Here is a detailed explanation of how this process works:

1. Shared Key Configuration

Before any authentication can take place, both the access point (AP) and client devices must have the same shared key configured.

This key is established by the network administrator and must be entered manually in the AP configurations and in each of the devices that wish to connect to the network.

2. Authentication Process

The Shared Key Authentication process typically follows these steps:

• Authentication Request: The client device sends an authentication request to the AP to start the process.
• AP Challenge: The AP responds to the request by sending a challenge to the client. This challenge is basically a random data set.
• Customer response: The client device receives the challenge and uses the shared key to encrypt this data. It then sends the encrypted data back to the AP as its response to the challenge.
• AP Verification: The AP, which also knows the shared key, decrypts the response. If the decrypted data matches the original challenge, the AP assumes that the client has demonstrated knowledge of the shared key and therefore authorizes its access to the network.

3. Security

Although authentication using shared keys may seem secure, it has several vulnerabilities:

• Fixed Shared Key: If the key is intercepted or otherwise compromised, any device with knowledge of this key can access the network.
• Vulnerability to Interception Attacks: The exchange of encrypted challenges and responses can be intercepted by an attacker, who could then attempt to decrypt the shared key using traffic analysis techniques or brute force attacks.

4. Safer Alternatives

Due to these vulnerabilities, the use of shared keys for wireless authentication has largely been replaced by more secure methods, such as WPA2 (Wi-Fi Protected Access 2) and WPA3, which use more robust authentication protocols such as EAP (Extensible Authentication Protocol) along with a variety of encryption methods to protect wireless communications.

Although shared key authentication was one of the first methods used in Wi-Fi networks, its security limitations have led to the adoption of more advanced and secure authentication and encryption technologies.