Don't mind Mikay and GOS docs saying different things about the actual implementation of the secure wipe. One says the data is wiped, the other that it's just locked, and code agrees with one of them (I checked but don't remember off the top of my head).
No, that's completely untrue. We've provided clear, consistent and accurate information about how data is wiped. Factory reset, device admin wipe and duress PIN/password all use the same mechanisms to prevent recovering any data.
Disk encryption headers, hardware keystore keys and secure element data are each securely erased. Each of those mechanisms prevents deriving the key encryption keys which prevents ever recovering the data. Secure element data isn't stored on the SSD and prevents recovering data via an earlier image of the SSD. We implemented doing all 3 of those before reboot to recovery for device admin wipe and we used the same code for duress PIN/password wipe. We filed an Android security bug for device admin wipe and convinced them to add the hardware keystore wipe before reboot to recovery, but we still add the other 2 forms of wiping there ourselves.
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The android system uses encryption to encrypt user data. When a factory reset is performed, the secure element, the TEE, as well as the encryption headers are wiped. As destroying one of them prevents deriving the encryption key, and that secure element can reliably zero its slots, the data is effectively rendered wiped as it cannot be read without the encryption key which can no longer be derived.
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