Years ago, I read a paper about how mobile devices made it possible to authenticate users without entering a password, simply by relying on behavior, habits, locations. Now, the DoD plans to use such authentication mechanisms for their own network security. However, I haven't seen any apps that use this widely.
I guess I have two questions:
1) Are there any real-world examples of such behavioral/implicit authentication systems that justifies the DoD's faith in using this for parts of their network?
2) If no, then what has prevented them from being more widely used-- is it because human behavior is unpredictable and this leads to false negatives (why not use passwords as a backup)? Or is it because of the privacy implications of such a scheme? Surely, we all hate typing passwords on our phone screens...