> Nation states almost certainly have the ability to extract the private keys out of an image sensor and SEP. Outside of superpowers even if you're willing to do it destructively. They can then sign their own fraudulent images.
That's not how this works.
Let's pretend they're able to extract the sensor key and the SEP key. Then what?
An attacker won't have the ECDSA P-256 over SHA-256 signed timestamp token from the Apple Push Notification Service.
When Reference mode starts, the operating system supplies a SHA-256 digest to be embedded at a fixed location in the captured frame’s metadata. The digest is computed from the most recent secure timestamp, the device manifest, and the device's secure boot manifest.
More encryption and checking happens until the secure digital negative is sent to Private Cloud Compute:
PCC recomputes the digest embedded in the frame and verifies the
sensor's signature over the pixels and that digest, verifying the
certificate chain back to the sensor CA. PCC also verifies the SEP
signature and chains it to the BAA CA, and it verifies the signature
on the device manifest and chains it to the CA that signs device
manifests at the factory. It then confirms that the sensor and SEP
named in those chains belong to the same device. Only if all these
checks pass does processing continue.