2026-10-23 / Signal #5
An AI hid secret messages in pictures by changing building heights — another AI read them
“This AI hid a secret in a picture by making the buildings different heights. Another copy of it read the message.”
The Story
Researchers asked Claude Fable 5.1 to hide a message inside an ordinary-looking SVG image without telling it how. A completely separate Fable session, given only the rendered PNG, recovered 39 of 50 messages (78%). The model independently converged on encodings such as object heights or tilts representing letters. No shared scheme was agreed in advance.
Why It Matters
AI art just became a covert channel. Two instances of the same model invented and then solved a steganography language using the heights of stars and buildings.
Evidence
LessWrong, GitHub experiment write-up, HN
Sources
Daily scan: 2026-10-23