1. Introduction
Side channel attacks (SCAs) involve the collection and interpretation of signals emitted by a device [30]. Such attacks have been successfully implemented utilising a number of emanation types, such as electromagnetic (EM) waves [34], power consumption [17], mobile sensors [21, 22, 23], as well as sound [4]. With such a wide range of available mediums, target devices have been similarly varied, with compromised devices including printers [5], the Enigma machine [32] and even Intel 86 processors [37]. It was found in [34] that wireless keyboards produce detectable and readable EM emanations, however there exists a far more prevalent emanation that is both ubiquitous and easier to detect: keystroke sounds [27]. The ubiquity of keyboard acoustic emanations makes them not only a readily available attack vector, but also prompts victims to underestimate (and therefore not try to hide) their output. For example, when typing a password, people will regularly hide their screen but will do little to obfuscate their keyboard’s sound. The lack of concern regarding keyboard acoustics could be due to the relatively small body of modern literature. While multiple papers have created models capable of inferring the correct key from test data, these models are often trained and tested on older, thicker, mechanical keyboards with far more pronounced acoustics than modern ones, especially laptops.