Authentication server of a cellular telecommunication network and corresponding UICC
The invention proposes an authentication server of a cellular telecommunication network, the authentication server being arranged for generating an authentication token to be transmitted to a telecommunication terminal, the authentication token comprising a message authentication code and a sequence number, wherein the message authentication code is equal to: MAC x =KId x XOR f 1(AMF,SQN x ,RAND, K ) with KIdx being a key index information in the form of a bias of a MAC equal to: MAC= f 1( K ,AMF,SQN x ,RAND) with f1 being a function, K a key, RAND a random number and SQNx a sequence counter relative to a corresponding key Kx derived from the key K and KIdx, and AMF the content of an authentication management field as defined in 3GPP TS 33.102.
1. An authentication server device of a cellular telecommunication network comprising:
a memory that stores a Key K,
wherein said authentication server generates an authentication token and transmits the authentication token to a telecommunication terminal, said authentication token comprising a message authentication code and a sequence number, wherein said message authentication code is equal to:
MAC x =KId x XOR f 1(AMF,SQN x ,RAND, K )
with KIdx being a key index information in the form of a bias of a MAC equal to:
MAC= f 1( K ,AMF,SQN x ,RAND)
with f1 being a function, the key K, RAND a random number and SQNx a sequence counter relative to a corresponding key Kx derived from the key K and KIdx, and AMF the content of an authentication management field as defined in 3GPP TS 33.102.
2. The authentication server device according to claim 1 , wherein said authentication server computes an authentication vector and transmits the authentication vector to said telecommunication terminal, said authentication vector being equal to:
AV x =RAND∥XRES x ∥CK x ∥IK x AUTN x
With: XRES x=f 2(RAND, Kx )
CK x=f 3(RAND, Kx )
AUTN x =SQN x XOR AK∥AMF∥MAC x
AK= f 5(RAND, K )
with ∥ being a concatenation, and f2, f3 and f5 being algorithms.
3. The authentication server according to claim 1 , wherein said authentication server is an Isolated Operation for Public Safety (IOPS) authentication server.
4. A Universal Integrated Circuit Card (UICC) comprising:
a memory that stores a Universal Subscriber Identity Module (USIM) application, said USIM application being configured to receive from a telecommunication terminal, with which it cooperates, a message
AUTN x II RAND
with RAND a random number and AUTNx being equal to:
AUTN x =SQN x XOR AK∥AMF∥MAC x
with AK=f5(RAND,K)
and MACx being equal to:
MAC x =KId x XOR f 1(AMF,SQN x ,RAND, K )
with KIdx being a key index information in the form of a bias of a MAC equal to:
MAC= f 1( K ,AMF,SQN x ,RAND)
with f1 and f5 being functions, K a key, SQNx a sequence counter relative to a corresponding key Kx derived from the key K and KIdx, and AMF the content of an authentication management field as defined in 3GPP TS 33.102,
said application computing a value
XMAC= f 1(AMF,SQN x ,RAND, K )
and a Key Index
KId=XMAC XOR MAC x
said application verifying that the computed KId matches one of the KIds in a stored white list and, if the match is positive, computing the corresponding key Kx based on the KIdx and computing said key AK, SQNx and
RES x=f 2( Kx ,RAND)
CK x=f 3( Kx ,RAND)
IK x=f 4( Kx ,RAND)
with ∥ being a concatenation and f2, f3 and f4 being algorithms, and sending RESx, CKx and IKx to said telecommunication terminal.