On a blustery March day, the artist Jim Sanborn received visitors at his studio on an isolated island in the Chesapeake Bay. The visitors sat him down in front of a laptop, and he typed in a secret message. They compressed the message using a unique hash function, sent that to the cloud, and wiped the laptop clean. Sanborn hoped that this action would set him free. But did it?

That’s the latest twist in the story of Kryptos, the famous Sanborn sculpture that’s been sitting outside CIA headquarters in Langley, Virginia, since 1990. The artwork is a copper S-curve that stands 9 feet, 11 inches tall, into which Sanborn had punched four panels of encrypted text. Professional and amateur cryptanalysts alike have been trying to crack the…