Function joplin_reader::key::load_master_key

pub fn load_master_key(
    key_path: &Path, 
    key_id: String, 
    passphrase: String
) -> Result<MasterKey, JoplinReaderError>

A passphrase is only used to decrypt the actual master key. This function uses a key_id and passphrase pair to read the key file and return the actual master key.