Couldn’t the chip have a HSM that signs requests to authenticate that it’s authentic? Data is already exchanged during the USB charging handshake, this could just be one extra step.
The key might leak, which is why you could have a new key everyday that’s signed by an intermediate key and these are internet connected devices (iphones and macbooks and ipads) that could easily download a key block-list for a kilobyte everyday.
Additionally, if the device has already connected to a charger in the past but then the key gets revoked, it could continue to show it’s authentic across their devices connected to their iCloud account, much like how wifi passwords and airpods just sync across devices.
Solving the key-leaking issue is usually done by having a unique per-device key in the HSM, and having an online database that can be checked for authenticity. Then cloning a device requires pulling out an HSM, and if you do sucessfully pull the key off that it becomes suspicious that many different devices have the same key, and it can be blacklisted. This is what google uses (anticompetitively, in my mind) to force people to use geniune chromecasts.
Oh that seems like a smart way to prevent against key cloning. This seems quiet sound, although we don't live in a perfect world so I doubt we'll see this come until something bad happens like consumers losing faith in online purchases not being fakes or infamous fires resulting from "unlicensed" chargers.
The key might leak, which is why you could have a new key everyday that’s signed by an intermediate key and these are internet connected devices (iphones and macbooks and ipads) that could easily download a key block-list for a kilobyte everyday.
Additionally, if the device has already connected to a charger in the past but then the key gets revoked, it could continue to show it’s authentic across their devices connected to their iCloud account, much like how wifi passwords and airpods just sync across devices.