It's fascinating to me that gyroscope and accelerometer data don't seem to require permissions or explicit user opt-in on smartphones (at least that was true a

It's fascinating to me that gyroscope and accelerometer data don't seem to require permissions or explicit user opt-in on smartphones (at least that was true a few years ago and still seems true from a quick Google search, although I'm not sure if things have changed). As a side-channel, I've read about them being used for: - This. - Audio recordings of users (https://arxiv.org/pdf/1907.05972.pdf https://arxiv.org/pdf/1907.05972.pdf) - Keystrokes (https://medium.com/@tomasreimers/axolotl-a-keylogger-for-iphone-and-android-a8b7b62cdab4 https://medium.com/@tomasreimers/axolotl-a-keylogger-for-iph..., this one is shameless self-promotion and also why I'm interested in the topic) To me it seems that there are so few legitimate use-cases for device motion (mostly fitness related and https://www.cyberdefinitions.com/definitions/SMTH.html https://www.cyberdefinitions.com/definitions/SMTH.html) that it's almost shocking you can access them by default.