TSG-Terminals Working Group 3 (USIM) #8	TdocT3-99245
Bonn 23rd – 27th Aug., 1999	

Title:	Proposal and Discussion of USIM security features

Source:	NTT DoCoMo 

Status:	Proposal and Discussion
_________________________________________________________________________

1.	Introduction
This document proposes USIM security features, as a result of another documents. (Refer to T3-99238, 239, 33.102, 33.103, and 33.105) 

2.	List of USIM security feature items
The USIM security feature items listed in Table 1.

Table 1. List of USIM security feature items
Item No.	Key Word	EF / Function	M/O	New / Modify	UST Indicate	Remarks	
1	EFLOCI	EF	M	Modify	Yes		
2	EFLOCIO	EF	M	New	Yes		
3	EFPSLOCI	EF	M	Modify EFGPRSLOCI	Yes		
4	EFPSLOCIO	EF	M	New	Yes		
5	EFGI	EF	O	New	Yes		
6	GK	stored secretly	O	New	No		
7	SEQ_UIC	function and stored secretly	O	New	No	Use for EMUI Compute.	
8	EMUI Computation	function	O	New	No		
9	EFRAND ?	EF	M/O	New	No	Use for Re-sync.	
10	SQNMS/CS	stored secretly	M/O	New	No	Use for Re-sync.	
11	SQNMS/PS	stored secretly	M/O	New	No	Use for Re-sync.	
12	Authentication	function	M	Modify	No		
13	Re-sync.	function	M/O	New	No	Include to Authentication	
14	EFCK	EF	M	Modify	Yes		
15	EFCKPS	EF	M?	Modify	Yes		
16	EFLIFE	EF	M?	New	Yes		
17	EFUSECK	EF	M?	New	Yes		
18	EFUSEIK	EF	M?	New	Yes		
19	EFUSECKPS	EF	M?	New	Yes		
20	EFUSEIKPS	EF	M?	New	Yes		
21							

3.	Proposal and Discussion
3.1.	User identity confidentiality
3.1.1.	Temporary User Identity
Two types temporary user identity stored in USIM. One is a “Registered User New Temporary Identity”, another one is a “Registered User Old Temporary Identity”. Therefore we propose new EF (EFLOCIO) that is stored “Registered User Old Temporary Identity”. EFLOCIO structure is similar to EFLOCI.
The “Registered User New Temporary Identity” is a component of EFLOCI. 

3.1.1.1.	EFLOCIO (Old Location Information)
This EF contains the following Location Information:
‑	Old Temporary Mobile Subscriber Identity (TMSI)
‑	Location Area Information (LAI)

‑	Location update status
Identifier: '6Fxx'	Structure: transparent	Mandatory	
File size: 11 bytes	Update activity: high	
Access Conditions:
	READ	CHV1
	UPDATE	CHV1
	INVALIDATE	ADM
	REHABILITATE	CHV1
	
Bytes	Description	M/O	Length	
1 ‑ 4	TMSI_O	M	4 bytes	
5 ‑ 9	LAI	M	5 bytes	
10	RFU	M	1 byte	
11	Location update status	M	1 byte	

For contents and coding see EFLOCI.

Note: parameter length and contents are further study.

3.1.2.	Identification by a Permanent Identity
It has two types indication. One is a clear-text IMUI. Another one is encrypt IMUI. Encrypt IMUI (EMUI) is new feature for 3G system and optional. Therefor EMUI procedure describes below.

3.1.2.1.	EMUI
According to Tdoc-99238, it is need some new parameter and function in USIM for EMUI computation. These are GK, GI and SEQ_UIC. The EMUI computation input data is IMUI. And output data is EMUI. The function of EMUI is f6(GK; SEQ_UIC, IMUI). GK is stored in USIM secretly. SEQ_UIC is generated by USIM and different each time. If the SEQ_UIC stored in USIM then stored secretly.

Summary of EMUI shows below.

Input: IMUI
Output: EMUI.
USIM stored (secretly): GK, SEQ_UIC
USIM stored (EF): GI 

Note: complite proposal is T.B.D.

3.2.	User authentication
According to Tdoc-99238, it is need some new parameter and function in USIM for user authentication. But is mutual authentication mandatory? Is the integrity key mandatory?

This feature has re-synchronisation procedure when SQN comparison failed. But this comparison and condition branch should be internal function of USIM.
 
The authentication command need a parameter are RAND, RANDMS, AUTN and SQNMS. The authentication command input data is RAND and AUTN. And output data is RES, CK and IK when mutual authentication is successful. Or RANDMS and AUTS when need a re-synchronisation.
Input and output data coding scheme is using a TLV coding.

Summary of user authentication shows below.

Input: RAND, AUTN  (AUTN is optional?)
Output (successful): RES, CK, IK  (IK is optional?)
Output (re-sync.): RANDMS, AUTS  (This case is optional?)
USIM stored (secretly): K, SQNMS (SQNMSCS, SQNMSPS or others)  (The SQN is optional?)

Note: complete proposal is T.B.D.

3.3.	Message authentication of signalling information sent to/from MS
The message authentication of signalling information function implement to ME. The USIM function is only generate an integrity key (IK). The IK generate during user authentication procedure and stored in USIM. The USIM need an EFIK and may be EFIKPS.

Note: this function is mandatory or optional? T.B.D

3.4.	USIM application security
3.4.1.	User-to-USIM authentication
This feature described as cardholder verification in “UICC physical and logical characteristics (31.101)”.

3.4.2.	USIM-Terminal Link
This feature described in “Personalisation of GSM ME (02.22)”. We think that this specification is necessary transfer for 3GPP.
When the personalisation applied, then the USIM should have an appropriate files and functions.