Compaq WL110, User Manual

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Security 7-17
Single Key – No Transition
Table 7-1 shows a system, where at each point in time only one single key is
used. The key to be used is dictated by the AP settings, showing only one valid
key at each period. This requires a change over of keys at all stations more or
less synchronous with the Access Point configuration changes. This is not
practical and hence there are four keys.
Table 7-1 Single Key - No Transition
By initially configuring all stations with the keys for the first 4 periods, only the
Txkey index needs to be changed at all stations for the first three steps. At the
step from period 3 to period 4, the keys have to be changed at all STAs as well.
Single Key – Transition Period
To introduce a transition period between the main life of the successive keys, the
scheme has to be changed as shown in Tabl e7-2.
Table 7-2 Single Key - Transition Period
Period AP Configuration Out-
ward
STA Configuration(s) In-
ward
# Description Keys 1-2-3-
4 Tx Key Keys 1-2-3-4 Tx Key
0 Main life key A A-0-0-0 1 A A-B-C-D 1 A
1 Main life key B 0-B-0-0 2 B = 2 B
2 Main life key C 0-0-C-0 3 C = 3 C
3 Main life key
D 0-0-0-D 4 D = 4 D
4 Main life key E E-0-0-0 1 E E-F-G-H 1 E
5 Main life key F 0-F-0-0 2 F = 2 F
Period AP Configuration Out-
ward STA
Configuration(s) In-ward
# Description Keys 1-2-3-4 Tx Key Keys 1-2-3-4 Tx Key
0 Main life key A A-0-0-0 1 A A-B-C-D 1 A
1 Transition A-B A-B-0-0 2 B = 1|2 A | B
2 Main life key B 0-B-0-0 2 B = 2 B
3 Transition B-C 0-B-C-0 3 C = 2|3 B | C
4 Main life key C 0-0-C-0 3 C = 3 C
5 Transition C-D 0-0-C-D 4 D = 3|4 C | D
6 Main life key D 0-0-0-D 4 D = 4 D
7 Transition D-E E-0-0-D 1 E A-B-C-D
E-F-G-H 4
1 D
E
8 Main life key E E-0-0-0 1 E E-F-G-H 1 E
9 Transition E-F E-F-0-0 2 F = 1|2 E | F