System for updating an encrypted key, by means of which the WEP of IEEE 802.11
can be applied to a wireless LAN system having plural APs and a large number of
STAs. A key management server is LAN-connected to the APs. A set of plural (k)
encrypted keys used for wireless communication between the entire APs and STAs
is provided and managed monistically. If an encrypted key is updated in the key
management server, the updated key is delivered to each of the APs and the STAs.