A 256-bit pre-shared key is used in WPA authentication. If you type a password, this key is calculated by applying the PBKDF2 key derivation function to the pas

A 256-bit pre-shared key is used in WPA authentication. If you type a password, this key is calculated by applying the PBKDF2 key derivation function to the passphrase, using the SSID as the salt and 4096 iterations of HMAC-SHA1. In my case, I am entering the raw PSK manually, so I can't say for sure that some passphrase exists that map to my PSK. Hex digits make it easier to enter this 256-bit binary value and it is a standard way to enter raw PSKs.