function getKeyFromFile

Source

Future<PrivateKey> getKeyFromFile(String path) async {
  var file = new File(path);

  PrivateKey key;
  if (!file.existsSync()) {
    key = await PrivateKey.generate();
    file.createSync(recursive: true);
    file.writeAsStringSync(key.saveToString());
  } else {
    key = new PrivateKey.loadFromString(file.readAsStringSync());
  }

  return key;
}