Apple introduced Apple Reference Image to cryptographically prove photos were taken by a camera, not AI-generated. During the Recurse Center summer, Alex Hornstein and I built a proof-of-capture camera using a Raspberry Pi Zero, display board, ATECC608 crypto chip, shutter button, and 3D-printed enclosure. The approach flips detection: prove real at capture time instead of detecting fakes later.

We used steganography to embed a signed perceptual hash in image pixels, surviving compression and resizing. The ATECC608 chip handles signing, with private key never leaving the chip and locking if tampered. Apple's method signs pixels at capture but stores signature in a 'digital negative' via Private Cloud Compute, not using open standard C2PA.

Neither solution fully stops screen attacks, but both address the problem. The project is open source and buildable for under $100. Visit Recurse Center to see the printed photo from our camera.