Edward Snowden, along with security engineer Micah Lee, has released an Android application in partnership with The Guardian Project. This application is intended for citizens who themselves or their assets are at risk and would like to monitor their environment to warn them of any intruders.
Haven, the app uses the sensors on your Android device to track different metrics. It uses the accelerometer to track the movement of the device and the surrounding vibrations, the camera to track the movements of the objects in sight, microphones to follow the noises in the environment, the light source lights to follow the changes in the lights and the power to check if the phone was the disconnected has no energy.
The way the app should work is that you need to install this application on a phone with a SIM card. The application is then configured to record all the information and to send notifications to a number, ideally your personal number, over a secure channel such as Signal or Tor with encryption. If the app receives data from sensors, as someone entering your room or accessing your belongings (let's say, a laptop) will immediately send notifications to your primary number. Alternatively, it can be installed on your primary phone and send the notifications to a trusted number, notifying them if you are in physical danger.
Undoubtedly, an app that uses sensors to find everything around your environment does not seem less frightening than the threats it claims to protect. But for those paranoid, the app is an open source so anyone can see the basic code and developers have invited people to contribute to it. You can also compile the application using Android Studio and Gradle. All necessary libraries and third-party dependencies are provided on their GitHub site.
Haven is currently in beta and can be downloaded for free on Android.