>In WF1 the 802.11 WEP keys would be changed many times each hour, say 
>every 10 minutes. A parameter, P , determines how many time per hour 
>the key is to be changed, where P must divide 3600 evenly. The WEP 
>keys are  derived from a master key, M,  by taking the low order N 
>bits (N = 40, 104, whatever) of the SHA1 hash of the master key with 
>the date and time (UTC) of the key change appended.
>      WEPkey = Bits[0-N](SHA1(M | yyyymmddhhmmss))
>Clearly good synchronization of the time-of-day clock on each node is 
>essential in WF1,  but protocols already exist that can do this over 
>a network. Small synchronization discrepancies can be handled by the 
>802 retry mechanism and should look very much like a short RF outage. 

        i see chicken and egg loop here - for instance, if I've got a laptop
        with 802.11 card only, I need to use the 802.11 network to synchronize
        clock.  i'm not sure if WF1 is workable (if you have other secure
        channel for synchronizing clock, you are okay - but then why bother
        using 802.11?).


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