TSG SA WG3 #8,																							S3-99552
	
3G CHANGE REQUEST	Please see embedded help file at the bottom of this
page for instructions on how to fill in this form correctly.	
	
	TS 33.102	CR	27r1	Current Version:	V3.2.0		
					
3G specification number 		 CR number as allocated by 3G support team	
	
For submission to TSG	SA#6	for approval	x	(only one box should	
list TSG meeting no. here 	for information		Be marked with an X)	
	
Form: 3G CR cover sheet, version 1.0        The latest version of this form is available from: ftp://ftp.3gpp.org/Information/3GCRF-xx.rtf	
	
Proposed change affects:	USIM	x	ME	x	UTRAN	X	Core Network	x	
(at least one should be marked with an X)	
	
Source:	S3	Date: 	16-11-99	
	
Subject:	Clarification of re-authentication during PS connections.	
	
3G Work item:	Security	
	
Category: 	F	Correction					
	A	Corresponds to a correction in a 2G specification					
(only one category 	B	Addition of feature					
shall be marked	C	Functional modification of feature	x				
with an X)	D	Editorial modification					
	
Reason for 
change:
	Re-authentication and key setting should be possible during a PS connection so that the cipher and integrity keys can be updated during long connections. This capability is provided in GPRS. The current text in section 6.4.1 is not very clear on whether this should be supported.	
	
Clauses affected:	Section 6.4.1	
	
Other specs	Other 3G core specifications		  List of CRs:		
affected:	Other 2G core specifications		  List of CRs:		
	MS test specifications		  List of CRs:		
	BSS test specifications		  List of CRs:		
	O&M specifications		  List of CRs:		
	
Other 
comments:	Editorial corrections to draft v3.2.0 need to be applied.	

6.4.1	Authentication and cipher key and integrity key setting
Mutual key setting is the procedure that allows the MS and the RNC to agree on the key IK used to compute message authentication codes using algorithm UIA. Key setting is triggered by the authentication procedure and described in 6.3. Authentication and key setting may be initiated by the network as often as the network operator wishes. Key setting can occur as soon as the identity of the mobile subscriber (i.e. TMUI or IMUI) is known by the SN/VLR. The key IK is stored in the SN/VLR and transferred to the RNC when it is needed. The key IK is stored in the USIM until it is updated at the next authentication. 
If an authentication procedure is performed during a data transfer in the PS mode, the new cipher key CK and integrity key IK shall be taken in use in both the RNC and the UE as part of the security mode negotiation (see 6.4.5) that follows the authentication procedure.