Following from, What information is leaked from an OpenPGP encrypted file?, which was very helpful, I'd like to ask a similar question regarding symmetric encryption. For example, in a file encrypted with
gpg -c --cipher-algo AES256 --armor -o file.asc file.txt
Is the passphrase hash (with salt and iterations as specified by --s2k-count) stored in the file.asc? How does gpg know a passphrase is correct?