Yes you can share data between Activities by packing it into a Bundle, and handing it over to the next Activity you start. But why would you need to check these things?
If you have activityes A1, A2, and say A3. Then most likely your program will start activity A1 from the application launcher menu. But no other application will be able to start your other activities A2 and A3 unless you design them for that pupose. So you will not get into a situation where you need to verify that your user is looking at an activity which he has the rights to access.
Correct me if I am wrong.