Shared Key Authentication (SKA)

Definition - What does Shared Key Authentication (SKA) mean?

Shared key authentication (SKA) is a verification method in which a computer or terminal uses the Wired Equivalent Privacy (WEP) protocol to access a wireless network. It pre-establishes that a requesting system has knowledge of a shared secret key required for authentication.

The Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard assumes that the key is delivered to wireless clients using a secured channel that is independent of the standard. In practice, the user simply types in the password for the Wi-Fi network in order to gain access.

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Techopedia explains Shared Key Authentication (SKA)

Shared key authentication (SKA) is not considered a secure method of granting network access because it uses conventional unsecured channels, like writing and verbal exchange, to share a security key for granting access.

Although the dissemination of the key is a large security issue, the authentication itself is secured using 64 or 128-bit encryption. It is difficult for an intruder to gain access without knowledge of the key.

SKA employs the following steps:

The requesting wireless device/client sends an identity assertion and authentication request to the access point (AP).
The access point challenges the client by sending a challenge text.
Using WEP and an encryption key, which is derived from the secret shared key (password), the client encrypts the challenge text and sends it back to the AP.
The AP decrypts the challenge text, and if it matches the one originally sent to the client, the authentication result is positive and the AP authenticates the client.
The client successfully connects to the network.