#7825 NORM 8.2.0 (: can't complete WPA handshake with D-Link WBR-2310

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Tue Sep 9 15:40:29 EDT 2008

#7825: can't complete WPA handshake with D-Link WBR-2310
   Reporter:  dsd        |       Owner:  jcardona            
       Type:  defect     |      Status:  new                 
   Priority:  normal     |   Milestone:  8.2.0 (was Update.2)
  Component:  wireless   |     Version:  not specified       
 Resolution:             |    Keywords:  8.2.0:? relnote     
Next_action:  never set  |    Verified:  0                   
  Blockedby:             |    Blocking:                      

Comment(by jcardona):

 Replying to [comment:5 dsd]:
 > My theory is that we are actually hitting a flaw in WPA combined with
 some slowness of the XO (slow processor, fullmac wifi hardware) and this
 AP being particularly fast.
 > (...)
 > My theory is that the XO then receives the message in (6) but has not
 had time to install the PTK, so decryption fails, and it throws the
 message away. I do not have a way to verify this though, any ideas?

 I could finally consistently capture the 5th EAPOL, the one with the group
 key.  The EAPOL-GTK is acknowledged by the station (802.11 ack) but no
 EAPOL response is sent to complete the two-way GTK handshake.  So it looks
 like your hypothesis is dead on.

 > The reason that this happens on this AP and not others is that this AP
 is particularly fast.
 > It takes just 1.83ms to respond to the 4th EAPOL (by sending the first
 GTK EAPOL), whereas
 > other AP's I have looked at take over 3ms.

 I confirmed that as well.  In my captures the time between the 4th and 5th
 EAPOL is between 1.8 and 2.0 ms.  On a Linksys WRT310N, this time is ~13
 ms, and the WPA handshake is successful.

Ticket URL: <http://dev.laptop.org/ticket/7825#comment:17>
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