A study called “SensorID: Sensor Calibration Fingerprinting for Smartphones” examined sensor fingerprinting techniques against smartphones. It found that Micro Electro Mechanical Systems (MEMS) are inaccurate in small ways that make them unique. But Apple thwarted this technique in iOS 12.2 and used the researchers’ suggestion to add random noise to the analog-to-digital converter output and removing default access to motion sensors in Safari.
We demonstrate that our approach is very likely to produce globally unique fingerprints for iOS devices, with an estimated 67 bits of entropy in the fingerprint for iPhone 6S devices. In addition, we find that the accelerometer of Google Pixel 2 and Pixel 3 devices can also be fingerprinted by our approach.