Proof of Capture: Apple Reference Image, but open source and using steganography
20 days ago
- Apple introduced Apple Reference Image to cryptographically verify camera-captured photos vs. AI-generated ones.
- The author and Alex Hornstein built an open-source Proof of Capture camera using steganography and cryptographic signing.
- Steganographic watermarks are embedded in image pixels, surviving compression and resizing unlike metadata-based EXIF signatures.
- The camera uses an ATECC608 chip with a sealed private key for signing, preventing tampering.
- Apple's approach signs pixels at capture time but uses a proprietary 'digital negative' in Private Cloud Compute, not the open C2PA standard.
- No current system fully prevents screen attacks where an AI image is photographed on a display.
- The Proof of Capture camera is open source and buildable for under $100.