TSG SA WG3 #8,																							S3-99415
	
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 33.103	CR	?	Current Version:	V3.0.0		
					
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:	Change length of KSI, removal of SQN from AV, correction of AUTN and AV length and correction of group identity terminology	
	
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.	
	
Clauses affected:	Sections 4.2.1, 4.2.2, 4.5.2	
	
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:		

4.2.1	Enhanced User Identity Confidentiality (EUIFUSIM)
For UMTS users with EUIC, the USIM has to store additional data and have additional functions implemented to encrypt the permanent user identity (IMSI). We describe the requirements as regards data storage and algorithm implementation for an example mechanism in annex B of 3G TS 33.102.
The following data elements need to be stored on the USIM:
a)	SQNUIC/MS: a counter that is equal to the highest SQNUIC generated and sent by the USIM to the HE/AuC;
b)	GK: the group key used to encrypt the IMSI, SQNUIC and the SQNMS ;
Table 1: USIM – Enhanced User Identity Confidentiality – Data elements
Symbol	Description	Multiplicity	Lifetime	Length	Mandatory / Optional	
GK	Group key	1 per user group the user belongs to	Permanent	128 bits	Optional	
SQNUIC/MS	Counter 	1 per user	Updated when protocol for EUIC is executed	32 bits	Optional	
GI	Group Identity	1 per user	Permanent	32 bits	Optional	

The following cryptographic functions need to be implemented in the HLR/AuC:
•	f6:	the user identity encryption function.	
For a summary of the data elements and cryptographic function of the EUICHE function see Table 2.
Table 2: HLR/AuC – Enhanced User Identity Confidentiality – Cryptographic functions
Symbol	Description	Multiplicity	Lifetime	Standardised / Proprietary	Mandatory / Optional	
f6	User identity encryption function	1 	Permanent	Proprietary	Optional 	

4.2.2	Authentication and key agreement (AKAUSIM)
The USIM shall support the UMTS mechanism for authentication and key agreement described in 6.3 of 3G TS 33.102. 
The following data elements need to be stored on the USIM:
a)	K: a permanent secret key; 
b)	SQNMS: a counter that is equal to the highest sequence number SQN in an AUTN parameter accepted by the user. 
c)	For the WINDOW option: an array of Boolean values over the interval [SQNMS - w, SQNMS), that indicate whether the USIM has accepted a certain sequence number in an AUTN parameter.
d)	For the LIST option: an ordered list of the highest values that the USIM has received    
e)	RANDMS: the random challenge which was received together with the last AUTN parameter accepted by the user. It is used to calculate the re-synchronisation message together with the highest accepted sequence number (SQNMS). 
f)	KSI: key set identifier.
g)	THRESHOLDC: a threshold defined by the HE to trigger re-authentication and to control the cipher key lifetime;
h)	CK The access link  cipher key established as part of  authentication
i)	IK  The access link  integrity key established as part of  authentication
j)	HFNMS: Stored Hyper Frame Number provides the Initialisation value for most significant part of COUNT-C and  COUNT-I. The least significant part is obtained from the RRC sequence number. 
k)	AMF:  A 16-bit field used Authentication Management. The use and format are unspecified in the architecture but examples are given in an informative annex. 
l)	The GSM authentication parameter and GSM cipher key derived from the UMTS to GSM conversion functions 
Table 3 provides an overview of the data elements stored on the USIM to support authentication and key agreement.
Table 3: USIM – Authentication and key agreement – Data elements
Symbol	Description	Multiplicity	Lifetime	Length	Mandatory / Optional	
K	Permanent secret key	1 	Permanent	128 bits	Mandatory	
SQNMS	Sequence number counter	1 	Updated when AKA protocol is executed	32-64 bits 	Mandatory	
WINDOW (option 1)	accepted sequence number array	1	Updated when AKA protocol is executed	10 to 100 bits	Optional	
LIST
(option 2)	Ordered list of sequence numbers received	1	Updated when AKA protocol is executed	32-64 bits 	Optional	
RANDMS	Random challenge received by the user.	1	Updated when AKA protocol is executed	128 bits	Mandatory	
KSI	Key set identifier 	1 	Updated when AKA protocol is executed	3 bits	Mandatory	
THRESHOLDC	Threshold value for ciphering	1 	Permanent	32 bits	Optional	
CK	Cipher key	1	Updated when AKA protocol is executed	128 bits	Mandatory	
IK	Integrity key	1	Updated when AKA protocol is executed	128 bits	Mandatory	
HFNMS:	Initialisation value for most significant part for COUNT-C and  for COUNT-I	1 	Updated when connection is released 	25 bits	Mandatory	
AMF	Authentication Management Field (indicates the algorithm and key in use) 	1	Updated when AKA protocol is executed	16 bits	Mandatory	
RANDG	GSM authentication parameter from conversion function	1	Updated when GSM AKA or UMTS AKA protocol is executed	As for GSM	Optional	
SRES	GSM authentication parameter from conversion function	1	Updated when GSM AKA or UMTS AKA protocol is executed	As for GSM	Optional	
Kc	GSM cipher Key	1	Updated when GSM AKA or UMTS AKA protocol is executed	As for GSM	Optional	

4.5.2	Authentication and key agreement ( AKASN)
The VLR (equivalently the SGSN) shall support the UMTS mechanism for authentication and key agreement described in 6.3 of 3G TS 33.102. 
The following data elements need to be stored in the VLR (and SGSN):
a)	AV:	Authentication vectors;
Table 16 provides an overview of the composition of an authentication vector
Table 16: Composition of an authentication vector
Symbol	Description	Multiplicity	Length	
				
RAND	Network challenge	1	128	
XRES	Expected response	1	32-128	
CK	Cipher key	1	128	
IK	Integrity key	1	128	
AUTN	Authentication token	1 that consists of:	112-144	
SQN
or  
SQN  AK	Sequence number
or
Concealed sequence number	1 per AUTN	32-64	
AMF	Authentication Management Field 	1 per AUTN	16	
  MAC-A	Message authentication code for network authentication	1 per AUTN	64	

b)	KSI:	Key set identifier; 
c)	CK:	Cipher key;
d)	IK:	Integrity key.
e)	GSM AV: Authentication vectors for GSM 
Table 17 provides an overview of the data elements stored in the VLR/SGSN to support authentication and key agreement. 
Table 17: VLR/SGSN – Authentication and key agreement – Data elements
Symbol	Description	Multiplicity	Lifetime	Length	Mandatory / Optional	
UMTS AV	UMTS Authentication vectors	several per user, SN dependent	Depends on many things	528-656	Mandatory	
KSI	Key set identifier 	1 per user	Updated when AKA protocol is executed	3 bits	Mandatory	
CK	Cipher key	1 per user	Updated when AKA protocol is executed	128 bits	Mandatory	
IK	Integrity key	1 per user	Updated when AKA protocol is executed	128 bits	Mandatory	
GSM AV	GSM Authentication vectors	As for GSM	As for GSM	As for GSM	Optional