def _GetDecrypter(self):
    """Retrieves a decrypter.

    Returns:
      A decrypter object (instance of encryptions.Decrypter).

    Raises:
      IOError: if the decrypter cannot be initialized.
    """
    try:
      credentials = resolver.Resolver.key_chain.GetCredentials(self._path_spec)
      return encryption_manager.EncryptionManager.GetDecrypter(
          self._encryption_method, **credentials)
    except __HOLE__ as exception:
      raise IOError(exception)
dataset/ETHPy150Open log2timeline/dfvfs/dfvfs/file_io/encrypted_stream_io.py/EncryptedStream._GetDecrypter