Guys, this as others have already asserted, is very old tech. It goes back to days of Morse code use in the military. Morse operators could authenticate another sender's identitiy (or whether he was sending his message under duress and potentially compromised) by what was called his "fist", or the rhythm of the transmission. Notably, Imprivata made an effort a couple of years ago to monetize this approach, but it is as many have pointed out fraught with multiple issues depending on how you enter and/or manage your passwords.