Handover mechanisms in next generation heterogeneous wireless ...

PROXY BASED AUTHENTICATION LOCALISATION SCHEME FOR HANDOVER
Figure 6.1 A trust model for security analysis of handover
The security of 3G UMTS has been developed to keep maximum compatibility with the
current GSM security architecture. Mutual authentication is achieved by showing
knowledge of a security key K shared between a mobile user and the Authentication
Centre (AuC) in its home network. Using the Authentication and Key Agreement (AKA)
protocol [93], the AuC generates and transfers a set of security credentials, known as
Authentication Vector (AV) of a mobile user to a visited network. With the AV, the
visited network performs mutual authentication with the mobile user as described in Sec.
3.2.2.
In IEEE 802.11, a new standard IEEE 802.11i [42] has been developed to strength its
security. IEEE 802.11i enhances key management and encryption algorithms by
incorporating IEEE 802.1X [47], a port-based network control mechanism. IEEE
802.1X employs the challenge-response Extensible Authentication Protocol (EAP) [18]
to provide a variety of authentication mechanisms. The security mechanisms
implemented within different wireless networks are limited to their particular
architectures.
To integrate WLAN with 3GPP network, 3rd Generation Partnership Project (3GPP)
has defined two new mechanisms in TS 33.234 [75]: Extensible Authentication Protocol
Method for 3rd Generation Authentication and Key Agreement (EAP-AKA) and
Extensible Authentication Protocol Method for GSM Subscriber Identity (EAP-SIM).
The full authentication methods defined in these protocols need at lease three round
trips with home AAA server and AuC. Thus, a lightweight process, the EAP-AKA fast
re-authentication method has been proposed. It re-uses keys generated from the previous
authentication process to save processing time. However, with the fast re-authentication,
at lease, two round trips are still needed to authenticate and authorise the mobile user
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