A reference monitor must have a complete policy. Specifically, in our system the user must provide a complete list of Android methods she wishes to detect and rewrite. If the user fails to identify methods in the Android framework that access sensitive resources, then our framework will not know to rewrite these method calls when it sees them in the app. While selecting the correct methods for the policy is important, the methodology for doing so is orthogonal to our work, and highly dependent on the user’s security goals