Da Vinci Under Lock-and-Key
In Dan Brown's suspenseful novel, The Da Vinci Code, a combination lock he dubs a "Cryptex" is poised to secure and protect secrets written on a parchment contained inside a portable vault. The author coined the term by combining the words "cryptography" and "codex," a large volume of ancient texts bound together in book form, like those for which Leonardo is famous.
The Cryptex functions like a bicycle combination lock. Inside the device, discs must be positioned in the exact manner to spell out a correct, preset password. Tumblers inside the lock then align, allowing the inner cylinder to slide apart, protecting the contents in the inner space.
In the Da Vinci Code, the incorrect combination will release a vial of vinegar, destroying the message inside, making it unreadable. Imagine if all of da Vinci’s codices had been encrypted this way!
While central to Brown's story, there is no evidence that Leonardo invented anything like this. But as a case of "life imitating art," since its mention in the 2003 blockbuster novel, the Cryptex has become a popular puzzle in-and-of-itself, foiling would-be lock pickers around the globe.