MoLe: Motion Leaks through Smartwatch

SensorsB00902069 傅蕎

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Demo video• https://www.youtube.com/watch?v=scZEHExzems

&feature=youtu.be

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MoLe• Motion sensor leaks input words• Accelerometer & gyroscope on Samsung watch

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Related work• Inferring keystroke on keyboard• Acoustic• Input timing• Electromagnetic

• Information from smart sensors• Typing on virtual keyboard• Keystroke cause vibration

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Specialty• No need training user• No brand-new signal processing or learning algorithm• No right hand data, with watch on left hand• Must dictionary word• Must not typing error• Must “correct” typing way• Output top-K possible words• Not support whole sentence, difficulty in “space bar”• Can support different keyboard

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System overview

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Watch data• Watch & phone camera & keyboard log• CPC(character point cloud)

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Keystroke detector - timing• Z axis• Error occurs• Moving from one key to another• Subtle motion, e.g. “asdf”

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Keystroke detector - location• Origin as “F” key• Gravity removal• Watch’s axis → absolute• Kalman smoothing

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Cloud fitting• UPC(unlabeled point cloud)• Reference template

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Bayesian inference• Output ranked list of possible word• Conditional probability• # of keystrokes• Consecutive character, e.g. “er”, “sa”• Watch displacement• Character transition, e.g. “va” VS “ra”• Keystroke interval

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Evaluation• 8 subjects familiar with English-typing• Variable factor• Word length• Bayesian model• Sampling rate• Keyboard

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Question?

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Thanks!:D