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DTUS065 rev A.7 – June 27, 2014
In
Open System authentication
, the WLAN client need not provide its
credentials to the Access Point during authentication. Thus, any client,
regardless of its WEP keys, can authenticate itself with the Access Point and
then attempt to associate. In effect, no authentication (in the true sense of the
term) occurs. After the authentication and association, WEP can be used for
encrypting the data frames. At this point, the client needs to have the right
keys.
In
Shared Key authentication
, WEP is used for authentication. A four-way
challenge-response handshake is used:
I) The client station sends an authentication request to the Access Point.
II) The Access Point sends back a clear-text challenge.
III) The client has to encrypt the challenge text using the configured
WEP key and send it back in another authentication request.
IV) The Access Point decrypts the information and compares it with the
clear-text it had sent. Depending on the result of this comparison,
the Access Point sends back a positive or negative response. After
the authentication and association, WEP can be used for encrypting
the data frames.
At first glance, it might seem as though Shared Key authentication is more
secure than Open System authentication, since the latter offers no real
authentication. However, it is quite the reverse. It is possible to derive the
static WEP key by capturing the four handshake frames in Shared Key
authentication. Hence, it is advisable to use Open System authentication for
WEP authentication, rather than Shared Key authentication. (Note that both
authentication mechanisms are weak).
V.5.2
WPA/WPA2 encryption
WPA greatly increases the level of over-the-air data protection and access
control on existing and future Wi-Fi networks. It addresses all known
weaknesses of Wired Equivalent Privacy (WEP), the original native security
mechanism in the 802.11 standard.
WPA not only provides strong data encryption to correct the weaknesses of
WEP, it adds user authentication that was largely missing in WEP. WPA is
designed to secure all versions of 802.11 devices, including 802.11b,
802.11a, and 802.11g, multi-band and multi-mode.
WPA is the older standard (which, due to progress in crypto science,
is not
considered secure anymore
); select this option if the Access Point only
supports the older standard. WPA2 is the newer implementation of the
stronger IEEE 802.11i security standard.
The cipher type is the encryption algorithm used to secure the data
communication. TKIP (Temporal Key Integrity Protocol) provides per-
packet key generation and is based on WEP. AES (Advanced Encryption
Standard) is a very secure block based encryption.
You can choose from 2 security options:
WPA Mode
Cipher Type
Security solution
WPA
AES
RC4-CCMP
WPA2
AES (default)
AES-CCMP
