TSG SA WG3 #8,																							S3-99389
	
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	025	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		Core Network	x	
(at least one should be marked with an X)	
	
Source:	Vodafone	Date: 	16-11-99	
	
Subject:	Refinement of key set identifier (KSI) specification to reach alignment with CKSN.	
	
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:
	The length of KSI is changed to reach alignment with CKSN in GSM. In addition, it is specified that KSI can have seven values with ‘111’ being used by the mobile station to indicate that a valid key set is not available for use. 	
	
Clauses affected:	Section 6.4.4.	
	
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:		

6.4.4	Cipher key and integrity key identification
The key set identifier (KSI) is a number which is associated with the cipher and integrity keys derived during authentication. The key set identifier is allocated by the network and sent with the authentication request message to the mobile station where it is stored together with the calculated cipher key CK and integrity key IK..
The purpose of the key set identifier is to make it possible for the network to identify the cipher key CK and integrity key IK which is stored in the mobile station without invoking the authentication procedure. This is used to allow re-use of the cipher key CK and integrity key IK during subsequent connections. 
The key set identifier is three bits. Seven values are used to identify the key set. A value of ‘111’ is used by the mobile station to indicate that a valid key set is not available for use. The value of ‘111’ in the other direction from network to mobile station is reserved.