If you have that file (“Cinderella”) you can create that hash (a glass shoe that fits her) but you cannot go back the other way (you cannot create a Cinderella from the shoe!). Possessing the shoe also does not tell you where Cinderella is Possesing the shoe does not allow the prince to home in on her location - it does not give clues like “warmer” or “colder”

Dominic Tarr: fairly tale cryptography 2: hashes