b$.$ Using the Dependency Inversion pattern we can do even better by creating an abstract interface called EncryptionMethod that will become the interface between high level client code and the lower level encryption$/$decryption methods. In addition to encrypt$()$ and decrypt$()$ methods we could also put the setPassword$()$ method into the interface and add a getPassword$()$ method that would return a string representation of the internal password data to make testing setPassword$()$ easier.