In order to overcome the vulnerability of WEP itself, WiFi Alliance puts forward WPA/WPA2 security solutions. But in actual applications, WPA/WPA2 still exist some defects which can be attacked. Especially in WPA/WPA2PSK mode, user passphrase can be acquired through the dictionary attack after capturing several specific wireless packets. Through the analysis of the dictionary attack principle, an improved method of dynamic key negotiation in WPA/WPA2PSK mode is developed. The improved method is based on symmetric key encryption technology and could avoid user passphrase suffering from dictionary attack. The improved method strengthens the safety of WPA/WPA2PSK mode.

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