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Reply to How does Apple certify the keys and queries of an application using App Attest?
My assumption is that this works using a "chain of trust" of some sort, i.e. the (immutable) bootloader computes a signature for the kernel before it loads it, and the kernel computes a signature for the app before it runs it, and when App Attest runs it sends these signatures to Apple. You can avoid replay attacks with nonces and timestamps and so on. There is plenty of public material available describing how to do "trusted computing" on, for example, UEFI bootloaders loading Linux; I speculate that what Apple is doing for App Attest is similar in most respects. Edited to add: the term to search for is "Remote Attestation". This will find a variety of e.g. academic papers, stack exchange answers, etc.
Topic: App & System Services SubTopic: Core OS Tags:
Feb ’23