BitLocker does this and it's nice UX for walking someone through a recovery key over the phone.
Another VERY nice feature is it hashes each set of 6 digits as you type, so if you transpose one, you immediately get feedback instead of "invalid key!" after typing the whole thing out.
Another VERY nice feature is it hashes each set of 6 digits as you type, so if you transpose one, you immediately get feedback instead of "invalid key!" after typing the whole thing out.