Apple has introduced a new technology called Apple Reference Image in the iPhone 18 Pro and iPhone 18 Pro Max, aimed at creating a cryptographically recorded history of a photo's authenticity.
According to ITNA citing Techspot, this optional capability signs the image's pixel data immediately after capture by the camera sensor; that is, before the image enters the usual stages of software processing. Apple says this method can determine that the image was indeed captured by the iPhone camera sensor and that its original data were not altered prior to the cryptographic signing.
When this feature is enabled, the camera sensor enters a dedicated operational mode and signs the pixel data immediately after capture. The resulting file acts like a “secure digital negative” and, in addition to the pixel data, stores cryptographically signed information about the sensor and the time.
The iPhone's Secure Enclave processor also signs some information related to the capture, including exposure settings, digital zoom, and lens information. These data are kept separate from the sensor information so they cannot change the original pixels.
The reference image must be processed to become a usable photo. When this is done, the original negative is sent to Apple's Private Cloud Processing system. This system checks the sensor and Secure Enclave signatures, verifies the association of the hardware components with the same iPhone, and ensures the image-processing software is approved. The photo is then processed and converted to a standard photo format.
The final image also receives a composite signature that uses the RSA-3072 algorithm and the quantum-resistant ML-DSA-87 algorithm. Apple says this approach is designed to keep images verifiable over the long term.
This technology also pays attention to photographer privacy. Reference images do not contain public information to identify the photographer and are not meant to enable linking multiple images to a specific camera sensor for others. Apple can also revoke a photo or a set of photos associated with a sensor if it detects a security issue, without needing to view the photo content to do so.
Apple Reference Image is optional and works only with the main camera of the iPhone 18 Pro and iPhone 18 Pro Max. This technology is offered with the goal of creating a reliable technical record of image provenance, at a time when distinguishing real photos from edited or AI-generated images is becoming increasingly difficult.