I would not recommend that one trust a secure enclave with full disk encryption (FDE). This is what you are doing when your password/PIN/fingerprint can't contain sufficient entropy to derive a secure encryption key.
replyThe problem with low entropy security measures arises due to the fact that this low entropy is used to instruct the secure enclave (TEE) to release/use the actual high entropy key. So the key must be stored physically (eg. as voltage levels) somewhere in the device.
It's a similar story when the device is locked, on most computers the RAM isn't even encrypted so a locked computer is no major obstacle to an adversary. On devices where RAM is encrypted the encryption key is also stored somewhere - if only while the device is powered on.
RAM encryption doesn’t prevent DMA attacks and perofming a DMA attack is quite trivial as long as the machine is running. Secure enclaves do prevent those and they're a good solution. If implemented correctly, they have no downsides. I'm not referring to TPMs due to their inherent flaws; I’m talking about SoC crypto engines like those found in Apple’s M series or Intel's latest Panther Lake lineup. They prevent DMA attacks and side-channel vulnerabilities. True, I wouldn’t trust any secure enclave never to be breached – that’s an impossible promise to make even though it would require a nation-state level attack – but even this concern can be easily addressed by making the final encryption key depend on both software key derivation and the secret stored within the enclave.
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