2.7.2 Handover Keying (hokey)

NOTE: This charter is a snapshot of the 76th IETF Meeting in Hiroshima, Japan. It may now be out-of-date.

Last Modified: 2009-11-24


Glen Zorn <gwz@net-zen.net>
Tina Tsou (Ting ZOU) <tena@huawei.com>

Security Area Director(s):

Tim Polk <tim.polk@nist.gov>
Pasi Eronen <pasi.eronen@nokia.com>

Security Area Advisor:

Tim Polk <tim.polk@nist.gov>

Mailing Lists:

General Discussion: hokey@ietf.org
To Subscribe: https://www.ietf.org/mailman/listinfo/hokey
Archive: http://www.ietf.org/mail-archive/web/hokey/current/maillist.html

Description of Working Group:

A mobile device has to re-authenticate each time it changes its point of
attachment to the network. When it goes through the full procedure of
authentication it creates a series of ruptures, during which the medium
cannot flow. This results in a poor user experience during handover.
However, it is possible to shorten the time it takes to re-authenticate by
reusing the key information developed during the initial authentication.

The Handover Keying Working Group is concerned with developing procedures
for key reuse and delivery, while respecting good security practice. The
Handover Keying Working Group has already done work on this subject, but it
has not yet developed the complete set of procedures, protocols, and changes
needed for different security environment scenarios and situations.

The solutions specified by the HOKEY WG fall into several categories, based
on timing and mechanism. The authentication and key management may occur
before handoff, when latency is much less critical. Alternatively,
authentication and key management can occur as part of the handoff, where
latency is critical. Solutions should reduce or eliminate the number of
referrals to AAA servers, and solutions should avoid re-executing lengthy
EAP method exchanges. This may be accomplished by providing new mechanisms
for cryptographic keying material in combination with a protocol for the
timely delivery of appropriate keys to the appropriate entities. Solutions
are expected to include "handover keying," "low-latency re-authentication,"
and "pre-authentication" or "early authentication".

All solution categories are useful, each supporting different scenarios.
The HOKEY WG may provide multiple solutions, each addressing a different

Solutions specified by the HOKEY WG must:

1) Be responsive to handover and re-authentication latency performance
objectives within a mobile wireless access network.

2) Fulfill the requirements in RFC 4962 and RFC 5247.

3) Be independent of the access-technology. Any key hierarchy topology or
protocol defined must be independent of EAP lower layers. The protocols may
require additional support from the EAP lower layers that use it.

4) Accommodate inter-technology heterogeneous handover and roaming.

5) Not require changes to EAP methods. Any extensions defined to EAP must
not cause changes to existing EAP methods.

In specifying an access-technology-independent solution, media independent
guidelines for SDOs may also be needed to explain how the keying material
and signaling can be employed in a specific access technology.

HOKEY WG Deliverables

1) A specification of Local Domain Name Discovery for ERP. Currently the use
of DHCP mechanisms to request the local domain name is unspecified. There
are other useful scenarios that need to be addressed. Lower layer
announcement for local domain name is unspecified. Ambiguity with using
initial full EAP exchange for re-authentication needs to be clarified.
Additional re-authentication scenarios, for which there is interest, need to
be addressed.

2) A specification of Early Authentication solutions. These include use of
EAP to pre-establish authenticated keying material on a target authenticator
prior to arrival of the peer.

3) A specification for a Hokey architecture Document. It includes deployment
of ERP and EAP early authentication protocol in the mobile environment.
There are various useful scenarios that need to be addressed. This
and the revision of RFC5296 should be conducted in parallel.

4) Assistance to the 802.21a group in specifying the integration of EAP
pre-authentication with IEEE 802.21a. The Hokey Working Group shall perform
tasks that are complementary to and do not duplicate work being done in IEEE

6) A specification for NAS-Authenticator interaction. NAS interaction can be
used to release resources in the old NAS and achieve faster initiation of
authentication. Related work in external SDOs on authenticator/NAS
interaction for re-authentication may be taken into consideration.

7) A revision of RFC 5296 to eliminate unnecessary references to the home

8) Assistance to the radext and dime Working Groups in developing AAA
support for handoff keying.

Goals and Milestones:

Done  First draft on EMSK-based Keying Hierarchy
Done  First draft with a problem statement on EAP re-authentication and key management
Done  First draft on EAP Re-authentication and Handover Keying Hierarchy
Done  First draft on EAP Re-authentication Protocol
Done  First draft on Protocol and Keying Hierarchy for Visited Domain Handovers and Re-authentication
Done  Submit EMSK-based Keying Hierarchy draft to IESG
Done  First draft on Handover Key Distribution Protocol
Done  Submit the problem statement draft to IESG
Done  Submit EAP Re-authentication and Handover Keying Hierarchy draft to IESG
Done  Submit EAP Re-authentication Protocol draft to IESG
Done  First draft on EAP Pre-authentication Specification for inter-technology and inter-domain handoffs
Done  Submit Protocol and Keying Hierarchy for Visited Domain Handovers and Re-authentication draft to IESG
Nov 2009  First draft on Local Domain Name Discovery for ERP
Nov 2009  First draft on Early Authentication solutions
Mar 2010  First draft on Hokey architecture
Mar 2010  First draft on NAS-Authenticator Interaction
Jul 2010  First draft on revision of RFC 5296
Mar 2011  Submit the Local Domain Name Discovery for ERP draft to IESG
Mar 2011  Submit the Early Authentication solutions draft to IESG
Jul 2011  Submit the NAS-Authenticator Interaction draft to IESG
Nov 2011  Submit the Hokey architecture draft to IESG
Nov 2011  Submit the revision of RFC 5296 to IESG
Mar 2012  Re-charter or shut down WG


  • draft-ietf-hokey-key-mgm-13.txt
  • draft-ietf-hokey-preauth-ps-12.txt

    Request For Comments:

    RFC5169 I Handover Key Management and Re-authentication Problem Statement
    RFC5295 PS Specification for the Derivation of Root Keys from an Extended Master Session Key (EMSK)
    RFC5296 PS EAP Extensions for EAP Re-authentication Protocol (ERP)

    Meeting Minutes


    Hokey Architecture
    Local Domain Name Discovery
    ERP extension for EAP Early-authentication protocol (EEP)
    Token based handover key derivation for Re-authentication
    ER architectural exploration