A Communication Protocol of RFID Systems in Internet of Things

……
……
International Journal of Security and Its Applications
Vol. 6, No. 2, April, 2012
Certification Stage
(1)Initialization: save H( EPCR i
) in the reader i , save H( EPCR 1
) H( EPC
R 2
) ......
H( EPCR
) and E
N
K
( EPC
1 T
), E (
2 T
)...... (
T
)
j j K
EPC E
j j K
EPC in tag j as shown in Fig 2. And make
Nj j
sure H( EPCR
) and E ( ),
1
K
EPC
1 j T
H( EPC )
j
R
and E ( )
2
K
EPC
2 j T
...... H( EPC )
j
R N
and EK Nj
( EPCT
j
) put
into a one-to-one relationship. The key K1j , K2j......
KNj
with corresponding
E ( ),
K
EPC
1 j T
E ( )
j K
EPC
2 j T
...... E (
j
K Nj
EPCT
j
) between all the readers and tag j saved in the
RFID middleware database just as shown in Fig 3, and make sure K and EK
( EPC
1 T
),
K2 j
and E ( EPC ) ...... K
Nj
and E ( EPCT
) put into a one-to-one relationship.
K2 j Tj
K Nj j
1 j
j
j
H( EPC
R 1
) EK
( EPC
1 T
)
j
j
H( EPC
R 2
) EK
( EPC
2 T
)
j
j
E ( EPC )
K1 j Tj
E ( EPC )
K2 j Tj
K
1 j
K
2 j
……
……
H( EPC ) E ( EPC
T
)
RN
K Nj j
E ( EPC )
K Nj T j
K
Nj
Figure 2. Tag j initialized
Figure 3. Database Initialized
(2)Reader i generates a random number r by random number generator Rand( x),
generate an authentication request through the XOR H( EPC ) r t , sent rt , to the tag.
(3)When receive certification request, tag j will search the
Ri
R i
R i
then
H( EPC ) to satisfy
H( EPC r)
equal to the received t . If not found, authentication fails and the tag stops
responding. Otherwise, continue to perform the following steps to find
E ( EPC ), which is
K ij T j
one-to-one with reader EPC
R i
. Then hashes a H( EK ij
( EPCT
j
) r)
and send a to the reader.
(4)When the reader receives tag response, sent a and random number r generated first to
the RFID middleware.
(5) After receiving a , RFID middleware will search the EK ij
( EPC
T j
) to satisfy
H( E ( EPC ) r)
a . If it is found, certification is completed. Then continue to perform the
K ij T j
following steps, search
K ,which is one-to-one with E ( EPC ).Otherwise, responding stops
ij
K ij T j
to conduct DK
( E (
T
))
ij K
EPC EPC
ij j T
symmetric decryption to obtain EPC
j
T j
.After that, search
the Info( EPC
T
) with EPC
j
T j
through the information service system of Internet of Things, and
sent it to reader. If the tag needs to update the keys and transfer the ownership, continue do
the following steps.
Key Update Phase
(1) RFID middleware databases generate a new key
function, then encrypt
K ij T j
T j
K H( K r)
, by using Hash
EPC with the key to generate new E ' ( EPC T
) , then XOR
E ( EPC ) and E ' ( EPC T
) , that is e E ( EPCT
) E ( EPC
' T
) ,then Hash function of
K ij
j
'
ij
Kij j K ij
j
ij
K ij
j
96