4 ms·
> "The processor forwards the data to the Secure Enclave but can’t read it. It’s encrypted and authenticated with a session key that is negotiated using a share
by cocktailpeanuts 9y ago
> "The processor forwards the data to the Secure Enclave but can’t read it. It’s encrypted and authenticated with a session key that is negotiated using a shared key provisioned for each Touch ID sensor and its corresponding Secure Enclave at the factory."
If I understand this correctly, IF they're using Diffie Hellman key exchange to generate the shared session key for every chip, doesn't this mean Apple also owns the session key for every single iDevice out there and can crack into them if they wanted to?
Does this mean the "security" only protects users from men-in-the-middle, but not from Apple (or NSA if they come after them)?
- axoltl 9y agoThe long-lived secret for TouchID is generated in the SEP, using the UID of the SoC (a secret known only to the SoC) and the serial number of the respective sensor. That key is then keywrapped with a (symmetric) key known to all TouchID sensors and sent to the fingerprint sensor. It unwraps and verifies the key and burns it into fuses. That key is then used for establishing a session key in the field. The session key uses entropy from both the SEP TRNG and the TouchID TRNG. So an 'evil' Apple couldn't crack the session key unless it had been evil all along and storing the generated keywrapped blobs. In which case you're sorta screwed no matter which way you slice it.