This reminds of a story in Hugo Cornwall's The Hacker's Handbook. He mentions that MI6 had figured out that each striker makes a slightly different sound when i

This reminds of a story in Hugo Cornwall's The Hacker's Handbook. He mentions that MI6 had figured out that each striker makes a slightly different sound when it hits the paper, so they'd started bugging printers. In retrospect, somebody really should have thought of this three decades ago. Props to the person that did, though.