I've just been told that Apple are transitioning to cleartext iBoot images. We already knew there wasn't anything naughty in iBoot (decryption keys had been published for some systems/versions, plus it's tiny anyway and doesn't have space for networking stacks or anything like that) but this means that, going forward, the entire AP (main CPU) boot chain for Apple Silicon machines is cleartext, as well as SMC and other aux firmware that was inside iBoot for practical reasons.

The only remaining encrypted component is SEPOS, but it's optional and we don't even load it yet for Asahi Linux. All other system firmware other than iBoot and the embedded SMC/PMU blobs was already plaintext.

That means that there is no place left for evil backdoors to hide in the set of mutable Apple Silicon firmware. All updates Apple publishes going forward can be audited for any weirdness. 🥳

(In practice this doesn't really change much for the already-excellent privacy posture of Apple Silicon systems running Asahi, which have always been way ahead of anything x86 since there's no Intel ME or AMD PSP equivalent full-system-access backdoor capable CPU, but it helps dispel some remaining paranoid hypotheticals about what Apple could potentially do, even if already very unlikely.)