Encryption is enabled by the exchange of {TAIL ~ at least one key} and the generation of additional keys by {HEAD ~ the access point} and the mobile computing unit to make the communications secure 
Encryption is enabled by the exchange of { TAIL ~ at least one key } and the generation of additional keys by { HEAD ~ the access point } and the mobile computing unit to make the communications secure
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH