I was looking at this guide to setting up a wifi connection on a modern linux system (specifically raspbian, but I assume the steps are similar in other linux systems) with only a command-line interface. The guide mentioned that the PSK could be stored as a pre-encrypted 32 byte hexadecimal number, but also mentioned that a plaintext SSID and PSK will be used to connect. Further, the
wpa_passphrase tool seems to encrypt the PSK using the SSID (unless I am misinterpreting the tutorial).
If an attacker gained access to this wpa-supplicant configuration file, it seems like he could just use the SSID (stored there in plain text) and knowledge of the
wpa_passphrase tool's encryption algorithm to decrypt the PSK, giving no more security than storing a plain-text PSK in the file. Is this not the case, and why?