E.8 Security information to be stored in the entities of the CTS

3GPP43.020Release 17Security related network functionsTS

This clause gives an overview of the security related information and the places where this information is stored in the CTS.

The entities of the CTS where security information is stored are:

– CTS home location register (CTS-HLR);

– CTS service node (CTS-SN);

– CTS authentication centre (CTS-AuC);

– CTS fixed part equipment (CTS-FPE);

– FP-SIM card;

– CTS mobile equipment (CTS-ME);

– MS-SIM card.

E.8.1 Entities and security information

E.8.1.1 CTS-HLR

The CTS-HLR stores permanently:

– The IFPSI;

– The authentication key Ki_FP.

The CTS-HLR receives and stores (possibly after processing):

– The mobile equipment identity IMEI;

– The IFPEI.

E.8.1.2 CTS-SN

The CTS-SN receives and stores possibly after processing:

– K_OP associated to a given IFPSI;

– Subscription timers;

– RAND value associated to an authentication and key generation procedure;

– SRES the result of the authentication procedure;

– The B5, B6 algorithms.

E.8.1.3 CTS-AuC

In the CTS authentication centre are implemented:

– The authentication algorithm A3;

– The key generation algorithm A8.

E.8.1.4 CTS Fixed Part Equipment (CTS-FPE)

The CTS-FPE stores permanently:

– The encryption algorithm A5/2.

The CTS-FPE generates and stores:

– The CTS authentication key Ka;

– The CTSMSI;

– The ciphering key Kc.

The CTS-FPE receives and stores (possibly after processing):

– The mobile equipment identity IMEI;

– The IMSI.

The CTS-FPE stores for each CTS-MS/CTS-FP pair a record of data which is needed for access on the CTS Radio Interface. The records are stored as a linear fixed file (see 3GPP TS 51.011) and contain:

– The authentication key Ka;

– The CTSMSI;

– The IMSI;

– Other, non security relevant information, which are related to a CTS-MS/CTS-FP pair.

The structure of the linear fixed file is shown in figure E11:

Index (Record Number)	Linear fixed file with one record for each CTS-MS/CTS-FP pair (Read/Write)
1	Ka[1], CTSMSI[1], IMSI[1], other data [1]
2	Ka[2], CTSMSI[2], IMSI[2], other data [2]
.	.
.	.
N	Ka[n], CTSMSI[n], IMSI[n], other data [n]

Figure E11: Storage of CTS-MS/CTS-FP pair related data on the CTS-FPE

The number of records is defined at subscription time and thus determines the number of CTS-FP, a CTS-MS can be enrolled to.

E.8.1.5 Fixed Part SIM card (FP-SIM)

The FP-SIM includes specific information for CTS purpose.

– The IFPSI;

– The Ki_FP;

– The K_OP;

– The list of PLMNs whose subscriber can roam onto the CTS-FP.

E.8.1.6 CTS Mobile Equipment (CTS-ME)

E.8.1.7 Mobile Station SIM card (MS-SIM)

The MS-SIM is a normal GSM SIM card as defined in 3GPP TS 51.011 that includes any information for CTS purpose.

The MS-SIM stores for each CTS-MS/CTS-FP pair a record of data which is needed for access on the CTS Radio Interface. The records are stored as a linear fixed file (see 3GPP TS 51.011) and contain:

– the authentication key Ka;

– the CTSMSI;

– the IFPEI;

– other, non security relevant information, which related to a CTS-MS/CTS-FP pair.

The structure of the linear fixed file is shown in the figure E12

Index (Record Number)	Linear fixed file with one record for each CTS-MS/CTS-FP pair (Read/Write)
1	Ka[1], CTSMSI[1], IFPEI[1], IFPSI[1],other data [1]
2	Ka[2], CTSMSI[2], IFPEI[2], IFPSI[2],other data [2]
.	.
.	.
N	Ka[n], CTSMSI[n], IFPEI[n], IFPSI[n], other data [n]

Figure E12: Storage of CTS-MS/CTS-FP pair related data on the CTS-ME

The number of records is definedby the mobile manufacturer and thus determines the number of CTS-FP, a CTS-MS can enroll onto.