Edward Snowden, along with security engineer Micah Lee, have released an Android app in partnership with The Guardian Project. This app is intended for citizens who themselves or their possessions are at risk and would like to monitor their surroundings to warn them of intruders.
Called Haven, the app uses the sensors on your Android device to track various metrics. It uses the accelerometer to track the movement of the device and surrounding vibrations, camera to track movements of objects in view, microphones to track noises in the environment, ambient light sensors to track changes in the lights and power to check if the phone was unplugged or the power cut.
The way this is supposed to work is that you should ideally install this app on a burner phone with a SIM card. The app is then configured to log all the information and send notifications to a number, ideally your personal number, over a secure channel like Signal or Tor with end-to-end encryption. If the app picks up any data from the sensors, such as someone entering your room or accessing your belongings (let's say, your laptop) then it will immediately send notifications to your main number. Alternatively, it can be installed on your main phone and have the notifications be sent to a trusted number, alerting them in case you come in physical danger.
Admittedly, an app that uses sensors to track everything about your surroundings doesn't sound any less scary than the threats it claims to protect you against. But for those paranoid, the app is open source, so anyone can look at the underlying source code and the developers have invited people to contribute to it. You can also compile the app yourself using Android Studio and Gradle. All the necessary libraries and third-party dependencies are provided on their GitHub page.
Haven is currently in beta and available for download for free on Android.
