Apple Reference Image signs photos at the sensor and develops them in Private Cloud Compute

Sources: primary, discussion
Summary: Apple described Reference Image as an opt-in capture mode debuting on the main camera sensor of iPhone 18 Pro and iPhone 18 Pro Max, relying on custom-designed sensors in those two models rather than on the platform as a whole. The sensor signs the capture and Private Cloud Compute develops the raw image. The final file carries a composite post-quantum signature combining RSA-3072 and ML-DSA-87, and the design supports revoking a sensor, meaning every photo from it, and revoking individual photos.
Why it matters: It moves image provenance from post-capture metadata, which C2PA relies on, to a hardware root of trust.