If you know the passphrase and you listen in when a client first connects, then you can extract all the data (easy to do in wireshark) However, if you joined/s

If you know the passphrase and you listen in when a client first connects, then you can extract all the data (easy to do in wireshark) However, if you joined/started sniffing for packets after the other client auth'd, than it's harder, at least in wireshark. It's been a while since I did it, but I do remember you need to listen to the initial negotiation for WPA, but not for WEP.