                     |
   | pre-authentication |                                              |
   | -                  | -                                            |
   | Indirect           | Discovers candidate access points.           |
   | pre-authentication | Initiates an EAP exchange between the peer   |
   |                    | and the EAP server through each candidate    |
   |                    | authenticator.  Mediates between L2          |
   |                    | transport of EAP frames on the peer side and |
   |                    | a non-AAA protocol over IP toward the        |
   |                    | candidate access point.                      |
   | -                  | -                                            |
   | EAP                | No role.                                     |
   | re-authentication  |                                              |
   | -                  | -                                            |
   | Authenticated      | Mediates between L2 transport of AAK frames  |
   | anticipatory       | on the peer side and AAA transport toward    |
   | keying             | the ER/AAK server.                           |
   | -                  | -                                            |
   | ER key management  | No role.                                     |
   +--------------------+----------------------------------------------+

              Table 2: Functions of the Serving Authenticator

5.3.  Functions of the Candidate Authenticator

   The candidate authenticator participates in the functions described
   in Section 4 as shown in Table 3.



















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   +--------------------+----------------------------------------------+
   | Function           | Candidate Authenticator Role                 |
   +--------------------+----------------------------------------------+
   | EAP authentication | Invokes AAA network access authentication    |
   |                    | and authorization upon handover/initial      |
   |                    | attachment.  Mediates between L2 transport   |
   |                    | of EAP frames on the peer link and AAA       |
   |                    | transport toward the EAP server.             |
   | -                  | -                                            |
   | Direct             | Invokes AAA network access authentication    |
   | pre-authentication | and authorization when the peer initiates    |
   |                    | authentication.  Mediates between non-AAA L3 |
   |                    | transport of EAP frames on the peer side and |
   |                    | AAA transport toward the EAP server.         |
   | -                  | -                                            |
   | Indirect           | Same as direct pre-authentication, except    |
   | pre-authentication | that it communicates with the serving        |
   |                    | authenticator rather than the peer.          |
   | -                  | -                                            |
   | EAP                | Invokes AAA network access authentication    |
   | re-authentication  | and authorization upon handover.  Discovers  |
   |                    | or is configured with the address of the ER  |
   |                    | server.  Mediates between L2 transport of a  |
   |                    | ERP frames on the peer side and AAA          |
   |                    | transport toward the ER server.              |
   | -                  | -                                            |
   | Authenticated      | Receives and saves pMSK.                     |
   | anticipatory       |                                              |
   | keying             |                                              |
   | -                  | -                                            |
   | ER key management  | No role.                                     |
   +--------------------+----------------------------------------------+

             Table 3: Functions of the Candidate Authenticator

5.4.  Functions of the EAP Server

   The EAP server participates in the functions described in Section 4
   as shown in Table 4.












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   +--------------------+----------------------------------------------+
   | Function           | EAP Server Role                              |
   +--------------------+----------------------------------------------+
   | EAP authentication | Authenticates and authorizes the candidate   |
   |                    | access point to act as authenticator.        |
   |                    | Terminates EAP signalling between it and the |
   |                    | peer via the candidate authenticator.        |
   |                    | Determines whether network access            |
   |                    | authentication succeeds or fails.  Provides  |
   |                    | MSK to authenticator.                        |
   | -                  | -                                            |
   | Direct             | As for EAP authentication.                   |
   | pre-authentication |                                              |
   | -                  | -                                            |
   | Indirect           | As for EAP authentication.                   |
   | pre-authentication |                                              |
   | -                  | -                                            |
   | EAP                | Mutually authenticates with the ER server    |
   | re-authentication  | and authorizes it for receiving keying       |
   |                    | amterial.  Provides rRK or DSrRK to the ER   |
   |                    | server.                                      |
   | -                  | -                                            |
   | Authenticated      | As for EAP re-authentication.                |
   | anticipatory       |                                              |
   | keying             |                                              |
   | -                  | -                                            |
   | ER key management  | Creates rRK or DSrRK and distributes it to   |
   |                    | ER server requesting the information.        |
   +--------------------+----------------------------------------------+

                   Table 4: Functions of the EAP Server

5.5.  Functions of the ER Server

   The ER server participates in the functions described in Section 4 as
   shown in Table 5.  [EDITOR'S NOTE: Need discussion of respective
   roles of local and home ER server, or whether there should even be
   such a distinction.]













