Non-interference properties on programs describe the absence of illicit
information flows. We focus on non-interference properties for the
byte-code language of the Dalvik virtual machine (DVM). The DVM
executes programs on Android, a popular operating system for mobile
phones. Most programs for Android make extensive use of
multi-threading to ensure smooth responses to user interactions. We
introduce an abstract transition system that supports multi-threading
and instantiate it with a subset of the DVM. To capture the notion of
secure/legal information flow for this abstract transition system, we
introduce a bisimulation based non-interference property that exploits
the intended data usage of concurrently executed threads.