Researchers have shown that motion sensors can pick up speech vibrations and typing patterns. Microphones can capture keystroke sounds, and screen and sensor timing can leak information. Apps often get motion sensors without asking.
What the shielding does
- Sensor monitoringThe gyroscope, accelerometer, and microphone arrays are watched for unusual access patterns.
- Rate limitingHigh-rate sampling, the kind side-channel attacks need, is capped or refused for apps with no legitimate reason to use it.
- Background denialSensor and microphone access from the background is blocked unless you grant it in real time.
- ReportingSentinel names the app that asked, so you can remove it.
Shielding removes the clean signal these attacks depend on. Physical surveillance in the room, such as a hidden microphone, is outside what a phone can control.