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WPA Coordination Changes

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Presentation on theme: "WPA Coordination Changes"— Presentation transcript:

1 WPA Coordination Changes
May 2003 doc.: IEEE /310r0A May 2003 WPA Coordination Changes Changes incorporated in versions 1.4 to 1.8 of the WPA specification. Making similar changes to TGi would keep us aligned. Mike Moreton, Synad Technologies Mike Moreton, Synad Technologies

2 TKIP TSC Initialisation
May 2003 doc.: IEEE /310r0A May 2003 TKIP TSC Initialisation TSCs start at zero. What do replay counters start at if they are always one less than the next expected TSC and are unsigned? It was decided to initialise TSCs to one instead. Mike Moreton, Synad Technologies Mike Moreton, Synad Technologies

3 May 2003 Request Bit Michael MIC failure messages have the Request bit set, but are not actually requesting a rekey (though the recipient is free to do one if it wishes). Need to make this clear in the text. Mike Moreton, Synad Technologies

4 Michael Countermeasures Cleanups
May 2003 Michael Countermeasures Cleanups Removal of remaining references that indicate a STA should view a received disassociation frame with cause “Michael MIC failure” as if it was itself a MIC failure. As the disassociation frame is not MICed this opened an easy DOS attack. Clarification that the countermeasures only apply to TKIP (not AES) communications, and that they apply to all TKIP communications, not just with the current AP. Mike Moreton, Synad Technologies

5 No Key Causes Disassociation
May 2003 No Key Causes Disassociation STA must disassociate if it receives an encrypted unicast frame when it doesn’t have a key. This may be the case when the STA receives the first frame of the group key handshake. If the AP is faster to respond than the supplicant. The fix is to allow the STA to drop such a frame rather than disassociating. Mike Moreton, Synad Technologies

6 May 2003 TKIP TSC Order In draft 3.0 the example code placed TSC0 and TSC1 in the frame in the opposite order to which the normative text specified. Most implementations were based on the reference code. WPA has decided to go with the majority. It will make life easier for everyone if we use the same order as WPA. Mike Moreton, Synad Technologies

7 Pass Phrase Clarification
May 2003 Pass Phrase Clarification The definition of which characters are acceptable in a pass phrase does not include space. Mike Moreton, Synad Technologies


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