# How is a salt used in WPA-PSK PBKDF2 key generation for both sides

I'm just learning about WPA-PSK and d I'm already stuck. My understanding is that both the AP and STA share the PSK, which is generated from PBKDF2 function. Which according to wikipedia is:

 DK = PBKDF2(PRF, Password, Salt, c, dkLen)


But wikipdia also says that Salt is random, so how can the DK be the same on the STA and the AP?

They also show that WPA uses:

DK = PBKDF2(HMAC−SHA1, passphrase, ssid, 4096, 256)


Is the HMAC related to the salt in this case, or is it a hash of the passphrase, ssid, etc?