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 scenario.
Solutions specified by the HOKEY WG must:
1) Be responsive to handover and re-authentication latency performance objectives within a mobile wireless access network.
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 specification 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 802.21a.
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 server.
8) Assistance to the radext and dime Working Groups in developing AAA support for handoff keying.