Is Wpa/Wpa2 Perfect - NETGEAR WG102 - ProSafe Wireless Access Point Reference Manual

Reference Manual for the NETGEAR ProSafe 802.11g Wireless Access Point WG102
• The verification of the security configuration after the encryption keys are determined.
• The synchronized changing of the unicast encryption key for each frame.
• The determination of a unique starting unicast encryption key for each preshared key
authentication.
Michael
With 802.11 and WEP, data integrity is provided by a 32-bit integrity check value (ICV) that is
appended to the 802.11 payload and encrypted with WEP. Although the ICV is encrypted, you can
use cryptanalysis to change bits in the encrypted payload and update the encrypted ICV without
being detected by the receiver.
With WPA, a method known as Michael specifies a new algorithm that calculates an 8-byte
message integrity check (MIC) using the calculation facilities available on existing wireless
devices. The MIC is placed between the data portion of the IEEE 802.11 frame and the 4-byte ICV.
The MIC field is encrypted together with the frame data and the ICV.
Michael also provides replay protection. A new frame counter in the IEEE 802.11 frame is used to
prevent replay attacks.
AES Support for WPA2
One of the encryption methods supported by WPA2 is the advanced encryption standard (AES),
although AES support will not be required initially for Wi-Fi certification. This is viewed as the
optimal choice for security conscience organizations, but the problem with AES is that it requires a
fundamental redesign of the NIC's hardware in both the station and the access point. TKIP is a
pragmatic compromise that allows organizations to deploy better security while AES capable
equipment is being designed, manufactured, and incrementally deployed.

Is WPA/WPA2 Perfect?

WPA/WPA2 is not without its vulnerabilities. Specifically, it is susceptible to denial of service
(DoS) attacks. If the access point receives two data packets that fail the message integrity code
(MIC) within 60 seconds of each other, then the network is under an active attack, and as a result,
the access point employs counter measures, which include disassociating each station using the
access point. This prevents an attacker from gleaning information about the encryption key and
alerts administrators, but it also causes users to lose network connectivity for 60 seconds. More
than anything else, this may just prove that no single security tactic is completely invulnerable.
WPA/WPA2 is a definite step forward in WLAN security over WEP and has to be thought of as a
single part of an end-to-end network security strategy.
Wireless Networking Basics
202-10064-02, June 2005
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