Behavicker: Eavesdropping Computer-Usage Activities through Acoustic Side Channel

Algorithm 1

Event detection.

Input:  clean audio signal sequence , constant parameters and

Output:  event segments , event start point , press(first) end point , event(release) end point ,

₁ ; framing the signal as windows sequence with step equal to 1;

₂ whiledo

₃  update , and , based on Equation(1)~Equation (4);

₄  ifthen

₅    ; Blindly segment the signal into equal length as signal ;

₆    forward to find that satisfied ;

₇    ;

₈    find inverse start point as on the reversed signal sig

₉    ES = S(i-1000:eep+1000);

₁₀    return , , ;

₁₁  end

₁₂ end