SIA: Smartwatch-Enabled Inference Attacks on Physical Keyboards Using Acoustic Signals

The convergence of various technologies, such as smartwatches, smartphones, etc. has proven to be beneficial, although poses various security and privacy risks. In this paper, we explore one such risk where a smartwatch can be exploited to infer what a user is typing on a physical keyboard while wearing the smartwatch. We exploited the acoustic emanations of the keyboard as recorded by the smartwatch to perform the proposed attack-SIA. To address various environment-related challenges, SIA employs four stages: Noise Cancelling, Keystroke Detection, Key Identification, and Word Correction, where several digital signal processing, machine learning, and natural language processing techniques are utilized to produce the final inference. Our results show that an acoustic emanation of a physical keyboard captured by a smartwatch recovers up to 98% of the typed text. We also showed that utilizing the noise cancellation, SIA is robust to the changes in the attack environment, which further boosts the practicality of the attack. The findings are alarming and call for further investigation on methods to cope with inference attacks due to the convergence of those technologies.