Verifying Apple Reference Images

In the iPhone 18 Pro, Apple added trusted hardware in the camera sensor that cryptographically signs the pixel data, but outside of their own iOS 27 Photos app, there wasn't really a way to inspect and verify these "Apple Reference Image" pictures. After lots of experimentation and poking around, we now know a lot more details about what's going on under the hood, which allowed us to write the first open-source verifier tool as well as this interactive deep dive article.

Apple's approach is quite different from prior works like C2PA, not just that parts of it are integrated with the sensor hardware, but also in that the image that user generally see isn't actually cryptographically signed at all - only the (half-resolution, raw-ish) "reference" JPEG that's stored as invisible metadata inside the image file container is actually signed.

You also need to explicitly enable this reference image mode in the camera app, and then it's also quite easy to accidentally loose the reference part when sharing or exporting the image, so the user experience is definitively still a bit rough around the edges