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Can't speak for Apple Secure Enclave but Intel Embedded Security threat model explicitly states that the firmware code is not encrypted and not meant to be secr

• kogepathic 9y ago
  > Intel Embedded Security threat model explicitly states that the firmware code is not encrypted and not meant to be secret. Yep. The root of trust for IME is within silicon, so unless there's a serious flaw in their IME initialization process, it will only run code signed with the root of trust in silicon. I don't agree with the motivations behind the IME (DRM foremost), but Intel seems to have built a very secure trusted boot chain. If the IME cannot boot a trusted firmware, it will shut down the rest of the platform and you'll have a fancy brick. This has been the situation for many years and it's why you cannot buy Intel based computers without IME made after ~2008 (X200/T400). Although recently Trammell Hudson seems to have found a way to mostly disable the IME boot process on the X220. [0] ARM vendors offer a similar feature with their on-silicon root of trust. The BROM (boot ROM) on silicon will only load and execute code signed by a trusted authority. [1] [0] https://mail.coreboot.org/pipermail/coreboot/2016-November/082331.html https://mail.coreboot.org/pipermail/coreboot/2016-November/0... [1] http://rhombus-tech.net/allwinner_a10/a10_boot_process/ http://rhombus-tech.net/allwinner_a10/a10_boot_process/