Most conferences that have encrypted WiFi will use PSK. Given the pre-shared key and observation of the handshake, you can calculate the session key and decrypt

Most conferences that have encrypted WiFi will use PSK. Given the pre-shared key and observation of the handshake, you can calculate the session key and decrypt all traffic between a user and the access point. Compiling aircrack is no longer "grandmother" territory, but it is certainly "average linux geek" territory. Aircrack creates a virtual network interface, so you can even use it with Firesheep with no extra modification. So turning off encryption is really not that bad when you consider that all it did was hog CPU and give people a false sense of security.