Open System or Shared-key authentication

On 26 Jan 2005 13:34:56 -0800, Richie spoketh
WPA doesn't use open system or shared key authentication, so don't worry about it.
Lars M. Hansen (replace 'badnews' with 'news' in e-mail address)

WPA-PSK usess a 4 way handshake. The PSK becomes the Pairwise Master Key (PMK). The PMK is used along with the mac address of both the ap and the client to create a unique (Pairwise Transient Key) The PTK is used in the initial start of dynamicly generated encrytion keys. A sniffer can find out the Mac addresses and also he can capture the authentication and using offline dictionary attacks he may be able to crack the passphrase. This is why it is important to not use names in the dic, or your name or any other legible word. This has been the only thing that has been mentioned as a weakness in wpa-psk. So if you use a really wierd passphrase of 20 characters or so you ought to be very safe (for now). So I would say, open authentication lets anybody associate with the AP although they cant pass any data and havent a clue about what the PTK may be. PSK using common words are riskier than open.