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   +--------------------+----------------------------------------------+
   | Function           | ER Server Role                               |
   +--------------------+----------------------------------------------+
   | EAP authentication | No role.                                     |
   | -                  | -                                            |
   | Direct             | No role.                                     |
   | pre-authentication |                                              |
   | -                  | -                                            |
   | Indirect           | No role.                                     |
   | pre-authentication |                                              |
   | -                  | -                                            |
   | EAP                | Authenticates and authorizes the candidate   |
   | re-authentication  | access point to act as authenticator.        |
   |                    | Authenticates itself to the EAP server and   |
   |                    | acquires rRK or DSrRK as applicable when     |
   |                    | necessary.  Terminates ERP signalling        |
   |                    | between it and the peer via the candidate    |
   |                    | authenticator.  Determines whether network   |
   |                    | access authentication succeeds or fails.     |
   |                    | Provides MSK to authenticator.               |
   | -                  | -                                            |
   | Authenticated      | Authenticates itself to the EAP server and   |
   | anticipatory       | acquires rRK or DSrRK as applicable when     |
   | keying             | necessary.  Authenticates and authorizes the |
   |                    | candidate access points to act as            |
   |                    | authenticator.  Derives pMSKs and passes     |
   |                    | them to the candidate access points.         |
   | -                  | -                                            |
   | ER key management  | Receives and saves rRK or DSrRK as           |
   |                    | applicable.                                  |
   +--------------------+----------------------------------------------+

                    Table 5: Functions of the ER Server


6.  Deployment Scenarios

   The necessity for this section and its contents are TBD.


7.  AAA Consideration

7.1.  Standalone HOKEY server

   TBD.






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8.  Security Considerations

   TBD


9.  IANA Considerations

   This document has no actions for IANA.


10.  Acknowledgments

   The authors would like to thank Mark Jones and Zhen Cao for their
   reviews of previous versions of this draft.


11.  Informative References

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

   [RFC3748]  Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
              Levkowetz, "Extensible Authentication Protocol (EAP)",
              RFC 3748, June 2004.

   [RFC5169]  Clancy, T., Nakhjiri, M., Narayanan, V., and L. Dondeti,
              "Handover Key Management and Re-Authentication Problem
              Statement", RFC 5169, March 2008.

   [RFC5295]  Salowey, J., Dondeti, L., Narayanan, V., and M. Nakhjiri,
              "Specification for the Derivation of Root Keys from an
              Extended Master Session Key (EMSK)", RFC 5295,
              August 2008.

   [RFC5296]  Narayanan, V. and L. Dondeti, "EAP Extensions for EAP Re-
              authentication Protocol (ERP)", RFC 5296, August 2008.

   [RFC5749]  Hoeper, K., Nakhjiri, M., and Y. Ohba, "Distribution of
              EAP-Based Keys for Handover and Re-Authentication",
              RFC 5749, March 2010.

   [RFC5836]  Ohba, Y., Wu, Q., and G. Zorn, "Extensible Authentication
              Protocol (EAP) Early Authentication Problem Statement",
              RFC 5836, April 2010.

   [RFC5873]  Ohba, Y. and A. Yegin, "Pre-Authentication Support for the
              Protocol for Carrying Authentication for Network Access
              (PANA)", RFC 5873, May 2010.



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   [I-D.ietf-hokey-erp-aak]
              Cao, Z., Deng, H., Wang, Y., Wu, Q., and G. Zorn, "EAP Re-
              authentication Protocol Extensions for Authenticated
              Anticipatory Keying (ERP/AAK)", Internet
              Draft draft-ietf-hokey-erp-aak-02, May 2010.


Authors' Addresses

   Katrin Hoeper
   Motorola, Inc.
   1301 E. Algonquin Road
   Schaumburg, IL  60196
   USA

   Email: khoeper@motorola.com


   Sebastien Decugis
   NICT
   4-2-1 Nukui-Kitamachi
   Tokyo, Koganei  184-8795
   Japan

   Email: sdecugis@nict.go.jp


   Glen Zorn
   Network Zen
   1310 East Thomas Street
   Seattle, Washington  98102
   USA

   Email: gwz@net-zen.net


   Qin Wu
   Huawei Technologies Co.,Ltd
   Site B, Floor 12F, Huihong Mansion, No.91 Baixia Rd.
   Nanjing, JiangSu  210001
   China

   Phone: +86-25-84565892
   Email: sunseawq@huawei.com







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   Tom Taylor
   Huawei Technologies Co., Ltd
   Ottawa
   Canada

   Email: tom111.taylor@bell.net













































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