A preshared key (PSK) is a security method used to transfer a shared secret key between two parties in order to authenticate users. The process is initiated when PSK cipher suite(s) are included in the hello message to the client.
The wireless local area network (WLAN) produces a passphrase or password of eight to 63 characters. Afterward, a 256-character key is generated using this password by the router and the credentials of the connecting node. This is used for both encryption and decryption.
A PSK does not require an authentication server and is used in environments with limited computer processing power. It is an alternative for avoiding more process-demanding tasks such as public-key operations.