> It would be amazing if they went back to typewriters as being 'unhackable' devices.

Considerable amounts of money and expertise have been thrown at sound analysis, and it's used in a range of situations from telling what submarine is in your waters to knowing what a typist is typing.

And eventually people put parallel ports on typewriters because typists are more expensive than a parallel port, at which point you've got a cumbersome but very hackable printer.

Researchers recover typed text from audio recording: https://news.ycombinator.com/item?id=7448976

Acoustic snooping: https://freedom-to-tinker.com/2005/09/09/acoustic-snooping-t...

And Germany was thinking of trying exactly this: http://www.telegraph.co.uk/news/worldnews/europe/germany/109...