Re: reencrypt: how to specify old and new key-files?

One more thing which is a bit confusing to me:
- There's luksChangeKey (and the somewhat overlapping luksConvertKey)
which changes a keyslot key/passphrase and/or its KDF algo/params.
- cryptsetup reencrypt, also allows to change the KDF algo/params (but
not the keyslot key/passphrase), which makes that part of identical to
luksConvertKey.


With all of them (luksChangeKey, luksConvertKey, reencrypt), what does
cryptsetup do when I don't specify the --pbkdf / --iter-time /
--pbkdf-memory / --pbkdf-parallel / --pbkdf-force-iterations options?
- For reencrypt the manpage says that for --cipher, it would use the
existing algo when really re-encrypting and the default when freshly
encrypting.
- But what about these options, when I don't specify ANY of the KDF
algo/param options? Do they use the same than what's been there
before? Or the default?
- What, if one specifies ONLY SOME of them? E.g. it was previously
PBKDF2, and I do only --pbkdf argon2id  OR  only that and
--pbkdf-parallel 4 - will the others get defaults?

Tanks,
Philippe