So I was wondering about some alternative attack scenario which I thought of when I started to understand KDF's . So lets say you have a cipher like AES and a strong KDF . And the legit user uses a 30 character strong Password :
30-char Pass ---> KDF ( slow stuff : argon2,scrypt ) ----> AES256
And normally the attacker would have to start at the beginning with brute force and then passing through the KDF which slowes him down very much and then finally checking if the final bit string is accepted by AES to decrypt the ciphertext .
But I the attacker knows that the legit user uses a very strong Pasword and a decent KDF , would it not be more efficient to just bypass the KDF and brute force the AES bits directly ( takes longer , but much less slowdown ) like :
wordlist ---> Some random 256 hash ( sha256 ) -----> AES256
With that method the attacker could brutefoce every possible AES key and the length would not even matter . But It would be very difficult because of all the possibilities .
How likely is such a Scenario ? And is it even worth doing so ?