Pre-Authentication Authentication of Management Frames Month Year doc.: IEEE 802.11-06/1655r0 November 2006 Pre-Authentication Authentication of Management Frames Date: 2006-11-12 Authors: Notice: This document has been prepared to assist IEEE 802.11. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures <http:// ieee802.org/guides/bylaws/sb-bylaws.pdf>, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair <stuart.kerry@philips.com> as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at <patcom@ieee.org>. Matthew Gast, Trapeze Networks Matthew Gast, Trapeze Networks

Month Year doc.: IEEE 802.11-06/1655r0 November 2006 Abstract This presentation describes the management frame signature extensions in 11-06/1641. Matthew Gast, Trapeze Networks Matthew Gast, Trapeze Networks

Month Year doc.: IEEE 802.11-06/1655r0 November 2006 Motivation 802.11w-D1.0 only protects management frames post-association Prior to association, some security-relevant tasks occur, mainly network selection Post-association transitions are protected by existing draft and 11k Network selection may use either Probe frames or Action frames Probe Request and Probe Response still used for initial join Action frames may also be used in current TGu draft Network selection is time-critical for emergency calls Matthew Gast, Trapeze Networks Matthew Gast, Trapeze Networks

Month Year doc.: IEEE 802.11-06/1655r0 November 2006 High-Level Approach Provide optional Signature Request and Signature Response information elements Per-Beacon signatures are difficult because they change frequently; restricting them to Probe frames reduces the load Both a pre-shared key and a public/private key pair specified, so there are options for varying environments Not all operations require this level of security; leave choices to client implementations Leverage existing PSK and certificate implementations in supplicants To do 802.11i handshake, either a PSK or certificate must exist Add certificate exchange protocol Matthew Gast, Trapeze Networks Matthew Gast, Trapeze Networks

Month Year doc.: IEEE 802.11-06/1655r0 November 2006 Signature Request IE Included in Probe Request or Action when STA requests a signature by the AP Specifies list of IEs STA wants validated Nonce provides liveness proof of response Can be used to request a particular signing key Matthew Gast, Trapeze Networks Matthew Gast, Trapeze Networks

Month Year doc.: IEEE 802.11-06/1655r0 November 2006 Signature Response IE Confirms signed elements and key used for signing Appears at end of authenticated frame Matthew Gast, Trapeze Networks Matthew Gast, Trapeze Networks

MIC Calculation Protected contents Public/private key Shared Key Month Year doc.: IEEE 802.11-06/1655r0 November 2006 MIC Calculation Protected contents TA, RA, Frame Control (with some masking), Nonce, and IE list Public/private key SHA-1 over protected contents, signed by private key Shared Key HMAC-SHA-1 over protected contents, using shared key as the hash Matthew Gast, Trapeze Networks Matthew Gast, Trapeze Networks

Month Year doc.: IEEE 802.11-06/1655r0 November 2006 Certificate Exchange Rather than passing certificates, protocol uses certificate identifiers CN + serial number + fingerprint Client must obtain certificate before requesting public/private key pair signature Simple transfer procedure using Action frames Note: some external source of trust is required, e.g. CA certificate installation Matthew Gast, Trapeze Networks Matthew Gast, Trapeze Networks

References November 2006 Month Year doc.: IEEE 802.11-06/1655r0 Matthew Gast, Trapeze Networks Matthew Gast, Trapeze Networks