3GPP WLAN Interworking Security Issues May 2003 doc.: IEEE 802.11-03/229r1 May 2004 3GPP WLAN Interworking Security Issues Andrew Myers British Telecommunications (WIEN-SG) 13th May 2004 Andrew Myers, BT Tan Pek-Yew, Matsushita Electric Ind.

May 2004 Introduction At the March 2004 meeting in Orlando it was suggested that specific issues were brought up for consideration, discussion and development appropriate to the WIEN-SC to ensure interoperability with the 3GPP specification from a security perspective. These fall into 3 Categories The provision of guidance to implementing the IEEE 802.11 standard. Consideration for enhancements to the 802.11 specification. Creation of liaison statements to be sent to 3GPP requesting enhancements or clarification of the 3GPP WLAN inter-working specification where necessary. Andrew Myers, BT

May 2004 802.11i Keying Material The 3GPP specification states that it shall provide the keying material as required by the IEEE 802.11i WLAN specification. 3GPP are unsure of IEEE 802.11’s detailed requirements for this material in terms of the requested bit length and entropy. Can the IEEE 802.11 WIEN-SC provide this information for 3GPP? Background information can be found in the Liaison Statement LS (S3-030166) http://www.3gpp.org/ftp/tsg_sa/WG3_Security/2003_meetings/TSGS3_27_Sophia_Antipolis/Docs/ZIP/ Andrew Myers, BT

May 2004 Simultaneous Access 3GPP’s definition of simultaneous access is ambiguous. Is the IEEE 802.11’s WIEN SG able to provide a definition of WLAN simultaneous access? This definition is still TBA within 3GPP Background to current thinking within 3GPP on WLAN simultaneous access can be found in a liaison statement, S3-030169 and the associated reply S3-030188 on the 3GPP web server [http://www.3gpp.org] http://www.3gpp.org/ftp/tsg_sa/WG3_Security/2003_meetings/TSGS3_27_Sophia_Antipolis/Docs/PDF/ http://www.3gpp.org/ftp/tsg_sa/WG3_Security/2003_meetings/TSGS3_28_Berlin/Docs/ZIP/ Andrew Myers, BT

May 2004 Access Control Access Control related functionality in the network elements of the 3GPP-WLAN interworking reference model provides a number of alternative capabilities or possible configurations. The alternative capabilities I.e. CAPWAP, may need to be examined in context of the combination of 3GPP and IEEE 802.11’s capabilities and an analysis made of the interoperability issues from a security perspective. Andrew Myers, BT

Wa Interface Protection May 2004 Wa Interface Protection Threats on the Wa interface are not clear yet within 3GPP. 3GPP Wa Definition: The Wa reference point connects the IEEE 802.11 WLAN Access Network, possibly via intermediate networks, to the 3GPP Network (i.e. the 3GPP AAA Proxy in the roaming case and the 3GPP AAA server in the non-roaming case). The prime purpose of the protocols crossing this reference point is to transport authentication, authorization and charging-related information in a secure manner. The reference point has also to accommodate legacy IEEE 802.11 WLAN Access Networks. Background information can be found in slides IEEE 802.11-04/0408r2 A proposal is for the IEEE 802.11 WIEN-SG to conduct a threat analysis on the Wa interface from IEEE 802.11’s perspective. Andrew Myers, BT

May 2004 Link Layer Security 3GPP do not specify any level of link layer security and permit interoperability to WEP, WPA and 802.11i networks indiscriminately. However, these technologies do not provide any indication of security to the user. Additionally, no decisions are made from a 3GPP network perspective on the behaviour of the accessed network in terms of the link layer security in place I.e. a WLAN Access Network is treated as a black box into which 3GPP pass the keys required for link layer encryption. Can IEEE 802.11 WIEN-SG provide a view on: Whether there is a need for indicating a security level to the user The possible impacts of “support vs non-support” of a security indicator within a device when requested by a 3GPP network E.g. the 3GPP network may refuse connection based on this information. Andrew Myers, BT

May 2004 Conclusion These slides have proposed a number of topic areas that are of interest to 3GPP and hopefully to the IEEE 802.11 WIEN-SG. It is now WIEN-SG’s call whether to make the decision to take none, some or all of these issues and how to address them. Andrew Myers, BT