Can someone who really knows it, please explain one thing for me? I've heard different statements and don't know which one is correct.
Can Apple - in theory - unlock that phone?
Is it
a) Unless there's a defect in HSM module (Secure Enclave) that allows the key extraction (like SEM data forensics or whatever), Apple just can't unlock the phone, because it's outside of their control.
I mean, I can readily imagine a system where encryption key is completely unknown to the OS, OS doesn't have any access (or has a write-only access using public key encryption) to the user data while the phone is locked, and encryption is performed by a tamper-resistant hardware, that won't do anything without a correct secret (passphrase) and HSM will irreparably erase key material after 10 failures (which is the behavior hard-coded into silicon).
or
b) Apple technically can unlock the phone by doing an OS update with a specially crafted insecure OS, but doesn't wants to do so, because it would create a bad precedent. I.e. the HSM isn't absolute and can be forced to disclose the key (or accept brute-force attacks) by the OS.
To put it simply: in theory, can Apple defeat their own security - if they would really want to - or not?
Edit: s/TPM/HSM/g
Can Apple - in theory - unlock that phone?
Is it
a) Unless there's a defect in HSM module (Secure Enclave) that allows the key extraction (like SEM data forensics or whatever), Apple just can't unlock the phone, because it's outside of their control.
I mean, I can readily imagine a system where encryption key is completely unknown to the OS, OS doesn't have any access (or has a write-only access using public key encryption) to the user data while the phone is locked, and encryption is performed by a tamper-resistant hardware, that won't do anything without a correct secret (passphrase) and HSM will irreparably erase key material after 10 failures (which is the behavior hard-coded into silicon).
or
b) Apple technically can unlock the phone by doing an OS update with a specially crafted insecure OS, but doesn't wants to do so, because it would create a bad precedent. I.e. the HSM isn't absolute and can be forced to disclose the key (or accept brute-force attacks) by the OS.
To put it simply: in theory, can Apple defeat their own security - if they would really want to - or not?
Edit: s/TPM/HSM/g