Handover mechanisms in next generation heterogeneous wireless ...

PROXY BASED AUTHENTICATION LOCALISATION SCHEME FOR HANDOVER
where f is a message authentication function that is only known to the MH and its
HAAA. The HAAA encrypts the FAT contents as listed in Equation 6.1 using the secret
key K hp shared with the corresponding FAP. After every AN on the neighbour access
network list has been produced a FAT, the HAAA builds up an encrypted FAT Vector
(FATV):
EK hm
( FATV[
FAT , IDp1,
FAT2
, IDp
2 ,..., FATt
, ID
1 pt
which includes every FAT and the corresponding FAP’s identity ID p . The FATV is
protected by the key K hm shared between the MH and its HAAA. Then, the encrypted
FATV is included in a FAT Response message, and sent back to the MH as shown in
Figure 6.4. The encryption using the PSK K hm makes sure that the FATV would not be
disclosed to other parties (including the sAN), and only the MH can view it. Although
the MH can decrypt the encrypted FATV, it is unable to learn the contents of individual
FAP. Each FAT is encrypted with a key ( K hp ) that is only known to the HAAA and the
FAP that it is generated for. Neither the MH nor the sAN can modify the received
FAT’s contents. Once the FAT response is received, the MH increments its SQN m
counter by 1.
MH sAN
HAAA
FAT Request
EK hm
FAT Response
FATV [ FAT , ID , FAT , ID
Initial full authentication via sAN
( Nm
)
EK hm
- 122 -
( Nm
) ,
])
FAT Request
NAN ,...,
�AN , AN AN �
_ IDs
1 2
FAT Response
FATV [ FAT , ID , FAT , ID
, ..., FAT , ID
EK ( hm
1 p1
2 p2
t p3
, ..., FAT , ID
EK ( h
1 p1
2 p2
t p3
Figure 6.4 Fast authentication ticket generation procedure
The consequence of the fast authentication ticket generation is that a FAT will be
produced for every nearby access network before a handover execution. Note that only
])
t
])