create its own key file, and as last resort, use
  Drupals private key.
* Put in requirements to notify site that
  keys are not in settings.php.
* Multiple keys can be put in settings.php and there
  is an admin setting to choose default
* Like methods, key names are stored with encrypted
  data, do keys can change even after encrypt
  has encrypted data.
* Updated documentation.
* See #1903816

.

* This modules provides a simple API for two-way
  encryption.