Dell AP-175 Network Card User Manual


 
33
4.1.2 User Authentication
Authentication for the User role depends on the module configuration. When the module is configured as a
Remote Mesh Portal FIPS mode and Remote Mesh Point FIPS mode, the User role is authenticated via the
WPA2 pre-shared key. When the module is configured as a Remote AP FIPS mode and CPSec protected
AP FIPS mode, the User role is authenticated via the same IKEv1/IKEv2 pre-shared key/RSA certificate
that is used by the Crypto Officer
4.1.3 Wireless Client Authentication
The wireless client role defined in each of FIPS approved modes authenticates to the module via WPA2.
Please notice that WEP and/or Open System configurations are not permitted in FIPS mode. In advanced
Remote AP configuration, when Remote AP cannot communicate with the controller, the wireless client
role authenticates to the module via WPA2-PSK only.
4.1.4 Strength of Authentication Mechanisms
The following table describes the relative strength of each supported authentication mechanism.
Authentication
Mechanism
Mechanism Strength
IKEv1/IKEv2
shared secret (CO
role)
For IKEv1/IKEv2, there are a 95^8 (=6.63 x 10^15) possible pre-shared keys.
In order to test the guessed key, the attacker must complete an IKEv1/IKEv2
aggressive mode exchange with the module. IKEv1/IKEv2 aggressive mode
consists of a 3 packet exchange, but for simplicity, let’s ignore the final
packet sent from the AP to the attacker.
An IKEv1/IKEv2 aggressive mode initiator packet with a single transform,
using Diffie-Hellman group 2, and having an eight character group name has
an IKEv1/IKEv2 packet size of 256 bytes. Adding the eight byte UDP header
and 20 byte IP header gives a total size of 284 bytes (2272 bits).
The response packet is very similar in size, except that it also contains the
HASH_R payload (an additional 16 bytes), so the total size of the second
packet is 300 bytes (2400 bits).
Assuming a link speed of 1Gbits/sec (this is the maximum rate supported by
the module), this gives a maximum idealized guessing rate of 60,000,000,000
/ 4,672 = 12,842,466 guesses per minute. This means the odds of guessing a
correct key in one minute is less than 12,842,466/(6.63x10^15) = 1.94 x 10^-
9, which is much less than 1 in 10^5.