SKA Shared Key Authentication

Shared Key Authentication (SKA) is a method of authenticating network devices in a wireless network. It is commonly used in Wi-Fi networks and is based on a shared secret key that is known by both the access point (AP) and the client devices. SKA is a simple and straightforward authentication method that provides a basic level of security but is considered less secure compared to more advanced authentication methods like WPA2 or WPA3.

Here is a detailed explanation of how SKA works:

1. Pre-shared Key (PSK) Generation: The first step in SKA is generating a pre-shared key, also known as a secret key or password. This key is created by the network administrator or the user who sets up the wireless network. The PSK should be a complex and random string of characters to ensure its security.
2. Key Distribution: Once the PSK is generated, it needs to be distributed to the client devices and the AP. This can be done manually by entering the PSK into each client device, or it can be distributed using methods like QR codes, USB sticks, or automatic configuration protocols like Wi-Fi Protected Setup (WPS).
3. Association Request: When a client device wants to connect to a wireless network that uses SKA, it sends an association request to the AP. This request includes the network's Service Set Identifier (SSID) and any additional information required by the network.
4. Shared Key Authentication: Upon receiving the association request, the AP checks whether the SSID matches the network it is broadcasting. If the SSID matches, the AP responds with a challenge to the client device.
5. Challenge-Response: The challenge is a random value generated by the AP and sent to the client device. The client device takes the challenge, combines it with the PSK using a cryptographic algorithm (e.g., a one-way hash function like HMAC-SHA1), and generates a response.
6. Verification: The client device sends the response back to the AP. The AP performs the same computation using the PSK and the received challenge to generate its own response. If the response generated by the AP matches the response sent by the client, the AP considers the client device authenticated and allows it to join the network.
7. Network Access: Once the authentication is successful, the AP and the client device establish a secure connection using the shared secret key. This key is used for encrypting and decrypting data exchanged between the client and the AP, ensuring the confidentiality and integrity of the wireless communications.

It's important to note that SKA has certain limitations and vulnerabilities. Since the same PSK is shared among all devices in the network, if the PSK is compromised or known to unauthorized individuals, they can easily gain access to the network. Additionally, if a device needs to be removed from the network, changing the PSK and reconfiguring all devices becomes necessary, which can be cumbersome in larger networks.

As a result of these limitations, more secure authentication methods like WPA2 (Wi-Fi Protected Access II) and WPA3 have been developed, which use more robust encryption algorithms, individualized key management, and more advanced security mechanisms.