code: def _GetDecrypter(self):
      
      resolver.Resolver.key_chain.ExtractCredentialsFromPathSpec(self._path_spec)
  
      try:
        credentials = resolver.Resolver.key_chain.GetCredentials(self._path_spec)
        return encryption_manager.EncryptionManager.GetDecrypter(
            self._encryption_method, **credentials)
      except ValueError as exception:
        raise IOError(exception)
docs: Retrieves a decrypter.
  
      Returns:
        Decrypter: decrypter.
  
      Raises:
        IOError: if the decrypter cannot be initialized.
        OSError: if the decrypter cannot be initialized.