Wipe and rotate hardware-backed keys rather than data:
reddit.com/r/GrapheneOS/c
Factory reset or profile deletion is the right way to prevent future access to data. Clearing app data or uninstalling works on a per-app basis if the app encrypts data with the keystore like Signal.
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How do you reliably erase an app-specific hardware-backed key without blowing away the entire profile? Don't they just get wrapped with a long-lived key and then stored in normal flash?
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> How do you reliably erase an app-specific hardware-backed key without blowing away the entire profile?
As stated in the comment, the app can reliably delete hardware-backed keys. Clearing the app data or uninstalling the app will also reliably delete hardware-backed keys too.
> Don't they just get wrapped with a long-lived key and then stored in normal flash?
No, that's not at all how the StrongBox keystore works and it's an oversimplication of the traditional TEE-based keystore. Rollback resistance is a standard feature.
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StrongBox keeps keys within a dedicated secure element. From my perspective, the TEE keystore is legacy compatibility cruft, and I don't need to be concerned with devices without StrongBox support for much longer. Pixel 2 and 2 XL are legacy targets for GrapheneOS at this point.
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