TSG-SA  Working Group 3 meeting #8		Tdoc S3-99393
Sophia Antipolis, France, 16-19 November 1999

To:	R3, N1
CC:	R2
Source: 	S3 
Title: 	Answer on liaison statement on Security Mode Control 
	procedure

S3 is pleased to provide the following comments to the proposed liason statement ( TSGR3#7(99)D49 = S3-99436) from R3. At the same time we believe the infrmation contained herein will cover the issues raised by N1 in their LS (Tdoc N1-99D06 = S3-99434).

1.	We confirm that the Security Mode Control procedure described is in line with  S3 requirements.

2.	The verification of the UE classmark is feasible. We refer to our CR30  to TS 33.102 (Tdoc S3-99409 Handling of UEA and UIA capability information, attached) where the procedure is described.

3.	Reauthentication is discussed in S3 but no firm decision has been made. S3 feels that it is still an open question if it is technically feasible (during ongoing traffic and without service disruption) and would like to receive information on the feasabilty of the feature.

4.	The selection of the algorithms can be made by the RNC. The CR30 to TS 33.102 removes the requirement for the CN to handle the MS UEA and UIA capability information.