The more powerful encryption
requires hardware acceleration, and is not supported by older WLAN equipment. The
802.11 standard now defines multiple alternative security arrangements for WLANs. For
the sake of simplicity we use the terminology of the Wi-Fi Alliance to group the various
alternatives, presented in Table 2.2.
Table 2.2: Encryption Methods in 802.11 WLANs.
Wi-Fi
name Authentication Key distribution Encryption Algorithm
(none) open none none none
WEP open or shared key (WEP) out of band WEP RC4
WPA ??“
Personal
open, followed by shared secret = PSK out of band (PSK=PMK) TKIP RC4
WPA ??“
Enterprise
open, followed by 802.1x, in which
shared secret = certificate or other token
PMK from Authentication
Server
TKIP RC4
WPA2 ??“
Personal
open, followed by shared secret = PSK out of band (PSK=PMK) CCMP AES
WPA2 ??“
Enterprise
open, followed by 802.1x, in which
shared secret = certificate or other token
PMK from Authentication
Server
CCMP AES
TKIP is the Temporal Key Integrity Protocol. It uses a message integrity check called
???Michael.??? Like WEP, TKIP uses the RC4 stream cipher encryption algorithm.
CCMP stands for CTR (Counter mode) with CBC-MAC (Cipher Block Chaining
Message Authentication Code) Protocol.
Pages:
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115