A first application instance is associated with a protection domain based on credentials (e.g.: a signed certificate) associated with a set of application code that, when executed, gives rise to the application instance. The first application instance executes in a first execution context. An indication is received that the first application instance seeks access to protected functionality associated with a second execution context. In response to receiving the indication, a determining is made as to whether the first application instance has permission to access the protected functionality. The determination is made by determining the protection domain with which the first application instance is associated, and determining if the protection domain with which the first application instance is associated is in the set of one or more protection domains.