pub trait KdfBasedKeyWrapper: KeyWrapper {
// Required methods
fn kdf_algorithm(&self) -> KdfAlgorithm;
fn update_salt(&mut self, salt: Vec<u8>) -> Result<(), Error>;
fn unwrap_key(&self, password: &str) -> Result<Vec<u8>, Error>;
fn impl_to_bytes(&self) -> Result<Vec<u8>, Error>;
// Provided method
fn kdf_wrapper_to_bytes(&self) -> Result<Vec<u8>, Error> { ... }
}