What is Shared Key Authentication (SKA)?
Shared Key Authentication (SKA) is a process by which a computer can gain access to a wireless network that uses the Wired Equivalent Privacy (WEP) protocol. With SKA, a computer equipped with a wireless modem can fully access any WEP network and exchange encrypted or unencrypted data.
For SKA to function, a WEP encryption key, obtained in advance by the connecting computer, must match a key stored at the wireless access point. To begin the connection process, the computer sends a request for authentication to the access point. The access point responds by generating a sequence of characters called a challenge text for the computer. The computer encrypts the challenge text with its WEP key and transmits the "message" back to the access point. The access point decrypts the "message" and compares the result with the original challenge text. If there are no discrepancies, the access point sends an authentication code to the connecting computer. Finally, the computer accepts the authentication code and becomes part of the network for the duration of the session or for as long as it remains within range of the original access point. If the decrypted "message" does not precisely agree with the original text, the access point does not allow the computer to become part of the network.
A wireless-equipped computer can connect to a WEP network access point without shared keys using a process known as Open System Authentication (OSA) but this method does not allow the computer to receive encrypted data.